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1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
6 help
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11 def_bool y
12 depends on !64BIT
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLKSRC_I8253
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
19 select KMAP_LOCAL
20 select MODULES_USE_ELF_REL
21 select OLD_SIGACTION
22 select ARCH_SPLIT_ARG64
23
24config X86_64
25 def_bool y
26 depends on 64BIT
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
32 select HAVE_ARCH_SOFT_DIRTY
33 select MODULES_USE_ELF_RELA
34 select NEED_DMA_MAP_STATE
35 select SWIOTLB
36 select ARCH_HAS_ELFCORE_COMPAT
37 select ZONE_DMA32
38 select EXECMEM if DYNAMIC_FTRACE
39
40config FORCE_DYNAMIC_FTRACE
41 def_bool y
42 depends on X86_32
43 depends on FUNCTION_TRACER
44 select DYNAMIC_FTRACE
45 help
46 We keep the static function tracing (!DYNAMIC_FTRACE) around
47 in order to test the non static function tracing in the
48 generic code, as other architectures still use it. But we
49 only need to keep it around for x86_64. No need to keep it
50 for x86_32. For x86_32, force DYNAMIC_FTRACE.
51#
52# Arch settings
53#
54# ( Note that options that are marked 'if X86_64' could in principle be
55# ported to 32-bit as well. )
56#
57config X86
58 def_bool y
59 #
60 # Note: keep this list sorted alphabetically
61 #
62 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
63 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
64 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
65 select ARCH_32BIT_OFF_T if X86_32
66 select ARCH_CLOCKSOURCE_INIT
67 select ARCH_CONFIGURES_CPU_MITIGATIONS
68 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
69 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
70 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
71 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
72 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
73 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
74 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
75 select ARCH_HAS_CACHE_LINE_SIZE
76 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
77 select ARCH_HAS_CPU_FINALIZE_INIT
78 select ARCH_HAS_CPU_PASID if IOMMU_SVA
79 select ARCH_HAS_CURRENT_STACK_POINTER
80 select ARCH_HAS_DEBUG_VIRTUAL
81 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
82 select ARCH_HAS_DEVMEM_IS_ALLOWED
83 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN
84 select ARCH_HAS_EARLY_DEBUG if KGDB
85 select ARCH_HAS_ELF_RANDOMIZE
86 select ARCH_HAS_FAST_MULTIPLIER
87 select ARCH_HAS_FORTIFY_SOURCE
88 select ARCH_HAS_GCOV_PROFILE_ALL
89 select ARCH_HAS_KCOV if X86_64
90 select ARCH_HAS_KERNEL_FPU_SUPPORT
91 select ARCH_HAS_MEM_ENCRYPT
92 select ARCH_HAS_MEMBARRIER_SYNC_CORE
93 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
94 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
95 select ARCH_HAS_PMEM_API if X86_64
96 select ARCH_HAS_PREEMPT_LAZY
97 select ARCH_HAS_PTE_DEVMAP if X86_64
98 select ARCH_HAS_PTE_SPECIAL
99 select ARCH_HAS_HW_PTE_YOUNG
100 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
101 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
102 select ARCH_HAS_COPY_MC if X86_64
103 select ARCH_HAS_SET_MEMORY
104 select ARCH_HAS_SET_DIRECT_MAP
105 select ARCH_HAS_STRICT_KERNEL_RWX
106 select ARCH_HAS_STRICT_MODULE_RWX
107 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
108 select ARCH_HAS_SYSCALL_WRAPPER
109 select ARCH_HAS_UBSAN
110 select ARCH_HAS_DEBUG_WX
111 select ARCH_HAS_ZONE_DMA_SET if EXPERT
112 select ARCH_HAVE_NMI_SAFE_CMPXCHG
113 select ARCH_HAVE_EXTRA_ELF_NOTES
114 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
115 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
116 select ARCH_MIGHT_HAVE_PC_PARPORT
117 select ARCH_MIGHT_HAVE_PC_SERIO
118 select ARCH_STACKWALK
119 select ARCH_SUPPORTS_ACPI
120 select ARCH_SUPPORTS_ATOMIC_RMW
121 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
122 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
123 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
124 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
125 select ARCH_SUPPORTS_CFI_CLANG if X86_64
126 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
127 select ARCH_SUPPORTS_LTO_CLANG
128 select ARCH_SUPPORTS_LTO_CLANG_THIN
129 select ARCH_SUPPORTS_RT
130 select ARCH_SUPPORTS_AUTOFDO_CLANG
131 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64
132 select ARCH_USE_BUILTIN_BSWAP
133 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
134 select ARCH_USE_MEMTEST
135 select ARCH_USE_QUEUED_RWLOCKS
136 select ARCH_USE_QUEUED_SPINLOCKS
137 select ARCH_USE_SYM_ANNOTATIONS
138 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
139 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
140 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
141 select ARCH_WANTS_NO_INSTR
142 select ARCH_WANT_GENERAL_HUGETLB
143 select ARCH_WANT_HUGE_PMD_SHARE
144 select ARCH_WANT_LD_ORPHAN_WARN
145 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
146 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
147 select ARCH_WANTS_THP_SWAP if X86_64
148 select ARCH_HAS_PARANOID_L1D_FLUSH
149 select BUILDTIME_TABLE_SORT
150 select CLKEVT_I8253
151 select CLOCKSOURCE_WATCHDOG
152 # Word-size accesses may read uninitialized data past the trailing \0
153 # in strings and cause false KMSAN reports.
154 select DCACHE_WORD_ACCESS if !KMSAN
155 select DYNAMIC_SIGFRAME
156 select EDAC_ATOMIC_SCRUB
157 select EDAC_SUPPORT
158 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
159 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST
160 select GENERIC_CLOCKEVENTS_MIN_ADJUST
161 select GENERIC_CMOS_UPDATE
162 select GENERIC_CPU_AUTOPROBE
163 select GENERIC_CPU_DEVICES
164 select GENERIC_CPU_VULNERABILITIES
165 select GENERIC_EARLY_IOREMAP
166 select GENERIC_ENTRY
167 select GENERIC_IOMAP
168 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
169 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
170 select GENERIC_IRQ_MIGRATION if SMP
171 select GENERIC_IRQ_PROBE
172 select GENERIC_IRQ_RESERVATION_MODE
173 select GENERIC_IRQ_SHOW
174 select GENERIC_PENDING_IRQ if SMP
175 select GENERIC_PTDUMP
176 select GENERIC_SMP_IDLE_THREAD
177 select GENERIC_TIME_VSYSCALL
178 select GENERIC_GETTIMEOFDAY
179 select GENERIC_VDSO_TIME_NS
180 select GENERIC_VDSO_OVERFLOW_PROTECT
181 select GUP_GET_PXX_LOW_HIGH if X86_PAE
182 select HARDIRQS_SW_RESEND
183 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
184 select HAS_IOPORT
185 select HAVE_ACPI_APEI if ACPI
186 select HAVE_ACPI_APEI_NMI if ACPI
187 select HAVE_ALIGNED_STRUCT_PAGE
188 select HAVE_ARCH_AUDITSYSCALL
189 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
190 select HAVE_ARCH_HUGE_VMALLOC if X86_64
191 select HAVE_ARCH_JUMP_LABEL
192 select HAVE_ARCH_JUMP_LABEL_RELATIVE
193 select HAVE_ARCH_KASAN if X86_64
194 select HAVE_ARCH_KASAN_VMALLOC if X86_64
195 select HAVE_ARCH_KFENCE
196 select HAVE_ARCH_KMSAN if X86_64
197 select HAVE_ARCH_KGDB
198 select HAVE_ARCH_MMAP_RND_BITS if MMU
199 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
200 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
201 select HAVE_ARCH_PREL32_RELOCATIONS
202 select HAVE_ARCH_SECCOMP_FILTER
203 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
204 select HAVE_ARCH_STACKLEAK
205 select HAVE_ARCH_TRACEHOOK
206 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
207 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
208 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
209 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
210 select HAVE_ARCH_VMAP_STACK if X86_64
211 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
212 select HAVE_ARCH_WITHIN_STACK_FRAMES
213 select HAVE_ASM_MODVERSIONS
214 select HAVE_CMPXCHG_DOUBLE
215 select HAVE_CMPXCHG_LOCAL
216 select HAVE_CONTEXT_TRACKING_USER if X86_64
217 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
218 select HAVE_C_RECORDMCOUNT
219 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
220 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
221 select HAVE_BUILDTIME_MCOUNT_SORT
222 select HAVE_DEBUG_KMEMLEAK
223 select HAVE_DMA_CONTIGUOUS
224 select HAVE_DYNAMIC_FTRACE
225 select HAVE_DYNAMIC_FTRACE_WITH_REGS
226 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
227 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
228 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
229 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
230 select HAVE_EBPF_JIT
231 select HAVE_EFFICIENT_UNALIGNED_ACCESS
232 select HAVE_EISA
233 select HAVE_EXIT_THREAD
234 select HAVE_GUP_FAST
235 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
236 select HAVE_FTRACE_MCOUNT_RECORD
237 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
238 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
239 select HAVE_FUNCTION_TRACER
240 select HAVE_GCC_PLUGINS
241 select HAVE_HW_BREAKPOINT
242 select HAVE_IOREMAP_PROT
243 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
244 select HAVE_IRQ_TIME_ACCOUNTING
245 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
246 select HAVE_KERNEL_BZIP2
247 select HAVE_KERNEL_GZIP
248 select HAVE_KERNEL_LZ4
249 select HAVE_KERNEL_LZMA
250 select HAVE_KERNEL_LZO
251 select HAVE_KERNEL_XZ
252 select HAVE_KERNEL_ZSTD
253 select HAVE_KPROBES
254 select HAVE_KPROBES_ON_FTRACE
255 select HAVE_FUNCTION_ERROR_INJECTION
256 select HAVE_KRETPROBES
257 select HAVE_RETHOOK
258 select HAVE_LIVEPATCH if X86_64
259 select HAVE_MIXED_BREAKPOINTS_REGS
260 select HAVE_MOD_ARCH_SPECIFIC
261 select HAVE_MOVE_PMD
262 select HAVE_MOVE_PUD
263 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
264 select HAVE_NMI
265 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
266 select HAVE_OBJTOOL if X86_64
267 select HAVE_OPTPROBES
268 select HAVE_PAGE_SIZE_4KB
269 select HAVE_PCSPKR_PLATFORM
270 select HAVE_PERF_EVENTS
271 select HAVE_PERF_EVENTS_NMI
272 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
273 select HAVE_PCI
274 select HAVE_PERF_REGS
275 select HAVE_PERF_USER_STACK_DUMP
276 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
277 select MMU_GATHER_MERGE_VMAS
278 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
279 select HAVE_REGS_AND_STACK_ACCESS_API
280 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
281 select HAVE_FUNCTION_ARG_ACCESS_API
282 select HAVE_SETUP_PER_CPU_AREA
283 select HAVE_SOFTIRQ_ON_OWN_STACK
284 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
285 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
286 select HAVE_STATIC_CALL
287 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
288 select HAVE_PREEMPT_DYNAMIC_CALL
289 select HAVE_RSEQ
290 select HAVE_RUST if X86_64
291 select HAVE_SYSCALL_TRACEPOINTS
292 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
293 select HAVE_UNSTABLE_SCHED_CLOCK
294 select HAVE_USER_RETURN_NOTIFIER
295 select HAVE_GENERIC_VDSO
296 select VDSO_GETRANDOM if X86_64
297 select HOTPLUG_PARALLEL if SMP && X86_64
298 select HOTPLUG_SMT if SMP
299 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
300 select IRQ_FORCED_THREADING
301 select LOCK_MM_AND_FIND_VMA
302 select NEED_PER_CPU_EMBED_FIRST_CHUNK
303 select NEED_PER_CPU_PAGE_FIRST_CHUNK
304 select NEED_SG_DMA_LENGTH
305 select NUMA_MEMBLKS if NUMA
306 select PCI_DOMAINS if PCI
307 select PCI_LOCKLESS_CONFIG if PCI
308 select PERF_EVENTS
309 select RTC_LIB
310 select RTC_MC146818_LIB
311 select SPARSE_IRQ
312 select SYSCTL_EXCEPTION_TRACE
313 select THREAD_INFO_IN_TASK
314 select TRACE_IRQFLAGS_SUPPORT
315 select TRACE_IRQFLAGS_NMI_SUPPORT
316 select USER_STACKTRACE_SUPPORT
317 select HAVE_ARCH_KCSAN if X86_64
318 select PROC_PID_ARCH_STATUS if PROC_FS
319 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
320 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
321 select FUNCTION_ALIGNMENT_4B
322 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
323 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
324
325config INSTRUCTION_DECODER
326 def_bool y
327 depends on KPROBES || PERF_EVENTS || UPROBES
328
329config OUTPUT_FORMAT
330 string
331 default "elf32-i386" if X86_32
332 default "elf64-x86-64" if X86_64
333
334config LOCKDEP_SUPPORT
335 def_bool y
336
337config STACKTRACE_SUPPORT
338 def_bool y
339
340config MMU
341 def_bool y
342
343config ARCH_MMAP_RND_BITS_MIN
344 default 28 if 64BIT
345 default 8
346
347config ARCH_MMAP_RND_BITS_MAX
348 default 32 if 64BIT
349 default 16
350
351config ARCH_MMAP_RND_COMPAT_BITS_MIN
352 default 8
353
354config ARCH_MMAP_RND_COMPAT_BITS_MAX
355 default 16
356
357config SBUS
358 bool
359
360config GENERIC_ISA_DMA
361 def_bool y
362 depends on ISA_DMA_API
363
364config GENERIC_CSUM
365 bool
366 default y if KMSAN || KASAN
367
368config GENERIC_BUG
369 def_bool y
370 depends on BUG
371 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
372
373config GENERIC_BUG_RELATIVE_POINTERS
374 bool
375
376config ARCH_MAY_HAVE_PC_FDC
377 def_bool y
378 depends on ISA_DMA_API
379
380config GENERIC_CALIBRATE_DELAY
381 def_bool y
382
383config ARCH_HAS_CPU_RELAX
384 def_bool y
385
386config ARCH_HIBERNATION_POSSIBLE
387 def_bool y
388
389config ARCH_SUSPEND_POSSIBLE
390 def_bool y
391
392config AUDIT_ARCH
393 def_bool y if X86_64
394
395config KASAN_SHADOW_OFFSET
396 hex
397 depends on KASAN
398 default 0xdffffc0000000000
399
400config HAVE_INTEL_TXT
401 def_bool y
402 depends on INTEL_IOMMU && ACPI
403
404config X86_64_SMP
405 def_bool y
406 depends on X86_64 && SMP
407
408config ARCH_SUPPORTS_UPROBES
409 def_bool y
410
411config FIX_EARLYCON_MEM
412 def_bool y
413
414config DYNAMIC_PHYSICAL_MASK
415 bool
416
417config PGTABLE_LEVELS
418 int
419 default 5 if X86_5LEVEL
420 default 4 if X86_64
421 default 3 if X86_PAE
422 default 2
423
424config CC_HAS_SANE_STACKPROTECTOR
425 bool
426 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
427 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
428 help
429 We have to make sure stack protector is unconditionally disabled if
430 the compiler produces broken code or if it does not let us control
431 the segment on 32-bit kernels.
432
433menu "Processor type and features"
434
435config SMP
436 bool "Symmetric multi-processing support"
437 help
438 This enables support for systems with more than one CPU. If you have
439 a system with only one CPU, say N. If you have a system with more
440 than one CPU, say Y.
441
442 If you say N here, the kernel will run on uni- and multiprocessor
443 machines, but will use only one CPU of a multiprocessor machine. If
444 you say Y here, the kernel will run on many, but not all,
445 uniprocessor machines. On a uniprocessor machine, the kernel
446 will run faster if you say N here.
447
448 Note that if you say Y here and choose architecture "586" or
449 "Pentium" under "Processor family", the kernel will not work on 486
450 architectures. Similarly, multiprocessor kernels for the "PPro"
451 architecture may not work on all Pentium based boards.
452
453 People using multiprocessor machines who say Y here should also say
454 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
455 Management" code will be disabled if you say Y here.
456
457 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
458 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
459 <http://www.tldp.org/docs.html#howto>.
460
461 If you don't know what to do here, say N.
462
463config X86_X2APIC
464 bool "Support x2apic"
465 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
466 help
467 This enables x2apic support on CPUs that have this feature.
468
469 This allows 32-bit apic IDs (so it can support very large systems),
470 and accesses the local apic via MSRs not via mmio.
471
472 Some Intel systems circa 2022 and later are locked into x2APIC mode
473 and can not fall back to the legacy APIC modes if SGX or TDX are
474 enabled in the BIOS. They will boot with very reduced functionality
475 without enabling this option.
476
477 If you don't know what to do here, say N.
478
479config X86_POSTED_MSI
480 bool "Enable MSI and MSI-x delivery by posted interrupts"
481 depends on X86_64 && IRQ_REMAP
482 help
483 This enables MSIs that are under interrupt remapping to be delivered as
484 posted interrupts to the host kernel. Interrupt throughput can
485 potentially be improved by coalescing CPU notifications during high
486 frequency bursts.
487
488 If you don't know what to do here, say N.
489
490config X86_MPPARSE
491 bool "Enable MPS table" if ACPI
492 default y
493 depends on X86_LOCAL_APIC
494 help
495 For old smp systems that do not have proper acpi support. Newer systems
496 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
497
498config X86_CPU_RESCTRL
499 bool "x86 CPU resource control support"
500 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
501 select KERNFS
502 select PROC_CPU_RESCTRL if PROC_FS
503 help
504 Enable x86 CPU resource control support.
505
506 Provide support for the allocation and monitoring of system resources
507 usage by the CPU.
508
509 Intel calls this Intel Resource Director Technology
510 (Intel(R) RDT). More information about RDT can be found in the
511 Intel x86 Architecture Software Developer Manual.
512
513 AMD calls this AMD Platform Quality of Service (AMD QoS).
514 More information about AMD QoS can be found in the AMD64 Technology
515 Platform Quality of Service Extensions manual.
516
517 Say N if unsure.
518
519config X86_FRED
520 bool "Flexible Return and Event Delivery"
521 depends on X86_64
522 help
523 When enabled, try to use Flexible Return and Event Delivery
524 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
525 ring transitions and exception/interrupt handling if the
526 system supports it.
527
528config X86_BIGSMP
529 bool "Support for big SMP systems with more than 8 CPUs"
530 depends on SMP && X86_32
531 help
532 This option is needed for the systems that have more than 8 CPUs.
533
534config X86_EXTENDED_PLATFORM
535 bool "Support for extended (non-PC) x86 platforms"
536 default y
537 help
538 If you disable this option then the kernel will only support
539 standard PC platforms. (which covers the vast majority of
540 systems out there.)
541
542 If you enable this option then you'll be able to select support
543 for the following non-PC x86 platforms, depending on the value of
544 CONFIG_64BIT.
545
546 32-bit platforms (CONFIG_64BIT=n):
547 Goldfish (Android emulator)
548 AMD Elan
549 RDC R-321x SoC
550 SGI 320/540 (Visual Workstation)
551 STA2X11-based (e.g. Northville)
552 Moorestown MID devices
553
554 64-bit platforms (CONFIG_64BIT=y):
555 Numascale NumaChip
556 ScaleMP vSMP
557 SGI Ultraviolet
558
559 If you have one of these systems, or if you want to build a
560 generic distribution kernel, say Y here - otherwise say N.
561
562# This is an alphabetically sorted list of 64 bit extended platforms
563# Please maintain the alphabetic order if and when there are additions
564config X86_NUMACHIP
565 bool "Numascale NumaChip"
566 depends on X86_64
567 depends on X86_EXTENDED_PLATFORM
568 depends on NUMA
569 depends on SMP
570 depends on X86_X2APIC
571 depends on PCI_MMCONFIG
572 help
573 Adds support for Numascale NumaChip large-SMP systems. Needed to
574 enable more than ~168 cores.
575 If you don't have one of these, you should say N here.
576
577config X86_VSMP
578 bool "ScaleMP vSMP"
579 select HYPERVISOR_GUEST
580 select PARAVIRT
581 depends on X86_64 && PCI
582 depends on X86_EXTENDED_PLATFORM
583 depends on SMP
584 help
585 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
586 supposed to run on these EM64T-based machines. Only choose this option
587 if you have one of these machines.
588
589config X86_UV
590 bool "SGI Ultraviolet"
591 depends on X86_64
592 depends on X86_EXTENDED_PLATFORM
593 depends on NUMA
594 depends on EFI
595 depends on KEXEC_CORE
596 depends on X86_X2APIC
597 depends on PCI
598 help
599 This option is needed in order to support SGI Ultraviolet systems.
600 If you don't have one of these, you should say N here.
601
602# Following is an alphabetically sorted list of 32 bit extended platforms
603# Please maintain the alphabetic order if and when there are additions
604
605config X86_GOLDFISH
606 bool "Goldfish (Virtual Platform)"
607 depends on X86_EXTENDED_PLATFORM
608 help
609 Enable support for the Goldfish virtual platform used primarily
610 for Android development. Unless you are building for the Android
611 Goldfish emulator say N here.
612
613config X86_INTEL_CE
614 bool "CE4100 TV platform"
615 depends on PCI
616 depends on PCI_GODIRECT
617 depends on X86_IO_APIC
618 depends on X86_32
619 depends on X86_EXTENDED_PLATFORM
620 select X86_REBOOTFIXUPS
621 select OF
622 select OF_EARLY_FLATTREE
623 help
624 Select for the Intel CE media processor (CE4100) SOC.
625 This option compiles in support for the CE4100 SOC for settop
626 boxes and media devices.
627
628config X86_INTEL_MID
629 bool "Intel MID platform support"
630 depends on X86_EXTENDED_PLATFORM
631 depends on X86_PLATFORM_DEVICES
632 depends on PCI
633 depends on X86_64 || (PCI_GOANY && X86_32)
634 depends on X86_IO_APIC
635 select I2C
636 select DW_APB_TIMER
637 select INTEL_SCU_PCI
638 help
639 Select to build a kernel capable of supporting Intel MID (Mobile
640 Internet Device) platform systems which do not have the PCI legacy
641 interfaces. If you are building for a PC class system say N here.
642
643 Intel MID platforms are based on an Intel processor and chipset which
644 consume less power than most of the x86 derivatives.
645
646config X86_INTEL_QUARK
647 bool "Intel Quark platform support"
648 depends on X86_32
649 depends on X86_EXTENDED_PLATFORM
650 depends on X86_PLATFORM_DEVICES
651 depends on X86_TSC
652 depends on PCI
653 depends on PCI_GOANY
654 depends on X86_IO_APIC
655 select IOSF_MBI
656 select INTEL_IMR
657 select COMMON_CLK
658 help
659 Select to include support for Quark X1000 SoC.
660 Say Y here if you have a Quark based system such as the Arduino
661 compatible Intel Galileo.
662
663config X86_INTEL_LPSS
664 bool "Intel Low Power Subsystem Support"
665 depends on X86 && ACPI && PCI
666 select COMMON_CLK
667 select PINCTRL
668 select IOSF_MBI
669 help
670 Select to build support for Intel Low Power Subsystem such as
671 found on Intel Lynxpoint PCH. Selecting this option enables
672 things like clock tree (common clock framework) and pincontrol
673 which are needed by the LPSS peripheral drivers.
674
675config X86_AMD_PLATFORM_DEVICE
676 bool "AMD ACPI2Platform devices support"
677 depends on ACPI
678 select COMMON_CLK
679 select PINCTRL
680 help
681 Select to interpret AMD specific ACPI device to platform device
682 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
683 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
684 implemented under PINCTRL subsystem.
685
686config IOSF_MBI
687 tristate "Intel SoC IOSF Sideband support for SoC platforms"
688 depends on PCI
689 help
690 This option enables sideband register access support for Intel SoC
691 platforms. On these platforms the IOSF sideband is used in lieu of
692 MSR's for some register accesses, mostly but not limited to thermal
693 and power. Drivers may query the availability of this device to
694 determine if they need the sideband in order to work on these
695 platforms. The sideband is available on the following SoC products.
696 This list is not meant to be exclusive.
697 - BayTrail
698 - Braswell
699 - Quark
700
701 You should say Y if you are running a kernel on one of these SoC's.
702
703config IOSF_MBI_DEBUG
704 bool "Enable IOSF sideband access through debugfs"
705 depends on IOSF_MBI && DEBUG_FS
706 help
707 Select this option to expose the IOSF sideband access registers (MCR,
708 MDR, MCRX) through debugfs to write and read register information from
709 different units on the SoC. This is most useful for obtaining device
710 state information for debug and analysis. As this is a general access
711 mechanism, users of this option would have specific knowledge of the
712 device they want to access.
713
714 If you don't require the option or are in doubt, say N.
715
716config X86_RDC321X
717 bool "RDC R-321x SoC"
718 depends on X86_32
719 depends on X86_EXTENDED_PLATFORM
720 select M486
721 select X86_REBOOTFIXUPS
722 help
723 This option is needed for RDC R-321x system-on-chip, also known
724 as R-8610-(G).
725 If you don't have one of these chips, you should say N here.
726
727config X86_32_NON_STANDARD
728 bool "Support non-standard 32-bit SMP architectures"
729 depends on X86_32 && SMP
730 depends on X86_EXTENDED_PLATFORM
731 help
732 This option compiles in the bigsmp and STA2X11 default
733 subarchitectures. It is intended for a generic binary
734 kernel. If you select them all, kernel will probe it one by
735 one and will fallback to default.
736
737# Alphabetically sorted list of Non standard 32 bit platforms
738
739config X86_SUPPORTS_MEMORY_FAILURE
740 def_bool y
741 # MCE code calls memory_failure():
742 depends on X86_MCE
743 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
744 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
745 depends on X86_64 || !SPARSEMEM
746 select ARCH_SUPPORTS_MEMORY_FAILURE
747
748config STA2X11
749 bool "STA2X11 Companion Chip Support"
750 depends on X86_32_NON_STANDARD && PCI
751 select SWIOTLB
752 select MFD_STA2X11
753 select GPIOLIB
754 help
755 This adds support for boards based on the STA2X11 IO-Hub,
756 a.k.a. "ConneXt". The chip is used in place of the standard
757 PC chipset, so all "standard" peripherals are missing. If this
758 option is selected the kernel will still be able to boot on
759 standard PC machines.
760
761config X86_32_IRIS
762 tristate "Eurobraille/Iris poweroff module"
763 depends on X86_32
764 help
765 The Iris machines from EuroBraille do not have APM or ACPI support
766 to shut themselves down properly. A special I/O sequence is
767 needed to do so, which is what this module does at
768 kernel shutdown.
769
770 This is only for Iris machines from EuroBraille.
771
772 If unused, say N.
773
774config SCHED_OMIT_FRAME_POINTER
775 def_bool y
776 prompt "Single-depth WCHAN output"
777 depends on X86
778 help
779 Calculate simpler /proc/<PID>/wchan values. If this option
780 is disabled then wchan values will recurse back to the
781 caller function. This provides more accurate wchan values,
782 at the expense of slightly more scheduling overhead.
783
784 If in doubt, say "Y".
785
786menuconfig HYPERVISOR_GUEST
787 bool "Linux guest support"
788 help
789 Say Y here to enable options for running Linux under various hyper-
790 visors. This option enables basic hypervisor detection and platform
791 setup.
792
793 If you say N, all options in this submenu will be skipped and
794 disabled, and Linux guest support won't be built in.
795
796if HYPERVISOR_GUEST
797
798config PARAVIRT
799 bool "Enable paravirtualization code"
800 depends on HAVE_STATIC_CALL
801 help
802 This changes the kernel so it can modify itself when it is run
803 under a hypervisor, potentially improving performance significantly
804 over full virtualization. However, when run without a hypervisor
805 the kernel is theoretically slower and slightly larger.
806
807config PARAVIRT_XXL
808 bool
809
810config PARAVIRT_DEBUG
811 bool "paravirt-ops debugging"
812 depends on PARAVIRT && DEBUG_KERNEL
813 help
814 Enable to debug paravirt_ops internals. Specifically, BUG if
815 a paravirt_op is missing when it is called.
816
817config PARAVIRT_SPINLOCKS
818 bool "Paravirtualization layer for spinlocks"
819 depends on PARAVIRT && SMP
820 help
821 Paravirtualized spinlocks allow a pvops backend to replace the
822 spinlock implementation with something virtualization-friendly
823 (for example, block the virtual CPU rather than spinning).
824
825 It has a minimal impact on native kernels and gives a nice performance
826 benefit on paravirtualized KVM / Xen kernels.
827
828 If you are unsure how to answer this question, answer Y.
829
830config X86_HV_CALLBACK_VECTOR
831 def_bool n
832
833source "arch/x86/xen/Kconfig"
834
835config KVM_GUEST
836 bool "KVM Guest support (including kvmclock)"
837 depends on PARAVIRT
838 select PARAVIRT_CLOCK
839 select ARCH_CPUIDLE_HALTPOLL
840 select X86_HV_CALLBACK_VECTOR
841 default y
842 help
843 This option enables various optimizations for running under the KVM
844 hypervisor. It includes a paravirtualized clock, so that instead
845 of relying on a PIT (or probably other) emulation by the
846 underlying device model, the host provides the guest with
847 timing infrastructure such as time of day, and system time
848
849config ARCH_CPUIDLE_HALTPOLL
850 def_bool n
851 prompt "Disable host haltpoll when loading haltpoll driver"
852 help
853 If virtualized under KVM, disable host haltpoll.
854
855config PVH
856 bool "Support for running PVH guests"
857 help
858 This option enables the PVH entry point for guest virtual machines
859 as specified in the x86/HVM direct boot ABI.
860
861config PARAVIRT_TIME_ACCOUNTING
862 bool "Paravirtual steal time accounting"
863 depends on PARAVIRT
864 help
865 Select this option to enable fine granularity task steal time
866 accounting. Time spent executing other tasks in parallel with
867 the current vCPU is discounted from the vCPU power. To account for
868 that, there can be a small performance impact.
869
870 If in doubt, say N here.
871
872config PARAVIRT_CLOCK
873 bool
874
875config JAILHOUSE_GUEST
876 bool "Jailhouse non-root cell support"
877 depends on X86_64 && PCI
878 select X86_PM_TIMER
879 help
880 This option allows to run Linux as guest in a Jailhouse non-root
881 cell. You can leave this option disabled if you only want to start
882 Jailhouse and run Linux afterwards in the root cell.
883
884config ACRN_GUEST
885 bool "ACRN Guest support"
886 depends on X86_64
887 select X86_HV_CALLBACK_VECTOR
888 help
889 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
890 a flexible, lightweight reference open-source hypervisor, built with
891 real-time and safety-criticality in mind. It is built for embedded
892 IOT with small footprint and real-time features. More details can be
893 found in https://projectacrn.org/.
894
895config INTEL_TDX_GUEST
896 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
897 depends on X86_64 && CPU_SUP_INTEL
898 depends on X86_X2APIC
899 depends on EFI_STUB
900 select ARCH_HAS_CC_PLATFORM
901 select X86_MEM_ENCRYPT
902 select X86_MCE
903 select UNACCEPTED_MEMORY
904 help
905 Support running as a guest under Intel TDX. Without this support,
906 the guest kernel can not boot or run under TDX.
907 TDX includes memory encryption and integrity capabilities
908 which protect the confidentiality and integrity of guest
909 memory contents and CPU state. TDX guests are protected from
910 some attacks from the VMM.
911
912endif # HYPERVISOR_GUEST
913
914source "arch/x86/Kconfig.cpu"
915
916config HPET_TIMER
917 def_bool X86_64
918 prompt "HPET Timer Support" if X86_32
919 help
920 Use the IA-PC HPET (High Precision Event Timer) to manage
921 time in preference to the PIT and RTC, if a HPET is
922 present.
923 HPET is the next generation timer replacing legacy 8254s.
924 The HPET provides a stable time base on SMP
925 systems, unlike the TSC, but it is more expensive to access,
926 as it is off-chip. The interface used is documented
927 in the HPET spec, revision 1.
928
929 You can safely choose Y here. However, HPET will only be
930 activated if the platform and the BIOS support this feature.
931 Otherwise the 8254 will be used for timing services.
932
933 Choose N to continue using the legacy 8254 timer.
934
935config HPET_EMULATE_RTC
936 def_bool y
937 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
938
939# Mark as expert because too many people got it wrong.
940# The code disables itself when not needed.
941config DMI
942 default y
943 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
944 bool "Enable DMI scanning" if EXPERT
945 help
946 Enabled scanning of DMI to identify machine quirks. Say Y
947 here unless you have verified that your setup is not
948 affected by entries in the DMI blacklist. Required by PNP
949 BIOS code.
950
951config GART_IOMMU
952 bool "Old AMD GART IOMMU support"
953 select IOMMU_HELPER
954 select SWIOTLB
955 depends on X86_64 && PCI && AMD_NB
956 help
957 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
958 GART based hardware IOMMUs.
959
960 The GART supports full DMA access for devices with 32-bit access
961 limitations, on systems with more than 3 GB. This is usually needed
962 for USB, sound, many IDE/SATA chipsets and some other devices.
963
964 Newer systems typically have a modern AMD IOMMU, supported via
965 the CONFIG_AMD_IOMMU=y config option.
966
967 In normal configurations this driver is only active when needed:
968 there's more than 3 GB of memory and the system contains a
969 32-bit limited device.
970
971 If unsure, say Y.
972
973config BOOT_VESA_SUPPORT
974 bool
975 help
976 If true, at least one selected framebuffer driver can take advantage
977 of VESA video modes set at an early boot stage via the vga= parameter.
978
979config MAXSMP
980 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
981 depends on X86_64 && SMP && DEBUG_KERNEL
982 select CPUMASK_OFFSTACK
983 help
984 Enable maximum number of CPUS and NUMA Nodes for this architecture.
985 If unsure, say N.
986
987#
988# The maximum number of CPUs supported:
989#
990# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
991# and which can be configured interactively in the
992# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
993#
994# The ranges are different on 32-bit and 64-bit kernels, depending on
995# hardware capabilities and scalability features of the kernel.
996#
997# ( If MAXSMP is enabled we just use the highest possible value and disable
998# interactive configuration. )
999#
1000
1001config NR_CPUS_RANGE_BEGIN
1002 int
1003 default NR_CPUS_RANGE_END if MAXSMP
1004 default 1 if !SMP
1005 default 2
1006
1007config NR_CPUS_RANGE_END
1008 int
1009 depends on X86_32
1010 default 64 if SMP && X86_BIGSMP
1011 default 8 if SMP && !X86_BIGSMP
1012 default 1 if !SMP
1013
1014config NR_CPUS_RANGE_END
1015 int
1016 depends on X86_64
1017 default 8192 if SMP && CPUMASK_OFFSTACK
1018 default 512 if SMP && !CPUMASK_OFFSTACK
1019 default 1 if !SMP
1020
1021config NR_CPUS_DEFAULT
1022 int
1023 depends on X86_32
1024 default 32 if X86_BIGSMP
1025 default 8 if SMP
1026 default 1 if !SMP
1027
1028config NR_CPUS_DEFAULT
1029 int
1030 depends on X86_64
1031 default 8192 if MAXSMP
1032 default 64 if SMP
1033 default 1 if !SMP
1034
1035config NR_CPUS
1036 int "Maximum number of CPUs" if SMP && !MAXSMP
1037 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1038 default NR_CPUS_DEFAULT
1039 help
1040 This allows you to specify the maximum number of CPUs which this
1041 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1042 supported value is 8192, otherwise the maximum value is 512. The
1043 minimum value which makes sense is 2.
1044
1045 This is purely to save memory: each supported CPU adds about 8KB
1046 to the kernel image.
1047
1048config SCHED_CLUSTER
1049 bool "Cluster scheduler support"
1050 depends on SMP
1051 default y
1052 help
1053 Cluster scheduler support improves the CPU scheduler's decision
1054 making when dealing with machines that have clusters of CPUs.
1055 Cluster usually means a couple of CPUs which are placed closely
1056 by sharing mid-level caches, last-level cache tags or internal
1057 busses.
1058
1059config SCHED_SMT
1060 def_bool y if SMP
1061
1062config SCHED_MC
1063 def_bool y
1064 prompt "Multi-core scheduler support"
1065 depends on SMP
1066 help
1067 Multi-core scheduler support improves the CPU scheduler's decision
1068 making when dealing with multi-core CPU chips at a cost of slightly
1069 increased overhead in some places. If unsure say N here.
1070
1071config SCHED_MC_PRIO
1072 bool "CPU core priorities scheduler support"
1073 depends on SCHED_MC
1074 select X86_INTEL_PSTATE if CPU_SUP_INTEL
1075 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1076 select CPU_FREQ
1077 default y
1078 help
1079 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1080 core ordering determined at manufacturing time, which allows
1081 certain cores to reach higher turbo frequencies (when running
1082 single threaded workloads) than others.
1083
1084 Enabling this kernel feature teaches the scheduler about
1085 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1086 scheduler's CPU selection logic accordingly, so that higher
1087 overall system performance can be achieved.
1088
1089 This feature will have no effect on CPUs without this feature.
1090
1091 If unsure say Y here.
1092
1093config UP_LATE_INIT
1094 def_bool y
1095 depends on !SMP && X86_LOCAL_APIC
1096
1097config X86_UP_APIC
1098 bool "Local APIC support on uniprocessors" if !PCI_MSI
1099 default PCI_MSI
1100 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1101 help
1102 A local APIC (Advanced Programmable Interrupt Controller) is an
1103 integrated interrupt controller in the CPU. If you have a single-CPU
1104 system which has a processor with a local APIC, you can say Y here to
1105 enable and use it. If you say Y here even though your machine doesn't
1106 have a local APIC, then the kernel will still run with no slowdown at
1107 all. The local APIC supports CPU-generated self-interrupts (timer,
1108 performance counters), and the NMI watchdog which detects hard
1109 lockups.
1110
1111config X86_UP_IOAPIC
1112 bool "IO-APIC support on uniprocessors"
1113 depends on X86_UP_APIC
1114 help
1115 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1116 SMP-capable replacement for PC-style interrupt controllers. Most
1117 SMP systems and many recent uniprocessor systems have one.
1118
1119 If you have a single-CPU system with an IO-APIC, you can say Y here
1120 to use it. If you say Y here even though your machine doesn't have
1121 an IO-APIC, then the kernel will still run with no slowdown at all.
1122
1123config X86_LOCAL_APIC
1124 def_bool y
1125 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1126 select IRQ_DOMAIN_HIERARCHY
1127
1128config ACPI_MADT_WAKEUP
1129 def_bool y
1130 depends on X86_64
1131 depends on ACPI
1132 depends on SMP
1133 depends on X86_LOCAL_APIC
1134
1135config X86_IO_APIC
1136 def_bool y
1137 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1138
1139config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1140 bool "Reroute for broken boot IRQs"
1141 depends on X86_IO_APIC
1142 help
1143 This option enables a workaround that fixes a source of
1144 spurious interrupts. This is recommended when threaded
1145 interrupt handling is used on systems where the generation of
1146 superfluous "boot interrupts" cannot be disabled.
1147
1148 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1149 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1150 kernel does during interrupt handling). On chipsets where this
1151 boot IRQ generation cannot be disabled, this workaround keeps
1152 the original IRQ line masked so that only the equivalent "boot
1153 IRQ" is delivered to the CPUs. The workaround also tells the
1154 kernel to set up the IRQ handler on the boot IRQ line. In this
1155 way only one interrupt is delivered to the kernel. Otherwise
1156 the spurious second interrupt may cause the kernel to bring
1157 down (vital) interrupt lines.
1158
1159 Only affects "broken" chipsets. Interrupt sharing may be
1160 increased on these systems.
1161
1162config X86_MCE
1163 bool "Machine Check / overheating reporting"
1164 select GENERIC_ALLOCATOR
1165 default y
1166 help
1167 Machine Check support allows the processor to notify the
1168 kernel if it detects a problem (e.g. overheating, data corruption).
1169 The action the kernel takes depends on the severity of the problem,
1170 ranging from warning messages to halting the machine.
1171
1172config X86_MCELOG_LEGACY
1173 bool "Support for deprecated /dev/mcelog character device"
1174 depends on X86_MCE
1175 help
1176 Enable support for /dev/mcelog which is needed by the old mcelog
1177 userspace logging daemon. Consider switching to the new generation
1178 rasdaemon solution.
1179
1180config X86_MCE_INTEL
1181 def_bool y
1182 prompt "Intel MCE features"
1183 depends on X86_MCE && X86_LOCAL_APIC
1184 help
1185 Additional support for intel specific MCE features such as
1186 the thermal monitor.
1187
1188config X86_MCE_AMD
1189 def_bool y
1190 prompt "AMD MCE features"
1191 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1192 help
1193 Additional support for AMD specific MCE features such as
1194 the DRAM Error Threshold.
1195
1196config X86_ANCIENT_MCE
1197 bool "Support for old Pentium 5 / WinChip machine checks"
1198 depends on X86_32 && X86_MCE
1199 help
1200 Include support for machine check handling on old Pentium 5 or WinChip
1201 systems. These typically need to be enabled explicitly on the command
1202 line.
1203
1204config X86_MCE_THRESHOLD
1205 depends on X86_MCE_AMD || X86_MCE_INTEL
1206 def_bool y
1207
1208config X86_MCE_INJECT
1209 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1210 tristate "Machine check injector support"
1211 help
1212 Provide support for injecting machine checks for testing purposes.
1213 If you don't know what a machine check is and you don't do kernel
1214 QA it is safe to say n.
1215
1216source "arch/x86/events/Kconfig"
1217
1218config X86_LEGACY_VM86
1219 bool "Legacy VM86 support"
1220 depends on X86_32
1221 help
1222 This option allows user programs to put the CPU into V8086
1223 mode, which is an 80286-era approximation of 16-bit real mode.
1224
1225 Some very old versions of X and/or vbetool require this option
1226 for user mode setting. Similarly, DOSEMU will use it if
1227 available to accelerate real mode DOS programs. However, any
1228 recent version of DOSEMU, X, or vbetool should be fully
1229 functional even without kernel VM86 support, as they will all
1230 fall back to software emulation. Nevertheless, if you are using
1231 a 16-bit DOS program where 16-bit performance matters, vm86
1232 mode might be faster than emulation and you might want to
1233 enable this option.
1234
1235 Note that any app that works on a 64-bit kernel is unlikely to
1236 need this option, as 64-bit kernels don't, and can't, support
1237 V8086 mode. This option is also unrelated to 16-bit protected
1238 mode and is not needed to run most 16-bit programs under Wine.
1239
1240 Enabling this option increases the complexity of the kernel
1241 and slows down exception handling a tiny bit.
1242
1243 If unsure, say N here.
1244
1245config VM86
1246 bool
1247 default X86_LEGACY_VM86
1248
1249config X86_16BIT
1250 bool "Enable support for 16-bit segments" if EXPERT
1251 default y
1252 depends on MODIFY_LDT_SYSCALL
1253 help
1254 This option is required by programs like Wine to run 16-bit
1255 protected mode legacy code on x86 processors. Disabling
1256 this option saves about 300 bytes on i386, or around 6K text
1257 plus 16K runtime memory on x86-64,
1258
1259config X86_ESPFIX32
1260 def_bool y
1261 depends on X86_16BIT && X86_32
1262
1263config X86_ESPFIX64
1264 def_bool y
1265 depends on X86_16BIT && X86_64
1266
1267config X86_VSYSCALL_EMULATION
1268 bool "Enable vsyscall emulation" if EXPERT
1269 default y
1270 depends on X86_64
1271 help
1272 This enables emulation of the legacy vsyscall page. Disabling
1273 it is roughly equivalent to booting with vsyscall=none, except
1274 that it will also disable the helpful warning if a program
1275 tries to use a vsyscall. With this option set to N, offending
1276 programs will just segfault, citing addresses of the form
1277 0xffffffffff600?00.
1278
1279 This option is required by many programs built before 2013, and
1280 care should be used even with newer programs if set to N.
1281
1282 Disabling this option saves about 7K of kernel size and
1283 possibly 4K of additional runtime pagetable memory.
1284
1285config X86_IOPL_IOPERM
1286 bool "IOPERM and IOPL Emulation"
1287 default y
1288 help
1289 This enables the ioperm() and iopl() syscalls which are necessary
1290 for legacy applications.
1291
1292 Legacy IOPL support is an overbroad mechanism which allows user
1293 space aside of accessing all 65536 I/O ports also to disable
1294 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1295 capabilities and permission from potentially active security
1296 modules.
1297
1298 The emulation restricts the functionality of the syscall to
1299 only allowing the full range I/O port access, but prevents the
1300 ability to disable interrupts from user space which would be
1301 granted if the hardware IOPL mechanism would be used.
1302
1303config TOSHIBA
1304 tristate "Toshiba Laptop support"
1305 depends on X86_32
1306 help
1307 This adds a driver to safely access the System Management Mode of
1308 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1309 not work on models with a Phoenix BIOS. The System Management Mode
1310 is used to set the BIOS and power saving options on Toshiba portables.
1311
1312 For information on utilities to make use of this driver see the
1313 Toshiba Linux utilities web site at:
1314 <http://www.buzzard.org.uk/toshiba/>.
1315
1316 Say Y if you intend to run this kernel on a Toshiba portable.
1317 Say N otherwise.
1318
1319config X86_REBOOTFIXUPS
1320 bool "Enable X86 board specific fixups for reboot"
1321 depends on X86_32
1322 help
1323 This enables chipset and/or board specific fixups to be done
1324 in order to get reboot to work correctly. This is only needed on
1325 some combinations of hardware and BIOS. The symptom, for which
1326 this config is intended, is when reboot ends with a stalled/hung
1327 system.
1328
1329 Currently, the only fixup is for the Geode machines using
1330 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1331
1332 Say Y if you want to enable the fixup. Currently, it's safe to
1333 enable this option even if you don't need it.
1334 Say N otherwise.
1335
1336config MICROCODE
1337 def_bool y
1338 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1339 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD
1340
1341config MICROCODE_INITRD32
1342 def_bool y
1343 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1344
1345config MICROCODE_LATE_LOADING
1346 bool "Late microcode loading (DANGEROUS)"
1347 default n
1348 depends on MICROCODE && SMP
1349 help
1350 Loading microcode late, when the system is up and executing instructions
1351 is a tricky business and should be avoided if possible. Just the sequence
1352 of synchronizing all cores and SMT threads is one fragile dance which does
1353 not guarantee that cores might not softlock after the loading. Therefore,
1354 use this at your own risk. Late loading taints the kernel unless the
1355 microcode header indicates that it is safe for late loading via the
1356 minimal revision check. This minimal revision check can be enforced on
1357 the kernel command line with "microcode.minrev=Y".
1358
1359config MICROCODE_LATE_FORCE_MINREV
1360 bool "Enforce late microcode loading minimal revision check"
1361 default n
1362 depends on MICROCODE_LATE_LOADING
1363 help
1364 To prevent that users load microcode late which modifies already
1365 in use features, newer microcode patches have a minimum revision field
1366 in the microcode header, which tells the kernel which minimum
1367 revision must be active in the CPU to safely load that new microcode
1368 late into the running system. If disabled the check will not
1369 be enforced but the kernel will be tainted when the minimal
1370 revision check fails.
1371
1372 This minimal revision check can also be controlled via the
1373 "microcode.minrev" parameter on the kernel command line.
1374
1375 If unsure say Y.
1376
1377config X86_MSR
1378 tristate "/dev/cpu/*/msr - Model-specific register support"
1379 help
1380 This device gives privileged processes access to the x86
1381 Model-Specific Registers (MSRs). It is a character device with
1382 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1383 MSR accesses are directed to a specific CPU on multi-processor
1384 systems.
1385
1386config X86_CPUID
1387 tristate "/dev/cpu/*/cpuid - CPU information support"
1388 help
1389 This device gives processes access to the x86 CPUID instruction to
1390 be executed on a specific processor. It is a character device
1391 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1392 /dev/cpu/31/cpuid.
1393
1394choice
1395 prompt "High Memory Support"
1396 default HIGHMEM4G
1397 depends on X86_32
1398
1399config NOHIGHMEM
1400 bool "off"
1401 help
1402 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1403 However, the address space of 32-bit x86 processors is only 4
1404 Gigabytes large. That means that, if you have a large amount of
1405 physical memory, not all of it can be "permanently mapped" by the
1406 kernel. The physical memory that's not permanently mapped is called
1407 "high memory".
1408
1409 If you are compiling a kernel which will never run on a machine with
1410 more than 1 Gigabyte total physical RAM, answer "off" here (default
1411 choice and suitable for most users). This will result in a "3GB/1GB"
1412 split: 3GB are mapped so that each process sees a 3GB virtual memory
1413 space and the remaining part of the 4GB virtual memory space is used
1414 by the kernel to permanently map as much physical memory as
1415 possible.
1416
1417 If the machine has between 1 and 4 Gigabytes physical RAM, then
1418 answer "4GB" here.
1419
1420 If more than 4 Gigabytes is used then answer "64GB" here. This
1421 selection turns Intel PAE (Physical Address Extension) mode on.
1422 PAE implements 3-level paging on IA32 processors. PAE is fully
1423 supported by Linux, PAE mode is implemented on all recent Intel
1424 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1425 then the kernel will not boot on CPUs that don't support PAE!
1426
1427 The actual amount of total physical memory will either be
1428 auto detected or can be forced by using a kernel command line option
1429 such as "mem=256M". (Try "man bootparam" or see the documentation of
1430 your boot loader (lilo or loadlin) about how to pass options to the
1431 kernel at boot time.)
1432
1433 If unsure, say "off".
1434
1435config HIGHMEM4G
1436 bool "4GB"
1437 help
1438 Select this if you have a 32-bit processor and between 1 and 4
1439 gigabytes of physical RAM.
1440
1441config HIGHMEM64G
1442 bool "64GB"
1443 depends on X86_HAVE_PAE
1444 select X86_PAE
1445 help
1446 Select this if you have a 32-bit processor and more than 4
1447 gigabytes of physical RAM.
1448
1449endchoice
1450
1451choice
1452 prompt "Memory split" if EXPERT
1453 default VMSPLIT_3G
1454 depends on X86_32
1455 help
1456 Select the desired split between kernel and user memory.
1457
1458 If the address range available to the kernel is less than the
1459 physical memory installed, the remaining memory will be available
1460 as "high memory". Accessing high memory is a little more costly
1461 than low memory, as it needs to be mapped into the kernel first.
1462 Note that increasing the kernel address space limits the range
1463 available to user programs, making the address space there
1464 tighter. Selecting anything other than the default 3G/1G split
1465 will also likely make your kernel incompatible with binary-only
1466 kernel modules.
1467
1468 If you are not absolutely sure what you are doing, leave this
1469 option alone!
1470
1471 config VMSPLIT_3G
1472 bool "3G/1G user/kernel split"
1473 config VMSPLIT_3G_OPT
1474 depends on !X86_PAE
1475 bool "3G/1G user/kernel split (for full 1G low memory)"
1476 config VMSPLIT_2G
1477 bool "2G/2G user/kernel split"
1478 config VMSPLIT_2G_OPT
1479 depends on !X86_PAE
1480 bool "2G/2G user/kernel split (for full 2G low memory)"
1481 config VMSPLIT_1G
1482 bool "1G/3G user/kernel split"
1483endchoice
1484
1485config PAGE_OFFSET
1486 hex
1487 default 0xB0000000 if VMSPLIT_3G_OPT
1488 default 0x80000000 if VMSPLIT_2G
1489 default 0x78000000 if VMSPLIT_2G_OPT
1490 default 0x40000000 if VMSPLIT_1G
1491 default 0xC0000000
1492 depends on X86_32
1493
1494config HIGHMEM
1495 def_bool y
1496 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1497
1498config X86_PAE
1499 bool "PAE (Physical Address Extension) Support"
1500 depends on X86_32 && X86_HAVE_PAE
1501 select PHYS_ADDR_T_64BIT
1502 select SWIOTLB
1503 help
1504 PAE is required for NX support, and furthermore enables
1505 larger swapspace support for non-overcommit purposes. It
1506 has the cost of more pagetable lookup overhead, and also
1507 consumes more pagetable space per process.
1508
1509config X86_5LEVEL
1510 bool "Enable 5-level page tables support"
1511 default y
1512 select DYNAMIC_MEMORY_LAYOUT
1513 select SPARSEMEM_VMEMMAP
1514 depends on X86_64
1515 help
1516 5-level paging enables access to larger address space:
1517 up to 128 PiB of virtual address space and 4 PiB of
1518 physical address space.
1519
1520 It will be supported by future Intel CPUs.
1521
1522 A kernel with the option enabled can be booted on machines that
1523 support 4- or 5-level paging.
1524
1525 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1526 information.
1527
1528 Say N if unsure.
1529
1530config X86_DIRECT_GBPAGES
1531 def_bool y
1532 depends on X86_64
1533 help
1534 Certain kernel features effectively disable kernel
1535 linear 1 GB mappings (even if the CPU otherwise
1536 supports them), so don't confuse the user by printing
1537 that we have them enabled.
1538
1539config X86_CPA_STATISTICS
1540 bool "Enable statistic for Change Page Attribute"
1541 depends on DEBUG_FS
1542 help
1543 Expose statistics about the Change Page Attribute mechanism, which
1544 helps to determine the effectiveness of preserving large and huge
1545 page mappings when mapping protections are changed.
1546
1547config X86_MEM_ENCRYPT
1548 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1549 select DYNAMIC_PHYSICAL_MASK
1550 def_bool n
1551
1552config AMD_MEM_ENCRYPT
1553 bool "AMD Secure Memory Encryption (SME) support"
1554 depends on X86_64 && CPU_SUP_AMD
1555 depends on EFI_STUB
1556 select DMA_COHERENT_POOL
1557 select ARCH_USE_MEMREMAP_PROT
1558 select INSTRUCTION_DECODER
1559 select ARCH_HAS_CC_PLATFORM
1560 select X86_MEM_ENCRYPT
1561 select UNACCEPTED_MEMORY
1562 help
1563 Say yes to enable support for the encryption of system memory.
1564 This requires an AMD processor that supports Secure Memory
1565 Encryption (SME).
1566
1567# Common NUMA Features
1568config NUMA
1569 bool "NUMA Memory Allocation and Scheduler Support"
1570 depends on SMP
1571 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1572 default y if X86_BIGSMP
1573 select USE_PERCPU_NUMA_NODE_ID
1574 select OF_NUMA if OF
1575 help
1576 Enable NUMA (Non-Uniform Memory Access) support.
1577
1578 The kernel will try to allocate memory used by a CPU on the
1579 local memory controller of the CPU and add some more
1580 NUMA awareness to the kernel.
1581
1582 For 64-bit this is recommended if the system is Intel Core i7
1583 (or later), AMD Opteron, or EM64T NUMA.
1584
1585 For 32-bit this is only needed if you boot a 32-bit
1586 kernel on a 64-bit NUMA platform.
1587
1588 Otherwise, you should say N.
1589
1590config AMD_NUMA
1591 def_bool y
1592 prompt "Old style AMD Opteron NUMA detection"
1593 depends on X86_64 && NUMA && PCI
1594 help
1595 Enable AMD NUMA node topology detection. You should say Y here if
1596 you have a multi processor AMD system. This uses an old method to
1597 read the NUMA configuration directly from the builtin Northbridge
1598 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1599 which also takes priority if both are compiled in.
1600
1601config X86_64_ACPI_NUMA
1602 def_bool y
1603 prompt "ACPI NUMA detection"
1604 depends on X86_64 && NUMA && ACPI && PCI
1605 select ACPI_NUMA
1606 help
1607 Enable ACPI SRAT based node topology detection.
1608
1609config NODES_SHIFT
1610 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1611 range 1 10
1612 default "10" if MAXSMP
1613 default "6" if X86_64
1614 default "3"
1615 depends on NUMA
1616 help
1617 Specify the maximum number of NUMA Nodes available on the target
1618 system. Increases memory reserved to accommodate various tables.
1619
1620config ARCH_FLATMEM_ENABLE
1621 def_bool y
1622 depends on X86_32 && !NUMA
1623
1624config ARCH_SPARSEMEM_ENABLE
1625 def_bool y
1626 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1627 select SPARSEMEM_STATIC if X86_32
1628 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1629
1630config ARCH_SPARSEMEM_DEFAULT
1631 def_bool X86_64 || (NUMA && X86_32)
1632
1633config ARCH_SELECT_MEMORY_MODEL
1634 def_bool y
1635 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1636
1637config ARCH_MEMORY_PROBE
1638 bool "Enable sysfs memory/probe interface"
1639 depends on MEMORY_HOTPLUG
1640 help
1641 This option enables a sysfs memory/probe interface for testing.
1642 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1643 If you are unsure how to answer this question, answer N.
1644
1645config ARCH_PROC_KCORE_TEXT
1646 def_bool y
1647 depends on X86_64 && PROC_KCORE
1648
1649config ILLEGAL_POINTER_VALUE
1650 hex
1651 default 0 if X86_32
1652 default 0xdead000000000000 if X86_64
1653
1654config X86_PMEM_LEGACY_DEVICE
1655 bool
1656
1657config X86_PMEM_LEGACY
1658 tristate "Support non-standard NVDIMMs and ADR protected memory"
1659 depends on PHYS_ADDR_T_64BIT
1660 depends on BLK_DEV
1661 select X86_PMEM_LEGACY_DEVICE
1662 select NUMA_KEEP_MEMINFO if NUMA
1663 select LIBNVDIMM
1664 help
1665 Treat memory marked using the non-standard e820 type of 12 as used
1666 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1667 The kernel will offer these regions to the 'pmem' driver so
1668 they can be used for persistent storage.
1669
1670 Say Y if unsure.
1671
1672config HIGHPTE
1673 bool "Allocate 3rd-level pagetables from highmem"
1674 depends on HIGHMEM
1675 help
1676 The VM uses one page table entry for each page of physical memory.
1677 For systems with a lot of RAM, this can be wasteful of precious
1678 low memory. Setting this option will put user-space page table
1679 entries in high memory.
1680
1681config X86_CHECK_BIOS_CORRUPTION
1682 bool "Check for low memory corruption"
1683 help
1684 Periodically check for memory corruption in low memory, which
1685 is suspected to be caused by BIOS. Even when enabled in the
1686 configuration, it is disabled at runtime. Enable it by
1687 setting "memory_corruption_check=1" on the kernel command
1688 line. By default it scans the low 64k of memory every 60
1689 seconds; see the memory_corruption_check_size and
1690 memory_corruption_check_period parameters in
1691 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1692
1693 When enabled with the default parameters, this option has
1694 almost no overhead, as it reserves a relatively small amount
1695 of memory and scans it infrequently. It both detects corruption
1696 and prevents it from affecting the running system.
1697
1698 It is, however, intended as a diagnostic tool; if repeatable
1699 BIOS-originated corruption always affects the same memory,
1700 you can use memmap= to prevent the kernel from using that
1701 memory.
1702
1703config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1704 bool "Set the default setting of memory_corruption_check"
1705 depends on X86_CHECK_BIOS_CORRUPTION
1706 default y
1707 help
1708 Set whether the default state of memory_corruption_check is
1709 on or off.
1710
1711config MATH_EMULATION
1712 bool
1713 depends on MODIFY_LDT_SYSCALL
1714 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1715 help
1716 Linux can emulate a math coprocessor (used for floating point
1717 operations) if you don't have one. 486DX and Pentium processors have
1718 a math coprocessor built in, 486SX and 386 do not, unless you added
1719 a 487DX or 387, respectively. (The messages during boot time can
1720 give you some hints here ["man dmesg"].) Everyone needs either a
1721 coprocessor or this emulation.
1722
1723 If you don't have a math coprocessor, you need to say Y here; if you
1724 say Y here even though you have a coprocessor, the coprocessor will
1725 be used nevertheless. (This behavior can be changed with the kernel
1726 command line option "no387", which comes handy if your coprocessor
1727 is broken. Try "man bootparam" or see the documentation of your boot
1728 loader (lilo or loadlin) about how to pass options to the kernel at
1729 boot time.) This means that it is a good idea to say Y here if you
1730 intend to use this kernel on different machines.
1731
1732 More information about the internals of the Linux math coprocessor
1733 emulation can be found in <file:arch/x86/math-emu/README>.
1734
1735 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1736 kernel, it won't hurt.
1737
1738config MTRR
1739 def_bool y
1740 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1741 help
1742 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1743 the Memory Type Range Registers (MTRRs) may be used to control
1744 processor access to memory ranges. This is most useful if you have
1745 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1746 allows bus write transfers to be combined into a larger transfer
1747 before bursting over the PCI/AGP bus. This can increase performance
1748 of image write operations 2.5 times or more. Saying Y here creates a
1749 /proc/mtrr file which may be used to manipulate your processor's
1750 MTRRs. Typically the X server should use this.
1751
1752 This code has a reasonably generic interface so that similar
1753 control registers on other processors can be easily supported
1754 as well:
1755
1756 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1757 Registers (ARRs) which provide a similar functionality to MTRRs. For
1758 these, the ARRs are used to emulate the MTRRs.
1759 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1760 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1761 write-combining. All of these processors are supported by this code
1762 and it makes sense to say Y here if you have one of them.
1763
1764 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1765 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1766 can lead to all sorts of problems, so it's good to say Y here.
1767
1768 You can safely say Y even if your machine doesn't have MTRRs, you'll
1769 just add about 9 KB to your kernel.
1770
1771 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1772
1773config MTRR_SANITIZER
1774 def_bool y
1775 prompt "MTRR cleanup support"
1776 depends on MTRR
1777 help
1778 Convert MTRR layout from continuous to discrete, so X drivers can
1779 add writeback entries.
1780
1781 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1782 The largest mtrr entry size for a continuous block can be set with
1783 mtrr_chunk_size.
1784
1785 If unsure, say Y.
1786
1787config MTRR_SANITIZER_ENABLE_DEFAULT
1788 int "MTRR cleanup enable value (0-1)"
1789 range 0 1
1790 default "0"
1791 depends on MTRR_SANITIZER
1792 help
1793 Enable mtrr cleanup default value
1794
1795config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1796 int "MTRR cleanup spare reg num (0-7)"
1797 range 0 7
1798 default "1"
1799 depends on MTRR_SANITIZER
1800 help
1801 mtrr cleanup spare entries default, it can be changed via
1802 mtrr_spare_reg_nr=N on the kernel command line.
1803
1804config X86_PAT
1805 def_bool y
1806 prompt "x86 PAT support" if EXPERT
1807 depends on MTRR
1808 select ARCH_USES_PG_ARCH_2
1809 help
1810 Use PAT attributes to setup page level cache control.
1811
1812 PATs are the modern equivalents of MTRRs and are much more
1813 flexible than MTRRs.
1814
1815 Say N here if you see bootup problems (boot crash, boot hang,
1816 spontaneous reboots) or a non-working video driver.
1817
1818 If unsure, say Y.
1819
1820config X86_UMIP
1821 def_bool y
1822 prompt "User Mode Instruction Prevention" if EXPERT
1823 help
1824 User Mode Instruction Prevention (UMIP) is a security feature in
1825 some x86 processors. If enabled, a general protection fault is
1826 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1827 executed in user mode. These instructions unnecessarily expose
1828 information about the hardware state.
1829
1830 The vast majority of applications do not use these instructions.
1831 For the very few that do, software emulation is provided in
1832 specific cases in protected and virtual-8086 modes. Emulated
1833 results are dummy.
1834
1835config CC_HAS_IBT
1836 # GCC >= 9 and binutils >= 2.29
1837 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1838 # Clang/LLVM >= 14
1839 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1840 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1841 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1842 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1843 $(as-instr,endbr64)
1844
1845config X86_CET
1846 def_bool n
1847 help
1848 CET features configured (Shadow stack or IBT)
1849
1850config X86_KERNEL_IBT
1851 prompt "Indirect Branch Tracking"
1852 def_bool y
1853 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1854 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1855 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1856 select OBJTOOL
1857 select X86_CET
1858 help
1859 Build the kernel with support for Indirect Branch Tracking, a
1860 hardware support course-grain forward-edge Control Flow Integrity
1861 protection. It enforces that all indirect calls must land on
1862 an ENDBR instruction, as such, the compiler will instrument the
1863 code with them to make this happen.
1864
1865 In addition to building the kernel with IBT, seal all functions that
1866 are not indirect call targets, avoiding them ever becoming one.
1867
1868 This requires LTO like objtool runs and will slow down the build. It
1869 does significantly reduce the number of ENDBR instructions in the
1870 kernel image.
1871
1872config X86_INTEL_MEMORY_PROTECTION_KEYS
1873 prompt "Memory Protection Keys"
1874 def_bool y
1875 # Note: only available in 64-bit mode
1876 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1877 select ARCH_USES_HIGH_VMA_FLAGS
1878 select ARCH_HAS_PKEYS
1879 help
1880 Memory Protection Keys provides a mechanism for enforcing
1881 page-based protections, but without requiring modification of the
1882 page tables when an application changes protection domains.
1883
1884 For details, see Documentation/core-api/protection-keys.rst
1885
1886 If unsure, say y.
1887
1888config ARCH_PKEY_BITS
1889 int
1890 default 4
1891
1892choice
1893 prompt "TSX enable mode"
1894 depends on CPU_SUP_INTEL
1895 default X86_INTEL_TSX_MODE_OFF
1896 help
1897 Intel's TSX (Transactional Synchronization Extensions) feature
1898 allows to optimize locking protocols through lock elision which
1899 can lead to a noticeable performance boost.
1900
1901 On the other hand it has been shown that TSX can be exploited
1902 to form side channel attacks (e.g. TAA) and chances are there
1903 will be more of those attacks discovered in the future.
1904
1905 Therefore TSX is not enabled by default (aka tsx=off). An admin
1906 might override this decision by tsx=on the command line parameter.
1907 Even with TSX enabled, the kernel will attempt to enable the best
1908 possible TAA mitigation setting depending on the microcode available
1909 for the particular machine.
1910
1911 This option allows to set the default tsx mode between tsx=on, =off
1912 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1913 details.
1914
1915 Say off if not sure, auto if TSX is in use but it should be used on safe
1916 platforms or on if TSX is in use and the security aspect of tsx is not
1917 relevant.
1918
1919config X86_INTEL_TSX_MODE_OFF
1920 bool "off"
1921 help
1922 TSX is disabled if possible - equals to tsx=off command line parameter.
1923
1924config X86_INTEL_TSX_MODE_ON
1925 bool "on"
1926 help
1927 TSX is always enabled on TSX capable HW - equals the tsx=on command
1928 line parameter.
1929
1930config X86_INTEL_TSX_MODE_AUTO
1931 bool "auto"
1932 help
1933 TSX is enabled on TSX capable HW that is believed to be safe against
1934 side channel attacks- equals the tsx=auto command line parameter.
1935endchoice
1936
1937config X86_SGX
1938 bool "Software Guard eXtensions (SGX)"
1939 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1940 depends on CRYPTO=y
1941 depends on CRYPTO_SHA256=y
1942 select MMU_NOTIFIER
1943 select NUMA_KEEP_MEMINFO if NUMA
1944 select XARRAY_MULTI
1945 help
1946 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1947 that can be used by applications to set aside private regions of code
1948 and data, referred to as enclaves. An enclave's private memory can
1949 only be accessed by code running within the enclave. Accesses from
1950 outside the enclave, including other enclaves, are disallowed by
1951 hardware.
1952
1953 If unsure, say N.
1954
1955config X86_USER_SHADOW_STACK
1956 bool "X86 userspace shadow stack"
1957 depends on AS_WRUSS
1958 depends on X86_64
1959 select ARCH_USES_HIGH_VMA_FLAGS
1960 select ARCH_HAS_USER_SHADOW_STACK
1961 select X86_CET
1962 help
1963 Shadow stack protection is a hardware feature that detects function
1964 return address corruption. This helps mitigate ROP attacks.
1965 Applications must be enabled to use it, and old userspace does not
1966 get protection "for free".
1967
1968 CPUs supporting shadow stacks were first released in 2020.
1969
1970 See Documentation/arch/x86/shstk.rst for more information.
1971
1972 If unsure, say N.
1973
1974config INTEL_TDX_HOST
1975 bool "Intel Trust Domain Extensions (TDX) host support"
1976 depends on CPU_SUP_INTEL
1977 depends on X86_64
1978 depends on KVM_INTEL
1979 depends on X86_X2APIC
1980 select ARCH_KEEP_MEMBLOCK
1981 depends on CONTIG_ALLOC
1982 depends on !KEXEC_CORE
1983 depends on X86_MCE
1984 help
1985 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1986 host and certain physical attacks. This option enables necessary TDX
1987 support in the host kernel to run confidential VMs.
1988
1989 If unsure, say N.
1990
1991config EFI
1992 bool "EFI runtime service support"
1993 depends on ACPI
1994 select UCS2_STRING
1995 select EFI_RUNTIME_WRAPPERS
1996 select ARCH_USE_MEMREMAP_PROT
1997 select EFI_RUNTIME_MAP if KEXEC_CORE
1998 help
1999 This enables the kernel to use EFI runtime services that are
2000 available (such as the EFI variable services).
2001
2002 This option is only useful on systems that have EFI firmware.
2003 In addition, you should use the latest ELILO loader available
2004 at <http://elilo.sourceforge.net> in order to take advantage
2005 of EFI runtime services. However, even with this option, the
2006 resultant kernel should continue to boot on existing non-EFI
2007 platforms.
2008
2009config EFI_STUB
2010 bool "EFI stub support"
2011 depends on EFI
2012 select RELOCATABLE
2013 help
2014 This kernel feature allows a bzImage to be loaded directly
2015 by EFI firmware without the use of a bootloader.
2016
2017 See Documentation/admin-guide/efi-stub.rst for more information.
2018
2019config EFI_HANDOVER_PROTOCOL
2020 bool "EFI handover protocol (DEPRECATED)"
2021 depends on EFI_STUB
2022 default y
2023 help
2024 Select this in order to include support for the deprecated EFI
2025 handover protocol, which defines alternative entry points into the
2026 EFI stub. This is a practice that has no basis in the UEFI
2027 specification, and requires a priori knowledge on the part of the
2028 bootloader about Linux/x86 specific ways of passing the command line
2029 and initrd, and where in memory those assets may be loaded.
2030
2031 If in doubt, say Y. Even though the corresponding support is not
2032 present in upstream GRUB or other bootloaders, most distros build
2033 GRUB with numerous downstream patches applied, and may rely on the
2034 handover protocol as as result.
2035
2036config EFI_MIXED
2037 bool "EFI mixed-mode support"
2038 depends on EFI_STUB && X86_64
2039 help
2040 Enabling this feature allows a 64-bit kernel to be booted
2041 on a 32-bit firmware, provided that your CPU supports 64-bit
2042 mode.
2043
2044 Note that it is not possible to boot a mixed-mode enabled
2045 kernel via the EFI boot stub - a bootloader that supports
2046 the EFI handover protocol must be used.
2047
2048 If unsure, say N.
2049
2050config EFI_RUNTIME_MAP
2051 bool "Export EFI runtime maps to sysfs" if EXPERT
2052 depends on EFI
2053 help
2054 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2055 That memory map is required by the 2nd kernel to set up EFI virtual
2056 mappings after kexec, but can also be used for debugging purposes.
2057
2058 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2059
2060source "kernel/Kconfig.hz"
2061
2062config ARCH_SUPPORTS_KEXEC
2063 def_bool y
2064
2065config ARCH_SUPPORTS_KEXEC_FILE
2066 def_bool X86_64
2067
2068config ARCH_SELECTS_KEXEC_FILE
2069 def_bool y
2070 depends on KEXEC_FILE
2071 select HAVE_IMA_KEXEC if IMA
2072
2073config ARCH_SUPPORTS_KEXEC_PURGATORY
2074 def_bool y
2075
2076config ARCH_SUPPORTS_KEXEC_SIG
2077 def_bool y
2078
2079config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2080 def_bool y
2081
2082config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2083 def_bool y
2084
2085config ARCH_SUPPORTS_KEXEC_JUMP
2086 def_bool y
2087
2088config ARCH_SUPPORTS_CRASH_DUMP
2089 def_bool X86_64 || (X86_32 && HIGHMEM)
2090
2091config ARCH_DEFAULT_CRASH_DUMP
2092 def_bool y
2093
2094config ARCH_SUPPORTS_CRASH_HOTPLUG
2095 def_bool y
2096
2097config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2098 def_bool CRASH_RESERVE
2099
2100config PHYSICAL_START
2101 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2102 default "0x1000000"
2103 help
2104 This gives the physical address where the kernel is loaded.
2105
2106 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2107 will decompress itself to above physical address and run from there.
2108 Otherwise, bzImage will run from the address where it has been loaded
2109 by the boot loader. The only exception is if it is loaded below the
2110 above physical address, in which case it will relocate itself there.
2111
2112 In normal kdump cases one does not have to set/change this option
2113 as now bzImage can be compiled as a completely relocatable image
2114 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2115 address. This option is mainly useful for the folks who don't want
2116 to use a bzImage for capturing the crash dump and want to use a
2117 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2118 to be specifically compiled to run from a specific memory area
2119 (normally a reserved region) and this option comes handy.
2120
2121 So if you are using bzImage for capturing the crash dump,
2122 leave the value here unchanged to 0x1000000 and set
2123 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2124 for capturing the crash dump change this value to start of
2125 the reserved region. In other words, it can be set based on
2126 the "X" value as specified in the "crashkernel=YM@XM"
2127 command line boot parameter passed to the panic-ed
2128 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2129 for more details about crash dumps.
2130
2131 Usage of bzImage for capturing the crash dump is recommended as
2132 one does not have to build two kernels. Same kernel can be used
2133 as production kernel and capture kernel. Above option should have
2134 gone away after relocatable bzImage support is introduced. But it
2135 is present because there are users out there who continue to use
2136 vmlinux for dump capture. This option should go away down the
2137 line.
2138
2139 Don't change this unless you know what you are doing.
2140
2141config RELOCATABLE
2142 bool "Build a relocatable kernel"
2143 default y
2144 help
2145 This builds a kernel image that retains relocation information
2146 so it can be loaded someplace besides the default 1MB.
2147 The relocations tend to make the kernel binary about 10% larger,
2148 but are discarded at runtime.
2149
2150 One use is for the kexec on panic case where the recovery kernel
2151 must live at a different physical address than the primary
2152 kernel.
2153
2154 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2155 it has been loaded at and the compile time physical address
2156 (CONFIG_PHYSICAL_START) is used as the minimum location.
2157
2158config RANDOMIZE_BASE
2159 bool "Randomize the address of the kernel image (KASLR)"
2160 depends on RELOCATABLE
2161 default y
2162 help
2163 In support of Kernel Address Space Layout Randomization (KASLR),
2164 this randomizes the physical address at which the kernel image
2165 is decompressed and the virtual address where the kernel
2166 image is mapped, as a security feature that deters exploit
2167 attempts relying on knowledge of the location of kernel
2168 code internals.
2169
2170 On 64-bit, the kernel physical and virtual addresses are
2171 randomized separately. The physical address will be anywhere
2172 between 16MB and the top of physical memory (up to 64TB). The
2173 virtual address will be randomized from 16MB up to 1GB (9 bits
2174 of entropy). Note that this also reduces the memory space
2175 available to kernel modules from 1.5GB to 1GB.
2176
2177 On 32-bit, the kernel physical and virtual addresses are
2178 randomized together. They will be randomized from 16MB up to
2179 512MB (8 bits of entropy).
2180
2181 Entropy is generated using the RDRAND instruction if it is
2182 supported. If RDTSC is supported, its value is mixed into
2183 the entropy pool as well. If neither RDRAND nor RDTSC are
2184 supported, then entropy is read from the i8254 timer. The
2185 usable entropy is limited by the kernel being built using
2186 2GB addressing, and that PHYSICAL_ALIGN must be at a
2187 minimum of 2MB. As a result, only 10 bits of entropy are
2188 theoretically possible, but the implementations are further
2189 limited due to memory layouts.
2190
2191 If unsure, say Y.
2192
2193# Relocation on x86 needs some additional build support
2194config X86_NEED_RELOCS
2195 def_bool y
2196 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2197
2198config PHYSICAL_ALIGN
2199 hex "Alignment value to which kernel should be aligned"
2200 default "0x200000"
2201 range 0x2000 0x1000000 if X86_32
2202 range 0x200000 0x1000000 if X86_64
2203 help
2204 This value puts the alignment restrictions on physical address
2205 where kernel is loaded and run from. Kernel is compiled for an
2206 address which meets above alignment restriction.
2207
2208 If bootloader loads the kernel at a non-aligned address and
2209 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2210 address aligned to above value and run from there.
2211
2212 If bootloader loads the kernel at a non-aligned address and
2213 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2214 load address and decompress itself to the address it has been
2215 compiled for and run from there. The address for which kernel is
2216 compiled already meets above alignment restrictions. Hence the
2217 end result is that kernel runs from a physical address meeting
2218 above alignment restrictions.
2219
2220 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2221 this value must be a multiple of 0x200000.
2222
2223 Don't change this unless you know what you are doing.
2224
2225config DYNAMIC_MEMORY_LAYOUT
2226 bool
2227 help
2228 This option makes base addresses of vmalloc and vmemmap as well as
2229 __PAGE_OFFSET movable during boot.
2230
2231config RANDOMIZE_MEMORY
2232 bool "Randomize the kernel memory sections"
2233 depends on X86_64
2234 depends on RANDOMIZE_BASE
2235 select DYNAMIC_MEMORY_LAYOUT
2236 default RANDOMIZE_BASE
2237 help
2238 Randomizes the base virtual address of kernel memory sections
2239 (physical memory mapping, vmalloc & vmemmap). This security feature
2240 makes exploits relying on predictable memory locations less reliable.
2241
2242 The order of allocations remains unchanged. Entropy is generated in
2243 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2244 configuration have in average 30,000 different possible virtual
2245 addresses for each memory section.
2246
2247 If unsure, say Y.
2248
2249config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2250 hex "Physical memory mapping padding" if EXPERT
2251 depends on RANDOMIZE_MEMORY
2252 default "0xa" if MEMORY_HOTPLUG
2253 default "0x0"
2254 range 0x1 0x40 if MEMORY_HOTPLUG
2255 range 0x0 0x40
2256 help
2257 Define the padding in terabytes added to the existing physical
2258 memory size during kernel memory randomization. It is useful
2259 for memory hotplug support but reduces the entropy available for
2260 address randomization.
2261
2262 If unsure, leave at the default value.
2263
2264config ADDRESS_MASKING
2265 bool "Linear Address Masking support"
2266 depends on X86_64
2267 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2268 help
2269 Linear Address Masking (LAM) modifies the checking that is applied
2270 to 64-bit linear addresses, allowing software to use of the
2271 untranslated address bits for metadata.
2272
2273 The capability can be used for efficient address sanitizers (ASAN)
2274 implementation and for optimizations in JITs.
2275
2276config HOTPLUG_CPU
2277 def_bool y
2278 depends on SMP
2279
2280config COMPAT_VDSO
2281 def_bool n
2282 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2283 depends on COMPAT_32
2284 help
2285 Certain buggy versions of glibc will crash if they are
2286 presented with a 32-bit vDSO that is not mapped at the address
2287 indicated in its segment table.
2288
2289 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2290 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2291 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2292 the only released version with the bug, but OpenSUSE 9
2293 contains a buggy "glibc 2.3.2".
2294
2295 The symptom of the bug is that everything crashes on startup, saying:
2296 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2297
2298 Saying Y here changes the default value of the vdso32 boot
2299 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2300 This works around the glibc bug but hurts performance.
2301
2302 If unsure, say N: if you are compiling your own kernel, you
2303 are unlikely to be using a buggy version of glibc.
2304
2305choice
2306 prompt "vsyscall table for legacy applications"
2307 depends on X86_64
2308 default LEGACY_VSYSCALL_XONLY
2309 help
2310 Legacy user code that does not know how to find the vDSO expects
2311 to be able to issue three syscalls by calling fixed addresses in
2312 kernel space. Since this location is not randomized with ASLR,
2313 it can be used to assist security vulnerability exploitation.
2314
2315 This setting can be changed at boot time via the kernel command
2316 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2317 is deprecated and can only be enabled using the kernel command
2318 line.
2319
2320 On a system with recent enough glibc (2.14 or newer) and no
2321 static binaries, you can say None without a performance penalty
2322 to improve security.
2323
2324 If unsure, select "Emulate execution only".
2325
2326 config LEGACY_VSYSCALL_XONLY
2327 bool "Emulate execution only"
2328 help
2329 The kernel traps and emulates calls into the fixed vsyscall
2330 address mapping and does not allow reads. This
2331 configuration is recommended when userspace might use the
2332 legacy vsyscall area but support for legacy binary
2333 instrumentation of legacy code is not needed. It mitigates
2334 certain uses of the vsyscall area as an ASLR-bypassing
2335 buffer.
2336
2337 config LEGACY_VSYSCALL_NONE
2338 bool "None"
2339 help
2340 There will be no vsyscall mapping at all. This will
2341 eliminate any risk of ASLR bypass due to the vsyscall
2342 fixed address mapping. Attempts to use the vsyscalls
2343 will be reported to dmesg, so that either old or
2344 malicious userspace programs can be identified.
2345
2346endchoice
2347
2348config CMDLINE_BOOL
2349 bool "Built-in kernel command line"
2350 help
2351 Allow for specifying boot arguments to the kernel at
2352 build time. On some systems (e.g. embedded ones), it is
2353 necessary or convenient to provide some or all of the
2354 kernel boot arguments with the kernel itself (that is,
2355 to not rely on the boot loader to provide them.)
2356
2357 To compile command line arguments into the kernel,
2358 set this option to 'Y', then fill in the
2359 boot arguments in CONFIG_CMDLINE.
2360
2361 Systems with fully functional boot loaders (i.e. non-embedded)
2362 should leave this option set to 'N'.
2363
2364config CMDLINE
2365 string "Built-in kernel command string"
2366 depends on CMDLINE_BOOL
2367 default ""
2368 help
2369 Enter arguments here that should be compiled into the kernel
2370 image and used at boot time. If the boot loader provides a
2371 command line at boot time, it is appended to this string to
2372 form the full kernel command line, when the system boots.
2373
2374 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2375 change this behavior.
2376
2377 In most cases, the command line (whether built-in or provided
2378 by the boot loader) should specify the device for the root
2379 file system.
2380
2381config CMDLINE_OVERRIDE
2382 bool "Built-in command line overrides boot loader arguments"
2383 depends on CMDLINE_BOOL && CMDLINE != ""
2384 help
2385 Set this option to 'Y' to have the kernel ignore the boot loader
2386 command line, and use ONLY the built-in command line.
2387
2388 This is used to work around broken boot loaders. This should
2389 be set to 'N' under normal conditions.
2390
2391config MODIFY_LDT_SYSCALL
2392 bool "Enable the LDT (local descriptor table)" if EXPERT
2393 default y
2394 help
2395 Linux can allow user programs to install a per-process x86
2396 Local Descriptor Table (LDT) using the modify_ldt(2) system
2397 call. This is required to run 16-bit or segmented code such as
2398 DOSEMU or some Wine programs. It is also used by some very old
2399 threading libraries.
2400
2401 Enabling this feature adds a small amount of overhead to
2402 context switches and increases the low-level kernel attack
2403 surface. Disabling it removes the modify_ldt(2) system call.
2404
2405 Saying 'N' here may make sense for embedded or server kernels.
2406
2407config STRICT_SIGALTSTACK_SIZE
2408 bool "Enforce strict size checking for sigaltstack"
2409 depends on DYNAMIC_SIGFRAME
2410 help
2411 For historical reasons MINSIGSTKSZ is a constant which became
2412 already too small with AVX512 support. Add a mechanism to
2413 enforce strict checking of the sigaltstack size against the
2414 real size of the FPU frame. This option enables the check
2415 by default. It can also be controlled via the kernel command
2416 line option 'strict_sas_size' independent of this config
2417 switch. Enabling it might break existing applications which
2418 allocate a too small sigaltstack but 'work' because they
2419 never get a signal delivered.
2420
2421 Say 'N' unless you want to really enforce this check.
2422
2423config CFI_AUTO_DEFAULT
2424 bool "Attempt to use FineIBT by default at boot time"
2425 depends on FINEIBT
2426 default y
2427 help
2428 Attempt to use FineIBT by default at boot time. If enabled,
2429 this is the same as booting with "cfi=auto". If disabled,
2430 this is the same as booting with "cfi=kcfi".
2431
2432source "kernel/livepatch/Kconfig"
2433
2434config X86_BUS_LOCK_DETECT
2435 bool "Split Lock Detect and Bus Lock Detect support"
2436 depends on CPU_SUP_INTEL || CPU_SUP_AMD
2437 default y
2438 help
2439 Enable Split Lock Detect and Bus Lock Detect functionalities.
2440 See <file:Documentation/arch/x86/buslock.rst> for more information.
2441
2442endmenu
2443
2444config CC_HAS_NAMED_AS
2445 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2446 depends on CC_IS_GCC
2447
2448config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2449 def_bool CC_IS_GCC && GCC_VERSION >= 130300
2450
2451config USE_X86_SEG_SUPPORT
2452 def_bool y
2453 depends on CC_HAS_NAMED_AS
2454 #
2455 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread
2456 # (KCSAN) are incompatible with named address spaces with
2457 # GCC < 13.3 - see GCC PR sanitizer/111736.
2458 #
2459 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS
2460
2461config CC_HAS_SLS
2462 def_bool $(cc-option,-mharden-sls=all)
2463
2464config CC_HAS_RETURN_THUNK
2465 def_bool $(cc-option,-mfunction-return=thunk-extern)
2466
2467config CC_HAS_ENTRY_PADDING
2468 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2469
2470config FUNCTION_PADDING_CFI
2471 int
2472 default 59 if FUNCTION_ALIGNMENT_64B
2473 default 27 if FUNCTION_ALIGNMENT_32B
2474 default 11 if FUNCTION_ALIGNMENT_16B
2475 default 3 if FUNCTION_ALIGNMENT_8B
2476 default 0
2477
2478# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2479# except Kconfig can't do arithmetic :/
2480config FUNCTION_PADDING_BYTES
2481 int
2482 default FUNCTION_PADDING_CFI if CFI_CLANG
2483 default FUNCTION_ALIGNMENT
2484
2485config CALL_PADDING
2486 def_bool n
2487 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2488 select FUNCTION_ALIGNMENT_16B
2489
2490config FINEIBT
2491 def_bool y
2492 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2493 select CALL_PADDING
2494
2495config HAVE_CALL_THUNKS
2496 def_bool y
2497 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2498
2499config CALL_THUNKS
2500 def_bool n
2501 select CALL_PADDING
2502
2503config PREFIX_SYMBOLS
2504 def_bool y
2505 depends on CALL_PADDING && !CFI_CLANG
2506
2507menuconfig CPU_MITIGATIONS
2508 bool "Mitigations for CPU vulnerabilities"
2509 default y
2510 help
2511 Say Y here to enable options which enable mitigations for hardware
2512 vulnerabilities (usually related to speculative execution).
2513 Mitigations can be disabled or restricted to SMT systems at runtime
2514 via the "mitigations" kernel parameter.
2515
2516 If you say N, all mitigations will be disabled. This CANNOT be
2517 overridden at runtime.
2518
2519 Say 'Y', unless you really know what you are doing.
2520
2521if CPU_MITIGATIONS
2522
2523config MITIGATION_PAGE_TABLE_ISOLATION
2524 bool "Remove the kernel mapping in user mode"
2525 default y
2526 depends on (X86_64 || X86_PAE)
2527 help
2528 This feature reduces the number of hardware side channels by
2529 ensuring that the majority of kernel addresses are not mapped
2530 into userspace.
2531
2532 See Documentation/arch/x86/pti.rst for more details.
2533
2534config MITIGATION_RETPOLINE
2535 bool "Avoid speculative indirect branches in kernel"
2536 select OBJTOOL if HAVE_OBJTOOL
2537 default y
2538 help
2539 Compile kernel with the retpoline compiler options to guard against
2540 kernel-to-user data leaks by avoiding speculative indirect
2541 branches. Requires a compiler with -mindirect-branch=thunk-extern
2542 support for full protection. The kernel may run slower.
2543
2544config MITIGATION_RETHUNK
2545 bool "Enable return-thunks"
2546 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2547 select OBJTOOL if HAVE_OBJTOOL
2548 default y if X86_64
2549 help
2550 Compile the kernel with the return-thunks compiler option to guard
2551 against kernel-to-user data leaks by avoiding return speculation.
2552 Requires a compiler with -mfunction-return=thunk-extern
2553 support for full protection. The kernel may run slower.
2554
2555config MITIGATION_UNRET_ENTRY
2556 bool "Enable UNRET on kernel entry"
2557 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2558 default y
2559 help
2560 Compile the kernel with support for the retbleed=unret mitigation.
2561
2562config MITIGATION_CALL_DEPTH_TRACKING
2563 bool "Mitigate RSB underflow with call depth tracking"
2564 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2565 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2566 select CALL_THUNKS
2567 default y
2568 help
2569 Compile the kernel with call depth tracking to mitigate the Intel
2570 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
2571 by default and needs to be enabled on the kernel command line via the
2572 retbleed=stuff option. For non-affected systems the overhead of this
2573 option is marginal as the call depth tracking is using run-time
2574 generated call thunks in a compiler generated padding area and call
2575 patching. This increases text size by ~5%. For non affected systems
2576 this space is unused. On affected SKL systems this results in a
2577 significant performance gain over the IBRS mitigation.
2578
2579config CALL_THUNKS_DEBUG
2580 bool "Enable call thunks and call depth tracking debugging"
2581 depends on MITIGATION_CALL_DEPTH_TRACKING
2582 select FUNCTION_ALIGNMENT_32B
2583 default n
2584 help
2585 Enable call/ret counters for imbalance detection and build in
2586 a noisy dmesg about callthunks generation and call patching for
2587 trouble shooting. The debug prints need to be enabled on the
2588 kernel command line with 'debug-callthunks'.
2589 Only enable this when you are debugging call thunks as this
2590 creates a noticeable runtime overhead. If unsure say N.
2591
2592config MITIGATION_IBPB_ENTRY
2593 bool "Enable IBPB on kernel entry"
2594 depends on CPU_SUP_AMD && X86_64
2595 default y
2596 help
2597 Compile the kernel with support for the retbleed=ibpb and
2598 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
2599
2600config MITIGATION_IBRS_ENTRY
2601 bool "Enable IBRS on kernel entry"
2602 depends on CPU_SUP_INTEL && X86_64
2603 default y
2604 help
2605 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2606 This mitigates both spectre_v2 and retbleed at great cost to
2607 performance.
2608
2609config MITIGATION_SRSO
2610 bool "Mitigate speculative RAS overflow on AMD"
2611 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2612 default y
2613 help
2614 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2615
2616config MITIGATION_SLS
2617 bool "Mitigate Straight-Line-Speculation"
2618 depends on CC_HAS_SLS && X86_64
2619 select OBJTOOL if HAVE_OBJTOOL
2620 default n
2621 help
2622 Compile the kernel with straight-line-speculation options to guard
2623 against straight line speculation. The kernel image might be slightly
2624 larger.
2625
2626config MITIGATION_GDS
2627 bool "Mitigate Gather Data Sampling"
2628 depends on CPU_SUP_INTEL
2629 default y
2630 help
2631 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2632 vulnerability which allows unprivileged speculative access to data
2633 which was previously stored in vector registers. The attacker uses gather
2634 instructions to infer the stale vector register data.
2635
2636config MITIGATION_RFDS
2637 bool "RFDS Mitigation"
2638 depends on CPU_SUP_INTEL
2639 default y
2640 help
2641 Enable mitigation for Register File Data Sampling (RFDS) by default.
2642 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2643 allows unprivileged speculative access to stale data previously
2644 stored in floating point, vector and integer registers.
2645 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2646
2647config MITIGATION_SPECTRE_BHI
2648 bool "Mitigate Spectre-BHB (Branch History Injection)"
2649 depends on CPU_SUP_INTEL
2650 default y
2651 help
2652 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2653 where the branch history buffer is poisoned to speculatively steer
2654 indirect branches.
2655 See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2656
2657config MITIGATION_MDS
2658 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2659 depends on CPU_SUP_INTEL
2660 default y
2661 help
2662 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2663 a hardware vulnerability which allows unprivileged speculative access
2664 to data which is available in various CPU internal buffers.
2665 See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2666
2667config MITIGATION_TAA
2668 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2669 depends on CPU_SUP_INTEL
2670 default y
2671 help
2672 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2673 vulnerability that allows unprivileged speculative access to data
2674 which is available in various CPU internal buffers by using
2675 asynchronous aborts within an Intel TSX transactional region.
2676 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2677
2678config MITIGATION_MMIO_STALE_DATA
2679 bool "Mitigate MMIO Stale Data hardware bug"
2680 depends on CPU_SUP_INTEL
2681 default y
2682 help
2683 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO
2684 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2685 vulnerabilities that can expose data. The vulnerabilities require the
2686 attacker to have access to MMIO.
2687 See also
2688 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2689
2690config MITIGATION_L1TF
2691 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2692 depends on CPU_SUP_INTEL
2693 default y
2694 help
2695 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2696 hardware vulnerability which allows unprivileged speculative access to data
2697 available in the Level 1 Data Cache.
2698 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2699
2700config MITIGATION_RETBLEED
2701 bool "Mitigate RETBleed hardware bug"
2702 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2703 default y
2704 help
2705 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2706 with Return Instructions) vulnerability. RETBleed is a speculative
2707 execution attack which takes advantage of microarchitectural behavior
2708 in many modern microprocessors, similar to Spectre v2. An
2709 unprivileged attacker can use these flaws to bypass conventional
2710 memory security restrictions to gain read access to privileged memory
2711 that would otherwise be inaccessible.
2712
2713config MITIGATION_SPECTRE_V1
2714 bool "Mitigate SPECTRE V1 hardware bug"
2715 default y
2716 help
2717 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2718 class of side channel attacks that takes advantage of speculative
2719 execution that bypasses conditional branch instructions used for
2720 memory access bounds check.
2721 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2722
2723config MITIGATION_SPECTRE_V2
2724 bool "Mitigate SPECTRE V2 hardware bug"
2725 default y
2726 help
2727 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2728 V2 is a class of side channel attacks that takes advantage of
2729 indirect branch predictors inside the processor. In Spectre variant 2
2730 attacks, the attacker can steer speculative indirect branches in the
2731 victim to gadget code by poisoning the branch target buffer of a CPU
2732 used for predicting indirect branch addresses.
2733 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2734
2735config MITIGATION_SRBDS
2736 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2737 depends on CPU_SUP_INTEL
2738 default y
2739 help
2740 Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2741 SRBDS is a hardware vulnerability that allows Microarchitectural Data
2742 Sampling (MDS) techniques to infer values returned from special
2743 register accesses. An unprivileged user can extract values returned
2744 from RDRAND and RDSEED executed on another core or sibling thread
2745 using MDS techniques.
2746 See also
2747 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2748
2749config MITIGATION_SSB
2750 bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2751 default y
2752 help
2753 Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2754 hardware security vulnerability and its exploitation takes advantage
2755 of speculative execution in a similar way to the Meltdown and Spectre
2756 security vulnerabilities.
2757
2758endif
2759
2760config ARCH_HAS_ADD_PAGES
2761 def_bool y
2762 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2763
2764menu "Power management and ACPI options"
2765
2766config ARCH_HIBERNATION_HEADER
2767 def_bool y
2768 depends on HIBERNATION
2769
2770source "kernel/power/Kconfig"
2771
2772source "drivers/acpi/Kconfig"
2773
2774config X86_APM_BOOT
2775 def_bool y
2776 depends on APM
2777
2778menuconfig APM
2779 tristate "APM (Advanced Power Management) BIOS support"
2780 depends on X86_32 && PM_SLEEP
2781 help
2782 APM is a BIOS specification for saving power using several different
2783 techniques. This is mostly useful for battery powered laptops with
2784 APM compliant BIOSes. If you say Y here, the system time will be
2785 reset after a RESUME operation, the /proc/apm device will provide
2786 battery status information, and user-space programs will receive
2787 notification of APM "events" (e.g. battery status change).
2788
2789 If you select "Y" here, you can disable actual use of the APM
2790 BIOS by passing the "apm=off" option to the kernel at boot time.
2791
2792 Note that the APM support is almost completely disabled for
2793 machines with more than one CPU.
2794
2795 In order to use APM, you will need supporting software. For location
2796 and more information, read <file:Documentation/power/apm-acpi.rst>
2797 and the Battery Powered Linux mini-HOWTO, available from
2798 <http://www.tldp.org/docs.html#howto>.
2799
2800 This driver does not spin down disk drives (see the hdparm(8)
2801 manpage ("man 8 hdparm") for that), and it doesn't turn off
2802 VESA-compliant "green" monitors.
2803
2804 This driver does not support the TI 4000M TravelMate and the ACER
2805 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2806 desktop machines also don't have compliant BIOSes, and this driver
2807 may cause those machines to panic during the boot phase.
2808
2809 Generally, if you don't have a battery in your machine, there isn't
2810 much point in using this driver and you should say N. If you get
2811 random kernel OOPSes or reboots that don't seem to be related to
2812 anything, try disabling/enabling this option (or disabling/enabling
2813 APM in your BIOS).
2814
2815 Some other things you should try when experiencing seemingly random,
2816 "weird" problems:
2817
2818 1) make sure that you have enough swap space and that it is
2819 enabled.
2820 2) pass the "idle=poll" option to the kernel
2821 3) switch on floating point emulation in the kernel and pass
2822 the "no387" option to the kernel
2823 4) pass the "floppy=nodma" option to the kernel
2824 5) pass the "mem=4M" option to the kernel (thereby disabling
2825 all but the first 4 MB of RAM)
2826 6) make sure that the CPU is not over clocked.
2827 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2828 8) disable the cache from your BIOS settings
2829 9) install a fan for the video card or exchange video RAM
2830 10) install a better fan for the CPU
2831 11) exchange RAM chips
2832 12) exchange the motherboard.
2833
2834 To compile this driver as a module, choose M here: the
2835 module will be called apm.
2836
2837if APM
2838
2839config APM_IGNORE_USER_SUSPEND
2840 bool "Ignore USER SUSPEND"
2841 help
2842 This option will ignore USER SUSPEND requests. On machines with a
2843 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2844 series notebooks, it is necessary to say Y because of a BIOS bug.
2845
2846config APM_DO_ENABLE
2847 bool "Enable PM at boot time"
2848 help
2849 Enable APM features at boot time. From page 36 of the APM BIOS
2850 specification: "When disabled, the APM BIOS does not automatically
2851 power manage devices, enter the Standby State, enter the Suspend
2852 State, or take power saving steps in response to CPU Idle calls."
2853 This driver will make CPU Idle calls when Linux is idle (unless this
2854 feature is turned off -- see "Do CPU IDLE calls", below). This
2855 should always save battery power, but more complicated APM features
2856 will be dependent on your BIOS implementation. You may need to turn
2857 this option off if your computer hangs at boot time when using APM
2858 support, or if it beeps continuously instead of suspending. Turn
2859 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2860 T400CDT. This is off by default since most machines do fine without
2861 this feature.
2862
2863config APM_CPU_IDLE
2864 depends on CPU_IDLE
2865 bool "Make CPU Idle calls when idle"
2866 help
2867 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2868 On some machines, this can activate improved power savings, such as
2869 a slowed CPU clock rate, when the machine is idle. These idle calls
2870 are made after the idle loop has run for some length of time (e.g.,
2871 333 mS). On some machines, this will cause a hang at boot time or
2872 whenever the CPU becomes idle. (On machines with more than one CPU,
2873 this option does nothing.)
2874
2875config APM_DISPLAY_BLANK
2876 bool "Enable console blanking using APM"
2877 help
2878 Enable console blanking using the APM. Some laptops can use this to
2879 turn off the LCD backlight when the screen blanker of the Linux
2880 virtual console blanks the screen. Note that this is only used by
2881 the virtual console screen blanker, and won't turn off the backlight
2882 when using the X Window system. This also doesn't have anything to
2883 do with your VESA-compliant power-saving monitor. Further, this
2884 option doesn't work for all laptops -- it might not turn off your
2885 backlight at all, or it might print a lot of errors to the console,
2886 especially if you are using gpm.
2887
2888config APM_ALLOW_INTS
2889 bool "Allow interrupts during APM BIOS calls"
2890 help
2891 Normally we disable external interrupts while we are making calls to
2892 the APM BIOS as a measure to lessen the effects of a badly behaving
2893 BIOS implementation. The BIOS should reenable interrupts if it
2894 needs to. Unfortunately, some BIOSes do not -- especially those in
2895 many of the newer IBM Thinkpads. If you experience hangs when you
2896 suspend, try setting this to Y. Otherwise, say N.
2897
2898endif # APM
2899
2900source "drivers/cpufreq/Kconfig"
2901
2902source "drivers/cpuidle/Kconfig"
2903
2904source "drivers/idle/Kconfig"
2905
2906endmenu
2907
2908menu "Bus options (PCI etc.)"
2909
2910choice
2911 prompt "PCI access mode"
2912 depends on X86_32 && PCI
2913 default PCI_GOANY
2914 help
2915 On PCI systems, the BIOS can be used to detect the PCI devices and
2916 determine their configuration. However, some old PCI motherboards
2917 have BIOS bugs and may crash if this is done. Also, some embedded
2918 PCI-based systems don't have any BIOS at all. Linux can also try to
2919 detect the PCI hardware directly without using the BIOS.
2920
2921 With this option, you can specify how Linux should detect the
2922 PCI devices. If you choose "BIOS", the BIOS will be used,
2923 if you choose "Direct", the BIOS won't be used, and if you
2924 choose "MMConfig", then PCI Express MMCONFIG will be used.
2925 If you choose "Any", the kernel will try MMCONFIG, then the
2926 direct access method and falls back to the BIOS if that doesn't
2927 work. If unsure, go with the default, which is "Any".
2928
2929config PCI_GOBIOS
2930 bool "BIOS"
2931
2932config PCI_GOMMCONFIG
2933 bool "MMConfig"
2934
2935config PCI_GODIRECT
2936 bool "Direct"
2937
2938config PCI_GOOLPC
2939 bool "OLPC XO-1"
2940 depends on OLPC
2941
2942config PCI_GOANY
2943 bool "Any"
2944
2945endchoice
2946
2947config PCI_BIOS
2948 def_bool y
2949 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2950
2951# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2952config PCI_DIRECT
2953 def_bool y
2954 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2955
2956config PCI_MMCONFIG
2957 bool "Support mmconfig PCI config space access" if X86_64
2958 default y
2959 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2960 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2961
2962config PCI_OLPC
2963 def_bool y
2964 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2965
2966config PCI_XEN
2967 def_bool y
2968 depends on PCI && XEN
2969
2970config MMCONF_FAM10H
2971 def_bool y
2972 depends on X86_64 && PCI_MMCONFIG && ACPI
2973
2974config PCI_CNB20LE_QUIRK
2975 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2976 depends on PCI
2977 help
2978 Read the PCI windows out of the CNB20LE host bridge. This allows
2979 PCI hotplug to work on systems with the CNB20LE chipset which do
2980 not have ACPI.
2981
2982 There's no public spec for this chipset, and this functionality
2983 is known to be incomplete.
2984
2985 You should say N unless you know you need this.
2986
2987config ISA_BUS
2988 bool "ISA bus support on modern systems" if EXPERT
2989 help
2990 Expose ISA bus device drivers and options available for selection and
2991 configuration. Enable this option if your target machine has an ISA
2992 bus. ISA is an older system, displaced by PCI and newer bus
2993 architectures -- if your target machine is modern, it probably does
2994 not have an ISA bus.
2995
2996 If unsure, say N.
2997
2998# x86_64 have no ISA slots, but can have ISA-style DMA.
2999config ISA_DMA_API
3000 bool "ISA-style DMA support" if (X86_64 && EXPERT)
3001 default y
3002 help
3003 Enables ISA-style DMA support for devices requiring such controllers.
3004 If unsure, say Y.
3005
3006if X86_32
3007
3008config ISA
3009 bool "ISA support"
3010 help
3011 Find out whether you have ISA slots on your motherboard. ISA is the
3012 name of a bus system, i.e. the way the CPU talks to the other stuff
3013 inside your box. Other bus systems are PCI, EISA, MicroChannel
3014 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
3015 newer boards don't support it. If you have ISA, say Y, otherwise N.
3016
3017config SCx200
3018 tristate "NatSemi SCx200 support"
3019 help
3020 This provides basic support for National Semiconductor's
3021 (now AMD's) Geode processors. The driver probes for the
3022 PCI-IDs of several on-chip devices, so its a good dependency
3023 for other scx200_* drivers.
3024
3025 If compiled as a module, the driver is named scx200.
3026
3027config SCx200HR_TIMER
3028 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
3029 depends on SCx200
3030 default y
3031 help
3032 This driver provides a clocksource built upon the on-chip
3033 27MHz high-resolution timer. Its also a workaround for
3034 NSC Geode SC-1100's buggy TSC, which loses time when the
3035 processor goes idle (as is done by the scheduler). The
3036 other workaround is idle=poll boot option.
3037
3038config OLPC
3039 bool "One Laptop Per Child support"
3040 depends on !X86_PAE
3041 select GPIOLIB
3042 select OF
3043 select OF_PROMTREE
3044 select IRQ_DOMAIN
3045 select OLPC_EC
3046 help
3047 Add support for detecting the unique features of the OLPC
3048 XO hardware.
3049
3050config OLPC_XO1_PM
3051 bool "OLPC XO-1 Power Management"
3052 depends on OLPC && MFD_CS5535=y && PM_SLEEP
3053 help
3054 Add support for poweroff and suspend of the OLPC XO-1 laptop.
3055
3056config OLPC_XO1_RTC
3057 bool "OLPC XO-1 Real Time Clock"
3058 depends on OLPC_XO1_PM && RTC_DRV_CMOS
3059 help
3060 Add support for the XO-1 real time clock, which can be used as a
3061 programmable wakeup source.
3062
3063config OLPC_XO1_SCI
3064 bool "OLPC XO-1 SCI extras"
3065 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3066 depends on INPUT=y
3067 select POWER_SUPPLY
3068 help
3069 Add support for SCI-based features of the OLPC XO-1 laptop:
3070 - EC-driven system wakeups
3071 - Power button
3072 - Ebook switch
3073 - Lid switch
3074 - AC adapter status updates
3075 - Battery status updates
3076
3077config OLPC_XO15_SCI
3078 bool "OLPC XO-1.5 SCI extras"
3079 depends on OLPC && ACPI
3080 select POWER_SUPPLY
3081 help
3082 Add support for SCI-based features of the OLPC XO-1.5 laptop:
3083 - EC-driven system wakeups
3084 - AC adapter status updates
3085 - Battery status updates
3086
3087config GEODE_COMMON
3088 bool
3089
3090config ALIX
3091 bool "PCEngines ALIX System Support (LED setup)"
3092 select GPIOLIB
3093 select GEODE_COMMON
3094 help
3095 This option enables system support for the PCEngines ALIX.
3096 At present this just sets up LEDs for GPIO control on
3097 ALIX2/3/6 boards. However, other system specific setup should
3098 get added here.
3099
3100 Note: You must still enable the drivers for GPIO and LED support
3101 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3102
3103 Note: You have to set alix.force=1 for boards with Award BIOS.
3104
3105config NET5501
3106 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3107 select GPIOLIB
3108 select GEODE_COMMON
3109 help
3110 This option enables system support for the Soekris Engineering net5501.
3111
3112config GEOS
3113 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3114 select GPIOLIB
3115 select GEODE_COMMON
3116 depends on DMI
3117 help
3118 This option enables system support for the Traverse Technologies GEOS.
3119
3120config TS5500
3121 bool "Technologic Systems TS-5500 platform support"
3122 depends on MELAN
3123 select CHECK_SIGNATURE
3124 select NEW_LEDS
3125 select LEDS_CLASS
3126 help
3127 This option enables system support for the Technologic Systems TS-5500.
3128
3129endif # X86_32
3130
3131config AMD_NB
3132 def_bool y
3133 depends on CPU_SUP_AMD && PCI
3134
3135endmenu
3136
3137menu "Binary Emulations"
3138
3139config IA32_EMULATION
3140 bool "IA32 Emulation"
3141 depends on X86_64
3142 select ARCH_WANT_OLD_COMPAT_IPC
3143 select BINFMT_ELF
3144 select COMPAT_OLD_SIGACTION
3145 help
3146 Include code to run legacy 32-bit programs under a
3147 64-bit kernel. You should likely turn this on, unless you're
3148 100% sure that you don't have any 32-bit programs left.
3149
3150config IA32_EMULATION_DEFAULT_DISABLED
3151 bool "IA32 emulation disabled by default"
3152 default n
3153 depends on IA32_EMULATION
3154 help
3155 Make IA32 emulation disabled by default. This prevents loading 32-bit
3156 processes and access to 32-bit syscalls. If unsure, leave it to its
3157 default value.
3158
3159config X86_X32_ABI
3160 bool "x32 ABI for 64-bit mode"
3161 depends on X86_64
3162 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3163 # compressed debug sections to x86_x32 properly:
3164 # https://github.com/ClangBuiltLinux/linux/issues/514
3165 # https://github.com/ClangBuiltLinux/linux/issues/1141
3166 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3167 help
3168 Include code to run binaries for the x32 native 32-bit ABI
3169 for 64-bit processors. An x32 process gets access to the
3170 full 64-bit register file and wide data path while leaving
3171 pointers at 32 bits for smaller memory footprint.
3172
3173config COMPAT_32
3174 def_bool y
3175 depends on IA32_EMULATION || X86_32
3176 select HAVE_UID16
3177 select OLD_SIGSUSPEND3
3178
3179config COMPAT
3180 def_bool y
3181 depends on IA32_EMULATION || X86_X32_ABI
3182
3183config COMPAT_FOR_U64_ALIGNMENT
3184 def_bool y
3185 depends on COMPAT
3186
3187endmenu
3188
3189config HAVE_ATOMIC_IOMAP
3190 def_bool y
3191 depends on X86_32
3192
3193source "arch/x86/kvm/Kconfig"
3194
3195source "arch/x86/Kconfig.assembler"
1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4 bool "64-bit kernel" if ARCH = "x86"
5 default ARCH != "i386"
6 ---help---
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11 def_bool y
12 depends on !64BIT
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLKSRC_I8253
16 select CLONE_BACKWARDS
17 select HAVE_AOUT
18 select HAVE_GENERIC_DMA_COHERENT
19 select MODULES_USE_ELF_REL
20 select OLD_SIGACTION
21
22config X86_64
23 def_bool y
24 depends on 64BIT
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
27 select ARCH_SUPPORTS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select X86_DEV_DMA_OPS
32 select ARCH_HAS_SYSCALL_WRAPPER
33
34#
35# Arch settings
36#
37# ( Note that options that are marked 'if X86_64' could in principle be
38# ported to 32-bit as well. )
39#
40config X86
41 def_bool y
42 #
43 # Note: keep this list sorted alphabetically
44 #
45 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
46 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
47 select ANON_INODES
48 select ARCH_CLOCKSOURCE_DATA
49 select ARCH_DISCARD_MEMBLOCK
50 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
51 select ARCH_HAS_DEBUG_VIRTUAL
52 select ARCH_HAS_DEVMEM_IS_ALLOWED
53 select ARCH_HAS_ELF_RANDOMIZE
54 select ARCH_HAS_FAST_MULTIPLIER
55 select ARCH_HAS_FILTER_PGPROT
56 select ARCH_HAS_FORTIFY_SOURCE
57 select ARCH_HAS_GCOV_PROFILE_ALL
58 select ARCH_HAS_KCOV if X86_64
59 select ARCH_HAS_MEMBARRIER_SYNC_CORE
60 select ARCH_HAS_PMEM_API if X86_64
61 select ARCH_HAS_REFCOUNT
62 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
63 select ARCH_HAS_SET_MEMORY
64 select ARCH_HAS_SG_CHAIN
65 select ARCH_HAS_STRICT_KERNEL_RWX
66 select ARCH_HAS_STRICT_MODULE_RWX
67 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
68 select ARCH_HAS_UBSAN_SANITIZE_ALL
69 select ARCH_HAS_ZONE_DEVICE if X86_64
70 select ARCH_HAVE_NMI_SAFE_CMPXCHG
71 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
72 select ARCH_MIGHT_HAVE_PC_PARPORT
73 select ARCH_MIGHT_HAVE_PC_SERIO
74 select ARCH_SUPPORTS_ATOMIC_RMW
75 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
76 select ARCH_USE_BUILTIN_BSWAP
77 select ARCH_USE_QUEUED_RWLOCKS
78 select ARCH_USE_QUEUED_SPINLOCKS
79 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
80 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
81 select ARCH_WANTS_THP_SWAP if X86_64
82 select BUILDTIME_EXTABLE_SORT
83 select CLKEVT_I8253
84 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
85 select CLOCKSOURCE_WATCHDOG
86 select DCACHE_WORD_ACCESS
87 select DMA_DIRECT_OPS
88 select EDAC_ATOMIC_SCRUB
89 select EDAC_SUPPORT
90 select GENERIC_CLOCKEVENTS
91 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
92 select GENERIC_CLOCKEVENTS_MIN_ADJUST
93 select GENERIC_CMOS_UPDATE
94 select GENERIC_CPU_AUTOPROBE
95 select GENERIC_CPU_VULNERABILITIES
96 select GENERIC_EARLY_IOREMAP
97 select GENERIC_FIND_FIRST_BIT
98 select GENERIC_IOMAP
99 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
100 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
101 select GENERIC_IRQ_MIGRATION if SMP
102 select GENERIC_IRQ_PROBE
103 select GENERIC_IRQ_RESERVATION_MODE
104 select GENERIC_IRQ_SHOW
105 select GENERIC_PENDING_IRQ if SMP
106 select GENERIC_SMP_IDLE_THREAD
107 select GENERIC_STRNCPY_FROM_USER
108 select GENERIC_STRNLEN_USER
109 select GENERIC_TIME_VSYSCALL
110 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
111 select HAVE_ACPI_APEI if ACPI
112 select HAVE_ACPI_APEI_NMI if ACPI
113 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
114 select HAVE_ARCH_AUDITSYSCALL
115 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
116 select HAVE_ARCH_JUMP_LABEL
117 select HAVE_ARCH_KASAN if X86_64
118 select HAVE_ARCH_KGDB
119 select HAVE_ARCH_MMAP_RND_BITS if MMU
120 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
121 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
122 select HAVE_ARCH_SECCOMP_FILTER
123 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
124 select HAVE_ARCH_TRACEHOOK
125 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
126 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
127 select HAVE_ARCH_VMAP_STACK if X86_64
128 select HAVE_ARCH_WITHIN_STACK_FRAMES
129 select HAVE_CC_STACKPROTECTOR
130 select HAVE_CMPXCHG_DOUBLE
131 select HAVE_CMPXCHG_LOCAL
132 select HAVE_CONTEXT_TRACKING if X86_64
133 select HAVE_COPY_THREAD_TLS
134 select HAVE_C_RECORDMCOUNT
135 select HAVE_DEBUG_KMEMLEAK
136 select HAVE_DEBUG_STACKOVERFLOW
137 select HAVE_DMA_API_DEBUG
138 select HAVE_DMA_CONTIGUOUS
139 select HAVE_DYNAMIC_FTRACE
140 select HAVE_DYNAMIC_FTRACE_WITH_REGS
141 select HAVE_EBPF_JIT if X86_64
142 select HAVE_EFFICIENT_UNALIGNED_ACCESS
143 select HAVE_EXIT_THREAD
144 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
145 select HAVE_FTRACE_MCOUNT_RECORD
146 select HAVE_FUNCTION_GRAPH_TRACER
147 select HAVE_FUNCTION_TRACER
148 select HAVE_GCC_PLUGINS
149 select HAVE_HW_BREAKPOINT
150 select HAVE_IDE
151 select HAVE_IOREMAP_PROT
152 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
153 select HAVE_IRQ_TIME_ACCOUNTING
154 select HAVE_KERNEL_BZIP2
155 select HAVE_KERNEL_GZIP
156 select HAVE_KERNEL_LZ4
157 select HAVE_KERNEL_LZMA
158 select HAVE_KERNEL_LZO
159 select HAVE_KERNEL_XZ
160 select HAVE_KPROBES
161 select HAVE_KPROBES_ON_FTRACE
162 select HAVE_FUNCTION_ERROR_INJECTION
163 select HAVE_KRETPROBES
164 select HAVE_KVM
165 select HAVE_LIVEPATCH if X86_64
166 select HAVE_MEMBLOCK
167 select HAVE_MEMBLOCK_NODE_MAP
168 select HAVE_MIXED_BREAKPOINTS_REGS
169 select HAVE_MOD_ARCH_SPECIFIC
170 select HAVE_NMI
171 select HAVE_OPROFILE
172 select HAVE_OPTPROBES
173 select HAVE_PCSPKR_PLATFORM
174 select HAVE_PERF_EVENTS
175 select HAVE_PERF_EVENTS_NMI
176 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
177 select HAVE_PERF_REGS
178 select HAVE_PERF_USER_STACK_DUMP
179 select HAVE_RCU_TABLE_FREE
180 select HAVE_REGS_AND_STACK_ACCESS_API
181 select HAVE_RELIABLE_STACKTRACE if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
182 select HAVE_STACK_VALIDATION if X86_64
183 select HAVE_SYSCALL_TRACEPOINTS
184 select HAVE_UNSTABLE_SCHED_CLOCK
185 select HAVE_USER_RETURN_NOTIFIER
186 select IRQ_FORCED_THREADING
187 select PCI_LOCKLESS_CONFIG
188 select PERF_EVENTS
189 select RTC_LIB
190 select RTC_MC146818_LIB
191 select SPARSE_IRQ
192 select SRCU
193 select SYSCTL_EXCEPTION_TRACE
194 select THREAD_INFO_IN_TASK
195 select USER_STACKTRACE_SUPPORT
196 select VIRT_TO_BUS
197 select X86_FEATURE_NAMES if PROC_FS
198
199config INSTRUCTION_DECODER
200 def_bool y
201 depends on KPROBES || PERF_EVENTS || UPROBES
202
203config OUTPUT_FORMAT
204 string
205 default "elf32-i386" if X86_32
206 default "elf64-x86-64" if X86_64
207
208config ARCH_DEFCONFIG
209 string
210 default "arch/x86/configs/i386_defconfig" if X86_32
211 default "arch/x86/configs/x86_64_defconfig" if X86_64
212
213config LOCKDEP_SUPPORT
214 def_bool y
215
216config STACKTRACE_SUPPORT
217 def_bool y
218
219config MMU
220 def_bool y
221
222config ARCH_MMAP_RND_BITS_MIN
223 default 28 if 64BIT
224 default 8
225
226config ARCH_MMAP_RND_BITS_MAX
227 default 32 if 64BIT
228 default 16
229
230config ARCH_MMAP_RND_COMPAT_BITS_MIN
231 default 8
232
233config ARCH_MMAP_RND_COMPAT_BITS_MAX
234 default 16
235
236config SBUS
237 bool
238
239config NEED_DMA_MAP_STATE
240 def_bool y
241 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
242
243config NEED_SG_DMA_LENGTH
244 def_bool y
245
246config GENERIC_ISA_DMA
247 def_bool y
248 depends on ISA_DMA_API
249
250config GENERIC_BUG
251 def_bool y
252 depends on BUG
253 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
254
255config GENERIC_BUG_RELATIVE_POINTERS
256 bool
257
258config GENERIC_HWEIGHT
259 def_bool y
260
261config ARCH_MAY_HAVE_PC_FDC
262 def_bool y
263 depends on ISA_DMA_API
264
265config RWSEM_XCHGADD_ALGORITHM
266 def_bool y
267
268config GENERIC_CALIBRATE_DELAY
269 def_bool y
270
271config ARCH_HAS_CPU_RELAX
272 def_bool y
273
274config ARCH_HAS_CACHE_LINE_SIZE
275 def_bool y
276
277config ARCH_HAS_FILTER_PGPROT
278 def_bool y
279
280config HAVE_SETUP_PER_CPU_AREA
281 def_bool y
282
283config NEED_PER_CPU_EMBED_FIRST_CHUNK
284 def_bool y
285
286config NEED_PER_CPU_PAGE_FIRST_CHUNK
287 def_bool y
288
289config ARCH_HIBERNATION_POSSIBLE
290 def_bool y
291
292config ARCH_SUSPEND_POSSIBLE
293 def_bool y
294
295config ARCH_WANT_HUGE_PMD_SHARE
296 def_bool y
297
298config ARCH_WANT_GENERAL_HUGETLB
299 def_bool y
300
301config ZONE_DMA32
302 def_bool y if X86_64
303
304config AUDIT_ARCH
305 def_bool y if X86_64
306
307config ARCH_SUPPORTS_OPTIMIZED_INLINING
308 def_bool y
309
310config ARCH_SUPPORTS_DEBUG_PAGEALLOC
311 def_bool y
312
313config KASAN_SHADOW_OFFSET
314 hex
315 depends on KASAN
316 default 0xdffffc0000000000
317
318config HAVE_INTEL_TXT
319 def_bool y
320 depends on INTEL_IOMMU && ACPI
321
322config X86_32_SMP
323 def_bool y
324 depends on X86_32 && SMP
325
326config X86_64_SMP
327 def_bool y
328 depends on X86_64 && SMP
329
330config X86_32_LAZY_GS
331 def_bool y
332 depends on X86_32 && CC_STACKPROTECTOR_NONE
333
334config ARCH_SUPPORTS_UPROBES
335 def_bool y
336
337config FIX_EARLYCON_MEM
338 def_bool y
339
340config PGTABLE_LEVELS
341 int
342 default 5 if X86_5LEVEL
343 default 4 if X86_64
344 default 3 if X86_PAE
345 default 2
346
347source "init/Kconfig"
348source "kernel/Kconfig.freezer"
349
350menu "Processor type and features"
351
352config ZONE_DMA
353 bool "DMA memory allocation support" if EXPERT
354 default y
355 help
356 DMA memory allocation support allows devices with less than 32-bit
357 addressing to allocate within the first 16MB of address space.
358 Disable if no such devices will be used.
359
360 If unsure, say Y.
361
362config SMP
363 bool "Symmetric multi-processing support"
364 ---help---
365 This enables support for systems with more than one CPU. If you have
366 a system with only one CPU, say N. If you have a system with more
367 than one CPU, say Y.
368
369 If you say N here, the kernel will run on uni- and multiprocessor
370 machines, but will use only one CPU of a multiprocessor machine. If
371 you say Y here, the kernel will run on many, but not all,
372 uniprocessor machines. On a uniprocessor machine, the kernel
373 will run faster if you say N here.
374
375 Note that if you say Y here and choose architecture "586" or
376 "Pentium" under "Processor family", the kernel will not work on 486
377 architectures. Similarly, multiprocessor kernels for the "PPro"
378 architecture may not work on all Pentium based boards.
379
380 People using multiprocessor machines who say Y here should also say
381 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
382 Management" code will be disabled if you say Y here.
383
384 See also <file:Documentation/x86/i386/IO-APIC.txt>,
385 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
386 <http://www.tldp.org/docs.html#howto>.
387
388 If you don't know what to do here, say N.
389
390config X86_FEATURE_NAMES
391 bool "Processor feature human-readable names" if EMBEDDED
392 default y
393 ---help---
394 This option compiles in a table of x86 feature bits and corresponding
395 names. This is required to support /proc/cpuinfo and a few kernel
396 messages. You can disable this to save space, at the expense of
397 making those few kernel messages show numeric feature bits instead.
398
399 If in doubt, say Y.
400
401config X86_X2APIC
402 bool "Support x2apic"
403 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
404 ---help---
405 This enables x2apic support on CPUs that have this feature.
406
407 This allows 32-bit apic IDs (so it can support very large systems),
408 and accesses the local apic via MSRs not via mmio.
409
410 If you don't know what to do here, say N.
411
412config X86_MPPARSE
413 bool "Enable MPS table" if ACPI || SFI
414 default y
415 depends on X86_LOCAL_APIC
416 ---help---
417 For old smp systems that do not have proper acpi support. Newer systems
418 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
419
420config GOLDFISH
421 def_bool y
422 depends on X86_GOLDFISH
423
424config RETPOLINE
425 bool "Avoid speculative indirect branches in kernel"
426 default y
427 select STACK_VALIDATION if HAVE_STACK_VALIDATION
428 help
429 Compile kernel with the retpoline compiler options to guard against
430 kernel-to-user data leaks by avoiding speculative indirect
431 branches. Requires a compiler with -mindirect-branch=thunk-extern
432 support for full protection. The kernel may run slower.
433
434 Without compiler support, at least indirect branches in assembler
435 code are eliminated. Since this includes the syscall entry path,
436 it is not entirely pointless.
437
438config INTEL_RDT
439 bool "Intel Resource Director Technology support"
440 default n
441 depends on X86 && CPU_SUP_INTEL
442 select KERNFS
443 help
444 Select to enable resource allocation and monitoring which are
445 sub-features of Intel Resource Director Technology(RDT). More
446 information about RDT can be found in the Intel x86
447 Architecture Software Developer Manual.
448
449 Say N if unsure.
450
451if X86_32
452config X86_BIGSMP
453 bool "Support for big SMP systems with more than 8 CPUs"
454 depends on SMP
455 ---help---
456 This option is needed for the systems that have more than 8 CPUs
457
458config X86_EXTENDED_PLATFORM
459 bool "Support for extended (non-PC) x86 platforms"
460 default y
461 ---help---
462 If you disable this option then the kernel will only support
463 standard PC platforms. (which covers the vast majority of
464 systems out there.)
465
466 If you enable this option then you'll be able to select support
467 for the following (non-PC) 32 bit x86 platforms:
468 Goldfish (Android emulator)
469 AMD Elan
470 RDC R-321x SoC
471 SGI 320/540 (Visual Workstation)
472 STA2X11-based (e.g. Northville)
473 Moorestown MID devices
474
475 If you have one of these systems, or if you want to build a
476 generic distribution kernel, say Y here - otherwise say N.
477endif
478
479if X86_64
480config X86_EXTENDED_PLATFORM
481 bool "Support for extended (non-PC) x86 platforms"
482 default y
483 ---help---
484 If you disable this option then the kernel will only support
485 standard PC platforms. (which covers the vast majority of
486 systems out there.)
487
488 If you enable this option then you'll be able to select support
489 for the following (non-PC) 64 bit x86 platforms:
490 Numascale NumaChip
491 ScaleMP vSMP
492 SGI Ultraviolet
493
494 If you have one of these systems, or if you want to build a
495 generic distribution kernel, say Y here - otherwise say N.
496endif
497# This is an alphabetically sorted list of 64 bit extended platforms
498# Please maintain the alphabetic order if and when there are additions
499config X86_NUMACHIP
500 bool "Numascale NumaChip"
501 depends on X86_64
502 depends on X86_EXTENDED_PLATFORM
503 depends on NUMA
504 depends on SMP
505 depends on X86_X2APIC
506 depends on PCI_MMCONFIG
507 ---help---
508 Adds support for Numascale NumaChip large-SMP systems. Needed to
509 enable more than ~168 cores.
510 If you don't have one of these, you should say N here.
511
512config X86_VSMP
513 bool "ScaleMP vSMP"
514 select HYPERVISOR_GUEST
515 select PARAVIRT
516 depends on X86_64 && PCI
517 depends on X86_EXTENDED_PLATFORM
518 depends on SMP
519 ---help---
520 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
521 supposed to run on these EM64T-based machines. Only choose this option
522 if you have one of these machines.
523
524config X86_UV
525 bool "SGI Ultraviolet"
526 depends on X86_64
527 depends on X86_EXTENDED_PLATFORM
528 depends on NUMA
529 depends on EFI
530 depends on X86_X2APIC
531 depends on PCI
532 ---help---
533 This option is needed in order to support SGI Ultraviolet systems.
534 If you don't have one of these, you should say N here.
535
536# Following is an alphabetically sorted list of 32 bit extended platforms
537# Please maintain the alphabetic order if and when there are additions
538
539config X86_GOLDFISH
540 bool "Goldfish (Virtual Platform)"
541 depends on X86_EXTENDED_PLATFORM
542 ---help---
543 Enable support for the Goldfish virtual platform used primarily
544 for Android development. Unless you are building for the Android
545 Goldfish emulator say N here.
546
547config X86_INTEL_CE
548 bool "CE4100 TV platform"
549 depends on PCI
550 depends on PCI_GODIRECT
551 depends on X86_IO_APIC
552 depends on X86_32
553 depends on X86_EXTENDED_PLATFORM
554 select X86_REBOOTFIXUPS
555 select OF
556 select OF_EARLY_FLATTREE
557 ---help---
558 Select for the Intel CE media processor (CE4100) SOC.
559 This option compiles in support for the CE4100 SOC for settop
560 boxes and media devices.
561
562config X86_INTEL_MID
563 bool "Intel MID platform support"
564 depends on X86_EXTENDED_PLATFORM
565 depends on X86_PLATFORM_DEVICES
566 depends on PCI
567 depends on X86_64 || (PCI_GOANY && X86_32)
568 depends on X86_IO_APIC
569 select SFI
570 select I2C
571 select DW_APB_TIMER
572 select APB_TIMER
573 select INTEL_SCU_IPC
574 select MFD_INTEL_MSIC
575 ---help---
576 Select to build a kernel capable of supporting Intel MID (Mobile
577 Internet Device) platform systems which do not have the PCI legacy
578 interfaces. If you are building for a PC class system say N here.
579
580 Intel MID platforms are based on an Intel processor and chipset which
581 consume less power than most of the x86 derivatives.
582
583config X86_INTEL_QUARK
584 bool "Intel Quark platform support"
585 depends on X86_32
586 depends on X86_EXTENDED_PLATFORM
587 depends on X86_PLATFORM_DEVICES
588 depends on X86_TSC
589 depends on PCI
590 depends on PCI_GOANY
591 depends on X86_IO_APIC
592 select IOSF_MBI
593 select INTEL_IMR
594 select COMMON_CLK
595 ---help---
596 Select to include support for Quark X1000 SoC.
597 Say Y here if you have a Quark based system such as the Arduino
598 compatible Intel Galileo.
599
600config X86_INTEL_LPSS
601 bool "Intel Low Power Subsystem Support"
602 depends on X86 && ACPI
603 select COMMON_CLK
604 select PINCTRL
605 select IOSF_MBI
606 ---help---
607 Select to build support for Intel Low Power Subsystem such as
608 found on Intel Lynxpoint PCH. Selecting this option enables
609 things like clock tree (common clock framework) and pincontrol
610 which are needed by the LPSS peripheral drivers.
611
612config X86_AMD_PLATFORM_DEVICE
613 bool "AMD ACPI2Platform devices support"
614 depends on ACPI
615 select COMMON_CLK
616 select PINCTRL
617 ---help---
618 Select to interpret AMD specific ACPI device to platform device
619 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
620 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
621 implemented under PINCTRL subsystem.
622
623config IOSF_MBI
624 tristate "Intel SoC IOSF Sideband support for SoC platforms"
625 depends on PCI
626 ---help---
627 This option enables sideband register access support for Intel SoC
628 platforms. On these platforms the IOSF sideband is used in lieu of
629 MSR's for some register accesses, mostly but not limited to thermal
630 and power. Drivers may query the availability of this device to
631 determine if they need the sideband in order to work on these
632 platforms. The sideband is available on the following SoC products.
633 This list is not meant to be exclusive.
634 - BayTrail
635 - Braswell
636 - Quark
637
638 You should say Y if you are running a kernel on one of these SoC's.
639
640config IOSF_MBI_DEBUG
641 bool "Enable IOSF sideband access through debugfs"
642 depends on IOSF_MBI && DEBUG_FS
643 ---help---
644 Select this option to expose the IOSF sideband access registers (MCR,
645 MDR, MCRX) through debugfs to write and read register information from
646 different units on the SoC. This is most useful for obtaining device
647 state information for debug and analysis. As this is a general access
648 mechanism, users of this option would have specific knowledge of the
649 device they want to access.
650
651 If you don't require the option or are in doubt, say N.
652
653config X86_RDC321X
654 bool "RDC R-321x SoC"
655 depends on X86_32
656 depends on X86_EXTENDED_PLATFORM
657 select M486
658 select X86_REBOOTFIXUPS
659 ---help---
660 This option is needed for RDC R-321x system-on-chip, also known
661 as R-8610-(G).
662 If you don't have one of these chips, you should say N here.
663
664config X86_32_NON_STANDARD
665 bool "Support non-standard 32-bit SMP architectures"
666 depends on X86_32 && SMP
667 depends on X86_EXTENDED_PLATFORM
668 ---help---
669 This option compiles in the bigsmp and STA2X11 default
670 subarchitectures. It is intended for a generic binary
671 kernel. If you select them all, kernel will probe it one by
672 one and will fallback to default.
673
674# Alphabetically sorted list of Non standard 32 bit platforms
675
676config X86_SUPPORTS_MEMORY_FAILURE
677 def_bool y
678 # MCE code calls memory_failure():
679 depends on X86_MCE
680 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
681 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
682 depends on X86_64 || !SPARSEMEM
683 select ARCH_SUPPORTS_MEMORY_FAILURE
684
685config STA2X11
686 bool "STA2X11 Companion Chip Support"
687 depends on X86_32_NON_STANDARD && PCI
688 select ARCH_HAS_PHYS_TO_DMA
689 select X86_DEV_DMA_OPS
690 select X86_DMA_REMAP
691 select SWIOTLB
692 select MFD_STA2X11
693 select GPIOLIB
694 default n
695 ---help---
696 This adds support for boards based on the STA2X11 IO-Hub,
697 a.k.a. "ConneXt". The chip is used in place of the standard
698 PC chipset, so all "standard" peripherals are missing. If this
699 option is selected the kernel will still be able to boot on
700 standard PC machines.
701
702config X86_32_IRIS
703 tristate "Eurobraille/Iris poweroff module"
704 depends on X86_32
705 ---help---
706 The Iris machines from EuroBraille do not have APM or ACPI support
707 to shut themselves down properly. A special I/O sequence is
708 needed to do so, which is what this module does at
709 kernel shutdown.
710
711 This is only for Iris machines from EuroBraille.
712
713 If unused, say N.
714
715config SCHED_OMIT_FRAME_POINTER
716 def_bool y
717 prompt "Single-depth WCHAN output"
718 depends on X86
719 ---help---
720 Calculate simpler /proc/<PID>/wchan values. If this option
721 is disabled then wchan values will recurse back to the
722 caller function. This provides more accurate wchan values,
723 at the expense of slightly more scheduling overhead.
724
725 If in doubt, say "Y".
726
727menuconfig HYPERVISOR_GUEST
728 bool "Linux guest support"
729 ---help---
730 Say Y here to enable options for running Linux under various hyper-
731 visors. This option enables basic hypervisor detection and platform
732 setup.
733
734 If you say N, all options in this submenu will be skipped and
735 disabled, and Linux guest support won't be built in.
736
737if HYPERVISOR_GUEST
738
739config PARAVIRT
740 bool "Enable paravirtualization code"
741 ---help---
742 This changes the kernel so it can modify itself when it is run
743 under a hypervisor, potentially improving performance significantly
744 over full virtualization. However, when run without a hypervisor
745 the kernel is theoretically slower and slightly larger.
746
747config PARAVIRT_DEBUG
748 bool "paravirt-ops debugging"
749 depends on PARAVIRT && DEBUG_KERNEL
750 ---help---
751 Enable to debug paravirt_ops internals. Specifically, BUG if
752 a paravirt_op is missing when it is called.
753
754config PARAVIRT_SPINLOCKS
755 bool "Paravirtualization layer for spinlocks"
756 depends on PARAVIRT && SMP
757 ---help---
758 Paravirtualized spinlocks allow a pvops backend to replace the
759 spinlock implementation with something virtualization-friendly
760 (for example, block the virtual CPU rather than spinning).
761
762 It has a minimal impact on native kernels and gives a nice performance
763 benefit on paravirtualized KVM / Xen kernels.
764
765 If you are unsure how to answer this question, answer Y.
766
767config QUEUED_LOCK_STAT
768 bool "Paravirt queued spinlock statistics"
769 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
770 ---help---
771 Enable the collection of statistical data on the slowpath
772 behavior of paravirtualized queued spinlocks and report
773 them on debugfs.
774
775source "arch/x86/xen/Kconfig"
776
777config KVM_GUEST
778 bool "KVM Guest support (including kvmclock)"
779 depends on PARAVIRT
780 select PARAVIRT_CLOCK
781 default y
782 ---help---
783 This option enables various optimizations for running under the KVM
784 hypervisor. It includes a paravirtualized clock, so that instead
785 of relying on a PIT (or probably other) emulation by the
786 underlying device model, the host provides the guest with
787 timing infrastructure such as time of day, and system time
788
789config KVM_DEBUG_FS
790 bool "Enable debug information for KVM Guests in debugfs"
791 depends on KVM_GUEST && DEBUG_FS
792 default n
793 ---help---
794 This option enables collection of various statistics for KVM guest.
795 Statistics are displayed in debugfs filesystem. Enabling this option
796 may incur significant overhead.
797
798config PARAVIRT_TIME_ACCOUNTING
799 bool "Paravirtual steal time accounting"
800 depends on PARAVIRT
801 default n
802 ---help---
803 Select this option to enable fine granularity task steal time
804 accounting. Time spent executing other tasks in parallel with
805 the current vCPU is discounted from the vCPU power. To account for
806 that, there can be a small performance impact.
807
808 If in doubt, say N here.
809
810config PARAVIRT_CLOCK
811 bool
812
813config JAILHOUSE_GUEST
814 bool "Jailhouse non-root cell support"
815 depends on X86_64 && PCI
816 select X86_PM_TIMER
817 ---help---
818 This option allows to run Linux as guest in a Jailhouse non-root
819 cell. You can leave this option disabled if you only want to start
820 Jailhouse and run Linux afterwards in the root cell.
821
822endif #HYPERVISOR_GUEST
823
824config NO_BOOTMEM
825 def_bool y
826
827source "arch/x86/Kconfig.cpu"
828
829config HPET_TIMER
830 def_bool X86_64
831 prompt "HPET Timer Support" if X86_32
832 ---help---
833 Use the IA-PC HPET (High Precision Event Timer) to manage
834 time in preference to the PIT and RTC, if a HPET is
835 present.
836 HPET is the next generation timer replacing legacy 8254s.
837 The HPET provides a stable time base on SMP
838 systems, unlike the TSC, but it is more expensive to access,
839 as it is off-chip. The interface used is documented
840 in the HPET spec, revision 1.
841
842 You can safely choose Y here. However, HPET will only be
843 activated if the platform and the BIOS support this feature.
844 Otherwise the 8254 will be used for timing services.
845
846 Choose N to continue using the legacy 8254 timer.
847
848config HPET_EMULATE_RTC
849 def_bool y
850 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
851
852config APB_TIMER
853 def_bool y if X86_INTEL_MID
854 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
855 select DW_APB_TIMER
856 depends on X86_INTEL_MID && SFI
857 help
858 APB timer is the replacement for 8254, HPET on X86 MID platforms.
859 The APBT provides a stable time base on SMP
860 systems, unlike the TSC, but it is more expensive to access,
861 as it is off-chip. APB timers are always running regardless of CPU
862 C states, they are used as per CPU clockevent device when possible.
863
864# Mark as expert because too many people got it wrong.
865# The code disables itself when not needed.
866config DMI
867 default y
868 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
869 bool "Enable DMI scanning" if EXPERT
870 ---help---
871 Enabled scanning of DMI to identify machine quirks. Say Y
872 here unless you have verified that your setup is not
873 affected by entries in the DMI blacklist. Required by PNP
874 BIOS code.
875
876config GART_IOMMU
877 bool "Old AMD GART IOMMU support"
878 select SWIOTLB
879 depends on X86_64 && PCI && AMD_NB
880 ---help---
881 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
882 GART based hardware IOMMUs.
883
884 The GART supports full DMA access for devices with 32-bit access
885 limitations, on systems with more than 3 GB. This is usually needed
886 for USB, sound, many IDE/SATA chipsets and some other devices.
887
888 Newer systems typically have a modern AMD IOMMU, supported via
889 the CONFIG_AMD_IOMMU=y config option.
890
891 In normal configurations this driver is only active when needed:
892 there's more than 3 GB of memory and the system contains a
893 32-bit limited device.
894
895 If unsure, say Y.
896
897config CALGARY_IOMMU
898 bool "IBM Calgary IOMMU support"
899 select SWIOTLB
900 depends on X86_64 && PCI
901 ---help---
902 Support for hardware IOMMUs in IBM's xSeries x366 and x460
903 systems. Needed to run systems with more than 3GB of memory
904 properly with 32-bit PCI devices that do not support DAC
905 (Double Address Cycle). Calgary also supports bus level
906 isolation, where all DMAs pass through the IOMMU. This
907 prevents them from going anywhere except their intended
908 destination. This catches hard-to-find kernel bugs and
909 mis-behaving drivers and devices that do not use the DMA-API
910 properly to set up their DMA buffers. The IOMMU can be
911 turned off at boot time with the iommu=off parameter.
912 Normally the kernel will make the right choice by itself.
913 If unsure, say Y.
914
915config CALGARY_IOMMU_ENABLED_BY_DEFAULT
916 def_bool y
917 prompt "Should Calgary be enabled by default?"
918 depends on CALGARY_IOMMU
919 ---help---
920 Should Calgary be enabled by default? if you choose 'y', Calgary
921 will be used (if it exists). If you choose 'n', Calgary will not be
922 used even if it exists. If you choose 'n' and would like to use
923 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
924 If unsure, say Y.
925
926# need this always selected by IOMMU for the VIA workaround
927config SWIOTLB
928 def_bool y if X86_64
929 ---help---
930 Support for software bounce buffers used on x86-64 systems
931 which don't have a hardware IOMMU. Using this PCI devices
932 which can only access 32-bits of memory can be used on systems
933 with more than 3 GB of memory.
934 If unsure, say Y.
935
936config IOMMU_HELPER
937 def_bool y
938 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
939
940config MAXSMP
941 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
942 depends on X86_64 && SMP && DEBUG_KERNEL
943 select CPUMASK_OFFSTACK
944 ---help---
945 Enable maximum number of CPUS and NUMA Nodes for this architecture.
946 If unsure, say N.
947
948#
949# The maximum number of CPUs supported:
950#
951# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
952# and which can be configured interactively in the
953# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
954#
955# The ranges are different on 32-bit and 64-bit kernels, depending on
956# hardware capabilities and scalability features of the kernel.
957#
958# ( If MAXSMP is enabled we just use the highest possible value and disable
959# interactive configuration. )
960#
961
962config NR_CPUS_RANGE_BEGIN
963 int
964 default NR_CPUS_RANGE_END if MAXSMP
965 default 1 if !SMP
966 default 2
967
968config NR_CPUS_RANGE_END
969 int
970 depends on X86_32
971 default 64 if SMP && X86_BIGSMP
972 default 8 if SMP && !X86_BIGSMP
973 default 1 if !SMP
974
975config NR_CPUS_RANGE_END
976 int
977 depends on X86_64
978 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
979 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
980 default 1 if !SMP
981
982config NR_CPUS_DEFAULT
983 int
984 depends on X86_32
985 default 32 if X86_BIGSMP
986 default 8 if SMP
987 default 1 if !SMP
988
989config NR_CPUS_DEFAULT
990 int
991 depends on X86_64
992 default 8192 if MAXSMP
993 default 64 if SMP
994 default 1 if !SMP
995
996config NR_CPUS
997 int "Maximum number of CPUs" if SMP && !MAXSMP
998 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
999 default NR_CPUS_DEFAULT
1000 ---help---
1001 This allows you to specify the maximum number of CPUs which this
1002 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1003 supported value is 8192, otherwise the maximum value is 512. The
1004 minimum value which makes sense is 2.
1005
1006 This is purely to save memory: each supported CPU adds about 8KB
1007 to the kernel image.
1008
1009config SCHED_SMT
1010 bool "SMT (Hyperthreading) scheduler support"
1011 depends on SMP
1012 ---help---
1013 SMT scheduler support improves the CPU scheduler's decision making
1014 when dealing with Intel Pentium 4 chips with HyperThreading at a
1015 cost of slightly increased overhead in some places. If unsure say
1016 N here.
1017
1018config SCHED_MC
1019 def_bool y
1020 prompt "Multi-core scheduler support"
1021 depends on SMP
1022 ---help---
1023 Multi-core scheduler support improves the CPU scheduler's decision
1024 making when dealing with multi-core CPU chips at a cost of slightly
1025 increased overhead in some places. If unsure say N here.
1026
1027config SCHED_MC_PRIO
1028 bool "CPU core priorities scheduler support"
1029 depends on SCHED_MC && CPU_SUP_INTEL
1030 select X86_INTEL_PSTATE
1031 select CPU_FREQ
1032 default y
1033 ---help---
1034 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1035 core ordering determined at manufacturing time, which allows
1036 certain cores to reach higher turbo frequencies (when running
1037 single threaded workloads) than others.
1038
1039 Enabling this kernel feature teaches the scheduler about
1040 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1041 scheduler's CPU selection logic accordingly, so that higher
1042 overall system performance can be achieved.
1043
1044 This feature will have no effect on CPUs without this feature.
1045
1046 If unsure say Y here.
1047
1048source "kernel/Kconfig.preempt"
1049
1050config UP_LATE_INIT
1051 def_bool y
1052 depends on !SMP && X86_LOCAL_APIC
1053
1054config X86_UP_APIC
1055 bool "Local APIC support on uniprocessors" if !PCI_MSI
1056 default PCI_MSI
1057 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1058 ---help---
1059 A local APIC (Advanced Programmable Interrupt Controller) is an
1060 integrated interrupt controller in the CPU. If you have a single-CPU
1061 system which has a processor with a local APIC, you can say Y here to
1062 enable and use it. If you say Y here even though your machine doesn't
1063 have a local APIC, then the kernel will still run with no slowdown at
1064 all. The local APIC supports CPU-generated self-interrupts (timer,
1065 performance counters), and the NMI watchdog which detects hard
1066 lockups.
1067
1068config X86_UP_IOAPIC
1069 bool "IO-APIC support on uniprocessors"
1070 depends on X86_UP_APIC
1071 ---help---
1072 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1073 SMP-capable replacement for PC-style interrupt controllers. Most
1074 SMP systems and many recent uniprocessor systems have one.
1075
1076 If you have a single-CPU system with an IO-APIC, you can say Y here
1077 to use it. If you say Y here even though your machine doesn't have
1078 an IO-APIC, then the kernel will still run with no slowdown at all.
1079
1080config X86_LOCAL_APIC
1081 def_bool y
1082 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1083 select IRQ_DOMAIN_HIERARCHY
1084 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1085
1086config X86_IO_APIC
1087 def_bool y
1088 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1089
1090config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1091 bool "Reroute for broken boot IRQs"
1092 depends on X86_IO_APIC
1093 ---help---
1094 This option enables a workaround that fixes a source of
1095 spurious interrupts. This is recommended when threaded
1096 interrupt handling is used on systems where the generation of
1097 superfluous "boot interrupts" cannot be disabled.
1098
1099 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1100 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1101 kernel does during interrupt handling). On chipsets where this
1102 boot IRQ generation cannot be disabled, this workaround keeps
1103 the original IRQ line masked so that only the equivalent "boot
1104 IRQ" is delivered to the CPUs. The workaround also tells the
1105 kernel to set up the IRQ handler on the boot IRQ line. In this
1106 way only one interrupt is delivered to the kernel. Otherwise
1107 the spurious second interrupt may cause the kernel to bring
1108 down (vital) interrupt lines.
1109
1110 Only affects "broken" chipsets. Interrupt sharing may be
1111 increased on these systems.
1112
1113config X86_MCE
1114 bool "Machine Check / overheating reporting"
1115 select GENERIC_ALLOCATOR
1116 default y
1117 ---help---
1118 Machine Check support allows the processor to notify the
1119 kernel if it detects a problem (e.g. overheating, data corruption).
1120 The action the kernel takes depends on the severity of the problem,
1121 ranging from warning messages to halting the machine.
1122
1123config X86_MCELOG_LEGACY
1124 bool "Support for deprecated /dev/mcelog character device"
1125 depends on X86_MCE
1126 ---help---
1127 Enable support for /dev/mcelog which is needed by the old mcelog
1128 userspace logging daemon. Consider switching to the new generation
1129 rasdaemon solution.
1130
1131config X86_MCE_INTEL
1132 def_bool y
1133 prompt "Intel MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC
1135 ---help---
1136 Additional support for intel specific MCE features such as
1137 the thermal monitor.
1138
1139config X86_MCE_AMD
1140 def_bool y
1141 prompt "AMD MCE features"
1142 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1143 ---help---
1144 Additional support for AMD specific MCE features such as
1145 the DRAM Error Threshold.
1146
1147config X86_ANCIENT_MCE
1148 bool "Support for old Pentium 5 / WinChip machine checks"
1149 depends on X86_32 && X86_MCE
1150 ---help---
1151 Include support for machine check handling on old Pentium 5 or WinChip
1152 systems. These typically need to be enabled explicitly on the command
1153 line.
1154
1155config X86_MCE_THRESHOLD
1156 depends on X86_MCE_AMD || X86_MCE_INTEL
1157 def_bool y
1158
1159config X86_MCE_INJECT
1160 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1161 tristate "Machine check injector support"
1162 ---help---
1163 Provide support for injecting machine checks for testing purposes.
1164 If you don't know what a machine check is and you don't do kernel
1165 QA it is safe to say n.
1166
1167config X86_THERMAL_VECTOR
1168 def_bool y
1169 depends on X86_MCE_INTEL
1170
1171source "arch/x86/events/Kconfig"
1172
1173config X86_LEGACY_VM86
1174 bool "Legacy VM86 support"
1175 default n
1176 depends on X86_32
1177 ---help---
1178 This option allows user programs to put the CPU into V8086
1179 mode, which is an 80286-era approximation of 16-bit real mode.
1180
1181 Some very old versions of X and/or vbetool require this option
1182 for user mode setting. Similarly, DOSEMU will use it if
1183 available to accelerate real mode DOS programs. However, any
1184 recent version of DOSEMU, X, or vbetool should be fully
1185 functional even without kernel VM86 support, as they will all
1186 fall back to software emulation. Nevertheless, if you are using
1187 a 16-bit DOS program where 16-bit performance matters, vm86
1188 mode might be faster than emulation and you might want to
1189 enable this option.
1190
1191 Note that any app that works on a 64-bit kernel is unlikely to
1192 need this option, as 64-bit kernels don't, and can't, support
1193 V8086 mode. This option is also unrelated to 16-bit protected
1194 mode and is not needed to run most 16-bit programs under Wine.
1195
1196 Enabling this option increases the complexity of the kernel
1197 and slows down exception handling a tiny bit.
1198
1199 If unsure, say N here.
1200
1201config VM86
1202 bool
1203 default X86_LEGACY_VM86
1204
1205config X86_16BIT
1206 bool "Enable support for 16-bit segments" if EXPERT
1207 default y
1208 depends on MODIFY_LDT_SYSCALL
1209 ---help---
1210 This option is required by programs like Wine to run 16-bit
1211 protected mode legacy code on x86 processors. Disabling
1212 this option saves about 300 bytes on i386, or around 6K text
1213 plus 16K runtime memory on x86-64,
1214
1215config X86_ESPFIX32
1216 def_bool y
1217 depends on X86_16BIT && X86_32
1218
1219config X86_ESPFIX64
1220 def_bool y
1221 depends on X86_16BIT && X86_64
1222
1223config X86_VSYSCALL_EMULATION
1224 bool "Enable vsyscall emulation" if EXPERT
1225 default y
1226 depends on X86_64
1227 ---help---
1228 This enables emulation of the legacy vsyscall page. Disabling
1229 it is roughly equivalent to booting with vsyscall=none, except
1230 that it will also disable the helpful warning if a program
1231 tries to use a vsyscall. With this option set to N, offending
1232 programs will just segfault, citing addresses of the form
1233 0xffffffffff600?00.
1234
1235 This option is required by many programs built before 2013, and
1236 care should be used even with newer programs if set to N.
1237
1238 Disabling this option saves about 7K of kernel size and
1239 possibly 4K of additional runtime pagetable memory.
1240
1241config TOSHIBA
1242 tristate "Toshiba Laptop support"
1243 depends on X86_32
1244 ---help---
1245 This adds a driver to safely access the System Management Mode of
1246 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1247 not work on models with a Phoenix BIOS. The System Management Mode
1248 is used to set the BIOS and power saving options on Toshiba portables.
1249
1250 For information on utilities to make use of this driver see the
1251 Toshiba Linux utilities web site at:
1252 <http://www.buzzard.org.uk/toshiba/>.
1253
1254 Say Y if you intend to run this kernel on a Toshiba portable.
1255 Say N otherwise.
1256
1257config I8K
1258 tristate "Dell i8k legacy laptop support"
1259 select HWMON
1260 select SENSORS_DELL_SMM
1261 ---help---
1262 This option enables legacy /proc/i8k userspace interface in hwmon
1263 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1264 temperature and allows controlling fan speeds of Dell laptops via
1265 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1266 it reports also power and hotkey status. For fan speed control is
1267 needed userspace package i8kutils.
1268
1269 Say Y if you intend to run this kernel on old Dell laptops or want to
1270 use userspace package i8kutils.
1271 Say N otherwise.
1272
1273config X86_REBOOTFIXUPS
1274 bool "Enable X86 board specific fixups for reboot"
1275 depends on X86_32
1276 ---help---
1277 This enables chipset and/or board specific fixups to be done
1278 in order to get reboot to work correctly. This is only needed on
1279 some combinations of hardware and BIOS. The symptom, for which
1280 this config is intended, is when reboot ends with a stalled/hung
1281 system.
1282
1283 Currently, the only fixup is for the Geode machines using
1284 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1285
1286 Say Y if you want to enable the fixup. Currently, it's safe to
1287 enable this option even if you don't need it.
1288 Say N otherwise.
1289
1290config MICROCODE
1291 bool "CPU microcode loading support"
1292 default y
1293 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1294 select FW_LOADER
1295 ---help---
1296 If you say Y here, you will be able to update the microcode on
1297 Intel and AMD processors. The Intel support is for the IA32 family,
1298 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1299 AMD support is for families 0x10 and later. You will obviously need
1300 the actual microcode binary data itself which is not shipped with
1301 the Linux kernel.
1302
1303 The preferred method to load microcode from a detached initrd is described
1304 in Documentation/x86/microcode.txt. For that you need to enable
1305 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1306 initrd for microcode blobs.
1307
1308 In addition, you can build the microcode into the kernel. For that you
1309 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1310 config option.
1311
1312config MICROCODE_INTEL
1313 bool "Intel microcode loading support"
1314 depends on MICROCODE
1315 default MICROCODE
1316 select FW_LOADER
1317 ---help---
1318 This options enables microcode patch loading support for Intel
1319 processors.
1320
1321 For the current Intel microcode data package go to
1322 <https://downloadcenter.intel.com> and search for
1323 'Linux Processor Microcode Data File'.
1324
1325config MICROCODE_AMD
1326 bool "AMD microcode loading support"
1327 depends on MICROCODE
1328 select FW_LOADER
1329 ---help---
1330 If you select this option, microcode patch loading support for AMD
1331 processors will be enabled.
1332
1333config MICROCODE_OLD_INTERFACE
1334 def_bool y
1335 depends on MICROCODE
1336
1337config X86_MSR
1338 tristate "/dev/cpu/*/msr - Model-specific register support"
1339 ---help---
1340 This device gives privileged processes access to the x86
1341 Model-Specific Registers (MSRs). It is a character device with
1342 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1343 MSR accesses are directed to a specific CPU on multi-processor
1344 systems.
1345
1346config X86_CPUID
1347 tristate "/dev/cpu/*/cpuid - CPU information support"
1348 ---help---
1349 This device gives processes access to the x86 CPUID instruction to
1350 be executed on a specific processor. It is a character device
1351 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1352 /dev/cpu/31/cpuid.
1353
1354choice
1355 prompt "High Memory Support"
1356 default HIGHMEM4G
1357 depends on X86_32
1358
1359config NOHIGHMEM
1360 bool "off"
1361 ---help---
1362 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1363 However, the address space of 32-bit x86 processors is only 4
1364 Gigabytes large. That means that, if you have a large amount of
1365 physical memory, not all of it can be "permanently mapped" by the
1366 kernel. The physical memory that's not permanently mapped is called
1367 "high memory".
1368
1369 If you are compiling a kernel which will never run on a machine with
1370 more than 1 Gigabyte total physical RAM, answer "off" here (default
1371 choice and suitable for most users). This will result in a "3GB/1GB"
1372 split: 3GB are mapped so that each process sees a 3GB virtual memory
1373 space and the remaining part of the 4GB virtual memory space is used
1374 by the kernel to permanently map as much physical memory as
1375 possible.
1376
1377 If the machine has between 1 and 4 Gigabytes physical RAM, then
1378 answer "4GB" here.
1379
1380 If more than 4 Gigabytes is used then answer "64GB" here. This
1381 selection turns Intel PAE (Physical Address Extension) mode on.
1382 PAE implements 3-level paging on IA32 processors. PAE is fully
1383 supported by Linux, PAE mode is implemented on all recent Intel
1384 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1385 then the kernel will not boot on CPUs that don't support PAE!
1386
1387 The actual amount of total physical memory will either be
1388 auto detected or can be forced by using a kernel command line option
1389 such as "mem=256M". (Try "man bootparam" or see the documentation of
1390 your boot loader (lilo or loadlin) about how to pass options to the
1391 kernel at boot time.)
1392
1393 If unsure, say "off".
1394
1395config HIGHMEM4G
1396 bool "4GB"
1397 ---help---
1398 Select this if you have a 32-bit processor and between 1 and 4
1399 gigabytes of physical RAM.
1400
1401config HIGHMEM64G
1402 bool "64GB"
1403 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1404 select X86_PAE
1405 ---help---
1406 Select this if you have a 32-bit processor and more than 4
1407 gigabytes of physical RAM.
1408
1409endchoice
1410
1411choice
1412 prompt "Memory split" if EXPERT
1413 default VMSPLIT_3G
1414 depends on X86_32
1415 ---help---
1416 Select the desired split between kernel and user memory.
1417
1418 If the address range available to the kernel is less than the
1419 physical memory installed, the remaining memory will be available
1420 as "high memory". Accessing high memory is a little more costly
1421 than low memory, as it needs to be mapped into the kernel first.
1422 Note that increasing the kernel address space limits the range
1423 available to user programs, making the address space there
1424 tighter. Selecting anything other than the default 3G/1G split
1425 will also likely make your kernel incompatible with binary-only
1426 kernel modules.
1427
1428 If you are not absolutely sure what you are doing, leave this
1429 option alone!
1430
1431 config VMSPLIT_3G
1432 bool "3G/1G user/kernel split"
1433 config VMSPLIT_3G_OPT
1434 depends on !X86_PAE
1435 bool "3G/1G user/kernel split (for full 1G low memory)"
1436 config VMSPLIT_2G
1437 bool "2G/2G user/kernel split"
1438 config VMSPLIT_2G_OPT
1439 depends on !X86_PAE
1440 bool "2G/2G user/kernel split (for full 2G low memory)"
1441 config VMSPLIT_1G
1442 bool "1G/3G user/kernel split"
1443endchoice
1444
1445config PAGE_OFFSET
1446 hex
1447 default 0xB0000000 if VMSPLIT_3G_OPT
1448 default 0x80000000 if VMSPLIT_2G
1449 default 0x78000000 if VMSPLIT_2G_OPT
1450 default 0x40000000 if VMSPLIT_1G
1451 default 0xC0000000
1452 depends on X86_32
1453
1454config HIGHMEM
1455 def_bool y
1456 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1457
1458config X86_PAE
1459 bool "PAE (Physical Address Extension) Support"
1460 depends on X86_32 && !HIGHMEM4G
1461 select SWIOTLB
1462 ---help---
1463 PAE is required for NX support, and furthermore enables
1464 larger swapspace support for non-overcommit purposes. It
1465 has the cost of more pagetable lookup overhead, and also
1466 consumes more pagetable space per process.
1467
1468config X86_5LEVEL
1469 bool "Enable 5-level page tables support"
1470 select DYNAMIC_MEMORY_LAYOUT
1471 select SPARSEMEM_VMEMMAP
1472 depends on X86_64
1473 ---help---
1474 5-level paging enables access to larger address space:
1475 upto 128 PiB of virtual address space and 4 PiB of
1476 physical address space.
1477
1478 It will be supported by future Intel CPUs.
1479
1480 A kernel with the option enabled can be booted on machines that
1481 support 4- or 5-level paging.
1482
1483 See Documentation/x86/x86_64/5level-paging.txt for more
1484 information.
1485
1486 Say N if unsure.
1487
1488config ARCH_PHYS_ADDR_T_64BIT
1489 def_bool y
1490 depends on X86_64 || X86_PAE
1491
1492config ARCH_DMA_ADDR_T_64BIT
1493 def_bool y
1494 depends on X86_64 || HIGHMEM64G
1495
1496config X86_DIRECT_GBPAGES
1497 def_bool y
1498 depends on X86_64 && !DEBUG_PAGEALLOC
1499 ---help---
1500 Certain kernel features effectively disable kernel
1501 linear 1 GB mappings (even if the CPU otherwise
1502 supports them), so don't confuse the user by printing
1503 that we have them enabled.
1504
1505config ARCH_HAS_MEM_ENCRYPT
1506 def_bool y
1507
1508config AMD_MEM_ENCRYPT
1509 bool "AMD Secure Memory Encryption (SME) support"
1510 depends on X86_64 && CPU_SUP_AMD
1511 ---help---
1512 Say yes to enable support for the encryption of system memory.
1513 This requires an AMD processor that supports Secure Memory
1514 Encryption (SME).
1515
1516config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1517 bool "Activate AMD Secure Memory Encryption (SME) by default"
1518 default y
1519 depends on AMD_MEM_ENCRYPT
1520 ---help---
1521 Say yes to have system memory encrypted by default if running on
1522 an AMD processor that supports Secure Memory Encryption (SME).
1523
1524 If set to Y, then the encryption of system memory can be
1525 deactivated with the mem_encrypt=off command line option.
1526
1527 If set to N, then the encryption of system memory can be
1528 activated with the mem_encrypt=on command line option.
1529
1530config ARCH_USE_MEMREMAP_PROT
1531 def_bool y
1532 depends on AMD_MEM_ENCRYPT
1533
1534# Common NUMA Features
1535config NUMA
1536 bool "Numa Memory Allocation and Scheduler Support"
1537 depends on SMP
1538 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1539 default y if X86_BIGSMP
1540 ---help---
1541 Enable NUMA (Non Uniform Memory Access) support.
1542
1543 The kernel will try to allocate memory used by a CPU on the
1544 local memory controller of the CPU and add some more
1545 NUMA awareness to the kernel.
1546
1547 For 64-bit this is recommended if the system is Intel Core i7
1548 (or later), AMD Opteron, or EM64T NUMA.
1549
1550 For 32-bit this is only needed if you boot a 32-bit
1551 kernel on a 64-bit NUMA platform.
1552
1553 Otherwise, you should say N.
1554
1555config AMD_NUMA
1556 def_bool y
1557 prompt "Old style AMD Opteron NUMA detection"
1558 depends on X86_64 && NUMA && PCI
1559 ---help---
1560 Enable AMD NUMA node topology detection. You should say Y here if
1561 you have a multi processor AMD system. This uses an old method to
1562 read the NUMA configuration directly from the builtin Northbridge
1563 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1564 which also takes priority if both are compiled in.
1565
1566config X86_64_ACPI_NUMA
1567 def_bool y
1568 prompt "ACPI NUMA detection"
1569 depends on X86_64 && NUMA && ACPI && PCI
1570 select ACPI_NUMA
1571 ---help---
1572 Enable ACPI SRAT based node topology detection.
1573
1574# Some NUMA nodes have memory ranges that span
1575# other nodes. Even though a pfn is valid and
1576# between a node's start and end pfns, it may not
1577# reside on that node. See memmap_init_zone()
1578# for details.
1579config NODES_SPAN_OTHER_NODES
1580 def_bool y
1581 depends on X86_64_ACPI_NUMA
1582
1583config NUMA_EMU
1584 bool "NUMA emulation"
1585 depends on NUMA
1586 ---help---
1587 Enable NUMA emulation. A flat machine will be split
1588 into virtual nodes when booted with "numa=fake=N", where N is the
1589 number of nodes. This is only useful for debugging.
1590
1591config NODES_SHIFT
1592 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1593 range 1 10
1594 default "10" if MAXSMP
1595 default "6" if X86_64
1596 default "3"
1597 depends on NEED_MULTIPLE_NODES
1598 ---help---
1599 Specify the maximum number of NUMA Nodes available on the target
1600 system. Increases memory reserved to accommodate various tables.
1601
1602config ARCH_HAVE_MEMORY_PRESENT
1603 def_bool y
1604 depends on X86_32 && DISCONTIGMEM
1605
1606config ARCH_FLATMEM_ENABLE
1607 def_bool y
1608 depends on X86_32 && !NUMA
1609
1610config ARCH_DISCONTIGMEM_ENABLE
1611 def_bool y
1612 depends on NUMA && X86_32
1613
1614config ARCH_DISCONTIGMEM_DEFAULT
1615 def_bool y
1616 depends on NUMA && X86_32
1617
1618config ARCH_SPARSEMEM_ENABLE
1619 def_bool y
1620 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1621 select SPARSEMEM_STATIC if X86_32
1622 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1623
1624config ARCH_SPARSEMEM_DEFAULT
1625 def_bool y
1626 depends on X86_64
1627
1628config ARCH_SELECT_MEMORY_MODEL
1629 def_bool y
1630 depends on ARCH_SPARSEMEM_ENABLE
1631
1632config ARCH_MEMORY_PROBE
1633 bool "Enable sysfs memory/probe interface"
1634 depends on X86_64 && MEMORY_HOTPLUG
1635 help
1636 This option enables a sysfs memory/probe interface for testing.
1637 See Documentation/memory-hotplug.txt for more information.
1638 If you are unsure how to answer this question, answer N.
1639
1640config ARCH_PROC_KCORE_TEXT
1641 def_bool y
1642 depends on X86_64 && PROC_KCORE
1643
1644config ILLEGAL_POINTER_VALUE
1645 hex
1646 default 0 if X86_32
1647 default 0xdead000000000000 if X86_64
1648
1649source "mm/Kconfig"
1650
1651config X86_PMEM_LEGACY_DEVICE
1652 bool
1653
1654config X86_PMEM_LEGACY
1655 tristate "Support non-standard NVDIMMs and ADR protected memory"
1656 depends on PHYS_ADDR_T_64BIT
1657 depends on BLK_DEV
1658 select X86_PMEM_LEGACY_DEVICE
1659 select LIBNVDIMM
1660 help
1661 Treat memory marked using the non-standard e820 type of 12 as used
1662 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1663 The kernel will offer these regions to the 'pmem' driver so
1664 they can be used for persistent storage.
1665
1666 Say Y if unsure.
1667
1668config HIGHPTE
1669 bool "Allocate 3rd-level pagetables from highmem"
1670 depends on HIGHMEM
1671 ---help---
1672 The VM uses one page table entry for each page of physical memory.
1673 For systems with a lot of RAM, this can be wasteful of precious
1674 low memory. Setting this option will put user-space page table
1675 entries in high memory.
1676
1677config X86_CHECK_BIOS_CORRUPTION
1678 bool "Check for low memory corruption"
1679 ---help---
1680 Periodically check for memory corruption in low memory, which
1681 is suspected to be caused by BIOS. Even when enabled in the
1682 configuration, it is disabled at runtime. Enable it by
1683 setting "memory_corruption_check=1" on the kernel command
1684 line. By default it scans the low 64k of memory every 60
1685 seconds; see the memory_corruption_check_size and
1686 memory_corruption_check_period parameters in
1687 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1688
1689 When enabled with the default parameters, this option has
1690 almost no overhead, as it reserves a relatively small amount
1691 of memory and scans it infrequently. It both detects corruption
1692 and prevents it from affecting the running system.
1693
1694 It is, however, intended as a diagnostic tool; if repeatable
1695 BIOS-originated corruption always affects the same memory,
1696 you can use memmap= to prevent the kernel from using that
1697 memory.
1698
1699config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1700 bool "Set the default setting of memory_corruption_check"
1701 depends on X86_CHECK_BIOS_CORRUPTION
1702 default y
1703 ---help---
1704 Set whether the default state of memory_corruption_check is
1705 on or off.
1706
1707config X86_RESERVE_LOW
1708 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1709 default 64
1710 range 4 640
1711 ---help---
1712 Specify the amount of low memory to reserve for the BIOS.
1713
1714 The first page contains BIOS data structures that the kernel
1715 must not use, so that page must always be reserved.
1716
1717 By default we reserve the first 64K of physical RAM, as a
1718 number of BIOSes are known to corrupt that memory range
1719 during events such as suspend/resume or monitor cable
1720 insertion, so it must not be used by the kernel.
1721
1722 You can set this to 4 if you are absolutely sure that you
1723 trust the BIOS to get all its memory reservations and usages
1724 right. If you know your BIOS have problems beyond the
1725 default 64K area, you can set this to 640 to avoid using the
1726 entire low memory range.
1727
1728 If you have doubts about the BIOS (e.g. suspend/resume does
1729 not work or there's kernel crashes after certain hardware
1730 hotplug events) then you might want to enable
1731 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1732 typical corruption patterns.
1733
1734 Leave this to the default value of 64 if you are unsure.
1735
1736config MATH_EMULATION
1737 bool
1738 depends on MODIFY_LDT_SYSCALL
1739 prompt "Math emulation" if X86_32
1740 ---help---
1741 Linux can emulate a math coprocessor (used for floating point
1742 operations) if you don't have one. 486DX and Pentium processors have
1743 a math coprocessor built in, 486SX and 386 do not, unless you added
1744 a 487DX or 387, respectively. (The messages during boot time can
1745 give you some hints here ["man dmesg"].) Everyone needs either a
1746 coprocessor or this emulation.
1747
1748 If you don't have a math coprocessor, you need to say Y here; if you
1749 say Y here even though you have a coprocessor, the coprocessor will
1750 be used nevertheless. (This behavior can be changed with the kernel
1751 command line option "no387", which comes handy if your coprocessor
1752 is broken. Try "man bootparam" or see the documentation of your boot
1753 loader (lilo or loadlin) about how to pass options to the kernel at
1754 boot time.) This means that it is a good idea to say Y here if you
1755 intend to use this kernel on different machines.
1756
1757 More information about the internals of the Linux math coprocessor
1758 emulation can be found in <file:arch/x86/math-emu/README>.
1759
1760 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1761 kernel, it won't hurt.
1762
1763config MTRR
1764 def_bool y
1765 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1766 ---help---
1767 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1768 the Memory Type Range Registers (MTRRs) may be used to control
1769 processor access to memory ranges. This is most useful if you have
1770 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1771 allows bus write transfers to be combined into a larger transfer
1772 before bursting over the PCI/AGP bus. This can increase performance
1773 of image write operations 2.5 times or more. Saying Y here creates a
1774 /proc/mtrr file which may be used to manipulate your processor's
1775 MTRRs. Typically the X server should use this.
1776
1777 This code has a reasonably generic interface so that similar
1778 control registers on other processors can be easily supported
1779 as well:
1780
1781 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1782 Registers (ARRs) which provide a similar functionality to MTRRs. For
1783 these, the ARRs are used to emulate the MTRRs.
1784 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1785 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1786 write-combining. All of these processors are supported by this code
1787 and it makes sense to say Y here if you have one of them.
1788
1789 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1790 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1791 can lead to all sorts of problems, so it's good to say Y here.
1792
1793 You can safely say Y even if your machine doesn't have MTRRs, you'll
1794 just add about 9 KB to your kernel.
1795
1796 See <file:Documentation/x86/mtrr.txt> for more information.
1797
1798config MTRR_SANITIZER
1799 def_bool y
1800 prompt "MTRR cleanup support"
1801 depends on MTRR
1802 ---help---
1803 Convert MTRR layout from continuous to discrete, so X drivers can
1804 add writeback entries.
1805
1806 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1807 The largest mtrr entry size for a continuous block can be set with
1808 mtrr_chunk_size.
1809
1810 If unsure, say Y.
1811
1812config MTRR_SANITIZER_ENABLE_DEFAULT
1813 int "MTRR cleanup enable value (0-1)"
1814 range 0 1
1815 default "0"
1816 depends on MTRR_SANITIZER
1817 ---help---
1818 Enable mtrr cleanup default value
1819
1820config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1821 int "MTRR cleanup spare reg num (0-7)"
1822 range 0 7
1823 default "1"
1824 depends on MTRR_SANITIZER
1825 ---help---
1826 mtrr cleanup spare entries default, it can be changed via
1827 mtrr_spare_reg_nr=N on the kernel command line.
1828
1829config X86_PAT
1830 def_bool y
1831 prompt "x86 PAT support" if EXPERT
1832 depends on MTRR
1833 ---help---
1834 Use PAT attributes to setup page level cache control.
1835
1836 PATs are the modern equivalents of MTRRs and are much more
1837 flexible than MTRRs.
1838
1839 Say N here if you see bootup problems (boot crash, boot hang,
1840 spontaneous reboots) or a non-working video driver.
1841
1842 If unsure, say Y.
1843
1844config ARCH_USES_PG_UNCACHED
1845 def_bool y
1846 depends on X86_PAT
1847
1848config ARCH_RANDOM
1849 def_bool y
1850 prompt "x86 architectural random number generator" if EXPERT
1851 ---help---
1852 Enable the x86 architectural RDRAND instruction
1853 (Intel Bull Mountain technology) to generate random numbers.
1854 If supported, this is a high bandwidth, cryptographically
1855 secure hardware random number generator.
1856
1857config X86_SMAP
1858 def_bool y
1859 prompt "Supervisor Mode Access Prevention" if EXPERT
1860 ---help---
1861 Supervisor Mode Access Prevention (SMAP) is a security
1862 feature in newer Intel processors. There is a small
1863 performance cost if this enabled and turned on; there is
1864 also a small increase in the kernel size if this is enabled.
1865
1866 If unsure, say Y.
1867
1868config X86_INTEL_UMIP
1869 def_bool y
1870 depends on CPU_SUP_INTEL
1871 prompt "Intel User Mode Instruction Prevention" if EXPERT
1872 ---help---
1873 The User Mode Instruction Prevention (UMIP) is a security
1874 feature in newer Intel processors. If enabled, a general
1875 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1876 or STR instructions are executed in user mode. These instructions
1877 unnecessarily expose information about the hardware state.
1878
1879 The vast majority of applications do not use these instructions.
1880 For the very few that do, software emulation is provided in
1881 specific cases in protected and virtual-8086 modes. Emulated
1882 results are dummy.
1883
1884config X86_INTEL_MPX
1885 prompt "Intel MPX (Memory Protection Extensions)"
1886 def_bool n
1887 # Note: only available in 64-bit mode due to VMA flags shortage
1888 depends on CPU_SUP_INTEL && X86_64
1889 select ARCH_USES_HIGH_VMA_FLAGS
1890 ---help---
1891 MPX provides hardware features that can be used in
1892 conjunction with compiler-instrumented code to check
1893 memory references. It is designed to detect buffer
1894 overflow or underflow bugs.
1895
1896 This option enables running applications which are
1897 instrumented or otherwise use MPX. It does not use MPX
1898 itself inside the kernel or to protect the kernel
1899 against bad memory references.
1900
1901 Enabling this option will make the kernel larger:
1902 ~8k of kernel text and 36 bytes of data on a 64-bit
1903 defconfig. It adds a long to the 'mm_struct' which
1904 will increase the kernel memory overhead of each
1905 process and adds some branches to paths used during
1906 exec() and munmap().
1907
1908 For details, see Documentation/x86/intel_mpx.txt
1909
1910 If unsure, say N.
1911
1912config X86_INTEL_MEMORY_PROTECTION_KEYS
1913 prompt "Intel Memory Protection Keys"
1914 def_bool y
1915 # Note: only available in 64-bit mode
1916 depends on CPU_SUP_INTEL && X86_64
1917 select ARCH_USES_HIGH_VMA_FLAGS
1918 select ARCH_HAS_PKEYS
1919 ---help---
1920 Memory Protection Keys provides a mechanism for enforcing
1921 page-based protections, but without requiring modification of the
1922 page tables when an application changes protection domains.
1923
1924 For details, see Documentation/x86/protection-keys.txt
1925
1926 If unsure, say y.
1927
1928config EFI
1929 bool "EFI runtime service support"
1930 depends on ACPI
1931 select UCS2_STRING
1932 select EFI_RUNTIME_WRAPPERS
1933 ---help---
1934 This enables the kernel to use EFI runtime services that are
1935 available (such as the EFI variable services).
1936
1937 This option is only useful on systems that have EFI firmware.
1938 In addition, you should use the latest ELILO loader available
1939 at <http://elilo.sourceforge.net> in order to take advantage
1940 of EFI runtime services. However, even with this option, the
1941 resultant kernel should continue to boot on existing non-EFI
1942 platforms.
1943
1944config EFI_STUB
1945 bool "EFI stub support"
1946 depends on EFI && !X86_USE_3DNOW
1947 select RELOCATABLE
1948 ---help---
1949 This kernel feature allows a bzImage to be loaded directly
1950 by EFI firmware without the use of a bootloader.
1951
1952 See Documentation/efi-stub.txt for more information.
1953
1954config EFI_MIXED
1955 bool "EFI mixed-mode support"
1956 depends on EFI_STUB && X86_64
1957 ---help---
1958 Enabling this feature allows a 64-bit kernel to be booted
1959 on a 32-bit firmware, provided that your CPU supports 64-bit
1960 mode.
1961
1962 Note that it is not possible to boot a mixed-mode enabled
1963 kernel via the EFI boot stub - a bootloader that supports
1964 the EFI handover protocol must be used.
1965
1966 If unsure, say N.
1967
1968config SECCOMP
1969 def_bool y
1970 prompt "Enable seccomp to safely compute untrusted bytecode"
1971 ---help---
1972 This kernel feature is useful for number crunching applications
1973 that may need to compute untrusted bytecode during their
1974 execution. By using pipes or other transports made available to
1975 the process as file descriptors supporting the read/write
1976 syscalls, it's possible to isolate those applications in
1977 their own address space using seccomp. Once seccomp is
1978 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1979 and the task is only allowed to execute a few safe syscalls
1980 defined by each seccomp mode.
1981
1982 If unsure, say Y. Only embedded should say N here.
1983
1984source kernel/Kconfig.hz
1985
1986config KEXEC
1987 bool "kexec system call"
1988 select KEXEC_CORE
1989 ---help---
1990 kexec is a system call that implements the ability to shutdown your
1991 current kernel, and to start another kernel. It is like a reboot
1992 but it is independent of the system firmware. And like a reboot
1993 you can start any kernel with it, not just Linux.
1994
1995 The name comes from the similarity to the exec system call.
1996
1997 It is an ongoing process to be certain the hardware in a machine
1998 is properly shutdown, so do not be surprised if this code does not
1999 initially work for you. As of this writing the exact hardware
2000 interface is strongly in flux, so no good recommendation can be
2001 made.
2002
2003config KEXEC_FILE
2004 bool "kexec file based system call"
2005 select KEXEC_CORE
2006 select BUILD_BIN2C
2007 depends on X86_64
2008 depends on CRYPTO=y
2009 depends on CRYPTO_SHA256=y
2010 ---help---
2011 This is new version of kexec system call. This system call is
2012 file based and takes file descriptors as system call argument
2013 for kernel and initramfs as opposed to list of segments as
2014 accepted by previous system call.
2015
2016config ARCH_HAS_KEXEC_PURGATORY
2017 def_bool KEXEC_FILE
2018
2019config KEXEC_VERIFY_SIG
2020 bool "Verify kernel signature during kexec_file_load() syscall"
2021 depends on KEXEC_FILE
2022 ---help---
2023 This option makes kernel signature verification mandatory for
2024 the kexec_file_load() syscall.
2025
2026 In addition to that option, you need to enable signature
2027 verification for the corresponding kernel image type being
2028 loaded in order for this to work.
2029
2030config KEXEC_BZIMAGE_VERIFY_SIG
2031 bool "Enable bzImage signature verification support"
2032 depends on KEXEC_VERIFY_SIG
2033 depends on SIGNED_PE_FILE_VERIFICATION
2034 select SYSTEM_TRUSTED_KEYRING
2035 ---help---
2036 Enable bzImage signature verification support.
2037
2038config CRASH_DUMP
2039 bool "kernel crash dumps"
2040 depends on X86_64 || (X86_32 && HIGHMEM)
2041 ---help---
2042 Generate crash dump after being started by kexec.
2043 This should be normally only set in special crash dump kernels
2044 which are loaded in the main kernel with kexec-tools into
2045 a specially reserved region and then later executed after
2046 a crash by kdump/kexec. The crash dump kernel must be compiled
2047 to a memory address not used by the main kernel or BIOS using
2048 PHYSICAL_START, or it must be built as a relocatable image
2049 (CONFIG_RELOCATABLE=y).
2050 For more details see Documentation/kdump/kdump.txt
2051
2052config KEXEC_JUMP
2053 bool "kexec jump"
2054 depends on KEXEC && HIBERNATION
2055 ---help---
2056 Jump between original kernel and kexeced kernel and invoke
2057 code in physical address mode via KEXEC
2058
2059config PHYSICAL_START
2060 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2061 default "0x1000000"
2062 ---help---
2063 This gives the physical address where the kernel is loaded.
2064
2065 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2066 bzImage will decompress itself to above physical address and
2067 run from there. Otherwise, bzImage will run from the address where
2068 it has been loaded by the boot loader and will ignore above physical
2069 address.
2070
2071 In normal kdump cases one does not have to set/change this option
2072 as now bzImage can be compiled as a completely relocatable image
2073 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2074 address. This option is mainly useful for the folks who don't want
2075 to use a bzImage for capturing the crash dump and want to use a
2076 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2077 to be specifically compiled to run from a specific memory area
2078 (normally a reserved region) and this option comes handy.
2079
2080 So if you are using bzImage for capturing the crash dump,
2081 leave the value here unchanged to 0x1000000 and set
2082 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2083 for capturing the crash dump change this value to start of
2084 the reserved region. In other words, it can be set based on
2085 the "X" value as specified in the "crashkernel=YM@XM"
2086 command line boot parameter passed to the panic-ed
2087 kernel. Please take a look at Documentation/kdump/kdump.txt
2088 for more details about crash dumps.
2089
2090 Usage of bzImage for capturing the crash dump is recommended as
2091 one does not have to build two kernels. Same kernel can be used
2092 as production kernel and capture kernel. Above option should have
2093 gone away after relocatable bzImage support is introduced. But it
2094 is present because there are users out there who continue to use
2095 vmlinux for dump capture. This option should go away down the
2096 line.
2097
2098 Don't change this unless you know what you are doing.
2099
2100config RELOCATABLE
2101 bool "Build a relocatable kernel"
2102 default y
2103 ---help---
2104 This builds a kernel image that retains relocation information
2105 so it can be loaded someplace besides the default 1MB.
2106 The relocations tend to make the kernel binary about 10% larger,
2107 but are discarded at runtime.
2108
2109 One use is for the kexec on panic case where the recovery kernel
2110 must live at a different physical address than the primary
2111 kernel.
2112
2113 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2114 it has been loaded at and the compile time physical address
2115 (CONFIG_PHYSICAL_START) is used as the minimum location.
2116
2117config RANDOMIZE_BASE
2118 bool "Randomize the address of the kernel image (KASLR)"
2119 depends on RELOCATABLE
2120 default y
2121 ---help---
2122 In support of Kernel Address Space Layout Randomization (KASLR),
2123 this randomizes the physical address at which the kernel image
2124 is decompressed and the virtual address where the kernel
2125 image is mapped, as a security feature that deters exploit
2126 attempts relying on knowledge of the location of kernel
2127 code internals.
2128
2129 On 64-bit, the kernel physical and virtual addresses are
2130 randomized separately. The physical address will be anywhere
2131 between 16MB and the top of physical memory (up to 64TB). The
2132 virtual address will be randomized from 16MB up to 1GB (9 bits
2133 of entropy). Note that this also reduces the memory space
2134 available to kernel modules from 1.5GB to 1GB.
2135
2136 On 32-bit, the kernel physical and virtual addresses are
2137 randomized together. They will be randomized from 16MB up to
2138 512MB (8 bits of entropy).
2139
2140 Entropy is generated using the RDRAND instruction if it is
2141 supported. If RDTSC is supported, its value is mixed into
2142 the entropy pool as well. If neither RDRAND nor RDTSC are
2143 supported, then entropy is read from the i8254 timer. The
2144 usable entropy is limited by the kernel being built using
2145 2GB addressing, and that PHYSICAL_ALIGN must be at a
2146 minimum of 2MB. As a result, only 10 bits of entropy are
2147 theoretically possible, but the implementations are further
2148 limited due to memory layouts.
2149
2150 If unsure, say Y.
2151
2152# Relocation on x86 needs some additional build support
2153config X86_NEED_RELOCS
2154 def_bool y
2155 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2156
2157config PHYSICAL_ALIGN
2158 hex "Alignment value to which kernel should be aligned"
2159 default "0x200000"
2160 range 0x2000 0x1000000 if X86_32
2161 range 0x200000 0x1000000 if X86_64
2162 ---help---
2163 This value puts the alignment restrictions on physical address
2164 where kernel is loaded and run from. Kernel is compiled for an
2165 address which meets above alignment restriction.
2166
2167 If bootloader loads the kernel at a non-aligned address and
2168 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2169 address aligned to above value and run from there.
2170
2171 If bootloader loads the kernel at a non-aligned address and
2172 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2173 load address and decompress itself to the address it has been
2174 compiled for and run from there. The address for which kernel is
2175 compiled already meets above alignment restrictions. Hence the
2176 end result is that kernel runs from a physical address meeting
2177 above alignment restrictions.
2178
2179 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2180 this value must be a multiple of 0x200000.
2181
2182 Don't change this unless you know what you are doing.
2183
2184config DYNAMIC_MEMORY_LAYOUT
2185 bool
2186 ---help---
2187 This option makes base addresses of vmalloc and vmemmap as well as
2188 __PAGE_OFFSET movable during boot.
2189
2190config RANDOMIZE_MEMORY
2191 bool "Randomize the kernel memory sections"
2192 depends on X86_64
2193 depends on RANDOMIZE_BASE
2194 select DYNAMIC_MEMORY_LAYOUT
2195 default RANDOMIZE_BASE
2196 ---help---
2197 Randomizes the base virtual address of kernel memory sections
2198 (physical memory mapping, vmalloc & vmemmap). This security feature
2199 makes exploits relying on predictable memory locations less reliable.
2200
2201 The order of allocations remains unchanged. Entropy is generated in
2202 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2203 configuration have in average 30,000 different possible virtual
2204 addresses for each memory section.
2205
2206 If unsure, say Y.
2207
2208config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2209 hex "Physical memory mapping padding" if EXPERT
2210 depends on RANDOMIZE_MEMORY
2211 default "0xa" if MEMORY_HOTPLUG
2212 default "0x0"
2213 range 0x1 0x40 if MEMORY_HOTPLUG
2214 range 0x0 0x40
2215 ---help---
2216 Define the padding in terabytes added to the existing physical
2217 memory size during kernel memory randomization. It is useful
2218 for memory hotplug support but reduces the entropy available for
2219 address randomization.
2220
2221 If unsure, leave at the default value.
2222
2223config HOTPLUG_CPU
2224 bool "Support for hot-pluggable CPUs"
2225 depends on SMP
2226 ---help---
2227 Say Y here to allow turning CPUs off and on. CPUs can be
2228 controlled through /sys/devices/system/cpu.
2229 ( Note: power management support will enable this option
2230 automatically on SMP systems. )
2231 Say N if you want to disable CPU hotplug.
2232
2233config BOOTPARAM_HOTPLUG_CPU0
2234 bool "Set default setting of cpu0_hotpluggable"
2235 default n
2236 depends on HOTPLUG_CPU
2237 ---help---
2238 Set whether default state of cpu0_hotpluggable is on or off.
2239
2240 Say Y here to enable CPU0 hotplug by default. If this switch
2241 is turned on, there is no need to give cpu0_hotplug kernel
2242 parameter and the CPU0 hotplug feature is enabled by default.
2243
2244 Please note: there are two known CPU0 dependencies if you want
2245 to enable the CPU0 hotplug feature either by this switch or by
2246 cpu0_hotplug kernel parameter.
2247
2248 First, resume from hibernate or suspend always starts from CPU0.
2249 So hibernate and suspend are prevented if CPU0 is offline.
2250
2251 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2252 offline if any interrupt can not migrate out of CPU0. There may
2253 be other CPU0 dependencies.
2254
2255 Please make sure the dependencies are under your control before
2256 you enable this feature.
2257
2258 Say N if you don't want to enable CPU0 hotplug feature by default.
2259 You still can enable the CPU0 hotplug feature at boot by kernel
2260 parameter cpu0_hotplug.
2261
2262config DEBUG_HOTPLUG_CPU0
2263 def_bool n
2264 prompt "Debug CPU0 hotplug"
2265 depends on HOTPLUG_CPU
2266 ---help---
2267 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2268 soon as possible and boots up userspace with CPU0 offlined. User
2269 can online CPU0 back after boot time.
2270
2271 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2272 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2273 compilation or giving cpu0_hotplug kernel parameter at boot.
2274
2275 If unsure, say N.
2276
2277config COMPAT_VDSO
2278 def_bool n
2279 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2280 depends on COMPAT_32
2281 ---help---
2282 Certain buggy versions of glibc will crash if they are
2283 presented with a 32-bit vDSO that is not mapped at the address
2284 indicated in its segment table.
2285
2286 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2287 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2288 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2289 the only released version with the bug, but OpenSUSE 9
2290 contains a buggy "glibc 2.3.2".
2291
2292 The symptom of the bug is that everything crashes on startup, saying:
2293 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2294
2295 Saying Y here changes the default value of the vdso32 boot
2296 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2297 This works around the glibc bug but hurts performance.
2298
2299 If unsure, say N: if you are compiling your own kernel, you
2300 are unlikely to be using a buggy version of glibc.
2301
2302choice
2303 prompt "vsyscall table for legacy applications"
2304 depends on X86_64
2305 default LEGACY_VSYSCALL_EMULATE
2306 help
2307 Legacy user code that does not know how to find the vDSO expects
2308 to be able to issue three syscalls by calling fixed addresses in
2309 kernel space. Since this location is not randomized with ASLR,
2310 it can be used to assist security vulnerability exploitation.
2311
2312 This setting can be changed at boot time via the kernel command
2313 line parameter vsyscall=[emulate|none].
2314
2315 On a system with recent enough glibc (2.14 or newer) and no
2316 static binaries, you can say None without a performance penalty
2317 to improve security.
2318
2319 If unsure, select "Emulate".
2320
2321 config LEGACY_VSYSCALL_EMULATE
2322 bool "Emulate"
2323 help
2324 The kernel traps and emulates calls into the fixed
2325 vsyscall address mapping. This makes the mapping
2326 non-executable, but it still contains known contents,
2327 which could be used in certain rare security vulnerability
2328 exploits. This configuration is recommended when userspace
2329 still uses the vsyscall area.
2330
2331 config LEGACY_VSYSCALL_NONE
2332 bool "None"
2333 help
2334 There will be no vsyscall mapping at all. This will
2335 eliminate any risk of ASLR bypass due to the vsyscall
2336 fixed address mapping. Attempts to use the vsyscalls
2337 will be reported to dmesg, so that either old or
2338 malicious userspace programs can be identified.
2339
2340endchoice
2341
2342config CMDLINE_BOOL
2343 bool "Built-in kernel command line"
2344 ---help---
2345 Allow for specifying boot arguments to the kernel at
2346 build time. On some systems (e.g. embedded ones), it is
2347 necessary or convenient to provide some or all of the
2348 kernel boot arguments with the kernel itself (that is,
2349 to not rely on the boot loader to provide them.)
2350
2351 To compile command line arguments into the kernel,
2352 set this option to 'Y', then fill in the
2353 boot arguments in CONFIG_CMDLINE.
2354
2355 Systems with fully functional boot loaders (i.e. non-embedded)
2356 should leave this option set to 'N'.
2357
2358config CMDLINE
2359 string "Built-in kernel command string"
2360 depends on CMDLINE_BOOL
2361 default ""
2362 ---help---
2363 Enter arguments here that should be compiled into the kernel
2364 image and used at boot time. If the boot loader provides a
2365 command line at boot time, it is appended to this string to
2366 form the full kernel command line, when the system boots.
2367
2368 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2369 change this behavior.
2370
2371 In most cases, the command line (whether built-in or provided
2372 by the boot loader) should specify the device for the root
2373 file system.
2374
2375config CMDLINE_OVERRIDE
2376 bool "Built-in command line overrides boot loader arguments"
2377 depends on CMDLINE_BOOL
2378 ---help---
2379 Set this option to 'Y' to have the kernel ignore the boot loader
2380 command line, and use ONLY the built-in command line.
2381
2382 This is used to work around broken boot loaders. This should
2383 be set to 'N' under normal conditions.
2384
2385config MODIFY_LDT_SYSCALL
2386 bool "Enable the LDT (local descriptor table)" if EXPERT
2387 default y
2388 ---help---
2389 Linux can allow user programs to install a per-process x86
2390 Local Descriptor Table (LDT) using the modify_ldt(2) system
2391 call. This is required to run 16-bit or segmented code such as
2392 DOSEMU or some Wine programs. It is also used by some very old
2393 threading libraries.
2394
2395 Enabling this feature adds a small amount of overhead to
2396 context switches and increases the low-level kernel attack
2397 surface. Disabling it removes the modify_ldt(2) system call.
2398
2399 Saying 'N' here may make sense for embedded or server kernels.
2400
2401source "kernel/livepatch/Kconfig"
2402
2403endmenu
2404
2405config ARCH_HAS_ADD_PAGES
2406 def_bool y
2407 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2408
2409config ARCH_ENABLE_MEMORY_HOTPLUG
2410 def_bool y
2411 depends on X86_64 || (X86_32 && HIGHMEM)
2412
2413config ARCH_ENABLE_MEMORY_HOTREMOVE
2414 def_bool y
2415 depends on MEMORY_HOTPLUG
2416
2417config USE_PERCPU_NUMA_NODE_ID
2418 def_bool y
2419 depends on NUMA
2420
2421config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2422 def_bool y
2423 depends on X86_64 || X86_PAE
2424
2425config ARCH_ENABLE_HUGEPAGE_MIGRATION
2426 def_bool y
2427 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2428
2429config ARCH_ENABLE_THP_MIGRATION
2430 def_bool y
2431 depends on X86_64 && TRANSPARENT_HUGEPAGE
2432
2433menu "Power management and ACPI options"
2434
2435config ARCH_HIBERNATION_HEADER
2436 def_bool y
2437 depends on X86_64 && HIBERNATION
2438
2439source "kernel/power/Kconfig"
2440
2441source "drivers/acpi/Kconfig"
2442
2443source "drivers/sfi/Kconfig"
2444
2445config X86_APM_BOOT
2446 def_bool y
2447 depends on APM
2448
2449menuconfig APM
2450 tristate "APM (Advanced Power Management) BIOS support"
2451 depends on X86_32 && PM_SLEEP
2452 ---help---
2453 APM is a BIOS specification for saving power using several different
2454 techniques. This is mostly useful for battery powered laptops with
2455 APM compliant BIOSes. If you say Y here, the system time will be
2456 reset after a RESUME operation, the /proc/apm device will provide
2457 battery status information, and user-space programs will receive
2458 notification of APM "events" (e.g. battery status change).
2459
2460 If you select "Y" here, you can disable actual use of the APM
2461 BIOS by passing the "apm=off" option to the kernel at boot time.
2462
2463 Note that the APM support is almost completely disabled for
2464 machines with more than one CPU.
2465
2466 In order to use APM, you will need supporting software. For location
2467 and more information, read <file:Documentation/power/apm-acpi.txt>
2468 and the Battery Powered Linux mini-HOWTO, available from
2469 <http://www.tldp.org/docs.html#howto>.
2470
2471 This driver does not spin down disk drives (see the hdparm(8)
2472 manpage ("man 8 hdparm") for that), and it doesn't turn off
2473 VESA-compliant "green" monitors.
2474
2475 This driver does not support the TI 4000M TravelMate and the ACER
2476 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2477 desktop machines also don't have compliant BIOSes, and this driver
2478 may cause those machines to panic during the boot phase.
2479
2480 Generally, if you don't have a battery in your machine, there isn't
2481 much point in using this driver and you should say N. If you get
2482 random kernel OOPSes or reboots that don't seem to be related to
2483 anything, try disabling/enabling this option (or disabling/enabling
2484 APM in your BIOS).
2485
2486 Some other things you should try when experiencing seemingly random,
2487 "weird" problems:
2488
2489 1) make sure that you have enough swap space and that it is
2490 enabled.
2491 2) pass the "no-hlt" option to the kernel
2492 3) switch on floating point emulation in the kernel and pass
2493 the "no387" option to the kernel
2494 4) pass the "floppy=nodma" option to the kernel
2495 5) pass the "mem=4M" option to the kernel (thereby disabling
2496 all but the first 4 MB of RAM)
2497 6) make sure that the CPU is not over clocked.
2498 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2499 8) disable the cache from your BIOS settings
2500 9) install a fan for the video card or exchange video RAM
2501 10) install a better fan for the CPU
2502 11) exchange RAM chips
2503 12) exchange the motherboard.
2504
2505 To compile this driver as a module, choose M here: the
2506 module will be called apm.
2507
2508if APM
2509
2510config APM_IGNORE_USER_SUSPEND
2511 bool "Ignore USER SUSPEND"
2512 ---help---
2513 This option will ignore USER SUSPEND requests. On machines with a
2514 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2515 series notebooks, it is necessary to say Y because of a BIOS bug.
2516
2517config APM_DO_ENABLE
2518 bool "Enable PM at boot time"
2519 ---help---
2520 Enable APM features at boot time. From page 36 of the APM BIOS
2521 specification: "When disabled, the APM BIOS does not automatically
2522 power manage devices, enter the Standby State, enter the Suspend
2523 State, or take power saving steps in response to CPU Idle calls."
2524 This driver will make CPU Idle calls when Linux is idle (unless this
2525 feature is turned off -- see "Do CPU IDLE calls", below). This
2526 should always save battery power, but more complicated APM features
2527 will be dependent on your BIOS implementation. You may need to turn
2528 this option off if your computer hangs at boot time when using APM
2529 support, or if it beeps continuously instead of suspending. Turn
2530 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2531 T400CDT. This is off by default since most machines do fine without
2532 this feature.
2533
2534config APM_CPU_IDLE
2535 depends on CPU_IDLE
2536 bool "Make CPU Idle calls when idle"
2537 ---help---
2538 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2539 On some machines, this can activate improved power savings, such as
2540 a slowed CPU clock rate, when the machine is idle. These idle calls
2541 are made after the idle loop has run for some length of time (e.g.,
2542 333 mS). On some machines, this will cause a hang at boot time or
2543 whenever the CPU becomes idle. (On machines with more than one CPU,
2544 this option does nothing.)
2545
2546config APM_DISPLAY_BLANK
2547 bool "Enable console blanking using APM"
2548 ---help---
2549 Enable console blanking using the APM. Some laptops can use this to
2550 turn off the LCD backlight when the screen blanker of the Linux
2551 virtual console blanks the screen. Note that this is only used by
2552 the virtual console screen blanker, and won't turn off the backlight
2553 when using the X Window system. This also doesn't have anything to
2554 do with your VESA-compliant power-saving monitor. Further, this
2555 option doesn't work for all laptops -- it might not turn off your
2556 backlight at all, or it might print a lot of errors to the console,
2557 especially if you are using gpm.
2558
2559config APM_ALLOW_INTS
2560 bool "Allow interrupts during APM BIOS calls"
2561 ---help---
2562 Normally we disable external interrupts while we are making calls to
2563 the APM BIOS as a measure to lessen the effects of a badly behaving
2564 BIOS implementation. The BIOS should reenable interrupts if it
2565 needs to. Unfortunately, some BIOSes do not -- especially those in
2566 many of the newer IBM Thinkpads. If you experience hangs when you
2567 suspend, try setting this to Y. Otherwise, say N.
2568
2569endif # APM
2570
2571source "drivers/cpufreq/Kconfig"
2572
2573source "drivers/cpuidle/Kconfig"
2574
2575source "drivers/idle/Kconfig"
2576
2577endmenu
2578
2579
2580menu "Bus options (PCI etc.)"
2581
2582config PCI
2583 bool "PCI support"
2584 default y
2585 ---help---
2586 Find out whether you have a PCI motherboard. PCI is the name of a
2587 bus system, i.e. the way the CPU talks to the other stuff inside
2588 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2589 VESA. If you have PCI, say Y, otherwise N.
2590
2591choice
2592 prompt "PCI access mode"
2593 depends on X86_32 && PCI
2594 default PCI_GOANY
2595 ---help---
2596 On PCI systems, the BIOS can be used to detect the PCI devices and
2597 determine their configuration. However, some old PCI motherboards
2598 have BIOS bugs and may crash if this is done. Also, some embedded
2599 PCI-based systems don't have any BIOS at all. Linux can also try to
2600 detect the PCI hardware directly without using the BIOS.
2601
2602 With this option, you can specify how Linux should detect the
2603 PCI devices. If you choose "BIOS", the BIOS will be used,
2604 if you choose "Direct", the BIOS won't be used, and if you
2605 choose "MMConfig", then PCI Express MMCONFIG will be used.
2606 If you choose "Any", the kernel will try MMCONFIG, then the
2607 direct access method and falls back to the BIOS if that doesn't
2608 work. If unsure, go with the default, which is "Any".
2609
2610config PCI_GOBIOS
2611 bool "BIOS"
2612
2613config PCI_GOMMCONFIG
2614 bool "MMConfig"
2615
2616config PCI_GODIRECT
2617 bool "Direct"
2618
2619config PCI_GOOLPC
2620 bool "OLPC XO-1"
2621 depends on OLPC
2622
2623config PCI_GOANY
2624 bool "Any"
2625
2626endchoice
2627
2628config PCI_BIOS
2629 def_bool y
2630 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2631
2632# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2633config PCI_DIRECT
2634 def_bool y
2635 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2636
2637config PCI_MMCONFIG
2638 bool "Support mmconfig PCI config space access" if X86_64
2639 default y
2640 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2641 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2642
2643config PCI_OLPC
2644 def_bool y
2645 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2646
2647config PCI_XEN
2648 def_bool y
2649 depends on PCI && XEN
2650 select SWIOTLB_XEN
2651
2652config PCI_DOMAINS
2653 def_bool y
2654 depends on PCI
2655
2656config MMCONF_FAM10H
2657 def_bool y
2658 depends on X86_64 && PCI_MMCONFIG && ACPI
2659
2660config PCI_CNB20LE_QUIRK
2661 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2662 depends on PCI
2663 help
2664 Read the PCI windows out of the CNB20LE host bridge. This allows
2665 PCI hotplug to work on systems with the CNB20LE chipset which do
2666 not have ACPI.
2667
2668 There's no public spec for this chipset, and this functionality
2669 is known to be incomplete.
2670
2671 You should say N unless you know you need this.
2672
2673source "drivers/pci/Kconfig"
2674
2675config ISA_BUS
2676 bool "ISA bus support on modern systems" if EXPERT
2677 help
2678 Expose ISA bus device drivers and options available for selection and
2679 configuration. Enable this option if your target machine has an ISA
2680 bus. ISA is an older system, displaced by PCI and newer bus
2681 architectures -- if your target machine is modern, it probably does
2682 not have an ISA bus.
2683
2684 If unsure, say N.
2685
2686# x86_64 have no ISA slots, but can have ISA-style DMA.
2687config ISA_DMA_API
2688 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2689 default y
2690 help
2691 Enables ISA-style DMA support for devices requiring such controllers.
2692 If unsure, say Y.
2693
2694if X86_32
2695
2696config ISA
2697 bool "ISA support"
2698 ---help---
2699 Find out whether you have ISA slots on your motherboard. ISA is the
2700 name of a bus system, i.e. the way the CPU talks to the other stuff
2701 inside your box. Other bus systems are PCI, EISA, MicroChannel
2702 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2703 newer boards don't support it. If you have ISA, say Y, otherwise N.
2704
2705config EISA
2706 bool "EISA support"
2707 depends on ISA
2708 ---help---
2709 The Extended Industry Standard Architecture (EISA) bus was
2710 developed as an open alternative to the IBM MicroChannel bus.
2711
2712 The EISA bus provided some of the features of the IBM MicroChannel
2713 bus while maintaining backward compatibility with cards made for
2714 the older ISA bus. The EISA bus saw limited use between 1988 and
2715 1995 when it was made obsolete by the PCI bus.
2716
2717 Say Y here if you are building a kernel for an EISA-based machine.
2718
2719 Otherwise, say N.
2720
2721source "drivers/eisa/Kconfig"
2722
2723config SCx200
2724 tristate "NatSemi SCx200 support"
2725 ---help---
2726 This provides basic support for National Semiconductor's
2727 (now AMD's) Geode processors. The driver probes for the
2728 PCI-IDs of several on-chip devices, so its a good dependency
2729 for other scx200_* drivers.
2730
2731 If compiled as a module, the driver is named scx200.
2732
2733config SCx200HR_TIMER
2734 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2735 depends on SCx200
2736 default y
2737 ---help---
2738 This driver provides a clocksource built upon the on-chip
2739 27MHz high-resolution timer. Its also a workaround for
2740 NSC Geode SC-1100's buggy TSC, which loses time when the
2741 processor goes idle (as is done by the scheduler). The
2742 other workaround is idle=poll boot option.
2743
2744config OLPC
2745 bool "One Laptop Per Child support"
2746 depends on !X86_PAE
2747 select GPIOLIB
2748 select OF
2749 select OF_PROMTREE
2750 select IRQ_DOMAIN
2751 ---help---
2752 Add support for detecting the unique features of the OLPC
2753 XO hardware.
2754
2755config OLPC_XO1_PM
2756 bool "OLPC XO-1 Power Management"
2757 depends on OLPC && MFD_CS5535 && PM_SLEEP
2758 select MFD_CORE
2759 ---help---
2760 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2761
2762config OLPC_XO1_RTC
2763 bool "OLPC XO-1 Real Time Clock"
2764 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2765 ---help---
2766 Add support for the XO-1 real time clock, which can be used as a
2767 programmable wakeup source.
2768
2769config OLPC_XO1_SCI
2770 bool "OLPC XO-1 SCI extras"
2771 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2772 depends on INPUT=y
2773 select POWER_SUPPLY
2774 ---help---
2775 Add support for SCI-based features of the OLPC XO-1 laptop:
2776 - EC-driven system wakeups
2777 - Power button
2778 - Ebook switch
2779 - Lid switch
2780 - AC adapter status updates
2781 - Battery status updates
2782
2783config OLPC_XO15_SCI
2784 bool "OLPC XO-1.5 SCI extras"
2785 depends on OLPC && ACPI
2786 select POWER_SUPPLY
2787 ---help---
2788 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2789 - EC-driven system wakeups
2790 - AC adapter status updates
2791 - Battery status updates
2792
2793config ALIX
2794 bool "PCEngines ALIX System Support (LED setup)"
2795 select GPIOLIB
2796 ---help---
2797 This option enables system support for the PCEngines ALIX.
2798 At present this just sets up LEDs for GPIO control on
2799 ALIX2/3/6 boards. However, other system specific setup should
2800 get added here.
2801
2802 Note: You must still enable the drivers for GPIO and LED support
2803 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2804
2805 Note: You have to set alix.force=1 for boards with Award BIOS.
2806
2807config NET5501
2808 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2809 select GPIOLIB
2810 ---help---
2811 This option enables system support for the Soekris Engineering net5501.
2812
2813config GEOS
2814 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2815 select GPIOLIB
2816 depends on DMI
2817 ---help---
2818 This option enables system support for the Traverse Technologies GEOS.
2819
2820config TS5500
2821 bool "Technologic Systems TS-5500 platform support"
2822 depends on MELAN
2823 select CHECK_SIGNATURE
2824 select NEW_LEDS
2825 select LEDS_CLASS
2826 ---help---
2827 This option enables system support for the Technologic Systems TS-5500.
2828
2829endif # X86_32
2830
2831config AMD_NB
2832 def_bool y
2833 depends on CPU_SUP_AMD && PCI
2834
2835source "drivers/pcmcia/Kconfig"
2836
2837config RAPIDIO
2838 tristate "RapidIO support"
2839 depends on PCI
2840 default n
2841 help
2842 If enabled this option will include drivers and the core
2843 infrastructure code to support RapidIO interconnect devices.
2844
2845source "drivers/rapidio/Kconfig"
2846
2847config X86_SYSFB
2848 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2849 help
2850 Firmwares often provide initial graphics framebuffers so the BIOS,
2851 bootloader or kernel can show basic video-output during boot for
2852 user-guidance and debugging. Historically, x86 used the VESA BIOS
2853 Extensions and EFI-framebuffers for this, which are mostly limited
2854 to x86.
2855 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2856 framebuffers so the new generic system-framebuffer drivers can be
2857 used on x86. If the framebuffer is not compatible with the generic
2858 modes, it is adverticed as fallback platform framebuffer so legacy
2859 drivers like efifb, vesafb and uvesafb can pick it up.
2860 If this option is not selected, all system framebuffers are always
2861 marked as fallback platform framebuffers as usual.
2862
2863 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2864 not be able to pick up generic system framebuffers if this option
2865 is selected. You are highly encouraged to enable simplefb as
2866 replacement if you select this option. simplefb can correctly deal
2867 with generic system framebuffers. But you should still keep vesafb
2868 and others enabled as fallback if a system framebuffer is
2869 incompatible with simplefb.
2870
2871 If unsure, say Y.
2872
2873endmenu
2874
2875
2876menu "Executable file formats / Emulations"
2877
2878source "fs/Kconfig.binfmt"
2879
2880config IA32_EMULATION
2881 bool "IA32 Emulation"
2882 depends on X86_64
2883 select ARCH_WANT_OLD_COMPAT_IPC
2884 select BINFMT_ELF
2885 select COMPAT_BINFMT_ELF
2886 select COMPAT_OLD_SIGACTION
2887 ---help---
2888 Include code to run legacy 32-bit programs under a
2889 64-bit kernel. You should likely turn this on, unless you're
2890 100% sure that you don't have any 32-bit programs left.
2891
2892config IA32_AOUT
2893 tristate "IA32 a.out support"
2894 depends on IA32_EMULATION
2895 ---help---
2896 Support old a.out binaries in the 32bit emulation.
2897
2898config X86_X32
2899 bool "x32 ABI for 64-bit mode"
2900 depends on X86_64
2901 ---help---
2902 Include code to run binaries for the x32 native 32-bit ABI
2903 for 64-bit processors. An x32 process gets access to the
2904 full 64-bit register file and wide data path while leaving
2905 pointers at 32 bits for smaller memory footprint.
2906
2907 You will need a recent binutils (2.22 or later) with
2908 elf32_x86_64 support enabled to compile a kernel with this
2909 option set.
2910
2911config COMPAT_32
2912 def_bool y
2913 depends on IA32_EMULATION || X86_32
2914 select HAVE_UID16
2915 select OLD_SIGSUSPEND3
2916
2917config COMPAT
2918 def_bool y
2919 depends on IA32_EMULATION || X86_X32
2920
2921if COMPAT
2922config COMPAT_FOR_U64_ALIGNMENT
2923 def_bool y
2924
2925config SYSVIPC_COMPAT
2926 def_bool y
2927 depends on SYSVIPC
2928endif
2929
2930endmenu
2931
2932
2933config HAVE_ATOMIC_IOMAP
2934 def_bool y
2935 depends on X86_32
2936
2937config X86_DEV_DMA_OPS
2938 bool
2939 depends on X86_64 || STA2X11
2940
2941config X86_DMA_REMAP
2942 bool
2943 depends on STA2X11
2944
2945config HAVE_GENERIC_GUP
2946 def_bool y
2947
2948source "net/Kconfig"
2949
2950source "drivers/Kconfig"
2951
2952source "drivers/firmware/Kconfig"
2953
2954source "fs/Kconfig"
2955
2956source "arch/x86/Kconfig.debug"
2957
2958source "security/Kconfig"
2959
2960source "crypto/Kconfig"
2961
2962source "arch/x86/kvm/Kconfig"
2963
2964source "lib/Kconfig"