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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 HAVE_DEBUG_STACKOVERFLOW
18 select MODULES_USE_ELF_REL
19 select OLD_SIGACTION
20 select GENERIC_VDSO_32
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
27 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select NEED_DMA_MAP_STATE
32 select SWIOTLB
33
34config FORCE_DYNAMIC_FTRACE
35 def_bool y
36 depends on X86_32
37 depends on FUNCTION_TRACER
38 select DYNAMIC_FTRACE
39 help
40 We keep the static function tracing (!DYNAMIC_FTRACE) around
41 in order to test the non static function tracing in the
42 generic code, as other architectures still use it. But we
43 only need to keep it around for x86_64. No need to keep it
44 for x86_32. For x86_32, force DYNAMIC_FTRACE.
45#
46# Arch settings
47#
48# ( Note that options that are marked 'if X86_64' could in principle be
49# ported to 32-bit as well. )
50#
51config X86
52 def_bool y
53 #
54 # Note: keep this list sorted alphabetically
55 #
56 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
57 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
58 select ARCH_32BIT_OFF_T if X86_32
59 select ARCH_CLOCKSOURCE_INIT
60 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
61 select ARCH_HAS_DEBUG_VIRTUAL
62 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
63 select ARCH_HAS_DEVMEM_IS_ALLOWED
64 select ARCH_HAS_EARLY_DEBUG if KGDB
65 select ARCH_HAS_ELF_RANDOMIZE
66 select ARCH_HAS_FAST_MULTIPLIER
67 select ARCH_HAS_FILTER_PGPROT
68 select ARCH_HAS_FORTIFY_SOURCE
69 select ARCH_HAS_GCOV_PROFILE_ALL
70 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
71 select ARCH_HAS_MEM_ENCRYPT
72 select ARCH_HAS_MEMBARRIER_SYNC_CORE
73 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
74 select ARCH_HAS_PMEM_API if X86_64
75 select ARCH_HAS_PTE_DEVMAP if X86_64
76 select ARCH_HAS_PTE_SPECIAL
77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
78 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
79 select ARCH_HAS_SET_MEMORY
80 select ARCH_HAS_SET_DIRECT_MAP
81 select ARCH_HAS_STRICT_KERNEL_RWX
82 select ARCH_HAS_STRICT_MODULE_RWX
83 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
84 select ARCH_HAS_SYSCALL_WRAPPER
85 select ARCH_HAS_UBSAN_SANITIZE_ALL
86 select ARCH_HAS_DEBUG_WX
87 select ARCH_HAVE_NMI_SAFE_CMPXCHG
88 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
89 select ARCH_MIGHT_HAVE_PC_PARPORT
90 select ARCH_MIGHT_HAVE_PC_SERIO
91 select ARCH_STACKWALK
92 select ARCH_SUPPORTS_ACPI
93 select ARCH_SUPPORTS_ATOMIC_RMW
94 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
95 select ARCH_USE_BUILTIN_BSWAP
96 select ARCH_USE_QUEUED_RWLOCKS
97 select ARCH_USE_QUEUED_SPINLOCKS
98 select ARCH_USE_SYM_ANNOTATIONS
99 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
100 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
101 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
102 select ARCH_WANT_HUGE_PMD_SHARE
103 select ARCH_WANTS_THP_SWAP if X86_64
104 select BUILDTIME_TABLE_SORT
105 select CLKEVT_I8253
106 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
107 select CLOCKSOURCE_WATCHDOG
108 select DCACHE_WORD_ACCESS
109 select EDAC_ATOMIC_SCRUB
110 select EDAC_SUPPORT
111 select GENERIC_CLOCKEVENTS
112 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
113 select GENERIC_CLOCKEVENTS_MIN_ADJUST
114 select GENERIC_CMOS_UPDATE
115 select GENERIC_CPU_AUTOPROBE
116 select GENERIC_CPU_VULNERABILITIES
117 select GENERIC_EARLY_IOREMAP
118 select GENERIC_ENTRY
119 select GENERIC_FIND_FIRST_BIT
120 select GENERIC_IOMAP
121 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
122 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
123 select GENERIC_IRQ_MIGRATION if SMP
124 select GENERIC_IRQ_PROBE
125 select GENERIC_IRQ_RESERVATION_MODE
126 select GENERIC_IRQ_SHOW
127 select GENERIC_PENDING_IRQ if SMP
128 select GENERIC_PTDUMP
129 select GENERIC_SMP_IDLE_THREAD
130 select GENERIC_STRNCPY_FROM_USER
131 select GENERIC_STRNLEN_USER
132 select GENERIC_TIME_VSYSCALL
133 select GENERIC_GETTIMEOFDAY
134 select GENERIC_VDSO_TIME_NS
135 select GUP_GET_PTE_LOW_HIGH if X86_PAE
136 select HARDIRQS_SW_RESEND
137 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
138 select HAVE_ACPI_APEI if ACPI
139 select HAVE_ACPI_APEI_NMI if ACPI
140 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
141 select HAVE_ARCH_AUDITSYSCALL
142 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
143 select HAVE_ARCH_JUMP_LABEL
144 select HAVE_ARCH_JUMP_LABEL_RELATIVE
145 select HAVE_ARCH_KASAN if X86_64
146 select HAVE_ARCH_KASAN_VMALLOC if X86_64
147 select HAVE_ARCH_KGDB
148 select HAVE_ARCH_MMAP_RND_BITS if MMU
149 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
150 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
151 select HAVE_ARCH_PREL32_RELOCATIONS
152 select HAVE_ARCH_SECCOMP_FILTER
153 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
154 select HAVE_ARCH_STACKLEAK
155 select HAVE_ARCH_TRACEHOOK
156 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
157 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
158 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
159 select HAVE_ARCH_VMAP_STACK if X86_64
160 select HAVE_ARCH_WITHIN_STACK_FRAMES
161 select HAVE_ASM_MODVERSIONS
162 select HAVE_CMPXCHG_DOUBLE
163 select HAVE_CMPXCHG_LOCAL
164 select HAVE_CONTEXT_TRACKING if X86_64
165 select HAVE_C_RECORDMCOUNT
166 select HAVE_DEBUG_KMEMLEAK
167 select HAVE_DMA_CONTIGUOUS
168 select HAVE_DYNAMIC_FTRACE
169 select HAVE_DYNAMIC_FTRACE_WITH_REGS
170 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
171 select HAVE_EBPF_JIT
172 select HAVE_EFFICIENT_UNALIGNED_ACCESS
173 select HAVE_EISA
174 select HAVE_EXIT_THREAD
175 select HAVE_FAST_GUP
176 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
177 select HAVE_FTRACE_MCOUNT_RECORD
178 select HAVE_FUNCTION_GRAPH_TRACER
179 select HAVE_FUNCTION_TRACER
180 select HAVE_GCC_PLUGINS
181 select HAVE_HW_BREAKPOINT
182 select HAVE_IDE
183 select HAVE_IOREMAP_PROT
184 select HAVE_IRQ_TIME_ACCOUNTING
185 select HAVE_KERNEL_BZIP2
186 select HAVE_KERNEL_GZIP
187 select HAVE_KERNEL_LZ4
188 select HAVE_KERNEL_LZMA
189 select HAVE_KERNEL_LZO
190 select HAVE_KERNEL_XZ
191 select HAVE_KERNEL_ZSTD
192 select HAVE_KPROBES
193 select HAVE_KPROBES_ON_FTRACE
194 select HAVE_FUNCTION_ERROR_INJECTION
195 select HAVE_KRETPROBES
196 select HAVE_KVM
197 select HAVE_LIVEPATCH if X86_64
198 select HAVE_MIXED_BREAKPOINTS_REGS
199 select HAVE_MOD_ARCH_SPECIFIC
200 select HAVE_MOVE_PMD
201 select HAVE_NMI
202 select HAVE_OPROFILE
203 select HAVE_OPTPROBES
204 select HAVE_PCSPKR_PLATFORM
205 select HAVE_PERF_EVENTS
206 select HAVE_PERF_EVENTS_NMI
207 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
208 select HAVE_PCI
209 select HAVE_PERF_REGS
210 select HAVE_PERF_USER_STACK_DUMP
211 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
212 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
213 select HAVE_REGS_AND_STACK_ACCESS_API
214 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
215 select HAVE_FUNCTION_ARG_ACCESS_API
216 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
217 select HAVE_STACK_VALIDATION if X86_64
218 select HAVE_RSEQ
219 select HAVE_SYSCALL_TRACEPOINTS
220 select HAVE_UNSTABLE_SCHED_CLOCK
221 select HAVE_USER_RETURN_NOTIFIER
222 select HAVE_GENERIC_VDSO
223 select HOTPLUG_SMT if SMP
224 select IRQ_FORCED_THREADING
225 select NEED_SG_DMA_LENGTH
226 select PCI_DOMAINS if PCI
227 select PCI_LOCKLESS_CONFIG if PCI
228 select PERF_EVENTS
229 select RTC_LIB
230 select RTC_MC146818_LIB
231 select SPARSE_IRQ
232 select SRCU
233 select SYSCTL_EXCEPTION_TRACE
234 select THREAD_INFO_IN_TASK
235 select USER_STACKTRACE_SUPPORT
236 select VIRT_TO_BUS
237 select HAVE_ARCH_KCSAN if X86_64
238 select X86_FEATURE_NAMES if PROC_FS
239 select PROC_PID_ARCH_STATUS if PROC_FS
240 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
241
242config INSTRUCTION_DECODER
243 def_bool y
244 depends on KPROBES || PERF_EVENTS || UPROBES
245
246config OUTPUT_FORMAT
247 string
248 default "elf32-i386" if X86_32
249 default "elf64-x86-64" if X86_64
250
251config LOCKDEP_SUPPORT
252 def_bool y
253
254config STACKTRACE_SUPPORT
255 def_bool y
256
257config MMU
258 def_bool y
259
260config ARCH_MMAP_RND_BITS_MIN
261 default 28 if 64BIT
262 default 8
263
264config ARCH_MMAP_RND_BITS_MAX
265 default 32 if 64BIT
266 default 16
267
268config ARCH_MMAP_RND_COMPAT_BITS_MIN
269 default 8
270
271config ARCH_MMAP_RND_COMPAT_BITS_MAX
272 default 16
273
274config SBUS
275 bool
276
277config GENERIC_ISA_DMA
278 def_bool y
279 depends on ISA_DMA_API
280
281config GENERIC_BUG
282 def_bool y
283 depends on BUG
284 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
285
286config GENERIC_BUG_RELATIVE_POINTERS
287 bool
288
289config ARCH_MAY_HAVE_PC_FDC
290 def_bool y
291 depends on ISA_DMA_API
292
293config GENERIC_CALIBRATE_DELAY
294 def_bool y
295
296config ARCH_HAS_CPU_RELAX
297 def_bool y
298
299config ARCH_HAS_CACHE_LINE_SIZE
300 def_bool y
301
302config ARCH_HAS_FILTER_PGPROT
303 def_bool y
304
305config HAVE_SETUP_PER_CPU_AREA
306 def_bool y
307
308config NEED_PER_CPU_EMBED_FIRST_CHUNK
309 def_bool y
310
311config NEED_PER_CPU_PAGE_FIRST_CHUNK
312 def_bool y
313
314config ARCH_HIBERNATION_POSSIBLE
315 def_bool y
316
317config ARCH_SUSPEND_POSSIBLE
318 def_bool y
319
320config ARCH_WANT_GENERAL_HUGETLB
321 def_bool y
322
323config ZONE_DMA32
324 def_bool y if X86_64
325
326config AUDIT_ARCH
327 def_bool y if X86_64
328
329config ARCH_SUPPORTS_DEBUG_PAGEALLOC
330 def_bool y
331
332config KASAN_SHADOW_OFFSET
333 hex
334 depends on KASAN
335 default 0xdffffc0000000000
336
337config HAVE_INTEL_TXT
338 def_bool y
339 depends on INTEL_IOMMU && ACPI
340
341config X86_32_SMP
342 def_bool y
343 depends on X86_32 && SMP
344
345config X86_64_SMP
346 def_bool y
347 depends on X86_64 && SMP
348
349config X86_32_LAZY_GS
350 def_bool y
351 depends on X86_32 && !STACKPROTECTOR
352
353config ARCH_SUPPORTS_UPROBES
354 def_bool y
355
356config FIX_EARLYCON_MEM
357 def_bool y
358
359config DYNAMIC_PHYSICAL_MASK
360 bool
361
362config PGTABLE_LEVELS
363 int
364 default 5 if X86_5LEVEL
365 default 4 if X86_64
366 default 3 if X86_PAE
367 default 2
368
369config CC_HAS_SANE_STACKPROTECTOR
370 bool
371 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
372 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
373 help
374 We have to make sure stack protector is unconditionally disabled if
375 the compiler produces broken code.
376
377menu "Processor type and features"
378
379config ZONE_DMA
380 bool "DMA memory allocation support" if EXPERT
381 default y
382 help
383 DMA memory allocation support allows devices with less than 32-bit
384 addressing to allocate within the first 16MB of address space.
385 Disable if no such devices will be used.
386
387 If unsure, say Y.
388
389config SMP
390 bool "Symmetric multi-processing support"
391 help
392 This enables support for systems with more than one CPU. If you have
393 a system with only one CPU, say N. If you have a system with more
394 than one CPU, say Y.
395
396 If you say N here, the kernel will run on uni- and multiprocessor
397 machines, but will use only one CPU of a multiprocessor machine. If
398 you say Y here, the kernel will run on many, but not all,
399 uniprocessor machines. On a uniprocessor machine, the kernel
400 will run faster if you say N here.
401
402 Note that if you say Y here and choose architecture "586" or
403 "Pentium" under "Processor family", the kernel will not work on 486
404 architectures. Similarly, multiprocessor kernels for the "PPro"
405 architecture may not work on all Pentium based boards.
406
407 People using multiprocessor machines who say Y here should also say
408 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
409 Management" code will be disabled if you say Y here.
410
411 See also <file:Documentation/x86/i386/IO-APIC.rst>,
412 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
413 <http://www.tldp.org/docs.html#howto>.
414
415 If you don't know what to do here, say N.
416
417config X86_FEATURE_NAMES
418 bool "Processor feature human-readable names" if EMBEDDED
419 default y
420 help
421 This option compiles in a table of x86 feature bits and corresponding
422 names. This is required to support /proc/cpuinfo and a few kernel
423 messages. You can disable this to save space, at the expense of
424 making those few kernel messages show numeric feature bits instead.
425
426 If in doubt, say Y.
427
428config X86_X2APIC
429 bool "Support x2apic"
430 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
431 help
432 This enables x2apic support on CPUs that have this feature.
433
434 This allows 32-bit apic IDs (so it can support very large systems),
435 and accesses the local apic via MSRs not via mmio.
436
437 If you don't know what to do here, say N.
438
439config X86_MPPARSE
440 bool "Enable MPS table" if ACPI || SFI
441 default y
442 depends on X86_LOCAL_APIC
443 help
444 For old smp systems that do not have proper acpi support. Newer systems
445 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
446
447config GOLDFISH
448 def_bool y
449 depends on X86_GOLDFISH
450
451config RETPOLINE
452 bool "Avoid speculative indirect branches in kernel"
453 default y
454 select STACK_VALIDATION if HAVE_STACK_VALIDATION
455 help
456 Compile kernel with the retpoline compiler options to guard against
457 kernel-to-user data leaks by avoiding speculative indirect
458 branches. Requires a compiler with -mindirect-branch=thunk-extern
459 support for full protection. The kernel may run slower.
460
461config X86_CPU_RESCTRL
462 bool "x86 CPU resource control support"
463 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
464 select KERNFS
465 select PROC_CPU_RESCTRL if PROC_FS
466 help
467 Enable x86 CPU resource control support.
468
469 Provide support for the allocation and monitoring of system resources
470 usage by the CPU.
471
472 Intel calls this Intel Resource Director Technology
473 (Intel(R) RDT). More information about RDT can be found in the
474 Intel x86 Architecture Software Developer Manual.
475
476 AMD calls this AMD Platform Quality of Service (AMD QoS).
477 More information about AMD QoS can be found in the AMD64 Technology
478 Platform Quality of Service Extensions manual.
479
480 Say N if unsure.
481
482if X86_32
483config X86_BIGSMP
484 bool "Support for big SMP systems with more than 8 CPUs"
485 depends on SMP
486 help
487 This option is needed for the systems that have more than 8 CPUs.
488
489config X86_EXTENDED_PLATFORM
490 bool "Support for extended (non-PC) x86 platforms"
491 default y
492 help
493 If you disable this option then the kernel will only support
494 standard PC platforms. (which covers the vast majority of
495 systems out there.)
496
497 If you enable this option then you'll be able to select support
498 for the following (non-PC) 32 bit x86 platforms:
499 Goldfish (Android emulator)
500 AMD Elan
501 RDC R-321x SoC
502 SGI 320/540 (Visual Workstation)
503 STA2X11-based (e.g. Northville)
504 Moorestown MID devices
505
506 If you have one of these systems, or if you want to build a
507 generic distribution kernel, say Y here - otherwise say N.
508endif
509
510if X86_64
511config X86_EXTENDED_PLATFORM
512 bool "Support for extended (non-PC) x86 platforms"
513 default y
514 help
515 If you disable this option then the kernel will only support
516 standard PC platforms. (which covers the vast majority of
517 systems out there.)
518
519 If you enable this option then you'll be able to select support
520 for the following (non-PC) 64 bit x86 platforms:
521 Numascale NumaChip
522 ScaleMP vSMP
523 SGI Ultraviolet
524
525 If you have one of these systems, or if you want to build a
526 generic distribution kernel, say Y here - otherwise say N.
527endif
528# This is an alphabetically sorted list of 64 bit extended platforms
529# Please maintain the alphabetic order if and when there are additions
530config X86_NUMACHIP
531 bool "Numascale NumaChip"
532 depends on X86_64
533 depends on X86_EXTENDED_PLATFORM
534 depends on NUMA
535 depends on SMP
536 depends on X86_X2APIC
537 depends on PCI_MMCONFIG
538 help
539 Adds support for Numascale NumaChip large-SMP systems. Needed to
540 enable more than ~168 cores.
541 If you don't have one of these, you should say N here.
542
543config X86_VSMP
544 bool "ScaleMP vSMP"
545 select HYPERVISOR_GUEST
546 select PARAVIRT
547 depends on X86_64 && PCI
548 depends on X86_EXTENDED_PLATFORM
549 depends on SMP
550 help
551 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
552 supposed to run on these EM64T-based machines. Only choose this option
553 if you have one of these machines.
554
555config X86_UV
556 bool "SGI Ultraviolet"
557 depends on X86_64
558 depends on X86_EXTENDED_PLATFORM
559 depends on NUMA
560 depends on EFI
561 depends on X86_X2APIC
562 depends on PCI
563 help
564 This option is needed in order to support SGI Ultraviolet systems.
565 If you don't have one of these, you should say N here.
566
567# Following is an alphabetically sorted list of 32 bit extended platforms
568# Please maintain the alphabetic order if and when there are additions
569
570config X86_GOLDFISH
571 bool "Goldfish (Virtual Platform)"
572 depends on X86_EXTENDED_PLATFORM
573 help
574 Enable support for the Goldfish virtual platform used primarily
575 for Android development. Unless you are building for the Android
576 Goldfish emulator say N here.
577
578config X86_INTEL_CE
579 bool "CE4100 TV platform"
580 depends on PCI
581 depends on PCI_GODIRECT
582 depends on X86_IO_APIC
583 depends on X86_32
584 depends on X86_EXTENDED_PLATFORM
585 select X86_REBOOTFIXUPS
586 select OF
587 select OF_EARLY_FLATTREE
588 help
589 Select for the Intel CE media processor (CE4100) SOC.
590 This option compiles in support for the CE4100 SOC for settop
591 boxes and media devices.
592
593config X86_INTEL_MID
594 bool "Intel MID platform support"
595 depends on X86_EXTENDED_PLATFORM
596 depends on X86_PLATFORM_DEVICES
597 depends on PCI
598 depends on X86_64 || (PCI_GOANY && X86_32)
599 depends on X86_IO_APIC
600 select SFI
601 select I2C
602 select DW_APB_TIMER
603 select APB_TIMER
604 select INTEL_SCU_PCI
605 select MFD_INTEL_MSIC
606 help
607 Select to build a kernel capable of supporting Intel MID (Mobile
608 Internet Device) platform systems which do not have the PCI legacy
609 interfaces. If you are building for a PC class system say N here.
610
611 Intel MID platforms are based on an Intel processor and chipset which
612 consume less power than most of the x86 derivatives.
613
614config X86_INTEL_QUARK
615 bool "Intel Quark platform support"
616 depends on X86_32
617 depends on X86_EXTENDED_PLATFORM
618 depends on X86_PLATFORM_DEVICES
619 depends on X86_TSC
620 depends on PCI
621 depends on PCI_GOANY
622 depends on X86_IO_APIC
623 select IOSF_MBI
624 select INTEL_IMR
625 select COMMON_CLK
626 help
627 Select to include support for Quark X1000 SoC.
628 Say Y here if you have a Quark based system such as the Arduino
629 compatible Intel Galileo.
630
631config X86_INTEL_LPSS
632 bool "Intel Low Power Subsystem Support"
633 depends on X86 && ACPI && PCI
634 select COMMON_CLK
635 select PINCTRL
636 select IOSF_MBI
637 help
638 Select to build support for Intel Low Power Subsystem such as
639 found on Intel Lynxpoint PCH. Selecting this option enables
640 things like clock tree (common clock framework) and pincontrol
641 which are needed by the LPSS peripheral drivers.
642
643config X86_AMD_PLATFORM_DEVICE
644 bool "AMD ACPI2Platform devices support"
645 depends on ACPI
646 select COMMON_CLK
647 select PINCTRL
648 help
649 Select to interpret AMD specific ACPI device to platform device
650 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
651 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
652 implemented under PINCTRL subsystem.
653
654config IOSF_MBI
655 tristate "Intel SoC IOSF Sideband support for SoC platforms"
656 depends on PCI
657 help
658 This option enables sideband register access support for Intel SoC
659 platforms. On these platforms the IOSF sideband is used in lieu of
660 MSR's for some register accesses, mostly but not limited to thermal
661 and power. Drivers may query the availability of this device to
662 determine if they need the sideband in order to work on these
663 platforms. The sideband is available on the following SoC products.
664 This list is not meant to be exclusive.
665 - BayTrail
666 - Braswell
667 - Quark
668
669 You should say Y if you are running a kernel on one of these SoC's.
670
671config IOSF_MBI_DEBUG
672 bool "Enable IOSF sideband access through debugfs"
673 depends on IOSF_MBI && DEBUG_FS
674 help
675 Select this option to expose the IOSF sideband access registers (MCR,
676 MDR, MCRX) through debugfs to write and read register information from
677 different units on the SoC. This is most useful for obtaining device
678 state information for debug and analysis. As this is a general access
679 mechanism, users of this option would have specific knowledge of the
680 device they want to access.
681
682 If you don't require the option or are in doubt, say N.
683
684config X86_RDC321X
685 bool "RDC R-321x SoC"
686 depends on X86_32
687 depends on X86_EXTENDED_PLATFORM
688 select M486
689 select X86_REBOOTFIXUPS
690 help
691 This option is needed for RDC R-321x system-on-chip, also known
692 as R-8610-(G).
693 If you don't have one of these chips, you should say N here.
694
695config X86_32_NON_STANDARD
696 bool "Support non-standard 32-bit SMP architectures"
697 depends on X86_32 && SMP
698 depends on X86_EXTENDED_PLATFORM
699 help
700 This option compiles in the bigsmp and STA2X11 default
701 subarchitectures. It is intended for a generic binary
702 kernel. If you select them all, kernel will probe it one by
703 one and will fallback to default.
704
705# Alphabetically sorted list of Non standard 32 bit platforms
706
707config X86_SUPPORTS_MEMORY_FAILURE
708 def_bool y
709 # MCE code calls memory_failure():
710 depends on X86_MCE
711 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
712 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
713 depends on X86_64 || !SPARSEMEM
714 select ARCH_SUPPORTS_MEMORY_FAILURE
715
716config STA2X11
717 bool "STA2X11 Companion Chip Support"
718 depends on X86_32_NON_STANDARD && PCI
719 select SWIOTLB
720 select MFD_STA2X11
721 select GPIOLIB
722 help
723 This adds support for boards based on the STA2X11 IO-Hub,
724 a.k.a. "ConneXt". The chip is used in place of the standard
725 PC chipset, so all "standard" peripherals are missing. If this
726 option is selected the kernel will still be able to boot on
727 standard PC machines.
728
729config X86_32_IRIS
730 tristate "Eurobraille/Iris poweroff module"
731 depends on X86_32
732 help
733 The Iris machines from EuroBraille do not have APM or ACPI support
734 to shut themselves down properly. A special I/O sequence is
735 needed to do so, which is what this module does at
736 kernel shutdown.
737
738 This is only for Iris machines from EuroBraille.
739
740 If unused, say N.
741
742config SCHED_OMIT_FRAME_POINTER
743 def_bool y
744 prompt "Single-depth WCHAN output"
745 depends on X86
746 help
747 Calculate simpler /proc/<PID>/wchan values. If this option
748 is disabled then wchan values will recurse back to the
749 caller function. This provides more accurate wchan values,
750 at the expense of slightly more scheduling overhead.
751
752 If in doubt, say "Y".
753
754menuconfig HYPERVISOR_GUEST
755 bool "Linux guest support"
756 help
757 Say Y here to enable options for running Linux under various hyper-
758 visors. This option enables basic hypervisor detection and platform
759 setup.
760
761 If you say N, all options in this submenu will be skipped and
762 disabled, and Linux guest support won't be built in.
763
764if HYPERVISOR_GUEST
765
766config PARAVIRT
767 bool "Enable paravirtualization code"
768 help
769 This changes the kernel so it can modify itself when it is run
770 under a hypervisor, potentially improving performance significantly
771 over full virtualization. However, when run without a hypervisor
772 the kernel is theoretically slower and slightly larger.
773
774config PARAVIRT_XXL
775 bool
776
777config PARAVIRT_DEBUG
778 bool "paravirt-ops debugging"
779 depends on PARAVIRT && DEBUG_KERNEL
780 help
781 Enable to debug paravirt_ops internals. Specifically, BUG if
782 a paravirt_op is missing when it is called.
783
784config PARAVIRT_SPINLOCKS
785 bool "Paravirtualization layer for spinlocks"
786 depends on PARAVIRT && SMP
787 help
788 Paravirtualized spinlocks allow a pvops backend to replace the
789 spinlock implementation with something virtualization-friendly
790 (for example, block the virtual CPU rather than spinning).
791
792 It has a minimal impact on native kernels and gives a nice performance
793 benefit on paravirtualized KVM / Xen kernels.
794
795 If you are unsure how to answer this question, answer Y.
796
797config X86_HV_CALLBACK_VECTOR
798 def_bool n
799
800source "arch/x86/xen/Kconfig"
801
802config KVM_GUEST
803 bool "KVM Guest support (including kvmclock)"
804 depends on PARAVIRT
805 select PARAVIRT_CLOCK
806 select ARCH_CPUIDLE_HALTPOLL
807 select X86_HV_CALLBACK_VECTOR
808 default y
809 help
810 This option enables various optimizations for running under the KVM
811 hypervisor. It includes a paravirtualized clock, so that instead
812 of relying on a PIT (or probably other) emulation by the
813 underlying device model, the host provides the guest with
814 timing infrastructure such as time of day, and system time
815
816config ARCH_CPUIDLE_HALTPOLL
817 def_bool n
818 prompt "Disable host haltpoll when loading haltpoll driver"
819 help
820 If virtualized under KVM, disable host haltpoll.
821
822config PVH
823 bool "Support for running PVH guests"
824 help
825 This option enables the PVH entry point for guest virtual machines
826 as specified in the x86/HVM direct boot ABI.
827
828config PARAVIRT_TIME_ACCOUNTING
829 bool "Paravirtual steal time accounting"
830 depends on PARAVIRT
831 help
832 Select this option to enable fine granularity task steal time
833 accounting. Time spent executing other tasks in parallel with
834 the current vCPU is discounted from the vCPU power. To account for
835 that, there can be a small performance impact.
836
837 If in doubt, say N here.
838
839config PARAVIRT_CLOCK
840 bool
841
842config JAILHOUSE_GUEST
843 bool "Jailhouse non-root cell support"
844 depends on X86_64 && PCI
845 select X86_PM_TIMER
846 help
847 This option allows to run Linux as guest in a Jailhouse non-root
848 cell. You can leave this option disabled if you only want to start
849 Jailhouse and run Linux afterwards in the root cell.
850
851config ACRN_GUEST
852 bool "ACRN Guest support"
853 depends on X86_64
854 select X86_HV_CALLBACK_VECTOR
855 help
856 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
857 a flexible, lightweight reference open-source hypervisor, built with
858 real-time and safety-criticality in mind. It is built for embedded
859 IOT with small footprint and real-time features. More details can be
860 found in https://projectacrn.org/.
861
862endif #HYPERVISOR_GUEST
863
864source "arch/x86/Kconfig.cpu"
865
866config HPET_TIMER
867 def_bool X86_64
868 prompt "HPET Timer Support" if X86_32
869 help
870 Use the IA-PC HPET (High Precision Event Timer) to manage
871 time in preference to the PIT and RTC, if a HPET is
872 present.
873 HPET is the next generation timer replacing legacy 8254s.
874 The HPET provides a stable time base on SMP
875 systems, unlike the TSC, but it is more expensive to access,
876 as it is off-chip. The interface used is documented
877 in the HPET spec, revision 1.
878
879 You can safely choose Y here. However, HPET will only be
880 activated if the platform and the BIOS support this feature.
881 Otherwise the 8254 will be used for timing services.
882
883 Choose N to continue using the legacy 8254 timer.
884
885config HPET_EMULATE_RTC
886 def_bool y
887 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
888
889config APB_TIMER
890 def_bool y if X86_INTEL_MID
891 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
892 select DW_APB_TIMER
893 depends on X86_INTEL_MID && SFI
894 help
895 APB timer is the replacement for 8254, HPET on X86 MID platforms.
896 The APBT provides a stable time base on SMP
897 systems, unlike the TSC, but it is more expensive to access,
898 as it is off-chip. APB timers are always running regardless of CPU
899 C states, they are used as per CPU clockevent device when possible.
900
901# Mark as expert because too many people got it wrong.
902# The code disables itself when not needed.
903config DMI
904 default y
905 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
906 bool "Enable DMI scanning" if EXPERT
907 help
908 Enabled scanning of DMI to identify machine quirks. Say Y
909 here unless you have verified that your setup is not
910 affected by entries in the DMI blacklist. Required by PNP
911 BIOS code.
912
913config GART_IOMMU
914 bool "Old AMD GART IOMMU support"
915 select DMA_OPS
916 select IOMMU_HELPER
917 select SWIOTLB
918 depends on X86_64 && PCI && AMD_NB
919 help
920 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
921 GART based hardware IOMMUs.
922
923 The GART supports full DMA access for devices with 32-bit access
924 limitations, on systems with more than 3 GB. This is usually needed
925 for USB, sound, many IDE/SATA chipsets and some other devices.
926
927 Newer systems typically have a modern AMD IOMMU, supported via
928 the CONFIG_AMD_IOMMU=y config option.
929
930 In normal configurations this driver is only active when needed:
931 there's more than 3 GB of memory and the system contains a
932 32-bit limited device.
933
934 If unsure, say Y.
935
936config MAXSMP
937 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
938 depends on X86_64 && SMP && DEBUG_KERNEL
939 select CPUMASK_OFFSTACK
940 help
941 Enable maximum number of CPUS and NUMA Nodes for this architecture.
942 If unsure, say N.
943
944#
945# The maximum number of CPUs supported:
946#
947# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
948# and which can be configured interactively in the
949# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
950#
951# The ranges are different on 32-bit and 64-bit kernels, depending on
952# hardware capabilities and scalability features of the kernel.
953#
954# ( If MAXSMP is enabled we just use the highest possible value and disable
955# interactive configuration. )
956#
957
958config NR_CPUS_RANGE_BEGIN
959 int
960 default NR_CPUS_RANGE_END if MAXSMP
961 default 1 if !SMP
962 default 2
963
964config NR_CPUS_RANGE_END
965 int
966 depends on X86_32
967 default 64 if SMP && X86_BIGSMP
968 default 8 if SMP && !X86_BIGSMP
969 default 1 if !SMP
970
971config NR_CPUS_RANGE_END
972 int
973 depends on X86_64
974 default 8192 if SMP && CPUMASK_OFFSTACK
975 default 512 if SMP && !CPUMASK_OFFSTACK
976 default 1 if !SMP
977
978config NR_CPUS_DEFAULT
979 int
980 depends on X86_32
981 default 32 if X86_BIGSMP
982 default 8 if SMP
983 default 1 if !SMP
984
985config NR_CPUS_DEFAULT
986 int
987 depends on X86_64
988 default 8192 if MAXSMP
989 default 64 if SMP
990 default 1 if !SMP
991
992config NR_CPUS
993 int "Maximum number of CPUs" if SMP && !MAXSMP
994 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
995 default NR_CPUS_DEFAULT
996 help
997 This allows you to specify the maximum number of CPUs which this
998 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
999 supported value is 8192, otherwise the maximum value is 512. The
1000 minimum value which makes sense is 2.
1001
1002 This is purely to save memory: each supported CPU adds about 8KB
1003 to the kernel image.
1004
1005config SCHED_SMT
1006 def_bool y if SMP
1007
1008config SCHED_MC
1009 def_bool y
1010 prompt "Multi-core scheduler support"
1011 depends on SMP
1012 help
1013 Multi-core scheduler support improves the CPU scheduler's decision
1014 making when dealing with multi-core CPU chips at a cost of slightly
1015 increased overhead in some places. If unsure say N here.
1016
1017config SCHED_MC_PRIO
1018 bool "CPU core priorities scheduler support"
1019 depends on SCHED_MC && CPU_SUP_INTEL
1020 select X86_INTEL_PSTATE
1021 select CPU_FREQ
1022 default y
1023 help
1024 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1025 core ordering determined at manufacturing time, which allows
1026 certain cores to reach higher turbo frequencies (when running
1027 single threaded workloads) than others.
1028
1029 Enabling this kernel feature teaches the scheduler about
1030 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1031 scheduler's CPU selection logic accordingly, so that higher
1032 overall system performance can be achieved.
1033
1034 This feature will have no effect on CPUs without this feature.
1035
1036 If unsure say Y here.
1037
1038config UP_LATE_INIT
1039 def_bool y
1040 depends on !SMP && X86_LOCAL_APIC
1041
1042config X86_UP_APIC
1043 bool "Local APIC support on uniprocessors" if !PCI_MSI
1044 default PCI_MSI
1045 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1046 help
1047 A local APIC (Advanced Programmable Interrupt Controller) is an
1048 integrated interrupt controller in the CPU. If you have a single-CPU
1049 system which has a processor with a local APIC, you can say Y here to
1050 enable and use it. If you say Y here even though your machine doesn't
1051 have a local APIC, then the kernel will still run with no slowdown at
1052 all. The local APIC supports CPU-generated self-interrupts (timer,
1053 performance counters), and the NMI watchdog which detects hard
1054 lockups.
1055
1056config X86_UP_IOAPIC
1057 bool "IO-APIC support on uniprocessors"
1058 depends on X86_UP_APIC
1059 help
1060 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1061 SMP-capable replacement for PC-style interrupt controllers. Most
1062 SMP systems and many recent uniprocessor systems have one.
1063
1064 If you have a single-CPU system with an IO-APIC, you can say Y here
1065 to use it. If you say Y here even though your machine doesn't have
1066 an IO-APIC, then the kernel will still run with no slowdown at all.
1067
1068config X86_LOCAL_APIC
1069 def_bool y
1070 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1071 select IRQ_DOMAIN_HIERARCHY
1072 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1073
1074config X86_IO_APIC
1075 def_bool y
1076 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1077
1078config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1079 bool "Reroute for broken boot IRQs"
1080 depends on X86_IO_APIC
1081 help
1082 This option enables a workaround that fixes a source of
1083 spurious interrupts. This is recommended when threaded
1084 interrupt handling is used on systems where the generation of
1085 superfluous "boot interrupts" cannot be disabled.
1086
1087 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1088 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1089 kernel does during interrupt handling). On chipsets where this
1090 boot IRQ generation cannot be disabled, this workaround keeps
1091 the original IRQ line masked so that only the equivalent "boot
1092 IRQ" is delivered to the CPUs. The workaround also tells the
1093 kernel to set up the IRQ handler on the boot IRQ line. In this
1094 way only one interrupt is delivered to the kernel. Otherwise
1095 the spurious second interrupt may cause the kernel to bring
1096 down (vital) interrupt lines.
1097
1098 Only affects "broken" chipsets. Interrupt sharing may be
1099 increased on these systems.
1100
1101config X86_MCE
1102 bool "Machine Check / overheating reporting"
1103 select GENERIC_ALLOCATOR
1104 default y
1105 help
1106 Machine Check support allows the processor to notify the
1107 kernel if it detects a problem (e.g. overheating, data corruption).
1108 The action the kernel takes depends on the severity of the problem,
1109 ranging from warning messages to halting the machine.
1110
1111config X86_MCELOG_LEGACY
1112 bool "Support for deprecated /dev/mcelog character device"
1113 depends on X86_MCE
1114 help
1115 Enable support for /dev/mcelog which is needed by the old mcelog
1116 userspace logging daemon. Consider switching to the new generation
1117 rasdaemon solution.
1118
1119config X86_MCE_INTEL
1120 def_bool y
1121 prompt "Intel MCE features"
1122 depends on X86_MCE && X86_LOCAL_APIC
1123 help
1124 Additional support for intel specific MCE features such as
1125 the thermal monitor.
1126
1127config X86_MCE_AMD
1128 def_bool y
1129 prompt "AMD MCE features"
1130 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1131 help
1132 Additional support for AMD specific MCE features such as
1133 the DRAM Error Threshold.
1134
1135config X86_ANCIENT_MCE
1136 bool "Support for old Pentium 5 / WinChip machine checks"
1137 depends on X86_32 && X86_MCE
1138 help
1139 Include support for machine check handling on old Pentium 5 or WinChip
1140 systems. These typically need to be enabled explicitly on the command
1141 line.
1142
1143config X86_MCE_THRESHOLD
1144 depends on X86_MCE_AMD || X86_MCE_INTEL
1145 def_bool y
1146
1147config X86_MCE_INJECT
1148 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1149 tristate "Machine check injector support"
1150 help
1151 Provide support for injecting machine checks for testing purposes.
1152 If you don't know what a machine check is and you don't do kernel
1153 QA it is safe to say n.
1154
1155config X86_THERMAL_VECTOR
1156 def_bool y
1157 depends on X86_MCE_INTEL
1158
1159source "arch/x86/events/Kconfig"
1160
1161config X86_LEGACY_VM86
1162 bool "Legacy VM86 support"
1163 depends on X86_32
1164 help
1165 This option allows user programs to put the CPU into V8086
1166 mode, which is an 80286-era approximation of 16-bit real mode.
1167
1168 Some very old versions of X and/or vbetool require this option
1169 for user mode setting. Similarly, DOSEMU will use it if
1170 available to accelerate real mode DOS programs. However, any
1171 recent version of DOSEMU, X, or vbetool should be fully
1172 functional even without kernel VM86 support, as they will all
1173 fall back to software emulation. Nevertheless, if you are using
1174 a 16-bit DOS program where 16-bit performance matters, vm86
1175 mode might be faster than emulation and you might want to
1176 enable this option.
1177
1178 Note that any app that works on a 64-bit kernel is unlikely to
1179 need this option, as 64-bit kernels don't, and can't, support
1180 V8086 mode. This option is also unrelated to 16-bit protected
1181 mode and is not needed to run most 16-bit programs under Wine.
1182
1183 Enabling this option increases the complexity of the kernel
1184 and slows down exception handling a tiny bit.
1185
1186 If unsure, say N here.
1187
1188config VM86
1189 bool
1190 default X86_LEGACY_VM86
1191
1192config X86_16BIT
1193 bool "Enable support for 16-bit segments" if EXPERT
1194 default y
1195 depends on MODIFY_LDT_SYSCALL
1196 help
1197 This option is required by programs like Wine to run 16-bit
1198 protected mode legacy code on x86 processors. Disabling
1199 this option saves about 300 bytes on i386, or around 6K text
1200 plus 16K runtime memory on x86-64,
1201
1202config X86_ESPFIX32
1203 def_bool y
1204 depends on X86_16BIT && X86_32
1205
1206config X86_ESPFIX64
1207 def_bool y
1208 depends on X86_16BIT && X86_64
1209
1210config X86_VSYSCALL_EMULATION
1211 bool "Enable vsyscall emulation" if EXPERT
1212 default y
1213 depends on X86_64
1214 help
1215 This enables emulation of the legacy vsyscall page. Disabling
1216 it is roughly equivalent to booting with vsyscall=none, except
1217 that it will also disable the helpful warning if a program
1218 tries to use a vsyscall. With this option set to N, offending
1219 programs will just segfault, citing addresses of the form
1220 0xffffffffff600?00.
1221
1222 This option is required by many programs built before 2013, and
1223 care should be used even with newer programs if set to N.
1224
1225 Disabling this option saves about 7K of kernel size and
1226 possibly 4K of additional runtime pagetable memory.
1227
1228config X86_IOPL_IOPERM
1229 bool "IOPERM and IOPL Emulation"
1230 default y
1231 help
1232 This enables the ioperm() and iopl() syscalls which are necessary
1233 for legacy applications.
1234
1235 Legacy IOPL support is an overbroad mechanism which allows user
1236 space aside of accessing all 65536 I/O ports also to disable
1237 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1238 capabilities and permission from potentially active security
1239 modules.
1240
1241 The emulation restricts the functionality of the syscall to
1242 only allowing the full range I/O port access, but prevents the
1243 ability to disable interrupts from user space which would be
1244 granted if the hardware IOPL mechanism would be used.
1245
1246config TOSHIBA
1247 tristate "Toshiba Laptop support"
1248 depends on X86_32
1249 help
1250 This adds a driver to safely access the System Management Mode of
1251 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1252 not work on models with a Phoenix BIOS. The System Management Mode
1253 is used to set the BIOS and power saving options on Toshiba portables.
1254
1255 For information on utilities to make use of this driver see the
1256 Toshiba Linux utilities web site at:
1257 <http://www.buzzard.org.uk/toshiba/>.
1258
1259 Say Y if you intend to run this kernel on a Toshiba portable.
1260 Say N otherwise.
1261
1262config I8K
1263 tristate "Dell i8k legacy laptop support"
1264 select HWMON
1265 select SENSORS_DELL_SMM
1266 help
1267 This option enables legacy /proc/i8k userspace interface in hwmon
1268 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1269 temperature and allows controlling fan speeds of Dell laptops via
1270 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1271 it reports also power and hotkey status. For fan speed control is
1272 needed userspace package i8kutils.
1273
1274 Say Y if you intend to run this kernel on old Dell laptops or want to
1275 use userspace package i8kutils.
1276 Say N otherwise.
1277
1278config X86_REBOOTFIXUPS
1279 bool "Enable X86 board specific fixups for reboot"
1280 depends on X86_32
1281 help
1282 This enables chipset and/or board specific fixups to be done
1283 in order to get reboot to work correctly. This is only needed on
1284 some combinations of hardware and BIOS. The symptom, for which
1285 this config is intended, is when reboot ends with a stalled/hung
1286 system.
1287
1288 Currently, the only fixup is for the Geode machines using
1289 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1290
1291 Say Y if you want to enable the fixup. Currently, it's safe to
1292 enable this option even if you don't need it.
1293 Say N otherwise.
1294
1295config MICROCODE
1296 bool "CPU microcode loading support"
1297 default y
1298 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1299 help
1300 If you say Y here, you will be able to update the microcode on
1301 Intel and AMD processors. The Intel support is for the IA32 family,
1302 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1303 AMD support is for families 0x10 and later. You will obviously need
1304 the actual microcode binary data itself which is not shipped with
1305 the Linux kernel.
1306
1307 The preferred method to load microcode from a detached initrd is described
1308 in Documentation/x86/microcode.rst. For that you need to enable
1309 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1310 initrd for microcode blobs.
1311
1312 In addition, you can build the microcode into the kernel. For that you
1313 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1314 config option.
1315
1316config MICROCODE_INTEL
1317 bool "Intel microcode loading support"
1318 depends on MICROCODE
1319 default MICROCODE
1320 help
1321 This options enables microcode patch loading support for Intel
1322 processors.
1323
1324 For the current Intel microcode data package go to
1325 <https://downloadcenter.intel.com> and search for
1326 'Linux Processor Microcode Data File'.
1327
1328config MICROCODE_AMD
1329 bool "AMD microcode loading support"
1330 depends on MICROCODE
1331 help
1332 If you select this option, microcode patch loading support for AMD
1333 processors will be enabled.
1334
1335config MICROCODE_OLD_INTERFACE
1336 bool "Ancient loading interface (DEPRECATED)"
1337 default n
1338 depends on MICROCODE
1339 help
1340 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1341 which was used by userspace tools like iucode_tool and microcode.ctl.
1342 It is inadequate because it runs too late to be able to properly
1343 load microcode on a machine and it needs special tools. Instead, you
1344 should've switched to the early loading method with the initrd or
1345 builtin microcode by now: Documentation/x86/microcode.rst
1346
1347config X86_MSR
1348 tristate "/dev/cpu/*/msr - Model-specific register support"
1349 help
1350 This device gives privileged processes access to the x86
1351 Model-Specific Registers (MSRs). It is a character device with
1352 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1353 MSR accesses are directed to a specific CPU on multi-processor
1354 systems.
1355
1356config X86_CPUID
1357 tristate "/dev/cpu/*/cpuid - CPU information support"
1358 help
1359 This device gives processes access to the x86 CPUID instruction to
1360 be executed on a specific processor. It is a character device
1361 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1362 /dev/cpu/31/cpuid.
1363
1364choice
1365 prompt "High Memory Support"
1366 default HIGHMEM4G
1367 depends on X86_32
1368
1369config NOHIGHMEM
1370 bool "off"
1371 help
1372 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1373 However, the address space of 32-bit x86 processors is only 4
1374 Gigabytes large. That means that, if you have a large amount of
1375 physical memory, not all of it can be "permanently mapped" by the
1376 kernel. The physical memory that's not permanently mapped is called
1377 "high memory".
1378
1379 If you are compiling a kernel which will never run on a machine with
1380 more than 1 Gigabyte total physical RAM, answer "off" here (default
1381 choice and suitable for most users). This will result in a "3GB/1GB"
1382 split: 3GB are mapped so that each process sees a 3GB virtual memory
1383 space and the remaining part of the 4GB virtual memory space is used
1384 by the kernel to permanently map as much physical memory as
1385 possible.
1386
1387 If the machine has between 1 and 4 Gigabytes physical RAM, then
1388 answer "4GB" here.
1389
1390 If more than 4 Gigabytes is used then answer "64GB" here. This
1391 selection turns Intel PAE (Physical Address Extension) mode on.
1392 PAE implements 3-level paging on IA32 processors. PAE is fully
1393 supported by Linux, PAE mode is implemented on all recent Intel
1394 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1395 then the kernel will not boot on CPUs that don't support PAE!
1396
1397 The actual amount of total physical memory will either be
1398 auto detected or can be forced by using a kernel command line option
1399 such as "mem=256M". (Try "man bootparam" or see the documentation of
1400 your boot loader (lilo or loadlin) about how to pass options to the
1401 kernel at boot time.)
1402
1403 If unsure, say "off".
1404
1405config HIGHMEM4G
1406 bool "4GB"
1407 help
1408 Select this if you have a 32-bit processor and between 1 and 4
1409 gigabytes of physical RAM.
1410
1411config HIGHMEM64G
1412 bool "64GB"
1413 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1414 select X86_PAE
1415 help
1416 Select this if you have a 32-bit processor and more than 4
1417 gigabytes of physical RAM.
1418
1419endchoice
1420
1421choice
1422 prompt "Memory split" if EXPERT
1423 default VMSPLIT_3G
1424 depends on X86_32
1425 help
1426 Select the desired split between kernel and user memory.
1427
1428 If the address range available to the kernel is less than the
1429 physical memory installed, the remaining memory will be available
1430 as "high memory". Accessing high memory is a little more costly
1431 than low memory, as it needs to be mapped into the kernel first.
1432 Note that increasing the kernel address space limits the range
1433 available to user programs, making the address space there
1434 tighter. Selecting anything other than the default 3G/1G split
1435 will also likely make your kernel incompatible with binary-only
1436 kernel modules.
1437
1438 If you are not absolutely sure what you are doing, leave this
1439 option alone!
1440
1441 config VMSPLIT_3G
1442 bool "3G/1G user/kernel split"
1443 config VMSPLIT_3G_OPT
1444 depends on !X86_PAE
1445 bool "3G/1G user/kernel split (for full 1G low memory)"
1446 config VMSPLIT_2G
1447 bool "2G/2G user/kernel split"
1448 config VMSPLIT_2G_OPT
1449 depends on !X86_PAE
1450 bool "2G/2G user/kernel split (for full 2G low memory)"
1451 config VMSPLIT_1G
1452 bool "1G/3G user/kernel split"
1453endchoice
1454
1455config PAGE_OFFSET
1456 hex
1457 default 0xB0000000 if VMSPLIT_3G_OPT
1458 default 0x80000000 if VMSPLIT_2G
1459 default 0x78000000 if VMSPLIT_2G_OPT
1460 default 0x40000000 if VMSPLIT_1G
1461 default 0xC0000000
1462 depends on X86_32
1463
1464config HIGHMEM
1465 def_bool y
1466 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1467
1468config X86_PAE
1469 bool "PAE (Physical Address Extension) Support"
1470 depends on X86_32 && !HIGHMEM4G
1471 select PHYS_ADDR_T_64BIT
1472 select SWIOTLB
1473 help
1474 PAE is required for NX support, and furthermore enables
1475 larger swapspace support for non-overcommit purposes. It
1476 has the cost of more pagetable lookup overhead, and also
1477 consumes more pagetable space per process.
1478
1479config X86_5LEVEL
1480 bool "Enable 5-level page tables support"
1481 default y
1482 select DYNAMIC_MEMORY_LAYOUT
1483 select SPARSEMEM_VMEMMAP
1484 depends on X86_64
1485 help
1486 5-level paging enables access to larger address space:
1487 upto 128 PiB of virtual address space and 4 PiB of
1488 physical address space.
1489
1490 It will be supported by future Intel CPUs.
1491
1492 A kernel with the option enabled can be booted on machines that
1493 support 4- or 5-level paging.
1494
1495 See Documentation/x86/x86_64/5level-paging.rst for more
1496 information.
1497
1498 Say N if unsure.
1499
1500config X86_DIRECT_GBPAGES
1501 def_bool y
1502 depends on X86_64
1503 help
1504 Certain kernel features effectively disable kernel
1505 linear 1 GB mappings (even if the CPU otherwise
1506 supports them), so don't confuse the user by printing
1507 that we have them enabled.
1508
1509config X86_CPA_STATISTICS
1510 bool "Enable statistic for Change Page Attribute"
1511 depends on DEBUG_FS
1512 help
1513 Expose statistics about the Change Page Attribute mechanism, which
1514 helps to determine the effectiveness of preserving large and huge
1515 page mappings when mapping protections are changed.
1516
1517config AMD_MEM_ENCRYPT
1518 bool "AMD Secure Memory Encryption (SME) support"
1519 depends on X86_64 && CPU_SUP_AMD
1520 select DMA_COHERENT_POOL
1521 select DYNAMIC_PHYSICAL_MASK
1522 select ARCH_USE_MEMREMAP_PROT
1523 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1524 help
1525 Say yes to enable support for the encryption of system memory.
1526 This requires an AMD processor that supports Secure Memory
1527 Encryption (SME).
1528
1529config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1530 bool "Activate AMD Secure Memory Encryption (SME) by default"
1531 default y
1532 depends on AMD_MEM_ENCRYPT
1533 help
1534 Say yes to have system memory encrypted by default if running on
1535 an AMD processor that supports Secure Memory Encryption (SME).
1536
1537 If set to Y, then the encryption of system memory can be
1538 deactivated with the mem_encrypt=off command line option.
1539
1540 If set to N, then the encryption of system memory can be
1541 activated with the mem_encrypt=on command line option.
1542
1543# Common NUMA Features
1544config NUMA
1545 bool "NUMA Memory Allocation and Scheduler Support"
1546 depends on SMP
1547 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1548 default y if X86_BIGSMP
1549 help
1550 Enable NUMA (Non-Uniform Memory Access) support.
1551
1552 The kernel will try to allocate memory used by a CPU on the
1553 local memory controller of the CPU and add some more
1554 NUMA awareness to the kernel.
1555
1556 For 64-bit this is recommended if the system is Intel Core i7
1557 (or later), AMD Opteron, or EM64T NUMA.
1558
1559 For 32-bit this is only needed if you boot a 32-bit
1560 kernel on a 64-bit NUMA platform.
1561
1562 Otherwise, you should say N.
1563
1564config AMD_NUMA
1565 def_bool y
1566 prompt "Old style AMD Opteron NUMA detection"
1567 depends on X86_64 && NUMA && PCI
1568 help
1569 Enable AMD NUMA node topology detection. You should say Y here if
1570 you have a multi processor AMD system. This uses an old method to
1571 read the NUMA configuration directly from the builtin Northbridge
1572 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1573 which also takes priority if both are compiled in.
1574
1575config X86_64_ACPI_NUMA
1576 def_bool y
1577 prompt "ACPI NUMA detection"
1578 depends on X86_64 && NUMA && ACPI && PCI
1579 select ACPI_NUMA
1580 help
1581 Enable ACPI SRAT based node topology detection.
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_FLATMEM_ENABLE
1603 def_bool y
1604 depends on X86_32 && !NUMA
1605
1606config ARCH_SPARSEMEM_ENABLE
1607 def_bool y
1608 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1609 select SPARSEMEM_STATIC if X86_32
1610 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1611
1612config ARCH_SPARSEMEM_DEFAULT
1613 def_bool X86_64 || (NUMA && X86_32)
1614
1615config ARCH_SELECT_MEMORY_MODEL
1616 def_bool y
1617 depends on ARCH_SPARSEMEM_ENABLE
1618
1619config ARCH_MEMORY_PROBE
1620 bool "Enable sysfs memory/probe interface"
1621 depends on X86_64 && MEMORY_HOTPLUG
1622 help
1623 This option enables a sysfs memory/probe interface for testing.
1624 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1625 If you are unsure how to answer this question, answer N.
1626
1627config ARCH_PROC_KCORE_TEXT
1628 def_bool y
1629 depends on X86_64 && PROC_KCORE
1630
1631config ILLEGAL_POINTER_VALUE
1632 hex
1633 default 0 if X86_32
1634 default 0xdead000000000000 if X86_64
1635
1636config X86_PMEM_LEGACY_DEVICE
1637 bool
1638
1639config X86_PMEM_LEGACY
1640 tristate "Support non-standard NVDIMMs and ADR protected memory"
1641 depends on PHYS_ADDR_T_64BIT
1642 depends on BLK_DEV
1643 select X86_PMEM_LEGACY_DEVICE
1644 select NUMA_KEEP_MEMINFO if NUMA
1645 select LIBNVDIMM
1646 help
1647 Treat memory marked using the non-standard e820 type of 12 as used
1648 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1649 The kernel will offer these regions to the 'pmem' driver so
1650 they can be used for persistent storage.
1651
1652 Say Y if unsure.
1653
1654config HIGHPTE
1655 bool "Allocate 3rd-level pagetables from highmem"
1656 depends on HIGHMEM
1657 help
1658 The VM uses one page table entry for each page of physical memory.
1659 For systems with a lot of RAM, this can be wasteful of precious
1660 low memory. Setting this option will put user-space page table
1661 entries in high memory.
1662
1663config X86_CHECK_BIOS_CORRUPTION
1664 bool "Check for low memory corruption"
1665 help
1666 Periodically check for memory corruption in low memory, which
1667 is suspected to be caused by BIOS. Even when enabled in the
1668 configuration, it is disabled at runtime. Enable it by
1669 setting "memory_corruption_check=1" on the kernel command
1670 line. By default it scans the low 64k of memory every 60
1671 seconds; see the memory_corruption_check_size and
1672 memory_corruption_check_period parameters in
1673 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1674
1675 When enabled with the default parameters, this option has
1676 almost no overhead, as it reserves a relatively small amount
1677 of memory and scans it infrequently. It both detects corruption
1678 and prevents it from affecting the running system.
1679
1680 It is, however, intended as a diagnostic tool; if repeatable
1681 BIOS-originated corruption always affects the same memory,
1682 you can use memmap= to prevent the kernel from using that
1683 memory.
1684
1685config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1686 bool "Set the default setting of memory_corruption_check"
1687 depends on X86_CHECK_BIOS_CORRUPTION
1688 default y
1689 help
1690 Set whether the default state of memory_corruption_check is
1691 on or off.
1692
1693config X86_RESERVE_LOW
1694 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1695 default 64
1696 range 4 640
1697 help
1698 Specify the amount of low memory to reserve for the BIOS.
1699
1700 The first page contains BIOS data structures that the kernel
1701 must not use, so that page must always be reserved.
1702
1703 By default we reserve the first 64K of physical RAM, as a
1704 number of BIOSes are known to corrupt that memory range
1705 during events such as suspend/resume or monitor cable
1706 insertion, so it must not be used by the kernel.
1707
1708 You can set this to 4 if you are absolutely sure that you
1709 trust the BIOS to get all its memory reservations and usages
1710 right. If you know your BIOS have problems beyond the
1711 default 64K area, you can set this to 640 to avoid using the
1712 entire low memory range.
1713
1714 If you have doubts about the BIOS (e.g. suspend/resume does
1715 not work or there's kernel crashes after certain hardware
1716 hotplug events) then you might want to enable
1717 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1718 typical corruption patterns.
1719
1720 Leave this to the default value of 64 if you are unsure.
1721
1722config MATH_EMULATION
1723 bool
1724 depends on MODIFY_LDT_SYSCALL
1725 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1726 help
1727 Linux can emulate a math coprocessor (used for floating point
1728 operations) if you don't have one. 486DX and Pentium processors have
1729 a math coprocessor built in, 486SX and 386 do not, unless you added
1730 a 487DX or 387, respectively. (The messages during boot time can
1731 give you some hints here ["man dmesg"].) Everyone needs either a
1732 coprocessor or this emulation.
1733
1734 If you don't have a math coprocessor, you need to say Y here; if you
1735 say Y here even though you have a coprocessor, the coprocessor will
1736 be used nevertheless. (This behavior can be changed with the kernel
1737 command line option "no387", which comes handy if your coprocessor
1738 is broken. Try "man bootparam" or see the documentation of your boot
1739 loader (lilo or loadlin) about how to pass options to the kernel at
1740 boot time.) This means that it is a good idea to say Y here if you
1741 intend to use this kernel on different machines.
1742
1743 More information about the internals of the Linux math coprocessor
1744 emulation can be found in <file:arch/x86/math-emu/README>.
1745
1746 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1747 kernel, it won't hurt.
1748
1749config MTRR
1750 def_bool y
1751 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1752 help
1753 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1754 the Memory Type Range Registers (MTRRs) may be used to control
1755 processor access to memory ranges. This is most useful if you have
1756 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1757 allows bus write transfers to be combined into a larger transfer
1758 before bursting over the PCI/AGP bus. This can increase performance
1759 of image write operations 2.5 times or more. Saying Y here creates a
1760 /proc/mtrr file which may be used to manipulate your processor's
1761 MTRRs. Typically the X server should use this.
1762
1763 This code has a reasonably generic interface so that similar
1764 control registers on other processors can be easily supported
1765 as well:
1766
1767 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1768 Registers (ARRs) which provide a similar functionality to MTRRs. For
1769 these, the ARRs are used to emulate the MTRRs.
1770 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1771 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1772 write-combining. All of these processors are supported by this code
1773 and it makes sense to say Y here if you have one of them.
1774
1775 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1776 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1777 can lead to all sorts of problems, so it's good to say Y here.
1778
1779 You can safely say Y even if your machine doesn't have MTRRs, you'll
1780 just add about 9 KB to your kernel.
1781
1782 See <file:Documentation/x86/mtrr.rst> for more information.
1783
1784config MTRR_SANITIZER
1785 def_bool y
1786 prompt "MTRR cleanup support"
1787 depends on MTRR
1788 help
1789 Convert MTRR layout from continuous to discrete, so X drivers can
1790 add writeback entries.
1791
1792 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1793 The largest mtrr entry size for a continuous block can be set with
1794 mtrr_chunk_size.
1795
1796 If unsure, say Y.
1797
1798config MTRR_SANITIZER_ENABLE_DEFAULT
1799 int "MTRR cleanup enable value (0-1)"
1800 range 0 1
1801 default "0"
1802 depends on MTRR_SANITIZER
1803 help
1804 Enable mtrr cleanup default value
1805
1806config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1807 int "MTRR cleanup spare reg num (0-7)"
1808 range 0 7
1809 default "1"
1810 depends on MTRR_SANITIZER
1811 help
1812 mtrr cleanup spare entries default, it can be changed via
1813 mtrr_spare_reg_nr=N on the kernel command line.
1814
1815config X86_PAT
1816 def_bool y
1817 prompt "x86 PAT support" if EXPERT
1818 depends on MTRR
1819 help
1820 Use PAT attributes to setup page level cache control.
1821
1822 PATs are the modern equivalents of MTRRs and are much more
1823 flexible than MTRRs.
1824
1825 Say N here if you see bootup problems (boot crash, boot hang,
1826 spontaneous reboots) or a non-working video driver.
1827
1828 If unsure, say Y.
1829
1830config ARCH_USES_PG_UNCACHED
1831 def_bool y
1832 depends on X86_PAT
1833
1834config ARCH_RANDOM
1835 def_bool y
1836 prompt "x86 architectural random number generator" if EXPERT
1837 help
1838 Enable the x86 architectural RDRAND instruction
1839 (Intel Bull Mountain technology) to generate random numbers.
1840 If supported, this is a high bandwidth, cryptographically
1841 secure hardware random number generator.
1842
1843config X86_SMAP
1844 def_bool y
1845 prompt "Supervisor Mode Access Prevention" if EXPERT
1846 help
1847 Supervisor Mode Access Prevention (SMAP) is a security
1848 feature in newer Intel processors. There is a small
1849 performance cost if this enabled and turned on; there is
1850 also a small increase in the kernel size if this is enabled.
1851
1852 If unsure, say Y.
1853
1854config X86_UMIP
1855 def_bool y
1856 prompt "User Mode Instruction Prevention" if EXPERT
1857 help
1858 User Mode Instruction Prevention (UMIP) is a security feature in
1859 some x86 processors. If enabled, a general protection fault is
1860 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1861 executed in user mode. These instructions unnecessarily expose
1862 information about the hardware state.
1863
1864 The vast majority of applications do not use these instructions.
1865 For the very few that do, software emulation is provided in
1866 specific cases in protected and virtual-8086 modes. Emulated
1867 results are dummy.
1868
1869config X86_INTEL_MEMORY_PROTECTION_KEYS
1870 prompt "Memory Protection Keys"
1871 def_bool y
1872 # Note: only available in 64-bit mode
1873 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1874 select ARCH_USES_HIGH_VMA_FLAGS
1875 select ARCH_HAS_PKEYS
1876 help
1877 Memory Protection Keys provides a mechanism for enforcing
1878 page-based protections, but without requiring modification of the
1879 page tables when an application changes protection domains.
1880
1881 For details, see Documentation/core-api/protection-keys.rst
1882
1883 If unsure, say y.
1884
1885choice
1886 prompt "TSX enable mode"
1887 depends on CPU_SUP_INTEL
1888 default X86_INTEL_TSX_MODE_OFF
1889 help
1890 Intel's TSX (Transactional Synchronization Extensions) feature
1891 allows to optimize locking protocols through lock elision which
1892 can lead to a noticeable performance boost.
1893
1894 On the other hand it has been shown that TSX can be exploited
1895 to form side channel attacks (e.g. TAA) and chances are there
1896 will be more of those attacks discovered in the future.
1897
1898 Therefore TSX is not enabled by default (aka tsx=off). An admin
1899 might override this decision by tsx=on the command line parameter.
1900 Even with TSX enabled, the kernel will attempt to enable the best
1901 possible TAA mitigation setting depending on the microcode available
1902 for the particular machine.
1903
1904 This option allows to set the default tsx mode between tsx=on, =off
1905 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1906 details.
1907
1908 Say off if not sure, auto if TSX is in use but it should be used on safe
1909 platforms or on if TSX is in use and the security aspect of tsx is not
1910 relevant.
1911
1912config X86_INTEL_TSX_MODE_OFF
1913 bool "off"
1914 help
1915 TSX is disabled if possible - equals to tsx=off command line parameter.
1916
1917config X86_INTEL_TSX_MODE_ON
1918 bool "on"
1919 help
1920 TSX is always enabled on TSX capable HW - equals the tsx=on command
1921 line parameter.
1922
1923config X86_INTEL_TSX_MODE_AUTO
1924 bool "auto"
1925 help
1926 TSX is enabled on TSX capable HW that is believed to be safe against
1927 side channel attacks- equals the tsx=auto command line parameter.
1928endchoice
1929
1930config EFI
1931 bool "EFI runtime service support"
1932 depends on ACPI
1933 select UCS2_STRING
1934 select EFI_RUNTIME_WRAPPERS
1935 help
1936 This enables the kernel to use EFI runtime services that are
1937 available (such as the EFI variable services).
1938
1939 This option is only useful on systems that have EFI firmware.
1940 In addition, you should use the latest ELILO loader available
1941 at <http://elilo.sourceforge.net> in order to take advantage
1942 of EFI runtime services. However, even with this option, the
1943 resultant kernel should continue to boot on existing non-EFI
1944 platforms.
1945
1946config EFI_STUB
1947 bool "EFI stub support"
1948 depends on EFI && !X86_USE_3DNOW
1949 depends on $(cc-option,-mabi=ms) || X86_32
1950 select RELOCATABLE
1951 help
1952 This kernel feature allows a bzImage to be loaded directly
1953 by EFI firmware without the use of a bootloader.
1954
1955 See Documentation/admin-guide/efi-stub.rst for more information.
1956
1957config EFI_MIXED
1958 bool "EFI mixed-mode support"
1959 depends on EFI_STUB && X86_64
1960 help
1961 Enabling this feature allows a 64-bit kernel to be booted
1962 on a 32-bit firmware, provided that your CPU supports 64-bit
1963 mode.
1964
1965 Note that it is not possible to boot a mixed-mode enabled
1966 kernel via the EFI boot stub - a bootloader that supports
1967 the EFI handover protocol must be used.
1968
1969 If unsure, say N.
1970
1971config SECCOMP
1972 def_bool y
1973 prompt "Enable seccomp to safely compute untrusted bytecode"
1974 help
1975 This kernel feature is useful for number crunching applications
1976 that may need to compute untrusted bytecode during their
1977 execution. By using pipes or other transports made available to
1978 the process as file descriptors supporting the read/write
1979 syscalls, it's possible to isolate those applications in
1980 their own address space using seccomp. Once seccomp is
1981 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1982 and the task is only allowed to execute a few safe syscalls
1983 defined by each seccomp mode.
1984
1985 If unsure, say Y. Only embedded should say N here.
1986
1987source "kernel/Kconfig.hz"
1988
1989config KEXEC
1990 bool "kexec system call"
1991 select KEXEC_CORE
1992 help
1993 kexec is a system call that implements the ability to shutdown your
1994 current kernel, and to start another kernel. It is like a reboot
1995 but it is independent of the system firmware. And like a reboot
1996 you can start any kernel with it, not just Linux.
1997
1998 The name comes from the similarity to the exec system call.
1999
2000 It is an ongoing process to be certain the hardware in a machine
2001 is properly shutdown, so do not be surprised if this code does not
2002 initially work for you. As of this writing the exact hardware
2003 interface is strongly in flux, so no good recommendation can be
2004 made.
2005
2006config KEXEC_FILE
2007 bool "kexec file based system call"
2008 select KEXEC_CORE
2009 select BUILD_BIN2C
2010 depends on X86_64
2011 depends on CRYPTO=y
2012 depends on CRYPTO_SHA256=y
2013 help
2014 This is new version of kexec system call. This system call is
2015 file based and takes file descriptors as system call argument
2016 for kernel and initramfs as opposed to list of segments as
2017 accepted by previous system call.
2018
2019config ARCH_HAS_KEXEC_PURGATORY
2020 def_bool KEXEC_FILE
2021
2022config KEXEC_SIG
2023 bool "Verify kernel signature during kexec_file_load() syscall"
2024 depends on KEXEC_FILE
2025 help
2026
2027 This option makes the kexec_file_load() syscall check for a valid
2028 signature of the kernel image. The image can still be loaded without
2029 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2030 there's a signature that we can check, then it must be valid.
2031
2032 In addition to this option, you need to enable signature
2033 verification for the corresponding kernel image type being
2034 loaded in order for this to work.
2035
2036config KEXEC_SIG_FORCE
2037 bool "Require a valid signature in kexec_file_load() syscall"
2038 depends on KEXEC_SIG
2039 help
2040 This option makes kernel signature verification mandatory for
2041 the kexec_file_load() syscall.
2042
2043config KEXEC_BZIMAGE_VERIFY_SIG
2044 bool "Enable bzImage signature verification support"
2045 depends on KEXEC_SIG
2046 depends on SIGNED_PE_FILE_VERIFICATION
2047 select SYSTEM_TRUSTED_KEYRING
2048 help
2049 Enable bzImage signature verification support.
2050
2051config CRASH_DUMP
2052 bool "kernel crash dumps"
2053 depends on X86_64 || (X86_32 && HIGHMEM)
2054 help
2055 Generate crash dump after being started by kexec.
2056 This should be normally only set in special crash dump kernels
2057 which are loaded in the main kernel with kexec-tools into
2058 a specially reserved region and then later executed after
2059 a crash by kdump/kexec. The crash dump kernel must be compiled
2060 to a memory address not used by the main kernel or BIOS using
2061 PHYSICAL_START, or it must be built as a relocatable image
2062 (CONFIG_RELOCATABLE=y).
2063 For more details see Documentation/admin-guide/kdump/kdump.rst
2064
2065config KEXEC_JUMP
2066 bool "kexec jump"
2067 depends on KEXEC && HIBERNATION
2068 help
2069 Jump between original kernel and kexeced kernel and invoke
2070 code in physical address mode via KEXEC
2071
2072config PHYSICAL_START
2073 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2074 default "0x1000000"
2075 help
2076 This gives the physical address where the kernel is loaded.
2077
2078 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2079 bzImage will decompress itself to above physical address and
2080 run from there. Otherwise, bzImage will run from the address where
2081 it has been loaded by the boot loader and will ignore above physical
2082 address.
2083
2084 In normal kdump cases one does not have to set/change this option
2085 as now bzImage can be compiled as a completely relocatable image
2086 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2087 address. This option is mainly useful for the folks who don't want
2088 to use a bzImage for capturing the crash dump and want to use a
2089 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2090 to be specifically compiled to run from a specific memory area
2091 (normally a reserved region) and this option comes handy.
2092
2093 So if you are using bzImage for capturing the crash dump,
2094 leave the value here unchanged to 0x1000000 and set
2095 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2096 for capturing the crash dump change this value to start of
2097 the reserved region. In other words, it can be set based on
2098 the "X" value as specified in the "crashkernel=YM@XM"
2099 command line boot parameter passed to the panic-ed
2100 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2101 for more details about crash dumps.
2102
2103 Usage of bzImage for capturing the crash dump is recommended as
2104 one does not have to build two kernels. Same kernel can be used
2105 as production kernel and capture kernel. Above option should have
2106 gone away after relocatable bzImage support is introduced. But it
2107 is present because there are users out there who continue to use
2108 vmlinux for dump capture. This option should go away down the
2109 line.
2110
2111 Don't change this unless you know what you are doing.
2112
2113config RELOCATABLE
2114 bool "Build a relocatable kernel"
2115 default y
2116 help
2117 This builds a kernel image that retains relocation information
2118 so it can be loaded someplace besides the default 1MB.
2119 The relocations tend to make the kernel binary about 10% larger,
2120 but are discarded at runtime.
2121
2122 One use is for the kexec on panic case where the recovery kernel
2123 must live at a different physical address than the primary
2124 kernel.
2125
2126 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2127 it has been loaded at and the compile time physical address
2128 (CONFIG_PHYSICAL_START) is used as the minimum location.
2129
2130config RANDOMIZE_BASE
2131 bool "Randomize the address of the kernel image (KASLR)"
2132 depends on RELOCATABLE
2133 default y
2134 help
2135 In support of Kernel Address Space Layout Randomization (KASLR),
2136 this randomizes the physical address at which the kernel image
2137 is decompressed and the virtual address where the kernel
2138 image is mapped, as a security feature that deters exploit
2139 attempts relying on knowledge of the location of kernel
2140 code internals.
2141
2142 On 64-bit, the kernel physical and virtual addresses are
2143 randomized separately. The physical address will be anywhere
2144 between 16MB and the top of physical memory (up to 64TB). The
2145 virtual address will be randomized from 16MB up to 1GB (9 bits
2146 of entropy). Note that this also reduces the memory space
2147 available to kernel modules from 1.5GB to 1GB.
2148
2149 On 32-bit, the kernel physical and virtual addresses are
2150 randomized together. They will be randomized from 16MB up to
2151 512MB (8 bits of entropy).
2152
2153 Entropy is generated using the RDRAND instruction if it is
2154 supported. If RDTSC is supported, its value is mixed into
2155 the entropy pool as well. If neither RDRAND nor RDTSC are
2156 supported, then entropy is read from the i8254 timer. The
2157 usable entropy is limited by the kernel being built using
2158 2GB addressing, and that PHYSICAL_ALIGN must be at a
2159 minimum of 2MB. As a result, only 10 bits of entropy are
2160 theoretically possible, but the implementations are further
2161 limited due to memory layouts.
2162
2163 If unsure, say Y.
2164
2165# Relocation on x86 needs some additional build support
2166config X86_NEED_RELOCS
2167 def_bool y
2168 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2169
2170config PHYSICAL_ALIGN
2171 hex "Alignment value to which kernel should be aligned"
2172 default "0x200000"
2173 range 0x2000 0x1000000 if X86_32
2174 range 0x200000 0x1000000 if X86_64
2175 help
2176 This value puts the alignment restrictions on physical address
2177 where kernel is loaded and run from. Kernel is compiled for an
2178 address which meets above alignment restriction.
2179
2180 If bootloader loads the kernel at a non-aligned address and
2181 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2182 address aligned to above value and run from there.
2183
2184 If bootloader loads the kernel at a non-aligned address and
2185 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2186 load address and decompress itself to the address it has been
2187 compiled for and run from there. The address for which kernel is
2188 compiled already meets above alignment restrictions. Hence the
2189 end result is that kernel runs from a physical address meeting
2190 above alignment restrictions.
2191
2192 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2193 this value must be a multiple of 0x200000.
2194
2195 Don't change this unless you know what you are doing.
2196
2197config DYNAMIC_MEMORY_LAYOUT
2198 bool
2199 help
2200 This option makes base addresses of vmalloc and vmemmap as well as
2201 __PAGE_OFFSET movable during boot.
2202
2203config RANDOMIZE_MEMORY
2204 bool "Randomize the kernel memory sections"
2205 depends on X86_64
2206 depends on RANDOMIZE_BASE
2207 select DYNAMIC_MEMORY_LAYOUT
2208 default RANDOMIZE_BASE
2209 help
2210 Randomizes the base virtual address of kernel memory sections
2211 (physical memory mapping, vmalloc & vmemmap). This security feature
2212 makes exploits relying on predictable memory locations less reliable.
2213
2214 The order of allocations remains unchanged. Entropy is generated in
2215 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2216 configuration have in average 30,000 different possible virtual
2217 addresses for each memory section.
2218
2219 If unsure, say Y.
2220
2221config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2222 hex "Physical memory mapping padding" if EXPERT
2223 depends on RANDOMIZE_MEMORY
2224 default "0xa" if MEMORY_HOTPLUG
2225 default "0x0"
2226 range 0x1 0x40 if MEMORY_HOTPLUG
2227 range 0x0 0x40
2228 help
2229 Define the padding in terabytes added to the existing physical
2230 memory size during kernel memory randomization. It is useful
2231 for memory hotplug support but reduces the entropy available for
2232 address randomization.
2233
2234 If unsure, leave at the default value.
2235
2236config HOTPLUG_CPU
2237 def_bool y
2238 depends on SMP
2239
2240config BOOTPARAM_HOTPLUG_CPU0
2241 bool "Set default setting of cpu0_hotpluggable"
2242 depends on HOTPLUG_CPU
2243 help
2244 Set whether default state of cpu0_hotpluggable is on or off.
2245
2246 Say Y here to enable CPU0 hotplug by default. If this switch
2247 is turned on, there is no need to give cpu0_hotplug kernel
2248 parameter and the CPU0 hotplug feature is enabled by default.
2249
2250 Please note: there are two known CPU0 dependencies if you want
2251 to enable the CPU0 hotplug feature either by this switch or by
2252 cpu0_hotplug kernel parameter.
2253
2254 First, resume from hibernate or suspend always starts from CPU0.
2255 So hibernate and suspend are prevented if CPU0 is offline.
2256
2257 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2258 offline if any interrupt can not migrate out of CPU0. There may
2259 be other CPU0 dependencies.
2260
2261 Please make sure the dependencies are under your control before
2262 you enable this feature.
2263
2264 Say N if you don't want to enable CPU0 hotplug feature by default.
2265 You still can enable the CPU0 hotplug feature at boot by kernel
2266 parameter cpu0_hotplug.
2267
2268config DEBUG_HOTPLUG_CPU0
2269 def_bool n
2270 prompt "Debug CPU0 hotplug"
2271 depends on HOTPLUG_CPU
2272 help
2273 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2274 soon as possible and boots up userspace with CPU0 offlined. User
2275 can online CPU0 back after boot time.
2276
2277 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2278 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2279 compilation or giving cpu0_hotplug kernel parameter at boot.
2280
2281 If unsure, say N.
2282
2283config COMPAT_VDSO
2284 def_bool n
2285 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2286 depends on COMPAT_32
2287 help
2288 Certain buggy versions of glibc will crash if they are
2289 presented with a 32-bit vDSO that is not mapped at the address
2290 indicated in its segment table.
2291
2292 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2293 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2294 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2295 the only released version with the bug, but OpenSUSE 9
2296 contains a buggy "glibc 2.3.2".
2297
2298 The symptom of the bug is that everything crashes on startup, saying:
2299 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2300
2301 Saying Y here changes the default value of the vdso32 boot
2302 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2303 This works around the glibc bug but hurts performance.
2304
2305 If unsure, say N: if you are compiling your own kernel, you
2306 are unlikely to be using a buggy version of glibc.
2307
2308choice
2309 prompt "vsyscall table for legacy applications"
2310 depends on X86_64
2311 default LEGACY_VSYSCALL_XONLY
2312 help
2313 Legacy user code that does not know how to find the vDSO expects
2314 to be able to issue three syscalls by calling fixed addresses in
2315 kernel space. Since this location is not randomized with ASLR,
2316 it can be used to assist security vulnerability exploitation.
2317
2318 This setting can be changed at boot time via the kernel command
2319 line parameter vsyscall=[emulate|xonly|none].
2320
2321 On a system with recent enough glibc (2.14 or newer) and no
2322 static binaries, you can say None without a performance penalty
2323 to improve security.
2324
2325 If unsure, select "Emulate execution only".
2326
2327 config LEGACY_VSYSCALL_EMULATE
2328 bool "Full emulation"
2329 help
2330 The kernel traps and emulates calls into the fixed vsyscall
2331 address mapping. This makes the mapping non-executable, but
2332 it still contains readable known contents, which could be
2333 used in certain rare security vulnerability exploits. This
2334 configuration is recommended when using legacy userspace
2335 that still uses vsyscalls along with legacy binary
2336 instrumentation tools that require code to be readable.
2337
2338 An example of this type of legacy userspace is running
2339 Pin on an old binary that still uses vsyscalls.
2340
2341 config LEGACY_VSYSCALL_XONLY
2342 bool "Emulate execution only"
2343 help
2344 The kernel traps and emulates calls into the fixed vsyscall
2345 address mapping and does not allow reads. This
2346 configuration is recommended when userspace might use the
2347 legacy vsyscall area but support for legacy binary
2348 instrumentation of legacy code is not needed. It mitigates
2349 certain uses of the vsyscall area as an ASLR-bypassing
2350 buffer.
2351
2352 config LEGACY_VSYSCALL_NONE
2353 bool "None"
2354 help
2355 There will be no vsyscall mapping at all. This will
2356 eliminate any risk of ASLR bypass due to the vsyscall
2357 fixed address mapping. Attempts to use the vsyscalls
2358 will be reported to dmesg, so that either old or
2359 malicious userspace programs can be identified.
2360
2361endchoice
2362
2363config CMDLINE_BOOL
2364 bool "Built-in kernel command line"
2365 help
2366 Allow for specifying boot arguments to the kernel at
2367 build time. On some systems (e.g. embedded ones), it is
2368 necessary or convenient to provide some or all of the
2369 kernel boot arguments with the kernel itself (that is,
2370 to not rely on the boot loader to provide them.)
2371
2372 To compile command line arguments into the kernel,
2373 set this option to 'Y', then fill in the
2374 boot arguments in CONFIG_CMDLINE.
2375
2376 Systems with fully functional boot loaders (i.e. non-embedded)
2377 should leave this option set to 'N'.
2378
2379config CMDLINE
2380 string "Built-in kernel command string"
2381 depends on CMDLINE_BOOL
2382 default ""
2383 help
2384 Enter arguments here that should be compiled into the kernel
2385 image and used at boot time. If the boot loader provides a
2386 command line at boot time, it is appended to this string to
2387 form the full kernel command line, when the system boots.
2388
2389 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2390 change this behavior.
2391
2392 In most cases, the command line (whether built-in or provided
2393 by the boot loader) should specify the device for the root
2394 file system.
2395
2396config CMDLINE_OVERRIDE
2397 bool "Built-in command line overrides boot loader arguments"
2398 depends on CMDLINE_BOOL && CMDLINE != ""
2399 help
2400 Set this option to 'Y' to have the kernel ignore the boot loader
2401 command line, and use ONLY the built-in command line.
2402
2403 This is used to work around broken boot loaders. This should
2404 be set to 'N' under normal conditions.
2405
2406config MODIFY_LDT_SYSCALL
2407 bool "Enable the LDT (local descriptor table)" if EXPERT
2408 default y
2409 help
2410 Linux can allow user programs to install a per-process x86
2411 Local Descriptor Table (LDT) using the modify_ldt(2) system
2412 call. This is required to run 16-bit or segmented code such as
2413 DOSEMU or some Wine programs. It is also used by some very old
2414 threading libraries.
2415
2416 Enabling this feature adds a small amount of overhead to
2417 context switches and increases the low-level kernel attack
2418 surface. Disabling it removes the modify_ldt(2) system call.
2419
2420 Saying 'N' here may make sense for embedded or server kernels.
2421
2422source "kernel/livepatch/Kconfig"
2423
2424endmenu
2425
2426config ARCH_HAS_ADD_PAGES
2427 def_bool y
2428 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2429
2430config ARCH_ENABLE_MEMORY_HOTPLUG
2431 def_bool y
2432 depends on X86_64 || (X86_32 && HIGHMEM)
2433
2434config ARCH_ENABLE_MEMORY_HOTREMOVE
2435 def_bool y
2436 depends on MEMORY_HOTPLUG
2437
2438config USE_PERCPU_NUMA_NODE_ID
2439 def_bool y
2440 depends on NUMA
2441
2442config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2443 def_bool y
2444 depends on X86_64 || X86_PAE
2445
2446config ARCH_ENABLE_HUGEPAGE_MIGRATION
2447 def_bool y
2448 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2449
2450config ARCH_ENABLE_THP_MIGRATION
2451 def_bool y
2452 depends on X86_64 && TRANSPARENT_HUGEPAGE
2453
2454menu "Power management and ACPI options"
2455
2456config ARCH_HIBERNATION_HEADER
2457 def_bool y
2458 depends on HIBERNATION
2459
2460source "kernel/power/Kconfig"
2461
2462source "drivers/acpi/Kconfig"
2463
2464source "drivers/sfi/Kconfig"
2465
2466config X86_APM_BOOT
2467 def_bool y
2468 depends on APM
2469
2470menuconfig APM
2471 tristate "APM (Advanced Power Management) BIOS support"
2472 depends on X86_32 && PM_SLEEP
2473 help
2474 APM is a BIOS specification for saving power using several different
2475 techniques. This is mostly useful for battery powered laptops with
2476 APM compliant BIOSes. If you say Y here, the system time will be
2477 reset after a RESUME operation, the /proc/apm device will provide
2478 battery status information, and user-space programs will receive
2479 notification of APM "events" (e.g. battery status change).
2480
2481 If you select "Y" here, you can disable actual use of the APM
2482 BIOS by passing the "apm=off" option to the kernel at boot time.
2483
2484 Note that the APM support is almost completely disabled for
2485 machines with more than one CPU.
2486
2487 In order to use APM, you will need supporting software. For location
2488 and more information, read <file:Documentation/power/apm-acpi.rst>
2489 and the Battery Powered Linux mini-HOWTO, available from
2490 <http://www.tldp.org/docs.html#howto>.
2491
2492 This driver does not spin down disk drives (see the hdparm(8)
2493 manpage ("man 8 hdparm") for that), and it doesn't turn off
2494 VESA-compliant "green" monitors.
2495
2496 This driver does not support the TI 4000M TravelMate and the ACER
2497 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2498 desktop machines also don't have compliant BIOSes, and this driver
2499 may cause those machines to panic during the boot phase.
2500
2501 Generally, if you don't have a battery in your machine, there isn't
2502 much point in using this driver and you should say N. If you get
2503 random kernel OOPSes or reboots that don't seem to be related to
2504 anything, try disabling/enabling this option (or disabling/enabling
2505 APM in your BIOS).
2506
2507 Some other things you should try when experiencing seemingly random,
2508 "weird" problems:
2509
2510 1) make sure that you have enough swap space and that it is
2511 enabled.
2512 2) pass the "no-hlt" option to the kernel
2513 3) switch on floating point emulation in the kernel and pass
2514 the "no387" option to the kernel
2515 4) pass the "floppy=nodma" option to the kernel
2516 5) pass the "mem=4M" option to the kernel (thereby disabling
2517 all but the first 4 MB of RAM)
2518 6) make sure that the CPU is not over clocked.
2519 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2520 8) disable the cache from your BIOS settings
2521 9) install a fan for the video card or exchange video RAM
2522 10) install a better fan for the CPU
2523 11) exchange RAM chips
2524 12) exchange the motherboard.
2525
2526 To compile this driver as a module, choose M here: the
2527 module will be called apm.
2528
2529if APM
2530
2531config APM_IGNORE_USER_SUSPEND
2532 bool "Ignore USER SUSPEND"
2533 help
2534 This option will ignore USER SUSPEND requests. On machines with a
2535 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2536 series notebooks, it is necessary to say Y because of a BIOS bug.
2537
2538config APM_DO_ENABLE
2539 bool "Enable PM at boot time"
2540 help
2541 Enable APM features at boot time. From page 36 of the APM BIOS
2542 specification: "When disabled, the APM BIOS does not automatically
2543 power manage devices, enter the Standby State, enter the Suspend
2544 State, or take power saving steps in response to CPU Idle calls."
2545 This driver will make CPU Idle calls when Linux is idle (unless this
2546 feature is turned off -- see "Do CPU IDLE calls", below). This
2547 should always save battery power, but more complicated APM features
2548 will be dependent on your BIOS implementation. You may need to turn
2549 this option off if your computer hangs at boot time when using APM
2550 support, or if it beeps continuously instead of suspending. Turn
2551 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2552 T400CDT. This is off by default since most machines do fine without
2553 this feature.
2554
2555config APM_CPU_IDLE
2556 depends on CPU_IDLE
2557 bool "Make CPU Idle calls when idle"
2558 help
2559 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2560 On some machines, this can activate improved power savings, such as
2561 a slowed CPU clock rate, when the machine is idle. These idle calls
2562 are made after the idle loop has run for some length of time (e.g.,
2563 333 mS). On some machines, this will cause a hang at boot time or
2564 whenever the CPU becomes idle. (On machines with more than one CPU,
2565 this option does nothing.)
2566
2567config APM_DISPLAY_BLANK
2568 bool "Enable console blanking using APM"
2569 help
2570 Enable console blanking using the APM. Some laptops can use this to
2571 turn off the LCD backlight when the screen blanker of the Linux
2572 virtual console blanks the screen. Note that this is only used by
2573 the virtual console screen blanker, and won't turn off the backlight
2574 when using the X Window system. This also doesn't have anything to
2575 do with your VESA-compliant power-saving monitor. Further, this
2576 option doesn't work for all laptops -- it might not turn off your
2577 backlight at all, or it might print a lot of errors to the console,
2578 especially if you are using gpm.
2579
2580config APM_ALLOW_INTS
2581 bool "Allow interrupts during APM BIOS calls"
2582 help
2583 Normally we disable external interrupts while we are making calls to
2584 the APM BIOS as a measure to lessen the effects of a badly behaving
2585 BIOS implementation. The BIOS should reenable interrupts if it
2586 needs to. Unfortunately, some BIOSes do not -- especially those in
2587 many of the newer IBM Thinkpads. If you experience hangs when you
2588 suspend, try setting this to Y. Otherwise, say N.
2589
2590endif # APM
2591
2592source "drivers/cpufreq/Kconfig"
2593
2594source "drivers/cpuidle/Kconfig"
2595
2596source "drivers/idle/Kconfig"
2597
2598endmenu
2599
2600
2601menu "Bus options (PCI etc.)"
2602
2603choice
2604 prompt "PCI access mode"
2605 depends on X86_32 && PCI
2606 default PCI_GOANY
2607 help
2608 On PCI systems, the BIOS can be used to detect the PCI devices and
2609 determine their configuration. However, some old PCI motherboards
2610 have BIOS bugs and may crash if this is done. Also, some embedded
2611 PCI-based systems don't have any BIOS at all. Linux can also try to
2612 detect the PCI hardware directly without using the BIOS.
2613
2614 With this option, you can specify how Linux should detect the
2615 PCI devices. If you choose "BIOS", the BIOS will be used,
2616 if you choose "Direct", the BIOS won't be used, and if you
2617 choose "MMConfig", then PCI Express MMCONFIG will be used.
2618 If you choose "Any", the kernel will try MMCONFIG, then the
2619 direct access method and falls back to the BIOS if that doesn't
2620 work. If unsure, go with the default, which is "Any".
2621
2622config PCI_GOBIOS
2623 bool "BIOS"
2624
2625config PCI_GOMMCONFIG
2626 bool "MMConfig"
2627
2628config PCI_GODIRECT
2629 bool "Direct"
2630
2631config PCI_GOOLPC
2632 bool "OLPC XO-1"
2633 depends on OLPC
2634
2635config PCI_GOANY
2636 bool "Any"
2637
2638endchoice
2639
2640config PCI_BIOS
2641 def_bool y
2642 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2643
2644# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2645config PCI_DIRECT
2646 def_bool y
2647 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2648
2649config PCI_MMCONFIG
2650 bool "Support mmconfig PCI config space access" if X86_64
2651 default y
2652 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2653 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2654
2655config PCI_OLPC
2656 def_bool y
2657 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2658
2659config PCI_XEN
2660 def_bool y
2661 depends on PCI && XEN
2662 select SWIOTLB_XEN
2663
2664config MMCONF_FAM10H
2665 def_bool y
2666 depends on X86_64 && PCI_MMCONFIG && ACPI
2667
2668config PCI_CNB20LE_QUIRK
2669 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2670 depends on PCI
2671 help
2672 Read the PCI windows out of the CNB20LE host bridge. This allows
2673 PCI hotplug to work on systems with the CNB20LE chipset which do
2674 not have ACPI.
2675
2676 There's no public spec for this chipset, and this functionality
2677 is known to be incomplete.
2678
2679 You should say N unless you know you need this.
2680
2681config ISA_BUS
2682 bool "ISA bus support on modern systems" if EXPERT
2683 help
2684 Expose ISA bus device drivers and options available for selection and
2685 configuration. Enable this option if your target machine has an ISA
2686 bus. ISA is an older system, displaced by PCI and newer bus
2687 architectures -- if your target machine is modern, it probably does
2688 not have an ISA bus.
2689
2690 If unsure, say N.
2691
2692# x86_64 have no ISA slots, but can have ISA-style DMA.
2693config ISA_DMA_API
2694 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2695 default y
2696 help
2697 Enables ISA-style DMA support for devices requiring such controllers.
2698 If unsure, say Y.
2699
2700if X86_32
2701
2702config ISA
2703 bool "ISA support"
2704 help
2705 Find out whether you have ISA slots on your motherboard. ISA is the
2706 name of a bus system, i.e. the way the CPU talks to the other stuff
2707 inside your box. Other bus systems are PCI, EISA, MicroChannel
2708 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2709 newer boards don't support it. If you have ISA, say Y, otherwise N.
2710
2711config SCx200
2712 tristate "NatSemi SCx200 support"
2713 help
2714 This provides basic support for National Semiconductor's
2715 (now AMD's) Geode processors. The driver probes for the
2716 PCI-IDs of several on-chip devices, so its a good dependency
2717 for other scx200_* drivers.
2718
2719 If compiled as a module, the driver is named scx200.
2720
2721config SCx200HR_TIMER
2722 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2723 depends on SCx200
2724 default y
2725 help
2726 This driver provides a clocksource built upon the on-chip
2727 27MHz high-resolution timer. Its also a workaround for
2728 NSC Geode SC-1100's buggy TSC, which loses time when the
2729 processor goes idle (as is done by the scheduler). The
2730 other workaround is idle=poll boot option.
2731
2732config OLPC
2733 bool "One Laptop Per Child support"
2734 depends on !X86_PAE
2735 select GPIOLIB
2736 select OF
2737 select OF_PROMTREE
2738 select IRQ_DOMAIN
2739 select OLPC_EC
2740 help
2741 Add support for detecting the unique features of the OLPC
2742 XO hardware.
2743
2744config OLPC_XO1_PM
2745 bool "OLPC XO-1 Power Management"
2746 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2747 help
2748 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2749
2750config OLPC_XO1_RTC
2751 bool "OLPC XO-1 Real Time Clock"
2752 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2753 help
2754 Add support for the XO-1 real time clock, which can be used as a
2755 programmable wakeup source.
2756
2757config OLPC_XO1_SCI
2758 bool "OLPC XO-1 SCI extras"
2759 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2760 depends on INPUT=y
2761 select POWER_SUPPLY
2762 help
2763 Add support for SCI-based features of the OLPC XO-1 laptop:
2764 - EC-driven system wakeups
2765 - Power button
2766 - Ebook switch
2767 - Lid switch
2768 - AC adapter status updates
2769 - Battery status updates
2770
2771config OLPC_XO15_SCI
2772 bool "OLPC XO-1.5 SCI extras"
2773 depends on OLPC && ACPI
2774 select POWER_SUPPLY
2775 help
2776 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2777 - EC-driven system wakeups
2778 - AC adapter status updates
2779 - Battery status updates
2780
2781config ALIX
2782 bool "PCEngines ALIX System Support (LED setup)"
2783 select GPIOLIB
2784 help
2785 This option enables system support for the PCEngines ALIX.
2786 At present this just sets up LEDs for GPIO control on
2787 ALIX2/3/6 boards. However, other system specific setup should
2788 get added here.
2789
2790 Note: You must still enable the drivers for GPIO and LED support
2791 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2792
2793 Note: You have to set alix.force=1 for boards with Award BIOS.
2794
2795config NET5501
2796 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2797 select GPIOLIB
2798 help
2799 This option enables system support for the Soekris Engineering net5501.
2800
2801config GEOS
2802 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2803 select GPIOLIB
2804 depends on DMI
2805 help
2806 This option enables system support for the Traverse Technologies GEOS.
2807
2808config TS5500
2809 bool "Technologic Systems TS-5500 platform support"
2810 depends on MELAN
2811 select CHECK_SIGNATURE
2812 select NEW_LEDS
2813 select LEDS_CLASS
2814 help
2815 This option enables system support for the Technologic Systems TS-5500.
2816
2817endif # X86_32
2818
2819config AMD_NB
2820 def_bool y
2821 depends on CPU_SUP_AMD && PCI
2822
2823config X86_SYSFB
2824 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2825 help
2826 Firmwares often provide initial graphics framebuffers so the BIOS,
2827 bootloader or kernel can show basic video-output during boot for
2828 user-guidance and debugging. Historically, x86 used the VESA BIOS
2829 Extensions and EFI-framebuffers for this, which are mostly limited
2830 to x86.
2831 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2832 framebuffers so the new generic system-framebuffer drivers can be
2833 used on x86. If the framebuffer is not compatible with the generic
2834 modes, it is advertised as fallback platform framebuffer so legacy
2835 drivers like efifb, vesafb and uvesafb can pick it up.
2836 If this option is not selected, all system framebuffers are always
2837 marked as fallback platform framebuffers as usual.
2838
2839 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2840 not be able to pick up generic system framebuffers if this option
2841 is selected. You are highly encouraged to enable simplefb as
2842 replacement if you select this option. simplefb can correctly deal
2843 with generic system framebuffers. But you should still keep vesafb
2844 and others enabled as fallback if a system framebuffer is
2845 incompatible with simplefb.
2846
2847 If unsure, say Y.
2848
2849endmenu
2850
2851
2852menu "Binary Emulations"
2853
2854config IA32_EMULATION
2855 bool "IA32 Emulation"
2856 depends on X86_64
2857 select ARCH_WANT_OLD_COMPAT_IPC
2858 select BINFMT_ELF
2859 select COMPAT_BINFMT_ELF
2860 select COMPAT_OLD_SIGACTION
2861 help
2862 Include code to run legacy 32-bit programs under a
2863 64-bit kernel. You should likely turn this on, unless you're
2864 100% sure that you don't have any 32-bit programs left.
2865
2866config IA32_AOUT
2867 tristate "IA32 a.out support"
2868 depends on IA32_EMULATION
2869 depends on BROKEN
2870 help
2871 Support old a.out binaries in the 32bit emulation.
2872
2873config X86_X32
2874 bool "x32 ABI for 64-bit mode"
2875 depends on X86_64
2876 help
2877 Include code to run binaries for the x32 native 32-bit ABI
2878 for 64-bit processors. An x32 process gets access to the
2879 full 64-bit register file and wide data path while leaving
2880 pointers at 32 bits for smaller memory footprint.
2881
2882 You will need a recent binutils (2.22 or later) with
2883 elf32_x86_64 support enabled to compile a kernel with this
2884 option set.
2885
2886config COMPAT_32
2887 def_bool y
2888 depends on IA32_EMULATION || X86_32
2889 select HAVE_UID16
2890 select OLD_SIGSUSPEND3
2891
2892config COMPAT
2893 def_bool y
2894 depends on IA32_EMULATION || X86_X32
2895
2896if COMPAT
2897config COMPAT_FOR_U64_ALIGNMENT
2898 def_bool y
2899
2900config SYSVIPC_COMPAT
2901 def_bool y
2902 depends on SYSVIPC
2903endif
2904
2905endmenu
2906
2907
2908config HAVE_ATOMIC_IOMAP
2909 def_bool y
2910 depends on X86_32
2911
2912source "drivers/firmware/Kconfig"
2913
2914source "arch/x86/kvm/Kconfig"
2915
2916source "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 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_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
34 select SWIOTLB
35 select ARCH_HAS_ELFCORE_COMPAT
36 select ZONE_DMA32
37
38config FORCE_DYNAMIC_FTRACE
39 def_bool y
40 depends on X86_32
41 depends on FUNCTION_TRACER
42 select DYNAMIC_FTRACE
43 help
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
49#
50# Arch settings
51#
52# ( Note that options that are marked 'if X86_64' could in principle be
53# ported to 32-bit as well. )
54#
55config X86
56 def_bool y
57 #
58 # Note: keep this list sorted alphabetically
59 #
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
73 select ARCH_HAS_CURRENT_STACK_POINTER
74 select ARCH_HAS_DEBUG_VIRTUAL
75 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
76 select ARCH_HAS_DEVMEM_IS_ALLOWED
77 select ARCH_HAS_EARLY_DEBUG if KGDB
78 select ARCH_HAS_ELF_RANDOMIZE
79 select ARCH_HAS_FAST_MULTIPLIER
80 select ARCH_HAS_FORTIFY_SOURCE
81 select ARCH_HAS_GCOV_PROFILE_ALL
82 select ARCH_HAS_KCOV if X86_64
83 select ARCH_HAS_MEM_ENCRYPT
84 select ARCH_HAS_MEMBARRIER_SYNC_CORE
85 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
86 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
87 select ARCH_HAS_PMEM_API if X86_64
88 select ARCH_HAS_PTE_DEVMAP if X86_64
89 select ARCH_HAS_PTE_SPECIAL
90 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
91 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
92 select ARCH_HAS_COPY_MC if X86_64
93 select ARCH_HAS_SET_MEMORY
94 select ARCH_HAS_SET_DIRECT_MAP
95 select ARCH_HAS_STRICT_KERNEL_RWX
96 select ARCH_HAS_STRICT_MODULE_RWX
97 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
98 select ARCH_HAS_SYSCALL_WRAPPER
99 select ARCH_HAS_UBSAN_SANITIZE_ALL
100 select ARCH_HAS_DEBUG_WX
101 select ARCH_HAS_ZONE_DMA_SET if EXPERT
102 select ARCH_HAVE_NMI_SAFE_CMPXCHG
103 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
104 select ARCH_MIGHT_HAVE_PC_PARPORT
105 select ARCH_MIGHT_HAVE_PC_SERIO
106 select ARCH_STACKWALK
107 select ARCH_SUPPORTS_ACPI
108 select ARCH_SUPPORTS_ATOMIC_RMW
109 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
110 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
111 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
112 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
113 select ARCH_SUPPORTS_CFI_CLANG if X86_64
114 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
115 select ARCH_SUPPORTS_LTO_CLANG
116 select ARCH_SUPPORTS_LTO_CLANG_THIN
117 select ARCH_USE_BUILTIN_BSWAP
118 select ARCH_USE_MEMTEST
119 select ARCH_USE_QUEUED_RWLOCKS
120 select ARCH_USE_QUEUED_SPINLOCKS
121 select ARCH_USE_SYM_ANNOTATIONS
122 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
123 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
124 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
125 select ARCH_WANTS_NO_INSTR
126 select ARCH_WANT_GENERAL_HUGETLB
127 select ARCH_WANT_HUGE_PMD_SHARE
128 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
129 select ARCH_WANT_LD_ORPHAN_WARN
130 select ARCH_WANTS_THP_SWAP if X86_64
131 select ARCH_HAS_PARANOID_L1D_FLUSH
132 select BUILDTIME_TABLE_SORT
133 select CLKEVT_I8253
134 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
135 select CLOCKSOURCE_WATCHDOG
136 # Word-size accesses may read uninitialized data past the trailing \0
137 # in strings and cause false KMSAN reports.
138 select DCACHE_WORD_ACCESS if !KMSAN
139 select DYNAMIC_SIGFRAME
140 select EDAC_ATOMIC_SCRUB
141 select EDAC_SUPPORT
142 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
143 select GENERIC_CLOCKEVENTS_MIN_ADJUST
144 select GENERIC_CMOS_UPDATE
145 select GENERIC_CPU_AUTOPROBE
146 select GENERIC_CPU_VULNERABILITIES
147 select GENERIC_EARLY_IOREMAP
148 select GENERIC_ENTRY
149 select GENERIC_IOMAP
150 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
151 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
152 select GENERIC_IRQ_MIGRATION if SMP
153 select GENERIC_IRQ_PROBE
154 select GENERIC_IRQ_RESERVATION_MODE
155 select GENERIC_IRQ_SHOW
156 select GENERIC_PENDING_IRQ if SMP
157 select GENERIC_PTDUMP
158 select GENERIC_SMP_IDLE_THREAD
159 select GENERIC_TIME_VSYSCALL
160 select GENERIC_GETTIMEOFDAY
161 select GENERIC_VDSO_TIME_NS
162 select GUP_GET_PXX_LOW_HIGH if X86_PAE
163 select HARDIRQS_SW_RESEND
164 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
165 select HAVE_ACPI_APEI if ACPI
166 select HAVE_ACPI_APEI_NMI if ACPI
167 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
168 select HAVE_ARCH_AUDITSYSCALL
169 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
170 select HAVE_ARCH_HUGE_VMALLOC if X86_64
171 select HAVE_ARCH_JUMP_LABEL
172 select HAVE_ARCH_JUMP_LABEL_RELATIVE
173 select HAVE_ARCH_KASAN if X86_64
174 select HAVE_ARCH_KASAN_VMALLOC if X86_64
175 select HAVE_ARCH_KFENCE
176 select HAVE_ARCH_KMSAN if X86_64
177 select HAVE_ARCH_KGDB
178 select HAVE_ARCH_MMAP_RND_BITS if MMU
179 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
180 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
181 select HAVE_ARCH_PREL32_RELOCATIONS
182 select HAVE_ARCH_SECCOMP_FILTER
183 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
184 select HAVE_ARCH_STACKLEAK
185 select HAVE_ARCH_TRACEHOOK
186 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
187 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
188 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
189 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
190 select HAVE_ARCH_VMAP_STACK if X86_64
191 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
192 select HAVE_ARCH_WITHIN_STACK_FRAMES
193 select HAVE_ASM_MODVERSIONS
194 select HAVE_CMPXCHG_DOUBLE
195 select HAVE_CMPXCHG_LOCAL
196 select HAVE_CONTEXT_TRACKING_USER if X86_64
197 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
198 select HAVE_C_RECORDMCOUNT
199 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
200 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
201 select HAVE_BUILDTIME_MCOUNT_SORT
202 select HAVE_DEBUG_KMEMLEAK
203 select HAVE_DMA_CONTIGUOUS
204 select HAVE_DYNAMIC_FTRACE
205 select HAVE_DYNAMIC_FTRACE_WITH_REGS
206 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
207 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
208 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
209 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
210 select HAVE_EBPF_JIT
211 select HAVE_EFFICIENT_UNALIGNED_ACCESS
212 select HAVE_EISA
213 select HAVE_EXIT_THREAD
214 select HAVE_FAST_GUP
215 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
216 select HAVE_FTRACE_MCOUNT_RECORD
217 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
218 select HAVE_FUNCTION_TRACER
219 select HAVE_GCC_PLUGINS
220 select HAVE_HW_BREAKPOINT
221 select HAVE_IOREMAP_PROT
222 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
223 select HAVE_IRQ_TIME_ACCOUNTING
224 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
225 select HAVE_KERNEL_BZIP2
226 select HAVE_KERNEL_GZIP
227 select HAVE_KERNEL_LZ4
228 select HAVE_KERNEL_LZMA
229 select HAVE_KERNEL_LZO
230 select HAVE_KERNEL_XZ
231 select HAVE_KERNEL_ZSTD
232 select HAVE_KPROBES
233 select HAVE_KPROBES_ON_FTRACE
234 select HAVE_FUNCTION_ERROR_INJECTION
235 select HAVE_KRETPROBES
236 select HAVE_RETHOOK
237 select HAVE_KVM
238 select HAVE_LIVEPATCH if X86_64
239 select HAVE_MIXED_BREAKPOINTS_REGS
240 select HAVE_MOD_ARCH_SPECIFIC
241 select HAVE_MOVE_PMD
242 select HAVE_MOVE_PUD
243 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
244 select HAVE_NMI
245 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
246 select HAVE_OBJTOOL if X86_64
247 select HAVE_OPTPROBES
248 select HAVE_PCSPKR_PLATFORM
249 select HAVE_PERF_EVENTS
250 select HAVE_PERF_EVENTS_NMI
251 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
252 select HAVE_PCI
253 select HAVE_PERF_REGS
254 select HAVE_PERF_USER_STACK_DUMP
255 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
256 select MMU_GATHER_MERGE_VMAS
257 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
258 select HAVE_REGS_AND_STACK_ACCESS_API
259 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
260 select HAVE_FUNCTION_ARG_ACCESS_API
261 select HAVE_SETUP_PER_CPU_AREA
262 select HAVE_SOFTIRQ_ON_OWN_STACK
263 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
264 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
265 select HAVE_STATIC_CALL
266 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
267 select HAVE_PREEMPT_DYNAMIC_CALL
268 select HAVE_RSEQ
269 select HAVE_RUST if X86_64
270 select HAVE_SYSCALL_TRACEPOINTS
271 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
272 select HAVE_UNSTABLE_SCHED_CLOCK
273 select HAVE_USER_RETURN_NOTIFIER
274 select HAVE_GENERIC_VDSO
275 select HOTPLUG_SMT if SMP
276 select IRQ_FORCED_THREADING
277 select NEED_PER_CPU_EMBED_FIRST_CHUNK
278 select NEED_PER_CPU_PAGE_FIRST_CHUNK
279 select NEED_SG_DMA_LENGTH
280 select PCI_DOMAINS if PCI
281 select PCI_LOCKLESS_CONFIG if PCI
282 select PERF_EVENTS
283 select RTC_LIB
284 select RTC_MC146818_LIB
285 select SPARSE_IRQ
286 select SRCU
287 select SYSCTL_EXCEPTION_TRACE
288 select THREAD_INFO_IN_TASK
289 select TRACE_IRQFLAGS_SUPPORT
290 select TRACE_IRQFLAGS_NMI_SUPPORT
291 select USER_STACKTRACE_SUPPORT
292 select HAVE_ARCH_KCSAN if X86_64
293 select X86_FEATURE_NAMES if PROC_FS
294 select PROC_PID_ARCH_STATUS if PROC_FS
295 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
296 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
297 select FUNCTION_ALIGNMENT_4B
298 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
299 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
300
301config INSTRUCTION_DECODER
302 def_bool y
303 depends on KPROBES || PERF_EVENTS || UPROBES
304
305config OUTPUT_FORMAT
306 string
307 default "elf32-i386" if X86_32
308 default "elf64-x86-64" if X86_64
309
310config LOCKDEP_SUPPORT
311 def_bool y
312
313config STACKTRACE_SUPPORT
314 def_bool y
315
316config MMU
317 def_bool y
318
319config ARCH_MMAP_RND_BITS_MIN
320 default 28 if 64BIT
321 default 8
322
323config ARCH_MMAP_RND_BITS_MAX
324 default 32 if 64BIT
325 default 16
326
327config ARCH_MMAP_RND_COMPAT_BITS_MIN
328 default 8
329
330config ARCH_MMAP_RND_COMPAT_BITS_MAX
331 default 16
332
333config SBUS
334 bool
335
336config GENERIC_ISA_DMA
337 def_bool y
338 depends on ISA_DMA_API
339
340config GENERIC_CSUM
341 bool
342 default y if KMSAN || KASAN
343
344config GENERIC_BUG
345 def_bool y
346 depends on BUG
347 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
348
349config GENERIC_BUG_RELATIVE_POINTERS
350 bool
351
352config ARCH_MAY_HAVE_PC_FDC
353 def_bool y
354 depends on ISA_DMA_API
355
356config GENERIC_CALIBRATE_DELAY
357 def_bool y
358
359config ARCH_HAS_CPU_RELAX
360 def_bool y
361
362config ARCH_HIBERNATION_POSSIBLE
363 def_bool y
364
365config ARCH_SUSPEND_POSSIBLE
366 def_bool y
367
368config AUDIT_ARCH
369 def_bool y if X86_64
370
371config KASAN_SHADOW_OFFSET
372 hex
373 depends on KASAN
374 default 0xdffffc0000000000
375
376config HAVE_INTEL_TXT
377 def_bool y
378 depends on INTEL_IOMMU && ACPI
379
380config X86_32_SMP
381 def_bool y
382 depends on X86_32 && SMP
383
384config X86_64_SMP
385 def_bool y
386 depends on X86_64 && SMP
387
388config ARCH_SUPPORTS_UPROBES
389 def_bool y
390
391config FIX_EARLYCON_MEM
392 def_bool y
393
394config DYNAMIC_PHYSICAL_MASK
395 bool
396
397config PGTABLE_LEVELS
398 int
399 default 5 if X86_5LEVEL
400 default 4 if X86_64
401 default 3 if X86_PAE
402 default 2
403
404config CC_HAS_SANE_STACKPROTECTOR
405 bool
406 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
407 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
408 help
409 We have to make sure stack protector is unconditionally disabled if
410 the compiler produces broken code or if it does not let us control
411 the segment on 32-bit kernels.
412
413menu "Processor type and features"
414
415config SMP
416 bool "Symmetric multi-processing support"
417 help
418 This enables support for systems with more than one CPU. If you have
419 a system with only one CPU, say N. If you have a system with more
420 than one CPU, say Y.
421
422 If you say N here, the kernel will run on uni- and multiprocessor
423 machines, but will use only one CPU of a multiprocessor machine. If
424 you say Y here, the kernel will run on many, but not all,
425 uniprocessor machines. On a uniprocessor machine, the kernel
426 will run faster if you say N here.
427
428 Note that if you say Y here and choose architecture "586" or
429 "Pentium" under "Processor family", the kernel will not work on 486
430 architectures. Similarly, multiprocessor kernels for the "PPro"
431 architecture may not work on all Pentium based boards.
432
433 People using multiprocessor machines who say Y here should also say
434 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
435 Management" code will be disabled if you say Y here.
436
437 See also <file:Documentation/x86/i386/IO-APIC.rst>,
438 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
439 <http://www.tldp.org/docs.html#howto>.
440
441 If you don't know what to do here, say N.
442
443config X86_FEATURE_NAMES
444 bool "Processor feature human-readable names" if EMBEDDED
445 default y
446 help
447 This option compiles in a table of x86 feature bits and corresponding
448 names. This is required to support /proc/cpuinfo and a few kernel
449 messages. You can disable this to save space, at the expense of
450 making those few kernel messages show numeric feature bits instead.
451
452 If in doubt, say Y.
453
454config X86_X2APIC
455 bool "Support x2apic"
456 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
457 help
458 This enables x2apic support on CPUs that have this feature.
459
460 This allows 32-bit apic IDs (so it can support very large systems),
461 and accesses the local apic via MSRs not via mmio.
462
463 Some Intel systems circa 2022 and later are locked into x2APIC mode
464 and can not fall back to the legacy APIC modes if SGX or TDX are
465 enabled in the BIOS. They will boot with very reduced functionality
466 without enabling this option.
467
468 If you don't know what to do here, say N.
469
470config X86_MPPARSE
471 bool "Enable MPS table" if ACPI
472 default y
473 depends on X86_LOCAL_APIC
474 help
475 For old smp systems that do not have proper acpi support. Newer systems
476 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
477
478config GOLDFISH
479 def_bool y
480 depends on X86_GOLDFISH
481
482config X86_CPU_RESCTRL
483 bool "x86 CPU resource control support"
484 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
485 select KERNFS
486 select PROC_CPU_RESCTRL if PROC_FS
487 help
488 Enable x86 CPU resource control support.
489
490 Provide support for the allocation and monitoring of system resources
491 usage by the CPU.
492
493 Intel calls this Intel Resource Director Technology
494 (Intel(R) RDT). More information about RDT can be found in the
495 Intel x86 Architecture Software Developer Manual.
496
497 AMD calls this AMD Platform Quality of Service (AMD QoS).
498 More information about AMD QoS can be found in the AMD64 Technology
499 Platform Quality of Service Extensions manual.
500
501 Say N if unsure.
502
503if X86_32
504config X86_BIGSMP
505 bool "Support for big SMP systems with more than 8 CPUs"
506 depends on SMP
507 help
508 This option is needed for the systems that have more than 8 CPUs.
509
510config X86_EXTENDED_PLATFORM
511 bool "Support for extended (non-PC) x86 platforms"
512 default y
513 help
514 If you disable this option then the kernel will only support
515 standard PC platforms. (which covers the vast majority of
516 systems out there.)
517
518 If you enable this option then you'll be able to select support
519 for the following (non-PC) 32 bit x86 platforms:
520 Goldfish (Android emulator)
521 AMD Elan
522 RDC R-321x SoC
523 SGI 320/540 (Visual Workstation)
524 STA2X11-based (e.g. Northville)
525 Moorestown MID devices
526
527 If you have one of these systems, or if you want to build a
528 generic distribution kernel, say Y here - otherwise say N.
529endif # X86_32
530
531if X86_64
532config X86_EXTENDED_PLATFORM
533 bool "Support for extended (non-PC) x86 platforms"
534 default y
535 help
536 If you disable this option then the kernel will only support
537 standard PC platforms. (which covers the vast majority of
538 systems out there.)
539
540 If you enable this option then you'll be able to select support
541 for the following (non-PC) 64 bit x86 platforms:
542 Numascale NumaChip
543 ScaleMP vSMP
544 SGI Ultraviolet
545
546 If you have one of these systems, or if you want to build a
547 generic distribution kernel, say Y here - otherwise say N.
548endif # X86_64
549# This is an alphabetically sorted list of 64 bit extended platforms
550# Please maintain the alphabetic order if and when there are additions
551config X86_NUMACHIP
552 bool "Numascale NumaChip"
553 depends on X86_64
554 depends on X86_EXTENDED_PLATFORM
555 depends on NUMA
556 depends on SMP
557 depends on X86_X2APIC
558 depends on PCI_MMCONFIG
559 help
560 Adds support for Numascale NumaChip large-SMP systems. Needed to
561 enable more than ~168 cores.
562 If you don't have one of these, you should say N here.
563
564config X86_VSMP
565 bool "ScaleMP vSMP"
566 select HYPERVISOR_GUEST
567 select PARAVIRT
568 depends on X86_64 && PCI
569 depends on X86_EXTENDED_PLATFORM
570 depends on SMP
571 help
572 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
573 supposed to run on these EM64T-based machines. Only choose this option
574 if you have one of these machines.
575
576config X86_UV
577 bool "SGI Ultraviolet"
578 depends on X86_64
579 depends on X86_EXTENDED_PLATFORM
580 depends on NUMA
581 depends on EFI
582 depends on KEXEC_CORE
583 depends on X86_X2APIC
584 depends on PCI
585 help
586 This option is needed in order to support SGI Ultraviolet systems.
587 If you don't have one of these, you should say N here.
588
589# Following is an alphabetically sorted list of 32 bit extended platforms
590# Please maintain the alphabetic order if and when there are additions
591
592config X86_GOLDFISH
593 bool "Goldfish (Virtual Platform)"
594 depends on X86_EXTENDED_PLATFORM
595 help
596 Enable support for the Goldfish virtual platform used primarily
597 for Android development. Unless you are building for the Android
598 Goldfish emulator say N here.
599
600config X86_INTEL_CE
601 bool "CE4100 TV platform"
602 depends on PCI
603 depends on PCI_GODIRECT
604 depends on X86_IO_APIC
605 depends on X86_32
606 depends on X86_EXTENDED_PLATFORM
607 select X86_REBOOTFIXUPS
608 select OF
609 select OF_EARLY_FLATTREE
610 help
611 Select for the Intel CE media processor (CE4100) SOC.
612 This option compiles in support for the CE4100 SOC for settop
613 boxes and media devices.
614
615config X86_INTEL_MID
616 bool "Intel MID platform support"
617 depends on X86_EXTENDED_PLATFORM
618 depends on X86_PLATFORM_DEVICES
619 depends on PCI
620 depends on X86_64 || (PCI_GOANY && X86_32)
621 depends on X86_IO_APIC
622 select I2C
623 select DW_APB_TIMER
624 select INTEL_SCU_PCI
625 help
626 Select to build a kernel capable of supporting Intel MID (Mobile
627 Internet Device) platform systems which do not have the PCI legacy
628 interfaces. If you are building for a PC class system say N here.
629
630 Intel MID platforms are based on an Intel processor and chipset which
631 consume less power than most of the x86 derivatives.
632
633config X86_INTEL_QUARK
634 bool "Intel Quark platform support"
635 depends on X86_32
636 depends on X86_EXTENDED_PLATFORM
637 depends on X86_PLATFORM_DEVICES
638 depends on X86_TSC
639 depends on PCI
640 depends on PCI_GOANY
641 depends on X86_IO_APIC
642 select IOSF_MBI
643 select INTEL_IMR
644 select COMMON_CLK
645 help
646 Select to include support for Quark X1000 SoC.
647 Say Y here if you have a Quark based system such as the Arduino
648 compatible Intel Galileo.
649
650config X86_INTEL_LPSS
651 bool "Intel Low Power Subsystem Support"
652 depends on X86 && ACPI && PCI
653 select COMMON_CLK
654 select PINCTRL
655 select IOSF_MBI
656 help
657 Select to build support for Intel Low Power Subsystem such as
658 found on Intel Lynxpoint PCH. Selecting this option enables
659 things like clock tree (common clock framework) and pincontrol
660 which are needed by the LPSS peripheral drivers.
661
662config X86_AMD_PLATFORM_DEVICE
663 bool "AMD ACPI2Platform devices support"
664 depends on ACPI
665 select COMMON_CLK
666 select PINCTRL
667 help
668 Select to interpret AMD specific ACPI device to platform device
669 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
670 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
671 implemented under PINCTRL subsystem.
672
673config IOSF_MBI
674 tristate "Intel SoC IOSF Sideband support for SoC platforms"
675 depends on PCI
676 help
677 This option enables sideband register access support for Intel SoC
678 platforms. On these platforms the IOSF sideband is used in lieu of
679 MSR's for some register accesses, mostly but not limited to thermal
680 and power. Drivers may query the availability of this device to
681 determine if they need the sideband in order to work on these
682 platforms. The sideband is available on the following SoC products.
683 This list is not meant to be exclusive.
684 - BayTrail
685 - Braswell
686 - Quark
687
688 You should say Y if you are running a kernel on one of these SoC's.
689
690config IOSF_MBI_DEBUG
691 bool "Enable IOSF sideband access through debugfs"
692 depends on IOSF_MBI && DEBUG_FS
693 help
694 Select this option to expose the IOSF sideband access registers (MCR,
695 MDR, MCRX) through debugfs to write and read register information from
696 different units on the SoC. This is most useful for obtaining device
697 state information for debug and analysis. As this is a general access
698 mechanism, users of this option would have specific knowledge of the
699 device they want to access.
700
701 If you don't require the option or are in doubt, say N.
702
703config X86_RDC321X
704 bool "RDC R-321x SoC"
705 depends on X86_32
706 depends on X86_EXTENDED_PLATFORM
707 select M486
708 select X86_REBOOTFIXUPS
709 help
710 This option is needed for RDC R-321x system-on-chip, also known
711 as R-8610-(G).
712 If you don't have one of these chips, you should say N here.
713
714config X86_32_NON_STANDARD
715 bool "Support non-standard 32-bit SMP architectures"
716 depends on X86_32 && SMP
717 depends on X86_EXTENDED_PLATFORM
718 help
719 This option compiles in the bigsmp and STA2X11 default
720 subarchitectures. It is intended for a generic binary
721 kernel. If you select them all, kernel will probe it one by
722 one and will fallback to default.
723
724# Alphabetically sorted list of Non standard 32 bit platforms
725
726config X86_SUPPORTS_MEMORY_FAILURE
727 def_bool y
728 # MCE code calls memory_failure():
729 depends on X86_MCE
730 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
731 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
732 depends on X86_64 || !SPARSEMEM
733 select ARCH_SUPPORTS_MEMORY_FAILURE
734
735config STA2X11
736 bool "STA2X11 Companion Chip Support"
737 depends on X86_32_NON_STANDARD && PCI
738 select SWIOTLB
739 select MFD_STA2X11
740 select GPIOLIB
741 help
742 This adds support for boards based on the STA2X11 IO-Hub,
743 a.k.a. "ConneXt". The chip is used in place of the standard
744 PC chipset, so all "standard" peripherals are missing. If this
745 option is selected the kernel will still be able to boot on
746 standard PC machines.
747
748config X86_32_IRIS
749 tristate "Eurobraille/Iris poweroff module"
750 depends on X86_32
751 help
752 The Iris machines from EuroBraille do not have APM or ACPI support
753 to shut themselves down properly. A special I/O sequence is
754 needed to do so, which is what this module does at
755 kernel shutdown.
756
757 This is only for Iris machines from EuroBraille.
758
759 If unused, say N.
760
761config SCHED_OMIT_FRAME_POINTER
762 def_bool y
763 prompt "Single-depth WCHAN output"
764 depends on X86
765 help
766 Calculate simpler /proc/<PID>/wchan values. If this option
767 is disabled then wchan values will recurse back to the
768 caller function. This provides more accurate wchan values,
769 at the expense of slightly more scheduling overhead.
770
771 If in doubt, say "Y".
772
773menuconfig HYPERVISOR_GUEST
774 bool "Linux guest support"
775 help
776 Say Y here to enable options for running Linux under various hyper-
777 visors. This option enables basic hypervisor detection and platform
778 setup.
779
780 If you say N, all options in this submenu will be skipped and
781 disabled, and Linux guest support won't be built in.
782
783if HYPERVISOR_GUEST
784
785config PARAVIRT
786 bool "Enable paravirtualization code"
787 depends on HAVE_STATIC_CALL
788 help
789 This changes the kernel so it can modify itself when it is run
790 under a hypervisor, potentially improving performance significantly
791 over full virtualization. However, when run without a hypervisor
792 the kernel is theoretically slower and slightly larger.
793
794config PARAVIRT_XXL
795 bool
796
797config PARAVIRT_DEBUG
798 bool "paravirt-ops debugging"
799 depends on PARAVIRT && DEBUG_KERNEL
800 help
801 Enable to debug paravirt_ops internals. Specifically, BUG if
802 a paravirt_op is missing when it is called.
803
804config PARAVIRT_SPINLOCKS
805 bool "Paravirtualization layer for spinlocks"
806 depends on PARAVIRT && SMP
807 help
808 Paravirtualized spinlocks allow a pvops backend to replace the
809 spinlock implementation with something virtualization-friendly
810 (for example, block the virtual CPU rather than spinning).
811
812 It has a minimal impact on native kernels and gives a nice performance
813 benefit on paravirtualized KVM / Xen kernels.
814
815 If you are unsure how to answer this question, answer Y.
816
817config X86_HV_CALLBACK_VECTOR
818 def_bool n
819
820source "arch/x86/xen/Kconfig"
821
822config KVM_GUEST
823 bool "KVM Guest support (including kvmclock)"
824 depends on PARAVIRT
825 select PARAVIRT_CLOCK
826 select ARCH_CPUIDLE_HALTPOLL
827 select X86_HV_CALLBACK_VECTOR
828 default y
829 help
830 This option enables various optimizations for running under the KVM
831 hypervisor. It includes a paravirtualized clock, so that instead
832 of relying on a PIT (or probably other) emulation by the
833 underlying device model, the host provides the guest with
834 timing infrastructure such as time of day, and system time
835
836config ARCH_CPUIDLE_HALTPOLL
837 def_bool n
838 prompt "Disable host haltpoll when loading haltpoll driver"
839 help
840 If virtualized under KVM, disable host haltpoll.
841
842config PVH
843 bool "Support for running PVH guests"
844 help
845 This option enables the PVH entry point for guest virtual machines
846 as specified in the x86/HVM direct boot ABI.
847
848config PARAVIRT_TIME_ACCOUNTING
849 bool "Paravirtual steal time accounting"
850 depends on PARAVIRT
851 help
852 Select this option to enable fine granularity task steal time
853 accounting. Time spent executing other tasks in parallel with
854 the current vCPU is discounted from the vCPU power. To account for
855 that, there can be a small performance impact.
856
857 If in doubt, say N here.
858
859config PARAVIRT_CLOCK
860 bool
861
862config JAILHOUSE_GUEST
863 bool "Jailhouse non-root cell support"
864 depends on X86_64 && PCI
865 select X86_PM_TIMER
866 help
867 This option allows to run Linux as guest in a Jailhouse non-root
868 cell. You can leave this option disabled if you only want to start
869 Jailhouse and run Linux afterwards in the root cell.
870
871config ACRN_GUEST
872 bool "ACRN Guest support"
873 depends on X86_64
874 select X86_HV_CALLBACK_VECTOR
875 help
876 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
877 a flexible, lightweight reference open-source hypervisor, built with
878 real-time and safety-criticality in mind. It is built for embedded
879 IOT with small footprint and real-time features. More details can be
880 found in https://projectacrn.org/.
881
882config INTEL_TDX_GUEST
883 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
884 depends on X86_64 && CPU_SUP_INTEL
885 depends on X86_X2APIC
886 select ARCH_HAS_CC_PLATFORM
887 select X86_MEM_ENCRYPT
888 select X86_MCE
889 help
890 Support running as a guest under Intel TDX. Without this support,
891 the guest kernel can not boot or run under TDX.
892 TDX includes memory encryption and integrity capabilities
893 which protect the confidentiality and integrity of guest
894 memory contents and CPU state. TDX guests are protected from
895 some attacks from the VMM.
896
897endif # HYPERVISOR_GUEST
898
899source "arch/x86/Kconfig.cpu"
900
901config HPET_TIMER
902 def_bool X86_64
903 prompt "HPET Timer Support" if X86_32
904 help
905 Use the IA-PC HPET (High Precision Event Timer) to manage
906 time in preference to the PIT and RTC, if a HPET is
907 present.
908 HPET is the next generation timer replacing legacy 8254s.
909 The HPET provides a stable time base on SMP
910 systems, unlike the TSC, but it is more expensive to access,
911 as it is off-chip. The interface used is documented
912 in the HPET spec, revision 1.
913
914 You can safely choose Y here. However, HPET will only be
915 activated if the platform and the BIOS support this feature.
916 Otherwise the 8254 will be used for timing services.
917
918 Choose N to continue using the legacy 8254 timer.
919
920config HPET_EMULATE_RTC
921 def_bool y
922 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
923
924# Mark as expert because too many people got it wrong.
925# The code disables itself when not needed.
926config DMI
927 default y
928 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
929 bool "Enable DMI scanning" if EXPERT
930 help
931 Enabled scanning of DMI to identify machine quirks. Say Y
932 here unless you have verified that your setup is not
933 affected by entries in the DMI blacklist. Required by PNP
934 BIOS code.
935
936config GART_IOMMU
937 bool "Old AMD GART IOMMU support"
938 select DMA_OPS
939 select IOMMU_HELPER
940 select SWIOTLB
941 depends on X86_64 && PCI && AMD_NB
942 help
943 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
944 GART based hardware IOMMUs.
945
946 The GART supports full DMA access for devices with 32-bit access
947 limitations, on systems with more than 3 GB. This is usually needed
948 for USB, sound, many IDE/SATA chipsets and some other devices.
949
950 Newer systems typically have a modern AMD IOMMU, supported via
951 the CONFIG_AMD_IOMMU=y config option.
952
953 In normal configurations this driver is only active when needed:
954 there's more than 3 GB of memory and the system contains a
955 32-bit limited device.
956
957 If unsure, say Y.
958
959config BOOT_VESA_SUPPORT
960 bool
961 help
962 If true, at least one selected framebuffer driver can take advantage
963 of VESA video modes set at an early boot stage via the vga= parameter.
964
965config MAXSMP
966 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
967 depends on X86_64 && SMP && DEBUG_KERNEL
968 select CPUMASK_OFFSTACK
969 help
970 Enable maximum number of CPUS and NUMA Nodes for this architecture.
971 If unsure, say N.
972
973#
974# The maximum number of CPUs supported:
975#
976# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
977# and which can be configured interactively in the
978# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
979#
980# The ranges are different on 32-bit and 64-bit kernels, depending on
981# hardware capabilities and scalability features of the kernel.
982#
983# ( If MAXSMP is enabled we just use the highest possible value and disable
984# interactive configuration. )
985#
986
987config NR_CPUS_RANGE_BEGIN
988 int
989 default NR_CPUS_RANGE_END if MAXSMP
990 default 1 if !SMP
991 default 2
992
993config NR_CPUS_RANGE_END
994 int
995 depends on X86_32
996 default 64 if SMP && X86_BIGSMP
997 default 8 if SMP && !X86_BIGSMP
998 default 1 if !SMP
999
1000config NR_CPUS_RANGE_END
1001 int
1002 depends on X86_64
1003 default 8192 if SMP && CPUMASK_OFFSTACK
1004 default 512 if SMP && !CPUMASK_OFFSTACK
1005 default 1 if !SMP
1006
1007config NR_CPUS_DEFAULT
1008 int
1009 depends on X86_32
1010 default 32 if X86_BIGSMP
1011 default 8 if SMP
1012 default 1 if !SMP
1013
1014config NR_CPUS_DEFAULT
1015 int
1016 depends on X86_64
1017 default 8192 if MAXSMP
1018 default 64 if SMP
1019 default 1 if !SMP
1020
1021config NR_CPUS
1022 int "Maximum number of CPUs" if SMP && !MAXSMP
1023 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1024 default NR_CPUS_DEFAULT
1025 help
1026 This allows you to specify the maximum number of CPUs which this
1027 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1028 supported value is 8192, otherwise the maximum value is 512. The
1029 minimum value which makes sense is 2.
1030
1031 This is purely to save memory: each supported CPU adds about 8KB
1032 to the kernel image.
1033
1034config SCHED_CLUSTER
1035 bool "Cluster scheduler support"
1036 depends on SMP
1037 default y
1038 help
1039 Cluster scheduler support improves the CPU scheduler's decision
1040 making when dealing with machines that have clusters of CPUs.
1041 Cluster usually means a couple of CPUs which are placed closely
1042 by sharing mid-level caches, last-level cache tags or internal
1043 busses.
1044
1045config SCHED_SMT
1046 def_bool y if SMP
1047
1048config SCHED_MC
1049 def_bool y
1050 prompt "Multi-core scheduler support"
1051 depends on SMP
1052 help
1053 Multi-core scheduler support improves the CPU scheduler's decision
1054 making when dealing with multi-core CPU chips at a cost of slightly
1055 increased overhead in some places. If unsure say N here.
1056
1057config SCHED_MC_PRIO
1058 bool "CPU core priorities scheduler support"
1059 depends on SCHED_MC && CPU_SUP_INTEL
1060 select X86_INTEL_PSTATE
1061 select CPU_FREQ
1062 default y
1063 help
1064 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1065 core ordering determined at manufacturing time, which allows
1066 certain cores to reach higher turbo frequencies (when running
1067 single threaded workloads) than others.
1068
1069 Enabling this kernel feature teaches the scheduler about
1070 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1071 scheduler's CPU selection logic accordingly, so that higher
1072 overall system performance can be achieved.
1073
1074 This feature will have no effect on CPUs without this feature.
1075
1076 If unsure say Y here.
1077
1078config UP_LATE_INIT
1079 def_bool y
1080 depends on !SMP && X86_LOCAL_APIC
1081
1082config X86_UP_APIC
1083 bool "Local APIC support on uniprocessors" if !PCI_MSI
1084 default PCI_MSI
1085 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1086 help
1087 A local APIC (Advanced Programmable Interrupt Controller) is an
1088 integrated interrupt controller in the CPU. If you have a single-CPU
1089 system which has a processor with a local APIC, you can say Y here to
1090 enable and use it. If you say Y here even though your machine doesn't
1091 have a local APIC, then the kernel will still run with no slowdown at
1092 all. The local APIC supports CPU-generated self-interrupts (timer,
1093 performance counters), and the NMI watchdog which detects hard
1094 lockups.
1095
1096config X86_UP_IOAPIC
1097 bool "IO-APIC support on uniprocessors"
1098 depends on X86_UP_APIC
1099 help
1100 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1101 SMP-capable replacement for PC-style interrupt controllers. Most
1102 SMP systems and many recent uniprocessor systems have one.
1103
1104 If you have a single-CPU system with an IO-APIC, you can say Y here
1105 to use it. If you say Y here even though your machine doesn't have
1106 an IO-APIC, then the kernel will still run with no slowdown at all.
1107
1108config X86_LOCAL_APIC
1109 def_bool y
1110 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1111 select IRQ_DOMAIN_HIERARCHY
1112
1113config X86_IO_APIC
1114 def_bool y
1115 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1116
1117config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1118 bool "Reroute for broken boot IRQs"
1119 depends on X86_IO_APIC
1120 help
1121 This option enables a workaround that fixes a source of
1122 spurious interrupts. This is recommended when threaded
1123 interrupt handling is used on systems where the generation of
1124 superfluous "boot interrupts" cannot be disabled.
1125
1126 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1127 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1128 kernel does during interrupt handling). On chipsets where this
1129 boot IRQ generation cannot be disabled, this workaround keeps
1130 the original IRQ line masked so that only the equivalent "boot
1131 IRQ" is delivered to the CPUs. The workaround also tells the
1132 kernel to set up the IRQ handler on the boot IRQ line. In this
1133 way only one interrupt is delivered to the kernel. Otherwise
1134 the spurious second interrupt may cause the kernel to bring
1135 down (vital) interrupt lines.
1136
1137 Only affects "broken" chipsets. Interrupt sharing may be
1138 increased on these systems.
1139
1140config X86_MCE
1141 bool "Machine Check / overheating reporting"
1142 select GENERIC_ALLOCATOR
1143 default y
1144 help
1145 Machine Check support allows the processor to notify the
1146 kernel if it detects a problem (e.g. overheating, data corruption).
1147 The action the kernel takes depends on the severity of the problem,
1148 ranging from warning messages to halting the machine.
1149
1150config X86_MCELOG_LEGACY
1151 bool "Support for deprecated /dev/mcelog character device"
1152 depends on X86_MCE
1153 help
1154 Enable support for /dev/mcelog which is needed by the old mcelog
1155 userspace logging daemon. Consider switching to the new generation
1156 rasdaemon solution.
1157
1158config X86_MCE_INTEL
1159 def_bool y
1160 prompt "Intel MCE features"
1161 depends on X86_MCE && X86_LOCAL_APIC
1162 help
1163 Additional support for intel specific MCE features such as
1164 the thermal monitor.
1165
1166config X86_MCE_AMD
1167 def_bool y
1168 prompt "AMD MCE features"
1169 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1170 help
1171 Additional support for AMD specific MCE features such as
1172 the DRAM Error Threshold.
1173
1174config X86_ANCIENT_MCE
1175 bool "Support for old Pentium 5 / WinChip machine checks"
1176 depends on X86_32 && X86_MCE
1177 help
1178 Include support for machine check handling on old Pentium 5 or WinChip
1179 systems. These typically need to be enabled explicitly on the command
1180 line.
1181
1182config X86_MCE_THRESHOLD
1183 depends on X86_MCE_AMD || X86_MCE_INTEL
1184 def_bool y
1185
1186config X86_MCE_INJECT
1187 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1188 tristate "Machine check injector support"
1189 help
1190 Provide support for injecting machine checks for testing purposes.
1191 If you don't know what a machine check is and you don't do kernel
1192 QA it is safe to say n.
1193
1194source "arch/x86/events/Kconfig"
1195
1196config X86_LEGACY_VM86
1197 bool "Legacy VM86 support"
1198 depends on X86_32
1199 help
1200 This option allows user programs to put the CPU into V8086
1201 mode, which is an 80286-era approximation of 16-bit real mode.
1202
1203 Some very old versions of X and/or vbetool require this option
1204 for user mode setting. Similarly, DOSEMU will use it if
1205 available to accelerate real mode DOS programs. However, any
1206 recent version of DOSEMU, X, or vbetool should be fully
1207 functional even without kernel VM86 support, as they will all
1208 fall back to software emulation. Nevertheless, if you are using
1209 a 16-bit DOS program where 16-bit performance matters, vm86
1210 mode might be faster than emulation and you might want to
1211 enable this option.
1212
1213 Note that any app that works on a 64-bit kernel is unlikely to
1214 need this option, as 64-bit kernels don't, and can't, support
1215 V8086 mode. This option is also unrelated to 16-bit protected
1216 mode and is not needed to run most 16-bit programs under Wine.
1217
1218 Enabling this option increases the complexity of the kernel
1219 and slows down exception handling a tiny bit.
1220
1221 If unsure, say N here.
1222
1223config VM86
1224 bool
1225 default X86_LEGACY_VM86
1226
1227config X86_16BIT
1228 bool "Enable support for 16-bit segments" if EXPERT
1229 default y
1230 depends on MODIFY_LDT_SYSCALL
1231 help
1232 This option is required by programs like Wine to run 16-bit
1233 protected mode legacy code on x86 processors. Disabling
1234 this option saves about 300 bytes on i386, or around 6K text
1235 plus 16K runtime memory on x86-64,
1236
1237config X86_ESPFIX32
1238 def_bool y
1239 depends on X86_16BIT && X86_32
1240
1241config X86_ESPFIX64
1242 def_bool y
1243 depends on X86_16BIT && X86_64
1244
1245config X86_VSYSCALL_EMULATION
1246 bool "Enable vsyscall emulation" if EXPERT
1247 default y
1248 depends on X86_64
1249 help
1250 This enables emulation of the legacy vsyscall page. Disabling
1251 it is roughly equivalent to booting with vsyscall=none, except
1252 that it will also disable the helpful warning if a program
1253 tries to use a vsyscall. With this option set to N, offending
1254 programs will just segfault, citing addresses of the form
1255 0xffffffffff600?00.
1256
1257 This option is required by many programs built before 2013, and
1258 care should be used even with newer programs if set to N.
1259
1260 Disabling this option saves about 7K of kernel size and
1261 possibly 4K of additional runtime pagetable memory.
1262
1263config X86_IOPL_IOPERM
1264 bool "IOPERM and IOPL Emulation"
1265 default y
1266 help
1267 This enables the ioperm() and iopl() syscalls which are necessary
1268 for legacy applications.
1269
1270 Legacy IOPL support is an overbroad mechanism which allows user
1271 space aside of accessing all 65536 I/O ports also to disable
1272 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1273 capabilities and permission from potentially active security
1274 modules.
1275
1276 The emulation restricts the functionality of the syscall to
1277 only allowing the full range I/O port access, but prevents the
1278 ability to disable interrupts from user space which would be
1279 granted if the hardware IOPL mechanism would be used.
1280
1281config TOSHIBA
1282 tristate "Toshiba Laptop support"
1283 depends on X86_32
1284 help
1285 This adds a driver to safely access the System Management Mode of
1286 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1287 not work on models with a Phoenix BIOS. The System Management Mode
1288 is used to set the BIOS and power saving options on Toshiba portables.
1289
1290 For information on utilities to make use of this driver see the
1291 Toshiba Linux utilities web site at:
1292 <http://www.buzzard.org.uk/toshiba/>.
1293
1294 Say Y if you intend to run this kernel on a Toshiba portable.
1295 Say N otherwise.
1296
1297config X86_REBOOTFIXUPS
1298 bool "Enable X86 board specific fixups for reboot"
1299 depends on X86_32
1300 help
1301 This enables chipset and/or board specific fixups to be done
1302 in order to get reboot to work correctly. This is only needed on
1303 some combinations of hardware and BIOS. The symptom, for which
1304 this config is intended, is when reboot ends with a stalled/hung
1305 system.
1306
1307 Currently, the only fixup is for the Geode machines using
1308 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1309
1310 Say Y if you want to enable the fixup. Currently, it's safe to
1311 enable this option even if you don't need it.
1312 Say N otherwise.
1313
1314config MICROCODE
1315 bool "CPU microcode loading support"
1316 default y
1317 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1318 help
1319 If you say Y here, you will be able to update the microcode on
1320 Intel and AMD processors. The Intel support is for the IA32 family,
1321 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1322 AMD support is for families 0x10 and later. You will obviously need
1323 the actual microcode binary data itself which is not shipped with
1324 the Linux kernel.
1325
1326 The preferred method to load microcode from a detached initrd is described
1327 in Documentation/x86/microcode.rst. For that you need to enable
1328 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1329 initrd for microcode blobs.
1330
1331 In addition, you can build the microcode into the kernel. For that you
1332 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1333 config option.
1334
1335config MICROCODE_INTEL
1336 bool "Intel microcode loading support"
1337 depends on CPU_SUP_INTEL && MICROCODE
1338 default MICROCODE
1339 help
1340 This options enables microcode patch loading support for Intel
1341 processors.
1342
1343 For the current Intel microcode data package go to
1344 <https://downloadcenter.intel.com> and search for
1345 'Linux Processor Microcode Data File'.
1346
1347config MICROCODE_AMD
1348 bool "AMD microcode loading support"
1349 depends on CPU_SUP_AMD && MICROCODE
1350 help
1351 If you select this option, microcode patch loading support for AMD
1352 processors will be enabled.
1353
1354config MICROCODE_LATE_LOADING
1355 bool "Late microcode loading (DANGEROUS)"
1356 default n
1357 depends on MICROCODE
1358 help
1359 Loading microcode late, when the system is up and executing instructions
1360 is a tricky business and should be avoided if possible. Just the sequence
1361 of synchronizing all cores and SMT threads is one fragile dance which does
1362 not guarantee that cores might not softlock after the loading. Therefore,
1363 use this at your own risk. Late loading taints the kernel too.
1364
1365config X86_MSR
1366 tristate "/dev/cpu/*/msr - Model-specific register support"
1367 help
1368 This device gives privileged processes access to the x86
1369 Model-Specific Registers (MSRs). It is a character device with
1370 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1371 MSR accesses are directed to a specific CPU on multi-processor
1372 systems.
1373
1374config X86_CPUID
1375 tristate "/dev/cpu/*/cpuid - CPU information support"
1376 help
1377 This device gives processes access to the x86 CPUID instruction to
1378 be executed on a specific processor. It is a character device
1379 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1380 /dev/cpu/31/cpuid.
1381
1382choice
1383 prompt "High Memory Support"
1384 default HIGHMEM4G
1385 depends on X86_32
1386
1387config NOHIGHMEM
1388 bool "off"
1389 help
1390 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1391 However, the address space of 32-bit x86 processors is only 4
1392 Gigabytes large. That means that, if you have a large amount of
1393 physical memory, not all of it can be "permanently mapped" by the
1394 kernel. The physical memory that's not permanently mapped is called
1395 "high memory".
1396
1397 If you are compiling a kernel which will never run on a machine with
1398 more than 1 Gigabyte total physical RAM, answer "off" here (default
1399 choice and suitable for most users). This will result in a "3GB/1GB"
1400 split: 3GB are mapped so that each process sees a 3GB virtual memory
1401 space and the remaining part of the 4GB virtual memory space is used
1402 by the kernel to permanently map as much physical memory as
1403 possible.
1404
1405 If the machine has between 1 and 4 Gigabytes physical RAM, then
1406 answer "4GB" here.
1407
1408 If more than 4 Gigabytes is used then answer "64GB" here. This
1409 selection turns Intel PAE (Physical Address Extension) mode on.
1410 PAE implements 3-level paging on IA32 processors. PAE is fully
1411 supported by Linux, PAE mode is implemented on all recent Intel
1412 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1413 then the kernel will not boot on CPUs that don't support PAE!
1414
1415 The actual amount of total physical memory will either be
1416 auto detected or can be forced by using a kernel command line option
1417 such as "mem=256M". (Try "man bootparam" or see the documentation of
1418 your boot loader (lilo or loadlin) about how to pass options to the
1419 kernel at boot time.)
1420
1421 If unsure, say "off".
1422
1423config HIGHMEM4G
1424 bool "4GB"
1425 help
1426 Select this if you have a 32-bit processor and between 1 and 4
1427 gigabytes of physical RAM.
1428
1429config HIGHMEM64G
1430 bool "64GB"
1431 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1432 select X86_PAE
1433 help
1434 Select this if you have a 32-bit processor and more than 4
1435 gigabytes of physical RAM.
1436
1437endchoice
1438
1439choice
1440 prompt "Memory split" if EXPERT
1441 default VMSPLIT_3G
1442 depends on X86_32
1443 help
1444 Select the desired split between kernel and user memory.
1445
1446 If the address range available to the kernel is less than the
1447 physical memory installed, the remaining memory will be available
1448 as "high memory". Accessing high memory is a little more costly
1449 than low memory, as it needs to be mapped into the kernel first.
1450 Note that increasing the kernel address space limits the range
1451 available to user programs, making the address space there
1452 tighter. Selecting anything other than the default 3G/1G split
1453 will also likely make your kernel incompatible with binary-only
1454 kernel modules.
1455
1456 If you are not absolutely sure what you are doing, leave this
1457 option alone!
1458
1459 config VMSPLIT_3G
1460 bool "3G/1G user/kernel split"
1461 config VMSPLIT_3G_OPT
1462 depends on !X86_PAE
1463 bool "3G/1G user/kernel split (for full 1G low memory)"
1464 config VMSPLIT_2G
1465 bool "2G/2G user/kernel split"
1466 config VMSPLIT_2G_OPT
1467 depends on !X86_PAE
1468 bool "2G/2G user/kernel split (for full 2G low memory)"
1469 config VMSPLIT_1G
1470 bool "1G/3G user/kernel split"
1471endchoice
1472
1473config PAGE_OFFSET
1474 hex
1475 default 0xB0000000 if VMSPLIT_3G_OPT
1476 default 0x80000000 if VMSPLIT_2G
1477 default 0x78000000 if VMSPLIT_2G_OPT
1478 default 0x40000000 if VMSPLIT_1G
1479 default 0xC0000000
1480 depends on X86_32
1481
1482config HIGHMEM
1483 def_bool y
1484 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1485
1486config X86_PAE
1487 bool "PAE (Physical Address Extension) Support"
1488 depends on X86_32 && !HIGHMEM4G
1489 select PHYS_ADDR_T_64BIT
1490 select SWIOTLB
1491 help
1492 PAE is required for NX support, and furthermore enables
1493 larger swapspace support for non-overcommit purposes. It
1494 has the cost of more pagetable lookup overhead, and also
1495 consumes more pagetable space per process.
1496
1497config X86_5LEVEL
1498 bool "Enable 5-level page tables support"
1499 default y
1500 select DYNAMIC_MEMORY_LAYOUT
1501 select SPARSEMEM_VMEMMAP
1502 depends on X86_64
1503 help
1504 5-level paging enables access to larger address space:
1505 upto 128 PiB of virtual address space and 4 PiB of
1506 physical address space.
1507
1508 It will be supported by future Intel CPUs.
1509
1510 A kernel with the option enabled can be booted on machines that
1511 support 4- or 5-level paging.
1512
1513 See Documentation/x86/x86_64/5level-paging.rst for more
1514 information.
1515
1516 Say N if unsure.
1517
1518config X86_DIRECT_GBPAGES
1519 def_bool y
1520 depends on X86_64
1521 help
1522 Certain kernel features effectively disable kernel
1523 linear 1 GB mappings (even if the CPU otherwise
1524 supports them), so don't confuse the user by printing
1525 that we have them enabled.
1526
1527config X86_CPA_STATISTICS
1528 bool "Enable statistic for Change Page Attribute"
1529 depends on DEBUG_FS
1530 help
1531 Expose statistics about the Change Page Attribute mechanism, which
1532 helps to determine the effectiveness of preserving large and huge
1533 page mappings when mapping protections are changed.
1534
1535config X86_MEM_ENCRYPT
1536 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1537 select DYNAMIC_PHYSICAL_MASK
1538 def_bool n
1539
1540config AMD_MEM_ENCRYPT
1541 bool "AMD Secure Memory Encryption (SME) support"
1542 depends on X86_64 && CPU_SUP_AMD
1543 select DMA_COHERENT_POOL
1544 select ARCH_USE_MEMREMAP_PROT
1545 select INSTRUCTION_DECODER
1546 select ARCH_HAS_CC_PLATFORM
1547 select X86_MEM_ENCRYPT
1548 help
1549 Say yes to enable support for the encryption of system memory.
1550 This requires an AMD processor that supports Secure Memory
1551 Encryption (SME).
1552
1553config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1554 bool "Activate AMD Secure Memory Encryption (SME) by default"
1555 depends on AMD_MEM_ENCRYPT
1556 help
1557 Say yes to have system memory encrypted by default if running on
1558 an AMD processor that supports Secure Memory Encryption (SME).
1559
1560 If set to Y, then the encryption of system memory can be
1561 deactivated with the mem_encrypt=off command line option.
1562
1563 If set to N, then the encryption of system memory can be
1564 activated with the mem_encrypt=on command line option.
1565
1566# Common NUMA Features
1567config NUMA
1568 bool "NUMA Memory Allocation and Scheduler Support"
1569 depends on SMP
1570 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1571 default y if X86_BIGSMP
1572 select USE_PERCPU_NUMA_NODE_ID
1573 help
1574 Enable NUMA (Non-Uniform Memory Access) support.
1575
1576 The kernel will try to allocate memory used by a CPU on the
1577 local memory controller of the CPU and add some more
1578 NUMA awareness to the kernel.
1579
1580 For 64-bit this is recommended if the system is Intel Core i7
1581 (or later), AMD Opteron, or EM64T NUMA.
1582
1583 For 32-bit this is only needed if you boot a 32-bit
1584 kernel on a 64-bit NUMA platform.
1585
1586 Otherwise, you should say N.
1587
1588config AMD_NUMA
1589 def_bool y
1590 prompt "Old style AMD Opteron NUMA detection"
1591 depends on X86_64 && NUMA && PCI
1592 help
1593 Enable AMD NUMA node topology detection. You should say Y here if
1594 you have a multi processor AMD system. This uses an old method to
1595 read the NUMA configuration directly from the builtin Northbridge
1596 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1597 which also takes priority if both are compiled in.
1598
1599config X86_64_ACPI_NUMA
1600 def_bool y
1601 prompt "ACPI NUMA detection"
1602 depends on X86_64 && NUMA && ACPI && PCI
1603 select ACPI_NUMA
1604 help
1605 Enable ACPI SRAT based node topology detection.
1606
1607config NUMA_EMU
1608 bool "NUMA emulation"
1609 depends on NUMA
1610 help
1611 Enable NUMA emulation. A flat machine will be split
1612 into virtual nodes when booted with "numa=fake=N", where N is the
1613 number of nodes. This is only useful for debugging.
1614
1615config NODES_SHIFT
1616 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1617 range 1 10
1618 default "10" if MAXSMP
1619 default "6" if X86_64
1620 default "3"
1621 depends on NUMA
1622 help
1623 Specify the maximum number of NUMA Nodes available on the target
1624 system. Increases memory reserved to accommodate various tables.
1625
1626config ARCH_FLATMEM_ENABLE
1627 def_bool y
1628 depends on X86_32 && !NUMA
1629
1630config ARCH_SPARSEMEM_ENABLE
1631 def_bool y
1632 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1633 select SPARSEMEM_STATIC if X86_32
1634 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1635
1636config ARCH_SPARSEMEM_DEFAULT
1637 def_bool X86_64 || (NUMA && X86_32)
1638
1639config ARCH_SELECT_MEMORY_MODEL
1640 def_bool y
1641 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1642
1643config ARCH_MEMORY_PROBE
1644 bool "Enable sysfs memory/probe interface"
1645 depends on MEMORY_HOTPLUG
1646 help
1647 This option enables a sysfs memory/probe interface for testing.
1648 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1649 If you are unsure how to answer this question, answer N.
1650
1651config ARCH_PROC_KCORE_TEXT
1652 def_bool y
1653 depends on X86_64 && PROC_KCORE
1654
1655config ILLEGAL_POINTER_VALUE
1656 hex
1657 default 0 if X86_32
1658 default 0xdead000000000000 if X86_64
1659
1660config X86_PMEM_LEGACY_DEVICE
1661 bool
1662
1663config X86_PMEM_LEGACY
1664 tristate "Support non-standard NVDIMMs and ADR protected memory"
1665 depends on PHYS_ADDR_T_64BIT
1666 depends on BLK_DEV
1667 select X86_PMEM_LEGACY_DEVICE
1668 select NUMA_KEEP_MEMINFO if NUMA
1669 select LIBNVDIMM
1670 help
1671 Treat memory marked using the non-standard e820 type of 12 as used
1672 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1673 The kernel will offer these regions to the 'pmem' driver so
1674 they can be used for persistent storage.
1675
1676 Say Y if unsure.
1677
1678config HIGHPTE
1679 bool "Allocate 3rd-level pagetables from highmem"
1680 depends on HIGHMEM
1681 help
1682 The VM uses one page table entry for each page of physical memory.
1683 For systems with a lot of RAM, this can be wasteful of precious
1684 low memory. Setting this option will put user-space page table
1685 entries in high memory.
1686
1687config X86_CHECK_BIOS_CORRUPTION
1688 bool "Check for low memory corruption"
1689 help
1690 Periodically check for memory corruption in low memory, which
1691 is suspected to be caused by BIOS. Even when enabled in the
1692 configuration, it is disabled at runtime. Enable it by
1693 setting "memory_corruption_check=1" on the kernel command
1694 line. By default it scans the low 64k of memory every 60
1695 seconds; see the memory_corruption_check_size and
1696 memory_corruption_check_period parameters in
1697 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1698
1699 When enabled with the default parameters, this option has
1700 almost no overhead, as it reserves a relatively small amount
1701 of memory and scans it infrequently. It both detects corruption
1702 and prevents it from affecting the running system.
1703
1704 It is, however, intended as a diagnostic tool; if repeatable
1705 BIOS-originated corruption always affects the same memory,
1706 you can use memmap= to prevent the kernel from using that
1707 memory.
1708
1709config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1710 bool "Set the default setting of memory_corruption_check"
1711 depends on X86_CHECK_BIOS_CORRUPTION
1712 default y
1713 help
1714 Set whether the default state of memory_corruption_check is
1715 on or off.
1716
1717config MATH_EMULATION
1718 bool
1719 depends on MODIFY_LDT_SYSCALL
1720 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1721 help
1722 Linux can emulate a math coprocessor (used for floating point
1723 operations) if you don't have one. 486DX and Pentium processors have
1724 a math coprocessor built in, 486SX and 386 do not, unless you added
1725 a 487DX or 387, respectively. (The messages during boot time can
1726 give you some hints here ["man dmesg"].) Everyone needs either a
1727 coprocessor or this emulation.
1728
1729 If you don't have a math coprocessor, you need to say Y here; if you
1730 say Y here even though you have a coprocessor, the coprocessor will
1731 be used nevertheless. (This behavior can be changed with the kernel
1732 command line option "no387", which comes handy if your coprocessor
1733 is broken. Try "man bootparam" or see the documentation of your boot
1734 loader (lilo or loadlin) about how to pass options to the kernel at
1735 boot time.) This means that it is a good idea to say Y here if you
1736 intend to use this kernel on different machines.
1737
1738 More information about the internals of the Linux math coprocessor
1739 emulation can be found in <file:arch/x86/math-emu/README>.
1740
1741 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1742 kernel, it won't hurt.
1743
1744config MTRR
1745 def_bool y
1746 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1747 help
1748 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1749 the Memory Type Range Registers (MTRRs) may be used to control
1750 processor access to memory ranges. This is most useful if you have
1751 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1752 allows bus write transfers to be combined into a larger transfer
1753 before bursting over the PCI/AGP bus. This can increase performance
1754 of image write operations 2.5 times or more. Saying Y here creates a
1755 /proc/mtrr file which may be used to manipulate your processor's
1756 MTRRs. Typically the X server should use this.
1757
1758 This code has a reasonably generic interface so that similar
1759 control registers on other processors can be easily supported
1760 as well:
1761
1762 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1763 Registers (ARRs) which provide a similar functionality to MTRRs. For
1764 these, the ARRs are used to emulate the MTRRs.
1765 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1766 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1767 write-combining. All of these processors are supported by this code
1768 and it makes sense to say Y here if you have one of them.
1769
1770 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1771 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1772 can lead to all sorts of problems, so it's good to say Y here.
1773
1774 You can safely say Y even if your machine doesn't have MTRRs, you'll
1775 just add about 9 KB to your kernel.
1776
1777 See <file:Documentation/x86/mtrr.rst> for more information.
1778
1779config MTRR_SANITIZER
1780 def_bool y
1781 prompt "MTRR cleanup support"
1782 depends on MTRR
1783 help
1784 Convert MTRR layout from continuous to discrete, so X drivers can
1785 add writeback entries.
1786
1787 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1788 The largest mtrr entry size for a continuous block can be set with
1789 mtrr_chunk_size.
1790
1791 If unsure, say Y.
1792
1793config MTRR_SANITIZER_ENABLE_DEFAULT
1794 int "MTRR cleanup enable value (0-1)"
1795 range 0 1
1796 default "0"
1797 depends on MTRR_SANITIZER
1798 help
1799 Enable mtrr cleanup default value
1800
1801config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1802 int "MTRR cleanup spare reg num (0-7)"
1803 range 0 7
1804 default "1"
1805 depends on MTRR_SANITIZER
1806 help
1807 mtrr cleanup spare entries default, it can be changed via
1808 mtrr_spare_reg_nr=N on the kernel command line.
1809
1810config X86_PAT
1811 def_bool y
1812 prompt "x86 PAT support" if EXPERT
1813 depends on MTRR
1814 help
1815 Use PAT attributes to setup page level cache control.
1816
1817 PATs are the modern equivalents of MTRRs and are much more
1818 flexible than MTRRs.
1819
1820 Say N here if you see bootup problems (boot crash, boot hang,
1821 spontaneous reboots) or a non-working video driver.
1822
1823 If unsure, say Y.
1824
1825config ARCH_USES_PG_UNCACHED
1826 def_bool y
1827 depends on X86_PAT
1828
1829config X86_UMIP
1830 def_bool y
1831 prompt "User Mode Instruction Prevention" if EXPERT
1832 help
1833 User Mode Instruction Prevention (UMIP) is a security feature in
1834 some x86 processors. If enabled, a general protection fault is
1835 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1836 executed in user mode. These instructions unnecessarily expose
1837 information about the hardware state.
1838
1839 The vast majority of applications do not use these instructions.
1840 For the very few that do, software emulation is provided in
1841 specific cases in protected and virtual-8086 modes. Emulated
1842 results are dummy.
1843
1844config CC_HAS_IBT
1845 # GCC >= 9 and binutils >= 2.29
1846 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1847 # Clang/LLVM >= 14
1848 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1849 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1850 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1851 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1852 $(as-instr,endbr64)
1853
1854config X86_KERNEL_IBT
1855 prompt "Indirect Branch Tracking"
1856 def_bool y
1857 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1858 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1859 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1860 select OBJTOOL
1861 help
1862 Build the kernel with support for Indirect Branch Tracking, a
1863 hardware support course-grain forward-edge Control Flow Integrity
1864 protection. It enforces that all indirect calls must land on
1865 an ENDBR instruction, as such, the compiler will instrument the
1866 code with them to make this happen.
1867
1868 In addition to building the kernel with IBT, seal all functions that
1869 are not indirect call targets, avoiding them ever becoming one.
1870
1871 This requires LTO like objtool runs and will slow down the build. It
1872 does significantly reduce the number of ENDBR instructions in the
1873 kernel image.
1874
1875config X86_INTEL_MEMORY_PROTECTION_KEYS
1876 prompt "Memory Protection Keys"
1877 def_bool y
1878 # Note: only available in 64-bit mode
1879 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1880 select ARCH_USES_HIGH_VMA_FLAGS
1881 select ARCH_HAS_PKEYS
1882 help
1883 Memory Protection Keys provides a mechanism for enforcing
1884 page-based protections, but without requiring modification of the
1885 page tables when an application changes protection domains.
1886
1887 For details, see Documentation/core-api/protection-keys.rst
1888
1889 If unsure, say y.
1890
1891choice
1892 prompt "TSX enable mode"
1893 depends on CPU_SUP_INTEL
1894 default X86_INTEL_TSX_MODE_OFF
1895 help
1896 Intel's TSX (Transactional Synchronization Extensions) feature
1897 allows to optimize locking protocols through lock elision which
1898 can lead to a noticeable performance boost.
1899
1900 On the other hand it has been shown that TSX can be exploited
1901 to form side channel attacks (e.g. TAA) and chances are there
1902 will be more of those attacks discovered in the future.
1903
1904 Therefore TSX is not enabled by default (aka tsx=off). An admin
1905 might override this decision by tsx=on the command line parameter.
1906 Even with TSX enabled, the kernel will attempt to enable the best
1907 possible TAA mitigation setting depending on the microcode available
1908 for the particular machine.
1909
1910 This option allows to set the default tsx mode between tsx=on, =off
1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1912 details.
1913
1914 Say off if not sure, auto if TSX is in use but it should be used on safe
1915 platforms or on if TSX is in use and the security aspect of tsx is not
1916 relevant.
1917
1918config X86_INTEL_TSX_MODE_OFF
1919 bool "off"
1920 help
1921 TSX is disabled if possible - equals to tsx=off command line parameter.
1922
1923config X86_INTEL_TSX_MODE_ON
1924 bool "on"
1925 help
1926 TSX is always enabled on TSX capable HW - equals the tsx=on command
1927 line parameter.
1928
1929config X86_INTEL_TSX_MODE_AUTO
1930 bool "auto"
1931 help
1932 TSX is enabled on TSX capable HW that is believed to be safe against
1933 side channel attacks- equals the tsx=auto command line parameter.
1934endchoice
1935
1936config X86_SGX
1937 bool "Software Guard eXtensions (SGX)"
1938 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1939 depends on CRYPTO=y
1940 depends on CRYPTO_SHA256=y
1941 select SRCU
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 EFI
1956 bool "EFI runtime service support"
1957 depends on ACPI
1958 select UCS2_STRING
1959 select EFI_RUNTIME_WRAPPERS
1960 select ARCH_USE_MEMREMAP_PROT
1961 help
1962 This enables the kernel to use EFI runtime services that are
1963 available (such as the EFI variable services).
1964
1965 This option is only useful on systems that have EFI firmware.
1966 In addition, you should use the latest ELILO loader available
1967 at <http://elilo.sourceforge.net> in order to take advantage
1968 of EFI runtime services. However, even with this option, the
1969 resultant kernel should continue to boot on existing non-EFI
1970 platforms.
1971
1972config EFI_STUB
1973 bool "EFI stub support"
1974 depends on EFI
1975 select RELOCATABLE
1976 help
1977 This kernel feature allows a bzImage to be loaded directly
1978 by EFI firmware without the use of a bootloader.
1979
1980 See Documentation/admin-guide/efi-stub.rst for more information.
1981
1982config EFI_HANDOVER_PROTOCOL
1983 bool "EFI handover protocol (DEPRECATED)"
1984 depends on EFI_STUB
1985 default y
1986 help
1987 Select this in order to include support for the deprecated EFI
1988 handover protocol, which defines alternative entry points into the
1989 EFI stub. This is a practice that has no basis in the UEFI
1990 specification, and requires a priori knowledge on the part of the
1991 bootloader about Linux/x86 specific ways of passing the command line
1992 and initrd, and where in memory those assets may be loaded.
1993
1994 If in doubt, say Y. Even though the corresponding support is not
1995 present in upstream GRUB or other bootloaders, most distros build
1996 GRUB with numerous downstream patches applied, and may rely on the
1997 handover protocol as as result.
1998
1999config EFI_MIXED
2000 bool "EFI mixed-mode support"
2001 depends on EFI_STUB && X86_64
2002 help
2003 Enabling this feature allows a 64-bit kernel to be booted
2004 on a 32-bit firmware, provided that your CPU supports 64-bit
2005 mode.
2006
2007 Note that it is not possible to boot a mixed-mode enabled
2008 kernel via the EFI boot stub - a bootloader that supports
2009 the EFI handover protocol must be used.
2010
2011 If unsure, say N.
2012
2013config EFI_FAKE_MEMMAP
2014 bool "Enable EFI fake memory map"
2015 depends on EFI
2016 help
2017 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2018 this parameter, you can add arbitrary attribute to specific memory
2019 range by updating original (firmware provided) EFI memmap. This is
2020 useful for debugging of EFI memmap related feature, e.g., Address
2021 Range Mirroring feature.
2022
2023config EFI_MAX_FAKE_MEM
2024 int "maximum allowable number of ranges in efi_fake_mem boot option"
2025 depends on EFI_FAKE_MEMMAP
2026 range 1 128
2027 default 8
2028 help
2029 Maximum allowable number of ranges in efi_fake_mem boot option.
2030 Ranges can be set up to this value using comma-separated list.
2031 The default value is 8.
2032
2033config EFI_RUNTIME_MAP
2034 bool "Export EFI runtime maps to sysfs" if EXPERT
2035 depends on EFI
2036 default KEXEC_CORE
2037 help
2038 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2039 That memory map is required by the 2nd kernel to set up EFI virtual
2040 mappings after kexec, but can also be used for debugging purposes.
2041
2042 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2043
2044source "kernel/Kconfig.hz"
2045
2046config KEXEC
2047 bool "kexec system call"
2048 select KEXEC_CORE
2049 help
2050 kexec is a system call that implements the ability to shutdown your
2051 current kernel, and to start another kernel. It is like a reboot
2052 but it is independent of the system firmware. And like a reboot
2053 you can start any kernel with it, not just Linux.
2054
2055 The name comes from the similarity to the exec system call.
2056
2057 It is an ongoing process to be certain the hardware in a machine
2058 is properly shutdown, so do not be surprised if this code does not
2059 initially work for you. As of this writing the exact hardware
2060 interface is strongly in flux, so no good recommendation can be
2061 made.
2062
2063config KEXEC_FILE
2064 bool "kexec file based system call"
2065 select KEXEC_CORE
2066 select HAVE_IMA_KEXEC if IMA
2067 depends on X86_64
2068 depends on CRYPTO=y
2069 depends on CRYPTO_SHA256=y
2070 help
2071 This is new version of kexec system call. This system call is
2072 file based and takes file descriptors as system call argument
2073 for kernel and initramfs as opposed to list of segments as
2074 accepted by previous system call.
2075
2076config ARCH_HAS_KEXEC_PURGATORY
2077 def_bool KEXEC_FILE
2078
2079config KEXEC_SIG
2080 bool "Verify kernel signature during kexec_file_load() syscall"
2081 depends on KEXEC_FILE
2082 help
2083
2084 This option makes the kexec_file_load() syscall check for a valid
2085 signature of the kernel image. The image can still be loaded without
2086 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2087 there's a signature that we can check, then it must be valid.
2088
2089 In addition to this option, you need to enable signature
2090 verification for the corresponding kernel image type being
2091 loaded in order for this to work.
2092
2093config KEXEC_SIG_FORCE
2094 bool "Require a valid signature in kexec_file_load() syscall"
2095 depends on KEXEC_SIG
2096 help
2097 This option makes kernel signature verification mandatory for
2098 the kexec_file_load() syscall.
2099
2100config KEXEC_BZIMAGE_VERIFY_SIG
2101 bool "Enable bzImage signature verification support"
2102 depends on KEXEC_SIG
2103 depends on SIGNED_PE_FILE_VERIFICATION
2104 select SYSTEM_TRUSTED_KEYRING
2105 help
2106 Enable bzImage signature verification support.
2107
2108config CRASH_DUMP
2109 bool "kernel crash dumps"
2110 depends on X86_64 || (X86_32 && HIGHMEM)
2111 help
2112 Generate crash dump after being started by kexec.
2113 This should be normally only set in special crash dump kernels
2114 which are loaded in the main kernel with kexec-tools into
2115 a specially reserved region and then later executed after
2116 a crash by kdump/kexec. The crash dump kernel must be compiled
2117 to a memory address not used by the main kernel or BIOS using
2118 PHYSICAL_START, or it must be built as a relocatable image
2119 (CONFIG_RELOCATABLE=y).
2120 For more details see Documentation/admin-guide/kdump/kdump.rst
2121
2122config KEXEC_JUMP
2123 bool "kexec jump"
2124 depends on KEXEC && HIBERNATION
2125 help
2126 Jump between original kernel and kexeced kernel and invoke
2127 code in physical address mode via KEXEC
2128
2129config PHYSICAL_START
2130 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2131 default "0x1000000"
2132 help
2133 This gives the physical address where the kernel is loaded.
2134
2135 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2136 bzImage will decompress itself to above physical address and
2137 run from there. Otherwise, bzImage will run from the address where
2138 it has been loaded by the boot loader and will ignore above physical
2139 address.
2140
2141 In normal kdump cases one does not have to set/change this option
2142 as now bzImage can be compiled as a completely relocatable image
2143 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2144 address. This option is mainly useful for the folks who don't want
2145 to use a bzImage for capturing the crash dump and want to use a
2146 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2147 to be specifically compiled to run from a specific memory area
2148 (normally a reserved region) and this option comes handy.
2149
2150 So if you are using bzImage for capturing the crash dump,
2151 leave the value here unchanged to 0x1000000 and set
2152 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2153 for capturing the crash dump change this value to start of
2154 the reserved region. In other words, it can be set based on
2155 the "X" value as specified in the "crashkernel=YM@XM"
2156 command line boot parameter passed to the panic-ed
2157 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2158 for more details about crash dumps.
2159
2160 Usage of bzImage for capturing the crash dump is recommended as
2161 one does not have to build two kernels. Same kernel can be used
2162 as production kernel and capture kernel. Above option should have
2163 gone away after relocatable bzImage support is introduced. But it
2164 is present because there are users out there who continue to use
2165 vmlinux for dump capture. This option should go away down the
2166 line.
2167
2168 Don't change this unless you know what you are doing.
2169
2170config RELOCATABLE
2171 bool "Build a relocatable kernel"
2172 default y
2173 help
2174 This builds a kernel image that retains relocation information
2175 so it can be loaded someplace besides the default 1MB.
2176 The relocations tend to make the kernel binary about 10% larger,
2177 but are discarded at runtime.
2178
2179 One use is for the kexec on panic case where the recovery kernel
2180 must live at a different physical address than the primary
2181 kernel.
2182
2183 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2184 it has been loaded at and the compile time physical address
2185 (CONFIG_PHYSICAL_START) is used as the minimum location.
2186
2187config RANDOMIZE_BASE
2188 bool "Randomize the address of the kernel image (KASLR)"
2189 depends on RELOCATABLE
2190 default y
2191 help
2192 In support of Kernel Address Space Layout Randomization (KASLR),
2193 this randomizes the physical address at which the kernel image
2194 is decompressed and the virtual address where the kernel
2195 image is mapped, as a security feature that deters exploit
2196 attempts relying on knowledge of the location of kernel
2197 code internals.
2198
2199 On 64-bit, the kernel physical and virtual addresses are
2200 randomized separately. The physical address will be anywhere
2201 between 16MB and the top of physical memory (up to 64TB). The
2202 virtual address will be randomized from 16MB up to 1GB (9 bits
2203 of entropy). Note that this also reduces the memory space
2204 available to kernel modules from 1.5GB to 1GB.
2205
2206 On 32-bit, the kernel physical and virtual addresses are
2207 randomized together. They will be randomized from 16MB up to
2208 512MB (8 bits of entropy).
2209
2210 Entropy is generated using the RDRAND instruction if it is
2211 supported. If RDTSC is supported, its value is mixed into
2212 the entropy pool as well. If neither RDRAND nor RDTSC are
2213 supported, then entropy is read from the i8254 timer. The
2214 usable entropy is limited by the kernel being built using
2215 2GB addressing, and that PHYSICAL_ALIGN must be at a
2216 minimum of 2MB. As a result, only 10 bits of entropy are
2217 theoretically possible, but the implementations are further
2218 limited due to memory layouts.
2219
2220 If unsure, say Y.
2221
2222# Relocation on x86 needs some additional build support
2223config X86_NEED_RELOCS
2224 def_bool y
2225 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2226
2227config PHYSICAL_ALIGN
2228 hex "Alignment value to which kernel should be aligned"
2229 default "0x200000"
2230 range 0x2000 0x1000000 if X86_32
2231 range 0x200000 0x1000000 if X86_64
2232 help
2233 This value puts the alignment restrictions on physical address
2234 where kernel is loaded and run from. Kernel is compiled for an
2235 address which meets above alignment restriction.
2236
2237 If bootloader loads the kernel at a non-aligned address and
2238 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2239 address aligned to above value and run from there.
2240
2241 If bootloader loads the kernel at a non-aligned address and
2242 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2243 load address and decompress itself to the address it has been
2244 compiled for and run from there. The address for which kernel is
2245 compiled already meets above alignment restrictions. Hence the
2246 end result is that kernel runs from a physical address meeting
2247 above alignment restrictions.
2248
2249 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2250 this value must be a multiple of 0x200000.
2251
2252 Don't change this unless you know what you are doing.
2253
2254config DYNAMIC_MEMORY_LAYOUT
2255 bool
2256 help
2257 This option makes base addresses of vmalloc and vmemmap as well as
2258 __PAGE_OFFSET movable during boot.
2259
2260config RANDOMIZE_MEMORY
2261 bool "Randomize the kernel memory sections"
2262 depends on X86_64
2263 depends on RANDOMIZE_BASE
2264 select DYNAMIC_MEMORY_LAYOUT
2265 default RANDOMIZE_BASE
2266 help
2267 Randomizes the base virtual address of kernel memory sections
2268 (physical memory mapping, vmalloc & vmemmap). This security feature
2269 makes exploits relying on predictable memory locations less reliable.
2270
2271 The order of allocations remains unchanged. Entropy is generated in
2272 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2273 configuration have in average 30,000 different possible virtual
2274 addresses for each memory section.
2275
2276 If unsure, say Y.
2277
2278config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2279 hex "Physical memory mapping padding" if EXPERT
2280 depends on RANDOMIZE_MEMORY
2281 default "0xa" if MEMORY_HOTPLUG
2282 default "0x0"
2283 range 0x1 0x40 if MEMORY_HOTPLUG
2284 range 0x0 0x40
2285 help
2286 Define the padding in terabytes added to the existing physical
2287 memory size during kernel memory randomization. It is useful
2288 for memory hotplug support but reduces the entropy available for
2289 address randomization.
2290
2291 If unsure, leave at the default value.
2292
2293config HOTPLUG_CPU
2294 def_bool y
2295 depends on SMP
2296
2297config BOOTPARAM_HOTPLUG_CPU0
2298 bool "Set default setting of cpu0_hotpluggable"
2299 depends on HOTPLUG_CPU
2300 help
2301 Set whether default state of cpu0_hotpluggable is on or off.
2302
2303 Say Y here to enable CPU0 hotplug by default. If this switch
2304 is turned on, there is no need to give cpu0_hotplug kernel
2305 parameter and the CPU0 hotplug feature is enabled by default.
2306
2307 Please note: there are two known CPU0 dependencies if you want
2308 to enable the CPU0 hotplug feature either by this switch or by
2309 cpu0_hotplug kernel parameter.
2310
2311 First, resume from hibernate or suspend always starts from CPU0.
2312 So hibernate and suspend are prevented if CPU0 is offline.
2313
2314 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2315 offline if any interrupt can not migrate out of CPU0. There may
2316 be other CPU0 dependencies.
2317
2318 Please make sure the dependencies are under your control before
2319 you enable this feature.
2320
2321 Say N if you don't want to enable CPU0 hotplug feature by default.
2322 You still can enable the CPU0 hotplug feature at boot by kernel
2323 parameter cpu0_hotplug.
2324
2325config DEBUG_HOTPLUG_CPU0
2326 def_bool n
2327 prompt "Debug CPU0 hotplug"
2328 depends on HOTPLUG_CPU
2329 help
2330 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2331 soon as possible and boots up userspace with CPU0 offlined. User
2332 can online CPU0 back after boot time.
2333
2334 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2335 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2336 compilation or giving cpu0_hotplug kernel parameter at boot.
2337
2338 If unsure, say N.
2339
2340config COMPAT_VDSO
2341 def_bool n
2342 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2343 depends on COMPAT_32
2344 help
2345 Certain buggy versions of glibc will crash if they are
2346 presented with a 32-bit vDSO that is not mapped at the address
2347 indicated in its segment table.
2348
2349 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2350 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2351 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2352 the only released version with the bug, but OpenSUSE 9
2353 contains a buggy "glibc 2.3.2".
2354
2355 The symptom of the bug is that everything crashes on startup, saying:
2356 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2357
2358 Saying Y here changes the default value of the vdso32 boot
2359 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2360 This works around the glibc bug but hurts performance.
2361
2362 If unsure, say N: if you are compiling your own kernel, you
2363 are unlikely to be using a buggy version of glibc.
2364
2365choice
2366 prompt "vsyscall table for legacy applications"
2367 depends on X86_64
2368 default LEGACY_VSYSCALL_XONLY
2369 help
2370 Legacy user code that does not know how to find the vDSO expects
2371 to be able to issue three syscalls by calling fixed addresses in
2372 kernel space. Since this location is not randomized with ASLR,
2373 it can be used to assist security vulnerability exploitation.
2374
2375 This setting can be changed at boot time via the kernel command
2376 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2377 is deprecated and can only be enabled using the kernel command
2378 line.
2379
2380 On a system with recent enough glibc (2.14 or newer) and no
2381 static binaries, you can say None without a performance penalty
2382 to improve security.
2383
2384 If unsure, select "Emulate execution only".
2385
2386 config LEGACY_VSYSCALL_XONLY
2387 bool "Emulate execution only"
2388 help
2389 The kernel traps and emulates calls into the fixed vsyscall
2390 address mapping and does not allow reads. This
2391 configuration is recommended when userspace might use the
2392 legacy vsyscall area but support for legacy binary
2393 instrumentation of legacy code is not needed. It mitigates
2394 certain uses of the vsyscall area as an ASLR-bypassing
2395 buffer.
2396
2397 config LEGACY_VSYSCALL_NONE
2398 bool "None"
2399 help
2400 There will be no vsyscall mapping at all. This will
2401 eliminate any risk of ASLR bypass due to the vsyscall
2402 fixed address mapping. Attempts to use the vsyscalls
2403 will be reported to dmesg, so that either old or
2404 malicious userspace programs can be identified.
2405
2406endchoice
2407
2408config CMDLINE_BOOL
2409 bool "Built-in kernel command line"
2410 help
2411 Allow for specifying boot arguments to the kernel at
2412 build time. On some systems (e.g. embedded ones), it is
2413 necessary or convenient to provide some or all of the
2414 kernel boot arguments with the kernel itself (that is,
2415 to not rely on the boot loader to provide them.)
2416
2417 To compile command line arguments into the kernel,
2418 set this option to 'Y', then fill in the
2419 boot arguments in CONFIG_CMDLINE.
2420
2421 Systems with fully functional boot loaders (i.e. non-embedded)
2422 should leave this option set to 'N'.
2423
2424config CMDLINE
2425 string "Built-in kernel command string"
2426 depends on CMDLINE_BOOL
2427 default ""
2428 help
2429 Enter arguments here that should be compiled into the kernel
2430 image and used at boot time. If the boot loader provides a
2431 command line at boot time, it is appended to this string to
2432 form the full kernel command line, when the system boots.
2433
2434 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2435 change this behavior.
2436
2437 In most cases, the command line (whether built-in or provided
2438 by the boot loader) should specify the device for the root
2439 file system.
2440
2441config CMDLINE_OVERRIDE
2442 bool "Built-in command line overrides boot loader arguments"
2443 depends on CMDLINE_BOOL && CMDLINE != ""
2444 help
2445 Set this option to 'Y' to have the kernel ignore the boot loader
2446 command line, and use ONLY the built-in command line.
2447
2448 This is used to work around broken boot loaders. This should
2449 be set to 'N' under normal conditions.
2450
2451config MODIFY_LDT_SYSCALL
2452 bool "Enable the LDT (local descriptor table)" if EXPERT
2453 default y
2454 help
2455 Linux can allow user programs to install a per-process x86
2456 Local Descriptor Table (LDT) using the modify_ldt(2) system
2457 call. This is required to run 16-bit or segmented code such as
2458 DOSEMU or some Wine programs. It is also used by some very old
2459 threading libraries.
2460
2461 Enabling this feature adds a small amount of overhead to
2462 context switches and increases the low-level kernel attack
2463 surface. Disabling it removes the modify_ldt(2) system call.
2464
2465 Saying 'N' here may make sense for embedded or server kernels.
2466
2467config STRICT_SIGALTSTACK_SIZE
2468 bool "Enforce strict size checking for sigaltstack"
2469 depends on DYNAMIC_SIGFRAME
2470 help
2471 For historical reasons MINSIGSTKSZ is a constant which became
2472 already too small with AVX512 support. Add a mechanism to
2473 enforce strict checking of the sigaltstack size against the
2474 real size of the FPU frame. This option enables the check
2475 by default. It can also be controlled via the kernel command
2476 line option 'strict_sas_size' independent of this config
2477 switch. Enabling it might break existing applications which
2478 allocate a too small sigaltstack but 'work' because they
2479 never get a signal delivered.
2480
2481 Say 'N' unless you want to really enforce this check.
2482
2483source "kernel/livepatch/Kconfig"
2484
2485endmenu
2486
2487config CC_HAS_SLS
2488 def_bool $(cc-option,-mharden-sls=all)
2489
2490config CC_HAS_RETURN_THUNK
2491 def_bool $(cc-option,-mfunction-return=thunk-extern)
2492
2493config CC_HAS_ENTRY_PADDING
2494 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2495
2496config FUNCTION_PADDING_CFI
2497 int
2498 default 59 if FUNCTION_ALIGNMENT_64B
2499 default 27 if FUNCTION_ALIGNMENT_32B
2500 default 11 if FUNCTION_ALIGNMENT_16B
2501 default 3 if FUNCTION_ALIGNMENT_8B
2502 default 0
2503
2504# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2505# except Kconfig can't do arithmetic :/
2506config FUNCTION_PADDING_BYTES
2507 int
2508 default FUNCTION_PADDING_CFI if CFI_CLANG
2509 default FUNCTION_ALIGNMENT
2510
2511config CALL_PADDING
2512 def_bool n
2513 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2514 select FUNCTION_ALIGNMENT_16B
2515
2516config FINEIBT
2517 def_bool y
2518 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2519 select CALL_PADDING
2520
2521config HAVE_CALL_THUNKS
2522 def_bool y
2523 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2524
2525config CALL_THUNKS
2526 def_bool n
2527 select CALL_PADDING
2528
2529config PREFIX_SYMBOLS
2530 def_bool y
2531 depends on CALL_PADDING && !CFI_CLANG
2532
2533menuconfig SPECULATION_MITIGATIONS
2534 bool "Mitigations for speculative execution vulnerabilities"
2535 default y
2536 help
2537 Say Y here to enable options which enable mitigations for
2538 speculative execution hardware vulnerabilities.
2539
2540 If you say N, all mitigations will be disabled. You really
2541 should know what you are doing to say so.
2542
2543if SPECULATION_MITIGATIONS
2544
2545config PAGE_TABLE_ISOLATION
2546 bool "Remove the kernel mapping in user mode"
2547 default y
2548 depends on (X86_64 || X86_PAE)
2549 help
2550 This feature reduces the number of hardware side channels by
2551 ensuring that the majority of kernel addresses are not mapped
2552 into userspace.
2553
2554 See Documentation/x86/pti.rst for more details.
2555
2556config RETPOLINE
2557 bool "Avoid speculative indirect branches in kernel"
2558 select OBJTOOL if HAVE_OBJTOOL
2559 default y
2560 help
2561 Compile kernel with the retpoline compiler options to guard against
2562 kernel-to-user data leaks by avoiding speculative indirect
2563 branches. Requires a compiler with -mindirect-branch=thunk-extern
2564 support for full protection. The kernel may run slower.
2565
2566config RETHUNK
2567 bool "Enable return-thunks"
2568 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2569 select OBJTOOL if HAVE_OBJTOOL
2570 default y if X86_64
2571 help
2572 Compile the kernel with the return-thunks compiler option to guard
2573 against kernel-to-user data leaks by avoiding return speculation.
2574 Requires a compiler with -mfunction-return=thunk-extern
2575 support for full protection. The kernel may run slower.
2576
2577config CPU_UNRET_ENTRY
2578 bool "Enable UNRET on kernel entry"
2579 depends on CPU_SUP_AMD && RETHUNK && X86_64
2580 default y
2581 help
2582 Compile the kernel with support for the retbleed=unret mitigation.
2583
2584config CALL_DEPTH_TRACKING
2585 bool "Mitigate RSB underflow with call depth tracking"
2586 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2587 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2588 select CALL_THUNKS
2589 default y
2590 help
2591 Compile the kernel with call depth tracking to mitigate the Intel
2592 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2593 mitigation is off by default and needs to be enabled on the
2594 kernel command line via the retbleed=stuff option. For
2595 non-affected systems the overhead of this option is marginal as
2596 the call depth tracking is using run-time generated call thunks
2597 in a compiler generated padding area and call patching. This
2598 increases text size by ~5%. For non affected systems this space
2599 is unused. On affected SKL systems this results in a significant
2600 performance gain over the IBRS mitigation.
2601
2602config CALL_THUNKS_DEBUG
2603 bool "Enable call thunks and call depth tracking debugging"
2604 depends on CALL_DEPTH_TRACKING
2605 select FUNCTION_ALIGNMENT_32B
2606 default n
2607 help
2608 Enable call/ret counters for imbalance detection and build in
2609 a noisy dmesg about callthunks generation and call patching for
2610 trouble shooting. The debug prints need to be enabled on the
2611 kernel command line with 'debug-callthunks'.
2612 Only enable this, when you are debugging call thunks as this
2613 creates a noticable runtime overhead. If unsure say N.
2614
2615config CPU_IBPB_ENTRY
2616 bool "Enable IBPB on kernel entry"
2617 depends on CPU_SUP_AMD && X86_64
2618 default y
2619 help
2620 Compile the kernel with support for the retbleed=ibpb mitigation.
2621
2622config CPU_IBRS_ENTRY
2623 bool "Enable IBRS on kernel entry"
2624 depends on CPU_SUP_INTEL && X86_64
2625 default y
2626 help
2627 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2628 This mitigates both spectre_v2 and retbleed at great cost to
2629 performance.
2630
2631config SLS
2632 bool "Mitigate Straight-Line-Speculation"
2633 depends on CC_HAS_SLS && X86_64
2634 select OBJTOOL if HAVE_OBJTOOL
2635 default n
2636 help
2637 Compile the kernel with straight-line-speculation options to guard
2638 against straight line speculation. The kernel image might be slightly
2639 larger.
2640
2641endif
2642
2643config ARCH_HAS_ADD_PAGES
2644 def_bool y
2645 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2646
2647config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2648 def_bool y
2649
2650menu "Power management and ACPI options"
2651
2652config ARCH_HIBERNATION_HEADER
2653 def_bool y
2654 depends on HIBERNATION
2655
2656source "kernel/power/Kconfig"
2657
2658source "drivers/acpi/Kconfig"
2659
2660config X86_APM_BOOT
2661 def_bool y
2662 depends on APM
2663
2664menuconfig APM
2665 tristate "APM (Advanced Power Management) BIOS support"
2666 depends on X86_32 && PM_SLEEP
2667 help
2668 APM is a BIOS specification for saving power using several different
2669 techniques. This is mostly useful for battery powered laptops with
2670 APM compliant BIOSes. If you say Y here, the system time will be
2671 reset after a RESUME operation, the /proc/apm device will provide
2672 battery status information, and user-space programs will receive
2673 notification of APM "events" (e.g. battery status change).
2674
2675 If you select "Y" here, you can disable actual use of the APM
2676 BIOS by passing the "apm=off" option to the kernel at boot time.
2677
2678 Note that the APM support is almost completely disabled for
2679 machines with more than one CPU.
2680
2681 In order to use APM, you will need supporting software. For location
2682 and more information, read <file:Documentation/power/apm-acpi.rst>
2683 and the Battery Powered Linux mini-HOWTO, available from
2684 <http://www.tldp.org/docs.html#howto>.
2685
2686 This driver does not spin down disk drives (see the hdparm(8)
2687 manpage ("man 8 hdparm") for that), and it doesn't turn off
2688 VESA-compliant "green" monitors.
2689
2690 This driver does not support the TI 4000M TravelMate and the ACER
2691 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2692 desktop machines also don't have compliant BIOSes, and this driver
2693 may cause those machines to panic during the boot phase.
2694
2695 Generally, if you don't have a battery in your machine, there isn't
2696 much point in using this driver and you should say N. If you get
2697 random kernel OOPSes or reboots that don't seem to be related to
2698 anything, try disabling/enabling this option (or disabling/enabling
2699 APM in your BIOS).
2700
2701 Some other things you should try when experiencing seemingly random,
2702 "weird" problems:
2703
2704 1) make sure that you have enough swap space and that it is
2705 enabled.
2706 2) pass the "idle=poll" option to the kernel
2707 3) switch on floating point emulation in the kernel and pass
2708 the "no387" option to the kernel
2709 4) pass the "floppy=nodma" option to the kernel
2710 5) pass the "mem=4M" option to the kernel (thereby disabling
2711 all but the first 4 MB of RAM)
2712 6) make sure that the CPU is not over clocked.
2713 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2714 8) disable the cache from your BIOS settings
2715 9) install a fan for the video card or exchange video RAM
2716 10) install a better fan for the CPU
2717 11) exchange RAM chips
2718 12) exchange the motherboard.
2719
2720 To compile this driver as a module, choose M here: the
2721 module will be called apm.
2722
2723if APM
2724
2725config APM_IGNORE_USER_SUSPEND
2726 bool "Ignore USER SUSPEND"
2727 help
2728 This option will ignore USER SUSPEND requests. On machines with a
2729 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2730 series notebooks, it is necessary to say Y because of a BIOS bug.
2731
2732config APM_DO_ENABLE
2733 bool "Enable PM at boot time"
2734 help
2735 Enable APM features at boot time. From page 36 of the APM BIOS
2736 specification: "When disabled, the APM BIOS does not automatically
2737 power manage devices, enter the Standby State, enter the Suspend
2738 State, or take power saving steps in response to CPU Idle calls."
2739 This driver will make CPU Idle calls when Linux is idle (unless this
2740 feature is turned off -- see "Do CPU IDLE calls", below). This
2741 should always save battery power, but more complicated APM features
2742 will be dependent on your BIOS implementation. You may need to turn
2743 this option off if your computer hangs at boot time when using APM
2744 support, or if it beeps continuously instead of suspending. Turn
2745 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2746 T400CDT. This is off by default since most machines do fine without
2747 this feature.
2748
2749config APM_CPU_IDLE
2750 depends on CPU_IDLE
2751 bool "Make CPU Idle calls when idle"
2752 help
2753 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2754 On some machines, this can activate improved power savings, such as
2755 a slowed CPU clock rate, when the machine is idle. These idle calls
2756 are made after the idle loop has run for some length of time (e.g.,
2757 333 mS). On some machines, this will cause a hang at boot time or
2758 whenever the CPU becomes idle. (On machines with more than one CPU,
2759 this option does nothing.)
2760
2761config APM_DISPLAY_BLANK
2762 bool "Enable console blanking using APM"
2763 help
2764 Enable console blanking using the APM. Some laptops can use this to
2765 turn off the LCD backlight when the screen blanker of the Linux
2766 virtual console blanks the screen. Note that this is only used by
2767 the virtual console screen blanker, and won't turn off the backlight
2768 when using the X Window system. This also doesn't have anything to
2769 do with your VESA-compliant power-saving monitor. Further, this
2770 option doesn't work for all laptops -- it might not turn off your
2771 backlight at all, or it might print a lot of errors to the console,
2772 especially if you are using gpm.
2773
2774config APM_ALLOW_INTS
2775 bool "Allow interrupts during APM BIOS calls"
2776 help
2777 Normally we disable external interrupts while we are making calls to
2778 the APM BIOS as a measure to lessen the effects of a badly behaving
2779 BIOS implementation. The BIOS should reenable interrupts if it
2780 needs to. Unfortunately, some BIOSes do not -- especially those in
2781 many of the newer IBM Thinkpads. If you experience hangs when you
2782 suspend, try setting this to Y. Otherwise, say N.
2783
2784endif # APM
2785
2786source "drivers/cpufreq/Kconfig"
2787
2788source "drivers/cpuidle/Kconfig"
2789
2790source "drivers/idle/Kconfig"
2791
2792endmenu
2793
2794menu "Bus options (PCI etc.)"
2795
2796choice
2797 prompt "PCI access mode"
2798 depends on X86_32 && PCI
2799 default PCI_GOANY
2800 help
2801 On PCI systems, the BIOS can be used to detect the PCI devices and
2802 determine their configuration. However, some old PCI motherboards
2803 have BIOS bugs and may crash if this is done. Also, some embedded
2804 PCI-based systems don't have any BIOS at all. Linux can also try to
2805 detect the PCI hardware directly without using the BIOS.
2806
2807 With this option, you can specify how Linux should detect the
2808 PCI devices. If you choose "BIOS", the BIOS will be used,
2809 if you choose "Direct", the BIOS won't be used, and if you
2810 choose "MMConfig", then PCI Express MMCONFIG will be used.
2811 If you choose "Any", the kernel will try MMCONFIG, then the
2812 direct access method and falls back to the BIOS if that doesn't
2813 work. If unsure, go with the default, which is "Any".
2814
2815config PCI_GOBIOS
2816 bool "BIOS"
2817
2818config PCI_GOMMCONFIG
2819 bool "MMConfig"
2820
2821config PCI_GODIRECT
2822 bool "Direct"
2823
2824config PCI_GOOLPC
2825 bool "OLPC XO-1"
2826 depends on OLPC
2827
2828config PCI_GOANY
2829 bool "Any"
2830
2831endchoice
2832
2833config PCI_BIOS
2834 def_bool y
2835 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2836
2837# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2838config PCI_DIRECT
2839 def_bool y
2840 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2841
2842config PCI_MMCONFIG
2843 bool "Support mmconfig PCI config space access" if X86_64
2844 default y
2845 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2846 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2847
2848config PCI_OLPC
2849 def_bool y
2850 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2851
2852config PCI_XEN
2853 def_bool y
2854 depends on PCI && XEN
2855
2856config MMCONF_FAM10H
2857 def_bool y
2858 depends on X86_64 && PCI_MMCONFIG && ACPI
2859
2860config PCI_CNB20LE_QUIRK
2861 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2862 depends on PCI
2863 help
2864 Read the PCI windows out of the CNB20LE host bridge. This allows
2865 PCI hotplug to work on systems with the CNB20LE chipset which do
2866 not have ACPI.
2867
2868 There's no public spec for this chipset, and this functionality
2869 is known to be incomplete.
2870
2871 You should say N unless you know you need this.
2872
2873config ISA_BUS
2874 bool "ISA bus support on modern systems" if EXPERT
2875 help
2876 Expose ISA bus device drivers and options available for selection and
2877 configuration. Enable this option if your target machine has an ISA
2878 bus. ISA is an older system, displaced by PCI and newer bus
2879 architectures -- if your target machine is modern, it probably does
2880 not have an ISA bus.
2881
2882 If unsure, say N.
2883
2884# x86_64 have no ISA slots, but can have ISA-style DMA.
2885config ISA_DMA_API
2886 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2887 default y
2888 help
2889 Enables ISA-style DMA support for devices requiring such controllers.
2890 If unsure, say Y.
2891
2892if X86_32
2893
2894config ISA
2895 bool "ISA support"
2896 help
2897 Find out whether you have ISA slots on your motherboard. ISA is the
2898 name of a bus system, i.e. the way the CPU talks to the other stuff
2899 inside your box. Other bus systems are PCI, EISA, MicroChannel
2900 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2901 newer boards don't support it. If you have ISA, say Y, otherwise N.
2902
2903config SCx200
2904 tristate "NatSemi SCx200 support"
2905 help
2906 This provides basic support for National Semiconductor's
2907 (now AMD's) Geode processors. The driver probes for the
2908 PCI-IDs of several on-chip devices, so its a good dependency
2909 for other scx200_* drivers.
2910
2911 If compiled as a module, the driver is named scx200.
2912
2913config SCx200HR_TIMER
2914 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2915 depends on SCx200
2916 default y
2917 help
2918 This driver provides a clocksource built upon the on-chip
2919 27MHz high-resolution timer. Its also a workaround for
2920 NSC Geode SC-1100's buggy TSC, which loses time when the
2921 processor goes idle (as is done by the scheduler). The
2922 other workaround is idle=poll boot option.
2923
2924config OLPC
2925 bool "One Laptop Per Child support"
2926 depends on !X86_PAE
2927 select GPIOLIB
2928 select OF
2929 select OF_PROMTREE
2930 select IRQ_DOMAIN
2931 select OLPC_EC
2932 help
2933 Add support for detecting the unique features of the OLPC
2934 XO hardware.
2935
2936config OLPC_XO1_PM
2937 bool "OLPC XO-1 Power Management"
2938 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2939 help
2940 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2941
2942config OLPC_XO1_RTC
2943 bool "OLPC XO-1 Real Time Clock"
2944 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2945 help
2946 Add support for the XO-1 real time clock, which can be used as a
2947 programmable wakeup source.
2948
2949config OLPC_XO1_SCI
2950 bool "OLPC XO-1 SCI extras"
2951 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2952 depends on INPUT=y
2953 select POWER_SUPPLY
2954 help
2955 Add support for SCI-based features of the OLPC XO-1 laptop:
2956 - EC-driven system wakeups
2957 - Power button
2958 - Ebook switch
2959 - Lid switch
2960 - AC adapter status updates
2961 - Battery status updates
2962
2963config OLPC_XO15_SCI
2964 bool "OLPC XO-1.5 SCI extras"
2965 depends on OLPC && ACPI
2966 select POWER_SUPPLY
2967 help
2968 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2969 - EC-driven system wakeups
2970 - AC adapter status updates
2971 - Battery status updates
2972
2973config ALIX
2974 bool "PCEngines ALIX System Support (LED setup)"
2975 select GPIOLIB
2976 help
2977 This option enables system support for the PCEngines ALIX.
2978 At present this just sets up LEDs for GPIO control on
2979 ALIX2/3/6 boards. However, other system specific setup should
2980 get added here.
2981
2982 Note: You must still enable the drivers for GPIO and LED support
2983 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2984
2985 Note: You have to set alix.force=1 for boards with Award BIOS.
2986
2987config NET5501
2988 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2989 select GPIOLIB
2990 help
2991 This option enables system support for the Soekris Engineering net5501.
2992
2993config GEOS
2994 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2995 select GPIOLIB
2996 depends on DMI
2997 help
2998 This option enables system support for the Traverse Technologies GEOS.
2999
3000config TS5500
3001 bool "Technologic Systems TS-5500 platform support"
3002 depends on MELAN
3003 select CHECK_SIGNATURE
3004 select NEW_LEDS
3005 select LEDS_CLASS
3006 help
3007 This option enables system support for the Technologic Systems TS-5500.
3008
3009endif # X86_32
3010
3011config AMD_NB
3012 def_bool y
3013 depends on CPU_SUP_AMD && PCI
3014
3015endmenu
3016
3017menu "Binary Emulations"
3018
3019config IA32_EMULATION
3020 bool "IA32 Emulation"
3021 depends on X86_64
3022 select ARCH_WANT_OLD_COMPAT_IPC
3023 select BINFMT_ELF
3024 select COMPAT_OLD_SIGACTION
3025 help
3026 Include code to run legacy 32-bit programs under a
3027 64-bit kernel. You should likely turn this on, unless you're
3028 100% sure that you don't have any 32-bit programs left.
3029
3030config X86_X32_ABI
3031 bool "x32 ABI for 64-bit mode"
3032 depends on X86_64
3033 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3034 # compressed debug sections to x86_x32 properly:
3035 # https://github.com/ClangBuiltLinux/linux/issues/514
3036 # https://github.com/ClangBuiltLinux/linux/issues/1141
3037 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3038 help
3039 Include code to run binaries for the x32 native 32-bit ABI
3040 for 64-bit processors. An x32 process gets access to the
3041 full 64-bit register file and wide data path while leaving
3042 pointers at 32 bits for smaller memory footprint.
3043
3044config COMPAT_32
3045 def_bool y
3046 depends on IA32_EMULATION || X86_32
3047 select HAVE_UID16
3048 select OLD_SIGSUSPEND3
3049
3050config COMPAT
3051 def_bool y
3052 depends on IA32_EMULATION || X86_X32_ABI
3053
3054config COMPAT_FOR_U64_ALIGNMENT
3055 def_bool y
3056 depends on COMPAT
3057
3058endmenu
3059
3060config HAVE_ATOMIC_IOMAP
3061 def_bool y
3062 depends on X86_32
3063
3064source "arch/x86/kvm/Kconfig"
3065
3066source "arch/x86/Kconfig.assembler"