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1# SPDX-License-Identifier: GPL-2.0
2config ARM
3 bool
4 default y
5 select ARCH_32BIT_OFF_T
6 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE if HAVE_KRETPROBES && FRAME_POINTER && !ARM_UNWIND
7 select ARCH_HAS_BINFMT_FLAT
8 select ARCH_HAS_CPU_CACHE_ALIASING
9 select ARCH_HAS_CPU_FINALIZE_INIT if MMU
10 select ARCH_HAS_CURRENT_STACK_POINTER
11 select ARCH_HAS_DEBUG_VIRTUAL if MMU
12 select ARCH_HAS_DMA_ALLOC if MMU
13 select ARCH_HAS_DMA_OPS
14 select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
15 select ARCH_HAS_ELF_RANDOMIZE
16 select ARCH_HAS_FORTIFY_SOURCE
17 select ARCH_HAS_KEEPINITRD
18 select ARCH_HAS_KCOV
19 select ARCH_HAS_MEMBARRIER_SYNC_CORE
20 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
21 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
22 select ARCH_HAS_SETUP_DMA_OPS
23 select ARCH_HAS_SET_MEMORY
24 select ARCH_STACKWALK
25 select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
26 select ARCH_HAS_STRICT_MODULE_RWX if MMU
27 select ARCH_HAS_SYNC_DMA_FOR_DEVICE
28 select ARCH_HAS_SYNC_DMA_FOR_CPU
29 select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
30 select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
31 select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
32 select ARCH_HAS_GCOV_PROFILE_ALL
33 select ARCH_KEEP_MEMBLOCK
34 select ARCH_HAS_UBSAN
35 select ARCH_MIGHT_HAVE_PC_PARPORT
36 select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
37 select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
38 select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6
39 select ARCH_SUPPORTS_ATOMIC_RMW
40 select ARCH_SUPPORTS_CFI_CLANG
41 select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
42 select ARCH_SUPPORTS_PER_VMA_LOCK
43 select ARCH_USE_BUILTIN_BSWAP
44 select ARCH_USE_CMPXCHG_LOCKREF
45 select ARCH_USE_MEMTEST
46 select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
47 select ARCH_WANT_GENERAL_HUGETLB
48 select ARCH_WANT_IPC_PARSE_VERSION
49 select ARCH_WANT_LD_ORPHAN_WARN
50 select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
51 select BUILDTIME_TABLE_SORT if MMU
52 select COMMON_CLK if !(ARCH_RPC || ARCH_FOOTBRIDGE)
53 select CLONE_BACKWARDS
54 select CPU_PM if SUSPEND || CPU_IDLE
55 select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
56 select DMA_DECLARE_COHERENT
57 select DMA_GLOBAL_POOL if !MMU
58 select DMA_NONCOHERENT_MMAP if MMU
59 select EDAC_SUPPORT
60 select EDAC_ATOMIC_SCRUB
61 select GENERIC_ALLOCATOR
62 select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
63 select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
64 select GENERIC_CLOCKEVENTS_BROADCAST if SMP
65 select GENERIC_IRQ_IPI if SMP
66 select GENERIC_CPU_AUTOPROBE
67 select GENERIC_CPU_DEVICES
68 select GENERIC_EARLY_IOREMAP
69 select GENERIC_IDLE_POLL_SETUP
70 select GENERIC_IRQ_MULTI_HANDLER
71 select GENERIC_IRQ_PROBE
72 select GENERIC_IRQ_SHOW
73 select GENERIC_IRQ_SHOW_LEVEL
74 select GENERIC_LIB_DEVMEM_IS_ALLOWED
75 select GENERIC_PCI_IOMAP
76 select GENERIC_SCHED_CLOCK
77 select GENERIC_SMP_IDLE_THREAD
78 select HARDIRQS_SW_RESEND
79 select HAS_IOPORT
80 select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
81 select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
82 select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
83 select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
84 select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
85 select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
86 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
87 select HAVE_ARCH_MMAP_RND_BITS if MMU
88 select HAVE_ARCH_PFN_VALID
89 select HAVE_ARCH_SECCOMP
90 select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
91 select HAVE_ARCH_STACKLEAK
92 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
93 select HAVE_ARCH_TRACEHOOK
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
95 select HAVE_ARM_SMCCC if CPU_V7
96 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
97 select HAVE_CONTEXT_TRACKING_USER
98 select HAVE_C_RECORDMCOUNT
99 select HAVE_BUILDTIME_MCOUNT_SORT
100 select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
101 select HAVE_DMA_CONTIGUOUS if MMU
102 select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
103 select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
104 select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
105 select HAVE_EXIT_THREAD
106 select HAVE_GUP_FAST if ARM_LPAE
107 select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
108 select HAVE_FUNCTION_ERROR_INJECTION
109 select HAVE_FUNCTION_GRAPH_TRACER
110 select HAVE_FUNCTION_TRACER if !XIP_KERNEL
111 select HAVE_GCC_PLUGINS
112 select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
113 select HAVE_IRQ_TIME_ACCOUNTING
114 select HAVE_KERNEL_GZIP
115 select HAVE_KERNEL_LZ4
116 select HAVE_KERNEL_LZMA
117 select HAVE_KERNEL_LZO
118 select HAVE_KERNEL_XZ
119 select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
120 select HAVE_KRETPROBES if HAVE_KPROBES
121 select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if (LD_VERSION >= 23600 || LD_IS_LLD)
122 select HAVE_MOD_ARCH_SPECIFIC
123 select HAVE_NMI
124 select HAVE_OPTPROBES if !THUMB2_KERNEL
125 select HAVE_PAGE_SIZE_4KB
126 select HAVE_PCI if MMU
127 select HAVE_PERF_EVENTS
128 select HAVE_PERF_REGS
129 select HAVE_PERF_USER_STACK_DUMP
130 select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
131 select HAVE_REGS_AND_STACK_ACCESS_API
132 select HAVE_RSEQ
133 select HAVE_STACKPROTECTOR
134 select HAVE_SYSCALL_TRACEPOINTS
135 select HAVE_UID16
136 select HAVE_VIRT_CPU_ACCOUNTING_GEN
137 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
138 select IRQ_FORCED_THREADING
139 select LOCK_MM_AND_FIND_VMA
140 select MODULES_USE_ELF_REL
141 select NEED_DMA_MAP_STATE
142 select OF_EARLY_FLATTREE if OF
143 select OLD_SIGACTION
144 select OLD_SIGSUSPEND3
145 select PCI_DOMAINS_GENERIC if PCI
146 select PCI_SYSCALL if PCI
147 select PERF_USE_VMALLOC
148 select RTC_LIB
149 select SPARSE_IRQ if !(ARCH_FOOTBRIDGE || ARCH_RPC)
150 select SYS_SUPPORTS_APM_EMULATION
151 select THREAD_INFO_IN_TASK
152 select TIMER_OF if OF
153 select HAVE_ARCH_VMAP_STACK if MMU && ARM_HAS_GROUP_RELOCS
154 select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
155 select USE_OF if !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
156 # Above selects are sorted alphabetically; please add new ones
157 # according to that. Thanks.
158 help
159 The ARM series is a line of low-power-consumption RISC chip designs
160 licensed by ARM Ltd and targeted at embedded applications and
161 handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
162 manufactured, but legacy ARM-based PC hardware remains popular in
163 Europe. There is an ARM Linux project with a web page at
164 <http://www.arm.linux.org.uk/>.
165
166config ARM_HAS_GROUP_RELOCS
167 def_bool y
168 depends on !LD_IS_LLD || LLD_VERSION >= 140000
169 depends on !COMPILE_TEST
170 help
171 Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
172 relocations, which have been around for a long time, but were not
173 supported in LLD until version 14. The combined range is -/+ 256 MiB,
174 which is usually sufficient, but not for allyesconfig, so we disable
175 this feature when doing compile testing.
176
177config ARM_DMA_USE_IOMMU
178 bool
179 select NEED_SG_DMA_LENGTH
180
181if ARM_DMA_USE_IOMMU
182
183config ARM_DMA_IOMMU_ALIGNMENT
184 int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
185 range 4 9
186 default 8
187 help
188 DMA mapping framework by default aligns all buffers to the smallest
189 PAGE_SIZE order which is greater than or equal to the requested buffer
190 size. This works well for buffers up to a few hundreds kilobytes, but
191 for larger buffers it just a waste of address space. Drivers which has
192 relatively small addressing window (like 64Mib) might run out of
193 virtual space with just a few allocations.
194
195 With this parameter you can specify the maximum PAGE_SIZE order for
196 DMA IOMMU buffers. Larger buffers will be aligned only to this
197 specified order. The order is expressed as a power of two multiplied
198 by the PAGE_SIZE.
199
200endif
201
202config SYS_SUPPORTS_APM_EMULATION
203 bool
204
205config HAVE_TCM
206 bool
207 select GENERIC_ALLOCATOR
208
209config HAVE_PROC_CPU
210 bool
211
212config NO_IOPORT_MAP
213 bool
214
215config SBUS
216 bool
217
218config STACKTRACE_SUPPORT
219 bool
220 default y
221
222config LOCKDEP_SUPPORT
223 bool
224 default y
225
226config ARCH_HAS_ILOG2_U32
227 bool
228
229config ARCH_HAS_ILOG2_U64
230 bool
231
232config ARCH_HAS_BANDGAP
233 bool
234
235config FIX_EARLYCON_MEM
236 def_bool y if MMU
237
238config GENERIC_HWEIGHT
239 bool
240 default y
241
242config GENERIC_CALIBRATE_DELAY
243 bool
244 default y
245
246config ARCH_MAY_HAVE_PC_FDC
247 bool
248
249config ARCH_SUPPORTS_UPROBES
250 def_bool y
251
252config GENERIC_ISA_DMA
253 bool
254
255config FIQ
256 bool
257
258config ARCH_MTD_XIP
259 bool
260
261config ARM_PATCH_PHYS_VIRT
262 bool "Patch physical to virtual translations at runtime" if !ARCH_MULTIPLATFORM
263 default y
264 depends on MMU
265 help
266 Patch phys-to-virt and virt-to-phys translation functions at
267 boot and module load time according to the position of the
268 kernel in system memory.
269
270 This can only be used with non-XIP MMU kernels where the base
271 of physical memory is at a 2 MiB boundary.
272
273 Only disable this option if you know that you do not require
274 this feature (eg, building a kernel for a single machine) and
275 you need to shrink the kernel to the minimal size.
276
277config NEED_MACH_IO_H
278 bool
279 help
280 Select this when mach/io.h is required to provide special
281 definitions for this platform. The need for mach/io.h should
282 be avoided when possible.
283
284config NEED_MACH_MEMORY_H
285 bool
286 help
287 Select this when mach/memory.h is required to provide special
288 definitions for this platform. The need for mach/memory.h should
289 be avoided when possible.
290
291config PHYS_OFFSET
292 hex "Physical address of main memory" if MMU
293 depends on !ARM_PATCH_PHYS_VIRT || !AUTO_ZRELADDR
294 default DRAM_BASE if !MMU
295 default 0x00000000 if ARCH_FOOTBRIDGE
296 default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
297 default 0xa0000000 if ARCH_PXA
298 default 0xc0000000 if ARCH_EP93XX || ARCH_SA1100
299 default 0
300 help
301 Please provide the physical address corresponding to the
302 location of main memory in your system.
303
304config GENERIC_BUG
305 def_bool y
306 depends on BUG
307
308config PGTABLE_LEVELS
309 int
310 default 3 if ARM_LPAE
311 default 2
312
313menu "System Type"
314
315config MMU
316 bool "MMU-based Paged Memory Management Support"
317 default y
318 help
319 Select if you want MMU-based virtualised addressing space
320 support by paged memory management. If unsure, say 'Y'.
321
322config ARM_SINGLE_ARMV7M
323 def_bool !MMU
324 select ARM_NVIC
325 select CPU_V7M
326 select NO_IOPORT_MAP
327
328config ARCH_MMAP_RND_BITS_MIN
329 default 8
330
331config ARCH_MMAP_RND_BITS_MAX
332 default 14 if PAGE_OFFSET=0x40000000
333 default 15 if PAGE_OFFSET=0x80000000
334 default 16
335
336config ARCH_MULTIPLATFORM
337 bool "Require kernel to be portable to multiple machines" if EXPERT
338 depends on MMU && !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
339 default y
340 help
341 In general, all Arm machines can be supported in a single
342 kernel image, covering either Armv4/v5 or Armv6/v7.
343
344 However, some configuration options require hardcoding machine
345 specific physical addresses or enable errata workarounds that may
346 break other machines.
347
348 Selecting N here allows using those options, including
349 DEBUG_UNCOMPRESS, XIP_KERNEL and ZBOOT_ROM. If unsure, say Y.
350
351source "arch/arm/Kconfig.platforms"
352
353#
354# This is sorted alphabetically by mach-* pathname. However, plat-*
355# Kconfigs may be included either alphabetically (according to the
356# plat- suffix) or along side the corresponding mach-* source.
357#
358source "arch/arm/mach-actions/Kconfig"
359
360source "arch/arm/mach-alpine/Kconfig"
361
362source "arch/arm/mach-artpec/Kconfig"
363
364source "arch/arm/mach-aspeed/Kconfig"
365
366source "arch/arm/mach-at91/Kconfig"
367
368source "arch/arm/mach-axxia/Kconfig"
369
370source "arch/arm/mach-bcm/Kconfig"
371
372source "arch/arm/mach-berlin/Kconfig"
373
374source "arch/arm/mach-clps711x/Kconfig"
375
376source "arch/arm/mach-davinci/Kconfig"
377
378source "arch/arm/mach-digicolor/Kconfig"
379
380source "arch/arm/mach-dove/Kconfig"
381
382source "arch/arm/mach-ep93xx/Kconfig"
383
384source "arch/arm/mach-exynos/Kconfig"
385
386source "arch/arm/mach-footbridge/Kconfig"
387
388source "arch/arm/mach-gemini/Kconfig"
389
390source "arch/arm/mach-highbank/Kconfig"
391
392source "arch/arm/mach-hisi/Kconfig"
393
394source "arch/arm/mach-hpe/Kconfig"
395
396source "arch/arm/mach-imx/Kconfig"
397
398source "arch/arm/mach-ixp4xx/Kconfig"
399
400source "arch/arm/mach-keystone/Kconfig"
401
402source "arch/arm/mach-lpc32xx/Kconfig"
403
404source "arch/arm/mach-mediatek/Kconfig"
405
406source "arch/arm/mach-meson/Kconfig"
407
408source "arch/arm/mach-milbeaut/Kconfig"
409
410source "arch/arm/mach-mmp/Kconfig"
411
412source "arch/arm/mach-mstar/Kconfig"
413
414source "arch/arm/mach-mv78xx0/Kconfig"
415
416source "arch/arm/mach-mvebu/Kconfig"
417
418source "arch/arm/mach-mxs/Kconfig"
419
420source "arch/arm/mach-nomadik/Kconfig"
421
422source "arch/arm/mach-npcm/Kconfig"
423
424source "arch/arm/mach-omap1/Kconfig"
425
426source "arch/arm/mach-omap2/Kconfig"
427
428source "arch/arm/mach-orion5x/Kconfig"
429
430source "arch/arm/mach-pxa/Kconfig"
431
432source "arch/arm/mach-qcom/Kconfig"
433
434source "arch/arm/mach-realtek/Kconfig"
435
436source "arch/arm/mach-rpc/Kconfig"
437
438source "arch/arm/mach-rockchip/Kconfig"
439
440source "arch/arm/mach-s3c/Kconfig"
441
442source "arch/arm/mach-s5pv210/Kconfig"
443
444source "arch/arm/mach-sa1100/Kconfig"
445
446source "arch/arm/mach-shmobile/Kconfig"
447
448source "arch/arm/mach-socfpga/Kconfig"
449
450source "arch/arm/mach-spear/Kconfig"
451
452source "arch/arm/mach-sti/Kconfig"
453
454source "arch/arm/mach-stm32/Kconfig"
455
456source "arch/arm/mach-sunxi/Kconfig"
457
458source "arch/arm/mach-tegra/Kconfig"
459
460source "arch/arm/mach-ux500/Kconfig"
461
462source "arch/arm/mach-versatile/Kconfig"
463
464source "arch/arm/mach-vt8500/Kconfig"
465
466source "arch/arm/mach-zynq/Kconfig"
467
468# ARMv7-M architecture
469config ARCH_LPC18XX
470 bool "NXP LPC18xx/LPC43xx"
471 depends on ARM_SINGLE_ARMV7M
472 select ARCH_HAS_RESET_CONTROLLER
473 select ARM_AMBA
474 select CLKSRC_LPC32XX
475 select PINCTRL
476 help
477 Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
478 high performance microcontrollers.
479
480config ARCH_MPS2
481 bool "ARM MPS2 platform"
482 depends on ARM_SINGLE_ARMV7M
483 select ARM_AMBA
484 select CLKSRC_MPS2
485 help
486 Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
487 with a range of available cores like Cortex-M3/M4/M7.
488
489 Please, note that depends which Application Note is used memory map
490 for the platform may vary, so adjustment of RAM base might be needed.
491
492# Definitions to make life easier
493config ARCH_ACORN
494 bool
495
496config PLAT_ORION
497 bool
498 select CLKSRC_MMIO
499 select GENERIC_IRQ_CHIP
500 select IRQ_DOMAIN
501
502config PLAT_ORION_LEGACY
503 bool
504 select PLAT_ORION
505
506config PLAT_VERSATILE
507 bool
508
509source "arch/arm/mm/Kconfig"
510
511config IWMMXT
512 bool "Enable iWMMXt support"
513 depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK
514 default y if PXA27x || PXA3xx || ARCH_MMP
515 help
516 Enable support for iWMMXt context switching at run time if
517 running on a CPU that supports it.
518
519if !MMU
520source "arch/arm/Kconfig-nommu"
521endif
522
523config PJ4B_ERRATA_4742
524 bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
525 depends on CPU_PJ4B && MACH_ARMADA_370
526 default y
527 help
528 When coming out of either a Wait for Interrupt (WFI) or a Wait for
529 Event (WFE) IDLE states, a specific timing sensitivity exists between
530 the retiring WFI/WFE instructions and the newly issued subsequent
531 instructions. This sensitivity can result in a CPU hang scenario.
532 Workaround:
533 The software must insert either a Data Synchronization Barrier (DSB)
534 or Data Memory Barrier (DMB) command immediately after the WFI/WFE
535 instruction
536
537config ARM_ERRATA_326103
538 bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
539 depends on CPU_V6
540 help
541 Executing a SWP instruction to read-only memory does not set bit 11
542 of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
543 treat the access as a read, preventing a COW from occurring and
544 causing the faulting task to livelock.
545
546config ARM_ERRATA_411920
547 bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
548 depends on CPU_V6 || CPU_V6K
549 help
550 Invalidation of the Instruction Cache operation can
551 fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
552 It does not affect the MPCore. This option enables the ARM Ltd.
553 recommended workaround.
554
555config ARM_ERRATA_430973
556 bool "ARM errata: Stale prediction on replaced interworking branch"
557 depends on CPU_V7
558 help
559 This option enables the workaround for the 430973 Cortex-A8
560 r1p* erratum. If a code sequence containing an ARM/Thumb
561 interworking branch is replaced with another code sequence at the
562 same virtual address, whether due to self-modifying code or virtual
563 to physical address re-mapping, Cortex-A8 does not recover from the
564 stale interworking branch prediction. This results in Cortex-A8
565 executing the new code sequence in the incorrect ARM or Thumb state.
566 The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
567 and also flushes the branch target cache at every context switch.
568 Note that setting specific bits in the ACTLR register may not be
569 available in non-secure mode.
570
571config ARM_ERRATA_458693
572 bool "ARM errata: Processor deadlock when a false hazard is created"
573 depends on CPU_V7
574 depends on !ARCH_MULTIPLATFORM
575 help
576 This option enables the workaround for the 458693 Cortex-A8 (r2p0)
577 erratum. For very specific sequences of memory operations, it is
578 possible for a hazard condition intended for a cache line to instead
579 be incorrectly associated with a different cache line. This false
580 hazard might then cause a processor deadlock. The workaround enables
581 the L1 caching of the NEON accesses and disables the PLD instruction
582 in the ACTLR register. Note that setting specific bits in the ACTLR
583 register may not be available in non-secure mode and thus is not
584 available on a multiplatform kernel. This should be applied by the
585 bootloader instead.
586
587config ARM_ERRATA_460075
588 bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
589 depends on CPU_V7
590 depends on !ARCH_MULTIPLATFORM
591 help
592 This option enables the workaround for the 460075 Cortex-A8 (r2p0)
593 erratum. Any asynchronous access to the L2 cache may encounter a
594 situation in which recent store transactions to the L2 cache are lost
595 and overwritten with stale memory contents from external memory. The
596 workaround disables the write-allocate mode for the L2 cache via the
597 ACTLR register. Note that setting specific bits in the ACTLR register
598 may not be available in non-secure mode and thus is not available on
599 a multiplatform kernel. This should be applied by the bootloader
600 instead.
601
602config ARM_ERRATA_742230
603 bool "ARM errata: DMB operation may be faulty"
604 depends on CPU_V7 && SMP
605 depends on !ARCH_MULTIPLATFORM
606 help
607 This option enables the workaround for the 742230 Cortex-A9
608 (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
609 between two write operations may not ensure the correct visibility
610 ordering of the two writes. This workaround sets a specific bit in
611 the diagnostic register of the Cortex-A9 which causes the DMB
612 instruction to behave as a DSB, ensuring the correct behaviour of
613 the two writes. Note that setting specific bits in the diagnostics
614 register may not be available in non-secure mode and thus is not
615 available on a multiplatform kernel. This should be applied by the
616 bootloader instead.
617
618config ARM_ERRATA_742231
619 bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
620 depends on CPU_V7 && SMP
621 depends on !ARCH_MULTIPLATFORM
622 help
623 This option enables the workaround for the 742231 Cortex-A9
624 (r2p0..r2p2) erratum. Under certain conditions, specific to the
625 Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
626 accessing some data located in the same cache line, may get corrupted
627 data due to bad handling of the address hazard when the line gets
628 replaced from one of the CPUs at the same time as another CPU is
629 accessing it. This workaround sets specific bits in the diagnostic
630 register of the Cortex-A9 which reduces the linefill issuing
631 capabilities of the processor. Note that setting specific bits in the
632 diagnostics register may not be available in non-secure mode and thus
633 is not available on a multiplatform kernel. This should be applied by
634 the bootloader instead.
635
636config ARM_ERRATA_643719
637 bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
638 depends on CPU_V7 && SMP
639 default y
640 help
641 This option enables the workaround for the 643719 Cortex-A9 (prior to
642 r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
643 register returns zero when it should return one. The workaround
644 corrects this value, ensuring cache maintenance operations which use
645 it behave as intended and avoiding data corruption.
646
647config ARM_ERRATA_720789
648 bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
649 depends on CPU_V7
650 help
651 This option enables the workaround for the 720789 Cortex-A9 (prior to
652 r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
653 broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
654 As a consequence of this erratum, some TLB entries which should be
655 invalidated are not, resulting in an incoherency in the system page
656 tables. The workaround changes the TLB flushing routines to invalidate
657 entries regardless of the ASID.
658
659config ARM_ERRATA_743622
660 bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
661 depends on CPU_V7
662 depends on !ARCH_MULTIPLATFORM
663 help
664 This option enables the workaround for the 743622 Cortex-A9
665 (r2p*) erratum. Under very rare conditions, a faulty
666 optimisation in the Cortex-A9 Store Buffer may lead to data
667 corruption. This workaround sets a specific bit in the diagnostic
668 register of the Cortex-A9 which disables the Store Buffer
669 optimisation, preventing the defect from occurring. This has no
670 visible impact on the overall performance or power consumption of the
671 processor. Note that setting specific bits in the diagnostics register
672 may not be available in non-secure mode and thus is not available on a
673 multiplatform kernel. This should be applied by the bootloader instead.
674
675config ARM_ERRATA_751472
676 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
677 depends on CPU_V7
678 depends on !ARCH_MULTIPLATFORM
679 help
680 This option enables the workaround for the 751472 Cortex-A9 (prior
681 to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
682 completion of a following broadcasted operation if the second
683 operation is received by a CPU before the ICIALLUIS has completed,
684 potentially leading to corrupted entries in the cache or TLB.
685 Note that setting specific bits in the diagnostics register may
686 not be available in non-secure mode and thus is not available on
687 a multiplatform kernel. This should be applied by the bootloader
688 instead.
689
690config ARM_ERRATA_754322
691 bool "ARM errata: possible faulty MMU translations following an ASID switch"
692 depends on CPU_V7
693 help
694 This option enables the workaround for the 754322 Cortex-A9 (r2p*,
695 r3p*) erratum. A speculative memory access may cause a page table walk
696 which starts prior to an ASID switch but completes afterwards. This
697 can populate the micro-TLB with a stale entry which may be hit with
698 the new ASID. This workaround places two dsb instructions in the mm
699 switching code so that no page table walks can cross the ASID switch.
700
701config ARM_ERRATA_754327
702 bool "ARM errata: no automatic Store Buffer drain"
703 depends on CPU_V7 && SMP
704 help
705 This option enables the workaround for the 754327 Cortex-A9 (prior to
706 r2p0) erratum. The Store Buffer does not have any automatic draining
707 mechanism and therefore a livelock may occur if an external agent
708 continuously polls a memory location waiting to observe an update.
709 This workaround defines cpu_relax() as smp_mb(), preventing correctly
710 written polling loops from denying visibility of updates to memory.
711
712config ARM_ERRATA_364296
713 bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
714 depends on CPU_V6
715 help
716 This options enables the workaround for the 364296 ARM1136
717 r0p2 erratum (possible cache data corruption with
718 hit-under-miss enabled). It sets the undocumented bit 31 in
719 the auxiliary control register and the FI bit in the control
720 register, thus disabling hit-under-miss without putting the
721 processor into full low interrupt latency mode. ARM11MPCore
722 is not affected.
723
724config ARM_ERRATA_764369
725 bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
726 depends on CPU_V7 && SMP
727 help
728 This option enables the workaround for erratum 764369
729 affecting Cortex-A9 MPCore with two or more processors (all
730 current revisions). Under certain timing circumstances, a data
731 cache line maintenance operation by MVA targeting an Inner
732 Shareable memory region may fail to proceed up to either the
733 Point of Coherency or to the Point of Unification of the
734 system. This workaround adds a DSB instruction before the
735 relevant cache maintenance functions and sets a specific bit
736 in the diagnostic control register of the SCU.
737
738config ARM_ERRATA_764319
739 bool "ARM errata: Read to DBGPRSR and DBGOSLSR may generate Undefined instruction"
740 depends on CPU_V7
741 help
742 This option enables the workaround for the 764319 Cortex-A9 erratum.
743 CP14 read accesses to the DBGPRSR and DBGOSLSR registers generate an
744 unexpected Undefined Instruction exception when the DBGSWENABLE
745 external pin is set to 0, even when the CP14 accesses are performed
746 from a privileged mode. This work around catches the exception in a
747 way the kernel does not stop execution.
748
749config ARM_ERRATA_775420
750 bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
751 depends on CPU_V7
752 help
753 This option enables the workaround for the 775420 Cortex-A9 (r2p2,
754 r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
755 operation aborts with MMU exception, it might cause the processor
756 to deadlock. This workaround puts DSB before executing ISB if
757 an abort may occur on cache maintenance.
758
759config ARM_ERRATA_798181
760 bool "ARM errata: TLBI/DSB failure on Cortex-A15"
761 depends on CPU_V7 && SMP
762 help
763 On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
764 adequately shooting down all use of the old entries. This
765 option enables the Linux kernel workaround for this erratum
766 which sends an IPI to the CPUs that are running the same ASID
767 as the one being invalidated.
768
769config ARM_ERRATA_773022
770 bool "ARM errata: incorrect instructions may be executed from loop buffer"
771 depends on CPU_V7
772 help
773 This option enables the workaround for the 773022 Cortex-A15
774 (up to r0p4) erratum. In certain rare sequences of code, the
775 loop buffer may deliver incorrect instructions. This
776 workaround disables the loop buffer to avoid the erratum.
777
778config ARM_ERRATA_818325_852422
779 bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
780 depends on CPU_V7
781 help
782 This option enables the workaround for:
783 - Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
784 instruction might deadlock. Fixed in r0p1.
785 - Cortex-A12 852422: Execution of a sequence of instructions might
786 lead to either a data corruption or a CPU deadlock. Not fixed in
787 any Cortex-A12 cores yet.
788 This workaround for all both errata involves setting bit[12] of the
789 Feature Register. This bit disables an optimisation applied to a
790 sequence of 2 instructions that use opposing condition codes.
791
792config ARM_ERRATA_821420
793 bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
794 depends on CPU_V7
795 help
796 This option enables the workaround for the 821420 Cortex-A12
797 (all revs) erratum. In very rare timing conditions, a sequence
798 of VMOV to Core registers instructions, for which the second
799 one is in the shadow of a branch or abort, can lead to a
800 deadlock when the VMOV instructions are issued out-of-order.
801
802config ARM_ERRATA_825619
803 bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
804 depends on CPU_V7
805 help
806 This option enables the workaround for the 825619 Cortex-A12
807 (all revs) erratum. Within rare timing constraints, executing a
808 DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
809 and Device/Strongly-Ordered loads and stores might cause deadlock
810
811config ARM_ERRATA_857271
812 bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
813 depends on CPU_V7
814 help
815 This option enables the workaround for the 857271 Cortex-A12
816 (all revs) erratum. Under very rare timing conditions, the CPU might
817 hang. The workaround is expected to have a < 1% performance impact.
818
819config ARM_ERRATA_852421
820 bool "ARM errata: A17: DMB ST might fail to create order between stores"
821 depends on CPU_V7
822 help
823 This option enables the workaround for the 852421 Cortex-A17
824 (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
825 execution of a DMB ST instruction might fail to properly order
826 stores from GroupA and stores from GroupB.
827
828config ARM_ERRATA_852423
829 bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
830 depends on CPU_V7
831 help
832 This option enables the workaround for:
833 - Cortex-A17 852423: Execution of a sequence of instructions might
834 lead to either a data corruption or a CPU deadlock. Not fixed in
835 any Cortex-A17 cores yet.
836 This is identical to Cortex-A12 erratum 852422. It is a separate
837 config option from the A12 erratum due to the way errata are checked
838 for and handled.
839
840config ARM_ERRATA_857272
841 bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
842 depends on CPU_V7
843 help
844 This option enables the workaround for the 857272 Cortex-A17 erratum.
845 This erratum is not known to be fixed in any A17 revision.
846 This is identical to Cortex-A12 erratum 857271. It is a separate
847 config option from the A12 erratum due to the way errata are checked
848 for and handled.
849
850endmenu
851
852source "arch/arm/common/Kconfig"
853
854menu "Bus support"
855
856config ISA
857 bool
858 help
859 Find out whether you have ISA slots on your motherboard. ISA is the
860 name of a bus system, i.e. the way the CPU talks to the other stuff
861 inside your box. Other bus systems are PCI, EISA, MicroChannel
862 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
863 newer boards don't support it. If you have ISA, say Y, otherwise N.
864
865# Select ISA DMA interface
866config ISA_DMA_API
867 bool
868
869config ARM_ERRATA_814220
870 bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
871 depends on CPU_V7
872 help
873 The v7 ARM states that all cache and branch predictor maintenance
874 operations that do not specify an address execute, relative to
875 each other, in program order.
876 However, because of this erratum, an L2 set/way cache maintenance
877 operation can overtake an L1 set/way cache maintenance operation.
878 This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
879 r0p4, r0p5.
880
881endmenu
882
883menu "Kernel Features"
884
885config HAVE_SMP
886 bool
887 help
888 This option should be selected by machines which have an SMP-
889 capable CPU.
890
891 The only effect of this option is to make the SMP-related
892 options available to the user for configuration.
893
894config SMP
895 bool "Symmetric Multi-Processing"
896 depends on CPU_V6K || CPU_V7
897 depends on HAVE_SMP
898 depends on MMU || ARM_MPU
899 select IRQ_WORK
900 help
901 This enables support for systems with more than one CPU. If you have
902 a system with only one CPU, say N. If you have a system with more
903 than one CPU, say Y.
904
905 If you say N here, the kernel will run on uni- and multiprocessor
906 machines, but will use only one CPU of a multiprocessor machine. If
907 you say Y here, the kernel will run on many, but not all,
908 uniprocessor machines. On a uniprocessor machine, the kernel
909 will run faster if you say N here.
910
911 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
912 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
913 <http://tldp.org/HOWTO/SMP-HOWTO.html>.
914
915 If you don't know what to do here, say N.
916
917config SMP_ON_UP
918 bool "Allow booting SMP kernel on uniprocessor systems"
919 depends on SMP && MMU
920 default y
921 help
922 SMP kernels contain instructions which fail on non-SMP processors.
923 Enabling this option allows the kernel to modify itself to make
924 these instructions safe. Disabling it allows about 1K of space
925 savings.
926
927 If you don't know what to do here, say Y.
928
929
930config CURRENT_POINTER_IN_TPIDRURO
931 def_bool y
932 depends on CPU_32v6K && !CPU_V6
933
934config IRQSTACKS
935 def_bool y
936 select HAVE_IRQ_EXIT_ON_IRQ_STACK
937 select HAVE_SOFTIRQ_ON_OWN_STACK
938
939config ARM_CPU_TOPOLOGY
940 bool "Support cpu topology definition"
941 depends on SMP && CPU_V7
942 default y
943 help
944 Support ARM cpu topology definition. The MPIDR register defines
945 affinity between processors which is then used to describe the cpu
946 topology of an ARM System.
947
948config SCHED_MC
949 bool "Multi-core scheduler support"
950 depends on ARM_CPU_TOPOLOGY
951 help
952 Multi-core scheduler support improves the CPU scheduler's decision
953 making when dealing with multi-core CPU chips at a cost of slightly
954 increased overhead in some places. If unsure say N here.
955
956config SCHED_SMT
957 bool "SMT scheduler support"
958 depends on ARM_CPU_TOPOLOGY
959 help
960 Improves the CPU scheduler's decision making when dealing with
961 MultiThreading at a cost of slightly increased overhead in some
962 places. If unsure say N here.
963
964config HAVE_ARM_SCU
965 bool
966 help
967 This option enables support for the ARM snoop control unit
968
969config HAVE_ARM_ARCH_TIMER
970 bool "Architected timer support"
971 depends on CPU_V7
972 select ARM_ARCH_TIMER
973 help
974 This option enables support for the ARM architected timer
975
976config HAVE_ARM_TWD
977 bool
978 help
979 This options enables support for the ARM timer and watchdog unit
980
981config MCPM
982 bool "Multi-Cluster Power Management"
983 depends on CPU_V7 && SMP
984 help
985 This option provides the common power management infrastructure
986 for (multi-)cluster based systems, such as big.LITTLE based
987 systems.
988
989config MCPM_QUAD_CLUSTER
990 bool
991 depends on MCPM
992 help
993 To avoid wasting resources unnecessarily, MCPM only supports up
994 to 2 clusters by default.
995 Platforms with 3 or 4 clusters that use MCPM must select this
996 option to allow the additional clusters to be managed.
997
998config BIG_LITTLE
999 bool "big.LITTLE support (Experimental)"
1000 depends on CPU_V7 && SMP
1001 select MCPM
1002 help
1003 This option enables support selections for the big.LITTLE
1004 system architecture.
1005
1006config BL_SWITCHER
1007 bool "big.LITTLE switcher support"
1008 depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
1009 select CPU_PM
1010 help
1011 The big.LITTLE "switcher" provides the core functionality to
1012 transparently handle transition between a cluster of A15's
1013 and a cluster of A7's in a big.LITTLE system.
1014
1015config BL_SWITCHER_DUMMY_IF
1016 tristate "Simple big.LITTLE switcher user interface"
1017 depends on BL_SWITCHER && DEBUG_KERNEL
1018 help
1019 This is a simple and dummy char dev interface to control
1020 the big.LITTLE switcher core code. It is meant for
1021 debugging purposes only.
1022
1023choice
1024 prompt "Memory split"
1025 depends on MMU
1026 default VMSPLIT_3G
1027 help
1028 Select the desired split between kernel and user memory.
1029
1030 If you are not absolutely sure what you are doing, leave this
1031 option alone!
1032
1033 config VMSPLIT_3G
1034 bool "3G/1G user/kernel split"
1035 config VMSPLIT_3G_OPT
1036 depends on !ARM_LPAE
1037 bool "3G/1G user/kernel split (for full 1G low memory)"
1038 config VMSPLIT_2G
1039 bool "2G/2G user/kernel split"
1040 config VMSPLIT_1G
1041 bool "1G/3G user/kernel split"
1042endchoice
1043
1044config PAGE_OFFSET
1045 hex
1046 default PHYS_OFFSET if !MMU
1047 default 0x40000000 if VMSPLIT_1G
1048 default 0x80000000 if VMSPLIT_2G
1049 default 0xB0000000 if VMSPLIT_3G_OPT
1050 default 0xC0000000
1051
1052config KASAN_SHADOW_OFFSET
1053 hex
1054 depends on KASAN
1055 default 0x1f000000 if PAGE_OFFSET=0x40000000
1056 default 0x5f000000 if PAGE_OFFSET=0x80000000
1057 default 0x9f000000 if PAGE_OFFSET=0xC0000000
1058 default 0x8f000000 if PAGE_OFFSET=0xB0000000
1059 default 0xffffffff
1060
1061config NR_CPUS
1062 int "Maximum number of CPUs (2-32)"
1063 range 2 16 if DEBUG_KMAP_LOCAL
1064 range 2 32 if !DEBUG_KMAP_LOCAL
1065 depends on SMP
1066 default "4"
1067 help
1068 The maximum number of CPUs that the kernel can support.
1069 Up to 32 CPUs can be supported, or up to 16 if kmap_local()
1070 debugging is enabled, which uses half of the per-CPU fixmap
1071 slots as guard regions.
1072
1073config HOTPLUG_CPU
1074 bool "Support for hot-pluggable CPUs"
1075 depends on SMP
1076 select GENERIC_IRQ_MIGRATION
1077 help
1078 Say Y here to experiment with turning CPUs off and on. CPUs
1079 can be controlled through /sys/devices/system/cpu.
1080
1081config ARM_PSCI
1082 bool "Support for the ARM Power State Coordination Interface (PSCI)"
1083 depends on HAVE_ARM_SMCCC
1084 select ARM_PSCI_FW
1085 help
1086 Say Y here if you want Linux to communicate with system firmware
1087 implementing the PSCI specification for CPU-centric power
1088 management operations described in ARM document number ARM DEN
1089 0022A ("Power State Coordination Interface System Software on
1090 ARM processors").
1091
1092config HZ_FIXED
1093 int
1094 default 128 if SOC_AT91RM9200
1095 default 0
1096
1097choice
1098 depends on HZ_FIXED = 0
1099 prompt "Timer frequency"
1100
1101config HZ_100
1102 bool "100 Hz"
1103
1104config HZ_200
1105 bool "200 Hz"
1106
1107config HZ_250
1108 bool "250 Hz"
1109
1110config HZ_300
1111 bool "300 Hz"
1112
1113config HZ_500
1114 bool "500 Hz"
1115
1116config HZ_1000
1117 bool "1000 Hz"
1118
1119endchoice
1120
1121config HZ
1122 int
1123 default HZ_FIXED if HZ_FIXED != 0
1124 default 100 if HZ_100
1125 default 200 if HZ_200
1126 default 250 if HZ_250
1127 default 300 if HZ_300
1128 default 500 if HZ_500
1129 default 1000
1130
1131config SCHED_HRTICK
1132 def_bool HIGH_RES_TIMERS
1133
1134config THUMB2_KERNEL
1135 bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
1136 depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
1137 default y if CPU_THUMBONLY
1138 select ARM_UNWIND
1139 help
1140 By enabling this option, the kernel will be compiled in
1141 Thumb-2 mode.
1142
1143 If unsure, say N.
1144
1145config ARM_PATCH_IDIV
1146 bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
1147 depends on CPU_32v7
1148 default y
1149 help
1150 The ARM compiler inserts calls to __aeabi_idiv() and
1151 __aeabi_uidiv() when it needs to perform division on signed
1152 and unsigned integers. Some v7 CPUs have support for the sdiv
1153 and udiv instructions that can be used to implement those
1154 functions.
1155
1156 Enabling this option allows the kernel to modify itself to
1157 replace the first two instructions of these library functions
1158 with the sdiv or udiv plus "bx lr" instructions when the CPU
1159 it is running on supports them. Typically this will be faster
1160 and less power intensive than running the original library
1161 code to do integer division.
1162
1163config AEABI
1164 bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
1165 !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
1166 default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
1167 help
1168 This option allows for the kernel to be compiled using the latest
1169 ARM ABI (aka EABI). This is only useful if you are using a user
1170 space environment that is also compiled with EABI.
1171
1172 Since there are major incompatibilities between the legacy ABI and
1173 EABI, especially with regard to structure member alignment, this
1174 option also changes the kernel syscall calling convention to
1175 disambiguate both ABIs and allow for backward compatibility support
1176 (selected with CONFIG_OABI_COMPAT).
1177
1178 To use this you need GCC version 4.0.0 or later.
1179
1180config OABI_COMPAT
1181 bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
1182 depends on AEABI && !THUMB2_KERNEL
1183 help
1184 This option preserves the old syscall interface along with the
1185 new (ARM EABI) one. It also provides a compatibility layer to
1186 intercept syscalls that have structure arguments which layout
1187 in memory differs between the legacy ABI and the new ARM EABI
1188 (only for non "thumb" binaries). This option adds a tiny
1189 overhead to all syscalls and produces a slightly larger kernel.
1190
1191 The seccomp filter system will not be available when this is
1192 selected, since there is no way yet to sensibly distinguish
1193 between calling conventions during filtering.
1194
1195 If you know you'll be using only pure EABI user space then you
1196 can say N here. If this option is not selected and you attempt
1197 to execute a legacy ABI binary then the result will be
1198 UNPREDICTABLE (in fact it can be predicted that it won't work
1199 at all). If in doubt say N.
1200
1201config ARCH_SELECT_MEMORY_MODEL
1202 def_bool y
1203
1204config ARCH_FLATMEM_ENABLE
1205 def_bool !(ARCH_RPC || ARCH_SA1100)
1206
1207config ARCH_SPARSEMEM_ENABLE
1208 def_bool !ARCH_FOOTBRIDGE
1209 select SPARSEMEM_STATIC if SPARSEMEM
1210
1211config HIGHMEM
1212 bool "High Memory Support"
1213 depends on MMU
1214 select KMAP_LOCAL
1215 select KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1216 help
1217 The address space of ARM processors is only 4 Gigabytes large
1218 and it has to accommodate user address space, kernel address
1219 space as well as some memory mapped IO. That means that, if you
1220 have a large amount of physical memory and/or IO, not all of the
1221 memory can be "permanently mapped" by the kernel. The physical
1222 memory that is not permanently mapped is called "high memory".
1223
1224 Depending on the selected kernel/user memory split, minimum
1225 vmalloc space and actual amount of RAM, you may not need this
1226 option which should result in a slightly faster kernel.
1227
1228 If unsure, say n.
1229
1230config HIGHPTE
1231 bool "Allocate 2nd-level pagetables from highmem" if EXPERT
1232 depends on HIGHMEM
1233 default y
1234 help
1235 The VM uses one page of physical memory for each page table.
1236 For systems with a lot of processes, this can use a lot of
1237 precious low memory, eventually leading to low memory being
1238 consumed by page tables. Setting this option will allow
1239 user-space 2nd level page tables to reside in high memory.
1240
1241config ARM_PAN
1242 bool "Enable privileged no-access"
1243 depends on MMU
1244 default y
1245 help
1246 Increase kernel security by ensuring that normal kernel accesses
1247 are unable to access userspace addresses. This can help prevent
1248 use-after-free bugs becoming an exploitable privilege escalation
1249 by ensuring that magic values (such as LIST_POISON) will always
1250 fault when dereferenced.
1251
1252 The implementation uses CPU domains when !CONFIG_ARM_LPAE and
1253 disabling of TTBR0 page table walks with CONFIG_ARM_LPAE.
1254
1255config CPU_SW_DOMAIN_PAN
1256 def_bool y
1257 depends on ARM_PAN && !ARM_LPAE
1258 help
1259 Enable use of CPU domains to implement privileged no-access.
1260
1261 CPUs with low-vector mappings use a best-efforts implementation.
1262 Their lower 1MB needs to remain accessible for the vectors, but
1263 the remainder of userspace will become appropriately inaccessible.
1264
1265config CPU_TTBR0_PAN
1266 def_bool y
1267 depends on ARM_PAN && ARM_LPAE
1268 help
1269 Enable privileged no-access by disabling TTBR0 page table walks when
1270 running in kernel mode.
1271
1272config HW_PERF_EVENTS
1273 def_bool y
1274 depends on ARM_PMU
1275
1276config ARM_MODULE_PLTS
1277 bool "Use PLTs to allow module memory to spill over into vmalloc area"
1278 depends on MODULES
1279 select KASAN_VMALLOC if KASAN
1280 default y
1281 help
1282 Allocate PLTs when loading modules so that jumps and calls whose
1283 targets are too far away for their relative offsets to be encoded
1284 in the instructions themselves can be bounced via veneers in the
1285 module's PLT. This allows modules to be allocated in the generic
1286 vmalloc area after the dedicated module memory area has been
1287 exhausted. The modules will use slightly more memory, but after
1288 rounding up to page size, the actual memory footprint is usually
1289 the same.
1290
1291 Disabling this is usually safe for small single-platform
1292 configurations. If unsure, say y.
1293
1294config ARCH_FORCE_MAX_ORDER
1295 int "Order of maximal physically contiguous allocations"
1296 default "11" if SOC_AM33XX
1297 default "8" if SA1111
1298 default "10"
1299 help
1300 The kernel page allocator limits the size of maximal physically
1301 contiguous allocations. The limit is called MAX_PAGE_ORDER and it
1302 defines the maximal power of two of number of pages that can be
1303 allocated as a single contiguous block. This option allows
1304 overriding the default setting when ability to allocate very
1305 large blocks of physically contiguous memory is required.
1306
1307 Don't change if unsure.
1308
1309config ALIGNMENT_TRAP
1310 def_bool CPU_CP15_MMU
1311 select HAVE_PROC_CPU if PROC_FS
1312 help
1313 ARM processors cannot fetch/store information which is not
1314 naturally aligned on the bus, i.e., a 4 byte fetch must start at an
1315 address divisible by 4. On 32-bit ARM processors, these non-aligned
1316 fetch/store instructions will be emulated in software if you say
1317 here, which has a severe performance impact. This is necessary for
1318 correct operation of some network protocols. With an IP-only
1319 configuration it is safe to say N, otherwise say Y.
1320
1321config UACCESS_WITH_MEMCPY
1322 bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
1323 depends on MMU
1324 default y if CPU_FEROCEON
1325 help
1326 Implement faster copy_to_user and clear_user methods for CPU
1327 cores where a 8-word STM instruction give significantly higher
1328 memory write throughput than a sequence of individual 32bit stores.
1329
1330 A possible side effect is a slight increase in scheduling latency
1331 between threads sharing the same address space if they invoke
1332 such copy operations with large buffers.
1333
1334 However, if the CPU data cache is using a write-allocate mode,
1335 this option is unlikely to provide any performance gain.
1336
1337config PARAVIRT
1338 bool "Enable paravirtualization code"
1339 help
1340 This changes the kernel so it can modify itself when it is run
1341 under a hypervisor, potentially improving performance significantly
1342 over full virtualization.
1343
1344config PARAVIRT_TIME_ACCOUNTING
1345 bool "Paravirtual steal time accounting"
1346 select PARAVIRT
1347 help
1348 Select this option to enable fine granularity task steal time
1349 accounting. Time spent executing other tasks in parallel with
1350 the current vCPU is discounted from the vCPU power. To account for
1351 that, there can be a small performance impact.
1352
1353 If in doubt, say N here.
1354
1355config XEN_DOM0
1356 def_bool y
1357 depends on XEN
1358
1359config XEN
1360 bool "Xen guest support on ARM"
1361 depends on ARM && AEABI && OF
1362 depends on CPU_V7 && !CPU_V6
1363 depends on !GENERIC_ATOMIC64
1364 depends on MMU
1365 select ARCH_DMA_ADDR_T_64BIT
1366 select ARM_PSCI
1367 select SWIOTLB
1368 select SWIOTLB_XEN
1369 select PARAVIRT
1370 help
1371 Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
1372
1373config CC_HAVE_STACKPROTECTOR_TLS
1374 def_bool $(cc-option,-mtp=cp15 -mstack-protector-guard=tls -mstack-protector-guard-offset=0)
1375
1376config STACKPROTECTOR_PER_TASK
1377 bool "Use a unique stack canary value for each task"
1378 depends on STACKPROTECTOR && CURRENT_POINTER_IN_TPIDRURO && !XIP_DEFLATED_DATA
1379 depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS
1380 select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS
1381 default y
1382 help
1383 Due to the fact that GCC uses an ordinary symbol reference from
1384 which to load the value of the stack canary, this value can only
1385 change at reboot time on SMP systems, and all tasks running in the
1386 kernel's address space are forced to use the same canary value for
1387 the entire duration that the system is up.
1388
1389 Enable this option to switch to a different method that uses a
1390 different canary value for each task.
1391
1392endmenu
1393
1394menu "Boot options"
1395
1396config USE_OF
1397 bool "Flattened Device Tree support"
1398 select IRQ_DOMAIN
1399 select OF
1400 help
1401 Include support for flattened device tree machine descriptions.
1402
1403config ARCH_WANT_FLAT_DTB_INSTALL
1404 def_bool y
1405
1406config ATAGS
1407 bool "Support for the traditional ATAGS boot data passing"
1408 default y
1409 help
1410 This is the traditional way of passing data to the kernel at boot
1411 time. If you are solely relying on the flattened device tree (or
1412 the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
1413 to remove ATAGS support from your kernel binary.
1414
1415config DEPRECATED_PARAM_STRUCT
1416 bool "Provide old way to pass kernel parameters"
1417 depends on ATAGS
1418 help
1419 This was deprecated in 2001 and announced to live on for 5 years.
1420 Some old boot loaders still use this way.
1421
1422# Compressed boot loader in ROM. Yes, we really want to ask about
1423# TEXT and BSS so we preserve their values in the config files.
1424config ZBOOT_ROM_TEXT
1425 hex "Compressed ROM boot loader base address"
1426 default 0x0
1427 help
1428 The physical address at which the ROM-able zImage is to be
1429 placed in the target. Platforms which normally make use of
1430 ROM-able zImage formats normally set this to a suitable
1431 value in their defconfig file.
1432
1433 If ZBOOT_ROM is not enabled, this has no effect.
1434
1435config ZBOOT_ROM_BSS
1436 hex "Compressed ROM boot loader BSS address"
1437 default 0x0
1438 help
1439 The base address of an area of read/write memory in the target
1440 for the ROM-able zImage which must be available while the
1441 decompressor is running. It must be large enough to hold the
1442 entire decompressed kernel plus an additional 128 KiB.
1443 Platforms which normally make use of ROM-able zImage formats
1444 normally set this to a suitable value in their defconfig file.
1445
1446 If ZBOOT_ROM is not enabled, this has no effect.
1447
1448config ZBOOT_ROM
1449 bool "Compressed boot loader in ROM/flash"
1450 depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
1451 depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
1452 help
1453 Say Y here if you intend to execute your compressed kernel image
1454 (zImage) directly from ROM or flash. If unsure, say N.
1455
1456config ARM_APPENDED_DTB
1457 bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
1458 depends on OF
1459 help
1460 With this option, the boot code will look for a device tree binary
1461 (DTB) appended to zImage
1462 (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
1463
1464 This is meant as a backward compatibility convenience for those
1465 systems with a bootloader that can't be upgraded to accommodate
1466 the documented boot protocol using a device tree.
1467
1468 Beware that there is very little in terms of protection against
1469 this option being confused by leftover garbage in memory that might
1470 look like a DTB header after a reboot if no actual DTB is appended
1471 to zImage. Do not leave this option active in a production kernel
1472 if you don't intend to always append a DTB. Proper passing of the
1473 location into r2 of a bootloader provided DTB is always preferable
1474 to this option.
1475
1476config ARM_ATAG_DTB_COMPAT
1477 bool "Supplement the appended DTB with traditional ATAG information"
1478 depends on ARM_APPENDED_DTB
1479 help
1480 Some old bootloaders can't be updated to a DTB capable one, yet
1481 they provide ATAGs with memory configuration, the ramdisk address,
1482 the kernel cmdline string, etc. Such information is dynamically
1483 provided by the bootloader and can't always be stored in a static
1484 DTB. To allow a device tree enabled kernel to be used with such
1485 bootloaders, this option allows zImage to extract the information
1486 from the ATAG list and store it at run time into the appended DTB.
1487
1488choice
1489 prompt "Kernel command line type"
1490 depends on ARM_ATAG_DTB_COMPAT
1491 default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1492
1493config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1494 bool "Use bootloader kernel arguments if available"
1495 help
1496 Uses the command-line options passed by the boot loader instead of
1497 the device tree bootargs property. If the boot loader doesn't provide
1498 any, the device tree bootargs property will be used.
1499
1500config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
1501 bool "Extend with bootloader kernel arguments"
1502 help
1503 The command-line arguments provided by the boot loader will be
1504 appended to the the device tree bootargs property.
1505
1506endchoice
1507
1508config CMDLINE
1509 string "Default kernel command string"
1510 default ""
1511 help
1512 On some architectures (e.g. CATS), there is currently no way
1513 for the boot loader to pass arguments to the kernel. For these
1514 architectures, you should supply some command-line options at build
1515 time by entering them here. As a minimum, you should specify the
1516 memory size and the root device (e.g., mem=64M root=/dev/nfs).
1517
1518choice
1519 prompt "Kernel command line type"
1520 depends on CMDLINE != ""
1521 default CMDLINE_FROM_BOOTLOADER
1522
1523config CMDLINE_FROM_BOOTLOADER
1524 bool "Use bootloader kernel arguments if available"
1525 help
1526 Uses the command-line options passed by the boot loader. If
1527 the boot loader doesn't provide any, the default kernel command
1528 string provided in CMDLINE will be used.
1529
1530config CMDLINE_EXTEND
1531 bool "Extend bootloader kernel arguments"
1532 help
1533 The command-line arguments provided by the boot loader will be
1534 appended to the default kernel command string.
1535
1536config CMDLINE_FORCE
1537 bool "Always use the default kernel command string"
1538 help
1539 Always use the default kernel command string, even if the boot
1540 loader passes other arguments to the kernel.
1541 This is useful if you cannot or don't want to change the
1542 command-line options your boot loader passes to the kernel.
1543endchoice
1544
1545config XIP_KERNEL
1546 bool "Kernel Execute-In-Place from ROM"
1547 depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
1548 depends on !ARM_PATCH_IDIV && !ARM_PATCH_PHYS_VIRT && !SMP_ON_UP
1549 help
1550 Execute-In-Place allows the kernel to run from non-volatile storage
1551 directly addressable by the CPU, such as NOR flash. This saves RAM
1552 space since the text section of the kernel is not loaded from flash
1553 to RAM. Read-write sections, such as the data section and stack,
1554 are still copied to RAM. The XIP kernel is not compressed since
1555 it has to run directly from flash, so it will take more space to
1556 store it. The flash address used to link the kernel object files,
1557 and for storing it, is configuration dependent. Therefore, if you
1558 say Y here, you must know the proper physical address where to
1559 store the kernel image depending on your own flash memory usage.
1560
1561 Also note that the make target becomes "make xipImage" rather than
1562 "make zImage" or "make Image". The final kernel binary to put in
1563 ROM memory will be arch/arm/boot/xipImage.
1564
1565 If unsure, say N.
1566
1567config XIP_PHYS_ADDR
1568 hex "XIP Kernel Physical Location"
1569 depends on XIP_KERNEL
1570 default "0x00080000"
1571 help
1572 This is the physical address in your flash memory the kernel will
1573 be linked for and stored to. This address is dependent on your
1574 own flash usage.
1575
1576config XIP_DEFLATED_DATA
1577 bool "Store kernel .data section compressed in ROM"
1578 depends on XIP_KERNEL
1579 select ZLIB_INFLATE
1580 help
1581 Before the kernel is actually executed, its .data section has to be
1582 copied to RAM from ROM. This option allows for storing that data
1583 in compressed form and decompressed to RAM rather than merely being
1584 copied, saving some precious ROM space. A possible drawback is a
1585 slightly longer boot delay.
1586
1587config ARCH_SUPPORTS_KEXEC
1588 def_bool (!SMP || PM_SLEEP_SMP) && MMU
1589
1590config ATAGS_PROC
1591 bool "Export atags in procfs"
1592 depends on ATAGS && KEXEC
1593 default y
1594 help
1595 Should the atags used to boot the kernel be exported in an "atags"
1596 file in procfs. Useful with kexec.
1597
1598config ARCH_SUPPORTS_CRASH_DUMP
1599 def_bool y
1600
1601config ARCH_DEFAULT_CRASH_DUMP
1602 def_bool y
1603
1604config AUTO_ZRELADDR
1605 bool "Auto calculation of the decompressed kernel image address" if !ARCH_MULTIPLATFORM
1606 default !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
1607 help
1608 ZRELADDR is the physical address where the decompressed kernel
1609 image will be placed. If AUTO_ZRELADDR is selected, the address
1610 will be determined at run-time, either by masking the current IP
1611 with 0xf8000000, or, if invalid, from the DTB passed in r2.
1612 This assumes the zImage being placed in the first 128MB from
1613 start of memory.
1614
1615config EFI_STUB
1616 bool
1617
1618config EFI
1619 bool "UEFI runtime support"
1620 depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
1621 select UCS2_STRING
1622 select EFI_PARAMS_FROM_FDT
1623 select EFI_STUB
1624 select EFI_GENERIC_STUB
1625 select EFI_RUNTIME_WRAPPERS
1626 help
1627 This option provides support for runtime services provided
1628 by UEFI firmware (such as non-volatile variables, realtime
1629 clock, and platform reset). A UEFI stub is also provided to
1630 allow the kernel to be booted as an EFI application. This
1631 is only useful for kernels that may run on systems that have
1632 UEFI firmware.
1633
1634config DMI
1635 bool "Enable support for SMBIOS (DMI) tables"
1636 depends on EFI
1637 default y
1638 help
1639 This enables SMBIOS/DMI feature for systems.
1640
1641 This option is only useful on systems that have UEFI firmware.
1642 However, even with this option, the resultant kernel should
1643 continue to boot on existing non-UEFI platforms.
1644
1645 NOTE: This does *NOT* enable or encourage the use of DMI quirks,
1646 i.e., the the practice of identifying the platform via DMI to
1647 decide whether certain workarounds for buggy hardware and/or
1648 firmware need to be enabled. This would require the DMI subsystem
1649 to be enabled much earlier than we do on ARM, which is non-trivial.
1650
1651endmenu
1652
1653menu "CPU Power Management"
1654
1655source "drivers/cpufreq/Kconfig"
1656
1657source "drivers/cpuidle/Kconfig"
1658
1659endmenu
1660
1661menu "Floating point emulation"
1662
1663comment "At least one emulation must be selected"
1664
1665config FPE_NWFPE
1666 bool "NWFPE math emulation"
1667 depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
1668 help
1669 Say Y to include the NWFPE floating point emulator in the kernel.
1670 This is necessary to run most binaries. Linux does not currently
1671 support floating point hardware so you need to say Y here even if
1672 your machine has an FPA or floating point co-processor podule.
1673
1674 You may say N here if you are going to load the Acorn FPEmulator
1675 early in the bootup.
1676
1677config FPE_NWFPE_XP
1678 bool "Support extended precision"
1679 depends on FPE_NWFPE
1680 help
1681 Say Y to include 80-bit support in the kernel floating-point
1682 emulator. Otherwise, only 32 and 64-bit support is compiled in.
1683 Note that gcc does not generate 80-bit operations by default,
1684 so in most cases this option only enlarges the size of the
1685 floating point emulator without any good reason.
1686
1687 You almost surely want to say N here.
1688
1689config FPE_FASTFPE
1690 bool "FastFPE math emulation (EXPERIMENTAL)"
1691 depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
1692 help
1693 Say Y here to include the FAST floating point emulator in the kernel.
1694 This is an experimental much faster emulator which now also has full
1695 precision for the mantissa. It does not support any exceptions.
1696 It is very simple, and approximately 3-6 times faster than NWFPE.
1697
1698 It should be sufficient for most programs. It may be not suitable
1699 for scientific calculations, but you have to check this for yourself.
1700 If you do not feel you need a faster FP emulation you should better
1701 choose NWFPE.
1702
1703config VFP
1704 bool "VFP-format floating point maths"
1705 depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
1706 help
1707 Say Y to include VFP support code in the kernel. This is needed
1708 if your hardware includes a VFP unit.
1709
1710 Please see <file:Documentation/arch/arm/vfp/release-notes.rst> for
1711 release notes and additional status information.
1712
1713 Say N if your target does not have VFP hardware.
1714
1715config VFPv3
1716 bool
1717 depends on VFP
1718 default y if CPU_V7
1719
1720config NEON
1721 bool "Advanced SIMD (NEON) Extension support"
1722 depends on VFPv3 && CPU_V7
1723 help
1724 Say Y to include support code for NEON, the ARMv7 Advanced SIMD
1725 Extension.
1726
1727config KERNEL_MODE_NEON
1728 bool "Support for NEON in kernel mode"
1729 depends on NEON && AEABI
1730 help
1731 Say Y to include support for NEON in kernel mode.
1732
1733endmenu
1734
1735menu "Power management options"
1736
1737source "kernel/power/Kconfig"
1738
1739config ARCH_SUSPEND_POSSIBLE
1740 depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
1741 CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
1742 def_bool y
1743
1744config ARM_CPU_SUSPEND
1745 def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
1746 depends on ARCH_SUSPEND_POSSIBLE
1747
1748config ARCH_HIBERNATION_POSSIBLE
1749 bool
1750 depends on MMU
1751 default y if ARCH_SUSPEND_POSSIBLE
1752
1753endmenu
1754
1755source "arch/arm/Kconfig.assembler"
1# SPDX-License-Identifier: GPL-2.0
2config ARM
3 bool
4 default y
5 select ARCH_32BIT_OFF_T
6 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE if HAVE_KRETPROBES && FRAME_POINTER && !ARM_UNWIND
7 select ARCH_HAS_BINFMT_FLAT
8 select ARCH_HAS_CPU_FINALIZE_INIT if MMU
9 select ARCH_HAS_CURRENT_STACK_POINTER
10 select ARCH_HAS_DEBUG_VIRTUAL if MMU
11 select ARCH_HAS_DMA_ALLOC if MMU
12 select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
13 select ARCH_HAS_ELF_RANDOMIZE
14 select ARCH_HAS_FORTIFY_SOURCE
15 select ARCH_HAS_KEEPINITRD
16 select ARCH_HAS_KCOV
17 select ARCH_HAS_MEMBARRIER_SYNC_CORE
18 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
19 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
20 select ARCH_HAS_SETUP_DMA_OPS
21 select ARCH_HAS_SET_MEMORY
22 select ARCH_STACKWALK
23 select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
24 select ARCH_HAS_STRICT_MODULE_RWX if MMU
25 select ARCH_HAS_SYNC_DMA_FOR_DEVICE
26 select ARCH_HAS_SYNC_DMA_FOR_CPU
27 select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
28 select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
29 select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
30 select ARCH_HAS_GCOV_PROFILE_ALL
31 select ARCH_KEEP_MEMBLOCK
32 select ARCH_HAS_UBSAN_SANITIZE_ALL
33 select ARCH_MIGHT_HAVE_PC_PARPORT
34 select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
35 select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
36 select ARCH_SUPPORTS_ATOMIC_RMW
37 select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
38 select ARCH_SUPPORTS_PER_VMA_LOCK
39 select ARCH_USE_BUILTIN_BSWAP
40 select ARCH_USE_CMPXCHG_LOCKREF
41 select ARCH_USE_MEMTEST
42 select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
43 select ARCH_WANT_GENERAL_HUGETLB
44 select ARCH_WANT_IPC_PARSE_VERSION
45 select ARCH_WANT_LD_ORPHAN_WARN
46 select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
47 select BUILDTIME_TABLE_SORT if MMU
48 select COMMON_CLK if !(ARCH_RPC || ARCH_FOOTBRIDGE)
49 select CLONE_BACKWARDS
50 select CPU_PM if SUSPEND || CPU_IDLE
51 select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
52 select DMA_DECLARE_COHERENT
53 select DMA_GLOBAL_POOL if !MMU
54 select DMA_OPS
55 select DMA_NONCOHERENT_MMAP if MMU
56 select EDAC_SUPPORT
57 select EDAC_ATOMIC_SCRUB
58 select GENERIC_ALLOCATOR
59 select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
60 select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
61 select GENERIC_CLOCKEVENTS_BROADCAST if SMP
62 select GENERIC_IRQ_IPI if SMP
63 select GENERIC_CPU_AUTOPROBE
64 select GENERIC_EARLY_IOREMAP
65 select GENERIC_IDLE_POLL_SETUP
66 select GENERIC_IRQ_MULTI_HANDLER
67 select GENERIC_IRQ_PROBE
68 select GENERIC_IRQ_SHOW
69 select GENERIC_IRQ_SHOW_LEVEL
70 select GENERIC_LIB_DEVMEM_IS_ALLOWED
71 select GENERIC_PCI_IOMAP
72 select GENERIC_SCHED_CLOCK
73 select GENERIC_SMP_IDLE_THREAD
74 select HARDIRQS_SW_RESEND
75 select HAS_IOPORT
76 select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
77 select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
78 select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
79 select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
80 select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
81 select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
82 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
83 select HAVE_ARCH_MMAP_RND_BITS if MMU
84 select HAVE_ARCH_PFN_VALID
85 select HAVE_ARCH_SECCOMP
86 select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
87 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
88 select HAVE_ARCH_TRACEHOOK
89 select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
90 select HAVE_ARM_SMCCC if CPU_V7
91 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
92 select HAVE_CONTEXT_TRACKING_USER
93 select HAVE_C_RECORDMCOUNT
94 select HAVE_BUILDTIME_MCOUNT_SORT
95 select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
96 select HAVE_DMA_CONTIGUOUS if MMU
97 select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
98 select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
99 select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
100 select HAVE_EXIT_THREAD
101 select HAVE_FAST_GUP if ARM_LPAE
102 select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
103 select HAVE_FUNCTION_ERROR_INJECTION
104 select HAVE_FUNCTION_GRAPH_TRACER
105 select HAVE_FUNCTION_TRACER if !XIP_KERNEL
106 select HAVE_GCC_PLUGINS
107 select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
108 select HAVE_IRQ_TIME_ACCOUNTING
109 select HAVE_KERNEL_GZIP
110 select HAVE_KERNEL_LZ4
111 select HAVE_KERNEL_LZMA
112 select HAVE_KERNEL_LZO
113 select HAVE_KERNEL_XZ
114 select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
115 select HAVE_KRETPROBES if HAVE_KPROBES
116 select HAVE_MOD_ARCH_SPECIFIC
117 select HAVE_NMI
118 select HAVE_OPTPROBES if !THUMB2_KERNEL
119 select HAVE_PCI if MMU
120 select HAVE_PERF_EVENTS
121 select HAVE_PERF_REGS
122 select HAVE_PERF_USER_STACK_DUMP
123 select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
124 select HAVE_REGS_AND_STACK_ACCESS_API
125 select HAVE_RSEQ
126 select HAVE_STACKPROTECTOR
127 select HAVE_SYSCALL_TRACEPOINTS
128 select HAVE_UID16
129 select HAVE_VIRT_CPU_ACCOUNTING_GEN
130 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
131 select IRQ_FORCED_THREADING
132 select LOCK_MM_AND_FIND_VMA
133 select MODULES_USE_ELF_REL
134 select NEED_DMA_MAP_STATE
135 select OF_EARLY_FLATTREE if OF
136 select OLD_SIGACTION
137 select OLD_SIGSUSPEND3
138 select PCI_DOMAINS_GENERIC if PCI
139 select PCI_SYSCALL if PCI
140 select PERF_USE_VMALLOC
141 select RTC_LIB
142 select SPARSE_IRQ if !(ARCH_FOOTBRIDGE || ARCH_RPC)
143 select SYS_SUPPORTS_APM_EMULATION
144 select THREAD_INFO_IN_TASK
145 select TIMER_OF if OF
146 select HAVE_ARCH_VMAP_STACK if MMU && ARM_HAS_GROUP_RELOCS
147 select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
148 select USE_OF if !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
149 # Above selects are sorted alphabetically; please add new ones
150 # according to that. Thanks.
151 help
152 The ARM series is a line of low-power-consumption RISC chip designs
153 licensed by ARM Ltd and targeted at embedded applications and
154 handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
155 manufactured, but legacy ARM-based PC hardware remains popular in
156 Europe. There is an ARM Linux project with a web page at
157 <http://www.arm.linux.org.uk/>.
158
159config ARM_HAS_GROUP_RELOCS
160 def_bool y
161 depends on !LD_IS_LLD || LLD_VERSION >= 140000
162 depends on !COMPILE_TEST
163 help
164 Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
165 relocations, which have been around for a long time, but were not
166 supported in LLD until version 14. The combined range is -/+ 256 MiB,
167 which is usually sufficient, but not for allyesconfig, so we disable
168 this feature when doing compile testing.
169
170config ARM_DMA_USE_IOMMU
171 bool
172 select NEED_SG_DMA_LENGTH
173
174if ARM_DMA_USE_IOMMU
175
176config ARM_DMA_IOMMU_ALIGNMENT
177 int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
178 range 4 9
179 default 8
180 help
181 DMA mapping framework by default aligns all buffers to the smallest
182 PAGE_SIZE order which is greater than or equal to the requested buffer
183 size. This works well for buffers up to a few hundreds kilobytes, but
184 for larger buffers it just a waste of address space. Drivers which has
185 relatively small addressing window (like 64Mib) might run out of
186 virtual space with just a few allocations.
187
188 With this parameter you can specify the maximum PAGE_SIZE order for
189 DMA IOMMU buffers. Larger buffers will be aligned only to this
190 specified order. The order is expressed as a power of two multiplied
191 by the PAGE_SIZE.
192
193endif
194
195config SYS_SUPPORTS_APM_EMULATION
196 bool
197
198config HAVE_TCM
199 bool
200 select GENERIC_ALLOCATOR
201
202config HAVE_PROC_CPU
203 bool
204
205config NO_IOPORT_MAP
206 bool
207
208config SBUS
209 bool
210
211config STACKTRACE_SUPPORT
212 bool
213 default y
214
215config LOCKDEP_SUPPORT
216 bool
217 default y
218
219config ARCH_HAS_ILOG2_U32
220 bool
221
222config ARCH_HAS_ILOG2_U64
223 bool
224
225config ARCH_HAS_BANDGAP
226 bool
227
228config FIX_EARLYCON_MEM
229 def_bool y if MMU
230
231config GENERIC_HWEIGHT
232 bool
233 default y
234
235config GENERIC_CALIBRATE_DELAY
236 bool
237 default y
238
239config ARCH_MAY_HAVE_PC_FDC
240 bool
241
242config ARCH_SUPPORTS_UPROBES
243 def_bool y
244
245config GENERIC_ISA_DMA
246 bool
247
248config FIQ
249 bool
250
251config ARCH_MTD_XIP
252 bool
253
254config ARM_PATCH_PHYS_VIRT
255 bool "Patch physical to virtual translations at runtime" if !ARCH_MULTIPLATFORM
256 default y
257 depends on MMU
258 help
259 Patch phys-to-virt and virt-to-phys translation functions at
260 boot and module load time according to the position of the
261 kernel in system memory.
262
263 This can only be used with non-XIP MMU kernels where the base
264 of physical memory is at a 2 MiB boundary.
265
266 Only disable this option if you know that you do not require
267 this feature (eg, building a kernel for a single machine) and
268 you need to shrink the kernel to the minimal size.
269
270config NEED_MACH_IO_H
271 bool
272 help
273 Select this when mach/io.h is required to provide special
274 definitions for this platform. The need for mach/io.h should
275 be avoided when possible.
276
277config NEED_MACH_MEMORY_H
278 bool
279 help
280 Select this when mach/memory.h is required to provide special
281 definitions for this platform. The need for mach/memory.h should
282 be avoided when possible.
283
284config PHYS_OFFSET
285 hex "Physical address of main memory" if MMU
286 depends on !ARM_PATCH_PHYS_VIRT || !AUTO_ZRELADDR
287 default DRAM_BASE if !MMU
288 default 0x00000000 if ARCH_FOOTBRIDGE
289 default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
290 default 0xa0000000 if ARCH_PXA
291 default 0xc0000000 if ARCH_EP93XX || ARCH_SA1100
292 default 0
293 help
294 Please provide the physical address corresponding to the
295 location of main memory in your system.
296
297config GENERIC_BUG
298 def_bool y
299 depends on BUG
300
301config PGTABLE_LEVELS
302 int
303 default 3 if ARM_LPAE
304 default 2
305
306menu "System Type"
307
308config MMU
309 bool "MMU-based Paged Memory Management Support"
310 default y
311 help
312 Select if you want MMU-based virtualised addressing space
313 support by paged memory management. If unsure, say 'Y'.
314
315config ARM_SINGLE_ARMV7M
316 def_bool !MMU
317 select ARM_NVIC
318 select CPU_V7M
319 select NO_IOPORT_MAP
320
321config ARCH_MMAP_RND_BITS_MIN
322 default 8
323
324config ARCH_MMAP_RND_BITS_MAX
325 default 14 if PAGE_OFFSET=0x40000000
326 default 15 if PAGE_OFFSET=0x80000000
327 default 16
328
329config ARCH_MULTIPLATFORM
330 bool "Require kernel to be portable to multiple machines" if EXPERT
331 depends on MMU && !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
332 default y
333 help
334 In general, all Arm machines can be supported in a single
335 kernel image, covering either Armv4/v5 or Armv6/v7.
336
337 However, some configuration options require hardcoding machine
338 specific physical addresses or enable errata workarounds that may
339 break other machines.
340
341 Selecting N here allows using those options, including
342 DEBUG_UNCOMPRESS, XIP_KERNEL and ZBOOT_ROM. If unsure, say Y.
343
344source "arch/arm/Kconfig.platforms"
345
346#
347# This is sorted alphabetically by mach-* pathname. However, plat-*
348# Kconfigs may be included either alphabetically (according to the
349# plat- suffix) or along side the corresponding mach-* source.
350#
351source "arch/arm/mach-actions/Kconfig"
352
353source "arch/arm/mach-alpine/Kconfig"
354
355source "arch/arm/mach-artpec/Kconfig"
356
357source "arch/arm/mach-aspeed/Kconfig"
358
359source "arch/arm/mach-at91/Kconfig"
360
361source "arch/arm/mach-axxia/Kconfig"
362
363source "arch/arm/mach-bcm/Kconfig"
364
365source "arch/arm/mach-berlin/Kconfig"
366
367source "arch/arm/mach-clps711x/Kconfig"
368
369source "arch/arm/mach-davinci/Kconfig"
370
371source "arch/arm/mach-digicolor/Kconfig"
372
373source "arch/arm/mach-dove/Kconfig"
374
375source "arch/arm/mach-ep93xx/Kconfig"
376
377source "arch/arm/mach-exynos/Kconfig"
378
379source "arch/arm/mach-footbridge/Kconfig"
380
381source "arch/arm/mach-gemini/Kconfig"
382
383source "arch/arm/mach-highbank/Kconfig"
384
385source "arch/arm/mach-hisi/Kconfig"
386
387source "arch/arm/mach-hpe/Kconfig"
388
389source "arch/arm/mach-imx/Kconfig"
390
391source "arch/arm/mach-ixp4xx/Kconfig"
392
393source "arch/arm/mach-keystone/Kconfig"
394
395source "arch/arm/mach-lpc32xx/Kconfig"
396
397source "arch/arm/mach-mediatek/Kconfig"
398
399source "arch/arm/mach-meson/Kconfig"
400
401source "arch/arm/mach-milbeaut/Kconfig"
402
403source "arch/arm/mach-mmp/Kconfig"
404
405source "arch/arm/mach-mstar/Kconfig"
406
407source "arch/arm/mach-mv78xx0/Kconfig"
408
409source "arch/arm/mach-mvebu/Kconfig"
410
411source "arch/arm/mach-mxs/Kconfig"
412
413source "arch/arm/mach-nomadik/Kconfig"
414
415source "arch/arm/mach-npcm/Kconfig"
416
417source "arch/arm/mach-omap1/Kconfig"
418
419source "arch/arm/mach-omap2/Kconfig"
420
421source "arch/arm/mach-orion5x/Kconfig"
422
423source "arch/arm/mach-pxa/Kconfig"
424
425source "arch/arm/mach-qcom/Kconfig"
426
427source "arch/arm/mach-realtek/Kconfig"
428
429source "arch/arm/mach-rpc/Kconfig"
430
431source "arch/arm/mach-rockchip/Kconfig"
432
433source "arch/arm/mach-s3c/Kconfig"
434
435source "arch/arm/mach-s5pv210/Kconfig"
436
437source "arch/arm/mach-sa1100/Kconfig"
438
439source "arch/arm/mach-shmobile/Kconfig"
440
441source "arch/arm/mach-socfpga/Kconfig"
442
443source "arch/arm/mach-spear/Kconfig"
444
445source "arch/arm/mach-sti/Kconfig"
446
447source "arch/arm/mach-stm32/Kconfig"
448
449source "arch/arm/mach-sunxi/Kconfig"
450
451source "arch/arm/mach-tegra/Kconfig"
452
453source "arch/arm/mach-ux500/Kconfig"
454
455source "arch/arm/mach-versatile/Kconfig"
456
457source "arch/arm/mach-vt8500/Kconfig"
458
459source "arch/arm/mach-zynq/Kconfig"
460
461# ARMv7-M architecture
462config ARCH_LPC18XX
463 bool "NXP LPC18xx/LPC43xx"
464 depends on ARM_SINGLE_ARMV7M
465 select ARCH_HAS_RESET_CONTROLLER
466 select ARM_AMBA
467 select CLKSRC_LPC32XX
468 select PINCTRL
469 help
470 Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
471 high performance microcontrollers.
472
473config ARCH_MPS2
474 bool "ARM MPS2 platform"
475 depends on ARM_SINGLE_ARMV7M
476 select ARM_AMBA
477 select CLKSRC_MPS2
478 help
479 Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
480 with a range of available cores like Cortex-M3/M4/M7.
481
482 Please, note that depends which Application Note is used memory map
483 for the platform may vary, so adjustment of RAM base might be needed.
484
485# Definitions to make life easier
486config ARCH_ACORN
487 bool
488
489config PLAT_ORION
490 bool
491 select CLKSRC_MMIO
492 select GENERIC_IRQ_CHIP
493 select IRQ_DOMAIN
494
495config PLAT_ORION_LEGACY
496 bool
497 select PLAT_ORION
498
499config PLAT_VERSATILE
500 bool
501
502source "arch/arm/mm/Kconfig"
503
504config IWMMXT
505 bool "Enable iWMMXt support"
506 depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
507 default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B
508 help
509 Enable support for iWMMXt context switching at run time if
510 running on a CPU that supports it.
511
512if !MMU
513source "arch/arm/Kconfig-nommu"
514endif
515
516config PJ4B_ERRATA_4742
517 bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
518 depends on CPU_PJ4B && MACH_ARMADA_370
519 default y
520 help
521 When coming out of either a Wait for Interrupt (WFI) or a Wait for
522 Event (WFE) IDLE states, a specific timing sensitivity exists between
523 the retiring WFI/WFE instructions and the newly issued subsequent
524 instructions. This sensitivity can result in a CPU hang scenario.
525 Workaround:
526 The software must insert either a Data Synchronization Barrier (DSB)
527 or Data Memory Barrier (DMB) command immediately after the WFI/WFE
528 instruction
529
530config ARM_ERRATA_326103
531 bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
532 depends on CPU_V6
533 help
534 Executing a SWP instruction to read-only memory does not set bit 11
535 of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
536 treat the access as a read, preventing a COW from occurring and
537 causing the faulting task to livelock.
538
539config ARM_ERRATA_411920
540 bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
541 depends on CPU_V6 || CPU_V6K
542 help
543 Invalidation of the Instruction Cache operation can
544 fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
545 It does not affect the MPCore. This option enables the ARM Ltd.
546 recommended workaround.
547
548config ARM_ERRATA_430973
549 bool "ARM errata: Stale prediction on replaced interworking branch"
550 depends on CPU_V7
551 help
552 This option enables the workaround for the 430973 Cortex-A8
553 r1p* erratum. If a code sequence containing an ARM/Thumb
554 interworking branch is replaced with another code sequence at the
555 same virtual address, whether due to self-modifying code or virtual
556 to physical address re-mapping, Cortex-A8 does not recover from the
557 stale interworking branch prediction. This results in Cortex-A8
558 executing the new code sequence in the incorrect ARM or Thumb state.
559 The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
560 and also flushes the branch target cache at every context switch.
561 Note that setting specific bits in the ACTLR register may not be
562 available in non-secure mode.
563
564config ARM_ERRATA_458693
565 bool "ARM errata: Processor deadlock when a false hazard is created"
566 depends on CPU_V7
567 depends on !ARCH_MULTIPLATFORM
568 help
569 This option enables the workaround for the 458693 Cortex-A8 (r2p0)
570 erratum. For very specific sequences of memory operations, it is
571 possible for a hazard condition intended for a cache line to instead
572 be incorrectly associated with a different cache line. This false
573 hazard might then cause a processor deadlock. The workaround enables
574 the L1 caching of the NEON accesses and disables the PLD instruction
575 in the ACTLR register. Note that setting specific bits in the ACTLR
576 register may not be available in non-secure mode and thus is not
577 available on a multiplatform kernel. This should be applied by the
578 bootloader instead.
579
580config ARM_ERRATA_460075
581 bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
582 depends on CPU_V7
583 depends on !ARCH_MULTIPLATFORM
584 help
585 This option enables the workaround for the 460075 Cortex-A8 (r2p0)
586 erratum. Any asynchronous access to the L2 cache may encounter a
587 situation in which recent store transactions to the L2 cache are lost
588 and overwritten with stale memory contents from external memory. The
589 workaround disables the write-allocate mode for the L2 cache via the
590 ACTLR register. Note that setting specific bits in the ACTLR register
591 may not be available in non-secure mode and thus is not available on
592 a multiplatform kernel. This should be applied by the bootloader
593 instead.
594
595config ARM_ERRATA_742230
596 bool "ARM errata: DMB operation may be faulty"
597 depends on CPU_V7 && SMP
598 depends on !ARCH_MULTIPLATFORM
599 help
600 This option enables the workaround for the 742230 Cortex-A9
601 (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
602 between two write operations may not ensure the correct visibility
603 ordering of the two writes. This workaround sets a specific bit in
604 the diagnostic register of the Cortex-A9 which causes the DMB
605 instruction to behave as a DSB, ensuring the correct behaviour of
606 the two writes. Note that setting specific bits in the diagnostics
607 register may not be available in non-secure mode and thus is not
608 available on a multiplatform kernel. This should be applied by the
609 bootloader instead.
610
611config ARM_ERRATA_742231
612 bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
613 depends on CPU_V7 && SMP
614 depends on !ARCH_MULTIPLATFORM
615 help
616 This option enables the workaround for the 742231 Cortex-A9
617 (r2p0..r2p2) erratum. Under certain conditions, specific to the
618 Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
619 accessing some data located in the same cache line, may get corrupted
620 data due to bad handling of the address hazard when the line gets
621 replaced from one of the CPUs at the same time as another CPU is
622 accessing it. This workaround sets specific bits in the diagnostic
623 register of the Cortex-A9 which reduces the linefill issuing
624 capabilities of the processor. Note that setting specific bits in the
625 diagnostics register may not be available in non-secure mode and thus
626 is not available on a multiplatform kernel. This should be applied by
627 the bootloader instead.
628
629config ARM_ERRATA_643719
630 bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
631 depends on CPU_V7 && SMP
632 default y
633 help
634 This option enables the workaround for the 643719 Cortex-A9 (prior to
635 r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
636 register returns zero when it should return one. The workaround
637 corrects this value, ensuring cache maintenance operations which use
638 it behave as intended and avoiding data corruption.
639
640config ARM_ERRATA_720789
641 bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
642 depends on CPU_V7
643 help
644 This option enables the workaround for the 720789 Cortex-A9 (prior to
645 r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
646 broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
647 As a consequence of this erratum, some TLB entries which should be
648 invalidated are not, resulting in an incoherency in the system page
649 tables. The workaround changes the TLB flushing routines to invalidate
650 entries regardless of the ASID.
651
652config ARM_ERRATA_743622
653 bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
654 depends on CPU_V7
655 depends on !ARCH_MULTIPLATFORM
656 help
657 This option enables the workaround for the 743622 Cortex-A9
658 (r2p*) erratum. Under very rare conditions, a faulty
659 optimisation in the Cortex-A9 Store Buffer may lead to data
660 corruption. This workaround sets a specific bit in the diagnostic
661 register of the Cortex-A9 which disables the Store Buffer
662 optimisation, preventing the defect from occurring. This has no
663 visible impact on the overall performance or power consumption of the
664 processor. Note that setting specific bits in the diagnostics register
665 may not be available in non-secure mode and thus is not available on a
666 multiplatform kernel. This should be applied by the bootloader instead.
667
668config ARM_ERRATA_751472
669 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
670 depends on CPU_V7
671 depends on !ARCH_MULTIPLATFORM
672 help
673 This option enables the workaround for the 751472 Cortex-A9 (prior
674 to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
675 completion of a following broadcasted operation if the second
676 operation is received by a CPU before the ICIALLUIS has completed,
677 potentially leading to corrupted entries in the cache or TLB.
678 Note that setting specific bits in the diagnostics register may
679 not be available in non-secure mode and thus is not available on
680 a multiplatform kernel. This should be applied by the bootloader
681 instead.
682
683config ARM_ERRATA_754322
684 bool "ARM errata: possible faulty MMU translations following an ASID switch"
685 depends on CPU_V7
686 help
687 This option enables the workaround for the 754322 Cortex-A9 (r2p*,
688 r3p*) erratum. A speculative memory access may cause a page table walk
689 which starts prior to an ASID switch but completes afterwards. This
690 can populate the micro-TLB with a stale entry which may be hit with
691 the new ASID. This workaround places two dsb instructions in the mm
692 switching code so that no page table walks can cross the ASID switch.
693
694config ARM_ERRATA_754327
695 bool "ARM errata: no automatic Store Buffer drain"
696 depends on CPU_V7 && SMP
697 help
698 This option enables the workaround for the 754327 Cortex-A9 (prior to
699 r2p0) erratum. The Store Buffer does not have any automatic draining
700 mechanism and therefore a livelock may occur if an external agent
701 continuously polls a memory location waiting to observe an update.
702 This workaround defines cpu_relax() as smp_mb(), preventing correctly
703 written polling loops from denying visibility of updates to memory.
704
705config ARM_ERRATA_364296
706 bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
707 depends on CPU_V6
708 help
709 This options enables the workaround for the 364296 ARM1136
710 r0p2 erratum (possible cache data corruption with
711 hit-under-miss enabled). It sets the undocumented bit 31 in
712 the auxiliary control register and the FI bit in the control
713 register, thus disabling hit-under-miss without putting the
714 processor into full low interrupt latency mode. ARM11MPCore
715 is not affected.
716
717config ARM_ERRATA_764369
718 bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
719 depends on CPU_V7 && SMP
720 help
721 This option enables the workaround for erratum 764369
722 affecting Cortex-A9 MPCore with two or more processors (all
723 current revisions). Under certain timing circumstances, a data
724 cache line maintenance operation by MVA targeting an Inner
725 Shareable memory region may fail to proceed up to either the
726 Point of Coherency or to the Point of Unification of the
727 system. This workaround adds a DSB instruction before the
728 relevant cache maintenance functions and sets a specific bit
729 in the diagnostic control register of the SCU.
730
731config ARM_ERRATA_764319
732 bool "ARM errata: Read to DBGPRSR and DBGOSLSR may generate Undefined instruction"
733 depends on CPU_V7
734 help
735 This option enables the workaround for the 764319 Cortex A-9 erratum.
736 CP14 read accesses to the DBGPRSR and DBGOSLSR registers generate an
737 unexpected Undefined Instruction exception when the DBGSWENABLE
738 external pin is set to 0, even when the CP14 accesses are performed
739 from a privileged mode. This work around catches the exception in a
740 way the kernel does not stop execution.
741
742config ARM_ERRATA_775420
743 bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
744 depends on CPU_V7
745 help
746 This option enables the workaround for the 775420 Cortex-A9 (r2p2,
747 r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
748 operation aborts with MMU exception, it might cause the processor
749 to deadlock. This workaround puts DSB before executing ISB if
750 an abort may occur on cache maintenance.
751
752config ARM_ERRATA_798181
753 bool "ARM errata: TLBI/DSB failure on Cortex-A15"
754 depends on CPU_V7 && SMP
755 help
756 On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
757 adequately shooting down all use of the old entries. This
758 option enables the Linux kernel workaround for this erratum
759 which sends an IPI to the CPUs that are running the same ASID
760 as the one being invalidated.
761
762config ARM_ERRATA_773022
763 bool "ARM errata: incorrect instructions may be executed from loop buffer"
764 depends on CPU_V7
765 help
766 This option enables the workaround for the 773022 Cortex-A15
767 (up to r0p4) erratum. In certain rare sequences of code, the
768 loop buffer may deliver incorrect instructions. This
769 workaround disables the loop buffer to avoid the erratum.
770
771config ARM_ERRATA_818325_852422
772 bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
773 depends on CPU_V7
774 help
775 This option enables the workaround for:
776 - Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
777 instruction might deadlock. Fixed in r0p1.
778 - Cortex-A12 852422: Execution of a sequence of instructions might
779 lead to either a data corruption or a CPU deadlock. Not fixed in
780 any Cortex-A12 cores yet.
781 This workaround for all both errata involves setting bit[12] of the
782 Feature Register. This bit disables an optimisation applied to a
783 sequence of 2 instructions that use opposing condition codes.
784
785config ARM_ERRATA_821420
786 bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
787 depends on CPU_V7
788 help
789 This option enables the workaround for the 821420 Cortex-A12
790 (all revs) erratum. In very rare timing conditions, a sequence
791 of VMOV to Core registers instructions, for which the second
792 one is in the shadow of a branch or abort, can lead to a
793 deadlock when the VMOV instructions are issued out-of-order.
794
795config ARM_ERRATA_825619
796 bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
797 depends on CPU_V7
798 help
799 This option enables the workaround for the 825619 Cortex-A12
800 (all revs) erratum. Within rare timing constraints, executing a
801 DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
802 and Device/Strongly-Ordered loads and stores might cause deadlock
803
804config ARM_ERRATA_857271
805 bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
806 depends on CPU_V7
807 help
808 This option enables the workaround for the 857271 Cortex-A12
809 (all revs) erratum. Under very rare timing conditions, the CPU might
810 hang. The workaround is expected to have a < 1% performance impact.
811
812config ARM_ERRATA_852421
813 bool "ARM errata: A17: DMB ST might fail to create order between stores"
814 depends on CPU_V7
815 help
816 This option enables the workaround for the 852421 Cortex-A17
817 (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
818 execution of a DMB ST instruction might fail to properly order
819 stores from GroupA and stores from GroupB.
820
821config ARM_ERRATA_852423
822 bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
823 depends on CPU_V7
824 help
825 This option enables the workaround for:
826 - Cortex-A17 852423: Execution of a sequence of instructions might
827 lead to either a data corruption or a CPU deadlock. Not fixed in
828 any Cortex-A17 cores yet.
829 This is identical to Cortex-A12 erratum 852422. It is a separate
830 config option from the A12 erratum due to the way errata are checked
831 for and handled.
832
833config ARM_ERRATA_857272
834 bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
835 depends on CPU_V7
836 help
837 This option enables the workaround for the 857272 Cortex-A17 erratum.
838 This erratum is not known to be fixed in any A17 revision.
839 This is identical to Cortex-A12 erratum 857271. It is a separate
840 config option from the A12 erratum due to the way errata are checked
841 for and handled.
842
843endmenu
844
845source "arch/arm/common/Kconfig"
846
847menu "Bus support"
848
849config ISA
850 bool
851 help
852 Find out whether you have ISA slots on your motherboard. ISA is the
853 name of a bus system, i.e. the way the CPU talks to the other stuff
854 inside your box. Other bus systems are PCI, EISA, MicroChannel
855 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
856 newer boards don't support it. If you have ISA, say Y, otherwise N.
857
858# Select ISA DMA interface
859config ISA_DMA_API
860 bool
861
862config ARM_ERRATA_814220
863 bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
864 depends on CPU_V7
865 help
866 The v7 ARM states that all cache and branch predictor maintenance
867 operations that do not specify an address execute, relative to
868 each other, in program order.
869 However, because of this erratum, an L2 set/way cache maintenance
870 operation can overtake an L1 set/way cache maintenance operation.
871 This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
872 r0p4, r0p5.
873
874endmenu
875
876menu "Kernel Features"
877
878config HAVE_SMP
879 bool
880 help
881 This option should be selected by machines which have an SMP-
882 capable CPU.
883
884 The only effect of this option is to make the SMP-related
885 options available to the user for configuration.
886
887config SMP
888 bool "Symmetric Multi-Processing"
889 depends on CPU_V6K || CPU_V7
890 depends on HAVE_SMP
891 depends on MMU || ARM_MPU
892 select IRQ_WORK
893 help
894 This enables support for systems with more than one CPU. If you have
895 a system with only one CPU, say N. If you have a system with more
896 than one CPU, say Y.
897
898 If you say N here, the kernel will run on uni- and multiprocessor
899 machines, but will use only one CPU of a multiprocessor machine. If
900 you say Y here, the kernel will run on many, but not all,
901 uniprocessor machines. On a uniprocessor machine, the kernel
902 will run faster if you say N here.
903
904 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
905 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
906 <http://tldp.org/HOWTO/SMP-HOWTO.html>.
907
908 If you don't know what to do here, say N.
909
910config SMP_ON_UP
911 bool "Allow booting SMP kernel on uniprocessor systems"
912 depends on SMP && MMU
913 default y
914 help
915 SMP kernels contain instructions which fail on non-SMP processors.
916 Enabling this option allows the kernel to modify itself to make
917 these instructions safe. Disabling it allows about 1K of space
918 savings.
919
920 If you don't know what to do here, say Y.
921
922
923config CURRENT_POINTER_IN_TPIDRURO
924 def_bool y
925 depends on CPU_32v6K && !CPU_V6
926
927config IRQSTACKS
928 def_bool y
929 select HAVE_IRQ_EXIT_ON_IRQ_STACK
930 select HAVE_SOFTIRQ_ON_OWN_STACK
931
932config ARM_CPU_TOPOLOGY
933 bool "Support cpu topology definition"
934 depends on SMP && CPU_V7
935 default y
936 help
937 Support ARM cpu topology definition. The MPIDR register defines
938 affinity between processors which is then used to describe the cpu
939 topology of an ARM System.
940
941config SCHED_MC
942 bool "Multi-core scheduler support"
943 depends on ARM_CPU_TOPOLOGY
944 help
945 Multi-core scheduler support improves the CPU scheduler's decision
946 making when dealing with multi-core CPU chips at a cost of slightly
947 increased overhead in some places. If unsure say N here.
948
949config SCHED_SMT
950 bool "SMT scheduler support"
951 depends on ARM_CPU_TOPOLOGY
952 help
953 Improves the CPU scheduler's decision making when dealing with
954 MultiThreading at a cost of slightly increased overhead in some
955 places. If unsure say N here.
956
957config HAVE_ARM_SCU
958 bool
959 help
960 This option enables support for the ARM snoop control unit
961
962config HAVE_ARM_ARCH_TIMER
963 bool "Architected timer support"
964 depends on CPU_V7
965 select ARM_ARCH_TIMER
966 help
967 This option enables support for the ARM architected timer
968
969config HAVE_ARM_TWD
970 bool
971 help
972 This options enables support for the ARM timer and watchdog unit
973
974config MCPM
975 bool "Multi-Cluster Power Management"
976 depends on CPU_V7 && SMP
977 help
978 This option provides the common power management infrastructure
979 for (multi-)cluster based systems, such as big.LITTLE based
980 systems.
981
982config MCPM_QUAD_CLUSTER
983 bool
984 depends on MCPM
985 help
986 To avoid wasting resources unnecessarily, MCPM only supports up
987 to 2 clusters by default.
988 Platforms with 3 or 4 clusters that use MCPM must select this
989 option to allow the additional clusters to be managed.
990
991config BIG_LITTLE
992 bool "big.LITTLE support (Experimental)"
993 depends on CPU_V7 && SMP
994 select MCPM
995 help
996 This option enables support selections for the big.LITTLE
997 system architecture.
998
999config BL_SWITCHER
1000 bool "big.LITTLE switcher support"
1001 depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
1002 select CPU_PM
1003 help
1004 The big.LITTLE "switcher" provides the core functionality to
1005 transparently handle transition between a cluster of A15's
1006 and a cluster of A7's in a big.LITTLE system.
1007
1008config BL_SWITCHER_DUMMY_IF
1009 tristate "Simple big.LITTLE switcher user interface"
1010 depends on BL_SWITCHER && DEBUG_KERNEL
1011 help
1012 This is a simple and dummy char dev interface to control
1013 the big.LITTLE switcher core code. It is meant for
1014 debugging purposes only.
1015
1016choice
1017 prompt "Memory split"
1018 depends on MMU
1019 default VMSPLIT_3G
1020 help
1021 Select the desired split between kernel and user memory.
1022
1023 If you are not absolutely sure what you are doing, leave this
1024 option alone!
1025
1026 config VMSPLIT_3G
1027 bool "3G/1G user/kernel split"
1028 config VMSPLIT_3G_OPT
1029 depends on !ARM_LPAE
1030 bool "3G/1G user/kernel split (for full 1G low memory)"
1031 config VMSPLIT_2G
1032 bool "2G/2G user/kernel split"
1033 config VMSPLIT_1G
1034 bool "1G/3G user/kernel split"
1035endchoice
1036
1037config PAGE_OFFSET
1038 hex
1039 default PHYS_OFFSET if !MMU
1040 default 0x40000000 if VMSPLIT_1G
1041 default 0x80000000 if VMSPLIT_2G
1042 default 0xB0000000 if VMSPLIT_3G_OPT
1043 default 0xC0000000
1044
1045config KASAN_SHADOW_OFFSET
1046 hex
1047 depends on KASAN
1048 default 0x1f000000 if PAGE_OFFSET=0x40000000
1049 default 0x5f000000 if PAGE_OFFSET=0x80000000
1050 default 0x9f000000 if PAGE_OFFSET=0xC0000000
1051 default 0x8f000000 if PAGE_OFFSET=0xB0000000
1052 default 0xffffffff
1053
1054config NR_CPUS
1055 int "Maximum number of CPUs (2-32)"
1056 range 2 16 if DEBUG_KMAP_LOCAL
1057 range 2 32 if !DEBUG_KMAP_LOCAL
1058 depends on SMP
1059 default "4"
1060 help
1061 The maximum number of CPUs that the kernel can support.
1062 Up to 32 CPUs can be supported, or up to 16 if kmap_local()
1063 debugging is enabled, which uses half of the per-CPU fixmap
1064 slots as guard regions.
1065
1066config HOTPLUG_CPU
1067 bool "Support for hot-pluggable CPUs"
1068 depends on SMP
1069 select GENERIC_IRQ_MIGRATION
1070 help
1071 Say Y here to experiment with turning CPUs off and on. CPUs
1072 can be controlled through /sys/devices/system/cpu.
1073
1074config ARM_PSCI
1075 bool "Support for the ARM Power State Coordination Interface (PSCI)"
1076 depends on HAVE_ARM_SMCCC
1077 select ARM_PSCI_FW
1078 help
1079 Say Y here if you want Linux to communicate with system firmware
1080 implementing the PSCI specification for CPU-centric power
1081 management operations described in ARM document number ARM DEN
1082 0022A ("Power State Coordination Interface System Software on
1083 ARM processors").
1084
1085config HZ_FIXED
1086 int
1087 default 128 if SOC_AT91RM9200
1088 default 0
1089
1090choice
1091 depends on HZ_FIXED = 0
1092 prompt "Timer frequency"
1093
1094config HZ_100
1095 bool "100 Hz"
1096
1097config HZ_200
1098 bool "200 Hz"
1099
1100config HZ_250
1101 bool "250 Hz"
1102
1103config HZ_300
1104 bool "300 Hz"
1105
1106config HZ_500
1107 bool "500 Hz"
1108
1109config HZ_1000
1110 bool "1000 Hz"
1111
1112endchoice
1113
1114config HZ
1115 int
1116 default HZ_FIXED if HZ_FIXED != 0
1117 default 100 if HZ_100
1118 default 200 if HZ_200
1119 default 250 if HZ_250
1120 default 300 if HZ_300
1121 default 500 if HZ_500
1122 default 1000
1123
1124config SCHED_HRTICK
1125 def_bool HIGH_RES_TIMERS
1126
1127config THUMB2_KERNEL
1128 bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
1129 depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
1130 default y if CPU_THUMBONLY
1131 select ARM_UNWIND
1132 help
1133 By enabling this option, the kernel will be compiled in
1134 Thumb-2 mode.
1135
1136 If unsure, say N.
1137
1138config ARM_PATCH_IDIV
1139 bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
1140 depends on CPU_32v7
1141 default y
1142 help
1143 The ARM compiler inserts calls to __aeabi_idiv() and
1144 __aeabi_uidiv() when it needs to perform division on signed
1145 and unsigned integers. Some v7 CPUs have support for the sdiv
1146 and udiv instructions that can be used to implement those
1147 functions.
1148
1149 Enabling this option allows the kernel to modify itself to
1150 replace the first two instructions of these library functions
1151 with the sdiv or udiv plus "bx lr" instructions when the CPU
1152 it is running on supports them. Typically this will be faster
1153 and less power intensive than running the original library
1154 code to do integer division.
1155
1156config AEABI
1157 bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
1158 !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
1159 default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
1160 help
1161 This option allows for the kernel to be compiled using the latest
1162 ARM ABI (aka EABI). This is only useful if you are using a user
1163 space environment that is also compiled with EABI.
1164
1165 Since there are major incompatibilities between the legacy ABI and
1166 EABI, especially with regard to structure member alignment, this
1167 option also changes the kernel syscall calling convention to
1168 disambiguate both ABIs and allow for backward compatibility support
1169 (selected with CONFIG_OABI_COMPAT).
1170
1171 To use this you need GCC version 4.0.0 or later.
1172
1173config OABI_COMPAT
1174 bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
1175 depends on AEABI && !THUMB2_KERNEL
1176 help
1177 This option preserves the old syscall interface along with the
1178 new (ARM EABI) one. It also provides a compatibility layer to
1179 intercept syscalls that have structure arguments which layout
1180 in memory differs between the legacy ABI and the new ARM EABI
1181 (only for non "thumb" binaries). This option adds a tiny
1182 overhead to all syscalls and produces a slightly larger kernel.
1183
1184 The seccomp filter system will not be available when this is
1185 selected, since there is no way yet to sensibly distinguish
1186 between calling conventions during filtering.
1187
1188 If you know you'll be using only pure EABI user space then you
1189 can say N here. If this option is not selected and you attempt
1190 to execute a legacy ABI binary then the result will be
1191 UNPREDICTABLE (in fact it can be predicted that it won't work
1192 at all). If in doubt say N.
1193
1194config ARCH_SELECT_MEMORY_MODEL
1195 def_bool y
1196
1197config ARCH_FLATMEM_ENABLE
1198 def_bool !(ARCH_RPC || ARCH_SA1100)
1199
1200config ARCH_SPARSEMEM_ENABLE
1201 def_bool !ARCH_FOOTBRIDGE
1202 select SPARSEMEM_STATIC if SPARSEMEM
1203
1204config HIGHMEM
1205 bool "High Memory Support"
1206 depends on MMU
1207 select KMAP_LOCAL
1208 select KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1209 help
1210 The address space of ARM processors is only 4 Gigabytes large
1211 and it has to accommodate user address space, kernel address
1212 space as well as some memory mapped IO. That means that, if you
1213 have a large amount of physical memory and/or IO, not all of the
1214 memory can be "permanently mapped" by the kernel. The physical
1215 memory that is not permanently mapped is called "high memory".
1216
1217 Depending on the selected kernel/user memory split, minimum
1218 vmalloc space and actual amount of RAM, you may not need this
1219 option which should result in a slightly faster kernel.
1220
1221 If unsure, say n.
1222
1223config HIGHPTE
1224 bool "Allocate 2nd-level pagetables from highmem" if EXPERT
1225 depends on HIGHMEM
1226 default y
1227 help
1228 The VM uses one page of physical memory for each page table.
1229 For systems with a lot of processes, this can use a lot of
1230 precious low memory, eventually leading to low memory being
1231 consumed by page tables. Setting this option will allow
1232 user-space 2nd level page tables to reside in high memory.
1233
1234config CPU_SW_DOMAIN_PAN
1235 bool "Enable use of CPU domains to implement privileged no-access"
1236 depends on MMU && !ARM_LPAE
1237 default y
1238 help
1239 Increase kernel security by ensuring that normal kernel accesses
1240 are unable to access userspace addresses. This can help prevent
1241 use-after-free bugs becoming an exploitable privilege escalation
1242 by ensuring that magic values (such as LIST_POISON) will always
1243 fault when dereferenced.
1244
1245 CPUs with low-vector mappings use a best-efforts implementation.
1246 Their lower 1MB needs to remain accessible for the vectors, but
1247 the remainder of userspace will become appropriately inaccessible.
1248
1249config HW_PERF_EVENTS
1250 def_bool y
1251 depends on ARM_PMU
1252
1253config ARM_MODULE_PLTS
1254 bool "Use PLTs to allow module memory to spill over into vmalloc area"
1255 depends on MODULES
1256 select KASAN_VMALLOC if KASAN
1257 default y
1258 help
1259 Allocate PLTs when loading modules so that jumps and calls whose
1260 targets are too far away for their relative offsets to be encoded
1261 in the instructions themselves can be bounced via veneers in the
1262 module's PLT. This allows modules to be allocated in the generic
1263 vmalloc area after the dedicated module memory area has been
1264 exhausted. The modules will use slightly more memory, but after
1265 rounding up to page size, the actual memory footprint is usually
1266 the same.
1267
1268 Disabling this is usually safe for small single-platform
1269 configurations. If unsure, say y.
1270
1271config ARCH_FORCE_MAX_ORDER
1272 int "Order of maximal physically contiguous allocations"
1273 default "11" if SOC_AM33XX
1274 default "8" if SA1111
1275 default "10"
1276 help
1277 The kernel page allocator limits the size of maximal physically
1278 contiguous allocations. The limit is called MAX_PAGE_ORDER and it
1279 defines the maximal power of two of number of pages that can be
1280 allocated as a single contiguous block. This option allows
1281 overriding the default setting when ability to allocate very
1282 large blocks of physically contiguous memory is required.
1283
1284 Don't change if unsure.
1285
1286config ALIGNMENT_TRAP
1287 def_bool CPU_CP15_MMU
1288 select HAVE_PROC_CPU if PROC_FS
1289 help
1290 ARM processors cannot fetch/store information which is not
1291 naturally aligned on the bus, i.e., a 4 byte fetch must start at an
1292 address divisible by 4. On 32-bit ARM processors, these non-aligned
1293 fetch/store instructions will be emulated in software if you say
1294 here, which has a severe performance impact. This is necessary for
1295 correct operation of some network protocols. With an IP-only
1296 configuration it is safe to say N, otherwise say Y.
1297
1298config UACCESS_WITH_MEMCPY
1299 bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
1300 depends on MMU
1301 default y if CPU_FEROCEON
1302 help
1303 Implement faster copy_to_user and clear_user methods for CPU
1304 cores where a 8-word STM instruction give significantly higher
1305 memory write throughput than a sequence of individual 32bit stores.
1306
1307 A possible side effect is a slight increase in scheduling latency
1308 between threads sharing the same address space if they invoke
1309 such copy operations with large buffers.
1310
1311 However, if the CPU data cache is using a write-allocate mode,
1312 this option is unlikely to provide any performance gain.
1313
1314config PARAVIRT
1315 bool "Enable paravirtualization code"
1316 help
1317 This changes the kernel so it can modify itself when it is run
1318 under a hypervisor, potentially improving performance significantly
1319 over full virtualization.
1320
1321config PARAVIRT_TIME_ACCOUNTING
1322 bool "Paravirtual steal time accounting"
1323 select PARAVIRT
1324 help
1325 Select this option to enable fine granularity task steal time
1326 accounting. Time spent executing other tasks in parallel with
1327 the current vCPU is discounted from the vCPU power. To account for
1328 that, there can be a small performance impact.
1329
1330 If in doubt, say N here.
1331
1332config XEN_DOM0
1333 def_bool y
1334 depends on XEN
1335
1336config XEN
1337 bool "Xen guest support on ARM"
1338 depends on ARM && AEABI && OF
1339 depends on CPU_V7 && !CPU_V6
1340 depends on !GENERIC_ATOMIC64
1341 depends on MMU
1342 select ARCH_DMA_ADDR_T_64BIT
1343 select ARM_PSCI
1344 select SWIOTLB
1345 select SWIOTLB_XEN
1346 select PARAVIRT
1347 help
1348 Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
1349
1350config CC_HAVE_STACKPROTECTOR_TLS
1351 def_bool $(cc-option,-mtp=cp15 -mstack-protector-guard=tls -mstack-protector-guard-offset=0)
1352
1353config STACKPROTECTOR_PER_TASK
1354 bool "Use a unique stack canary value for each task"
1355 depends on STACKPROTECTOR && CURRENT_POINTER_IN_TPIDRURO && !XIP_DEFLATED_DATA
1356 depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS
1357 select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS
1358 default y
1359 help
1360 Due to the fact that GCC uses an ordinary symbol reference from
1361 which to load the value of the stack canary, this value can only
1362 change at reboot time on SMP systems, and all tasks running in the
1363 kernel's address space are forced to use the same canary value for
1364 the entire duration that the system is up.
1365
1366 Enable this option to switch to a different method that uses a
1367 different canary value for each task.
1368
1369endmenu
1370
1371menu "Boot options"
1372
1373config USE_OF
1374 bool "Flattened Device Tree support"
1375 select IRQ_DOMAIN
1376 select OF
1377 help
1378 Include support for flattened device tree machine descriptions.
1379
1380config ARCH_WANT_FLAT_DTB_INSTALL
1381 def_bool y
1382
1383config ATAGS
1384 bool "Support for the traditional ATAGS boot data passing"
1385 default y
1386 help
1387 This is the traditional way of passing data to the kernel at boot
1388 time. If you are solely relying on the flattened device tree (or
1389 the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
1390 to remove ATAGS support from your kernel binary.
1391
1392config DEPRECATED_PARAM_STRUCT
1393 bool "Provide old way to pass kernel parameters"
1394 depends on ATAGS
1395 help
1396 This was deprecated in 2001 and announced to live on for 5 years.
1397 Some old boot loaders still use this way.
1398
1399# Compressed boot loader in ROM. Yes, we really want to ask about
1400# TEXT and BSS so we preserve their values in the config files.
1401config ZBOOT_ROM_TEXT
1402 hex "Compressed ROM boot loader base address"
1403 default 0x0
1404 help
1405 The physical address at which the ROM-able zImage is to be
1406 placed in the target. Platforms which normally make use of
1407 ROM-able zImage formats normally set this to a suitable
1408 value in their defconfig file.
1409
1410 If ZBOOT_ROM is not enabled, this has no effect.
1411
1412config ZBOOT_ROM_BSS
1413 hex "Compressed ROM boot loader BSS address"
1414 default 0x0
1415 help
1416 The base address of an area of read/write memory in the target
1417 for the ROM-able zImage which must be available while the
1418 decompressor is running. It must be large enough to hold the
1419 entire decompressed kernel plus an additional 128 KiB.
1420 Platforms which normally make use of ROM-able zImage formats
1421 normally set this to a suitable value in their defconfig file.
1422
1423 If ZBOOT_ROM is not enabled, this has no effect.
1424
1425config ZBOOT_ROM
1426 bool "Compressed boot loader in ROM/flash"
1427 depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
1428 depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
1429 help
1430 Say Y here if you intend to execute your compressed kernel image
1431 (zImage) directly from ROM or flash. If unsure, say N.
1432
1433config ARM_APPENDED_DTB
1434 bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
1435 depends on OF
1436 help
1437 With this option, the boot code will look for a device tree binary
1438 (DTB) appended to zImage
1439 (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
1440
1441 This is meant as a backward compatibility convenience for those
1442 systems with a bootloader that can't be upgraded to accommodate
1443 the documented boot protocol using a device tree.
1444
1445 Beware that there is very little in terms of protection against
1446 this option being confused by leftover garbage in memory that might
1447 look like a DTB header after a reboot if no actual DTB is appended
1448 to zImage. Do not leave this option active in a production kernel
1449 if you don't intend to always append a DTB. Proper passing of the
1450 location into r2 of a bootloader provided DTB is always preferable
1451 to this option.
1452
1453config ARM_ATAG_DTB_COMPAT
1454 bool "Supplement the appended DTB with traditional ATAG information"
1455 depends on ARM_APPENDED_DTB
1456 help
1457 Some old bootloaders can't be updated to a DTB capable one, yet
1458 they provide ATAGs with memory configuration, the ramdisk address,
1459 the kernel cmdline string, etc. Such information is dynamically
1460 provided by the bootloader and can't always be stored in a static
1461 DTB. To allow a device tree enabled kernel to be used with such
1462 bootloaders, this option allows zImage to extract the information
1463 from the ATAG list and store it at run time into the appended DTB.
1464
1465choice
1466 prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
1467 default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1468
1469config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1470 bool "Use bootloader kernel arguments if available"
1471 help
1472 Uses the command-line options passed by the boot loader instead of
1473 the device tree bootargs property. If the boot loader doesn't provide
1474 any, the device tree bootargs property will be used.
1475
1476config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
1477 bool "Extend with bootloader kernel arguments"
1478 help
1479 The command-line arguments provided by the boot loader will be
1480 appended to the the device tree bootargs property.
1481
1482endchoice
1483
1484config CMDLINE
1485 string "Default kernel command string"
1486 default ""
1487 help
1488 On some architectures (e.g. CATS), there is currently no way
1489 for the boot loader to pass arguments to the kernel. For these
1490 architectures, you should supply some command-line options at build
1491 time by entering them here. As a minimum, you should specify the
1492 memory size and the root device (e.g., mem=64M root=/dev/nfs).
1493
1494choice
1495 prompt "Kernel command line type" if CMDLINE != ""
1496 default CMDLINE_FROM_BOOTLOADER
1497
1498config CMDLINE_FROM_BOOTLOADER
1499 bool "Use bootloader kernel arguments if available"
1500 help
1501 Uses the command-line options passed by the boot loader. If
1502 the boot loader doesn't provide any, the default kernel command
1503 string provided in CMDLINE will be used.
1504
1505config CMDLINE_EXTEND
1506 bool "Extend bootloader kernel arguments"
1507 help
1508 The command-line arguments provided by the boot loader will be
1509 appended to the default kernel command string.
1510
1511config CMDLINE_FORCE
1512 bool "Always use the default kernel command string"
1513 help
1514 Always use the default kernel command string, even if the boot
1515 loader passes other arguments to the kernel.
1516 This is useful if you cannot or don't want to change the
1517 command-line options your boot loader passes to the kernel.
1518endchoice
1519
1520config XIP_KERNEL
1521 bool "Kernel Execute-In-Place from ROM"
1522 depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
1523 depends on !ARM_PATCH_IDIV && !ARM_PATCH_PHYS_VIRT && !SMP_ON_UP
1524 help
1525 Execute-In-Place allows the kernel to run from non-volatile storage
1526 directly addressable by the CPU, such as NOR flash. This saves RAM
1527 space since the text section of the kernel is not loaded from flash
1528 to RAM. Read-write sections, such as the data section and stack,
1529 are still copied to RAM. The XIP kernel is not compressed since
1530 it has to run directly from flash, so it will take more space to
1531 store it. The flash address used to link the kernel object files,
1532 and for storing it, is configuration dependent. Therefore, if you
1533 say Y here, you must know the proper physical address where to
1534 store the kernel image depending on your own flash memory usage.
1535
1536 Also note that the make target becomes "make xipImage" rather than
1537 "make zImage" or "make Image". The final kernel binary to put in
1538 ROM memory will be arch/arm/boot/xipImage.
1539
1540 If unsure, say N.
1541
1542config XIP_PHYS_ADDR
1543 hex "XIP Kernel Physical Location"
1544 depends on XIP_KERNEL
1545 default "0x00080000"
1546 help
1547 This is the physical address in your flash memory the kernel will
1548 be linked for and stored to. This address is dependent on your
1549 own flash usage.
1550
1551config XIP_DEFLATED_DATA
1552 bool "Store kernel .data section compressed in ROM"
1553 depends on XIP_KERNEL
1554 select ZLIB_INFLATE
1555 help
1556 Before the kernel is actually executed, its .data section has to be
1557 copied to RAM from ROM. This option allows for storing that data
1558 in compressed form and decompressed to RAM rather than merely being
1559 copied, saving some precious ROM space. A possible drawback is a
1560 slightly longer boot delay.
1561
1562config ARCH_SUPPORTS_KEXEC
1563 def_bool (!SMP || PM_SLEEP_SMP) && MMU
1564
1565config ATAGS_PROC
1566 bool "Export atags in procfs"
1567 depends on ATAGS && KEXEC
1568 default y
1569 help
1570 Should the atags used to boot the kernel be exported in an "atags"
1571 file in procfs. Useful with kexec.
1572
1573config ARCH_SUPPORTS_CRASH_DUMP
1574 def_bool y
1575
1576config AUTO_ZRELADDR
1577 bool "Auto calculation of the decompressed kernel image address" if !ARCH_MULTIPLATFORM
1578 default !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
1579 help
1580 ZRELADDR is the physical address where the decompressed kernel
1581 image will be placed. If AUTO_ZRELADDR is selected, the address
1582 will be determined at run-time, either by masking the current IP
1583 with 0xf8000000, or, if invalid, from the DTB passed in r2.
1584 This assumes the zImage being placed in the first 128MB from
1585 start of memory.
1586
1587config EFI_STUB
1588 bool
1589
1590config EFI
1591 bool "UEFI runtime support"
1592 depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
1593 select UCS2_STRING
1594 select EFI_PARAMS_FROM_FDT
1595 select EFI_STUB
1596 select EFI_GENERIC_STUB
1597 select EFI_RUNTIME_WRAPPERS
1598 help
1599 This option provides support for runtime services provided
1600 by UEFI firmware (such as non-volatile variables, realtime
1601 clock, and platform reset). A UEFI stub is also provided to
1602 allow the kernel to be booted as an EFI application. This
1603 is only useful for kernels that may run on systems that have
1604 UEFI firmware.
1605
1606config DMI
1607 bool "Enable support for SMBIOS (DMI) tables"
1608 depends on EFI
1609 default y
1610 help
1611 This enables SMBIOS/DMI feature for systems.
1612
1613 This option is only useful on systems that have UEFI firmware.
1614 However, even with this option, the resultant kernel should
1615 continue to boot on existing non-UEFI platforms.
1616
1617 NOTE: This does *NOT* enable or encourage the use of DMI quirks,
1618 i.e., the the practice of identifying the platform via DMI to
1619 decide whether certain workarounds for buggy hardware and/or
1620 firmware need to be enabled. This would require the DMI subsystem
1621 to be enabled much earlier than we do on ARM, which is non-trivial.
1622
1623endmenu
1624
1625menu "CPU Power Management"
1626
1627source "drivers/cpufreq/Kconfig"
1628
1629source "drivers/cpuidle/Kconfig"
1630
1631endmenu
1632
1633menu "Floating point emulation"
1634
1635comment "At least one emulation must be selected"
1636
1637config FPE_NWFPE
1638 bool "NWFPE math emulation"
1639 depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
1640 help
1641 Say Y to include the NWFPE floating point emulator in the kernel.
1642 This is necessary to run most binaries. Linux does not currently
1643 support floating point hardware so you need to say Y here even if
1644 your machine has an FPA or floating point co-processor podule.
1645
1646 You may say N here if you are going to load the Acorn FPEmulator
1647 early in the bootup.
1648
1649config FPE_NWFPE_XP
1650 bool "Support extended precision"
1651 depends on FPE_NWFPE
1652 help
1653 Say Y to include 80-bit support in the kernel floating-point
1654 emulator. Otherwise, only 32 and 64-bit support is compiled in.
1655 Note that gcc does not generate 80-bit operations by default,
1656 so in most cases this option only enlarges the size of the
1657 floating point emulator without any good reason.
1658
1659 You almost surely want to say N here.
1660
1661config FPE_FASTFPE
1662 bool "FastFPE math emulation (EXPERIMENTAL)"
1663 depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
1664 help
1665 Say Y here to include the FAST floating point emulator in the kernel.
1666 This is an experimental much faster emulator which now also has full
1667 precision for the mantissa. It does not support any exceptions.
1668 It is very simple, and approximately 3-6 times faster than NWFPE.
1669
1670 It should be sufficient for most programs. It may be not suitable
1671 for scientific calculations, but you have to check this for yourself.
1672 If you do not feel you need a faster FP emulation you should better
1673 choose NWFPE.
1674
1675config VFP
1676 bool "VFP-format floating point maths"
1677 depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
1678 help
1679 Say Y to include VFP support code in the kernel. This is needed
1680 if your hardware includes a VFP unit.
1681
1682 Please see <file:Documentation/arch/arm/vfp/release-notes.rst> for
1683 release notes and additional status information.
1684
1685 Say N if your target does not have VFP hardware.
1686
1687config VFPv3
1688 bool
1689 depends on VFP
1690 default y if CPU_V7
1691
1692config NEON
1693 bool "Advanced SIMD (NEON) Extension support"
1694 depends on VFPv3 && CPU_V7
1695 help
1696 Say Y to include support code for NEON, the ARMv7 Advanced SIMD
1697 Extension.
1698
1699config KERNEL_MODE_NEON
1700 bool "Support for NEON in kernel mode"
1701 depends on NEON && AEABI
1702 help
1703 Say Y to include support for NEON in kernel mode.
1704
1705endmenu
1706
1707menu "Power management options"
1708
1709source "kernel/power/Kconfig"
1710
1711config ARCH_SUSPEND_POSSIBLE
1712 depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
1713 CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
1714 def_bool y
1715
1716config ARM_CPU_SUSPEND
1717 def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
1718 depends on ARCH_SUSPEND_POSSIBLE
1719
1720config ARCH_HIBERNATION_POSSIBLE
1721 bool
1722 depends on MMU
1723 default y if ARCH_SUSPEND_POSSIBLE
1724
1725endmenu
1726
1727source "arch/arm/Kconfig.assembler"