1 # SPDX-License-Identifier: GPL-2.0
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_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
12 select ARCH_HAS_ELF_RANDOMIZE
13 select ARCH_HAS_FORTIFY_SOURCE
14 select ARCH_HAS_KEEPINITRD
16 select ARCH_HAS_MEMBARRIER_SYNC_CORE
17 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
18 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
19 select ARCH_HAS_SETUP_DMA_OPS
20 select ARCH_HAS_SET_MEMORY
22 select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
23 select ARCH_HAS_STRICT_MODULE_RWX if MMU
24 select ARCH_HAS_SYNC_DMA_FOR_DEVICE
25 select ARCH_HAS_SYNC_DMA_FOR_CPU
26 select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
27 select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
28 select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
29 select ARCH_HAS_GCOV_PROFILE_ALL
30 select ARCH_KEEP_MEMBLOCK
31 select ARCH_HAS_UBSAN_SANITIZE_ALL
32 select ARCH_MIGHT_HAVE_PC_PARPORT
33 select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
34 select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
35 select ARCH_SUPPORTS_ATOMIC_RMW
36 select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
37 select ARCH_USE_BUILTIN_BSWAP
38 select ARCH_USE_CMPXCHG_LOCKREF
39 select ARCH_USE_MEMTEST
40 select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
41 select ARCH_WANT_GENERAL_HUGETLB
42 select ARCH_WANT_IPC_PARSE_VERSION
43 select ARCH_WANT_LD_ORPHAN_WARN
44 select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
45 select BUILDTIME_TABLE_SORT if MMU
46 select COMMON_CLK if !(ARCH_RPC || ARCH_FOOTBRIDGE)
47 select CLONE_BACKWARDS
48 select CPU_PM if SUSPEND || CPU_IDLE
49 select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
50 select DMA_DECLARE_COHERENT
51 select DMA_GLOBAL_POOL if !MMU
53 select DMA_NONCOHERENT_MMAP if MMU
55 select EDAC_ATOMIC_SCRUB
56 select GENERIC_ALLOCATOR
57 select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
58 select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
59 select GENERIC_CLOCKEVENTS_BROADCAST if SMP
60 select GENERIC_IRQ_IPI if SMP
61 select GENERIC_CPU_AUTOPROBE
62 select GENERIC_EARLY_IOREMAP
63 select GENERIC_IDLE_POLL_SETUP
64 select GENERIC_IRQ_MULTI_HANDLER
65 select GENERIC_IRQ_PROBE
66 select GENERIC_IRQ_SHOW
67 select GENERIC_IRQ_SHOW_LEVEL
68 select GENERIC_LIB_DEVMEM_IS_ALLOWED
69 select GENERIC_PCI_IOMAP
70 select GENERIC_SCHED_CLOCK
71 select GENERIC_SMP_IDLE_THREAD
72 select HARDIRQS_SW_RESEND
74 select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
75 select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
76 select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
77 select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
78 select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
79 select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
80 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
81 select HAVE_ARCH_MMAP_RND_BITS if MMU
82 select HAVE_ARCH_PFN_VALID
83 select HAVE_ARCH_SECCOMP
84 select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
85 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
86 select HAVE_ARCH_TRACEHOOK
87 select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
88 select HAVE_ARM_SMCCC if CPU_V7
89 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
90 select HAVE_CONTEXT_TRACKING_USER
91 select HAVE_C_RECORDMCOUNT
92 select HAVE_BUILDTIME_MCOUNT_SORT
93 select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
94 select HAVE_DMA_CONTIGUOUS if MMU
95 select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
96 select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
97 select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
98 select HAVE_EXIT_THREAD
99 select HAVE_FAST_GUP if ARM_LPAE
100 select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
101 select HAVE_FUNCTION_ERROR_INJECTION
102 select HAVE_FUNCTION_GRAPH_TRACER
103 select HAVE_FUNCTION_TRACER if !XIP_KERNEL
104 select HAVE_GCC_PLUGINS
105 select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
106 select HAVE_IRQ_TIME_ACCOUNTING
107 select HAVE_KERNEL_GZIP
108 select HAVE_KERNEL_LZ4
109 select HAVE_KERNEL_LZMA
110 select HAVE_KERNEL_LZO
111 select HAVE_KERNEL_XZ
112 select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
113 select HAVE_KRETPROBES if HAVE_KPROBES
114 select HAVE_MOD_ARCH_SPECIFIC
116 select HAVE_OPTPROBES if !THUMB2_KERNEL
117 select HAVE_PCI if MMU
118 select HAVE_PERF_EVENTS
119 select HAVE_PERF_REGS
120 select HAVE_PERF_USER_STACK_DUMP
121 select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
122 select HAVE_REGS_AND_STACK_ACCESS_API
124 select HAVE_STACKPROTECTOR
125 select HAVE_SYSCALL_TRACEPOINTS
127 select HAVE_VIRT_CPU_ACCOUNTING_GEN
128 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
129 select IRQ_FORCED_THREADING
130 select MODULES_USE_ELF_REL
131 select NEED_DMA_MAP_STATE
132 select OF_EARLY_FLATTREE if OF
134 select OLD_SIGSUSPEND3
135 select PCI_DOMAINS_GENERIC if PCI
136 select PCI_SYSCALL if PCI
137 select PERF_USE_VMALLOC
139 select SPARSE_IRQ if !(ARCH_FOOTBRIDGE || ARCH_RPC)
140 select SYS_SUPPORTS_APM_EMULATION
141 select THREAD_INFO_IN_TASK
142 select TIMER_OF if OF
143 select HAVE_ARCH_VMAP_STACK if MMU && ARM_HAS_GROUP_RELOCS
144 select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
145 select USE_OF if !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
146 # Above selects are sorted alphabetically; please add new ones
147 # according to that. Thanks.
149 The ARM series is a line of low-power-consumption RISC chip designs
150 licensed by ARM Ltd and targeted at embedded applications and
151 handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
152 manufactured, but legacy ARM-based PC hardware remains popular in
153 Europe. There is an ARM Linux project with a web page at
154 <http://www.arm.linux.org.uk/>.
156 config ARM_HAS_GROUP_RELOCS
158 depends on !LD_IS_LLD || LLD_VERSION >= 140000
159 depends on !COMPILE_TEST
161 Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
162 relocations, which have been around for a long time, but were not
163 supported in LLD until version 14. The combined range is -/+ 256 MiB,
164 which is usually sufficient, but not for allyesconfig, so we disable
165 this feature when doing compile testing.
167 config ARM_DMA_USE_IOMMU
169 select NEED_SG_DMA_LENGTH
173 config ARM_DMA_IOMMU_ALIGNMENT
174 int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
178 DMA mapping framework by default aligns all buffers to the smallest
179 PAGE_SIZE order which is greater than or equal to the requested buffer
180 size. This works well for buffers up to a few hundreds kilobytes, but
181 for larger buffers it just a waste of address space. Drivers which has
182 relatively small addressing window (like 64Mib) might run out of
183 virtual space with just a few allocations.
185 With this parameter you can specify the maximum PAGE_SIZE order for
186 DMA IOMMU buffers. Larger buffers will be aligned only to this
187 specified order. The order is expressed as a power of two multiplied
192 config SYS_SUPPORTS_APM_EMULATION
197 select GENERIC_ALLOCATOR
208 config STACKTRACE_SUPPORT
212 config LOCKDEP_SUPPORT
216 config ARCH_HAS_ILOG2_U32
219 config ARCH_HAS_ILOG2_U64
222 config ARCH_HAS_BANDGAP
225 config FIX_EARLYCON_MEM
228 config GENERIC_HWEIGHT
232 config GENERIC_CALIBRATE_DELAY
236 config ARCH_MAY_HAVE_PC_FDC
239 config ARCH_SUPPORTS_UPROBES
242 config GENERIC_ISA_DMA
251 config ARM_PATCH_PHYS_VIRT
252 bool "Patch physical to virtual translations at runtime" if EMBEDDED
256 Patch phys-to-virt and virt-to-phys translation functions at
257 boot and module load time according to the position of the
258 kernel in system memory.
260 This can only be used with non-XIP MMU kernels where the base
261 of physical memory is at a 2 MiB boundary.
263 Only disable this option if you know that you do not require
264 this feature (eg, building a kernel for a single machine) and
265 you need to shrink the kernel to the minimal size.
267 config NEED_MACH_IO_H
270 Select this when mach/io.h is required to provide special
271 definitions for this platform. The need for mach/io.h should
272 be avoided when possible.
274 config NEED_MACH_MEMORY_H
277 Select this when mach/memory.h is required to provide special
278 definitions for this platform. The need for mach/memory.h should
279 be avoided when possible.
282 hex "Physical address of main memory" if MMU
283 depends on !ARM_PATCH_PHYS_VIRT || !AUTO_ZRELADDR
284 default DRAM_BASE if !MMU
285 default 0x00000000 if ARCH_FOOTBRIDGE
286 default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
287 default 0xa0000000 if ARCH_PXA
288 default 0xc0000000 if ARCH_EP93XX || ARCH_SA1100
291 Please provide the physical address corresponding to the
292 location of main memory in your system.
298 config PGTABLE_LEVELS
300 default 3 if ARM_LPAE
306 bool "MMU-based Paged Memory Management Support"
309 Select if you want MMU-based virtualised addressing space
310 support by paged memory management. If unsure, say 'Y'.
312 config ARM_SINGLE_ARMV7M
318 config ARCH_MMAP_RND_BITS_MIN
321 config ARCH_MMAP_RND_BITS_MAX
322 default 14 if PAGE_OFFSET=0x40000000
323 default 15 if PAGE_OFFSET=0x80000000
326 config ARCH_MULTIPLATFORM
327 bool "Require kernel to be portable to multiple machines" if EXPERT
328 depends on MMU && !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
331 In general, all Arm machines can be supported in a single
332 kernel image, covering either Armv4/v5 or Armv6/v7.
334 However, some configuration options require hardcoding machine
335 specific physical addresses or enable errata workarounds that may
336 break other machines.
338 Selecting N here allows using those options, including
339 DEBUG_UNCOMPRESS, XIP_KERNEL and ZBOOT_ROM. If unsure, say Y.
341 menu "Platform selection"
344 comment "CPU Core family selection"
347 bool "ARMv4 based platforms (FA526, StrongARM)"
348 depends on !ARCH_MULTI_V6_V7
349 # https://github.com/llvm/llvm-project/issues/50764
350 depends on !LD_IS_LLD || LLD_VERSION >= 160000
351 select ARCH_MULTI_V4_V5
352 select CPU_FA526 if !(CPU_SA110 || CPU_SA1100)
354 config ARCH_MULTI_V4T
355 bool "ARMv4T based platforms (ARM720T, ARM920T, ...)"
356 depends on !ARCH_MULTI_V6_V7
357 # https://github.com/llvm/llvm-project/issues/50764
358 depends on !LD_IS_LLD || LLD_VERSION >= 160000
359 select ARCH_MULTI_V4_V5
360 select CPU_ARM920T if !(CPU_ARM7TDMI || CPU_ARM720T || \
361 CPU_ARM740T || CPU_ARM9TDMI || CPU_ARM922T || \
362 CPU_ARM925T || CPU_ARM940T)
365 bool "ARMv5 based platforms (ARM926T, XSCALE, PJ1, ...)"
366 depends on !ARCH_MULTI_V6_V7
367 select ARCH_MULTI_V4_V5
368 select CPU_ARM926T if !(CPU_ARM946E || CPU_ARM1020 || \
369 CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || \
370 CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_FEROCEON)
372 config ARCH_MULTI_V4_V5
376 bool "ARMv6 based platforms (ARM11)"
377 select ARCH_MULTI_V6_V7
381 bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)"
383 select ARCH_MULTI_V6_V7
387 config ARCH_MULTI_V6_V7
389 select MIGHT_HAVE_CACHE_L2X0
391 config ARCH_MULTI_CPU_AUTO
392 def_bool !(ARCH_MULTI_V4 || ARCH_MULTI_V4T || ARCH_MULTI_V6_V7)
398 bool "Dummy Virtual Machine"
399 depends on ARCH_MULTI_V7
402 select ARM_GIC_V2M if PCI
404 select ARM_GIC_V3_ITS if PCI
406 select HAVE_ARM_ARCH_TIMER
409 bool "Airoha SoC Support"
410 depends on ARCH_MULTI_V7
415 select HAVE_ARM_ARCH_TIMER
417 Support for Airoha EN7523 SoCs
420 # This is sorted alphabetically by mach-* pathname. However, plat-*
421 # Kconfigs may be included either alphabetically (according to the
422 # plat- suffix) or along side the corresponding mach-* source.
424 source "arch/arm/mach-actions/Kconfig"
426 source "arch/arm/mach-alpine/Kconfig"
428 source "arch/arm/mach-artpec/Kconfig"
430 source "arch/arm/mach-asm9260/Kconfig"
432 source "arch/arm/mach-aspeed/Kconfig"
434 source "arch/arm/mach-at91/Kconfig"
436 source "arch/arm/mach-axxia/Kconfig"
438 source "arch/arm/mach-bcm/Kconfig"
440 source "arch/arm/mach-berlin/Kconfig"
442 source "arch/arm/mach-clps711x/Kconfig"
444 source "arch/arm/mach-davinci/Kconfig"
446 source "arch/arm/mach-digicolor/Kconfig"
448 source "arch/arm/mach-dove/Kconfig"
450 source "arch/arm/mach-ep93xx/Kconfig"
452 source "arch/arm/mach-exynos/Kconfig"
454 source "arch/arm/mach-footbridge/Kconfig"
456 source "arch/arm/mach-gemini/Kconfig"
458 source "arch/arm/mach-highbank/Kconfig"
460 source "arch/arm/mach-hisi/Kconfig"
462 source "arch/arm/mach-hpe/Kconfig"
464 source "arch/arm/mach-imx/Kconfig"
466 source "arch/arm/mach-ixp4xx/Kconfig"
468 source "arch/arm/mach-keystone/Kconfig"
470 source "arch/arm/mach-lpc32xx/Kconfig"
472 source "arch/arm/mach-mediatek/Kconfig"
474 source "arch/arm/mach-meson/Kconfig"
476 source "arch/arm/mach-milbeaut/Kconfig"
478 source "arch/arm/mach-mmp/Kconfig"
480 source "arch/arm/mach-moxart/Kconfig"
482 source "arch/arm/mach-mstar/Kconfig"
484 source "arch/arm/mach-mv78xx0/Kconfig"
486 source "arch/arm/mach-mvebu/Kconfig"
488 source "arch/arm/mach-mxs/Kconfig"
490 source "arch/arm/mach-nomadik/Kconfig"
492 source "arch/arm/mach-npcm/Kconfig"
494 source "arch/arm/mach-nspire/Kconfig"
496 source "arch/arm/mach-omap1/Kconfig"
498 source "arch/arm/mach-omap2/Kconfig"
500 source "arch/arm/mach-orion5x/Kconfig"
502 source "arch/arm/mach-pxa/Kconfig"
504 source "arch/arm/mach-qcom/Kconfig"
506 source "arch/arm/mach-rda/Kconfig"
508 source "arch/arm/mach-realtek/Kconfig"
510 source "arch/arm/mach-rpc/Kconfig"
512 source "arch/arm/mach-rockchip/Kconfig"
514 source "arch/arm/mach-s3c/Kconfig"
516 source "arch/arm/mach-s5pv210/Kconfig"
518 source "arch/arm/mach-sa1100/Kconfig"
520 source "arch/arm/mach-shmobile/Kconfig"
522 source "arch/arm/mach-socfpga/Kconfig"
524 source "arch/arm/mach-spear/Kconfig"
526 source "arch/arm/mach-sti/Kconfig"
528 source "arch/arm/mach-stm32/Kconfig"
530 source "arch/arm/mach-sunplus/Kconfig"
532 source "arch/arm/mach-sunxi/Kconfig"
534 source "arch/arm/mach-tegra/Kconfig"
536 source "arch/arm/mach-uniphier/Kconfig"
538 source "arch/arm/mach-ux500/Kconfig"
540 source "arch/arm/mach-versatile/Kconfig"
542 source "arch/arm/mach-vt8500/Kconfig"
544 source "arch/arm/mach-zynq/Kconfig"
546 # ARMv7-M architecture
548 bool "NXP LPC18xx/LPC43xx"
549 depends on ARM_SINGLE_ARMV7M
550 select ARCH_HAS_RESET_CONTROLLER
552 select CLKSRC_LPC32XX
555 Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
556 high performance microcontrollers.
559 bool "ARM MPS2 platform"
560 depends on ARM_SINGLE_ARMV7M
564 Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
565 with a range of available cores like Cortex-M3/M4/M7.
567 Please, note that depends which Application Note is used memory map
568 for the platform may vary, so adjustment of RAM base might be needed.
570 # Definitions to make life easier
577 select GENERIC_IRQ_CHIP
580 config PLAT_ORION_LEGACY
584 config PLAT_VERSATILE
587 source "arch/arm/mm/Kconfig"
590 bool "Enable iWMMXt support"
591 depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
592 default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B
594 Enable support for iWMMXt context switching at run time if
595 running on a CPU that supports it.
598 source "arch/arm/Kconfig-nommu"
601 config PJ4B_ERRATA_4742
602 bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
603 depends on CPU_PJ4B && MACH_ARMADA_370
606 When coming out of either a Wait for Interrupt (WFI) or a Wait for
607 Event (WFE) IDLE states, a specific timing sensitivity exists between
608 the retiring WFI/WFE instructions and the newly issued subsequent
609 instructions. This sensitivity can result in a CPU hang scenario.
611 The software must insert either a Data Synchronization Barrier (DSB)
612 or Data Memory Barrier (DMB) command immediately after the WFI/WFE
615 config ARM_ERRATA_326103
616 bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
619 Executing a SWP instruction to read-only memory does not set bit 11
620 of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
621 treat the access as a read, preventing a COW from occurring and
622 causing the faulting task to livelock.
624 config ARM_ERRATA_411920
625 bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
626 depends on CPU_V6 || CPU_V6K
628 Invalidation of the Instruction Cache operation can
629 fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
630 It does not affect the MPCore. This option enables the ARM Ltd.
631 recommended workaround.
633 config ARM_ERRATA_430973
634 bool "ARM errata: Stale prediction on replaced interworking branch"
637 This option enables the workaround for the 430973 Cortex-A8
638 r1p* erratum. If a code sequence containing an ARM/Thumb
639 interworking branch is replaced with another code sequence at the
640 same virtual address, whether due to self-modifying code or virtual
641 to physical address re-mapping, Cortex-A8 does not recover from the
642 stale interworking branch prediction. This results in Cortex-A8
643 executing the new code sequence in the incorrect ARM or Thumb state.
644 The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
645 and also flushes the branch target cache at every context switch.
646 Note that setting specific bits in the ACTLR register may not be
647 available in non-secure mode.
649 config ARM_ERRATA_458693
650 bool "ARM errata: Processor deadlock when a false hazard is created"
652 depends on !ARCH_MULTIPLATFORM
654 This option enables the workaround for the 458693 Cortex-A8 (r2p0)
655 erratum. For very specific sequences of memory operations, it is
656 possible for a hazard condition intended for a cache line to instead
657 be incorrectly associated with a different cache line. This false
658 hazard might then cause a processor deadlock. The workaround enables
659 the L1 caching of the NEON accesses and disables the PLD instruction
660 in the ACTLR register. Note that setting specific bits in the ACTLR
661 register may not be available in non-secure mode and thus is not
662 available on a multiplatform kernel. This should be applied by the
665 config ARM_ERRATA_460075
666 bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
668 depends on !ARCH_MULTIPLATFORM
670 This option enables the workaround for the 460075 Cortex-A8 (r2p0)
671 erratum. Any asynchronous access to the L2 cache may encounter a
672 situation in which recent store transactions to the L2 cache are lost
673 and overwritten with stale memory contents from external memory. The
674 workaround disables the write-allocate mode for the L2 cache via the
675 ACTLR register. Note that setting specific bits in the ACTLR register
676 may not be available in non-secure mode and thus is not available on
677 a multiplatform kernel. This should be applied by the bootloader
680 config ARM_ERRATA_742230
681 bool "ARM errata: DMB operation may be faulty"
682 depends on CPU_V7 && SMP
683 depends on !ARCH_MULTIPLATFORM
685 This option enables the workaround for the 742230 Cortex-A9
686 (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
687 between two write operations may not ensure the correct visibility
688 ordering of the two writes. This workaround sets a specific bit in
689 the diagnostic register of the Cortex-A9 which causes the DMB
690 instruction to behave as a DSB, ensuring the correct behaviour of
691 the two writes. Note that setting specific bits in the diagnostics
692 register may not be available in non-secure mode and thus is not
693 available on a multiplatform kernel. This should be applied by the
696 config ARM_ERRATA_742231
697 bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
698 depends on CPU_V7 && SMP
699 depends on !ARCH_MULTIPLATFORM
701 This option enables the workaround for the 742231 Cortex-A9
702 (r2p0..r2p2) erratum. Under certain conditions, specific to the
703 Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
704 accessing some data located in the same cache line, may get corrupted
705 data due to bad handling of the address hazard when the line gets
706 replaced from one of the CPUs at the same time as another CPU is
707 accessing it. This workaround sets specific bits in the diagnostic
708 register of the Cortex-A9 which reduces the linefill issuing
709 capabilities of the processor. Note that setting specific bits in the
710 diagnostics register may not be available in non-secure mode and thus
711 is not available on a multiplatform kernel. This should be applied by
712 the bootloader instead.
714 config ARM_ERRATA_643719
715 bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
716 depends on CPU_V7 && SMP
719 This option enables the workaround for the 643719 Cortex-A9 (prior to
720 r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
721 register returns zero when it should return one. The workaround
722 corrects this value, ensuring cache maintenance operations which use
723 it behave as intended and avoiding data corruption.
725 config ARM_ERRATA_720789
726 bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
729 This option enables the workaround for the 720789 Cortex-A9 (prior to
730 r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
731 broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
732 As a consequence of this erratum, some TLB entries which should be
733 invalidated are not, resulting in an incoherency in the system page
734 tables. The workaround changes the TLB flushing routines to invalidate
735 entries regardless of the ASID.
737 config ARM_ERRATA_743622
738 bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
740 depends on !ARCH_MULTIPLATFORM
742 This option enables the workaround for the 743622 Cortex-A9
743 (r2p*) erratum. Under very rare conditions, a faulty
744 optimisation in the Cortex-A9 Store Buffer may lead to data
745 corruption. This workaround sets a specific bit in the diagnostic
746 register of the Cortex-A9 which disables the Store Buffer
747 optimisation, preventing the defect from occurring. This has no
748 visible impact on the overall performance or power consumption of the
749 processor. Note that setting specific bits in the diagnostics register
750 may not be available in non-secure mode and thus is not available on a
751 multiplatform kernel. This should be applied by the bootloader instead.
753 config ARM_ERRATA_751472
754 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
756 depends on !ARCH_MULTIPLATFORM
758 This option enables the workaround for the 751472 Cortex-A9 (prior
759 to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
760 completion of a following broadcasted operation if the second
761 operation is received by a CPU before the ICIALLUIS has completed,
762 potentially leading to corrupted entries in the cache or TLB.
763 Note that setting specific bits in the diagnostics register may
764 not be available in non-secure mode and thus is not available on
765 a multiplatform kernel. This should be applied by the bootloader
768 config ARM_ERRATA_754322
769 bool "ARM errata: possible faulty MMU translations following an ASID switch"
772 This option enables the workaround for the 754322 Cortex-A9 (r2p*,
773 r3p*) erratum. A speculative memory access may cause a page table walk
774 which starts prior to an ASID switch but completes afterwards. This
775 can populate the micro-TLB with a stale entry which may be hit with
776 the new ASID. This workaround places two dsb instructions in the mm
777 switching code so that no page table walks can cross the ASID switch.
779 config ARM_ERRATA_754327
780 bool "ARM errata: no automatic Store Buffer drain"
781 depends on CPU_V7 && SMP
783 This option enables the workaround for the 754327 Cortex-A9 (prior to
784 r2p0) erratum. The Store Buffer does not have any automatic draining
785 mechanism and therefore a livelock may occur if an external agent
786 continuously polls a memory location waiting to observe an update.
787 This workaround defines cpu_relax() as smp_mb(), preventing correctly
788 written polling loops from denying visibility of updates to memory.
790 config ARM_ERRATA_364296
791 bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
794 This options enables the workaround for the 364296 ARM1136
795 r0p2 erratum (possible cache data corruption with
796 hit-under-miss enabled). It sets the undocumented bit 31 in
797 the auxiliary control register and the FI bit in the control
798 register, thus disabling hit-under-miss without putting the
799 processor into full low interrupt latency mode. ARM11MPCore
802 config ARM_ERRATA_764369
803 bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
804 depends on CPU_V7 && SMP
806 This option enables the workaround for erratum 764369
807 affecting Cortex-A9 MPCore with two or more processors (all
808 current revisions). Under certain timing circumstances, a data
809 cache line maintenance operation by MVA targeting an Inner
810 Shareable memory region may fail to proceed up to either the
811 Point of Coherency or to the Point of Unification of the
812 system. This workaround adds a DSB instruction before the
813 relevant cache maintenance functions and sets a specific bit
814 in the diagnostic control register of the SCU.
816 config ARM_ERRATA_764319
817 bool "ARM errata: Read to DBGPRSR and DBGOSLSR may generate Undefined instruction"
820 This option enables the workaround for the 764319 Cortex A-9 erratum.
821 CP14 read accesses to the DBGPRSR and DBGOSLSR registers generate an
822 unexpected Undefined Instruction exception when the DBGSWENABLE
823 external pin is set to 0, even when the CP14 accesses are performed
824 from a privileged mode. This work around catches the exception in a
825 way the kernel does not stop execution.
827 config ARM_ERRATA_775420
828 bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
831 This option enables the workaround for the 775420 Cortex-A9 (r2p2,
832 r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
833 operation aborts with MMU exception, it might cause the processor
834 to deadlock. This workaround puts DSB before executing ISB if
835 an abort may occur on cache maintenance.
837 config ARM_ERRATA_798181
838 bool "ARM errata: TLBI/DSB failure on Cortex-A15"
839 depends on CPU_V7 && SMP
841 On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
842 adequately shooting down all use of the old entries. This
843 option enables the Linux kernel workaround for this erratum
844 which sends an IPI to the CPUs that are running the same ASID
845 as the one being invalidated.
847 config ARM_ERRATA_773022
848 bool "ARM errata: incorrect instructions may be executed from loop buffer"
851 This option enables the workaround for the 773022 Cortex-A15
852 (up to r0p4) erratum. In certain rare sequences of code, the
853 loop buffer may deliver incorrect instructions. This
854 workaround disables the loop buffer to avoid the erratum.
856 config ARM_ERRATA_818325_852422
857 bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
860 This option enables the workaround for:
861 - Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
862 instruction might deadlock. Fixed in r0p1.
863 - Cortex-A12 852422: Execution of a sequence of instructions might
864 lead to either a data corruption or a CPU deadlock. Not fixed in
865 any Cortex-A12 cores yet.
866 This workaround for all both errata involves setting bit[12] of the
867 Feature Register. This bit disables an optimisation applied to a
868 sequence of 2 instructions that use opposing condition codes.
870 config ARM_ERRATA_821420
871 bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
874 This option enables the workaround for the 821420 Cortex-A12
875 (all revs) erratum. In very rare timing conditions, a sequence
876 of VMOV to Core registers instructions, for which the second
877 one is in the shadow of a branch or abort, can lead to a
878 deadlock when the VMOV instructions are issued out-of-order.
880 config ARM_ERRATA_825619
881 bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
884 This option enables the workaround for the 825619 Cortex-A12
885 (all revs) erratum. Within rare timing constraints, executing a
886 DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
887 and Device/Strongly-Ordered loads and stores might cause deadlock
889 config ARM_ERRATA_857271
890 bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
893 This option enables the workaround for the 857271 Cortex-A12
894 (all revs) erratum. Under very rare timing conditions, the CPU might
895 hang. The workaround is expected to have a < 1% performance impact.
897 config ARM_ERRATA_852421
898 bool "ARM errata: A17: DMB ST might fail to create order between stores"
901 This option enables the workaround for the 852421 Cortex-A17
902 (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
903 execution of a DMB ST instruction might fail to properly order
904 stores from GroupA and stores from GroupB.
906 config ARM_ERRATA_852423
907 bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
910 This option enables the workaround for:
911 - Cortex-A17 852423: Execution of a sequence of instructions might
912 lead to either a data corruption or a CPU deadlock. Not fixed in
913 any Cortex-A17 cores yet.
914 This is identical to Cortex-A12 erratum 852422. It is a separate
915 config option from the A12 erratum due to the way errata are checked
918 config ARM_ERRATA_857272
919 bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
922 This option enables the workaround for the 857272 Cortex-A17 erratum.
923 This erratum is not known to be fixed in any A17 revision.
924 This is identical to Cortex-A12 erratum 857271. It is a separate
925 config option from the A12 erratum due to the way errata are checked
930 source "arch/arm/common/Kconfig"
937 Find out whether you have ISA slots on your motherboard. ISA is the
938 name of a bus system, i.e. the way the CPU talks to the other stuff
939 inside your box. Other bus systems are PCI, EISA, MicroChannel
940 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
941 newer boards don't support it. If you have ISA, say Y, otherwise N.
943 # Select ISA DMA interface
947 config ARM_ERRATA_814220
948 bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
951 The v7 ARM states that all cache and branch predictor maintenance
952 operations that do not specify an address execute, relative to
953 each other, in program order.
954 However, because of this erratum, an L2 set/way cache maintenance
955 operation can overtake an L1 set/way cache maintenance operation.
956 This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
961 menu "Kernel Features"
966 This option should be selected by machines which have an SMP-
969 The only effect of this option is to make the SMP-related
970 options available to the user for configuration.
973 bool "Symmetric Multi-Processing"
974 depends on CPU_V6K || CPU_V7
976 depends on MMU || ARM_MPU
979 This enables support for systems with more than one CPU. If you have
980 a system with only one CPU, say N. If you have a system with more
983 If you say N here, the kernel will run on uni- and multiprocessor
984 machines, but will use only one CPU of a multiprocessor machine. If
985 you say Y here, the kernel will run on many, but not all,
986 uniprocessor machines. On a uniprocessor machine, the kernel
987 will run faster if you say N here.
989 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
990 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
991 <http://tldp.org/HOWTO/SMP-HOWTO.html>.
993 If you don't know what to do here, say N.
996 bool "Allow booting SMP kernel on uniprocessor systems"
997 depends on SMP && MMU
1000 SMP kernels contain instructions which fail on non-SMP processors.
1001 Enabling this option allows the kernel to modify itself to make
1002 these instructions safe. Disabling it allows about 1K of space
1005 If you don't know what to do here, say Y.
1008 config CURRENT_POINTER_IN_TPIDRURO
1010 depends on CPU_32v6K && !CPU_V6
1014 select HAVE_IRQ_EXIT_ON_IRQ_STACK
1015 select HAVE_SOFTIRQ_ON_OWN_STACK
1017 config ARM_CPU_TOPOLOGY
1018 bool "Support cpu topology definition"
1019 depends on SMP && CPU_V7
1022 Support ARM cpu topology definition. The MPIDR register defines
1023 affinity between processors which is then used to describe the cpu
1024 topology of an ARM System.
1027 bool "Multi-core scheduler support"
1028 depends on ARM_CPU_TOPOLOGY
1030 Multi-core scheduler support improves the CPU scheduler's decision
1031 making when dealing with multi-core CPU chips at a cost of slightly
1032 increased overhead in some places. If unsure say N here.
1035 bool "SMT scheduler support"
1036 depends on ARM_CPU_TOPOLOGY
1038 Improves the CPU scheduler's decision making when dealing with
1039 MultiThreading at a cost of slightly increased overhead in some
1040 places. If unsure say N here.
1045 This option enables support for the ARM snoop control unit
1047 config HAVE_ARM_ARCH_TIMER
1048 bool "Architected timer support"
1050 select ARM_ARCH_TIMER
1052 This option enables support for the ARM architected timer
1057 This options enables support for the ARM timer and watchdog unit
1060 bool "Multi-Cluster Power Management"
1061 depends on CPU_V7 && SMP
1063 This option provides the common power management infrastructure
1064 for (multi-)cluster based systems, such as big.LITTLE based
1067 config MCPM_QUAD_CLUSTER
1071 To avoid wasting resources unnecessarily, MCPM only supports up
1072 to 2 clusters by default.
1073 Platforms with 3 or 4 clusters that use MCPM must select this
1074 option to allow the additional clusters to be managed.
1077 bool "big.LITTLE support (Experimental)"
1078 depends on CPU_V7 && SMP
1081 This option enables support selections for the big.LITTLE
1082 system architecture.
1085 bool "big.LITTLE switcher support"
1086 depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
1089 The big.LITTLE "switcher" provides the core functionality to
1090 transparently handle transition between a cluster of A15's
1091 and a cluster of A7's in a big.LITTLE system.
1093 config BL_SWITCHER_DUMMY_IF
1094 tristate "Simple big.LITTLE switcher user interface"
1095 depends on BL_SWITCHER && DEBUG_KERNEL
1097 This is a simple and dummy char dev interface to control
1098 the big.LITTLE switcher core code. It is meant for
1099 debugging purposes only.
1102 prompt "Memory split"
1106 Select the desired split between kernel and user memory.
1108 If you are not absolutely sure what you are doing, leave this
1112 bool "3G/1G user/kernel split"
1113 config VMSPLIT_3G_OPT
1114 depends on !ARM_LPAE
1115 bool "3G/1G user/kernel split (for full 1G low memory)"
1117 bool "2G/2G user/kernel split"
1119 bool "1G/3G user/kernel split"
1124 default PHYS_OFFSET if !MMU
1125 default 0x40000000 if VMSPLIT_1G
1126 default 0x80000000 if VMSPLIT_2G
1127 default 0xB0000000 if VMSPLIT_3G_OPT
1130 config KASAN_SHADOW_OFFSET
1133 default 0x1f000000 if PAGE_OFFSET=0x40000000
1134 default 0x5f000000 if PAGE_OFFSET=0x80000000
1135 default 0x9f000000 if PAGE_OFFSET=0xC0000000
1136 default 0x8f000000 if PAGE_OFFSET=0xB0000000
1140 int "Maximum number of CPUs (2-32)"
1141 range 2 16 if DEBUG_KMAP_LOCAL
1142 range 2 32 if !DEBUG_KMAP_LOCAL
1146 The maximum number of CPUs that the kernel can support.
1147 Up to 32 CPUs can be supported, or up to 16 if kmap_local()
1148 debugging is enabled, which uses half of the per-CPU fixmap
1149 slots as guard regions.
1152 bool "Support for hot-pluggable CPUs"
1154 select GENERIC_IRQ_MIGRATION
1156 Say Y here to experiment with turning CPUs off and on. CPUs
1157 can be controlled through /sys/devices/system/cpu.
1160 bool "Support for the ARM Power State Coordination Interface (PSCI)"
1161 depends on HAVE_ARM_SMCCC
1164 Say Y here if you want Linux to communicate with system firmware
1165 implementing the PSCI specification for CPU-centric power
1166 management operations described in ARM document number ARM DEN
1167 0022A ("Power State Coordination Interface System Software on
1172 default 128 if SOC_AT91RM9200
1176 depends on HZ_FIXED = 0
1177 prompt "Timer frequency"
1201 default HZ_FIXED if HZ_FIXED != 0
1202 default 100 if HZ_100
1203 default 200 if HZ_200
1204 default 250 if HZ_250
1205 default 300 if HZ_300
1206 default 500 if HZ_500
1210 def_bool HIGH_RES_TIMERS
1212 config THUMB2_KERNEL
1213 bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
1214 depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
1215 default y if CPU_THUMBONLY
1218 By enabling this option, the kernel will be compiled in
1223 config ARM_PATCH_IDIV
1224 bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
1228 The ARM compiler inserts calls to __aeabi_idiv() and
1229 __aeabi_uidiv() when it needs to perform division on signed
1230 and unsigned integers. Some v7 CPUs have support for the sdiv
1231 and udiv instructions that can be used to implement those
1234 Enabling this option allows the kernel to modify itself to
1235 replace the first two instructions of these library functions
1236 with the sdiv or udiv plus "bx lr" instructions when the CPU
1237 it is running on supports them. Typically this will be faster
1238 and less power intensive than running the original library
1239 code to do integer division.
1242 bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
1243 !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
1244 default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
1246 This option allows for the kernel to be compiled using the latest
1247 ARM ABI (aka EABI). This is only useful if you are using a user
1248 space environment that is also compiled with EABI.
1250 Since there are major incompatibilities between the legacy ABI and
1251 EABI, especially with regard to structure member alignment, this
1252 option also changes the kernel syscall calling convention to
1253 disambiguate both ABIs and allow for backward compatibility support
1254 (selected with CONFIG_OABI_COMPAT).
1256 To use this you need GCC version 4.0.0 or later.
1259 bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
1260 depends on AEABI && !THUMB2_KERNEL
1262 This option preserves the old syscall interface along with the
1263 new (ARM EABI) one. It also provides a compatibility layer to
1264 intercept syscalls that have structure arguments which layout
1265 in memory differs between the legacy ABI and the new ARM EABI
1266 (only for non "thumb" binaries). This option adds a tiny
1267 overhead to all syscalls and produces a slightly larger kernel.
1269 The seccomp filter system will not be available when this is
1270 selected, since there is no way yet to sensibly distinguish
1271 between calling conventions during filtering.
1273 If you know you'll be using only pure EABI user space then you
1274 can say N here. If this option is not selected and you attempt
1275 to execute a legacy ABI binary then the result will be
1276 UNPREDICTABLE (in fact it can be predicted that it won't work
1277 at all). If in doubt say N.
1279 config ARCH_SELECT_MEMORY_MODEL
1282 config ARCH_FLATMEM_ENABLE
1283 def_bool !(ARCH_RPC || ARCH_SA1100)
1285 config ARCH_SPARSEMEM_ENABLE
1286 def_bool !ARCH_FOOTBRIDGE
1287 select SPARSEMEM_STATIC if SPARSEMEM
1290 bool "High Memory Support"
1293 select KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1295 The address space of ARM processors is only 4 Gigabytes large
1296 and it has to accommodate user address space, kernel address
1297 space as well as some memory mapped IO. That means that, if you
1298 have a large amount of physical memory and/or IO, not all of the
1299 memory can be "permanently mapped" by the kernel. The physical
1300 memory that is not permanently mapped is called "high memory".
1302 Depending on the selected kernel/user memory split, minimum
1303 vmalloc space and actual amount of RAM, you may not need this
1304 option which should result in a slightly faster kernel.
1309 bool "Allocate 2nd-level pagetables from highmem" if EXPERT
1313 The VM uses one page of physical memory for each page table.
1314 For systems with a lot of processes, this can use a lot of
1315 precious low memory, eventually leading to low memory being
1316 consumed by page tables. Setting this option will allow
1317 user-space 2nd level page tables to reside in high memory.
1319 config CPU_SW_DOMAIN_PAN
1320 bool "Enable use of CPU domains to implement privileged no-access"
1321 depends on MMU && !ARM_LPAE
1324 Increase kernel security by ensuring that normal kernel accesses
1325 are unable to access userspace addresses. This can help prevent
1326 use-after-free bugs becoming an exploitable privilege escalation
1327 by ensuring that magic values (such as LIST_POISON) will always
1328 fault when dereferenced.
1330 CPUs with low-vector mappings use a best-efforts implementation.
1331 Their lower 1MB needs to remain accessible for the vectors, but
1332 the remainder of userspace will become appropriately inaccessible.
1334 config HW_PERF_EVENTS
1338 config ARM_MODULE_PLTS
1339 bool "Use PLTs to allow module memory to spill over into vmalloc area"
1341 select KASAN_VMALLOC if KASAN
1344 Allocate PLTs when loading modules so that jumps and calls whose
1345 targets are too far away for their relative offsets to be encoded
1346 in the instructions themselves can be bounced via veneers in the
1347 module's PLT. This allows modules to be allocated in the generic
1348 vmalloc area after the dedicated module memory area has been
1349 exhausted. The modules will use slightly more memory, but after
1350 rounding up to page size, the actual memory footprint is usually
1353 Disabling this is usually safe for small single-platform
1354 configurations. If unsure, say y.
1356 config ARCH_FORCE_MAX_ORDER
1357 int "Order of maximal physically contiguous allocations"
1358 default "11" if SOC_AM33XX
1359 default "8" if SA1111
1362 The kernel page allocator limits the size of maximal physically
1363 contiguous allocations. The limit is called MAX_ORDER and it
1364 defines the maximal power of two of number of pages that can be
1365 allocated as a single contiguous block. This option allows
1366 overriding the default setting when ability to allocate very
1367 large blocks of physically contiguous memory is required.
1369 Don't change if unsure.
1371 config ALIGNMENT_TRAP
1372 def_bool CPU_CP15_MMU
1373 select HAVE_PROC_CPU if PROC_FS
1375 ARM processors cannot fetch/store information which is not
1376 naturally aligned on the bus, i.e., a 4 byte fetch must start at an
1377 address divisible by 4. On 32-bit ARM processors, these non-aligned
1378 fetch/store instructions will be emulated in software if you say
1379 here, which has a severe performance impact. This is necessary for
1380 correct operation of some network protocols. With an IP-only
1381 configuration it is safe to say N, otherwise say Y.
1383 config UACCESS_WITH_MEMCPY
1384 bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
1386 default y if CPU_FEROCEON
1388 Implement faster copy_to_user and clear_user methods for CPU
1389 cores where a 8-word STM instruction give significantly higher
1390 memory write throughput than a sequence of individual 32bit stores.
1392 A possible side effect is a slight increase in scheduling latency
1393 between threads sharing the same address space if they invoke
1394 such copy operations with large buffers.
1396 However, if the CPU data cache is using a write-allocate mode,
1397 this option is unlikely to provide any performance gain.
1400 bool "Enable paravirtualization code"
1402 This changes the kernel so it can modify itself when it is run
1403 under a hypervisor, potentially improving performance significantly
1404 over full virtualization.
1406 config PARAVIRT_TIME_ACCOUNTING
1407 bool "Paravirtual steal time accounting"
1410 Select this option to enable fine granularity task steal time
1411 accounting. Time spent executing other tasks in parallel with
1412 the current vCPU is discounted from the vCPU power. To account for
1413 that, there can be a small performance impact.
1415 If in doubt, say N here.
1422 bool "Xen guest support on ARM"
1423 depends on ARM && AEABI && OF
1424 depends on CPU_V7 && !CPU_V6
1425 depends on !GENERIC_ATOMIC64
1427 select ARCH_DMA_ADDR_T_64BIT
1433 Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
1435 config CC_HAVE_STACKPROTECTOR_TLS
1436 def_bool $(cc-option,-mtp=cp15 -mstack-protector-guard=tls -mstack-protector-guard-offset=0)
1438 config STACKPROTECTOR_PER_TASK
1439 bool "Use a unique stack canary value for each task"
1440 depends on STACKPROTECTOR && CURRENT_POINTER_IN_TPIDRURO && !XIP_DEFLATED_DATA
1441 depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS
1442 select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS
1445 Due to the fact that GCC uses an ordinary symbol reference from
1446 which to load the value of the stack canary, this value can only
1447 change at reboot time on SMP systems, and all tasks running in the
1448 kernel's address space are forced to use the same canary value for
1449 the entire duration that the system is up.
1451 Enable this option to switch to a different method that uses a
1452 different canary value for each task.
1459 bool "Flattened Device Tree support"
1463 Include support for flattened device tree machine descriptions.
1466 bool "Support for the traditional ATAGS boot data passing"
1469 This is the traditional way of passing data to the kernel at boot
1470 time. If you are solely relying on the flattened device tree (or
1471 the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
1472 to remove ATAGS support from your kernel binary.
1474 config DEPRECATED_PARAM_STRUCT
1475 bool "Provide old way to pass kernel parameters"
1478 This was deprecated in 2001 and announced to live on for 5 years.
1479 Some old boot loaders still use this way.
1481 # Compressed boot loader in ROM. Yes, we really want to ask about
1482 # TEXT and BSS so we preserve their values in the config files.
1483 config ZBOOT_ROM_TEXT
1484 hex "Compressed ROM boot loader base address"
1487 The physical address at which the ROM-able zImage is to be
1488 placed in the target. Platforms which normally make use of
1489 ROM-able zImage formats normally set this to a suitable
1490 value in their defconfig file.
1492 If ZBOOT_ROM is not enabled, this has no effect.
1494 config ZBOOT_ROM_BSS
1495 hex "Compressed ROM boot loader BSS address"
1498 The base address of an area of read/write memory in the target
1499 for the ROM-able zImage which must be available while the
1500 decompressor is running. It must be large enough to hold the
1501 entire decompressed kernel plus an additional 128 KiB.
1502 Platforms which normally make use of ROM-able zImage formats
1503 normally set this to a suitable value in their defconfig file.
1505 If ZBOOT_ROM is not enabled, this has no effect.
1508 bool "Compressed boot loader in ROM/flash"
1509 depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
1510 depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
1512 Say Y here if you intend to execute your compressed kernel image
1513 (zImage) directly from ROM or flash. If unsure, say N.
1515 config ARM_APPENDED_DTB
1516 bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
1519 With this option, the boot code will look for a device tree binary
1520 (DTB) appended to zImage
1521 (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
1523 This is meant as a backward compatibility convenience for those
1524 systems with a bootloader that can't be upgraded to accommodate
1525 the documented boot protocol using a device tree.
1527 Beware that there is very little in terms of protection against
1528 this option being confused by leftover garbage in memory that might
1529 look like a DTB header after a reboot if no actual DTB is appended
1530 to zImage. Do not leave this option active in a production kernel
1531 if you don't intend to always append a DTB. Proper passing of the
1532 location into r2 of a bootloader provided DTB is always preferable
1535 config ARM_ATAG_DTB_COMPAT
1536 bool "Supplement the appended DTB with traditional ATAG information"
1537 depends on ARM_APPENDED_DTB
1539 Some old bootloaders can't be updated to a DTB capable one, yet
1540 they provide ATAGs with memory configuration, the ramdisk address,
1541 the kernel cmdline string, etc. Such information is dynamically
1542 provided by the bootloader and can't always be stored in a static
1543 DTB. To allow a device tree enabled kernel to be used with such
1544 bootloaders, this option allows zImage to extract the information
1545 from the ATAG list and store it at run time into the appended DTB.
1548 prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
1549 default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1551 config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1552 bool "Use bootloader kernel arguments if available"
1554 Uses the command-line options passed by the boot loader instead of
1555 the device tree bootargs property. If the boot loader doesn't provide
1556 any, the device tree bootargs property will be used.
1558 config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
1559 bool "Extend with bootloader kernel arguments"
1561 The command-line arguments provided by the boot loader will be
1562 appended to the the device tree bootargs property.
1567 string "Default kernel command string"
1570 On some architectures (e.g. CATS), there is currently no way
1571 for the boot loader to pass arguments to the kernel. For these
1572 architectures, you should supply some command-line options at build
1573 time by entering them here. As a minimum, you should specify the
1574 memory size and the root device (e.g., mem=64M root=/dev/nfs).
1577 prompt "Kernel command line type" if CMDLINE != ""
1578 default CMDLINE_FROM_BOOTLOADER
1580 config CMDLINE_FROM_BOOTLOADER
1581 bool "Use bootloader kernel arguments if available"
1583 Uses the command-line options passed by the boot loader. If
1584 the boot loader doesn't provide any, the default kernel command
1585 string provided in CMDLINE will be used.
1587 config CMDLINE_EXTEND
1588 bool "Extend bootloader kernel arguments"
1590 The command-line arguments provided by the boot loader will be
1591 appended to the default kernel command string.
1593 config CMDLINE_FORCE
1594 bool "Always use the default kernel command string"
1596 Always use the default kernel command string, even if the boot
1597 loader passes other arguments to the kernel.
1598 This is useful if you cannot or don't want to change the
1599 command-line options your boot loader passes to the kernel.
1603 bool "Kernel Execute-In-Place from ROM"
1604 depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
1605 depends on !ARM_PATCH_IDIV && !ARM_PATCH_PHYS_VIRT && !SMP_ON_UP
1607 Execute-In-Place allows the kernel to run from non-volatile storage
1608 directly addressable by the CPU, such as NOR flash. This saves RAM
1609 space since the text section of the kernel is not loaded from flash
1610 to RAM. Read-write sections, such as the data section and stack,
1611 are still copied to RAM. The XIP kernel is not compressed since
1612 it has to run directly from flash, so it will take more space to
1613 store it. The flash address used to link the kernel object files,
1614 and for storing it, is configuration dependent. Therefore, if you
1615 say Y here, you must know the proper physical address where to
1616 store the kernel image depending on your own flash memory usage.
1618 Also note that the make target becomes "make xipImage" rather than
1619 "make zImage" or "make Image". The final kernel binary to put in
1620 ROM memory will be arch/arm/boot/xipImage.
1624 config XIP_PHYS_ADDR
1625 hex "XIP Kernel Physical Location"
1626 depends on XIP_KERNEL
1627 default "0x00080000"
1629 This is the physical address in your flash memory the kernel will
1630 be linked for and stored to. This address is dependent on your
1633 config XIP_DEFLATED_DATA
1634 bool "Store kernel .data section compressed in ROM"
1635 depends on XIP_KERNEL
1638 Before the kernel is actually executed, its .data section has to be
1639 copied to RAM from ROM. This option allows for storing that data
1640 in compressed form and decompressed to RAM rather than merely being
1641 copied, saving some precious ROM space. A possible drawback is a
1642 slightly longer boot delay.
1645 bool "Kexec system call (EXPERIMENTAL)"
1646 depends on (!SMP || PM_SLEEP_SMP)
1650 kexec is a system call that implements the ability to shutdown your
1651 current kernel, and to start another kernel. It is like a reboot
1652 but it is independent of the system firmware. And like a reboot
1653 you can start any kernel with it, not just Linux.
1655 It is an ongoing process to be certain the hardware in a machine
1656 is properly shutdown, so do not be surprised if this code does not
1657 initially work for you.
1660 bool "Export atags in procfs"
1661 depends on ATAGS && KEXEC
1664 Should the atags used to boot the kernel be exported in an "atags"
1665 file in procfs. Useful with kexec.
1668 bool "Build kdump crash kernel (EXPERIMENTAL)"
1670 Generate crash dump after being started by kexec. This should
1671 be normally only set in special crash dump kernels which are
1672 loaded in the main kernel with kexec-tools into a specially
1673 reserved region and then later executed after a crash by
1674 kdump/kexec. The crash dump kernel must be compiled to a
1675 memory address not used by the main kernel
1677 For more details see Documentation/admin-guide/kdump/kdump.rst
1679 config AUTO_ZRELADDR
1680 bool "Auto calculation of the decompressed kernel image address" if !ARCH_MULTIPLATFORM
1681 default !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
1683 ZRELADDR is the physical address where the decompressed kernel
1684 image will be placed. If AUTO_ZRELADDR is selected, the address
1685 will be determined at run-time, either by masking the current IP
1686 with 0xf8000000, or, if invalid, from the DTB passed in r2.
1687 This assumes the zImage being placed in the first 128MB from
1694 bool "UEFI runtime support"
1695 depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
1697 select EFI_PARAMS_FROM_FDT
1699 select EFI_GENERIC_STUB
1700 select EFI_RUNTIME_WRAPPERS
1702 This option provides support for runtime services provided
1703 by UEFI firmware (such as non-volatile variables, realtime
1704 clock, and platform reset). A UEFI stub is also provided to
1705 allow the kernel to be booted as an EFI application. This
1706 is only useful for kernels that may run on systems that have
1710 bool "Enable support for SMBIOS (DMI) tables"
1714 This enables SMBIOS/DMI feature for systems.
1716 This option is only useful on systems that have UEFI firmware.
1717 However, even with this option, the resultant kernel should
1718 continue to boot on existing non-UEFI platforms.
1720 NOTE: This does *NOT* enable or encourage the use of DMI quirks,
1721 i.e., the the practice of identifying the platform via DMI to
1722 decide whether certain workarounds for buggy hardware and/or
1723 firmware need to be enabled. This would require the DMI subsystem
1724 to be enabled much earlier than we do on ARM, which is non-trivial.
1728 menu "CPU Power Management"
1730 source "drivers/cpufreq/Kconfig"
1732 source "drivers/cpuidle/Kconfig"
1736 menu "Floating point emulation"
1738 comment "At least one emulation must be selected"
1741 bool "NWFPE math emulation"
1742 depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
1744 Say Y to include the NWFPE floating point emulator in the kernel.
1745 This is necessary to run most binaries. Linux does not currently
1746 support floating point hardware so you need to say Y here even if
1747 your machine has an FPA or floating point co-processor podule.
1749 You may say N here if you are going to load the Acorn FPEmulator
1750 early in the bootup.
1753 bool "Support extended precision"
1754 depends on FPE_NWFPE
1756 Say Y to include 80-bit support in the kernel floating-point
1757 emulator. Otherwise, only 32 and 64-bit support is compiled in.
1758 Note that gcc does not generate 80-bit operations by default,
1759 so in most cases this option only enlarges the size of the
1760 floating point emulator without any good reason.
1762 You almost surely want to say N here.
1765 bool "FastFPE math emulation (EXPERIMENTAL)"
1766 depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
1768 Say Y here to include the FAST floating point emulator in the kernel.
1769 This is an experimental much faster emulator which now also has full
1770 precision for the mantissa. It does not support any exceptions.
1771 It is very simple, and approximately 3-6 times faster than NWFPE.
1773 It should be sufficient for most programs. It may be not suitable
1774 for scientific calculations, but you have to check this for yourself.
1775 If you do not feel you need a faster FP emulation you should better
1779 bool "VFP-format floating point maths"
1780 depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
1782 Say Y to include VFP support code in the kernel. This is needed
1783 if your hardware includes a VFP unit.
1785 Please see <file:Documentation/arch/arm/vfp/release-notes.rst> for
1786 release notes and additional status information.
1788 Say N if your target does not have VFP hardware.
1796 bool "Advanced SIMD (NEON) Extension support"
1797 depends on VFPv3 && CPU_V7
1799 Say Y to include support code for NEON, the ARMv7 Advanced SIMD
1802 config KERNEL_MODE_NEON
1803 bool "Support for NEON in kernel mode"
1804 depends on NEON && AEABI
1806 Say Y to include support for NEON in kernel mode.
1810 menu "Power management options"
1812 source "kernel/power/Kconfig"
1814 config ARCH_SUSPEND_POSSIBLE
1815 depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
1816 CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
1819 config ARM_CPU_SUSPEND
1820 def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
1821 depends on ARCH_SUSPEND_POSSIBLE
1823 config ARCH_HIBERNATION_POSSIBLE
1826 default y if ARCH_SUSPEND_POSSIBLE
1830 source "arch/arm/Kconfig.assembler"