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_CURRENT_STACK_POINTER
9 select ARCH_HAS_DEBUG_VIRTUAL if MMU
10 select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
11 select ARCH_HAS_ELF_RANDOMIZE
12 select ARCH_HAS_FORTIFY_SOURCE
13 select ARCH_HAS_KEEPINITRD
15 select ARCH_HAS_MEMBARRIER_SYNC_CORE
16 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
17 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
18 select ARCH_HAS_PHYS_TO_DMA
19 select ARCH_HAS_SETUP_DMA_OPS
20 select ARCH_HAS_SET_MEMORY
21 select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
22 select ARCH_HAS_STRICT_MODULE_RWX if MMU
23 select ARCH_HAS_SYNC_DMA_FOR_DEVICE if SWIOTLB || !MMU
24 select ARCH_HAS_SYNC_DMA_FOR_CPU if SWIOTLB || !MMU
25 select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
26 select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
27 select ARCH_HAVE_CUSTOM_GPIO_H
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_MIGHT_HAVE_PC_PARPORT
32 select ARCH_NO_SG_CHAIN if !ARM_HAS_SG_CHAIN
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 CLONE_BACKWARDS
47 select CPU_PM if SUSPEND || CPU_IDLE
48 select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
49 select DMA_DECLARE_COHERENT
50 select DMA_GLOBAL_POOL if !MMU
52 select DMA_NONCOHERENT_MMAP if MMU
54 select EDAC_ATOMIC_SCRUB
55 select GENERIC_ALLOCATOR
56 select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
57 select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
58 select GENERIC_CLOCKEVENTS_BROADCAST if SMP
59 select GENERIC_IRQ_IPI if SMP
60 select GENERIC_CPU_AUTOPROBE
61 select GENERIC_EARLY_IOREMAP
62 select GENERIC_IDLE_POLL_SETUP
63 select GENERIC_IRQ_MULTI_HANDLER
64 select GENERIC_IRQ_PROBE
65 select GENERIC_IRQ_SHOW
66 select GENERIC_IRQ_SHOW_LEVEL
67 select GENERIC_LIB_DEVMEM_IS_ALLOWED
68 select GENERIC_PCI_IOMAP
69 select GENERIC_SCHED_CLOCK
70 select GENERIC_SMP_IDLE_THREAD
71 select HARDIRQS_SW_RESEND
72 select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
73 select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
74 select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
75 select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
76 select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
77 select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
78 select HAVE_ARCH_MMAP_RND_BITS if MMU
79 select HAVE_ARCH_PFN_VALID
80 select HAVE_ARCH_SECCOMP
81 select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
82 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
83 select HAVE_ARCH_TRACEHOOK
84 select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
85 select HAVE_ARM_SMCCC if CPU_V7
86 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
87 select HAVE_CONTEXT_TRACKING
88 select HAVE_C_RECORDMCOUNT
89 select HAVE_BUILDTIME_MCOUNT_SORT
90 select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
91 select HAVE_DMA_CONTIGUOUS if MMU
92 select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
93 select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
94 select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
95 select HAVE_EXIT_THREAD
96 select HAVE_FAST_GUP if ARM_LPAE
97 select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
98 select HAVE_FUNCTION_GRAPH_TRACER
99 select HAVE_FUNCTION_TRACER if !XIP_KERNEL
100 select HAVE_GCC_PLUGINS
101 select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
102 select HAVE_IRQ_TIME_ACCOUNTING
103 select HAVE_KERNEL_GZIP
104 select HAVE_KERNEL_LZ4
105 select HAVE_KERNEL_LZMA
106 select HAVE_KERNEL_LZO
107 select HAVE_KERNEL_XZ
108 select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
109 select HAVE_KRETPROBES if HAVE_KPROBES
110 select HAVE_MOD_ARCH_SPECIFIC
112 select HAVE_OPTPROBES if !THUMB2_KERNEL
113 select HAVE_PERF_EVENTS
114 select HAVE_PERF_REGS
115 select HAVE_PERF_USER_STACK_DUMP
116 select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
117 select HAVE_REGS_AND_STACK_ACCESS_API
119 select HAVE_STACKPROTECTOR
120 select HAVE_SYSCALL_TRACEPOINTS
122 select HAVE_VIRT_CPU_ACCOUNTING_GEN
123 select IRQ_FORCED_THREADING
124 select MODULES_USE_ELF_REL
125 select NEED_DMA_MAP_STATE
126 select OF_EARLY_FLATTREE if OF
128 select OLD_SIGSUSPEND3
129 select PCI_SYSCALL if PCI
130 select PERF_USE_VMALLOC
132 select SYS_SUPPORTS_APM_EMULATION
133 select THREAD_INFO_IN_TASK
134 select HAVE_ARCH_VMAP_STACK if MMU && ARM_HAS_GROUP_RELOCS
135 select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
136 # Above selects are sorted alphabetically; please add new ones
137 # according to that. Thanks.
139 The ARM series is a line of low-power-consumption RISC chip designs
140 licensed by ARM Ltd and targeted at embedded applications and
141 handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
142 manufactured, but legacy ARM-based PC hardware remains popular in
143 Europe. There is an ARM Linux project with a web page at
144 <http://www.arm.linux.org.uk/>.
146 config ARM_HAS_GROUP_RELOCS
148 depends on !LD_IS_LLD || LLD_VERSION >= 140000
149 depends on !COMPILE_TEST
151 Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
152 relocations, which have been around for a long time, but were not
153 supported in LLD until version 14. The combined range is -/+ 256 MiB,
154 which is usually sufficient, but not for allyesconfig, so we disable
155 this feature when doing compile testing.
157 config ARM_HAS_SG_CHAIN
160 config ARM_DMA_USE_IOMMU
162 select ARM_HAS_SG_CHAIN
163 select NEED_SG_DMA_LENGTH
167 config ARM_DMA_IOMMU_ALIGNMENT
168 int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
172 DMA mapping framework by default aligns all buffers to the smallest
173 PAGE_SIZE order which is greater than or equal to the requested buffer
174 size. This works well for buffers up to a few hundreds kilobytes, but
175 for larger buffers it just a waste of address space. Drivers which has
176 relatively small addressing window (like 64Mib) might run out of
177 virtual space with just a few allocations.
179 With this parameter you can specify the maximum PAGE_SIZE order for
180 DMA IOMMU buffers. Larger buffers will be aligned only to this
181 specified order. The order is expressed as a power of two multiplied
186 config SYS_SUPPORTS_APM_EMULATION
191 select GENERIC_ALLOCATOR
202 config STACKTRACE_SUPPORT
206 config LOCKDEP_SUPPORT
210 config ARCH_HAS_ILOG2_U32
213 config ARCH_HAS_ILOG2_U64
216 config ARCH_HAS_BANDGAP
219 config FIX_EARLYCON_MEM
222 config GENERIC_HWEIGHT
226 config GENERIC_CALIBRATE_DELAY
230 config ARCH_MAY_HAVE_PC_FDC
233 config ARCH_SUPPORTS_UPROBES
236 config GENERIC_ISA_DMA
245 config ARM_PATCH_PHYS_VIRT
246 bool "Patch physical to virtual translations at runtime" if EMBEDDED
248 depends on !XIP_KERNEL && MMU
250 Patch phys-to-virt and virt-to-phys translation functions at
251 boot and module load time according to the position of the
252 kernel in system memory.
254 This can only be used with non-XIP MMU kernels where the base
255 of physical memory is at a 2 MiB boundary.
257 Only disable this option if you know that you do not require
258 this feature (eg, building a kernel for a single machine) and
259 you need to shrink the kernel to the minimal size.
261 config NEED_MACH_IO_H
264 Select this when mach/io.h is required to provide special
265 definitions for this platform. The need for mach/io.h should
266 be avoided when possible.
268 config NEED_MACH_MEMORY_H
271 Select this when mach/memory.h is required to provide special
272 definitions for this platform. The need for mach/memory.h should
273 be avoided when possible.
276 hex "Physical address of main memory" if MMU
277 depends on !ARM_PATCH_PHYS_VIRT
278 default DRAM_BASE if !MMU
279 default 0x00000000 if ARCH_FOOTBRIDGE
280 default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
281 default 0x30000000 if ARCH_S3C24XX
282 default 0xa0000000 if ARCH_IOP32X || ARCH_PXA
283 default 0xc0000000 if ARCH_EP93XX || ARCH_SA1100
286 Please provide the physical address corresponding to the
287 location of main memory in your system.
293 config PGTABLE_LEVELS
295 default 3 if ARM_LPAE
301 bool "MMU-based Paged Memory Management Support"
304 Select if you want MMU-based virtualised addressing space
305 support by paged memory management. If unsure, say 'Y'.
307 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
327 # The "ARM system type" choice list is ordered alphabetically by option
328 # text. Please add new entries in the option alphabetic order.
331 prompt "ARM system type"
333 default ARCH_MULTIPLATFORM
335 config ARCH_MULTIPLATFORM
336 bool "Allow multiple platforms to be selected"
337 select ARCH_FLATMEM_ENABLE
338 select ARCH_SPARSEMEM_ENABLE
339 select ARCH_SELECT_MEMORY_MODEL
340 select ARM_HAS_SG_CHAIN
341 select ARM_PATCH_PHYS_VIRT
346 select PCI_DOMAINS_GENERIC if PCI
352 select ARCH_SPARSEMEM_ENABLE
354 imply ARM_PATCH_PHYS_VIRT
362 This enables support for the Cirrus EP93xx series of CPUs.
364 config ARCH_FOOTBRIDGE
368 select NEED_MACH_MEMORY_H
370 Support for systems based on the DC21285 companion chip
371 ("FootBridge"), such as the Simtec CATS and the Rebel NetWinder.
381 Support for Intel's 80219 and IOP32X (XScale) family of
386 select ARCH_SUPPORTS_BIG_ENDIAN
387 select ARM_PATCH_PHYS_VIRT
395 select USB_EHCI_BIG_ENDIAN_DESC
396 select USB_EHCI_BIG_ENDIAN_MMIO
398 Support for Intel's IXP4XX (XScale) family of processors.
408 select PLAT_ORION_LEGACY
410 select PM_GENERIC_DOMAINS if PM
412 Support for the Marvell Dove SoC 88AP510
415 bool "PXA2xx/PXA3xx-based"
417 select ARM_CPU_SUSPEND if PM
423 select CPU_XSCALE if !CPU_XSC3
430 Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
434 depends on !CC_IS_CLANG && GCC_VERSION < 90100 && GCC_VERSION >= 60000
436 select ARCH_MAY_HAVE_PC_FDC
437 select ARCH_SPARSEMEM_ENABLE
438 select ARM_HAS_SG_CHAIN
441 select HAVE_PATA_PLATFORM
443 select LEGACY_TIMER_TICK
444 select NEED_MACH_IO_H
445 select NEED_MACH_MEMORY_H
448 On the Acorn Risc-PC, Linux can support the internal IDE disk and
449 CD-ROM interface, serial and parallel port, and the floppy drive.
454 select ARCH_SPARSEMEM_ENABLE
457 select TIMER_OF if OF
464 select NEED_MACH_MEMORY_H
467 Support for StrongARM 11x0 based boards.
470 bool "Samsung S3C24XX SoCs"
472 select CLKSRC_SAMSUNG_PWM
475 select NEED_MACH_IO_H
476 select S3C2410_WATCHDOG
481 Samsung S3C2410, S3C2412, S3C2413, S3C2416, S3C2440, S3C2442, S3C2443
482 and S3C2450 SoCs based systems, such as the Simtec Electronics BAST
483 (<http://www.simtec.co.uk/products/EB110ITX/>), the IPAQ 1940 or the
484 Samsung SMDK2410 development board (and derivatives).
490 select GENERIC_IRQ_CHIP
492 select HAVE_LEGACY_CLK
494 select NEED_MACH_IO_H if PCCARD
495 select NEED_MACH_MEMORY_H
498 Support for older TI OMAP1 (omap7xx, omap15xx or omap16xx)
502 menu "Multiple platform selection"
503 depends on ARCH_MULTIPLATFORM
505 comment "CPU Core family selection"
508 bool "ARMv4 based platforms (FA526)"
509 depends on !ARCH_MULTI_V6_V7
510 select ARCH_MULTI_V4_V5
513 config ARCH_MULTI_V4T
514 bool "ARMv4T based platforms (ARM720T, ARM920T, ...)"
515 depends on !ARCH_MULTI_V6_V7
516 select ARCH_MULTI_V4_V5
517 select CPU_ARM920T if !(CPU_ARM7TDMI || CPU_ARM720T || \
518 CPU_ARM740T || CPU_ARM9TDMI || CPU_ARM922T || \
519 CPU_ARM925T || CPU_ARM940T)
522 bool "ARMv5 based platforms (ARM926T, XSCALE, PJ1, ...)"
523 depends on !ARCH_MULTI_V6_V7
524 select ARCH_MULTI_V4_V5
525 select CPU_ARM926T if !(CPU_ARM946E || CPU_ARM1020 || \
526 CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || \
527 CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_FEROCEON)
529 config ARCH_MULTI_V4_V5
533 bool "ARMv6 based platforms (ARM11)"
534 select ARCH_MULTI_V6_V7
538 bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)"
540 select ARCH_MULTI_V6_V7
544 config ARCH_MULTI_V6_V7
546 select MIGHT_HAVE_CACHE_L2X0
548 config ARCH_MULTI_CPU_AUTO
549 def_bool !(ARCH_MULTI_V4 || ARCH_MULTI_V4T || ARCH_MULTI_V6_V7)
555 bool "Dummy Virtual Machine"
556 depends on ARCH_MULTI_V7
559 select ARM_GIC_V2M if PCI
561 select ARM_GIC_V3_ITS if PCI
563 select HAVE_ARM_ARCH_TIMER
564 select ARCH_SUPPORTS_BIG_ENDIAN
567 bool "Airoha SoC Support"
568 depends on ARCH_MULTI_V7
573 select HAVE_ARM_ARCH_TIMER
576 Support for Airoha EN7523 SoCs
579 # This is sorted alphabetically by mach-* pathname. However, plat-*
580 # Kconfigs may be included either alphabetically (according to the
581 # plat- suffix) or along side the corresponding mach-* source.
583 source "arch/arm/mach-actions/Kconfig"
585 source "arch/arm/mach-alpine/Kconfig"
587 source "arch/arm/mach-artpec/Kconfig"
589 source "arch/arm/mach-asm9260/Kconfig"
591 source "arch/arm/mach-aspeed/Kconfig"
593 source "arch/arm/mach-at91/Kconfig"
595 source "arch/arm/mach-axxia/Kconfig"
597 source "arch/arm/mach-bcm/Kconfig"
599 source "arch/arm/mach-berlin/Kconfig"
601 source "arch/arm/mach-clps711x/Kconfig"
603 source "arch/arm/mach-cns3xxx/Kconfig"
605 source "arch/arm/mach-davinci/Kconfig"
607 source "arch/arm/mach-digicolor/Kconfig"
609 source "arch/arm/mach-dove/Kconfig"
611 source "arch/arm/mach-ep93xx/Kconfig"
613 source "arch/arm/mach-exynos/Kconfig"
615 source "arch/arm/mach-footbridge/Kconfig"
617 source "arch/arm/mach-gemini/Kconfig"
619 source "arch/arm/mach-highbank/Kconfig"
621 source "arch/arm/mach-hisi/Kconfig"
623 source "arch/arm/mach-imx/Kconfig"
625 source "arch/arm/mach-integrator/Kconfig"
627 source "arch/arm/mach-iop32x/Kconfig"
629 source "arch/arm/mach-ixp4xx/Kconfig"
631 source "arch/arm/mach-keystone/Kconfig"
633 source "arch/arm/mach-lpc32xx/Kconfig"
635 source "arch/arm/mach-mediatek/Kconfig"
637 source "arch/arm/mach-meson/Kconfig"
639 source "arch/arm/mach-milbeaut/Kconfig"
641 source "arch/arm/mach-mmp/Kconfig"
643 source "arch/arm/mach-moxart/Kconfig"
645 source "arch/arm/mach-mstar/Kconfig"
647 source "arch/arm/mach-mv78xx0/Kconfig"
649 source "arch/arm/mach-mvebu/Kconfig"
651 source "arch/arm/mach-mxs/Kconfig"
653 source "arch/arm/mach-nomadik/Kconfig"
655 source "arch/arm/mach-npcm/Kconfig"
657 source "arch/arm/mach-nspire/Kconfig"
659 source "arch/arm/plat-omap/Kconfig"
661 source "arch/arm/mach-omap1/Kconfig"
663 source "arch/arm/mach-omap2/Kconfig"
665 source "arch/arm/mach-orion5x/Kconfig"
667 source "arch/arm/mach-oxnas/Kconfig"
669 source "arch/arm/mach-pxa/Kconfig"
670 source "arch/arm/plat-pxa/Kconfig"
672 source "arch/arm/mach-qcom/Kconfig"
674 source "arch/arm/mach-rda/Kconfig"
676 source "arch/arm/mach-realtek/Kconfig"
678 source "arch/arm/mach-realview/Kconfig"
680 source "arch/arm/mach-rockchip/Kconfig"
682 source "arch/arm/mach-s3c/Kconfig"
684 source "arch/arm/mach-s5pv210/Kconfig"
686 source "arch/arm/mach-sa1100/Kconfig"
688 source "arch/arm/mach-shmobile/Kconfig"
690 source "arch/arm/mach-socfpga/Kconfig"
692 source "arch/arm/mach-spear/Kconfig"
694 source "arch/arm/mach-sti/Kconfig"
696 source "arch/arm/mach-stm32/Kconfig"
698 source "arch/arm/mach-sunxi/Kconfig"
700 source "arch/arm/mach-tegra/Kconfig"
702 source "arch/arm/mach-uniphier/Kconfig"
704 source "arch/arm/mach-ux500/Kconfig"
706 source "arch/arm/mach-versatile/Kconfig"
708 source "arch/arm/mach-vexpress/Kconfig"
710 source "arch/arm/mach-vt8500/Kconfig"
712 source "arch/arm/mach-zynq/Kconfig"
714 # ARMv7-M architecture
716 bool "NXP LPC18xx/LPC43xx"
717 depends on ARM_SINGLE_ARMV7M
718 select ARCH_HAS_RESET_CONTROLLER
720 select CLKSRC_LPC32XX
723 Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
724 high performance microcontrollers.
727 bool "ARM MPS2 platform"
728 depends on ARM_SINGLE_ARMV7M
732 Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
733 with a range of available cores like Cortex-M3/M4/M7.
735 Please, note that depends which Application Note is used memory map
736 for the platform may vary, so adjustment of RAM base might be needed.
738 # Definitions to make life easier
749 select GENERIC_IRQ_CHIP
752 config PLAT_ORION_LEGACY
759 config PLAT_VERSATILE
762 source "arch/arm/mm/Kconfig"
765 bool "Enable iWMMXt support"
766 depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
767 default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B
769 Enable support for iWMMXt context switching at run time if
770 running on a CPU that supports it.
773 source "arch/arm/Kconfig-nommu"
776 config PJ4B_ERRATA_4742
777 bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
778 depends on CPU_PJ4B && MACH_ARMADA_370
781 When coming out of either a Wait for Interrupt (WFI) or a Wait for
782 Event (WFE) IDLE states, a specific timing sensitivity exists between
783 the retiring WFI/WFE instructions and the newly issued subsequent
784 instructions. This sensitivity can result in a CPU hang scenario.
786 The software must insert either a Data Synchronization Barrier (DSB)
787 or Data Memory Barrier (DMB) command immediately after the WFI/WFE
790 config ARM_ERRATA_326103
791 bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
794 Executing a SWP instruction to read-only memory does not set bit 11
795 of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
796 treat the access as a read, preventing a COW from occurring and
797 causing the faulting task to livelock.
799 config ARM_ERRATA_411920
800 bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
801 depends on CPU_V6 || CPU_V6K
803 Invalidation of the Instruction Cache operation can
804 fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
805 It does not affect the MPCore. This option enables the ARM Ltd.
806 recommended workaround.
808 config ARM_ERRATA_430973
809 bool "ARM errata: Stale prediction on replaced interworking branch"
812 This option enables the workaround for the 430973 Cortex-A8
813 r1p* erratum. If a code sequence containing an ARM/Thumb
814 interworking branch is replaced with another code sequence at the
815 same virtual address, whether due to self-modifying code or virtual
816 to physical address re-mapping, Cortex-A8 does not recover from the
817 stale interworking branch prediction. This results in Cortex-A8
818 executing the new code sequence in the incorrect ARM or Thumb state.
819 The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
820 and also flushes the branch target cache at every context switch.
821 Note that setting specific bits in the ACTLR register may not be
822 available in non-secure mode.
824 config ARM_ERRATA_458693
825 bool "ARM errata: Processor deadlock when a false hazard is created"
827 depends on !ARCH_MULTIPLATFORM
829 This option enables the workaround for the 458693 Cortex-A8 (r2p0)
830 erratum. For very specific sequences of memory operations, it is
831 possible for a hazard condition intended for a cache line to instead
832 be incorrectly associated with a different cache line. This false
833 hazard might then cause a processor deadlock. The workaround enables
834 the L1 caching of the NEON accesses and disables the PLD instruction
835 in the ACTLR register. Note that setting specific bits in the ACTLR
836 register may not be available in non-secure mode.
838 config ARM_ERRATA_460075
839 bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
841 depends on !ARCH_MULTIPLATFORM
843 This option enables the workaround for the 460075 Cortex-A8 (r2p0)
844 erratum. Any asynchronous access to the L2 cache may encounter a
845 situation in which recent store transactions to the L2 cache are lost
846 and overwritten with stale memory contents from external memory. The
847 workaround disables the write-allocate mode for the L2 cache via the
848 ACTLR register. Note that setting specific bits in the ACTLR register
849 may not be available in non-secure mode.
851 config ARM_ERRATA_742230
852 bool "ARM errata: DMB operation may be faulty"
853 depends on CPU_V7 && SMP
854 depends on !ARCH_MULTIPLATFORM
856 This option enables the workaround for the 742230 Cortex-A9
857 (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
858 between two write operations may not ensure the correct visibility
859 ordering of the two writes. This workaround sets a specific bit in
860 the diagnostic register of the Cortex-A9 which causes the DMB
861 instruction to behave as a DSB, ensuring the correct behaviour of
864 config ARM_ERRATA_742231
865 bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
866 depends on CPU_V7 && SMP
867 depends on !ARCH_MULTIPLATFORM
869 This option enables the workaround for the 742231 Cortex-A9
870 (r2p0..r2p2) erratum. Under certain conditions, specific to the
871 Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
872 accessing some data located in the same cache line, may get corrupted
873 data due to bad handling of the address hazard when the line gets
874 replaced from one of the CPUs at the same time as another CPU is
875 accessing it. This workaround sets specific bits in the diagnostic
876 register of the Cortex-A9 which reduces the linefill issuing
877 capabilities of the processor.
879 config ARM_ERRATA_643719
880 bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
881 depends on CPU_V7 && SMP
884 This option enables the workaround for the 643719 Cortex-A9 (prior to
885 r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
886 register returns zero when it should return one. The workaround
887 corrects this value, ensuring cache maintenance operations which use
888 it behave as intended and avoiding data corruption.
890 config ARM_ERRATA_720789
891 bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
894 This option enables the workaround for the 720789 Cortex-A9 (prior to
895 r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
896 broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
897 As a consequence of this erratum, some TLB entries which should be
898 invalidated are not, resulting in an incoherency in the system page
899 tables. The workaround changes the TLB flushing routines to invalidate
900 entries regardless of the ASID.
902 config ARM_ERRATA_743622
903 bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
905 depends on !ARCH_MULTIPLATFORM
907 This option enables the workaround for the 743622 Cortex-A9
908 (r2p*) erratum. Under very rare conditions, a faulty
909 optimisation in the Cortex-A9 Store Buffer may lead to data
910 corruption. This workaround sets a specific bit in the diagnostic
911 register of the Cortex-A9 which disables the Store Buffer
912 optimisation, preventing the defect from occurring. This has no
913 visible impact on the overall performance or power consumption of the
916 config ARM_ERRATA_751472
917 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
919 depends on !ARCH_MULTIPLATFORM
921 This option enables the workaround for the 751472 Cortex-A9 (prior
922 to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
923 completion of a following broadcasted operation if the second
924 operation is received by a CPU before the ICIALLUIS has completed,
925 potentially leading to corrupted entries in the cache or TLB.
927 config ARM_ERRATA_754322
928 bool "ARM errata: possible faulty MMU translations following an ASID switch"
931 This option enables the workaround for the 754322 Cortex-A9 (r2p*,
932 r3p*) erratum. A speculative memory access may cause a page table walk
933 which starts prior to an ASID switch but completes afterwards. This
934 can populate the micro-TLB with a stale entry which may be hit with
935 the new ASID. This workaround places two dsb instructions in the mm
936 switching code so that no page table walks can cross the ASID switch.
938 config ARM_ERRATA_754327
939 bool "ARM errata: no automatic Store Buffer drain"
940 depends on CPU_V7 && SMP
942 This option enables the workaround for the 754327 Cortex-A9 (prior to
943 r2p0) erratum. The Store Buffer does not have any automatic draining
944 mechanism and therefore a livelock may occur if an external agent
945 continuously polls a memory location waiting to observe an update.
946 This workaround defines cpu_relax() as smp_mb(), preventing correctly
947 written polling loops from denying visibility of updates to memory.
949 config ARM_ERRATA_364296
950 bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
953 This options enables the workaround for the 364296 ARM1136
954 r0p2 erratum (possible cache data corruption with
955 hit-under-miss enabled). It sets the undocumented bit 31 in
956 the auxiliary control register and the FI bit in the control
957 register, thus disabling hit-under-miss without putting the
958 processor into full low interrupt latency mode. ARM11MPCore
961 config ARM_ERRATA_764369
962 bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
963 depends on CPU_V7 && SMP
965 This option enables the workaround for erratum 764369
966 affecting Cortex-A9 MPCore with two or more processors (all
967 current revisions). Under certain timing circumstances, a data
968 cache line maintenance operation by MVA targeting an Inner
969 Shareable memory region may fail to proceed up to either the
970 Point of Coherency or to the Point of Unification of the
971 system. This workaround adds a DSB instruction before the
972 relevant cache maintenance functions and sets a specific bit
973 in the diagnostic control register of the SCU.
975 config ARM_ERRATA_764319
976 bool "ARM errata: Read to DBGPRSR and DBGOSLSR may generate Undefined instruction"
979 This option enables the workaround for the 764319 Cortex A-9 erratum.
980 CP14 read accesses to the DBGPRSR and DBGOSLSR registers generate an
981 unexpected Undefined Instruction exception when the DBGSWENABLE
982 external pin is set to 0, even when the CP14 accesses are performed
983 from a privileged mode. This work around catches the exception in a
984 way the kernel does not stop execution.
986 config ARM_ERRATA_775420
987 bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
990 This option enables the workaround for the 775420 Cortex-A9 (r2p2,
991 r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
992 operation aborts with MMU exception, it might cause the processor
993 to deadlock. This workaround puts DSB before executing ISB if
994 an abort may occur on cache maintenance.
996 config ARM_ERRATA_798181
997 bool "ARM errata: TLBI/DSB failure on Cortex-A15"
998 depends on CPU_V7 && SMP
1000 On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
1001 adequately shooting down all use of the old entries. This
1002 option enables the Linux kernel workaround for this erratum
1003 which sends an IPI to the CPUs that are running the same ASID
1004 as the one being invalidated.
1006 config ARM_ERRATA_773022
1007 bool "ARM errata: incorrect instructions may be executed from loop buffer"
1010 This option enables the workaround for the 773022 Cortex-A15
1011 (up to r0p4) erratum. In certain rare sequences of code, the
1012 loop buffer may deliver incorrect instructions. This
1013 workaround disables the loop buffer to avoid the erratum.
1015 config ARM_ERRATA_818325_852422
1016 bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
1019 This option enables the workaround for:
1020 - Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
1021 instruction might deadlock. Fixed in r0p1.
1022 - Cortex-A12 852422: Execution of a sequence of instructions might
1023 lead to either a data corruption or a CPU deadlock. Not fixed in
1024 any Cortex-A12 cores yet.
1025 This workaround for all both errata involves setting bit[12] of the
1026 Feature Register. This bit disables an optimisation applied to a
1027 sequence of 2 instructions that use opposing condition codes.
1029 config ARM_ERRATA_821420
1030 bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
1033 This option enables the workaround for the 821420 Cortex-A12
1034 (all revs) erratum. In very rare timing conditions, a sequence
1035 of VMOV to Core registers instructions, for which the second
1036 one is in the shadow of a branch or abort, can lead to a
1037 deadlock when the VMOV instructions are issued out-of-order.
1039 config ARM_ERRATA_825619
1040 bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
1043 This option enables the workaround for the 825619 Cortex-A12
1044 (all revs) erratum. Within rare timing constraints, executing a
1045 DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
1046 and Device/Strongly-Ordered loads and stores might cause deadlock
1048 config ARM_ERRATA_857271
1049 bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
1052 This option enables the workaround for the 857271 Cortex-A12
1053 (all revs) erratum. Under very rare timing conditions, the CPU might
1054 hang. The workaround is expected to have a < 1% performance impact.
1056 config ARM_ERRATA_852421
1057 bool "ARM errata: A17: DMB ST might fail to create order between stores"
1060 This option enables the workaround for the 852421 Cortex-A17
1061 (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
1062 execution of a DMB ST instruction might fail to properly order
1063 stores from GroupA and stores from GroupB.
1065 config ARM_ERRATA_852423
1066 bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
1069 This option enables the workaround for:
1070 - Cortex-A17 852423: Execution of a sequence of instructions might
1071 lead to either a data corruption or a CPU deadlock. Not fixed in
1072 any Cortex-A17 cores yet.
1073 This is identical to Cortex-A12 erratum 852422. It is a separate
1074 config option from the A12 erratum due to the way errata are checked
1077 config ARM_ERRATA_857272
1078 bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
1081 This option enables the workaround for the 857272 Cortex-A17 erratum.
1082 This erratum is not known to be fixed in any A17 revision.
1083 This is identical to Cortex-A12 erratum 857271. It is a separate
1084 config option from the A12 erratum due to the way errata are checked
1089 source "arch/arm/common/Kconfig"
1096 Find out whether you have ISA slots on your motherboard. ISA is the
1097 name of a bus system, i.e. the way the CPU talks to the other stuff
1098 inside your box. Other bus systems are PCI, EISA, MicroChannel
1099 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1100 newer boards don't support it. If you have ISA, say Y, otherwise N.
1102 # Select ISA DMA controller support
1107 # Select ISA DMA interface
1111 config PCI_NANOENGINE
1112 bool "BSE nanoEngine PCI support"
1113 depends on SA1100_NANOENGINE
1115 Enable PCI on the BSE nanoEngine board.
1117 config ARM_ERRATA_814220
1118 bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
1121 The v7 ARM states that all cache and branch predictor maintenance
1122 operations that do not specify an address execute, relative to
1123 each other, in program order.
1124 However, because of this erratum, an L2 set/way cache maintenance
1125 operation can overtake an L1 set/way cache maintenance operation.
1126 This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
1131 menu "Kernel Features"
1136 This option should be selected by machines which have an SMP-
1139 The only effect of this option is to make the SMP-related
1140 options available to the user for configuration.
1143 bool "Symmetric Multi-Processing"
1144 depends on CPU_V6K || CPU_V7
1146 depends on MMU || ARM_MPU
1149 This enables support for systems with more than one CPU. If you have
1150 a system with only one CPU, say N. If you have a system with more
1151 than one CPU, say Y.
1153 If you say N here, the kernel will run on uni- and multiprocessor
1154 machines, but will use only one CPU of a multiprocessor machine. If
1155 you say Y here, the kernel will run on many, but not all,
1156 uniprocessor machines. On a uniprocessor machine, the kernel
1157 will run faster if you say N here.
1159 See also <file:Documentation/x86/i386/IO-APIC.rst>,
1160 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
1161 <http://tldp.org/HOWTO/SMP-HOWTO.html>.
1163 If you don't know what to do here, say N.
1166 bool "Allow booting SMP kernel on uniprocessor systems"
1167 depends on SMP && !XIP_KERNEL && MMU
1170 SMP kernels contain instructions which fail on non-SMP processors.
1171 Enabling this option allows the kernel to modify itself to make
1172 these instructions safe. Disabling it allows about 1K of space
1175 If you don't know what to do here, say Y.
1178 config CURRENT_POINTER_IN_TPIDRURO
1180 depends on CPU_32v6K && !CPU_V6
1184 select HAVE_IRQ_EXIT_ON_IRQ_STACK
1185 select HAVE_SOFTIRQ_ON_OWN_STACK
1187 config ARM_CPU_TOPOLOGY
1188 bool "Support cpu topology definition"
1189 depends on SMP && CPU_V7
1192 Support ARM cpu topology definition. The MPIDR register defines
1193 affinity between processors which is then used to describe the cpu
1194 topology of an ARM System.
1197 bool "Multi-core scheduler support"
1198 depends on ARM_CPU_TOPOLOGY
1200 Multi-core scheduler support improves the CPU scheduler's decision
1201 making when dealing with multi-core CPU chips at a cost of slightly
1202 increased overhead in some places. If unsure say N here.
1205 bool "SMT scheduler support"
1206 depends on ARM_CPU_TOPOLOGY
1208 Improves the CPU scheduler's decision making when dealing with
1209 MultiThreading at a cost of slightly increased overhead in some
1210 places. If unsure say N here.
1215 This option enables support for the ARM snoop control unit
1217 config HAVE_ARM_ARCH_TIMER
1218 bool "Architected timer support"
1220 select ARM_ARCH_TIMER
1222 This option enables support for the ARM architected timer
1227 This options enables support for the ARM timer and watchdog unit
1230 bool "Multi-Cluster Power Management"
1231 depends on CPU_V7 && SMP
1233 This option provides the common power management infrastructure
1234 for (multi-)cluster based systems, such as big.LITTLE based
1237 config MCPM_QUAD_CLUSTER
1241 To avoid wasting resources unnecessarily, MCPM only supports up
1242 to 2 clusters by default.
1243 Platforms with 3 or 4 clusters that use MCPM must select this
1244 option to allow the additional clusters to be managed.
1247 bool "big.LITTLE support (Experimental)"
1248 depends on CPU_V7 && SMP
1251 This option enables support selections for the big.LITTLE
1252 system architecture.
1255 bool "big.LITTLE switcher support"
1256 depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
1259 The big.LITTLE "switcher" provides the core functionality to
1260 transparently handle transition between a cluster of A15's
1261 and a cluster of A7's in a big.LITTLE system.
1263 config BL_SWITCHER_DUMMY_IF
1264 tristate "Simple big.LITTLE switcher user interface"
1265 depends on BL_SWITCHER && DEBUG_KERNEL
1267 This is a simple and dummy char dev interface to control
1268 the big.LITTLE switcher core code. It is meant for
1269 debugging purposes only.
1272 prompt "Memory split"
1276 Select the desired split between kernel and user memory.
1278 If you are not absolutely sure what you are doing, leave this
1282 bool "3G/1G user/kernel split"
1283 config VMSPLIT_3G_OPT
1284 depends on !ARM_LPAE
1285 bool "3G/1G user/kernel split (for full 1G low memory)"
1287 bool "2G/2G user/kernel split"
1289 bool "1G/3G user/kernel split"
1294 default PHYS_OFFSET if !MMU
1295 default 0x40000000 if VMSPLIT_1G
1296 default 0x80000000 if VMSPLIT_2G
1297 default 0xB0000000 if VMSPLIT_3G_OPT
1300 config KASAN_SHADOW_OFFSET
1303 default 0x1f000000 if PAGE_OFFSET=0x40000000
1304 default 0x5f000000 if PAGE_OFFSET=0x80000000
1305 default 0x9f000000 if PAGE_OFFSET=0xC0000000
1306 default 0x8f000000 if PAGE_OFFSET=0xB0000000
1310 int "Maximum number of CPUs (2-32)"
1311 range 2 16 if DEBUG_KMAP_LOCAL
1312 range 2 32 if !DEBUG_KMAP_LOCAL
1316 The maximum number of CPUs that the kernel can support.
1317 Up to 32 CPUs can be supported, or up to 16 if kmap_local()
1318 debugging is enabled, which uses half of the per-CPU fixmap
1319 slots as guard regions.
1322 bool "Support for hot-pluggable CPUs"
1324 select GENERIC_IRQ_MIGRATION
1326 Say Y here to experiment with turning CPUs off and on. CPUs
1327 can be controlled through /sys/devices/system/cpu.
1330 bool "Support for the ARM Power State Coordination Interface (PSCI)"
1331 depends on HAVE_ARM_SMCCC
1334 Say Y here if you want Linux to communicate with system firmware
1335 implementing the PSCI specification for CPU-centric power
1336 management operations described in ARM document number ARM DEN
1337 0022A ("Power State Coordination Interface System Software on
1340 # The GPIO number here must be sorted by descending number. In case of
1341 # a multiplatform kernel, we just want the highest value required by the
1342 # selected platforms.
1345 default 2048 if ARCH_INTEL_SOCFPGA
1346 default 1024 if ARCH_BRCMSTB || ARCH_RENESAS || ARCH_TEGRA || \
1347 ARCH_ZYNQ || ARCH_ASPEED
1348 default 512 if ARCH_EXYNOS || ARCH_KEYSTONE || SOC_OMAP5 || \
1349 SOC_DRA7XX || ARCH_S3C24XX || ARCH_S3C64XX || ARCH_S5PV210
1350 default 416 if ARCH_SUNXI
1351 default 392 if ARCH_U8500
1352 default 352 if ARCH_VT8500
1353 default 288 if ARCH_ROCKCHIP
1354 default 264 if MACH_H4700
1357 Maximum number of GPIOs in the system.
1359 If unsure, leave the default value.
1363 default 128 if SOC_AT91RM9200
1367 depends on HZ_FIXED = 0
1368 prompt "Timer frequency"
1392 default HZ_FIXED if HZ_FIXED != 0
1393 default 100 if HZ_100
1394 default 200 if HZ_200
1395 default 250 if HZ_250
1396 default 300 if HZ_300
1397 default 500 if HZ_500
1401 def_bool HIGH_RES_TIMERS
1403 config THUMB2_KERNEL
1404 bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
1405 depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
1406 default y if CPU_THUMBONLY
1409 By enabling this option, the kernel will be compiled in
1414 config ARM_PATCH_IDIV
1415 bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
1416 depends on CPU_32v7 && !XIP_KERNEL
1419 The ARM compiler inserts calls to __aeabi_idiv() and
1420 __aeabi_uidiv() when it needs to perform division on signed
1421 and unsigned integers. Some v7 CPUs have support for the sdiv
1422 and udiv instructions that can be used to implement those
1425 Enabling this option allows the kernel to modify itself to
1426 replace the first two instructions of these library functions
1427 with the sdiv or udiv plus "bx lr" instructions when the CPU
1428 it is running on supports them. Typically this will be faster
1429 and less power intensive than running the original library
1430 code to do integer division.
1433 bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
1434 !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
1435 default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
1437 This option allows for the kernel to be compiled using the latest
1438 ARM ABI (aka EABI). This is only useful if you are using a user
1439 space environment that is also compiled with EABI.
1441 Since there are major incompatibilities between the legacy ABI and
1442 EABI, especially with regard to structure member alignment, this
1443 option also changes the kernel syscall calling convention to
1444 disambiguate both ABIs and allow for backward compatibility support
1445 (selected with CONFIG_OABI_COMPAT).
1447 To use this you need GCC version 4.0.0 or later.
1450 bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
1451 depends on AEABI && !THUMB2_KERNEL
1453 This option preserves the old syscall interface along with the
1454 new (ARM EABI) one. It also provides a compatibility layer to
1455 intercept syscalls that have structure arguments which layout
1456 in memory differs between the legacy ABI and the new ARM EABI
1457 (only for non "thumb" binaries). This option adds a tiny
1458 overhead to all syscalls and produces a slightly larger kernel.
1460 The seccomp filter system will not be available when this is
1461 selected, since there is no way yet to sensibly distinguish
1462 between calling conventions during filtering.
1464 If you know you'll be using only pure EABI user space then you
1465 can say N here. If this option is not selected and you attempt
1466 to execute a legacy ABI binary then the result will be
1467 UNPREDICTABLE (in fact it can be predicted that it won't work
1468 at all). If in doubt say N.
1470 config ARCH_SELECT_MEMORY_MODEL
1473 config ARCH_FLATMEM_ENABLE
1476 config ARCH_SPARSEMEM_ENABLE
1478 select SPARSEMEM_STATIC if SPARSEMEM
1481 bool "High Memory Support"
1484 select KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1486 The address space of ARM processors is only 4 Gigabytes large
1487 and it has to accommodate user address space, kernel address
1488 space as well as some memory mapped IO. That means that, if you
1489 have a large amount of physical memory and/or IO, not all of the
1490 memory can be "permanently mapped" by the kernel. The physical
1491 memory that is not permanently mapped is called "high memory".
1493 Depending on the selected kernel/user memory split, minimum
1494 vmalloc space and actual amount of RAM, you may not need this
1495 option which should result in a slightly faster kernel.
1500 bool "Allocate 2nd-level pagetables from highmem" if EXPERT
1504 The VM uses one page of physical memory for each page table.
1505 For systems with a lot of processes, this can use a lot of
1506 precious low memory, eventually leading to low memory being
1507 consumed by page tables. Setting this option will allow
1508 user-space 2nd level page tables to reside in high memory.
1510 config CPU_SW_DOMAIN_PAN
1511 bool "Enable use of CPU domains to implement privileged no-access"
1512 depends on MMU && !ARM_LPAE
1515 Increase kernel security by ensuring that normal kernel accesses
1516 are unable to access userspace addresses. This can help prevent
1517 use-after-free bugs becoming an exploitable privilege escalation
1518 by ensuring that magic values (such as LIST_POISON) will always
1519 fault when dereferenced.
1521 CPUs with low-vector mappings use a best-efforts implementation.
1522 Their lower 1MB needs to remain accessible for the vectors, but
1523 the remainder of userspace will become appropriately inaccessible.
1525 config HW_PERF_EVENTS
1529 config ARM_MODULE_PLTS
1530 bool "Use PLTs to allow module memory to spill over into vmalloc area"
1534 Allocate PLTs when loading modules so that jumps and calls whose
1535 targets are too far away for their relative offsets to be encoded
1536 in the instructions themselves can be bounced via veneers in the
1537 module's PLT. This allows modules to be allocated in the generic
1538 vmalloc area after the dedicated module memory area has been
1539 exhausted. The modules will use slightly more memory, but after
1540 rounding up to page size, the actual memory footprint is usually
1543 Disabling this is usually safe for small single-platform
1544 configurations. If unsure, say y.
1546 config FORCE_MAX_ZONEORDER
1547 int "Maximum zone order"
1548 default "12" if SOC_AM33XX
1549 default "9" if SA1111
1552 The kernel memory allocator divides physically contiguous memory
1553 blocks into "zones", where each zone is a power of two number of
1554 pages. This option selects the largest power of two that the kernel
1555 keeps in the memory allocator. If you need to allocate very large
1556 blocks of physically contiguous memory, then you may need to
1557 increase this value.
1559 This config option is actually maximum order plus one. For example,
1560 a value of 11 means that the largest free memory block is 2^10 pages.
1562 config ALIGNMENT_TRAP
1563 def_bool CPU_CP15_MMU
1564 select HAVE_PROC_CPU if PROC_FS
1566 ARM processors cannot fetch/store information which is not
1567 naturally aligned on the bus, i.e., a 4 byte fetch must start at an
1568 address divisible by 4. On 32-bit ARM processors, these non-aligned
1569 fetch/store instructions will be emulated in software if you say
1570 here, which has a severe performance impact. This is necessary for
1571 correct operation of some network protocols. With an IP-only
1572 configuration it is safe to say N, otherwise say Y.
1574 config UACCESS_WITH_MEMCPY
1575 bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
1577 default y if CPU_FEROCEON
1579 Implement faster copy_to_user and clear_user methods for CPU
1580 cores where a 8-word STM instruction give significantly higher
1581 memory write throughput than a sequence of individual 32bit stores.
1583 A possible side effect is a slight increase in scheduling latency
1584 between threads sharing the same address space if they invoke
1585 such copy operations with large buffers.
1587 However, if the CPU data cache is using a write-allocate mode,
1588 this option is unlikely to provide any performance gain.
1591 bool "Enable paravirtualization code"
1593 This changes the kernel so it can modify itself when it is run
1594 under a hypervisor, potentially improving performance significantly
1595 over full virtualization.
1597 config PARAVIRT_TIME_ACCOUNTING
1598 bool "Paravirtual steal time accounting"
1601 Select this option to enable fine granularity task steal time
1602 accounting. Time spent executing other tasks in parallel with
1603 the current vCPU is discounted from the vCPU power. To account for
1604 that, there can be a small performance impact.
1606 If in doubt, say N here.
1613 bool "Xen guest support on ARM"
1614 depends on ARM && AEABI && OF
1615 depends on CPU_V7 && !CPU_V6
1616 depends on !GENERIC_ATOMIC64
1618 select ARCH_DMA_ADDR_T_64BIT
1624 Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
1626 config CC_HAVE_STACKPROTECTOR_TLS
1627 def_bool $(cc-option,-mtp=cp15 -mstack-protector-guard=tls -mstack-protector-guard-offset=0)
1629 config STACKPROTECTOR_PER_TASK
1630 bool "Use a unique stack canary value for each task"
1631 depends on STACKPROTECTOR && CURRENT_POINTER_IN_TPIDRURO && !XIP_DEFLATED_DATA
1632 depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS
1633 select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS
1636 Due to the fact that GCC uses an ordinary symbol reference from
1637 which to load the value of the stack canary, this value can only
1638 change at reboot time on SMP systems, and all tasks running in the
1639 kernel's address space are forced to use the same canary value for
1640 the entire duration that the system is up.
1642 Enable this option to switch to a different method that uses a
1643 different canary value for each task.
1650 bool "Flattened Device Tree support"
1654 Include support for flattened device tree machine descriptions.
1657 bool "Support for the traditional ATAGS boot data passing" if USE_OF
1660 This is the traditional way of passing data to the kernel at boot
1661 time. If you are solely relying on the flattened device tree (or
1662 the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
1663 to remove ATAGS support from your kernel binary. If unsure,
1666 config DEPRECATED_PARAM_STRUCT
1667 bool "Provide old way to pass kernel parameters"
1670 This was deprecated in 2001 and announced to live on for 5 years.
1671 Some old boot loaders still use this way.
1673 # Compressed boot loader in ROM. Yes, we really want to ask about
1674 # TEXT and BSS so we preserve their values in the config files.
1675 config ZBOOT_ROM_TEXT
1676 hex "Compressed ROM boot loader base address"
1679 The physical address at which the ROM-able zImage is to be
1680 placed in the target. Platforms which normally make use of
1681 ROM-able zImage formats normally set this to a suitable
1682 value in their defconfig file.
1684 If ZBOOT_ROM is not enabled, this has no effect.
1686 config ZBOOT_ROM_BSS
1687 hex "Compressed ROM boot loader BSS address"
1690 The base address of an area of read/write memory in the target
1691 for the ROM-able zImage which must be available while the
1692 decompressor is running. It must be large enough to hold the
1693 entire decompressed kernel plus an additional 128 KiB.
1694 Platforms which normally make use of ROM-able zImage formats
1695 normally set this to a suitable value in their defconfig file.
1697 If ZBOOT_ROM is not enabled, this has no effect.
1700 bool "Compressed boot loader in ROM/flash"
1701 depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
1702 depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
1704 Say Y here if you intend to execute your compressed kernel image
1705 (zImage) directly from ROM or flash. If unsure, say N.
1707 config ARM_APPENDED_DTB
1708 bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
1711 With this option, the boot code will look for a device tree binary
1712 (DTB) appended to zImage
1713 (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
1715 This is meant as a backward compatibility convenience for those
1716 systems with a bootloader that can't be upgraded to accommodate
1717 the documented boot protocol using a device tree.
1719 Beware that there is very little in terms of protection against
1720 this option being confused by leftover garbage in memory that might
1721 look like a DTB header after a reboot if no actual DTB is appended
1722 to zImage. Do not leave this option active in a production kernel
1723 if you don't intend to always append a DTB. Proper passing of the
1724 location into r2 of a bootloader provided DTB is always preferable
1727 config ARM_ATAG_DTB_COMPAT
1728 bool "Supplement the appended DTB with traditional ATAG information"
1729 depends on ARM_APPENDED_DTB
1731 Some old bootloaders can't be updated to a DTB capable one, yet
1732 they provide ATAGs with memory configuration, the ramdisk address,
1733 the kernel cmdline string, etc. Such information is dynamically
1734 provided by the bootloader and can't always be stored in a static
1735 DTB. To allow a device tree enabled kernel to be used with such
1736 bootloaders, this option allows zImage to extract the information
1737 from the ATAG list and store it at run time into the appended DTB.
1740 prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
1741 default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1743 config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1744 bool "Use bootloader kernel arguments if available"
1746 Uses the command-line options passed by the boot loader instead of
1747 the device tree bootargs property. If the boot loader doesn't provide
1748 any, the device tree bootargs property will be used.
1750 config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
1751 bool "Extend with bootloader kernel arguments"
1753 The command-line arguments provided by the boot loader will be
1754 appended to the the device tree bootargs property.
1759 string "Default kernel command string"
1762 On some architectures (e.g. CATS), there is currently no way
1763 for the boot loader to pass arguments to the kernel. For these
1764 architectures, you should supply some command-line options at build
1765 time by entering them here. As a minimum, you should specify the
1766 memory size and the root device (e.g., mem=64M root=/dev/nfs).
1769 prompt "Kernel command line type" if CMDLINE != ""
1770 default CMDLINE_FROM_BOOTLOADER
1773 config CMDLINE_FROM_BOOTLOADER
1774 bool "Use bootloader kernel arguments if available"
1776 Uses the command-line options passed by the boot loader. If
1777 the boot loader doesn't provide any, the default kernel command
1778 string provided in CMDLINE will be used.
1780 config CMDLINE_EXTEND
1781 bool "Extend bootloader kernel arguments"
1783 The command-line arguments provided by the boot loader will be
1784 appended to the default kernel command string.
1786 config CMDLINE_FORCE
1787 bool "Always use the default kernel command string"
1789 Always use the default kernel command string, even if the boot
1790 loader passes other arguments to the kernel.
1791 This is useful if you cannot or don't want to change the
1792 command-line options your boot loader passes to the kernel.
1796 bool "Kernel Execute-In-Place from ROM"
1797 depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
1799 Execute-In-Place allows the kernel to run from non-volatile storage
1800 directly addressable by the CPU, such as NOR flash. This saves RAM
1801 space since the text section of the kernel is not loaded from flash
1802 to RAM. Read-write sections, such as the data section and stack,
1803 are still copied to RAM. The XIP kernel is not compressed since
1804 it has to run directly from flash, so it will take more space to
1805 store it. The flash address used to link the kernel object files,
1806 and for storing it, is configuration dependent. Therefore, if you
1807 say Y here, you must know the proper physical address where to
1808 store the kernel image depending on your own flash memory usage.
1810 Also note that the make target becomes "make xipImage" rather than
1811 "make zImage" or "make Image". The final kernel binary to put in
1812 ROM memory will be arch/arm/boot/xipImage.
1816 config XIP_PHYS_ADDR
1817 hex "XIP Kernel Physical Location"
1818 depends on XIP_KERNEL
1819 default "0x00080000"
1821 This is the physical address in your flash memory the kernel will
1822 be linked for and stored to. This address is dependent on your
1825 config XIP_DEFLATED_DATA
1826 bool "Store kernel .data section compressed in ROM"
1827 depends on XIP_KERNEL
1830 Before the kernel is actually executed, its .data section has to be
1831 copied to RAM from ROM. This option allows for storing that data
1832 in compressed form and decompressed to RAM rather than merely being
1833 copied, saving some precious ROM space. A possible drawback is a
1834 slightly longer boot delay.
1837 bool "Kexec system call (EXPERIMENTAL)"
1838 depends on (!SMP || PM_SLEEP_SMP)
1842 kexec is a system call that implements the ability to shutdown your
1843 current kernel, and to start another kernel. It is like a reboot
1844 but it is independent of the system firmware. And like a reboot
1845 you can start any kernel with it, not just Linux.
1847 It is an ongoing process to be certain the hardware in a machine
1848 is properly shutdown, so do not be surprised if this code does not
1849 initially work for you.
1852 bool "Export atags in procfs"
1853 depends on ATAGS && KEXEC
1856 Should the atags used to boot the kernel be exported in an "atags"
1857 file in procfs. Useful with kexec.
1860 bool "Build kdump crash kernel (EXPERIMENTAL)"
1862 Generate crash dump after being started by kexec. This should
1863 be normally only set in special crash dump kernels which are
1864 loaded in the main kernel with kexec-tools into a specially
1865 reserved region and then later executed after a crash by
1866 kdump/kexec. The crash dump kernel must be compiled to a
1867 memory address not used by the main kernel
1869 For more details see Documentation/admin-guide/kdump/kdump.rst
1871 config AUTO_ZRELADDR
1872 bool "Auto calculation of the decompressed kernel image address"
1874 ZRELADDR is the physical address where the decompressed kernel
1875 image will be placed. If AUTO_ZRELADDR is selected, the address
1876 will be determined at run-time, either by masking the current IP
1877 with 0xf8000000, or, if invalid, from the DTB passed in r2.
1878 This assumes the zImage being placed in the first 128MB from
1885 bool "UEFI runtime support"
1886 depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
1888 select EFI_PARAMS_FROM_FDT
1890 select EFI_GENERIC_STUB
1891 select EFI_RUNTIME_WRAPPERS
1893 This option provides support for runtime services provided
1894 by UEFI firmware (such as non-volatile variables, realtime
1895 clock, and platform reset). A UEFI stub is also provided to
1896 allow the kernel to be booted as an EFI application. This
1897 is only useful for kernels that may run on systems that have
1901 bool "Enable support for SMBIOS (DMI) tables"
1905 This enables SMBIOS/DMI feature for systems.
1907 This option is only useful on systems that have UEFI firmware.
1908 However, even with this option, the resultant kernel should
1909 continue to boot on existing non-UEFI platforms.
1911 NOTE: This does *NOT* enable or encourage the use of DMI quirks,
1912 i.e., the the practice of identifying the platform via DMI to
1913 decide whether certain workarounds for buggy hardware and/or
1914 firmware need to be enabled. This would require the DMI subsystem
1915 to be enabled much earlier than we do on ARM, which is non-trivial.
1919 menu "CPU Power Management"
1921 source "drivers/cpufreq/Kconfig"
1923 source "drivers/cpuidle/Kconfig"
1927 menu "Floating point emulation"
1929 comment "At least one emulation must be selected"
1932 bool "NWFPE math emulation"
1933 depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
1935 Say Y to include the NWFPE floating point emulator in the kernel.
1936 This is necessary to run most binaries. Linux does not currently
1937 support floating point hardware so you need to say Y here even if
1938 your machine has an FPA or floating point co-processor podule.
1940 You may say N here if you are going to load the Acorn FPEmulator
1941 early in the bootup.
1944 bool "Support extended precision"
1945 depends on FPE_NWFPE
1947 Say Y to include 80-bit support in the kernel floating-point
1948 emulator. Otherwise, only 32 and 64-bit support is compiled in.
1949 Note that gcc does not generate 80-bit operations by default,
1950 so in most cases this option only enlarges the size of the
1951 floating point emulator without any good reason.
1953 You almost surely want to say N here.
1956 bool "FastFPE math emulation (EXPERIMENTAL)"
1957 depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
1959 Say Y here to include the FAST floating point emulator in the kernel.
1960 This is an experimental much faster emulator which now also has full
1961 precision for the mantissa. It does not support any exceptions.
1962 It is very simple, and approximately 3-6 times faster than NWFPE.
1964 It should be sufficient for most programs. It may be not suitable
1965 for scientific calculations, but you have to check this for yourself.
1966 If you do not feel you need a faster FP emulation you should better
1970 bool "VFP-format floating point maths"
1971 depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
1973 Say Y to include VFP support code in the kernel. This is needed
1974 if your hardware includes a VFP unit.
1976 Please see <file:Documentation/arm/vfp/release-notes.rst> for
1977 release notes and additional status information.
1979 Say N if your target does not have VFP hardware.
1987 bool "Advanced SIMD (NEON) Extension support"
1988 depends on VFPv3 && CPU_V7
1990 Say Y to include support code for NEON, the ARMv7 Advanced SIMD
1993 config KERNEL_MODE_NEON
1994 bool "Support for NEON in kernel mode"
1995 depends on NEON && AEABI
1997 Say Y to include support for NEON in kernel mode.
2001 menu "Power management options"
2003 source "kernel/power/Kconfig"
2005 config ARCH_SUSPEND_POSSIBLE
2006 depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
2007 CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
2010 config ARM_CPU_SUSPEND
2011 def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
2012 depends on ARCH_SUSPEND_POSSIBLE
2014 config ARCH_HIBERNATION_POSSIBLE
2017 default y if ARCH_SUSPEND_POSSIBLE
2022 source "arch/arm/crypto/Kconfig"
2025 source "arch/arm/Kconfig.assembler"