1 # SPDX-License-Identifier: GPL-2.0
5 select ARCH_32BIT_OFF_T
6 select ARCH_HAS_BINFMT_FLAT
7 select ARCH_HAS_DEBUG_VIRTUAL if MMU
8 select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
9 select ARCH_HAS_ELF_RANDOMIZE
10 select ARCH_HAS_FORTIFY_SOURCE
11 select ARCH_HAS_KEEPINITRD
13 select ARCH_HAS_MEMBARRIER_SYNC_CORE
14 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
15 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
16 select ARCH_HAS_PHYS_TO_DMA
17 select ARCH_HAS_SETUP_DMA_OPS
18 select ARCH_HAS_SET_MEMORY
19 select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
20 select ARCH_HAS_STRICT_MODULE_RWX if MMU
21 select ARCH_HAS_SYNC_DMA_FOR_DEVICE if SWIOTLB || !MMU
22 select ARCH_HAS_SYNC_DMA_FOR_CPU if SWIOTLB || !MMU
23 select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
24 select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
25 select ARCH_HAVE_CUSTOM_GPIO_H
26 select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
27 select ARCH_HAS_GCOV_PROFILE_ALL
28 select ARCH_KEEP_MEMBLOCK
29 select ARCH_MIGHT_HAVE_PC_PARPORT
30 select ARCH_NO_SG_CHAIN if !ARM_HAS_SG_CHAIN
31 select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
32 select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
33 select ARCH_SUPPORTS_ATOMIC_RMW
34 select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
35 select ARCH_USE_BUILTIN_BSWAP
36 select ARCH_USE_CMPXCHG_LOCKREF
37 select ARCH_USE_MEMTEST
38 select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
39 select ARCH_WANT_IPC_PARSE_VERSION
40 select ARCH_WANT_LD_ORPHAN_WARN
41 select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
42 select BUILDTIME_TABLE_SORT if MMU
43 select CLONE_BACKWARDS
44 select CPU_PM if SUSPEND || CPU_IDLE
45 select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
46 select DMA_DECLARE_COHERENT
47 select DMA_GLOBAL_POOL if !MMU
49 select DMA_REMAP if MMU
51 select EDAC_ATOMIC_SCRUB
52 select GENERIC_ALLOCATOR
53 select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
54 select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
55 select GENERIC_CLOCKEVENTS_BROADCAST if SMP
56 select GENERIC_IRQ_IPI if SMP
57 select GENERIC_CPU_AUTOPROBE
58 select GENERIC_EARLY_IOREMAP
59 select GENERIC_IDLE_POLL_SETUP
60 select GENERIC_IRQ_PROBE
61 select GENERIC_IRQ_SHOW
62 select GENERIC_IRQ_SHOW_LEVEL
63 select GENERIC_LIB_DEVMEM_IS_ALLOWED
64 select GENERIC_PCI_IOMAP
65 select GENERIC_SCHED_CLOCK
66 select GENERIC_SMP_IDLE_THREAD
67 select HANDLE_DOMAIN_IRQ
68 select HARDIRQS_SW_RESEND
69 select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
70 select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
71 select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
72 select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
73 select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
74 select HAVE_ARCH_MMAP_RND_BITS if MMU
75 select HAVE_ARCH_PFN_VALID
76 select HAVE_ARCH_SECCOMP
77 select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
78 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
79 select HAVE_ARCH_TRACEHOOK
80 select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
81 select HAVE_ARM_SMCCC if CPU_V7
82 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
83 select HAVE_CONTEXT_TRACKING
84 select HAVE_C_RECORDMCOUNT
85 select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
86 select HAVE_DMA_CONTIGUOUS if MMU
87 select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
88 select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
89 select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
90 select HAVE_EXIT_THREAD
91 select HAVE_FAST_GUP if ARM_LPAE
92 select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
93 select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
94 select HAVE_FUNCTION_TRACER if !XIP_KERNEL
95 select HAVE_FUTEX_CMPXCHG if FUTEX
96 select HAVE_GCC_PLUGINS
97 select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
98 select HAVE_IRQ_TIME_ACCOUNTING
99 select HAVE_KERNEL_GZIP
100 select HAVE_KERNEL_LZ4
101 select HAVE_KERNEL_LZMA
102 select HAVE_KERNEL_LZO
103 select HAVE_KERNEL_XZ
104 select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
105 select HAVE_KRETPROBES if HAVE_KPROBES
106 select HAVE_MOD_ARCH_SPECIFIC
108 select HAVE_OPTPROBES if !THUMB2_KERNEL
109 select HAVE_PERF_EVENTS
110 select HAVE_PERF_REGS
111 select HAVE_PERF_USER_STACK_DUMP
112 select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
113 select HAVE_REGS_AND_STACK_ACCESS_API
115 select HAVE_STACKPROTECTOR
116 select HAVE_SYSCALL_TRACEPOINTS
118 select HAVE_VIRT_CPU_ACCOUNTING_GEN
119 select IRQ_FORCED_THREADING
120 select MODULES_USE_ELF_REL
121 select NEED_DMA_MAP_STATE
122 select OF_EARLY_FLATTREE if OF
124 select OLD_SIGSUSPEND3
125 select PCI_SYSCALL if PCI
126 select PERF_USE_VMALLOC
128 select SYS_SUPPORTS_APM_EMULATION
129 select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
130 # Above selects are sorted alphabetically; please add new ones
131 # according to that. Thanks.
133 The ARM series is a line of low-power-consumption RISC chip designs
134 licensed by ARM Ltd and targeted at embedded applications and
135 handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
136 manufactured, but legacy ARM-based PC hardware remains popular in
137 Europe. There is an ARM Linux project with a web page at
138 <http://www.arm.linux.org.uk/>.
140 config ARM_HAS_SG_CHAIN
143 config ARM_DMA_USE_IOMMU
145 select ARM_HAS_SG_CHAIN
146 select NEED_SG_DMA_LENGTH
150 config ARM_DMA_IOMMU_ALIGNMENT
151 int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
155 DMA mapping framework by default aligns all buffers to the smallest
156 PAGE_SIZE order which is greater than or equal to the requested buffer
157 size. This works well for buffers up to a few hundreds kilobytes, but
158 for larger buffers it just a waste of address space. Drivers which has
159 relatively small addressing window (like 64Mib) might run out of
160 virtual space with just a few allocations.
162 With this parameter you can specify the maximum PAGE_SIZE order for
163 DMA IOMMU buffers. Larger buffers will be aligned only to this
164 specified order. The order is expressed as a power of two multiplied
169 config SYS_SUPPORTS_APM_EMULATION
174 select GENERIC_ALLOCATOR
185 config STACKTRACE_SUPPORT
189 config LOCKDEP_SUPPORT
193 config ARCH_HAS_ILOG2_U32
196 config ARCH_HAS_ILOG2_U64
199 config ARCH_HAS_BANDGAP
202 config FIX_EARLYCON_MEM
205 config GENERIC_HWEIGHT
209 config GENERIC_CALIBRATE_DELAY
213 config ARCH_MAY_HAVE_PC_FDC
216 config ARCH_SUPPORTS_UPROBES
219 config ARCH_HAS_DMA_SET_COHERENT_MASK
222 config GENERIC_ISA_DMA
228 config NEED_RET_TO_USER
234 config ARM_PATCH_PHYS_VIRT
235 bool "Patch physical to virtual translations at runtime" if EMBEDDED
237 depends on !XIP_KERNEL && MMU
239 Patch phys-to-virt and virt-to-phys translation functions at
240 boot and module load time according to the position of the
241 kernel in system memory.
243 This can only be used with non-XIP MMU kernels where the base
244 of physical memory is at a 2 MiB boundary.
246 Only disable this option if you know that you do not require
247 this feature (eg, building a kernel for a single machine) and
248 you need to shrink the kernel to the minimal size.
250 config NEED_MACH_IO_H
253 Select this when mach/io.h is required to provide special
254 definitions for this platform. The need for mach/io.h should
255 be avoided when possible.
257 config NEED_MACH_MEMORY_H
260 Select this when mach/memory.h is required to provide special
261 definitions for this platform. The need for mach/memory.h should
262 be avoided when possible.
265 hex "Physical address of main memory" if MMU
266 depends on !ARM_PATCH_PHYS_VIRT
267 default DRAM_BASE if !MMU
268 default 0x00000000 if ARCH_FOOTBRIDGE
269 default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
270 default 0x20000000 if ARCH_S5PV210
271 default 0xc0000000 if ARCH_SA1100
273 Please provide the physical address corresponding to the
274 location of main memory in your system.
280 config PGTABLE_LEVELS
282 default 3 if ARM_LPAE
288 bool "MMU-based Paged Memory Management Support"
291 Select if you want MMU-based virtualised addressing space
292 support by paged memory management. If unsure, say 'Y'.
294 config ARCH_MMAP_RND_BITS_MIN
297 config ARCH_MMAP_RND_BITS_MAX
298 default 14 if PAGE_OFFSET=0x40000000
299 default 15 if PAGE_OFFSET=0x80000000
303 # The "ARM system type" choice list is ordered alphabetically by option
304 # text. Please add new entries in the option alphabetic order.
307 prompt "ARM system type"
308 default ARM_SINGLE_ARMV7M if !MMU
309 default ARCH_MULTIPLATFORM if MMU
311 config ARCH_MULTIPLATFORM
312 bool "Allow multiple platforms to be selected"
314 select ARCH_FLATMEM_ENABLE
315 select ARCH_SPARSEMEM_ENABLE
316 select ARCH_SELECT_MEMORY_MODEL
317 select ARM_HAS_SG_CHAIN
318 select ARM_PATCH_PHYS_VIRT
322 select GENERIC_IRQ_MULTI_HANDLER
324 select PCI_DOMAINS_GENERIC if PCI
328 config ARM_SINGLE_ARMV7M
329 bool "ARMv7-M based platforms (Cortex-M0/M3/M4)"
342 select ARCH_SPARSEMEM_ENABLE
344 imply ARM_PATCH_PHYS_VIRT
346 select GENERIC_IRQ_MULTI_HANDLER
351 select HAVE_LEGACY_CLK
353 This enables support for the Cirrus EP93xx series of CPUs.
355 config ARCH_FOOTBRIDGE
359 select NEED_MACH_IO_H if !MMU
360 select NEED_MACH_MEMORY_H
362 Support for systems based on the DC21285 companion chip
363 ("FootBridge"), such as the Simtec CATS and the Rebel NetWinder.
371 select NEED_RET_TO_USER
375 Support for Intel's 80219 and IOP32X (XScale) family of
381 select ARCH_HAS_DMA_SET_COHERENT_MASK
382 select ARCH_SUPPORTS_BIG_ENDIAN
384 select DMABOUNCE if PCI
385 select GENERIC_IRQ_MULTI_HANDLER
391 # With the new PCI driver this is not needed
392 select NEED_MACH_IO_H if IXP4XX_PCI_LEGACY
393 select USB_EHCI_BIG_ENDIAN_DESC
394 select USB_EHCI_BIG_ENDIAN_MMIO
396 Support for Intel's IXP4XX (XScale) family of processors.
401 select GENERIC_IRQ_MULTI_HANDLER
407 select PLAT_ORION_LEGACY
409 select PM_GENERIC_DOMAINS if PM
411 Support for the Marvell Dove SoC 88AP510
414 bool "PXA2xx/PXA3xx-based"
417 select ARM_CPU_SUSPEND if PM
423 select CPU_XSCALE if !CPU_XSC3
424 select GENERIC_IRQ_MULTI_HANDLER
431 Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
437 select ARCH_MAY_HAVE_PC_FDC
438 select ARCH_SPARSEMEM_ENABLE
439 select ARM_HAS_SG_CHAIN
442 select HAVE_PATA_PLATFORM
444 select LEGACY_TIMER_TICK
445 select NEED_MACH_IO_H
446 select NEED_MACH_MEMORY_H
449 On the Acorn Risc-PC, Linux can support the internal IDE disk and
450 CD-ROM interface, serial and parallel port, and the floppy drive.
455 select ARCH_SPARSEMEM_ENABLE
458 select TIMER_OF if OF
462 select GENERIC_IRQ_MULTI_HANDLER
466 select NEED_MACH_MEMORY_H
469 Support for StrongARM 11x0 based boards.
472 bool "Samsung S3C24XX SoCs"
474 select CLKSRC_SAMSUNG_PWM
477 select GENERIC_IRQ_MULTI_HANDLER
478 select HAVE_S3C2410_I2C if I2C
479 select HAVE_S3C_RTC if RTC_CLASS
480 select NEED_MACH_IO_H
481 select S3C2410_WATCHDOG
486 Samsung S3C2410, S3C2412, S3C2413, S3C2416, S3C2440, S3C2442, S3C2443
487 and S3C2450 SoCs based systems, such as the Simtec Electronics BAST
488 (<http://www.simtec.co.uk/products/EB110ITX/>), the IPAQ 1940 or the
489 Samsung SMDK2410 development board (and derivatives).
496 select GENERIC_IRQ_CHIP
497 select GENERIC_IRQ_MULTI_HANDLER
499 select HAVE_LEGACY_CLK
501 select NEED_MACH_IO_H if PCCARD
502 select NEED_MACH_MEMORY_H
505 Support for older TI OMAP1 (omap7xx, omap15xx or omap16xx)
509 menu "Multiple platform selection"
510 depends on ARCH_MULTIPLATFORM
512 comment "CPU Core family selection"
515 bool "ARMv4 based platforms (FA526)"
516 depends on !ARCH_MULTI_V6_V7
517 select ARCH_MULTI_V4_V5
520 config ARCH_MULTI_V4T
521 bool "ARMv4T based platforms (ARM720T, ARM920T, ...)"
522 depends on !ARCH_MULTI_V6_V7
523 select ARCH_MULTI_V4_V5
524 select CPU_ARM920T if !(CPU_ARM7TDMI || CPU_ARM720T || \
525 CPU_ARM740T || CPU_ARM9TDMI || CPU_ARM922T || \
526 CPU_ARM925T || CPU_ARM940T)
529 bool "ARMv5 based platforms (ARM926T, XSCALE, PJ1, ...)"
530 depends on !ARCH_MULTI_V6_V7
531 select ARCH_MULTI_V4_V5
532 select CPU_ARM926T if !(CPU_ARM946E || CPU_ARM1020 || \
533 CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || \
534 CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_FEROCEON)
536 config ARCH_MULTI_V4_V5
540 bool "ARMv6 based platforms (ARM11)"
541 select ARCH_MULTI_V6_V7
545 bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)"
547 select ARCH_MULTI_V6_V7
551 config ARCH_MULTI_V6_V7
553 select MIGHT_HAVE_CACHE_L2X0
555 config ARCH_MULTI_CPU_AUTO
556 def_bool !(ARCH_MULTI_V4 || ARCH_MULTI_V4T || ARCH_MULTI_V6_V7)
562 bool "Dummy Virtual Machine"
563 depends on ARCH_MULTI_V7
566 select ARM_GIC_V2M if PCI
568 select ARM_GIC_V3_ITS if PCI
570 select HAVE_ARM_ARCH_TIMER
571 select ARCH_SUPPORTS_BIG_ENDIAN
574 # This is sorted alphabetically by mach-* pathname. However, plat-*
575 # Kconfigs may be included either alphabetically (according to the
576 # plat- suffix) or along side the corresponding mach-* source.
578 source "arch/arm/mach-actions/Kconfig"
580 source "arch/arm/mach-alpine/Kconfig"
582 source "arch/arm/mach-artpec/Kconfig"
584 source "arch/arm/mach-asm9260/Kconfig"
586 source "arch/arm/mach-aspeed/Kconfig"
588 source "arch/arm/mach-at91/Kconfig"
590 source "arch/arm/mach-axxia/Kconfig"
592 source "arch/arm/mach-bcm/Kconfig"
594 source "arch/arm/mach-berlin/Kconfig"
596 source "arch/arm/mach-clps711x/Kconfig"
598 source "arch/arm/mach-cns3xxx/Kconfig"
600 source "arch/arm/mach-davinci/Kconfig"
602 source "arch/arm/mach-digicolor/Kconfig"
604 source "arch/arm/mach-dove/Kconfig"
606 source "arch/arm/mach-ep93xx/Kconfig"
608 source "arch/arm/mach-exynos/Kconfig"
610 source "arch/arm/mach-footbridge/Kconfig"
612 source "arch/arm/mach-gemini/Kconfig"
614 source "arch/arm/mach-highbank/Kconfig"
616 source "arch/arm/mach-hisi/Kconfig"
618 source "arch/arm/mach-imx/Kconfig"
620 source "arch/arm/mach-integrator/Kconfig"
622 source "arch/arm/mach-iop32x/Kconfig"
624 source "arch/arm/mach-ixp4xx/Kconfig"
626 source "arch/arm/mach-keystone/Kconfig"
628 source "arch/arm/mach-lpc32xx/Kconfig"
630 source "arch/arm/mach-mediatek/Kconfig"
632 source "arch/arm/mach-meson/Kconfig"
634 source "arch/arm/mach-milbeaut/Kconfig"
636 source "arch/arm/mach-mmp/Kconfig"
638 source "arch/arm/mach-moxart/Kconfig"
640 source "arch/arm/mach-mstar/Kconfig"
642 source "arch/arm/mach-mv78xx0/Kconfig"
644 source "arch/arm/mach-mvebu/Kconfig"
646 source "arch/arm/mach-mxs/Kconfig"
648 source "arch/arm/mach-nomadik/Kconfig"
650 source "arch/arm/mach-npcm/Kconfig"
652 source "arch/arm/mach-nspire/Kconfig"
654 source "arch/arm/plat-omap/Kconfig"
656 source "arch/arm/mach-omap1/Kconfig"
658 source "arch/arm/mach-omap2/Kconfig"
660 source "arch/arm/mach-orion5x/Kconfig"
662 source "arch/arm/mach-oxnas/Kconfig"
664 source "arch/arm/mach-pxa/Kconfig"
665 source "arch/arm/plat-pxa/Kconfig"
667 source "arch/arm/mach-qcom/Kconfig"
669 source "arch/arm/mach-rda/Kconfig"
671 source "arch/arm/mach-realtek/Kconfig"
673 source "arch/arm/mach-realview/Kconfig"
675 source "arch/arm/mach-rockchip/Kconfig"
677 source "arch/arm/mach-s3c/Kconfig"
679 source "arch/arm/mach-s5pv210/Kconfig"
681 source "arch/arm/mach-sa1100/Kconfig"
683 source "arch/arm/mach-shmobile/Kconfig"
685 source "arch/arm/mach-socfpga/Kconfig"
687 source "arch/arm/mach-spear/Kconfig"
689 source "arch/arm/mach-sti/Kconfig"
691 source "arch/arm/mach-stm32/Kconfig"
693 source "arch/arm/mach-sunxi/Kconfig"
695 source "arch/arm/mach-tegra/Kconfig"
697 source "arch/arm/mach-uniphier/Kconfig"
699 source "arch/arm/mach-ux500/Kconfig"
701 source "arch/arm/mach-versatile/Kconfig"
703 source "arch/arm/mach-vexpress/Kconfig"
705 source "arch/arm/mach-vt8500/Kconfig"
707 source "arch/arm/mach-zynq/Kconfig"
709 # ARMv7-M architecture
711 bool "NXP LPC18xx/LPC43xx"
712 depends on ARM_SINGLE_ARMV7M
713 select ARCH_HAS_RESET_CONTROLLER
715 select CLKSRC_LPC32XX
718 Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
719 high performance microcontrollers.
722 bool "ARM MPS2 platform"
723 depends on ARM_SINGLE_ARMV7M
727 Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
728 with a range of available cores like Cortex-M3/M4/M7.
730 Please, note that depends which Application Note is used memory map
731 for the platform may vary, so adjustment of RAM base might be needed.
733 # Definitions to make life easier
744 select GENERIC_IRQ_CHIP
747 config PLAT_ORION_LEGACY
754 config PLAT_VERSATILE
757 source "arch/arm/mm/Kconfig"
760 bool "Enable iWMMXt support"
761 depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
762 default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B
764 Enable support for iWMMXt context switching at run time if
765 running on a CPU that supports it.
768 source "arch/arm/Kconfig-nommu"
771 config PJ4B_ERRATA_4742
772 bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
773 depends on CPU_PJ4B && MACH_ARMADA_370
776 When coming out of either a Wait for Interrupt (WFI) or a Wait for
777 Event (WFE) IDLE states, a specific timing sensitivity exists between
778 the retiring WFI/WFE instructions and the newly issued subsequent
779 instructions. This sensitivity can result in a CPU hang scenario.
781 The software must insert either a Data Synchronization Barrier (DSB)
782 or Data Memory Barrier (DMB) command immediately after the WFI/WFE
785 config ARM_ERRATA_326103
786 bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
789 Executing a SWP instruction to read-only memory does not set bit 11
790 of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
791 treat the access as a read, preventing a COW from occurring and
792 causing the faulting task to livelock.
794 config ARM_ERRATA_411920
795 bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
796 depends on CPU_V6 || CPU_V6K
798 Invalidation of the Instruction Cache operation can
799 fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
800 It does not affect the MPCore. This option enables the ARM Ltd.
801 recommended workaround.
803 config ARM_ERRATA_430973
804 bool "ARM errata: Stale prediction on replaced interworking branch"
807 This option enables the workaround for the 430973 Cortex-A8
808 r1p* erratum. If a code sequence containing an ARM/Thumb
809 interworking branch is replaced with another code sequence at the
810 same virtual address, whether due to self-modifying code or virtual
811 to physical address re-mapping, Cortex-A8 does not recover from the
812 stale interworking branch prediction. This results in Cortex-A8
813 executing the new code sequence in the incorrect ARM or Thumb state.
814 The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
815 and also flushes the branch target cache at every context switch.
816 Note that setting specific bits in the ACTLR register may not be
817 available in non-secure mode.
819 config ARM_ERRATA_458693
820 bool "ARM errata: Processor deadlock when a false hazard is created"
822 depends on !ARCH_MULTIPLATFORM
824 This option enables the workaround for the 458693 Cortex-A8 (r2p0)
825 erratum. For very specific sequences of memory operations, it is
826 possible for a hazard condition intended for a cache line to instead
827 be incorrectly associated with a different cache line. This false
828 hazard might then cause a processor deadlock. The workaround enables
829 the L1 caching of the NEON accesses and disables the PLD instruction
830 in the ACTLR register. Note that setting specific bits in the ACTLR
831 register may not be available in non-secure mode.
833 config ARM_ERRATA_460075
834 bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
836 depends on !ARCH_MULTIPLATFORM
838 This option enables the workaround for the 460075 Cortex-A8 (r2p0)
839 erratum. Any asynchronous access to the L2 cache may encounter a
840 situation in which recent store transactions to the L2 cache are lost
841 and overwritten with stale memory contents from external memory. The
842 workaround disables the write-allocate mode for the L2 cache via the
843 ACTLR register. Note that setting specific bits in the ACTLR register
844 may not be available in non-secure mode.
846 config ARM_ERRATA_742230
847 bool "ARM errata: DMB operation may be faulty"
848 depends on CPU_V7 && SMP
849 depends on !ARCH_MULTIPLATFORM
851 This option enables the workaround for the 742230 Cortex-A9
852 (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
853 between two write operations may not ensure the correct visibility
854 ordering of the two writes. This workaround sets a specific bit in
855 the diagnostic register of the Cortex-A9 which causes the DMB
856 instruction to behave as a DSB, ensuring the correct behaviour of
859 config ARM_ERRATA_742231
860 bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
861 depends on CPU_V7 && SMP
862 depends on !ARCH_MULTIPLATFORM
864 This option enables the workaround for the 742231 Cortex-A9
865 (r2p0..r2p2) erratum. Under certain conditions, specific to the
866 Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
867 accessing some data located in the same cache line, may get corrupted
868 data due to bad handling of the address hazard when the line gets
869 replaced from one of the CPUs at the same time as another CPU is
870 accessing it. This workaround sets specific bits in the diagnostic
871 register of the Cortex-A9 which reduces the linefill issuing
872 capabilities of the processor.
874 config ARM_ERRATA_643719
875 bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
876 depends on CPU_V7 && SMP
879 This option enables the workaround for the 643719 Cortex-A9 (prior to
880 r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
881 register returns zero when it should return one. The workaround
882 corrects this value, ensuring cache maintenance operations which use
883 it behave as intended and avoiding data corruption.
885 config ARM_ERRATA_720789
886 bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
889 This option enables the workaround for the 720789 Cortex-A9 (prior to
890 r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
891 broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
892 As a consequence of this erratum, some TLB entries which should be
893 invalidated are not, resulting in an incoherency in the system page
894 tables. The workaround changes the TLB flushing routines to invalidate
895 entries regardless of the ASID.
897 config ARM_ERRATA_743622
898 bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
900 depends on !ARCH_MULTIPLATFORM
902 This option enables the workaround for the 743622 Cortex-A9
903 (r2p*) erratum. Under very rare conditions, a faulty
904 optimisation in the Cortex-A9 Store Buffer may lead to data
905 corruption. This workaround sets a specific bit in the diagnostic
906 register of the Cortex-A9 which disables the Store Buffer
907 optimisation, preventing the defect from occurring. This has no
908 visible impact on the overall performance or power consumption of the
911 config ARM_ERRATA_751472
912 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
914 depends on !ARCH_MULTIPLATFORM
916 This option enables the workaround for the 751472 Cortex-A9 (prior
917 to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
918 completion of a following broadcasted operation if the second
919 operation is received by a CPU before the ICIALLUIS has completed,
920 potentially leading to corrupted entries in the cache or TLB.
922 config ARM_ERRATA_754322
923 bool "ARM errata: possible faulty MMU translations following an ASID switch"
926 This option enables the workaround for the 754322 Cortex-A9 (r2p*,
927 r3p*) erratum. A speculative memory access may cause a page table walk
928 which starts prior to an ASID switch but completes afterwards. This
929 can populate the micro-TLB with a stale entry which may be hit with
930 the new ASID. This workaround places two dsb instructions in the mm
931 switching code so that no page table walks can cross the ASID switch.
933 config ARM_ERRATA_754327
934 bool "ARM errata: no automatic Store Buffer drain"
935 depends on CPU_V7 && SMP
937 This option enables the workaround for the 754327 Cortex-A9 (prior to
938 r2p0) erratum. The Store Buffer does not have any automatic draining
939 mechanism and therefore a livelock may occur if an external agent
940 continuously polls a memory location waiting to observe an update.
941 This workaround defines cpu_relax() as smp_mb(), preventing correctly
942 written polling loops from denying visibility of updates to memory.
944 config ARM_ERRATA_364296
945 bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
948 This options enables the workaround for the 364296 ARM1136
949 r0p2 erratum (possible cache data corruption with
950 hit-under-miss enabled). It sets the undocumented bit 31 in
951 the auxiliary control register and the FI bit in the control
952 register, thus disabling hit-under-miss without putting the
953 processor into full low interrupt latency mode. ARM11MPCore
956 config ARM_ERRATA_764369
957 bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
958 depends on CPU_V7 && SMP
960 This option enables the workaround for erratum 764369
961 affecting Cortex-A9 MPCore with two or more processors (all
962 current revisions). Under certain timing circumstances, a data
963 cache line maintenance operation by MVA targeting an Inner
964 Shareable memory region may fail to proceed up to either the
965 Point of Coherency or to the Point of Unification of the
966 system. This workaround adds a DSB instruction before the
967 relevant cache maintenance functions and sets a specific bit
968 in the diagnostic control register of the SCU.
970 config ARM_ERRATA_775420
971 bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
974 This option enables the workaround for the 775420 Cortex-A9 (r2p2,
975 r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
976 operation aborts with MMU exception, it might cause the processor
977 to deadlock. This workaround puts DSB before executing ISB if
978 an abort may occur on cache maintenance.
980 config ARM_ERRATA_798181
981 bool "ARM errata: TLBI/DSB failure on Cortex-A15"
982 depends on CPU_V7 && SMP
984 On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
985 adequately shooting down all use of the old entries. This
986 option enables the Linux kernel workaround for this erratum
987 which sends an IPI to the CPUs that are running the same ASID
988 as the one being invalidated.
990 config ARM_ERRATA_773022
991 bool "ARM errata: incorrect instructions may be executed from loop buffer"
994 This option enables the workaround for the 773022 Cortex-A15
995 (up to r0p4) erratum. In certain rare sequences of code, the
996 loop buffer may deliver incorrect instructions. This
997 workaround disables the loop buffer to avoid the erratum.
999 config ARM_ERRATA_818325_852422
1000 bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
1003 This option enables the workaround for:
1004 - Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
1005 instruction might deadlock. Fixed in r0p1.
1006 - Cortex-A12 852422: Execution of a sequence of instructions might
1007 lead to either a data corruption or a CPU deadlock. Not fixed in
1008 any Cortex-A12 cores yet.
1009 This workaround for all both errata involves setting bit[12] of the
1010 Feature Register. This bit disables an optimisation applied to a
1011 sequence of 2 instructions that use opposing condition codes.
1013 config ARM_ERRATA_821420
1014 bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
1017 This option enables the workaround for the 821420 Cortex-A12
1018 (all revs) erratum. In very rare timing conditions, a sequence
1019 of VMOV to Core registers instructions, for which the second
1020 one is in the shadow of a branch or abort, can lead to a
1021 deadlock when the VMOV instructions are issued out-of-order.
1023 config ARM_ERRATA_825619
1024 bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
1027 This option enables the workaround for the 825619 Cortex-A12
1028 (all revs) erratum. Within rare timing constraints, executing a
1029 DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
1030 and Device/Strongly-Ordered loads and stores might cause deadlock
1032 config ARM_ERRATA_857271
1033 bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
1036 This option enables the workaround for the 857271 Cortex-A12
1037 (all revs) erratum. Under very rare timing conditions, the CPU might
1038 hang. The workaround is expected to have a < 1% performance impact.
1040 config ARM_ERRATA_852421
1041 bool "ARM errata: A17: DMB ST might fail to create order between stores"
1044 This option enables the workaround for the 852421 Cortex-A17
1045 (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
1046 execution of a DMB ST instruction might fail to properly order
1047 stores from GroupA and stores from GroupB.
1049 config ARM_ERRATA_852423
1050 bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
1053 This option enables the workaround for:
1054 - Cortex-A17 852423: Execution of a sequence of instructions might
1055 lead to either a data corruption or a CPU deadlock. Not fixed in
1056 any Cortex-A17 cores yet.
1057 This is identical to Cortex-A12 erratum 852422. It is a separate
1058 config option from the A12 erratum due to the way errata are checked
1061 config ARM_ERRATA_857272
1062 bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
1065 This option enables the workaround for the 857272 Cortex-A17 erratum.
1066 This erratum is not known to be fixed in any A17 revision.
1067 This is identical to Cortex-A12 erratum 857271. It is a separate
1068 config option from the A12 erratum due to the way errata are checked
1073 source "arch/arm/common/Kconfig"
1080 Find out whether you have ISA slots on your motherboard. ISA is the
1081 name of a bus system, i.e. the way the CPU talks to the other stuff
1082 inside your box. Other bus systems are PCI, EISA, MicroChannel
1083 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1084 newer boards don't support it. If you have ISA, say Y, otherwise N.
1086 # Select ISA DMA controller support
1091 # Select ISA DMA interface
1095 config PCI_NANOENGINE
1096 bool "BSE nanoEngine PCI support"
1097 depends on SA1100_NANOENGINE
1099 Enable PCI on the BSE nanoEngine board.
1101 config ARM_ERRATA_814220
1102 bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
1105 The v7 ARM states that all cache and branch predictor maintenance
1106 operations that do not specify an address execute, relative to
1107 each other, in program order.
1108 However, because of this erratum, an L2 set/way cache maintenance
1109 operation can overtake an L1 set/way cache maintenance operation.
1110 This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
1115 menu "Kernel Features"
1120 This option should be selected by machines which have an SMP-
1123 The only effect of this option is to make the SMP-related
1124 options available to the user for configuration.
1127 bool "Symmetric Multi-Processing"
1128 depends on CPU_V6K || CPU_V7
1130 depends on MMU || ARM_MPU
1133 This enables support for systems with more than one CPU. If you have
1134 a system with only one CPU, say N. If you have a system with more
1135 than one CPU, say Y.
1137 If you say N here, the kernel will run on uni- and multiprocessor
1138 machines, but will use only one CPU of a multiprocessor machine. If
1139 you say Y here, the kernel will run on many, but not all,
1140 uniprocessor machines. On a uniprocessor machine, the kernel
1141 will run faster if you say N here.
1143 See also <file:Documentation/x86/i386/IO-APIC.rst>,
1144 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
1145 <http://tldp.org/HOWTO/SMP-HOWTO.html>.
1147 If you don't know what to do here, say N.
1150 bool "Allow booting SMP kernel on uniprocessor systems"
1151 depends on SMP && !XIP_KERNEL && MMU
1154 SMP kernels contain instructions which fail on non-SMP processors.
1155 Enabling this option allows the kernel to modify itself to make
1156 these instructions safe. Disabling it allows about 1K of space
1159 If you don't know what to do here, say Y.
1161 config ARM_CPU_TOPOLOGY
1162 bool "Support cpu topology definition"
1163 depends on SMP && CPU_V7
1166 Support ARM cpu topology definition. The MPIDR register defines
1167 affinity between processors which is then used to describe the cpu
1168 topology of an ARM System.
1171 bool "Multi-core scheduler support"
1172 depends on ARM_CPU_TOPOLOGY
1174 Multi-core scheduler support improves the CPU scheduler's decision
1175 making when dealing with multi-core CPU chips at a cost of slightly
1176 increased overhead in some places. If unsure say N here.
1179 bool "SMT scheduler support"
1180 depends on ARM_CPU_TOPOLOGY
1182 Improves the CPU scheduler's decision making when dealing with
1183 MultiThreading at a cost of slightly increased overhead in some
1184 places. If unsure say N here.
1189 This option enables support for the ARM snoop control unit
1191 config HAVE_ARM_ARCH_TIMER
1192 bool "Architected timer support"
1194 select ARM_ARCH_TIMER
1196 This option enables support for the ARM architected timer
1201 This options enables support for the ARM timer and watchdog unit
1204 bool "Multi-Cluster Power Management"
1205 depends on CPU_V7 && SMP
1207 This option provides the common power management infrastructure
1208 for (multi-)cluster based systems, such as big.LITTLE based
1211 config MCPM_QUAD_CLUSTER
1215 To avoid wasting resources unnecessarily, MCPM only supports up
1216 to 2 clusters by default.
1217 Platforms with 3 or 4 clusters that use MCPM must select this
1218 option to allow the additional clusters to be managed.
1221 bool "big.LITTLE support (Experimental)"
1222 depends on CPU_V7 && SMP
1225 This option enables support selections for the big.LITTLE
1226 system architecture.
1229 bool "big.LITTLE switcher support"
1230 depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
1233 The big.LITTLE "switcher" provides the core functionality to
1234 transparently handle transition between a cluster of A15's
1235 and a cluster of A7's in a big.LITTLE system.
1237 config BL_SWITCHER_DUMMY_IF
1238 tristate "Simple big.LITTLE switcher user interface"
1239 depends on BL_SWITCHER && DEBUG_KERNEL
1241 This is a simple and dummy char dev interface to control
1242 the big.LITTLE switcher core code. It is meant for
1243 debugging purposes only.
1246 prompt "Memory split"
1250 Select the desired split between kernel and user memory.
1252 If you are not absolutely sure what you are doing, leave this
1256 bool "3G/1G user/kernel split"
1257 config VMSPLIT_3G_OPT
1258 depends on !ARM_LPAE
1259 bool "3G/1G user/kernel split (for full 1G low memory)"
1261 bool "2G/2G user/kernel split"
1263 bool "1G/3G user/kernel split"
1268 default PHYS_OFFSET if !MMU
1269 default 0x40000000 if VMSPLIT_1G
1270 default 0x80000000 if VMSPLIT_2G
1271 default 0xB0000000 if VMSPLIT_3G_OPT
1274 config KASAN_SHADOW_OFFSET
1277 default 0x1f000000 if PAGE_OFFSET=0x40000000
1278 default 0x5f000000 if PAGE_OFFSET=0x80000000
1279 default 0x9f000000 if PAGE_OFFSET=0xC0000000
1280 default 0x8f000000 if PAGE_OFFSET=0xB0000000
1284 int "Maximum number of CPUs (2-32)"
1285 range 2 16 if DEBUG_KMAP_LOCAL
1286 range 2 32 if !DEBUG_KMAP_LOCAL
1290 The maximum number of CPUs that the kernel can support.
1291 Up to 32 CPUs can be supported, or up to 16 if kmap_local()
1292 debugging is enabled, which uses half of the per-CPU fixmap
1293 slots as guard regions.
1296 bool "Support for hot-pluggable CPUs"
1298 select GENERIC_IRQ_MIGRATION
1300 Say Y here to experiment with turning CPUs off and on. CPUs
1301 can be controlled through /sys/devices/system/cpu.
1304 bool "Support for the ARM Power State Coordination Interface (PSCI)"
1305 depends on HAVE_ARM_SMCCC
1308 Say Y here if you want Linux to communicate with system firmware
1309 implementing the PSCI specification for CPU-centric power
1310 management operations described in ARM document number ARM DEN
1311 0022A ("Power State Coordination Interface System Software on
1314 # The GPIO number here must be sorted by descending number. In case of
1315 # a multiplatform kernel, we just want the highest value required by the
1316 # selected platforms.
1319 default 2048 if ARCH_INTEL_SOCFPGA
1320 default 1024 if ARCH_BRCMSTB || ARCH_RENESAS || ARCH_TEGRA || \
1321 ARCH_ZYNQ || ARCH_ASPEED
1322 default 512 if ARCH_EXYNOS || ARCH_KEYSTONE || SOC_OMAP5 || \
1323 SOC_DRA7XX || ARCH_S3C24XX || ARCH_S3C64XX || ARCH_S5PV210
1324 default 416 if ARCH_SUNXI
1325 default 392 if ARCH_U8500
1326 default 352 if ARCH_VT8500
1327 default 288 if ARCH_ROCKCHIP
1328 default 264 if MACH_H4700
1331 Maximum number of GPIOs in the system.
1333 If unsure, leave the default value.
1337 default 128 if SOC_AT91RM9200
1341 depends on HZ_FIXED = 0
1342 prompt "Timer frequency"
1366 default HZ_FIXED if HZ_FIXED != 0
1367 default 100 if HZ_100
1368 default 200 if HZ_200
1369 default 250 if HZ_250
1370 default 300 if HZ_300
1371 default 500 if HZ_500
1375 def_bool HIGH_RES_TIMERS
1377 config THUMB2_KERNEL
1378 bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
1379 depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
1380 default y if CPU_THUMBONLY
1383 By enabling this option, the kernel will be compiled in
1388 config ARM_PATCH_IDIV
1389 bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
1390 depends on CPU_32v7 && !XIP_KERNEL
1393 The ARM compiler inserts calls to __aeabi_idiv() and
1394 __aeabi_uidiv() when it needs to perform division on signed
1395 and unsigned integers. Some v7 CPUs have support for the sdiv
1396 and udiv instructions that can be used to implement those
1399 Enabling this option allows the kernel to modify itself to
1400 replace the first two instructions of these library functions
1401 with the sdiv or udiv plus "bx lr" instructions when the CPU
1402 it is running on supports them. Typically this will be faster
1403 and less power intensive than running the original library
1404 code to do integer division.
1407 bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
1408 !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
1409 default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
1411 This option allows for the kernel to be compiled using the latest
1412 ARM ABI (aka EABI). This is only useful if you are using a user
1413 space environment that is also compiled with EABI.
1415 Since there are major incompatibilities between the legacy ABI and
1416 EABI, especially with regard to structure member alignment, this
1417 option also changes the kernel syscall calling convention to
1418 disambiguate both ABIs and allow for backward compatibility support
1419 (selected with CONFIG_OABI_COMPAT).
1421 To use this you need GCC version 4.0.0 or later.
1424 bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
1425 depends on AEABI && !THUMB2_KERNEL
1427 This option preserves the old syscall interface along with the
1428 new (ARM EABI) one. It also provides a compatibility layer to
1429 intercept syscalls that have structure arguments which layout
1430 in memory differs between the legacy ABI and the new ARM EABI
1431 (only for non "thumb" binaries). This option adds a tiny
1432 overhead to all syscalls and produces a slightly larger kernel.
1434 The seccomp filter system will not be available when this is
1435 selected, since there is no way yet to sensibly distinguish
1436 between calling conventions during filtering.
1438 If you know you'll be using only pure EABI user space then you
1439 can say N here. If this option is not selected and you attempt
1440 to execute a legacy ABI binary then the result will be
1441 UNPREDICTABLE (in fact it can be predicted that it won't work
1442 at all). If in doubt say N.
1444 config ARCH_SELECT_MEMORY_MODEL
1447 config ARCH_FLATMEM_ENABLE
1450 config ARCH_SPARSEMEM_ENABLE
1452 select SPARSEMEM_STATIC if SPARSEMEM
1455 bool "High Memory Support"
1459 The address space of ARM processors is only 4 Gigabytes large
1460 and it has to accommodate user address space, kernel address
1461 space as well as some memory mapped IO. That means that, if you
1462 have a large amount of physical memory and/or IO, not all of the
1463 memory can be "permanently mapped" by the kernel. The physical
1464 memory that is not permanently mapped is called "high memory".
1466 Depending on the selected kernel/user memory split, minimum
1467 vmalloc space and actual amount of RAM, you may not need this
1468 option which should result in a slightly faster kernel.
1473 bool "Allocate 2nd-level pagetables from highmem" if EXPERT
1477 The VM uses one page of physical memory for each page table.
1478 For systems with a lot of processes, this can use a lot of
1479 precious low memory, eventually leading to low memory being
1480 consumed by page tables. Setting this option will allow
1481 user-space 2nd level page tables to reside in high memory.
1483 config CPU_SW_DOMAIN_PAN
1484 bool "Enable use of CPU domains to implement privileged no-access"
1485 depends on MMU && !ARM_LPAE
1488 Increase kernel security by ensuring that normal kernel accesses
1489 are unable to access userspace addresses. This can help prevent
1490 use-after-free bugs becoming an exploitable privilege escalation
1491 by ensuring that magic values (such as LIST_POISON) will always
1492 fault when dereferenced.
1494 CPUs with low-vector mappings use a best-efforts implementation.
1495 Their lower 1MB needs to remain accessible for the vectors, but
1496 the remainder of userspace will become appropriately inaccessible.
1498 config HW_PERF_EVENTS
1502 config ARCH_WANT_GENERAL_HUGETLB
1505 config ARM_MODULE_PLTS
1506 bool "Use PLTs to allow module memory to spill over into vmalloc area"
1510 Allocate PLTs when loading modules so that jumps and calls whose
1511 targets are too far away for their relative offsets to be encoded
1512 in the instructions themselves can be bounced via veneers in the
1513 module's PLT. This allows modules to be allocated in the generic
1514 vmalloc area after the dedicated module memory area has been
1515 exhausted. The modules will use slightly more memory, but after
1516 rounding up to page size, the actual memory footprint is usually
1519 Disabling this is usually safe for small single-platform
1520 configurations. If unsure, say y.
1522 config FORCE_MAX_ZONEORDER
1523 int "Maximum zone order"
1524 default "12" if SOC_AM33XX
1525 default "9" if SA1111
1528 The kernel memory allocator divides physically contiguous memory
1529 blocks into "zones", where each zone is a power of two number of
1530 pages. This option selects the largest power of two that the kernel
1531 keeps in the memory allocator. If you need to allocate very large
1532 blocks of physically contiguous memory, then you may need to
1533 increase this value.
1535 This config option is actually maximum order plus one. For example,
1536 a value of 11 means that the largest free memory block is 2^10 pages.
1538 config ALIGNMENT_TRAP
1539 def_bool CPU_CP15_MMU
1540 select HAVE_PROC_CPU if PROC_FS
1542 ARM processors cannot fetch/store information which is not
1543 naturally aligned on the bus, i.e., a 4 byte fetch must start at an
1544 address divisible by 4. On 32-bit ARM processors, these non-aligned
1545 fetch/store instructions will be emulated in software if you say
1546 here, which has a severe performance impact. This is necessary for
1547 correct operation of some network protocols. With an IP-only
1548 configuration it is safe to say N, otherwise say Y.
1550 config UACCESS_WITH_MEMCPY
1551 bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
1553 default y if CPU_FEROCEON
1555 Implement faster copy_to_user and clear_user methods for CPU
1556 cores where a 8-word STM instruction give significantly higher
1557 memory write throughput than a sequence of individual 32bit stores.
1559 A possible side effect is a slight increase in scheduling latency
1560 between threads sharing the same address space if they invoke
1561 such copy operations with large buffers.
1563 However, if the CPU data cache is using a write-allocate mode,
1564 this option is unlikely to provide any performance gain.
1567 bool "Enable paravirtualization code"
1569 This changes the kernel so it can modify itself when it is run
1570 under a hypervisor, potentially improving performance significantly
1571 over full virtualization.
1573 config PARAVIRT_TIME_ACCOUNTING
1574 bool "Paravirtual steal time accounting"
1577 Select this option to enable fine granularity task steal time
1578 accounting. Time spent executing other tasks in parallel with
1579 the current vCPU is discounted from the vCPU power. To account for
1580 that, there can be a small performance impact.
1582 If in doubt, say N here.
1589 bool "Xen guest support on ARM"
1590 depends on ARM && AEABI && OF
1591 depends on CPU_V7 && !CPU_V6
1592 depends on !GENERIC_ATOMIC64
1594 select ARCH_DMA_ADDR_T_64BIT
1600 Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
1602 config STACKPROTECTOR_PER_TASK
1603 bool "Use a unique stack canary value for each task"
1604 depends on GCC_PLUGINS && STACKPROTECTOR && SMP && !XIP_DEFLATED_DATA
1605 select GCC_PLUGIN_ARM_SSP_PER_TASK
1608 Due to the fact that GCC uses an ordinary symbol reference from
1609 which to load the value of the stack canary, this value can only
1610 change at reboot time on SMP systems, and all tasks running in the
1611 kernel's address space are forced to use the same canary value for
1612 the entire duration that the system is up.
1614 Enable this option to switch to a different method that uses a
1615 different canary value for each task.
1622 bool "Flattened Device Tree support"
1626 Include support for flattened device tree machine descriptions.
1629 bool "Support for the traditional ATAGS boot data passing" if USE_OF
1632 This is the traditional way of passing data to the kernel at boot
1633 time. If you are solely relying on the flattened device tree (or
1634 the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
1635 to remove ATAGS support from your kernel binary. If unsure,
1638 config DEPRECATED_PARAM_STRUCT
1639 bool "Provide old way to pass kernel parameters"
1642 This was deprecated in 2001 and announced to live on for 5 years.
1643 Some old boot loaders still use this way.
1645 # Compressed boot loader in ROM. Yes, we really want to ask about
1646 # TEXT and BSS so we preserve their values in the config files.
1647 config ZBOOT_ROM_TEXT
1648 hex "Compressed ROM boot loader base address"
1651 The physical address at which the ROM-able zImage is to be
1652 placed in the target. Platforms which normally make use of
1653 ROM-able zImage formats normally set this to a suitable
1654 value in their defconfig file.
1656 If ZBOOT_ROM is not enabled, this has no effect.
1658 config ZBOOT_ROM_BSS
1659 hex "Compressed ROM boot loader BSS address"
1662 The base address of an area of read/write memory in the target
1663 for the ROM-able zImage which must be available while the
1664 decompressor is running. It must be large enough to hold the
1665 entire decompressed kernel plus an additional 128 KiB.
1666 Platforms which normally make use of ROM-able zImage formats
1667 normally set this to a suitable value in their defconfig file.
1669 If ZBOOT_ROM is not enabled, this has no effect.
1672 bool "Compressed boot loader in ROM/flash"
1673 depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
1674 depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
1676 Say Y here if you intend to execute your compressed kernel image
1677 (zImage) directly from ROM or flash. If unsure, say N.
1679 config ARM_APPENDED_DTB
1680 bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
1683 With this option, the boot code will look for a device tree binary
1684 (DTB) appended to zImage
1685 (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
1687 This is meant as a backward compatibility convenience for those
1688 systems with a bootloader that can't be upgraded to accommodate
1689 the documented boot protocol using a device tree.
1691 Beware that there is very little in terms of protection against
1692 this option being confused by leftover garbage in memory that might
1693 look like a DTB header after a reboot if no actual DTB is appended
1694 to zImage. Do not leave this option active in a production kernel
1695 if you don't intend to always append a DTB. Proper passing of the
1696 location into r2 of a bootloader provided DTB is always preferable
1699 config ARM_ATAG_DTB_COMPAT
1700 bool "Supplement the appended DTB with traditional ATAG information"
1701 depends on ARM_APPENDED_DTB
1703 Some old bootloaders can't be updated to a DTB capable one, yet
1704 they provide ATAGs with memory configuration, the ramdisk address,
1705 the kernel cmdline string, etc. Such information is dynamically
1706 provided by the bootloader and can't always be stored in a static
1707 DTB. To allow a device tree enabled kernel to be used with such
1708 bootloaders, this option allows zImage to extract the information
1709 from the ATAG list and store it at run time into the appended DTB.
1712 prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
1713 default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1715 config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1716 bool "Use bootloader kernel arguments if available"
1718 Uses the command-line options passed by the boot loader instead of
1719 the device tree bootargs property. If the boot loader doesn't provide
1720 any, the device tree bootargs property will be used.
1722 config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
1723 bool "Extend with bootloader kernel arguments"
1725 The command-line arguments provided by the boot loader will be
1726 appended to the the device tree bootargs property.
1731 string "Default kernel command string"
1734 On some architectures (e.g. CATS), there is currently no way
1735 for the boot loader to pass arguments to the kernel. For these
1736 architectures, you should supply some command-line options at build
1737 time by entering them here. As a minimum, you should specify the
1738 memory size and the root device (e.g., mem=64M root=/dev/nfs).
1741 prompt "Kernel command line type" if CMDLINE != ""
1742 default CMDLINE_FROM_BOOTLOADER
1745 config CMDLINE_FROM_BOOTLOADER
1746 bool "Use bootloader kernel arguments if available"
1748 Uses the command-line options passed by the boot loader. If
1749 the boot loader doesn't provide any, the default kernel command
1750 string provided in CMDLINE will be used.
1752 config CMDLINE_EXTEND
1753 bool "Extend bootloader kernel arguments"
1755 The command-line arguments provided by the boot loader will be
1756 appended to the default kernel command string.
1758 config CMDLINE_FORCE
1759 bool "Always use the default kernel command string"
1761 Always use the default kernel command string, even if the boot
1762 loader passes other arguments to the kernel.
1763 This is useful if you cannot or don't want to change the
1764 command-line options your boot loader passes to the kernel.
1768 bool "Kernel Execute-In-Place from ROM"
1769 depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
1771 Execute-In-Place allows the kernel to run from non-volatile storage
1772 directly addressable by the CPU, such as NOR flash. This saves RAM
1773 space since the text section of the kernel is not loaded from flash
1774 to RAM. Read-write sections, such as the data section and stack,
1775 are still copied to RAM. The XIP kernel is not compressed since
1776 it has to run directly from flash, so it will take more space to
1777 store it. The flash address used to link the kernel object files,
1778 and for storing it, is configuration dependent. Therefore, if you
1779 say Y here, you must know the proper physical address where to
1780 store the kernel image depending on your own flash memory usage.
1782 Also note that the make target becomes "make xipImage" rather than
1783 "make zImage" or "make Image". The final kernel binary to put in
1784 ROM memory will be arch/arm/boot/xipImage.
1788 config XIP_PHYS_ADDR
1789 hex "XIP Kernel Physical Location"
1790 depends on XIP_KERNEL
1791 default "0x00080000"
1793 This is the physical address in your flash memory the kernel will
1794 be linked for and stored to. This address is dependent on your
1797 config XIP_DEFLATED_DATA
1798 bool "Store kernel .data section compressed in ROM"
1799 depends on XIP_KERNEL
1802 Before the kernel is actually executed, its .data section has to be
1803 copied to RAM from ROM. This option allows for storing that data
1804 in compressed form and decompressed to RAM rather than merely being
1805 copied, saving some precious ROM space. A possible drawback is a
1806 slightly longer boot delay.
1809 bool "Kexec system call (EXPERIMENTAL)"
1810 depends on (!SMP || PM_SLEEP_SMP)
1814 kexec is a system call that implements the ability to shutdown your
1815 current kernel, and to start another kernel. It is like a reboot
1816 but it is independent of the system firmware. And like a reboot
1817 you can start any kernel with it, not just Linux.
1819 It is an ongoing process to be certain the hardware in a machine
1820 is properly shutdown, so do not be surprised if this code does not
1821 initially work for you.
1824 bool "Export atags in procfs"
1825 depends on ATAGS && KEXEC
1828 Should the atags used to boot the kernel be exported in an "atags"
1829 file in procfs. Useful with kexec.
1832 bool "Build kdump crash kernel (EXPERIMENTAL)"
1834 Generate crash dump after being started by kexec. This should
1835 be normally only set in special crash dump kernels which are
1836 loaded in the main kernel with kexec-tools into a specially
1837 reserved region and then later executed after a crash by
1838 kdump/kexec. The crash dump kernel must be compiled to a
1839 memory address not used by the main kernel
1841 For more details see Documentation/admin-guide/kdump/kdump.rst
1843 config AUTO_ZRELADDR
1844 bool "Auto calculation of the decompressed kernel image address"
1846 ZRELADDR is the physical address where the decompressed kernel
1847 image will be placed. If AUTO_ZRELADDR is selected, the address
1848 will be determined at run-time, either by masking the current IP
1849 with 0xf8000000, or, if invalid, from the DTB passed in r2.
1850 This assumes the zImage being placed in the first 128MB from
1857 bool "UEFI runtime support"
1858 depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
1860 select EFI_PARAMS_FROM_FDT
1862 select EFI_GENERIC_STUB
1863 select EFI_RUNTIME_WRAPPERS
1865 This option provides support for runtime services provided
1866 by UEFI firmware (such as non-volatile variables, realtime
1867 clock, and platform reset). A UEFI stub is also provided to
1868 allow the kernel to be booted as an EFI application. This
1869 is only useful for kernels that may run on systems that have
1873 bool "Enable support for SMBIOS (DMI) tables"
1877 This enables SMBIOS/DMI feature for systems.
1879 This option is only useful on systems that have UEFI firmware.
1880 However, even with this option, the resultant kernel should
1881 continue to boot on existing non-UEFI platforms.
1883 NOTE: This does *NOT* enable or encourage the use of DMI quirks,
1884 i.e., the the practice of identifying the platform via DMI to
1885 decide whether certain workarounds for buggy hardware and/or
1886 firmware need to be enabled. This would require the DMI subsystem
1887 to be enabled much earlier than we do on ARM, which is non-trivial.
1891 menu "CPU Power Management"
1893 source "drivers/cpufreq/Kconfig"
1895 source "drivers/cpuidle/Kconfig"
1899 menu "Floating point emulation"
1901 comment "At least one emulation must be selected"
1904 bool "NWFPE math emulation"
1905 depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
1907 Say Y to include the NWFPE floating point emulator in the kernel.
1908 This is necessary to run most binaries. Linux does not currently
1909 support floating point hardware so you need to say Y here even if
1910 your machine has an FPA or floating point co-processor podule.
1912 You may say N here if you are going to load the Acorn FPEmulator
1913 early in the bootup.
1916 bool "Support extended precision"
1917 depends on FPE_NWFPE
1919 Say Y to include 80-bit support in the kernel floating-point
1920 emulator. Otherwise, only 32 and 64-bit support is compiled in.
1921 Note that gcc does not generate 80-bit operations by default,
1922 so in most cases this option only enlarges the size of the
1923 floating point emulator without any good reason.
1925 You almost surely want to say N here.
1928 bool "FastFPE math emulation (EXPERIMENTAL)"
1929 depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
1931 Say Y here to include the FAST floating point emulator in the kernel.
1932 This is an experimental much faster emulator which now also has full
1933 precision for the mantissa. It does not support any exceptions.
1934 It is very simple, and approximately 3-6 times faster than NWFPE.
1936 It should be sufficient for most programs. It may be not suitable
1937 for scientific calculations, but you have to check this for yourself.
1938 If you do not feel you need a faster FP emulation you should better
1942 bool "VFP-format floating point maths"
1943 depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
1945 Say Y to include VFP support code in the kernel. This is needed
1946 if your hardware includes a VFP unit.
1948 Please see <file:Documentation/arm/vfp/release-notes.rst> for
1949 release notes and additional status information.
1951 Say N if your target does not have VFP hardware.
1959 bool "Advanced SIMD (NEON) Extension support"
1960 depends on VFPv3 && CPU_V7
1962 Say Y to include support code for NEON, the ARMv7 Advanced SIMD
1965 config KERNEL_MODE_NEON
1966 bool "Support for NEON in kernel mode"
1967 depends on NEON && AEABI
1969 Say Y to include support for NEON in kernel mode.
1973 menu "Power management options"
1975 source "kernel/power/Kconfig"
1977 config ARCH_SUSPEND_POSSIBLE
1978 depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
1979 CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
1982 config ARM_CPU_SUSPEND
1983 def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
1984 depends on ARCH_SUSPEND_POSSIBLE
1986 config ARCH_HIBERNATION_POSSIBLE
1989 default y if ARCH_SUSPEND_POSSIBLE
1994 source "arch/arm/crypto/Kconfig"
1997 source "arch/arm/Kconfig.assembler"