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_DEBUG_VIRTUAL if MMU
9 select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
10 select ARCH_HAS_ELF_RANDOMIZE
11 select ARCH_HAS_FORTIFY_SOURCE
12 select ARCH_HAS_KEEPINITRD
14 select ARCH_HAS_MEMBARRIER_SYNC_CORE
15 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
16 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
17 select ARCH_HAS_PHYS_TO_DMA
18 select ARCH_HAS_SETUP_DMA_OPS
19 select ARCH_HAS_SET_MEMORY
20 select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
21 select ARCH_HAS_STRICT_MODULE_RWX if MMU
22 select ARCH_HAS_SYNC_DMA_FOR_DEVICE if SWIOTLB || !MMU
23 select ARCH_HAS_SYNC_DMA_FOR_CPU if SWIOTLB || !MMU
24 select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
25 select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
26 select ARCH_HAVE_CUSTOM_GPIO_H
27 select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
28 select ARCH_HAS_GCOV_PROFILE_ALL
29 select ARCH_KEEP_MEMBLOCK
30 select ARCH_MIGHT_HAVE_PC_PARPORT
31 select ARCH_NO_SG_CHAIN if !ARM_HAS_SG_CHAIN
32 select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
33 select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
34 select ARCH_SUPPORTS_ATOMIC_RMW
35 select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
36 select ARCH_USE_BUILTIN_BSWAP
37 select ARCH_USE_CMPXCHG_LOCKREF
38 select ARCH_USE_MEMTEST
39 select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
40 select ARCH_WANT_IPC_PARSE_VERSION
41 select ARCH_WANT_LD_ORPHAN_WARN
42 select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
43 select BUILDTIME_TABLE_SORT if MMU
44 select CLONE_BACKWARDS
45 select CPU_PM if SUSPEND || CPU_IDLE
46 select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
47 select DMA_DECLARE_COHERENT
48 select DMA_GLOBAL_POOL if !MMU
50 select DMA_REMAP if MMU
52 select EDAC_ATOMIC_SCRUB
53 select GENERIC_ALLOCATOR
54 select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
55 select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
56 select GENERIC_CLOCKEVENTS_BROADCAST if SMP
57 select GENERIC_IRQ_IPI if SMP
58 select GENERIC_CPU_AUTOPROBE
59 select GENERIC_EARLY_IOREMAP
60 select GENERIC_IDLE_POLL_SETUP
61 select GENERIC_IRQ_PROBE
62 select GENERIC_IRQ_SHOW
63 select GENERIC_IRQ_SHOW_LEVEL
64 select GENERIC_LIB_DEVMEM_IS_ALLOWED
65 select GENERIC_PCI_IOMAP
66 select GENERIC_SCHED_CLOCK
67 select GENERIC_SMP_IDLE_THREAD
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 && !(THUMB2_KERNEL && CC_IS_CLANG)
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 THREAD_INFO_IN_TASK if CURRENT_POINTER_IN_TPIDRURO
130 select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
131 # Above selects are sorted alphabetically; please add new ones
132 # according to that. Thanks.
134 The ARM series is a line of low-power-consumption RISC chip designs
135 licensed by ARM Ltd and targeted at embedded applications and
136 handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
137 manufactured, but legacy ARM-based PC hardware remains popular in
138 Europe. There is an ARM Linux project with a web page at
139 <http://www.arm.linux.org.uk/>.
141 config ARM_HAS_SG_CHAIN
144 config ARM_DMA_USE_IOMMU
146 select ARM_HAS_SG_CHAIN
147 select NEED_SG_DMA_LENGTH
151 config ARM_DMA_IOMMU_ALIGNMENT
152 int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
156 DMA mapping framework by default aligns all buffers to the smallest
157 PAGE_SIZE order which is greater than or equal to the requested buffer
158 size. This works well for buffers up to a few hundreds kilobytes, but
159 for larger buffers it just a waste of address space. Drivers which has
160 relatively small addressing window (like 64Mib) might run out of
161 virtual space with just a few allocations.
163 With this parameter you can specify the maximum PAGE_SIZE order for
164 DMA IOMMU buffers. Larger buffers will be aligned only to this
165 specified order. The order is expressed as a power of two multiplied
170 config SYS_SUPPORTS_APM_EMULATION
175 select GENERIC_ALLOCATOR
186 config STACKTRACE_SUPPORT
190 config LOCKDEP_SUPPORT
194 config ARCH_HAS_ILOG2_U32
197 config ARCH_HAS_ILOG2_U64
200 config ARCH_HAS_BANDGAP
203 config FIX_EARLYCON_MEM
206 config GENERIC_HWEIGHT
210 config GENERIC_CALIBRATE_DELAY
214 config ARCH_MAY_HAVE_PC_FDC
217 config ARCH_SUPPORTS_UPROBES
220 config ARCH_HAS_DMA_SET_COHERENT_MASK
223 config GENERIC_ISA_DMA
229 config NEED_RET_TO_USER
235 config ARM_PATCH_PHYS_VIRT
236 bool "Patch physical to virtual translations at runtime" if EMBEDDED
238 depends on !XIP_KERNEL && MMU
240 Patch phys-to-virt and virt-to-phys translation functions at
241 boot and module load time according to the position of the
242 kernel in system memory.
244 This can only be used with non-XIP MMU kernels where the base
245 of physical memory is at a 2 MiB boundary.
247 Only disable this option if you know that you do not require
248 this feature (eg, building a kernel for a single machine) and
249 you need to shrink the kernel to the minimal size.
251 config NEED_MACH_IO_H
254 Select this when mach/io.h is required to provide special
255 definitions for this platform. The need for mach/io.h should
256 be avoided when possible.
258 config NEED_MACH_MEMORY_H
261 Select this when mach/memory.h is required to provide special
262 definitions for this platform. The need for mach/memory.h should
263 be avoided when possible.
266 hex "Physical address of main memory" if MMU
267 depends on !ARM_PATCH_PHYS_VIRT
268 default DRAM_BASE if !MMU
269 default 0x00000000 if ARCH_FOOTBRIDGE || ARCH_IXP4XX
270 default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
271 default 0x30000000 if ARCH_S3C24XX
272 default 0xa0000000 if ARCH_IOP32X || ARCH_PXA
273 default 0xc0000000 if ARCH_EP93XX || ARCH_SA1100
276 Please provide the physical address corresponding to the
277 location of main memory in your system.
283 config PGTABLE_LEVELS
285 default 3 if ARM_LPAE
291 bool "MMU-based Paged Memory Management Support"
294 Select if you want MMU-based virtualised addressing space
295 support by paged memory management. If unsure, say 'Y'.
297 config ARCH_MMAP_RND_BITS_MIN
300 config ARCH_MMAP_RND_BITS_MAX
301 default 14 if PAGE_OFFSET=0x40000000
302 default 15 if PAGE_OFFSET=0x80000000
306 # The "ARM system type" choice list is ordered alphabetically by option
307 # text. Please add new entries in the option alphabetic order.
310 prompt "ARM system type"
311 default ARM_SINGLE_ARMV7M if !MMU
312 default ARCH_MULTIPLATFORM if MMU
314 config ARCH_MULTIPLATFORM
315 bool "Allow multiple platforms to be selected"
317 select ARCH_FLATMEM_ENABLE
318 select ARCH_SPARSEMEM_ENABLE
319 select ARCH_SELECT_MEMORY_MODEL
320 select ARM_HAS_SG_CHAIN
321 select ARM_PATCH_PHYS_VIRT
325 select GENERIC_IRQ_MULTI_HANDLER
327 select PCI_DOMAINS_GENERIC if PCI
331 config ARM_SINGLE_ARMV7M
332 bool "ARMv7-M based platforms (Cortex-M0/M3/M4)"
345 select ARCH_SPARSEMEM_ENABLE
347 imply ARM_PATCH_PHYS_VIRT
349 select GENERIC_IRQ_MULTI_HANDLER
356 This enables support for the Cirrus EP93xx series of CPUs.
358 config ARCH_FOOTBRIDGE
362 select NEED_MACH_IO_H if !MMU
363 select NEED_MACH_MEMORY_H
365 Support for systems based on the DC21285 companion chip
366 ("FootBridge"), such as the Simtec CATS and the Rebel NetWinder.
374 select NEED_RET_TO_USER
378 Support for Intel's 80219 and IOP32X (XScale) family of
384 select ARCH_HAS_DMA_SET_COHERENT_MASK
385 select ARCH_SUPPORTS_BIG_ENDIAN
387 select DMABOUNCE if PCI
388 select GENERIC_IRQ_MULTI_HANDLER
394 # With the new PCI driver this is not needed
395 select NEED_MACH_IO_H if IXP4XX_PCI_LEGACY
396 select USB_EHCI_BIG_ENDIAN_DESC
397 select USB_EHCI_BIG_ENDIAN_MMIO
399 Support for Intel's IXP4XX (XScale) family of processors.
404 select GENERIC_IRQ_MULTI_HANDLER
410 select PLAT_ORION_LEGACY
412 select PM_GENERIC_DOMAINS if PM
414 Support for the Marvell Dove SoC 88AP510
417 bool "PXA2xx/PXA3xx-based"
420 select ARM_CPU_SUSPEND if PM
426 select CPU_XSCALE if !CPU_XSC3
427 select GENERIC_IRQ_MULTI_HANDLER
434 Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
439 depends on !CC_IS_CLANG && GCC_VERSION < 90100 && GCC_VERSION >= 60000
441 select ARCH_MAY_HAVE_PC_FDC
442 select ARCH_SPARSEMEM_ENABLE
443 select ARM_HAS_SG_CHAIN
446 select HAVE_PATA_PLATFORM
448 select LEGACY_TIMER_TICK
449 select NEED_MACH_IO_H
450 select NEED_MACH_MEMORY_H
453 On the Acorn Risc-PC, Linux can support the internal IDE disk and
454 CD-ROM interface, serial and parallel port, and the floppy drive.
459 select ARCH_SPARSEMEM_ENABLE
462 select TIMER_OF if OF
466 select GENERIC_IRQ_MULTI_HANDLER
470 select NEED_MACH_MEMORY_H
473 Support for StrongARM 11x0 based boards.
476 bool "Samsung S3C24XX SoCs"
478 select CLKSRC_SAMSUNG_PWM
481 select GENERIC_IRQ_MULTI_HANDLER
482 select HAVE_S3C2410_I2C if I2C
483 select NEED_MACH_IO_H
484 select S3C2410_WATCHDOG
489 Samsung S3C2410, S3C2412, S3C2413, S3C2416, S3C2440, S3C2442, S3C2443
490 and S3C2450 SoCs based systems, such as the Simtec Electronics BAST
491 (<http://www.simtec.co.uk/products/EB110ITX/>), the IPAQ 1940 or the
492 Samsung SMDK2410 development board (and derivatives).
499 select GENERIC_IRQ_CHIP
500 select GENERIC_IRQ_MULTI_HANDLER
502 select HAVE_LEGACY_CLK
504 select NEED_MACH_IO_H if PCCARD
505 select NEED_MACH_MEMORY_H
508 Support for older TI OMAP1 (omap7xx, omap15xx or omap16xx)
512 menu "Multiple platform selection"
513 depends on ARCH_MULTIPLATFORM
515 comment "CPU Core family selection"
518 bool "ARMv4 based platforms (FA526)"
519 depends on !ARCH_MULTI_V6_V7
520 select ARCH_MULTI_V4_V5
523 config ARCH_MULTI_V4T
524 bool "ARMv4T based platforms (ARM720T, ARM920T, ...)"
525 depends on !ARCH_MULTI_V6_V7
526 select ARCH_MULTI_V4_V5
527 select CPU_ARM920T if !(CPU_ARM7TDMI || CPU_ARM720T || \
528 CPU_ARM740T || CPU_ARM9TDMI || CPU_ARM922T || \
529 CPU_ARM925T || CPU_ARM940T)
532 bool "ARMv5 based platforms (ARM926T, XSCALE, PJ1, ...)"
533 depends on !ARCH_MULTI_V6_V7
534 select ARCH_MULTI_V4_V5
535 select CPU_ARM926T if !(CPU_ARM946E || CPU_ARM1020 || \
536 CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || \
537 CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_FEROCEON)
539 config ARCH_MULTI_V4_V5
543 bool "ARMv6 based platforms (ARM11)"
544 select ARCH_MULTI_V6_V7
548 bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)"
550 select ARCH_MULTI_V6_V7
554 config ARCH_MULTI_V6_V7
556 select MIGHT_HAVE_CACHE_L2X0
558 config ARCH_MULTI_CPU_AUTO
559 def_bool !(ARCH_MULTI_V4 || ARCH_MULTI_V4T || ARCH_MULTI_V6_V7)
565 bool "Dummy Virtual Machine"
566 depends on ARCH_MULTI_V7
569 select ARM_GIC_V2M if PCI
571 select ARM_GIC_V3_ITS if PCI
573 select HAVE_ARM_ARCH_TIMER
574 select ARCH_SUPPORTS_BIG_ENDIAN
577 # This is sorted alphabetically by mach-* pathname. However, plat-*
578 # Kconfigs may be included either alphabetically (according to the
579 # plat- suffix) or along side the corresponding mach-* source.
581 source "arch/arm/mach-actions/Kconfig"
583 source "arch/arm/mach-alpine/Kconfig"
585 source "arch/arm/mach-artpec/Kconfig"
587 source "arch/arm/mach-asm9260/Kconfig"
589 source "arch/arm/mach-aspeed/Kconfig"
591 source "arch/arm/mach-at91/Kconfig"
593 source "arch/arm/mach-axxia/Kconfig"
595 source "arch/arm/mach-bcm/Kconfig"
597 source "arch/arm/mach-berlin/Kconfig"
599 source "arch/arm/mach-clps711x/Kconfig"
601 source "arch/arm/mach-cns3xxx/Kconfig"
603 source "arch/arm/mach-davinci/Kconfig"
605 source "arch/arm/mach-digicolor/Kconfig"
607 source "arch/arm/mach-dove/Kconfig"
609 source "arch/arm/mach-ep93xx/Kconfig"
611 source "arch/arm/mach-exynos/Kconfig"
613 source "arch/arm/mach-footbridge/Kconfig"
615 source "arch/arm/mach-gemini/Kconfig"
617 source "arch/arm/mach-highbank/Kconfig"
619 source "arch/arm/mach-hisi/Kconfig"
621 source "arch/arm/mach-imx/Kconfig"
623 source "arch/arm/mach-integrator/Kconfig"
625 source "arch/arm/mach-iop32x/Kconfig"
627 source "arch/arm/mach-ixp4xx/Kconfig"
629 source "arch/arm/mach-keystone/Kconfig"
631 source "arch/arm/mach-lpc32xx/Kconfig"
633 source "arch/arm/mach-mediatek/Kconfig"
635 source "arch/arm/mach-meson/Kconfig"
637 source "arch/arm/mach-milbeaut/Kconfig"
639 source "arch/arm/mach-mmp/Kconfig"
641 source "arch/arm/mach-moxart/Kconfig"
643 source "arch/arm/mach-mstar/Kconfig"
645 source "arch/arm/mach-mv78xx0/Kconfig"
647 source "arch/arm/mach-mvebu/Kconfig"
649 source "arch/arm/mach-mxs/Kconfig"
651 source "arch/arm/mach-nomadik/Kconfig"
653 source "arch/arm/mach-npcm/Kconfig"
655 source "arch/arm/mach-nspire/Kconfig"
657 source "arch/arm/plat-omap/Kconfig"
659 source "arch/arm/mach-omap1/Kconfig"
661 source "arch/arm/mach-omap2/Kconfig"
663 source "arch/arm/mach-orion5x/Kconfig"
665 source "arch/arm/mach-oxnas/Kconfig"
667 source "arch/arm/mach-pxa/Kconfig"
668 source "arch/arm/plat-pxa/Kconfig"
670 source "arch/arm/mach-qcom/Kconfig"
672 source "arch/arm/mach-rda/Kconfig"
674 source "arch/arm/mach-realtek/Kconfig"
676 source "arch/arm/mach-realview/Kconfig"
678 source "arch/arm/mach-rockchip/Kconfig"
680 source "arch/arm/mach-s3c/Kconfig"
682 source "arch/arm/mach-s5pv210/Kconfig"
684 source "arch/arm/mach-sa1100/Kconfig"
686 source "arch/arm/mach-shmobile/Kconfig"
688 source "arch/arm/mach-socfpga/Kconfig"
690 source "arch/arm/mach-spear/Kconfig"
692 source "arch/arm/mach-sti/Kconfig"
694 source "arch/arm/mach-stm32/Kconfig"
696 source "arch/arm/mach-sunxi/Kconfig"
698 source "arch/arm/mach-tegra/Kconfig"
700 source "arch/arm/mach-uniphier/Kconfig"
702 source "arch/arm/mach-ux500/Kconfig"
704 source "arch/arm/mach-versatile/Kconfig"
706 source "arch/arm/mach-vexpress/Kconfig"
708 source "arch/arm/mach-vt8500/Kconfig"
710 source "arch/arm/mach-zynq/Kconfig"
712 # ARMv7-M architecture
714 bool "NXP LPC18xx/LPC43xx"
715 depends on ARM_SINGLE_ARMV7M
716 select ARCH_HAS_RESET_CONTROLLER
718 select CLKSRC_LPC32XX
721 Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
722 high performance microcontrollers.
725 bool "ARM MPS2 platform"
726 depends on ARM_SINGLE_ARMV7M
730 Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
731 with a range of available cores like Cortex-M3/M4/M7.
733 Please, note that depends which Application Note is used memory map
734 for the platform may vary, so adjustment of RAM base might be needed.
736 # Definitions to make life easier
747 select GENERIC_IRQ_CHIP
750 config PLAT_ORION_LEGACY
757 config PLAT_VERSATILE
760 source "arch/arm/mm/Kconfig"
763 bool "Enable iWMMXt support"
764 depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
765 default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B
767 Enable support for iWMMXt context switching at run time if
768 running on a CPU that supports it.
771 source "arch/arm/Kconfig-nommu"
774 config PJ4B_ERRATA_4742
775 bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
776 depends on CPU_PJ4B && MACH_ARMADA_370
779 When coming out of either a Wait for Interrupt (WFI) or a Wait for
780 Event (WFE) IDLE states, a specific timing sensitivity exists between
781 the retiring WFI/WFE instructions and the newly issued subsequent
782 instructions. This sensitivity can result in a CPU hang scenario.
784 The software must insert either a Data Synchronization Barrier (DSB)
785 or Data Memory Barrier (DMB) command immediately after the WFI/WFE
788 config ARM_ERRATA_326103
789 bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
792 Executing a SWP instruction to read-only memory does not set bit 11
793 of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
794 treat the access as a read, preventing a COW from occurring and
795 causing the faulting task to livelock.
797 config ARM_ERRATA_411920
798 bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
799 depends on CPU_V6 || CPU_V6K
801 Invalidation of the Instruction Cache operation can
802 fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
803 It does not affect the MPCore. This option enables the ARM Ltd.
804 recommended workaround.
806 config ARM_ERRATA_430973
807 bool "ARM errata: Stale prediction on replaced interworking branch"
810 This option enables the workaround for the 430973 Cortex-A8
811 r1p* erratum. If a code sequence containing an ARM/Thumb
812 interworking branch is replaced with another code sequence at the
813 same virtual address, whether due to self-modifying code or virtual
814 to physical address re-mapping, Cortex-A8 does not recover from the
815 stale interworking branch prediction. This results in Cortex-A8
816 executing the new code sequence in the incorrect ARM or Thumb state.
817 The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
818 and also flushes the branch target cache at every context switch.
819 Note that setting specific bits in the ACTLR register may not be
820 available in non-secure mode.
822 config ARM_ERRATA_458693
823 bool "ARM errata: Processor deadlock when a false hazard is created"
825 depends on !ARCH_MULTIPLATFORM
827 This option enables the workaround for the 458693 Cortex-A8 (r2p0)
828 erratum. For very specific sequences of memory operations, it is
829 possible for a hazard condition intended for a cache line to instead
830 be incorrectly associated with a different cache line. This false
831 hazard might then cause a processor deadlock. The workaround enables
832 the L1 caching of the NEON accesses and disables the PLD instruction
833 in the ACTLR register. Note that setting specific bits in the ACTLR
834 register may not be available in non-secure mode.
836 config ARM_ERRATA_460075
837 bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
839 depends on !ARCH_MULTIPLATFORM
841 This option enables the workaround for the 460075 Cortex-A8 (r2p0)
842 erratum. Any asynchronous access to the L2 cache may encounter a
843 situation in which recent store transactions to the L2 cache are lost
844 and overwritten with stale memory contents from external memory. The
845 workaround disables the write-allocate mode for the L2 cache via the
846 ACTLR register. Note that setting specific bits in the ACTLR register
847 may not be available in non-secure mode.
849 config ARM_ERRATA_742230
850 bool "ARM errata: DMB operation may be faulty"
851 depends on CPU_V7 && SMP
852 depends on !ARCH_MULTIPLATFORM
854 This option enables the workaround for the 742230 Cortex-A9
855 (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
856 between two write operations may not ensure the correct visibility
857 ordering of the two writes. This workaround sets a specific bit in
858 the diagnostic register of the Cortex-A9 which causes the DMB
859 instruction to behave as a DSB, ensuring the correct behaviour of
862 config ARM_ERRATA_742231
863 bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
864 depends on CPU_V7 && SMP
865 depends on !ARCH_MULTIPLATFORM
867 This option enables the workaround for the 742231 Cortex-A9
868 (r2p0..r2p2) erratum. Under certain conditions, specific to the
869 Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
870 accessing some data located in the same cache line, may get corrupted
871 data due to bad handling of the address hazard when the line gets
872 replaced from one of the CPUs at the same time as another CPU is
873 accessing it. This workaround sets specific bits in the diagnostic
874 register of the Cortex-A9 which reduces the linefill issuing
875 capabilities of the processor.
877 config ARM_ERRATA_643719
878 bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
879 depends on CPU_V7 && SMP
882 This option enables the workaround for the 643719 Cortex-A9 (prior to
883 r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
884 register returns zero when it should return one. The workaround
885 corrects this value, ensuring cache maintenance operations which use
886 it behave as intended and avoiding data corruption.
888 config ARM_ERRATA_720789
889 bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
892 This option enables the workaround for the 720789 Cortex-A9 (prior to
893 r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
894 broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
895 As a consequence of this erratum, some TLB entries which should be
896 invalidated are not, resulting in an incoherency in the system page
897 tables. The workaround changes the TLB flushing routines to invalidate
898 entries regardless of the ASID.
900 config ARM_ERRATA_743622
901 bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
903 depends on !ARCH_MULTIPLATFORM
905 This option enables the workaround for the 743622 Cortex-A9
906 (r2p*) erratum. Under very rare conditions, a faulty
907 optimisation in the Cortex-A9 Store Buffer may lead to data
908 corruption. This workaround sets a specific bit in the diagnostic
909 register of the Cortex-A9 which disables the Store Buffer
910 optimisation, preventing the defect from occurring. This has no
911 visible impact on the overall performance or power consumption of the
914 config ARM_ERRATA_751472
915 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
917 depends on !ARCH_MULTIPLATFORM
919 This option enables the workaround for the 751472 Cortex-A9 (prior
920 to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
921 completion of a following broadcasted operation if the second
922 operation is received by a CPU before the ICIALLUIS has completed,
923 potentially leading to corrupted entries in the cache or TLB.
925 config ARM_ERRATA_754322
926 bool "ARM errata: possible faulty MMU translations following an ASID switch"
929 This option enables the workaround for the 754322 Cortex-A9 (r2p*,
930 r3p*) erratum. A speculative memory access may cause a page table walk
931 which starts prior to an ASID switch but completes afterwards. This
932 can populate the micro-TLB with a stale entry which may be hit with
933 the new ASID. This workaround places two dsb instructions in the mm
934 switching code so that no page table walks can cross the ASID switch.
936 config ARM_ERRATA_754327
937 bool "ARM errata: no automatic Store Buffer drain"
938 depends on CPU_V7 && SMP
940 This option enables the workaround for the 754327 Cortex-A9 (prior to
941 r2p0) erratum. The Store Buffer does not have any automatic draining
942 mechanism and therefore a livelock may occur if an external agent
943 continuously polls a memory location waiting to observe an update.
944 This workaround defines cpu_relax() as smp_mb(), preventing correctly
945 written polling loops from denying visibility of updates to memory.
947 config ARM_ERRATA_364296
948 bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
951 This options enables the workaround for the 364296 ARM1136
952 r0p2 erratum (possible cache data corruption with
953 hit-under-miss enabled). It sets the undocumented bit 31 in
954 the auxiliary control register and the FI bit in the control
955 register, thus disabling hit-under-miss without putting the
956 processor into full low interrupt latency mode. ARM11MPCore
959 config ARM_ERRATA_764369
960 bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
961 depends on CPU_V7 && SMP
963 This option enables the workaround for erratum 764369
964 affecting Cortex-A9 MPCore with two or more processors (all
965 current revisions). Under certain timing circumstances, a data
966 cache line maintenance operation by MVA targeting an Inner
967 Shareable memory region may fail to proceed up to either the
968 Point of Coherency or to the Point of Unification of the
969 system. This workaround adds a DSB instruction before the
970 relevant cache maintenance functions and sets a specific bit
971 in the diagnostic control register of the SCU.
973 config ARM_ERRATA_775420
974 bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
977 This option enables the workaround for the 775420 Cortex-A9 (r2p2,
978 r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
979 operation aborts with MMU exception, it might cause the processor
980 to deadlock. This workaround puts DSB before executing ISB if
981 an abort may occur on cache maintenance.
983 config ARM_ERRATA_798181
984 bool "ARM errata: TLBI/DSB failure on Cortex-A15"
985 depends on CPU_V7 && SMP
987 On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
988 adequately shooting down all use of the old entries. This
989 option enables the Linux kernel workaround for this erratum
990 which sends an IPI to the CPUs that are running the same ASID
991 as the one being invalidated.
993 config ARM_ERRATA_773022
994 bool "ARM errata: incorrect instructions may be executed from loop buffer"
997 This option enables the workaround for the 773022 Cortex-A15
998 (up to r0p4) erratum. In certain rare sequences of code, the
999 loop buffer may deliver incorrect instructions. This
1000 workaround disables the loop buffer to avoid the erratum.
1002 config ARM_ERRATA_818325_852422
1003 bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
1006 This option enables the workaround for:
1007 - Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
1008 instruction might deadlock. Fixed in r0p1.
1009 - Cortex-A12 852422: Execution of a sequence of instructions might
1010 lead to either a data corruption or a CPU deadlock. Not fixed in
1011 any Cortex-A12 cores yet.
1012 This workaround for all both errata involves setting bit[12] of the
1013 Feature Register. This bit disables an optimisation applied to a
1014 sequence of 2 instructions that use opposing condition codes.
1016 config ARM_ERRATA_821420
1017 bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
1020 This option enables the workaround for the 821420 Cortex-A12
1021 (all revs) erratum. In very rare timing conditions, a sequence
1022 of VMOV to Core registers instructions, for which the second
1023 one is in the shadow of a branch or abort, can lead to a
1024 deadlock when the VMOV instructions are issued out-of-order.
1026 config ARM_ERRATA_825619
1027 bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
1030 This option enables the workaround for the 825619 Cortex-A12
1031 (all revs) erratum. Within rare timing constraints, executing a
1032 DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
1033 and Device/Strongly-Ordered loads and stores might cause deadlock
1035 config ARM_ERRATA_857271
1036 bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
1039 This option enables the workaround for the 857271 Cortex-A12
1040 (all revs) erratum. Under very rare timing conditions, the CPU might
1041 hang. The workaround is expected to have a < 1% performance impact.
1043 config ARM_ERRATA_852421
1044 bool "ARM errata: A17: DMB ST might fail to create order between stores"
1047 This option enables the workaround for the 852421 Cortex-A17
1048 (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
1049 execution of a DMB ST instruction might fail to properly order
1050 stores from GroupA and stores from GroupB.
1052 config ARM_ERRATA_852423
1053 bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
1056 This option enables the workaround for:
1057 - Cortex-A17 852423: Execution of a sequence of instructions might
1058 lead to either a data corruption or a CPU deadlock. Not fixed in
1059 any Cortex-A17 cores yet.
1060 This is identical to Cortex-A12 erratum 852422. It is a separate
1061 config option from the A12 erratum due to the way errata are checked
1064 config ARM_ERRATA_857272
1065 bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
1068 This option enables the workaround for the 857272 Cortex-A17 erratum.
1069 This erratum is not known to be fixed in any A17 revision.
1070 This is identical to Cortex-A12 erratum 857271. It is a separate
1071 config option from the A12 erratum due to the way errata are checked
1076 source "arch/arm/common/Kconfig"
1083 Find out whether you have ISA slots on your motherboard. ISA is the
1084 name of a bus system, i.e. the way the CPU talks to the other stuff
1085 inside your box. Other bus systems are PCI, EISA, MicroChannel
1086 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1087 newer boards don't support it. If you have ISA, say Y, otherwise N.
1089 # Select ISA DMA controller support
1094 # Select ISA DMA interface
1098 config PCI_NANOENGINE
1099 bool "BSE nanoEngine PCI support"
1100 depends on SA1100_NANOENGINE
1102 Enable PCI on the BSE nanoEngine board.
1104 config ARM_ERRATA_814220
1105 bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
1108 The v7 ARM states that all cache and branch predictor maintenance
1109 operations that do not specify an address execute, relative to
1110 each other, in program order.
1111 However, because of this erratum, an L2 set/way cache maintenance
1112 operation can overtake an L1 set/way cache maintenance operation.
1113 This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
1118 menu "Kernel Features"
1123 This option should be selected by machines which have an SMP-
1126 The only effect of this option is to make the SMP-related
1127 options available to the user for configuration.
1130 bool "Symmetric Multi-Processing"
1131 depends on CPU_V6K || CPU_V7
1133 depends on MMU || ARM_MPU
1136 This enables support for systems with more than one CPU. If you have
1137 a system with only one CPU, say N. If you have a system with more
1138 than one CPU, say Y.
1140 If you say N here, the kernel will run on uni- and multiprocessor
1141 machines, but will use only one CPU of a multiprocessor machine. If
1142 you say Y here, the kernel will run on many, but not all,
1143 uniprocessor machines. On a uniprocessor machine, the kernel
1144 will run faster if you say N here.
1146 See also <file:Documentation/x86/i386/IO-APIC.rst>,
1147 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
1148 <http://tldp.org/HOWTO/SMP-HOWTO.html>.
1150 If you don't know what to do here, say N.
1153 bool "Allow booting SMP kernel on uniprocessor systems"
1154 depends on SMP && !XIP_KERNEL && MMU
1157 SMP kernels contain instructions which fail on non-SMP processors.
1158 Enabling this option allows the kernel to modify itself to make
1159 these instructions safe. Disabling it allows about 1K of space
1162 If you don't know what to do here, say Y.
1165 config CURRENT_POINTER_IN_TPIDRURO
1167 depends on SMP && CPU_32v6K && !CPU_V6
1169 config ARM_CPU_TOPOLOGY
1170 bool "Support cpu topology definition"
1171 depends on SMP && CPU_V7
1174 Support ARM cpu topology definition. The MPIDR register defines
1175 affinity between processors which is then used to describe the cpu
1176 topology of an ARM System.
1179 bool "Multi-core scheduler support"
1180 depends on ARM_CPU_TOPOLOGY
1182 Multi-core scheduler support improves the CPU scheduler's decision
1183 making when dealing with multi-core CPU chips at a cost of slightly
1184 increased overhead in some places. If unsure say N here.
1187 bool "SMT scheduler support"
1188 depends on ARM_CPU_TOPOLOGY
1190 Improves the CPU scheduler's decision making when dealing with
1191 MultiThreading at a cost of slightly increased overhead in some
1192 places. If unsure say N here.
1197 This option enables support for the ARM snoop control unit
1199 config HAVE_ARM_ARCH_TIMER
1200 bool "Architected timer support"
1202 select ARM_ARCH_TIMER
1204 This option enables support for the ARM architected timer
1209 This options enables support for the ARM timer and watchdog unit
1212 bool "Multi-Cluster Power Management"
1213 depends on CPU_V7 && SMP
1215 This option provides the common power management infrastructure
1216 for (multi-)cluster based systems, such as big.LITTLE based
1219 config MCPM_QUAD_CLUSTER
1223 To avoid wasting resources unnecessarily, MCPM only supports up
1224 to 2 clusters by default.
1225 Platforms with 3 or 4 clusters that use MCPM must select this
1226 option to allow the additional clusters to be managed.
1229 bool "big.LITTLE support (Experimental)"
1230 depends on CPU_V7 && SMP
1233 This option enables support selections for the big.LITTLE
1234 system architecture.
1237 bool "big.LITTLE switcher support"
1238 depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
1241 The big.LITTLE "switcher" provides the core functionality to
1242 transparently handle transition between a cluster of A15's
1243 and a cluster of A7's in a big.LITTLE system.
1245 config BL_SWITCHER_DUMMY_IF
1246 tristate "Simple big.LITTLE switcher user interface"
1247 depends on BL_SWITCHER && DEBUG_KERNEL
1249 This is a simple and dummy char dev interface to control
1250 the big.LITTLE switcher core code. It is meant for
1251 debugging purposes only.
1254 prompt "Memory split"
1258 Select the desired split between kernel and user memory.
1260 If you are not absolutely sure what you are doing, leave this
1264 bool "3G/1G user/kernel split"
1265 config VMSPLIT_3G_OPT
1266 depends on !ARM_LPAE
1267 bool "3G/1G user/kernel split (for full 1G low memory)"
1269 bool "2G/2G user/kernel split"
1271 bool "1G/3G user/kernel split"
1276 default PHYS_OFFSET if !MMU
1277 default 0x40000000 if VMSPLIT_1G
1278 default 0x80000000 if VMSPLIT_2G
1279 default 0xB0000000 if VMSPLIT_3G_OPT
1282 config KASAN_SHADOW_OFFSET
1285 default 0x1f000000 if PAGE_OFFSET=0x40000000
1286 default 0x5f000000 if PAGE_OFFSET=0x80000000
1287 default 0x9f000000 if PAGE_OFFSET=0xC0000000
1288 default 0x8f000000 if PAGE_OFFSET=0xB0000000
1292 int "Maximum number of CPUs (2-32)"
1293 range 2 16 if DEBUG_KMAP_LOCAL
1294 range 2 32 if !DEBUG_KMAP_LOCAL
1298 The maximum number of CPUs that the kernel can support.
1299 Up to 32 CPUs can be supported, or up to 16 if kmap_local()
1300 debugging is enabled, which uses half of the per-CPU fixmap
1301 slots as guard regions.
1304 bool "Support for hot-pluggable CPUs"
1306 select GENERIC_IRQ_MIGRATION
1308 Say Y here to experiment with turning CPUs off and on. CPUs
1309 can be controlled through /sys/devices/system/cpu.
1312 bool "Support for the ARM Power State Coordination Interface (PSCI)"
1313 depends on HAVE_ARM_SMCCC
1316 Say Y here if you want Linux to communicate with system firmware
1317 implementing the PSCI specification for CPU-centric power
1318 management operations described in ARM document number ARM DEN
1319 0022A ("Power State Coordination Interface System Software on
1322 # The GPIO number here must be sorted by descending number. In case of
1323 # a multiplatform kernel, we just want the highest value required by the
1324 # selected platforms.
1327 default 2048 if ARCH_INTEL_SOCFPGA
1328 default 1024 if ARCH_BRCMSTB || ARCH_RENESAS || ARCH_TEGRA || \
1329 ARCH_ZYNQ || ARCH_ASPEED
1330 default 512 if ARCH_EXYNOS || ARCH_KEYSTONE || SOC_OMAP5 || \
1331 SOC_DRA7XX || ARCH_S3C24XX || ARCH_S3C64XX || ARCH_S5PV210
1332 default 416 if ARCH_SUNXI
1333 default 392 if ARCH_U8500
1334 default 352 if ARCH_VT8500
1335 default 288 if ARCH_ROCKCHIP
1336 default 264 if MACH_H4700
1339 Maximum number of GPIOs in the system.
1341 If unsure, leave the default value.
1345 default 128 if SOC_AT91RM9200
1349 depends on HZ_FIXED = 0
1350 prompt "Timer frequency"
1374 default HZ_FIXED if HZ_FIXED != 0
1375 default 100 if HZ_100
1376 default 200 if HZ_200
1377 default 250 if HZ_250
1378 default 300 if HZ_300
1379 default 500 if HZ_500
1383 def_bool HIGH_RES_TIMERS
1385 config THUMB2_KERNEL
1386 bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
1387 depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
1388 default y if CPU_THUMBONLY
1391 By enabling this option, the kernel will be compiled in
1396 config ARM_PATCH_IDIV
1397 bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
1398 depends on CPU_32v7 && !XIP_KERNEL
1401 The ARM compiler inserts calls to __aeabi_idiv() and
1402 __aeabi_uidiv() when it needs to perform division on signed
1403 and unsigned integers. Some v7 CPUs have support for the sdiv
1404 and udiv instructions that can be used to implement those
1407 Enabling this option allows the kernel to modify itself to
1408 replace the first two instructions of these library functions
1409 with the sdiv or udiv plus "bx lr" instructions when the CPU
1410 it is running on supports them. Typically this will be faster
1411 and less power intensive than running the original library
1412 code to do integer division.
1415 bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
1416 !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
1417 default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
1419 This option allows for the kernel to be compiled using the latest
1420 ARM ABI (aka EABI). This is only useful if you are using a user
1421 space environment that is also compiled with EABI.
1423 Since there are major incompatibilities between the legacy ABI and
1424 EABI, especially with regard to structure member alignment, this
1425 option also changes the kernel syscall calling convention to
1426 disambiguate both ABIs and allow for backward compatibility support
1427 (selected with CONFIG_OABI_COMPAT).
1429 To use this you need GCC version 4.0.0 or later.
1432 bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
1433 depends on AEABI && !THUMB2_KERNEL
1435 This option preserves the old syscall interface along with the
1436 new (ARM EABI) one. It also provides a compatibility layer to
1437 intercept syscalls that have structure arguments which layout
1438 in memory differs between the legacy ABI and the new ARM EABI
1439 (only for non "thumb" binaries). This option adds a tiny
1440 overhead to all syscalls and produces a slightly larger kernel.
1442 The seccomp filter system will not be available when this is
1443 selected, since there is no way yet to sensibly distinguish
1444 between calling conventions during filtering.
1446 If you know you'll be using only pure EABI user space then you
1447 can say N here. If this option is not selected and you attempt
1448 to execute a legacy ABI binary then the result will be
1449 UNPREDICTABLE (in fact it can be predicted that it won't work
1450 at all). If in doubt say N.
1452 config ARCH_SELECT_MEMORY_MODEL
1455 config ARCH_FLATMEM_ENABLE
1458 config ARCH_SPARSEMEM_ENABLE
1460 select SPARSEMEM_STATIC if SPARSEMEM
1463 bool "High Memory Support"
1467 The address space of ARM processors is only 4 Gigabytes large
1468 and it has to accommodate user address space, kernel address
1469 space as well as some memory mapped IO. That means that, if you
1470 have a large amount of physical memory and/or IO, not all of the
1471 memory can be "permanently mapped" by the kernel. The physical
1472 memory that is not permanently mapped is called "high memory".
1474 Depending on the selected kernel/user memory split, minimum
1475 vmalloc space and actual amount of RAM, you may not need this
1476 option which should result in a slightly faster kernel.
1481 bool "Allocate 2nd-level pagetables from highmem" if EXPERT
1485 The VM uses one page of physical memory for each page table.
1486 For systems with a lot of processes, this can use a lot of
1487 precious low memory, eventually leading to low memory being
1488 consumed by page tables. Setting this option will allow
1489 user-space 2nd level page tables to reside in high memory.
1491 config CPU_SW_DOMAIN_PAN
1492 bool "Enable use of CPU domains to implement privileged no-access"
1493 depends on MMU && !ARM_LPAE
1496 Increase kernel security by ensuring that normal kernel accesses
1497 are unable to access userspace addresses. This can help prevent
1498 use-after-free bugs becoming an exploitable privilege escalation
1499 by ensuring that magic values (such as LIST_POISON) will always
1500 fault when dereferenced.
1502 CPUs with low-vector mappings use a best-efforts implementation.
1503 Their lower 1MB needs to remain accessible for the vectors, but
1504 the remainder of userspace will become appropriately inaccessible.
1506 config HW_PERF_EVENTS
1510 config ARCH_WANT_GENERAL_HUGETLB
1513 config ARM_MODULE_PLTS
1514 bool "Use PLTs to allow module memory to spill over into vmalloc area"
1518 Allocate PLTs when loading modules so that jumps and calls whose
1519 targets are too far away for their relative offsets to be encoded
1520 in the instructions themselves can be bounced via veneers in the
1521 module's PLT. This allows modules to be allocated in the generic
1522 vmalloc area after the dedicated module memory area has been
1523 exhausted. The modules will use slightly more memory, but after
1524 rounding up to page size, the actual memory footprint is usually
1527 Disabling this is usually safe for small single-platform
1528 configurations. If unsure, say y.
1530 config FORCE_MAX_ZONEORDER
1531 int "Maximum zone order"
1532 default "12" if SOC_AM33XX
1533 default "9" if SA1111
1536 The kernel memory allocator divides physically contiguous memory
1537 blocks into "zones", where each zone is a power of two number of
1538 pages. This option selects the largest power of two that the kernel
1539 keeps in the memory allocator. If you need to allocate very large
1540 blocks of physically contiguous memory, then you may need to
1541 increase this value.
1543 This config option is actually maximum order plus one. For example,
1544 a value of 11 means that the largest free memory block is 2^10 pages.
1546 config ALIGNMENT_TRAP
1547 def_bool CPU_CP15_MMU
1548 select HAVE_PROC_CPU if PROC_FS
1550 ARM processors cannot fetch/store information which is not
1551 naturally aligned on the bus, i.e., a 4 byte fetch must start at an
1552 address divisible by 4. On 32-bit ARM processors, these non-aligned
1553 fetch/store instructions will be emulated in software if you say
1554 here, which has a severe performance impact. This is necessary for
1555 correct operation of some network protocols. With an IP-only
1556 configuration it is safe to say N, otherwise say Y.
1558 config UACCESS_WITH_MEMCPY
1559 bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
1561 default y if CPU_FEROCEON
1563 Implement faster copy_to_user and clear_user methods for CPU
1564 cores where a 8-word STM instruction give significantly higher
1565 memory write throughput than a sequence of individual 32bit stores.
1567 A possible side effect is a slight increase in scheduling latency
1568 between threads sharing the same address space if they invoke
1569 such copy operations with large buffers.
1571 However, if the CPU data cache is using a write-allocate mode,
1572 this option is unlikely to provide any performance gain.
1575 bool "Enable paravirtualization code"
1577 This changes the kernel so it can modify itself when it is run
1578 under a hypervisor, potentially improving performance significantly
1579 over full virtualization.
1581 config PARAVIRT_TIME_ACCOUNTING
1582 bool "Paravirtual steal time accounting"
1585 Select this option to enable fine granularity task steal time
1586 accounting. Time spent executing other tasks in parallel with
1587 the current vCPU is discounted from the vCPU power. To account for
1588 that, there can be a small performance impact.
1590 If in doubt, say N here.
1597 bool "Xen guest support on ARM"
1598 depends on ARM && AEABI && OF
1599 depends on CPU_V7 && !CPU_V6
1600 depends on !GENERIC_ATOMIC64
1602 select ARCH_DMA_ADDR_T_64BIT
1608 Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
1610 config STACKPROTECTOR_PER_TASK
1611 bool "Use a unique stack canary value for each task"
1612 depends on GCC_PLUGINS && STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA
1613 select GCC_PLUGIN_ARM_SSP_PER_TASK
1616 Due to the fact that GCC uses an ordinary symbol reference from
1617 which to load the value of the stack canary, this value can only
1618 change at reboot time on SMP systems, and all tasks running in the
1619 kernel's address space are forced to use the same canary value for
1620 the entire duration that the system is up.
1622 Enable this option to switch to a different method that uses a
1623 different canary value for each task.
1630 bool "Flattened Device Tree support"
1634 Include support for flattened device tree machine descriptions.
1637 bool "Support for the traditional ATAGS boot data passing" if USE_OF
1640 This is the traditional way of passing data to the kernel at boot
1641 time. If you are solely relying on the flattened device tree (or
1642 the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
1643 to remove ATAGS support from your kernel binary. If unsure,
1646 config DEPRECATED_PARAM_STRUCT
1647 bool "Provide old way to pass kernel parameters"
1650 This was deprecated in 2001 and announced to live on for 5 years.
1651 Some old boot loaders still use this way.
1653 # Compressed boot loader in ROM. Yes, we really want to ask about
1654 # TEXT and BSS so we preserve their values in the config files.
1655 config ZBOOT_ROM_TEXT
1656 hex "Compressed ROM boot loader base address"
1659 The physical address at which the ROM-able zImage is to be
1660 placed in the target. Platforms which normally make use of
1661 ROM-able zImage formats normally set this to a suitable
1662 value in their defconfig file.
1664 If ZBOOT_ROM is not enabled, this has no effect.
1666 config ZBOOT_ROM_BSS
1667 hex "Compressed ROM boot loader BSS address"
1670 The base address of an area of read/write memory in the target
1671 for the ROM-able zImage which must be available while the
1672 decompressor is running. It must be large enough to hold the
1673 entire decompressed kernel plus an additional 128 KiB.
1674 Platforms which normally make use of ROM-able zImage formats
1675 normally set this to a suitable value in their defconfig file.
1677 If ZBOOT_ROM is not enabled, this has no effect.
1680 bool "Compressed boot loader in ROM/flash"
1681 depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
1682 depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
1684 Say Y here if you intend to execute your compressed kernel image
1685 (zImage) directly from ROM or flash. If unsure, say N.
1687 config ARM_APPENDED_DTB
1688 bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
1691 With this option, the boot code will look for a device tree binary
1692 (DTB) appended to zImage
1693 (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
1695 This is meant as a backward compatibility convenience for those
1696 systems with a bootloader that can't be upgraded to accommodate
1697 the documented boot protocol using a device tree.
1699 Beware that there is very little in terms of protection against
1700 this option being confused by leftover garbage in memory that might
1701 look like a DTB header after a reboot if no actual DTB is appended
1702 to zImage. Do not leave this option active in a production kernel
1703 if you don't intend to always append a DTB. Proper passing of the
1704 location into r2 of a bootloader provided DTB is always preferable
1707 config ARM_ATAG_DTB_COMPAT
1708 bool "Supplement the appended DTB with traditional ATAG information"
1709 depends on ARM_APPENDED_DTB
1711 Some old bootloaders can't be updated to a DTB capable one, yet
1712 they provide ATAGs with memory configuration, the ramdisk address,
1713 the kernel cmdline string, etc. Such information is dynamically
1714 provided by the bootloader and can't always be stored in a static
1715 DTB. To allow a device tree enabled kernel to be used with such
1716 bootloaders, this option allows zImage to extract the information
1717 from the ATAG list and store it at run time into the appended DTB.
1720 prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
1721 default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1723 config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
1724 bool "Use bootloader kernel arguments if available"
1726 Uses the command-line options passed by the boot loader instead of
1727 the device tree bootargs property. If the boot loader doesn't provide
1728 any, the device tree bootargs property will be used.
1730 config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
1731 bool "Extend with bootloader kernel arguments"
1733 The command-line arguments provided by the boot loader will be
1734 appended to the the device tree bootargs property.
1739 string "Default kernel command string"
1742 On some architectures (e.g. CATS), there is currently no way
1743 for the boot loader to pass arguments to the kernel. For these
1744 architectures, you should supply some command-line options at build
1745 time by entering them here. As a minimum, you should specify the
1746 memory size and the root device (e.g., mem=64M root=/dev/nfs).
1749 prompt "Kernel command line type" if CMDLINE != ""
1750 default CMDLINE_FROM_BOOTLOADER
1753 config CMDLINE_FROM_BOOTLOADER
1754 bool "Use bootloader kernel arguments if available"
1756 Uses the command-line options passed by the boot loader. If
1757 the boot loader doesn't provide any, the default kernel command
1758 string provided in CMDLINE will be used.
1760 config CMDLINE_EXTEND
1761 bool "Extend bootloader kernel arguments"
1763 The command-line arguments provided by the boot loader will be
1764 appended to the default kernel command string.
1766 config CMDLINE_FORCE
1767 bool "Always use the default kernel command string"
1769 Always use the default kernel command string, even if the boot
1770 loader passes other arguments to the kernel.
1771 This is useful if you cannot or don't want to change the
1772 command-line options your boot loader passes to the kernel.
1776 bool "Kernel Execute-In-Place from ROM"
1777 depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
1779 Execute-In-Place allows the kernel to run from non-volatile storage
1780 directly addressable by the CPU, such as NOR flash. This saves RAM
1781 space since the text section of the kernel is not loaded from flash
1782 to RAM. Read-write sections, such as the data section and stack,
1783 are still copied to RAM. The XIP kernel is not compressed since
1784 it has to run directly from flash, so it will take more space to
1785 store it. The flash address used to link the kernel object files,
1786 and for storing it, is configuration dependent. Therefore, if you
1787 say Y here, you must know the proper physical address where to
1788 store the kernel image depending on your own flash memory usage.
1790 Also note that the make target becomes "make xipImage" rather than
1791 "make zImage" or "make Image". The final kernel binary to put in
1792 ROM memory will be arch/arm/boot/xipImage.
1796 config XIP_PHYS_ADDR
1797 hex "XIP Kernel Physical Location"
1798 depends on XIP_KERNEL
1799 default "0x00080000"
1801 This is the physical address in your flash memory the kernel will
1802 be linked for and stored to. This address is dependent on your
1805 config XIP_DEFLATED_DATA
1806 bool "Store kernel .data section compressed in ROM"
1807 depends on XIP_KERNEL
1810 Before the kernel is actually executed, its .data section has to be
1811 copied to RAM from ROM. This option allows for storing that data
1812 in compressed form and decompressed to RAM rather than merely being
1813 copied, saving some precious ROM space. A possible drawback is a
1814 slightly longer boot delay.
1817 bool "Kexec system call (EXPERIMENTAL)"
1818 depends on (!SMP || PM_SLEEP_SMP)
1822 kexec is a system call that implements the ability to shutdown your
1823 current kernel, and to start another kernel. It is like a reboot
1824 but it is independent of the system firmware. And like a reboot
1825 you can start any kernel with it, not just Linux.
1827 It is an ongoing process to be certain the hardware in a machine
1828 is properly shutdown, so do not be surprised if this code does not
1829 initially work for you.
1832 bool "Export atags in procfs"
1833 depends on ATAGS && KEXEC
1836 Should the atags used to boot the kernel be exported in an "atags"
1837 file in procfs. Useful with kexec.
1840 bool "Build kdump crash kernel (EXPERIMENTAL)"
1842 Generate crash dump after being started by kexec. This should
1843 be normally only set in special crash dump kernels which are
1844 loaded in the main kernel with kexec-tools into a specially
1845 reserved region and then later executed after a crash by
1846 kdump/kexec. The crash dump kernel must be compiled to a
1847 memory address not used by the main kernel
1849 For more details see Documentation/admin-guide/kdump/kdump.rst
1851 config AUTO_ZRELADDR
1852 bool "Auto calculation of the decompressed kernel image address"
1854 ZRELADDR is the physical address where the decompressed kernel
1855 image will be placed. If AUTO_ZRELADDR is selected, the address
1856 will be determined at run-time, either by masking the current IP
1857 with 0xf8000000, or, if invalid, from the DTB passed in r2.
1858 This assumes the zImage being placed in the first 128MB from
1865 bool "UEFI runtime support"
1866 depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
1868 select EFI_PARAMS_FROM_FDT
1870 select EFI_GENERIC_STUB
1871 select EFI_RUNTIME_WRAPPERS
1873 This option provides support for runtime services provided
1874 by UEFI firmware (such as non-volatile variables, realtime
1875 clock, and platform reset). A UEFI stub is also provided to
1876 allow the kernel to be booted as an EFI application. This
1877 is only useful for kernels that may run on systems that have
1881 bool "Enable support for SMBIOS (DMI) tables"
1885 This enables SMBIOS/DMI feature for systems.
1887 This option is only useful on systems that have UEFI firmware.
1888 However, even with this option, the resultant kernel should
1889 continue to boot on existing non-UEFI platforms.
1891 NOTE: This does *NOT* enable or encourage the use of DMI quirks,
1892 i.e., the the practice of identifying the platform via DMI to
1893 decide whether certain workarounds for buggy hardware and/or
1894 firmware need to be enabled. This would require the DMI subsystem
1895 to be enabled much earlier than we do on ARM, which is non-trivial.
1899 menu "CPU Power Management"
1901 source "drivers/cpufreq/Kconfig"
1903 source "drivers/cpuidle/Kconfig"
1907 menu "Floating point emulation"
1909 comment "At least one emulation must be selected"
1912 bool "NWFPE math emulation"
1913 depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
1915 Say Y to include the NWFPE floating point emulator in the kernel.
1916 This is necessary to run most binaries. Linux does not currently
1917 support floating point hardware so you need to say Y here even if
1918 your machine has an FPA or floating point co-processor podule.
1920 You may say N here if you are going to load the Acorn FPEmulator
1921 early in the bootup.
1924 bool "Support extended precision"
1925 depends on FPE_NWFPE
1927 Say Y to include 80-bit support in the kernel floating-point
1928 emulator. Otherwise, only 32 and 64-bit support is compiled in.
1929 Note that gcc does not generate 80-bit operations by default,
1930 so in most cases this option only enlarges the size of the
1931 floating point emulator without any good reason.
1933 You almost surely want to say N here.
1936 bool "FastFPE math emulation (EXPERIMENTAL)"
1937 depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
1939 Say Y here to include the FAST floating point emulator in the kernel.
1940 This is an experimental much faster emulator which now also has full
1941 precision for the mantissa. It does not support any exceptions.
1942 It is very simple, and approximately 3-6 times faster than NWFPE.
1944 It should be sufficient for most programs. It may be not suitable
1945 for scientific calculations, but you have to check this for yourself.
1946 If you do not feel you need a faster FP emulation you should better
1950 bool "VFP-format floating point maths"
1951 depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
1953 Say Y to include VFP support code in the kernel. This is needed
1954 if your hardware includes a VFP unit.
1956 Please see <file:Documentation/arm/vfp/release-notes.rst> for
1957 release notes and additional status information.
1959 Say N if your target does not have VFP hardware.
1967 bool "Advanced SIMD (NEON) Extension support"
1968 depends on VFPv3 && CPU_V7
1970 Say Y to include support code for NEON, the ARMv7 Advanced SIMD
1973 config KERNEL_MODE_NEON
1974 bool "Support for NEON in kernel mode"
1975 depends on NEON && AEABI
1977 Say Y to include support for NEON in kernel mode.
1981 menu "Power management options"
1983 source "kernel/power/Kconfig"
1985 config ARCH_SUSPEND_POSSIBLE
1986 depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
1987 CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
1990 config ARM_CPU_SUSPEND
1991 def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
1992 depends on ARCH_SUSPEND_POSSIBLE
1994 config ARCH_HIBERNATION_POSSIBLE
1997 default y if ARCH_SUSPEND_POSSIBLE
2002 source "arch/arm/crypto/Kconfig"
2005 source "arch/arm/Kconfig.assembler"