# SPDX-License-Identifier: GPL-2.0
config ARM
bool
default y
select ARCH_32BIT_OFF_T
select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE if HAVE_KRETPROBES && FRAME_POINTER && !ARM_UNWIND
select ARCH_HAS_BINFMT_FLAT
select ARCH_HAS_CPU_FINALIZE_INIT if MMU
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL if MMU
select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_KEEPINITRD
select ARCH_HAS_KCOV
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SET_MEMORY
select ARCH_STACKWALK
select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
select ARCH_HAS_STRICT_MODULE_RWX if MMU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_KEEP_MEMBLOCK
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_USE_MEMTEST
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
select ARCH_WANT_GENERAL_HUGETLB
select ARCH_WANT_IPC_PARSE_VERSION
select ARCH_WANT_LD_ORPHAN_WARN
select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
select BUILDTIME_TABLE_SORT if MMU
select COMMON_CLK if !(ARCH_RPC || ARCH_FOOTBRIDGE)
select CLONE_BACKWARDS
select CPU_PM if SUSPEND || CPU_IDLE
select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
select DMA_DECLARE_COHERENT
select DMA_GLOBAL_POOL if !MMU
select DMA_OPS
select DMA_NONCOHERENT_MMAP if MMU
select EDAC_SUPPORT
select EDAC_ATOMIC_SCRUB
select GENERIC_ALLOCATOR
select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_IRQ_IPI if SMP
select GENERIC_CPU_AUTOPROBE
select GENERIC_EARLY_IOREMAP
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_MULTI_HANDLER
select GENERIC_IRQ_PROBE
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_LIB_DEVMEM_IS_ALLOWED
select GENERIC_PCI_IOMAP
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select HARDIRQS_SW_RESEND
select HAS_IOPORT
select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_PFN_VALID
select HAVE_ARCH_SECCOMP
select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
select HAVE_ARM_SMCCC if CPU_V7
select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
select HAVE_CONTEXT_TRACKING_USER
select HAVE_C_RECORDMCOUNT
select HAVE_BUILDTIME_MCOUNT_SORT
select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
select HAVE_DMA_CONTIGUOUS if MMU
select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
select HAVE_EXIT_THREAD
select HAVE_FAST_GUP if ARM_LPAE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER if !XIP_KERNEL
select HAVE_GCC_PLUGINS
select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZ4
select HAVE_KERNEL_LZMA
select HAVE_KERNEL_LZO
select HAVE_KERNEL_XZ
select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
select HAVE_KRETPROBES if HAVE_KPROBES
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_NMI
select HAVE_OPTPROBES if !THUMB2_KERNEL
select HAVE_PCI if MMU
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RSEQ
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UID16
select HAVE_VIRT_CPU_ACCOUNTING_GEN
select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
select IRQ_FORCED_THREADING
select LOCK_MM_AND_FIND_VMA
select MODULES_USE_ELF_REL
select NEED_DMA_MAP_STATE
select OF_EARLY_FLATTREE if OF
select OLD_SIGACTION
select OLD_SIGSUSPEND3
select PCI_DOMAINS_GENERIC if PCI
select PCI_SYSCALL if PCI
select PERF_USE_VMALLOC
select RTC_LIB
select SPARSE_IRQ if !(ARCH_FOOTBRIDGE || ARCH_RPC)
select SYS_SUPPORTS_APM_EMULATION
select THREAD_INFO_IN_TASK
select TIMER_OF if OF
select HAVE_ARCH_VMAP_STACK if MMU && ARM_HAS_GROUP_RELOCS
select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
select USE_OF if !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
# Above selects are sorted alphabetically; please add new ones
# according to that. Thanks.
help
The ARM series is a line of low-power-consumption RISC chip designs
licensed by ARM Ltd and targeted at embedded applications and
handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
manufactured, but legacy ARM-based PC hardware remains popular in
Europe. There is an ARM Linux project with a web page at
<http://www.arm.linux.org.uk/>.
config ARM_HAS_GROUP_RELOCS
def_bool y
depends on !LD_IS_LLD || LLD_VERSION >= 140000
depends on !COMPILE_TEST
help
Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
relocations, which have been around for a long time, but were not
supported in LLD until version 14. The combined range is -/+ 256 MiB,
which is usually sufficient, but not for allyesconfig, so we disable
this feature when doing compile testing.
config ARM_DMA_USE_IOMMU
bool
select NEED_SG_DMA_LENGTH
if ARM_DMA_USE_IOMMU
config ARM_DMA_IOMMU_ALIGNMENT
int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
range 4 9
default 8
help
DMA mapping framework by default aligns all buffers to the smallest
PAGE_SIZE order which is greater than or equal to the requested buffer
size. This works well for buffers up to a few hundreds kilobytes, but
for larger buffers it just a waste of address space. Drivers which has
relatively small addressing window (like 64Mib) might run out of
virtual space with just a few allocations.
With this parameter you can specify the maximum PAGE_SIZE order for
DMA IOMMU buffers. Larger buffers will be aligned only to this
specified order. The order is expressed as a power of two multiplied
by the PAGE_SIZE.
endif
config SYS_SUPPORTS_APM_EMULATION
bool
config HAVE_TCM
bool
select GENERIC_ALLOCATOR
config HAVE_PROC_CPU
bool
config NO_IOPORT_MAP
bool
config SBUS
bool
config STACKTRACE_SUPPORT
bool
default y
config LOCKDEP_SUPPORT
bool
default y
config ARCH_HAS_ILOG2_U32
bool
config ARCH_HAS_ILOG2_U64
bool
config ARCH_HAS_BANDGAP
bool
config FIX_EARLYCON_MEM
def_bool y if MMU
config GENERIC_HWEIGHT
bool
default y
config GENERIC_CALIBRATE_DELAY
bool
default y
config ARCH_MAY_HAVE_PC_FDC
bool
config ARCH_SUPPORTS_UPROBES
def_bool y
config GENERIC_ISA_DMA
bool
config FIQ
bool
config ARCH_MTD_XIP
bool
config ARM_PATCH_PHYS_VIRT
bool "Patch physical to virtual translations at runtime" if !ARCH_MULTIPLATFORM
default y
depends on MMU
help
Patch phys-to-virt and virt-to-phys translation functions at
boot and module load time according to the position of the
kernel in system memory.
This can only be used with non-XIP MMU kernels where the base
of physical memory is at a 2 MiB boundary.
Only disable this option if you know that you do not require
this feature (eg, building a kernel for a single machine) and
you need to shrink the kernel to the minimal size.
config NEED_MACH_IO_H
bool
help
Select this when mach/io.h is required to provide special
definitions for this platform. The need for mach/io.h should
be avoided when possible.
config NEED_MACH_MEMORY_H
bool
help
Select this when mach/memory.h is required to provide special
definitions for this platform. The need for mach/memory.h should
be avoided when possible.
config PHYS_OFFSET
hex "Physical address of main memory" if MMU
depends on !ARM_PATCH_PHYS_VIRT || !AUTO_ZRELADDR
default DRAM_BASE if !MMU
default 0x00000000 if ARCH_FOOTBRIDGE
default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
default 0xa0000000 if ARCH_PXA
default 0xc0000000 if ARCH_EP93XX || ARCH_SA1100
default 0
help
Please provide the physical address corresponding to the
location of main memory in your system.
config GENERIC_BUG
def_bool y
depends on BUG
config PGTABLE_LEVELS
int
default 3 if ARM_LPAE
default 2
menu "System Type"
config MMU
bool "MMU-based Paged Memory Management Support"
default y
help
Select if you want MMU-based virtualised addressing space
support by paged memory management. If unsure, say 'Y'.
config ARM_SINGLE_ARMV7M
def_bool !MMU
select ARM_NVIC
select CPU_V7M
select NO_IOPORT_MAP
config ARCH_MMAP_RND_BITS_MIN
default 8
config ARCH_MMAP_RND_BITS_MAX
default 14 if PAGE_OFFSET=0x40000000
default 15 if PAGE_OFFSET=0x80000000
default 16
config ARCH_MULTIPLATFORM
bool "Require kernel to be portable to multiple machines" if EXPERT
depends on MMU && !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
default y
help
In general, all Arm machines can be supported in a single
kernel image, covering either Armv4/v5 or Armv6/v7.
However, some configuration options require hardcoding machine
specific physical addresses or enable errata workarounds that may
break other machines.
Selecting N here allows using those options, including
DEBUG_UNCOMPRESS, XIP_KERNEL and ZBOOT_ROM. If unsure, say Y.
menu "Platform selection"
depends on MMU
comment "CPU Core family selection"
config ARCH_MULTI_V4
bool "ARMv4 based platforms (FA526, StrongARM)"
depends on !ARCH_MULTI_V6_V7
# https://github.com/llvm/llvm-project/issues/50764
depends on !LD_IS_LLD || LLD_VERSION >= 160000
select ARCH_MULTI_V4_V5
select CPU_FA526 if !(CPU_SA110 || CPU_SA1100)
config ARCH_MULTI_V4T
bool "ARMv4T based platforms (ARM720T, ARM920T, ...)"
depends on !ARCH_MULTI_V6_V7
# https://github.com/llvm/llvm-project/issues/50764
depends on !LD_IS_LLD || LLD_VERSION >= 160000
select ARCH_MULTI_V4_V5
select CPU_ARM920T if !(CPU_ARM7TDMI || CPU_ARM720T || \
CPU_ARM740T || CPU_ARM9TDMI || CPU_ARM922T || \
CPU_ARM925T || CPU_ARM940T)
config ARCH_MULTI_V5
bool "ARMv5 based platforms (ARM926T, XSCALE, PJ1, ...)"
depends on !ARCH_MULTI_V6_V7
select ARCH_MULTI_V4_V5
select CPU_ARM926T if !(CPU_ARM946E || CPU_ARM1020 || \
CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || \
CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_FEROCEON)
config ARCH_MULTI_V4_V5
bool
config ARCH_MULTI_V6
bool "ARMv6 based platforms (ARM11)"
select ARCH_MULTI_V6_V7
select CPU_V6K
config ARCH_MULTI_V7
bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)"
default y
select ARCH_MULTI_V6_V7
select CPU_V7
select HAVE_SMP
config ARCH_MULTI_V6_V7
bool
select MIGHT_HAVE_CACHE_L2X0
config ARCH_MULTI_CPU_AUTO
def_bool !(ARCH_MULTI_V4 || ARCH_MULTI_V4T || ARCH_MULTI_V6_V7)
select ARCH_MULTI_V5
endmenu
config ARCH_VIRT
bool "Dummy Virtual Machine"
depends on ARCH_MULTI_V7
select ARM_AMBA
select ARM_GIC
select ARM_GIC_V2M if PCI
select ARM_GIC_V3
select ARM_GIC_V3_ITS if PCI
select ARM_PSCI
select HAVE_ARM_ARCH_TIMER
config ARCH_AIROHA
bool "Airoha SoC Support"
depends on ARCH_MULTI_V7
select ARM_AMBA
select ARM_GIC
select ARM_GIC_V3
select ARM_PSCI
select HAVE_ARM_ARCH_TIMER
help
Support for Airoha EN7523 SoCs
#
# This is sorted alphabetically by mach-* pathname. However, plat-*
# Kconfigs may be included either alphabetically (according to the
# plat- suffix) or along side the corresponding mach-* source.
#
source "arch/arm/mach-actions/Kconfig"
source "arch/arm/mach-alpine/Kconfig"
source "arch/arm/mach-artpec/Kconfig"
source "arch/arm/mach-asm9260/Kconfig"
source "arch/arm/mach-aspeed/Kconfig"
source "arch/arm/mach-at91/Kconfig"
source "arch/arm/mach-axxia/Kconfig"
source "arch/arm/mach-bcm/Kconfig"
source "arch/arm/mach-berlin/Kconfig"
source "arch/arm/mach-clps711x/Kconfig"
source "arch/arm/mach-davinci/Kconfig"
source "arch/arm/mach-digicolor/Kconfig"
source "arch/arm/mach-dove/Kconfig"
source "arch/arm/mach-ep93xx/Kconfig"
source "arch/arm/mach-exynos/Kconfig"
source "arch/arm/mach-footbridge/Kconfig"
source "arch/arm/mach-gemini/Kconfig"
source "arch/arm/mach-highbank/Kconfig"
source "arch/arm/mach-hisi/Kconfig"
source "arch/arm/mach-hpe/Kconfig"
source "arch/arm/mach-imx/Kconfig"
source "arch/arm/mach-ixp4xx/Kconfig"
source "arch/arm/mach-keystone/Kconfig"
source "arch/arm/mach-lpc32xx/Kconfig"
source "arch/arm/mach-mediatek/Kconfig"
source "arch/arm/mach-meson/Kconfig"
source "arch/arm/mach-milbeaut/Kconfig"
source "arch/arm/mach-mmp/Kconfig"
source "arch/arm/mach-moxart/Kconfig"
source "arch/arm/mach-mstar/Kconfig"
source "arch/arm/mach-mv78xx0/Kconfig"
source "arch/arm/mach-mvebu/Kconfig"
source "arch/arm/mach-mxs/Kconfig"
source "arch/arm/mach-nomadik/Kconfig"
source "arch/arm/mach-npcm/Kconfig"
source "arch/arm/mach-nspire/Kconfig"
source "arch/arm/mach-omap1/Kconfig"
source "arch/arm/mach-omap2/Kconfig"
source "arch/arm/mach-orion5x/Kconfig"
source "arch/arm/mach-pxa/Kconfig"
source "arch/arm/mach-qcom/Kconfig"
source "arch/arm/mach-rda/Kconfig"
source "arch/arm/mach-realtek/Kconfig"
source "arch/arm/mach-rpc/Kconfig"
source "arch/arm/mach-rockchip/Kconfig"
source "arch/arm/mach-s3c/Kconfig"
source "arch/arm/mach-s5pv210/Kconfig"
source "arch/arm/mach-sa1100/Kconfig"
source "arch/arm/mach-shmobile/Kconfig"
source "arch/arm/mach-socfpga/Kconfig"
source "arch/arm/mach-spear/Kconfig"
source "arch/arm/mach-sti/Kconfig"
source "arch/arm/mach-stm32/Kconfig"
source "arch/arm/mach-sunplus/Kconfig"
source "arch/arm/mach-sunxi/Kconfig"
source "arch/arm/mach-tegra/Kconfig"
source "arch/arm/mach-uniphier/Kconfig"
source "arch/arm/mach-ux500/Kconfig"
source "arch/arm/mach-versatile/Kconfig"
source "arch/arm/mach-vt8500/Kconfig"
source "arch/arm/mach-zynq/Kconfig"
# ARMv7-M architecture
config ARCH_LPC18XX
bool "NXP LPC18xx/LPC43xx"
depends on ARM_SINGLE_ARMV7M
select ARCH_HAS_RESET_CONTROLLER
select ARM_AMBA
select CLKSRC_LPC32XX
select PINCTRL
help
Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
high performance microcontrollers.
config ARCH_MPS2
bool "ARM MPS2 platform"
depends on ARM_SINGLE_ARMV7M
select ARM_AMBA
select CLKSRC_MPS2
help
Support for Cortex-M Prototyping System (or V2M-MPS2) which comes
with a range of available cores like Cortex-M3/M4/M7.
Please, note that depends which Application Note is used memory map
for the platform may vary, so adjustment of RAM base might be needed.
# Definitions to make life easier
config ARCH_ACORN
bool
config PLAT_ORION
bool
select CLKSRC_MMIO
select GENERIC_IRQ_CHIP
select IRQ_DOMAIN
config PLAT_ORION_LEGACY
bool
select PLAT_ORION
config PLAT_VERSATILE
bool
source "arch/arm/mm/Kconfig"
config IWMMXT
bool "Enable iWMMXt support"
depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B
help
Enable support for iWMMXt context switching at run time if
running on a CPU that supports it.
if !MMU
source "arch/arm/Kconfig-nommu"
endif
config PJ4B_ERRATA_4742
bool "PJ4B Errata 4742: IDLE Wake Up Commands can Cause the CPU Core to Cease Operation"
depends on CPU_PJ4B && MACH_ARMADA_370
default y
help
When coming out of either a Wait for Interrupt (WFI) or a Wait for
Event (WFE) IDLE states, a specific timing sensitivity exists between
the retiring WFI/WFE instructions and the newly issued subsequent
instructions. This sensitivity can result in a CPU hang scenario.
Workaround:
The software must insert either a Data Synchronization Barrier (DSB)
or Data Memory Barrier (DMB) command immediately after the WFI/WFE
instruction
config ARM_ERRATA_326103
bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
depends on CPU_V6
help
Executing a SWP instruction to read-only memory does not set bit 11
of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
treat the access as a read, preventing a COW from occurring and
causing the faulting task to livelock.
config ARM_ERRATA_411920
bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
depends on CPU_V6 || CPU_V6K
help
Invalidation of the Instruction Cache operation can
fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.
It does not affect the MPCore. This option enables the ARM Ltd.
recommended workaround.
config ARM_ERRATA_430973
bool "ARM errata: Stale prediction on replaced interworking branch"
depends on CPU_V7
help
This option enables the workaround for the 430973 Cortex-A8
r1p* erratum. If a code sequence containing an ARM/Thumb
interworking branch is replaced with another code sequence at the
same virtual address, whether due to self-modifying code or virtual
to physical address re-mapping, Cortex-A8 does not recover from the
stale interworking branch prediction. This results in Cortex-A8
executing the new code sequence in the incorrect ARM or Thumb state.
The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
and also flushes the branch target cache at every context switch.
Note that setting specific bits in the ACTLR register may not be
available in non-secure mode.
config ARM_ERRATA_458693
bool "ARM errata: Processor deadlock when a false hazard is created"
depends on CPU_V7
depends on !ARCH_MULTIPLATFORM
help
This option enables the workaround for the 458693 Cortex-A8 (r2p0)
erratum. For very specific sequences of memory operations, it is
possible for a hazard condition intended for a cache line to instead
be incorrectly associated with a different cache line. This false
hazard might then cause a processor deadlock. The workaround enables
the L1 caching of the NEON accesses and disables the PLD instruction
in the ACTLR register. Note that setting specific bits in the ACTLR
register may not be available in non-secure mode and thus is not
available on a multiplatform kernel. This should be applied by the
bootloader instead.
config ARM_ERRATA_460075
bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
depends on CPU_V7
depends on !ARCH_MULTIPLATFORM
help
This option enables the workaround for the 460075 Cortex-A8 (r2p0)
erratum. Any asynchronous access to the L2 cache may encounter a
situation in which recent store transactions to the L2 cache are lost
and overwritten with stale memory contents from external memory. The
workaround disables the write-allocate mode for the L2 cache via the
ACTLR register. Note that setting specific bits in the ACTLR register
may not be available in non-secure mode and thus is not available on
a multiplatform kernel. This should be applied by the bootloader
instead.
config ARM_ERRATA_742230
bool "ARM errata: DMB operation may be faulty"
depends on CPU_V7 && SMP
depends on !ARCH_MULTIPLATFORM
help
This option enables the workaround for the 742230 Cortex-A9
(r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
between two write operations may not ensure the correct visibility
ordering of the two writes. This workaround sets a specific bit in
the diagnostic register of the Cortex-A9 which causes the DMB
instruction to behave as a DSB, ensuring the correct behaviour of
the two writes. Note that setting specific bits in the diagnostics
register may not be available in non-secure mode and thus is not
available on a multiplatform kernel. This should be applied by the
bootloader instead.
config ARM_ERRATA_742231
bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
depends on CPU_V7 && SMP
depends on !ARCH_MULTIPLATFORM
help
This option enables the workaround for the 742231 Cortex-A9
(r2p0..r2p2) erratum. Under certain conditions, specific to the
Cortex-A9 MPCore micro-architecture, two CPUs working in SMP mode,
accessing some data located in the same cache line, may get corrupted
data due to bad handling of the address hazard when the line gets
replaced from one of the CPUs at the same time as another CPU is
accessing it. This workaround sets specific bits in the diagnostic
register of the Cortex-A9 which reduces the linefill issuing
capabilities of the processor. Note that setting specific bits in the
diagnostics register may not be available in non-secure mode and thus
is not available on a multiplatform kernel. This should be applied by
the bootloader instead.
config ARM_ERRATA_643719
bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
depends on CPU_V7 && SMP
default y
help
This option enables the workaround for the 643719 Cortex-A9 (prior to
r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
register returns zero when it should return one. The workaround
corrects this value, ensuring cache maintenance operations which use
it behave as intended and avoiding data corruption.
config ARM_ERRATA_720789
bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
depends on CPU_V7
help
This option enables the workaround for the 720789 Cortex-A9 (prior to
r2p0) erratum. A faulty ASID can be sent to the other CPUs for the
broadcasted CP15 TLB maintenance operations TLBIASIDIS and TLBIMVAIS.
As a consequence of this erratum, some TLB entries which should be
invalidated are not, resulting in an incoherency in the system page
tables. The workaround changes the TLB flushing routines to invalidate
entries regardless of the ASID.
config ARM_ERRATA_743622
bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
depends on CPU_V7
depends on !ARCH_MULTIPLATFORM
help
This option enables the workaround for the 743622 Cortex-A9
(r2p*) erratum. Under very rare conditions, a faulty
optimisation in the Cortex-A9 Store Buffer may lead to data
corruption. This workaround sets a specific bit in the diagnostic
register of the Cortex-A9 which disables the Store Buffer
optimisation, preventing the defect from occurring. This has no
visible impact on the overall performance or power consumption of the
processor. Note that setting specific bits in the diagnostics register
may not be available in non-secure mode and thus is not available on a
multiplatform kernel. This should be applied by the bootloader instead.
config ARM_ERRATA_751472
bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
depends on CPU_V7
depends on !ARCH_MULTIPLATFORM
help
This option enables the workaround for the 751472 Cortex-A9 (prior
to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
completion of a following broadcasted operation if the second
operation is received by a CPU before the ICIALLUIS has completed,
potentially leading to corrupted entries in the cache or TLB.
Note that setting specific bits in the diagnostics register may
not be available in non-secure mode and thus is not available on
a multiplatform kernel. This should be applied by the bootloader
instead.
config ARM_ERRATA_754322
bool "ARM errata: possible faulty MMU translations following an ASID switch"
depends on CPU_V7
help
This option enables the workaround for the 754322 Cortex-A9 (r2p*,
r3p*) erratum. A speculative memory access may cause a page table walk
which starts prior to an ASID switch but completes afterwards. This
can populate the micro-TLB with a stale entry which may be hit with
the new ASID. This workaround places two dsb instructions in the mm
switching code so that no page table walks can cross the ASID switch.
config ARM_ERRATA_754327
bool "ARM errata: no automatic Store Buffer drain"
depends on CPU_V7 && SMP
help
This option enables the workaround for the 754327 Cortex-A9 (prior to
r2p0) erratum. The Store Buffer does not have any automatic draining
mechanism and therefore a livelock may occur if an external agent
continuously polls a memory location waiting to observe an update.
This workaround defines cpu_relax() as smp_mb(), preventing correctly
written polling loops from denying visibility of updates to memory.
config ARM_ERRATA_364296
bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
depends on CPU_V6
help
This options enables the workaround for the 364296 ARM1136
r0p2 erratum (possible cache data corruption with
hit-under-miss enabled). It sets the undocumented bit 31 in
the auxiliary control register and the FI bit in the control
register, thus disabling hit-under-miss without putting the
processor into full low interrupt latency mode. ARM11MPCore
is not affected.
config ARM_ERRATA_764369
bool "ARM errata: Data cache line maintenance operation by MVA may not succeed"
depends on CPU_V7 && SMP
help
This option enables the workaround for erratum 764369
affecting Cortex-A9 MPCore with two or more processors (all
current revisions). Under certain timing circumstances, a data
cache line maintenance operation by MVA targeting an Inner
Shareable memory region may fail to proceed up to either the
Point of Coherency or to the Point of Unification of the
system. This workaround adds a DSB instruction before the
relevant cache maintenance functions and sets a specific bit
in the diagnostic control register of the SCU.
config ARM_ERRATA_764319
bool "ARM errata: Read to DBGPRSR and DBGOSLSR may generate Undefined instruction"
depends on CPU_V7
help
This option enables the workaround for the 764319 Cortex A-9 erratum.
CP14 read accesses to the DBGPRSR and DBGOSLSR registers generate an
unexpected Undefined Instruction exception when the DBGSWENABLE
external pin is set to 0, even when the CP14 accesses are performed
from a privileged mode. This work around catches the exception in a
way the kernel does not stop execution.
config ARM_ERRATA_775420
bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
depends on CPU_V7
help
This option enables the workaround for the 775420 Cortex-A9 (r2p2,
r2p6,r2p8,r2p10,r3p0) erratum. In case a data cache maintenance
operation aborts with MMU exception, it might cause the processor
to deadlock. This workaround puts DSB before executing ISB if
an abort may occur on cache maintenance.
config ARM_ERRATA_798181
bool "ARM errata: TLBI/DSB failure on Cortex-A15"
depends on CPU_V7 && SMP
help
On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
adequately shooting down all use of the old entries. This
option enables the Linux kernel workaround for this erratum
which sends an IPI to the CPUs that are running the same ASID
as the one being invalidated.
config ARM_ERRATA_773022
bool "ARM errata: incorrect instructions may be executed from loop buffer"
depends on CPU_V7
help
This option enables the workaround for the 773022 Cortex-A15
(up to r0p4) erratum. In certain rare sequences of code, the
loop buffer may deliver incorrect instructions. This
workaround disables the loop buffer to avoid the erratum.
config ARM_ERRATA_818325_852422
bool "ARM errata: A12: some seqs of opposed cond code instrs => deadlock or corruption"
depends on CPU_V7
help
This option enables the workaround for:
- Cortex-A12 818325: Execution of an UNPREDICTABLE STR or STM
instruction might deadlock. Fixed in r0p1.
- Cortex-A12 852422: Execution of a sequence of instructions might
lead to either a data corruption or a CPU deadlock. Not fixed in
any Cortex-A12 cores yet.
This workaround for all both errata involves setting bit[12] of the
Feature Register. This bit disables an optimisation applied to a
sequence of 2 instructions that use opposing condition codes.
config ARM_ERRATA_821420
bool "ARM errata: A12: sequence of VMOV to core registers might lead to a dead lock"
depends on CPU_V7
help
This option enables the workaround for the 821420 Cortex-A12
(all revs) erratum. In very rare timing conditions, a sequence
of VMOV to Core registers instructions, for which the second
one is in the shadow of a branch or abort, can lead to a
deadlock when the VMOV instructions are issued out-of-order.
config ARM_ERRATA_825619
bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
depends on CPU_V7
help
This option enables the workaround for the 825619 Cortex-A12
(all revs) erratum. Within rare timing constraints, executing a
DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
and Device/Strongly-Ordered loads and stores might cause deadlock
config ARM_ERRATA_857271
bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
depends on CPU_V7
help
This option enables the workaround for the 857271 Cortex-A12
(all revs) erratum. Under very rare timing conditions, the CPU might
hang. The workaround is expected to have a < 1% performance impact.
config ARM_ERRATA_852421
bool "ARM errata: A17: DMB ST might fail to create order between stores"
depends on CPU_V7
help
This option enables the workaround for the 852421 Cortex-A17
(r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
execution of a DMB ST instruction might fail to properly order
stores from GroupA and stores from GroupB.
config ARM_ERRATA_852423
bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
depends on CPU_V7
help
This option enables the workaround for:
- Cortex-A17 852423: Execution of a sequence of instructions might
lead to either a data corruption or a CPU deadlock. Not fixed in
any Cortex-A17 cores yet.
This is identical to Cortex-A12 erratum 852422. It is a separate
config option from the A12 erratum due to the way errata are checked
for and handled.
config ARM_ERRATA_857272
bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
depends on CPU_V7
help
This option enables the workaround for the 857272 Cortex-A17 erratum.
This erratum is not known to be fixed in any A17 revision.
This is identical to Cortex-A12 erratum 857271. It is a separate
config option from the A12 erratum due to the way errata are checked
for and handled.
endmenu
source "arch/arm/common/Kconfig"
menu "Bus support"
config ISA
bool
help
Find out whether you have ISA slots on your motherboard. ISA is the
name of a bus system, i.e. the way the CPU talks to the other stuff
inside your box. Other bus systems are PCI, EISA, MicroChannel
(MCA) or VESA. ISA is an older system, now being displaced by PCI;
newer boards don't support it. If you have ISA, say Y, otherwise N.
# Select ISA DMA interface
config ISA_DMA_API
bool
config ARM_ERRATA_814220
bool "ARM errata: Cache maintenance by set/way operations can execute out of order"
depends on CPU_V7
help
The v7 ARM states that all cache and branch predictor maintenance
operations that do not specify an address execute, relative to
each other, in program order.
However, because of this erratum, an L2 set/way cache maintenance
operation can overtake an L1 set/way cache maintenance operation.
This ERRATA only affected the Cortex-A7 and present in r0p2, r0p3,
r0p4, r0p5.
endmenu
menu "Kernel Features"
config HAVE_SMP
bool
help
This option should be selected by machines which have an SMP-
capable CPU.
The only effect of this option is to make the SMP-related
options available to the user for configuration.
config SMP
bool "Symmetric Multi-Processing"
depends on CPU_V6K || CPU_V7
depends on HAVE_SMP
depends on MMU || ARM_MPU
select IRQ_WORK
help
This enables support for systems with more than one CPU. If you have
a system with only one CPU, say N. If you have a system with more
than one CPU, say Y.
If you say N here, the kernel will run on uni- and multiprocessor
machines, but will use only one CPU of a multiprocessor machine. If
you say Y here, the kernel will run on many, but not all,
uniprocessor machines. On a uniprocessor machine, the kernel
will run faster if you say N here.
See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
<file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
<http://tldp.org/HOWTO/SMP-HOWTO.html>.
If you don't know what to do here, say N.
config SMP_ON_UP
bool "Allow booting SMP kernel on uniprocessor systems"
depends on SMP && MMU
default y
help
SMP kernels contain instructions which fail on non-SMP processors.
Enabling this option allows the kernel to modify itself to make
these instructions safe. Disabling it allows about 1K of space
savings.
If you don't know what to do here, say Y.
config CURRENT_POINTER_IN_TPIDRURO
def_bool y
depends on CPU_32v6K && !CPU_V6
config IRQSTACKS
def_bool y
select HAVE_IRQ_EXIT_ON_IRQ_STACK
select HAVE_SOFTIRQ_ON_OWN_STACK
config ARM_CPU_TOPOLOGY
bool "Support cpu topology definition"
depends on SMP && CPU_V7
default y
help
Support ARM cpu topology definition. The MPIDR register defines
affinity between processors which is then used to describe the cpu
topology of an ARM System.
config SCHED_MC
bool "Multi-core scheduler support"
depends on ARM_CPU_TOPOLOGY
help
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
increased overhead in some places. If unsure say N here.
config SCHED_SMT
bool "SMT scheduler support"
depends on ARM_CPU_TOPOLOGY
help
Improves the CPU scheduler's decision making when dealing with
MultiThreading at a cost of slightly increased overhead in some
places. If unsure say N here.
config HAVE_ARM_SCU
bool
help
This option enables support for the ARM snoop control unit
config HAVE_ARM_ARCH_TIMER
bool "Architected timer support"
depends on CPU_V7
select ARM_ARCH_TIMER
help
This option enables support for the ARM architected timer
config HAVE_ARM_TWD
bool
help
This options enables support for the ARM timer and watchdog unit
config MCPM
bool "Multi-Cluster Power Management"
depends on CPU_V7 && SMP
help
This option provides the common power management infrastructure
for (multi-)cluster based systems, such as big.LITTLE based
systems.
config MCPM_QUAD_CLUSTER
bool
depends on MCPM
help
To avoid wasting resources unnecessarily, MCPM only supports up
to 2 clusters by default.
Platforms with 3 or 4 clusters that use MCPM must select this
option to allow the additional clusters to be managed.
config BIG_LITTLE
bool "big.LITTLE support (Experimental)"
depends on CPU_V7 && SMP
select MCPM
help
This option enables support selections for the big.LITTLE
system architecture.
config BL_SWITCHER
bool "big.LITTLE switcher support"
depends on BIG_LITTLE && MCPM && HOTPLUG_CPU && ARM_GIC
select CPU_PM
help
The big.LITTLE "switcher" provides the core functionality to
transparently handle transition between a cluster of A15's
and a cluster of A7's in a big.LITTLE system.
config BL_SWITCHER_DUMMY_IF
tristate "Simple big.LITTLE switcher user interface"
depends on BL_SWITCHER && DEBUG_KERNEL
help
This is a simple and dummy char dev interface to control
the big.LITTLE switcher core code. It is meant for
debugging purposes only.
choice
prompt "Memory split"
depends on MMU
default VMSPLIT_3G
help
Select the desired split between kernel and user memory.
If you are not absolutely sure what you are doing, leave this
option alone!
config VMSPLIT_3G
bool "3G/1G user/kernel split"
config VMSPLIT_3G_OPT
depends on !ARM_LPAE
bool "3G/1G user/kernel split (for full 1G low memory)"
config VMSPLIT_2G
bool "2G/2G user/kernel split"
config VMSPLIT_1G
bool "1G/3G user/kernel split"
endchoice
config PAGE_OFFSET
hex
default PHYS_OFFSET if !MMU
default 0x40000000 if VMSPLIT_1G
default 0x80000000 if VMSPLIT_2G
default 0xB0000000 if VMSPLIT_3G_OPT
default 0xC0000000
config KASAN_SHADOW_OFFSET
hex
depends on KASAN
default 0x1f000000 if PAGE_OFFSET=0x40000000
default 0x5f000000 if PAGE_OFFSET=0x80000000
default 0x9f000000 if PAGE_OFFSET=0xC0000000
default 0x8f000000 if PAGE_OFFSET=0xB0000000
default 0xffffffff
config NR_CPUS
int "Maximum number of CPUs (2-32)"
range 2 16 if DEBUG_KMAP_LOCAL
range 2 32 if !DEBUG_KMAP_LOCAL
depends on SMP
default "4"
help
The maximum number of CPUs that the kernel can support.
Up to 32 CPUs can be supported, or up to 16 if kmap_local()
debugging is enabled, which uses half of the per-CPU fixmap
slots as guard regions.
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
depends on SMP
select GENERIC_IRQ_MIGRATION
help
Say Y here to experiment with turning CPUs off and on. CPUs
can be controlled through /sys/devices/system/cpu.
config ARM_PSCI
bool "Support for the ARM Power State Coordination Interface (PSCI)"
depends on HAVE_ARM_SMCCC
select ARM_PSCI_FW
help
Say Y here if you want Linux to communicate with system firmware
implementing the PSCI specification for CPU-centric power
management operations described in ARM document number ARM DEN
0022A ("Power State Coordination Interface System Software on
ARM processors").
config HZ_FIXED
int
default 128 if SOC_AT91RM9200
default 0
choice
depends on HZ_FIXED = 0
prompt "Timer frequency"
config HZ_100
bool "100 Hz"
config HZ_200
bool "200 Hz"
config HZ_250
bool "250 Hz"
config HZ_300
bool "300 Hz"
config HZ_500
bool "500 Hz"
config HZ_1000
bool "1000 Hz"
endchoice
config HZ
int
default HZ_FIXED if HZ_FIXED != 0
default 100 if HZ_100
default 200 if HZ_200
default 250 if HZ_250
default 300 if HZ_300
default 500 if HZ_500
default 1000
config SCHED_HRTICK
def_bool HIGH_RES_TIMERS
config THUMB2_KERNEL
bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY
depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K
default y if CPU_THUMBONLY
select ARM_UNWIND
help
By enabling this option, the kernel will be compiled in
Thumb-2 mode.
If unsure, say N.
config ARM_PATCH_IDIV
bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
depends on CPU_32v7
default y
help
The ARM compiler inserts calls to __aeabi_idiv() and
__aeabi_uidiv() when it needs to perform division on signed
and unsigned integers. Some v7 CPUs have support for the sdiv
and udiv instructions that can be used to implement those
functions.
Enabling this option allows the kernel to modify itself to
replace the first two instructions of these library functions
with the sdiv or udiv plus "bx lr" instructions when the CPU
it is running on supports them. Typically this will be faster
and less power intensive than running the original library
code to do integer division.
config AEABI
bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
!CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG
help
This option allows for the kernel to be compiled using the latest
ARM ABI (aka EABI). This is only useful if you are using a user
space environment that is also compiled with EABI.
Since there are major incompatibilities between the legacy ABI and
EABI, especially with regard to structure member alignment, this
option also changes the kernel syscall calling convention to
disambiguate both ABIs and allow for backward compatibility support
(selected with CONFIG_OABI_COMPAT).
To use this you need GCC version 4.0.0 or later.
config OABI_COMPAT
bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
depends on AEABI && !THUMB2_KERNEL
help
This option preserves the old syscall interface along with the
new (ARM EABI) one. It also provides a compatibility layer to
intercept syscalls that have structure arguments which layout
in memory differs between the legacy ABI and the new ARM EABI
(only for non "thumb" binaries). This option adds a tiny
overhead to all syscalls and produces a slightly larger kernel.
The seccomp filter system will not be available when this is
selected, since there is no way yet to sensibly distinguish
between calling conventions during filtering.
If you know you'll be using only pure EABI user space then you
can say N here. If this option is not selected and you attempt
to execute a legacy ABI binary then the result will be
UNPREDICTABLE (in fact it can be predicted that it won't work
at all). If in doubt say N.
config ARCH_SELECT_MEMORY_MODEL
def_bool y
config ARCH_FLATMEM_ENABLE
def_bool !(ARCH_RPC || ARCH_SA1100)
config ARCH_SPARSEMEM_ENABLE
def_bool !ARCH_FOOTBRIDGE
select SPARSEMEM_STATIC if SPARSEMEM
config HIGHMEM
bool "High Memory Support"
depends on MMU
select KMAP_LOCAL
select KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
help
The address space of ARM processors is only 4 Gigabytes large
and it has to accommodate user address space, kernel address
space as well as some memory mapped IO. That means that, if you
have a large amount of physical memory and/or IO, not all of the
memory can be "permanently mapped" by the kernel. The physical
memory that is not permanently mapped is called "high memory".
Depending on the selected kernel/user memory split, minimum
vmalloc space and actual amount of RAM, you may not need this
option which should result in a slightly faster kernel.
If unsure, say n.
config HIGHPTE
bool "Allocate 2nd-level pagetables from highmem" if EXPERT
depends on HIGHMEM
default y
help
The VM uses one page of physical memory for each page table.
For systems with a lot of processes, this can use a lot of
precious low memory, eventually leading to low memory being
consumed by page tables. Setting this option will allow
user-space 2nd level page tables to reside in high memory.
config CPU_SW_DOMAIN_PAN
bool "Enable use of CPU domains to implement privileged no-access"
depends on MMU && !ARM_LPAE
default y
help
Increase kernel security by ensuring that normal kernel accesses
are unable to access userspace addresses. This can help prevent
use-after-free bugs becoming an exploitable privilege escalation
by ensuring that magic values (such as LIST_POISON) will always
fault when dereferenced.
CPUs with low-vector mappings use a best-efforts implementation.
Their lower 1MB needs to remain accessible for the vectors, but
the remainder of userspace will become appropriately inaccessible.
config HW_PERF_EVENTS
def_bool y
depends on ARM_PMU
config ARM_MODULE_PLTS
bool "Use PLTs to allow module memory to spill over into vmalloc area"
depends on MODULES
select KASAN_VMALLOC if KASAN
default y
help
Allocate PLTs when loading modules so that jumps and calls whose
targets are too far away for their relative offsets to be encoded
in the instructions themselves can be bounced via veneers in the
module's PLT. This allows modules to be allocated in the generic
vmalloc area after the dedicated module memory area has been
exhausted. The modules will use slightly more memory, but after
rounding up to page size, the actual memory footprint is usually
the same.
Disabling this is usually safe for small single-platform
configurations. If unsure, say y.
config ARCH_FORCE_MAX_ORDER
int "Order of maximal physically contiguous allocations"
default "11" if SOC_AM33XX
default "8" if SA1111
default "10"
help
The kernel page allocator limits the size of maximal physically
contiguous allocations. The limit is called MAX_ORDER and it
defines the maximal power of two of number of pages that can be
allocated as a single contiguous block. This option allows
overriding the default setting when ability to allocate very
large blocks of physically contiguous memory is required.
Don't change if unsure.
config ALIGNMENT_TRAP
def_bool CPU_CP15_MMU
select HAVE_PROC_CPU if PROC_FS
help
ARM processors cannot fetch/store information which is not
naturally aligned on the bus, i.e., a 4 byte fetch must start at an
address divisible by 4. On 32-bit ARM processors, these non-aligned
fetch/store instructions will be emulated in software if you say
here, which has a severe performance impact. This is necessary for
correct operation of some network protocols. With an IP-only
configuration it is safe to say N, otherwise say Y.
config UACCESS_WITH_MEMCPY
bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user()"
depends on MMU
default y if CPU_FEROCEON
help
Implement faster copy_to_user and clear_user methods for CPU
cores where a 8-word STM instruction give significantly higher
memory write throughput than a sequence of individual 32bit stores.
A possible side effect is a slight increase in scheduling latency
between threads sharing the same address space if they invoke
such copy operations with large buffers.
However, if the CPU data cache is using a write-allocate mode,
this option is unlikely to provide any performance gain.
config PARAVIRT
bool "Enable paravirtualization code"
help
This changes the kernel so it can modify itself when it is run
under a hypervisor, potentially improving performance significantly
over full virtualization.
config PARAVIRT_TIME_ACCOUNTING
bool "Paravirtual steal time accounting"
select PARAVIRT
help
Select this option to enable fine granularity task steal time
accounting. Time spent executing other tasks in parallel with
the current vCPU is discounted from the vCPU power. To account for
that, there can be a small performance impact.
If in doubt, say N here.
config XEN_DOM0
def_bool y
depends on XEN
config XEN
bool "Xen guest support on ARM"
depends on ARM && AEABI && OF
depends on CPU_V7 && !CPU_V6
depends on !GENERIC_ATOMIC64
depends on MMU
select ARCH_DMA_ADDR_T_64BIT
select ARM_PSCI
select SWIOTLB
select SWIOTLB_XEN
select PARAVIRT
help
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
config CC_HAVE_STACKPROTECTOR_TLS
def_bool $(cc-option,-mtp=cp15 -mstack-protector-guard=tls -mstack-protector-guard-offset=0)
config STACKPROTECTOR_PER_TASK
bool "Use a unique stack canary value for each task"
depends on STACKPROTECTOR && CURRENT_POINTER_IN_TPIDRURO && !XIP_DEFLATED_DATA
depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS
select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS
default y
help
Due to the fact that GCC uses an ordinary symbol reference from
which to load the value of the stack canary, this value can only
change at reboot time on SMP systems, and all tasks running in the
kernel's address space are forced to use the same canary value for
the entire duration that the system is up.
Enable this option to switch to a different method that uses a
different canary value for each task.
endmenu
menu "Boot options"
config USE_OF
bool "Flattened Device Tree support"
select IRQ_DOMAIN
select OF
help
Include support for flattened device tree machine descriptions.
config ARCH_WANT_FLAT_DTB_INSTALL
def_bool y
config ATAGS
bool "Support for the traditional ATAGS boot data passing"
default y
help
This is the traditional way of passing data to the kernel at boot
time. If you are solely relying on the flattened device tree (or
the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
to remove ATAGS support from your kernel binary.
config DEPRECATED_PARAM_STRUCT
bool "Provide old way to pass kernel parameters"
depends on ATAGS
help
This was deprecated in 2001 and announced to live on for 5 years.
Some old boot loaders still use this way.
# Compressed boot loader in ROM. Yes, we really want to ask about
# TEXT and BSS so we preserve their values in the config files.
config ZBOOT_ROM_TEXT
hex "Compressed ROM boot loader base address"
default 0x0
help
The physical address at which the ROM-able zImage is to be
placed in the target. Platforms which normally make use of
ROM-able zImage formats normally set this to a suitable
value in their defconfig file.
If ZBOOT_ROM is not enabled, this has no effect.
config ZBOOT_ROM_BSS
hex "Compressed ROM boot loader BSS address"
default 0x0
help
The base address of an area of read/write memory in the target
for the ROM-able zImage which must be available while the
decompressor is running. It must be large enough to hold the
entire decompressed kernel plus an additional 128 KiB.
Platforms which normally make use of ROM-able zImage formats
normally set this to a suitable value in their defconfig file.
If ZBOOT_ROM is not enabled, this has no effect.
config ZBOOT_ROM
bool "Compressed boot loader in ROM/flash"
depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
depends on !ARM_APPENDED_DTB && !XIP_KERNEL && !AUTO_ZRELADDR
help
Say Y here if you intend to execute your compressed kernel image
(zImage) directly from ROM or flash. If unsure, say N.
config ARM_APPENDED_DTB
bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
depends on OF
help
With this option, the boot code will look for a device tree binary
(DTB) appended to zImage
(e.g. cat zImage <filename>.dtb > zImage_w_dtb).
This is meant as a backward compatibility convenience for those
systems with a bootloader that can't be upgraded to accommodate
the documented boot protocol using a device tree.
Beware that there is very little in terms of protection against
this option being confused by leftover garbage in memory that might
look like a DTB header after a reboot if no actual DTB is appended
to zImage. Do not leave this option active in a production kernel
if you don't intend to always append a DTB. Proper passing of the
location into r2 of a bootloader provided DTB is always preferable
to this option.
config ARM_ATAG_DTB_COMPAT
bool "Supplement the appended DTB with traditional ATAG information"
depends on ARM_APPENDED_DTB
help
Some old bootloaders can't be updated to a DTB capable one, yet
they provide ATAGs with memory configuration, the ramdisk address,
the kernel cmdline string, etc. Such information is dynamically
provided by the bootloader and can't always be stored in a static
DTB. To allow a device tree enabled kernel to be used with such
bootloaders, this option allows zImage to extract the information
from the ATAG list and store it at run time into the appended DTB.
choice
prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
config ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
bool "Use bootloader kernel arguments if available"
help
Uses the command-line options passed by the boot loader instead of
the device tree bootargs property. If the boot loader doesn't provide
any, the device tree bootargs property will be used.
config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND
bool "Extend with bootloader kernel arguments"
help
The command-line arguments provided by the boot loader will be
appended to the the device tree bootargs property.
endchoice
config CMDLINE
string "Default kernel command string"
default ""
help
On some architectures (e.g. CATS), there is currently no way
for the boot loader to pass arguments to the kernel. For these
architectures, you should supply some command-line options at build
time by entering them here. As a minimum, you should specify the
memory size and the root device (e.g., mem=64M root=/dev/nfs).
choice
prompt "Kernel command line type" if CMDLINE != ""
default CMDLINE_FROM_BOOTLOADER
config CMDLINE_FROM_BOOTLOADER
bool "Use bootloader kernel arguments if available"
help
Uses the command-line options passed by the boot loader. If
the boot loader doesn't provide any, the default kernel command
string provided in CMDLINE will be used.
config CMDLINE_EXTEND
bool "Extend bootloader kernel arguments"
help
The command-line arguments provided by the boot loader will be
appended to the default kernel command string.
config CMDLINE_FORCE
bool "Always use the default kernel command string"
help
Always use the default kernel command string, even if the boot
loader passes other arguments to the kernel.
This is useful if you cannot or don't want to change the
command-line options your boot loader passes to the kernel.
endchoice
config XIP_KERNEL
bool "Kernel Execute-In-Place from ROM"
depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
depends on !ARM_PATCH_IDIV && !ARM_PATCH_PHYS_VIRT && !SMP_ON_UP
help
Execute-In-Place allows the kernel to run from non-volatile storage
directly addressable by the CPU, such as NOR flash. This saves RAM
space since the text section of the kernel is not loaded from flash
to RAM. Read-write sections, such as the data section and stack,
are still copied to RAM. The XIP kernel is not compressed since
it has to run directly from flash, so it will take more space to
store it. The flash address used to link the kernel object files,
and for storing it, is configuration dependent. Therefore, if you
say Y here, you must know the proper physical address where to
store the kernel image depending on your own flash memory usage.
Also note that the make target becomes "make xipImage" rather than
"make zImage" or "make Image". The final kernel binary to put in
ROM memory will be arch/arm/boot/xipImage.
If unsure, say N.
config XIP_PHYS_ADDR
hex "XIP Kernel Physical Location"
depends on XIP_KERNEL
default "0x00080000"
help
This is the physical address in your flash memory the kernel will
be linked for and stored to. This address is dependent on your
own flash usage.
config XIP_DEFLATED_DATA
bool "Store kernel .data section compressed in ROM"
depends on XIP_KERNEL
select ZLIB_INFLATE
help
Before the kernel is actually executed, its .data section has to be
copied to RAM from ROM. This option allows for storing that data
in compressed form and decompressed to RAM rather than merely being
copied, saving some precious ROM space. A possible drawback is a
slightly longer boot delay.
config ARCH_SUPPORTS_KEXEC
def_bool (!SMP || PM_SLEEP_SMP) && MMU
config ATAGS_PROC
bool "Export atags in procfs"
depends on ATAGS && KEXEC
default y
help
Should the atags used to boot the kernel be exported in an "atags"
file in procfs. Useful with kexec.
config ARCH_SUPPORTS_CRASH_DUMP
def_bool y
config AUTO_ZRELADDR
bool "Auto calculation of the decompressed kernel image address" if !ARCH_MULTIPLATFORM
default !(ARCH_FOOTBRIDGE || ARCH_RPC || ARCH_SA1100)
help
ZRELADDR is the physical address where the decompressed kernel
image will be placed. If AUTO_ZRELADDR is selected, the address
will be determined at run-time, either by masking the current IP
with 0xf8000000, or, if invalid, from the DTB passed in r2.
This assumes the zImage being placed in the first 128MB from
start of memory.
config EFI_STUB
bool
config EFI
bool "UEFI runtime support"
depends on OF && !CPU_BIG_ENDIAN && MMU && AUTO_ZRELADDR && !XIP_KERNEL
select UCS2_STRING
select EFI_PARAMS_FROM_FDT
select EFI_STUB
select EFI_GENERIC_STUB
select EFI_RUNTIME_WRAPPERS
help
This option provides support for runtime services provided
by UEFI firmware (such as non-volatile variables, realtime
clock, and platform reset). A UEFI stub is also provided to
allow the kernel to be booted as an EFI application. This
is only useful for kernels that may run on systems that have
UEFI firmware.
config DMI
bool "Enable support for SMBIOS (DMI) tables"
depends on EFI
default y
help
This enables SMBIOS/DMI feature for systems.
This option is only useful on systems that have UEFI firmware.
However, even with this option, the resultant kernel should
continue to boot on existing non-UEFI platforms.
NOTE: This does *NOT* enable or encourage the use of DMI quirks,
i.e., the the practice of identifying the platform via DMI to
decide whether certain workarounds for buggy hardware and/or
firmware need to be enabled. This would require the DMI subsystem
to be enabled much earlier than we do on ARM, which is non-trivial.
endmenu
menu "CPU Power Management"
source "drivers/cpufreq/Kconfig"
source "drivers/cpuidle/Kconfig"
endmenu
menu "Floating point emulation"
comment "At least one emulation must be selected"
config FPE_NWFPE
bool "NWFPE math emulation"
depends on (!AEABI || OABI_COMPAT) && !THUMB2_KERNEL
help
Say Y to include the NWFPE floating point emulator in the kernel.
This is necessary to run most binaries. Linux does not currently
support floating point hardware so you need to say Y here even if
your machine has an FPA or floating point co-processor podule.
You may say N here if you are going to load the Acorn FPEmulator
early in the bootup.
config FPE_NWFPE_XP
bool "Support extended precision"
depends on FPE_NWFPE
help
Say Y to include 80-bit support in the kernel floating-point
emulator. Otherwise, only 32 and 64-bit support is compiled in.
Note that gcc does not generate 80-bit operations by default,
so in most cases this option only enlarges the size of the
floating point emulator without any good reason.
You almost surely want to say N here.
config FPE_FASTFPE
bool "FastFPE math emulation (EXPERIMENTAL)"
depends on (!AEABI || OABI_COMPAT) && !CPU_32v3
help
Say Y here to include the FAST floating point emulator in the kernel.
This is an experimental much faster emulator which now also has full
precision for the mantissa. It does not support any exceptions.
It is very simple, and approximately 3-6 times faster than NWFPE.
It should be sufficient for most programs. It may be not suitable
for scientific calculations, but you have to check this for yourself.
If you do not feel you need a faster FP emulation you should better
choose NWFPE.
config VFP
bool "VFP-format floating point maths"
depends on CPU_V6 || CPU_V6K || CPU_ARM926T || CPU_V7 || CPU_FEROCEON
help
Say Y to include VFP support code in the kernel. This is needed
if your hardware includes a VFP unit.
Please see <file:Documentation/arch/arm/vfp/release-notes.rst> for
release notes and additional status information.
Say N if your target does not have VFP hardware.
config VFPv3
bool
depends on VFP
default y if CPU_V7
config NEON
bool "Advanced SIMD (NEON) Extension support"
depends on VFPv3 && CPU_V7
help
Say Y to include support code for NEON, the ARMv7 Advanced SIMD
Extension.
config KERNEL_MODE_NEON
bool "Support for NEON in kernel mode"
depends on NEON && AEABI
help
Say Y to include support for NEON in kernel mode.
endmenu
menu "Power management options"
source "kernel/power/Kconfig"
config ARCH_SUSPEND_POSSIBLE
depends on CPU_ARM920T || CPU_ARM926T || CPU_FEROCEON || CPU_SA1100 || \
CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M || CPU_XSC3 || CPU_XSCALE || CPU_MOHAWK
def_bool y
config ARM_CPU_SUSPEND
def_bool PM_SLEEP || BL_SWITCHER || ARM_PSCI_FW
depends on ARCH_SUSPEND_POSSIBLE
config ARCH_HIBERNATION_POSSIBLE
bool
depends on MMU
default y if ARCH_SUSPEND_POSSIBLE
endmenu
source "arch/arm/Kconfig.assembler"