config ARM64
def_bool y
select ACPI_CCA_REQUIRED if ACPI
select ACPI_GENERIC_GSI if ACPI
select ACPI_REDUCED_HARDWARE_ONLY if ACPI
select ACPI_MCFG if ACPI
select ACPI_SPCR_TABLE if ACPI
select ARCH_CLOCKSOURCE_DATA
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_KCOV
select ARCH_HAS_SG_CHAIN
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_NUMA_BALANCING
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
select ARCH_WANT_FRAME_POINTERS
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARM_AMBA
select ARM_ARCH_TIMER
select ARM_GIC
select AUDIT_ARCH_COMPAT_GENERIC
select ARM_GIC_V2M if PCI
select ARM_GIC_V3
select ARM_GIC_V3_ITS if PCI
select ARM_PSCI_FW
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS
select COMMON_CLK
select CPU_PM if (SUSPEND || CPU_IDLE)
select DCACHE_WORD_ACCESS
select EDAC_SUPPORT
select FRAME_POINTER
select GENERIC_ALLOCATOR
select GENERIC_CLOCKEVENTS
select GENERIC_CLOCKEVENTS_BROADCAST
select GENERIC_CPU_AUTOPROBE
select GENERIC_EARLY_IOREMAP
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_PROBE
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_PCI_IOMAP
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select GENERIC_TIME_VSYSCALL
select HANDLE_DOMAIN_IRQ
select HARDIRQS_SW_RESEND
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_BITREVERSE
select HAVE_ARCH_HARDENED_USERCOPY
select HAVE_ARCH_HUGE_VMAP
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARM_SMCCC
select HAVE_EBPF_JIT
select HAVE_C_RECORDMCOUNT
select HAVE_CC_STACKPROTECTOR
select HAVE_CMPXCHG_DOUBLE
select HAVE_CMPXCHG_LOCAL
select HAVE_CONTEXT_TRACKING
select HAVE_DEBUG_BUGVERBOSE
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_API_DEBUG
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_EFFICIENT_UNALIGNED_ACCESS
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_GCC_PLUGINS
select HAVE_GENERIC_DMA_COHERENT
select HAVE_HW_BREAKPOINT if PERF_EVENTS
select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_MEMBLOCK
select HAVE_MEMBLOCK_NODE_MAP if NUMA
select HAVE_PATA_PLATFORM
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RCU_TABLE_FREE
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_KPROBES
select HAVE_KRETPROBES if HAVE_KPROBES
select IOMMU_DMA if IOMMU_SUPPORT
select IRQ_DOMAIN
select IRQ_FORCED_THREADING
select MODULES_USE_ELF_RELA
select NO_BOOTMEM
select OF
select OF_EARLY_FLATTREE
select OF_RESERVED_MEM
select PCI_ECAM if ACPI
select POWER_RESET
select POWER_SUPPLY
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
help
ARM 64-bit (AArch64) Linux support.
config 64BIT
def_bool y
config ARCH_PHYS_ADDR_T_64BIT
def_bool y
config MMU
def_bool y
config DEBUG_RODATA
def_bool y
config ARM64_PAGE_SHIFT
int
default 16 if ARM64_64K_PAGES
default 14 if ARM64_16K_PAGES
default 12
config ARM64_CONT_SHIFT
int
default 5 if ARM64_64K_PAGES
default 7 if ARM64_16K_PAGES
default 4
config ARCH_MMAP_RND_BITS_MIN
default 14 if ARM64_64K_PAGES
default 16 if ARM64_16K_PAGES
default 18
# max bits determined by the following formula:
# VA_BITS - PAGE_SHIFT - 3
config ARCH_MMAP_RND_BITS_MAX
default 19 if ARM64_VA_BITS=36
default 24 if ARM64_VA_BITS=39
default 27 if ARM64_VA_BITS=42
default 30 if ARM64_VA_BITS=47
default 29 if ARM64_VA_BITS=48 && ARM64_64K_PAGES
default 31 if ARM64_VA_BITS=48 && ARM64_16K_PAGES
default 33 if ARM64_VA_BITS=48
default 14 if ARM64_64K_PAGES
default 16 if ARM64_16K_PAGES
default 18
config ARCH_MMAP_RND_COMPAT_BITS_MIN
default 7 if ARM64_64K_PAGES
default 9 if ARM64_16K_PAGES
default 11
config ARCH_MMAP_RND_COMPAT_BITS_MAX
default 16
config NO_IOPORT_MAP
def_bool y if !PCI
config STACKTRACE_SUPPORT
def_bool y
config ILLEGAL_POINTER_VALUE
hex
default 0xdead000000000000
config LOCKDEP_SUPPORT
def_bool y
config TRACE_IRQFLAGS_SUPPORT
def_bool y
config RWSEM_XCHGADD_ALGORITHM
def_bool y
config GENERIC_BUG
def_bool y
depends on BUG
config GENERIC_BUG_RELATIVE_POINTERS
def_bool y
depends on GENERIC_BUG
config GENERIC_HWEIGHT
def_bool y
config GENERIC_CSUM
def_bool y
config GENERIC_CALIBRATE_DELAY
def_bool y
config ZONE_DMA
def_bool y
config HAVE_GENERIC_RCU_GUP
def_bool y
config ARCH_DMA_ADDR_T_64BIT
def_bool y
config NEED_DMA_MAP_STATE
def_bool y
config NEED_SG_DMA_LENGTH
def_bool y
config SMP
def_bool y
config SWIOTLB
def_bool y
config IOMMU_HELPER
def_bool SWIOTLB
config KERNEL_MODE_NEON
def_bool y
config FIX_EARLYCON_MEM
def_bool y
config PGTABLE_LEVELS
int
default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42
default 3 if ARM64_64K_PAGES && ARM64_VA_BITS_48
default 3 if ARM64_4K_PAGES && ARM64_VA_BITS_39
default 3 if ARM64_16K_PAGES && ARM64_VA_BITS_47
default 4 if !ARM64_64K_PAGES && ARM64_VA_BITS_48
source "init/Kconfig"
source "kernel/Kconfig.freezer"
source "arch/arm64/Kconfig.platforms"
menu "Bus support"
config PCI
bool "PCI support"
help
This feature enables support for PCI bus system. If you say Y
here, the kernel will include drivers and infrastructure code
to support PCI bus devices.
config PCI_DOMAINS
def_bool PCI
config PCI_DOMAINS_GENERIC
def_bool PCI
config PCI_SYSCALL
def_bool PCI
source "drivers/pci/Kconfig"
endmenu
menu "Kernel Features"
menu "ARM errata workarounds via the alternatives framework"
config ARM64_ERRATUM_826319
bool "Cortex-A53: 826319: System might deadlock if a write cannot complete until read data is accepted"
default y
help
This option adds an alternative code sequence to work around ARM
erratum 826319 on Cortex-A53 parts up to r0p2 with an AMBA 4 ACE or
AXI master interface and an L2 cache.
If a Cortex-A53 uses an AMBA AXI4 ACE interface to other processors
and is unable to accept a certain write via this interface, it will
not progress on read data presented on the read data channel and the
system can deadlock.
The workaround promotes data cache clean instructions to
data cache clean-and-invalidate.
Please note that this does not necessarily enable the workaround,
as it depends on the alternative framework, which will only patch
the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_827319
bool "Cortex-A53: 827319: Data cache clean instructions might cause overlapping transactions to the interconnect"
default y
help
This option adds an alternative code sequence to work around ARM
erratum 827319 on Cortex-A53 parts up to r0p2 with an AMBA 5 CHI
master interface and an L2 cache.
Under certain conditions this erratum can cause a clean line eviction
to occur at the same time as another transaction to the same address
on the AMBA 5 CHI interface, which can cause data corruption if the
interconnect reorders the two transactions.
The workaround promotes data cache clean instructions to
data cache clean-and-invalidate.
Please note that this does not necessarily enable the workaround,
as it depends on the alternative framework, which will only patch
the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_824069
bool "Cortex-A53: 824069: Cache line might not be marked as clean after a CleanShared snoop"
default y
help
This option adds an alternative code sequence to work around ARM
erratum 824069 on Cortex-A53 parts up to r0p2 when it is connected
to a coherent interconnect.
If a Cortex-A53 processor is executing a store or prefetch for
write instruction at the same time as a processor in another
cluster is executing a cache maintenance operation to the same
address, then this erratum might cause a clean cache line to be
incorrectly marked as dirty.
The workaround promotes data cache clean instructions to
data cache clean-and-invalidate.
Please note that this option does not necessarily enable the
workaround, as it depends on the alternative framework, which will
only patch the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_819472
bool "Cortex-A53: 819472: Store exclusive instructions might cause data corruption"
default y
help
This option adds an alternative code sequence to work around ARM
erratum 819472 on Cortex-A53 parts up to r0p1 with an L2 cache
present when it is connected to a coherent interconnect.
If the processor is executing a load and store exclusive sequence at
the same time as a processor in another cluster is executing a cache
maintenance operation to the same address, then this erratum might
cause data corruption.
The workaround promotes data cache clean instructions to
data cache clean-and-invalidate.
Please note that this does not necessarily enable the workaround,
as it depends on the alternative framework, which will only patch
the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_832075
bool "Cortex-A57: 832075: possible deadlock on mixing exclusive memory accesses with device loads"
default y
help
This option adds an alternative code sequence to work around ARM
erratum 832075 on Cortex-A57 parts up to r1p2.
Affected Cortex-A57 parts might deadlock when exclusive load/store
instructions to Write-Back memory are mixed with Device loads.
The workaround is to promote device loads to use Load-Acquire
semantics.
Please note that this does not necessarily enable the workaround,
as it depends on the alternative framework, which will only patch
the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_834220
bool "Cortex-A57: 834220: Stage 2 translation fault might be incorrectly reported in presence of a Stage 1 fault"
depends on KVM
default y
help
This option adds an alternative code sequence to work around ARM
erratum 834220 on Cortex-A57 parts up to r1p2.
Affected Cortex-A57 parts might report a Stage 2 translation
fault as the result of a Stage 1 fault for load crossing a
page boundary when there is a permission or device memory
alignment fault at Stage 1 and a translation fault at Stage 2.
The workaround is to verify that the Stage 1 translation
doesn't generate a fault before handling the Stage 2 fault.
Please note that this does not necessarily enable the workaround,
as it depends on the alternative framework, which will only patch
the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_845719
bool "Cortex-A53: 845719: a load might read incorrect data"
depends on COMPAT
default y
help
This option adds an alternative code sequence to work around ARM
erratum 845719 on Cortex-A53 parts up to r0p4.
When running a compat (AArch32) userspace on an affected Cortex-A53
part, a load at EL0 from a virtual address that matches the bottom 32
bits of the virtual address used by a recent load at (AArch64) EL1
might return incorrect data.
The workaround is to write the contextidr_el1 register on exception
return to a 32-bit task.
Please note that this does not necessarily enable the workaround,
as it depends on the alternative framework, which will only patch
the kernel if an affected CPU is detected.
If unsure, say Y.
config ARM64_ERRATUM_843419
bool "Cortex-A53: 843419: A load or store might access an incorrect address"
default y
select ARM64_MODULE_CMODEL_LARGE if MODULES
help
This option links the kernel with '--fix-cortex-a53-843419' and
builds modules using the large memory model in order to avoid the use
of the ADRP instruction, which can cause a subsequent memory access
to use an incorrect address on Cortex-A53 parts up to r0p4.
If unsure, say Y.
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y
help
Enable workaround for erratum 22375, 24313.
This implements two gicv3-its errata workarounds for ThunderX. Both
with small impact affecting only ITS table allocation.
erratum 22375: only alloc 8MB table size
erratum 24313: ignore memory access type
The fixes are in ITS initialization and basically ignore memory access
type and table size provided by the TYPER and BASER registers.
If unsure, say Y.
config CAVIUM_ERRATUM_23144
bool "Cavium erratum 23144: ITS SYNC hang on dual socket system"
depends on NUMA
default y
help
ITS SYNC command hang for cross node io and collections/cpu mapping.
If unsure, say Y.
config CAVIUM_ERRATUM_23154
bool "Cavium erratum 23154: Access to ICC_IAR1_EL1 is not sync'ed"
default y
help
The gicv3 of ThunderX requires a modified version for
reading the IAR status to ensure data synchronization
(access to icc_iar1_el1 is not sync'ed before and after).
If unsure, say Y.
config CAVIUM_ERRATUM_27456
bool "Cavium erratum 27456: Broadcast TLBI instructions may cause icache corruption"
default y
help
On ThunderX T88 pass 1.x through 2.1 parts, broadcast TLBI
instructions may cause the icache to become corrupted if it
contains data for a non-current ASID. The fix is to
invalidate the icache when changing the mm context.
If unsure, say Y.
endmenu
choice
prompt "Page size"
default ARM64_4K_PAGES
help
Page size (translation granule) configuration.
config ARM64_4K_PAGES
bool "4KB"
help
This feature enables 4KB pages support.
config ARM64_16K_PAGES
bool "16KB"
help
The system will use 16KB pages support. AArch32 emulation
requires applications compiled with 16K (or a multiple of 16K)
aligned segments.
config ARM64_64K_PAGES
bool "64KB"
help
This feature enables 64KB pages support (4KB by default)
allowing only two levels of page tables and faster TLB
look-up. AArch32 emulation requires applications compiled
with 64K aligned segments.
endchoice
choice
prompt "Virtual address space size"
default ARM64_VA_BITS_39 if ARM64_4K_PAGES
default ARM64_VA_BITS_47 if ARM64_16K_PAGES
default ARM64_VA_BITS_42 if ARM64_64K_PAGES
help
Allows choosing one of multiple possible virtual address
space sizes. The level of translation table is determined by
a combination of page size and virtual address space size.
config ARM64_VA_BITS_36
bool "36-bit" if EXPERT
depends on ARM64_16K_PAGES
config ARM64_VA_BITS_39
bool "39-bit"
depends on ARM64_4K_PAGES
config ARM64_VA_BITS_42
bool "42-bit"
depends on ARM64_64K_PAGES
config ARM64_VA_BITS_47
bool "47-bit"
depends on ARM64_16K_PAGES
config ARM64_VA_BITS_48
bool "48-bit"
endchoice
config ARM64_VA_BITS
int
default 36 if ARM64_VA_BITS_36
default 39 if ARM64_VA_BITS_39
default 42 if ARM64_VA_BITS_42
default 47 if ARM64_VA_BITS_47
default 48 if ARM64_VA_BITS_48
config CPU_BIG_ENDIAN
bool "Build big-endian kernel"
help
Say Y if you plan on running a kernel in big-endian mode.
config SCHED_MC
bool "Multi-core scheduler support"
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"
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 NR_CPUS
int "Maximum number of CPUs (2-4096)"
range 2 4096
# These have to remain sorted largest to smallest
default "64"
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
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.
# Common NUMA Features
config NUMA
bool "Numa Memory Allocation and Scheduler Support"
select ACPI_NUMA if ACPI
select OF_NUMA
help
Enable NUMA (Non Uniform Memory Access) support.
The kernel will try to allocate memory used by a CPU on the
local memory of the CPU and add some more
NUMA awareness to the kernel.
config NODES_SHIFT
int "Maximum NUMA Nodes (as a power of 2)"
range 1 10
default "2"
depends on NEED_MULTIPLE_NODES
help
Specify the maximum number of NUMA Nodes available on the target
system. Increases memory reserved to accommodate various tables.
config USE_PERCPU_NUMA_NODE_ID
def_bool y
depends on NUMA
config HAVE_SETUP_PER_CPU_AREA
def_bool y
depends on NUMA
config NEED_PER_CPU_EMBED_FIRST_CHUNK
def_bool y
depends on NUMA
source kernel/Kconfig.preempt
source kernel/Kconfig.hz
config ARCH_SUPPORTS_DEBUG_PAGEALLOC
def_bool y
config ARCH_HAS_HOLES_MEMORYMODEL
def_bool y if SPARSEMEM
config ARCH_SPARSEMEM_ENABLE
def_bool y
select SPARSEMEM_VMEMMAP_ENABLE
config ARCH_SPARSEMEM_DEFAULT
def_bool ARCH_SPARSEMEM_ENABLE
config ARCH_SELECT_MEMORY_MODEL
def_bool ARCH_SPARSEMEM_ENABLE
config HAVE_ARCH_PFN_VALID
def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM
config HW_PERF_EVENTS
def_bool y
depends on ARM_PMU
config SYS_SUPPORTS_HUGETLBFS
def_bool y
config ARCH_WANT_HUGE_PMD_SHARE
def_bool y if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
config ARCH_HAS_CACHE_LINE_SIZE
def_bool y
source "mm/Kconfig"
config SECCOMP
bool "Enable seccomp to safely compute untrusted bytecode"
---help---
This kernel feature is useful for number crunching applications
that may need to compute untrusted bytecode during their
execution. By using pipes or other transports made available to
the process as file descriptors supporting the read/write
syscalls, it's possible to isolate those applications in
their own address space using seccomp. Once seccomp is
enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
and the task is only allowed to execute a few safe syscalls
defined by each seccomp mode.
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
default n
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 KEXEC
depends on PM_SLEEP_SMP
select KEXEC_CORE
bool "kexec system call"
---help---
kexec is a system call that implements the ability to shutdown your
current kernel, and to start another kernel. It is like a reboot
but it is independent of the system firmware. And like a reboot
you can start any kernel with it, not just Linux.
config XEN_DOM0
def_bool y
depends on XEN
config XEN
bool "Xen guest support on ARM64"
depends on ARM64 && OF
select SWIOTLB_XEN
select PARAVIRT
help
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
config FORCE_MAX_ZONEORDER
int
default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
default "12" if (ARM64_16K_PAGES && TRANSPARENT_HUGEPAGE)
default "11"
help
The kernel memory allocator divides physically contiguous memory
blocks into "zones", where each zone is a power of two number of
pages. This option selects the largest power of two that the kernel
keeps in the memory allocator. If you need to allocate very large
blocks of physically contiguous memory, then you may need to
increase this value.
This config option is actually maximum order plus one. For example,
a value of 11 means that the largest free memory block is 2^10 pages.
We make sure that we can allocate upto a HugePage size for each configuration.
Hence we have :
MAX_ORDER = (PMD_SHIFT - PAGE_SHIFT) + 1 => PAGE_SHIFT - 2
However for 4K, we choose a higher default value, 11 as opposed to 10, giving us
4M allocations matching the default size used by generic code.
menuconfig ARMV8_DEPRECATED
bool "Emulate deprecated/obsolete ARMv8 instructions"
depends on COMPAT
help
Legacy software support may require certain instructions
that have been deprecated or obsoleted in the architecture.
Enable this config to enable selective emulation of these
features.
If unsure, say Y
if ARMV8_DEPRECATED
config SWP_EMULATION
bool "Emulate SWP/SWPB instructions"
help
ARMv8 obsoletes the use of A32 SWP/SWPB instructions such that
they are always undefined. Say Y here to enable software
emulation of these instructions for userspace using LDXR/STXR.
In some older versions of glibc [<=2.8] SWP is used during futex
trylock() operations with the assumption that the code will not
be preempted. This invalid assumption may be more likely to fail
with SWP emulation enabled, leading to deadlock of the user
application.
NOTE: when accessing uncached shared regions, LDXR/STXR rely
on an external transaction monitoring block called a global
monitor to maintain update atomicity. If your system does not
implement a global monitor, this option can cause programs that
perform SWP operations to uncached memory to deadlock.
If unsure, say Y
config CP15_BARRIER_EMULATION
bool "Emulate CP15 Barrier instructions"
help
The CP15 barrier instructions - CP15ISB, CP15DSB, and
CP15DMB - are deprecated in ARMv8 (and ARMv7). It is
strongly recommended to use the ISB, DSB, and DMB
instructions instead.
Say Y here to enable software emulation of these
instructions for AArch32 userspace code. When this option is
enabled, CP15 barrier usage is traced which can help
identify software that needs updating.
If unsure, say Y
config SETEND_EMULATION
bool "Emulate SETEND instruction"
help
The SETEND instruction alters the data-endianness of the
AArch32 EL0, and is deprecated in ARMv8.
Say Y here to enable software emulation of the instruction
for AArch32 userspace code.
Note: All the cpus on the system must have mixed endian support at EL0
for this feature to be enabled. If a new CPU - which doesn't support mixed
endian - is hotplugged in after this feature has been enabled, there could
be unexpected results in the applications.
If unsure, say Y
endif
menu "ARMv8.1 architectural features"
config ARM64_HW_AFDBM
bool "Support for hardware updates of the Access and Dirty page flags"
default y
help
The ARMv8.1 architecture extensions introduce support for
hardware updates of the access and dirty information in page
table entries. When enabled in TCR_EL1 (HA and HD bits) on
capable processors, accesses to pages with PTE_AF cleared will
set this bit instead of raising an access flag fault.
Similarly, writes to read-only pages with the DBM bit set will
clear the read-only bit (AP[2]) instead of raising a
permission fault.
Kernels built with this configuration option enabled continue
to work on pre-ARMv8.1 hardware and the performance impact is
minimal. If unsure, say Y.
config ARM64_PAN
bool "Enable support for Privileged Access Never (PAN)"
default y
help
Privileged Access Never (PAN; part of the ARMv8.1 Extensions)
prevents the kernel or hypervisor from accessing user-space (EL0)
memory directly.
Choosing this option will cause any unprotected (not using
copy_to_user et al) memory access to fail with a permission fault.
The feature is detected at runtime, and will remain as a 'nop'
instruction if the cpu does not implement the feature.
config ARM64_LSE_ATOMICS
bool "Atomic instructions"
help
As part of the Large System Extensions, ARMv8.1 introduces new
atomic instructions that are designed specifically to scale in
very large systems.
Say Y here to make use of these instructions for the in-kernel
atomic routines. This incurs a small overhead on CPUs that do
not support these instructions and requires the kernel to be
built with binutils >= 2.25.
config ARM64_VHE
bool "Enable support for Virtualization Host Extensions (VHE)"
default y
help
Virtualization Host Extensions (VHE) allow the kernel to run
directly at EL2 (instead of EL1) on processors that support
it. This leads to better performance for KVM, as they reduce
the cost of the world switch.
Selecting this option allows the VHE feature to be detected
at runtime, and does not affect processors that do not
implement this feature.
endmenu
menu "ARMv8.2 architectural features"
config ARM64_UAO
bool "Enable support for User Access Override (UAO)"
default y
help
User Access Override (UAO; part of the ARMv8.2 Extensions)
causes the 'unprivileged' variant of the load/store instructions to
be overriden to be privileged.
This option changes get_user() and friends to use the 'unprivileged'
variant of the load/store instructions. This ensures that user-space
really did have access to the supplied memory. When addr_limit is
set to kernel memory the UAO bit will be set, allowing privileged
access to kernel memory.
Choosing this option will cause copy_to_user() et al to use user-space
memory permissions.
The feature is detected at runtime, the kernel will use the
regular load/store instructions if the cpu does not implement the
feature.
endmenu
config ARM64_MODULE_CMODEL_LARGE
bool
config ARM64_MODULE_PLTS
bool
select ARM64_MODULE_CMODEL_LARGE
select HAVE_MOD_ARCH_SPECIFIC
config RELOCATABLE
bool
help
This builds the kernel as a Position Independent Executable (PIE),
which retains all relocation metadata required to relocate the
kernel binary at runtime to a different virtual address than the
address it was linked at.
Since AArch64 uses the RELA relocation format, this requires a
relocation pass at runtime even if the kernel is loaded at the
same address it was linked at.
config RANDOMIZE_BASE
bool "Randomize the address of the kernel image"
select ARM64_MODULE_PLTS if MODULES
select RELOCATABLE
help
Randomizes the virtual address at which the kernel image is
loaded, as a security feature that deters exploit attempts
relying on knowledge of the location of kernel internals.
It is the bootloader's job to provide entropy, by passing a
random u64 value in /chosen/kaslr-seed at kernel entry.
When booting via the UEFI stub, it will invoke the firmware's
EFI_RNG_PROTOCOL implementation (if available) to supply entropy
to the kernel proper. In addition, it will randomise the physical
location of the kernel Image as well.
If unsure, say N.
config RANDOMIZE_MODULE_REGION_FULL
bool "Randomize the module region independently from the core kernel"
depends on RANDOMIZE_BASE
default y
help
Randomizes the location of the module region without considering the
location of the core kernel. This way, it is impossible for modules
to leak information about the location of core kernel data structures
but it does imply that function calls between modules and the core
kernel will need to be resolved via veneers in the module PLT.
When this option is not set, the module region will be randomized over
a limited range that contains the [_stext, _etext] interval of the
core kernel, so branch relocations are always in range.
endmenu
menu "Boot options"
config ARM64_ACPI_PARKING_PROTOCOL
bool "Enable support for the ARM64 ACPI parking protocol"
depends on ACPI
help
Enable support for the ARM64 ACPI parking protocol. If disabled
the kernel will not allow booting through the ARM64 ACPI parking
protocol even if the corresponding data is present in the ACPI
MADT table.
config CMDLINE
string "Default kernel command string"
default ""
help
Provide a set of default command-line options at build time by
entering them here. As a minimum, you should specify the the
root device (e.g. root=/dev/nfs).
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.
config EFI_STUB
bool
config EFI
bool "UEFI runtime support"
depends on OF && !CPU_BIG_ENDIAN
select LIBFDT
select UCS2_STRING
select EFI_PARAMS_FROM_FDT
select EFI_RUNTIME_WRAPPERS
select EFI_STUB
select EFI_ARMSTUB
default y
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 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.
endmenu
menu "Userspace binary formats"
source "fs/Kconfig.binfmt"
config COMPAT
bool "Kernel support for 32-bit EL0"
depends on ARM64_4K_PAGES || EXPERT
select COMPAT_BINFMT_ELF
select HAVE_UID16
select OLD_SIGSUSPEND3
select COMPAT_OLD_SIGACTION
help
This option enables support for a 32-bit EL0 running under a 64-bit
kernel at EL1. AArch32-specific components such as system calls,
the user helper functions, VFP support and the ptrace interface are
handled appropriately by the kernel.
If you use a page size other than 4KB (i.e, 16KB or 64KB), please be aware
that you will only be able to execute AArch32 binaries that were compiled
with page size aligned segments.
If you want to execute 32-bit userspace applications, say Y.
config SYSVIPC_COMPAT
def_bool y
depends on COMPAT && SYSVIPC
endmenu
menu "Power management options"
source "kernel/power/Kconfig"
config ARCH_HIBERNATION_POSSIBLE
def_bool y
depends on CPU_PM
config ARCH_HIBERNATION_HEADER
def_bool y
depends on HIBERNATION
config ARCH_SUSPEND_POSSIBLE
def_bool y
endmenu
menu "CPU Power Management"
source "drivers/cpuidle/Kconfig"
source "drivers/cpufreq/Kconfig"
endmenu
source "net/Kconfig"
source "drivers/Kconfig"
source "drivers/firmware/Kconfig"
source "drivers/acpi/Kconfig"
source "fs/Kconfig"
source "arch/arm64/kvm/Kconfig"
source "arch/arm64/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
if CRYPTO
source "arch/arm64/crypto/Kconfig"
endif
source "lib/Kconfig"
