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kernel/linux-rt-4.4.41/arch/arm64/Kconfig 24.1 KB
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  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 ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
  	select ARCH_HAS_ELF_RANDOMIZE
  	select ARCH_HAS_GCOV_PROFILE_ALL
  	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_WANT_OPTIONAL_GPIOLIB
  	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
  	select ARCH_WANT_FRAME_POINTERS
  	select ARM_AMBA
  	select ARM_ARCH_TIMER
  	select ARM_GIC
  	select AUDIT_ARCH_COMPAT_GENERIC
  	select ARM_GIC_V2M if PCI_MSI
  	select ARM_GIC_V3
  	select ARM_GIC_V3_ITS if PCI_MSI
  	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_JUMP_LABEL
  	select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
  	select HAVE_ARCH_KGDB
  	select HAVE_ARCH_SECCOMP_FILTER
  	select HAVE_ARCH_TRACEHOOK
  	select HAVE_BPF_JIT
  	select HAVE_C_RECORDMCOUNT
  	select HAVE_CC_STACKPROTECTOR
  	select HAVE_CMPXCHG_DOUBLE
  	select HAVE_CMPXCHG_LOCAL
  	select HAVE_DEBUG_BUGVERBOSE
  	select HAVE_DEBUG_KMEMLEAK
  	select HAVE_DMA_API_DEBUG
  	select HAVE_DMA_ATTRS
  	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_GENERIC_DMA_COHERENT
  	select HAVE_HW_BREAKPOINT if PERF_EVENTS
  	select HAVE_MEMBLOCK
  	select HAVE_PATA_PLATFORM
  	select HAVE_PERF_EVENTS
  	select HAVE_PERF_REGS
  	select HAVE_PERF_USER_STACK_DUMP
  	select HAVE_RCU_TABLE_FREE
  	select HAVE_PREEMPT_LAZY
  	select HAVE_SYSCALL_TRACEPOINTS
  	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 PERF_USE_VMALLOC
  	select POWER_RESET
  	select POWER_SUPPLY
  	select RTC_LIB
  	select SPARSE_IRQ
  	select SYSCTL_EXCEPTION_TRACE
  	select HAVE_CONTEXT_TRACKING
  	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 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"
  source "drivers/pci/pcie/Kconfig"
  source "drivers/pci/hotplug/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"
  	depends on MODULES
  	default y
  	help
  	  This option builds kernel 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.
  
  	  Note that the kernel itself must be linked with a version of ld
  	  which fixes potentially affected ADRP instructions through the
  	  use of veneers.
  
  	  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.
  
  source kernel/Kconfig.preempt
  source kernel/Kconfig.hz
  
  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_GENERAL_HUGETLB
  	def_bool y
  
  config ARCH_WANT_HUGE_PMD_SHARE
  	def_bool y if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
  
  config HAVE_ARCH_TRANSPARENT_HUGEPAGE
  	def_bool y
  
  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 XEN_DOM0
  	def_bool y
  	depends on XEN
  
  config XEN
  	bool "Xen guest support on ARM64"
  	depends on ARM64 && OF && !PREEMPT_RT_FULL
  	select SWIOTLB_XEN
  	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.
  
  endmenu
  
  endmenu
  
  menu "Boot options"
  
  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_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"