Kconfig 95.7 KB
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# SPDX-License-Identifier: GPL-2.0
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# Select 32 or 64 bit
config 64BIT
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	bool "64-bit kernel" if "$(ARCH)" = "x86"
	default "$(ARCH)" != "i386"
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	---help---
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	  Say yes to build a 64-bit kernel - formerly known as x86_64
	  Say no to build a 32-bit kernel - formerly known as i386

config X86_32
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	def_bool y
	depends on !64BIT
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	# Options that are inherently 32-bit kernel only:
	select ARCH_WANT_IPC_PARSE_VERSION
	select CLKSRC_I8253
	select CLONE_BACKWARDS
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	select HAVE_DEBUG_STACKOVERFLOW
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	select MODULES_USE_ELF_REL
	select OLD_SIGACTION
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	select GENERIC_VDSO_32
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config X86_64
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	def_bool y
	depends on 64BIT
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	# Options that are inherently 64-bit kernel only:
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	select ARCH_HAS_GIGANTIC_PAGE
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	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
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	select ARCH_USE_CMPXCHG_LOCKREF
	select HAVE_ARCH_SOFT_DIRTY
	select MODULES_USE_ELF_RELA
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	select NEED_DMA_MAP_STATE
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	select SWIOTLB
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	select ARCH_HAS_SYSCALL_WRAPPER
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config FORCE_DYNAMIC_FTRACE
	def_bool y
	depends on X86_32
	depends on FUNCTION_TRACER
	select DYNAMIC_FTRACE
	help
	 We keep the static function tracing (!DYNAMIC_FTRACE) around
	 in order to test the non static function tracing in the
	 generic code, as other architectures still use it. But we
	 only need to keep it around for x86_64. No need to keep it
	 for x86_32. For x86_32, force DYNAMIC_FTRACE. 
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#
# Arch settings
#
# ( Note that options that are marked 'if X86_64' could in principle be
#   ported to 32-bit as well. )
#
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config X86
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	def_bool y
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	#
	# Note: keep this list sorted alphabetically
	#
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	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
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	select ARCH_32BIT_OFF_T			if X86_32
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	select ARCH_CLOCKSOURCE_DATA
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	select ARCH_CLOCKSOURCE_INIT
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	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
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	select ARCH_HAS_DEBUG_VIRTUAL
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	select ARCH_HAS_DEVMEM_IS_ALLOWED
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	select ARCH_HAS_ELF_RANDOMIZE
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	select ARCH_HAS_FAST_MULTIPLIER
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	select ARCH_HAS_FILTER_PGPROT
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	select ARCH_HAS_FORTIFY_SOURCE
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	select ARCH_HAS_GCOV_PROFILE_ALL
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	select ARCH_HAS_KCOV			if X86_64
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	select ARCH_HAS_MEM_ENCRYPT
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	select ARCH_HAS_MEMBARRIER_SYNC_CORE
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	select ARCH_HAS_PMEM_API		if X86_64
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	select ARCH_HAS_PTE_DEVMAP		if X86_64
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	select ARCH_HAS_PTE_SPECIAL
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	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
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	select ARCH_HAS_UACCESS_MCSAFE		if X86_64 && X86_MCE
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	select ARCH_HAS_SET_MEMORY
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	select ARCH_HAS_SET_DIRECT_MAP
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	select ARCH_HAS_STRICT_KERNEL_RWX
	select ARCH_HAS_STRICT_MODULE_RWX
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	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
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	select ARCH_HAS_UBSAN_SANITIZE_ALL
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	select ARCH_HAVE_NMI_SAFE_CMPXCHG
	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
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	select ARCH_MIGHT_HAVE_PC_PARPORT
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	select ARCH_MIGHT_HAVE_PC_SERIO
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	select ARCH_STACKWALK
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	select ARCH_SUPPORTS_ACPI
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	select ARCH_SUPPORTS_ATOMIC_RMW
	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
	select ARCH_USE_BUILTIN_BSWAP
	select ARCH_USE_QUEUED_RWLOCKS
	select ARCH_USE_QUEUED_SPINLOCKS
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	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
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	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
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	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
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	select ARCH_WANT_HUGE_PMD_SHARE
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	select ARCH_WANTS_THP_SWAP		if X86_64
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	select BUILDTIME_TABLE_SORT
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	select CLKEVT_I8253
	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
	select CLOCKSOURCE_WATCHDOG
	select DCACHE_WORD_ACCESS
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	select EDAC_ATOMIC_SCRUB
	select EDAC_SUPPORT
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	select GENERIC_CLOCKEVENTS
	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
	select GENERIC_CLOCKEVENTS_MIN_ADJUST
	select GENERIC_CMOS_UPDATE
	select GENERIC_CPU_AUTOPROBE
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	select GENERIC_CPU_VULNERABILITIES
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	select GENERIC_EARLY_IOREMAP
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	select GENERIC_FIND_FIRST_BIT
	select GENERIC_IOMAP
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	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
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	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
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	select GENERIC_IRQ_MIGRATION		if SMP
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	select GENERIC_IRQ_PROBE
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	select GENERIC_IRQ_RESERVATION_MODE
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	select GENERIC_IRQ_SHOW
	select GENERIC_PENDING_IRQ		if SMP
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	select GENERIC_PTDUMP
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	select GENERIC_SMP_IDLE_THREAD
	select GENERIC_STRNCPY_FROM_USER
	select GENERIC_STRNLEN_USER
	select GENERIC_TIME_VSYSCALL
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	select GENERIC_GETTIMEOFDAY
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	select GENERIC_VDSO_TIME_NS
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	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
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	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
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	select HAVE_ACPI_APEI			if ACPI
	select HAVE_ACPI_APEI_NMI		if ACPI
	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
	select HAVE_ARCH_AUDITSYSCALL
	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
	select HAVE_ARCH_JUMP_LABEL
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	select HAVE_ARCH_JUMP_LABEL_RELATIVE
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	select HAVE_ARCH_KASAN			if X86_64
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	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
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	select HAVE_ARCH_KGDB
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	select HAVE_ARCH_MMAP_RND_BITS		if MMU
	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
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	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
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	select HAVE_ARCH_PREL32_RELOCATIONS
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	select HAVE_ARCH_SECCOMP_FILTER
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	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
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	select HAVE_ARCH_STACKLEAK
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	select HAVE_ARCH_TRACEHOOK
	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
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	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
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	select HAVE_ARCH_VMAP_STACK		if X86_64
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	select HAVE_ARCH_WITHIN_STACK_FRAMES
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	select HAVE_ASM_MODVERSIONS
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	select HAVE_CMPXCHG_DOUBLE
	select HAVE_CMPXCHG_LOCAL
	select HAVE_CONTEXT_TRACKING		if X86_64
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	select HAVE_COPY_THREAD_TLS
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	select HAVE_C_RECORDMCOUNT
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	select HAVE_DEBUG_KMEMLEAK
	select HAVE_DMA_CONTIGUOUS
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	select HAVE_DYNAMIC_FTRACE
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	select HAVE_DYNAMIC_FTRACE_WITH_REGS
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	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
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	select HAVE_EBPF_JIT
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	select HAVE_EFFICIENT_UNALIGNED_ACCESS
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	select HAVE_EISA
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	select HAVE_EXIT_THREAD
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	select HAVE_FAST_GUP
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	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
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	select HAVE_FTRACE_MCOUNT_RECORD
	select HAVE_FUNCTION_GRAPH_TRACER
	select HAVE_FUNCTION_TRACER
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	select HAVE_GCC_PLUGINS
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	select HAVE_HW_BREAKPOINT
	select HAVE_IDE
	select HAVE_IOREMAP_PROT
	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
	select HAVE_IRQ_TIME_ACCOUNTING
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	select HAVE_KERNEL_BZIP2
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	select HAVE_KERNEL_GZIP
	select HAVE_KERNEL_LZ4
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	select HAVE_KERNEL_LZMA
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	select HAVE_KERNEL_LZO
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	select HAVE_KERNEL_XZ
	select HAVE_KPROBES
	select HAVE_KPROBES_ON_FTRACE
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	select HAVE_FUNCTION_ERROR_INJECTION
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	select HAVE_KRETPROBES
	select HAVE_KVM
	select HAVE_LIVEPATCH			if X86_64
	select HAVE_MEMBLOCK_NODE_MAP
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	select HAVE_MIXED_BREAKPOINTS_REGS
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	select HAVE_MOD_ARCH_SPECIFIC
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	select HAVE_MOVE_PMD
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	select HAVE_NMI
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	select HAVE_OPROFILE
	select HAVE_OPTPROBES
	select HAVE_PCSPKR_PLATFORM
	select HAVE_PERF_EVENTS
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	select HAVE_PERF_EVENTS_NMI
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	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
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	select HAVE_PCI
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	select HAVE_PERF_REGS
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	select HAVE_PERF_USER_STACK_DUMP
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	select MMU_GATHER_RCU_TABLE_FREE		if PARAVIRT
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	select HAVE_REGS_AND_STACK_ACCESS_API
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	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
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	select HAVE_FUNCTION_ARG_ACCESS_API
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	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
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	select HAVE_STACK_VALIDATION		if X86_64
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	select HAVE_RSEQ
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	select HAVE_SYSCALL_TRACEPOINTS
	select HAVE_UNSTABLE_SCHED_CLOCK
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	select HAVE_USER_RETURN_NOTIFIER
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	select HAVE_GENERIC_VDSO
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	select HOTPLUG_SMT			if SMP
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	select IRQ_FORCED_THREADING
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	select NEED_SG_DMA_LENGTH
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	select PCI_DOMAINS			if PCI
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	select PCI_LOCKLESS_CONFIG		if PCI
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	select PERF_EVENTS
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	select RTC_LIB
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	select RTC_MC146818_LIB
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	select SPARSE_IRQ
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	select SRCU
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	select SYSCTL_EXCEPTION_TRACE
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	select THREAD_INFO_IN_TASK
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	select USER_STACKTRACE_SUPPORT
	select VIRT_TO_BUS
	select X86_FEATURE_NAMES		if PROC_FS
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	select PROC_PID_ARCH_STATUS		if PROC_FS
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config INSTRUCTION_DECODER
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	def_bool y
	depends on KPROBES || PERF_EVENTS || UPROBES
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config OUTPUT_FORMAT
	string
	default "elf32-i386" if X86_32
	default "elf64-x86-64" if X86_64

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config ARCH_DEFCONFIG
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	string
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	default "arch/x86/configs/i386_defconfig" if X86_32
	default "arch/x86/configs/x86_64_defconfig" if X86_64
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config LOCKDEP_SUPPORT
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	def_bool y
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config STACKTRACE_SUPPORT
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	def_bool y
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config MMU
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	def_bool y
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config ARCH_MMAP_RND_BITS_MIN
	default 28 if 64BIT
	default 8

config ARCH_MMAP_RND_BITS_MAX
	default 32 if 64BIT
	default 16

config ARCH_MMAP_RND_COMPAT_BITS_MIN
	default 8

config ARCH_MMAP_RND_COMPAT_BITS_MAX
	default 16

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config SBUS
	bool

config GENERIC_ISA_DMA
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	def_bool y
	depends on ISA_DMA_API
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config GENERIC_BUG
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	def_bool y
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	depends on BUG
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	select GENERIC_BUG_RELATIVE_POINTERS if X86_64

config GENERIC_BUG_RELATIVE_POINTERS
	bool
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config ARCH_MAY_HAVE_PC_FDC
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	def_bool y
	depends on ISA_DMA_API
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config GENERIC_CALIBRATE_DELAY
	def_bool y

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config ARCH_HAS_CPU_RELAX
	def_bool y

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config ARCH_HAS_CACHE_LINE_SIZE
	def_bool y

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config ARCH_HAS_FILTER_PGPROT
	def_bool y

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config HAVE_SETUP_PER_CPU_AREA
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	def_bool y
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config NEED_PER_CPU_EMBED_FIRST_CHUNK
	def_bool y

config NEED_PER_CPU_PAGE_FIRST_CHUNK
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	def_bool y

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config ARCH_HIBERNATION_POSSIBLE
	def_bool y

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config ARCH_SUSPEND_POSSIBLE
	def_bool y

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config ARCH_WANT_GENERAL_HUGETLB
	def_bool y

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config ZONE_DMA32
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	def_bool y if X86_64
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config AUDIT_ARCH
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	def_bool y if X86_64
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config ARCH_SUPPORTS_DEBUG_PAGEALLOC
	def_bool y

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config KASAN_SHADOW_OFFSET
	hex
	depends on KASAN
	default 0xdffffc0000000000

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config HAVE_INTEL_TXT
	def_bool y
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	depends on INTEL_IOMMU && ACPI
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config X86_32_SMP
	def_bool y
	depends on X86_32 && SMP

config X86_64_SMP
	def_bool y
	depends on X86_64 && SMP

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config X86_32_LAZY_GS
	def_bool y
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	depends on X86_32 && !STACKPROTECTOR
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config ARCH_SUPPORTS_UPROBES
	def_bool y

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config FIX_EARLYCON_MEM
	def_bool y

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config DYNAMIC_PHYSICAL_MASK
	bool

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config PGTABLE_LEVELS
	int
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	default 5 if X86_5LEVEL
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	default 4 if X86_64
	default 3 if X86_PAE
	default 2

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config CC_HAS_SANE_STACKPROTECTOR
	bool
	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
	help
	   We have to make sure stack protector is unconditionally disabled if
	   the compiler produces broken code.

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menu "Processor type and features"

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config ZONE_DMA
	bool "DMA memory allocation support" if EXPERT
	default y
	help
	  DMA memory allocation support allows devices with less than 32-bit
	  addressing to allocate within the first 16MB of address space.
	  Disable if no such devices will be used.

	  If unsure, say Y.

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config SMP
	bool "Symmetric multi-processing support"
	---help---
	  This enables support for systems with more than one CPU. If you have
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	  a system with only one CPU, say N. If you have a system with more
	  than one CPU, say Y.
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	  If you say N here, the kernel will run on uni- and multiprocessor
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	  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,
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	  uniprocessor machines. On a uniprocessor machine, the kernel
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	  will run faster if you say N here.

	  Note that if you say Y here and choose architecture "586" or
	  "Pentium" under "Processor family", the kernel will not work on 486
	  architectures. Similarly, multiprocessor kernels for the "PPro"
	  architecture may not work on all Pentium based boards.

	  People using multiprocessor machines who say Y here should also say
	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
	  Management" code will be disabled if you say Y here.

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	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
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	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
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	  <http://www.tldp.org/docs.html#howto>.

	  If you don't know what to do here, say N.

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config X86_FEATURE_NAMES
	bool "Processor feature human-readable names" if EMBEDDED
	default y
	---help---
	  This option compiles in a table of x86 feature bits and corresponding
	  names.  This is required to support /proc/cpuinfo and a few kernel
	  messages.  You can disable this to save space, at the expense of
	  making those few kernel messages show numeric feature bits instead.

	  If in doubt, say Y.

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config X86_X2APIC
	bool "Support x2apic"
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	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
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	---help---
	  This enables x2apic support on CPUs that have this feature.

	  This allows 32-bit apic IDs (so it can support very large systems),
	  and accesses the local apic via MSRs not via mmio.

	  If you don't know what to do here, say N.

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config X86_MPPARSE
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	bool "Enable MPS table" if ACPI || SFI
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	default y
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	depends on X86_LOCAL_APIC
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	---help---
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	  For old smp systems that do not have proper acpi support. Newer systems
	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it

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config GOLDFISH
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	def_bool y
	depends on X86_GOLDFISH
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config RETPOLINE
	bool "Avoid speculative indirect branches in kernel"
	default y
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	select STACK_VALIDATION if HAVE_STACK_VALIDATION
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	help
	  Compile kernel with the retpoline compiler options to guard against
	  kernel-to-user data leaks by avoiding speculative indirect
	  branches. Requires a compiler with -mindirect-branch=thunk-extern
	  support for full protection. The kernel may run slower.

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config X86_CPU_RESCTRL
	bool "x86 CPU resource control support"
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	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
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	select KERNFS
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	select PROC_CPU_RESCTRL		if PROC_FS
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	help
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	  Enable x86 CPU resource control support.
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	  Provide support for the allocation and monitoring of system resources
	  usage by the CPU.

	  Intel calls this Intel Resource Director Technology
	  (Intel(R) RDT). More information about RDT can be found in the
	  Intel x86 Architecture Software Developer Manual.

	  AMD calls this AMD Platform Quality of Service (AMD QoS).
	  More information about AMD QoS can be found in the AMD64 Technology
	  Platform Quality of Service Extensions manual.
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	  Say N if unsure.

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if X86_32
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config X86_BIGSMP
	bool "Support for big SMP systems with more than 8 CPUs"
	depends on SMP
	---help---
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	  This option is needed for the systems that have more than 8 CPUs.
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config X86_EXTENDED_PLATFORM
	bool "Support for extended (non-PC) x86 platforms"
	default y
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	---help---
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	  If you disable this option then the kernel will only support
	  standard PC platforms. (which covers the vast majority of
	  systems out there.)

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	  If you enable this option then you'll be able to select support
	  for the following (non-PC) 32 bit x86 platforms:
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		Goldfish (Android emulator)
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		AMD Elan
		RDC R-321x SoC
		SGI 320/540 (Visual Workstation)
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		STA2X11-based (e.g. Northville)
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		Moorestown MID devices
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	  If you have one of these systems, or if you want to build a
	  generic distribution kernel, say Y here - otherwise say N.
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endif
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if X86_64
config X86_EXTENDED_PLATFORM
	bool "Support for extended (non-PC) x86 platforms"
	default y
	---help---
	  If you disable this option then the kernel will only support
	  standard PC platforms. (which covers the vast majority of
	  systems out there.)

	  If you enable this option then you'll be able to select support
	  for the following (non-PC) 64 bit x86 platforms:
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		Numascale NumaChip
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		ScaleMP vSMP
		SGI Ultraviolet

	  If you have one of these systems, or if you want to build a
	  generic distribution kernel, say Y here - otherwise say N.
endif
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# This is an alphabetically sorted list of 64 bit extended platforms
# Please maintain the alphabetic order if and when there are additions
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config X86_NUMACHIP
	bool "Numascale NumaChip"
	depends on X86_64
	depends on X86_EXTENDED_PLATFORM
	depends on NUMA
	depends on SMP
	depends on X86_X2APIC
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	depends on PCI_MMCONFIG
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	---help---
	  Adds support for Numascale NumaChip large-SMP systems. Needed to
	  enable more than ~168 cores.
	  If you don't have one of these, you should say N here.
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config X86_VSMP
	bool "ScaleMP vSMP"
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	select HYPERVISOR_GUEST
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	select PARAVIRT
	depends on X86_64 && PCI
	depends on X86_EXTENDED_PLATFORM
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	depends on SMP
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	---help---
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	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
	  supposed to run on these EM64T-based machines.  Only choose this option
	  if you have one of these machines.
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config X86_UV
	bool "SGI Ultraviolet"
	depends on X86_64
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	depends on X86_EXTENDED_PLATFORM
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	depends on NUMA
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	depends on EFI
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	depends on X86_X2APIC
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	depends on PCI
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	---help---
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	  This option is needed in order to support SGI Ultraviolet systems.
	  If you don't have one of these, you should say N here.

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# Following is an alphabetically sorted list of 32 bit extended platforms
# Please maintain the alphabetic order if and when there are additions
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config X86_GOLDFISH
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	bool "Goldfish (Virtual Platform)"
	depends on X86_EXTENDED_PLATFORM
	---help---
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	 Enable support for the Goldfish virtual platform used primarily
	 for Android development. Unless you are building for the Android
	 Goldfish emulator say N here.

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config X86_INTEL_CE
	bool "CE4100 TV platform"
	depends on PCI
	depends on PCI_GODIRECT
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	depends on X86_IO_APIC
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	depends on X86_32
	depends on X86_EXTENDED_PLATFORM
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	select X86_REBOOTFIXUPS
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	select OF
	select OF_EARLY_FLATTREE
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	---help---
	  Select for the Intel CE media processor (CE4100) SOC.
	  This option compiles in support for the CE4100 SOC for settop
	  boxes and media devices.

590
config X86_INTEL_MID
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	bool "Intel MID platform support"
	depends on X86_EXTENDED_PLATFORM
593
	depends on X86_PLATFORM_DEVICES
594
	depends on PCI
595
	depends on X86_64 || (PCI_GOANY && X86_32)
596
	depends on X86_IO_APIC
597
	select SFI
598
	select I2C
599
	select DW_APB_TIMER
600 601
	select APB_TIMER
	select INTEL_SCU_IPC
602
	select MFD_INTEL_MSIC
603
	---help---
604 605 606
	  Select to build a kernel capable of supporting Intel MID (Mobile
	  Internet Device) platform systems which do not have the PCI legacy
	  interfaces. If you are building for a PC class system say N here.
607

608 609
	  Intel MID platforms are based on an Intel processor and chipset which
	  consume less power than most of the x86 derivatives.
610

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config X86_INTEL_QUARK
	bool "Intel Quark platform support"
	depends on X86_32
	depends on X86_EXTENDED_PLATFORM
	depends on X86_PLATFORM_DEVICES
	depends on X86_TSC
	depends on PCI
	depends on PCI_GOANY
	depends on X86_IO_APIC
	select IOSF_MBI
	select INTEL_IMR
622
	select COMMON_CLK
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	---help---
	  Select to include support for Quark X1000 SoC.
	  Say Y here if you have a Quark based system such as the Arduino
	  compatible Intel Galileo.

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config X86_INTEL_LPSS
	bool "Intel Low Power Subsystem Support"
630
	depends on X86 && ACPI && PCI
631
	select COMMON_CLK
632
	select PINCTRL
633
	select IOSF_MBI
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	---help---
	  Select to build support for Intel Low Power Subsystem such as
	  found on Intel Lynxpoint PCH. Selecting this option enables
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	  things like clock tree (common clock framework) and pincontrol
	  which are needed by the LPSS peripheral drivers.
639

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config X86_AMD_PLATFORM_DEVICE
	bool "AMD ACPI2Platform devices support"
	depends on ACPI
	select COMMON_CLK
	select PINCTRL
	---help---
	  Select to interpret AMD specific ACPI device to platform device
	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
	  implemented under PINCTRL subsystem.

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config IOSF_MBI
	tristate "Intel SoC IOSF Sideband support for SoC platforms"
	depends on PCI
	---help---
	  This option enables sideband register access support for Intel SoC
	  platforms. On these platforms the IOSF sideband is used in lieu of
	  MSR's for some register accesses, mostly but not limited to thermal
	  and power. Drivers may query the availability of this device to
	  determine if they need the sideband in order to work on these
	  platforms. The sideband is available on the following SoC products.
	  This list is not meant to be exclusive.
	   - BayTrail
	   - Braswell
	   - Quark

	  You should say Y if you are running a kernel on one of these SoC's.

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config IOSF_MBI_DEBUG
	bool "Enable IOSF sideband access through debugfs"
	depends on IOSF_MBI && DEBUG_FS
	---help---
	  Select this option to expose the IOSF sideband access registers (MCR,
	  MDR, MCRX) through debugfs to write and read register information from
	  different units on the SoC. This is most useful for obtaining device
	  state information for debug and analysis. As this is a general access
	  mechanism, users of this option would have specific knowledge of the
	  device they want to access.

	  If you don't require the option or are in doubt, say N.

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config X86_RDC321X
	bool "RDC R-321x SoC"
683
	depends on X86_32
684 685 686 687 688 689 690 691
	depends on X86_EXTENDED_PLATFORM
	select M486
	select X86_REBOOTFIXUPS
	---help---
	  This option is needed for RDC R-321x system-on-chip, also known
	  as R-8610-(G).
	  If you don't have one of these chips, you should say N here.

692
config X86_32_NON_STANDARD
693 694
	bool "Support non-standard 32-bit SMP architectures"
	depends on X86_32 && SMP
695
	depends on X86_EXTENDED_PLATFORM
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	---help---
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	  This option compiles in the bigsmp and STA2X11 default
	  subarchitectures.  It is intended for a generic binary
	  kernel. If you select them all, kernel will probe it one by
	  one and will fallback to default.
701

702
# Alphabetically sorted list of Non standard 32 bit platforms
703

704
config X86_SUPPORTS_MEMORY_FAILURE
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	def_bool y
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	# MCE code calls memory_failure():
	depends on X86_MCE
	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
	depends on X86_64 || !SPARSEMEM
	select ARCH_SUPPORTS_MEMORY_FAILURE

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config STA2X11
	bool "STA2X11 Companion Chip Support"
	depends on X86_32_NON_STANDARD && PCI
	select SWIOTLB
	select MFD_STA2X11
718
	select GPIOLIB
719 720 721 722 723 724 725
	---help---
	  This adds support for boards based on the STA2X11 IO-Hub,
	  a.k.a. "ConneXt". The chip is used in place of the standard
	  PC chipset, so all "standard" peripherals are missing. If this
	  option is selected the kernel will still be able to boot on
	  standard PC machines.

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config X86_32_IRIS
	tristate "Eurobraille/Iris poweroff module"
	depends on X86_32
	---help---
	  The Iris machines from EuroBraille do not have APM or ACPI support
	  to shut themselves down properly.  A special I/O sequence is
	  needed to do so, which is what this module does at
	  kernel shutdown.

	  This is only for Iris machines from EuroBraille.

	  If unused, say N.

739
config SCHED_OMIT_FRAME_POINTER
740 741
	def_bool y
	prompt "Single-depth WCHAN output"
742
	depends on X86
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	---help---
744 745 746 747 748 749 750
	  Calculate simpler /proc/<PID>/wchan values. If this option
	  is disabled then wchan values will recurse back to the
	  caller function. This provides more accurate wchan values,
	  at the expense of slightly more scheduling overhead.

	  If in doubt, say "Y".

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menuconfig HYPERVISOR_GUEST
	bool "Linux guest support"
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	---help---
754 755 756
	  Say Y here to enable options for running Linux under various hyper-
	  visors. This option enables basic hypervisor detection and platform
	  setup.
757

758 759
	  If you say N, all options in this submenu will be skipped and
	  disabled, and Linux guest support won't be built in.
760

761
if HYPERVISOR_GUEST
762

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config PARAVIRT
	bool "Enable paravirtualization code"
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	---help---
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	  This changes the kernel so it can modify itself when it is run
	  under a hypervisor, potentially improving performance significantly
	  over full virtualization.  However, when run without a hypervisor
	  the kernel is theoretically slower and slightly larger.

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config PARAVIRT_XXL
	bool

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config PARAVIRT_DEBUG
	bool "paravirt-ops debugging"
	depends on PARAVIRT && DEBUG_KERNEL
	---help---
	  Enable to debug paravirt_ops internals.  Specifically, BUG if
	  a paravirt_op is missing when it is called.

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config PARAVIRT_SPINLOCKS
	bool "Paravirtualization layer for spinlocks"
783
	depends on PARAVIRT && SMP
784 785 786 787 788
	---help---
	  Paravirtualized spinlocks allow a pvops backend to replace the
	  spinlock implementation with something virtualization-friendly
	  (for example, block the virtual CPU rather than spinning).

789 790
	  It has a minimal impact on native kernels and gives a nice performance
	  benefit on paravirtualized KVM / Xen kernels.
791

792
	  If you are unsure how to answer this question, answer Y.
793

794 795 796
config X86_HV_CALLBACK_VECTOR
	def_bool n

797
source "arch/x86/xen/Kconfig"
798

799 800 801 802
config KVM_GUEST
	bool "KVM Guest support (including kvmclock)"
	depends on PARAVIRT
	select PARAVIRT_CLOCK
803
	select ARCH_CPUIDLE_HALTPOLL
804
	default y
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	---help---
806 807 808 809 810
	  This option enables various optimizations for running under the KVM
	  hypervisor. It includes a paravirtualized clock, so that instead
	  of relying on a PIT (or probably other) emulation by the
	  underlying device model, the host provides the guest with
	  timing infrastructure such as time of day, and system time
811

812
config ARCH_CPUIDLE_HALTPOLL
813 814 815
	def_bool n
	prompt "Disable host haltpoll when loading haltpoll driver"
	help
816 817
	  If virtualized under KVM, disable host haltpoll.

818 819 820 821 822 823
config PVH
	bool "Support for running PVH guests"
	---help---
	  This option enables the PVH entry point for guest virtual machines
	  as specified in the x86/HVM direct boot ABI.

824 825 826 827 828 829 830 831
config KVM_DEBUG_FS
	bool "Enable debug information for KVM Guests in debugfs"
	depends on KVM_GUEST && DEBUG_FS
	---help---
	  This option enables collection of various statistics for KVM guest.
	  Statistics are displayed in debugfs filesystem. Enabling this option
	  may incur significant overhead.

832 833 834
config PARAVIRT_TIME_ACCOUNTING
	bool "Paravirtual steal time accounting"
	depends on PARAVIRT
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	---help---
836 837 838 839 840 841 842 843 844
	  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 PARAVIRT_CLOCK
	bool
845

846 847
config JAILHOUSE_GUEST
	bool "Jailhouse non-root cell support"
848
	depends on X86_64 && PCI
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	select X86_PM_TIMER
850 851 852 853 854
	---help---
	  This option allows to run Linux as guest in a Jailhouse non-root
	  cell. You can leave this option disabled if you only want to start
	  Jailhouse and run Linux afterwards in the root cell.

855 856 857
config ACRN_GUEST
	bool "ACRN Guest support"
	depends on X86_64
858
	select X86_HV_CALLBACK_VECTOR
859 860 861 862 863 864 865
	help
	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
	  a flexible, lightweight reference open-source hypervisor, built with
	  real-time and safety-criticality in mind. It is built for embedded
	  IOT with small footprint and real-time features. More details can be
	  found in https://projectacrn.org/.

866
endif #HYPERVISOR_GUEST
867

868 869 870
source "arch/x86/Kconfig.cpu"

config HPET_TIMER
871
	def_bool X86_64
872
	prompt "HPET Timer Support" if X86_32
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	---help---
	  Use the IA-PC HPET (High Precision Event Timer) to manage
	  time in preference to the PIT and RTC, if a HPET is
	  present.
	  HPET is the next generation timer replacing legacy 8254s.
	  The HPET provides a stable time base on SMP
	  systems, unlike the TSC, but it is more expensive to access,
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	  as it is off-chip.  The interface used is documented
	  in the HPET spec, revision 1.
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	  You can safely choose Y here.  However, HPET will only be
	  activated if the platform and the BIOS support this feature.
	  Otherwise the 8254 will be used for timing services.
886

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	  Choose N to continue using the legacy 8254 timer.
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config HPET_EMULATE_RTC
890
	def_bool y
891
	depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
892

893
config APB_TIMER
894 895 896 897 898 899 900 901 902 903
	def_bool y if X86_INTEL_MID
	prompt "Intel MID APB Timer Support" if X86_INTEL_MID
	select DW_APB_TIMER
	depends on X86_INTEL_MID && SFI
	help
	 APB timer is the replacement for 8254, HPET on X86 MID platforms.
	 The APBT provides a stable time base on SMP
	 systems, unlike the TSC, but it is more expensive to access,
	 as it is off-chip. APB timers are always running regardless of CPU
	 C states, they are used as per CPU clockevent device when possible.
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905
# Mark as expert because too many people got it wrong.
906
# The code disables itself when not needed.
907 908
config DMI
	default y
909
	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
910
	bool "Enable DMI scanning" if EXPERT
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	---help---
912 913 914 915 916
	  Enabled scanning of DMI to identify machine quirks. Say Y
	  here unless you have verified that your setup is not
	  affected by entries in the DMI blacklist. Required by PNP
	  BIOS code.

917
config GART_IOMMU
918
	bool "Old AMD GART IOMMU support"
919
	select IOMMU_HELPER
920
	select SWIOTLB
921
	depends on X86_64 && PCI && AMD_NB
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	---help---
923 924 925 926 927 928 929 930 931 932 933 934 935 936 937
	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
	  GART based hardware IOMMUs.

	  The GART supports full DMA access for devices with 32-bit access
	  limitations, on systems with more than 3 GB. This is usually needed
	  for USB, sound, many IDE/SATA chipsets and some other devices.

	  Newer systems typically have a modern AMD IOMMU, supported via
	  the CONFIG_AMD_IOMMU=y config option.

	  In normal configurations this driver is only active when needed:
	  there's more than 3 GB of memory and the system contains a
	  32-bit limited device.

	  If unsure, say Y.
938

939
config MAXSMP
940
	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
941
	depends on X86_64 && SMP && DEBUG_KERNEL
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	select CPUMASK_OFFSTACK
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	---help---
944
	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
945
	  If unsure, say N.
946

947 948 949 950 951 952 953 954 955 956 957 958 959 960 961
#
# The maximum number of CPUs supported:
#
# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
# and which can be configured interactively in the
# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
#
# The ranges are different on 32-bit and 64-bit kernels, depending on
# hardware capabilities and scalability features of the kernel.
#
# ( If MAXSMP is enabled we just use the highest possible value and disable
#   interactive configuration. )
#

config NR_CPUS_RANGE_BEGIN
962
	int
963 964 965
	default NR_CPUS_RANGE_END if MAXSMP
	default    1 if !SMP
	default    2
966

967
config NR_CPUS_RANGE_END
968
	int
969 970 971 972
	depends on X86_32
	default   64 if  SMP &&  X86_BIGSMP
	default    8 if  SMP && !X86_BIGSMP
	default    1 if !SMP
973

974
config NR_CPUS_RANGE_END
975
	int
976
	depends on X86_64
977 978
	default 8192 if  SMP && CPUMASK_OFFSTACK
	default  512 if  SMP && !CPUMASK_OFFSTACK
979
	default    1 if !SMP
980

981
config NR_CPUS_DEFAULT
982 983
	int
	depends on X86_32
984 985 986
	default   32 if  X86_BIGSMP
	default    8 if  SMP
	default    1 if !SMP
987

988
config NR_CPUS_DEFAULT
989 990
	int
	depends on X86_64
991 992 993
	default 8192 if  MAXSMP
	default   64 if  SMP
	default    1 if !SMP
994

995
config NR_CPUS
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	int "Maximum number of CPUs" if SMP && !MAXSMP
997 998
	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
	default NR_CPUS_DEFAULT
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	---help---
1000
	  This allows you to specify the maximum number of CPUs which this
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	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1002
	  supported value is 8192, otherwise the maximum value is 512.  The
1003 1004
	  minimum value which makes sense is 2.

1005 1006
	  This is purely to save memory: each supported CPU adds about 8KB
	  to the kernel image.
1007 1008

config SCHED_SMT
1009
	def_bool y if SMP
1010 1011

config SCHED_MC
1012 1013
	def_bool y
	prompt "Multi-core scheduler support"
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	depends on SMP
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	---help---
1016 1017 1018 1019
	  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.

1020 1021
config SCHED_MC_PRIO
	bool "CPU core priorities scheduler support"
1022 1023 1024
	depends on SCHED_MC && CPU_SUP_INTEL
	select X86_INTEL_PSTATE
	select CPU_FREQ
1025
	default y
1026
	---help---
1027 1028 1029 1030
	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
	  core ordering determined at manufacturing time, which allows
	  certain cores to reach higher turbo frequencies (when running
	  single threaded workloads) than others.
1031

1032 1033 1034 1035
	  Enabling this kernel feature teaches the scheduler about
	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
	  scheduler's CPU selection logic accordingly, so that higher
	  overall system performance can be achieved.
1036

1037
	  This feature will have no effect on CPUs without this feature.
1038

1039
	  If unsure say Y here.
1040

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config UP_LATE_INIT
1042 1043
	def_bool y
	depends on !SMP && X86_LOCAL_APIC
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1045
config X86_UP_APIC
1046 1047
	bool "Local APIC support on uniprocessors" if !PCI_MSI
	default PCI_MSI
1048
	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
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	---help---
1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
	  A local APIC (Advanced Programmable Interrupt Controller) is an
	  integrated interrupt controller in the CPU. If you have a single-CPU
	  system which has a processor with a local APIC, you can say Y here to
	  enable and use it. If you say Y here even though your machine doesn't
	  have a local APIC, then the kernel will still run with no slowdown at
	  all. The local APIC supports CPU-generated self-interrupts (timer,
	  performance counters), and the NMI watchdog which detects hard
	  lockups.

config X86_UP_IOAPIC
	bool "IO-APIC support on uniprocessors"
	depends on X86_UP_APIC
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	---help---
1063 1064 1065 1066 1067 1068 1069 1070 1071
	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
	  SMP-capable replacement for PC-style interrupt controllers. Most
	  SMP systems and many recent uniprocessor systems have one.

	  If you have a single-CPU system with an IO-APIC, you can say Y here
	  to use it. If you say Y here even though your machine doesn't have
	  an IO-APIC, then the kernel will still run with no slowdown at all.

config X86_LOCAL_APIC
1072
	def_bool y
1073
	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1074
	select IRQ_DOMAIN_HIERARCHY
1075
	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1076 1077

config X86_IO_APIC
1078 1079
	def_bool y
	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1080

1081 1082 1083
config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
	bool "Reroute for broken boot IRQs"
	depends on X86_IO_APIC
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	---help---
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103
	  This option enables a workaround that fixes a source of
	  spurious interrupts. This is recommended when threaded
	  interrupt handling is used on systems where the generation of
	  superfluous "boot interrupts" cannot be disabled.

	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
	  kernel does during interrupt handling). On chipsets where this
	  boot IRQ generation cannot be disabled, this workaround keeps
	  the original IRQ line masked so that only the equivalent "boot
	  IRQ" is delivered to the CPUs. The workaround also tells the
	  kernel to set up the IRQ handler on the boot IRQ line. In this
	  way only one interrupt is delivered to the kernel. Otherwise
	  the spurious second interrupt may cause the kernel to bring
	  down (vital) interrupt lines.

	  Only affects "broken" chipsets. Interrupt sharing may be
	  increased on these systems.

1104
config X86_MCE
1105
	bool "Machine Check / overheating reporting"
1106
	select GENERIC_ALLOCATOR
1107
	default y
1108
	---help---
1109 1110
	  Machine Check support allows the processor to notify the
	  kernel if it detects a problem (e.g. overheating, data corruption).
1111
	  The action the kernel takes depends on the severity of the problem,
1112
	  ranging from warning messages to halting the machine.
1113

1114 1115 1116 1117 1118 1119 1120 1121
config X86_MCELOG_LEGACY
	bool "Support for deprecated /dev/mcelog character device"
	depends on X86_MCE
	---help---
	  Enable support for /dev/mcelog which is needed by the old mcelog
	  userspace logging daemon. Consider switching to the new generation
	  rasdaemon solution.

1122
config X86_MCE_INTEL
1123 1124
	def_bool y
	prompt "Intel MCE features"
1125
	depends on X86_MCE && X86_LOCAL_APIC
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	---help---
1127 1128 1129 1130
	   Additional support for intel specific MCE features such as
	   the thermal monitor.

config X86_MCE_AMD
1131 1132
	def_bool y
	prompt "AMD MCE features"
1133
	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
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	---help---
1135 1136 1137
	   Additional support for AMD specific MCE features such as
	   the DRAM Error Threshold.

1138
config X86_ANCIENT_MCE
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	bool "Support for old Pentium 5 / WinChip machine checks"
1140
	depends on X86_32 && X86_MCE
1141 1142
	---help---
	  Include support for machine check handling on old Pentium 5 or WinChip
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	  systems. These typically need to be enabled explicitly on the command
1144
	  line.
1145

1146 1147
config X86_MCE_THRESHOLD
	depends on X86_MCE_AMD || X86_MCE_INTEL
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	def_bool y
1149

1150
config X86_MCE_INJECT
1151
	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1152 1153 1154 1155 1156 1157
	tristate "Machine check injector support"
	---help---
	  Provide support for injecting machine checks for testing purposes.
	  If you don't know what a machine check is and you don't do kernel
	  QA it is safe to say n.

1158 1159
config X86_THERMAL_VECTOR
	def_bool y
1160
	depends on X86_MCE_INTEL
1161

1162
source "arch/x86/events/Kconfig"
1163

1164
config X86_LEGACY_VM86
1165
	bool "Legacy VM86 support"
1166
	depends on X86_32
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	---help---
1168 1169 1170 1171 1172 1173 1174 1175
	  This option allows user programs to put the CPU into V8086
	  mode, which is an 80286-era approximation of 16-bit real mode.

	  Some very old versions of X and/or vbetool require this option
	  for user mode setting.  Similarly, DOSEMU will use it if
	  available to accelerate real mode DOS programs.  However, any
	  recent version of DOSEMU, X, or vbetool should be fully
	  functional even without kernel VM86 support, as they will all
1176 1177 1178 1179
	  fall back to software emulation. Nevertheless, if you are using
	  a 16-bit DOS program where 16-bit performance matters, vm86
	  mode might be faster than emulation and you might want to
	  enable this option.
1180

1181 1182 1183 1184
	  Note that any app that works on a 64-bit kernel is unlikely to
	  need this option, as 64-bit kernels don't, and can't, support
	  V8086 mode. This option is also unrelated to 16-bit protected
	  mode and is not needed to run most 16-bit programs under Wine.
1185

1186 1187
	  Enabling this option increases the complexity of the kernel
	  and slows down exception handling a tiny bit.
1188

1189
	  If unsure, say N here.
1190 1191

config VM86
1192 1193
	bool
	default X86_LEGACY_VM86
1194 1195 1196 1197

config X86_16BIT
	bool "Enable support for 16-bit segments" if EXPERT
	default y
1198
	depends on MODIFY_LDT_SYSCALL
1199 1200 1201 1202 1203 1204 1205 1206 1207
	---help---
	  This option is required by programs like Wine to run 16-bit
	  protected mode legacy code on x86 processors.  Disabling
	  this option saves about 300 bytes on i386, or around 6K text
	  plus 16K runtime memory on x86-64,

config X86_ESPFIX32
	def_bool y
	depends on X86_16BIT && X86_32
1208

1209 1210
config X86_ESPFIX64
	def_bool y
1211
	depends on X86_16BIT && X86_64
1212

1213
config X86_VSYSCALL_EMULATION
1214 1215 1216 1217
	bool "Enable vsyscall emulation" if EXPERT
	default y
	depends on X86_64
	---help---
1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230
	 This enables emulation of the legacy vsyscall page.  Disabling
	 it is roughly equivalent to booting with vsyscall=none, except
	 that it will also disable the helpful warning if a program
	 tries to use a vsyscall.  With this option set to N, offending
	 programs will just segfault, citing addresses of the form
	 0xffffffffff600?00.

	 This option is required by many programs built before 2013, and
	 care should be used even with newer programs if set to N.

	 Disabling this option saves about 7K of kernel size and
	 possibly 4K of additional runtime pagetable memory.

1231 1232
config X86_IOPL_IOPERM
	bool "IOPERM and IOPL Emulation"
1233
	default y
1234
	---help---
1235 1236 1237
	  This enables the ioperm() and iopl() syscalls which are necessary
	  for legacy applications.

1238 1239 1240 1241 1242 1243 1244 1245
	  Legacy IOPL support is an overbroad mechanism which allows user
	  space aside of accessing all 65536 I/O ports also to disable
	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
	  capabilities and permission from potentially active security
	  modules.

	  The emulation restricts the functionality of the syscall to
	  only allowing the full range I/O port access, but prevents the
1246 1247
	  ability to disable interrupts from user space which would be
	  granted if the hardware IOPL mechanism would be used.
1248

1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265
config TOSHIBA
	tristate "Toshiba Laptop support"
	depends on X86_32
	---help---
	  This adds a driver to safely access the System Management Mode of
	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
	  not work on models with a Phoenix BIOS. The System Management Mode
	  is used to set the BIOS and power saving options on Toshiba portables.

	  For information on utilities to make use of this driver see the
	  Toshiba Linux utilities web site at:
	  <http://www.buzzard.org.uk/toshiba/>.

	  Say Y if you intend to run this kernel on a Toshiba portable.
	  Say N otherwise.

config I8K
1266
	tristate "Dell i8k legacy laptop support"
1267
	select HWMON
1268
	select SENSORS_DELL_SMM
1269
	---help---
1270 1271 1272 1273 1274 1275 1276 1277 1278
	  This option enables legacy /proc/i8k userspace interface in hwmon
	  dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
	  temperature and allows controlling fan speeds of Dell laptops via
	  System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
	  it reports also power and hotkey status. For fan speed control is
	  needed userspace package i8kutils.

	  Say Y if you intend to run this kernel on old Dell laptops or want to
	  use userspace package i8kutils.
1279 1280 1281
	  Say N otherwise.

config X86_REBOOTFIXUPS
1282 1283
	bool "Enable X86 board specific fixups for reboot"
	depends on X86_32
1284 1285 1286 1287 1288 1289 1290 1291
	---help---
	  This enables chipset and/or board specific fixups to be done
	  in order to get reboot to work correctly. This is only needed on
	  some combinations of hardware and BIOS. The symptom, for which
	  this config is intended, is when reboot ends with a stalled/hung
	  system.

	  Currently, the only fixup is for the Geode machines using
1292
	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1293 1294 1295 1296 1297 1298

	  Say Y if you want to enable the fixup. Currently, it's safe to
	  enable this option even if you don't need it.
	  Say N otherwise.

config MICROCODE
1299 1300
	bool "CPU microcode loading support"
	default y
1301
	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1302 1303 1304
	select FW_LOADER
	---help---
	  If you say Y here, you will be able to update the microcode on
1305 1306 1307 1308 1309 1310 1311
	  Intel and AMD processors. The Intel support is for the IA32 family,
	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
	  AMD support is for families 0x10 and later. You will obviously need
	  the actual microcode binary data itself which is not shipped with
	  the Linux kernel.

	  The preferred method to load microcode from a detached initrd is described
1312
	  in Documentation/x86/microcode.rst. For that you need to enable
1313 1314 1315
	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
	  initrd for microcode blobs.

1316 1317 1318
	  In addition, you can build the microcode into the kernel. For that you
	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
	  config option.
1319

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config MICROCODE_INTEL
1321
	bool "Intel microcode loading support"
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1322 1323 1324 1325 1326 1327 1328
	depends on MICROCODE
	default MICROCODE
	select FW_LOADER
	---help---
	  This options enables microcode patch loading support for Intel
	  processors.

1329 1330 1331
	  For the current Intel microcode data package go to
	  <https://downloadcenter.intel.com> and search for
	  'Linux Processor Microcode Data File'.
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1332

1333
config MICROCODE_AMD
1334
	bool "AMD microcode loading support"
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1335 1336 1337 1338 1339
	depends on MICROCODE
	select FW_LOADER
	---help---
	  If you select this option, microcode patch loading support for AMD
	  processors will be enabled.
1340

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1341
config MICROCODE_OLD_INTERFACE
1342 1343
	bool "Ancient loading interface (DEPRECATED)"
	default n
1344
	depends on MICROCODE
1345 1346 1347 1348 1349 1350
	---help---
	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
	  which was used by userspace tools like iucode_tool and microcode.ctl.
	  It is inadequate because it runs too late to be able to properly
	  load microcode on a machine and it needs special tools. Instead, you
	  should've switched to the early loading method with the initrd or
1351
	  builtin microcode by now: Documentation/x86/microcode.rst
1352 1353 1354

config X86_MSR
	tristate "/dev/cpu/*/msr - Model-specific register support"
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	---help---
1356 1357 1358 1359 1360 1361 1362 1363
	  This device gives privileged processes access to the x86
	  Model-Specific Registers (MSRs).  It is a character device with
	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
	  MSR accesses are directed to a specific CPU on multi-processor
	  systems.

config X86_CPUID
	tristate "/dev/cpu/*/cpuid - CPU information support"
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	---help---
1365 1366 1367 1368 1369 1370 1371
	  This device gives processes access to the x86 CPUID instruction to
	  be executed on a specific processor.  It is a character device
	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
	  /dev/cpu/31/cpuid.

choice
	prompt "High Memory Support"
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	default HIGHMEM4G
1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412
	depends on X86_32

config NOHIGHMEM
	bool "off"
	---help---
	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
	  However, the address space of 32-bit x86 processors is only 4
	  Gigabytes large. That means that, if you have a large amount of
	  physical memory, not all of it can be "permanently mapped" by the
	  kernel. The physical memory that's not permanently mapped is called
	  "high memory".

	  If you are compiling a kernel which will never run on a machine with
	  more than 1 Gigabyte total physical RAM, answer "off" here (default
	  choice and suitable for most users). This will result in a "3GB/1GB"
	  split: 3GB are mapped so that each process sees a 3GB virtual memory
	  space and the remaining part of the 4GB virtual memory space is used
	  by the kernel to permanently map as much physical memory as
	  possible.

	  If the machine has between 1 and 4 Gigabytes physical RAM, then
	  answer "4GB" here.

	  If more than 4 Gigabytes is used then answer "64GB" here. This
	  selection turns Intel PAE (Physical Address Extension) mode on.
	  PAE implements 3-level paging on IA32 processors. PAE is fully
	  supported by Linux, PAE mode is implemented on all recent Intel
	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
	  then the kernel will not boot on CPUs that don't support PAE!

	  The actual amount of total physical memory will either be
	  auto detected or can be forced by using a kernel command line option
	  such as "mem=256M". (Try "man bootparam" or see the documentation of
	  your boot loader (lilo or loadlin) about how to pass options to the
	  kernel at boot time.)

	  If unsure, say "off".

config HIGHMEM4G
	bool "4GB"
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	---help---
1414 1415 1416 1417 1418
	  Select this if you have a 32-bit processor and between 1 and 4
	  gigabytes of physical RAM.

config HIGHMEM64G
	bool "64GB"
1419
	depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1420
	select X86_PAE
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1421
	---help---
1422 1423 1424 1425 1426 1427
	  Select this if you have a 32-bit processor and more than 4
	  gigabytes of physical RAM.

endchoice

choice
1428
	prompt "Memory split" if EXPERT
1429 1430
	default VMSPLIT_3G
	depends on X86_32
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1431
	---help---
1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470
	  Select the desired split between kernel and user memory.

	  If the address range available to the kernel is less than the
	  physical memory installed, the remaining memory will be available
	  as "high memory". Accessing high memory is a little more costly
	  than low memory, as it needs to be mapped into the kernel first.
	  Note that increasing the kernel address space limits the range
	  available to user programs, making the address space there
	  tighter.  Selecting anything other than the default 3G/1G split
	  will also likely make your kernel incompatible with binary-only
	  kernel modules.

	  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 !X86_PAE
		bool "3G/1G user/kernel split (for full 1G low memory)"
	config VMSPLIT_2G
		bool "2G/2G user/kernel split"
	config VMSPLIT_2G_OPT
		depends on !X86_PAE
		bool "2G/2G user/kernel split (for full 2G low memory)"
	config VMSPLIT_1G
		bool "1G/3G user/kernel split"
endchoice

config PAGE_OFFSET
	hex
	default 0xB0000000 if VMSPLIT_3G_OPT
	default 0x80000000 if VMSPLIT_2G
	default 0x78000000 if VMSPLIT_2G_OPT
	default 0x40000000 if VMSPLIT_1G
	default 0xC0000000
	depends on X86_32

config HIGHMEM
1471
	def_bool y
1472 1473 1474
	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)

config X86_PAE
1475
	bool "PAE (Physical Address Extension) Support"
1476
	depends on X86_32 && !HIGHMEM4G
1477
	select PHYS_ADDR_T_64BIT
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1478
	select SWIOTLB
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1479
	---help---
1480 1481 1482 1483 1484
	  PAE is required for NX support, and furthermore enables
	  larger swapspace support for non-overcommit purposes. It
	  has the cost of more pagetable lookup overhead, and also
	  consumes more pagetable space per process.

1485 1486
config X86_5LEVEL
	bool "Enable 5-level page tables support"
1487
	default y
1488
	select DYNAMIC_MEMORY_LAYOUT
1489
	select SPARSEMEM_VMEMMAP
1490 1491 1492 1493 1494 1495 1496 1497
	depends on X86_64
	---help---
	  5-level paging enables access to larger address space:
	  upto 128 PiB of virtual address space and 4 PiB of
	  physical address space.

	  It will be supported by future Intel CPUs.

1498 1499
	  A kernel with the option enabled can be booted on machines that
	  support 4- or 5-level paging.
1500

1501
	  See Documentation/x86/x86_64/5level-paging.rst for more
1502 1503 1504 1505
	  information.

	  Say N if unsure.

1506
config X86_DIRECT_GBPAGES
1507
	def_bool y
1508
	depends on X86_64
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1509
	---help---
1510 1511 1512 1513
	  Certain kernel features effectively disable kernel
	  linear 1 GB mappings (even if the CPU otherwise
	  supports them), so don't confuse the user by printing
	  that we have them enabled.
1514

1515 1516 1517 1518
config X86_CPA_STATISTICS
	bool "Enable statistic for Change Page Attribute"
	depends on DEBUG_FS
	---help---
1519
	  Expose statistics about the Change Page Attribute mechanism, which
1520
	  helps to determine the effectiveness of preserving large and huge
1521 1522
	  page mappings when mapping protections are changed.

1523 1524 1525
config AMD_MEM_ENCRYPT
	bool "AMD Secure Memory Encryption (SME) support"
	depends on X86_64 && CPU_SUP_AMD
1526
	select DYNAMIC_PHYSICAL_MASK
1527
	select ARCH_USE_MEMREMAP_PROT
1528
	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547
	---help---
	  Say yes to enable support for the encryption of system memory.
	  This requires an AMD processor that supports Secure Memory
	  Encryption (SME).

config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
	bool "Activate AMD Secure Memory Encryption (SME) by default"
	default y
	depends on AMD_MEM_ENCRYPT
	---help---
	  Say yes to have system memory encrypted by default if running on
	  an AMD processor that supports Secure Memory Encryption (SME).

	  If set to Y, then the encryption of system memory can be
	  deactivated with the mem_encrypt=off command line option.

	  If set to N, then the encryption of system memory can be
	  activated with the mem_encrypt=on command line option.

1548 1549
# Common NUMA Features
config NUMA
1550
	bool "NUMA Memory Allocation and Scheduler Support"
1551
	depends on SMP
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1552 1553
	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
	default y if X86_BIGSMP
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1554
	---help---
1555
	  Enable NUMA (Non-Uniform Memory Access) support.
1556

1557 1558 1559 1560
	  The kernel will try to allocate memory used by a CPU on the
	  local memory controller of the CPU and add some more
	  NUMA awareness to the kernel.

1561
	  For 64-bit this is recommended if the system is Intel Core i7
1562 1563
	  (or later), AMD Opteron, or EM64T NUMA.

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1564
	  For 32-bit this is only needed if you boot a 32-bit
1565
	  kernel on a 64-bit NUMA platform.
1566 1567

	  Otherwise, you should say N.
1568

1569
config AMD_NUMA
1570 1571
	def_bool y
	prompt "Old style AMD Opteron NUMA detection"
1572
	depends on X86_64 && NUMA && PCI
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1573
	---help---
1574 1575 1576 1577 1578
	  Enable AMD NUMA node topology detection.  You should say Y here if
	  you have a multi processor AMD system. This uses an old method to
	  read the NUMA configuration directly from the builtin Northbridge
	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
	  which also takes priority if both are compiled in.
1579 1580

config X86_64_ACPI_NUMA
1581 1582
	def_bool y
	prompt "ACPI NUMA detection"
1583 1584
	depends on X86_64 && NUMA && ACPI && PCI
	select ACPI_NUMA
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1585
	---help---
1586 1587
	  Enable ACPI SRAT based node topology detection.

1588 1589 1590 1591 1592 1593 1594 1595 1596
# Some NUMA nodes have memory ranges that span
# other nodes.  Even though a pfn is valid and
# between a node's start and end pfns, it may not
# reside on that node.  See memmap_init_zone()
# for details.
config NODES_SPAN_OTHER_NODES
	def_bool y
	depends on X86_64_ACPI_NUMA

1597 1598
config NUMA_EMU
	bool "NUMA emulation"
1599
	depends on NUMA
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1600
	---help---
1601 1602 1603 1604 1605
	  Enable NUMA emulation. A flat machine will be split
	  into virtual nodes when booted with "numa=fake=N", where N is the
	  number of nodes. This is only useful for debugging.

config NODES_SHIFT
1606
	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1607 1608
	range 1 10
	default "10" if MAXSMP
1609 1610 1611
	default "6" if X86_64
	default "3"
	depends on NEED_MULTIPLE_NODES
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1612
	---help---
1613
	  Specify the maximum number of NUMA Nodes available on the target
1614
	  system.  Increases memory reserved to accommodate various tables.
1615 1616

config ARCH_HAVE_MEMORY_PRESENT
1617
	def_bool y
1618 1619 1620 1621
	depends on X86_32 && DISCONTIGMEM

config ARCH_FLATMEM_ENABLE
	def_bool y
1622
	depends on X86_32 && !NUMA
1623 1624

config ARCH_DISCONTIGMEM_ENABLE
1625
	def_bool n
1626
	depends on NUMA && X86_32
1627
	depends on BROKEN
1628

1629 1630
config ARCH_SPARSEMEM_ENABLE
	def_bool y
1631
	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1632 1633 1634
	select SPARSEMEM_STATIC if X86_32
	select SPARSEMEM_VMEMMAP_ENABLE if X86_64

1635
config ARCH_SPARSEMEM_DEFAULT
1636
	def_bool X86_64 || (NUMA && X86_32)
1637

1638 1639
config ARCH_SELECT_MEMORY_MODEL
	def_bool y
1640
	depends on ARCH_SPARSEMEM_ENABLE
1641 1642

config ARCH_MEMORY_PROBE
1643
	bool "Enable sysfs memory/probe interface"
1644
	depends on X86_64 && MEMORY_HOTPLUG
1645 1646
	help
	  This option enables a sysfs memory/probe interface for testing.
1647
	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1648
	  If you are unsure how to answer this question, answer N.
1649

1650 1651 1652 1653
config ARCH_PROC_KCORE_TEXT
	def_bool y
	depends on X86_64 && PROC_KCORE

1654
config ILLEGAL_POINTER_VALUE
1655 1656 1657
	hex
	default 0 if X86_32
	default 0xdead000000000000 if X86_64
1658

1659 1660 1661
config X86_PMEM_LEGACY_DEVICE
	bool

1662
config X86_PMEM_LEGACY
1663
	tristate "Support non-standard NVDIMMs and ADR protected memory"
1664 1665
	depends on PHYS_ADDR_T_64BIT
	depends on BLK_DEV
1666
	select X86_PMEM_LEGACY_DEVICE
1667
	select LIBNVDIMM
1668 1669 1670 1671 1672 1673 1674 1675
	help
	  Treat memory marked using the non-standard e820 type of 12 as used
	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
	  The kernel will offer these regions to the 'pmem' driver so
	  they can be used for persistent storage.

	  Say Y if unsure.

1676 1677
config HIGHPTE
	bool "Allocate 3rd-level pagetables from highmem"
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	depends on HIGHMEM
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1679
	---help---
1680 1681 1682 1683 1684
	  The VM uses one page table entry for each page of physical memory.
	  For systems with a lot of RAM, this can be wasteful of precious
	  low memory.  Setting this option will put user-space page table
	  entries in high memory.

1685
config X86_CHECK_BIOS_CORRUPTION
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	bool "Check for low memory corruption"
	---help---
	  Periodically check for memory corruption in low memory, which
	  is suspected to be caused by BIOS.  Even when enabled in the
	  configuration, it is disabled at runtime.  Enable it by
	  setting "memory_corruption_check=1" on the kernel command
	  line.  By default it scans the low 64k of memory every 60
	  seconds; see the memory_corruption_check_size and
	  memory_corruption_check_period parameters in
1695
	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
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	  When enabled with the default parameters, this option has
	  almost no overhead, as it reserves a relatively small amount
	  of memory and scans it infrequently.  It both detects corruption
	  and prevents it from affecting the running system.

	  It is, however, intended as a diagnostic tool; if repeatable
	  BIOS-originated corruption always affects the same memory,
	  you can use memmap= to prevent the kernel from using that
	  memory.
1706

1707
config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
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	bool "Set the default setting of memory_corruption_check"
1709 1710
	depends on X86_CHECK_BIOS_CORRUPTION
	default y
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	---help---
	  Set whether the default state of memory_corruption_check is
	  on or off.
1714

1715
config X86_RESERVE_LOW
1716 1717 1718
	int "Amount of low memory, in kilobytes, to reserve for the BIOS"
	default 64
	range 4 640
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	---help---
1720 1721 1722 1723 1724 1725 1726 1727 1728
	  Specify the amount of low memory to reserve for the BIOS.

	  The first page contains BIOS data structures that the kernel
	  must not use, so that page must always be reserved.

	  By default we reserve the first 64K of physical RAM, as a
	  number of BIOSes are known to corrupt that memory range
	  during events such as suspend/resume or monitor cable
	  insertion, so it must not be used by the kernel.
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1730 1731 1732 1733 1734
	  You can set this to 4 if you are absolutely sure that you
	  trust the BIOS to get all its memory reservations and usages
	  right.  If you know your BIOS have problems beyond the
	  default 64K area, you can set this to 640 to avoid using the
	  entire low memory range.
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1736 1737 1738 1739 1740
	  If you have doubts about the BIOS (e.g. suspend/resume does
	  not work or there's kernel crashes after certain hardware
	  hotplug events) then you might want to enable
	  X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
	  typical corruption patterns.
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1742
	  Leave this to the default value of 64 if you are unsure.
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1744 1745
config MATH_EMULATION
	bool
1746
	depends on MODIFY_LDT_SYSCALL
1747
	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771
	---help---
	  Linux can emulate a math coprocessor (used for floating point
	  operations) if you don't have one. 486DX and Pentium processors have
	  a math coprocessor built in, 486SX and 386 do not, unless you added
	  a 487DX or 387, respectively. (The messages during boot time can
	  give you some hints here ["man dmesg"].) Everyone needs either a
	  coprocessor or this emulation.

	  If you don't have a math coprocessor, you need to say Y here; if you
	  say Y here even though you have a coprocessor, the coprocessor will
	  be used nevertheless. (This behavior can be changed with the kernel
	  command line option "no387", which comes handy if your coprocessor
	  is broken. Try "man bootparam" or see the documentation of your boot
	  loader (lilo or loadlin) about how to pass options to the kernel at
	  boot time.) This means that it is a good idea to say Y here if you
	  intend to use this kernel on different machines.

	  More information about the internals of the Linux math coprocessor
	  emulation can be found in <file:arch/x86/math-emu/README>.

	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
	  kernel, it won't hurt.

config MTRR
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	def_bool y
1773
	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803
	---help---
	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
	  the Memory Type Range Registers (MTRRs) may be used to control
	  processor access to memory ranges. This is most useful if you have
	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
	  allows bus write transfers to be combined into a larger transfer
	  before bursting over the PCI/AGP bus. This can increase performance
	  of image write operations 2.5 times or more. Saying Y here creates a
	  /proc/mtrr file which may be used to manipulate your processor's
	  MTRRs. Typically the X server should use this.

	  This code has a reasonably generic interface so that similar
	  control registers on other processors can be easily supported
	  as well:

	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
	  Registers (ARRs) which provide a similar functionality to MTRRs. For
	  these, the ARRs are used to emulate the MTRRs.
	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
	  write-combining. All of these processors are supported by this code
	  and it makes sense to say Y here if you have one of them.

	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
	  can lead to all sorts of problems, so it's good to say Y here.

	  You can safely say Y even if your machine doesn't have MTRRs, you'll
	  just add about 9 KB to your kernel.

1804
	  See <file:Documentation/x86/mtrr.rst> for more information.
1805

1806
config MTRR_SANITIZER
1807
	def_bool y
1808 1809
	prompt "MTRR cleanup support"
	depends on MTRR
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	---help---
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	  Convert MTRR layout from continuous to discrete, so X drivers can
	  add writeback entries.
1813

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	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1815
	  The largest mtrr entry size for a continuous block can be set with
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	  mtrr_chunk_size.
1817

1818
	  If unsure, say Y.
1819 1820

config MTRR_SANITIZER_ENABLE_DEFAULT
1821 1822 1823
	int "MTRR cleanup enable value (0-1)"
	range 0 1
	default "0"
1824
	depends on MTRR_SANITIZER
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	---help---
1826
	  Enable mtrr cleanup default value
1827

1828 1829 1830 1831 1832
config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
	int "MTRR cleanup spare reg num (0-7)"
	range 0 7
	default "1"
	depends on MTRR_SANITIZER
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	---help---
1834
	  mtrr cleanup spare entries default, it can be changed via
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	  mtrr_spare_reg_nr=N on the kernel command line.
1836

1837
config X86_PAT
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	def_bool y
1839
	prompt "x86 PAT support" if EXPERT
1840
	depends on MTRR
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	---help---
1842
	  Use PAT attributes to setup page level cache control.
1843

1844 1845 1846 1847
	  PATs are the modern equivalents of MTRRs and are much more
	  flexible than MTRRs.

	  Say N here if you see bootup problems (boot crash, boot hang,
1848
	  spontaneous reboots) or a non-working video driver.
1849 1850 1851

	  If unsure, say Y.

1852 1853 1854 1855
config ARCH_USES_PG_UNCACHED
	def_bool y
	depends on X86_PAT

1856 1857 1858 1859 1860 1861 1862 1863 1864
config ARCH_RANDOM
	def_bool y
	prompt "x86 architectural random number generator" if EXPERT
	---help---
	  Enable the x86 architectural RDRAND instruction
	  (Intel Bull Mountain technology) to generate random numbers.
	  If supported, this is a high bandwidth, cryptographically
	  secure hardware random number generator.

1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875
config X86_SMAP
	def_bool y
	prompt "Supervisor Mode Access Prevention" if EXPERT
	---help---
	  Supervisor Mode Access Prevention (SMAP) is a security
	  feature in newer Intel processors.  There is a small
	  performance cost if this enabled and turned on; there is
	  also a small increase in the kernel size if this is enabled.

	  If unsure, say Y.

1876
config X86_UMIP
1877
	def_bool y
1878 1879 1880 1881 1882 1883 1884 1885
	depends on CPU_SUP_INTEL || CPU_SUP_AMD
	prompt "User Mode Instruction Prevention" if EXPERT
	---help---
	  User Mode Instruction Prevention (UMIP) is a security feature in
	  some x86 processors. If enabled, a general protection fault is
	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
	  executed in user mode. These instructions unnecessarily expose
	  information about the hardware state.
1886 1887 1888 1889 1890

	  The vast majority of applications do not use these instructions.
	  For the very few that do, software emulation is provided in
	  specific cases in protected and virtual-8086 modes. Emulated
	  results are dummy.
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config X86_INTEL_MEMORY_PROTECTION_KEYS
1893
	prompt "Intel Memory Protection Keys"
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	def_bool y
1895
	# Note: only available in 64-bit mode
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	depends on CPU_SUP_INTEL && X86_64
1897 1898
	select ARCH_USES_HIGH_VMA_FLAGS
	select ARCH_HAS_PKEYS
1899 1900 1901 1902 1903
	---help---
	  Memory Protection Keys provides a mechanism for enforcing
	  page-based protections, but without requiring modification of the
	  page tables when an application changes protection domains.

1904
	  For details, see Documentation/core-api/protection-keys.rst
1905 1906

	  If unsure, say y.
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1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952
choice
	prompt "TSX enable mode"
	depends on CPU_SUP_INTEL
	default X86_INTEL_TSX_MODE_OFF
	help
	  Intel's TSX (Transactional Synchronization Extensions) feature
	  allows to optimize locking protocols through lock elision which
	  can lead to a noticeable performance boost.

	  On the other hand it has been shown that TSX can be exploited
	  to form side channel attacks (e.g. TAA) and chances are there
	  will be more of those attacks discovered in the future.

	  Therefore TSX is not enabled by default (aka tsx=off). An admin
	  might override this decision by tsx=on the command line parameter.
	  Even with TSX enabled, the kernel will attempt to enable the best
	  possible TAA mitigation setting depending on the microcode available
	  for the particular machine.

	  This option allows to set the default tsx mode between tsx=on, =off
	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
	  details.

	  Say off if not sure, auto if TSX is in use but it should be used on safe
	  platforms or on if TSX is in use and the security aspect of tsx is not
	  relevant.

config X86_INTEL_TSX_MODE_OFF
	bool "off"
	help
	  TSX is disabled if possible - equals to tsx=off command line parameter.

config X86_INTEL_TSX_MODE_ON
	bool "on"
	help
	  TSX is always enabled on TSX capable HW - equals the tsx=on command
	  line parameter.

config X86_INTEL_TSX_MODE_AUTO
	bool "auto"
	help
	  TSX is enabled on TSX capable HW that is believed to be safe against
	  side channel attacks- equals the tsx=auto command line parameter.
endchoice

1953
config EFI
1954
	bool "EFI runtime service support"
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	depends on ACPI
1956
	select UCS2_STRING
1957
	select EFI_RUNTIME_WRAPPERS
1958
	---help---
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	  This enables the kernel to use EFI runtime services that are
	  available (such as the EFI variable services).
1961

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	  This option is only useful on systems that have EFI firmware.
	  In addition, you should use the latest ELILO loader available
	  at <http://elilo.sourceforge.net> in order to take advantage
	  of EFI runtime services. However, even with this option, the
	  resultant kernel should continue to boot on existing non-EFI
	  platforms.
1968

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config EFI_STUB
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	bool "EFI stub support"
	depends on EFI && !X86_USE_3DNOW
	depends on $(cc-option,-mabi=ms) || X86_32
	select RELOCATABLE
	---help---
	  This kernel feature allows a bzImage to be loaded directly
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	  by EFI firmware without the use of a bootloader.

1978
	  See Documentation/admin-guide/efi-stub.rst for more information.
1979

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config EFI_MIXED
	bool "EFI mixed-mode support"
	depends on EFI_STUB && X86_64
	---help---
	   Enabling this feature allows a 64-bit kernel to be booted
	   on a 32-bit firmware, provided that your CPU supports 64-bit
	   mode.

	   Note that it is not possible to boot a mixed-mode enabled
	   kernel via the EFI boot stub - a bootloader that supports
	   the EFI handover protocol must be used.

	   If unsure, say N.

1994
config SECCOMP
1995 1996
	def_bool y
	prompt "Enable seccomp to safely compute untrusted bytecode"
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	---help---
1998 1999 2000 2001 2002 2003
	  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
2004
	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2005 2006 2007 2008 2009
	  and the task is only allowed to execute a few safe syscalls
	  defined by each seccomp mode.

	  If unsure, say Y. Only embedded should say N here.

2010
source "kernel/Kconfig.hz"
2011 2012 2013

config KEXEC
	bool "kexec system call"
2014
	select KEXEC_CORE
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	---help---
2016 2017 2018 2019 2020 2021 2022 2023 2024
	  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.

	  The name comes from the similarity to the exec system call.

	  It is an ongoing process to be certain the hardware in a machine
	  is properly shutdown, so do not be surprised if this code does not
2025 2026 2027
	  initially work for you.  As of this writing the exact hardware
	  interface is strongly in flux, so no good recommendation can be
	  made.
2028

2029 2030
config KEXEC_FILE
	bool "kexec file based system call"
2031
	select KEXEC_CORE
2032 2033 2034 2035 2036 2037 2038 2039 2040 2041
	select BUILD_BIN2C
	depends on X86_64
	depends on CRYPTO=y
	depends on CRYPTO_SHA256=y
	---help---
	  This is new version of kexec system call. This system call is
	  file based and takes file descriptors as system call argument
	  for kernel and initramfs as opposed to list of segments as
	  accepted by previous system call.

2042 2043 2044
config ARCH_HAS_KEXEC_PURGATORY
	def_bool KEXEC_FILE

2045
config KEXEC_SIG
2046
	bool "Verify kernel signature during kexec_file_load() syscall"
2047
	depends on KEXEC_FILE
2048
	---help---
2049

2050 2051 2052 2053 2054 2055
	  This option makes the kexec_file_load() syscall check for a valid
	  signature of the kernel image.  The image can still be loaded without
	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
	  there's a signature that we can check, then it must be valid.

	  In addition to this option, you need to enable signature
2056 2057
	  verification for the corresponding kernel image type being
	  loaded in order for this to work.
2058

2059 2060 2061 2062 2063 2064 2065
config KEXEC_SIG_FORCE
	bool "Require a valid signature in kexec_file_load() syscall"
	depends on KEXEC_SIG
	---help---
	  This option makes kernel signature verification mandatory for
	  the kexec_file_load() syscall.

2066 2067
config KEXEC_BZIMAGE_VERIFY_SIG
	bool "Enable bzImage signature verification support"
2068
	depends on KEXEC_SIG
2069 2070 2071 2072 2073
	depends on SIGNED_PE_FILE_VERIFICATION
	select SYSTEM_TRUSTED_KEYRING
	---help---
	  Enable bzImage signature verification support.

2074
config CRASH_DUMP
2075
	bool "kernel crash dumps"
2076
	depends on X86_64 || (X86_32 && HIGHMEM)
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	---help---
2078 2079 2080 2081 2082 2083 2084 2085
	  Generate crash dump after being started by kexec.
	  This should be normally only set in special crash dump kernels
	  which are loaded in the main kernel with kexec-tools into
	  a specially reserved region and then later executed after
	  a crash by kdump/kexec. The crash dump kernel must be compiled
	  to a memory address not used by the main kernel or BIOS using
	  PHYSICAL_START, or it must be built as a relocatable image
	  (CONFIG_RELOCATABLE=y).
2086
	  For more details see Documentation/admin-guide/kdump/kdump.rst
2087

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config KEXEC_JUMP
2089
	bool "kexec jump"
2090
	depends on KEXEC && HIBERNATION
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	---help---
2092 2093
	  Jump between original kernel and kexeced kernel and invoke
	  code in physical address mode via KEXEC
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2095
config PHYSICAL_START
2096
	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2097
	default "0x1000000"
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	---help---
2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115
	  This gives the physical address where the kernel is loaded.

	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
	  bzImage will decompress itself to above physical address and
	  run from there. Otherwise, bzImage will run from the address where
	  it has been loaded by the boot loader and will ignore above physical
	  address.

	  In normal kdump cases one does not have to set/change this option
	  as now bzImage can be compiled as a completely relocatable image
	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
	  address. This option is mainly useful for the folks who don't want
	  to use a bzImage for capturing the crash dump and want to use a
	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
	  to be specifically compiled to run from a specific memory area
	  (normally a reserved region) and this option comes handy.

2116 2117 2118 2119 2120 2121 2122
	  So if you are using bzImage for capturing the crash dump,
	  leave the value here unchanged to 0x1000000 and set
	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
	  for capturing the crash dump change this value to start of
	  the reserved region.  In other words, it can be set based on
	  the "X" value as specified in the "crashkernel=YM@XM"
	  command line boot parameter passed to the panic-ed
2123
	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2124
	  for more details about crash dumps.
2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136

	  Usage of bzImage for capturing the crash dump is recommended as
	  one does not have to build two kernels. Same kernel can be used
	  as production kernel and capture kernel. Above option should have
	  gone away after relocatable bzImage support is introduced. But it
	  is present because there are users out there who continue to use
	  vmlinux for dump capture. This option should go away down the
	  line.

	  Don't change this unless you know what you are doing.

config RELOCATABLE
2137 2138
	bool "Build a relocatable kernel"
	default y
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	---help---
2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150
	  This builds a kernel image that retains relocation information
	  so it can be loaded someplace besides the default 1MB.
	  The relocations tend to make the kernel binary about 10% larger,
	  but are discarded at runtime.

	  One use is for the kexec on panic case where the recovery kernel
	  must live at a different physical address than the primary
	  kernel.

	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
	  it has been loaded at and the compile time physical address
2151
	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2152

2153
config RANDOMIZE_BASE
2154
	bool "Randomize the address of the kernel image (KASLR)"
2155
	depends on RELOCATABLE
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	default y
2157
	---help---
2158 2159 2160 2161 2162 2163 2164
	  In support of Kernel Address Space Layout Randomization (KASLR),
	  this randomizes the physical address at which the kernel image
	  is decompressed and the virtual address where the kernel
	  image is mapped, as a security feature that deters exploit
	  attempts relying on knowledge of the location of kernel
	  code internals.

2165 2166 2167 2168 2169 2170 2171 2172 2173 2174
	  On 64-bit, the kernel physical and virtual addresses are
	  randomized separately. The physical address will be anywhere
	  between 16MB and the top of physical memory (up to 64TB). The
	  virtual address will be randomized from 16MB up to 1GB (9 bits
	  of entropy). Note that this also reduces the memory space
	  available to kernel modules from 1.5GB to 1GB.

	  On 32-bit, the kernel physical and virtual addresses are
	  randomized together. They will be randomized from 16MB up to
	  512MB (8 bits of entropy).
2175 2176 2177 2178

	  Entropy is generated using the RDRAND instruction if it is
	  supported. If RDTSC is supported, its value is mixed into
	  the entropy pool as well. If neither RDRAND nor RDTSC are
2179 2180 2181 2182 2183 2184
	  supported, then entropy is read from the i8254 timer. The
	  usable entropy is limited by the kernel being built using
	  2GB addressing, and that PHYSICAL_ALIGN must be at a
	  minimum of 2MB. As a result, only 10 bits of entropy are
	  theoretically possible, but the implementations are further
	  limited due to memory layouts.
2185

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	  If unsure, say Y.
2187 2188

# Relocation on x86 needs some additional build support
2189 2190
config X86_NEED_RELOCS
	def_bool y
2191
	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2192

2193
config PHYSICAL_ALIGN
2194
	hex "Alignment value to which kernel should be aligned"
2195
	default "0x200000"
2196 2197
	range 0x2000 0x1000000 if X86_32
	range 0x200000 0x1000000 if X86_64
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	---help---
2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214
	  This value puts the alignment restrictions on physical address
	  where kernel is loaded and run from. Kernel is compiled for an
	  address which meets above alignment restriction.

	  If bootloader loads the kernel at a non-aligned address and
	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
	  address aligned to above value and run from there.

	  If bootloader loads the kernel at a non-aligned address and
	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
	  load address and decompress itself to the address it has been
	  compiled for and run from there. The address for which kernel is
	  compiled already meets above alignment restrictions. Hence the
	  end result is that kernel runs from a physical address meeting
	  above alignment restrictions.

2215 2216 2217
	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
	  this value must be a multiple of 0x200000.

2218 2219
	  Don't change this unless you know what you are doing.

2220 2221 2222 2223 2224 2225
config DYNAMIC_MEMORY_LAYOUT
	bool
	---help---
	  This option makes base addresses of vmalloc and vmemmap as well as
	  __PAGE_OFFSET movable during boot.

2226 2227 2228 2229
config RANDOMIZE_MEMORY
	bool "Randomize the kernel memory sections"
	depends on X86_64
	depends on RANDOMIZE_BASE
2230
	select DYNAMIC_MEMORY_LAYOUT
2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241
	default RANDOMIZE_BASE
	---help---
	   Randomizes the base virtual address of kernel memory sections
	   (physical memory mapping, vmalloc & vmemmap). This security feature
	   makes exploits relying on predictable memory locations less reliable.

	   The order of allocations remains unchanged. Entropy is generated in
	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
	   configuration have in average 30,000 different possible virtual
	   addresses for each memory section.

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	   If unsure, say Y.
2243

2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258
config RANDOMIZE_MEMORY_PHYSICAL_PADDING
	hex "Physical memory mapping padding" if EXPERT
	depends on RANDOMIZE_MEMORY
	default "0xa" if MEMORY_HOTPLUG
	default "0x0"
	range 0x1 0x40 if MEMORY_HOTPLUG
	range 0x0 0x40
	---help---
	   Define the padding in terabytes added to the existing physical
	   memory size during kernel memory randomization. It is useful
	   for memory hotplug support but reduces the entropy available for
	   address randomization.

	   If unsure, leave at the default value.

2259
config HOTPLUG_CPU
2260
	def_bool y
2261
	depends on SMP
2262

2263 2264
config BOOTPARAM_HOTPLUG_CPU0
	bool "Set default setting of cpu0_hotpluggable"
2265
	depends on HOTPLUG_CPU
2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290
	---help---
	  Set whether default state of cpu0_hotpluggable is on or off.

	  Say Y here to enable CPU0 hotplug by default. If this switch
	  is turned on, there is no need to give cpu0_hotplug kernel
	  parameter and the CPU0 hotplug feature is enabled by default.

	  Please note: there are two known CPU0 dependencies if you want
	  to enable the CPU0 hotplug feature either by this switch or by
	  cpu0_hotplug kernel parameter.

	  First, resume from hibernate or suspend always starts from CPU0.
	  So hibernate and suspend are prevented if CPU0 is offline.

	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
	  offline if any interrupt can not migrate out of CPU0. There may
	  be other CPU0 dependencies.

	  Please make sure the dependencies are under your control before
	  you enable this feature.

	  Say N if you don't want to enable CPU0 hotplug feature by default.
	  You still can enable the CPU0 hotplug feature at boot by kernel
	  parameter cpu0_hotplug.

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config DEBUG_HOTPLUG_CPU0
	def_bool n
	prompt "Debug CPU0 hotplug"
2294
	depends on HOTPLUG_CPU
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	---help---
	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
	  soon as possible and boots up userspace with CPU0 offlined. User
	  can online CPU0 back after boot time.

	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
	  compilation or giving cpu0_hotplug kernel parameter at boot.

	  If unsure, say N.

2306
config COMPAT_VDSO
2307 2308
	def_bool n
	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2309
	depends on COMPAT_32
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	---help---
2311 2312 2313
	  Certain buggy versions of glibc will crash if they are
	  presented with a 32-bit vDSO that is not mapped at the address
	  indicated in its segment table.
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2315 2316 2317 2318 2319
	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
	  the only released version with the bug, but OpenSUSE 9
	  contains a buggy "glibc 2.3.2".
2320

2321 2322 2323 2324 2325 2326 2327 2328 2329
	  The symptom of the bug is that everything crashes on startup, saying:
	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!

	  Saying Y here changes the default value of the vdso32 boot
	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
	  This works around the glibc bug but hurts performance.

	  If unsure, say N: if you are compiling your own kernel, you
	  are unlikely to be using a buggy version of glibc.
2330

2331 2332 2333
choice
	prompt "vsyscall table for legacy applications"
	depends on X86_64
2334
	default LEGACY_VSYSCALL_XONLY
2335 2336 2337 2338 2339 2340 2341
	help
	  Legacy user code that does not know how to find the vDSO expects
	  to be able to issue three syscalls by calling fixed addresses in
	  kernel space. Since this location is not randomized with ASLR,
	  it can be used to assist security vulnerability exploitation.

	  This setting can be changed at boot time via the kernel command
2342
	  line parameter vsyscall=[emulate|xonly|none].
2343 2344 2345 2346 2347

	  On a system with recent enough glibc (2.14 or newer) and no
	  static binaries, you can say None without a performance penalty
	  to improve security.

2348
	  If unsure, select "Emulate execution only".
2349 2350

	config LEGACY_VSYSCALL_EMULATE
2351
		bool "Full emulation"
2352
		help
2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373
		  The kernel traps and emulates calls into the fixed vsyscall
		  address mapping. This makes the mapping non-executable, but
		  it still contains readable known contents, which could be
		  used in certain rare security vulnerability exploits. This
		  configuration is recommended when using legacy userspace
		  that still uses vsyscalls along with legacy binary
		  instrumentation tools that require code to be readable.

		  An example of this type of legacy userspace is running
		  Pin on an old binary that still uses vsyscalls.

	config LEGACY_VSYSCALL_XONLY
		bool "Emulate execution only"
		help
		  The kernel traps and emulates calls into the fixed vsyscall
		  address mapping and does not allow reads.  This
		  configuration is recommended when userspace might use the
		  legacy vsyscall area but support for legacy binary
		  instrumentation of legacy code is not needed.  It mitigates
		  certain uses of the vsyscall area as an ASLR-bypassing
		  buffer.
2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385

	config LEGACY_VSYSCALL_NONE
		bool "None"
		help
		  There will be no vsyscall mapping at all. This will
		  eliminate any risk of ASLR bypass due to the vsyscall
		  fixed address mapping. Attempts to use the vsyscalls
		  will be reported to dmesg, so that either old or
		  malicious userspace programs can be identified.

endchoice

2386 2387
config CMDLINE_BOOL
	bool "Built-in kernel command line"
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	---help---
2389 2390 2391 2392 2393 2394 2395 2396
	  Allow for specifying boot arguments to the kernel at
	  build time.  On some systems (e.g. embedded ones), it is
	  necessary or convenient to provide some or all of the
	  kernel boot arguments with the kernel itself (that is,
	  to not rely on the boot loader to provide them.)

	  To compile command line arguments into the kernel,
	  set this option to 'Y', then fill in the
2397
	  boot arguments in CONFIG_CMDLINE.
2398 2399 2400 2401 2402 2403 2404 2405

	  Systems with fully functional boot loaders (i.e. non-embedded)
	  should leave this option set to 'N'.

config CMDLINE
	string "Built-in kernel command string"
	depends on CMDLINE_BOOL
	default ""
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	---help---
2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421
	  Enter arguments here that should be compiled into the kernel
	  image and used at boot time.  If the boot loader provides a
	  command line at boot time, it is appended to this string to
	  form the full kernel command line, when the system boots.

	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
	  change this behavior.

	  In most cases, the command line (whether built-in or provided
	  by the boot loader) should specify the device for the root
	  file system.

config CMDLINE_OVERRIDE
	bool "Built-in command line overrides boot loader arguments"
	depends on CMDLINE_BOOL
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	---help---
2423 2424 2425 2426 2427 2428
	  Set this option to 'Y' to have the kernel ignore the boot loader
	  command line, and use ONLY the built-in command line.

	  This is used to work around broken boot loaders.  This should
	  be set to 'N' under normal conditions.

2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444
config MODIFY_LDT_SYSCALL
	bool "Enable the LDT (local descriptor table)" if EXPERT
	default y
	---help---
	  Linux can allow user programs to install a per-process x86
	  Local Descriptor Table (LDT) using the modify_ldt(2) system
	  call.  This is required to run 16-bit or segmented code such as
	  DOSEMU or some Wine programs.  It is also used by some very old
	  threading libraries.

	  Enabling this feature adds a small amount of overhead to
	  context switches and increases the low-level kernel attack
	  surface.  Disabling it removes the modify_ldt(2) system call.

	  Saying 'N' here may make sense for embedded or server kernels.

2445 2446
source "kernel/livepatch/Kconfig"

2447 2448
endmenu

2449 2450 2451 2452
config ARCH_HAS_ADD_PAGES
	def_bool y
	depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG

2453 2454 2455 2456
config ARCH_ENABLE_MEMORY_HOTPLUG
	def_bool y
	depends on X86_64 || (X86_32 && HIGHMEM)

2457 2458 2459 2460
config ARCH_ENABLE_MEMORY_HOTREMOVE
	def_bool y
	depends on MEMORY_HOTPLUG

2461
config USE_PERCPU_NUMA_NODE_ID
2462
	def_bool y
2463 2464
	depends on NUMA

2465 2466 2467 2468
config ARCH_ENABLE_SPLIT_PMD_PTLOCK
	def_bool y
	depends on X86_64 || X86_PAE

2469 2470 2471 2472
config ARCH_ENABLE_HUGEPAGE_MIGRATION
	def_bool y
	depends on X86_64 && HUGETLB_PAGE && MIGRATION

2473 2474 2475 2476
config ARCH_ENABLE_THP_MIGRATION
	def_bool y
	depends on X86_64 && TRANSPARENT_HUGEPAGE

2477
menu "Power management and ACPI options"
2478 2479

config ARCH_HIBERNATION_HEADER
2480
	def_bool y
2481
	depends on HIBERNATION
2482 2483 2484 2485 2486

source "kernel/power/Kconfig"

source "drivers/acpi/Kconfig"

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2487 2488
source "drivers/sfi/Kconfig"

2489
config X86_APM_BOOT
J
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2490
	def_bool y
2491
	depends on APM
2492

2493 2494
menuconfig APM
	tristate "APM (Advanced Power Management) BIOS support"
2495
	depends on X86_32 && PM_SLEEP
2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510
	---help---
	  APM is a BIOS specification for saving power using several different
	  techniques. This is mostly useful for battery powered laptops with
	  APM compliant BIOSes. If you say Y here, the system time will be
	  reset after a RESUME operation, the /proc/apm device will provide
	  battery status information, and user-space programs will receive
	  notification of APM "events" (e.g. battery status change).

	  If you select "Y" here, you can disable actual use of the APM
	  BIOS by passing the "apm=off" option to the kernel at boot time.

	  Note that the APM support is almost completely disabled for
	  machines with more than one CPU.

	  In order to use APM, you will need supporting software. For location
2511
	  and more information, read <file:Documentation/power/apm-acpi.rst>
2512
	  and the Battery Powered Linux mini-HOWTO, available from
2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555
	  <http://www.tldp.org/docs.html#howto>.

	  This driver does not spin down disk drives (see the hdparm(8)
	  manpage ("man 8 hdparm") for that), and it doesn't turn off
	  VESA-compliant "green" monitors.

	  This driver does not support the TI 4000M TravelMate and the ACER
	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
	  desktop machines also don't have compliant BIOSes, and this driver
	  may cause those machines to panic during the boot phase.

	  Generally, if you don't have a battery in your machine, there isn't
	  much point in using this driver and you should say N. If you get
	  random kernel OOPSes or reboots that don't seem to be related to
	  anything, try disabling/enabling this option (or disabling/enabling
	  APM in your BIOS).

	  Some other things you should try when experiencing seemingly random,
	  "weird" problems:

	  1) make sure that you have enough swap space and that it is
	  enabled.
	  2) pass the "no-hlt" option to the kernel
	  3) switch on floating point emulation in the kernel and pass
	  the "no387" option to the kernel
	  4) pass the "floppy=nodma" option to the kernel
	  5) pass the "mem=4M" option to the kernel (thereby disabling
	  all but the first 4 MB of RAM)
	  6) make sure that the CPU is not over clocked.
	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
	  8) disable the cache from your BIOS settings
	  9) install a fan for the video card or exchange video RAM
	  10) install a better fan for the CPU
	  11) exchange RAM chips
	  12) exchange the motherboard.

	  To compile this driver as a module, choose M here: the
	  module will be called apm.

if APM

config APM_IGNORE_USER_SUSPEND
	bool "Ignore USER SUSPEND"
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	---help---
2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578
	  This option will ignore USER SUSPEND requests. On machines with a
	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
	  series notebooks, it is necessary to say Y because of a BIOS bug.

config APM_DO_ENABLE
	bool "Enable PM at boot time"
	---help---
	  Enable APM features at boot time. From page 36 of the APM BIOS
	  specification: "When disabled, the APM BIOS does not automatically
	  power manage devices, enter the Standby State, enter the Suspend
	  State, or take power saving steps in response to CPU Idle calls."
	  This driver will make CPU Idle calls when Linux is idle (unless this
	  feature is turned off -- see "Do CPU IDLE calls", below). This
	  should always save battery power, but more complicated APM features
	  will be dependent on your BIOS implementation. You may need to turn
	  this option off if your computer hangs at boot time when using APM
	  support, or if it beeps continuously instead of suspending. Turn
	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
	  T400CDT. This is off by default since most machines do fine without
	  this feature.

config APM_CPU_IDLE
2579
	depends on CPU_IDLE
2580
	bool "Make CPU Idle calls when idle"
I
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2581
	---help---
2582 2583 2584 2585 2586 2587 2588 2589 2590 2591
	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
	  On some machines, this can activate improved power savings, such as
	  a slowed CPU clock rate, when the machine is idle. These idle calls
	  are made after the idle loop has run for some length of time (e.g.,
	  333 mS). On some machines, this will cause a hang at boot time or
	  whenever the CPU becomes idle. (On machines with more than one CPU,
	  this option does nothing.)

config APM_DISPLAY_BLANK
	bool "Enable console blanking using APM"
I
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2592
	---help---
2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604
	  Enable console blanking using the APM. Some laptops can use this to
	  turn off the LCD backlight when the screen blanker of the Linux
	  virtual console blanks the screen. Note that this is only used by
	  the virtual console screen blanker, and won't turn off the backlight
	  when using the X Window system. This also doesn't have anything to
	  do with your VESA-compliant power-saving monitor. Further, this
	  option doesn't work for all laptops -- it might not turn off your
	  backlight at all, or it might print a lot of errors to the console,
	  especially if you are using gpm.

config APM_ALLOW_INTS
	bool "Allow interrupts during APM BIOS calls"
I
Ingo Molnar 已提交
2605
	---help---
2606 2607 2608 2609 2610 2611 2612 2613 2614
	  Normally we disable external interrupts while we are making calls to
	  the APM BIOS as a measure to lessen the effects of a badly behaving
	  BIOS implementation.  The BIOS should reenable interrupts if it
	  needs to.  Unfortunately, some BIOSes do not -- especially those in
	  many of the newer IBM Thinkpads.  If you experience hangs when you
	  suspend, try setting this to Y.  Otherwise, say N.

endif # APM

2615
source "drivers/cpufreq/Kconfig"
2616 2617 2618

source "drivers/cpuidle/Kconfig"

A
Andy Henroid 已提交
2619 2620
source "drivers/idle/Kconfig"

2621 2622 2623 2624 2625 2626 2627
endmenu


menu "Bus options (PCI etc.)"

choice
	prompt "PCI access mode"
2628
	depends on X86_32 && PCI
2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653
	default PCI_GOANY
	---help---
	  On PCI systems, the BIOS can be used to detect the PCI devices and
	  determine their configuration. However, some old PCI motherboards
	  have BIOS bugs and may crash if this is done. Also, some embedded
	  PCI-based systems don't have any BIOS at all. Linux can also try to
	  detect the PCI hardware directly without using the BIOS.

	  With this option, you can specify how Linux should detect the
	  PCI devices. If you choose "BIOS", the BIOS will be used,
	  if you choose "Direct", the BIOS won't be used, and if you
	  choose "MMConfig", then PCI Express MMCONFIG will be used.
	  If you choose "Any", the kernel will try MMCONFIG, then the
	  direct access method and falls back to the BIOS if that doesn't
	  work. If unsure, go with the default, which is "Any".

config PCI_GOBIOS
	bool "BIOS"

config PCI_GOMMCONFIG
	bool "MMConfig"

config PCI_GODIRECT
	bool "Direct"

2654
config PCI_GOOLPC
2655
	bool "OLPC XO-1"
2656 2657
	depends on OLPC

2658 2659 2660
config PCI_GOANY
	bool "Any"

2661 2662 2663
endchoice

config PCI_BIOS
2664
	def_bool y
2665
	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2666 2667 2668

# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
config PCI_DIRECT
2669
	def_bool y
2670
	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2671 2672

config PCI_MMCONFIG
2673 2674
	bool "Support mmconfig PCI config space access" if X86_64
	default y
2675
	depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2676
	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2677

2678
config PCI_OLPC
2679 2680
	def_bool y
	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2681

2682 2683 2684 2685 2686
config PCI_XEN
	def_bool y
	depends on PCI && XEN
	select SWIOTLB_XEN

2687 2688 2689
config MMCONF_FAM10H
	def_bool y
	depends on X86_64 && PCI_MMCONFIG && ACPI
2690

2691
config PCI_CNB20LE_QUIRK
2692
	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2693
	depends on PCI
2694 2695 2696 2697 2698
	help
	  Read the PCI windows out of the CNB20LE host bridge. This allows
	  PCI hotplug to work on systems with the CNB20LE chipset which do
	  not have ACPI.

2699 2700 2701 2702 2703
	  There's no public spec for this chipset, and this functionality
	  is known to be incomplete.

	  You should say N unless you know you need this.

2704
config ISA_BUS
2705
	bool "ISA bus support on modern systems" if EXPERT
2706
	help
2707 2708 2709 2710 2711
	  Expose ISA bus device drivers and options available for selection and
	  configuration. Enable this option if your target machine has an ISA
	  bus. ISA is an older system, displaced by PCI and newer bus
	  architectures -- if your target machine is modern, it probably does
	  not have an ISA bus.
2712 2713 2714

	  If unsure, say N.

2715
# x86_64 have no ISA slots, but can have ISA-style DMA.
2716
config ISA_DMA_API
2717 2718 2719 2720 2721
	bool "ISA-style DMA support" if (X86_64 && EXPERT)
	default y
	help
	  Enables ISA-style DMA support for devices requiring such controllers.
	  If unsure, say Y.
2722

2723 2724
if X86_32

2725 2726
config ISA
	bool "ISA support"
I
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2727
	---help---
2728 2729 2730 2731 2732 2733 2734 2735
	  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.

config SCx200
	tristate "NatSemi SCx200 support"
I
Ingo Molnar 已提交
2736
	---help---
2737 2738 2739 2740 2741 2742 2743 2744 2745
	  This provides basic support for National Semiconductor's
	  (now AMD's) Geode processors.  The driver probes for the
	  PCI-IDs of several on-chip devices, so its a good dependency
	  for other scx200_* drivers.

	  If compiled as a module, the driver is named scx200.

config SCx200HR_TIMER
	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
J
John Stultz 已提交
2746
	depends on SCx200
2747
	default y
I
Ingo Molnar 已提交
2748
	---help---
2749 2750 2751 2752 2753 2754
	  This driver provides a clocksource built upon the on-chip
	  27MHz high-resolution timer.  Its also a workaround for
	  NSC Geode SC-1100's buggy TSC, which loses time when the
	  processor goes idle (as is done by the scheduler).  The
	  other workaround is idle=poll boot option.

2755 2756
config OLPC
	bool "One Laptop Per Child support"
2757
	depends on !X86_PAE
2758
	select GPIOLIB
2759
	select OF
2760
	select OF_PROMTREE
2761
	select IRQ_DOMAIN
2762
	select OLPC_EC
I
Ingo Molnar 已提交
2763
	---help---
2764 2765 2766
	  Add support for detecting the unique features of the OLPC
	  XO hardware.

2767 2768
config OLPC_XO1_PM
	bool "OLPC XO-1 Power Management"
2769
	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2770
	---help---
2771
	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2772

D
Daniel Drake 已提交
2773 2774 2775 2776 2777 2778 2779
config OLPC_XO1_RTC
	bool "OLPC XO-1 Real Time Clock"
	depends on OLPC_XO1_PM && RTC_DRV_CMOS
	---help---
	  Add support for the XO-1 real time clock, which can be used as a
	  programmable wakeup source.

2780 2781
config OLPC_XO1_SCI
	bool "OLPC XO-1 SCI extras"
2782
	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2783
	depends on INPUT=y
2784
	select POWER_SUPPLY
2785 2786
	---help---
	  Add support for SCI-based features of the OLPC XO-1 laptop:
2787
	   - EC-driven system wakeups
2788
	   - Power button
2789
	   - Ebook switch
2790
	   - Lid switch
2791 2792
	   - AC adapter status updates
	   - Battery status updates
2793

D
Daniel Drake 已提交
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config OLPC_XO15_SCI
	bool "OLPC XO-1.5 SCI extras"
2796 2797
	depends on OLPC && ACPI
	select POWER_SUPPLY
D
Daniel Drake 已提交
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	---help---
	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
	   - EC-driven system wakeups
	   - AC adapter status updates
	   - Battery status updates
2803

2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817
config ALIX
	bool "PCEngines ALIX System Support (LED setup)"
	select GPIOLIB
	---help---
	  This option enables system support for the PCEngines ALIX.
	  At present this just sets up LEDs for GPIO control on
	  ALIX2/3/6 boards.  However, other system specific setup should
	  get added here.

	  Note: You must still enable the drivers for GPIO and LED support
	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs

	  Note: You have to set alix.force=1 for boards with Award BIOS.

2818 2819 2820 2821 2822 2823
config NET5501
	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
	select GPIOLIB
	---help---
	  This option enables system support for the Soekris Engineering net5501.

2824 2825 2826 2827 2828 2829 2830
config GEOS
	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
	select GPIOLIB
	depends on DMI
	---help---
	  This option enables system support for the Traverse Technologies GEOS.

2831 2832 2833 2834 2835 2836 2837 2838 2839
config TS5500
	bool "Technologic Systems TS-5500 platform support"
	depends on MELAN
	select CHECK_SIGNATURE
	select NEW_LEDS
	select LEDS_CLASS
	---help---
	  This option enables system support for the Technologic Systems TS-5500.

2840 2841
endif # X86_32

2842
config AMD_NB
2843
	def_bool y
2844
	depends on CPU_SUP_AMD && PCI
2845

2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856
config X86_SYSFB
	bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
	help
	  Firmwares often provide initial graphics framebuffers so the BIOS,
	  bootloader or kernel can show basic video-output during boot for
	  user-guidance and debugging. Historically, x86 used the VESA BIOS
	  Extensions and EFI-framebuffers for this, which are mostly limited
	  to x86.
	  This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
	  framebuffers so the new generic system-framebuffer drivers can be
	  used on x86. If the framebuffer is not compatible with the generic
N
Nikolas Nyby 已提交
2857
	  modes, it is advertised as fallback platform framebuffer so legacy
2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871
	  drivers like efifb, vesafb and uvesafb can pick it up.
	  If this option is not selected, all system framebuffers are always
	  marked as fallback platform framebuffers as usual.

	  Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
	  not be able to pick up generic system framebuffers if this option
	  is selected. You are highly encouraged to enable simplefb as
	  replacement if you select this option. simplefb can correctly deal
	  with generic system framebuffers. But you should still keep vesafb
	  and others enabled as fallback if a system framebuffer is
	  incompatible with simplefb.

	  If unsure, say Y.

2872 2873 2874
endmenu


2875
menu "Binary Emulations"
2876 2877 2878 2879

config IA32_EMULATION
	bool "IA32 Emulation"
	depends on X86_64
2880
	select ARCH_WANT_OLD_COMPAT_IPC
2881
	select BINFMT_ELF
R
Roland McGrath 已提交
2882
	select COMPAT_BINFMT_ELF
2883
	select COMPAT_OLD_SIGACTION
I
Ingo Molnar 已提交
2884
	---help---
H
H. J. Lu 已提交
2885 2886 2887
	  Include code to run legacy 32-bit programs under a
	  64-bit kernel. You should likely turn this on, unless you're
	  100% sure that you don't have any 32-bit programs left.
2888 2889

config IA32_AOUT
I
Ingo Molnar 已提交
2890 2891
	tristate "IA32 a.out support"
	depends on IA32_EMULATION
B
Borislav Petkov 已提交
2892
	depends on BROKEN
I
Ingo Molnar 已提交
2893 2894
	---help---
	  Support old a.out binaries in the 32bit emulation.
2895

2896
config X86_X32
2897
	bool "x32 ABI for 64-bit mode"
2898
	depends on X86_64
H
H. J. Lu 已提交
2899 2900 2901 2902 2903 2904 2905 2906 2907 2908
	---help---
	  Include code to run binaries for the x32 native 32-bit ABI
	  for 64-bit processors.  An x32 process gets access to the
	  full 64-bit register file and wide data path while leaving
	  pointers at 32 bits for smaller memory footprint.

	  You will need a recent binutils (2.22 or later) with
	  elf32_x86_64 support enabled to compile a kernel with this
	  option set.

2909 2910 2911 2912 2913 2914
config COMPAT_32
	def_bool y
	depends on IA32_EMULATION || X86_32
	select HAVE_UID16
	select OLD_SIGSUSPEND3

2915
config COMPAT
2916
	def_bool y
2917
	depends on IA32_EMULATION || X86_X32
2918

2919
if COMPAT
2920
config COMPAT_FOR_U64_ALIGNMENT
2921
	def_bool y
2922 2923

config SYSVIPC_COMPAT
2924
	def_bool y
2925 2926
	depends on SYSVIPC
endif
2927

2928 2929 2930
endmenu


K
Keith Packard 已提交
2931 2932 2933 2934
config HAVE_ATOMIC_IOMAP
	def_bool y
	depends on X86_32

2935 2936
source "drivers/firmware/Kconfig"

2937
source "arch/x86/kvm/Kconfig"