Kconfig 96.7 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_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_EXTABLE_SORT
	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
	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 HAVE_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
       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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	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---
	  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
       bool "Goldfish (Virtual Platform)"
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       depends on X86_EXTENDED_PLATFORM
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       ---help---
	 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
579
	select X86_REBOOTFIXUPS
580 581
	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.

587
config X86_INTEL_MID
588 589
	bool "Intel MID platform support"
	depends on X86_EXTENDED_PLATFORM
590
	depends on X86_PLATFORM_DEVICES
591
	depends on PCI
592
	depends on X86_64 || (PCI_GOANY && X86_32)
593
	depends on X86_IO_APIC
594
	select SFI
595
	select I2C
596
	select DW_APB_TIMER
597 598
	select APB_TIMER
	select INTEL_SCU_IPC
599
	select MFD_INTEL_MSIC
600
	---help---
601 602 603
	  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.
604

605 606
	  Intel MID platforms are based on an Intel processor and chipset which
	  consume less power than most of the x86 derivatives.
607

608 609 610 611 612 613 614 615 616 617 618
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
619
	select COMMON_CLK
620 621 622 623 624
	---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.

625 626
config X86_INTEL_LPSS
	bool "Intel Low Power Subsystem Support"
627
	depends on X86 && ACPI && PCI
628
	select COMMON_CLK
629
	select PINCTRL
630
	select IOSF_MBI
631 632 633
	---help---
	  Select to build support for Intel Low Power Subsystem such as
	  found on Intel Lynxpoint PCH. Selecting this option enables
634 635
	  things like clock tree (common clock framework) and pincontrol
	  which are needed by the LPSS peripheral drivers.
636

637 638 639 640 641 642 643 644 645 646 647
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"
680
	depends on X86_32
681 682 683 684 685 686 687 688
	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.

689
config X86_32_NON_STANDARD
690 691
	bool "Support non-standard 32-bit SMP architectures"
	depends on X86_32 && SMP
692
	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.
698

699
# Alphabetically sorted list of Non standard 32 bit platforms
700

701
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
715
	select GPIOLIB
716 717 718 719 720 721 722
	---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.

736
config SCHED_OMIT_FRAME_POINTER
737 738
	def_bool y
	prompt "Single-depth WCHAN output"
739
	depends on X86
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	---help---
741 742 743 744 745 746 747
	  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---
751 752 753
	  Say Y here to enable options for running Linux under various hyper-
	  visors. This option enables basic hypervisor detection and platform
	  setup.
754

755 756
	  If you say N, all options in this submenu will be skipped and
	  disabled, and Linux guest support won't be built in.
757

758
if HYPERVISOR_GUEST
759

760 761
config PARAVIRT
	bool "Enable paravirtualization code"
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	---help---
763 764 765 766 767
	  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.

768 769 770
config PARAVIRT_XXL
	bool

771 772 773 774 775 776 777
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.

778 779
config PARAVIRT_SPINLOCKS
	bool "Paravirtualization layer for spinlocks"
780
	depends on PARAVIRT && SMP
781 782 783 784 785
	---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).

786 787
	  It has a minimal impact on native kernels and gives a nice performance
	  benefit on paravirtualized KVM / Xen kernels.
788

789
	  If you are unsure how to answer this question, answer Y.
790

791 792 793
config X86_HV_CALLBACK_VECTOR
	def_bool n

794
source "arch/x86/xen/Kconfig"
795

796 797 798 799
config KVM_GUEST
	bool "KVM Guest support (including kvmclock)"
	depends on PARAVIRT
	select PARAVIRT_CLOCK
800
	select ARCH_CPUIDLE_HALTPOLL
801
	default y
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	---help---
803 804 805 806 807
	  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
808

809 810 811 812 813 814
config ARCH_CPUIDLE_HALTPOLL
        def_bool n
        prompt "Disable host haltpoll when loading haltpoll driver"
        help
	  If virtualized under KVM, disable host haltpoll.

815 816 817 818 819 820
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.

821 822 823 824 825 826 827 828
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.

829 830 831
config PARAVIRT_TIME_ACCOUNTING
	bool "Paravirtual steal time accounting"
	depends on PARAVIRT
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	---help---
833 834 835 836 837 838 839 840 841
	  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
842

843 844
config JAILHOUSE_GUEST
	bool "Jailhouse non-root cell support"
845
	depends on X86_64 && PCI
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	select X86_PM_TIMER
847 848 849 850 851
	---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.

852 853 854
config ACRN_GUEST
	bool "ACRN Guest support"
	depends on X86_64
855
	select X86_HV_CALLBACK_VECTOR
856 857 858 859 860 861 862
	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/.

863
endif #HYPERVISOR_GUEST
864

865 866 867
source "arch/x86/Kconfig.cpu"

config HPET_TIMER
868
	def_bool X86_64
869
	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.
879

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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.
883

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	  Choose N to continue using the legacy 8254 timer.
885 886

config HPET_EMULATE_RTC
887
	def_bool y
888
	depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
889

890
config APB_TIMER
891 892
       def_bool y if X86_INTEL_MID
       prompt "Intel MID APB Timer Support" if X86_INTEL_MID
893
       select DW_APB_TIMER
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       depends on X86_INTEL_MID && SFI
895 896 897 898 899 900 901
       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.

902
# Mark as expert because too many people got it wrong.
903
# The code disables itself when not needed.
904 905
config DMI
	default y
906
	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
907
	bool "Enable DMI scanning" if EXPERT
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	---help---
909 910 911 912 913
	  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.

914
config GART_IOMMU
915
	bool "Old AMD GART IOMMU support"
916
	select IOMMU_HELPER
917
	select SWIOTLB
918
	depends on X86_64 && PCI && AMD_NB
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	---help---
920 921 922 923 924 925 926 927 928 929 930 931 932 933 934
	  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.
935

936
config MAXSMP
937
	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
938
	depends on X86_64 && SMP && DEBUG_KERNEL
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	select CPUMASK_OFFSTACK
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	---help---
941
	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
942
	  If unsure, say N.
943

944 945 946 947 948 949 950 951 952 953 954 955 956 957 958
#
# 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
959
	int
960 961 962
	default NR_CPUS_RANGE_END if MAXSMP
	default    1 if !SMP
	default    2
963

964
config NR_CPUS_RANGE_END
965
	int
966 967 968 969
	depends on X86_32
	default   64 if  SMP &&  X86_BIGSMP
	default    8 if  SMP && !X86_BIGSMP
	default    1 if !SMP
970

971
config NR_CPUS_RANGE_END
972
	int
973
	depends on X86_64
974 975
	default 8192 if  SMP && CPUMASK_OFFSTACK
	default  512 if  SMP && !CPUMASK_OFFSTACK
976
	default    1 if !SMP
977

978
config NR_CPUS_DEFAULT
979 980
	int
	depends on X86_32
981 982 983
	default   32 if  X86_BIGSMP
	default    8 if  SMP
	default    1 if !SMP
984

985
config NR_CPUS_DEFAULT
986 987
	int
	depends on X86_64
988 989 990
	default 8192 if  MAXSMP
	default   64 if  SMP
	default    1 if !SMP
991

992
config NR_CPUS
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	int "Maximum number of CPUs" if SMP && !MAXSMP
994 995
	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
	default NR_CPUS_DEFAULT
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	---help---
997
	  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
999
	  supported value is 8192, otherwise the maximum value is 512.  The
1000 1001
	  minimum value which makes sense is 2.

1002 1003
	  This is purely to save memory: each supported CPU adds about 8KB
	  to the kernel image.
1004 1005

config SCHED_SMT
1006
	def_bool y if SMP
1007 1008

config SCHED_MC
1009 1010
	def_bool y
	prompt "Multi-core scheduler support"
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	depends on SMP
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	---help---
1013 1014 1015 1016
	  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.

1017 1018
config SCHED_MC_PRIO
	bool "CPU core priorities scheduler support"
1019 1020 1021
	depends on SCHED_MC && CPU_SUP_INTEL
	select X86_INTEL_PSTATE
	select CPU_FREQ
1022
	default y
1023
	---help---
1024 1025 1026 1027
	  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.
1028

1029 1030 1031 1032
	  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.
1033

1034
	  This feature will have no effect on CPUs without this feature.
1035

1036
	  If unsure say Y here.
1037

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config UP_LATE_INIT
       def_bool y
1040
       depends on !SMP && X86_LOCAL_APIC
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1041

1042
config X86_UP_APIC
1043 1044
	bool "Local APIC support on uniprocessors" if !PCI_MSI
	default PCI_MSI
1045
	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
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1046
	---help---
1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058
	  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---
1060 1061 1062 1063 1064 1065 1066 1067 1068
	  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
1069
	def_bool y
1070
	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1071
	select IRQ_DOMAIN_HIERARCHY
1072
	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1073 1074

config X86_IO_APIC
1075 1076
	def_bool y
	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1077

1078 1079 1080
config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
	bool "Reroute for broken boot IRQs"
	depends on X86_IO_APIC
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	---help---
1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
	  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.

1101
config X86_MCE
1102
	bool "Machine Check / overheating reporting"
1103
	select GENERIC_ALLOCATOR
1104
	default y
1105
	---help---
1106 1107
	  Machine Check support allows the processor to notify the
	  kernel if it detects a problem (e.g. overheating, data corruption).
1108
	  The action the kernel takes depends on the severity of the problem,
1109
	  ranging from warning messages to halting the machine.
1110

1111 1112 1113 1114 1115 1116 1117 1118
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.

1119
config X86_MCE_INTEL
1120 1121
	def_bool y
	prompt "Intel MCE features"
1122
	depends on X86_MCE && X86_LOCAL_APIC
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	---help---
1124 1125 1126 1127
	   Additional support for intel specific MCE features such as
	   the thermal monitor.

config X86_MCE_AMD
1128 1129
	def_bool y
	prompt "AMD MCE features"
1130
	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
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	---help---
1132 1133 1134
	   Additional support for AMD specific MCE features such as
	   the DRAM Error Threshold.

1135
config X86_ANCIENT_MCE
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	bool "Support for old Pentium 5 / WinChip machine checks"
1137
	depends on X86_32 && X86_MCE
1138 1139
	---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
1141
	  line.
1142

1143 1144
config X86_MCE_THRESHOLD
	depends on X86_MCE_AMD || X86_MCE_INTEL
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	def_bool y
1146

1147
config X86_MCE_INJECT
1148
	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1149 1150 1151 1152 1153 1154
	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.

1155 1156
config X86_THERMAL_VECTOR
	def_bool y
1157
	depends on X86_MCE_INTEL
1158

1159
source "arch/x86/events/Kconfig"
1160

1161
config X86_LEGACY_VM86
1162
	bool "Legacy VM86 support"
1163
	depends on X86_32
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	---help---
1165 1166 1167 1168 1169 1170 1171 1172
	  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
1173 1174 1175 1176
	  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.
1177

1178 1179 1180 1181
	  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.
1182

1183 1184
	  Enabling this option increases the complexity of the kernel
	  and slows down exception handling a tiny bit.
1185

1186
	  If unsure, say N here.
1187 1188 1189 1190

config VM86
       bool
       default X86_LEGACY_VM86
1191 1192 1193 1194

config X86_16BIT
	bool "Enable support for 16-bit segments" if EXPERT
	default y
1195
	depends on MODIFY_LDT_SYSCALL
1196 1197 1198 1199 1200 1201 1202 1203 1204
	---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
1205

1206 1207
config X86_ESPFIX64
	def_bool y
1208
	depends on X86_16BIT && X86_64
1209

1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
config X86_VSYSCALL_EMULATION
       bool "Enable vsyscall emulation" if EXPERT
       default y
       depends on X86_64
       ---help---
	 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.

1228 1229
config X86_IOPL_IOPERM
	bool "IOPERM and IOPL Emulation"
1230
	default y
1231
	---help---
1232 1233 1234
	  This enables the ioperm() and iopl() syscalls which are necessary
	  for legacy applications.

1235 1236 1237 1238 1239 1240 1241 1242
	  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
1243 1244
	  ability to disable interrupts from user space which would be
	  granted if the hardware IOPL mechanism would be used.
1245

1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262
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
1263
	tristate "Dell i8k legacy laptop support"
1264
	select HWMON
1265
	select SENSORS_DELL_SMM
1266
	---help---
1267 1268 1269 1270 1271 1272 1273 1274 1275
	  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.
1276 1277 1278
	  Say N otherwise.

config X86_REBOOTFIXUPS
1279 1280
	bool "Enable X86 board specific fixups for reboot"
	depends on X86_32
1281 1282 1283 1284 1285 1286 1287 1288
	---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
1289
	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1290 1291 1292 1293 1294 1295

	  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
1296 1297
	bool "CPU microcode loading support"
	default y
1298
	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1299 1300 1301
	select FW_LOADER
	---help---
	  If you say Y here, you will be able to update the microcode on
1302 1303 1304 1305 1306 1307 1308
	  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
1309
	  in Documentation/x86/microcode.rst. For that you need to enable
1310 1311 1312
	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
	  initrd for microcode blobs.

1313 1314 1315
	  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.
1316

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config MICROCODE_INTEL
1318
	bool "Intel microcode loading support"
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	depends on MICROCODE
	default MICROCODE
	select FW_LOADER
	---help---
	  This options enables microcode patch loading support for Intel
	  processors.

1326 1327 1328
	  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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1330
config MICROCODE_AMD
1331
	bool "AMD microcode loading support"
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1332 1333 1334 1335 1336
	depends on MICROCODE
	select FW_LOADER
	---help---
	  If you select this option, microcode patch loading support for AMD
	  processors will be enabled.
1337

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1338
config MICROCODE_OLD_INTERFACE
1339 1340
	bool "Ancient loading interface (DEPRECATED)"
	default n
1341
	depends on MICROCODE
1342 1343 1344 1345 1346 1347
	---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
1348
	  builtin microcode by now: Documentation/x86/microcode.rst
1349 1350 1351

config X86_MSR
	tristate "/dev/cpu/*/msr - Model-specific register support"
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	---help---
1353 1354 1355 1356 1357 1358 1359 1360
	  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---
1362 1363 1364 1365 1366 1367 1368
	  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
1370 1371 1372 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
	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---
1411 1412 1413 1414 1415
	  Select this if you have a 32-bit processor and between 1 and 4
	  gigabytes of physical RAM.

config HIGHMEM64G
	bool "64GB"
1416
	depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1417
	select X86_PAE
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	---help---
1419 1420 1421 1422 1423 1424
	  Select this if you have a 32-bit processor and more than 4
	  gigabytes of physical RAM.

endchoice

choice
1425
	prompt "Memory split" if EXPERT
1426 1427
	default VMSPLIT_3G
	depends on X86_32
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	---help---
1429 1430 1431 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
	  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
1468
	def_bool y
1469 1470 1471
	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)

config X86_PAE
1472
	bool "PAE (Physical Address Extension) Support"
1473
	depends on X86_32 && !HIGHMEM4G
1474
	select PHYS_ADDR_T_64BIT
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	select SWIOTLB
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1476
	---help---
1477 1478 1479 1480 1481
	  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.

1482 1483
config X86_5LEVEL
	bool "Enable 5-level page tables support"
1484
	default y
1485
	select DYNAMIC_MEMORY_LAYOUT
1486
	select SPARSEMEM_VMEMMAP
1487 1488 1489 1490 1491 1492 1493 1494
	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.

1495 1496
	  A kernel with the option enabled can be booted on machines that
	  support 4- or 5-level paging.
1497

1498
	  See Documentation/x86/x86_64/5level-paging.rst for more
1499 1500 1501 1502
	  information.

	  Say N if unsure.

1503
config X86_DIRECT_GBPAGES
1504
	def_bool y
1505
	depends on X86_64
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1506
	---help---
1507 1508 1509 1510
	  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.
1511

1512 1513 1514 1515 1516
config X86_CPA_STATISTICS
	bool "Enable statistic for Change Page Attribute"
	depends on DEBUG_FS
	---help---
	  Expose statistics about the Change Page Attribute mechanims, which
1517
	  helps to determine the effectiveness of preserving large and huge
1518 1519
	  page mappings when mapping protections are changed.

1520 1521 1522
config AMD_MEM_ENCRYPT
	bool "AMD Secure Memory Encryption (SME) support"
	depends on X86_64 && CPU_SUP_AMD
1523
	select DYNAMIC_PHYSICAL_MASK
1524
	select ARCH_USE_MEMREMAP_PROT
1525
	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544
	---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.

1545 1546
# Common NUMA Features
config NUMA
1547
	bool "Numa Memory Allocation and Scheduler Support"
1548
	depends on SMP
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1549 1550
	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
	default y if X86_BIGSMP
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1551
	---help---
1552
	  Enable NUMA (Non Uniform Memory Access) support.
1553

1554 1555 1556 1557
	  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.

1558
	  For 64-bit this is recommended if the system is Intel Core i7
1559 1560
	  (or later), AMD Opteron, or EM64T NUMA.

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	  For 32-bit this is only needed if you boot a 32-bit
1562
	  kernel on a 64-bit NUMA platform.
1563 1564

	  Otherwise, you should say N.
1565

1566
config AMD_NUMA
1567 1568
	def_bool y
	prompt "Old style AMD Opteron NUMA detection"
1569
	depends on X86_64 && NUMA && PCI
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1570
	---help---
1571 1572 1573 1574 1575
	  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.
1576 1577

config X86_64_ACPI_NUMA
1578 1579
	def_bool y
	prompt "ACPI NUMA detection"
1580 1581
	depends on X86_64 && NUMA && ACPI && PCI
	select ACPI_NUMA
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	---help---
1583 1584
	  Enable ACPI SRAT based node topology detection.

1585 1586 1587 1588 1589 1590 1591 1592 1593
# 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

1594 1595
config NUMA_EMU
	bool "NUMA emulation"
1596
	depends on NUMA
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1597
	---help---
1598 1599 1600 1601 1602
	  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
1603
	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1604 1605
	range 1 10
	default "10" if MAXSMP
1606 1607 1608
	default "6" if X86_64
	default "3"
	depends on NEED_MULTIPLE_NODES
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1609
	---help---
1610
	  Specify the maximum number of NUMA Nodes available on the target
1611
	  system.  Increases memory reserved to accommodate various tables.
1612 1613

config ARCH_HAVE_MEMORY_PRESENT
1614
	def_bool y
1615 1616 1617 1618
	depends on X86_32 && DISCONTIGMEM

config ARCH_FLATMEM_ENABLE
	def_bool y
1619
	depends on X86_32 && !NUMA
1620 1621

config ARCH_DISCONTIGMEM_ENABLE
1622
	def_bool n
1623
	depends on NUMA && X86_32
1624
	depends on BROKEN
1625

1626 1627
config ARCH_SPARSEMEM_ENABLE
	def_bool y
1628
	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1629 1630 1631
	select SPARSEMEM_STATIC if X86_32
	select SPARSEMEM_VMEMMAP_ENABLE if X86_64

1632
config ARCH_SPARSEMEM_DEFAULT
1633
	def_bool X86_64 || (NUMA && X86_32)
1634

1635 1636
config ARCH_SELECT_MEMORY_MODEL
	def_bool y
1637
	depends on ARCH_SPARSEMEM_ENABLE
1638 1639

config ARCH_MEMORY_PROBE
1640
	bool "Enable sysfs memory/probe interface"
1641
	depends on X86_64 && MEMORY_HOTPLUG
1642 1643
	help
	  This option enables a sysfs memory/probe interface for testing.
1644
	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1645
	  If you are unsure how to answer this question, answer N.
1646

1647 1648 1649 1650
config ARCH_PROC_KCORE_TEXT
	def_bool y
	depends on X86_64 && PROC_KCORE

1651 1652 1653 1654 1655
config ILLEGAL_POINTER_VALUE
       hex
       default 0 if X86_32
       default 0xdead000000000000 if X86_64

1656 1657 1658
config X86_PMEM_LEGACY_DEVICE
	bool

1659
config X86_PMEM_LEGACY
1660
	tristate "Support non-standard NVDIMMs and ADR protected memory"
1661 1662
	depends on PHYS_ADDR_T_64BIT
	depends on BLK_DEV
1663
	select X86_PMEM_LEGACY_DEVICE
1664
	select LIBNVDIMM
1665 1666 1667 1668 1669 1670 1671 1672
	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.

1673 1674
config HIGHPTE
	bool "Allocate 3rd-level pagetables from highmem"
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1675
	depends on HIGHMEM
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1676
	---help---
1677 1678 1679 1680 1681
	  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.

1682
config X86_CHECK_BIOS_CORRUPTION
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1683 1684 1685 1686 1687 1688 1689 1690 1691
	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
1692
	  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.
1703

1704
config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
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	bool "Set the default setting of memory_corruption_check"
1706 1707
	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.
1711

1712
config X86_RESERVE_LOW
1713 1714 1715
	int "Amount of low memory, in kilobytes, to reserve for the BIOS"
	default 64
	range 4 640
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	---help---
1717 1718 1719 1720 1721 1722 1723 1724 1725
	  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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1727 1728 1729 1730 1731
	  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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1733 1734 1735 1736 1737
	  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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1739
	  Leave this to the default value of 64 if you are unsure.
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1741 1742
config MATH_EMULATION
	bool
1743
	depends on MODIFY_LDT_SYSCALL
1744
	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768
	---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
1770
	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1771 1772 1773 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
	---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.

1801
	  See <file:Documentation/x86/mtrr.rst> for more information.
1802

1803
config MTRR_SANITIZER
1804
	def_bool y
1805 1806
	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.
1810

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	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1812
	  The largest mtrr entry size for a continuous block can be set with
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	  mtrr_chunk_size.
1814

1815
	  If unsure, say Y.
1816 1817

config MTRR_SANITIZER_ENABLE_DEFAULT
1818 1819 1820
	int "MTRR cleanup enable value (0-1)"
	range 0 1
	default "0"
1821
	depends on MTRR_SANITIZER
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	---help---
1823
	  Enable mtrr cleanup default value
1824

1825 1826 1827 1828 1829
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---
1831
	  mtrr cleanup spare entries default, it can be changed via
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	  mtrr_spare_reg_nr=N on the kernel command line.
1833

1834
config X86_PAT
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	def_bool y
1836
	prompt "x86 PAT support" if EXPERT
1837
	depends on MTRR
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	---help---
1839
	  Use PAT attributes to setup page level cache control.
1840

1841 1842 1843 1844
	  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,
1845
	  spontaneous reboots) or a non-working video driver.
1846 1847 1848

	  If unsure, say Y.

1849 1850 1851 1852
config ARCH_USES_PG_UNCACHED
	def_bool y
	depends on X86_PAT

1853 1854 1855 1856 1857 1858 1859 1860 1861
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.

1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872
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.

1873
config X86_UMIP
1874
	def_bool y
1875 1876 1877 1878 1879 1880 1881 1882
	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.
1883 1884 1885 1886 1887

	  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.
1888

1889 1890 1891
config X86_INTEL_MPX
	prompt "Intel MPX (Memory Protection Extensions)"
	def_bool n
1892 1893 1894
	# Note: only available in 64-bit mode due to VMA flags shortage
	depends on CPU_SUP_INTEL && X86_64
	select ARCH_USES_HIGH_VMA_FLAGS
1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912
	---help---
	  MPX provides hardware features that can be used in
	  conjunction with compiler-instrumented code to check
	  memory references.  It is designed to detect buffer
	  overflow or underflow bugs.

	  This option enables running applications which are
	  instrumented or otherwise use MPX.  It does not use MPX
	  itself inside the kernel or to protect the kernel
	  against bad memory references.

	  Enabling this option will make the kernel larger:
	  ~8k of kernel text and 36 bytes of data on a 64-bit
	  defconfig.  It adds a long to the 'mm_struct' which
	  will increase the kernel memory overhead of each
	  process and adds some branches to paths used during
	  exec() and munmap().

1913
	  For details, see Documentation/x86/intel_mpx.rst
1914 1915 1916

	  If unsure, say N.

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config X86_INTEL_MEMORY_PROTECTION_KEYS
1918
	prompt "Intel Memory Protection Keys"
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	def_bool y
1920
	# Note: only available in 64-bit mode
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	depends on CPU_SUP_INTEL && X86_64
1922 1923
	select ARCH_USES_HIGH_VMA_FLAGS
	select ARCH_HAS_PKEYS
1924 1925 1926 1927 1928
	---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.

1929
	  For details, see Documentation/core-api/protection-keys.rst
1930 1931

	  If unsure, say y.
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1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977
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

1978
config EFI
1979
	bool "EFI runtime service support"
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	depends on ACPI
1981
	select UCS2_STRING
1982
	select EFI_RUNTIME_WRAPPERS
1983
	---help---
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	  This enables the kernel to use EFI runtime services that are
	  available (such as the EFI variable services).
1986

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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.
1993

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config EFI_STUB
       bool "EFI stub support"
1996
       depends on EFI && !X86_USE_3DNOW
1997
       select RELOCATABLE
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       ---help---
          This kernel feature allows a bzImage to be loaded directly
	  by EFI firmware without the use of a bootloader.

2002
	  See Documentation/admin-guide/efi-stub.rst for more information.
2003

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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.

2018
config SECCOMP
2019 2020
	def_bool y
	prompt "Enable seccomp to safely compute untrusted bytecode"
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	---help---
2022 2023 2024 2025 2026 2027
	  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
2028
	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2029 2030 2031 2032 2033
	  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.

2034
source "kernel/Kconfig.hz"
2035 2036 2037

config KEXEC
	bool "kexec system call"
2038
	select KEXEC_CORE
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	---help---
2040 2041 2042 2043 2044 2045 2046 2047 2048
	  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
2049 2050 2051
	  initially work for you.  As of this writing the exact hardware
	  interface is strongly in flux, so no good recommendation can be
	  made.
2052

2053 2054
config KEXEC_FILE
	bool "kexec file based system call"
2055
	select KEXEC_CORE
2056 2057 2058 2059 2060 2061 2062 2063 2064 2065
	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.

2066 2067 2068
config ARCH_HAS_KEXEC_PURGATORY
	def_bool KEXEC_FILE

2069
config KEXEC_SIG
2070
	bool "Verify kernel signature during kexec_file_load() syscall"
2071
	depends on KEXEC_FILE
2072
	---help---
2073

2074 2075 2076 2077 2078 2079
	  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
2080 2081
	  verification for the corresponding kernel image type being
	  loaded in order for this to work.
2082

2083 2084 2085 2086 2087 2088 2089
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.

2090 2091
config KEXEC_BZIMAGE_VERIFY_SIG
	bool "Enable bzImage signature verification support"
2092
	depends on KEXEC_SIG
2093 2094 2095 2096 2097
	depends on SIGNED_PE_FILE_VERIFICATION
	select SYSTEM_TRUSTED_KEYRING
	---help---
	  Enable bzImage signature verification support.

2098
config CRASH_DUMP
2099
	bool "kernel crash dumps"
2100
	depends on X86_64 || (X86_32 && HIGHMEM)
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	---help---
2102 2103 2104 2105 2106 2107 2108 2109
	  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).
2110
	  For more details see Documentation/admin-guide/kdump/kdump.rst
2111

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config KEXEC_JUMP
2113
	bool "kexec jump"
2114
	depends on KEXEC && HIBERNATION
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	---help---
2116 2117
	  Jump between original kernel and kexeced kernel and invoke
	  code in physical address mode via KEXEC
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2119
config PHYSICAL_START
2120
	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2121
	default "0x1000000"
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	---help---
2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139
	  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.

2140 2141 2142 2143 2144 2145 2146
	  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
2147
	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2148
	  for more details about crash dumps.
2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160

	  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
2161 2162
	bool "Build a relocatable kernel"
	default y
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	---help---
2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174
	  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
2175
	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2176

2177
config RANDOMIZE_BASE
2178
	bool "Randomize the address of the kernel image (KASLR)"
2179
	depends on RELOCATABLE
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	default y
2181
	---help---
2182 2183 2184 2185 2186 2187 2188
	  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.

2189 2190 2191 2192 2193 2194 2195 2196 2197 2198
	  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).
2199 2200 2201 2202

	  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
2203 2204 2205 2206 2207 2208
	  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.
2209

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	  If unsure, say Y.
2211 2212

# Relocation on x86 needs some additional build support
2213 2214
config X86_NEED_RELOCS
	def_bool y
2215
	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2216

2217
config PHYSICAL_ALIGN
2218
	hex "Alignment value to which kernel should be aligned"
2219
	default "0x200000"
2220 2221
	range 0x2000 0x1000000 if X86_32
	range 0x200000 0x1000000 if X86_64
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	---help---
2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238
	  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.

2239 2240 2241
	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
	  this value must be a multiple of 0x200000.

2242 2243
	  Don't change this unless you know what you are doing.

2244 2245 2246 2247 2248 2249
config DYNAMIC_MEMORY_LAYOUT
	bool
	---help---
	  This option makes base addresses of vmalloc and vmemmap as well as
	  __PAGE_OFFSET movable during boot.

2250 2251 2252 2253
config RANDOMIZE_MEMORY
	bool "Randomize the kernel memory sections"
	depends on X86_64
	depends on RANDOMIZE_BASE
2254
	select DYNAMIC_MEMORY_LAYOUT
2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265
	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.
2267

2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282
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.

2283
config HOTPLUG_CPU
2284
	def_bool y
2285
	depends on SMP
2286

2287 2288
config BOOTPARAM_HOTPLUG_CPU0
	bool "Set default setting of cpu0_hotpluggable"
2289
	depends on HOTPLUG_CPU
2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314
	---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"
2318
	depends on HOTPLUG_CPU
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2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329
	---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.

2330
config COMPAT_VDSO
2331 2332
	def_bool n
	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2333
	depends on COMPAT_32
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	---help---
2335 2336 2337
	  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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2339 2340 2341 2342 2343
	  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".
2344

2345 2346 2347 2348 2349 2350 2351 2352 2353
	  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.
2354

2355 2356 2357
choice
	prompt "vsyscall table for legacy applications"
	depends on X86_64
2358
	default LEGACY_VSYSCALL_XONLY
2359 2360 2361 2362 2363 2364 2365
	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
2366
	  line parameter vsyscall=[emulate|xonly|none].
2367 2368 2369 2370 2371

	  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.

2372
	  If unsure, select "Emulate execution only".
2373 2374

	config LEGACY_VSYSCALL_EMULATE
2375
		bool "Full emulation"
2376
		help
2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397
		  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.
2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409

	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

2410 2411
config CMDLINE_BOOL
	bool "Built-in kernel command line"
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	---help---
2413 2414 2415 2416 2417 2418 2419 2420
	  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
2421
	  boot arguments in CONFIG_CMDLINE.
2422 2423 2424 2425 2426 2427 2428 2429

	  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---
2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445
	  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---
2447 2448 2449 2450 2451 2452
	  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.

2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468
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.

2469 2470
source "kernel/livepatch/Kconfig"

2471 2472
endmenu

2473 2474 2475 2476
config ARCH_HAS_ADD_PAGES
	def_bool y
	depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG

2477 2478 2479 2480
config ARCH_ENABLE_MEMORY_HOTPLUG
	def_bool y
	depends on X86_64 || (X86_32 && HIGHMEM)

2481 2482 2483 2484
config ARCH_ENABLE_MEMORY_HOTREMOVE
	def_bool y
	depends on MEMORY_HOTPLUG

2485
config USE_PERCPU_NUMA_NODE_ID
2486
	def_bool y
2487 2488
	depends on NUMA

2489 2490 2491 2492
config ARCH_ENABLE_SPLIT_PMD_PTLOCK
	def_bool y
	depends on X86_64 || X86_PAE

2493 2494 2495 2496
config ARCH_ENABLE_HUGEPAGE_MIGRATION
	def_bool y
	depends on X86_64 && HUGETLB_PAGE && MIGRATION

2497 2498 2499 2500
config ARCH_ENABLE_THP_MIGRATION
	def_bool y
	depends on X86_64 && TRANSPARENT_HUGEPAGE

2501
menu "Power management and ACPI options"
2502 2503

config ARCH_HIBERNATION_HEADER
2504
	def_bool y
2505
	depends on HIBERNATION
2506 2507 2508 2509 2510

source "kernel/power/Kconfig"

source "drivers/acpi/Kconfig"

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2511 2512
source "drivers/sfi/Kconfig"

2513
config X86_APM_BOOT
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2514
	def_bool y
2515
	depends on APM
2516

2517 2518
menuconfig APM
	tristate "APM (Advanced Power Management) BIOS support"
2519
	depends on X86_32 && PM_SLEEP
2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534
	---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
2535
	  and more information, read <file:Documentation/power/apm-acpi.rst>
2536
	  and the Battery Powered Linux mini-HOWTO, available from
2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579
	  <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---
2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602
	  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
2603
	depends on CPU_IDLE
2604
	bool "Make CPU Idle calls when idle"
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2605
	---help---
2606 2607 2608 2609 2610 2611 2612 2613 2614 2615
	  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"
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2616
	---help---
2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628
	  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"
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Ingo Molnar 已提交
2629
	---help---
2630 2631 2632 2633 2634 2635 2636 2637 2638
	  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

2639
source "drivers/cpufreq/Kconfig"
2640 2641 2642

source "drivers/cpuidle/Kconfig"

A
Andy Henroid 已提交
2643 2644
source "drivers/idle/Kconfig"

2645 2646 2647 2648 2649 2650 2651
endmenu


menu "Bus options (PCI etc.)"

choice
	prompt "PCI access mode"
2652
	depends on X86_32 && PCI
2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677
	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"

2678
config PCI_GOOLPC
2679
	bool "OLPC XO-1"
2680 2681
	depends on OLPC

2682 2683 2684
config PCI_GOANY
	bool "Any"

2685 2686 2687
endchoice

config PCI_BIOS
2688
	def_bool y
2689
	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2690 2691 2692

# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
config PCI_DIRECT
2693
	def_bool y
2694
	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2695 2696

config PCI_MMCONFIG
2697 2698
	bool "Support mmconfig PCI config space access" if X86_64
	default y
2699
	depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2700
	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2701

2702
config PCI_OLPC
2703 2704
	def_bool y
	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2705

2706 2707 2708 2709 2710
config PCI_XEN
	def_bool y
	depends on PCI && XEN
	select SWIOTLB_XEN

2711 2712 2713
config MMCONF_FAM10H
	def_bool y
	depends on X86_64 && PCI_MMCONFIG && ACPI
2714

2715
config PCI_CNB20LE_QUIRK
2716
	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2717
	depends on PCI
2718 2719 2720 2721 2722
	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.

2723 2724 2725 2726 2727
	  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.

2728
config ISA_BUS
2729
	bool "ISA bus support on modern systems" if EXPERT
2730
	help
2731 2732 2733 2734 2735
	  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.
2736 2737 2738

	  If unsure, say N.

2739
# x86_64 have no ISA slots, but can have ISA-style DMA.
2740
config ISA_DMA_API
2741 2742 2743 2744 2745
	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.
2746

2747 2748
if X86_32

2749 2750
config ISA
	bool "ISA support"
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2751
	---help---
2752 2753 2754 2755 2756 2757 2758 2759
	  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
2760
	---help---
2761 2762 2763 2764 2765 2766 2767 2768 2769
	  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
2770
	depends on SCx200
2771
	default y
I
Ingo Molnar 已提交
2772
	---help---
2773 2774 2775 2776 2777 2778
	  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.

2779 2780
config OLPC
	bool "One Laptop Per Child support"
2781
	depends on !X86_PAE
2782
	select GPIOLIB
2783
	select OF
2784
	select OF_PROMTREE
2785
	select IRQ_DOMAIN
2786
	select OLPC_EC
I
Ingo Molnar 已提交
2787
	---help---
2788 2789 2790
	  Add support for detecting the unique features of the OLPC
	  XO hardware.

2791 2792
config OLPC_XO1_PM
	bool "OLPC XO-1 Power Management"
2793
	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2794
	---help---
2795
	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2796

D
Daniel Drake 已提交
2797 2798 2799 2800 2801 2802 2803
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.

2804 2805
config OLPC_XO1_SCI
	bool "OLPC XO-1 SCI extras"
2806
	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2807
	depends on INPUT=y
2808
	select POWER_SUPPLY
2809 2810
	---help---
	  Add support for SCI-based features of the OLPC XO-1 laptop:
2811
	   - EC-driven system wakeups
2812
	   - Power button
2813
	   - Ebook switch
2814
	   - Lid switch
2815 2816
	   - AC adapter status updates
	   - Battery status updates
2817

D
Daniel Drake 已提交
2818 2819
config OLPC_XO15_SCI
	bool "OLPC XO-1.5 SCI extras"
2820 2821
	depends on OLPC && ACPI
	select POWER_SUPPLY
D
Daniel Drake 已提交
2822 2823 2824 2825 2826
	---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
2827

2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841
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.

2842 2843 2844 2845 2846 2847
config NET5501
	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
	select GPIOLIB
	---help---
	  This option enables system support for the Soekris Engineering net5501.

2848 2849 2850 2851 2852 2853 2854
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.

2855 2856 2857 2858 2859 2860 2861 2862 2863
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.

2864 2865
endif # X86_32

2866
config AMD_NB
2867
	def_bool y
2868
	depends on CPU_SUP_AMD && PCI
2869

2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880
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
2881
	  modes, it is advertised as fallback platform framebuffer so legacy
2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895
	  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.

2896 2897 2898
endmenu


2899
menu "Binary Emulations"
2900 2901 2902 2903

config IA32_EMULATION
	bool "IA32 Emulation"
	depends on X86_64
2904
	select ARCH_WANT_OLD_COMPAT_IPC
2905
	select BINFMT_ELF
R
Roland McGrath 已提交
2906
	select COMPAT_BINFMT_ELF
2907
	select COMPAT_OLD_SIGACTION
I
Ingo Molnar 已提交
2908
	---help---
H
H. J. Lu 已提交
2909 2910 2911
	  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.
2912 2913

config IA32_AOUT
I
Ingo Molnar 已提交
2914 2915
	tristate "IA32 a.out support"
	depends on IA32_EMULATION
B
Borislav Petkov 已提交
2916
	depends on BROKEN
I
Ingo Molnar 已提交
2917 2918
	---help---
	  Support old a.out binaries in the 32bit emulation.
2919

2920
config X86_X32
2921
	bool "x32 ABI for 64-bit mode"
2922
	depends on X86_64
H
H. J. Lu 已提交
2923 2924 2925 2926 2927 2928 2929 2930 2931 2932
	---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.

2933 2934 2935 2936 2937 2938
config COMPAT_32
	def_bool y
	depends on IA32_EMULATION || X86_32
	select HAVE_UID16
	select OLD_SIGSUSPEND3

2939
config COMPAT
2940
	def_bool y
2941
	depends on IA32_EMULATION || X86_X32
2942

2943
if COMPAT
2944
config COMPAT_FOR_U64_ALIGNMENT
2945
	def_bool y
2946 2947

config SYSVIPC_COMPAT
2948
	def_bool y
2949 2950
	depends on SYSVIPC
endif
2951

2952 2953 2954
endmenu


K
Keith Packard 已提交
2955 2956 2957 2958
config HAVE_ATOMIC_IOMAP
	def_bool y
	depends on X86_32

2959 2960
config X86_DEV_DMA_OPS
	bool
2961

2962 2963
source "drivers/firmware/Kconfig"

2964
source "arch/x86/kvm/Kconfig"