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0001 # SPDX-License-Identifier: GPL-2.0
0002 # Select 32 or 64 bit
0003 config 64BIT
0004         bool "64-bit kernel" if "$(ARCH)" = "x86"
0005         default "$(ARCH)" != "i386"
0006         help
0007           Say yes to build a 64-bit kernel - formerly known as x86_64
0008           Say no to build a 32-bit kernel - formerly known as i386
0009 
0010 config X86_32
0011         def_bool y
0012         depends on !64BIT
0013         # Options that are inherently 32-bit kernel only:
0014         select ARCH_WANT_IPC_PARSE_VERSION
0015         select CLKSRC_I8253
0016         select CLONE_BACKWARDS
0017         select GENERIC_VDSO_32
0018         select HAVE_DEBUG_STACKOVERFLOW
0019         select KMAP_LOCAL
0020         select MODULES_USE_ELF_REL
0021         select OLD_SIGACTION
0022         select ARCH_SPLIT_ARG64
0023 
0024 config X86_64
0025         def_bool y
0026         depends on 64BIT
0027         # Options that are inherently 64-bit kernel only:
0028         select ARCH_HAS_GIGANTIC_PAGE
0029         select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
0030         select ARCH_USE_CMPXCHG_LOCKREF
0031         select HAVE_ARCH_SOFT_DIRTY
0032         select MODULES_USE_ELF_RELA
0033         select NEED_DMA_MAP_STATE
0034         select SWIOTLB
0035         select ARCH_HAS_ELFCORE_COMPAT
0036         select ZONE_DMA32
0037 
0038 config FORCE_DYNAMIC_FTRACE
0039         def_bool y
0040         depends on X86_32
0041         depends on FUNCTION_TRACER
0042         select DYNAMIC_FTRACE
0043         help
0044           We keep the static function tracing (!DYNAMIC_FTRACE) around
0045           in order to test the non static function tracing in the
0046           generic code, as other architectures still use it. But we
0047           only need to keep it around for x86_64. No need to keep it
0048           for x86_32. For x86_32, force DYNAMIC_FTRACE.
0049 #
0050 # Arch settings
0051 #
0052 # ( Note that options that are marked 'if X86_64' could in principle be
0053 #   ported to 32-bit as well. )
0054 #
0055 config X86
0056         def_bool y
0057         #
0058         # Note: keep this list sorted alphabetically
0059         #
0060         select ACPI_LEGACY_TABLES_LOOKUP        if ACPI
0061         select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
0062         select ARCH_32BIT_OFF_T                 if X86_32
0063         select ARCH_CLOCKSOURCE_INIT
0064         select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
0065         select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
0066         select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
0067         select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
0068         select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
0069         select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
0070         select ARCH_HAS_ACPI_TABLE_UPGRADE      if ACPI
0071         select ARCH_HAS_CACHE_LINE_SIZE
0072         select ARCH_HAS_CURRENT_STACK_POINTER
0073         select ARCH_HAS_DEBUG_VIRTUAL
0074         select ARCH_HAS_DEBUG_VM_PGTABLE        if !X86_PAE
0075         select ARCH_HAS_DEVMEM_IS_ALLOWED
0076         select ARCH_HAS_EARLY_DEBUG             if KGDB
0077         select ARCH_HAS_ELF_RANDOMIZE
0078         select ARCH_HAS_FAST_MULTIPLIER
0079         select ARCH_HAS_FORTIFY_SOURCE
0080         select ARCH_HAS_GCOV_PROFILE_ALL
0081         select ARCH_HAS_KCOV                    if X86_64
0082         select ARCH_HAS_MEM_ENCRYPT
0083         select ARCH_HAS_MEMBARRIER_SYNC_CORE
0084         select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
0085         select ARCH_HAS_PMEM_API                if X86_64
0086         select ARCH_HAS_PTE_DEVMAP              if X86_64
0087         select ARCH_HAS_PTE_SPECIAL
0088         select ARCH_HAS_UACCESS_FLUSHCACHE      if X86_64
0089         select ARCH_HAS_COPY_MC                 if X86_64
0090         select ARCH_HAS_SET_MEMORY
0091         select ARCH_HAS_SET_DIRECT_MAP
0092         select ARCH_HAS_STRICT_KERNEL_RWX
0093         select ARCH_HAS_STRICT_MODULE_RWX
0094         select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
0095         select ARCH_HAS_SYSCALL_WRAPPER
0096         select ARCH_HAS_UBSAN_SANITIZE_ALL
0097         select ARCH_HAS_DEBUG_WX
0098         select ARCH_HAS_ZONE_DMA_SET if EXPERT
0099         select ARCH_HAVE_NMI_SAFE_CMPXCHG
0100         select ARCH_MIGHT_HAVE_ACPI_PDC         if ACPI
0101         select ARCH_MIGHT_HAVE_PC_PARPORT
0102         select ARCH_MIGHT_HAVE_PC_SERIO
0103         select ARCH_STACKWALK
0104         select ARCH_SUPPORTS_ACPI
0105         select ARCH_SUPPORTS_ATOMIC_RMW
0106         select ARCH_SUPPORTS_DEBUG_PAGEALLOC
0107         select ARCH_SUPPORTS_PAGE_TABLE_CHECK   if X86_64
0108         select ARCH_SUPPORTS_NUMA_BALANCING     if X86_64
0109         select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP       if NR_CPUS <= 4096
0110         select ARCH_SUPPORTS_LTO_CLANG
0111         select ARCH_SUPPORTS_LTO_CLANG_THIN
0112         select ARCH_USE_BUILTIN_BSWAP
0113         select ARCH_USE_MEMTEST
0114         select ARCH_USE_QUEUED_RWLOCKS
0115         select ARCH_USE_QUEUED_SPINLOCKS
0116         select ARCH_USE_SYM_ANNOTATIONS
0117         select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
0118         select ARCH_WANT_DEFAULT_BPF_JIT        if X86_64
0119         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
0120         select ARCH_WANTS_NO_INSTR
0121         select ARCH_WANT_GENERAL_HUGETLB
0122         select ARCH_WANT_HUGE_PMD_SHARE
0123         select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP  if X86_64
0124         select ARCH_WANT_LD_ORPHAN_WARN
0125         select ARCH_WANTS_THP_SWAP              if X86_64
0126         select ARCH_HAS_PARANOID_L1D_FLUSH
0127         select BUILDTIME_TABLE_SORT
0128         select CLKEVT_I8253
0129         select CLOCKSOURCE_VALIDATE_LAST_CYCLE
0130         select CLOCKSOURCE_WATCHDOG
0131         select DCACHE_WORD_ACCESS
0132         select DYNAMIC_SIGFRAME
0133         select EDAC_ATOMIC_SCRUB
0134         select EDAC_SUPPORT
0135         select GENERIC_CLOCKEVENTS_BROADCAST    if X86_64 || (X86_32 && X86_LOCAL_APIC)
0136         select GENERIC_CLOCKEVENTS_MIN_ADJUST
0137         select GENERIC_CMOS_UPDATE
0138         select GENERIC_CPU_AUTOPROBE
0139         select GENERIC_CPU_VULNERABILITIES
0140         select GENERIC_EARLY_IOREMAP
0141         select GENERIC_ENTRY
0142         select GENERIC_IOMAP
0143         select GENERIC_IRQ_EFFECTIVE_AFF_MASK   if SMP
0144         select GENERIC_IRQ_MATRIX_ALLOCATOR     if X86_LOCAL_APIC
0145         select GENERIC_IRQ_MIGRATION            if SMP
0146         select GENERIC_IRQ_PROBE
0147         select GENERIC_IRQ_RESERVATION_MODE
0148         select GENERIC_IRQ_SHOW
0149         select GENERIC_PENDING_IRQ              if SMP
0150         select GENERIC_PTDUMP
0151         select GENERIC_SMP_IDLE_THREAD
0152         select GENERIC_TIME_VSYSCALL
0153         select GENERIC_GETTIMEOFDAY
0154         select GENERIC_VDSO_TIME_NS
0155         select GUP_GET_PTE_LOW_HIGH             if X86_PAE
0156         select HARDIRQS_SW_RESEND
0157         select HARDLOCKUP_CHECK_TIMESTAMP       if X86_64
0158         select HAVE_ACPI_APEI                   if ACPI
0159         select HAVE_ACPI_APEI_NMI               if ACPI
0160         select HAVE_ALIGNED_STRUCT_PAGE         if SLUB
0161         select HAVE_ARCH_AUDITSYSCALL
0162         select HAVE_ARCH_HUGE_VMAP              if X86_64 || X86_PAE
0163         select HAVE_ARCH_HUGE_VMALLOC           if X86_64
0164         select HAVE_ARCH_JUMP_LABEL
0165         select HAVE_ARCH_JUMP_LABEL_RELATIVE
0166         select HAVE_ARCH_KASAN                  if X86_64
0167         select HAVE_ARCH_KASAN_VMALLOC          if X86_64
0168         select HAVE_ARCH_KFENCE
0169         select HAVE_ARCH_KGDB
0170         select HAVE_ARCH_MMAP_RND_BITS          if MMU
0171         select HAVE_ARCH_MMAP_RND_COMPAT_BITS   if MMU && COMPAT
0172         select HAVE_ARCH_COMPAT_MMAP_BASES      if MMU && COMPAT
0173         select HAVE_ARCH_PREL32_RELOCATIONS
0174         select HAVE_ARCH_SECCOMP_FILTER
0175         select HAVE_ARCH_THREAD_STRUCT_WHITELIST
0176         select HAVE_ARCH_STACKLEAK
0177         select HAVE_ARCH_TRACEHOOK
0178         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
0179         select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
0180         select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
0181         select HAVE_ARCH_USERFAULTFD_MINOR      if X86_64 && USERFAULTFD
0182         select HAVE_ARCH_VMAP_STACK             if X86_64
0183         select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
0184         select HAVE_ARCH_WITHIN_STACK_FRAMES
0185         select HAVE_ASM_MODVERSIONS
0186         select HAVE_CMPXCHG_DOUBLE
0187         select HAVE_CMPXCHG_LOCAL
0188         select HAVE_CONTEXT_TRACKING_USER               if X86_64
0189         select HAVE_CONTEXT_TRACKING_USER_OFFSTACK      if HAVE_CONTEXT_TRACKING_USER
0190         select HAVE_C_RECORDMCOUNT
0191         select HAVE_OBJTOOL_MCOUNT              if HAVE_OBJTOOL
0192         select HAVE_BUILDTIME_MCOUNT_SORT
0193         select HAVE_DEBUG_KMEMLEAK
0194         select HAVE_DMA_CONTIGUOUS
0195         select HAVE_DYNAMIC_FTRACE
0196         select HAVE_DYNAMIC_FTRACE_WITH_REGS
0197         select HAVE_DYNAMIC_FTRACE_WITH_ARGS    if X86_64
0198         select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
0199         select HAVE_SAMPLE_FTRACE_DIRECT        if X86_64
0200         select HAVE_SAMPLE_FTRACE_DIRECT_MULTI  if X86_64
0201         select HAVE_EBPF_JIT
0202         select HAVE_EFFICIENT_UNALIGNED_ACCESS
0203         select HAVE_EISA
0204         select HAVE_EXIT_THREAD
0205         select HAVE_FAST_GUP
0206         select HAVE_FENTRY                      if X86_64 || DYNAMIC_FTRACE
0207         select HAVE_FTRACE_MCOUNT_RECORD
0208         select HAVE_FUNCTION_GRAPH_TRACER       if X86_32 || (X86_64 && DYNAMIC_FTRACE)
0209         select HAVE_FUNCTION_TRACER
0210         select HAVE_GCC_PLUGINS
0211         select HAVE_HW_BREAKPOINT
0212         select HAVE_IOREMAP_PROT
0213         select HAVE_IRQ_EXIT_ON_IRQ_STACK       if X86_64
0214         select HAVE_IRQ_TIME_ACCOUNTING
0215         select HAVE_JUMP_LABEL_HACK             if HAVE_OBJTOOL
0216         select HAVE_KERNEL_BZIP2
0217         select HAVE_KERNEL_GZIP
0218         select HAVE_KERNEL_LZ4
0219         select HAVE_KERNEL_LZMA
0220         select HAVE_KERNEL_LZO
0221         select HAVE_KERNEL_XZ
0222         select HAVE_KERNEL_ZSTD
0223         select HAVE_KPROBES
0224         select HAVE_KPROBES_ON_FTRACE
0225         select HAVE_FUNCTION_ERROR_INJECTION
0226         select HAVE_KRETPROBES
0227         select HAVE_RETHOOK
0228         select HAVE_KVM
0229         select HAVE_LIVEPATCH                   if X86_64
0230         select HAVE_MIXED_BREAKPOINTS_REGS
0231         select HAVE_MOD_ARCH_SPECIFIC
0232         select HAVE_MOVE_PMD
0233         select HAVE_MOVE_PUD
0234         select HAVE_NOINSTR_HACK                if HAVE_OBJTOOL
0235         select HAVE_NMI
0236         select HAVE_NOINSTR_VALIDATION          if HAVE_OBJTOOL
0237         select HAVE_OBJTOOL                     if X86_64
0238         select HAVE_OPTPROBES
0239         select HAVE_PCSPKR_PLATFORM
0240         select HAVE_PERF_EVENTS
0241         select HAVE_PERF_EVENTS_NMI
0242         select HAVE_HARDLOCKUP_DETECTOR_PERF    if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
0243         select HAVE_PCI
0244         select HAVE_PERF_REGS
0245         select HAVE_PERF_USER_STACK_DUMP
0246         select MMU_GATHER_RCU_TABLE_FREE        if PARAVIRT
0247         select MMU_GATHER_MERGE_VMAS
0248         select HAVE_POSIX_CPU_TIMERS_TASK_WORK
0249         select HAVE_REGS_AND_STACK_ACCESS_API
0250         select HAVE_RELIABLE_STACKTRACE         if UNWINDER_ORC || STACK_VALIDATION
0251         select HAVE_FUNCTION_ARG_ACCESS_API
0252         select HAVE_SETUP_PER_CPU_AREA
0253         select HAVE_SOFTIRQ_ON_OWN_STACK
0254         select HAVE_STACKPROTECTOR              if CC_HAS_SANE_STACKPROTECTOR
0255         select HAVE_STACK_VALIDATION            if HAVE_OBJTOOL
0256         select HAVE_STATIC_CALL
0257         select HAVE_STATIC_CALL_INLINE          if HAVE_OBJTOOL
0258         select HAVE_PREEMPT_DYNAMIC_CALL
0259         select HAVE_RSEQ
0260         select HAVE_SYSCALL_TRACEPOINTS
0261         select HAVE_UACCESS_VALIDATION          if HAVE_OBJTOOL
0262         select HAVE_UNSTABLE_SCHED_CLOCK
0263         select HAVE_USER_RETURN_NOTIFIER
0264         select HAVE_GENERIC_VDSO
0265         select HOTPLUG_SMT                      if SMP
0266         select IRQ_FORCED_THREADING
0267         select NEED_PER_CPU_EMBED_FIRST_CHUNK
0268         select NEED_PER_CPU_PAGE_FIRST_CHUNK
0269         select NEED_SG_DMA_LENGTH
0270         select PCI_DOMAINS                      if PCI
0271         select PCI_LOCKLESS_CONFIG              if PCI
0272         select PERF_EVENTS
0273         select RTC_LIB
0274         select RTC_MC146818_LIB
0275         select SPARSE_IRQ
0276         select SRCU
0277         select SYSCTL_EXCEPTION_TRACE
0278         select THREAD_INFO_IN_TASK
0279         select TRACE_IRQFLAGS_SUPPORT
0280         select TRACE_IRQFLAGS_NMI_SUPPORT
0281         select USER_STACKTRACE_SUPPORT
0282         select HAVE_ARCH_KCSAN                  if X86_64
0283         select X86_FEATURE_NAMES                if PROC_FS
0284         select PROC_PID_ARCH_STATUS             if PROC_FS
0285         select HAVE_ARCH_NODE_DEV_GROUP         if X86_SGX
0286         imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
0287 
0288 config INSTRUCTION_DECODER
0289         def_bool y
0290         depends on KPROBES || PERF_EVENTS || UPROBES
0291 
0292 config OUTPUT_FORMAT
0293         string
0294         default "elf32-i386" if X86_32
0295         default "elf64-x86-64" if X86_64
0296 
0297 config LOCKDEP_SUPPORT
0298         def_bool y
0299 
0300 config STACKTRACE_SUPPORT
0301         def_bool y
0302 
0303 config MMU
0304         def_bool y
0305 
0306 config ARCH_MMAP_RND_BITS_MIN
0307         default 28 if 64BIT
0308         default 8
0309 
0310 config ARCH_MMAP_RND_BITS_MAX
0311         default 32 if 64BIT
0312         default 16
0313 
0314 config ARCH_MMAP_RND_COMPAT_BITS_MIN
0315         default 8
0316 
0317 config ARCH_MMAP_RND_COMPAT_BITS_MAX
0318         default 16
0319 
0320 config SBUS
0321         bool
0322 
0323 config GENERIC_ISA_DMA
0324         def_bool y
0325         depends on ISA_DMA_API
0326 
0327 config GENERIC_BUG
0328         def_bool y
0329         depends on BUG
0330         select GENERIC_BUG_RELATIVE_POINTERS if X86_64
0331 
0332 config GENERIC_BUG_RELATIVE_POINTERS
0333         bool
0334 
0335 config ARCH_MAY_HAVE_PC_FDC
0336         def_bool y
0337         depends on ISA_DMA_API
0338 
0339 config GENERIC_CALIBRATE_DELAY
0340         def_bool y
0341 
0342 config ARCH_HAS_CPU_RELAX
0343         def_bool y
0344 
0345 config ARCH_HIBERNATION_POSSIBLE
0346         def_bool y
0347 
0348 config ARCH_NR_GPIO
0349         int
0350         default 1024 if X86_64
0351         default 512
0352 
0353 config ARCH_SUSPEND_POSSIBLE
0354         def_bool y
0355 
0356 config AUDIT_ARCH
0357         def_bool y if X86_64
0358 
0359 config KASAN_SHADOW_OFFSET
0360         hex
0361         depends on KASAN
0362         default 0xdffffc0000000000
0363 
0364 config HAVE_INTEL_TXT
0365         def_bool y
0366         depends on INTEL_IOMMU && ACPI
0367 
0368 config X86_32_SMP
0369         def_bool y
0370         depends on X86_32 && SMP
0371 
0372 config X86_64_SMP
0373         def_bool y
0374         depends on X86_64 && SMP
0375 
0376 config ARCH_SUPPORTS_UPROBES
0377         def_bool y
0378 
0379 config FIX_EARLYCON_MEM
0380         def_bool y
0381 
0382 config DYNAMIC_PHYSICAL_MASK
0383         bool
0384 
0385 config PGTABLE_LEVELS
0386         int
0387         default 5 if X86_5LEVEL
0388         default 4 if X86_64
0389         default 3 if X86_PAE
0390         default 2
0391 
0392 config CC_HAS_SANE_STACKPROTECTOR
0393         bool
0394         default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
0395         default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
0396         help
0397           We have to make sure stack protector is unconditionally disabled if
0398           the compiler produces broken code or if it does not let us control
0399           the segment on 32-bit kernels.
0400 
0401 menu "Processor type and features"
0402 
0403 config SMP
0404         bool "Symmetric multi-processing support"
0405         help
0406           This enables support for systems with more than one CPU. If you have
0407           a system with only one CPU, say N. If you have a system with more
0408           than one CPU, say Y.
0409 
0410           If you say N here, the kernel will run on uni- and multiprocessor
0411           machines, but will use only one CPU of a multiprocessor machine. If
0412           you say Y here, the kernel will run on many, but not all,
0413           uniprocessor machines. On a uniprocessor machine, the kernel
0414           will run faster if you say N here.
0415 
0416           Note that if you say Y here and choose architecture "586" or
0417           "Pentium" under "Processor family", the kernel will not work on 486
0418           architectures. Similarly, multiprocessor kernels for the "PPro"
0419           architecture may not work on all Pentium based boards.
0420 
0421           People using multiprocessor machines who say Y here should also say
0422           Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
0423           Management" code will be disabled if you say Y here.
0424 
0425           See also <file:Documentation/x86/i386/IO-APIC.rst>,
0426           <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
0427           <http://www.tldp.org/docs.html#howto>.
0428 
0429           If you don't know what to do here, say N.
0430 
0431 config X86_FEATURE_NAMES
0432         bool "Processor feature human-readable names" if EMBEDDED
0433         default y
0434         help
0435           This option compiles in a table of x86 feature bits and corresponding
0436           names.  This is required to support /proc/cpuinfo and a few kernel
0437           messages.  You can disable this to save space, at the expense of
0438           making those few kernel messages show numeric feature bits instead.
0439 
0440           If in doubt, say Y.
0441 
0442 config X86_X2APIC
0443         bool "Support x2apic"
0444         depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
0445         help
0446           This enables x2apic support on CPUs that have this feature.
0447 
0448           This allows 32-bit apic IDs (so it can support very large systems),
0449           and accesses the local apic via MSRs not via mmio.
0450 
0451           If you don't know what to do here, say N.
0452 
0453 config X86_MPPARSE
0454         bool "Enable MPS table" if ACPI
0455         default y
0456         depends on X86_LOCAL_APIC
0457         help
0458           For old smp systems that do not have proper acpi support. Newer systems
0459           (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
0460 
0461 config GOLDFISH
0462         def_bool y
0463         depends on X86_GOLDFISH
0464 
0465 config X86_CPU_RESCTRL
0466         bool "x86 CPU resource control support"
0467         depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
0468         select KERNFS
0469         select PROC_CPU_RESCTRL         if PROC_FS
0470         help
0471           Enable x86 CPU resource control support.
0472 
0473           Provide support for the allocation and monitoring of system resources
0474           usage by the CPU.
0475 
0476           Intel calls this Intel Resource Director Technology
0477           (Intel(R) RDT). More information about RDT can be found in the
0478           Intel x86 Architecture Software Developer Manual.
0479 
0480           AMD calls this AMD Platform Quality of Service (AMD QoS).
0481           More information about AMD QoS can be found in the AMD64 Technology
0482           Platform Quality of Service Extensions manual.
0483 
0484           Say N if unsure.
0485 
0486 if X86_32
0487 config X86_BIGSMP
0488         bool "Support for big SMP systems with more than 8 CPUs"
0489         depends on SMP
0490         help
0491           This option is needed for the systems that have more than 8 CPUs.
0492 
0493 config X86_EXTENDED_PLATFORM
0494         bool "Support for extended (non-PC) x86 platforms"
0495         default y
0496         help
0497           If you disable this option then the kernel will only support
0498           standard PC platforms. (which covers the vast majority of
0499           systems out there.)
0500 
0501           If you enable this option then you'll be able to select support
0502           for the following (non-PC) 32 bit x86 platforms:
0503                 Goldfish (Android emulator)
0504                 AMD Elan
0505                 RDC R-321x SoC
0506                 SGI 320/540 (Visual Workstation)
0507                 STA2X11-based (e.g. Northville)
0508                 Moorestown MID devices
0509 
0510           If you have one of these systems, or if you want to build a
0511           generic distribution kernel, say Y here - otherwise say N.
0512 endif # X86_32
0513 
0514 if X86_64
0515 config X86_EXTENDED_PLATFORM
0516         bool "Support for extended (non-PC) x86 platforms"
0517         default y
0518         help
0519           If you disable this option then the kernel will only support
0520           standard PC platforms. (which covers the vast majority of
0521           systems out there.)
0522 
0523           If you enable this option then you'll be able to select support
0524           for the following (non-PC) 64 bit x86 platforms:
0525                 Numascale NumaChip
0526                 ScaleMP vSMP
0527                 SGI Ultraviolet
0528 
0529           If you have one of these systems, or if you want to build a
0530           generic distribution kernel, say Y here - otherwise say N.
0531 endif # X86_64
0532 # This is an alphabetically sorted list of 64 bit extended platforms
0533 # Please maintain the alphabetic order if and when there are additions
0534 config X86_NUMACHIP
0535         bool "Numascale NumaChip"
0536         depends on X86_64
0537         depends on X86_EXTENDED_PLATFORM
0538         depends on NUMA
0539         depends on SMP
0540         depends on X86_X2APIC
0541         depends on PCI_MMCONFIG
0542         help
0543           Adds support for Numascale NumaChip large-SMP systems. Needed to
0544           enable more than ~168 cores.
0545           If you don't have one of these, you should say N here.
0546 
0547 config X86_VSMP
0548         bool "ScaleMP vSMP"
0549         select HYPERVISOR_GUEST
0550         select PARAVIRT
0551         depends on X86_64 && PCI
0552         depends on X86_EXTENDED_PLATFORM
0553         depends on SMP
0554         help
0555           Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
0556           supposed to run on these EM64T-based machines.  Only choose this option
0557           if you have one of these machines.
0558 
0559 config X86_UV
0560         bool "SGI Ultraviolet"
0561         depends on X86_64
0562         depends on X86_EXTENDED_PLATFORM
0563         depends on NUMA
0564         depends on EFI
0565         depends on KEXEC_CORE
0566         depends on X86_X2APIC
0567         depends on PCI
0568         help
0569           This option is needed in order to support SGI Ultraviolet systems.
0570           If you don't have one of these, you should say N here.
0571 
0572 # Following is an alphabetically sorted list of 32 bit extended platforms
0573 # Please maintain the alphabetic order if and when there are additions
0574 
0575 config X86_GOLDFISH
0576         bool "Goldfish (Virtual Platform)"
0577         depends on X86_EXTENDED_PLATFORM
0578         help
0579           Enable support for the Goldfish virtual platform used primarily
0580           for Android development. Unless you are building for the Android
0581           Goldfish emulator say N here.
0582 
0583 config X86_INTEL_CE
0584         bool "CE4100 TV platform"
0585         depends on PCI
0586         depends on PCI_GODIRECT
0587         depends on X86_IO_APIC
0588         depends on X86_32
0589         depends on X86_EXTENDED_PLATFORM
0590         select X86_REBOOTFIXUPS
0591         select OF
0592         select OF_EARLY_FLATTREE
0593         help
0594           Select for the Intel CE media processor (CE4100) SOC.
0595           This option compiles in support for the CE4100 SOC for settop
0596           boxes and media devices.
0597 
0598 config X86_INTEL_MID
0599         bool "Intel MID platform support"
0600         depends on X86_EXTENDED_PLATFORM
0601         depends on X86_PLATFORM_DEVICES
0602         depends on PCI
0603         depends on X86_64 || (PCI_GOANY && X86_32)
0604         depends on X86_IO_APIC
0605         select I2C
0606         select DW_APB_TIMER
0607         select INTEL_SCU_PCI
0608         help
0609           Select to build a kernel capable of supporting Intel MID (Mobile
0610           Internet Device) platform systems which do not have the PCI legacy
0611           interfaces. If you are building for a PC class system say N here.
0612 
0613           Intel MID platforms are based on an Intel processor and chipset which
0614           consume less power than most of the x86 derivatives.
0615 
0616 config X86_INTEL_QUARK
0617         bool "Intel Quark platform support"
0618         depends on X86_32
0619         depends on X86_EXTENDED_PLATFORM
0620         depends on X86_PLATFORM_DEVICES
0621         depends on X86_TSC
0622         depends on PCI
0623         depends on PCI_GOANY
0624         depends on X86_IO_APIC
0625         select IOSF_MBI
0626         select INTEL_IMR
0627         select COMMON_CLK
0628         help
0629           Select to include support for Quark X1000 SoC.
0630           Say Y here if you have a Quark based system such as the Arduino
0631           compatible Intel Galileo.
0632 
0633 config X86_INTEL_LPSS
0634         bool "Intel Low Power Subsystem Support"
0635         depends on X86 && ACPI && PCI
0636         select COMMON_CLK
0637         select PINCTRL
0638         select IOSF_MBI
0639         help
0640           Select to build support for Intel Low Power Subsystem such as
0641           found on Intel Lynxpoint PCH. Selecting this option enables
0642           things like clock tree (common clock framework) and pincontrol
0643           which are needed by the LPSS peripheral drivers.
0644 
0645 config X86_AMD_PLATFORM_DEVICE
0646         bool "AMD ACPI2Platform devices support"
0647         depends on ACPI
0648         select COMMON_CLK
0649         select PINCTRL
0650         help
0651           Select to interpret AMD specific ACPI device to platform device
0652           such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
0653           I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
0654           implemented under PINCTRL subsystem.
0655 
0656 config IOSF_MBI
0657         tristate "Intel SoC IOSF Sideband support for SoC platforms"
0658         depends on PCI
0659         help
0660           This option enables sideband register access support for Intel SoC
0661           platforms. On these platforms the IOSF sideband is used in lieu of
0662           MSR's for some register accesses, mostly but not limited to thermal
0663           and power. Drivers may query the availability of this device to
0664           determine if they need the sideband in order to work on these
0665           platforms. The sideband is available on the following SoC products.
0666           This list is not meant to be exclusive.
0667            - BayTrail
0668            - Braswell
0669            - Quark
0670 
0671           You should say Y if you are running a kernel on one of these SoC's.
0672 
0673 config IOSF_MBI_DEBUG
0674         bool "Enable IOSF sideband access through debugfs"
0675         depends on IOSF_MBI && DEBUG_FS
0676         help
0677           Select this option to expose the IOSF sideband access registers (MCR,
0678           MDR, MCRX) through debugfs to write and read register information from
0679           different units on the SoC. This is most useful for obtaining device
0680           state information for debug and analysis. As this is a general access
0681           mechanism, users of this option would have specific knowledge of the
0682           device they want to access.
0683 
0684           If you don't require the option or are in doubt, say N.
0685 
0686 config X86_RDC321X
0687         bool "RDC R-321x SoC"
0688         depends on X86_32
0689         depends on X86_EXTENDED_PLATFORM
0690         select M486
0691         select X86_REBOOTFIXUPS
0692         help
0693           This option is needed for RDC R-321x system-on-chip, also known
0694           as R-8610-(G).
0695           If you don't have one of these chips, you should say N here.
0696 
0697 config X86_32_NON_STANDARD
0698         bool "Support non-standard 32-bit SMP architectures"
0699         depends on X86_32 && SMP
0700         depends on X86_EXTENDED_PLATFORM
0701         help
0702           This option compiles in the bigsmp and STA2X11 default
0703           subarchitectures.  It is intended for a generic binary
0704           kernel. If you select them all, kernel will probe it one by
0705           one and will fallback to default.
0706 
0707 # Alphabetically sorted list of Non standard 32 bit platforms
0708 
0709 config X86_SUPPORTS_MEMORY_FAILURE
0710         def_bool y
0711         # MCE code calls memory_failure():
0712         depends on X86_MCE
0713         # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
0714         # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
0715         depends on X86_64 || !SPARSEMEM
0716         select ARCH_SUPPORTS_MEMORY_FAILURE
0717 
0718 config STA2X11
0719         bool "STA2X11 Companion Chip Support"
0720         depends on X86_32_NON_STANDARD && PCI
0721         select SWIOTLB
0722         select MFD_STA2X11
0723         select GPIOLIB
0724         help
0725           This adds support for boards based on the STA2X11 IO-Hub,
0726           a.k.a. "ConneXt". The chip is used in place of the standard
0727           PC chipset, so all "standard" peripherals are missing. If this
0728           option is selected the kernel will still be able to boot on
0729           standard PC machines.
0730 
0731 config X86_32_IRIS
0732         tristate "Eurobraille/Iris poweroff module"
0733         depends on X86_32
0734         help
0735           The Iris machines from EuroBraille do not have APM or ACPI support
0736           to shut themselves down properly.  A special I/O sequence is
0737           needed to do so, which is what this module does at
0738           kernel shutdown.
0739 
0740           This is only for Iris machines from EuroBraille.
0741 
0742           If unused, say N.
0743 
0744 config SCHED_OMIT_FRAME_POINTER
0745         def_bool y
0746         prompt "Single-depth WCHAN output"
0747         depends on X86
0748         help
0749           Calculate simpler /proc/<PID>/wchan values. If this option
0750           is disabled then wchan values will recurse back to the
0751           caller function. This provides more accurate wchan values,
0752           at the expense of slightly more scheduling overhead.
0753 
0754           If in doubt, say "Y".
0755 
0756 menuconfig HYPERVISOR_GUEST
0757         bool "Linux guest support"
0758         help
0759           Say Y here to enable options for running Linux under various hyper-
0760           visors. This option enables basic hypervisor detection and platform
0761           setup.
0762 
0763           If you say N, all options in this submenu will be skipped and
0764           disabled, and Linux guest support won't be built in.
0765 
0766 if HYPERVISOR_GUEST
0767 
0768 config PARAVIRT
0769         bool "Enable paravirtualization code"
0770         depends on HAVE_STATIC_CALL
0771         help
0772           This changes the kernel so it can modify itself when it is run
0773           under a hypervisor, potentially improving performance significantly
0774           over full virtualization.  However, when run without a hypervisor
0775           the kernel is theoretically slower and slightly larger.
0776 
0777 config PARAVIRT_XXL
0778         bool
0779 
0780 config PARAVIRT_DEBUG
0781         bool "paravirt-ops debugging"
0782         depends on PARAVIRT && DEBUG_KERNEL
0783         help
0784           Enable to debug paravirt_ops internals.  Specifically, BUG if
0785           a paravirt_op is missing when it is called.
0786 
0787 config PARAVIRT_SPINLOCKS
0788         bool "Paravirtualization layer for spinlocks"
0789         depends on PARAVIRT && SMP
0790         help
0791           Paravirtualized spinlocks allow a pvops backend to replace the
0792           spinlock implementation with something virtualization-friendly
0793           (for example, block the virtual CPU rather than spinning).
0794 
0795           It has a minimal impact on native kernels and gives a nice performance
0796           benefit on paravirtualized KVM / Xen kernels.
0797 
0798           If you are unsure how to answer this question, answer Y.
0799 
0800 config X86_HV_CALLBACK_VECTOR
0801         def_bool n
0802 
0803 source "arch/x86/xen/Kconfig"
0804 
0805 config KVM_GUEST
0806         bool "KVM Guest support (including kvmclock)"
0807         depends on PARAVIRT
0808         select PARAVIRT_CLOCK
0809         select ARCH_CPUIDLE_HALTPOLL
0810         select X86_HV_CALLBACK_VECTOR
0811         default y
0812         help
0813           This option enables various optimizations for running under the KVM
0814           hypervisor. It includes a paravirtualized clock, so that instead
0815           of relying on a PIT (or probably other) emulation by the
0816           underlying device model, the host provides the guest with
0817           timing infrastructure such as time of day, and system time
0818 
0819 config ARCH_CPUIDLE_HALTPOLL
0820         def_bool n
0821         prompt "Disable host haltpoll when loading haltpoll driver"
0822         help
0823           If virtualized under KVM, disable host haltpoll.
0824 
0825 config PVH
0826         bool "Support for running PVH guests"
0827         help
0828           This option enables the PVH entry point for guest virtual machines
0829           as specified in the x86/HVM direct boot ABI.
0830 
0831 config PARAVIRT_TIME_ACCOUNTING
0832         bool "Paravirtual steal time accounting"
0833         depends on PARAVIRT
0834         help
0835           Select this option to enable fine granularity task steal time
0836           accounting. Time spent executing other tasks in parallel with
0837           the current vCPU is discounted from the vCPU power. To account for
0838           that, there can be a small performance impact.
0839 
0840           If in doubt, say N here.
0841 
0842 config PARAVIRT_CLOCK
0843         bool
0844 
0845 config JAILHOUSE_GUEST
0846         bool "Jailhouse non-root cell support"
0847         depends on X86_64 && PCI
0848         select X86_PM_TIMER
0849         help
0850           This option allows to run Linux as guest in a Jailhouse non-root
0851           cell. You can leave this option disabled if you only want to start
0852           Jailhouse and run Linux afterwards in the root cell.
0853 
0854 config ACRN_GUEST
0855         bool "ACRN Guest support"
0856         depends on X86_64
0857         select X86_HV_CALLBACK_VECTOR
0858         help
0859           This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
0860           a flexible, lightweight reference open-source hypervisor, built with
0861           real-time and safety-criticality in mind. It is built for embedded
0862           IOT with small footprint and real-time features. More details can be
0863           found in https://projectacrn.org/.
0864 
0865 config INTEL_TDX_GUEST
0866         bool "Intel TDX (Trust Domain Extensions) - Guest Support"
0867         depends on X86_64 && CPU_SUP_INTEL
0868         depends on X86_X2APIC
0869         select ARCH_HAS_CC_PLATFORM
0870         select X86_MEM_ENCRYPT
0871         select X86_MCE
0872         help
0873           Support running as a guest under Intel TDX.  Without this support,
0874           the guest kernel can not boot or run under TDX.
0875           TDX includes memory encryption and integrity capabilities
0876           which protect the confidentiality and integrity of guest
0877           memory contents and CPU state. TDX guests are protected from
0878           some attacks from the VMM.
0879 
0880 endif # HYPERVISOR_GUEST
0881 
0882 source "arch/x86/Kconfig.cpu"
0883 
0884 config HPET_TIMER
0885         def_bool X86_64
0886         prompt "HPET Timer Support" if X86_32
0887         help
0888           Use the IA-PC HPET (High Precision Event Timer) to manage
0889           time in preference to the PIT and RTC, if a HPET is
0890           present.
0891           HPET is the next generation timer replacing legacy 8254s.
0892           The HPET provides a stable time base on SMP
0893           systems, unlike the TSC, but it is more expensive to access,
0894           as it is off-chip.  The interface used is documented
0895           in the HPET spec, revision 1.
0896 
0897           You can safely choose Y here.  However, HPET will only be
0898           activated if the platform and the BIOS support this feature.
0899           Otherwise the 8254 will be used for timing services.
0900 
0901           Choose N to continue using the legacy 8254 timer.
0902 
0903 config HPET_EMULATE_RTC
0904         def_bool y
0905         depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
0906 
0907 # Mark as expert because too many people got it wrong.
0908 # The code disables itself when not needed.
0909 config DMI
0910         default y
0911         select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
0912         bool "Enable DMI scanning" if EXPERT
0913         help
0914           Enabled scanning of DMI to identify machine quirks. Say Y
0915           here unless you have verified that your setup is not
0916           affected by entries in the DMI blacklist. Required by PNP
0917           BIOS code.
0918 
0919 config GART_IOMMU
0920         bool "Old AMD GART IOMMU support"
0921         select DMA_OPS
0922         select IOMMU_HELPER
0923         select SWIOTLB
0924         depends on X86_64 && PCI && AMD_NB
0925         help
0926           Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
0927           GART based hardware IOMMUs.
0928 
0929           The GART supports full DMA access for devices with 32-bit access
0930           limitations, on systems with more than 3 GB. This is usually needed
0931           for USB, sound, many IDE/SATA chipsets and some other devices.
0932 
0933           Newer systems typically have a modern AMD IOMMU, supported via
0934           the CONFIG_AMD_IOMMU=y config option.
0935 
0936           In normal configurations this driver is only active when needed:
0937           there's more than 3 GB of memory and the system contains a
0938           32-bit limited device.
0939 
0940           If unsure, say Y.
0941 
0942 config BOOT_VESA_SUPPORT
0943         bool
0944         help
0945           If true, at least one selected framebuffer driver can take advantage
0946           of VESA video modes set at an early boot stage via the vga= parameter.
0947 
0948 config MAXSMP
0949         bool "Enable Maximum number of SMP Processors and NUMA Nodes"
0950         depends on X86_64 && SMP && DEBUG_KERNEL
0951         select CPUMASK_OFFSTACK
0952         help
0953           Enable maximum number of CPUS and NUMA Nodes for this architecture.
0954           If unsure, say N.
0955 
0956 #
0957 # The maximum number of CPUs supported:
0958 #
0959 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
0960 # and which can be configured interactively in the
0961 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
0962 #
0963 # The ranges are different on 32-bit and 64-bit kernels, depending on
0964 # hardware capabilities and scalability features of the kernel.
0965 #
0966 # ( If MAXSMP is enabled we just use the highest possible value and disable
0967 #   interactive configuration. )
0968 #
0969 
0970 config NR_CPUS_RANGE_BEGIN
0971         int
0972         default NR_CPUS_RANGE_END if MAXSMP
0973         default    1 if !SMP
0974         default    2
0975 
0976 config NR_CPUS_RANGE_END
0977         int
0978         depends on X86_32
0979         default   64 if  SMP &&  X86_BIGSMP
0980         default    8 if  SMP && !X86_BIGSMP
0981         default    1 if !SMP
0982 
0983 config NR_CPUS_RANGE_END
0984         int
0985         depends on X86_64
0986         default 8192 if  SMP && CPUMASK_OFFSTACK
0987         default  512 if  SMP && !CPUMASK_OFFSTACK
0988         default    1 if !SMP
0989 
0990 config NR_CPUS_DEFAULT
0991         int
0992         depends on X86_32
0993         default   32 if  X86_BIGSMP
0994         default    8 if  SMP
0995         default    1 if !SMP
0996 
0997 config NR_CPUS_DEFAULT
0998         int
0999         depends on X86_64
1000         default 8192 if  MAXSMP
1001         default   64 if  SMP
1002         default    1 if !SMP
1003 
1004 config NR_CPUS
1005         int "Maximum number of CPUs" if SMP && !MAXSMP
1006         range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1007         default NR_CPUS_DEFAULT
1008         help
1009           This allows you to specify the maximum number of CPUs which this
1010           kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1011           supported value is 8192, otherwise the maximum value is 512.  The
1012           minimum value which makes sense is 2.
1013 
1014           This is purely to save memory: each supported CPU adds about 8KB
1015           to the kernel image.
1016 
1017 config SCHED_CLUSTER
1018         bool "Cluster scheduler support"
1019         depends on SMP
1020         default y
1021         help
1022           Cluster scheduler support improves the CPU scheduler's decision
1023           making when dealing with machines that have clusters of CPUs.
1024           Cluster usually means a couple of CPUs which are placed closely
1025           by sharing mid-level caches, last-level cache tags or internal
1026           busses.
1027 
1028 config SCHED_SMT
1029         def_bool y if SMP
1030 
1031 config SCHED_MC
1032         def_bool y
1033         prompt "Multi-core scheduler support"
1034         depends on SMP
1035         help
1036           Multi-core scheduler support improves the CPU scheduler's decision
1037           making when dealing with multi-core CPU chips at a cost of slightly
1038           increased overhead in some places. If unsure say N here.
1039 
1040 config SCHED_MC_PRIO
1041         bool "CPU core priorities scheduler support"
1042         depends on SCHED_MC && CPU_SUP_INTEL
1043         select X86_INTEL_PSTATE
1044         select CPU_FREQ
1045         default y
1046         help
1047           Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1048           core ordering determined at manufacturing time, which allows
1049           certain cores to reach higher turbo frequencies (when running
1050           single threaded workloads) than others.
1051 
1052           Enabling this kernel feature teaches the scheduler about
1053           the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1054           scheduler's CPU selection logic accordingly, so that higher
1055           overall system performance can be achieved.
1056 
1057           This feature will have no effect on CPUs without this feature.
1058 
1059           If unsure say Y here.
1060 
1061 config UP_LATE_INIT
1062         def_bool y
1063         depends on !SMP && X86_LOCAL_APIC
1064 
1065 config X86_UP_APIC
1066         bool "Local APIC support on uniprocessors" if !PCI_MSI
1067         default PCI_MSI
1068         depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1069         help
1070           A local APIC (Advanced Programmable Interrupt Controller) is an
1071           integrated interrupt controller in the CPU. If you have a single-CPU
1072           system which has a processor with a local APIC, you can say Y here to
1073           enable and use it. If you say Y here even though your machine doesn't
1074           have a local APIC, then the kernel will still run with no slowdown at
1075           all. The local APIC supports CPU-generated self-interrupts (timer,
1076           performance counters), and the NMI watchdog which detects hard
1077           lockups.
1078 
1079 config X86_UP_IOAPIC
1080         bool "IO-APIC support on uniprocessors"
1081         depends on X86_UP_APIC
1082         help
1083           An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1084           SMP-capable replacement for PC-style interrupt controllers. Most
1085           SMP systems and many recent uniprocessor systems have one.
1086 
1087           If you have a single-CPU system with an IO-APIC, you can say Y here
1088           to use it. If you say Y here even though your machine doesn't have
1089           an IO-APIC, then the kernel will still run with no slowdown at all.
1090 
1091 config X86_LOCAL_APIC
1092         def_bool y
1093         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1094         select IRQ_DOMAIN_HIERARCHY
1095         select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1096 
1097 config X86_IO_APIC
1098         def_bool y
1099         depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1100 
1101 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1102         bool "Reroute for broken boot IRQs"
1103         depends on X86_IO_APIC
1104         help
1105           This option enables a workaround that fixes a source of
1106           spurious interrupts. This is recommended when threaded
1107           interrupt handling is used on systems where the generation of
1108           superfluous "boot interrupts" cannot be disabled.
1109 
1110           Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1111           entry in the chipset's IO-APIC is masked (as, e.g. the RT
1112           kernel does during interrupt handling). On chipsets where this
1113           boot IRQ generation cannot be disabled, this workaround keeps
1114           the original IRQ line masked so that only the equivalent "boot
1115           IRQ" is delivered to the CPUs. The workaround also tells the
1116           kernel to set up the IRQ handler on the boot IRQ line. In this
1117           way only one interrupt is delivered to the kernel. Otherwise
1118           the spurious second interrupt may cause the kernel to bring
1119           down (vital) interrupt lines.
1120 
1121           Only affects "broken" chipsets. Interrupt sharing may be
1122           increased on these systems.
1123 
1124 config X86_MCE
1125         bool "Machine Check / overheating reporting"
1126         select GENERIC_ALLOCATOR
1127         default y
1128         help
1129           Machine Check support allows the processor to notify the
1130           kernel if it detects a problem (e.g. overheating, data corruption).
1131           The action the kernel takes depends on the severity of the problem,
1132           ranging from warning messages to halting the machine.
1133 
1134 config X86_MCELOG_LEGACY
1135         bool "Support for deprecated /dev/mcelog character device"
1136         depends on X86_MCE
1137         help
1138           Enable support for /dev/mcelog which is needed by the old mcelog
1139           userspace logging daemon. Consider switching to the new generation
1140           rasdaemon solution.
1141 
1142 config X86_MCE_INTEL
1143         def_bool y
1144         prompt "Intel MCE features"
1145         depends on X86_MCE && X86_LOCAL_APIC
1146         help
1147           Additional support for intel specific MCE features such as
1148           the thermal monitor.
1149 
1150 config X86_MCE_AMD
1151         def_bool y
1152         prompt "AMD MCE features"
1153         depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1154         help
1155           Additional support for AMD specific MCE features such as
1156           the DRAM Error Threshold.
1157 
1158 config X86_ANCIENT_MCE
1159         bool "Support for old Pentium 5 / WinChip machine checks"
1160         depends on X86_32 && X86_MCE
1161         help
1162           Include support for machine check handling on old Pentium 5 or WinChip
1163           systems. These typically need to be enabled explicitly on the command
1164           line.
1165 
1166 config X86_MCE_THRESHOLD
1167         depends on X86_MCE_AMD || X86_MCE_INTEL
1168         def_bool y
1169 
1170 config X86_MCE_INJECT
1171         depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1172         tristate "Machine check injector support"
1173         help
1174           Provide support for injecting machine checks for testing purposes.
1175           If you don't know what a machine check is and you don't do kernel
1176           QA it is safe to say n.
1177 
1178 source "arch/x86/events/Kconfig"
1179 
1180 config X86_LEGACY_VM86
1181         bool "Legacy VM86 support"
1182         depends on X86_32
1183         help
1184           This option allows user programs to put the CPU into V8086
1185           mode, which is an 80286-era approximation of 16-bit real mode.
1186 
1187           Some very old versions of X and/or vbetool require this option
1188           for user mode setting.  Similarly, DOSEMU will use it if
1189           available to accelerate real mode DOS programs.  However, any
1190           recent version of DOSEMU, X, or vbetool should be fully
1191           functional even without kernel VM86 support, as they will all
1192           fall back to software emulation. Nevertheless, if you are using
1193           a 16-bit DOS program where 16-bit performance matters, vm86
1194           mode might be faster than emulation and you might want to
1195           enable this option.
1196 
1197           Note that any app that works on a 64-bit kernel is unlikely to
1198           need this option, as 64-bit kernels don't, and can't, support
1199           V8086 mode. This option is also unrelated to 16-bit protected
1200           mode and is not needed to run most 16-bit programs under Wine.
1201 
1202           Enabling this option increases the complexity of the kernel
1203           and slows down exception handling a tiny bit.
1204 
1205           If unsure, say N here.
1206 
1207 config VM86
1208         bool
1209         default X86_LEGACY_VM86
1210 
1211 config X86_16BIT
1212         bool "Enable support for 16-bit segments" if EXPERT
1213         default y
1214         depends on MODIFY_LDT_SYSCALL
1215         help
1216           This option is required by programs like Wine to run 16-bit
1217           protected mode legacy code on x86 processors.  Disabling
1218           this option saves about 300 bytes on i386, or around 6K text
1219           plus 16K runtime memory on x86-64,
1220 
1221 config X86_ESPFIX32
1222         def_bool y
1223         depends on X86_16BIT && X86_32
1224 
1225 config X86_ESPFIX64
1226         def_bool y
1227         depends on X86_16BIT && X86_64
1228 
1229 config X86_VSYSCALL_EMULATION
1230         bool "Enable vsyscall emulation" if EXPERT
1231         default y
1232         depends on X86_64
1233         help
1234           This enables emulation of the legacy vsyscall page.  Disabling
1235           it is roughly equivalent to booting with vsyscall=none, except
1236           that it will also disable the helpful warning if a program
1237           tries to use a vsyscall.  With this option set to N, offending
1238           programs will just segfault, citing addresses of the form
1239           0xffffffffff600?00.
1240 
1241           This option is required by many programs built before 2013, and
1242           care should be used even with newer programs if set to N.
1243 
1244           Disabling this option saves about 7K of kernel size and
1245           possibly 4K of additional runtime pagetable memory.
1246 
1247 config X86_IOPL_IOPERM
1248         bool "IOPERM and IOPL Emulation"
1249         default y
1250         help
1251           This enables the ioperm() and iopl() syscalls which are necessary
1252           for legacy applications.
1253 
1254           Legacy IOPL support is an overbroad mechanism which allows user
1255           space aside of accessing all 65536 I/O ports also to disable
1256           interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1257           capabilities and permission from potentially active security
1258           modules.
1259 
1260           The emulation restricts the functionality of the syscall to
1261           only allowing the full range I/O port access, but prevents the
1262           ability to disable interrupts from user space which would be
1263           granted if the hardware IOPL mechanism would be used.
1264 
1265 config TOSHIBA
1266         tristate "Toshiba Laptop support"
1267         depends on X86_32
1268         help
1269           This adds a driver to safely access the System Management Mode of
1270           the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1271           not work on models with a Phoenix BIOS. The System Management Mode
1272           is used to set the BIOS and power saving options on Toshiba portables.
1273 
1274           For information on utilities to make use of this driver see the
1275           Toshiba Linux utilities web site at:
1276           <http://www.buzzard.org.uk/toshiba/>.
1277 
1278           Say Y if you intend to run this kernel on a Toshiba portable.
1279           Say N otherwise.
1280 
1281 config X86_REBOOTFIXUPS
1282         bool "Enable X86 board specific fixups for reboot"
1283         depends on X86_32
1284         help
1285           This enables chipset and/or board specific fixups to be done
1286           in order to get reboot to work correctly. This is only needed on
1287           some combinations of hardware and BIOS. The symptom, for which
1288           this config is intended, is when reboot ends with a stalled/hung
1289           system.
1290 
1291           Currently, the only fixup is for the Geode machines using
1292           CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1293 
1294           Say Y if you want to enable the fixup. Currently, it's safe to
1295           enable this option even if you don't need it.
1296           Say N otherwise.
1297 
1298 config MICROCODE
1299         bool "CPU microcode loading support"
1300         default y
1301         depends on CPU_SUP_AMD || CPU_SUP_INTEL
1302         help
1303           If you say Y here, you will be able to update the microcode on
1304           Intel and AMD processors. The Intel support is for the IA32 family,
1305           e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1306           AMD support is for families 0x10 and later. You will obviously need
1307           the actual microcode binary data itself which is not shipped with
1308           the Linux kernel.
1309 
1310           The preferred method to load microcode from a detached initrd is described
1311           in Documentation/x86/microcode.rst. For that you need to enable
1312           CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1313           initrd for microcode blobs.
1314 
1315           In addition, you can build the microcode into the kernel. For that you
1316           need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1317           config option.
1318 
1319 config MICROCODE_INTEL
1320         bool "Intel microcode loading support"
1321         depends on CPU_SUP_INTEL && MICROCODE
1322         default MICROCODE
1323         help
1324           This options enables microcode patch loading support for Intel
1325           processors.
1326 
1327           For the current Intel microcode data package go to
1328           <https://downloadcenter.intel.com> and search for
1329           'Linux Processor Microcode Data File'.
1330 
1331 config MICROCODE_AMD
1332         bool "AMD microcode loading support"
1333         depends on CPU_SUP_AMD && MICROCODE
1334         help
1335           If you select this option, microcode patch loading support for AMD
1336           processors will be enabled.
1337 
1338 config MICROCODE_LATE_LOADING
1339         bool "Late microcode loading (DANGEROUS)"
1340         default n
1341         depends on MICROCODE
1342         help
1343           Loading microcode late, when the system is up and executing instructions
1344           is a tricky business and should be avoided if possible. Just the sequence
1345           of synchronizing all cores and SMT threads is one fragile dance which does
1346           not guarantee that cores might not softlock after the loading. Therefore,
1347           use this at your own risk. Late loading taints the kernel too.
1348 
1349 config X86_MSR
1350         tristate "/dev/cpu/*/msr - Model-specific register support"
1351         help
1352           This device gives privileged processes access to the x86
1353           Model-Specific Registers (MSRs).  It is a character device with
1354           major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1355           MSR accesses are directed to a specific CPU on multi-processor
1356           systems.
1357 
1358 config X86_CPUID
1359         tristate "/dev/cpu/*/cpuid - CPU information support"
1360         help
1361           This device gives processes access to the x86 CPUID instruction to
1362           be executed on a specific processor.  It is a character device
1363           with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1364           /dev/cpu/31/cpuid.
1365 
1366 choice
1367         prompt "High Memory Support"
1368         default HIGHMEM4G
1369         depends on X86_32
1370 
1371 config NOHIGHMEM
1372         bool "off"
1373         help
1374           Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1375           However, the address space of 32-bit x86 processors is only 4
1376           Gigabytes large. That means that, if you have a large amount of
1377           physical memory, not all of it can be "permanently mapped" by the
1378           kernel. The physical memory that's not permanently mapped is called
1379           "high memory".
1380 
1381           If you are compiling a kernel which will never run on a machine with
1382           more than 1 Gigabyte total physical RAM, answer "off" here (default
1383           choice and suitable for most users). This will result in a "3GB/1GB"
1384           split: 3GB are mapped so that each process sees a 3GB virtual memory
1385           space and the remaining part of the 4GB virtual memory space is used
1386           by the kernel to permanently map as much physical memory as
1387           possible.
1388 
1389           If the machine has between 1 and 4 Gigabytes physical RAM, then
1390           answer "4GB" here.
1391 
1392           If more than 4 Gigabytes is used then answer "64GB" here. This
1393           selection turns Intel PAE (Physical Address Extension) mode on.
1394           PAE implements 3-level paging on IA32 processors. PAE is fully
1395           supported by Linux, PAE mode is implemented on all recent Intel
1396           processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1397           then the kernel will not boot on CPUs that don't support PAE!
1398 
1399           The actual amount of total physical memory will either be
1400           auto detected or can be forced by using a kernel command line option
1401           such as "mem=256M". (Try "man bootparam" or see the documentation of
1402           your boot loader (lilo or loadlin) about how to pass options to the
1403           kernel at boot time.)
1404 
1405           If unsure, say "off".
1406 
1407 config HIGHMEM4G
1408         bool "4GB"
1409         help
1410           Select this if you have a 32-bit processor and between 1 and 4
1411           gigabytes of physical RAM.
1412 
1413 config HIGHMEM64G
1414         bool "64GB"
1415         depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1416         select X86_PAE
1417         help
1418           Select this if you have a 32-bit processor and more than 4
1419           gigabytes of physical RAM.
1420 
1421 endchoice
1422 
1423 choice
1424         prompt "Memory split" if EXPERT
1425         default VMSPLIT_3G
1426         depends on X86_32
1427         help
1428           Select the desired split between kernel and user memory.
1429 
1430           If the address range available to the kernel is less than the
1431           physical memory installed, the remaining memory will be available
1432           as "high memory". Accessing high memory is a little more costly
1433           than low memory, as it needs to be mapped into the kernel first.
1434           Note that increasing the kernel address space limits the range
1435           available to user programs, making the address space there
1436           tighter.  Selecting anything other than the default 3G/1G split
1437           will also likely make your kernel incompatible with binary-only
1438           kernel modules.
1439 
1440           If you are not absolutely sure what you are doing, leave this
1441           option alone!
1442 
1443         config VMSPLIT_3G
1444                 bool "3G/1G user/kernel split"
1445         config VMSPLIT_3G_OPT
1446                 depends on !X86_PAE
1447                 bool "3G/1G user/kernel split (for full 1G low memory)"
1448         config VMSPLIT_2G
1449                 bool "2G/2G user/kernel split"
1450         config VMSPLIT_2G_OPT
1451                 depends on !X86_PAE
1452                 bool "2G/2G user/kernel split (for full 2G low memory)"
1453         config VMSPLIT_1G
1454                 bool "1G/3G user/kernel split"
1455 endchoice
1456 
1457 config PAGE_OFFSET
1458         hex
1459         default 0xB0000000 if VMSPLIT_3G_OPT
1460         default 0x80000000 if VMSPLIT_2G
1461         default 0x78000000 if VMSPLIT_2G_OPT
1462         default 0x40000000 if VMSPLIT_1G
1463         default 0xC0000000
1464         depends on X86_32
1465 
1466 config HIGHMEM
1467         def_bool y
1468         depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1469 
1470 config X86_PAE
1471         bool "PAE (Physical Address Extension) Support"
1472         depends on X86_32 && !HIGHMEM4G
1473         select PHYS_ADDR_T_64BIT
1474         select SWIOTLB
1475         help
1476           PAE is required for NX support, and furthermore enables
1477           larger swapspace support for non-overcommit purposes. It
1478           has the cost of more pagetable lookup overhead, and also
1479           consumes more pagetable space per process.
1480 
1481 config X86_5LEVEL
1482         bool "Enable 5-level page tables support"
1483         default y
1484         select DYNAMIC_MEMORY_LAYOUT
1485         select SPARSEMEM_VMEMMAP
1486         depends on X86_64
1487         help
1488           5-level paging enables access to larger address space:
1489           upto 128 PiB of virtual address space and 4 PiB of
1490           physical address space.
1491 
1492           It will be supported by future Intel CPUs.
1493 
1494           A kernel with the option enabled can be booted on machines that
1495           support 4- or 5-level paging.
1496 
1497           See Documentation/x86/x86_64/5level-paging.rst for more
1498           information.
1499 
1500           Say N if unsure.
1501 
1502 config X86_DIRECT_GBPAGES
1503         def_bool y
1504         depends on X86_64
1505         help
1506           Certain kernel features effectively disable kernel
1507           linear 1 GB mappings (even if the CPU otherwise
1508           supports them), so don't confuse the user by printing
1509           that we have them enabled.
1510 
1511 config X86_CPA_STATISTICS
1512         bool "Enable statistic for Change Page Attribute"
1513         depends on DEBUG_FS
1514         help
1515           Expose statistics about the Change Page Attribute mechanism, which
1516           helps to determine the effectiveness of preserving large and huge
1517           page mappings when mapping protections are changed.
1518 
1519 config X86_MEM_ENCRYPT
1520         select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1521         select DYNAMIC_PHYSICAL_MASK
1522         def_bool n
1523 
1524 config AMD_MEM_ENCRYPT
1525         bool "AMD Secure Memory Encryption (SME) support"
1526         depends on X86_64 && CPU_SUP_AMD
1527         select DMA_COHERENT_POOL
1528         select ARCH_USE_MEMREMAP_PROT
1529         select INSTRUCTION_DECODER
1530         select ARCH_HAS_CC_PLATFORM
1531         select X86_MEM_ENCRYPT
1532         help
1533           Say yes to enable support for the encryption of system memory.
1534           This requires an AMD processor that supports Secure Memory
1535           Encryption (SME).
1536 
1537 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1538         bool "Activate AMD Secure Memory Encryption (SME) by default"
1539         depends on AMD_MEM_ENCRYPT
1540         help
1541           Say yes to have system memory encrypted by default if running on
1542           an AMD processor that supports Secure Memory Encryption (SME).
1543 
1544           If set to Y, then the encryption of system memory can be
1545           deactivated with the mem_encrypt=off command line option.
1546 
1547           If set to N, then the encryption of system memory can be
1548           activated with the mem_encrypt=on command line option.
1549 
1550 # Common NUMA Features
1551 config NUMA
1552         bool "NUMA Memory Allocation and Scheduler Support"
1553         depends on SMP
1554         depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1555         default y if X86_BIGSMP
1556         select USE_PERCPU_NUMA_NODE_ID
1557         help
1558           Enable NUMA (Non-Uniform Memory Access) support.
1559 
1560           The kernel will try to allocate memory used by a CPU on the
1561           local memory controller of the CPU and add some more
1562           NUMA awareness to the kernel.
1563 
1564           For 64-bit this is recommended if the system is Intel Core i7
1565           (or later), AMD Opteron, or EM64T NUMA.
1566 
1567           For 32-bit this is only needed if you boot a 32-bit
1568           kernel on a 64-bit NUMA platform.
1569 
1570           Otherwise, you should say N.
1571 
1572 config AMD_NUMA
1573         def_bool y
1574         prompt "Old style AMD Opteron NUMA detection"
1575         depends on X86_64 && NUMA && PCI
1576         help
1577           Enable AMD NUMA node topology detection.  You should say Y here if
1578           you have a multi processor AMD system. This uses an old method to
1579           read the NUMA configuration directly from the builtin Northbridge
1580           of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1581           which also takes priority if both are compiled in.
1582 
1583 config X86_64_ACPI_NUMA
1584         def_bool y
1585         prompt "ACPI NUMA detection"
1586         depends on X86_64 && NUMA && ACPI && PCI
1587         select ACPI_NUMA
1588         help
1589           Enable ACPI SRAT based node topology detection.
1590 
1591 config NUMA_EMU
1592         bool "NUMA emulation"
1593         depends on NUMA
1594         help
1595           Enable NUMA emulation. A flat machine will be split
1596           into virtual nodes when booted with "numa=fake=N", where N is the
1597           number of nodes. This is only useful for debugging.
1598 
1599 config NODES_SHIFT
1600         int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1601         range 1 10
1602         default "10" if MAXSMP
1603         default "6" if X86_64
1604         default "3"
1605         depends on NUMA
1606         help
1607           Specify the maximum number of NUMA Nodes available on the target
1608           system.  Increases memory reserved to accommodate various tables.
1609 
1610 config ARCH_FLATMEM_ENABLE
1611         def_bool y
1612         depends on X86_32 && !NUMA
1613 
1614 config ARCH_SPARSEMEM_ENABLE
1615         def_bool y
1616         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1617         select SPARSEMEM_STATIC if X86_32
1618         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1619 
1620 config ARCH_SPARSEMEM_DEFAULT
1621         def_bool X86_64 || (NUMA && X86_32)
1622 
1623 config ARCH_SELECT_MEMORY_MODEL
1624         def_bool y
1625         depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1626 
1627 config ARCH_MEMORY_PROBE
1628         bool "Enable sysfs memory/probe interface"
1629         depends on MEMORY_HOTPLUG
1630         help
1631           This option enables a sysfs memory/probe interface for testing.
1632           See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1633           If you are unsure how to answer this question, answer N.
1634 
1635 config ARCH_PROC_KCORE_TEXT
1636         def_bool y
1637         depends on X86_64 && PROC_KCORE
1638 
1639 config ILLEGAL_POINTER_VALUE
1640         hex
1641         default 0 if X86_32
1642         default 0xdead000000000000 if X86_64
1643 
1644 config X86_PMEM_LEGACY_DEVICE
1645         bool
1646 
1647 config X86_PMEM_LEGACY
1648         tristate "Support non-standard NVDIMMs and ADR protected memory"
1649         depends on PHYS_ADDR_T_64BIT
1650         depends on BLK_DEV
1651         select X86_PMEM_LEGACY_DEVICE
1652         select NUMA_KEEP_MEMINFO if NUMA
1653         select LIBNVDIMM
1654         help
1655           Treat memory marked using the non-standard e820 type of 12 as used
1656           by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1657           The kernel will offer these regions to the 'pmem' driver so
1658           they can be used for persistent storage.
1659 
1660           Say Y if unsure.
1661 
1662 config HIGHPTE
1663         bool "Allocate 3rd-level pagetables from highmem"
1664         depends on HIGHMEM
1665         help
1666           The VM uses one page table entry for each page of physical memory.
1667           For systems with a lot of RAM, this can be wasteful of precious
1668           low memory.  Setting this option will put user-space page table
1669           entries in high memory.
1670 
1671 config X86_CHECK_BIOS_CORRUPTION
1672         bool "Check for low memory corruption"
1673         help
1674           Periodically check for memory corruption in low memory, which
1675           is suspected to be caused by BIOS.  Even when enabled in the
1676           configuration, it is disabled at runtime.  Enable it by
1677           setting "memory_corruption_check=1" on the kernel command
1678           line.  By default it scans the low 64k of memory every 60
1679           seconds; see the memory_corruption_check_size and
1680           memory_corruption_check_period parameters in
1681           Documentation/admin-guide/kernel-parameters.rst to adjust this.
1682 
1683           When enabled with the default parameters, this option has
1684           almost no overhead, as it reserves a relatively small amount
1685           of memory and scans it infrequently.  It both detects corruption
1686           and prevents it from affecting the running system.
1687 
1688           It is, however, intended as a diagnostic tool; if repeatable
1689           BIOS-originated corruption always affects the same memory,
1690           you can use memmap= to prevent the kernel from using that
1691           memory.
1692 
1693 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1694         bool "Set the default setting of memory_corruption_check"
1695         depends on X86_CHECK_BIOS_CORRUPTION
1696         default y
1697         help
1698           Set whether the default state of memory_corruption_check is
1699           on or off.
1700 
1701 config MATH_EMULATION
1702         bool
1703         depends on MODIFY_LDT_SYSCALL
1704         prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1705         help
1706           Linux can emulate a math coprocessor (used for floating point
1707           operations) if you don't have one. 486DX and Pentium processors have
1708           a math coprocessor built in, 486SX and 386 do not, unless you added
1709           a 487DX or 387, respectively. (The messages during boot time can
1710           give you some hints here ["man dmesg"].) Everyone needs either a
1711           coprocessor or this emulation.
1712 
1713           If you don't have a math coprocessor, you need to say Y here; if you
1714           say Y here even though you have a coprocessor, the coprocessor will
1715           be used nevertheless. (This behavior can be changed with the kernel
1716           command line option "no387", which comes handy if your coprocessor
1717           is broken. Try "man bootparam" or see the documentation of your boot
1718           loader (lilo or loadlin) about how to pass options to the kernel at
1719           boot time.) This means that it is a good idea to say Y here if you
1720           intend to use this kernel on different machines.
1721 
1722           More information about the internals of the Linux math coprocessor
1723           emulation can be found in <file:arch/x86/math-emu/README>.
1724 
1725           If you are not sure, say Y; apart from resulting in a 66 KB bigger
1726           kernel, it won't hurt.
1727 
1728 config MTRR
1729         def_bool y
1730         prompt "MTRR (Memory Type Range Register) support" if EXPERT
1731         help
1732           On Intel P6 family processors (Pentium Pro, Pentium II and later)
1733           the Memory Type Range Registers (MTRRs) may be used to control
1734           processor access to memory ranges. This is most useful if you have
1735           a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1736           allows bus write transfers to be combined into a larger transfer
1737           before bursting over the PCI/AGP bus. This can increase performance
1738           of image write operations 2.5 times or more. Saying Y here creates a
1739           /proc/mtrr file which may be used to manipulate your processor's
1740           MTRRs. Typically the X server should use this.
1741 
1742           This code has a reasonably generic interface so that similar
1743           control registers on other processors can be easily supported
1744           as well:
1745 
1746           The Cyrix 6x86, 6x86MX and M II processors have Address Range
1747           Registers (ARRs) which provide a similar functionality to MTRRs. For
1748           these, the ARRs are used to emulate the MTRRs.
1749           The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1750           MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1751           write-combining. All of these processors are supported by this code
1752           and it makes sense to say Y here if you have one of them.
1753 
1754           Saying Y here also fixes a problem with buggy SMP BIOSes which only
1755           set the MTRRs for the boot CPU and not for the secondary CPUs. This
1756           can lead to all sorts of problems, so it's good to say Y here.
1757 
1758           You can safely say Y even if your machine doesn't have MTRRs, you'll
1759           just add about 9 KB to your kernel.
1760 
1761           See <file:Documentation/x86/mtrr.rst> for more information.
1762 
1763 config MTRR_SANITIZER
1764         def_bool y
1765         prompt "MTRR cleanup support"
1766         depends on MTRR
1767         help
1768           Convert MTRR layout from continuous to discrete, so X drivers can
1769           add writeback entries.
1770 
1771           Can be disabled with disable_mtrr_cleanup on the kernel command line.
1772           The largest mtrr entry size for a continuous block can be set with
1773           mtrr_chunk_size.
1774 
1775           If unsure, say Y.
1776 
1777 config MTRR_SANITIZER_ENABLE_DEFAULT
1778         int "MTRR cleanup enable value (0-1)"
1779         range 0 1
1780         default "0"
1781         depends on MTRR_SANITIZER
1782         help
1783           Enable mtrr cleanup default value
1784 
1785 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1786         int "MTRR cleanup spare reg num (0-7)"
1787         range 0 7
1788         default "1"
1789         depends on MTRR_SANITIZER
1790         help
1791           mtrr cleanup spare entries default, it can be changed via
1792           mtrr_spare_reg_nr=N on the kernel command line.
1793 
1794 config X86_PAT
1795         def_bool y
1796         prompt "x86 PAT support" if EXPERT
1797         depends on MTRR
1798         help
1799           Use PAT attributes to setup page level cache control.
1800 
1801           PATs are the modern equivalents of MTRRs and are much more
1802           flexible than MTRRs.
1803 
1804           Say N here if you see bootup problems (boot crash, boot hang,
1805           spontaneous reboots) or a non-working video driver.
1806 
1807           If unsure, say Y.
1808 
1809 config ARCH_USES_PG_UNCACHED
1810         def_bool y
1811         depends on X86_PAT
1812 
1813 config X86_UMIP
1814         def_bool y
1815         prompt "User Mode Instruction Prevention" if EXPERT
1816         help
1817           User Mode Instruction Prevention (UMIP) is a security feature in
1818           some x86 processors. If enabled, a general protection fault is
1819           issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1820           executed in user mode. These instructions unnecessarily expose
1821           information about the hardware state.
1822 
1823           The vast majority of applications do not use these instructions.
1824           For the very few that do, software emulation is provided in
1825           specific cases in protected and virtual-8086 modes. Emulated
1826           results are dummy.
1827 
1828 config CC_HAS_IBT
1829         # GCC >= 9 and binutils >= 2.29
1830         # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1831         # Clang/LLVM >= 14
1832         # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1833         # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1834         def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1835                   (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1836                   $(as-instr,endbr64)
1837 
1838 config X86_KERNEL_IBT
1839         prompt "Indirect Branch Tracking"
1840         bool
1841         depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1842         # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1843         depends on !LD_IS_LLD || LLD_VERSION >= 140000
1844         select OBJTOOL
1845         help
1846           Build the kernel with support for Indirect Branch Tracking, a
1847           hardware support course-grain forward-edge Control Flow Integrity
1848           protection. It enforces that all indirect calls must land on
1849           an ENDBR instruction, as such, the compiler will instrument the
1850           code with them to make this happen.
1851 
1852           In addition to building the kernel with IBT, seal all functions that
1853           are not indirect call targets, avoiding them ever becoming one.
1854 
1855           This requires LTO like objtool runs and will slow down the build. It
1856           does significantly reduce the number of ENDBR instructions in the
1857           kernel image.
1858 
1859 config X86_INTEL_MEMORY_PROTECTION_KEYS
1860         prompt "Memory Protection Keys"
1861         def_bool y
1862         # Note: only available in 64-bit mode
1863         depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1864         select ARCH_USES_HIGH_VMA_FLAGS
1865         select ARCH_HAS_PKEYS
1866         help
1867           Memory Protection Keys provides a mechanism for enforcing
1868           page-based protections, but without requiring modification of the
1869           page tables when an application changes protection domains.
1870 
1871           For details, see Documentation/core-api/protection-keys.rst
1872 
1873           If unsure, say y.
1874 
1875 choice
1876         prompt "TSX enable mode"
1877         depends on CPU_SUP_INTEL
1878         default X86_INTEL_TSX_MODE_OFF
1879         help
1880           Intel's TSX (Transactional Synchronization Extensions) feature
1881           allows to optimize locking protocols through lock elision which
1882           can lead to a noticeable performance boost.
1883 
1884           On the other hand it has been shown that TSX can be exploited
1885           to form side channel attacks (e.g. TAA) and chances are there
1886           will be more of those attacks discovered in the future.
1887 
1888           Therefore TSX is not enabled by default (aka tsx=off). An admin
1889           might override this decision by tsx=on the command line parameter.
1890           Even with TSX enabled, the kernel will attempt to enable the best
1891           possible TAA mitigation setting depending on the microcode available
1892           for the particular machine.
1893 
1894           This option allows to set the default tsx mode between tsx=on, =off
1895           and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1896           details.
1897 
1898           Say off if not sure, auto if TSX is in use but it should be used on safe
1899           platforms or on if TSX is in use and the security aspect of tsx is not
1900           relevant.
1901 
1902 config X86_INTEL_TSX_MODE_OFF
1903         bool "off"
1904         help
1905           TSX is disabled if possible - equals to tsx=off command line parameter.
1906 
1907 config X86_INTEL_TSX_MODE_ON
1908         bool "on"
1909         help
1910           TSX is always enabled on TSX capable HW - equals the tsx=on command
1911           line parameter.
1912 
1913 config X86_INTEL_TSX_MODE_AUTO
1914         bool "auto"
1915         help
1916           TSX is enabled on TSX capable HW that is believed to be safe against
1917           side channel attacks- equals the tsx=auto command line parameter.
1918 endchoice
1919 
1920 config X86_SGX
1921         bool "Software Guard eXtensions (SGX)"
1922         depends on X86_64 && CPU_SUP_INTEL
1923         depends on CRYPTO=y
1924         depends on CRYPTO_SHA256=y
1925         select SRCU
1926         select MMU_NOTIFIER
1927         select NUMA_KEEP_MEMINFO if NUMA
1928         select XARRAY_MULTI
1929         help
1930           Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1931           that can be used by applications to set aside private regions of code
1932           and data, referred to as enclaves. An enclave's private memory can
1933           only be accessed by code running within the enclave. Accesses from
1934           outside the enclave, including other enclaves, are disallowed by
1935           hardware.
1936 
1937           If unsure, say N.
1938 
1939 config EFI
1940         bool "EFI runtime service support"
1941         depends on ACPI
1942         select UCS2_STRING
1943         select EFI_RUNTIME_WRAPPERS
1944         select ARCH_USE_MEMREMAP_PROT
1945         help
1946           This enables the kernel to use EFI runtime services that are
1947           available (such as the EFI variable services).
1948 
1949           This option is only useful on systems that have EFI firmware.
1950           In addition, you should use the latest ELILO loader available
1951           at <http://elilo.sourceforge.net> in order to take advantage
1952           of EFI runtime services. However, even with this option, the
1953           resultant kernel should continue to boot on existing non-EFI
1954           platforms.
1955 
1956 config EFI_STUB
1957         bool "EFI stub support"
1958         depends on EFI
1959         depends on $(cc-option,-mabi=ms) || X86_32
1960         select RELOCATABLE
1961         help
1962           This kernel feature allows a bzImage to be loaded directly
1963           by EFI firmware without the use of a bootloader.
1964 
1965           See Documentation/admin-guide/efi-stub.rst for more information.
1966 
1967 config EFI_MIXED
1968         bool "EFI mixed-mode support"
1969         depends on EFI_STUB && X86_64
1970         help
1971           Enabling this feature allows a 64-bit kernel to be booted
1972           on a 32-bit firmware, provided that your CPU supports 64-bit
1973           mode.
1974 
1975           Note that it is not possible to boot a mixed-mode enabled
1976           kernel via the EFI boot stub - a bootloader that supports
1977           the EFI handover protocol must be used.
1978 
1979           If unsure, say N.
1980 
1981 source "kernel/Kconfig.hz"
1982 
1983 config KEXEC
1984         bool "kexec system call"
1985         select KEXEC_CORE
1986         help
1987           kexec is a system call that implements the ability to shutdown your
1988           current kernel, and to start another kernel.  It is like a reboot
1989           but it is independent of the system firmware.   And like a reboot
1990           you can start any kernel with it, not just Linux.
1991 
1992           The name comes from the similarity to the exec system call.
1993 
1994           It is an ongoing process to be certain the hardware in a machine
1995           is properly shutdown, so do not be surprised if this code does not
1996           initially work for you.  As of this writing the exact hardware
1997           interface is strongly in flux, so no good recommendation can be
1998           made.
1999 
2000 config KEXEC_FILE
2001         bool "kexec file based system call"
2002         select KEXEC_CORE
2003         select HAVE_IMA_KEXEC if IMA
2004         depends on X86_64
2005         depends on CRYPTO=y
2006         depends on CRYPTO_SHA256=y
2007         help
2008           This is new version of kexec system call. This system call is
2009           file based and takes file descriptors as system call argument
2010           for kernel and initramfs as opposed to list of segments as
2011           accepted by previous system call.
2012 
2013 config ARCH_HAS_KEXEC_PURGATORY
2014         def_bool KEXEC_FILE
2015 
2016 config KEXEC_SIG
2017         bool "Verify kernel signature during kexec_file_load() syscall"
2018         depends on KEXEC_FILE
2019         help
2020 
2021           This option makes the kexec_file_load() syscall check for a valid
2022           signature of the kernel image.  The image can still be loaded without
2023           a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2024           there's a signature that we can check, then it must be valid.
2025 
2026           In addition to this option, you need to enable signature
2027           verification for the corresponding kernel image type being
2028           loaded in order for this to work.
2029 
2030 config KEXEC_SIG_FORCE
2031         bool "Require a valid signature in kexec_file_load() syscall"
2032         depends on KEXEC_SIG
2033         help
2034           This option makes kernel signature verification mandatory for
2035           the kexec_file_load() syscall.
2036 
2037 config KEXEC_BZIMAGE_VERIFY_SIG
2038         bool "Enable bzImage signature verification support"
2039         depends on KEXEC_SIG
2040         depends on SIGNED_PE_FILE_VERIFICATION
2041         select SYSTEM_TRUSTED_KEYRING
2042         help
2043           Enable bzImage signature verification support.
2044 
2045 config CRASH_DUMP
2046         bool "kernel crash dumps"
2047         depends on X86_64 || (X86_32 && HIGHMEM)
2048         help
2049           Generate crash dump after being started by kexec.
2050           This should be normally only set in special crash dump kernels
2051           which are loaded in the main kernel with kexec-tools into
2052           a specially reserved region and then later executed after
2053           a crash by kdump/kexec. The crash dump kernel must be compiled
2054           to a memory address not used by the main kernel or BIOS using
2055           PHYSICAL_START, or it must be built as a relocatable image
2056           (CONFIG_RELOCATABLE=y).
2057           For more details see Documentation/admin-guide/kdump/kdump.rst
2058 
2059 config KEXEC_JUMP
2060         bool "kexec jump"
2061         depends on KEXEC && HIBERNATION
2062         help
2063           Jump between original kernel and kexeced kernel and invoke
2064           code in physical address mode via KEXEC
2065 
2066 config PHYSICAL_START
2067         hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2068         default "0x1000000"
2069         help
2070           This gives the physical address where the kernel is loaded.
2071 
2072           If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2073           bzImage will decompress itself to above physical address and
2074           run from there. Otherwise, bzImage will run from the address where
2075           it has been loaded by the boot loader and will ignore above physical
2076           address.
2077 
2078           In normal kdump cases one does not have to set/change this option
2079           as now bzImage can be compiled as a completely relocatable image
2080           (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2081           address. This option is mainly useful for the folks who don't want
2082           to use a bzImage for capturing the crash dump and want to use a
2083           vmlinux instead. vmlinux is not relocatable hence a kernel needs
2084           to be specifically compiled to run from a specific memory area
2085           (normally a reserved region) and this option comes handy.
2086 
2087           So if you are using bzImage for capturing the crash dump,
2088           leave the value here unchanged to 0x1000000 and set
2089           CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2090           for capturing the crash dump change this value to start of
2091           the reserved region.  In other words, it can be set based on
2092           the "X" value as specified in the "crashkernel=YM@XM"
2093           command line boot parameter passed to the panic-ed
2094           kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2095           for more details about crash dumps.
2096 
2097           Usage of bzImage for capturing the crash dump is recommended as
2098           one does not have to build two kernels. Same kernel can be used
2099           as production kernel and capture kernel. Above option should have
2100           gone away after relocatable bzImage support is introduced. But it
2101           is present because there are users out there who continue to use
2102           vmlinux for dump capture. This option should go away down the
2103           line.
2104 
2105           Don't change this unless you know what you are doing.
2106 
2107 config RELOCATABLE
2108         bool "Build a relocatable kernel"
2109         default y
2110         help
2111           This builds a kernel image that retains relocation information
2112           so it can be loaded someplace besides the default 1MB.
2113           The relocations tend to make the kernel binary about 10% larger,
2114           but are discarded at runtime.
2115 
2116           One use is for the kexec on panic case where the recovery kernel
2117           must live at a different physical address than the primary
2118           kernel.
2119 
2120           Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2121           it has been loaded at and the compile time physical address
2122           (CONFIG_PHYSICAL_START) is used as the minimum location.
2123 
2124 config RANDOMIZE_BASE
2125         bool "Randomize the address of the kernel image (KASLR)"
2126         depends on RELOCATABLE
2127         default y
2128         help
2129           In support of Kernel Address Space Layout Randomization (KASLR),
2130           this randomizes the physical address at which the kernel image
2131           is decompressed and the virtual address where the kernel
2132           image is mapped, as a security feature that deters exploit
2133           attempts relying on knowledge of the location of kernel
2134           code internals.
2135 
2136           On 64-bit, the kernel physical and virtual addresses are
2137           randomized separately. The physical address will be anywhere
2138           between 16MB and the top of physical memory (up to 64TB). The
2139           virtual address will be randomized from 16MB up to 1GB (9 bits
2140           of entropy). Note that this also reduces the memory space
2141           available to kernel modules from 1.5GB to 1GB.
2142 
2143           On 32-bit, the kernel physical and virtual addresses are
2144           randomized together. They will be randomized from 16MB up to
2145           512MB (8 bits of entropy).
2146 
2147           Entropy is generated using the RDRAND instruction if it is
2148           supported. If RDTSC is supported, its value is mixed into
2149           the entropy pool as well. If neither RDRAND nor RDTSC are
2150           supported, then entropy is read from the i8254 timer. The
2151           usable entropy is limited by the kernel being built using
2152           2GB addressing, and that PHYSICAL_ALIGN must be at a
2153           minimum of 2MB. As a result, only 10 bits of entropy are
2154           theoretically possible, but the implementations are further
2155           limited due to memory layouts.
2156 
2157           If unsure, say Y.
2158 
2159 # Relocation on x86 needs some additional build support
2160 config X86_NEED_RELOCS
2161         def_bool y
2162         depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2163 
2164 config PHYSICAL_ALIGN
2165         hex "Alignment value to which kernel should be aligned"
2166         default "0x200000"
2167         range 0x2000 0x1000000 if X86_32
2168         range 0x200000 0x1000000 if X86_64
2169         help
2170           This value puts the alignment restrictions on physical address
2171           where kernel is loaded and run from. Kernel is compiled for an
2172           address which meets above alignment restriction.
2173 
2174           If bootloader loads the kernel at a non-aligned address and
2175           CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2176           address aligned to above value and run from there.
2177 
2178           If bootloader loads the kernel at a non-aligned address and
2179           CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2180           load address and decompress itself to the address it has been
2181           compiled for and run from there. The address for which kernel is
2182           compiled already meets above alignment restrictions. Hence the
2183           end result is that kernel runs from a physical address meeting
2184           above alignment restrictions.
2185 
2186           On 32-bit this value must be a multiple of 0x2000. On 64-bit
2187           this value must be a multiple of 0x200000.
2188 
2189           Don't change this unless you know what you are doing.
2190 
2191 config DYNAMIC_MEMORY_LAYOUT
2192         bool
2193         help
2194           This option makes base addresses of vmalloc and vmemmap as well as
2195           __PAGE_OFFSET movable during boot.
2196 
2197 config RANDOMIZE_MEMORY
2198         bool "Randomize the kernel memory sections"
2199         depends on X86_64
2200         depends on RANDOMIZE_BASE
2201         select DYNAMIC_MEMORY_LAYOUT
2202         default RANDOMIZE_BASE
2203         help
2204           Randomizes the base virtual address of kernel memory sections
2205           (physical memory mapping, vmalloc & vmemmap). This security feature
2206           makes exploits relying on predictable memory locations less reliable.
2207 
2208           The order of allocations remains unchanged. Entropy is generated in
2209           the same way as RANDOMIZE_BASE. Current implementation in the optimal
2210           configuration have in average 30,000 different possible virtual
2211           addresses for each memory section.
2212 
2213           If unsure, say Y.
2214 
2215 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2216         hex "Physical memory mapping padding" if EXPERT
2217         depends on RANDOMIZE_MEMORY
2218         default "0xa" if MEMORY_HOTPLUG
2219         default "0x0"
2220         range 0x1 0x40 if MEMORY_HOTPLUG
2221         range 0x0 0x40
2222         help
2223           Define the padding in terabytes added to the existing physical
2224           memory size during kernel memory randomization. It is useful
2225           for memory hotplug support but reduces the entropy available for
2226           address randomization.
2227 
2228           If unsure, leave at the default value.
2229 
2230 config HOTPLUG_CPU
2231         def_bool y
2232         depends on SMP
2233 
2234 config BOOTPARAM_HOTPLUG_CPU0
2235         bool "Set default setting of cpu0_hotpluggable"
2236         depends on HOTPLUG_CPU
2237         help
2238           Set whether default state of cpu0_hotpluggable is on or off.
2239 
2240           Say Y here to enable CPU0 hotplug by default. If this switch
2241           is turned on, there is no need to give cpu0_hotplug kernel
2242           parameter and the CPU0 hotplug feature is enabled by default.
2243 
2244           Please note: there are two known CPU0 dependencies if you want
2245           to enable the CPU0 hotplug feature either by this switch or by
2246           cpu0_hotplug kernel parameter.
2247 
2248           First, resume from hibernate or suspend always starts from CPU0.
2249           So hibernate and suspend are prevented if CPU0 is offline.
2250 
2251           Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2252           offline if any interrupt can not migrate out of CPU0. There may
2253           be other CPU0 dependencies.
2254 
2255           Please make sure the dependencies are under your control before
2256           you enable this feature.
2257 
2258           Say N if you don't want to enable CPU0 hotplug feature by default.
2259           You still can enable the CPU0 hotplug feature at boot by kernel
2260           parameter cpu0_hotplug.
2261 
2262 config DEBUG_HOTPLUG_CPU0
2263         def_bool n
2264         prompt "Debug CPU0 hotplug"
2265         depends on HOTPLUG_CPU
2266         help
2267           Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2268           soon as possible and boots up userspace with CPU0 offlined. User
2269           can online CPU0 back after boot time.
2270 
2271           To debug CPU0 hotplug, you need to enable CPU0 offline/online
2272           feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2273           compilation or giving cpu0_hotplug kernel parameter at boot.
2274 
2275           If unsure, say N.
2276 
2277 config COMPAT_VDSO
2278         def_bool n
2279         prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2280         depends on COMPAT_32
2281         help
2282           Certain buggy versions of glibc will crash if they are
2283           presented with a 32-bit vDSO that is not mapped at the address
2284           indicated in its segment table.
2285 
2286           The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2287           and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2288           49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2289           the only released version with the bug, but OpenSUSE 9
2290           contains a buggy "glibc 2.3.2".
2291 
2292           The symptom of the bug is that everything crashes on startup, saying:
2293           dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2294 
2295           Saying Y here changes the default value of the vdso32 boot
2296           option from 1 to 0, which turns off the 32-bit vDSO entirely.
2297           This works around the glibc bug but hurts performance.
2298 
2299           If unsure, say N: if you are compiling your own kernel, you
2300           are unlikely to be using a buggy version of glibc.
2301 
2302 choice
2303         prompt "vsyscall table for legacy applications"
2304         depends on X86_64
2305         default LEGACY_VSYSCALL_XONLY
2306         help
2307           Legacy user code that does not know how to find the vDSO expects
2308           to be able to issue three syscalls by calling fixed addresses in
2309           kernel space. Since this location is not randomized with ASLR,
2310           it can be used to assist security vulnerability exploitation.
2311 
2312           This setting can be changed at boot time via the kernel command
2313           line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2314           is deprecated and can only be enabled using the kernel command
2315           line.
2316 
2317           On a system with recent enough glibc (2.14 or newer) and no
2318           static binaries, you can say None without a performance penalty
2319           to improve security.
2320 
2321           If unsure, select "Emulate execution only".
2322 
2323         config LEGACY_VSYSCALL_XONLY
2324                 bool "Emulate execution only"
2325                 help
2326                   The kernel traps and emulates calls into the fixed vsyscall
2327                   address mapping and does not allow reads.  This
2328                   configuration is recommended when userspace might use the
2329                   legacy vsyscall area but support for legacy binary
2330                   instrumentation of legacy code is not needed.  It mitigates
2331                   certain uses of the vsyscall area as an ASLR-bypassing
2332                   buffer.
2333 
2334         config LEGACY_VSYSCALL_NONE
2335                 bool "None"
2336                 help
2337                   There will be no vsyscall mapping at all. This will
2338                   eliminate any risk of ASLR bypass due to the vsyscall
2339                   fixed address mapping. Attempts to use the vsyscalls
2340                   will be reported to dmesg, so that either old or
2341                   malicious userspace programs can be identified.
2342 
2343 endchoice
2344 
2345 config CMDLINE_BOOL
2346         bool "Built-in kernel command line"
2347         help
2348           Allow for specifying boot arguments to the kernel at
2349           build time.  On some systems (e.g. embedded ones), it is
2350           necessary or convenient to provide some or all of the
2351           kernel boot arguments with the kernel itself (that is,
2352           to not rely on the boot loader to provide them.)
2353 
2354           To compile command line arguments into the kernel,
2355           set this option to 'Y', then fill in the
2356           boot arguments in CONFIG_CMDLINE.
2357 
2358           Systems with fully functional boot loaders (i.e. non-embedded)
2359           should leave this option set to 'N'.
2360 
2361 config CMDLINE
2362         string "Built-in kernel command string"
2363         depends on CMDLINE_BOOL
2364         default ""
2365         help
2366           Enter arguments here that should be compiled into the kernel
2367           image and used at boot time.  If the boot loader provides a
2368           command line at boot time, it is appended to this string to
2369           form the full kernel command line, when the system boots.
2370 
2371           However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2372           change this behavior.
2373 
2374           In most cases, the command line (whether built-in or provided
2375           by the boot loader) should specify the device for the root
2376           file system.
2377 
2378 config CMDLINE_OVERRIDE
2379         bool "Built-in command line overrides boot loader arguments"
2380         depends on CMDLINE_BOOL && CMDLINE != ""
2381         help
2382           Set this option to 'Y' to have the kernel ignore the boot loader
2383           command line, and use ONLY the built-in command line.
2384 
2385           This is used to work around broken boot loaders.  This should
2386           be set to 'N' under normal conditions.
2387 
2388 config MODIFY_LDT_SYSCALL
2389         bool "Enable the LDT (local descriptor table)" if EXPERT
2390         default y
2391         help
2392           Linux can allow user programs to install a per-process x86
2393           Local Descriptor Table (LDT) using the modify_ldt(2) system
2394           call.  This is required to run 16-bit or segmented code such as
2395           DOSEMU or some Wine programs.  It is also used by some very old
2396           threading libraries.
2397 
2398           Enabling this feature adds a small amount of overhead to
2399           context switches and increases the low-level kernel attack
2400           surface.  Disabling it removes the modify_ldt(2) system call.
2401 
2402           Saying 'N' here may make sense for embedded or server kernels.
2403 
2404 config STRICT_SIGALTSTACK_SIZE
2405         bool "Enforce strict size checking for sigaltstack"
2406         depends on DYNAMIC_SIGFRAME
2407         help
2408           For historical reasons MINSIGSTKSZ is a constant which became
2409           already too small with AVX512 support. Add a mechanism to
2410           enforce strict checking of the sigaltstack size against the
2411           real size of the FPU frame. This option enables the check
2412           by default. It can also be controlled via the kernel command
2413           line option 'strict_sas_size' independent of this config
2414           switch. Enabling it might break existing applications which
2415           allocate a too small sigaltstack but 'work' because they
2416           never get a signal delivered.
2417 
2418           Say 'N' unless you want to really enforce this check.
2419 
2420 source "kernel/livepatch/Kconfig"
2421 
2422 endmenu
2423 
2424 config CC_HAS_SLS
2425         def_bool $(cc-option,-mharden-sls=all)
2426 
2427 config CC_HAS_RETURN_THUNK
2428         def_bool $(cc-option,-mfunction-return=thunk-extern)
2429 
2430 menuconfig SPECULATION_MITIGATIONS
2431         bool "Mitigations for speculative execution vulnerabilities"
2432         default y
2433         help
2434           Say Y here to enable options which enable mitigations for
2435           speculative execution hardware vulnerabilities.
2436 
2437           If you say N, all mitigations will be disabled. You really
2438           should know what you are doing to say so.
2439 
2440 if SPECULATION_MITIGATIONS
2441 
2442 config PAGE_TABLE_ISOLATION
2443         bool "Remove the kernel mapping in user mode"
2444         default y
2445         depends on (X86_64 || X86_PAE)
2446         help
2447           This feature reduces the number of hardware side channels by
2448           ensuring that the majority of kernel addresses are not mapped
2449           into userspace.
2450 
2451           See Documentation/x86/pti.rst for more details.
2452 
2453 config RETPOLINE
2454         bool "Avoid speculative indirect branches in kernel"
2455         select OBJTOOL if HAVE_OBJTOOL
2456         default y
2457         help
2458           Compile kernel with the retpoline compiler options to guard against
2459           kernel-to-user data leaks by avoiding speculative indirect
2460           branches. Requires a compiler with -mindirect-branch=thunk-extern
2461           support for full protection. The kernel may run slower.
2462 
2463 config RETHUNK
2464         bool "Enable return-thunks"
2465         depends on RETPOLINE && CC_HAS_RETURN_THUNK
2466         select OBJTOOL if HAVE_OBJTOOL
2467         default y if X86_64
2468         help
2469           Compile the kernel with the return-thunks compiler option to guard
2470           against kernel-to-user data leaks by avoiding return speculation.
2471           Requires a compiler with -mfunction-return=thunk-extern
2472           support for full protection. The kernel may run slower.
2473 
2474 config CPU_UNRET_ENTRY
2475         bool "Enable UNRET on kernel entry"
2476         depends on CPU_SUP_AMD && RETHUNK && X86_64
2477         default y
2478         help
2479           Compile the kernel with support for the retbleed=unret mitigation.
2480 
2481 config CPU_IBPB_ENTRY
2482         bool "Enable IBPB on kernel entry"
2483         depends on CPU_SUP_AMD && X86_64
2484         default y
2485         help
2486           Compile the kernel with support for the retbleed=ibpb mitigation.
2487 
2488 config CPU_IBRS_ENTRY
2489         bool "Enable IBRS on kernel entry"
2490         depends on CPU_SUP_INTEL && X86_64
2491         default y
2492         help
2493           Compile the kernel with support for the spectre_v2=ibrs mitigation.
2494           This mitigates both spectre_v2 and retbleed at great cost to
2495           performance.
2496 
2497 config SLS
2498         bool "Mitigate Straight-Line-Speculation"
2499         depends on CC_HAS_SLS && X86_64
2500         select OBJTOOL if HAVE_OBJTOOL
2501         default n
2502         help
2503           Compile the kernel with straight-line-speculation options to guard
2504           against straight line speculation. The kernel image might be slightly
2505           larger.
2506 
2507 endif
2508 
2509 config ARCH_HAS_ADD_PAGES
2510         def_bool y
2511         depends on ARCH_ENABLE_MEMORY_HOTPLUG
2512 
2513 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2514         def_bool y
2515 
2516 menu "Power management and ACPI options"
2517 
2518 config ARCH_HIBERNATION_HEADER
2519         def_bool y
2520         depends on HIBERNATION
2521 
2522 source "kernel/power/Kconfig"
2523 
2524 source "drivers/acpi/Kconfig"
2525 
2526 config X86_APM_BOOT
2527         def_bool y
2528         depends on APM
2529 
2530 menuconfig APM
2531         tristate "APM (Advanced Power Management) BIOS support"
2532         depends on X86_32 && PM_SLEEP
2533         help
2534           APM is a BIOS specification for saving power using several different
2535           techniques. This is mostly useful for battery powered laptops with
2536           APM compliant BIOSes. If you say Y here, the system time will be
2537           reset after a RESUME operation, the /proc/apm device will provide
2538           battery status information, and user-space programs will receive
2539           notification of APM "events" (e.g. battery status change).
2540 
2541           If you select "Y" here, you can disable actual use of the APM
2542           BIOS by passing the "apm=off" option to the kernel at boot time.
2543 
2544           Note that the APM support is almost completely disabled for
2545           machines with more than one CPU.
2546 
2547           In order to use APM, you will need supporting software. For location
2548           and more information, read <file:Documentation/power/apm-acpi.rst>
2549           and the Battery Powered Linux mini-HOWTO, available from
2550           <http://www.tldp.org/docs.html#howto>.
2551 
2552           This driver does not spin down disk drives (see the hdparm(8)
2553           manpage ("man 8 hdparm") for that), and it doesn't turn off
2554           VESA-compliant "green" monitors.
2555 
2556           This driver does not support the TI 4000M TravelMate and the ACER
2557           486/DX4/75 because they don't have compliant BIOSes. Many "green"
2558           desktop machines also don't have compliant BIOSes, and this driver
2559           may cause those machines to panic during the boot phase.
2560 
2561           Generally, if you don't have a battery in your machine, there isn't
2562           much point in using this driver and you should say N. If you get
2563           random kernel OOPSes or reboots that don't seem to be related to
2564           anything, try disabling/enabling this option (or disabling/enabling
2565           APM in your BIOS).
2566 
2567           Some other things you should try when experiencing seemingly random,
2568           "weird" problems:
2569 
2570           1) make sure that you have enough swap space and that it is
2571           enabled.
2572           2) pass the "no-hlt" option to the kernel
2573           3) switch on floating point emulation in the kernel and pass
2574           the "no387" option to the kernel
2575           4) pass the "floppy=nodma" option to the kernel
2576           5) pass the "mem=4M" option to the kernel (thereby disabling
2577           all but the first 4 MB of RAM)
2578           6) make sure that the CPU is not over clocked.
2579           7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2580           8) disable the cache from your BIOS settings
2581           9) install a fan for the video card or exchange video RAM
2582           10) install a better fan for the CPU
2583           11) exchange RAM chips
2584           12) exchange the motherboard.
2585 
2586           To compile this driver as a module, choose M here: the
2587           module will be called apm.
2588 
2589 if APM
2590 
2591 config APM_IGNORE_USER_SUSPEND
2592         bool "Ignore USER SUSPEND"
2593         help
2594           This option will ignore USER SUSPEND requests. On machines with a
2595           compliant APM BIOS, you want to say N. However, on the NEC Versa M
2596           series notebooks, it is necessary to say Y because of a BIOS bug.
2597 
2598 config APM_DO_ENABLE
2599         bool "Enable PM at boot time"
2600         help
2601           Enable APM features at boot time. From page 36 of the APM BIOS
2602           specification: "When disabled, the APM BIOS does not automatically
2603           power manage devices, enter the Standby State, enter the Suspend
2604           State, or take power saving steps in response to CPU Idle calls."
2605           This driver will make CPU Idle calls when Linux is idle (unless this
2606           feature is turned off -- see "Do CPU IDLE calls", below). This
2607           should always save battery power, but more complicated APM features
2608           will be dependent on your BIOS implementation. You may need to turn
2609           this option off if your computer hangs at boot time when using APM
2610           support, or if it beeps continuously instead of suspending. Turn
2611           this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2612           T400CDT. This is off by default since most machines do fine without
2613           this feature.
2614 
2615 config APM_CPU_IDLE
2616         depends on CPU_IDLE
2617         bool "Make CPU Idle calls when idle"
2618         help
2619           Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2620           On some machines, this can activate improved power savings, such as
2621           a slowed CPU clock rate, when the machine is idle. These idle calls
2622           are made after the idle loop has run for some length of time (e.g.,
2623           333 mS). On some machines, this will cause a hang at boot time or
2624           whenever the CPU becomes idle. (On machines with more than one CPU,
2625           this option does nothing.)
2626 
2627 config APM_DISPLAY_BLANK
2628         bool "Enable console blanking using APM"
2629         help
2630           Enable console blanking using the APM. Some laptops can use this to
2631           turn off the LCD backlight when the screen blanker of the Linux
2632           virtual console blanks the screen. Note that this is only used by
2633           the virtual console screen blanker, and won't turn off the backlight
2634           when using the X Window system. This also doesn't have anything to
2635           do with your VESA-compliant power-saving monitor. Further, this
2636           option doesn't work for all laptops -- it might not turn off your
2637           backlight at all, or it might print a lot of errors to the console,
2638           especially if you are using gpm.
2639 
2640 config APM_ALLOW_INTS
2641         bool "Allow interrupts during APM BIOS calls"
2642         help
2643           Normally we disable external interrupts while we are making calls to
2644           the APM BIOS as a measure to lessen the effects of a badly behaving
2645           BIOS implementation.  The BIOS should reenable interrupts if it
2646           needs to.  Unfortunately, some BIOSes do not -- especially those in
2647           many of the newer IBM Thinkpads.  If you experience hangs when you
2648           suspend, try setting this to Y.  Otherwise, say N.
2649 
2650 endif # APM
2651 
2652 source "drivers/cpufreq/Kconfig"
2653 
2654 source "drivers/cpuidle/Kconfig"
2655 
2656 source "drivers/idle/Kconfig"
2657 
2658 endmenu
2659 
2660 menu "Bus options (PCI etc.)"
2661 
2662 choice
2663         prompt "PCI access mode"
2664         depends on X86_32 && PCI
2665         default PCI_GOANY
2666         help
2667           On PCI systems, the BIOS can be used to detect the PCI devices and
2668           determine their configuration. However, some old PCI motherboards
2669           have BIOS bugs and may crash if this is done. Also, some embedded
2670           PCI-based systems don't have any BIOS at all. Linux can also try to
2671           detect the PCI hardware directly without using the BIOS.
2672 
2673           With this option, you can specify how Linux should detect the
2674           PCI devices. If you choose "BIOS", the BIOS will be used,
2675           if you choose "Direct", the BIOS won't be used, and if you
2676           choose "MMConfig", then PCI Express MMCONFIG will be used.
2677           If you choose "Any", the kernel will try MMCONFIG, then the
2678           direct access method and falls back to the BIOS if that doesn't
2679           work. If unsure, go with the default, which is "Any".
2680 
2681 config PCI_GOBIOS
2682         bool "BIOS"
2683 
2684 config PCI_GOMMCONFIG
2685         bool "MMConfig"
2686 
2687 config PCI_GODIRECT
2688         bool "Direct"
2689 
2690 config PCI_GOOLPC
2691         bool "OLPC XO-1"
2692         depends on OLPC
2693 
2694 config PCI_GOANY
2695         bool "Any"
2696 
2697 endchoice
2698 
2699 config PCI_BIOS
2700         def_bool y
2701         depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2702 
2703 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2704 config PCI_DIRECT
2705         def_bool y
2706         depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2707 
2708 config PCI_MMCONFIG
2709         bool "Support mmconfig PCI config space access" if X86_64
2710         default y
2711         depends on PCI && (ACPI || JAILHOUSE_GUEST)
2712         depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2713 
2714 config PCI_OLPC
2715         def_bool y
2716         depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2717 
2718 config PCI_XEN
2719         def_bool y
2720         depends on PCI && XEN
2721 
2722 config MMCONF_FAM10H
2723         def_bool y
2724         depends on X86_64 && PCI_MMCONFIG && ACPI
2725 
2726 config PCI_CNB20LE_QUIRK
2727         bool "Read CNB20LE Host Bridge Windows" if EXPERT
2728         depends on PCI
2729         help
2730           Read the PCI windows out of the CNB20LE host bridge. This allows
2731           PCI hotplug to work on systems with the CNB20LE chipset which do
2732           not have ACPI.
2733 
2734           There's no public spec for this chipset, and this functionality
2735           is known to be incomplete.
2736 
2737           You should say N unless you know you need this.
2738 
2739 config ISA_BUS
2740         bool "ISA bus support on modern systems" if EXPERT
2741         help
2742           Expose ISA bus device drivers and options available for selection and
2743           configuration. Enable this option if your target machine has an ISA
2744           bus. ISA is an older system, displaced by PCI and newer bus
2745           architectures -- if your target machine is modern, it probably does
2746           not have an ISA bus.
2747 
2748           If unsure, say N.
2749 
2750 # x86_64 have no ISA slots, but can have ISA-style DMA.
2751 config ISA_DMA_API
2752         bool "ISA-style DMA support" if (X86_64 && EXPERT)
2753         default y
2754         help
2755           Enables ISA-style DMA support for devices requiring such controllers.
2756           If unsure, say Y.
2757 
2758 if X86_32
2759 
2760 config ISA
2761         bool "ISA support"
2762         help
2763           Find out whether you have ISA slots on your motherboard.  ISA is the
2764           name of a bus system, i.e. the way the CPU talks to the other stuff
2765           inside your box.  Other bus systems are PCI, EISA, MicroChannel
2766           (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2767           newer boards don't support it.  If you have ISA, say Y, otherwise N.
2768 
2769 config SCx200
2770         tristate "NatSemi SCx200 support"
2771         help
2772           This provides basic support for National Semiconductor's
2773           (now AMD's) Geode processors.  The driver probes for the
2774           PCI-IDs of several on-chip devices, so its a good dependency
2775           for other scx200_* drivers.
2776 
2777           If compiled as a module, the driver is named scx200.
2778 
2779 config SCx200HR_TIMER
2780         tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2781         depends on SCx200
2782         default y
2783         help
2784           This driver provides a clocksource built upon the on-chip
2785           27MHz high-resolution timer.  Its also a workaround for
2786           NSC Geode SC-1100's buggy TSC, which loses time when the
2787           processor goes idle (as is done by the scheduler).  The
2788           other workaround is idle=poll boot option.
2789 
2790 config OLPC
2791         bool "One Laptop Per Child support"
2792         depends on !X86_PAE
2793         select GPIOLIB
2794         select OF
2795         select OF_PROMTREE
2796         select IRQ_DOMAIN
2797         select OLPC_EC
2798         help
2799           Add support for detecting the unique features of the OLPC
2800           XO hardware.
2801 
2802 config OLPC_XO1_PM
2803         bool "OLPC XO-1 Power Management"
2804         depends on OLPC && MFD_CS5535=y && PM_SLEEP
2805         help
2806           Add support for poweroff and suspend of the OLPC XO-1 laptop.
2807 
2808 config OLPC_XO1_RTC
2809         bool "OLPC XO-1 Real Time Clock"
2810         depends on OLPC_XO1_PM && RTC_DRV_CMOS
2811         help
2812           Add support for the XO-1 real time clock, which can be used as a
2813           programmable wakeup source.
2814 
2815 config OLPC_XO1_SCI
2816         bool "OLPC XO-1 SCI extras"
2817         depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2818         depends on INPUT=y
2819         select POWER_SUPPLY
2820         help
2821           Add support for SCI-based features of the OLPC XO-1 laptop:
2822            - EC-driven system wakeups
2823            - Power button
2824            - Ebook switch
2825            - Lid switch
2826            - AC adapter status updates
2827            - Battery status updates
2828 
2829 config OLPC_XO15_SCI
2830         bool "OLPC XO-1.5 SCI extras"
2831         depends on OLPC && ACPI
2832         select POWER_SUPPLY
2833         help
2834           Add support for SCI-based features of the OLPC XO-1.5 laptop:
2835            - EC-driven system wakeups
2836            - AC adapter status updates
2837            - Battery status updates
2838 
2839 config ALIX
2840         bool "PCEngines ALIX System Support (LED setup)"
2841         select GPIOLIB
2842         help
2843           This option enables system support for the PCEngines ALIX.
2844           At present this just sets up LEDs for GPIO control on
2845           ALIX2/3/6 boards.  However, other system specific setup should
2846           get added here.
2847 
2848           Note: You must still enable the drivers for GPIO and LED support
2849           (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2850 
2851           Note: You have to set alix.force=1 for boards with Award BIOS.
2852 
2853 config NET5501
2854         bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2855         select GPIOLIB
2856         help
2857           This option enables system support for the Soekris Engineering net5501.
2858 
2859 config GEOS
2860         bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2861         select GPIOLIB
2862         depends on DMI
2863         help
2864           This option enables system support for the Traverse Technologies GEOS.
2865 
2866 config TS5500
2867         bool "Technologic Systems TS-5500 platform support"
2868         depends on MELAN
2869         select CHECK_SIGNATURE
2870         select NEW_LEDS
2871         select LEDS_CLASS
2872         help
2873           This option enables system support for the Technologic Systems TS-5500.
2874 
2875 endif # X86_32
2876 
2877 config AMD_NB
2878         def_bool y
2879         depends on CPU_SUP_AMD && PCI
2880 
2881 endmenu
2882 
2883 menu "Binary Emulations"
2884 
2885 config IA32_EMULATION
2886         bool "IA32 Emulation"
2887         depends on X86_64
2888         select ARCH_WANT_OLD_COMPAT_IPC
2889         select BINFMT_ELF
2890         select COMPAT_OLD_SIGACTION
2891         help
2892           Include code to run legacy 32-bit programs under a
2893           64-bit kernel. You should likely turn this on, unless you're
2894           100% sure that you don't have any 32-bit programs left.
2895 
2896 config X86_X32_ABI
2897         bool "x32 ABI for 64-bit mode"
2898         depends on X86_64
2899         # llvm-objcopy does not convert x86_64 .note.gnu.property or
2900         # compressed debug sections to x86_x32 properly:
2901         # https://github.com/ClangBuiltLinux/linux/issues/514
2902         # https://github.com/ClangBuiltLinux/linux/issues/1141
2903         depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2904         help
2905           Include code to run binaries for the x32 native 32-bit ABI
2906           for 64-bit processors.  An x32 process gets access to the
2907           full 64-bit register file and wide data path while leaving
2908           pointers at 32 bits for smaller memory footprint.
2909 
2910 config COMPAT_32
2911         def_bool y
2912         depends on IA32_EMULATION || X86_32
2913         select HAVE_UID16
2914         select OLD_SIGSUSPEND3
2915 
2916 config COMPAT
2917         def_bool y
2918         depends on IA32_EMULATION || X86_X32_ABI
2919 
2920 config COMPAT_FOR_U64_ALIGNMENT
2921         def_bool y
2922         depends on COMPAT
2923 
2924 endmenu
2925 
2926 config HAVE_ATOMIC_IOMAP
2927         def_bool y
2928         depends on X86_32
2929 
2930 source "arch/x86/kvm/Kconfig"
2931 
2932 source "arch/x86/Kconfig.assembler"