linux/arch/x86/Kconfig
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   1# SPDX-License-Identifier: GPL-2.0
   2# Select 32 or 64 bit
   3config 64BIT
   4        bool "64-bit kernel" if "$(ARCH)" = "x86"
   5        default "$(ARCH)" != "i386"
   6        ---help---
   7          Say yes to build a 64-bit kernel - formerly known as x86_64
   8          Say no to build a 32-bit kernel - formerly known as i386
   9
  10config X86_32
  11        def_bool y
  12        depends on !64BIT
  13        # Options that are inherently 32-bit kernel only:
  14        select ARCH_WANT_IPC_PARSE_VERSION
  15        select CLKSRC_I8253
  16        select CLONE_BACKWARDS
  17        select HAVE_DEBUG_STACKOVERFLOW
  18        select MODULES_USE_ELF_REL
  19        select OLD_SIGACTION
  20        select GENERIC_VDSO_32
  21
  22config X86_64
  23        def_bool y
  24        depends on 64BIT
  25        # Options that are inherently 64-bit kernel only:
  26        select ARCH_HAS_GIGANTIC_PAGE
  27        select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
  28        select ARCH_USE_CMPXCHG_LOCKREF
  29        select HAVE_ARCH_SOFT_DIRTY
  30        select MODULES_USE_ELF_RELA
  31        select NEED_DMA_MAP_STATE
  32        select SWIOTLB
  33        select ARCH_HAS_SYSCALL_WRAPPER
  34
  35config FORCE_DYNAMIC_FTRACE
  36        def_bool y
  37        depends on X86_32
  38        depends on FUNCTION_TRACER
  39        select DYNAMIC_FTRACE
  40        help
  41         We keep the static function tracing (!DYNAMIC_FTRACE) around
  42         in order to test the non static function tracing in the
  43         generic code, as other architectures still use it. But we
  44         only need to keep it around for x86_64. No need to keep it
  45         for x86_32. For x86_32, force DYNAMIC_FTRACE. 
  46#
  47# Arch settings
  48#
  49# ( Note that options that are marked 'if X86_64' could in principle be
  50#   ported to 32-bit as well. )
  51#
  52config X86
  53        def_bool y
  54        #
  55        # Note: keep this list sorted alphabetically
  56        #
  57        select ACPI_LEGACY_TABLES_LOOKUP        if ACPI
  58        select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
  59        select ARCH_32BIT_OFF_T                 if X86_32
  60        select ARCH_CLOCKSOURCE_DATA
  61        select ARCH_CLOCKSOURCE_INIT
  62        select ARCH_HAS_ACPI_TABLE_UPGRADE      if ACPI
  63        select ARCH_HAS_DEBUG_VIRTUAL
  64        select ARCH_HAS_DEVMEM_IS_ALLOWED
  65        select ARCH_HAS_ELF_RANDOMIZE
  66        select ARCH_HAS_FAST_MULTIPLIER
  67        select ARCH_HAS_FILTER_PGPROT
  68        select ARCH_HAS_FORTIFY_SOURCE
  69        select ARCH_HAS_GCOV_PROFILE_ALL
  70        select ARCH_HAS_KCOV                    if X86_64
  71        select ARCH_HAS_MEM_ENCRYPT
  72        select ARCH_HAS_MEMBARRIER_SYNC_CORE
  73        select ARCH_HAS_PMEM_API                if X86_64
  74        select ARCH_HAS_PTE_DEVMAP              if X86_64
  75        select ARCH_HAS_PTE_SPECIAL
  76        select ARCH_HAS_UACCESS_FLUSHCACHE      if X86_64
  77        select ARCH_HAS_UACCESS_MCSAFE          if X86_64 && X86_MCE
  78        select ARCH_HAS_SET_MEMORY
  79        select ARCH_HAS_SET_DIRECT_MAP
  80        select ARCH_HAS_STRICT_KERNEL_RWX
  81        select ARCH_HAS_STRICT_MODULE_RWX
  82        select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
  83        select ARCH_HAS_UBSAN_SANITIZE_ALL
  84        select ARCH_HAVE_NMI_SAFE_CMPXCHG
  85        select ARCH_MIGHT_HAVE_ACPI_PDC         if ACPI
  86        select ARCH_MIGHT_HAVE_PC_PARPORT
  87        select ARCH_MIGHT_HAVE_PC_SERIO
  88        select ARCH_STACKWALK
  89        select ARCH_SUPPORTS_ACPI
  90        select ARCH_SUPPORTS_ATOMIC_RMW
  91        select ARCH_SUPPORTS_NUMA_BALANCING     if X86_64
  92        select ARCH_USE_BUILTIN_BSWAP
  93        select ARCH_USE_QUEUED_RWLOCKS
  94        select ARCH_USE_QUEUED_SPINLOCKS
  95        select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
  96        select ARCH_WANT_DEFAULT_BPF_JIT        if X86_64
  97        select ARCH_WANTS_DYNAMIC_TASK_STRUCT
  98        select ARCH_WANT_HUGE_PMD_SHARE
  99        select ARCH_WANTS_THP_SWAP              if X86_64
 100        select BUILDTIME_TABLE_SORT
 101        select CLKEVT_I8253
 102        select CLOCKSOURCE_VALIDATE_LAST_CYCLE
 103        select CLOCKSOURCE_WATCHDOG
 104        select DCACHE_WORD_ACCESS
 105        select EDAC_ATOMIC_SCRUB
 106        select EDAC_SUPPORT
 107        select GENERIC_CLOCKEVENTS
 108        select GENERIC_CLOCKEVENTS_BROADCAST    if X86_64 || (X86_32 && X86_LOCAL_APIC)
 109        select GENERIC_CLOCKEVENTS_MIN_ADJUST
 110        select GENERIC_CMOS_UPDATE
 111        select GENERIC_CPU_AUTOPROBE
 112        select GENERIC_CPU_VULNERABILITIES
 113        select GENERIC_EARLY_IOREMAP
 114        select GENERIC_FIND_FIRST_BIT
 115        select GENERIC_IOMAP
 116        select GENERIC_IRQ_EFFECTIVE_AFF_MASK   if SMP
 117        select GENERIC_IRQ_MATRIX_ALLOCATOR     if X86_LOCAL_APIC
 118        select GENERIC_IRQ_MIGRATION            if SMP
 119        select GENERIC_IRQ_PROBE
 120        select GENERIC_IRQ_RESERVATION_MODE
 121        select GENERIC_IRQ_SHOW
 122        select GENERIC_PENDING_IRQ              if SMP
 123        select GENERIC_PTDUMP
 124        select GENERIC_SMP_IDLE_THREAD
 125        select GENERIC_STRNCPY_FROM_USER
 126        select GENERIC_STRNLEN_USER
 127        select GENERIC_TIME_VSYSCALL
 128        select GENERIC_GETTIMEOFDAY
 129        select GENERIC_VDSO_TIME_NS
 130        select GUP_GET_PTE_LOW_HIGH             if X86_PAE
 131        select HARDLOCKUP_CHECK_TIMESTAMP       if X86_64
 132        select HAVE_ACPI_APEI                   if ACPI
 133        select HAVE_ACPI_APEI_NMI               if ACPI
 134        select HAVE_ALIGNED_STRUCT_PAGE         if SLUB
 135        select HAVE_ARCH_AUDITSYSCALL
 136        select HAVE_ARCH_HUGE_VMAP              if X86_64 || X86_PAE
 137        select HAVE_ARCH_JUMP_LABEL
 138        select HAVE_ARCH_JUMP_LABEL_RELATIVE
 139        select HAVE_ARCH_KASAN                  if X86_64
 140        select HAVE_ARCH_KASAN_VMALLOC          if X86_64
 141        select HAVE_ARCH_KGDB
 142        select HAVE_ARCH_MMAP_RND_BITS          if MMU
 143        select HAVE_ARCH_MMAP_RND_COMPAT_BITS   if MMU && COMPAT
 144        select HAVE_ARCH_COMPAT_MMAP_BASES      if MMU && COMPAT
 145        select HAVE_ARCH_PREL32_RELOCATIONS
 146        select HAVE_ARCH_SECCOMP_FILTER
 147        select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 148        select HAVE_ARCH_STACKLEAK
 149        select HAVE_ARCH_TRACEHOOK
 150        select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 151        select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
 152        select HAVE_ARCH_VMAP_STACK             if X86_64
 153        select HAVE_ARCH_WITHIN_STACK_FRAMES
 154        select HAVE_ASM_MODVERSIONS
 155        select HAVE_CMPXCHG_DOUBLE
 156        select HAVE_CMPXCHG_LOCAL
 157        select HAVE_CONTEXT_TRACKING            if X86_64
 158        select HAVE_COPY_THREAD_TLS
 159        select HAVE_C_RECORDMCOUNT
 160        select HAVE_DEBUG_KMEMLEAK
 161        select HAVE_DMA_CONTIGUOUS
 162        select HAVE_DYNAMIC_FTRACE
 163        select HAVE_DYNAMIC_FTRACE_WITH_REGS
 164        select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 165        select HAVE_EBPF_JIT
 166        select HAVE_EFFICIENT_UNALIGNED_ACCESS
 167        select HAVE_EISA
 168        select HAVE_EXIT_THREAD
 169        select HAVE_FAST_GUP
 170        select HAVE_FENTRY                      if X86_64 || DYNAMIC_FTRACE
 171        select HAVE_FTRACE_MCOUNT_RECORD
 172        select HAVE_FUNCTION_GRAPH_TRACER
 173        select HAVE_FUNCTION_TRACER
 174        select HAVE_GCC_PLUGINS
 175        select HAVE_HW_BREAKPOINT
 176        select HAVE_IDE
 177        select HAVE_IOREMAP_PROT
 178        select HAVE_IRQ_EXIT_ON_IRQ_STACK       if X86_64
 179        select HAVE_IRQ_TIME_ACCOUNTING
 180        select HAVE_KERNEL_BZIP2
 181        select HAVE_KERNEL_GZIP
 182        select HAVE_KERNEL_LZ4
 183        select HAVE_KERNEL_LZMA
 184        select HAVE_KERNEL_LZO
 185        select HAVE_KERNEL_XZ
 186        select HAVE_KPROBES
 187        select HAVE_KPROBES_ON_FTRACE
 188        select HAVE_FUNCTION_ERROR_INJECTION
 189        select HAVE_KRETPROBES
 190        select HAVE_KVM
 191        select HAVE_LIVEPATCH                   if X86_64
 192        select HAVE_MEMBLOCK_NODE_MAP
 193        select HAVE_MIXED_BREAKPOINTS_REGS
 194        select HAVE_MOD_ARCH_SPECIFIC
 195        select HAVE_MOVE_PMD
 196        select HAVE_NMI
 197        select HAVE_OPROFILE
 198        select HAVE_OPTPROBES
 199        select HAVE_PCSPKR_PLATFORM
 200        select HAVE_PERF_EVENTS
 201        select HAVE_PERF_EVENTS_NMI
 202        select HAVE_HARDLOCKUP_DETECTOR_PERF    if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 203        select HAVE_PCI
 204        select HAVE_PERF_REGS
 205        select HAVE_PERF_USER_STACK_DUMP
 206        select MMU_GATHER_RCU_TABLE_FREE                if PARAVIRT
 207        select HAVE_REGS_AND_STACK_ACCESS_API
 208        select HAVE_RELIABLE_STACKTRACE         if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
 209        select HAVE_FUNCTION_ARG_ACCESS_API
 210        select HAVE_STACKPROTECTOR              if CC_HAS_SANE_STACKPROTECTOR
 211        select HAVE_STACK_VALIDATION            if X86_64
 212        select HAVE_RSEQ
 213        select HAVE_SYSCALL_TRACEPOINTS
 214        select HAVE_UNSTABLE_SCHED_CLOCK
 215        select HAVE_USER_RETURN_NOTIFIER
 216        select HAVE_GENERIC_VDSO
 217        select HOTPLUG_SMT                      if SMP
 218        select IRQ_FORCED_THREADING
 219        select NEED_SG_DMA_LENGTH
 220        select PCI_DOMAINS                      if PCI
 221        select PCI_LOCKLESS_CONFIG              if PCI
 222        select PERF_EVENTS
 223        select RTC_LIB
 224        select RTC_MC146818_LIB
 225        select SPARSE_IRQ
 226        select SRCU
 227        select SYSCTL_EXCEPTION_TRACE
 228        select THREAD_INFO_IN_TASK
 229        select USER_STACKTRACE_SUPPORT
 230        select VIRT_TO_BUS
 231        select X86_FEATURE_NAMES                if PROC_FS
 232        select PROC_PID_ARCH_STATUS             if PROC_FS
 233
 234config INSTRUCTION_DECODER
 235        def_bool y
 236        depends on KPROBES || PERF_EVENTS || UPROBES
 237
 238config OUTPUT_FORMAT
 239        string
 240        default "elf32-i386" if X86_32
 241        default "elf64-x86-64" if X86_64
 242
 243config ARCH_DEFCONFIG
 244        string
 245        default "arch/x86/configs/i386_defconfig" if X86_32
 246        default "arch/x86/configs/x86_64_defconfig" if X86_64
 247
 248config LOCKDEP_SUPPORT
 249        def_bool y
 250
 251config STACKTRACE_SUPPORT
 252        def_bool y
 253
 254config MMU
 255        def_bool y
 256
 257config ARCH_MMAP_RND_BITS_MIN
 258        default 28 if 64BIT
 259        default 8
 260
 261config ARCH_MMAP_RND_BITS_MAX
 262        default 32 if 64BIT
 263        default 16
 264
 265config ARCH_MMAP_RND_COMPAT_BITS_MIN
 266        default 8
 267
 268config ARCH_MMAP_RND_COMPAT_BITS_MAX
 269        default 16
 270
 271config SBUS
 272        bool
 273
 274config GENERIC_ISA_DMA
 275        def_bool y
 276        depends on ISA_DMA_API
 277
 278config GENERIC_BUG
 279        def_bool y
 280        depends on BUG
 281        select GENERIC_BUG_RELATIVE_POINTERS if X86_64
 282
 283config GENERIC_BUG_RELATIVE_POINTERS
 284        bool
 285
 286config ARCH_MAY_HAVE_PC_FDC
 287        def_bool y
 288        depends on ISA_DMA_API
 289
 290config GENERIC_CALIBRATE_DELAY
 291        def_bool y
 292
 293config ARCH_HAS_CPU_RELAX
 294        def_bool y
 295
 296config ARCH_HAS_CACHE_LINE_SIZE
 297        def_bool y
 298
 299config ARCH_HAS_FILTER_PGPROT
 300        def_bool y
 301
 302config HAVE_SETUP_PER_CPU_AREA
 303        def_bool y
 304
 305config NEED_PER_CPU_EMBED_FIRST_CHUNK
 306        def_bool y
 307
 308config NEED_PER_CPU_PAGE_FIRST_CHUNK
 309        def_bool y
 310
 311config ARCH_HIBERNATION_POSSIBLE
 312        def_bool y
 313
 314config ARCH_SUSPEND_POSSIBLE
 315        def_bool y
 316
 317config ARCH_WANT_GENERAL_HUGETLB
 318        def_bool y
 319
 320config ZONE_DMA32
 321        def_bool y if X86_64
 322
 323config AUDIT_ARCH
 324        def_bool y if X86_64
 325
 326config ARCH_SUPPORTS_DEBUG_PAGEALLOC
 327        def_bool y
 328
 329config KASAN_SHADOW_OFFSET
 330        hex
 331        depends on KASAN
 332        default 0xdffffc0000000000
 333
 334config HAVE_INTEL_TXT
 335        def_bool y
 336        depends on INTEL_IOMMU && ACPI
 337
 338config X86_32_SMP
 339        def_bool y
 340        depends on X86_32 && SMP
 341
 342config X86_64_SMP
 343        def_bool y
 344        depends on X86_64 && SMP
 345
 346config X86_32_LAZY_GS
 347        def_bool y
 348        depends on X86_32 && !STACKPROTECTOR
 349
 350config ARCH_SUPPORTS_UPROBES
 351        def_bool y
 352
 353config FIX_EARLYCON_MEM
 354        def_bool y
 355
 356config DYNAMIC_PHYSICAL_MASK
 357        bool
 358
 359config PGTABLE_LEVELS
 360        int
 361        default 5 if X86_5LEVEL
 362        default 4 if X86_64
 363        default 3 if X86_PAE
 364        default 2
 365
 366config CC_HAS_SANE_STACKPROTECTOR
 367        bool
 368        default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
 369        default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
 370        help
 371           We have to make sure stack protector is unconditionally disabled if
 372           the compiler produces broken code.
 373
 374menu "Processor type and features"
 375
 376config ZONE_DMA
 377        bool "DMA memory allocation support" if EXPERT
 378        default y
 379        help
 380          DMA memory allocation support allows devices with less than 32-bit
 381          addressing to allocate within the first 16MB of address space.
 382          Disable if no such devices will be used.
 383
 384          If unsure, say Y.
 385
 386config SMP
 387        bool "Symmetric multi-processing support"
 388        ---help---
 389          This enables support for systems with more than one CPU. If you have
 390          a system with only one CPU, say N. If you have a system with more
 391          than one CPU, say Y.
 392
 393          If you say N here, the kernel will run on uni- and multiprocessor
 394          machines, but will use only one CPU of a multiprocessor machine. If
 395          you say Y here, the kernel will run on many, but not all,
 396          uniprocessor machines. On a uniprocessor machine, the kernel
 397          will run faster if you say N here.
 398
 399          Note that if you say Y here and choose architecture "586" or
 400          "Pentium" under "Processor family", the kernel will not work on 486
 401          architectures. Similarly, multiprocessor kernels for the "PPro"
 402          architecture may not work on all Pentium based boards.
 403
 404          People using multiprocessor machines who say Y here should also say
 405          Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
 406          Management" code will be disabled if you say Y here.
 407
 408          See also <file:Documentation/x86/i386/IO-APIC.rst>,
 409          <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
 410          <http://www.tldp.org/docs.html#howto>.
 411
 412          If you don't know what to do here, say N.
 413
 414config X86_FEATURE_NAMES
 415        bool "Processor feature human-readable names" if EMBEDDED
 416        default y
 417        ---help---
 418          This option compiles in a table of x86 feature bits and corresponding
 419          names.  This is required to support /proc/cpuinfo and a few kernel
 420          messages.  You can disable this to save space, at the expense of
 421          making those few kernel messages show numeric feature bits instead.
 422
 423          If in doubt, say Y.
 424
 425config X86_X2APIC
 426        bool "Support x2apic"
 427        depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
 428        ---help---
 429          This enables x2apic support on CPUs that have this feature.
 430
 431          This allows 32-bit apic IDs (so it can support very large systems),
 432          and accesses the local apic via MSRs not via mmio.
 433
 434          If you don't know what to do here, say N.
 435
 436config X86_MPPARSE
 437        bool "Enable MPS table" if ACPI || SFI
 438        default y
 439        depends on X86_LOCAL_APIC
 440        ---help---
 441          For old smp systems that do not have proper acpi support. Newer systems
 442          (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
 443
 444config GOLDFISH
 445        def_bool y
 446        depends on X86_GOLDFISH
 447
 448config RETPOLINE
 449        bool "Avoid speculative indirect branches in kernel"
 450        default y
 451        select STACK_VALIDATION if HAVE_STACK_VALIDATION
 452        help
 453          Compile kernel with the retpoline compiler options to guard against
 454          kernel-to-user data leaks by avoiding speculative indirect
 455          branches. Requires a compiler with -mindirect-branch=thunk-extern
 456          support for full protection. The kernel may run slower.
 457
 458config X86_CPU_RESCTRL
 459        bool "x86 CPU resource control support"
 460        depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
 461        select KERNFS
 462        select PROC_CPU_RESCTRL         if PROC_FS
 463        help
 464          Enable x86 CPU resource control support.
 465
 466          Provide support for the allocation and monitoring of system resources
 467          usage by the CPU.
 468
 469          Intel calls this Intel Resource Director Technology
 470          (Intel(R) RDT). More information about RDT can be found in the
 471          Intel x86 Architecture Software Developer Manual.
 472
 473          AMD calls this AMD Platform Quality of Service (AMD QoS).
 474          More information about AMD QoS can be found in the AMD64 Technology
 475          Platform Quality of Service Extensions manual.
 476
 477          Say N if unsure.
 478
 479if X86_32
 480config X86_BIGSMP
 481        bool "Support for big SMP systems with more than 8 CPUs"
 482        depends on SMP
 483        ---help---
 484          This option is needed for the systems that have more than 8 CPUs.
 485
 486config X86_EXTENDED_PLATFORM
 487        bool "Support for extended (non-PC) x86 platforms"
 488        default y
 489        ---help---
 490          If you disable this option then the kernel will only support
 491          standard PC platforms. (which covers the vast majority of
 492          systems out there.)
 493
 494          If you enable this option then you'll be able to select support
 495          for the following (non-PC) 32 bit x86 platforms:
 496                Goldfish (Android emulator)
 497                AMD Elan
 498                RDC R-321x SoC
 499                SGI 320/540 (Visual Workstation)
 500                STA2X11-based (e.g. Northville)
 501                Moorestown MID devices
 502
 503          If you have one of these systems, or if you want to build a
 504          generic distribution kernel, say Y here - otherwise say N.
 505endif
 506
 507if X86_64
 508config X86_EXTENDED_PLATFORM
 509        bool "Support for extended (non-PC) x86 platforms"
 510        default y
 511        ---help---
 512          If you disable this option then the kernel will only support
 513          standard PC platforms. (which covers the vast majority of
 514          systems out there.)
 515
 516          If you enable this option then you'll be able to select support
 517          for the following (non-PC) 64 bit x86 platforms:
 518                Numascale NumaChip
 519                ScaleMP vSMP
 520                SGI Ultraviolet
 521
 522          If you have one of these systems, or if you want to build a
 523          generic distribution kernel, say Y here - otherwise say N.
 524endif
 525# This is an alphabetically sorted list of 64 bit extended platforms
 526# Please maintain the alphabetic order if and when there are additions
 527config X86_NUMACHIP
 528        bool "Numascale NumaChip"
 529        depends on X86_64
 530        depends on X86_EXTENDED_PLATFORM
 531        depends on NUMA
 532        depends on SMP
 533        depends on X86_X2APIC
 534        depends on PCI_MMCONFIG
 535        ---help---
 536          Adds support for Numascale NumaChip large-SMP systems. Needed to
 537          enable more than ~168 cores.
 538          If you don't have one of these, you should say N here.
 539
 540config X86_VSMP
 541        bool "ScaleMP vSMP"
 542        select HYPERVISOR_GUEST
 543        select PARAVIRT
 544        depends on X86_64 && PCI
 545        depends on X86_EXTENDED_PLATFORM
 546        depends on SMP
 547        ---help---
 548          Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
 549          supposed to run on these EM64T-based machines.  Only choose this option
 550          if you have one of these machines.
 551
 552config X86_UV
 553        bool "SGI Ultraviolet"
 554        depends on X86_64
 555        depends on X86_EXTENDED_PLATFORM
 556        depends on NUMA
 557        depends on EFI
 558        depends on X86_X2APIC
 559        depends on PCI
 560        ---help---
 561          This option is needed in order to support SGI Ultraviolet systems.
 562          If you don't have one of these, you should say N here.
 563
 564# Following is an alphabetically sorted list of 32 bit extended platforms
 565# Please maintain the alphabetic order if and when there are additions
 566
 567config X86_GOLDFISH
 568        bool "Goldfish (Virtual Platform)"
 569        depends on X86_EXTENDED_PLATFORM
 570        ---help---
 571         Enable support for the Goldfish virtual platform used primarily
 572         for Android development. Unless you are building for the Android
 573         Goldfish emulator say N here.
 574
 575config X86_INTEL_CE
 576        bool "CE4100 TV platform"
 577        depends on PCI
 578        depends on PCI_GODIRECT
 579        depends on X86_IO_APIC
 580        depends on X86_32
 581        depends on X86_EXTENDED_PLATFORM
 582        select X86_REBOOTFIXUPS
 583        select OF
 584        select OF_EARLY_FLATTREE
 585        ---help---
 586          Select for the Intel CE media processor (CE4100) SOC.
 587          This option compiles in support for the CE4100 SOC for settop
 588          boxes and media devices.
 589
 590config X86_INTEL_MID
 591        bool "Intel MID platform support"
 592        depends on X86_EXTENDED_PLATFORM
 593        depends on X86_PLATFORM_DEVICES
 594        depends on PCI
 595        depends on X86_64 || (PCI_GOANY && X86_32)
 596        depends on X86_IO_APIC
 597        select SFI
 598        select I2C
 599        select DW_APB_TIMER
 600        select APB_TIMER
 601        select INTEL_SCU_IPC
 602        select MFD_INTEL_MSIC
 603        ---help---
 604          Select to build a kernel capable of supporting Intel MID (Mobile
 605          Internet Device) platform systems which do not have the PCI legacy
 606          interfaces. If you are building for a PC class system say N here.
 607
 608          Intel MID platforms are based on an Intel processor and chipset which
 609          consume less power than most of the x86 derivatives.
 610
 611config X86_INTEL_QUARK
 612        bool "Intel Quark platform support"
 613        depends on X86_32
 614        depends on X86_EXTENDED_PLATFORM
 615        depends on X86_PLATFORM_DEVICES
 616        depends on X86_TSC
 617        depends on PCI
 618        depends on PCI_GOANY
 619        depends on X86_IO_APIC
 620        select IOSF_MBI
 621        select INTEL_IMR
 622        select COMMON_CLK
 623        ---help---
 624          Select to include support for Quark X1000 SoC.
 625          Say Y here if you have a Quark based system such as the Arduino
 626          compatible Intel Galileo.
 627
 628config X86_INTEL_LPSS
 629        bool "Intel Low Power Subsystem Support"
 630        depends on X86 && ACPI && PCI
 631        select COMMON_CLK
 632        select PINCTRL
 633        select IOSF_MBI
 634        ---help---
 635          Select to build support for Intel Low Power Subsystem such as
 636          found on Intel Lynxpoint PCH. Selecting this option enables
 637          things like clock tree (common clock framework) and pincontrol
 638          which are needed by the LPSS peripheral drivers.
 639
 640config X86_AMD_PLATFORM_DEVICE
 641        bool "AMD ACPI2Platform devices support"
 642        depends on ACPI
 643        select COMMON_CLK
 644        select PINCTRL
 645        ---help---
 646          Select to interpret AMD specific ACPI device to platform device
 647          such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
 648          I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
 649          implemented under PINCTRL subsystem.
 650
 651config IOSF_MBI
 652        tristate "Intel SoC IOSF Sideband support for SoC platforms"
 653        depends on PCI
 654        ---help---
 655          This option enables sideband register access support for Intel SoC
 656          platforms. On these platforms the IOSF sideband is used in lieu of
 657          MSR's for some register accesses, mostly but not limited to thermal
 658          and power. Drivers may query the availability of this device to
 659          determine if they need the sideband in order to work on these
 660          platforms. The sideband is available on the following SoC products.
 661          This list is not meant to be exclusive.
 662           - BayTrail
 663           - Braswell
 664           - Quark
 665
 666          You should say Y if you are running a kernel on one of these SoC's.
 667
 668config IOSF_MBI_DEBUG
 669        bool "Enable IOSF sideband access through debugfs"
 670        depends on IOSF_MBI && DEBUG_FS
 671        ---help---
 672          Select this option to expose the IOSF sideband access registers (MCR,
 673          MDR, MCRX) through debugfs to write and read register information from
 674          different units on the SoC. This is most useful for obtaining device
 675          state information for debug and analysis. As this is a general access
 676          mechanism, users of this option would have specific knowledge of the
 677          device they want to access.
 678
 679          If you don't require the option or are in doubt, say N.
 680
 681config X86_RDC321X
 682        bool "RDC R-321x SoC"
 683        depends on X86_32
 684        depends on X86_EXTENDED_PLATFORM
 685        select M486
 686        select X86_REBOOTFIXUPS
 687        ---help---
 688          This option is needed for RDC R-321x system-on-chip, also known
 689          as R-8610-(G).
 690          If you don't have one of these chips, you should say N here.
 691
 692config X86_32_NON_STANDARD
 693        bool "Support non-standard 32-bit SMP architectures"
 694        depends on X86_32 && SMP
 695        depends on X86_EXTENDED_PLATFORM
 696        ---help---
 697          This option compiles in the bigsmp and STA2X11 default
 698          subarchitectures.  It is intended for a generic binary
 699          kernel. If you select them all, kernel will probe it one by
 700          one and will fallback to default.
 701
 702# Alphabetically sorted list of Non standard 32 bit platforms
 703
 704config X86_SUPPORTS_MEMORY_FAILURE
 705        def_bool y
 706        # MCE code calls memory_failure():
 707        depends on X86_MCE
 708        # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
 709        # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
 710        depends on X86_64 || !SPARSEMEM
 711        select ARCH_SUPPORTS_MEMORY_FAILURE
 712
 713config STA2X11
 714        bool "STA2X11 Companion Chip Support"
 715        depends on X86_32_NON_STANDARD && PCI
 716        select SWIOTLB
 717        select MFD_STA2X11
 718        select GPIOLIB
 719        ---help---
 720          This adds support for boards based on the STA2X11 IO-Hub,
 721          a.k.a. "ConneXt". The chip is used in place of the standard
 722          PC chipset, so all "standard" peripherals are missing. If this
 723          option is selected the kernel will still be able to boot on
 724          standard PC machines.
 725
 726config X86_32_IRIS
 727        tristate "Eurobraille/Iris poweroff module"
 728        depends on X86_32
 729        ---help---
 730          The Iris machines from EuroBraille do not have APM or ACPI support
 731          to shut themselves down properly.  A special I/O sequence is
 732          needed to do so, which is what this module does at
 733          kernel shutdown.
 734
 735          This is only for Iris machines from EuroBraille.
 736
 737          If unused, say N.
 738
 739config SCHED_OMIT_FRAME_POINTER
 740        def_bool y
 741        prompt "Single-depth WCHAN output"
 742        depends on X86
 743        ---help---
 744          Calculate simpler /proc/<PID>/wchan values. If this option
 745          is disabled then wchan values will recurse back to the
 746          caller function. This provides more accurate wchan values,
 747          at the expense of slightly more scheduling overhead.
 748
 749          If in doubt, say "Y".
 750
 751menuconfig HYPERVISOR_GUEST
 752        bool "Linux guest support"
 753        ---help---
 754          Say Y here to enable options for running Linux under various hyper-
 755          visors. This option enables basic hypervisor detection and platform
 756          setup.
 757
 758          If you say N, all options in this submenu will be skipped and
 759          disabled, and Linux guest support won't be built in.
 760
 761if HYPERVISOR_GUEST
 762
 763config PARAVIRT
 764        bool "Enable paravirtualization code"
 765        ---help---
 766          This changes the kernel so it can modify itself when it is run
 767          under a hypervisor, potentially improving performance significantly
 768          over full virtualization.  However, when run without a hypervisor
 769          the kernel is theoretically slower and slightly larger.
 770
 771config PARAVIRT_XXL
 772        bool
 773
 774config PARAVIRT_DEBUG
 775        bool "paravirt-ops debugging"
 776        depends on PARAVIRT && DEBUG_KERNEL
 777        ---help---
 778          Enable to debug paravirt_ops internals.  Specifically, BUG if
 779          a paravirt_op is missing when it is called.
 780
 781config PARAVIRT_SPINLOCKS
 782        bool "Paravirtualization layer for spinlocks"
 783        depends on PARAVIRT && SMP
 784        ---help---
 785          Paravirtualized spinlocks allow a pvops backend to replace the
 786          spinlock implementation with something virtualization-friendly
 787          (for example, block the virtual CPU rather than spinning).
 788
 789          It has a minimal impact on native kernels and gives a nice performance
 790          benefit on paravirtualized KVM / Xen kernels.
 791
 792          If you are unsure how to answer this question, answer Y.
 793
 794config X86_HV_CALLBACK_VECTOR
 795        def_bool n
 796
 797source "arch/x86/xen/Kconfig"
 798
 799config KVM_GUEST
 800        bool "KVM Guest support (including kvmclock)"
 801        depends on PARAVIRT
 802        select PARAVIRT_CLOCK
 803        select ARCH_CPUIDLE_HALTPOLL
 804        default y
 805        ---help---
 806          This option enables various optimizations for running under the KVM
 807          hypervisor. It includes a paravirtualized clock, so that instead
 808          of relying on a PIT (or probably other) emulation by the
 809          underlying device model, the host provides the guest with
 810          timing infrastructure such as time of day, and system time
 811
 812config ARCH_CPUIDLE_HALTPOLL
 813        def_bool n
 814        prompt "Disable host haltpoll when loading haltpoll driver"
 815        help
 816          If virtualized under KVM, disable host haltpoll.
 817
 818config PVH
 819        bool "Support for running PVH guests"
 820        ---help---
 821          This option enables the PVH entry point for guest virtual machines
 822          as specified in the x86/HVM direct boot ABI.
 823
 824config KVM_DEBUG_FS
 825        bool "Enable debug information for KVM Guests in debugfs"
 826        depends on KVM_GUEST && DEBUG_FS
 827        ---help---
 828          This option enables collection of various statistics for KVM guest.
 829          Statistics are displayed in debugfs filesystem. Enabling this option
 830          may incur significant overhead.
 831
 832config PARAVIRT_TIME_ACCOUNTING
 833        bool "Paravirtual steal time accounting"
 834        depends on PARAVIRT
 835        ---help---
 836          Select this option to enable fine granularity task steal time
 837          accounting. Time spent executing other tasks in parallel with
 838          the current vCPU is discounted from the vCPU power. To account for
 839          that, there can be a small performance impact.
 840
 841          If in doubt, say N here.
 842
 843config PARAVIRT_CLOCK
 844        bool
 845
 846config JAILHOUSE_GUEST
 847        bool "Jailhouse non-root cell support"
 848        depends on X86_64 && PCI
 849        select X86_PM_TIMER
 850        ---help---
 851          This option allows to run Linux as guest in a Jailhouse non-root
 852          cell. You can leave this option disabled if you only want to start
 853          Jailhouse and run Linux afterwards in the root cell.
 854
 855config ACRN_GUEST
 856        bool "ACRN Guest support"
 857        depends on X86_64
 858        select X86_HV_CALLBACK_VECTOR
 859        help
 860          This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
 861          a flexible, lightweight reference open-source hypervisor, built with
 862          real-time and safety-criticality in mind. It is built for embedded
 863          IOT with small footprint and real-time features. More details can be
 864          found in https://projectacrn.org/.
 865
 866endif #HYPERVISOR_GUEST
 867
 868source "arch/x86/Kconfig.cpu"
 869
 870config HPET_TIMER
 871        def_bool X86_64
 872        prompt "HPET Timer Support" if X86_32
 873        ---help---
 874          Use the IA-PC HPET (High Precision Event Timer) to manage
 875          time in preference to the PIT and RTC, if a HPET is
 876          present.
 877          HPET is the next generation timer replacing legacy 8254s.
 878          The HPET provides a stable time base on SMP
 879          systems, unlike the TSC, but it is more expensive to access,
 880          as it is off-chip.  The interface used is documented
 881          in the HPET spec, revision 1.
 882
 883          You can safely choose Y here.  However, HPET will only be
 884          activated if the platform and the BIOS support this feature.
 885          Otherwise the 8254 will be used for timing services.
 886
 887          Choose N to continue using the legacy 8254 timer.
 888
 889config HPET_EMULATE_RTC
 890        def_bool y
 891        depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
 892
 893config APB_TIMER
 894        def_bool y if X86_INTEL_MID
 895        prompt "Intel MID APB Timer Support" if X86_INTEL_MID
 896        select DW_APB_TIMER
 897        depends on X86_INTEL_MID && SFI
 898        help
 899         APB timer is the replacement for 8254, HPET on X86 MID platforms.
 900         The APBT provides a stable time base on SMP
 901         systems, unlike the TSC, but it is more expensive to access,
 902         as it is off-chip. APB timers are always running regardless of CPU
 903         C states, they are used as per CPU clockevent device when possible.
 904
 905# Mark as expert because too many people got it wrong.
 906# The code disables itself when not needed.
 907config DMI
 908        default y
 909        select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
 910        bool "Enable DMI scanning" if EXPERT
 911        ---help---
 912          Enabled scanning of DMI to identify machine quirks. Say Y
 913          here unless you have verified that your setup is not
 914          affected by entries in the DMI blacklist. Required by PNP
 915          BIOS code.
 916
 917config GART_IOMMU
 918        bool "Old AMD GART IOMMU support"
 919        select IOMMU_HELPER
 920        select SWIOTLB
 921        depends on X86_64 && PCI && AMD_NB
 922        ---help---
 923          Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
 924          GART based hardware IOMMUs.
 925
 926          The GART supports full DMA access for devices with 32-bit access
 927          limitations, on systems with more than 3 GB. This is usually needed
 928          for USB, sound, many IDE/SATA chipsets and some other devices.
 929
 930          Newer systems typically have a modern AMD IOMMU, supported via
 931          the CONFIG_AMD_IOMMU=y config option.
 932
 933          In normal configurations this driver is only active when needed:
 934          there's more than 3 GB of memory and the system contains a
 935          32-bit limited device.
 936
 937          If unsure, say Y.
 938
 939config MAXSMP
 940        bool "Enable Maximum number of SMP Processors and NUMA Nodes"
 941        depends on X86_64 && SMP && DEBUG_KERNEL
 942        select CPUMASK_OFFSTACK
 943        ---help---
 944          Enable maximum number of CPUS and NUMA Nodes for this architecture.
 945          If unsure, say N.
 946
 947#
 948# The maximum number of CPUs supported:
 949#
 950# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
 951# and which can be configured interactively in the
 952# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
 953#
 954# The ranges are different on 32-bit and 64-bit kernels, depending on
 955# hardware capabilities and scalability features of the kernel.
 956#
 957# ( If MAXSMP is enabled we just use the highest possible value and disable
 958#   interactive configuration. )
 959#
 960
 961config NR_CPUS_RANGE_BEGIN
 962        int
 963        default NR_CPUS_RANGE_END if MAXSMP
 964        default    1 if !SMP
 965        default    2
 966
 967config NR_CPUS_RANGE_END
 968        int
 969        depends on X86_32
 970        default   64 if  SMP &&  X86_BIGSMP
 971        default    8 if  SMP && !X86_BIGSMP
 972        default    1 if !SMP
 973
 974config NR_CPUS_RANGE_END
 975        int
 976        depends on X86_64
 977        default 8192 if  SMP && CPUMASK_OFFSTACK
 978        default  512 if  SMP && !CPUMASK_OFFSTACK
 979        default    1 if !SMP
 980
 981config NR_CPUS_DEFAULT
 982        int
 983        depends on X86_32
 984        default   32 if  X86_BIGSMP
 985        default    8 if  SMP
 986        default    1 if !SMP
 987
 988config NR_CPUS_DEFAULT
 989        int
 990        depends on X86_64
 991        default 8192 if  MAXSMP
 992        default   64 if  SMP
 993        default    1 if !SMP
 994
 995config NR_CPUS
 996        int "Maximum number of CPUs" if SMP && !MAXSMP
 997        range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
 998        default NR_CPUS_DEFAULT
 999        ---help---
1000          This allows you to specify the maximum number of CPUs which this
1001          kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1002          supported value is 8192, otherwise the maximum value is 512.  The
1003          minimum value which makes sense is 2.
1004
1005          This is purely to save memory: each supported CPU adds about 8KB
1006          to the kernel image.
1007
1008config SCHED_SMT
1009        def_bool y if SMP
1010
1011config SCHED_MC
1012        def_bool y
1013        prompt "Multi-core scheduler support"
1014        depends on SMP
1015        ---help---
1016          Multi-core scheduler support improves the CPU scheduler's decision
1017          making when dealing with multi-core CPU chips at a cost of slightly
1018          increased overhead in some places. If unsure say N here.
1019
1020config SCHED_MC_PRIO
1021        bool "CPU core priorities scheduler support"
1022        depends on SCHED_MC && CPU_SUP_INTEL
1023        select X86_INTEL_PSTATE
1024        select CPU_FREQ
1025        default y
1026        ---help---
1027          Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1028          core ordering determined at manufacturing time, which allows
1029          certain cores to reach higher turbo frequencies (when running
1030          single threaded workloads) than others.
1031
1032          Enabling this kernel feature teaches the scheduler about
1033          the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1034          scheduler's CPU selection logic accordingly, so that higher
1035          overall system performance can be achieved.
1036
1037          This feature will have no effect on CPUs without this feature.
1038
1039          If unsure say Y here.
1040
1041config UP_LATE_INIT
1042        def_bool y
1043        depends on !SMP && X86_LOCAL_APIC
1044
1045config X86_UP_APIC
1046        bool "Local APIC support on uniprocessors" if !PCI_MSI
1047        default PCI_MSI
1048        depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1049        ---help---
1050          A local APIC (Advanced Programmable Interrupt Controller) is an
1051          integrated interrupt controller in the CPU. If you have a single-CPU
1052          system which has a processor with a local APIC, you can say Y here to
1053          enable and use it. If you say Y here even though your machine doesn't
1054          have a local APIC, then the kernel will still run with no slowdown at
1055          all. The local APIC supports CPU-generated self-interrupts (timer,
1056          performance counters), and the NMI watchdog which detects hard
1057          lockups.
1058
1059config X86_UP_IOAPIC
1060        bool "IO-APIC support on uniprocessors"
1061        depends on X86_UP_APIC
1062        ---help---
1063          An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1064          SMP-capable replacement for PC-style interrupt controllers. Most
1065          SMP systems and many recent uniprocessor systems have one.
1066
1067          If you have a single-CPU system with an IO-APIC, you can say Y here
1068          to use it. If you say Y here even though your machine doesn't have
1069          an IO-APIC, then the kernel will still run with no slowdown at all.
1070
1071config X86_LOCAL_APIC
1072        def_bool y
1073        depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1074        select IRQ_DOMAIN_HIERARCHY
1075        select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1076
1077config X86_IO_APIC
1078        def_bool y
1079        depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1080
1081config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1082        bool "Reroute for broken boot IRQs"
1083        depends on X86_IO_APIC
1084        ---help---
1085          This option enables a workaround that fixes a source of
1086          spurious interrupts. This is recommended when threaded
1087          interrupt handling is used on systems where the generation of
1088          superfluous "boot interrupts" cannot be disabled.
1089
1090          Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1091          entry in the chipset's IO-APIC is masked (as, e.g. the RT
1092          kernel does during interrupt handling). On chipsets where this
1093          boot IRQ generation cannot be disabled, this workaround keeps
1094          the original IRQ line masked so that only the equivalent "boot
1095          IRQ" is delivered to the CPUs. The workaround also tells the
1096          kernel to set up the IRQ handler on the boot IRQ line. In this
1097          way only one interrupt is delivered to the kernel. Otherwise
1098          the spurious second interrupt may cause the kernel to bring
1099          down (vital) interrupt lines.
1100
1101          Only affects "broken" chipsets. Interrupt sharing may be
1102          increased on these systems.
1103
1104config X86_MCE
1105        bool "Machine Check / overheating reporting"
1106        select GENERIC_ALLOCATOR
1107        default y
1108        ---help---
1109          Machine Check support allows the processor to notify the
1110          kernel if it detects a problem (e.g. overheating, data corruption).
1111          The action the kernel takes depends on the severity of the problem,
1112          ranging from warning messages to halting the machine.
1113
1114config X86_MCELOG_LEGACY
1115        bool "Support for deprecated /dev/mcelog character device"
1116        depends on X86_MCE
1117        ---help---
1118          Enable support for /dev/mcelog which is needed by the old mcelog
1119          userspace logging daemon. Consider switching to the new generation
1120          rasdaemon solution.
1121
1122config X86_MCE_INTEL
1123        def_bool y
1124        prompt "Intel MCE features"
1125        depends on X86_MCE && X86_LOCAL_APIC
1126        ---help---
1127           Additional support for intel specific MCE features such as
1128           the thermal monitor.
1129
1130config X86_MCE_AMD
1131        def_bool y
1132        prompt "AMD MCE features"
1133        depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1134        ---help---
1135           Additional support for AMD specific MCE features such as
1136           the DRAM Error Threshold.
1137
1138config X86_ANCIENT_MCE
1139        bool "Support for old Pentium 5 / WinChip machine checks"
1140        depends on X86_32 && X86_MCE
1141        ---help---
1142          Include support for machine check handling on old Pentium 5 or WinChip
1143          systems. These typically need to be enabled explicitly on the command
1144          line.
1145
1146config X86_MCE_THRESHOLD
1147        depends on X86_MCE_AMD || X86_MCE_INTEL
1148        def_bool y
1149
1150config X86_MCE_INJECT
1151        depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1152        tristate "Machine check injector support"
1153        ---help---
1154          Provide support for injecting machine checks for testing purposes.
1155          If you don't know what a machine check is and you don't do kernel
1156          QA it is safe to say n.
1157
1158config X86_THERMAL_VECTOR
1159        def_bool y
1160        depends on X86_MCE_INTEL
1161
1162source "arch/x86/events/Kconfig"
1163
1164config X86_LEGACY_VM86
1165        bool "Legacy VM86 support"
1166        depends on X86_32
1167        ---help---
1168          This option allows user programs to put the CPU into V8086
1169          mode, which is an 80286-era approximation of 16-bit real mode.
1170
1171          Some very old versions of X and/or vbetool require this option
1172          for user mode setting.  Similarly, DOSEMU will use it if
1173          available to accelerate real mode DOS programs.  However, any
1174          recent version of DOSEMU, X, or vbetool should be fully
1175          functional even without kernel VM86 support, as they will all
1176          fall back to software emulation. Nevertheless, if you are using
1177          a 16-bit DOS program where 16-bit performance matters, vm86
1178          mode might be faster than emulation and you might want to
1179          enable this option.
1180
1181          Note that any app that works on a 64-bit kernel is unlikely to
1182          need this option, as 64-bit kernels don't, and can't, support
1183          V8086 mode. This option is also unrelated to 16-bit protected
1184          mode and is not needed to run most 16-bit programs under Wine.
1185
1186          Enabling this option increases the complexity of the kernel
1187          and slows down exception handling a tiny bit.
1188
1189          If unsure, say N here.
1190
1191config VM86
1192        bool
1193        default X86_LEGACY_VM86
1194
1195config X86_16BIT
1196        bool "Enable support for 16-bit segments" if EXPERT
1197        default y
1198        depends on MODIFY_LDT_SYSCALL
1199        ---help---
1200          This option is required by programs like Wine to run 16-bit
1201          protected mode legacy code on x86 processors.  Disabling
1202          this option saves about 300 bytes on i386, or around 6K text
1203          plus 16K runtime memory on x86-64,
1204
1205config X86_ESPFIX32
1206        def_bool y
1207        depends on X86_16BIT && X86_32
1208
1209config X86_ESPFIX64
1210        def_bool y
1211        depends on X86_16BIT && X86_64
1212
1213config X86_VSYSCALL_EMULATION
1214        bool "Enable vsyscall emulation" if EXPERT
1215        default y
1216        depends on X86_64
1217        ---help---
1218         This enables emulation of the legacy vsyscall page.  Disabling
1219         it is roughly equivalent to booting with vsyscall=none, except
1220         that it will also disable the helpful warning if a program
1221         tries to use a vsyscall.  With this option set to N, offending
1222         programs will just segfault, citing addresses of the form
1223         0xffffffffff600?00.
1224
1225         This option is required by many programs built before 2013, and
1226         care should be used even with newer programs if set to N.
1227
1228         Disabling this option saves about 7K of kernel size and
1229         possibly 4K of additional runtime pagetable memory.
1230
1231config X86_IOPL_IOPERM
1232        bool "IOPERM and IOPL Emulation"
1233        default y
1234        ---help---
1235          This enables the ioperm() and iopl() syscalls which are necessary
1236          for legacy applications.
1237
1238          Legacy IOPL support is an overbroad mechanism which allows user
1239          space aside of accessing all 65536 I/O ports also to disable
1240          interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1241          capabilities and permission from potentially active security
1242          modules.
1243
1244          The emulation restricts the functionality of the syscall to
1245          only allowing the full range I/O port access, but prevents the
1246          ability to disable interrupts from user space which would be
1247          granted if the hardware IOPL mechanism would be used.
1248
1249config TOSHIBA
1250        tristate "Toshiba Laptop support"
1251        depends on X86_32
1252        ---help---
1253          This adds a driver to safely access the System Management Mode of
1254          the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1255          not work on models with a Phoenix BIOS. The System Management Mode
1256          is used to set the BIOS and power saving options on Toshiba portables.
1257
1258          For information on utilities to make use of this driver see the
1259          Toshiba Linux utilities web site at:
1260          <http://www.buzzard.org.uk/toshiba/>.
1261
1262          Say Y if you intend to run this kernel on a Toshiba portable.
1263          Say N otherwise.
1264
1265config I8K
1266        tristate "Dell i8k legacy laptop support"
1267        select HWMON
1268        select SENSORS_DELL_SMM
1269        ---help---
1270          This option enables legacy /proc/i8k userspace interface in hwmon
1271          dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1272          temperature and allows controlling fan speeds of Dell laptops via
1273          System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1274          it reports also power and hotkey status. For fan speed control is
1275          needed userspace package i8kutils.
1276
1277          Say Y if you intend to run this kernel on old Dell laptops or want to
1278          use userspace package i8kutils.
1279          Say N otherwise.
1280
1281config 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
1298config MICROCODE
1299        bool "CPU microcode loading support"
1300        default y
1301        depends on CPU_SUP_AMD || CPU_SUP_INTEL
1302        select FW_LOADER
1303        ---help---
1304          If you say Y here, you will be able to update the microcode on
1305          Intel and AMD processors. The Intel support is for the IA32 family,
1306          e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1307          AMD support is for families 0x10 and later. You will obviously need
1308          the actual microcode binary data itself which is not shipped with
1309          the Linux kernel.
1310
1311          The preferred method to load microcode from a detached initrd is described
1312          in Documentation/x86/microcode.rst. For that you need to enable
1313          CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1314          initrd for microcode blobs.
1315
1316          In addition, you can build the microcode into the kernel. For that you
1317          need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1318          config option.
1319
1320config MICROCODE_INTEL
1321        bool "Intel microcode loading support"
1322        depends on MICROCODE
1323        default MICROCODE
1324        select FW_LOADER
1325        ---help---
1326          This options enables microcode patch loading support for Intel
1327          processors.
1328
1329          For the current Intel microcode data package go to
1330          <https://downloadcenter.intel.com> and search for
1331          'Linux Processor Microcode Data File'.
1332
1333config MICROCODE_AMD
1334        bool "AMD microcode loading support"
1335        depends on MICROCODE
1336        select FW_LOADER
1337        ---help---
1338          If you select this option, microcode patch loading support for AMD
1339          processors will be enabled.
1340
1341config MICROCODE_OLD_INTERFACE
1342        bool "Ancient loading interface (DEPRECATED)"
1343        default n
1344        depends on MICROCODE
1345        ---help---
1346          DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1347          which was used by userspace tools like iucode_tool and microcode.ctl.
1348          It is inadequate because it runs too late to be able to properly
1349          load microcode on a machine and it needs special tools. Instead, you
1350          should've switched to the early loading method with the initrd or
1351          builtin microcode by now: Documentation/x86/microcode.rst
1352
1353config X86_MSR
1354        tristate "/dev/cpu/*/msr - Model-specific register support"
1355        ---help---
1356          This device gives privileged processes access to the x86
1357          Model-Specific Registers (MSRs).  It is a character device with
1358          major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1359          MSR accesses are directed to a specific CPU on multi-processor
1360          systems.
1361
1362config X86_CPUID
1363        tristate "/dev/cpu/*/cpuid - CPU information support"
1364        ---help---
1365          This device gives processes access to the x86 CPUID instruction to
1366          be executed on a specific processor.  It is a character device
1367          with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1368          /dev/cpu/31/cpuid.
1369
1370choice
1371        prompt "High Memory Support"
1372        default HIGHMEM4G
1373        depends on X86_32
1374
1375config NOHIGHMEM
1376        bool "off"
1377        ---help---
1378          Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1379          However, the address space of 32-bit x86 processors is only 4
1380          Gigabytes large. That means that, if you have a large amount of
1381          physical memory, not all of it can be "permanently mapped" by the
1382          kernel. The physical memory that's not permanently mapped is called
1383          "high memory".
1384
1385          If you are compiling a kernel which will never run on a machine with
1386          more than 1 Gigabyte total physical RAM, answer "off" here (default
1387          choice and suitable for most users). This will result in a "3GB/1GB"
1388          split: 3GB are mapped so that each process sees a 3GB virtual memory
1389          space and the remaining part of the 4GB virtual memory space is used
1390          by the kernel to permanently map as much physical memory as
1391          possible.
1392
1393          If the machine has between 1 and 4 Gigabytes physical RAM, then
1394          answer "4GB" here.
1395
1396          If more than 4 Gigabytes is used then answer "64GB" here. This
1397          selection turns Intel PAE (Physical Address Extension) mode on.
1398          PAE implements 3-level paging on IA32 processors. PAE is fully
1399          supported by Linux, PAE mode is implemented on all recent Intel
1400          processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1401          then the kernel will not boot on CPUs that don't support PAE!
1402
1403          The actual amount of total physical memory will either be
1404          auto detected or can be forced by using a kernel command line option
1405          such as "mem=256M". (Try "man bootparam" or see the documentation of
1406          your boot loader (lilo or loadlin) about how to pass options to the
1407          kernel at boot time.)
1408
1409          If unsure, say "off".
1410
1411config HIGHMEM4G
1412        bool "4GB"
1413        ---help---
1414          Select this if you have a 32-bit processor and between 1 and 4
1415          gigabytes of physical RAM.
1416
1417config HIGHMEM64G
1418        bool "64GB"
1419        depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1420        select X86_PAE
1421        ---help---
1422          Select this if you have a 32-bit processor and more than 4
1423          gigabytes of physical RAM.
1424
1425endchoice
1426
1427choice
1428        prompt "Memory split" if EXPERT
1429        default VMSPLIT_3G
1430        depends on X86_32
1431        ---help---
1432          Select the desired split between kernel and user memory.
1433
1434          If the address range available to the kernel is less than the
1435          physical memory installed, the remaining memory will be available
1436          as "high memory". Accessing high memory is a little more costly
1437          than low memory, as it needs to be mapped into the kernel first.
1438          Note that increasing the kernel address space limits the range
1439          available to user programs, making the address space there
1440          tighter.  Selecting anything other than the default 3G/1G split
1441          will also likely make your kernel incompatible with binary-only
1442          kernel modules.
1443
1444          If you are not absolutely sure what you are doing, leave this
1445          option alone!
1446
1447        config VMSPLIT_3G
1448                bool "3G/1G user/kernel split"
1449        config VMSPLIT_3G_OPT
1450                depends on !X86_PAE
1451                bool "3G/1G user/kernel split (for full 1G low memory)"
1452        config VMSPLIT_2G
1453                bool "2G/2G user/kernel split"
1454        config VMSPLIT_2G_OPT
1455                depends on !X86_PAE
1456                bool "2G/2G user/kernel split (for full 2G low memory)"
1457        config VMSPLIT_1G
1458                bool "1G/3G user/kernel split"
1459endchoice
1460
1461config PAGE_OFFSET
1462        hex
1463        default 0xB0000000 if VMSPLIT_3G_OPT
1464        default 0x80000000 if VMSPLIT_2G
1465        default 0x78000000 if VMSPLIT_2G_OPT
1466        default 0x40000000 if VMSPLIT_1G
1467        default 0xC0000000
1468        depends on X86_32
1469
1470config HIGHMEM
1471        def_bool y
1472        depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1473
1474config X86_PAE
1475        bool "PAE (Physical Address Extension) Support"
1476        depends on X86_32 && !HIGHMEM4G
1477        select PHYS_ADDR_T_64BIT
1478        select SWIOTLB
1479        ---help---
1480          PAE is required for NX support, and furthermore enables
1481          larger swapspace support for non-overcommit purposes. It
1482          has the cost of more pagetable lookup overhead, and also
1483          consumes more pagetable space per process.
1484
1485config X86_5LEVEL
1486        bool "Enable 5-level page tables support"
1487        default y
1488        select DYNAMIC_MEMORY_LAYOUT
1489        select SPARSEMEM_VMEMMAP
1490        depends on X86_64
1491        ---help---
1492          5-level paging enables access to larger address space:
1493          upto 128 PiB of virtual address space and 4 PiB of
1494          physical address space.
1495
1496          It will be supported by future Intel CPUs.
1497
1498          A kernel with the option enabled can be booted on machines that
1499          support 4- or 5-level paging.
1500
1501          See Documentation/x86/x86_64/5level-paging.rst for more
1502          information.
1503
1504          Say N if unsure.
1505
1506config X86_DIRECT_GBPAGES
1507        def_bool y
1508        depends on X86_64
1509        ---help---
1510          Certain kernel features effectively disable kernel
1511          linear 1 GB mappings (even if the CPU otherwise
1512          supports them), so don't confuse the user by printing
1513          that we have them enabled.
1514
1515config X86_CPA_STATISTICS
1516        bool "Enable statistic for Change Page Attribute"
1517        depends on DEBUG_FS
1518        ---help---
1519          Expose statistics about the Change Page Attribute mechanism, which
1520          helps to determine the effectiveness of preserving large and huge
1521          page mappings when mapping protections are changed.
1522
1523config AMD_MEM_ENCRYPT
1524        bool "AMD Secure Memory Encryption (SME) support"
1525        depends on X86_64 && CPU_SUP_AMD
1526        select DYNAMIC_PHYSICAL_MASK
1527        select ARCH_USE_MEMREMAP_PROT
1528        select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1529        ---help---
1530          Say yes to enable support for the encryption of system memory.
1531          This requires an AMD processor that supports Secure Memory
1532          Encryption (SME).
1533
1534config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1535        bool "Activate AMD Secure Memory Encryption (SME) by default"
1536        default y
1537        depends on AMD_MEM_ENCRYPT
1538        ---help---
1539          Say yes to have system memory encrypted by default if running on
1540          an AMD processor that supports Secure Memory Encryption (SME).
1541
1542          If set to Y, then the encryption of system memory can be
1543          deactivated with the mem_encrypt=off command line option.
1544
1545          If set to N, then the encryption of system memory can be
1546          activated with the mem_encrypt=on command line option.
1547
1548# Common NUMA Features
1549config NUMA
1550        bool "NUMA Memory Allocation and Scheduler Support"
1551        depends on SMP
1552        depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1553        default y if X86_BIGSMP
1554        ---help---
1555          Enable NUMA (Non-Uniform Memory Access) support.
1556
1557          The kernel will try to allocate memory used by a CPU on the
1558          local memory controller of the CPU and add some more
1559          NUMA awareness to the kernel.
1560
1561          For 64-bit this is recommended if the system is Intel Core i7
1562          (or later), AMD Opteron, or EM64T NUMA.
1563
1564          For 32-bit this is only needed if you boot a 32-bit
1565          kernel on a 64-bit NUMA platform.
1566
1567          Otherwise, you should say N.
1568
1569config AMD_NUMA
1570        def_bool y
1571        prompt "Old style AMD Opteron NUMA detection"
1572        depends on X86_64 && NUMA && PCI
1573        ---help---
1574          Enable AMD NUMA node topology detection.  You should say Y here if
1575          you have a multi processor AMD system. This uses an old method to
1576          read the NUMA configuration directly from the builtin Northbridge
1577          of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1578          which also takes priority if both are compiled in.
1579
1580config X86_64_ACPI_NUMA
1581        def_bool y
1582        prompt "ACPI NUMA detection"
1583        depends on X86_64 && NUMA && ACPI && PCI
1584        select ACPI_NUMA
1585        ---help---
1586          Enable ACPI SRAT based node topology detection.
1587
1588# Some NUMA nodes have memory ranges that span
1589# other nodes.  Even though a pfn is valid and
1590# between a node's start and end pfns, it may not
1591# reside on that node.  See memmap_init_zone()
1592# for details.
1593config NODES_SPAN_OTHER_NODES
1594        def_bool y
1595        depends on X86_64_ACPI_NUMA
1596
1597config NUMA_EMU
1598        bool "NUMA emulation"
1599        depends on NUMA
1600        ---help---
1601          Enable NUMA emulation. A flat machine will be split
1602          into virtual nodes when booted with "numa=fake=N", where N is the
1603          number of nodes. This is only useful for debugging.
1604
1605config NODES_SHIFT
1606        int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1607        range 1 10
1608        default "10" if MAXSMP
1609        default "6" if X86_64
1610        default "3"
1611        depends on NEED_MULTIPLE_NODES
1612        ---help---
1613          Specify the maximum number of NUMA Nodes available on the target
1614          system.  Increases memory reserved to accommodate various tables.
1615
1616config ARCH_HAVE_MEMORY_PRESENT
1617        def_bool y
1618        depends on X86_32 && DISCONTIGMEM
1619
1620config ARCH_FLATMEM_ENABLE
1621        def_bool y
1622        depends on X86_32 && !NUMA
1623
1624config ARCH_DISCONTIGMEM_ENABLE
1625        def_bool n
1626        depends on NUMA && X86_32
1627        depends on BROKEN
1628
1629config ARCH_SPARSEMEM_ENABLE
1630        def_bool y
1631        depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1632        select SPARSEMEM_STATIC if X86_32
1633        select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1634
1635config ARCH_SPARSEMEM_DEFAULT
1636        def_bool X86_64 || (NUMA && X86_32)
1637
1638config ARCH_SELECT_MEMORY_MODEL
1639        def_bool y
1640        depends on ARCH_SPARSEMEM_ENABLE
1641
1642config ARCH_MEMORY_PROBE
1643        bool "Enable sysfs memory/probe interface"
1644        depends on X86_64 && MEMORY_HOTPLUG
1645        help
1646          This option enables a sysfs memory/probe interface for testing.
1647          See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1648          If you are unsure how to answer this question, answer N.
1649
1650config ARCH_PROC_KCORE_TEXT
1651        def_bool y
1652        depends on X86_64 && PROC_KCORE
1653
1654config ILLEGAL_POINTER_VALUE
1655        hex
1656        default 0 if X86_32
1657        default 0xdead000000000000 if X86_64
1658
1659config X86_PMEM_LEGACY_DEVICE
1660        bool
1661
1662config X86_PMEM_LEGACY
1663        tristate "Support non-standard NVDIMMs and ADR protected memory"
1664        depends on PHYS_ADDR_T_64BIT
1665        depends on BLK_DEV
1666        select X86_PMEM_LEGACY_DEVICE
1667        select LIBNVDIMM
1668        help
1669          Treat memory marked using the non-standard e820 type of 12 as used
1670          by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1671          The kernel will offer these regions to the 'pmem' driver so
1672          they can be used for persistent storage.
1673
1674          Say Y if unsure.
1675
1676config HIGHPTE
1677        bool "Allocate 3rd-level pagetables from highmem"
1678        depends on HIGHMEM
1679        ---help---
1680          The VM uses one page table entry for each page of physical memory.
1681          For systems with a lot of RAM, this can be wasteful of precious
1682          low memory.  Setting this option will put user-space page table
1683          entries in high memory.
1684
1685config X86_CHECK_BIOS_CORRUPTION
1686        bool "Check for low memory corruption"
1687        ---help---
1688          Periodically check for memory corruption in low memory, which
1689          is suspected to be caused by BIOS.  Even when enabled in the
1690          configuration, it is disabled at runtime.  Enable it by
1691          setting "memory_corruption_check=1" on the kernel command
1692          line.  By default it scans the low 64k of memory every 60
1693          seconds; see the memory_corruption_check_size and
1694          memory_corruption_check_period parameters in
1695          Documentation/admin-guide/kernel-parameters.rst to adjust this.
1696
1697          When enabled with the default parameters, this option has
1698          almost no overhead, as it reserves a relatively small amount
1699          of memory and scans it infrequently.  It both detects corruption
1700          and prevents it from affecting the running system.
1701
1702          It is, however, intended as a diagnostic tool; if repeatable
1703          BIOS-originated corruption always affects the same memory,
1704          you can use memmap= to prevent the kernel from using that
1705          memory.
1706
1707config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1708        bool "Set the default setting of memory_corruption_check"
1709        depends on X86_CHECK_BIOS_CORRUPTION
1710        default y
1711        ---help---
1712          Set whether the default state of memory_corruption_check is
1713          on or off.
1714
1715config X86_RESERVE_LOW
1716        int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1717        default 64
1718        range 4 640
1719        ---help---
1720          Specify the amount of low memory to reserve for the BIOS.
1721
1722          The first page contains BIOS data structures that the kernel
1723          must not use, so that page must always be reserved.
1724
1725          By default we reserve the first 64K of physical RAM, as a
1726          number of BIOSes are known to corrupt that memory range
1727          during events such as suspend/resume or monitor cable
1728          insertion, so it must not be used by the kernel.
1729
1730          You can set this to 4 if you are absolutely sure that you
1731          trust the BIOS to get all its memory reservations and usages
1732          right.  If you know your BIOS have problems beyond the
1733          default 64K area, you can set this to 640 to avoid using the
1734          entire low memory range.
1735
1736          If you have doubts about the BIOS (e.g. suspend/resume does
1737          not work or there's kernel crashes after certain hardware
1738          hotplug events) then you might want to enable
1739          X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1740          typical corruption patterns.
1741
1742          Leave this to the default value of 64 if you are unsure.
1743
1744config MATH_EMULATION
1745        bool
1746        depends on MODIFY_LDT_SYSCALL
1747        prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1748        ---help---
1749          Linux can emulate a math coprocessor (used for floating point
1750          operations) if you don't have one. 486DX and Pentium processors have
1751          a math coprocessor built in, 486SX and 386 do not, unless you added
1752          a 487DX or 387, respectively. (The messages during boot time can
1753          give you some hints here ["man dmesg"].) Everyone needs either a
1754          coprocessor or this emulation.
1755
1756          If you don't have a math coprocessor, you need to say Y here; if you
1757          say Y here even though you have a coprocessor, the coprocessor will
1758          be used nevertheless. (This behavior can be changed with the kernel
1759          command line option "no387", which comes handy if your coprocessor
1760          is broken. Try "man bootparam" or see the documentation of your boot
1761          loader (lilo or loadlin) about how to pass options to the kernel at
1762          boot time.) This means that it is a good idea to say Y here if you
1763          intend to use this kernel on different machines.
1764
1765          More information about the internals of the Linux math coprocessor
1766          emulation can be found in <file:arch/x86/math-emu/README>.
1767
1768          If you are not sure, say Y; apart from resulting in a 66 KB bigger
1769          kernel, it won't hurt.
1770
1771config MTRR
1772        def_bool y
1773        prompt "MTRR (Memory Type Range Register) support" if EXPERT
1774        ---help---
1775          On Intel P6 family processors (Pentium Pro, Pentium II and later)
1776          the Memory Type Range Registers (MTRRs) may be used to control
1777          processor access to memory ranges. This is most useful if you have
1778          a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1779          allows bus write transfers to be combined into a larger transfer
1780          before bursting over the PCI/AGP bus. This can increase performance
1781          of image write operations 2.5 times or more. Saying Y here creates a
1782          /proc/mtrr file which may be used to manipulate your processor's
1783          MTRRs. Typically the X server should use this.
1784
1785          This code has a reasonably generic interface so that similar
1786          control registers on other processors can be easily supported
1787          as well:
1788
1789          The Cyrix 6x86, 6x86MX and M II processors have Address Range
1790          Registers (ARRs) which provide a similar functionality to MTRRs. For
1791          these, the ARRs are used to emulate the MTRRs.
1792          The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1793          MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1794          write-combining. All of these processors are supported by this code
1795          and it makes sense to say Y here if you have one of them.
1796
1797          Saying Y here also fixes a problem with buggy SMP BIOSes which only
1798          set the MTRRs for the boot CPU and not for the secondary CPUs. This
1799          can lead to all sorts of problems, so it's good to say Y here.
1800
1801          You can safely say Y even if your machine doesn't have MTRRs, you'll
1802          just add about 9 KB to your kernel.
1803
1804          See <file:Documentation/x86/mtrr.rst> for more information.
1805
1806config MTRR_SANITIZER
1807        def_bool y
1808        prompt "MTRR cleanup support"
1809        depends on MTRR
1810        ---help---
1811          Convert MTRR layout from continuous to discrete, so X drivers can
1812          add writeback entries.
1813
1814          Can be disabled with disable_mtrr_cleanup on the kernel command line.
1815          The largest mtrr entry size for a continuous block can be set with
1816          mtrr_chunk_size.
1817
1818          If unsure, say Y.
1819
1820config MTRR_SANITIZER_ENABLE_DEFAULT
1821        int "MTRR cleanup enable value (0-1)"
1822        range 0 1
1823        default "0"
1824        depends on MTRR_SANITIZER
1825        ---help---
1826          Enable mtrr cleanup default value
1827
1828config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1829        int "MTRR cleanup spare reg num (0-7)"
1830        range 0 7
1831        default "1"
1832        depends on MTRR_SANITIZER
1833        ---help---
1834          mtrr cleanup spare entries default, it can be changed via
1835          mtrr_spare_reg_nr=N on the kernel command line.
1836
1837config X86_PAT
1838        def_bool y
1839        prompt "x86 PAT support" if EXPERT
1840        depends on MTRR
1841        ---help---
1842          Use PAT attributes to setup page level cache control.
1843
1844          PATs are the modern equivalents of MTRRs and are much more
1845          flexible than MTRRs.
1846
1847          Say N here if you see bootup problems (boot crash, boot hang,
1848          spontaneous reboots) or a non-working video driver.
1849
1850          If unsure, say Y.
1851
1852config ARCH_USES_PG_UNCACHED
1853        def_bool y
1854        depends on X86_PAT
1855
1856config ARCH_RANDOM
1857        def_bool y
1858        prompt "x86 architectural random number generator" if EXPERT
1859        ---help---
1860          Enable the x86 architectural RDRAND instruction
1861          (Intel Bull Mountain technology) to generate random numbers.
1862          If supported, this is a high bandwidth, cryptographically
1863          secure hardware random number generator.
1864
1865config X86_SMAP
1866        def_bool y
1867        prompt "Supervisor Mode Access Prevention" if EXPERT
1868        ---help---
1869          Supervisor Mode Access Prevention (SMAP) is a security
1870          feature in newer Intel processors.  There is a small
1871          performance cost if this enabled and turned on; there is
1872          also a small increase in the kernel size if this is enabled.
1873
1874          If unsure, say Y.
1875
1876config X86_UMIP
1877        def_bool y
1878        depends on CPU_SUP_INTEL || CPU_SUP_AMD
1879        prompt "User Mode Instruction Prevention" if EXPERT
1880        ---help---
1881          User Mode Instruction Prevention (UMIP) is a security feature in
1882          some x86 processors. If enabled, a general protection fault is
1883          issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1884          executed in user mode. These instructions unnecessarily expose
1885          information about the hardware state.
1886
1887          The vast majority of applications do not use these instructions.
1888          For the very few that do, software emulation is provided in
1889          specific cases in protected and virtual-8086 modes. Emulated
1890          results are dummy.
1891
1892config X86_INTEL_MEMORY_PROTECTION_KEYS
1893        prompt "Intel Memory Protection Keys"
1894        def_bool y
1895        # Note: only available in 64-bit mode
1896        depends on CPU_SUP_INTEL && X86_64
1897        select ARCH_USES_HIGH_VMA_FLAGS
1898        select ARCH_HAS_PKEYS
1899        ---help---
1900          Memory Protection Keys provides a mechanism for enforcing
1901          page-based protections, but without requiring modification of the
1902          page tables when an application changes protection domains.
1903
1904          For details, see Documentation/core-api/protection-keys.rst
1905
1906          If unsure, say y.
1907
1908choice
1909        prompt "TSX enable mode"
1910        depends on CPU_SUP_INTEL
1911        default X86_INTEL_TSX_MODE_OFF
1912        help
1913          Intel's TSX (Transactional Synchronization Extensions) feature
1914          allows to optimize locking protocols through lock elision which
1915          can lead to a noticeable performance boost.
1916
1917          On the other hand it has been shown that TSX can be exploited
1918          to form side channel attacks (e.g. TAA) and chances are there
1919          will be more of those attacks discovered in the future.
1920
1921          Therefore TSX is not enabled by default (aka tsx=off). An admin
1922          might override this decision by tsx=on the command line parameter.
1923          Even with TSX enabled, the kernel will attempt to enable the best
1924          possible TAA mitigation setting depending on the microcode available
1925          for the particular machine.
1926
1927          This option allows to set the default tsx mode between tsx=on, =off
1928          and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1929          details.
1930
1931          Say off if not sure, auto if TSX is in use but it should be used on safe
1932          platforms or on if TSX is in use and the security aspect of tsx is not
1933          relevant.
1934
1935config X86_INTEL_TSX_MODE_OFF
1936        bool "off"
1937        help
1938          TSX is disabled if possible - equals to tsx=off command line parameter.
1939
1940config X86_INTEL_TSX_MODE_ON
1941        bool "on"
1942        help
1943          TSX is always enabled on TSX capable HW - equals the tsx=on command
1944          line parameter.
1945
1946config X86_INTEL_TSX_MODE_AUTO
1947        bool "auto"
1948        help
1949          TSX is enabled on TSX capable HW that is believed to be safe against
1950          side channel attacks- equals the tsx=auto command line parameter.
1951endchoice
1952
1953config EFI
1954        bool "EFI runtime service support"
1955        depends on ACPI
1956        select UCS2_STRING
1957        select EFI_RUNTIME_WRAPPERS
1958        ---help---
1959          This enables the kernel to use EFI runtime services that are
1960          available (such as the EFI variable services).
1961
1962          This option is only useful on systems that have EFI firmware.
1963          In addition, you should use the latest ELILO loader available
1964          at <http://elilo.sourceforge.net> in order to take advantage
1965          of EFI runtime services. However, even with this option, the
1966          resultant kernel should continue to boot on existing non-EFI
1967          platforms.
1968
1969config EFI_STUB
1970        bool "EFI stub support"
1971        depends on EFI && !X86_USE_3DNOW
1972        depends on $(cc-option,-mabi=ms) || X86_32
1973        select RELOCATABLE
1974        ---help---
1975          This kernel feature allows a bzImage to be loaded directly
1976          by EFI firmware without the use of a bootloader.
1977
1978          See Documentation/admin-guide/efi-stub.rst for more information.
1979
1980config EFI_MIXED
1981        bool "EFI mixed-mode support"
1982        depends on EFI_STUB && X86_64
1983        ---help---
1984           Enabling this feature allows a 64-bit kernel to be booted
1985           on a 32-bit firmware, provided that your CPU supports 64-bit
1986           mode.
1987
1988           Note that it is not possible to boot a mixed-mode enabled
1989           kernel via the EFI boot stub - a bootloader that supports
1990           the EFI handover protocol must be used.
1991
1992           If unsure, say N.
1993
1994config SECCOMP
1995        def_bool y
1996        prompt "Enable seccomp to safely compute untrusted bytecode"
1997        ---help---
1998          This kernel feature is useful for number crunching applications
1999          that may need to compute untrusted bytecode during their
2000          execution. By using pipes or other transports made available to
2001          the process as file descriptors supporting the read/write
2002          syscalls, it's possible to isolate those applications in
2003          their own address space using seccomp. Once seccomp is
2004          enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2005          and the task is only allowed to execute a few safe syscalls
2006          defined by each seccomp mode.
2007
2008          If unsure, say Y. Only embedded should say N here.
2009
2010source "kernel/Kconfig.hz"
2011
2012config KEXEC
2013        bool "kexec system call"
2014        select KEXEC_CORE
2015        ---help---
2016          kexec is a system call that implements the ability to shutdown your
2017          current kernel, and to start another kernel.  It is like a reboot
2018          but it is independent of the system firmware.   And like a reboot
2019          you can start any kernel with it, not just Linux.
2020
2021          The name comes from the similarity to the exec system call.
2022
2023          It is an ongoing process to be certain the hardware in a machine
2024          is properly shutdown, so do not be surprised if this code does not
2025          initially work for you.  As of this writing the exact hardware
2026          interface is strongly in flux, so no good recommendation can be
2027          made.
2028
2029config KEXEC_FILE
2030        bool "kexec file based system call"
2031        select KEXEC_CORE
2032        select BUILD_BIN2C
2033        depends on X86_64
2034        depends on CRYPTO=y
2035        depends on CRYPTO_SHA256=y
2036        ---help---
2037          This is new version of kexec system call. This system call is
2038          file based and takes file descriptors as system call argument
2039          for kernel and initramfs as opposed to list of segments as
2040          accepted by previous system call.
2041
2042config ARCH_HAS_KEXEC_PURGATORY
2043        def_bool KEXEC_FILE
2044
2045config KEXEC_SIG
2046        bool "Verify kernel signature during kexec_file_load() syscall"
2047        depends on KEXEC_FILE
2048        ---help---
2049
2050          This option makes the kexec_file_load() syscall check for a valid
2051          signature of the kernel image.  The image can still be loaded without
2052          a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2053          there's a signature that we can check, then it must be valid.
2054
2055          In addition to this option, you need to enable signature
2056          verification for the corresponding kernel image type being
2057          loaded in order for this to work.
2058
2059config KEXEC_SIG_FORCE
2060        bool "Require a valid signature in kexec_file_load() syscall"
2061        depends on KEXEC_SIG
2062        ---help---
2063          This option makes kernel signature verification mandatory for
2064          the kexec_file_load() syscall.
2065
2066config KEXEC_BZIMAGE_VERIFY_SIG
2067        bool "Enable bzImage signature verification support"
2068        depends on KEXEC_SIG
2069        depends on SIGNED_PE_FILE_VERIFICATION
2070        select SYSTEM_TRUSTED_KEYRING
2071        ---help---
2072          Enable bzImage signature verification support.
2073
2074config CRASH_DUMP
2075        bool "kernel crash dumps"
2076        depends on X86_64 || (X86_32 && HIGHMEM)
2077        ---help---
2078          Generate crash dump after being started by kexec.
2079          This should be normally only set in special crash dump kernels
2080          which are loaded in the main kernel with kexec-tools into
2081          a specially reserved region and then later executed after
2082          a crash by kdump/kexec. The crash dump kernel must be compiled
2083          to a memory address not used by the main kernel or BIOS using
2084          PHYSICAL_START, or it must be built as a relocatable image
2085          (CONFIG_RELOCATABLE=y).
2086          For more details see Documentation/admin-guide/kdump/kdump.rst
2087
2088config KEXEC_JUMP
2089        bool "kexec jump"
2090        depends on KEXEC && HIBERNATION
2091        ---help---
2092          Jump between original kernel and kexeced kernel and invoke
2093          code in physical address mode via KEXEC
2094
2095config PHYSICAL_START
2096        hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2097        default "0x1000000"
2098        ---help---
2099          This gives the physical address where the kernel is loaded.
2100
2101          If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2102          bzImage will decompress itself to above physical address and
2103          run from there. Otherwise, bzImage will run from the address where
2104          it has been loaded by the boot loader and will ignore above physical
2105          address.
2106
2107          In normal kdump cases one does not have to set/change this option
2108          as now bzImage can be compiled as a completely relocatable image
2109          (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2110          address. This option is mainly useful for the folks who don't want
2111          to use a bzImage for capturing the crash dump and want to use a
2112          vmlinux instead. vmlinux is not relocatable hence a kernel needs
2113          to be specifically compiled to run from a specific memory area
2114          (normally a reserved region) and this option comes handy.
2115
2116          So if you are using bzImage for capturing the crash dump,
2117          leave the value here unchanged to 0x1000000 and set
2118          CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2119          for capturing the crash dump change this value to start of
2120          the reserved region.  In other words, it can be set based on
2121          the "X" value as specified in the "crashkernel=YM@XM"
2122          command line boot parameter passed to the panic-ed
2123          kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2124          for more details about crash dumps.
2125
2126          Usage of bzImage for capturing the crash dump is recommended as
2127          one does not have to build two kernels. Same kernel can be used
2128          as production kernel and capture kernel. Above option should have
2129          gone away after relocatable bzImage support is introduced. But it
2130          is present because there are users out there who continue to use
2131          vmlinux for dump capture. This option should go away down the
2132          line.
2133
2134          Don't change this unless you know what you are doing.
2135
2136config RELOCATABLE
2137        bool "Build a relocatable kernel"
2138        default y
2139        ---help---
2140          This builds a kernel image that retains relocation information
2141          so it can be loaded someplace besides the default 1MB.
2142          The relocations tend to make the kernel binary about 10% larger,
2143          but are discarded at runtime.
2144
2145          One use is for the kexec on panic case where the recovery kernel
2146          must live at a different physical address than the primary
2147          kernel.
2148
2149          Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2150          it has been loaded at and the compile time physical address
2151          (CONFIG_PHYSICAL_START) is used as the minimum location.
2152
2153config RANDOMIZE_BASE
2154        bool "Randomize the address of the kernel image (KASLR)"
2155        depends on RELOCATABLE
2156        default y
2157        ---help---
2158          In support of Kernel Address Space Layout Randomization (KASLR),
2159          this randomizes the physical address at which the kernel image
2160          is decompressed and the virtual address where the kernel
2161          image is mapped, as a security feature that deters exploit
2162          attempts relying on knowledge of the location of kernel
2163          code internals.
2164
2165          On 64-bit, the kernel physical and virtual addresses are
2166          randomized separately. The physical address will be anywhere
2167          between 16MB and the top of physical memory (up to 64TB). The
2168          virtual address will be randomized from 16MB up to 1GB (9 bits
2169          of entropy). Note that this also reduces the memory space
2170          available to kernel modules from 1.5GB to 1GB.
2171
2172          On 32-bit, the kernel physical and virtual addresses are
2173          randomized together. They will be randomized from 16MB up to
2174          512MB (8 bits of entropy).
2175
2176          Entropy is generated using the RDRAND instruction if it is
2177          supported. If RDTSC is supported, its value is mixed into
2178          the entropy pool as well. If neither RDRAND nor RDTSC are
2179          supported, then entropy is read from the i8254 timer. The
2180          usable entropy is limited by the kernel being built using
2181          2GB addressing, and that PHYSICAL_ALIGN must be at a
2182          minimum of 2MB. As a result, only 10 bits of entropy are
2183          theoretically possible, but the implementations are further
2184          limited due to memory layouts.
2185
2186          If unsure, say Y.
2187
2188# Relocation on x86 needs some additional build support
2189config X86_NEED_RELOCS
2190        def_bool y
2191        depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2192
2193config PHYSICAL_ALIGN
2194        hex "Alignment value to which kernel should be aligned"
2195        default "0x200000"
2196        range 0x2000 0x1000000 if X86_32
2197        range 0x200000 0x1000000 if X86_64
2198        ---help---
2199          This value puts the alignment restrictions on physical address
2200          where kernel is loaded and run from. Kernel is compiled for an
2201          address which meets above alignment restriction.
2202
2203          If bootloader loads the kernel at a non-aligned address and
2204          CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2205          address aligned to above value and run from there.
2206
2207          If bootloader loads the kernel at a non-aligned address and
2208          CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2209          load address and decompress itself to the address it has been
2210          compiled for and run from there. The address for which kernel is
2211          compiled already meets above alignment restrictions. Hence the
2212          end result is that kernel runs from a physical address meeting
2213          above alignment restrictions.
2214
2215          On 32-bit this value must be a multiple of 0x2000. On 64-bit
2216          this value must be a multiple of 0x200000.
2217
2218          Don't change this unless you know what you are doing.
2219
2220config DYNAMIC_MEMORY_LAYOUT
2221        bool
2222        ---help---
2223          This option makes base addresses of vmalloc and vmemmap as well as
2224          __PAGE_OFFSET movable during boot.
2225
2226config RANDOMIZE_MEMORY
2227        bool "Randomize the kernel memory sections"
2228        depends on X86_64
2229        depends on RANDOMIZE_BASE
2230        select DYNAMIC_MEMORY_LAYOUT
2231        default RANDOMIZE_BASE
2232        ---help---
2233           Randomizes the base virtual address of kernel memory sections
2234           (physical memory mapping, vmalloc & vmemmap). This security feature
2235           makes exploits relying on predictable memory locations less reliable.
2236
2237           The order of allocations remains unchanged. Entropy is generated in
2238           the same way as RANDOMIZE_BASE. Current implementation in the optimal
2239           configuration have in average 30,000 different possible virtual
2240           addresses for each memory section.
2241
2242           If unsure, say Y.
2243
2244config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2245        hex "Physical memory mapping padding" if EXPERT
2246        depends on RANDOMIZE_MEMORY
2247        default "0xa" if MEMORY_HOTPLUG
2248        default "0x0"
2249        range 0x1 0x40 if MEMORY_HOTPLUG
2250        range 0x0 0x40
2251        ---help---
2252           Define the padding in terabytes added to the existing physical
2253           memory size during kernel memory randomization. It is useful
2254           for memory hotplug support but reduces the entropy available for
2255           address randomization.
2256
2257           If unsure, leave at the default value.
2258
2259config HOTPLUG_CPU
2260        def_bool y
2261        depends on SMP
2262
2263config BOOTPARAM_HOTPLUG_CPU0
2264        bool "Set default setting of cpu0_hotpluggable"
2265        depends on HOTPLUG_CPU
2266        ---help---
2267          Set whether default state of cpu0_hotpluggable is on or off.
2268
2269          Say Y here to enable CPU0 hotplug by default. If this switch
2270          is turned on, there is no need to give cpu0_hotplug kernel
2271          parameter and the CPU0 hotplug feature is enabled by default.
2272
2273          Please note: there are two known CPU0 dependencies if you want
2274          to enable the CPU0 hotplug feature either by this switch or by
2275          cpu0_hotplug kernel parameter.
2276
2277          First, resume from hibernate or suspend always starts from CPU0.
2278          So hibernate and suspend are prevented if CPU0 is offline.
2279
2280          Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2281          offline if any interrupt can not migrate out of CPU0. There may
2282          be other CPU0 dependencies.
2283
2284          Please make sure the dependencies are under your control before
2285          you enable this feature.
2286
2287          Say N if you don't want to enable CPU0 hotplug feature by default.
2288          You still can enable the CPU0 hotplug feature at boot by kernel
2289          parameter cpu0_hotplug.
2290
2291config DEBUG_HOTPLUG_CPU0
2292        def_bool n
2293        prompt "Debug CPU0 hotplug"
2294        depends on HOTPLUG_CPU
2295        ---help---
2296          Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2297          soon as possible and boots up userspace with CPU0 offlined. User
2298          can online CPU0 back after boot time.
2299
2300          To debug CPU0 hotplug, you need to enable CPU0 offline/online
2301          feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2302          compilation or giving cpu0_hotplug kernel parameter at boot.
2303
2304          If unsure, say N.
2305
2306config COMPAT_VDSO
2307        def_bool n
2308        prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2309        depends on COMPAT_32
2310        ---help---
2311          Certain buggy versions of glibc will crash if they are
2312          presented with a 32-bit vDSO that is not mapped at the address
2313          indicated in its segment table.
2314
2315          The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2316          and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2317          49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2318          the only released version with the bug, but OpenSUSE 9
2319          contains a buggy "glibc 2.3.2".
2320
2321          The symptom of the bug is that everything crashes on startup, saying:
2322          dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2323
2324          Saying Y here changes the default value of the vdso32 boot
2325          option from 1 to 0, which turns off the 32-bit vDSO entirely.
2326          This works around the glibc bug but hurts performance.
2327
2328          If unsure, say N: if you are compiling your own kernel, you
2329          are unlikely to be using a buggy version of glibc.
2330
2331choice
2332        prompt "vsyscall table for legacy applications"
2333        depends on X86_64
2334        default LEGACY_VSYSCALL_XONLY
2335        help
2336          Legacy user code that does not know how to find the vDSO expects
2337          to be able to issue three syscalls by calling fixed addresses in
2338          kernel space. Since this location is not randomized with ASLR,
2339          it can be used to assist security vulnerability exploitation.
2340
2341          This setting can be changed at boot time via the kernel command
2342          line parameter vsyscall=[emulate|xonly|none].
2343
2344          On a system with recent enough glibc (2.14 or newer) and no
2345          static binaries, you can say None without a performance penalty
2346          to improve security.
2347
2348          If unsure, select "Emulate execution only".
2349
2350        config LEGACY_VSYSCALL_EMULATE
2351                bool "Full emulation"
2352                help
2353                  The kernel traps and emulates calls into the fixed vsyscall
2354                  address mapping. This makes the mapping non-executable, but
2355                  it still contains readable known contents, which could be
2356                  used in certain rare security vulnerability exploits. This
2357                  configuration is recommended when using legacy userspace
2358                  that still uses vsyscalls along with legacy binary
2359                  instrumentation tools that require code to be readable.
2360
2361                  An example of this type of legacy userspace is running
2362                  Pin on an old binary that still uses vsyscalls.
2363
2364        config LEGACY_VSYSCALL_XONLY
2365                bool "Emulate execution only"
2366                help
2367                  The kernel traps and emulates calls into the fixed vsyscall
2368                  address mapping and does not allow reads.  This
2369                  configuration is recommended when userspace might use the
2370                  legacy vsyscall area but support for legacy binary
2371                  instrumentation of legacy code is not needed.  It mitigates
2372                  certain uses of the vsyscall area as an ASLR-bypassing
2373                  buffer.
2374
2375        config LEGACY_VSYSCALL_NONE
2376                bool "None"
2377                help
2378                  There will be no vsyscall mapping at all. This will
2379                  eliminate any risk of ASLR bypass due to the vsyscall
2380                  fixed address mapping. Attempts to use the vsyscalls
2381                  will be reported to dmesg, so that either old or
2382                  malicious userspace programs can be identified.
2383
2384endchoice
2385
2386config CMDLINE_BOOL
2387        bool "Built-in kernel command line"
2388        ---help---
2389          Allow for specifying boot arguments to the kernel at
2390          build time.  On some systems (e.g. embedded ones), it is
2391          necessary or convenient to provide some or all of the
2392          kernel boot arguments with the kernel itself (that is,
2393          to not rely on the boot loader to provide them.)
2394
2395          To compile command line arguments into the kernel,
2396          set this option to 'Y', then fill in the
2397          boot arguments in CONFIG_CMDLINE.
2398
2399          Systems with fully functional boot loaders (i.e. non-embedded)
2400          should leave this option set to 'N'.
2401
2402config CMDLINE
2403        string "Built-in kernel command string"
2404        depends on CMDLINE_BOOL
2405        default ""
2406        ---help---
2407          Enter arguments here that should be compiled into the kernel
2408          image and used at boot time.  If the boot loader provides a
2409          command line at boot time, it is appended to this string to
2410          form the full kernel command line, when the system boots.
2411
2412          However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2413          change this behavior.
2414
2415          In most cases, the command line (whether built-in or provided
2416          by the boot loader) should specify the device for the root
2417          file system.
2418
2419config CMDLINE_OVERRIDE
2420        bool "Built-in command line overrides boot loader arguments"
2421        depends on CMDLINE_BOOL
2422        ---help---
2423          Set this option to 'Y' to have the kernel ignore the boot loader
2424          command line, and use ONLY the built-in command line.
2425
2426          This is used to work around broken boot loaders.  This should
2427          be set to 'N' under normal conditions.
2428
2429config MODIFY_LDT_SYSCALL
2430        bool "Enable the LDT (local descriptor table)" if EXPERT
2431        default y
2432        ---help---
2433          Linux can allow user programs to install a per-process x86
2434          Local Descriptor Table (LDT) using the modify_ldt(2) system
2435          call.  This is required to run 16-bit or segmented code such as
2436          DOSEMU or some Wine programs.  It is also used by some very old
2437          threading libraries.
2438
2439          Enabling this feature adds a small amount of overhead to
2440          context switches and increases the low-level kernel attack
2441          surface.  Disabling it removes the modify_ldt(2) system call.
2442
2443          Saying 'N' here may make sense for embedded or server kernels.
2444
2445source "kernel/livepatch/Kconfig"
2446
2447endmenu
2448
2449config ARCH_HAS_ADD_PAGES
2450        def_bool y
2451        depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2452
2453config ARCH_ENABLE_MEMORY_HOTPLUG
2454        def_bool y
2455        depends on X86_64 || (X86_32 && HIGHMEM)
2456
2457config ARCH_ENABLE_MEMORY_HOTREMOVE
2458        def_bool y
2459        depends on MEMORY_HOTPLUG
2460
2461config USE_PERCPU_NUMA_NODE_ID
2462        def_bool y
2463        depends on NUMA
2464
2465config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2466        def_bool y
2467        depends on X86_64 || X86_PAE
2468
2469config ARCH_ENABLE_HUGEPAGE_MIGRATION
2470        def_bool y
2471        depends on X86_64 && HUGETLB_PAGE && MIGRATION
2472
2473config ARCH_ENABLE_THP_MIGRATION
2474        def_bool y
2475        depends on X86_64 && TRANSPARENT_HUGEPAGE
2476
2477menu "Power management and ACPI options"
2478
2479config ARCH_HIBERNATION_HEADER
2480        def_bool y
2481        depends on HIBERNATION
2482
2483source "kernel/power/Kconfig"
2484
2485source "drivers/acpi/Kconfig"
2486
2487source "drivers/sfi/Kconfig"
2488
2489config X86_APM_BOOT
2490        def_bool y
2491        depends on APM
2492
2493menuconfig APM
2494        tristate "APM (Advanced Power Management) BIOS support"
2495        depends on X86_32 && PM_SLEEP
2496        ---help---
2497          APM is a BIOS specification for saving power using several different
2498          techniques. This is mostly useful for battery powered laptops with
2499          APM compliant BIOSes. If you say Y here, the system time will be
2500          reset after a RESUME operation, the /proc/apm device will provide
2501          battery status information, and user-space programs will receive
2502          notification of APM "events" (e.g. battery status change).
2503
2504          If you select "Y" here, you can disable actual use of the APM
2505          BIOS by passing the "apm=off" option to the kernel at boot time.
2506
2507          Note that the APM support is almost completely disabled for
2508          machines with more than one CPU.
2509
2510          In order to use APM, you will need supporting software. For location
2511          and more information, read <file:Documentation/power/apm-acpi.rst>
2512          and the Battery Powered Linux mini-HOWTO, available from
2513          <http://www.tldp.org/docs.html#howto>.
2514
2515          This driver does not spin down disk drives (see the hdparm(8)
2516          manpage ("man 8 hdparm") for that), and it doesn't turn off
2517          VESA-compliant "green" monitors.
2518
2519          This driver does not support the TI 4000M TravelMate and the ACER
2520          486/DX4/75 because they don't have compliant BIOSes. Many "green"
2521          desktop machines also don't have compliant BIOSes, and this driver
2522          may cause those machines to panic during the boot phase.
2523
2524          Generally, if you don't have a battery in your machine, there isn't
2525          much point in using this driver and you should say N. If you get
2526          random kernel OOPSes or reboots that don't seem to be related to
2527          anything, try disabling/enabling this option (or disabling/enabling
2528          APM in your BIOS).
2529
2530          Some other things you should try when experiencing seemingly random,
2531          "weird" problems:
2532
2533          1) make sure that you have enough swap space and that it is
2534          enabled.
2535          2) pass the "no-hlt" option to the kernel
2536          3) switch on floating point emulation in the kernel and pass
2537          the "no387" option to the kernel
2538          4) pass the "floppy=nodma" option to the kernel
2539          5) pass the "mem=4M" option to the kernel (thereby disabling
2540          all but the first 4 MB of RAM)
2541          6) make sure that the CPU is not over clocked.
2542          7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2543          8) disable the cache from your BIOS settings
2544          9) install a fan for the video card or exchange video RAM
2545          10) install a better fan for the CPU
2546          11) exchange RAM chips
2547          12) exchange the motherboard.
2548
2549          To compile this driver as a module, choose M here: the
2550          module will be called apm.
2551
2552if APM
2553
2554config APM_IGNORE_USER_SUSPEND
2555        bool "Ignore USER SUSPEND"
2556        ---help---
2557          This option will ignore USER SUSPEND requests. On machines with a
2558          compliant APM BIOS, you want to say N. However, on the NEC Versa M
2559          series notebooks, it is necessary to say Y because of a BIOS bug.
2560
2561config APM_DO_ENABLE
2562        bool "Enable PM at boot time"
2563        ---help---
2564          Enable APM features at boot time. From page 36 of the APM BIOS
2565          specification: "When disabled, the APM BIOS does not automatically
2566          power manage devices, enter the Standby State, enter the Suspend
2567          State, or take power saving steps in response to CPU Idle calls."
2568          This driver will make CPU Idle calls when Linux is idle (unless this
2569          feature is turned off -- see "Do CPU IDLE calls", below). This
2570          should always save battery power, but more complicated APM features
2571          will be dependent on your BIOS implementation. You may need to turn
2572          this option off if your computer hangs at boot time when using APM
2573          support, or if it beeps continuously instead of suspending. Turn
2574          this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2575          T400CDT. This is off by default since most machines do fine without
2576          this feature.
2577
2578config APM_CPU_IDLE
2579        depends on CPU_IDLE
2580        bool "Make CPU Idle calls when idle"
2581        ---help---
2582          Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2583          On some machines, this can activate improved power savings, such as
2584          a slowed CPU clock rate, when the machine is idle. These idle calls
2585          are made after the idle loop has run for some length of time (e.g.,
2586          333 mS). On some machines, this will cause a hang at boot time or
2587          whenever the CPU becomes idle. (On machines with more than one CPU,
2588          this option does nothing.)
2589
2590config APM_DISPLAY_BLANK
2591        bool "Enable console blanking using APM"
2592        ---help---
2593          Enable console blanking using the APM. Some laptops can use this to
2594          turn off the LCD backlight when the screen blanker of the Linux
2595          virtual console blanks the screen. Note that this is only used by
2596          the virtual console screen blanker, and won't turn off the backlight
2597          when using the X Window system. This also doesn't have anything to
2598          do with your VESA-compliant power-saving monitor. Further, this
2599          option doesn't work for all laptops -- it might not turn off your
2600          backlight at all, or it might print a lot of errors to the console,
2601          especially if you are using gpm.
2602
2603config APM_ALLOW_INTS
2604        bool "Allow interrupts during APM BIOS calls"
2605        ---help---
2606          Normally we disable external interrupts while we are making calls to
2607          the APM BIOS as a measure to lessen the effects of a badly behaving
2608          BIOS implementation.  The BIOS should reenable interrupts if it
2609          needs to.  Unfortunately, some BIOSes do not -- especially those in
2610          many of the newer IBM Thinkpads.  If you experience hangs when you
2611          suspend, try setting this to Y.  Otherwise, say N.
2612
2613endif # APM
2614
2615source "drivers/cpufreq/Kconfig"
2616
2617source "drivers/cpuidle/Kconfig"
2618
2619source "drivers/idle/Kconfig"
2620
2621endmenu
2622
2623
2624menu "Bus options (PCI etc.)"
2625
2626choice
2627        prompt "PCI access mode"
2628        depends on X86_32 && PCI
2629        default PCI_GOANY
2630        ---help---
2631          On PCI systems, the BIOS can be used to detect the PCI devices and
2632          determine their configuration. However, some old PCI motherboards
2633          have BIOS bugs and may crash if this is done. Also, some embedded
2634          PCI-based systems don't have any BIOS at all. Linux can also try to
2635          detect the PCI hardware directly without using the BIOS.
2636
2637          With this option, you can specify how Linux should detect the
2638          PCI devices. If you choose "BIOS", the BIOS will be used,
2639          if you choose "Direct", the BIOS won't be used, and if you
2640          choose "MMConfig", then PCI Express MMCONFIG will be used.
2641          If you choose "Any", the kernel will try MMCONFIG, then the
2642          direct access method and falls back to the BIOS if that doesn't
2643          work. If unsure, go with the default, which is "Any".
2644
2645config PCI_GOBIOS
2646        bool "BIOS"
2647
2648config PCI_GOMMCONFIG
2649        bool "MMConfig"
2650
2651config PCI_GODIRECT
2652        bool "Direct"
2653
2654config PCI_GOOLPC
2655        bool "OLPC XO-1"
2656        depends on OLPC
2657
2658config PCI_GOANY
2659        bool "Any"
2660
2661endchoice
2662
2663config PCI_BIOS
2664        def_bool y
2665        depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2666
2667# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2668config PCI_DIRECT
2669        def_bool y
2670        depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2671
2672config PCI_MMCONFIG
2673        bool "Support mmconfig PCI config space access" if X86_64
2674        default y
2675        depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2676        depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2677
2678config PCI_OLPC
2679        def_bool y
2680        depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2681
2682config PCI_XEN
2683        def_bool y
2684        depends on PCI && XEN
2685        select SWIOTLB_XEN
2686
2687config MMCONF_FAM10H
2688        def_bool y
2689        depends on X86_64 && PCI_MMCONFIG && ACPI
2690
2691config PCI_CNB20LE_QUIRK
2692        bool "Read CNB20LE Host Bridge Windows" if EXPERT
2693        depends on PCI
2694        help
2695          Read the PCI windows out of the CNB20LE host bridge. This allows
2696          PCI hotplug to work on systems with the CNB20LE chipset which do
2697          not have ACPI.
2698
2699          There's no public spec for this chipset, and this functionality
2700          is known to be incomplete.
2701
2702          You should say N unless you know you need this.
2703
2704config ISA_BUS
2705        bool "ISA bus support on modern systems" if EXPERT
2706        help
2707          Expose ISA bus device drivers and options available for selection and
2708          configuration. Enable this option if your target machine has an ISA
2709          bus. ISA is an older system, displaced by PCI and newer bus
2710          architectures -- if your target machine is modern, it probably does
2711          not have an ISA bus.
2712
2713          If unsure, say N.
2714
2715# x86_64 have no ISA slots, but can have ISA-style DMA.
2716config ISA_DMA_API
2717        bool "ISA-style DMA support" if (X86_64 && EXPERT)
2718        default y
2719        help
2720          Enables ISA-style DMA support for devices requiring such controllers.
2721          If unsure, say Y.
2722
2723if X86_32
2724
2725config ISA
2726        bool "ISA support"
2727        ---help---
2728          Find out whether you have ISA slots on your motherboard.  ISA is the
2729          name of a bus system, i.e. the way the CPU talks to the other stuff
2730          inside your box.  Other bus systems are PCI, EISA, MicroChannel
2731          (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2732          newer boards don't support it.  If you have ISA, say Y, otherwise N.
2733
2734config SCx200
2735        tristate "NatSemi SCx200 support"
2736        ---help---
2737          This provides basic support for National Semiconductor's
2738          (now AMD's) Geode processors.  The driver probes for the
2739          PCI-IDs of several on-chip devices, so its a good dependency
2740          for other scx200_* drivers.
2741
2742          If compiled as a module, the driver is named scx200.
2743
2744config SCx200HR_TIMER
2745        tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2746        depends on SCx200
2747        default y
2748        ---help---
2749          This driver provides a clocksource built upon the on-chip
2750          27MHz high-resolution timer.  Its also a workaround for
2751          NSC Geode SC-1100's buggy TSC, which loses time when the
2752          processor goes idle (as is done by the scheduler).  The
2753          other workaround is idle=poll boot option.
2754
2755config OLPC
2756        bool "One Laptop Per Child support"
2757        depends on !X86_PAE
2758        select GPIOLIB
2759        select OF
2760        select OF_PROMTREE
2761        select IRQ_DOMAIN
2762        select OLPC_EC
2763        ---help---
2764          Add support for detecting the unique features of the OLPC
2765          XO hardware.
2766
2767config OLPC_XO1_PM
2768        bool "OLPC XO-1 Power Management"
2769        depends on OLPC && MFD_CS5535=y && PM_SLEEP
2770        ---help---
2771          Add support for poweroff and suspend of the OLPC XO-1 laptop.
2772
2773config OLPC_XO1_RTC
2774        bool "OLPC XO-1 Real Time Clock"
2775        depends on OLPC_XO1_PM && RTC_DRV_CMOS
2776        ---help---
2777          Add support for the XO-1 real time clock, which can be used as a
2778          programmable wakeup source.
2779
2780config OLPC_XO1_SCI
2781        bool "OLPC XO-1 SCI extras"
2782        depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2783        depends on INPUT=y
2784        select POWER_SUPPLY
2785        ---help---
2786          Add support for SCI-based features of the OLPC XO-1 laptop:
2787           - EC-driven system wakeups
2788           - Power button
2789           - Ebook switch
2790           - Lid switch
2791           - AC adapter status updates
2792           - Battery status updates
2793
2794config OLPC_XO15_SCI
2795        bool "OLPC XO-1.5 SCI extras"
2796        depends on OLPC && ACPI
2797        select POWER_SUPPLY
2798        ---help---
2799          Add support for SCI-based features of the OLPC XO-1.5 laptop:
2800           - EC-driven system wakeups
2801           - AC adapter status updates
2802           - Battery status updates
2803
2804config ALIX
2805        bool "PCEngines ALIX System Support (LED setup)"
2806        select GPIOLIB
2807        ---help---
2808          This option enables system support for the PCEngines ALIX.
2809          At present this just sets up LEDs for GPIO control on
2810          ALIX2/3/6 boards.  However, other system specific setup should
2811          get added here.
2812
2813          Note: You must still enable the drivers for GPIO and LED support
2814          (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2815
2816          Note: You have to set alix.force=1 for boards with Award BIOS.
2817
2818config NET5501
2819        bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2820        select GPIOLIB
2821        ---help---
2822          This option enables system support for the Soekris Engineering net5501.
2823
2824config GEOS
2825        bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2826        select GPIOLIB
2827        depends on DMI
2828        ---help---
2829          This option enables system support for the Traverse Technologies GEOS.
2830
2831config TS5500
2832        bool "Technologic Systems TS-5500 platform support"
2833        depends on MELAN
2834        select CHECK_SIGNATURE
2835        select NEW_LEDS
2836        select LEDS_CLASS
2837        ---help---
2838          This option enables system support for the Technologic Systems TS-5500.
2839
2840endif # X86_32
2841
2842config AMD_NB
2843        def_bool y
2844        depends on CPU_SUP_AMD && PCI
2845
2846config X86_SYSFB
2847        bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2848        help
2849          Firmwares often provide initial graphics framebuffers so the BIOS,
2850          bootloader or kernel can show basic video-output during boot for
2851          user-guidance and debugging. Historically, x86 used the VESA BIOS
2852          Extensions and EFI-framebuffers for this, which are mostly limited
2853          to x86.
2854          This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2855          framebuffers so the new generic system-framebuffer drivers can be
2856          used on x86. If the framebuffer is not compatible with the generic
2857          modes, it is advertised as fallback platform framebuffer so legacy
2858          drivers like efifb, vesafb and uvesafb can pick it up.
2859          If this option is not selected, all system framebuffers are always
2860          marked as fallback platform framebuffers as usual.
2861
2862          Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2863          not be able to pick up generic system framebuffers if this option
2864          is selected. You are highly encouraged to enable simplefb as
2865          replacement if you select this option. simplefb can correctly deal
2866          with generic system framebuffers. But you should still keep vesafb
2867          and others enabled as fallback if a system framebuffer is
2868          incompatible with simplefb.
2869
2870          If unsure, say Y.
2871
2872endmenu
2873
2874
2875menu "Binary Emulations"
2876
2877config IA32_EMULATION
2878        bool "IA32 Emulation"
2879        depends on X86_64
2880        select ARCH_WANT_OLD_COMPAT_IPC
2881        select BINFMT_ELF
2882        select COMPAT_BINFMT_ELF
2883        select COMPAT_OLD_SIGACTION
2884        ---help---
2885          Include code to run legacy 32-bit programs under a
2886          64-bit kernel. You should likely turn this on, unless you're
2887          100% sure that you don't have any 32-bit programs left.
2888
2889config IA32_AOUT
2890        tristate "IA32 a.out support"
2891        depends on IA32_EMULATION
2892        depends on BROKEN
2893        ---help---
2894          Support old a.out binaries in the 32bit emulation.
2895
2896config X86_X32
2897        bool "x32 ABI for 64-bit mode"
2898        depends on X86_64
2899        ---help---
2900          Include code to run binaries for the x32 native 32-bit ABI
2901          for 64-bit processors.  An x32 process gets access to the
2902          full 64-bit register file and wide data path while leaving
2903          pointers at 32 bits for smaller memory footprint.
2904
2905          You will need a recent binutils (2.22 or later) with
2906          elf32_x86_64 support enabled to compile a kernel with this
2907          option set.
2908
2909config COMPAT_32
2910        def_bool y
2911        depends on IA32_EMULATION || X86_32
2912        select HAVE_UID16
2913        select OLD_SIGSUSPEND3
2914
2915config COMPAT
2916        def_bool y
2917        depends on IA32_EMULATION || X86_X32
2918
2919if COMPAT
2920config COMPAT_FOR_U64_ALIGNMENT
2921        def_bool y
2922
2923config SYSVIPC_COMPAT
2924        def_bool y
2925        depends on SYSVIPC
2926endif
2927
2928endmenu
2929
2930
2931config HAVE_ATOMIC_IOMAP
2932        def_bool y
2933        depends on X86_32
2934
2935source "drivers/firmware/Kconfig"
2936
2937source "arch/x86/kvm/Kconfig"
2938