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Linux/arch/x86/Kconfig

  1 # Select 32 or 64 bit
  2 config 64BIT
  3         bool "64-bit kernel" if ARCH = "x86"
  4         default ARCH != "i386"
  5         ---help---
  6           Say yes to build a 64-bit kernel - formerly known as x86_64
  7           Say no to build a 32-bit kernel - formerly known as i386
  8 
  9 config X86_32
 10         def_bool y
 11         depends on !64BIT
 12 
 13 config X86_64
 14         def_bool y
 15         depends on 64BIT
 16 
 17 ### Arch settings
 18 config X86
 19         def_bool y
 20         select ACPI_LEGACY_TABLES_LOOKUP        if ACPI
 21         select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
 22         select ANON_INODES
 23         select ARCH_CLOCKSOURCE_DATA
 24         select ARCH_DISCARD_MEMBLOCK
 25         select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
 26         select ARCH_HAS_DEVMEM_IS_ALLOWED
 27         select ARCH_HAS_ELF_RANDOMIZE
 28         select ARCH_HAS_FAST_MULTIPLIER
 29         select ARCH_HAS_GCOV_PROFILE_ALL
 30         select ARCH_HAS_GIGANTIC_PAGE           if X86_64
 31         select ARCH_HAS_KCOV                    if X86_64
 32         select ARCH_HAS_PMEM_API                if X86_64
 33         select ARCH_HAS_MMIO_FLUSH
 34         select ARCH_HAS_SG_CHAIN
 35         select ARCH_HAS_UBSAN_SANITIZE_ALL
 36         select ARCH_HAVE_NMI_SAFE_CMPXCHG
 37         select ARCH_MIGHT_HAVE_ACPI_PDC         if ACPI
 38         select ARCH_MIGHT_HAVE_PC_PARPORT
 39         select ARCH_MIGHT_HAVE_PC_SERIO
 40         select ARCH_SUPPORTS_ATOMIC_RMW
 41         select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
 42         select ARCH_SUPPORTS_INT128             if X86_64
 43         select ARCH_SUPPORTS_NUMA_BALANCING     if X86_64
 44         select ARCH_USE_BUILTIN_BSWAP
 45         select ARCH_USE_CMPXCHG_LOCKREF         if X86_64
 46         select ARCH_USE_QUEUED_RWLOCKS
 47         select ARCH_USE_QUEUED_SPINLOCKS
 48         select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
 49         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 50         select ARCH_WANT_FRAME_POINTERS
 51         select ARCH_WANT_IPC_PARSE_VERSION      if X86_32
 52         select BUILDTIME_EXTABLE_SORT
 53         select CLKEVT_I8253
 54         select CLKSRC_I8253                     if X86_32
 55         select CLOCKSOURCE_VALIDATE_LAST_CYCLE
 56         select CLOCKSOURCE_WATCHDOG
 57         select CLONE_BACKWARDS                  if X86_32
 58         select COMPAT_OLD_SIGACTION             if IA32_EMULATION
 59         select DCACHE_WORD_ACCESS
 60         select EDAC_ATOMIC_SCRUB
 61         select EDAC_SUPPORT
 62         select GENERIC_CLOCKEVENTS
 63         select GENERIC_CLOCKEVENTS_BROADCAST    if X86_64 || (X86_32 && X86_LOCAL_APIC)
 64         select GENERIC_CLOCKEVENTS_MIN_ADJUST
 65         select GENERIC_CMOS_UPDATE
 66         select GENERIC_CPU_AUTOPROBE
 67         select GENERIC_EARLY_IOREMAP
 68         select GENERIC_FIND_FIRST_BIT
 69         select GENERIC_IOMAP
 70         select GENERIC_IRQ_PROBE
 71         select GENERIC_IRQ_SHOW
 72         select GENERIC_PENDING_IRQ              if SMP
 73         select GENERIC_SMP_IDLE_THREAD
 74         select GENERIC_STRNCPY_FROM_USER
 75         select GENERIC_STRNLEN_USER
 76         select GENERIC_TIME_VSYSCALL
 77         select HAVE_ACPI_APEI                   if ACPI
 78         select HAVE_ACPI_APEI_NMI               if ACPI
 79         select HAVE_ALIGNED_STRUCT_PAGE         if SLUB
 80         select HAVE_AOUT                        if X86_32
 81         select HAVE_ARCH_AUDITSYSCALL
 82         select HAVE_ARCH_HARDENED_USERCOPY
 83         select HAVE_ARCH_HUGE_VMAP              if X86_64 || X86_PAE
 84         select HAVE_ARCH_JUMP_LABEL
 85         select HAVE_ARCH_KASAN                  if X86_64 && SPARSEMEM_VMEMMAP
 86         select HAVE_ARCH_KGDB
 87         select HAVE_ARCH_KMEMCHECK
 88         select HAVE_ARCH_MMAP_RND_BITS          if MMU
 89         select HAVE_ARCH_MMAP_RND_COMPAT_BITS   if MMU && COMPAT
 90         select HAVE_ARCH_SECCOMP_FILTER
 91         select HAVE_ARCH_SOFT_DIRTY             if X86_64
 92         select HAVE_ARCH_TRACEHOOK
 93         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 94         select HAVE_ARCH_WITHIN_STACK_FRAMES
 95         select HAVE_EBPF_JIT                    if X86_64
 96         select HAVE_ARCH_VMAP_STACK             if X86_64
 97         select HAVE_CC_STACKPROTECTOR
 98         select HAVE_CMPXCHG_DOUBLE
 99         select HAVE_CMPXCHG_LOCAL
100         select HAVE_CONTEXT_TRACKING            if X86_64
101         select HAVE_COPY_THREAD_TLS
102         select HAVE_C_RECORDMCOUNT
103         select HAVE_DEBUG_KMEMLEAK
104         select HAVE_DEBUG_STACKOVERFLOW
105         select HAVE_DMA_API_DEBUG
106         select HAVE_DMA_CONTIGUOUS
107         select HAVE_DYNAMIC_FTRACE
108         select HAVE_DYNAMIC_FTRACE_WITH_REGS
109         select HAVE_EFFICIENT_UNALIGNED_ACCESS
110         select HAVE_EXIT_THREAD
111         select HAVE_FENTRY                      if X86_64
112         select HAVE_FTRACE_MCOUNT_RECORD
113         select HAVE_FUNCTION_GRAPH_TRACER
114         select HAVE_FUNCTION_TRACER
115         select HAVE_GCC_PLUGINS
116         select HAVE_GENERIC_DMA_COHERENT        if X86_32
117         select HAVE_HW_BREAKPOINT
118         select HAVE_IDE
119         select HAVE_IOREMAP_PROT
120         select HAVE_IRQ_EXIT_ON_IRQ_STACK       if X86_64
121         select HAVE_IRQ_TIME_ACCOUNTING
122         select HAVE_KERNEL_BZIP2
123         select HAVE_KERNEL_GZIP
124         select HAVE_KERNEL_LZ4
125         select HAVE_KERNEL_LZMA
126         select HAVE_KERNEL_LZO
127         select HAVE_KERNEL_XZ
128         select HAVE_KPROBES
129         select HAVE_KPROBES_ON_FTRACE
130         select HAVE_KRETPROBES
131         select HAVE_KVM
132         select HAVE_LIVEPATCH                   if X86_64
133         select HAVE_MEMBLOCK
134         select HAVE_MEMBLOCK_NODE_MAP
135         select HAVE_MIXED_BREAKPOINTS_REGS
136         select HAVE_NMI
137         select HAVE_OPROFILE
138         select HAVE_OPTPROBES
139         select HAVE_PCSPKR_PLATFORM
140         select HAVE_PERF_EVENTS
141         select HAVE_PERF_EVENTS_NMI
142         select HAVE_PERF_REGS
143         select HAVE_PERF_USER_STACK_DUMP
144         select HAVE_REGS_AND_STACK_ACCESS_API
145         select HAVE_SYSCALL_TRACEPOINTS
146         select HAVE_UID16                       if X86_32 || IA32_EMULATION
147         select HAVE_UNSTABLE_SCHED_CLOCK
148         select HAVE_USER_RETURN_NOTIFIER
149         select IRQ_FORCED_THREADING
150         select MODULES_USE_ELF_RELA             if X86_64
151         select MODULES_USE_ELF_REL              if X86_32
152         select OLD_SIGACTION                    if X86_32
153         select OLD_SIGSUSPEND3                  if X86_32 || IA32_EMULATION
154         select PERF_EVENTS
155         select RTC_LIB
156         select RTC_MC146818_LIB
157         select SPARSE_IRQ
158         select SRCU
159         select SYSCTL_EXCEPTION_TRACE
160         select THREAD_INFO_IN_TASK
161         select USER_STACKTRACE_SUPPORT
162         select VIRT_TO_BUS
163         select X86_DEV_DMA_OPS                  if X86_64
164         select X86_FEATURE_NAMES                if PROC_FS
165         select HAVE_STACK_VALIDATION            if X86_64
166         select ARCH_USES_HIGH_VMA_FLAGS         if X86_INTEL_MEMORY_PROTECTION_KEYS
167         select ARCH_HAS_PKEYS                   if X86_INTEL_MEMORY_PROTECTION_KEYS
168 
169 config INSTRUCTION_DECODER
170         def_bool y
171         depends on KPROBES || PERF_EVENTS || UPROBES
172 
173 config OUTPUT_FORMAT
174         string
175         default "elf32-i386" if X86_32
176         default "elf64-x86-64" if X86_64
177 
178 config ARCH_DEFCONFIG
179         string
180         default "arch/x86/configs/i386_defconfig" if X86_32
181         default "arch/x86/configs/x86_64_defconfig" if X86_64
182 
183 config LOCKDEP_SUPPORT
184         def_bool y
185 
186 config STACKTRACE_SUPPORT
187         def_bool y
188 
189 config MMU
190         def_bool y
191 
192 config ARCH_MMAP_RND_BITS_MIN
193         default 28 if 64BIT
194         default 8
195 
196 config ARCH_MMAP_RND_BITS_MAX
197         default 32 if 64BIT
198         default 16
199 
200 config ARCH_MMAP_RND_COMPAT_BITS_MIN
201         default 8
202 
203 config ARCH_MMAP_RND_COMPAT_BITS_MAX
204         default 16
205 
206 config SBUS
207         bool
208 
209 config NEED_DMA_MAP_STATE
210         def_bool y
211         depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
212 
213 config NEED_SG_DMA_LENGTH
214         def_bool y
215 
216 config GENERIC_ISA_DMA
217         def_bool y
218         depends on ISA_DMA_API
219 
220 config GENERIC_BUG
221         def_bool y
222         depends on BUG
223         select GENERIC_BUG_RELATIVE_POINTERS if X86_64
224 
225 config GENERIC_BUG_RELATIVE_POINTERS
226         bool
227 
228 config GENERIC_HWEIGHT
229         def_bool y
230 
231 config ARCH_MAY_HAVE_PC_FDC
232         def_bool y
233         depends on ISA_DMA_API
234 
235 config RWSEM_XCHGADD_ALGORITHM
236         def_bool y
237 
238 config GENERIC_CALIBRATE_DELAY
239         def_bool y
240 
241 config ARCH_HAS_CPU_RELAX
242         def_bool y
243 
244 config ARCH_HAS_CACHE_LINE_SIZE
245         def_bool y
246 
247 config HAVE_SETUP_PER_CPU_AREA
248         def_bool y
249 
250 config NEED_PER_CPU_EMBED_FIRST_CHUNK
251         def_bool y
252 
253 config NEED_PER_CPU_PAGE_FIRST_CHUNK
254         def_bool y
255 
256 config ARCH_HIBERNATION_POSSIBLE
257         def_bool y
258 
259 config ARCH_SUSPEND_POSSIBLE
260         def_bool y
261 
262 config ARCH_WANT_HUGE_PMD_SHARE
263         def_bool y
264 
265 config ARCH_WANT_GENERAL_HUGETLB
266         def_bool y
267 
268 config ZONE_DMA32
269         def_bool y if X86_64
270 
271 config AUDIT_ARCH
272         def_bool y if X86_64
273 
274 config ARCH_SUPPORTS_OPTIMIZED_INLINING
275         def_bool y
276 
277 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
278         def_bool y
279 
280 config KASAN_SHADOW_OFFSET
281         hex
282         depends on KASAN
283         default 0xdffffc0000000000
284 
285 config HAVE_INTEL_TXT
286         def_bool y
287         depends on INTEL_IOMMU && ACPI
288 
289 config X86_32_SMP
290         def_bool y
291         depends on X86_32 && SMP
292 
293 config X86_64_SMP
294         def_bool y
295         depends on X86_64 && SMP
296 
297 config X86_32_LAZY_GS
298         def_bool y
299         depends on X86_32 && !CC_STACKPROTECTOR
300 
301 config ARCH_SUPPORTS_UPROBES
302         def_bool y
303 
304 config FIX_EARLYCON_MEM
305         def_bool y
306 
307 config DEBUG_RODATA
308         def_bool y
309 
310 config PGTABLE_LEVELS
311         int
312         default 4 if X86_64
313         default 3 if X86_PAE
314         default 2
315 
316 source "init/Kconfig"
317 source "kernel/Kconfig.freezer"
318 
319 menu "Processor type and features"
320 
321 config ZONE_DMA
322         bool "DMA memory allocation support" if EXPERT
323         default y
324         help
325           DMA memory allocation support allows devices with less than 32-bit
326           addressing to allocate within the first 16MB of address space.
327           Disable if no such devices will be used.
328 
329           If unsure, say Y.
330 
331 config SMP
332         bool "Symmetric multi-processing support"
333         ---help---
334           This enables support for systems with more than one CPU. If you have
335           a system with only one CPU, say N. If you have a system with more
336           than one CPU, say Y.
337 
338           If you say N here, the kernel will run on uni- and multiprocessor
339           machines, but will use only one CPU of a multiprocessor machine. If
340           you say Y here, the kernel will run on many, but not all,
341           uniprocessor machines. On a uniprocessor machine, the kernel
342           will run faster if you say N here.
343 
344           Note that if you say Y here and choose architecture "586" or
345           "Pentium" under "Processor family", the kernel will not work on 486
346           architectures. Similarly, multiprocessor kernels for the "PPro"
347           architecture may not work on all Pentium based boards.
348 
349           People using multiprocessor machines who say Y here should also say
350           Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
351           Management" code will be disabled if you say Y here.
352 
353           See also <file:Documentation/x86/i386/IO-APIC.txt>,
354           <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
355           <http://www.tldp.org/docs.html#howto>.
356 
357           If you don't know what to do here, say N.
358 
359 config X86_FEATURE_NAMES
360         bool "Processor feature human-readable names" if EMBEDDED
361         default y
362         ---help---
363           This option compiles in a table of x86 feature bits and corresponding
364           names.  This is required to support /proc/cpuinfo and a few kernel
365           messages.  You can disable this to save space, at the expense of
366           making those few kernel messages show numeric feature bits instead.
367 
368           If in doubt, say Y.
369 
370 config X86_FAST_FEATURE_TESTS
371         bool "Fast CPU feature tests" if EMBEDDED
372         default y
373         ---help---
374           Some fast-paths in the kernel depend on the capabilities of the CPU.
375           Say Y here for the kernel to patch in the appropriate code at runtime
376           based on the capabilities of the CPU. The infrastructure for patching
377           code at runtime takes up some additional space; space-constrained
378           embedded systems may wish to say N here to produce smaller, slightly
379           slower code.
380 
381 config X86_X2APIC
382         bool "Support x2apic"
383         depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
384         ---help---
385           This enables x2apic support on CPUs that have this feature.
386 
387           This allows 32-bit apic IDs (so it can support very large systems),
388           and accesses the local apic via MSRs not via mmio.
389 
390           If you don't know what to do here, say N.
391 
392 config X86_MPPARSE
393         bool "Enable MPS table" if ACPI || SFI
394         default y
395         depends on X86_LOCAL_APIC
396         ---help---
397           For old smp systems that do not have proper acpi support. Newer systems
398           (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
399 
400 config X86_BIGSMP
401         bool "Support for big SMP systems with more than 8 CPUs"
402         depends on X86_32 && SMP
403         ---help---
404           This option is needed for the systems that have more than 8 CPUs
405 
406 config GOLDFISH
407        def_bool y
408        depends on X86_GOLDFISH
409 
410 if X86_32
411 config X86_EXTENDED_PLATFORM
412         bool "Support for extended (non-PC) x86 platforms"
413         default y
414         ---help---
415           If you disable this option then the kernel will only support
416           standard PC platforms. (which covers the vast majority of
417           systems out there.)
418 
419           If you enable this option then you'll be able to select support
420           for the following (non-PC) 32 bit x86 platforms:
421                 Goldfish (Android emulator)
422                 AMD Elan
423                 RDC R-321x SoC
424                 SGI 320/540 (Visual Workstation)
425                 STA2X11-based (e.g. Northville)
426                 Moorestown MID devices
427 
428           If you have one of these systems, or if you want to build a
429           generic distribution kernel, say Y here - otherwise say N.
430 endif
431 
432 if X86_64
433 config X86_EXTENDED_PLATFORM
434         bool "Support for extended (non-PC) x86 platforms"
435         default y
436         ---help---
437           If you disable this option then the kernel will only support
438           standard PC platforms. (which covers the vast majority of
439           systems out there.)
440 
441           If you enable this option then you'll be able to select support
442           for the following (non-PC) 64 bit x86 platforms:
443                 Numascale NumaChip
444                 ScaleMP vSMP
445                 SGI Ultraviolet
446 
447           If you have one of these systems, or if you want to build a
448           generic distribution kernel, say Y here - otherwise say N.
449 endif
450 # This is an alphabetically sorted list of 64 bit extended platforms
451 # Please maintain the alphabetic order if and when there are additions
452 config X86_NUMACHIP
453         bool "Numascale NumaChip"
454         depends on X86_64
455         depends on X86_EXTENDED_PLATFORM
456         depends on NUMA
457         depends on SMP
458         depends on X86_X2APIC
459         depends on PCI_MMCONFIG
460         ---help---
461           Adds support for Numascale NumaChip large-SMP systems. Needed to
462           enable more than ~168 cores.
463           If you don't have one of these, you should say N here.
464 
465 config X86_VSMP
466         bool "ScaleMP vSMP"
467         select HYPERVISOR_GUEST
468         select PARAVIRT
469         depends on X86_64 && PCI
470         depends on X86_EXTENDED_PLATFORM
471         depends on SMP
472         ---help---
473           Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
474           supposed to run on these EM64T-based machines.  Only choose this option
475           if you have one of these machines.
476 
477 config X86_UV
478         bool "SGI Ultraviolet"
479         depends on X86_64
480         depends on X86_EXTENDED_PLATFORM
481         depends on NUMA
482         depends on EFI
483         depends on X86_X2APIC
484         depends on PCI
485         ---help---
486           This option is needed in order to support SGI Ultraviolet systems.
487           If you don't have one of these, you should say N here.
488 
489 # Following is an alphabetically sorted list of 32 bit extended platforms
490 # Please maintain the alphabetic order if and when there are additions
491 
492 config X86_GOLDFISH
493        bool "Goldfish (Virtual Platform)"
494        depends on X86_EXTENDED_PLATFORM
495        ---help---
496          Enable support for the Goldfish virtual platform used primarily
497          for Android development. Unless you are building for the Android
498          Goldfish emulator say N here.
499 
500 config X86_INTEL_CE
501         bool "CE4100 TV platform"
502         depends on PCI
503         depends on PCI_GODIRECT
504         depends on X86_IO_APIC
505         depends on X86_32
506         depends on X86_EXTENDED_PLATFORM
507         select X86_REBOOTFIXUPS
508         select OF
509         select OF_EARLY_FLATTREE
510         ---help---
511           Select for the Intel CE media processor (CE4100) SOC.
512           This option compiles in support for the CE4100 SOC for settop
513           boxes and media devices.
514 
515 config X86_INTEL_MID
516         bool "Intel MID platform support"
517         depends on X86_EXTENDED_PLATFORM
518         depends on X86_PLATFORM_DEVICES
519         depends on PCI
520         depends on X86_64 || (PCI_GOANY && X86_32)
521         depends on X86_IO_APIC
522         select SFI
523         select I2C
524         select DW_APB_TIMER
525         select APB_TIMER
526         select INTEL_SCU_IPC
527         select MFD_INTEL_MSIC
528         ---help---
529           Select to build a kernel capable of supporting Intel MID (Mobile
530           Internet Device) platform systems which do not have the PCI legacy
531           interfaces. If you are building for a PC class system say N here.
532 
533           Intel MID platforms are based on an Intel processor and chipset which
534           consume less power than most of the x86 derivatives.
535 
536 config X86_INTEL_QUARK
537         bool "Intel Quark platform support"
538         depends on X86_32
539         depends on X86_EXTENDED_PLATFORM
540         depends on X86_PLATFORM_DEVICES
541         depends on X86_TSC
542         depends on PCI
543         depends on PCI_GOANY
544         depends on X86_IO_APIC
545         select IOSF_MBI
546         select INTEL_IMR
547         select COMMON_CLK
548         ---help---
549           Select to include support for Quark X1000 SoC.
550           Say Y here if you have a Quark based system such as the Arduino
551           compatible Intel Galileo.
552 
553 config MLX_PLATFORM
554         tristate "Mellanox Technologies platform support"
555         depends on X86_64
556         depends on X86_EXTENDED_PLATFORM
557         ---help---
558           This option enables system support for the Mellanox Technologies
559           platform.
560 
561           Say Y here if you are building a kernel for Mellanox system.
562 
563           Otherwise, say N.
564 
565 config X86_INTEL_LPSS
566         bool "Intel Low Power Subsystem Support"
567         depends on X86 && ACPI
568         select COMMON_CLK
569         select PINCTRL
570         select IOSF_MBI
571         ---help---
572           Select to build support for Intel Low Power Subsystem such as
573           found on Intel Lynxpoint PCH. Selecting this option enables
574           things like clock tree (common clock framework) and pincontrol
575           which are needed by the LPSS peripheral drivers.
576 
577 config X86_AMD_PLATFORM_DEVICE
578         bool "AMD ACPI2Platform devices support"
579         depends on ACPI
580         select COMMON_CLK
581         select PINCTRL
582         ---help---
583           Select to interpret AMD specific ACPI device to platform device
584           such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
585           I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
586           implemented under PINCTRL subsystem.
587 
588 config IOSF_MBI
589         tristate "Intel SoC IOSF Sideband support for SoC platforms"
590         depends on PCI
591         ---help---
592           This option enables sideband register access support for Intel SoC
593           platforms. On these platforms the IOSF sideband is used in lieu of
594           MSR's for some register accesses, mostly but not limited to thermal
595           and power. Drivers may query the availability of this device to
596           determine if they need the sideband in order to work on these
597           platforms. The sideband is available on the following SoC products.
598           This list is not meant to be exclusive.
599            - BayTrail
600            - Braswell
601            - Quark
602 
603           You should say Y if you are running a kernel on one of these SoC's.
604 
605 config IOSF_MBI_DEBUG
606         bool "Enable IOSF sideband access through debugfs"
607         depends on IOSF_MBI && DEBUG_FS
608         ---help---
609           Select this option to expose the IOSF sideband access registers (MCR,
610           MDR, MCRX) through debugfs to write and read register information from
611           different units on the SoC. This is most useful for obtaining device
612           state information for debug and analysis. As this is a general access
613           mechanism, users of this option would have specific knowledge of the
614           device they want to access.
615 
616           If you don't require the option or are in doubt, say N.
617 
618 config X86_RDC321X
619         bool "RDC R-321x SoC"
620         depends on X86_32
621         depends on X86_EXTENDED_PLATFORM
622         select M486
623         select X86_REBOOTFIXUPS
624         ---help---
625           This option is needed for RDC R-321x system-on-chip, also known
626           as R-8610-(G).
627           If you don't have one of these chips, you should say N here.
628 
629 config X86_32_NON_STANDARD
630         bool "Support non-standard 32-bit SMP architectures"
631         depends on X86_32 && SMP
632         depends on X86_EXTENDED_PLATFORM
633         ---help---
634           This option compiles in the bigsmp and STA2X11 default
635           subarchitectures.  It is intended for a generic binary
636           kernel. If you select them all, kernel will probe it one by
637           one and will fallback to default.
638 
639 # Alphabetically sorted list of Non standard 32 bit platforms
640 
641 config X86_SUPPORTS_MEMORY_FAILURE
642         def_bool y
643         # MCE code calls memory_failure():
644         depends on X86_MCE
645         # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
646         # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
647         depends on X86_64 || !SPARSEMEM
648         select ARCH_SUPPORTS_MEMORY_FAILURE
649 
650 config STA2X11
651         bool "STA2X11 Companion Chip Support"
652         depends on X86_32_NON_STANDARD && PCI
653         select X86_DEV_DMA_OPS
654         select X86_DMA_REMAP
655         select SWIOTLB
656         select MFD_STA2X11
657         select GPIOLIB
658         default n
659         ---help---
660           This adds support for boards based on the STA2X11 IO-Hub,
661           a.k.a. "ConneXt". The chip is used in place of the standard
662           PC chipset, so all "standard" peripherals are missing. If this
663           option is selected the kernel will still be able to boot on
664           standard PC machines.
665 
666 config X86_32_IRIS
667         tristate "Eurobraille/Iris poweroff module"
668         depends on X86_32
669         ---help---
670           The Iris machines from EuroBraille do not have APM or ACPI support
671           to shut themselves down properly.  A special I/O sequence is
672           needed to do so, which is what this module does at
673           kernel shutdown.
674 
675           This is only for Iris machines from EuroBraille.
676 
677           If unused, say N.
678 
679 config SCHED_OMIT_FRAME_POINTER
680         def_bool y
681         prompt "Single-depth WCHAN output"
682         depends on X86
683         ---help---
684           Calculate simpler /proc/<PID>/wchan values. If this option
685           is disabled then wchan values will recurse back to the
686           caller function. This provides more accurate wchan values,
687           at the expense of slightly more scheduling overhead.
688 
689           If in doubt, say "Y".
690 
691 menuconfig HYPERVISOR_GUEST
692         bool "Linux guest support"
693         ---help---
694           Say Y here to enable options for running Linux under various hyper-
695           visors. This option enables basic hypervisor detection and platform
696           setup.
697 
698           If you say N, all options in this submenu will be skipped and
699           disabled, and Linux guest support won't be built in.
700 
701 if HYPERVISOR_GUEST
702 
703 config PARAVIRT
704         bool "Enable paravirtualization code"
705         ---help---
706           This changes the kernel so it can modify itself when it is run
707           under a hypervisor, potentially improving performance significantly
708           over full virtualization.  However, when run without a hypervisor
709           the kernel is theoretically slower and slightly larger.
710 
711 config PARAVIRT_DEBUG
712         bool "paravirt-ops debugging"
713         depends on PARAVIRT && DEBUG_KERNEL
714         ---help---
715           Enable to debug paravirt_ops internals.  Specifically, BUG if
716           a paravirt_op is missing when it is called.
717 
718 config PARAVIRT_SPINLOCKS
719         bool "Paravirtualization layer for spinlocks"
720         depends on PARAVIRT && SMP
721         ---help---
722           Paravirtualized spinlocks allow a pvops backend to replace the
723           spinlock implementation with something virtualization-friendly
724           (for example, block the virtual CPU rather than spinning).
725 
726           It has a minimal impact on native kernels and gives a nice performance
727           benefit on paravirtualized KVM / Xen kernels.
728 
729           If you are unsure how to answer this question, answer Y.
730 
731 config QUEUED_LOCK_STAT
732         bool "Paravirt queued spinlock statistics"
733         depends on PARAVIRT_SPINLOCKS && DEBUG_FS
734         ---help---
735           Enable the collection of statistical data on the slowpath
736           behavior of paravirtualized queued spinlocks and report
737           them on debugfs.
738 
739 source "arch/x86/xen/Kconfig"
740 
741 config KVM_GUEST
742         bool "KVM Guest support (including kvmclock)"
743         depends on PARAVIRT
744         select PARAVIRT_CLOCK
745         default y
746         ---help---
747           This option enables various optimizations for running under the KVM
748           hypervisor. It includes a paravirtualized clock, so that instead
749           of relying on a PIT (or probably other) emulation by the
750           underlying device model, the host provides the guest with
751           timing infrastructure such as time of day, and system time
752 
753 config KVM_DEBUG_FS
754         bool "Enable debug information for KVM Guests in debugfs"
755         depends on KVM_GUEST && DEBUG_FS
756         default n
757         ---help---
758           This option enables collection of various statistics for KVM guest.
759           Statistics are displayed in debugfs filesystem. Enabling this option
760           may incur significant overhead.
761 
762 source "arch/x86/lguest/Kconfig"
763 
764 config PARAVIRT_TIME_ACCOUNTING
765         bool "Paravirtual steal time accounting"
766         depends on PARAVIRT
767         default n
768         ---help---
769           Select this option to enable fine granularity task steal time
770           accounting. Time spent executing other tasks in parallel with
771           the current vCPU is discounted from the vCPU power. To account for
772           that, there can be a small performance impact.
773 
774           If in doubt, say N here.
775 
776 config PARAVIRT_CLOCK
777         bool
778 
779 endif #HYPERVISOR_GUEST
780 
781 config NO_BOOTMEM
782         def_bool y
783 
784 source "arch/x86/Kconfig.cpu"
785 
786 config HPET_TIMER
787         def_bool X86_64
788         prompt "HPET Timer Support" if X86_32
789         ---help---
790           Use the IA-PC HPET (High Precision Event Timer) to manage
791           time in preference to the PIT and RTC, if a HPET is
792           present.
793           HPET is the next generation timer replacing legacy 8254s.
794           The HPET provides a stable time base on SMP
795           systems, unlike the TSC, but it is more expensive to access,
796           as it is off-chip.  The interface used is documented
797           in the HPET spec, revision 1.
798 
799           You can safely choose Y here.  However, HPET will only be
800           activated if the platform and the BIOS support this feature.
801           Otherwise the 8254 will be used for timing services.
802 
803           Choose N to continue using the legacy 8254 timer.
804 
805 config HPET_EMULATE_RTC
806         def_bool y
807         depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
808 
809 config APB_TIMER
810        def_bool y if X86_INTEL_MID
811        prompt "Intel MID APB Timer Support" if X86_INTEL_MID
812        select DW_APB_TIMER
813        depends on X86_INTEL_MID && SFI
814        help
815          APB timer is the replacement for 8254, HPET on X86 MID platforms.
816          The APBT provides a stable time base on SMP
817          systems, unlike the TSC, but it is more expensive to access,
818          as it is off-chip. APB timers are always running regardless of CPU
819          C states, they are used as per CPU clockevent device when possible.
820 
821 # Mark as expert because too many people got it wrong.
822 # The code disables itself when not needed.
823 config DMI
824         default y
825         select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
826         bool "Enable DMI scanning" if EXPERT
827         ---help---
828           Enabled scanning of DMI to identify machine quirks. Say Y
829           here unless you have verified that your setup is not
830           affected by entries in the DMI blacklist. Required by PNP
831           BIOS code.
832 
833 config GART_IOMMU
834         bool "Old AMD GART IOMMU support"
835         select SWIOTLB
836         depends on X86_64 && PCI && AMD_NB
837         ---help---
838           Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
839           GART based hardware IOMMUs.
840 
841           The GART supports full DMA access for devices with 32-bit access
842           limitations, on systems with more than 3 GB. This is usually needed
843           for USB, sound, many IDE/SATA chipsets and some other devices.
844 
845           Newer systems typically have a modern AMD IOMMU, supported via
846           the CONFIG_AMD_IOMMU=y config option.
847 
848           In normal configurations this driver is only active when needed:
849           there's more than 3 GB of memory and the system contains a
850           32-bit limited device.
851 
852           If unsure, say Y.
853 
854 config CALGARY_IOMMU
855         bool "IBM Calgary IOMMU support"
856         select SWIOTLB
857         depends on X86_64 && PCI
858         ---help---
859           Support for hardware IOMMUs in IBM's xSeries x366 and x460
860           systems. Needed to run systems with more than 3GB of memory
861           properly with 32-bit PCI devices that do not support DAC
862           (Double Address Cycle). Calgary also supports bus level
863           isolation, where all DMAs pass through the IOMMU.  This
864           prevents them from going anywhere except their intended
865           destination. This catches hard-to-find kernel bugs and
866           mis-behaving drivers and devices that do not use the DMA-API
867           properly to set up their DMA buffers.  The IOMMU can be
868           turned off at boot time with the iommu=off parameter.
869           Normally the kernel will make the right choice by itself.
870           If unsure, say Y.
871 
872 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
873         def_bool y
874         prompt "Should Calgary be enabled by default?"
875         depends on CALGARY_IOMMU
876         ---help---
877           Should Calgary be enabled by default? if you choose 'y', Calgary
878           will be used (if it exists). If you choose 'n', Calgary will not be
879           used even if it exists. If you choose 'n' and would like to use
880           Calgary anyway, pass 'iommu=calgary' on the kernel command line.
881           If unsure, say Y.
882 
883 # need this always selected by IOMMU for the VIA workaround
884 config SWIOTLB
885         def_bool y if X86_64
886         ---help---
887           Support for software bounce buffers used on x86-64 systems
888           which don't have a hardware IOMMU. Using this PCI devices
889           which can only access 32-bits of memory can be used on systems
890           with more than 3 GB of memory.
891           If unsure, say Y.
892 
893 config IOMMU_HELPER
894         def_bool y
895         depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
896 
897 config MAXSMP
898         bool "Enable Maximum number of SMP Processors and NUMA Nodes"
899         depends on X86_64 && SMP && DEBUG_KERNEL
900         select CPUMASK_OFFSTACK
901         ---help---
902           Enable maximum number of CPUS and NUMA Nodes for this architecture.
903           If unsure, say N.
904 
905 config NR_CPUS
906         int "Maximum number of CPUs" if SMP && !MAXSMP
907         range 2 8 if SMP && X86_32 && !X86_BIGSMP
908         range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
909         range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
910         default "1" if !SMP
911         default "8192" if MAXSMP
912         default "32" if SMP && X86_BIGSMP
913         default "8" if SMP && X86_32
914         default "64" if SMP
915         ---help---
916           This allows you to specify the maximum number of CPUs which this
917           kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
918           supported value is 8192, otherwise the maximum value is 512.  The
919           minimum value which makes sense is 2.
920 
921           This is purely to save memory - each supported CPU adds
922           approximately eight kilobytes to the kernel image.
923 
924 config SCHED_SMT
925         bool "SMT (Hyperthreading) scheduler support"
926         depends on SMP
927         ---help---
928           SMT scheduler support improves the CPU scheduler's decision making
929           when dealing with Intel Pentium 4 chips with HyperThreading at a
930           cost of slightly increased overhead in some places. If unsure say
931           N here.
932 
933 config SCHED_MC
934         def_bool y
935         prompt "Multi-core scheduler support"
936         depends on SMP
937         ---help---
938           Multi-core scheduler support improves the CPU scheduler's decision
939           making when dealing with multi-core CPU chips at a cost of slightly
940           increased overhead in some places. If unsure say N here.
941 
942 source "kernel/Kconfig.preempt"
943 
944 config UP_LATE_INIT
945        def_bool y
946        depends on !SMP && X86_LOCAL_APIC
947 
948 config X86_UP_APIC
949         bool "Local APIC support on uniprocessors" if !PCI_MSI
950         default PCI_MSI
951         depends on X86_32 && !SMP && !X86_32_NON_STANDARD
952         ---help---
953           A local APIC (Advanced Programmable Interrupt Controller) is an
954           integrated interrupt controller in the CPU. If you have a single-CPU
955           system which has a processor with a local APIC, you can say Y here to
956           enable and use it. If you say Y here even though your machine doesn't
957           have a local APIC, then the kernel will still run with no slowdown at
958           all. The local APIC supports CPU-generated self-interrupts (timer,
959           performance counters), and the NMI watchdog which detects hard
960           lockups.
961 
962 config X86_UP_IOAPIC
963         bool "IO-APIC support on uniprocessors"
964         depends on X86_UP_APIC
965         ---help---
966           An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
967           SMP-capable replacement for PC-style interrupt controllers. Most
968           SMP systems and many recent uniprocessor systems have one.
969 
970           If you have a single-CPU system with an IO-APIC, you can say Y here
971           to use it. If you say Y here even though your machine doesn't have
972           an IO-APIC, then the kernel will still run with no slowdown at all.
973 
974 config X86_LOCAL_APIC
975         def_bool y
976         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
977         select IRQ_DOMAIN_HIERARCHY
978         select PCI_MSI_IRQ_DOMAIN if PCI_MSI
979 
980 config X86_IO_APIC
981         def_bool y
982         depends on X86_LOCAL_APIC || X86_UP_IOAPIC
983 
984 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
985         bool "Reroute for broken boot IRQs"
986         depends on X86_IO_APIC
987         ---help---
988           This option enables a workaround that fixes a source of
989           spurious interrupts. This is recommended when threaded
990           interrupt handling is used on systems where the generation of
991           superfluous "boot interrupts" cannot be disabled.
992 
993           Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
994           entry in the chipset's IO-APIC is masked (as, e.g. the RT
995           kernel does during interrupt handling). On chipsets where this
996           boot IRQ generation cannot be disabled, this workaround keeps
997           the original IRQ line masked so that only the equivalent "boot
998           IRQ" is delivered to the CPUs. The workaround also tells the
999           kernel to set up the IRQ handler on the boot IRQ line. In this
1000           way only one interrupt is delivered to the kernel. Otherwise
1001           the spurious second interrupt may cause the kernel to bring
1002           down (vital) interrupt lines.
1003 
1004           Only affects "broken" chipsets. Interrupt sharing may be
1005           increased on these systems.
1006 
1007 config X86_MCE
1008         bool "Machine Check / overheating reporting"
1009         select GENERIC_ALLOCATOR
1010         default y
1011         ---help---
1012           Machine Check support allows the processor to notify the
1013           kernel if it detects a problem (e.g. overheating, data corruption).
1014           The action the kernel takes depends on the severity of the problem,
1015           ranging from warning messages to halting the machine.
1016 
1017 config X86_MCE_INTEL
1018         def_bool y
1019         prompt "Intel MCE features"
1020         depends on X86_MCE && X86_LOCAL_APIC
1021         ---help---
1022            Additional support for intel specific MCE features such as
1023            the thermal monitor.
1024 
1025 config X86_MCE_AMD
1026         def_bool y
1027         prompt "AMD MCE features"
1028         depends on X86_MCE && X86_LOCAL_APIC
1029         ---help---
1030            Additional support for AMD specific MCE features such as
1031            the DRAM Error Threshold.
1032 
1033 config X86_ANCIENT_MCE
1034         bool "Support for old Pentium 5 / WinChip machine checks"
1035         depends on X86_32 && X86_MCE
1036         ---help---
1037           Include support for machine check handling on old Pentium 5 or WinChip
1038           systems. These typically need to be enabled explicitly on the command
1039           line.
1040 
1041 config X86_MCE_THRESHOLD
1042         depends on X86_MCE_AMD || X86_MCE_INTEL
1043         def_bool y
1044 
1045 config X86_MCE_INJECT
1046         depends on X86_MCE
1047         tristate "Machine check injector support"
1048         ---help---
1049           Provide support for injecting machine checks for testing purposes.
1050           If you don't know what a machine check is and you don't do kernel
1051           QA it is safe to say n.
1052 
1053 config X86_THERMAL_VECTOR
1054         def_bool y
1055         depends on X86_MCE_INTEL
1056 
1057 source "arch/x86/events/Kconfig"
1058 
1059 config X86_LEGACY_VM86
1060         bool "Legacy VM86 support"
1061         default n
1062         depends on X86_32
1063         ---help---
1064           This option allows user programs to put the CPU into V8086
1065           mode, which is an 80286-era approximation of 16-bit real mode.
1066 
1067           Some very old versions of X and/or vbetool require this option
1068           for user mode setting.  Similarly, DOSEMU will use it if
1069           available to accelerate real mode DOS programs.  However, any
1070           recent version of DOSEMU, X, or vbetool should be fully
1071           functional even without kernel VM86 support, as they will all
1072           fall back to software emulation. Nevertheless, if you are using
1073           a 16-bit DOS program where 16-bit performance matters, vm86
1074           mode might be faster than emulation and you might want to
1075           enable this option.
1076 
1077           Note that any app that works on a 64-bit kernel is unlikely to
1078           need this option, as 64-bit kernels don't, and can't, support
1079           V8086 mode. This option is also unrelated to 16-bit protected
1080           mode and is not needed to run most 16-bit programs under Wine.
1081 
1082           Enabling this option increases the complexity of the kernel
1083           and slows down exception handling a tiny bit.
1084 
1085           If unsure, say N here.
1086 
1087 config VM86
1088        bool
1089        default X86_LEGACY_VM86
1090 
1091 config X86_16BIT
1092         bool "Enable support for 16-bit segments" if EXPERT
1093         default y
1094         depends on MODIFY_LDT_SYSCALL
1095         ---help---
1096           This option is required by programs like Wine to run 16-bit
1097           protected mode legacy code on x86 processors.  Disabling
1098           this option saves about 300 bytes on i386, or around 6K text
1099           plus 16K runtime memory on x86-64,
1100 
1101 config X86_ESPFIX32
1102         def_bool y
1103         depends on X86_16BIT && X86_32
1104 
1105 config X86_ESPFIX64
1106         def_bool y
1107         depends on X86_16BIT && X86_64
1108 
1109 config X86_VSYSCALL_EMULATION
1110        bool "Enable vsyscall emulation" if EXPERT
1111        default y
1112        depends on X86_64
1113        ---help---
1114          This enables emulation of the legacy vsyscall page.  Disabling
1115          it is roughly equivalent to booting with vsyscall=none, except
1116          that it will also disable the helpful warning if a program
1117          tries to use a vsyscall.  With this option set to N, offending
1118          programs will just segfault, citing addresses of the form
1119          0xffffffffff600?00.
1120 
1121          This option is required by many programs built before 2013, and
1122          care should be used even with newer programs if set to N.
1123 
1124          Disabling this option saves about 7K of kernel size and
1125          possibly 4K of additional runtime pagetable memory.
1126 
1127 config TOSHIBA
1128         tristate "Toshiba Laptop support"
1129         depends on X86_32
1130         ---help---
1131           This adds a driver to safely access the System Management Mode of
1132           the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1133           not work on models with a Phoenix BIOS. The System Management Mode
1134           is used to set the BIOS and power saving options on Toshiba portables.
1135 
1136           For information on utilities to make use of this driver see the
1137           Toshiba Linux utilities web site at:
1138           <http://www.buzzard.org.uk/toshiba/>.
1139 
1140           Say Y if you intend to run this kernel on a Toshiba portable.
1141           Say N otherwise.
1142 
1143 config I8K
1144         tristate "Dell i8k legacy laptop support"
1145         select HWMON
1146         select SENSORS_DELL_SMM
1147         ---help---
1148           This option enables legacy /proc/i8k userspace interface in hwmon
1149           dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1150           temperature and allows controlling fan speeds of Dell laptops via
1151           System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1152           it reports also power and hotkey status. For fan speed control is
1153           needed userspace package i8kutils.
1154 
1155           Say Y if you intend to run this kernel on old Dell laptops or want to
1156           use userspace package i8kutils.
1157           Say N otherwise.
1158 
1159 config X86_REBOOTFIXUPS
1160         bool "Enable X86 board specific fixups for reboot"
1161         depends on X86_32
1162         ---help---
1163           This enables chipset and/or board specific fixups to be done
1164           in order to get reboot to work correctly. This is only needed on
1165           some combinations of hardware and BIOS. The symptom, for which
1166           this config is intended, is when reboot ends with a stalled/hung
1167           system.
1168 
1169           Currently, the only fixup is for the Geode machines using
1170           CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1171 
1172           Say Y if you want to enable the fixup. Currently, it's safe to
1173           enable this option even if you don't need it.
1174           Say N otherwise.
1175 
1176 config MICROCODE
1177         bool "CPU microcode loading support"
1178         default y
1179         depends on CPU_SUP_AMD || CPU_SUP_INTEL
1180         select FW_LOADER
1181         ---help---
1182           If you say Y here, you will be able to update the microcode on
1183           Intel and AMD processors. The Intel support is for the IA32 family,
1184           e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1185           AMD support is for families 0x10 and later. You will obviously need
1186           the actual microcode binary data itself which is not shipped with
1187           the Linux kernel.
1188 
1189           The preferred method to load microcode from a detached initrd is described
1190           in Documentation/x86/early-microcode.txt. For that you need to enable
1191           CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1192           initrd for microcode blobs.
1193 
1194           In addition, you can build-in the microcode into the kernel. For that you
1195           need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1196           to the CONFIG_EXTRA_FIRMWARE config option.
1197 
1198 config MICROCODE_INTEL
1199         bool "Intel microcode loading support"
1200         depends on MICROCODE
1201         default MICROCODE
1202         select FW_LOADER
1203         ---help---
1204           This options enables microcode patch loading support for Intel
1205           processors.
1206 
1207           For the current Intel microcode data package go to
1208           <https://downloadcenter.intel.com> and search for
1209           'Linux Processor Microcode Data File'.
1210 
1211 config MICROCODE_AMD
1212         bool "AMD microcode loading support"
1213         depends on MICROCODE
1214         select FW_LOADER
1215         ---help---
1216           If you select this option, microcode patch loading support for AMD
1217           processors will be enabled.
1218 
1219 config MICROCODE_OLD_INTERFACE
1220         def_bool y
1221         depends on MICROCODE
1222 
1223 config X86_MSR
1224         tristate "/dev/cpu/*/msr - Model-specific register support"
1225         ---help---
1226           This device gives privileged processes access to the x86
1227           Model-Specific Registers (MSRs).  It is a character device with
1228           major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1229           MSR accesses are directed to a specific CPU on multi-processor
1230           systems.
1231 
1232 config X86_CPUID
1233         tristate "/dev/cpu/*/cpuid - CPU information support"
1234         ---help---
1235           This device gives processes access to the x86 CPUID instruction to
1236           be executed on a specific processor.  It is a character device
1237           with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1238           /dev/cpu/31/cpuid.
1239 
1240 choice
1241         prompt "High Memory Support"
1242         default HIGHMEM4G
1243         depends on X86_32
1244 
1245 config NOHIGHMEM
1246         bool "off"
1247         ---help---
1248           Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1249           However, the address space of 32-bit x86 processors is only 4
1250           Gigabytes large. That means that, if you have a large amount of
1251           physical memory, not all of it can be "permanently mapped" by the
1252           kernel. The physical memory that's not permanently mapped is called
1253           "high memory".
1254 
1255           If you are compiling a kernel which will never run on a machine with
1256           more than 1 Gigabyte total physical RAM, answer "off" here (default
1257           choice and suitable for most users). This will result in a "3GB/1GB"
1258           split: 3GB are mapped so that each process sees a 3GB virtual memory
1259           space and the remaining part of the 4GB virtual memory space is used
1260           by the kernel to permanently map as much physical memory as
1261           possible.
1262 
1263           If the machine has between 1 and 4 Gigabytes physical RAM, then
1264           answer "4GB" here.
1265 
1266           If more than 4 Gigabytes is used then answer "64GB" here. This
1267           selection turns Intel PAE (Physical Address Extension) mode on.
1268           PAE implements 3-level paging on IA32 processors. PAE is fully
1269           supported by Linux, PAE mode is implemented on all recent Intel
1270           processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1271           then the kernel will not boot on CPUs that don't support PAE!
1272 
1273           The actual amount of total physical memory will either be
1274           auto detected or can be forced by using a kernel command line option
1275           such as "mem=256M". (Try "man bootparam" or see the documentation of
1276           your boot loader (lilo or loadlin) about how to pass options to the
1277           kernel at boot time.)
1278 
1279           If unsure, say "off".
1280 
1281 config HIGHMEM4G
1282         bool "4GB"
1283         ---help---
1284           Select this if you have a 32-bit processor and between 1 and 4
1285           gigabytes of physical RAM.
1286 
1287 config HIGHMEM64G
1288         bool "64GB"
1289         depends on !M486
1290         select X86_PAE
1291         ---help---
1292           Select this if you have a 32-bit processor and more than 4
1293           gigabytes of physical RAM.
1294 
1295 endchoice
1296 
1297 choice
1298         prompt "Memory split" if EXPERT
1299         default VMSPLIT_3G
1300         depends on X86_32
1301         ---help---
1302           Select the desired split between kernel and user memory.
1303 
1304           If the address range available to the kernel is less than the
1305           physical memory installed, the remaining memory will be available
1306           as "high memory". Accessing high memory is a little more costly
1307           than low memory, as it needs to be mapped into the kernel first.
1308           Note that increasing the kernel address space limits the range
1309           available to user programs, making the address space there
1310           tighter.  Selecting anything other than the default 3G/1G split
1311           will also likely make your kernel incompatible with binary-only
1312           kernel modules.
1313 
1314           If you are not absolutely sure what you are doing, leave this
1315           option alone!
1316 
1317         config VMSPLIT_3G
1318                 bool "3G/1G user/kernel split"
1319         config VMSPLIT_3G_OPT
1320                 depends on !X86_PAE
1321                 bool "3G/1G user/kernel split (for full 1G low memory)"
1322         config VMSPLIT_2G
1323                 bool "2G/2G user/kernel split"
1324         config VMSPLIT_2G_OPT
1325                 depends on !X86_PAE
1326                 bool "2G/2G user/kernel split (for full 2G low memory)"
1327         config VMSPLIT_1G
1328                 bool "1G/3G user/kernel split"
1329 endchoice
1330 
1331 config PAGE_OFFSET
1332         hex
1333         default 0xB0000000 if VMSPLIT_3G_OPT
1334         default 0x80000000 if VMSPLIT_2G
1335         default 0x78000000 if VMSPLIT_2G_OPT
1336         default 0x40000000 if VMSPLIT_1G
1337         default 0xC0000000
1338         depends on X86_32
1339 
1340 config HIGHMEM
1341         def_bool y
1342         depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1343 
1344 config X86_PAE
1345         bool "PAE (Physical Address Extension) Support"
1346         depends on X86_32 && !HIGHMEM4G
1347         select SWIOTLB
1348         ---help---
1349           PAE is required for NX support, and furthermore enables
1350           larger swapspace support for non-overcommit purposes. It
1351           has the cost of more pagetable lookup overhead, and also
1352           consumes more pagetable space per process.
1353 
1354 config ARCH_PHYS_ADDR_T_64BIT
1355         def_bool y
1356         depends on X86_64 || X86_PAE
1357 
1358 config ARCH_DMA_ADDR_T_64BIT
1359         def_bool y
1360         depends on X86_64 || HIGHMEM64G
1361 
1362 config X86_DIRECT_GBPAGES
1363         def_bool y
1364         depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1365         ---help---
1366           Certain kernel features effectively disable kernel
1367           linear 1 GB mappings (even if the CPU otherwise
1368           supports them), so don't confuse the user by printing
1369           that we have them enabled.
1370 
1371 # Common NUMA Features
1372 config NUMA
1373         bool "Numa Memory Allocation and Scheduler Support"
1374         depends on SMP
1375         depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1376         default y if X86_BIGSMP
1377         ---help---
1378           Enable NUMA (Non Uniform Memory Access) support.
1379 
1380           The kernel will try to allocate memory used by a CPU on the
1381           local memory controller of the CPU and add some more
1382           NUMA awareness to the kernel.
1383 
1384           For 64-bit this is recommended if the system is Intel Core i7
1385           (or later), AMD Opteron, or EM64T NUMA.
1386 
1387           For 32-bit this is only needed if you boot a 32-bit
1388           kernel on a 64-bit NUMA platform.
1389 
1390           Otherwise, you should say N.
1391 
1392 config AMD_NUMA
1393         def_bool y
1394         prompt "Old style AMD Opteron NUMA detection"
1395         depends on X86_64 && NUMA && PCI
1396         ---help---
1397           Enable AMD NUMA node topology detection.  You should say Y here if
1398           you have a multi processor AMD system. This uses an old method to
1399           read the NUMA configuration directly from the builtin Northbridge
1400           of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1401           which also takes priority if both are compiled in.
1402 
1403 config X86_64_ACPI_NUMA
1404         def_bool y
1405         prompt "ACPI NUMA detection"
1406         depends on X86_64 && NUMA && ACPI && PCI
1407         select ACPI_NUMA
1408         ---help---
1409           Enable ACPI SRAT based node topology detection.
1410 
1411 # Some NUMA nodes have memory ranges that span
1412 # other nodes.  Even though a pfn is valid and
1413 # between a node's start and end pfns, it may not
1414 # reside on that node.  See memmap_init_zone()
1415 # for details.
1416 config NODES_SPAN_OTHER_NODES
1417         def_bool y
1418         depends on X86_64_ACPI_NUMA
1419 
1420 config NUMA_EMU
1421         bool "NUMA emulation"
1422         depends on NUMA
1423         ---help---
1424           Enable NUMA emulation. A flat machine will be split
1425           into virtual nodes when booted with "numa=fake=N", where N is the
1426           number of nodes. This is only useful for debugging.
1427 
1428 config NODES_SHIFT
1429         int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1430         range 1 10
1431         default "10" if MAXSMP
1432         default "6" if X86_64
1433         default "3"
1434         depends on NEED_MULTIPLE_NODES
1435         ---help---
1436           Specify the maximum number of NUMA Nodes available on the target
1437           system.  Increases memory reserved to accommodate various tables.
1438 
1439 config ARCH_HAVE_MEMORY_PRESENT
1440         def_bool y
1441         depends on X86_32 && DISCONTIGMEM
1442 
1443 config NEED_NODE_MEMMAP_SIZE
1444         def_bool y
1445         depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1446 
1447 config ARCH_FLATMEM_ENABLE
1448         def_bool y
1449         depends on X86_32 && !NUMA
1450 
1451 config ARCH_DISCONTIGMEM_ENABLE
1452         def_bool y
1453         depends on NUMA && X86_32
1454 
1455 config ARCH_DISCONTIGMEM_DEFAULT
1456         def_bool y
1457         depends on NUMA && X86_32
1458 
1459 config ARCH_SPARSEMEM_ENABLE
1460         def_bool y
1461         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1462         select SPARSEMEM_STATIC if X86_32
1463         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1464 
1465 config ARCH_SPARSEMEM_DEFAULT
1466         def_bool y
1467         depends on X86_64
1468 
1469 config ARCH_SELECT_MEMORY_MODEL
1470         def_bool y
1471         depends on ARCH_SPARSEMEM_ENABLE
1472 
1473 config ARCH_MEMORY_PROBE
1474         bool "Enable sysfs memory/probe interface"
1475         depends on X86_64 && MEMORY_HOTPLUG
1476         help
1477           This option enables a sysfs memory/probe interface for testing.
1478           See Documentation/memory-hotplug.txt for more information.
1479           If you are unsure how to answer this question, answer N.
1480 
1481 config ARCH_PROC_KCORE_TEXT
1482         def_bool y
1483         depends on X86_64 && PROC_KCORE
1484 
1485 config ILLEGAL_POINTER_VALUE
1486        hex
1487        default 0 if X86_32
1488        default 0xdead000000000000 if X86_64
1489 
1490 source "mm/Kconfig"
1491 
1492 config X86_PMEM_LEGACY_DEVICE
1493         bool
1494 
1495 config X86_PMEM_LEGACY
1496         tristate "Support non-standard NVDIMMs and ADR protected memory"
1497         depends on PHYS_ADDR_T_64BIT
1498         depends on BLK_DEV
1499         select X86_PMEM_LEGACY_DEVICE
1500         select LIBNVDIMM
1501         help
1502           Treat memory marked using the non-standard e820 type of 12 as used
1503           by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1504           The kernel will offer these regions to the 'pmem' driver so
1505           they can be used for persistent storage.
1506 
1507           Say Y if unsure.
1508 
1509 config HIGHPTE
1510         bool "Allocate 3rd-level pagetables from highmem"
1511         depends on HIGHMEM
1512         ---help---
1513           The VM uses one page table entry for each page of physical memory.
1514           For systems with a lot of RAM, this can be wasteful of precious
1515           low memory.  Setting this option will put user-space page table
1516           entries in high memory.
1517 
1518 config X86_CHECK_BIOS_CORRUPTION
1519         bool "Check for low memory corruption"
1520         ---help---
1521           Periodically check for memory corruption in low memory, which
1522           is suspected to be caused by BIOS.  Even when enabled in the
1523           configuration, it is disabled at runtime.  Enable it by
1524           setting "memory_corruption_check=1" on the kernel command
1525           line.  By default it scans the low 64k of memory every 60
1526           seconds; see the memory_corruption_check_size and
1527           memory_corruption_check_period parameters in
1528           Documentation/kernel-parameters.txt to adjust this.
1529 
1530           When enabled with the default parameters, this option has
1531           almost no overhead, as it reserves a relatively small amount
1532           of memory and scans it infrequently.  It both detects corruption
1533           and prevents it from affecting the running system.
1534 
1535           It is, however, intended as a diagnostic tool; if repeatable
1536           BIOS-originated corruption always affects the same memory,
1537           you can use memmap= to prevent the kernel from using that
1538           memory.
1539 
1540 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1541         bool "Set the default setting of memory_corruption_check"
1542         depends on X86_CHECK_BIOS_CORRUPTION
1543         default y
1544         ---help---
1545           Set whether the default state of memory_corruption_check is
1546           on or off.
1547 
1548 config X86_RESERVE_LOW
1549         int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1550         default 64
1551         range 4 640
1552         ---help---
1553           Specify the amount of low memory to reserve for the BIOS.
1554 
1555           The first page contains BIOS data structures that the kernel
1556           must not use, so that page must always be reserved.
1557 
1558           By default we reserve the first 64K of physical RAM, as a
1559           number of BIOSes are known to corrupt that memory range
1560           during events such as suspend/resume or monitor cable
1561           insertion, so it must not be used by the kernel.
1562 
1563           You can set this to 4 if you are absolutely sure that you
1564           trust the BIOS to get all its memory reservations and usages
1565           right.  If you know your BIOS have problems beyond the
1566           default 64K area, you can set this to 640 to avoid using the
1567           entire low memory range.
1568 
1569           If you have doubts about the BIOS (e.g. suspend/resume does
1570           not work or there's kernel crashes after certain hardware
1571           hotplug events) then you might want to enable
1572           X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1573           typical corruption patterns.
1574 
1575           Leave this to the default value of 64 if you are unsure.
1576 
1577 config MATH_EMULATION
1578         bool
1579         depends on MODIFY_LDT_SYSCALL
1580         prompt "Math emulation" if X86_32
1581         ---help---
1582           Linux can emulate a math coprocessor (used for floating point
1583           operations) if you don't have one. 486DX and Pentium processors have
1584           a math coprocessor built in, 486SX and 386 do not, unless you added
1585           a 487DX or 387, respectively. (The messages during boot time can
1586           give you some hints here ["man dmesg"].) Everyone needs either a
1587           coprocessor or this emulation.
1588 
1589           If you don't have a math coprocessor, you need to say Y here; if you
1590           say Y here even though you have a coprocessor, the coprocessor will
1591           be used nevertheless. (This behavior can be changed with the kernel
1592           command line option "no387", which comes handy if your coprocessor
1593           is broken. Try "man bootparam" or see the documentation of your boot
1594           loader (lilo or loadlin) about how to pass options to the kernel at
1595           boot time.) This means that it is a good idea to say Y here if you
1596           intend to use this kernel on different machines.
1597 
1598           More information about the internals of the Linux math coprocessor
1599           emulation can be found in <file:arch/x86/math-emu/README>.
1600 
1601           If you are not sure, say Y; apart from resulting in a 66 KB bigger
1602           kernel, it won't hurt.
1603 
1604 config MTRR
1605         def_bool y
1606         prompt "MTRR (Memory Type Range Register) support" if EXPERT
1607         ---help---
1608           On Intel P6 family processors (Pentium Pro, Pentium II and later)
1609           the Memory Type Range Registers (MTRRs) may be used to control
1610           processor access to memory ranges. This is most useful if you have
1611           a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1612           allows bus write transfers to be combined into a larger transfer
1613           before bursting over the PCI/AGP bus. This can increase performance
1614           of image write operations 2.5 times or more. Saying Y here creates a
1615           /proc/mtrr file which may be used to manipulate your processor's
1616           MTRRs. Typically the X server should use this.
1617 
1618           This code has a reasonably generic interface so that similar
1619           control registers on other processors can be easily supported
1620           as well:
1621 
1622           The Cyrix 6x86, 6x86MX and M II processors have Address Range
1623           Registers (ARRs) which provide a similar functionality to MTRRs. For
1624           these, the ARRs are used to emulate the MTRRs.
1625           The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1626           MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1627           write-combining. All of these processors are supported by this code
1628           and it makes sense to say Y here if you have one of them.
1629 
1630           Saying Y here also fixes a problem with buggy SMP BIOSes which only
1631           set the MTRRs for the boot CPU and not for the secondary CPUs. This
1632           can lead to all sorts of problems, so it's good to say Y here.
1633 
1634           You can safely say Y even if your machine doesn't have MTRRs, you'll
1635           just add about 9 KB to your kernel.
1636 
1637           See <file:Documentation/x86/mtrr.txt> for more information.
1638 
1639 config MTRR_SANITIZER
1640         def_bool y
1641         prompt "MTRR cleanup support"
1642         depends on MTRR
1643         ---help---
1644           Convert MTRR layout from continuous to discrete, so X drivers can
1645           add writeback entries.
1646 
1647           Can be disabled with disable_mtrr_cleanup on the kernel command line.
1648           The largest mtrr entry size for a continuous block can be set with
1649           mtrr_chunk_size.
1650 
1651           If unsure, say Y.
1652 
1653 config MTRR_SANITIZER_ENABLE_DEFAULT
1654         int "MTRR cleanup enable value (0-1)"
1655         range 0 1
1656         default "0"
1657         depends on MTRR_SANITIZER
1658         ---help---
1659           Enable mtrr cleanup default value
1660 
1661 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1662         int "MTRR cleanup spare reg num (0-7)"
1663         range 0 7
1664         default "1"
1665         depends on MTRR_SANITIZER
1666         ---help---
1667           mtrr cleanup spare entries default, it can be changed via
1668           mtrr_spare_reg_nr=N on the kernel command line.
1669 
1670 config X86_PAT
1671         def_bool y
1672         prompt "x86 PAT support" if EXPERT
1673         depends on MTRR
1674         ---help---
1675           Use PAT attributes to setup page level cache control.
1676 
1677           PATs are the modern equivalents of MTRRs and are much more
1678           flexible than MTRRs.
1679 
1680           Say N here if you see bootup problems (boot crash, boot hang,
1681           spontaneous reboots) or a non-working video driver.
1682 
1683           If unsure, say Y.
1684 
1685 config ARCH_USES_PG_UNCACHED
1686         def_bool y
1687         depends on X86_PAT
1688 
1689 config ARCH_RANDOM
1690         def_bool y
1691         prompt "x86 architectural random number generator" if EXPERT
1692         ---help---
1693           Enable the x86 architectural RDRAND instruction
1694           (Intel Bull Mountain technology) to generate random numbers.
1695           If supported, this is a high bandwidth, cryptographically
1696           secure hardware random number generator.
1697 
1698 config X86_SMAP
1699         def_bool y
1700         prompt "Supervisor Mode Access Prevention" if EXPERT
1701         ---help---
1702           Supervisor Mode Access Prevention (SMAP) is a security
1703           feature in newer Intel processors.  There is a small
1704           performance cost if this enabled and turned on; there is
1705           also a small increase in the kernel size if this is enabled.
1706 
1707           If unsure, say Y.
1708 
1709 config X86_INTEL_MPX
1710         prompt "Intel MPX (Memory Protection Extensions)"
1711         def_bool n
1712         depends on CPU_SUP_INTEL
1713         ---help---
1714           MPX provides hardware features that can be used in
1715           conjunction with compiler-instrumented code to check
1716           memory references.  It is designed to detect buffer
1717           overflow or underflow bugs.
1718 
1719           This option enables running applications which are
1720           instrumented or otherwise use MPX.  It does not use MPX
1721           itself inside the kernel or to protect the kernel
1722           against bad memory references.
1723 
1724           Enabling this option will make the kernel larger:
1725           ~8k of kernel text and 36 bytes of data on a 64-bit
1726           defconfig.  It adds a long to the 'mm_struct' which
1727           will increase the kernel memory overhead of each
1728           process and adds some branches to paths used during
1729           exec() and munmap().
1730 
1731           For details, see Documentation/x86/intel_mpx.txt
1732 
1733           If unsure, say N.
1734 
1735 config X86_INTEL_MEMORY_PROTECTION_KEYS
1736         prompt "Intel Memory Protection Keys"
1737         def_bool y
1738         # Note: only available in 64-bit mode
1739         depends on CPU_SUP_INTEL && X86_64
1740         ---help---
1741           Memory Protection Keys provides a mechanism for enforcing
1742           page-based protections, but without requiring modification of the
1743           page tables when an application changes protection domains.
1744 
1745           For details, see Documentation/x86/protection-keys.txt
1746 
1747           If unsure, say y.
1748 
1749 config EFI
1750         bool "EFI runtime service support"
1751         depends on ACPI
1752         select UCS2_STRING
1753         select EFI_RUNTIME_WRAPPERS
1754         ---help---
1755           This enables the kernel to use EFI runtime services that are
1756           available (such as the EFI variable services).
1757 
1758           This option is only useful on systems that have EFI firmware.
1759           In addition, you should use the latest ELILO loader available
1760           at <http://elilo.sourceforge.net> in order to take advantage
1761           of EFI runtime services. However, even with this option, the
1762           resultant kernel should continue to boot on existing non-EFI
1763           platforms.
1764 
1765 config EFI_STUB
1766        bool "EFI stub support"
1767        depends on EFI && !X86_USE_3DNOW
1768        select RELOCATABLE
1769        ---help---
1770           This kernel feature allows a bzImage to be loaded directly
1771           by EFI firmware without the use of a bootloader.
1772 
1773           See Documentation/efi-stub.txt for more information.
1774 
1775 config EFI_MIXED
1776         bool "EFI mixed-mode support"
1777         depends on EFI_STUB && X86_64
1778         ---help---
1779            Enabling this feature allows a 64-bit kernel to be booted
1780            on a 32-bit firmware, provided that your CPU supports 64-bit
1781            mode.
1782 
1783            Note that it is not possible to boot a mixed-mode enabled
1784            kernel via the EFI boot stub - a bootloader that supports
1785            the EFI handover protocol must be used.
1786 
1787            If unsure, say N.
1788 
1789 config SECCOMP
1790         def_bool y
1791         prompt "Enable seccomp to safely compute untrusted bytecode"
1792         ---help---
1793           This kernel feature is useful for number crunching applications
1794           that may need to compute untrusted bytecode during their
1795           execution. By using pipes or other transports made available to
1796           the process as file descriptors supporting the read/write
1797           syscalls, it's possible to isolate those applications in
1798           their own address space using seccomp. Once seccomp is
1799           enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1800           and the task is only allowed to execute a few safe syscalls
1801           defined by each seccomp mode.
1802 
1803           If unsure, say Y. Only embedded should say N here.
1804 
1805 source kernel/Kconfig.hz
1806 
1807 config KEXEC
1808         bool "kexec system call"
1809         select KEXEC_CORE
1810         ---help---
1811           kexec is a system call that implements the ability to shutdown your
1812           current kernel, and to start another kernel.  It is like a reboot
1813           but it is independent of the system firmware.   And like a reboot
1814           you can start any kernel with it, not just Linux.
1815 
1816           The name comes from the similarity to the exec system call.
1817 
1818           It is an ongoing process to be certain the hardware in a machine
1819           is properly shutdown, so do not be surprised if this code does not
1820           initially work for you.  As of this writing the exact hardware
1821           interface is strongly in flux, so no good recommendation can be
1822           made.
1823 
1824 config KEXEC_FILE
1825         bool "kexec file based system call"
1826         select KEXEC_CORE
1827         select BUILD_BIN2C
1828         depends on X86_64
1829         depends on CRYPTO=y
1830         depends on CRYPTO_SHA256=y
1831         ---help---
1832           This is new version of kexec system call. This system call is
1833           file based and takes file descriptors as system call argument
1834           for kernel and initramfs as opposed to list of segments as
1835           accepted by previous system call.
1836 
1837 config KEXEC_VERIFY_SIG
1838         bool "Verify kernel signature during kexec_file_load() syscall"
1839         depends on KEXEC_FILE
1840         ---help---
1841           This option makes kernel signature verification mandatory for
1842           the kexec_file_load() syscall.
1843 
1844           In addition to that option, you need to enable signature
1845           verification for the corresponding kernel image type being
1846           loaded in order for this to work.
1847 
1848 config KEXEC_BZIMAGE_VERIFY_SIG
1849         bool "Enable bzImage signature verification support"
1850         depends on KEXEC_VERIFY_SIG
1851         depends on SIGNED_PE_FILE_VERIFICATION
1852         select SYSTEM_TRUSTED_KEYRING
1853         ---help---
1854           Enable bzImage signature verification support.
1855 
1856 config CRASH_DUMP
1857         bool "kernel crash dumps"
1858         depends on X86_64 || (X86_32 && HIGHMEM)
1859         ---help---
1860           Generate crash dump after being started by kexec.
1861           This should be normally only set in special crash dump kernels
1862           which are loaded in the main kernel with kexec-tools into
1863           a specially reserved region and then later executed after
1864           a crash by kdump/kexec. The crash dump kernel must be compiled
1865           to a memory address not used by the main kernel or BIOS using
1866           PHYSICAL_START, or it must be built as a relocatable image
1867           (CONFIG_RELOCATABLE=y).
1868           For more details see Documentation/kdump/kdump.txt
1869 
1870 config KEXEC_JUMP
1871         bool "kexec jump"
1872         depends on KEXEC && HIBERNATION
1873         ---help---
1874           Jump between original kernel and kexeced kernel and invoke
1875           code in physical address mode via KEXEC
1876 
1877 config PHYSICAL_START
1878         hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1879         default "0x1000000"
1880         ---help---
1881           This gives the physical address where the kernel is loaded.
1882 
1883           If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1884           bzImage will decompress itself to above physical address and
1885           run from there. Otherwise, bzImage will run from the address where
1886           it has been loaded by the boot loader and will ignore above physical
1887           address.
1888 
1889           In normal kdump cases one does not have to set/change this option
1890           as now bzImage can be compiled as a completely relocatable image
1891           (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1892           address. This option is mainly useful for the folks who don't want
1893           to use a bzImage for capturing the crash dump and want to use a
1894           vmlinux instead. vmlinux is not relocatable hence a kernel needs
1895           to be specifically compiled to run from a specific memory area
1896           (normally a reserved region) and this option comes handy.
1897 
1898           So if you are using bzImage for capturing the crash dump,
1899           leave the value here unchanged to 0x1000000 and set
1900           CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
1901           for capturing the crash dump change this value to start of
1902           the reserved region.  In other words, it can be set based on
1903           the "X" value as specified in the "crashkernel=YM@XM"
1904           command line boot parameter passed to the panic-ed
1905           kernel. Please take a look at Documentation/kdump/kdump.txt
1906           for more details about crash dumps.
1907 
1908           Usage of bzImage for capturing the crash dump is recommended as
1909           one does not have to build two kernels. Same kernel can be used
1910           as production kernel and capture kernel. Above option should have
1911           gone away after relocatable bzImage support is introduced. But it
1912           is present because there are users out there who continue to use
1913           vmlinux for dump capture. This option should go away down the
1914           line.
1915 
1916           Don't change this unless you know what you are doing.
1917 
1918 config RELOCATABLE
1919         bool "Build a relocatable kernel"
1920         default y
1921         ---help---
1922           This builds a kernel image that retains relocation information
1923           so it can be loaded someplace besides the default 1MB.
1924           The relocations tend to make the kernel binary about 10% larger,
1925           but are discarded at runtime.
1926 
1927           One use is for the kexec on panic case where the recovery kernel
1928           must live at a different physical address than the primary
1929           kernel.
1930 
1931           Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1932           it has been loaded at and the compile time physical address
1933           (CONFIG_PHYSICAL_START) is used as the minimum location.
1934 
1935 config RANDOMIZE_BASE
1936         bool "Randomize the address of the kernel image (KASLR)"
1937         depends on RELOCATABLE
1938         default n
1939         ---help---
1940           In support of Kernel Address Space Layout Randomization (KASLR),
1941           this randomizes the physical address at which the kernel image
1942           is decompressed and the virtual address where the kernel
1943           image is mapped, as a security feature that deters exploit
1944           attempts relying on knowledge of the location of kernel
1945           code internals.
1946 
1947           On 64-bit, the kernel physical and virtual addresses are
1948           randomized separately. The physical address will be anywhere
1949           between 16MB and the top of physical memory (up to 64TB). The
1950           virtual address will be randomized from 16MB up to 1GB (9 bits
1951           of entropy). Note that this also reduces the memory space
1952           available to kernel modules from 1.5GB to 1GB.
1953 
1954           On 32-bit, the kernel physical and virtual addresses are
1955           randomized together. They will be randomized from 16MB up to
1956           512MB (8 bits of entropy).
1957 
1958           Entropy is generated using the RDRAND instruction if it is
1959           supported. If RDTSC is supported, its value is mixed into
1960           the entropy pool as well. If neither RDRAND nor RDTSC are
1961           supported, then entropy is read from the i8254 timer. The
1962           usable entropy is limited by the kernel being built using
1963           2GB addressing, and that PHYSICAL_ALIGN must be at a
1964           minimum of 2MB. As a result, only 10 bits of entropy are
1965           theoretically possible, but the implementations are further
1966           limited due to memory layouts.
1967 
1968           If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1969           time. To enable it, boot with "kaslr" on the kernel command
1970           line (which will also disable hibernation).
1971 
1972           If unsure, say N.
1973 
1974 # Relocation on x86 needs some additional build support
1975 config X86_NEED_RELOCS
1976         def_bool y
1977         depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1978 
1979 config PHYSICAL_ALIGN
1980         hex "Alignment value to which kernel should be aligned"
1981         default "0x200000"
1982         range 0x2000 0x1000000 if X86_32
1983         range 0x200000 0x1000000 if X86_64
1984         ---help---
1985           This value puts the alignment restrictions on physical address
1986           where kernel is loaded and run from. Kernel is compiled for an
1987           address which meets above alignment restriction.
1988 
1989           If bootloader loads the kernel at a non-aligned address and
1990           CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1991           address aligned to above value and run from there.
1992 
1993           If bootloader loads the kernel at a non-aligned address and
1994           CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1995           load address and decompress itself to the address it has been
1996           compiled for and run from there. The address for which kernel is
1997           compiled already meets above alignment restrictions. Hence the
1998           end result is that kernel runs from a physical address meeting
1999           above alignment restrictions.
2000 
2001           On 32-bit this value must be a multiple of 0x2000. On 64-bit
2002           this value must be a multiple of 0x200000.
2003 
2004           Don't change this unless you know what you are doing.
2005 
2006 config RANDOMIZE_MEMORY
2007         bool "Randomize the kernel memory sections"
2008         depends on X86_64
2009         depends on RANDOMIZE_BASE
2010         default RANDOMIZE_BASE
2011         ---help---
2012            Randomizes the base virtual address of kernel memory sections
2013            (physical memory mapping, vmalloc & vmemmap). This security feature
2014            makes exploits relying on predictable memory locations less reliable.
2015 
2016            The order of allocations remains unchanged. Entropy is generated in
2017            the same way as RANDOMIZE_BASE. Current implementation in the optimal
2018            configuration have in average 30,000 different possible virtual
2019            addresses for each memory section.
2020 
2021            If unsure, say N.
2022 
2023 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2024         hex "Physical memory mapping padding" if EXPERT
2025         depends on RANDOMIZE_MEMORY
2026         default "0xa" if MEMORY_HOTPLUG
2027         default "0x0"
2028         range 0x1 0x40 if MEMORY_HOTPLUG
2029         range 0x0 0x40
2030         ---help---
2031            Define the padding in terabytes added to the existing physical
2032            memory size during kernel memory randomization. It is useful
2033            for memory hotplug support but reduces the entropy available for
2034            address randomization.
2035 
2036            If unsure, leave at the default value.
2037 
2038 config HOTPLUG_CPU
2039         bool "Support for hot-pluggable CPUs"
2040         depends on SMP
2041         ---help---
2042           Say Y here to allow turning CPUs off and on. CPUs can be
2043           controlled through /sys/devices/system/cpu.
2044           ( Note: power management support will enable this option
2045             automatically on SMP systems. )
2046           Say N if you want to disable CPU hotplug.
2047 
2048 config BOOTPARAM_HOTPLUG_CPU0
2049         bool "Set default setting of cpu0_hotpluggable"
2050         default n
2051         depends on HOTPLUG_CPU
2052         ---help---
2053           Set whether default state of cpu0_hotpluggable is on or off.
2054 
2055           Say Y here to enable CPU0 hotplug by default. If this switch
2056           is turned on, there is no need to give cpu0_hotplug kernel
2057           parameter and the CPU0 hotplug feature is enabled by default.
2058 
2059           Please note: there are two known CPU0 dependencies if you want
2060           to enable the CPU0 hotplug feature either by this switch or by
2061           cpu0_hotplug kernel parameter.
2062 
2063           First, resume from hibernate or suspend always starts from CPU0.
2064           So hibernate and suspend are prevented if CPU0 is offline.
2065 
2066           Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2067           offline if any interrupt can not migrate out of CPU0. There may
2068           be other CPU0 dependencies.
2069 
2070           Please make sure the dependencies are under your control before
2071           you enable this feature.
2072 
2073           Say N if you don't want to enable CPU0 hotplug feature by default.
2074           You still can enable the CPU0 hotplug feature at boot by kernel
2075           parameter cpu0_hotplug.
2076 
2077 config DEBUG_HOTPLUG_CPU0
2078         def_bool n
2079         prompt "Debug CPU0 hotplug"
2080         depends on HOTPLUG_CPU
2081         ---help---
2082           Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2083           soon as possible and boots up userspace with CPU0 offlined. User
2084           can online CPU0 back after boot time.
2085 
2086           To debug CPU0 hotplug, you need to enable CPU0 offline/online
2087           feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2088           compilation or giving cpu0_hotplug kernel parameter at boot.
2089 
2090           If unsure, say N.
2091 
2092 config COMPAT_VDSO
2093         def_bool n
2094         prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2095         depends on X86_32 || IA32_EMULATION
2096         ---help---
2097           Certain buggy versions of glibc will crash if they are
2098           presented with a 32-bit vDSO that is not mapped at the address
2099           indicated in its segment table.
2100 
2101           The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2102           and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2103           49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2104           the only released version with the bug, but OpenSUSE 9
2105           contains a buggy "glibc 2.3.2".
2106 
2107           The symptom of the bug is that everything crashes on startup, saying:
2108           dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2109 
2110           Saying Y here changes the default value of the vdso32 boot
2111           option from 1 to 0, which turns off the 32-bit vDSO entirely.
2112           This works around the glibc bug but hurts performance.
2113 
2114           If unsure, say N: if you are compiling your own kernel, you
2115           are unlikely to be using a buggy version of glibc.
2116 
2117 choice
2118         prompt "vsyscall table for legacy applications"
2119         depends on X86_64
2120         default LEGACY_VSYSCALL_EMULATE
2121         help
2122           Legacy user code that does not know how to find the vDSO expects
2123           to be able to issue three syscalls by calling fixed addresses in
2124           kernel space. Since this location is not randomized with ASLR,
2125           it can be used to assist security vulnerability exploitation.
2126 
2127           This setting can be changed at boot time via the kernel command
2128           line parameter vsyscall=[native|emulate|none].
2129 
2130           On a system with recent enough glibc (2.14 or newer) and no
2131           static binaries, you can say None without a performance penalty
2132           to improve security.
2133 
2134           If unsure, select "Emulate".
2135 
2136         config LEGACY_VSYSCALL_NATIVE
2137                 bool "Native"
2138                 help
2139                   Actual executable code is located in the fixed vsyscall
2140                   address mapping, implementing time() efficiently. Since
2141                   this makes the mapping executable, it can be used during
2142                   security vulnerability exploitation (traditionally as
2143                   ROP gadgets). This configuration is not recommended.
2144 
2145         config LEGACY_VSYSCALL_EMULATE
2146                 bool "Emulate"
2147                 help
2148                   The kernel traps and emulates calls into the fixed
2149                   vsyscall address mapping. This makes the mapping
2150                   non-executable, but it still contains known contents,
2151                   which could be used in certain rare security vulnerability
2152                   exploits. This configuration is recommended when userspace
2153                   still uses the vsyscall area.
2154 
2155         config LEGACY_VSYSCALL_NONE
2156                 bool "None"
2157                 help
2158                   There will be no vsyscall mapping at all. This will
2159                   eliminate any risk of ASLR bypass due to the vsyscall
2160                   fixed address mapping. Attempts to use the vsyscalls
2161                   will be reported to dmesg, so that either old or
2162                   malicious userspace programs can be identified.
2163 
2164 endchoice
2165 
2166 config CMDLINE_BOOL
2167         bool "Built-in kernel command line"
2168         ---help---
2169           Allow for specifying boot arguments to the kernel at
2170           build time.  On some systems (e.g. embedded ones), it is
2171           necessary or convenient to provide some or all of the
2172           kernel boot arguments with the kernel itself (that is,
2173           to not rely on the boot loader to provide them.)
2174 
2175           To compile command line arguments into the kernel,
2176           set this option to 'Y', then fill in the
2177           boot arguments in CONFIG_CMDLINE.
2178 
2179           Systems with fully functional boot loaders (i.e. non-embedded)
2180           should leave this option set to 'N'.
2181 
2182 config CMDLINE
2183         string "Built-in kernel command string"
2184         depends on CMDLINE_BOOL
2185         default ""
2186         ---help---
2187           Enter arguments here that should be compiled into the kernel
2188           image and used at boot time.  If the boot loader provides a
2189           command line at boot time, it is appended to this string to
2190           form the full kernel command line, when the system boots.
2191 
2192           However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2193           change this behavior.
2194 
2195           In most cases, the command line (whether built-in or provided
2196           by the boot loader) should specify the device for the root
2197           file system.
2198 
2199 config CMDLINE_OVERRIDE
2200         bool "Built-in command line overrides boot loader arguments"
2201         depends on CMDLINE_BOOL
2202         ---help---
2203           Set this option to 'Y' to have the kernel ignore the boot loader
2204           command line, and use ONLY the built-in command line.
2205 
2206           This is used to work around broken boot loaders.  This should
2207           be set to 'N' under normal conditions.
2208 
2209 config MODIFY_LDT_SYSCALL
2210         bool "Enable the LDT (local descriptor table)" if EXPERT
2211         default y
2212         ---help---
2213           Linux can allow user programs to install a per-process x86
2214           Local Descriptor Table (LDT) using the modify_ldt(2) system
2215           call.  This is required to run 16-bit or segmented code such as
2216           DOSEMU or some Wine programs.  It is also used by some very old
2217           threading libraries.
2218 
2219           Enabling this feature adds a small amount of overhead to
2220           context switches and increases the low-level kernel attack
2221           surface.  Disabling it removes the modify_ldt(2) system call.
2222 
2223           Saying 'N' here may make sense for embedded or server kernels.
2224 
2225 source "kernel/livepatch/Kconfig"
2226 
2227 endmenu
2228 
2229 config ARCH_ENABLE_MEMORY_HOTPLUG
2230         def_bool y
2231         depends on X86_64 || (X86_32 && HIGHMEM)
2232 
2233 config ARCH_ENABLE_MEMORY_HOTREMOVE
2234         def_bool y
2235         depends on MEMORY_HOTPLUG
2236 
2237 config USE_PERCPU_NUMA_NODE_ID
2238         def_bool y
2239         depends on NUMA
2240 
2241 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2242         def_bool y
2243         depends on X86_64 || X86_PAE
2244 
2245 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2246         def_bool y
2247         depends on X86_64 && HUGETLB_PAGE && MIGRATION
2248 
2249 menu "Power management and ACPI options"
2250 
2251 config ARCH_HIBERNATION_HEADER
2252         def_bool y
2253         depends on X86_64 && HIBERNATION
2254 
2255 source "kernel/power/Kconfig"
2256 
2257 source "drivers/acpi/Kconfig"
2258 
2259 source "drivers/sfi/Kconfig"
2260 
2261 config X86_APM_BOOT
2262         def_bool y
2263         depends on APM
2264 
2265 menuconfig APM
2266         tristate "APM (Advanced Power Management) BIOS support"
2267         depends on X86_32 && PM_SLEEP
2268         ---help---
2269           APM is a BIOS specification for saving power using several different
2270           techniques. This is mostly useful for battery powered laptops with
2271           APM compliant BIOSes. If you say Y here, the system time will be
2272           reset after a RESUME operation, the /proc/apm device will provide
2273           battery status information, and user-space programs will receive
2274           notification of APM "events" (e.g. battery status change).
2275 
2276           If you select "Y" here, you can disable actual use of the APM
2277           BIOS by passing the "apm=off" option to the kernel at boot time.
2278 
2279           Note that the APM support is almost completely disabled for
2280           machines with more than one CPU.
2281 
2282           In order to use APM, you will need supporting software. For location
2283           and more information, read <file:Documentation/power/apm-acpi.txt>
2284           and the Battery Powered Linux mini-HOWTO, available from
2285           <http://www.tldp.org/docs.html#howto>.
2286 
2287           This driver does not spin down disk drives (see the hdparm(8)
2288           manpage ("man 8 hdparm") for that), and it doesn't turn off
2289           VESA-compliant "green" monitors.
2290 
2291           This driver does not support the TI 4000M TravelMate and the ACER
2292           486/DX4/75 because they don't have compliant BIOSes. Many "green"
2293           desktop machines also don't have compliant BIOSes, and this driver
2294           may cause those machines to panic during the boot phase.
2295 
2296           Generally, if you don't have a battery in your machine, there isn't
2297           much point in using this driver and you should say N. If you get
2298           random kernel OOPSes or reboots that don't seem to be related to
2299           anything, try disabling/enabling this option (or disabling/enabling
2300           APM in your BIOS).
2301 
2302           Some other things you should try when experiencing seemingly random,
2303           "weird" problems:
2304 
2305           1) make sure that you have enough swap space and that it is
2306           enabled.
2307           2) pass the "no-hlt" option to the kernel
2308           3) switch on floating point emulation in the kernel and pass
2309           the "no387" option to the kernel
2310           4) pass the "floppy=nodma" option to the kernel
2311           5) pass the "mem=4M" option to the kernel (thereby disabling
2312           all but the first 4 MB of RAM)
2313           6) make sure that the CPU is not over clocked.
2314           7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2315           8) disable the cache from your BIOS settings
2316           9) install a fan for the video card or exchange video RAM
2317           10) install a better fan for the CPU
2318           11) exchange RAM chips
2319           12) exchange the motherboard.
2320 
2321           To compile this driver as a module, choose M here: the
2322           module will be called apm.
2323 
2324 if APM
2325 
2326 config APM_IGNORE_USER_SUSPEND
2327         bool "Ignore USER SUSPEND"
2328         ---help---
2329           This option will ignore USER SUSPEND requests. On machines with a
2330           compliant APM BIOS, you want to say N. However, on the NEC Versa M
2331           series notebooks, it is necessary to say Y because of a BIOS bug.
2332 
2333 config APM_DO_ENABLE
2334         bool "Enable PM at boot time"
2335         ---help---
2336           Enable APM features at boot time. From page 36 of the APM BIOS
2337           specification: "When disabled, the APM BIOS does not automatically
2338           power manage devices, enter the Standby State, enter the Suspend
2339           State, or take power saving steps in response to CPU Idle calls."
2340           This driver will make CPU Idle calls when Linux is idle (unless this
2341           feature is turned off -- see "Do CPU IDLE calls", below). This
2342           should always save battery power, but more complicated APM features
2343           will be dependent on your BIOS implementation. You may need to turn
2344           this option off if your computer hangs at boot time when using APM
2345           support, or if it beeps continuously instead of suspending. Turn
2346           this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2347           T400CDT. This is off by default since most machines do fine without
2348           this feature.
2349 
2350 config APM_CPU_IDLE
2351         depends on CPU_IDLE
2352         bool "Make CPU Idle calls when idle"
2353         ---help---
2354           Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2355           On some machines, this can activate improved power savings, such as
2356           a slowed CPU clock rate, when the machine is idle. These idle calls
2357           are made after the idle loop has run for some length of time (e.g.,
2358           333 mS). On some machines, this will cause a hang at boot time or
2359           whenever the CPU becomes idle. (On machines with more than one CPU,
2360           this option does nothing.)
2361 
2362 config APM_DISPLAY_BLANK
2363         bool "Enable console blanking using APM"
2364         ---help---
2365           Enable console blanking using the APM. Some laptops can use this to
2366           turn off the LCD backlight when the screen blanker of the Linux
2367           virtual console blanks the screen. Note that this is only used by
2368           the virtual console screen blanker, and won't turn off the backlight
2369           when using the X Window system. This also doesn't have anything to
2370           do with your VESA-compliant power-saving monitor. Further, this
2371           option doesn't work for all laptops -- it might not turn off your
2372           backlight at all, or it might print a lot of errors to the console,
2373           especially if you are using gpm.
2374 
2375 config APM_ALLOW_INTS
2376         bool "Allow interrupts during APM BIOS calls"
2377         ---help---
2378           Normally we disable external interrupts while we are making calls to
2379           the APM BIOS as a measure to lessen the effects of a badly behaving
2380           BIOS implementation.  The BIOS should reenable interrupts if it
2381           needs to.  Unfortunately, some BIOSes do not -- especially those in
2382           many of the newer IBM Thinkpads.  If you experience hangs when you
2383           suspend, try setting this to Y.  Otherwise, say N.
2384 
2385 endif # APM
2386 
2387 source "drivers/cpufreq/Kconfig"
2388 
2389 source "drivers/cpuidle/Kconfig"
2390 
2391 source "drivers/idle/Kconfig"
2392 
2393 endmenu
2394 
2395 
2396 menu "Bus options (PCI etc.)"
2397 
2398 config PCI
2399         bool "PCI support"
2400         default y
2401         ---help---
2402           Find out whether you have a PCI motherboard. PCI is the name of a
2403           bus system, i.e. the way the CPU talks to the other stuff inside
2404           your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2405           VESA. If you have PCI, say Y, otherwise N.
2406 
2407 choice
2408         prompt "PCI access mode"
2409         depends on X86_32 && PCI
2410         default PCI_GOANY
2411         ---help---
2412           On PCI systems, the BIOS can be used to detect the PCI devices and
2413           determine their configuration. However, some old PCI motherboards
2414           have BIOS bugs and may crash if this is done. Also, some embedded
2415           PCI-based systems don't have any BIOS at all. Linux can also try to
2416           detect the PCI hardware directly without using the BIOS.
2417 
2418           With this option, you can specify how Linux should detect the
2419           PCI devices. If you choose "BIOS", the BIOS will be used,
2420           if you choose "Direct", the BIOS won't be used, and if you
2421           choose "MMConfig", then PCI Express MMCONFIG will be used.
2422           If you choose "Any", the kernel will try MMCONFIG, then the
2423           direct access method and falls back to the BIOS if that doesn't
2424           work. If unsure, go with the default, which is "Any".
2425 
2426 config PCI_GOBIOS
2427         bool "BIOS"
2428 
2429 config PCI_GOMMCONFIG
2430         bool "MMConfig"
2431 
2432 config PCI_GODIRECT
2433         bool "Direct"
2434 
2435 config PCI_GOOLPC
2436         bool "OLPC XO-1"
2437         depends on OLPC
2438 
2439 config PCI_GOANY
2440         bool "Any"
2441 
2442 endchoice
2443 
2444 config PCI_BIOS
2445         def_bool y
2446         depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2447 
2448 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2449 config PCI_DIRECT
2450         def_bool y
2451         depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2452 
2453 config PCI_MMCONFIG
2454         def_bool y
2455         depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2456 
2457 config PCI_OLPC
2458         def_bool y
2459         depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2460 
2461 config PCI_XEN
2462         def_bool y
2463         depends on PCI && XEN
2464         select SWIOTLB_XEN
2465 
2466 config PCI_DOMAINS
2467         def_bool y
2468         depends on PCI
2469 
2470 config PCI_MMCONFIG
2471         bool "Support mmconfig PCI config space access"
2472         depends on X86_64 && PCI && ACPI
2473 
2474 config PCI_CNB20LE_QUIRK
2475         bool "Read CNB20LE Host Bridge Windows" if EXPERT
2476         depends on PCI
2477         help
2478           Read the PCI windows out of the CNB20LE host bridge. This allows
2479           PCI hotplug to work on systems with the CNB20LE chipset which do
2480           not have ACPI.
2481 
2482           There's no public spec for this chipset, and this functionality
2483           is known to be incomplete.
2484 
2485           You should say N unless you know you need this.
2486 
2487 source "drivers/pci/Kconfig"
2488 
2489 config ISA_BUS
2490         bool "ISA-style bus support on modern systems" if EXPERT
2491         select ISA_BUS_API
2492         help
2493           Enables ISA-style drivers on modern systems. This is necessary to
2494           support PC/104 devices on X86_64 platforms.
2495 
2496           If unsure, say N.
2497 
2498 # x86_64 have no ISA slots, but can have ISA-style DMA.
2499 config ISA_DMA_API
2500         bool "ISA-style DMA support" if (X86_64 && EXPERT)
2501         default y
2502         help
2503           Enables ISA-style DMA support for devices requiring such controllers.
2504           If unsure, say Y.
2505 
2506 if X86_32
2507 
2508 config ISA
2509         bool "ISA support"
2510         ---help---
2511           Find out whether you have ISA slots on your motherboard.  ISA is the
2512           name of a bus system, i.e. the way the CPU talks to the other stuff
2513           inside your box.  Other bus systems are PCI, EISA, MicroChannel
2514           (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2515           newer boards don't support it.  If you have ISA, say Y, otherwise N.
2516 
2517 config EISA
2518         bool "EISA support"
2519         depends on ISA
2520         ---help---
2521           The Extended Industry Standard Architecture (EISA) bus was
2522           developed as an open alternative to the IBM MicroChannel bus.
2523 
2524           The EISA bus provided some of the features of the IBM MicroChannel
2525           bus while maintaining backward compatibility with cards made for
2526           the older ISA bus.  The EISA bus saw limited use between 1988 and
2527           1995 when it was made obsolete by the PCI bus.
2528 
2529           Say Y here if you are building a kernel for an EISA-based machine.
2530 
2531           Otherwise, say N.
2532 
2533 source "drivers/eisa/Kconfig"
2534 
2535 config SCx200
2536         tristate "NatSemi SCx200 support"
2537         ---help---
2538           This provides basic support for National Semiconductor's
2539           (now AMD's) Geode processors.  The driver probes for the
2540           PCI-IDs of several on-chip devices, so its a good dependency
2541           for other scx200_* drivers.
2542 
2543           If compiled as a module, the driver is named scx200.
2544 
2545 config SCx200HR_TIMER
2546         tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2547         depends on SCx200
2548         default y
2549         ---help---
2550           This driver provides a clocksource built upon the on-chip
2551           27MHz high-resolution timer.  Its also a workaround for
2552           NSC Geode SC-1100's buggy TSC, which loses time when the
2553           processor goes idle (as is done by the scheduler).  The
2554           other workaround is idle=poll boot option.
2555 
2556 config OLPC
2557         bool "One Laptop Per Child support"
2558         depends on !X86_PAE
2559         select GPIOLIB
2560         select OF
2561         select OF_PROMTREE
2562         select IRQ_DOMAIN
2563         ---help---
2564           Add support for detecting the unique features of the OLPC
2565           XO hardware.
2566 
2567 config OLPC_XO1_PM
2568         bool "OLPC XO-1 Power Management"
2569         depends on OLPC && MFD_CS5535 && PM_SLEEP
2570         select MFD_CORE
2571         ---help---
2572           Add support for poweroff and suspend of the OLPC XO-1 laptop.
2573 
2574 config OLPC_XO1_RTC
2575         bool "OLPC XO-1 Real Time Clock"
2576         depends on OLPC_XO1_PM && RTC_DRV_CMOS
2577         ---help---
2578           Add support for the XO-1 real time clock, which can be used as a
2579           programmable wakeup source.
2580 
2581 config OLPC_XO1_SCI
2582         bool "OLPC XO-1 SCI extras"
2583         depends on OLPC && OLPC_XO1_PM
2584         depends on INPUT=y
2585         select POWER_SUPPLY
2586         select GPIO_CS5535
2587         select MFD_CORE
2588         ---help---
2589           Add support for SCI-based features of the OLPC XO-1 laptop:
2590            - EC-driven system wakeups
2591            - Power button
2592            - Ebook switch
2593            - Lid switch
2594            - AC adapter status updates
2595            - Battery status updates
2596 
2597 config OLPC_XO15_SCI
2598         bool "OLPC XO-1.5 SCI extras"
2599         depends on OLPC && ACPI
2600         select POWER_SUPPLY
2601         ---help---
2602           Add support for SCI-based features of the OLPC XO-1.5 laptop:
2603            - EC-driven system wakeups
2604            - AC adapter status updates
2605            - Battery status updates
2606 
2607 config ALIX
2608         bool "PCEngines ALIX System Support (LED setup)"
2609         select GPIOLIB
2610         ---help---
2611           This option enables system support for the PCEngines ALIX.
2612           At present this just sets up LEDs for GPIO control on
2613           ALIX2/3/6 boards.  However, other system specific setup should
2614           get added here.
2615 
2616           Note: You must still enable the drivers for GPIO and LED support
2617           (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2618 
2619           Note: You have to set alix.force=1 for boards with Award BIOS.
2620 
2621 config NET5501
2622         bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2623         select GPIOLIB
2624         ---help---
2625           This option enables system support for the Soekris Engineering net5501.
2626 
2627 config GEOS
2628         bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2629         select GPIOLIB
2630         depends on DMI
2631         ---help---
2632           This option enables system support for the Traverse Technologies GEOS.
2633 
2634 config TS5500
2635         bool "Technologic Systems TS-5500 platform support"
2636         depends on MELAN
2637         select CHECK_SIGNATURE
2638         select NEW_LEDS
2639         select LEDS_CLASS
2640         ---help---
2641           This option enables system support for the Technologic Systems TS-5500.
2642 
2643 endif # X86_32
2644 
2645 config AMD_NB
2646         def_bool y
2647         depends on CPU_SUP_AMD && PCI
2648 
2649 source "drivers/pcmcia/Kconfig"
2650 
2651 config RAPIDIO
2652         tristate "RapidIO support"
2653         depends on PCI
2654         default n
2655         help
2656           If enabled this option will include drivers and the core
2657           infrastructure code to support RapidIO interconnect devices.
2658 
2659 source "drivers/rapidio/Kconfig"
2660 
2661 config X86_SYSFB
2662         bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2663         help
2664           Firmwares often provide initial graphics framebuffers so the BIOS,
2665           bootloader or kernel can show basic video-output during boot for
2666           user-guidance and debugging. Historically, x86 used the VESA BIOS
2667           Extensions and EFI-framebuffers for this, which are mostly limited
2668           to x86.
2669           This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2670           framebuffers so the new generic system-framebuffer drivers can be
2671           used on x86. If the framebuffer is not compatible with the generic
2672           modes, it is adverticed as fallback platform framebuffer so legacy
2673           drivers like efifb, vesafb and uvesafb can pick it up.
2674           If this option is not selected, all system framebuffers are always
2675           marked as fallback platform framebuffers as usual.
2676 
2677           Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2678           not be able to pick up generic system framebuffers if this option
2679           is selected. You are highly encouraged to enable simplefb as
2680           replacement if you select this option. simplefb can correctly deal
2681           with generic system framebuffers. But you should still keep vesafb
2682           and others enabled as fallback if a system framebuffer is
2683           incompatible with simplefb.
2684 
2685           If unsure, say Y.
2686 
2687 endmenu
2688 
2689 
2690 menu "Executable file formats / Emulations"
2691 
2692 source "fs/Kconfig.binfmt"
2693 
2694 config IA32_EMULATION
2695         bool "IA32 Emulation"
2696         depends on X86_64
2697         select BINFMT_ELF
2698         select COMPAT_BINFMT_ELF
2699         select ARCH_WANT_OLD_COMPAT_IPC
2700         ---help---
2701           Include code to run legacy 32-bit programs under a
2702           64-bit kernel. You should likely turn this on, unless you're
2703           100% sure that you don't have any 32-bit programs left.
2704 
2705 config IA32_AOUT
2706         tristate "IA32 a.out support"
2707         depends on IA32_EMULATION
2708         ---help---
2709           Support old a.out binaries in the 32bit emulation.
2710 
2711 config X86_X32
2712         bool "x32 ABI for 64-bit mode"
2713         depends on X86_64
2714         ---help---
2715           Include code to run binaries for the x32 native 32-bit ABI
2716           for 64-bit processors.  An x32 process gets access to the
2717           full 64-bit register file and wide data path while leaving
2718           pointers at 32 bits for smaller memory footprint.
2719 
2720           You will need a recent binutils (2.22 or later) with
2721           elf32_x86_64 support enabled to compile a kernel with this
2722           option set.
2723 
2724 config COMPAT
2725         def_bool y
2726         depends on IA32_EMULATION || X86_X32
2727 
2728 if COMPAT
2729 config COMPAT_FOR_U64_ALIGNMENT
2730         def_bool y
2731 
2732 config SYSVIPC_COMPAT
2733         def_bool y
2734         depends on SYSVIPC
2735 
2736 config KEYS_COMPAT
2737         def_bool y
2738         depends on KEYS
2739 endif
2740 
2741 endmenu
2742 
2743 
2744 config HAVE_ATOMIC_IOMAP
2745         def_bool y
2746         depends on X86_32
2747 
2748 config X86_DEV_DMA_OPS
2749         bool
2750         depends on X86_64 || STA2X11
2751 
2752 config X86_DMA_REMAP
2753         bool
2754         depends on STA2X11
2755 
2756 config PMC_ATOM
2757         def_bool y
2758         depends on PCI
2759 
2760 source "net/Kconfig"
2761 
2762 source "drivers/Kconfig"
2763 
2764 source "drivers/firmware/Kconfig"
2765 
2766 source "fs/Kconfig"
2767 
2768 source "arch/x86/Kconfig.debug"
2769 
2770 source "security/Kconfig"
2771 
2772 source "crypto/Kconfig"
2773 
2774 source "arch/x86/kvm/Kconfig"
2775 
2776 source "lib/Kconfig"

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