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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         select CLKSRC_I8253
 13         select HAVE_UID16
 14 
 15 config X86_64
 16         def_bool y
 17         depends on 64BIT
 18         select X86_DEV_DMA_OPS
 19         select ARCH_USE_CMPXCHG_LOCKREF
 20 
 21 ### Arch settings
 22 config X86
 23         def_bool y
 24         select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
 25         select ARCH_MIGHT_HAVE_PC_PARPORT
 26         select ARCH_MIGHT_HAVE_PC_SERIO
 27         select HAVE_AOUT if X86_32
 28         select HAVE_UNSTABLE_SCHED_CLOCK
 29         select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
 30         select ARCH_SUPPORTS_INT128 if X86_64
 31         select ARCH_WANTS_PROT_NUMA_PROT_NONE
 32         select HAVE_IDE
 33         select HAVE_OPROFILE
 34         select HAVE_PCSPKR_PLATFORM
 35         select HAVE_PERF_EVENTS
 36         select HAVE_IOREMAP_PROT
 37         select HAVE_KPROBES
 38         select HAVE_MEMBLOCK
 39         select HAVE_MEMBLOCK_NODE_MAP
 40         select ARCH_DISCARD_MEMBLOCK
 41         select ARCH_WANT_OPTIONAL_GPIOLIB
 42         select ARCH_WANT_FRAME_POINTERS
 43         select HAVE_DMA_ATTRS
 44         select HAVE_DMA_CONTIGUOUS
 45         select HAVE_KRETPROBES
 46         select GENERIC_EARLY_IOREMAP
 47         select HAVE_OPTPROBES
 48         select HAVE_KPROBES_ON_FTRACE
 49         select HAVE_FTRACE_MCOUNT_RECORD
 50         select HAVE_FENTRY if X86_64
 51         select HAVE_C_RECORDMCOUNT
 52         select HAVE_DYNAMIC_FTRACE
 53         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 54         select HAVE_FUNCTION_TRACER
 55         select HAVE_FUNCTION_GRAPH_TRACER
 56         select HAVE_FUNCTION_GRAPH_FP_TEST
 57         select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 58         select HAVE_SYSCALL_TRACEPOINTS
 59         select SYSCTL_EXCEPTION_TRACE
 60         select HAVE_KVM
 61         select HAVE_ARCH_KGDB
 62         select HAVE_ARCH_TRACEHOOK
 63         select HAVE_GENERIC_DMA_COHERENT if X86_32
 64         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 65         select USER_STACKTRACE_SUPPORT
 66         select HAVE_REGS_AND_STACK_ACCESS_API
 67         select HAVE_DMA_API_DEBUG
 68         select HAVE_KERNEL_GZIP
 69         select HAVE_KERNEL_BZIP2
 70         select HAVE_KERNEL_LZMA
 71         select HAVE_KERNEL_XZ
 72         select HAVE_KERNEL_LZO
 73         select HAVE_KERNEL_LZ4
 74         select HAVE_HW_BREAKPOINT
 75         select HAVE_MIXED_BREAKPOINTS_REGS
 76         select PERF_EVENTS
 77         select HAVE_PERF_EVENTS_NMI
 78         select HAVE_PERF_REGS
 79         select HAVE_PERF_USER_STACK_DUMP
 80         select HAVE_DEBUG_KMEMLEAK
 81         select ANON_INODES
 82         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 83         select HAVE_CMPXCHG_LOCAL
 84         select HAVE_CMPXCHG_DOUBLE
 85         select HAVE_ARCH_KMEMCHECK
 86         select HAVE_USER_RETURN_NOTIFIER
 87         select ARCH_BINFMT_ELF_RANDOMIZE_PIE
 88         select HAVE_ARCH_JUMP_LABEL
 89         select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 90         select SPARSE_IRQ
 91         select GENERIC_FIND_FIRST_BIT
 92         select GENERIC_IRQ_PROBE
 93         select GENERIC_PENDING_IRQ if SMP
 94         select GENERIC_IRQ_SHOW
 95         select GENERIC_CLOCKEVENTS_MIN_ADJUST
 96         select IRQ_FORCED_THREADING
 97         select HAVE_BPF_JIT if X86_64
 98         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 99         select CLKEVT_I8253
100         select ARCH_HAVE_NMI_SAFE_CMPXCHG
101         select GENERIC_IOMAP
102         select DCACHE_WORD_ACCESS
103         select GENERIC_SMP_IDLE_THREAD
104         select ARCH_WANT_IPC_PARSE_VERSION if X86_32
105         select HAVE_ARCH_SECCOMP_FILTER
106         select BUILDTIME_EXTABLE_SORT
107         select GENERIC_CMOS_UPDATE
108         select HAVE_ARCH_SOFT_DIRTY if X86_64
109         select CLOCKSOURCE_WATCHDOG
110         select GENERIC_CLOCKEVENTS
111         select ARCH_CLOCKSOURCE_DATA
112         select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
113         select GENERIC_TIME_VSYSCALL
114         select KTIME_SCALAR if X86_32
115         select GENERIC_STRNCPY_FROM_USER
116         select GENERIC_STRNLEN_USER
117         select HAVE_CONTEXT_TRACKING if X86_64
118         select HAVE_IRQ_TIME_ACCOUNTING
119         select VIRT_TO_BUS
120         select MODULES_USE_ELF_REL if X86_32
121         select MODULES_USE_ELF_RELA if X86_64
122         select CLONE_BACKWARDS if X86_32
123         select ARCH_USE_BUILTIN_BSWAP
124         select ARCH_USE_QUEUE_RWLOCK
125         select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
126         select OLD_SIGACTION if X86_32
127         select COMPAT_OLD_SIGACTION if IA32_EMULATION
128         select RTC_LIB
129         select HAVE_DEBUG_STACKOVERFLOW
130         select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
131         select HAVE_CC_STACKPROTECTOR
132         select GENERIC_CPU_AUTOPROBE
133         select HAVE_ARCH_AUDITSYSCALL
134         select ARCH_SUPPORTS_ATOMIC_RMW
135 
136 config INSTRUCTION_DECODER
137         def_bool y
138         depends on KPROBES || PERF_EVENTS || UPROBES
139 
140 config OUTPUT_FORMAT
141         string
142         default "elf32-i386" if X86_32
143         default "elf64-x86-64" if X86_64
144 
145 config ARCH_DEFCONFIG
146         string
147         default "arch/x86/configs/i386_defconfig" if X86_32
148         default "arch/x86/configs/x86_64_defconfig" if X86_64
149 
150 config LOCKDEP_SUPPORT
151         def_bool y
152 
153 config STACKTRACE_SUPPORT
154         def_bool y
155 
156 config HAVE_LATENCYTOP_SUPPORT
157         def_bool y
158 
159 config MMU
160         def_bool y
161 
162 config SBUS
163         bool
164 
165 config NEED_DMA_MAP_STATE
166         def_bool y
167         depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
168 
169 config NEED_SG_DMA_LENGTH
170         def_bool y
171 
172 config GENERIC_ISA_DMA
173         def_bool y
174         depends on ISA_DMA_API
175 
176 config GENERIC_BUG
177         def_bool y
178         depends on BUG
179         select GENERIC_BUG_RELATIVE_POINTERS if X86_64
180 
181 config GENERIC_BUG_RELATIVE_POINTERS
182         bool
183 
184 config GENERIC_HWEIGHT
185         def_bool y
186 
187 config ARCH_MAY_HAVE_PC_FDC
188         def_bool y
189         depends on ISA_DMA_API
190 
191 config RWSEM_XCHGADD_ALGORITHM
192         def_bool y
193 
194 config GENERIC_CALIBRATE_DELAY
195         def_bool y
196 
197 config ARCH_HAS_CPU_RELAX
198         def_bool y
199 
200 config ARCH_HAS_CACHE_LINE_SIZE
201         def_bool y
202 
203 config HAVE_SETUP_PER_CPU_AREA
204         def_bool y
205 
206 config NEED_PER_CPU_EMBED_FIRST_CHUNK
207         def_bool y
208 
209 config NEED_PER_CPU_PAGE_FIRST_CHUNK
210         def_bool y
211 
212 config ARCH_HIBERNATION_POSSIBLE
213         def_bool y
214 
215 config ARCH_SUSPEND_POSSIBLE
216         def_bool y
217 
218 config ARCH_WANT_HUGE_PMD_SHARE
219         def_bool y
220 
221 config ARCH_WANT_GENERAL_HUGETLB
222         def_bool y
223 
224 config ZONE_DMA32
225         bool
226         default X86_64
227 
228 config AUDIT_ARCH
229         bool
230         default X86_64
231 
232 config ARCH_SUPPORTS_OPTIMIZED_INLINING
233         def_bool y
234 
235 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
236         def_bool y
237 
238 config HAVE_INTEL_TXT
239         def_bool y
240         depends on INTEL_IOMMU && ACPI
241 
242 config X86_32_SMP
243         def_bool y
244         depends on X86_32 && SMP
245 
246 config X86_64_SMP
247         def_bool y
248         depends on X86_64 && SMP
249 
250 config X86_HT
251         def_bool y
252         depends on SMP
253 
254 config X86_32_LAZY_GS
255         def_bool y
256         depends on X86_32 && !CC_STACKPROTECTOR
257 
258 config ARCH_HWEIGHT_CFLAGS
259         string
260         default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
261         default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
262 
263 config ARCH_SUPPORTS_UPROBES
264         def_bool y
265 
266 config FIX_EARLYCON_MEM
267         def_bool y
268 
269 source "init/Kconfig"
270 source "kernel/Kconfig.freezer"
271 
272 menu "Processor type and features"
273 
274 config ZONE_DMA
275         bool "DMA memory allocation support" if EXPERT
276         default y
277         help
278           DMA memory allocation support allows devices with less than 32-bit
279           addressing to allocate within the first 16MB of address space.
280           Disable if no such devices will be used.
281 
282           If unsure, say Y.
283 
284 config SMP
285         bool "Symmetric multi-processing support"
286         ---help---
287           This enables support for systems with more than one CPU. If you have
288           a system with only one CPU, say N. If you have a system with more
289           than one CPU, say Y.
290 
291           If you say N here, the kernel will run on uni- and multiprocessor
292           machines, but will use only one CPU of a multiprocessor machine. If
293           you say Y here, the kernel will run on many, but not all,
294           uniprocessor machines. On a uniprocessor machine, the kernel
295           will run faster if you say N here.
296 
297           Note that if you say Y here and choose architecture "586" or
298           "Pentium" under "Processor family", the kernel will not work on 486
299           architectures. Similarly, multiprocessor kernels for the "PPro"
300           architecture may not work on all Pentium based boards.
301 
302           People using multiprocessor machines who say Y here should also say
303           Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
304           Management" code will be disabled if you say Y here.
305 
306           See also <file:Documentation/x86/i386/IO-APIC.txt>,
307           <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
308           <http://www.tldp.org/docs.html#howto>.
309 
310           If you don't know what to do here, say N.
311 
312 config X86_X2APIC
313         bool "Support x2apic"
314         depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
315         ---help---
316           This enables x2apic support on CPUs that have this feature.
317 
318           This allows 32-bit apic IDs (so it can support very large systems),
319           and accesses the local apic via MSRs not via mmio.
320 
321           If you don't know what to do here, say N.
322 
323 config X86_MPPARSE
324         bool "Enable MPS table" if ACPI || SFI
325         default y
326         depends on X86_LOCAL_APIC
327         ---help---
328           For old smp systems that do not have proper acpi support. Newer systems
329           (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
330 
331 config X86_BIGSMP
332         bool "Support for big SMP systems with more than 8 CPUs"
333         depends on X86_32 && SMP
334         ---help---
335           This option is needed for the systems that have more than 8 CPUs
336 
337 config GOLDFISH
338        def_bool y
339        depends on X86_GOLDFISH
340 
341 if X86_32
342 config X86_EXTENDED_PLATFORM
343         bool "Support for extended (non-PC) x86 platforms"
344         default y
345         ---help---
346           If you disable this option then the kernel will only support
347           standard PC platforms. (which covers the vast majority of
348           systems out there.)
349 
350           If you enable this option then you'll be able to select support
351           for the following (non-PC) 32 bit x86 platforms:
352                 Goldfish (Android emulator)
353                 AMD Elan
354                 RDC R-321x SoC
355                 SGI 320/540 (Visual Workstation)
356                 STA2X11-based (e.g. Northville)
357                 Moorestown MID devices
358 
359           If you have one of these systems, or if you want to build a
360           generic distribution kernel, say Y here - otherwise say N.
361 endif
362 
363 if X86_64
364 config X86_EXTENDED_PLATFORM
365         bool "Support for extended (non-PC) x86 platforms"
366         default y
367         ---help---
368           If you disable this option then the kernel will only support
369           standard PC platforms. (which covers the vast majority of
370           systems out there.)
371 
372           If you enable this option then you'll be able to select support
373           for the following (non-PC) 64 bit x86 platforms:
374                 Numascale NumaChip
375                 ScaleMP vSMP
376                 SGI Ultraviolet
377 
378           If you have one of these systems, or if you want to build a
379           generic distribution kernel, say Y here - otherwise say N.
380 endif
381 # This is an alphabetically sorted list of 64 bit extended platforms
382 # Please maintain the alphabetic order if and when there are additions
383 config X86_NUMACHIP
384         bool "Numascale NumaChip"
385         depends on X86_64
386         depends on X86_EXTENDED_PLATFORM
387         depends on NUMA
388         depends on SMP
389         depends on X86_X2APIC
390         depends on PCI_MMCONFIG
391         ---help---
392           Adds support for Numascale NumaChip large-SMP systems. Needed to
393           enable more than ~168 cores.
394           If you don't have one of these, you should say N here.
395 
396 config X86_VSMP
397         bool "ScaleMP vSMP"
398         select HYPERVISOR_GUEST
399         select PARAVIRT
400         depends on X86_64 && PCI
401         depends on X86_EXTENDED_PLATFORM
402         depends on SMP
403         ---help---
404           Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
405           supposed to run on these EM64T-based machines.  Only choose this option
406           if you have one of these machines.
407 
408 config X86_UV
409         bool "SGI Ultraviolet"
410         depends on X86_64
411         depends on X86_EXTENDED_PLATFORM
412         depends on NUMA
413         depends on X86_X2APIC
414         ---help---
415           This option is needed in order to support SGI Ultraviolet systems.
416           If you don't have one of these, you should say N here.
417 
418 # Following is an alphabetically sorted list of 32 bit extended platforms
419 # Please maintain the alphabetic order if and when there are additions
420 
421 config X86_GOLDFISH
422        bool "Goldfish (Virtual Platform)"
423        depends on X86_EXTENDED_PLATFORM
424        ---help---
425          Enable support for the Goldfish virtual platform used primarily
426          for Android development. Unless you are building for the Android
427          Goldfish emulator say N here.
428 
429 config X86_INTEL_CE
430         bool "CE4100 TV platform"
431         depends on PCI
432         depends on PCI_GODIRECT
433         depends on X86_32
434         depends on X86_EXTENDED_PLATFORM
435         select X86_REBOOTFIXUPS
436         select OF
437         select OF_EARLY_FLATTREE
438         select IRQ_DOMAIN
439         ---help---
440           Select for the Intel CE media processor (CE4100) SOC.
441           This option compiles in support for the CE4100 SOC for settop
442           boxes and media devices.
443 
444 config X86_INTEL_MID
445         bool "Intel MID platform support"
446         depends on X86_32
447         depends on X86_EXTENDED_PLATFORM
448         depends on X86_PLATFORM_DEVICES
449         depends on PCI
450         depends on PCI_GOANY
451         depends on X86_IO_APIC
452         select SFI
453         select I2C
454         select DW_APB_TIMER
455         select APB_TIMER
456         select INTEL_SCU_IPC
457         select MFD_INTEL_MSIC
458         ---help---
459           Select to build a kernel capable of supporting Intel MID (Mobile
460           Internet Device) platform systems which do not have the PCI legacy
461           interfaces. If you are building for a PC class system say N here.
462 
463           Intel MID platforms are based on an Intel processor and chipset which
464           consume less power than most of the x86 derivatives.
465 
466 config X86_INTEL_LPSS
467         bool "Intel Low Power Subsystem Support"
468         depends on ACPI
469         select COMMON_CLK
470         select PINCTRL
471         ---help---
472           Select to build support for Intel Low Power Subsystem such as
473           found on Intel Lynxpoint PCH. Selecting this option enables
474           things like clock tree (common clock framework) and pincontrol
475           which are needed by the LPSS peripheral drivers.
476 
477 config X86_RDC321X
478         bool "RDC R-321x SoC"
479         depends on X86_32
480         depends on X86_EXTENDED_PLATFORM
481         select M486
482         select X86_REBOOTFIXUPS
483         ---help---
484           This option is needed for RDC R-321x system-on-chip, also known
485           as R-8610-(G).
486           If you don't have one of these chips, you should say N here.
487 
488 config X86_32_NON_STANDARD
489         bool "Support non-standard 32-bit SMP architectures"
490         depends on X86_32 && SMP
491         depends on X86_EXTENDED_PLATFORM
492         ---help---
493           This option compiles in the bigsmp and STA2X11 default
494           subarchitectures.  It is intended for a generic binary
495           kernel. If you select them all, kernel will probe it one by
496           one and will fallback to default.
497 
498 # Alphabetically sorted list of Non standard 32 bit platforms
499 
500 config X86_SUPPORTS_MEMORY_FAILURE
501         def_bool y
502         # MCE code calls memory_failure():
503         depends on X86_MCE
504         # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
505         # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
506         depends on X86_64 || !SPARSEMEM
507         select ARCH_SUPPORTS_MEMORY_FAILURE
508 
509 config STA2X11
510         bool "STA2X11 Companion Chip Support"
511         depends on X86_32_NON_STANDARD && PCI
512         select X86_DEV_DMA_OPS
513         select X86_DMA_REMAP
514         select SWIOTLB
515         select MFD_STA2X11
516         select ARCH_REQUIRE_GPIOLIB
517         default n
518         ---help---
519           This adds support for boards based on the STA2X11 IO-Hub,
520           a.k.a. "ConneXt". The chip is used in place of the standard
521           PC chipset, so all "standard" peripherals are missing. If this
522           option is selected the kernel will still be able to boot on
523           standard PC machines.
524 
525 config X86_32_IRIS
526         tristate "Eurobraille/Iris poweroff module"
527         depends on X86_32
528         ---help---
529           The Iris machines from EuroBraille do not have APM or ACPI support
530           to shut themselves down properly.  A special I/O sequence is
531           needed to do so, which is what this module does at
532           kernel shutdown.
533 
534           This is only for Iris machines from EuroBraille.
535 
536           If unused, say N.
537 
538 config SCHED_OMIT_FRAME_POINTER
539         def_bool y
540         prompt "Single-depth WCHAN output"
541         depends on X86
542         ---help---
543           Calculate simpler /proc/<PID>/wchan values. If this option
544           is disabled then wchan values will recurse back to the
545           caller function. This provides more accurate wchan values,
546           at the expense of slightly more scheduling overhead.
547 
548           If in doubt, say "Y".
549 
550 menuconfig HYPERVISOR_GUEST
551         bool "Linux guest support"
552         ---help---
553           Say Y here to enable options for running Linux under various hyper-
554           visors. This option enables basic hypervisor detection and platform
555           setup.
556 
557           If you say N, all options in this submenu will be skipped and
558           disabled, and Linux guest support won't be built in.
559 
560 if HYPERVISOR_GUEST
561 
562 config PARAVIRT
563         bool "Enable paravirtualization code"
564         ---help---
565           This changes the kernel so it can modify itself when it is run
566           under a hypervisor, potentially improving performance significantly
567           over full virtualization.  However, when run without a hypervisor
568           the kernel is theoretically slower and slightly larger.
569 
570 config PARAVIRT_DEBUG
571         bool "paravirt-ops debugging"
572         depends on PARAVIRT && DEBUG_KERNEL
573         ---help---
574           Enable to debug paravirt_ops internals.  Specifically, BUG if
575           a paravirt_op is missing when it is called.
576 
577 config PARAVIRT_SPINLOCKS
578         bool "Paravirtualization layer for spinlocks"
579         depends on PARAVIRT && SMP
580         select UNINLINE_SPIN_UNLOCK
581         ---help---
582           Paravirtualized spinlocks allow a pvops backend to replace the
583           spinlock implementation with something virtualization-friendly
584           (for example, block the virtual CPU rather than spinning).
585 
586           It has a minimal impact on native kernels and gives a nice performance
587           benefit on paravirtualized KVM / Xen kernels.
588 
589           If you are unsure how to answer this question, answer Y.
590 
591 source "arch/x86/xen/Kconfig"
592 
593 config KVM_GUEST
594         bool "KVM Guest support (including kvmclock)"
595         depends on PARAVIRT
596         select PARAVIRT_CLOCK
597         default y
598         ---help---
599           This option enables various optimizations for running under the KVM
600           hypervisor. It includes a paravirtualized clock, so that instead
601           of relying on a PIT (or probably other) emulation by the
602           underlying device model, the host provides the guest with
603           timing infrastructure such as time of day, and system time
604 
605 config KVM_DEBUG_FS
606         bool "Enable debug information for KVM Guests in debugfs"
607         depends on KVM_GUEST && DEBUG_FS
608         default n
609         ---help---
610           This option enables collection of various statistics for KVM guest.
611           Statistics are displayed in debugfs filesystem. Enabling this option
612           may incur significant overhead.
613 
614 source "arch/x86/lguest/Kconfig"
615 
616 config PARAVIRT_TIME_ACCOUNTING
617         bool "Paravirtual steal time accounting"
618         depends on PARAVIRT
619         default n
620         ---help---
621           Select this option to enable fine granularity task steal time
622           accounting. Time spent executing other tasks in parallel with
623           the current vCPU is discounted from the vCPU power. To account for
624           that, there can be a small performance impact.
625 
626           If in doubt, say N here.
627 
628 config PARAVIRT_CLOCK
629         bool
630 
631 endif #HYPERVISOR_GUEST
632 
633 config NO_BOOTMEM
634         def_bool y
635 
636 config MEMTEST
637         bool "Memtest"
638         ---help---
639           This option adds a kernel parameter 'memtest', which allows memtest
640           to be set.
641                 memtest=0, mean disabled; -- default
642                 memtest=1, mean do 1 test pattern;
643                 ...
644                 memtest=4, mean do 4 test patterns.
645           If you are unsure how to answer this question, answer N.
646 
647 source "arch/x86/Kconfig.cpu"
648 
649 config HPET_TIMER
650         def_bool X86_64
651         prompt "HPET Timer Support" if X86_32
652         ---help---
653           Use the IA-PC HPET (High Precision Event Timer) to manage
654           time in preference to the PIT and RTC, if a HPET is
655           present.
656           HPET is the next generation timer replacing legacy 8254s.
657           The HPET provides a stable time base on SMP
658           systems, unlike the TSC, but it is more expensive to access,
659           as it is off-chip.  You can find the HPET spec at
660           <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
661 
662           You can safely choose Y here.  However, HPET will only be
663           activated if the platform and the BIOS support this feature.
664           Otherwise the 8254 will be used for timing services.
665 
666           Choose N to continue using the legacy 8254 timer.
667 
668 config HPET_EMULATE_RTC
669         def_bool y
670         depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
671 
672 config APB_TIMER
673        def_bool y if X86_INTEL_MID
674        prompt "Intel MID APB Timer Support" if X86_INTEL_MID
675        select DW_APB_TIMER
676        depends on X86_INTEL_MID && SFI
677        help
678          APB timer is the replacement for 8254, HPET on X86 MID platforms.
679          The APBT provides a stable time base on SMP
680          systems, unlike the TSC, but it is more expensive to access,
681          as it is off-chip. APB timers are always running regardless of CPU
682          C states, they are used as per CPU clockevent device when possible.
683 
684 # Mark as expert because too many people got it wrong.
685 # The code disables itself when not needed.
686 config DMI
687         default y
688         select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
689         bool "Enable DMI scanning" if EXPERT
690         ---help---
691           Enabled scanning of DMI to identify machine quirks. Say Y
692           here unless you have verified that your setup is not
693           affected by entries in the DMI blacklist. Required by PNP
694           BIOS code.
695 
696 config GART_IOMMU
697         bool "Old AMD GART IOMMU support"
698         select SWIOTLB
699         depends on X86_64 && PCI && AMD_NB
700         ---help---
701           Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
702           GART based hardware IOMMUs.
703 
704           The GART supports full DMA access for devices with 32-bit access
705           limitations, on systems with more than 3 GB. This is usually needed
706           for USB, sound, many IDE/SATA chipsets and some other devices.
707 
708           Newer systems typically have a modern AMD IOMMU, supported via
709           the CONFIG_AMD_IOMMU=y config option.
710 
711           In normal configurations this driver is only active when needed:
712           there's more than 3 GB of memory and the system contains a
713           32-bit limited device.
714 
715           If unsure, say Y.
716 
717 config CALGARY_IOMMU
718         bool "IBM Calgary IOMMU support"
719         select SWIOTLB
720         depends on X86_64 && PCI
721         ---help---
722           Support for hardware IOMMUs in IBM's xSeries x366 and x460
723           systems. Needed to run systems with more than 3GB of memory
724           properly with 32-bit PCI devices that do not support DAC
725           (Double Address Cycle). Calgary also supports bus level
726           isolation, where all DMAs pass through the IOMMU.  This
727           prevents them from going anywhere except their intended
728           destination. This catches hard-to-find kernel bugs and
729           mis-behaving drivers and devices that do not use the DMA-API
730           properly to set up their DMA buffers.  The IOMMU can be
731           turned off at boot time with the iommu=off parameter.
732           Normally the kernel will make the right choice by itself.
733           If unsure, say Y.
734 
735 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
736         def_bool y
737         prompt "Should Calgary be enabled by default?"
738         depends on CALGARY_IOMMU
739         ---help---
740           Should Calgary be enabled by default? if you choose 'y', Calgary
741           will be used (if it exists). If you choose 'n', Calgary will not be
742           used even if it exists. If you choose 'n' and would like to use
743           Calgary anyway, pass 'iommu=calgary' on the kernel command line.
744           If unsure, say Y.
745 
746 # need this always selected by IOMMU for the VIA workaround
747 config SWIOTLB
748         def_bool y if X86_64
749         ---help---
750           Support for software bounce buffers used on x86-64 systems
751           which don't have a hardware IOMMU. Using this PCI devices
752           which can only access 32-bits of memory can be used on systems
753           with more than 3 GB of memory.
754           If unsure, say Y.
755 
756 config IOMMU_HELPER
757         def_bool y
758         depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
759 
760 config MAXSMP
761         bool "Enable Maximum number of SMP Processors and NUMA Nodes"
762         depends on X86_64 && SMP && DEBUG_KERNEL
763         select CPUMASK_OFFSTACK
764         ---help---
765           Enable maximum number of CPUS and NUMA Nodes for this architecture.
766           If unsure, say N.
767 
768 config NR_CPUS
769         int "Maximum number of CPUs" if SMP && !MAXSMP
770         range 2 8 if SMP && X86_32 && !X86_BIGSMP
771         range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
772         range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
773         default "1" if !SMP
774         default "8192" if MAXSMP
775         default "32" if SMP && X86_BIGSMP
776         default "8" if SMP
777         ---help---
778           This allows you to specify the maximum number of CPUs which this
779           kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
780           supported value is 4096, otherwise the maximum value is 512.  The
781           minimum value which makes sense is 2.
782 
783           This is purely to save memory - each supported CPU adds
784           approximately eight kilobytes to the kernel image.
785 
786 config SCHED_SMT
787         bool "SMT (Hyperthreading) scheduler support"
788         depends on X86_HT
789         ---help---
790           SMT scheduler support improves the CPU scheduler's decision making
791           when dealing with Intel Pentium 4 chips with HyperThreading at a
792           cost of slightly increased overhead in some places. If unsure say
793           N here.
794 
795 config SCHED_MC
796         def_bool y
797         prompt "Multi-core scheduler support"
798         depends on X86_HT
799         ---help---
800           Multi-core scheduler support improves the CPU scheduler's decision
801           making when dealing with multi-core CPU chips at a cost of slightly
802           increased overhead in some places. If unsure say N here.
803 
804 source "kernel/Kconfig.preempt"
805 
806 config X86_UP_APIC
807         bool "Local APIC support on uniprocessors"
808         depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI
809         ---help---
810           A local APIC (Advanced Programmable Interrupt Controller) is an
811           integrated interrupt controller in the CPU. If you have a single-CPU
812           system which has a processor with a local APIC, you can say Y here to
813           enable and use it. If you say Y here even though your machine doesn't
814           have a local APIC, then the kernel will still run with no slowdown at
815           all. The local APIC supports CPU-generated self-interrupts (timer,
816           performance counters), and the NMI watchdog which detects hard
817           lockups.
818 
819 config X86_UP_IOAPIC
820         bool "IO-APIC support on uniprocessors"
821         depends on X86_UP_APIC
822         ---help---
823           An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
824           SMP-capable replacement for PC-style interrupt controllers. Most
825           SMP systems and many recent uniprocessor systems have one.
826 
827           If you have a single-CPU system with an IO-APIC, you can say Y here
828           to use it. If you say Y here even though your machine doesn't have
829           an IO-APIC, then the kernel will still run with no slowdown at all.
830 
831 config X86_LOCAL_APIC
832         def_bool y
833         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
834 
835 config X86_IO_APIC
836         def_bool y
837         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC || PCI_MSI
838         select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
839 
840 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
841         bool "Reroute for broken boot IRQs"
842         depends on X86_IO_APIC
843         ---help---
844           This option enables a workaround that fixes a source of
845           spurious interrupts. This is recommended when threaded
846           interrupt handling is used on systems where the generation of
847           superfluous "boot interrupts" cannot be disabled.
848 
849           Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
850           entry in the chipset's IO-APIC is masked (as, e.g. the RT
851           kernel does during interrupt handling). On chipsets where this
852           boot IRQ generation cannot be disabled, this workaround keeps
853           the original IRQ line masked so that only the equivalent "boot
854           IRQ" is delivered to the CPUs. The workaround also tells the
855           kernel to set up the IRQ handler on the boot IRQ line. In this
856           way only one interrupt is delivered to the kernel. Otherwise
857           the spurious second interrupt may cause the kernel to bring
858           down (vital) interrupt lines.
859 
860           Only affects "broken" chipsets. Interrupt sharing may be
861           increased on these systems.
862 
863 config X86_MCE
864         bool "Machine Check / overheating reporting"
865         default y
866         ---help---
867           Machine Check support allows the processor to notify the
868           kernel if it detects a problem (e.g. overheating, data corruption).
869           The action the kernel takes depends on the severity of the problem,
870           ranging from warning messages to halting the machine.
871 
872 config X86_MCE_INTEL
873         def_bool y
874         prompt "Intel MCE features"
875         depends on X86_MCE && X86_LOCAL_APIC
876         ---help---
877            Additional support for intel specific MCE features such as
878            the thermal monitor.
879 
880 config X86_MCE_AMD
881         def_bool y
882         prompt "AMD MCE features"
883         depends on X86_MCE && X86_LOCAL_APIC
884         ---help---
885            Additional support for AMD specific MCE features such as
886            the DRAM Error Threshold.
887 
888 config X86_ANCIENT_MCE
889         bool "Support for old Pentium 5 / WinChip machine checks"
890         depends on X86_32 && X86_MCE
891         ---help---
892           Include support for machine check handling on old Pentium 5 or WinChip
893           systems. These typically need to be enabled explicitly on the command
894           line.
895 
896 config X86_MCE_THRESHOLD
897         depends on X86_MCE_AMD || X86_MCE_INTEL
898         def_bool y
899 
900 config X86_MCE_INJECT
901         depends on X86_MCE
902         tristate "Machine check injector support"
903         ---help---
904           Provide support for injecting machine checks for testing purposes.
905           If you don't know what a machine check is and you don't do kernel
906           QA it is safe to say n.
907 
908 config X86_THERMAL_VECTOR
909         def_bool y
910         depends on X86_MCE_INTEL
911 
912 config VM86
913         bool "Enable VM86 support" if EXPERT
914         default y
915         depends on X86_32
916         ---help---
917           This option is required by programs like DOSEMU to run
918           16-bit real mode legacy code on x86 processors. It also may
919           be needed by software like XFree86 to initialize some video
920           cards via BIOS. Disabling this option saves about 6K.
921 
922 config X86_16BIT
923         bool "Enable support for 16-bit segments" if EXPERT
924         default y
925         ---help---
926           This option is required by programs like Wine to run 16-bit
927           protected mode legacy code on x86 processors.  Disabling
928           this option saves about 300 bytes on i386, or around 6K text
929           plus 16K runtime memory on x86-64,
930 
931 config X86_ESPFIX32
932         def_bool y
933         depends on X86_16BIT && X86_32
934 
935 config X86_ESPFIX64
936         def_bool y
937         depends on X86_16BIT && X86_64
938 
939 config TOSHIBA
940         tristate "Toshiba Laptop support"
941         depends on X86_32
942         ---help---
943           This adds a driver to safely access the System Management Mode of
944           the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
945           not work on models with a Phoenix BIOS. The System Management Mode
946           is used to set the BIOS and power saving options on Toshiba portables.
947 
948           For information on utilities to make use of this driver see the
949           Toshiba Linux utilities web site at:
950           <http://www.buzzard.org.uk/toshiba/>.
951 
952           Say Y if you intend to run this kernel on a Toshiba portable.
953           Say N otherwise.
954 
955 config I8K
956         tristate "Dell laptop support"
957         select HWMON
958         ---help---
959           This adds a driver to safely access the System Management Mode
960           of the CPU on the Dell Inspiron 8000. The System Management Mode
961           is used to read cpu temperature and cooling fan status and to
962           control the fans on the I8K portables.
963 
964           This driver has been tested only on the Inspiron 8000 but it may
965           also work with other Dell laptops. You can force loading on other
966           models by passing the parameter `force=1' to the module. Use at
967           your own risk.
968 
969           For information on utilities to make use of this driver see the
970           I8K Linux utilities web site at:
971           <http://people.debian.org/~dz/i8k/>
972 
973           Say Y if you intend to run this kernel on a Dell Inspiron 8000.
974           Say N otherwise.
975 
976 config X86_REBOOTFIXUPS
977         bool "Enable X86 board specific fixups for reboot"
978         depends on X86_32
979         ---help---
980           This enables chipset and/or board specific fixups to be done
981           in order to get reboot to work correctly. This is only needed on
982           some combinations of hardware and BIOS. The symptom, for which
983           this config is intended, is when reboot ends with a stalled/hung
984           system.
985 
986           Currently, the only fixup is for the Geode machines using
987           CS5530A and CS5536 chipsets and the RDC R-321x SoC.
988 
989           Say Y if you want to enable the fixup. Currently, it's safe to
990           enable this option even if you don't need it.
991           Say N otherwise.
992 
993 config MICROCODE
994         tristate "CPU microcode loading support"
995         depends on CPU_SUP_AMD || CPU_SUP_INTEL
996         select FW_LOADER
997         ---help---
998 
999           If you say Y here, you will be able to update the microcode on
1000           certain Intel and AMD processors. The Intel support is for the
1001           IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1002           Xeon etc. The AMD support is for families 0x10 and later. You will
1003           obviously need the actual microcode binary data itself which is not
1004           shipped with the Linux kernel.
1005 
1006           This option selects the general module only, you need to select
1007           at least one vendor specific module as well.
1008 
1009           To compile this driver as a module, choose M here: the module
1010           will be called microcode.
1011 
1012 config MICROCODE_INTEL
1013         bool "Intel microcode loading support"
1014         depends on MICROCODE
1015         default MICROCODE
1016         select FW_LOADER
1017         ---help---
1018           This options enables microcode patch loading support for Intel
1019           processors.
1020 
1021           For the current Intel microcode data package go to
1022           <https://downloadcenter.intel.com> and search for
1023           'Linux Processor Microcode Data File'.
1024 
1025 config MICROCODE_AMD
1026         bool "AMD microcode loading support"
1027         depends on MICROCODE
1028         select FW_LOADER
1029         ---help---
1030           If you select this option, microcode patch loading support for AMD
1031           processors will be enabled.
1032 
1033 config MICROCODE_OLD_INTERFACE
1034         def_bool y
1035         depends on MICROCODE
1036 
1037 config MICROCODE_INTEL_EARLY
1038         def_bool n
1039 
1040 config MICROCODE_AMD_EARLY
1041         def_bool n
1042 
1043 config MICROCODE_EARLY
1044         bool "Early load microcode"
1045         depends on MICROCODE=y && BLK_DEV_INITRD
1046         select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1047         select MICROCODE_AMD_EARLY if MICROCODE_AMD
1048         default y
1049         help
1050           This option provides functionality to read additional microcode data
1051           at the beginning of initrd image. The data tells kernel to load
1052           microcode to CPU's as early as possible. No functional change if no
1053           microcode data is glued to the initrd, therefore it's safe to say Y.
1054 
1055 config X86_MSR
1056         tristate "/dev/cpu/*/msr - Model-specific register support"
1057         ---help---
1058           This device gives privileged processes access to the x86
1059           Model-Specific Registers (MSRs).  It is a character device with
1060           major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1061           MSR accesses are directed to a specific CPU on multi-processor
1062           systems.
1063 
1064 config X86_CPUID
1065         tristate "/dev/cpu/*/cpuid - CPU information support"
1066         ---help---
1067           This device gives processes access to the x86 CPUID instruction to
1068           be executed on a specific processor.  It is a character device
1069           with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1070           /dev/cpu/31/cpuid.
1071 
1072 choice
1073         prompt "High Memory Support"
1074         default HIGHMEM4G
1075         depends on X86_32
1076 
1077 config NOHIGHMEM
1078         bool "off"
1079         ---help---
1080           Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1081           However, the address space of 32-bit x86 processors is only 4
1082           Gigabytes large. That means that, if you have a large amount of
1083           physical memory, not all of it can be "permanently mapped" by the
1084           kernel. The physical memory that's not permanently mapped is called
1085           "high memory".
1086 
1087           If you are compiling a kernel which will never run on a machine with
1088           more than 1 Gigabyte total physical RAM, answer "off" here (default
1089           choice and suitable for most users). This will result in a "3GB/1GB"
1090           split: 3GB are mapped so that each process sees a 3GB virtual memory
1091           space and the remaining part of the 4GB virtual memory space is used
1092           by the kernel to permanently map as much physical memory as
1093           possible.
1094 
1095           If the machine has between 1 and 4 Gigabytes physical RAM, then
1096           answer "4GB" here.
1097 
1098           If more than 4 Gigabytes is used then answer "64GB" here. This
1099           selection turns Intel PAE (Physical Address Extension) mode on.
1100           PAE implements 3-level paging on IA32 processors. PAE is fully
1101           supported by Linux, PAE mode is implemented on all recent Intel
1102           processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1103           then the kernel will not boot on CPUs that don't support PAE!
1104 
1105           The actual amount of total physical memory will either be
1106           auto detected or can be forced by using a kernel command line option
1107           such as "mem=256M". (Try "man bootparam" or see the documentation of
1108           your boot loader (lilo or loadlin) about how to pass options to the
1109           kernel at boot time.)
1110 
1111           If unsure, say "off".
1112 
1113 config HIGHMEM4G
1114         bool "4GB"
1115         ---help---
1116           Select this if you have a 32-bit processor and between 1 and 4
1117           gigabytes of physical RAM.
1118 
1119 config HIGHMEM64G
1120         bool "64GB"
1121         depends on !M486
1122         select X86_PAE
1123         ---help---
1124           Select this if you have a 32-bit processor and more than 4
1125           gigabytes of physical RAM.
1126 
1127 endchoice
1128 
1129 choice
1130         prompt "Memory split" if EXPERT
1131         default VMSPLIT_3G
1132         depends on X86_32
1133         ---help---
1134           Select the desired split between kernel and user memory.
1135 
1136           If the address range available to the kernel is less than the
1137           physical memory installed, the remaining memory will be available
1138           as "high memory". Accessing high memory is a little more costly
1139           than low memory, as it needs to be mapped into the kernel first.
1140           Note that increasing the kernel address space limits the range
1141           available to user programs, making the address space there
1142           tighter.  Selecting anything other than the default 3G/1G split
1143           will also likely make your kernel incompatible with binary-only
1144           kernel modules.
1145 
1146           If you are not absolutely sure what you are doing, leave this
1147           option alone!
1148 
1149         config VMSPLIT_3G
1150                 bool "3G/1G user/kernel split"
1151         config VMSPLIT_3G_OPT
1152                 depends on !X86_PAE
1153                 bool "3G/1G user/kernel split (for full 1G low memory)"
1154         config VMSPLIT_2G
1155                 bool "2G/2G user/kernel split"
1156         config VMSPLIT_2G_OPT
1157                 depends on !X86_PAE
1158                 bool "2G/2G user/kernel split (for full 2G low memory)"
1159         config VMSPLIT_1G
1160                 bool "1G/3G user/kernel split"
1161 endchoice
1162 
1163 config PAGE_OFFSET
1164         hex
1165         default 0xB0000000 if VMSPLIT_3G_OPT
1166         default 0x80000000 if VMSPLIT_2G
1167         default 0x78000000 if VMSPLIT_2G_OPT
1168         default 0x40000000 if VMSPLIT_1G
1169         default 0xC0000000
1170         depends on X86_32
1171 
1172 config HIGHMEM
1173         def_bool y
1174         depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1175 
1176 config X86_PAE
1177         bool "PAE (Physical Address Extension) Support"
1178         depends on X86_32 && !HIGHMEM4G
1179         ---help---
1180           PAE is required for NX support, and furthermore enables
1181           larger swapspace support for non-overcommit purposes. It
1182           has the cost of more pagetable lookup overhead, and also
1183           consumes more pagetable space per process.
1184 
1185 config ARCH_PHYS_ADDR_T_64BIT
1186         def_bool y
1187         depends on X86_64 || X86_PAE
1188 
1189 config ARCH_DMA_ADDR_T_64BIT
1190         def_bool y
1191         depends on X86_64 || HIGHMEM64G
1192 
1193 config DIRECT_GBPAGES
1194         bool "Enable 1GB pages for kernel pagetables" if EXPERT
1195         default y
1196         depends on X86_64
1197         ---help---
1198           Allow the kernel linear mapping to use 1GB pages on CPUs that
1199           support it. This can improve the kernel's performance a tiny bit by
1200           reducing TLB pressure. If in doubt, say "Y".
1201 
1202 # Common NUMA Features
1203 config NUMA
1204         bool "Numa Memory Allocation and Scheduler Support"
1205         depends on SMP
1206         depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1207         default y if X86_BIGSMP
1208         ---help---
1209           Enable NUMA (Non Uniform Memory Access) support.
1210 
1211           The kernel will try to allocate memory used by a CPU on the
1212           local memory controller of the CPU and add some more
1213           NUMA awareness to the kernel.
1214 
1215           For 64-bit this is recommended if the system is Intel Core i7
1216           (or later), AMD Opteron, or EM64T NUMA.
1217 
1218           For 32-bit this is only needed if you boot a 32-bit
1219           kernel on a 64-bit NUMA platform.
1220 
1221           Otherwise, you should say N.
1222 
1223 config AMD_NUMA
1224         def_bool y
1225         prompt "Old style AMD Opteron NUMA detection"
1226         depends on X86_64 && NUMA && PCI
1227         ---help---
1228           Enable AMD NUMA node topology detection.  You should say Y here if
1229           you have a multi processor AMD system. This uses an old method to
1230           read the NUMA configuration directly from the builtin Northbridge
1231           of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1232           which also takes priority if both are compiled in.
1233 
1234 config X86_64_ACPI_NUMA
1235         def_bool y
1236         prompt "ACPI NUMA detection"
1237         depends on X86_64 && NUMA && ACPI && PCI
1238         select ACPI_NUMA
1239         ---help---
1240           Enable ACPI SRAT based node topology detection.
1241 
1242 # Some NUMA nodes have memory ranges that span
1243 # other nodes.  Even though a pfn is valid and
1244 # between a node's start and end pfns, it may not
1245 # reside on that node.  See memmap_init_zone()
1246 # for details.
1247 config NODES_SPAN_OTHER_NODES
1248         def_bool y
1249         depends on X86_64_ACPI_NUMA
1250 
1251 config NUMA_EMU
1252         bool "NUMA emulation"
1253         depends on NUMA
1254         ---help---
1255           Enable NUMA emulation. A flat machine will be split
1256           into virtual nodes when booted with "numa=fake=N", where N is the
1257           number of nodes. This is only useful for debugging.
1258 
1259 config NODES_SHIFT
1260         int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1261         range 1 10
1262         default "10" if MAXSMP
1263         default "6" if X86_64
1264         default "3"
1265         depends on NEED_MULTIPLE_NODES
1266         ---help---
1267           Specify the maximum number of NUMA Nodes available on the target
1268           system.  Increases memory reserved to accommodate various tables.
1269 
1270 config ARCH_HAVE_MEMORY_PRESENT
1271         def_bool y
1272         depends on X86_32 && DISCONTIGMEM
1273 
1274 config NEED_NODE_MEMMAP_SIZE
1275         def_bool y
1276         depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1277 
1278 config ARCH_FLATMEM_ENABLE
1279         def_bool y
1280         depends on X86_32 && !NUMA
1281 
1282 config ARCH_DISCONTIGMEM_ENABLE
1283         def_bool y
1284         depends on NUMA && X86_32
1285 
1286 config ARCH_DISCONTIGMEM_DEFAULT
1287         def_bool y
1288         depends on NUMA && X86_32
1289 
1290 config ARCH_SPARSEMEM_ENABLE
1291         def_bool y
1292         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1293         select SPARSEMEM_STATIC if X86_32
1294         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1295 
1296 config ARCH_SPARSEMEM_DEFAULT
1297         def_bool y
1298         depends on X86_64
1299 
1300 config ARCH_SELECT_MEMORY_MODEL
1301         def_bool y
1302         depends on ARCH_SPARSEMEM_ENABLE
1303 
1304 config ARCH_MEMORY_PROBE
1305         bool "Enable sysfs memory/probe interface"
1306         depends on X86_64 && MEMORY_HOTPLUG
1307         help
1308           This option enables a sysfs memory/probe interface for testing.
1309           See Documentation/memory-hotplug.txt for more information.
1310           If you are unsure how to answer this question, answer N.
1311 
1312 config ARCH_PROC_KCORE_TEXT
1313         def_bool y
1314         depends on X86_64 && PROC_KCORE
1315 
1316 config ILLEGAL_POINTER_VALUE
1317        hex
1318        default 0 if X86_32
1319        default 0xdead000000000000 if X86_64
1320 
1321 source "mm/Kconfig"
1322 
1323 config HIGHPTE
1324         bool "Allocate 3rd-level pagetables from highmem"
1325         depends on HIGHMEM
1326         ---help---
1327           The VM uses one page table entry for each page of physical memory.
1328           For systems with a lot of RAM, this can be wasteful of precious
1329           low memory.  Setting this option will put user-space page table
1330           entries in high memory.
1331 
1332 config X86_CHECK_BIOS_CORRUPTION
1333         bool "Check for low memory corruption"
1334         ---help---
1335           Periodically check for memory corruption in low memory, which
1336           is suspected to be caused by BIOS.  Even when enabled in the
1337           configuration, it is disabled at runtime.  Enable it by
1338           setting "memory_corruption_check=1" on the kernel command
1339           line.  By default it scans the low 64k of memory every 60
1340           seconds; see the memory_corruption_check_size and
1341           memory_corruption_check_period parameters in
1342           Documentation/kernel-parameters.txt to adjust this.
1343 
1344           When enabled with the default parameters, this option has
1345           almost no overhead, as it reserves a relatively small amount
1346           of memory and scans it infrequently.  It both detects corruption
1347           and prevents it from affecting the running system.
1348 
1349           It is, however, intended as a diagnostic tool; if repeatable
1350           BIOS-originated corruption always affects the same memory,
1351           you can use memmap= to prevent the kernel from using that
1352           memory.
1353 
1354 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1355         bool "Set the default setting of memory_corruption_check"
1356         depends on X86_CHECK_BIOS_CORRUPTION
1357         default y
1358         ---help---
1359           Set whether the default state of memory_corruption_check is
1360           on or off.
1361 
1362 config X86_RESERVE_LOW
1363         int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1364         default 64
1365         range 4 640
1366         ---help---
1367           Specify the amount of low memory to reserve for the BIOS.
1368 
1369           The first page contains BIOS data structures that the kernel
1370           must not use, so that page must always be reserved.
1371 
1372           By default we reserve the first 64K of physical RAM, as a
1373           number of BIOSes are known to corrupt that memory range
1374           during events such as suspend/resume or monitor cable
1375           insertion, so it must not be used by the kernel.
1376 
1377           You can set this to 4 if you are absolutely sure that you
1378           trust the BIOS to get all its memory reservations and usages
1379           right.  If you know your BIOS have problems beyond the
1380           default 64K area, you can set this to 640 to avoid using the
1381           entire low memory range.
1382 
1383           If you have doubts about the BIOS (e.g. suspend/resume does
1384           not work or there's kernel crashes after certain hardware
1385           hotplug events) then you might want to enable
1386           X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1387           typical corruption patterns.
1388 
1389           Leave this to the default value of 64 if you are unsure.
1390 
1391 config MATH_EMULATION
1392         bool
1393         prompt "Math emulation" if X86_32
1394         ---help---
1395           Linux can emulate a math coprocessor (used for floating point
1396           operations) if you don't have one. 486DX and Pentium processors have
1397           a math coprocessor built in, 486SX and 386 do not, unless you added
1398           a 487DX or 387, respectively. (The messages during boot time can
1399           give you some hints here ["man dmesg"].) Everyone needs either a
1400           coprocessor or this emulation.
1401 
1402           If you don't have a math coprocessor, you need to say Y here; if you
1403           say Y here even though you have a coprocessor, the coprocessor will
1404           be used nevertheless. (This behavior can be changed with the kernel
1405           command line option "no387", which comes handy if your coprocessor
1406           is broken. Try "man bootparam" or see the documentation of your boot
1407           loader (lilo or loadlin) about how to pass options to the kernel at
1408           boot time.) This means that it is a good idea to say Y here if you
1409           intend to use this kernel on different machines.
1410 
1411           More information about the internals of the Linux math coprocessor
1412           emulation can be found in <file:arch/x86/math-emu/README>.
1413 
1414           If you are not sure, say Y; apart from resulting in a 66 KB bigger
1415           kernel, it won't hurt.
1416 
1417 config MTRR
1418         def_bool y
1419         prompt "MTRR (Memory Type Range Register) support" if EXPERT
1420         ---help---
1421           On Intel P6 family processors (Pentium Pro, Pentium II and later)
1422           the Memory Type Range Registers (MTRRs) may be used to control
1423           processor access to memory ranges. This is most useful if you have
1424           a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1425           allows bus write transfers to be combined into a larger transfer
1426           before bursting over the PCI/AGP bus. This can increase performance
1427           of image write operations 2.5 times or more. Saying Y here creates a
1428           /proc/mtrr file which may be used to manipulate your processor's
1429           MTRRs. Typically the X server should use this.
1430 
1431           This code has a reasonably generic interface so that similar
1432           control registers on other processors can be easily supported
1433           as well:
1434 
1435           The Cyrix 6x86, 6x86MX and M II processors have Address Range
1436           Registers (ARRs) which provide a similar functionality to MTRRs. For
1437           these, the ARRs are used to emulate the MTRRs.
1438           The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1439           MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1440           write-combining. All of these processors are supported by this code
1441           and it makes sense to say Y here if you have one of them.
1442 
1443           Saying Y here also fixes a problem with buggy SMP BIOSes which only
1444           set the MTRRs for the boot CPU and not for the secondary CPUs. This
1445           can lead to all sorts of problems, so it's good to say Y here.
1446 
1447           You can safely say Y even if your machine doesn't have MTRRs, you'll
1448           just add about 9 KB to your kernel.
1449 
1450           See <file:Documentation/x86/mtrr.txt> for more information.
1451 
1452 config MTRR_SANITIZER
1453         def_bool y
1454         prompt "MTRR cleanup support"
1455         depends on MTRR
1456         ---help---
1457           Convert MTRR layout from continuous to discrete, so X drivers can
1458           add writeback entries.
1459 
1460           Can be disabled with disable_mtrr_cleanup on the kernel command line.
1461           The largest mtrr entry size for a continuous block can be set with
1462           mtrr_chunk_size.
1463 
1464           If unsure, say Y.
1465 
1466 config MTRR_SANITIZER_ENABLE_DEFAULT
1467         int "MTRR cleanup enable value (0-1)"
1468         range 0 1
1469         default "0"
1470         depends on MTRR_SANITIZER
1471         ---help---
1472           Enable mtrr cleanup default value
1473 
1474 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1475         int "MTRR cleanup spare reg num (0-7)"
1476         range 0 7
1477         default "1"
1478         depends on MTRR_SANITIZER
1479         ---help---
1480           mtrr cleanup spare entries default, it can be changed via
1481           mtrr_spare_reg_nr=N on the kernel command line.
1482 
1483 config X86_PAT
1484         def_bool y
1485         prompt "x86 PAT support" if EXPERT
1486         depends on MTRR
1487         ---help---
1488           Use PAT attributes to setup page level cache control.
1489 
1490           PATs are the modern equivalents of MTRRs and are much more
1491           flexible than MTRRs.
1492 
1493           Say N here if you see bootup problems (boot crash, boot hang,
1494           spontaneous reboots) or a non-working video driver.
1495 
1496           If unsure, say Y.
1497 
1498 config ARCH_USES_PG_UNCACHED
1499         def_bool y
1500         depends on X86_PAT
1501 
1502 config ARCH_RANDOM
1503         def_bool y
1504         prompt "x86 architectural random number generator" if EXPERT
1505         ---help---
1506           Enable the x86 architectural RDRAND instruction
1507           (Intel Bull Mountain technology) to generate random numbers.
1508           If supported, this is a high bandwidth, cryptographically
1509           secure hardware random number generator.
1510 
1511 config X86_SMAP
1512         def_bool y
1513         prompt "Supervisor Mode Access Prevention" if EXPERT
1514         ---help---
1515           Supervisor Mode Access Prevention (SMAP) is a security
1516           feature in newer Intel processors.  There is a small
1517           performance cost if this enabled and turned on; there is
1518           also a small increase in the kernel size if this is enabled.
1519 
1520           If unsure, say Y.
1521 
1522 config EFI
1523         bool "EFI runtime service support"
1524         depends on ACPI
1525         select UCS2_STRING
1526         ---help---
1527           This enables the kernel to use EFI runtime services that are
1528           available (such as the EFI variable services).
1529 
1530           This option is only useful on systems that have EFI firmware.
1531           In addition, you should use the latest ELILO loader available
1532           at <http://elilo.sourceforge.net> in order to take advantage
1533           of EFI runtime services. However, even with this option, the
1534           resultant kernel should continue to boot on existing non-EFI
1535           platforms.
1536 
1537 config EFI_STUB
1538        bool "EFI stub support"
1539        depends on EFI
1540        ---help---
1541           This kernel feature allows a bzImage to be loaded directly
1542           by EFI firmware without the use of a bootloader.
1543 
1544           See Documentation/efi-stub.txt for more information.
1545 
1546 config EFI_MIXED
1547         bool "EFI mixed-mode support"
1548         depends on EFI_STUB && X86_64
1549         ---help---
1550            Enabling this feature allows a 64-bit kernel to be booted
1551            on a 32-bit firmware, provided that your CPU supports 64-bit
1552            mode.
1553 
1554            Note that it is not possible to boot a mixed-mode enabled
1555            kernel via the EFI boot stub - a bootloader that supports
1556            the EFI handover protocol must be used.
1557 
1558            If unsure, say N.
1559 
1560 config SECCOMP
1561         def_bool y
1562         prompt "Enable seccomp to safely compute untrusted bytecode"
1563         ---help---
1564           This kernel feature is useful for number crunching applications
1565           that may need to compute untrusted bytecode during their
1566           execution. By using pipes or other transports made available to
1567           the process as file descriptors supporting the read/write
1568           syscalls, it's possible to isolate those applications in
1569           their own address space using seccomp. Once seccomp is
1570           enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1571           and the task is only allowed to execute a few safe syscalls
1572           defined by each seccomp mode.
1573 
1574           If unsure, say Y. Only embedded should say N here.
1575 
1576 source kernel/Kconfig.hz
1577 
1578 config KEXEC
1579         bool "kexec system call"
1580         ---help---
1581           kexec is a system call that implements the ability to shutdown your
1582           current kernel, and to start another kernel.  It is like a reboot
1583           but it is independent of the system firmware.   And like a reboot
1584           you can start any kernel with it, not just Linux.
1585 
1586           The name comes from the similarity to the exec system call.
1587 
1588           It is an ongoing process to be certain the hardware in a machine
1589           is properly shutdown, so do not be surprised if this code does not
1590           initially work for you.  As of this writing the exact hardware
1591           interface is strongly in flux, so no good recommendation can be
1592           made.
1593 
1594 config CRASH_DUMP
1595         bool "kernel crash dumps"
1596         depends on X86_64 || (X86_32 && HIGHMEM)
1597         ---help---
1598           Generate crash dump after being started by kexec.
1599           This should be normally only set in special crash dump kernels
1600           which are loaded in the main kernel with kexec-tools into
1601           a specially reserved region and then later executed after
1602           a crash by kdump/kexec. The crash dump kernel must be compiled
1603           to a memory address not used by the main kernel or BIOS using
1604           PHYSICAL_START, or it must be built as a relocatable image
1605           (CONFIG_RELOCATABLE=y).
1606           For more details see Documentation/kdump/kdump.txt
1607 
1608 config KEXEC_JUMP
1609         bool "kexec jump"
1610         depends on KEXEC && HIBERNATION
1611         ---help---
1612           Jump between original kernel and kexeced kernel and invoke
1613           code in physical address mode via KEXEC
1614 
1615 config PHYSICAL_START
1616         hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1617         default "0x1000000"
1618         ---help---
1619           This gives the physical address where the kernel is loaded.
1620 
1621           If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1622           bzImage will decompress itself to above physical address and
1623           run from there. Otherwise, bzImage will run from the address where
1624           it has been loaded by the boot loader and will ignore above physical
1625           address.
1626 
1627           In normal kdump cases one does not have to set/change this option
1628           as now bzImage can be compiled as a completely relocatable image
1629           (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1630           address. This option is mainly useful for the folks who don't want
1631           to use a bzImage for capturing the crash dump and want to use a
1632           vmlinux instead. vmlinux is not relocatable hence a kernel needs
1633           to be specifically compiled to run from a specific memory area
1634           (normally a reserved region) and this option comes handy.
1635 
1636           So if you are using bzImage for capturing the crash dump,
1637           leave the value here unchanged to 0x1000000 and set
1638           CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
1639           for capturing the crash dump change this value to start of
1640           the reserved region.  In other words, it can be set based on
1641           the "X" value as specified in the "crashkernel=YM@XM"
1642           command line boot parameter passed to the panic-ed
1643           kernel. Please take a look at Documentation/kdump/kdump.txt
1644           for more details about crash dumps.
1645 
1646           Usage of bzImage for capturing the crash dump is recommended as
1647           one does not have to build two kernels. Same kernel can be used
1648           as production kernel and capture kernel. Above option should have
1649           gone away after relocatable bzImage support is introduced. But it
1650           is present because there are users out there who continue to use
1651           vmlinux for dump capture. This option should go away down the
1652           line.
1653 
1654           Don't change this unless you know what you are doing.
1655 
1656 config RELOCATABLE
1657         bool "Build a relocatable kernel"
1658         default y
1659         ---help---
1660           This builds a kernel image that retains relocation information
1661           so it can be loaded someplace besides the default 1MB.
1662           The relocations tend to make the kernel binary about 10% larger,
1663           but are discarded at runtime.
1664 
1665           One use is for the kexec on panic case where the recovery kernel
1666           must live at a different physical address than the primary
1667           kernel.
1668 
1669           Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1670           it has been loaded at and the compile time physical address
1671           (CONFIG_PHYSICAL_START) is used as the minimum location.
1672 
1673 config RANDOMIZE_BASE
1674         bool "Randomize the address of the kernel image"
1675         depends on RELOCATABLE
1676         default n
1677         ---help---
1678            Randomizes the physical and virtual address at which the
1679            kernel image is decompressed, as a security feature that
1680            deters exploit attempts relying on knowledge of the location
1681            of kernel internals.
1682 
1683            Entropy is generated using the RDRAND instruction if it is
1684            supported. If RDTSC is supported, it is used as well. If
1685            neither RDRAND nor RDTSC are supported, then randomness is
1686            read from the i8254 timer.
1687 
1688            The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1689            and aligned according to PHYSICAL_ALIGN. Since the kernel is
1690            built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1691            minimum of 2MiB, only 10 bits of entropy is theoretically
1692            possible. At best, due to page table layouts, 64-bit can use
1693            9 bits of entropy and 32-bit uses 8 bits.
1694 
1695            If unsure, say N.
1696 
1697 config RANDOMIZE_BASE_MAX_OFFSET
1698         hex "Maximum kASLR offset allowed" if EXPERT
1699         depends on RANDOMIZE_BASE
1700         range 0x0 0x20000000 if X86_32
1701         default "0x20000000" if X86_32
1702         range 0x0 0x40000000 if X86_64
1703         default "0x40000000" if X86_64
1704         ---help---
1705           The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1706           memory is used to determine the maximal offset in bytes that will
1707           be applied to the kernel when kernel Address Space Layout
1708           Randomization (kASLR) is active. This must be a multiple of
1709           PHYSICAL_ALIGN.
1710 
1711           On 32-bit this is limited to 512MiB by page table layouts. The
1712           default is 512MiB.
1713 
1714           On 64-bit this is limited by how the kernel fixmap page table is
1715           positioned, so this cannot be larger than 1GiB currently. Without
1716           RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1717           and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1718           modules area will shrink to compensate, up to the current maximum
1719           1GiB to 1GiB split. The default is 1GiB.
1720 
1721           If unsure, leave at the default value.
1722 
1723 # Relocation on x86 needs some additional build support
1724 config X86_NEED_RELOCS
1725         def_bool y
1726         depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1727 
1728 config PHYSICAL_ALIGN
1729         hex "Alignment value to which kernel should be aligned"
1730         default "0x200000"
1731         range 0x2000 0x1000000 if X86_32
1732         range 0x200000 0x1000000 if X86_64
1733         ---help---
1734           This value puts the alignment restrictions on physical address
1735           where kernel is loaded and run from. Kernel is compiled for an
1736           address which meets above alignment restriction.
1737 
1738           If bootloader loads the kernel at a non-aligned address and
1739           CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1740           address aligned to above value and run from there.
1741 
1742           If bootloader loads the kernel at a non-aligned address and
1743           CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1744           load address and decompress itself to the address it has been
1745           compiled for and run from there. The address for which kernel is
1746           compiled already meets above alignment restrictions. Hence the
1747           end result is that kernel runs from a physical address meeting
1748           above alignment restrictions.
1749 
1750           On 32-bit this value must be a multiple of 0x2000. On 64-bit
1751           this value must be a multiple of 0x200000.
1752 
1753           Don't change this unless you know what you are doing.
1754 
1755 config HOTPLUG_CPU
1756         bool "Support for hot-pluggable CPUs"
1757         depends on SMP
1758         ---help---
1759           Say Y here to allow turning CPUs off and on. CPUs can be
1760           controlled through /sys/devices/system/cpu.
1761           ( Note: power management support will enable this option
1762             automatically on SMP systems. )
1763           Say N if you want to disable CPU hotplug.
1764 
1765 config BOOTPARAM_HOTPLUG_CPU0
1766         bool "Set default setting of cpu0_hotpluggable"
1767         default n
1768         depends on HOTPLUG_CPU
1769         ---help---
1770           Set whether default state of cpu0_hotpluggable is on or off.
1771 
1772           Say Y here to enable CPU0 hotplug by default. If this switch
1773           is turned on, there is no need to give cpu0_hotplug kernel
1774           parameter and the CPU0 hotplug feature is enabled by default.
1775 
1776           Please note: there are two known CPU0 dependencies if you want
1777           to enable the CPU0 hotplug feature either by this switch or by
1778           cpu0_hotplug kernel parameter.
1779 
1780           First, resume from hibernate or suspend always starts from CPU0.
1781           So hibernate and suspend are prevented if CPU0 is offline.
1782 
1783           Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1784           offline if any interrupt can not migrate out of CPU0. There may
1785           be other CPU0 dependencies.
1786 
1787           Please make sure the dependencies are under your control before
1788           you enable this feature.
1789 
1790           Say N if you don't want to enable CPU0 hotplug feature by default.
1791           You still can enable the CPU0 hotplug feature at boot by kernel
1792           parameter cpu0_hotplug.
1793 
1794 config DEBUG_HOTPLUG_CPU0
1795         def_bool n
1796         prompt "Debug CPU0 hotplug"
1797         depends on HOTPLUG_CPU
1798         ---help---
1799           Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1800           soon as possible and boots up userspace with CPU0 offlined. User
1801           can online CPU0 back after boot time.
1802 
1803           To debug CPU0 hotplug, you need to enable CPU0 offline/online
1804           feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1805           compilation or giving cpu0_hotplug kernel parameter at boot.
1806 
1807           If unsure, say N.
1808 
1809 config COMPAT_VDSO
1810         def_bool n
1811         prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
1812         depends on X86_32 || IA32_EMULATION
1813         ---help---
1814           Certain buggy versions of glibc will crash if they are
1815           presented with a 32-bit vDSO that is not mapped at the address
1816           indicated in its segment table.
1817 
1818           The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
1819           and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
1820           49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
1821           the only released version with the bug, but OpenSUSE 9
1822           contains a buggy "glibc 2.3.2".
1823 
1824           The symptom of the bug is that everything crashes on startup, saying:
1825           dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
1826 
1827           Saying Y here changes the default value of the vdso32 boot
1828           option from 1 to 0, which turns off the 32-bit vDSO entirely.
1829           This works around the glibc bug but hurts performance.
1830 
1831           If unsure, say N: if you are compiling your own kernel, you
1832           are unlikely to be using a buggy version of glibc.
1833 
1834 config CMDLINE_BOOL
1835         bool "Built-in kernel command line"
1836         ---help---
1837           Allow for specifying boot arguments to the kernel at
1838           build time.  On some systems (e.g. embedded ones), it is
1839           necessary or convenient to provide some or all of the
1840           kernel boot arguments with the kernel itself (that is,
1841           to not rely on the boot loader to provide them.)
1842 
1843           To compile command line arguments into the kernel,
1844           set this option to 'Y', then fill in the
1845           the boot arguments in CONFIG_CMDLINE.
1846 
1847           Systems with fully functional boot loaders (i.e. non-embedded)
1848           should leave this option set to 'N'.
1849 
1850 config CMDLINE
1851         string "Built-in kernel command string"
1852         depends on CMDLINE_BOOL
1853         default ""
1854         ---help---
1855           Enter arguments here that should be compiled into the kernel
1856           image and used at boot time.  If the boot loader provides a
1857           command line at boot time, it is appended to this string to
1858           form the full kernel command line, when the system boots.
1859 
1860           However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1861           change this behavior.
1862 
1863           In most cases, the command line (whether built-in or provided
1864           by the boot loader) should specify the device for the root
1865           file system.
1866 
1867 config CMDLINE_OVERRIDE
1868         bool "Built-in command line overrides boot loader arguments"
1869         depends on CMDLINE_BOOL
1870         ---help---
1871           Set this option to 'Y' to have the kernel ignore the boot loader
1872           command line, and use ONLY the built-in command line.
1873 
1874           This is used to work around broken boot loaders.  This should
1875           be set to 'N' under normal conditions.
1876 
1877 endmenu
1878 
1879 config ARCH_ENABLE_MEMORY_HOTPLUG
1880         def_bool y
1881         depends on X86_64 || (X86_32 && HIGHMEM)
1882 
1883 config ARCH_ENABLE_MEMORY_HOTREMOVE
1884         def_bool y
1885         depends on MEMORY_HOTPLUG
1886 
1887 config USE_PERCPU_NUMA_NODE_ID
1888         def_bool y
1889         depends on NUMA
1890 
1891 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
1892         def_bool y
1893         depends on X86_64 || X86_PAE
1894 
1895 config ARCH_ENABLE_HUGEPAGE_MIGRATION
1896         def_bool y
1897         depends on X86_64 && HUGETLB_PAGE && MIGRATION
1898 
1899 menu "Power management and ACPI options"
1900 
1901 config ARCH_HIBERNATION_HEADER
1902         def_bool y
1903         depends on X86_64 && HIBERNATION
1904 
1905 source "kernel/power/Kconfig"
1906 
1907 source "drivers/acpi/Kconfig"
1908 
1909 source "drivers/sfi/Kconfig"
1910 
1911 config X86_APM_BOOT
1912         def_bool y
1913         depends on APM
1914 
1915 menuconfig APM
1916         tristate "APM (Advanced Power Management) BIOS support"
1917         depends on X86_32 && PM_SLEEP
1918         ---help---
1919           APM is a BIOS specification for saving power using several different
1920           techniques. This is mostly useful for battery powered laptops with
1921           APM compliant BIOSes. If you say Y here, the system time will be
1922           reset after a RESUME operation, the /proc/apm device will provide
1923           battery status information, and user-space programs will receive
1924           notification of APM "events" (e.g. battery status change).
1925 
1926           If you select "Y" here, you can disable actual use of the APM
1927           BIOS by passing the "apm=off" option to the kernel at boot time.
1928 
1929           Note that the APM support is almost completely disabled for
1930           machines with more than one CPU.
1931 
1932           In order to use APM, you will need supporting software. For location
1933           and more information, read <file:Documentation/power/apm-acpi.txt>
1934           and the Battery Powered Linux mini-HOWTO, available from
1935           <http://www.tldp.org/docs.html#howto>.
1936 
1937           This driver does not spin down disk drives (see the hdparm(8)
1938           manpage ("man 8 hdparm") for that), and it doesn't turn off
1939           VESA-compliant "green" monitors.
1940 
1941           This driver does not support the TI 4000M TravelMate and the ACER
1942           486/DX4/75 because they don't have compliant BIOSes. Many "green"
1943           desktop machines also don't have compliant BIOSes, and this driver
1944           may cause those machines to panic during the boot phase.
1945 
1946           Generally, if you don't have a battery in your machine, there isn't
1947           much point in using this driver and you should say N. If you get
1948           random kernel OOPSes or reboots that don't seem to be related to
1949           anything, try disabling/enabling this option (or disabling/enabling
1950           APM in your BIOS).
1951 
1952           Some other things you should try when experiencing seemingly random,
1953           "weird" problems:
1954 
1955           1) make sure that you have enough swap space and that it is
1956           enabled.
1957           2) pass the "no-hlt" option to the kernel
1958           3) switch on floating point emulation in the kernel and pass
1959           the "no387" option to the kernel
1960           4) pass the "floppy=nodma" option to the kernel
1961           5) pass the "mem=4M" option to the kernel (thereby disabling
1962           all but the first 4 MB of RAM)
1963           6) make sure that the CPU is not over clocked.
1964           7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1965           8) disable the cache from your BIOS settings
1966           9) install a fan for the video card or exchange video RAM
1967           10) install a better fan for the CPU
1968           11) exchange RAM chips
1969           12) exchange the motherboard.
1970 
1971           To compile this driver as a module, choose M here: the
1972           module will be called apm.
1973 
1974 if APM
1975 
1976 config APM_IGNORE_USER_SUSPEND
1977         bool "Ignore USER SUSPEND"
1978         ---help---
1979           This option will ignore USER SUSPEND requests. On machines with a
1980           compliant APM BIOS, you want to say N. However, on the NEC Versa M
1981           series notebooks, it is necessary to say Y because of a BIOS bug.
1982 
1983 config APM_DO_ENABLE
1984         bool "Enable PM at boot time"
1985         ---help---
1986           Enable APM features at boot time. From page 36 of the APM BIOS
1987           specification: "When disabled, the APM BIOS does not automatically
1988           power manage devices, enter the Standby State, enter the Suspend
1989           State, or take power saving steps in response to CPU Idle calls."
1990           This driver will make CPU Idle calls when Linux is idle (unless this
1991           feature is turned off -- see "Do CPU IDLE calls", below). This
1992           should always save battery power, but more complicated APM features
1993           will be dependent on your BIOS implementation. You may need to turn
1994           this option off if your computer hangs at boot time when using APM
1995           support, or if it beeps continuously instead of suspending. Turn
1996           this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1997           T400CDT. This is off by default since most machines do fine without
1998           this feature.
1999 
2000 config APM_CPU_IDLE
2001         depends on CPU_IDLE
2002         bool "Make CPU Idle calls when idle"
2003         ---help---
2004           Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2005           On some machines, this can activate improved power savings, such as
2006           a slowed CPU clock rate, when the machine is idle. These idle calls
2007           are made after the idle loop has run for some length of time (e.g.,
2008           333 mS). On some machines, this will cause a hang at boot time or
2009           whenever the CPU becomes idle. (On machines with more than one CPU,
2010           this option does nothing.)
2011 
2012 config APM_DISPLAY_BLANK
2013         bool "Enable console blanking using APM"
2014         ---help---
2015           Enable console blanking using the APM. Some laptops can use this to
2016           turn off the LCD backlight when the screen blanker of the Linux
2017           virtual console blanks the screen. Note that this is only used by
2018           the virtual console screen blanker, and won't turn off the backlight
2019           when using the X Window system. This also doesn't have anything to
2020           do with your VESA-compliant power-saving monitor. Further, this
2021           option doesn't work for all laptops -- it might not turn off your
2022           backlight at all, or it might print a lot of errors to the console,
2023           especially if you are using gpm.
2024 
2025 config APM_ALLOW_INTS
2026         bool "Allow interrupts during APM BIOS calls"
2027         ---help---
2028           Normally we disable external interrupts while we are making calls to
2029           the APM BIOS as a measure to lessen the effects of a badly behaving
2030           BIOS implementation.  The BIOS should reenable interrupts if it
2031           needs to.  Unfortunately, some BIOSes do not -- especially those in
2032           many of the newer IBM Thinkpads.  If you experience hangs when you
2033           suspend, try setting this to Y.  Otherwise, say N.
2034 
2035 endif # APM
2036 
2037 source "drivers/cpufreq/Kconfig"
2038 
2039 source "drivers/cpuidle/Kconfig"
2040 
2041 source "drivers/idle/Kconfig"
2042 
2043 endmenu
2044 
2045 
2046 menu "Bus options (PCI etc.)"
2047 
2048 config PCI
2049         bool "PCI support"
2050         default y
2051         ---help---
2052           Find out whether you have a PCI motherboard. PCI is the name of a
2053           bus system, i.e. the way the CPU talks to the other stuff inside
2054           your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2055           VESA. If you have PCI, say Y, otherwise N.
2056 
2057 choice
2058         prompt "PCI access mode"
2059         depends on X86_32 && PCI
2060         default PCI_GOANY
2061         ---help---
2062           On PCI systems, the BIOS can be used to detect the PCI devices and
2063           determine their configuration. However, some old PCI motherboards
2064           have BIOS bugs and may crash if this is done. Also, some embedded
2065           PCI-based systems don't have any BIOS at all. Linux can also try to
2066           detect the PCI hardware directly without using the BIOS.
2067 
2068           With this option, you can specify how Linux should detect the
2069           PCI devices. If you choose "BIOS", the BIOS will be used,
2070           if you choose "Direct", the BIOS won't be used, and if you
2071           choose "MMConfig", then PCI Express MMCONFIG will be used.
2072           If you choose "Any", the kernel will try MMCONFIG, then the
2073           direct access method and falls back to the BIOS if that doesn't
2074           work. If unsure, go with the default, which is "Any".
2075 
2076 config PCI_GOBIOS
2077         bool "BIOS"
2078 
2079 config PCI_GOMMCONFIG
2080         bool "MMConfig"
2081 
2082 config PCI_GODIRECT
2083         bool "Direct"
2084 
2085 config PCI_GOOLPC
2086         bool "OLPC XO-1"
2087         depends on OLPC
2088 
2089 config PCI_GOANY
2090         bool "Any"
2091 
2092 endchoice
2093 
2094 config PCI_BIOS
2095         def_bool y
2096         depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2097 
2098 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2099 config PCI_DIRECT
2100         def_bool y
2101         depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2102 
2103 config PCI_MMCONFIG
2104         def_bool y
2105         depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2106 
2107 config PCI_OLPC
2108         def_bool y
2109         depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2110 
2111 config PCI_XEN
2112         def_bool y
2113         depends on PCI && XEN
2114         select SWIOTLB_XEN
2115 
2116 config PCI_DOMAINS
2117         def_bool y
2118         depends on PCI
2119 
2120 config PCI_MMCONFIG
2121         bool "Support mmconfig PCI config space access"
2122         depends on X86_64 && PCI && ACPI
2123 
2124 config PCI_CNB20LE_QUIRK
2125         bool "Read CNB20LE Host Bridge Windows" if EXPERT
2126         depends on PCI
2127         help
2128           Read the PCI windows out of the CNB20LE host bridge. This allows
2129           PCI hotplug to work on systems with the CNB20LE chipset which do
2130           not have ACPI.
2131 
2132           There's no public spec for this chipset, and this functionality
2133           is known to be incomplete.
2134 
2135           You should say N unless you know you need this.
2136 
2137 source "drivers/pci/pcie/Kconfig"
2138 
2139 source "drivers/pci/Kconfig"
2140 
2141 # x86_64 have no ISA slots, but can have ISA-style DMA.
2142 config ISA_DMA_API
2143         bool "ISA-style DMA support" if (X86_64 && EXPERT)
2144         default y
2145         help
2146           Enables ISA-style DMA support for devices requiring such controllers.
2147           If unsure, say Y.
2148 
2149 if X86_32
2150 
2151 config ISA
2152         bool "ISA support"
2153         ---help---
2154           Find out whether you have ISA slots on your motherboard.  ISA is the
2155           name of a bus system, i.e. the way the CPU talks to the other stuff
2156           inside your box.  Other bus systems are PCI, EISA, MicroChannel
2157           (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2158           newer boards don't support it.  If you have ISA, say Y, otherwise N.
2159 
2160 config EISA
2161         bool "EISA support"
2162         depends on ISA
2163         ---help---
2164           The Extended Industry Standard Architecture (EISA) bus was
2165           developed as an open alternative to the IBM MicroChannel bus.
2166 
2167           The EISA bus provided some of the features of the IBM MicroChannel
2168           bus while maintaining backward compatibility with cards made for
2169           the older ISA bus.  The EISA bus saw limited use between 1988 and
2170           1995 when it was made obsolete by the PCI bus.
2171 
2172           Say Y here if you are building a kernel for an EISA-based machine.
2173 
2174           Otherwise, say N.
2175 
2176 source "drivers/eisa/Kconfig"
2177 
2178 config SCx200
2179         tristate "NatSemi SCx200 support"
2180         ---help---
2181           This provides basic support for National Semiconductor's
2182           (now AMD's) Geode processors.  The driver probes for the
2183           PCI-IDs of several on-chip devices, so its a good dependency
2184           for other scx200_* drivers.
2185 
2186           If compiled as a module, the driver is named scx200.
2187 
2188 config SCx200HR_TIMER
2189         tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2190         depends on SCx200
2191         default y
2192         ---help---
2193           This driver provides a clocksource built upon the on-chip
2194           27MHz high-resolution timer.  Its also a workaround for
2195           NSC Geode SC-1100's buggy TSC, which loses time when the
2196           processor goes idle (as is done by the scheduler).  The
2197           other workaround is idle=poll boot option.
2198 
2199 config OLPC
2200         bool "One Laptop Per Child support"
2201         depends on !X86_PAE
2202         select GPIOLIB
2203         select OF
2204         select OF_PROMTREE
2205         select IRQ_DOMAIN
2206         ---help---
2207           Add support for detecting the unique features of the OLPC
2208           XO hardware.
2209 
2210 config OLPC_XO1_PM
2211         bool "OLPC XO-1 Power Management"
2212         depends on OLPC && MFD_CS5535 && PM_SLEEP
2213         select MFD_CORE
2214         ---help---
2215           Add support for poweroff and suspend of the OLPC XO-1 laptop.
2216 
2217 config OLPC_XO1_RTC
2218         bool "OLPC XO-1 Real Time Clock"
2219         depends on OLPC_XO1_PM && RTC_DRV_CMOS
2220         ---help---
2221           Add support for the XO-1 real time clock, which can be used as a
2222           programmable wakeup source.
2223 
2224 config OLPC_XO1_SCI
2225         bool "OLPC XO-1 SCI extras"
2226         depends on OLPC && OLPC_XO1_PM
2227         depends on INPUT=y
2228         select POWER_SUPPLY
2229         select GPIO_CS5535
2230         select MFD_CORE
2231         ---help---
2232           Add support for SCI-based features of the OLPC XO-1 laptop:
2233            - EC-driven system wakeups
2234            - Power button
2235            - Ebook switch
2236            - Lid switch
2237            - AC adapter status updates
2238            - Battery status updates
2239 
2240 config OLPC_XO15_SCI
2241         bool "OLPC XO-1.5 SCI extras"
2242         depends on OLPC && ACPI
2243         select POWER_SUPPLY
2244         ---help---
2245           Add support for SCI-based features of the OLPC XO-1.5 laptop:
2246            - EC-driven system wakeups
2247            - AC adapter status updates
2248            - Battery status updates
2249 
2250 config ALIX
2251         bool "PCEngines ALIX System Support (LED setup)"
2252         select GPIOLIB
2253         ---help---
2254           This option enables system support for the PCEngines ALIX.
2255           At present this just sets up LEDs for GPIO control on
2256           ALIX2/3/6 boards.  However, other system specific setup should
2257           get added here.
2258 
2259           Note: You must still enable the drivers for GPIO and LED support
2260           (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2261 
2262           Note: You have to set alix.force=1 for boards with Award BIOS.
2263 
2264 config NET5501
2265         bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2266         select GPIOLIB
2267         ---help---
2268           This option enables system support for the Soekris Engineering net5501.
2269 
2270 config GEOS
2271         bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2272         select GPIOLIB
2273         depends on DMI
2274         ---help---
2275           This option enables system support for the Traverse Technologies GEOS.
2276 
2277 config TS5500
2278         bool "Technologic Systems TS-5500 platform support"
2279         depends on MELAN
2280         select CHECK_SIGNATURE
2281         select NEW_LEDS
2282         select LEDS_CLASS
2283         ---help---
2284           This option enables system support for the Technologic Systems TS-5500.
2285 
2286 endif # X86_32
2287 
2288 config AMD_NB
2289         def_bool y
2290         depends on CPU_SUP_AMD && PCI
2291 
2292 source "drivers/pcmcia/Kconfig"
2293 
2294 source "drivers/pci/hotplug/Kconfig"
2295 
2296 config RAPIDIO
2297         tristate "RapidIO support"
2298         depends on PCI
2299         default n
2300         help
2301           If enabled this option will include drivers and the core
2302           infrastructure code to support RapidIO interconnect devices.
2303 
2304 source "drivers/rapidio/Kconfig"
2305 
2306 config X86_SYSFB
2307         bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2308         help
2309           Firmwares often provide initial graphics framebuffers so the BIOS,
2310           bootloader or kernel can show basic video-output during boot for
2311           user-guidance and debugging. Historically, x86 used the VESA BIOS
2312           Extensions and EFI-framebuffers for this, which are mostly limited
2313           to x86.
2314           This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2315           framebuffers so the new generic system-framebuffer drivers can be
2316           used on x86. If the framebuffer is not compatible with the generic
2317           modes, it is adverticed as fallback platform framebuffer so legacy
2318           drivers like efifb, vesafb and uvesafb can pick it up.
2319           If this option is not selected, all system framebuffers are always
2320           marked as fallback platform framebuffers as usual.
2321 
2322           Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2323           not be able to pick up generic system framebuffers if this option
2324           is selected. You are highly encouraged to enable simplefb as
2325           replacement if you select this option. simplefb can correctly deal
2326           with generic system framebuffers. But you should still keep vesafb
2327           and others enabled as fallback if a system framebuffer is
2328           incompatible with simplefb.
2329 
2330           If unsure, say Y.
2331 
2332 endmenu
2333 
2334 
2335 menu "Executable file formats / Emulations"
2336 
2337 source "fs/Kconfig.binfmt"
2338 
2339 config IA32_EMULATION
2340         bool "IA32 Emulation"
2341         depends on X86_64
2342         select BINFMT_ELF
2343         select COMPAT_BINFMT_ELF
2344         select HAVE_UID16
2345         ---help---
2346           Include code to run legacy 32-bit programs under a
2347           64-bit kernel. You should likely turn this on, unless you're
2348           100% sure that you don't have any 32-bit programs left.
2349 
2350 config IA32_AOUT
2351         tristate "IA32 a.out support"
2352         depends on IA32_EMULATION
2353         ---help---
2354           Support old a.out binaries in the 32bit emulation.
2355 
2356 config X86_X32
2357         bool "x32 ABI for 64-bit mode"
2358         depends on X86_64 && IA32_EMULATION
2359         ---help---
2360           Include code to run binaries for the x32 native 32-bit ABI
2361           for 64-bit processors.  An x32 process gets access to the
2362           full 64-bit register file and wide data path while leaving
2363           pointers at 32 bits for smaller memory footprint.
2364 
2365           You will need a recent binutils (2.22 or later) with
2366           elf32_x86_64 support enabled to compile a kernel with this
2367           option set.
2368 
2369 config COMPAT
2370         def_bool y
2371         depends on IA32_EMULATION || X86_X32
2372         select ARCH_WANT_OLD_COMPAT_IPC
2373 
2374 if COMPAT
2375 config COMPAT_FOR_U64_ALIGNMENT
2376         def_bool y
2377 
2378 config SYSVIPC_COMPAT
2379         def_bool y
2380         depends on SYSVIPC
2381 
2382 config KEYS_COMPAT
2383         def_bool y
2384         depends on KEYS
2385 endif
2386 
2387 endmenu
2388 
2389 
2390 config HAVE_ATOMIC_IOMAP
2391         def_bool y
2392         depends on X86_32
2393 
2394 config X86_DEV_DMA_OPS
2395         bool
2396         depends on X86_64 || STA2X11
2397 
2398 config X86_DMA_REMAP
2399         bool
2400         depends on STA2X11
2401 
2402 config IOSF_MBI
2403         tristate
2404         default m
2405         depends on PCI
2406 
2407 source "net/Kconfig"
2408 
2409 source "drivers/Kconfig"
2410 
2411 source "drivers/firmware/Kconfig"
2412 
2413 source "fs/Kconfig"
2414 
2415 source "arch/x86/Kconfig.debug"
2416 
2417 source "security/Kconfig"
2418 
2419 source "crypto/Kconfig"
2420 
2421 source "arch/x86/kvm/Kconfig"
2422 
2423 source "lib/Kconfig"

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