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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_MIGHT_HAVE_ACPI_PDC if ACPI
 25         select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
 26         select ARCH_HAS_FAST_MULTIPLIER
 27         select ARCH_MIGHT_HAVE_PC_PARPORT
 28         select ARCH_MIGHT_HAVE_PC_SERIO
 29         select HAVE_AOUT if X86_32
 30         select HAVE_UNSTABLE_SCHED_CLOCK
 31         select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
 32         select ARCH_SUPPORTS_INT128 if X86_64
 33         select HAVE_IDE
 34         select HAVE_OPROFILE
 35         select HAVE_PCSPKR_PLATFORM
 36         select HAVE_PERF_EVENTS
 37         select HAVE_IOREMAP_PROT
 38         select HAVE_KPROBES
 39         select HAVE_MEMBLOCK
 40         select HAVE_MEMBLOCK_NODE_MAP
 41         select ARCH_DISCARD_MEMBLOCK
 42         select ARCH_WANT_OPTIONAL_GPIOLIB
 43         select ARCH_WANT_FRAME_POINTERS
 44         select HAVE_DMA_ATTRS
 45         select HAVE_DMA_CONTIGUOUS
 46         select HAVE_KRETPROBES
 47         select GENERIC_EARLY_IOREMAP
 48         select HAVE_OPTPROBES
 49         select HAVE_KPROBES_ON_FTRACE
 50         select HAVE_FTRACE_MCOUNT_RECORD
 51         select HAVE_FENTRY if X86_64
 52         select HAVE_C_RECORDMCOUNT
 53         select HAVE_DYNAMIC_FTRACE
 54         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 55         select HAVE_FUNCTION_TRACER
 56         select HAVE_FUNCTION_GRAPH_TRACER
 57         select HAVE_FUNCTION_GRAPH_FP_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 ARCH_HAS_SG_CHAIN
100         select CLKEVT_I8253
101         select ARCH_HAVE_NMI_SAFE_CMPXCHG
102         select GENERIC_IOMAP
103         select DCACHE_WORD_ACCESS
104         select GENERIC_SMP_IDLE_THREAD
105         select ARCH_WANT_IPC_PARSE_VERSION if X86_32
106         select HAVE_ARCH_SECCOMP_FILTER
107         select BUILDTIME_EXTABLE_SORT
108         select GENERIC_CMOS_UPDATE
109         select HAVE_ARCH_SOFT_DIRTY if X86_64
110         select CLOCKSOURCE_WATCHDOG
111         select GENERIC_CLOCKEVENTS
112         select ARCH_CLOCKSOURCE_DATA
113         select CLOCKSOURCE_VALIDATE_LAST_CYCLE
114         select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
115         select GENERIC_TIME_VSYSCALL
116         select GENERIC_STRNCPY_FROM_USER
117         select GENERIC_STRNLEN_USER
118         select HAVE_CONTEXT_TRACKING if X86_64
119         select HAVE_IRQ_TIME_ACCOUNTING
120         select VIRT_TO_BUS
121         select MODULES_USE_ELF_REL if X86_32
122         select MODULES_USE_ELF_RELA if X86_64
123         select CLONE_BACKWARDS if X86_32
124         select ARCH_USE_BUILTIN_BSWAP
125         select ARCH_USE_QUEUE_RWLOCK
126         select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
127         select OLD_SIGACTION if X86_32
128         select COMPAT_OLD_SIGACTION if IA32_EMULATION
129         select RTC_LIB
130         select HAVE_DEBUG_STACKOVERFLOW
131         select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
132         select HAVE_CC_STACKPROTECTOR
133         select GENERIC_CPU_AUTOPROBE
134         select HAVE_ARCH_AUDITSYSCALL
135         select ARCH_SUPPORTS_ATOMIC_RMW
136         select HAVE_ACPI_APEI if ACPI
137         select HAVE_ACPI_APEI_NMI if ACPI
138         select ACPI_LEGACY_TABLES_LOOKUP if ACPI
139         select X86_FEATURE_NAMES if PROC_FS
140 
141 config INSTRUCTION_DECODER
142         def_bool y
143         depends on KPROBES || PERF_EVENTS || UPROBES
144 
145 config PERF_EVENTS_INTEL_UNCORE
146         def_bool y
147         depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
148 
149 config OUTPUT_FORMAT
150         string
151         default "elf32-i386" if X86_32
152         default "elf64-x86-64" if X86_64
153 
154 config ARCH_DEFCONFIG
155         string
156         default "arch/x86/configs/i386_defconfig" if X86_32
157         default "arch/x86/configs/x86_64_defconfig" if X86_64
158 
159 config LOCKDEP_SUPPORT
160         def_bool y
161 
162 config STACKTRACE_SUPPORT
163         def_bool y
164 
165 config HAVE_LATENCYTOP_SUPPORT
166         def_bool y
167 
168 config MMU
169         def_bool y
170 
171 config SBUS
172         bool
173 
174 config NEED_DMA_MAP_STATE
175         def_bool y
176         depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
177 
178 config NEED_SG_DMA_LENGTH
179         def_bool y
180 
181 config GENERIC_ISA_DMA
182         def_bool y
183         depends on ISA_DMA_API
184 
185 config GENERIC_BUG
186         def_bool y
187         depends on BUG
188         select GENERIC_BUG_RELATIVE_POINTERS if X86_64
189 
190 config GENERIC_BUG_RELATIVE_POINTERS
191         bool
192 
193 config GENERIC_HWEIGHT
194         def_bool y
195 
196 config ARCH_MAY_HAVE_PC_FDC
197         def_bool y
198         depends on ISA_DMA_API
199 
200 config RWSEM_XCHGADD_ALGORITHM
201         def_bool y
202 
203 config GENERIC_CALIBRATE_DELAY
204         def_bool y
205 
206 config ARCH_HAS_CPU_RELAX
207         def_bool y
208 
209 config ARCH_HAS_CACHE_LINE_SIZE
210         def_bool y
211 
212 config HAVE_SETUP_PER_CPU_AREA
213         def_bool y
214 
215 config NEED_PER_CPU_EMBED_FIRST_CHUNK
216         def_bool y
217 
218 config NEED_PER_CPU_PAGE_FIRST_CHUNK
219         def_bool y
220 
221 config ARCH_HIBERNATION_POSSIBLE
222         def_bool y
223 
224 config ARCH_SUSPEND_POSSIBLE
225         def_bool y
226 
227 config ARCH_WANT_HUGE_PMD_SHARE
228         def_bool y
229 
230 config ARCH_WANT_GENERAL_HUGETLB
231         def_bool y
232 
233 config ZONE_DMA32
234         bool
235         default X86_64
236 
237 config AUDIT_ARCH
238         bool
239         default X86_64
240 
241 config ARCH_SUPPORTS_OPTIMIZED_INLINING
242         def_bool y
243 
244 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
245         def_bool y
246 
247 config HAVE_INTEL_TXT
248         def_bool y
249         depends on INTEL_IOMMU && ACPI
250 
251 config X86_32_SMP
252         def_bool y
253         depends on X86_32 && SMP
254 
255 config X86_64_SMP
256         def_bool y
257         depends on X86_64 && SMP
258 
259 config X86_HT
260         def_bool y
261         depends on SMP
262 
263 config X86_32_LAZY_GS
264         def_bool y
265         depends on X86_32 && !CC_STACKPROTECTOR
266 
267 config ARCH_HWEIGHT_CFLAGS
268         string
269         default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
270         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
271 
272 config ARCH_SUPPORTS_UPROBES
273         def_bool y
274 
275 config FIX_EARLYCON_MEM
276         def_bool y
277 
278 source "init/Kconfig"
279 source "kernel/Kconfig.freezer"
280 
281 menu "Processor type and features"
282 
283 config ZONE_DMA
284         bool "DMA memory allocation support" if EXPERT
285         default y
286         help
287           DMA memory allocation support allows devices with less than 32-bit
288           addressing to allocate within the first 16MB of address space.
289           Disable if no such devices will be used.
290 
291           If unsure, say Y.
292 
293 config SMP
294         bool "Symmetric multi-processing support"
295         ---help---
296           This enables support for systems with more than one CPU. If you have
297           a system with only one CPU, say N. If you have a system with more
298           than one CPU, say Y.
299 
300           If you say N here, the kernel will run on uni- and multiprocessor
301           machines, but will use only one CPU of a multiprocessor machine. If
302           you say Y here, the kernel will run on many, but not all,
303           uniprocessor machines. On a uniprocessor machine, the kernel
304           will run faster if you say N here.
305 
306           Note that if you say Y here and choose architecture "586" or
307           "Pentium" under "Processor family", the kernel will not work on 486
308           architectures. Similarly, multiprocessor kernels for the "PPro"
309           architecture may not work on all Pentium based boards.
310 
311           People using multiprocessor machines who say Y here should also say
312           Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
313           Management" code will be disabled if you say Y here.
314 
315           See also <file:Documentation/x86/i386/IO-APIC.txt>,
316           <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
317           <http://www.tldp.org/docs.html#howto>.
318 
319           If you don't know what to do here, say N.
320 
321 config X86_FEATURE_NAMES
322         bool "Processor feature human-readable names" if EMBEDDED
323         default y
324         ---help---
325           This option compiles in a table of x86 feature bits and corresponding
326           names.  This is required to support /proc/cpuinfo and a few kernel
327           messages.  You can disable this to save space, at the expense of
328           making those few kernel messages show numeric feature bits instead.
329 
330           If in doubt, say Y.
331 
332 config X86_X2APIC
333         bool "Support x2apic"
334         depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
335         ---help---
336           This enables x2apic support on CPUs that have this feature.
337 
338           This allows 32-bit apic IDs (so it can support very large systems),
339           and accesses the local apic via MSRs not via mmio.
340 
341           If you don't know what to do here, say N.
342 
343 config X86_MPPARSE
344         bool "Enable MPS table" if ACPI || SFI
345         default y
346         depends on X86_LOCAL_APIC
347         ---help---
348           For old smp systems that do not have proper acpi support. Newer systems
349           (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
350 
351 config X86_BIGSMP
352         bool "Support for big SMP systems with more than 8 CPUs"
353         depends on X86_32 && SMP
354         ---help---
355           This option is needed for the systems that have more than 8 CPUs
356 
357 config GOLDFISH
358        def_bool y
359        depends on X86_GOLDFISH
360 
361 if X86_32
362 config X86_EXTENDED_PLATFORM
363         bool "Support for extended (non-PC) x86 platforms"
364         default y
365         ---help---
366           If you disable this option then the kernel will only support
367           standard PC platforms. (which covers the vast majority of
368           systems out there.)
369 
370           If you enable this option then you'll be able to select support
371           for the following (non-PC) 32 bit x86 platforms:
372                 Goldfish (Android emulator)
373                 AMD Elan
374                 RDC R-321x SoC
375                 SGI 320/540 (Visual Workstation)
376                 STA2X11-based (e.g. Northville)
377                 Moorestown MID devices
378 
379           If you have one of these systems, or if you want to build a
380           generic distribution kernel, say Y here - otherwise say N.
381 endif
382 
383 if X86_64
384 config X86_EXTENDED_PLATFORM
385         bool "Support for extended (non-PC) x86 platforms"
386         default y
387         ---help---
388           If you disable this option then the kernel will only support
389           standard PC platforms. (which covers the vast majority of
390           systems out there.)
391 
392           If you enable this option then you'll be able to select support
393           for the following (non-PC) 64 bit x86 platforms:
394                 Numascale NumaChip
395                 ScaleMP vSMP
396                 SGI Ultraviolet
397 
398           If you have one of these systems, or if you want to build a
399           generic distribution kernel, say Y here - otherwise say N.
400 endif
401 # This is an alphabetically sorted list of 64 bit extended platforms
402 # Please maintain the alphabetic order if and when there are additions
403 config X86_NUMACHIP
404         bool "Numascale NumaChip"
405         depends on X86_64
406         depends on X86_EXTENDED_PLATFORM
407         depends on NUMA
408         depends on SMP
409         depends on X86_X2APIC
410         depends on PCI_MMCONFIG
411         ---help---
412           Adds support for Numascale NumaChip large-SMP systems. Needed to
413           enable more than ~168 cores.
414           If you don't have one of these, you should say N here.
415 
416 config X86_VSMP
417         bool "ScaleMP vSMP"
418         select HYPERVISOR_GUEST
419         select PARAVIRT
420         depends on X86_64 && PCI
421         depends on X86_EXTENDED_PLATFORM
422         depends on SMP
423         ---help---
424           Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
425           supposed to run on these EM64T-based machines.  Only choose this option
426           if you have one of these machines.
427 
428 config X86_UV
429         bool "SGI Ultraviolet"
430         depends on X86_64
431         depends on X86_EXTENDED_PLATFORM
432         depends on NUMA
433         depends on X86_X2APIC
434         ---help---
435           This option is needed in order to support SGI Ultraviolet systems.
436           If you don't have one of these, you should say N here.
437 
438 # Following is an alphabetically sorted list of 32 bit extended platforms
439 # Please maintain the alphabetic order if and when there are additions
440 
441 config X86_GOLDFISH
442        bool "Goldfish (Virtual Platform)"
443        depends on X86_EXTENDED_PLATFORM
444        ---help---
445          Enable support for the Goldfish virtual platform used primarily
446          for Android development. Unless you are building for the Android
447          Goldfish emulator say N here.
448 
449 config X86_INTEL_CE
450         bool "CE4100 TV platform"
451         depends on PCI
452         depends on PCI_GODIRECT
453         depends on X86_IO_APIC
454         depends on X86_32
455         depends on X86_EXTENDED_PLATFORM
456         select X86_REBOOTFIXUPS
457         select OF
458         select OF_EARLY_FLATTREE
459         select IRQ_DOMAIN
460         ---help---
461           Select for the Intel CE media processor (CE4100) SOC.
462           This option compiles in support for the CE4100 SOC for settop
463           boxes and media devices.
464 
465 config X86_INTEL_MID
466         bool "Intel MID platform support"
467         depends on X86_32
468         depends on X86_EXTENDED_PLATFORM
469         depends on X86_PLATFORM_DEVICES
470         depends on PCI
471         depends on PCI_GOANY
472         depends on X86_IO_APIC
473         select SFI
474         select I2C
475         select DW_APB_TIMER
476         select APB_TIMER
477         select INTEL_SCU_IPC
478         select MFD_INTEL_MSIC
479         ---help---
480           Select to build a kernel capable of supporting Intel MID (Mobile
481           Internet Device) platform systems which do not have the PCI legacy
482           interfaces. If you are building for a PC class system say N here.
483 
484           Intel MID platforms are based on an Intel processor and chipset which
485           consume less power than most of the x86 derivatives.
486 
487 config X86_INTEL_LPSS
488         bool "Intel Low Power Subsystem Support"
489         depends on ACPI
490         select COMMON_CLK
491         select PINCTRL
492         ---help---
493           Select to build support for Intel Low Power Subsystem such as
494           found on Intel Lynxpoint PCH. Selecting this option enables
495           things like clock tree (common clock framework) and pincontrol
496           which are needed by the LPSS peripheral drivers.
497 
498 config IOSF_MBI
499         tristate "Intel SoC IOSF Sideband support for SoC platforms"
500         depends on PCI
501         ---help---
502           This option enables sideband register access support for Intel SoC
503           platforms. On these platforms the IOSF sideband is used in lieu of
504           MSR's for some register accesses, mostly but not limited to thermal
505           and power. Drivers may query the availability of this device to
506           determine if they need the sideband in order to work on these
507           platforms. The sideband is available on the following SoC products.
508           This list is not meant to be exclusive.
509            - BayTrail
510            - Braswell
511            - Quark
512 
513           You should say Y if you are running a kernel on one of these SoC's.
514 
515 config IOSF_MBI_DEBUG
516         bool "Enable IOSF sideband access through debugfs"
517         depends on IOSF_MBI && DEBUG_FS
518         ---help---
519           Select this option to expose the IOSF sideband access registers (MCR,
520           MDR, MCRX) through debugfs to write and read register information from
521           different units on the SoC. This is most useful for obtaining device
522           state information for debug and analysis. As this is a general access
523           mechanism, users of this option would have specific knowledge of the
524           device they want to access.
525 
526           If you don't require the option or are in doubt, say N.
527 
528 config X86_RDC321X
529         bool "RDC R-321x SoC"
530         depends on X86_32
531         depends on X86_EXTENDED_PLATFORM
532         select M486
533         select X86_REBOOTFIXUPS
534         ---help---
535           This option is needed for RDC R-321x system-on-chip, also known
536           as R-8610-(G).
537           If you don't have one of these chips, you should say N here.
538 
539 config X86_32_NON_STANDARD
540         bool "Support non-standard 32-bit SMP architectures"
541         depends on X86_32 && SMP
542         depends on X86_EXTENDED_PLATFORM
543         ---help---
544           This option compiles in the bigsmp and STA2X11 default
545           subarchitectures.  It is intended for a generic binary
546           kernel. If you select them all, kernel will probe it one by
547           one and will fallback to default.
548 
549 # Alphabetically sorted list of Non standard 32 bit platforms
550 
551 config X86_SUPPORTS_MEMORY_FAILURE
552         def_bool y
553         # MCE code calls memory_failure():
554         depends on X86_MCE
555         # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
556         # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
557         depends on X86_64 || !SPARSEMEM
558         select ARCH_SUPPORTS_MEMORY_FAILURE
559 
560 config STA2X11
561         bool "STA2X11 Companion Chip Support"
562         depends on X86_32_NON_STANDARD && PCI
563         select X86_DEV_DMA_OPS
564         select X86_DMA_REMAP
565         select SWIOTLB
566         select MFD_STA2X11
567         select ARCH_REQUIRE_GPIOLIB
568         default n
569         ---help---
570           This adds support for boards based on the STA2X11 IO-Hub,
571           a.k.a. "ConneXt". The chip is used in place of the standard
572           PC chipset, so all "standard" peripherals are missing. If this
573           option is selected the kernel will still be able to boot on
574           standard PC machines.
575 
576 config X86_32_IRIS
577         tristate "Eurobraille/Iris poweroff module"
578         depends on X86_32
579         ---help---
580           The Iris machines from EuroBraille do not have APM or ACPI support
581           to shut themselves down properly.  A special I/O sequence is
582           needed to do so, which is what this module does at
583           kernel shutdown.
584 
585           This is only for Iris machines from EuroBraille.
586 
587           If unused, say N.
588 
589 config SCHED_OMIT_FRAME_POINTER
590         def_bool y
591         prompt "Single-depth WCHAN output"
592         depends on X86
593         ---help---
594           Calculate simpler /proc/<PID>/wchan values. If this option
595           is disabled then wchan values will recurse back to the
596           caller function. This provides more accurate wchan values,
597           at the expense of slightly more scheduling overhead.
598 
599           If in doubt, say "Y".
600 
601 menuconfig HYPERVISOR_GUEST
602         bool "Linux guest support"
603         ---help---
604           Say Y here to enable options for running Linux under various hyper-
605           visors. This option enables basic hypervisor detection and platform
606           setup.
607 
608           If you say N, all options in this submenu will be skipped and
609           disabled, and Linux guest support won't be built in.
610 
611 if HYPERVISOR_GUEST
612 
613 config PARAVIRT
614         bool "Enable paravirtualization code"
615         ---help---
616           This changes the kernel so it can modify itself when it is run
617           under a hypervisor, potentially improving performance significantly
618           over full virtualization.  However, when run without a hypervisor
619           the kernel is theoretically slower and slightly larger.
620 
621 config PARAVIRT_DEBUG
622         bool "paravirt-ops debugging"
623         depends on PARAVIRT && DEBUG_KERNEL
624         ---help---
625           Enable to debug paravirt_ops internals.  Specifically, BUG if
626           a paravirt_op is missing when it is called.
627 
628 config PARAVIRT_SPINLOCKS
629         bool "Paravirtualization layer for spinlocks"
630         depends on PARAVIRT && SMP
631         select UNINLINE_SPIN_UNLOCK
632         ---help---
633           Paravirtualized spinlocks allow a pvops backend to replace the
634           spinlock implementation with something virtualization-friendly
635           (for example, block the virtual CPU rather than spinning).
636 
637           It has a minimal impact on native kernels and gives a nice performance
638           benefit on paravirtualized KVM / Xen kernels.
639 
640           If you are unsure how to answer this question, answer Y.
641 
642 source "arch/x86/xen/Kconfig"
643 
644 config KVM_GUEST
645         bool "KVM Guest support (including kvmclock)"
646         depends on PARAVIRT
647         select PARAVIRT_CLOCK
648         default y
649         ---help---
650           This option enables various optimizations for running under the KVM
651           hypervisor. It includes a paravirtualized clock, so that instead
652           of relying on a PIT (or probably other) emulation by the
653           underlying device model, the host provides the guest with
654           timing infrastructure such as time of day, and system time
655 
656 config KVM_DEBUG_FS
657         bool "Enable debug information for KVM Guests in debugfs"
658         depends on KVM_GUEST && DEBUG_FS
659         default n
660         ---help---
661           This option enables collection of various statistics for KVM guest.
662           Statistics are displayed in debugfs filesystem. Enabling this option
663           may incur significant overhead.
664 
665 source "arch/x86/lguest/Kconfig"
666 
667 config PARAVIRT_TIME_ACCOUNTING
668         bool "Paravirtual steal time accounting"
669         depends on PARAVIRT
670         default n
671         ---help---
672           Select this option to enable fine granularity task steal time
673           accounting. Time spent executing other tasks in parallel with
674           the current vCPU is discounted from the vCPU power. To account for
675           that, there can be a small performance impact.
676 
677           If in doubt, say N here.
678 
679 config PARAVIRT_CLOCK
680         bool
681 
682 endif #HYPERVISOR_GUEST
683 
684 config NO_BOOTMEM
685         def_bool y
686 
687 config MEMTEST
688         bool "Memtest"
689         ---help---
690           This option adds a kernel parameter 'memtest', which allows memtest
691           to be set.
692                 memtest=0, mean disabled; -- default
693                 memtest=1, mean do 1 test pattern;
694                 ...
695                 memtest=4, mean do 4 test patterns.
696           If you are unsure how to answer this question, answer N.
697 
698 source "arch/x86/Kconfig.cpu"
699 
700 config HPET_TIMER
701         def_bool X86_64
702         prompt "HPET Timer Support" if X86_32
703         ---help---
704           Use the IA-PC HPET (High Precision Event Timer) to manage
705           time in preference to the PIT and RTC, if a HPET is
706           present.
707           HPET is the next generation timer replacing legacy 8254s.
708           The HPET provides a stable time base on SMP
709           systems, unlike the TSC, but it is more expensive to access,
710           as it is off-chip.  You can find the HPET spec at
711           <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
712 
713           You can safely choose Y here.  However, HPET will only be
714           activated if the platform and the BIOS support this feature.
715           Otherwise the 8254 will be used for timing services.
716 
717           Choose N to continue using the legacy 8254 timer.
718 
719 config HPET_EMULATE_RTC
720         def_bool y
721         depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
722 
723 config APB_TIMER
724        def_bool y if X86_INTEL_MID
725        prompt "Intel MID APB Timer Support" if X86_INTEL_MID
726        select DW_APB_TIMER
727        depends on X86_INTEL_MID && SFI
728        help
729          APB timer is the replacement for 8254, HPET on X86 MID platforms.
730          The APBT provides a stable time base on SMP
731          systems, unlike the TSC, but it is more expensive to access,
732          as it is off-chip. APB timers are always running regardless of CPU
733          C states, they are used as per CPU clockevent device when possible.
734 
735 # Mark as expert because too many people got it wrong.
736 # The code disables itself when not needed.
737 config DMI
738         default y
739         select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
740         bool "Enable DMI scanning" if EXPERT
741         ---help---
742           Enabled scanning of DMI to identify machine quirks. Say Y
743           here unless you have verified that your setup is not
744           affected by entries in the DMI blacklist. Required by PNP
745           BIOS code.
746 
747 config GART_IOMMU
748         bool "Old AMD GART IOMMU support"
749         select SWIOTLB
750         depends on X86_64 && PCI && AMD_NB
751         ---help---
752           Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
753           GART based hardware IOMMUs.
754 
755           The GART supports full DMA access for devices with 32-bit access
756           limitations, on systems with more than 3 GB. This is usually needed
757           for USB, sound, many IDE/SATA chipsets and some other devices.
758 
759           Newer systems typically have a modern AMD IOMMU, supported via
760           the CONFIG_AMD_IOMMU=y config option.
761 
762           In normal configurations this driver is only active when needed:
763           there's more than 3 GB of memory and the system contains a
764           32-bit limited device.
765 
766           If unsure, say Y.
767 
768 config CALGARY_IOMMU
769         bool "IBM Calgary IOMMU support"
770         select SWIOTLB
771         depends on X86_64 && PCI
772         ---help---
773           Support for hardware IOMMUs in IBM's xSeries x366 and x460
774           systems. Needed to run systems with more than 3GB of memory
775           properly with 32-bit PCI devices that do not support DAC
776           (Double Address Cycle). Calgary also supports bus level
777           isolation, where all DMAs pass through the IOMMU.  This
778           prevents them from going anywhere except their intended
779           destination. This catches hard-to-find kernel bugs and
780           mis-behaving drivers and devices that do not use the DMA-API
781           properly to set up their DMA buffers.  The IOMMU can be
782           turned off at boot time with the iommu=off parameter.
783           Normally the kernel will make the right choice by itself.
784           If unsure, say Y.
785 
786 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
787         def_bool y
788         prompt "Should Calgary be enabled by default?"
789         depends on CALGARY_IOMMU
790         ---help---
791           Should Calgary be enabled by default? if you choose 'y', Calgary
792           will be used (if it exists). If you choose 'n', Calgary will not be
793           used even if it exists. If you choose 'n' and would like to use
794           Calgary anyway, pass 'iommu=calgary' on the kernel command line.
795           If unsure, say Y.
796 
797 # need this always selected by IOMMU for the VIA workaround
798 config SWIOTLB
799         def_bool y if X86_64
800         ---help---
801           Support for software bounce buffers used on x86-64 systems
802           which don't have a hardware IOMMU. Using this PCI devices
803           which can only access 32-bits of memory can be used on systems
804           with more than 3 GB of memory.
805           If unsure, say Y.
806 
807 config IOMMU_HELPER
808         def_bool y
809         depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
810 
811 config MAXSMP
812         bool "Enable Maximum number of SMP Processors and NUMA Nodes"
813         depends on X86_64 && SMP && DEBUG_KERNEL
814         select CPUMASK_OFFSTACK
815         ---help---
816           Enable maximum number of CPUS and NUMA Nodes for this architecture.
817           If unsure, say N.
818 
819 config NR_CPUS
820         int "Maximum number of CPUs" if SMP && !MAXSMP
821         range 2 8 if SMP && X86_32 && !X86_BIGSMP
822         range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
823         range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
824         default "1" if !SMP
825         default "8192" if MAXSMP
826         default "32" if SMP && X86_BIGSMP
827         default "8" if SMP
828         ---help---
829           This allows you to specify the maximum number of CPUs which this
830           kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
831           supported value is 4096, otherwise the maximum value is 512.  The
832           minimum value which makes sense is 2.
833 
834           This is purely to save memory - each supported CPU adds
835           approximately eight kilobytes to the kernel image.
836 
837 config SCHED_SMT
838         bool "SMT (Hyperthreading) scheduler support"
839         depends on X86_HT
840         ---help---
841           SMT scheduler support improves the CPU scheduler's decision making
842           when dealing with Intel Pentium 4 chips with HyperThreading at a
843           cost of slightly increased overhead in some places. If unsure say
844           N here.
845 
846 config SCHED_MC
847         def_bool y
848         prompt "Multi-core scheduler support"
849         depends on X86_HT
850         ---help---
851           Multi-core scheduler support improves the CPU scheduler's decision
852           making when dealing with multi-core CPU chips at a cost of slightly
853           increased overhead in some places. If unsure say N here.
854 
855 source "kernel/Kconfig.preempt"
856 
857 config X86_UP_APIC
858         bool "Local APIC support on uniprocessors"
859         depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI
860         ---help---
861           A local APIC (Advanced Programmable Interrupt Controller) is an
862           integrated interrupt controller in the CPU. If you have a single-CPU
863           system which has a processor with a local APIC, you can say Y here to
864           enable and use it. If you say Y here even though your machine doesn't
865           have a local APIC, then the kernel will still run with no slowdown at
866           all. The local APIC supports CPU-generated self-interrupts (timer,
867           performance counters), and the NMI watchdog which detects hard
868           lockups.
869 
870 config X86_UP_IOAPIC
871         bool "IO-APIC support on uniprocessors"
872         depends on X86_UP_APIC
873         ---help---
874           An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
875           SMP-capable replacement for PC-style interrupt controllers. Most
876           SMP systems and many recent uniprocessor systems have one.
877 
878           If you have a single-CPU system with an IO-APIC, you can say Y here
879           to use it. If you say Y here even though your machine doesn't have
880           an IO-APIC, then the kernel will still run with no slowdown at all.
881 
882 config X86_LOCAL_APIC
883         def_bool y
884         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
885 
886 config X86_IO_APIC
887         def_bool y
888         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC || PCI_MSI
889         select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
890         select IRQ_DOMAIN
891 
892 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
893         bool "Reroute for broken boot IRQs"
894         depends on X86_IO_APIC
895         ---help---
896           This option enables a workaround that fixes a source of
897           spurious interrupts. This is recommended when threaded
898           interrupt handling is used on systems where the generation of
899           superfluous "boot interrupts" cannot be disabled.
900 
901           Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
902           entry in the chipset's IO-APIC is masked (as, e.g. the RT
903           kernel does during interrupt handling). On chipsets where this
904           boot IRQ generation cannot be disabled, this workaround keeps
905           the original IRQ line masked so that only the equivalent "boot
906           IRQ" is delivered to the CPUs. The workaround also tells the
907           kernel to set up the IRQ handler on the boot IRQ line. In this
908           way only one interrupt is delivered to the kernel. Otherwise
909           the spurious second interrupt may cause the kernel to bring
910           down (vital) interrupt lines.
911 
912           Only affects "broken" chipsets. Interrupt sharing may be
913           increased on these systems.
914 
915 config X86_MCE
916         bool "Machine Check / overheating reporting"
917         default y
918         ---help---
919           Machine Check support allows the processor to notify the
920           kernel if it detects a problem (e.g. overheating, data corruption).
921           The action the kernel takes depends on the severity of the problem,
922           ranging from warning messages to halting the machine.
923 
924 config X86_MCE_INTEL
925         def_bool y
926         prompt "Intel MCE features"
927         depends on X86_MCE && X86_LOCAL_APIC
928         ---help---
929            Additional support for intel specific MCE features such as
930            the thermal monitor.
931 
932 config X86_MCE_AMD
933         def_bool y
934         prompt "AMD MCE features"
935         depends on X86_MCE && X86_LOCAL_APIC
936         ---help---
937            Additional support for AMD specific MCE features such as
938            the DRAM Error Threshold.
939 
940 config X86_ANCIENT_MCE
941         bool "Support for old Pentium 5 / WinChip machine checks"
942         depends on X86_32 && X86_MCE
943         ---help---
944           Include support for machine check handling on old Pentium 5 or WinChip
945           systems. These typically need to be enabled explicitly on the command
946           line.
947 
948 config X86_MCE_THRESHOLD
949         depends on X86_MCE_AMD || X86_MCE_INTEL
950         def_bool y
951 
952 config X86_MCE_INJECT
953         depends on X86_MCE
954         tristate "Machine check injector support"
955         ---help---
956           Provide support for injecting machine checks for testing purposes.
957           If you don't know what a machine check is and you don't do kernel
958           QA it is safe to say n.
959 
960 config X86_THERMAL_VECTOR
961         def_bool y
962         depends on X86_MCE_INTEL
963 
964 config VM86
965         bool "Enable VM86 support" if EXPERT
966         default y
967         depends on X86_32
968         ---help---
969           This option is required by programs like DOSEMU to run
970           16-bit real mode legacy code on x86 processors. It also may
971           be needed by software like XFree86 to initialize some video
972           cards via BIOS. Disabling this option saves about 6K.
973 
974 config X86_16BIT
975         bool "Enable support for 16-bit segments" if EXPERT
976         default y
977         ---help---
978           This option is required by programs like Wine to run 16-bit
979           protected mode legacy code on x86 processors.  Disabling
980           this option saves about 300 bytes on i386, or around 6K text
981           plus 16K runtime memory on x86-64,
982 
983 config X86_ESPFIX32
984         def_bool y
985         depends on X86_16BIT && X86_32
986 
987 config X86_ESPFIX64
988         def_bool y
989         depends on X86_16BIT && X86_64
990 
991 config TOSHIBA
992         tristate "Toshiba Laptop support"
993         depends on X86_32
994         ---help---
995           This adds a driver to safely access the System Management Mode of
996           the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
997           not work on models with a Phoenix BIOS. The System Management Mode
998           is used to set the BIOS and power saving options on Toshiba portables.
999 
1000           For information on utilities to make use of this driver see the
1001           Toshiba Linux utilities web site at:
1002           <http://www.buzzard.org.uk/toshiba/>.
1003 
1004           Say Y if you intend to run this kernel on a Toshiba portable.
1005           Say N otherwise.
1006 
1007 config I8K
1008         tristate "Dell laptop support"
1009         select HWMON
1010         ---help---
1011           This adds a driver to safely access the System Management Mode
1012           of the CPU on the Dell Inspiron 8000. The System Management Mode
1013           is used to read cpu temperature and cooling fan status and to
1014           control the fans on the I8K portables.
1015 
1016           This driver has been tested only on the Inspiron 8000 but it may
1017           also work with other Dell laptops. You can force loading on other
1018           models by passing the parameter `force=1' to the module. Use at
1019           your own risk.
1020 
1021           For information on utilities to make use of this driver see the
1022           I8K Linux utilities web site at:
1023           <http://people.debian.org/~dz/i8k/>
1024 
1025           Say Y if you intend to run this kernel on a Dell Inspiron 8000.
1026           Say N otherwise.
1027 
1028 config X86_REBOOTFIXUPS
1029         bool "Enable X86 board specific fixups for reboot"
1030         depends on X86_32
1031         ---help---
1032           This enables chipset and/or board specific fixups to be done
1033           in order to get reboot to work correctly. This is only needed on
1034           some combinations of hardware and BIOS. The symptom, for which
1035           this config is intended, is when reboot ends with a stalled/hung
1036           system.
1037 
1038           Currently, the only fixup is for the Geode machines using
1039           CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1040 
1041           Say Y if you want to enable the fixup. Currently, it's safe to
1042           enable this option even if you don't need it.
1043           Say N otherwise.
1044 
1045 config MICROCODE
1046         tristate "CPU microcode loading support"
1047         depends on CPU_SUP_AMD || CPU_SUP_INTEL
1048         select FW_LOADER
1049         ---help---
1050 
1051           If you say Y here, you will be able to update the microcode on
1052           certain Intel and AMD processors. The Intel support is for the
1053           IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1054           Xeon etc. The AMD support is for families 0x10 and later. You will
1055           obviously need the actual microcode binary data itself which is not
1056           shipped with the Linux kernel.
1057 
1058           This option selects the general module only, you need to select
1059           at least one vendor specific module as well.
1060 
1061           To compile this driver as a module, choose M here: the module
1062           will be called microcode.
1063 
1064 config MICROCODE_INTEL
1065         bool "Intel microcode loading support"
1066         depends on MICROCODE
1067         default MICROCODE
1068         select FW_LOADER
1069         ---help---
1070           This options enables microcode patch loading support for Intel
1071           processors.
1072 
1073           For the current Intel microcode data package go to
1074           <https://downloadcenter.intel.com> and search for
1075           'Linux Processor Microcode Data File'.
1076 
1077 config MICROCODE_AMD
1078         bool "AMD microcode loading support"
1079         depends on MICROCODE
1080         select FW_LOADER
1081         ---help---
1082           If you select this option, microcode patch loading support for AMD
1083           processors will be enabled.
1084 
1085 config MICROCODE_OLD_INTERFACE
1086         def_bool y
1087         depends on MICROCODE
1088 
1089 config MICROCODE_INTEL_EARLY
1090         def_bool n
1091 
1092 config MICROCODE_AMD_EARLY
1093         def_bool n
1094 
1095 config MICROCODE_EARLY
1096         bool "Early load microcode"
1097         depends on MICROCODE=y && BLK_DEV_INITRD
1098         select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1099         select MICROCODE_AMD_EARLY if MICROCODE_AMD
1100         default y
1101         help
1102           This option provides functionality to read additional microcode data
1103           at the beginning of initrd image. The data tells kernel to load
1104           microcode to CPU's as early as possible. No functional change if no
1105           microcode data is glued to the initrd, therefore it's safe to say Y.
1106 
1107 config X86_MSR
1108         tristate "/dev/cpu/*/msr - Model-specific register support"
1109         ---help---
1110           This device gives privileged processes access to the x86
1111           Model-Specific Registers (MSRs).  It is a character device with
1112           major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1113           MSR accesses are directed to a specific CPU on multi-processor
1114           systems.
1115 
1116 config X86_CPUID
1117         tristate "/dev/cpu/*/cpuid - CPU information support"
1118         ---help---
1119           This device gives processes access to the x86 CPUID instruction to
1120           be executed on a specific processor.  It is a character device
1121           with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1122           /dev/cpu/31/cpuid.
1123 
1124 choice
1125         prompt "High Memory Support"
1126         default HIGHMEM4G
1127         depends on X86_32
1128 
1129 config NOHIGHMEM
1130         bool "off"
1131         ---help---
1132           Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1133           However, the address space of 32-bit x86 processors is only 4
1134           Gigabytes large. That means that, if you have a large amount of
1135           physical memory, not all of it can be "permanently mapped" by the
1136           kernel. The physical memory that's not permanently mapped is called
1137           "high memory".
1138 
1139           If you are compiling a kernel which will never run on a machine with
1140           more than 1 Gigabyte total physical RAM, answer "off" here (default
1141           choice and suitable for most users). This will result in a "3GB/1GB"
1142           split: 3GB are mapped so that each process sees a 3GB virtual memory
1143           space and the remaining part of the 4GB virtual memory space is used
1144           by the kernel to permanently map as much physical memory as
1145           possible.
1146 
1147           If the machine has between 1 and 4 Gigabytes physical RAM, then
1148           answer "4GB" here.
1149 
1150           If more than 4 Gigabytes is used then answer "64GB" here. This
1151           selection turns Intel PAE (Physical Address Extension) mode on.
1152           PAE implements 3-level paging on IA32 processors. PAE is fully
1153           supported by Linux, PAE mode is implemented on all recent Intel
1154           processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1155           then the kernel will not boot on CPUs that don't support PAE!
1156 
1157           The actual amount of total physical memory will either be
1158           auto detected or can be forced by using a kernel command line option
1159           such as "mem=256M". (Try "man bootparam" or see the documentation of
1160           your boot loader (lilo or loadlin) about how to pass options to the
1161           kernel at boot time.)
1162 
1163           If unsure, say "off".
1164 
1165 config HIGHMEM4G
1166         bool "4GB"
1167         ---help---
1168           Select this if you have a 32-bit processor and between 1 and 4
1169           gigabytes of physical RAM.
1170 
1171 config HIGHMEM64G
1172         bool "64GB"
1173         depends on !M486
1174         select X86_PAE
1175         ---help---
1176           Select this if you have a 32-bit processor and more than 4
1177           gigabytes of physical RAM.
1178 
1179 endchoice
1180 
1181 choice
1182         prompt "Memory split" if EXPERT
1183         default VMSPLIT_3G
1184         depends on X86_32
1185         ---help---
1186           Select the desired split between kernel and user memory.
1187 
1188           If the address range available to the kernel is less than the
1189           physical memory installed, the remaining memory will be available
1190           as "high memory". Accessing high memory is a little more costly
1191           than low memory, as it needs to be mapped into the kernel first.
1192           Note that increasing the kernel address space limits the range
1193           available to user programs, making the address space there
1194           tighter.  Selecting anything other than the default 3G/1G split
1195           will also likely make your kernel incompatible with binary-only
1196           kernel modules.
1197 
1198           If you are not absolutely sure what you are doing, leave this
1199           option alone!
1200 
1201         config VMSPLIT_3G
1202                 bool "3G/1G user/kernel split"
1203         config VMSPLIT_3G_OPT
1204                 depends on !X86_PAE
1205                 bool "3G/1G user/kernel split (for full 1G low memory)"
1206         config VMSPLIT_2G
1207                 bool "2G/2G user/kernel split"
1208         config VMSPLIT_2G_OPT
1209                 depends on !X86_PAE
1210                 bool "2G/2G user/kernel split (for full 2G low memory)"
1211         config VMSPLIT_1G
1212                 bool "1G/3G user/kernel split"
1213 endchoice
1214 
1215 config PAGE_OFFSET
1216         hex
1217         default 0xB0000000 if VMSPLIT_3G_OPT
1218         default 0x80000000 if VMSPLIT_2G
1219         default 0x78000000 if VMSPLIT_2G_OPT
1220         default 0x40000000 if VMSPLIT_1G
1221         default 0xC0000000
1222         depends on X86_32
1223 
1224 config HIGHMEM
1225         def_bool y
1226         depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1227 
1228 config X86_PAE
1229         bool "PAE (Physical Address Extension) Support"
1230         depends on X86_32 && !HIGHMEM4G
1231         ---help---
1232           PAE is required for NX support, and furthermore enables
1233           larger swapspace support for non-overcommit purposes. It
1234           has the cost of more pagetable lookup overhead, and also
1235           consumes more pagetable space per process.
1236 
1237 config ARCH_PHYS_ADDR_T_64BIT
1238         def_bool y
1239         depends on X86_64 || X86_PAE
1240 
1241 config ARCH_DMA_ADDR_T_64BIT
1242         def_bool y
1243         depends on X86_64 || HIGHMEM64G
1244 
1245 config DIRECT_GBPAGES
1246         bool "Enable 1GB pages for kernel pagetables" if EXPERT
1247         default y
1248         depends on X86_64
1249         ---help---
1250           Allow the kernel linear mapping to use 1GB pages on CPUs that
1251           support it. This can improve the kernel's performance a tiny bit by
1252           reducing TLB pressure. If in doubt, say "Y".
1253 
1254 # Common NUMA Features
1255 config NUMA
1256         bool "Numa Memory Allocation and Scheduler Support"
1257         depends on SMP
1258         depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1259         default y if X86_BIGSMP
1260         ---help---
1261           Enable NUMA (Non Uniform Memory Access) support.
1262 
1263           The kernel will try to allocate memory used by a CPU on the
1264           local memory controller of the CPU and add some more
1265           NUMA awareness to the kernel.
1266 
1267           For 64-bit this is recommended if the system is Intel Core i7
1268           (or later), AMD Opteron, or EM64T NUMA.
1269 
1270           For 32-bit this is only needed if you boot a 32-bit
1271           kernel on a 64-bit NUMA platform.
1272 
1273           Otherwise, you should say N.
1274 
1275 config AMD_NUMA
1276         def_bool y
1277         prompt "Old style AMD Opteron NUMA detection"
1278         depends on X86_64 && NUMA && PCI
1279         ---help---
1280           Enable AMD NUMA node topology detection.  You should say Y here if
1281           you have a multi processor AMD system. This uses an old method to
1282           read the NUMA configuration directly from the builtin Northbridge
1283           of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1284           which also takes priority if both are compiled in.
1285 
1286 config X86_64_ACPI_NUMA
1287         def_bool y
1288         prompt "ACPI NUMA detection"
1289         depends on X86_64 && NUMA && ACPI && PCI
1290         select ACPI_NUMA
1291         ---help---
1292           Enable ACPI SRAT based node topology detection.
1293 
1294 # Some NUMA nodes have memory ranges that span
1295 # other nodes.  Even though a pfn is valid and
1296 # between a node's start and end pfns, it may not
1297 # reside on that node.  See memmap_init_zone()
1298 # for details.
1299 config NODES_SPAN_OTHER_NODES
1300         def_bool y
1301         depends on X86_64_ACPI_NUMA
1302 
1303 config NUMA_EMU
1304         bool "NUMA emulation"
1305         depends on NUMA
1306         ---help---
1307           Enable NUMA emulation. A flat machine will be split
1308           into virtual nodes when booted with "numa=fake=N", where N is the
1309           number of nodes. This is only useful for debugging.
1310 
1311 config NODES_SHIFT
1312         int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1313         range 1 10
1314         default "10" if MAXSMP
1315         default "6" if X86_64
1316         default "3"
1317         depends on NEED_MULTIPLE_NODES
1318         ---help---
1319           Specify the maximum number of NUMA Nodes available on the target
1320           system.  Increases memory reserved to accommodate various tables.
1321 
1322 config ARCH_HAVE_MEMORY_PRESENT
1323         def_bool y
1324         depends on X86_32 && DISCONTIGMEM
1325 
1326 config NEED_NODE_MEMMAP_SIZE
1327         def_bool y
1328         depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1329 
1330 config ARCH_FLATMEM_ENABLE
1331         def_bool y
1332         depends on X86_32 && !NUMA
1333 
1334 config ARCH_DISCONTIGMEM_ENABLE
1335         def_bool y
1336         depends on NUMA && X86_32
1337 
1338 config ARCH_DISCONTIGMEM_DEFAULT
1339         def_bool y
1340         depends on NUMA && X86_32
1341 
1342 config ARCH_SPARSEMEM_ENABLE
1343         def_bool y
1344         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1345         select SPARSEMEM_STATIC if X86_32
1346         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1347 
1348 config ARCH_SPARSEMEM_DEFAULT
1349         def_bool y
1350         depends on X86_64
1351 
1352 config ARCH_SELECT_MEMORY_MODEL
1353         def_bool y
1354         depends on ARCH_SPARSEMEM_ENABLE
1355 
1356 config ARCH_MEMORY_PROBE
1357         bool "Enable sysfs memory/probe interface"
1358         depends on X86_64 && MEMORY_HOTPLUG
1359         help
1360           This option enables a sysfs memory/probe interface for testing.
1361           See Documentation/memory-hotplug.txt for more information.
1362           If you are unsure how to answer this question, answer N.
1363 
1364 config ARCH_PROC_KCORE_TEXT
1365         def_bool y
1366         depends on X86_64 && PROC_KCORE
1367 
1368 config ILLEGAL_POINTER_VALUE
1369        hex
1370        default 0 if X86_32
1371        default 0xdead000000000000 if X86_64
1372 
1373 source "mm/Kconfig"
1374 
1375 config HIGHPTE
1376         bool "Allocate 3rd-level pagetables from highmem"
1377         depends on HIGHMEM
1378         ---help---
1379           The VM uses one page table entry for each page of physical memory.
1380           For systems with a lot of RAM, this can be wasteful of precious
1381           low memory.  Setting this option will put user-space page table
1382           entries in high memory.
1383 
1384 config X86_CHECK_BIOS_CORRUPTION
1385         bool "Check for low memory corruption"
1386         ---help---
1387           Periodically check for memory corruption in low memory, which
1388           is suspected to be caused by BIOS.  Even when enabled in the
1389           configuration, it is disabled at runtime.  Enable it by
1390           setting "memory_corruption_check=1" on the kernel command
1391           line.  By default it scans the low 64k of memory every 60
1392           seconds; see the memory_corruption_check_size and
1393           memory_corruption_check_period parameters in
1394           Documentation/kernel-parameters.txt to adjust this.
1395 
1396           When enabled with the default parameters, this option has
1397           almost no overhead, as it reserves a relatively small amount
1398           of memory and scans it infrequently.  It both detects corruption
1399           and prevents it from affecting the running system.
1400 
1401           It is, however, intended as a diagnostic tool; if repeatable
1402           BIOS-originated corruption always affects the same memory,
1403           you can use memmap= to prevent the kernel from using that
1404           memory.
1405 
1406 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1407         bool "Set the default setting of memory_corruption_check"
1408         depends on X86_CHECK_BIOS_CORRUPTION
1409         default y
1410         ---help---
1411           Set whether the default state of memory_corruption_check is
1412           on or off.
1413 
1414 config X86_RESERVE_LOW
1415         int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1416         default 64
1417         range 4 640
1418         ---help---
1419           Specify the amount of low memory to reserve for the BIOS.
1420 
1421           The first page contains BIOS data structures that the kernel
1422           must not use, so that page must always be reserved.
1423 
1424           By default we reserve the first 64K of physical RAM, as a
1425           number of BIOSes are known to corrupt that memory range
1426           during events such as suspend/resume or monitor cable
1427           insertion, so it must not be used by the kernel.
1428 
1429           You can set this to 4 if you are absolutely sure that you
1430           trust the BIOS to get all its memory reservations and usages
1431           right.  If you know your BIOS have problems beyond the
1432           default 64K area, you can set this to 640 to avoid using the
1433           entire low memory range.
1434 
1435           If you have doubts about the BIOS (e.g. suspend/resume does
1436           not work or there's kernel crashes after certain hardware
1437           hotplug events) then you might want to enable
1438           X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1439           typical corruption patterns.
1440 
1441           Leave this to the default value of 64 if you are unsure.
1442 
1443 config MATH_EMULATION
1444         bool
1445         prompt "Math emulation" if X86_32
1446         ---help---
1447           Linux can emulate a math coprocessor (used for floating point
1448           operations) if you don't have one. 486DX and Pentium processors have
1449           a math coprocessor built in, 486SX and 386 do not, unless you added
1450           a 487DX or 387, respectively. (The messages during boot time can
1451           give you some hints here ["man dmesg"].) Everyone needs either a
1452           coprocessor or this emulation.
1453 
1454           If you don't have a math coprocessor, you need to say Y here; if you
1455           say Y here even though you have a coprocessor, the coprocessor will
1456           be used nevertheless. (This behavior can be changed with the kernel
1457           command line option "no387", which comes handy if your coprocessor
1458           is broken. Try "man bootparam" or see the documentation of your boot
1459           loader (lilo or loadlin) about how to pass options to the kernel at
1460           boot time.) This means that it is a good idea to say Y here if you
1461           intend to use this kernel on different machines.
1462 
1463           More information about the internals of the Linux math coprocessor
1464           emulation can be found in <file:arch/x86/math-emu/README>.
1465 
1466           If you are not sure, say Y; apart from resulting in a 66 KB bigger
1467           kernel, it won't hurt.
1468 
1469 config MTRR
1470         def_bool y
1471         prompt "MTRR (Memory Type Range Register) support" if EXPERT
1472         ---help---
1473           On Intel P6 family processors (Pentium Pro, Pentium II and later)
1474           the Memory Type Range Registers (MTRRs) may be used to control
1475           processor access to memory ranges. This is most useful if you have
1476           a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1477           allows bus write transfers to be combined into a larger transfer
1478           before bursting over the PCI/AGP bus. This can increase performance
1479           of image write operations 2.5 times or more. Saying Y here creates a
1480           /proc/mtrr file which may be used to manipulate your processor's
1481           MTRRs. Typically the X server should use this.
1482 
1483           This code has a reasonably generic interface so that similar
1484           control registers on other processors can be easily supported
1485           as well:
1486 
1487           The Cyrix 6x86, 6x86MX and M II processors have Address Range
1488           Registers (ARRs) which provide a similar functionality to MTRRs. For
1489           these, the ARRs are used to emulate the MTRRs.
1490           The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1491           MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1492           write-combining. All of these processors are supported by this code
1493           and it makes sense to say Y here if you have one of them.
1494 
1495           Saying Y here also fixes a problem with buggy SMP BIOSes which only
1496           set the MTRRs for the boot CPU and not for the secondary CPUs. This
1497           can lead to all sorts of problems, so it's good to say Y here.
1498 
1499           You can safely say Y even if your machine doesn't have MTRRs, you'll
1500           just add about 9 KB to your kernel.
1501 
1502           See <file:Documentation/x86/mtrr.txt> for more information.
1503 
1504 config MTRR_SANITIZER
1505         def_bool y
1506         prompt "MTRR cleanup support"
1507         depends on MTRR
1508         ---help---
1509           Convert MTRR layout from continuous to discrete, so X drivers can
1510           add writeback entries.
1511 
1512           Can be disabled with disable_mtrr_cleanup on the kernel command line.
1513           The largest mtrr entry size for a continuous block can be set with
1514           mtrr_chunk_size.
1515 
1516           If unsure, say Y.
1517 
1518 config MTRR_SANITIZER_ENABLE_DEFAULT
1519         int "MTRR cleanup enable value (0-1)"
1520         range 0 1
1521         default "0"
1522         depends on MTRR_SANITIZER
1523         ---help---
1524           Enable mtrr cleanup default value
1525 
1526 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1527         int "MTRR cleanup spare reg num (0-7)"
1528         range 0 7
1529         default "1"
1530         depends on MTRR_SANITIZER
1531         ---help---
1532           mtrr cleanup spare entries default, it can be changed via
1533           mtrr_spare_reg_nr=N on the kernel command line.
1534 
1535 config X86_PAT
1536         def_bool y
1537         prompt "x86 PAT support" if EXPERT
1538         depends on MTRR
1539         ---help---
1540           Use PAT attributes to setup page level cache control.
1541 
1542           PATs are the modern equivalents of MTRRs and are much more
1543           flexible than MTRRs.
1544 
1545           Say N here if you see bootup problems (boot crash, boot hang,
1546           spontaneous reboots) or a non-working video driver.
1547 
1548           If unsure, say Y.
1549 
1550 config ARCH_USES_PG_UNCACHED
1551         def_bool y
1552         depends on X86_PAT
1553 
1554 config ARCH_RANDOM
1555         def_bool y
1556         prompt "x86 architectural random number generator" if EXPERT
1557         ---help---
1558           Enable the x86 architectural RDRAND instruction
1559           (Intel Bull Mountain technology) to generate random numbers.
1560           If supported, this is a high bandwidth, cryptographically
1561           secure hardware random number generator.
1562 
1563 config X86_SMAP
1564         def_bool y
1565         prompt "Supervisor Mode Access Prevention" if EXPERT
1566         ---help---
1567           Supervisor Mode Access Prevention (SMAP) is a security
1568           feature in newer Intel processors.  There is a small
1569           performance cost if this enabled and turned on; there is
1570           also a small increase in the kernel size if this is enabled.
1571 
1572           If unsure, say Y.
1573 
1574 config EFI
1575         bool "EFI runtime service support"
1576         depends on ACPI
1577         select UCS2_STRING
1578         select EFI_RUNTIME_WRAPPERS
1579         ---help---
1580           This enables the kernel to use EFI runtime services that are
1581           available (such as the EFI variable services).
1582 
1583           This option is only useful on systems that have EFI firmware.
1584           In addition, you should use the latest ELILO loader available
1585           at <http://elilo.sourceforge.net> in order to take advantage
1586           of EFI runtime services. However, even with this option, the
1587           resultant kernel should continue to boot on existing non-EFI
1588           platforms.
1589 
1590 config EFI_STUB
1591        bool "EFI stub support"
1592        depends on EFI && !X86_USE_3DNOW
1593        select RELOCATABLE
1594        ---help---
1595           This kernel feature allows a bzImage to be loaded directly
1596           by EFI firmware without the use of a bootloader.
1597 
1598           See Documentation/efi-stub.txt for more information.
1599 
1600 config EFI_MIXED
1601         bool "EFI mixed-mode support"
1602         depends on EFI_STUB && X86_64
1603         ---help---
1604            Enabling this feature allows a 64-bit kernel to be booted
1605            on a 32-bit firmware, provided that your CPU supports 64-bit
1606            mode.
1607 
1608            Note that it is not possible to boot a mixed-mode enabled
1609            kernel via the EFI boot stub - a bootloader that supports
1610            the EFI handover protocol must be used.
1611 
1612            If unsure, say N.
1613 
1614 config SECCOMP
1615         def_bool y
1616         prompt "Enable seccomp to safely compute untrusted bytecode"
1617         ---help---
1618           This kernel feature is useful for number crunching applications
1619           that may need to compute untrusted bytecode during their
1620           execution. By using pipes or other transports made available to
1621           the process as file descriptors supporting the read/write
1622           syscalls, it's possible to isolate those applications in
1623           their own address space using seccomp. Once seccomp is
1624           enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1625           and the task is only allowed to execute a few safe syscalls
1626           defined by each seccomp mode.
1627 
1628           If unsure, say Y. Only embedded should say N here.
1629 
1630 source kernel/Kconfig.hz
1631 
1632 config KEXEC
1633         bool "kexec system call"
1634         ---help---
1635           kexec is a system call that implements the ability to shutdown your
1636           current kernel, and to start another kernel.  It is like a reboot
1637           but it is independent of the system firmware.   And like a reboot
1638           you can start any kernel with it, not just Linux.
1639 
1640           The name comes from the similarity to the exec system call.
1641 
1642           It is an ongoing process to be certain the hardware in a machine
1643           is properly shutdown, so do not be surprised if this code does not
1644           initially work for you.  As of this writing the exact hardware
1645           interface is strongly in flux, so no good recommendation can be
1646           made.
1647 
1648 config KEXEC_FILE
1649         bool "kexec file based system call"
1650         select BUILD_BIN2C
1651         depends on KEXEC
1652         depends on X86_64
1653         depends on CRYPTO=y
1654         depends on CRYPTO_SHA256=y
1655         ---help---
1656           This is new version of kexec system call. This system call is
1657           file based and takes file descriptors as system call argument
1658           for kernel and initramfs as opposed to list of segments as
1659           accepted by previous system call.
1660 
1661 config KEXEC_VERIFY_SIG
1662         bool "Verify kernel signature during kexec_file_load() syscall"
1663         depends on KEXEC_FILE
1664         ---help---
1665           This option makes kernel signature verification mandatory for
1666           kexec_file_load() syscall. If kernel is signature can not be
1667           verified, kexec_file_load() will fail.
1668 
1669           This option enforces signature verification at generic level.
1670           One needs to enable signature verification for type of kernel
1671           image being loaded to make sure it works. For example, enable
1672           bzImage signature verification option to be able to load and
1673           verify signatures of bzImage. Otherwise kernel loading will fail.
1674 
1675 config KEXEC_BZIMAGE_VERIFY_SIG
1676         bool "Enable bzImage signature verification support"
1677         depends on KEXEC_VERIFY_SIG
1678         depends on SIGNED_PE_FILE_VERIFICATION
1679         select SYSTEM_TRUSTED_KEYRING
1680         ---help---
1681           Enable bzImage signature verification support.
1682 
1683 config CRASH_DUMP
1684         bool "kernel crash dumps"
1685         depends on X86_64 || (X86_32 && HIGHMEM)
1686         ---help---
1687           Generate crash dump after being started by kexec.
1688           This should be normally only set in special crash dump kernels
1689           which are loaded in the main kernel with kexec-tools into
1690           a specially reserved region and then later executed after
1691           a crash by kdump/kexec. The crash dump kernel must be compiled
1692           to a memory address not used by the main kernel or BIOS using
1693           PHYSICAL_START, or it must be built as a relocatable image
1694           (CONFIG_RELOCATABLE=y).
1695           For more details see Documentation/kdump/kdump.txt
1696 
1697 config KEXEC_JUMP
1698         bool "kexec jump"
1699         depends on KEXEC && HIBERNATION
1700         ---help---
1701           Jump between original kernel and kexeced kernel and invoke
1702           code in physical address mode via KEXEC
1703 
1704 config PHYSICAL_START
1705         hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1706         default "0x1000000"
1707         ---help---
1708           This gives the physical address where the kernel is loaded.
1709 
1710           If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1711           bzImage will decompress itself to above physical address and
1712           run from there. Otherwise, bzImage will run from the address where
1713           it has been loaded by the boot loader and will ignore above physical
1714           address.
1715 
1716           In normal kdump cases one does not have to set/change this option
1717           as now bzImage can be compiled as a completely relocatable image
1718           (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1719           address. This option is mainly useful for the folks who don't want
1720           to use a bzImage for capturing the crash dump and want to use a
1721           vmlinux instead. vmlinux is not relocatable hence a kernel needs
1722           to be specifically compiled to run from a specific memory area
1723           (normally a reserved region) and this option comes handy.
1724 
1725           So if you are using bzImage for capturing the crash dump,
1726           leave the value here unchanged to 0x1000000 and set
1727           CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
1728           for capturing the crash dump change this value to start of
1729           the reserved region.  In other words, it can be set based on
1730           the "X" value as specified in the "crashkernel=YM@XM"
1731           command line boot parameter passed to the panic-ed
1732           kernel. Please take a look at Documentation/kdump/kdump.txt
1733           for more details about crash dumps.
1734 
1735           Usage of bzImage for capturing the crash dump is recommended as
1736           one does not have to build two kernels. Same kernel can be used
1737           as production kernel and capture kernel. Above option should have
1738           gone away after relocatable bzImage support is introduced. But it
1739           is present because there are users out there who continue to use
1740           vmlinux for dump capture. This option should go away down the
1741           line.
1742 
1743           Don't change this unless you know what you are doing.
1744 
1745 config RELOCATABLE
1746         bool "Build a relocatable kernel"
1747         default y
1748         ---help---
1749           This builds a kernel image that retains relocation information
1750           so it can be loaded someplace besides the default 1MB.
1751           The relocations tend to make the kernel binary about 10% larger,
1752           but are discarded at runtime.
1753 
1754           One use is for the kexec on panic case where the recovery kernel
1755           must live at a different physical address than the primary
1756           kernel.
1757 
1758           Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1759           it has been loaded at and the compile time physical address
1760           (CONFIG_PHYSICAL_START) is used as the minimum location.
1761 
1762 config RANDOMIZE_BASE
1763         bool "Randomize the address of the kernel image"
1764         depends on RELOCATABLE
1765         default n
1766         ---help---
1767            Randomizes the physical and virtual address at which the
1768            kernel image is decompressed, as a security feature that
1769            deters exploit attempts relying on knowledge of the location
1770            of kernel internals.
1771 
1772            Entropy is generated using the RDRAND instruction if it is
1773            supported. If RDTSC is supported, it is used as well. If
1774            neither RDRAND nor RDTSC are supported, then randomness is
1775            read from the i8254 timer.
1776 
1777            The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1778            and aligned according to PHYSICAL_ALIGN. Since the kernel is
1779            built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1780            minimum of 2MiB, only 10 bits of entropy is theoretically
1781            possible. At best, due to page table layouts, 64-bit can use
1782            9 bits of entropy and 32-bit uses 8 bits.
1783 
1784            If unsure, say N.
1785 
1786 config RANDOMIZE_BASE_MAX_OFFSET
1787         hex "Maximum kASLR offset allowed" if EXPERT
1788         depends on RANDOMIZE_BASE
1789         range 0x0 0x20000000 if X86_32
1790         default "0x20000000" if X86_32
1791         range 0x0 0x40000000 if X86_64
1792         default "0x40000000" if X86_64
1793         ---help---
1794           The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1795           memory is used to determine the maximal offset in bytes that will
1796           be applied to the kernel when kernel Address Space Layout
1797           Randomization (kASLR) is active. This must be a multiple of
1798           PHYSICAL_ALIGN.
1799 
1800           On 32-bit this is limited to 512MiB by page table layouts. The
1801           default is 512MiB.
1802 
1803           On 64-bit this is limited by how the kernel fixmap page table is
1804           positioned, so this cannot be larger than 1GiB currently. Without
1805           RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1806           and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1807           modules area will shrink to compensate, up to the current maximum
1808           1GiB to 1GiB split. The default is 1GiB.
1809 
1810           If unsure, leave at the default value.
1811 
1812 # Relocation on x86 needs some additional build support
1813 config X86_NEED_RELOCS
1814         def_bool y
1815         depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1816 
1817 config PHYSICAL_ALIGN
1818         hex "Alignment value to which kernel should be aligned"
1819         default "0x200000"
1820         range 0x2000 0x1000000 if X86_32
1821         range 0x200000 0x1000000 if X86_64
1822         ---help---
1823           This value puts the alignment restrictions on physical address
1824           where kernel is loaded and run from. Kernel is compiled for an
1825           address which meets above alignment restriction.
1826 
1827           If bootloader loads the kernel at a non-aligned address and
1828           CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1829           address aligned to above value and run from there.
1830 
1831           If bootloader loads the kernel at a non-aligned address and
1832           CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1833           load address and decompress itself to the address it has been
1834           compiled for and run from there. The address for which kernel is
1835           compiled already meets above alignment restrictions. Hence the
1836           end result is that kernel runs from a physical address meeting
1837           above alignment restrictions.
1838 
1839           On 32-bit this value must be a multiple of 0x2000. On 64-bit
1840           this value must be a multiple of 0x200000.
1841 
1842           Don't change this unless you know what you are doing.
1843 
1844 config HOTPLUG_CPU
1845         bool "Support for hot-pluggable CPUs"
1846         depends on SMP
1847         ---help---
1848           Say Y here to allow turning CPUs off and on. CPUs can be
1849           controlled through /sys/devices/system/cpu.
1850           ( Note: power management support will enable this option
1851             automatically on SMP systems. )
1852           Say N if you want to disable CPU hotplug.
1853 
1854 config BOOTPARAM_HOTPLUG_CPU0
1855         bool "Set default setting of cpu0_hotpluggable"
1856         default n
1857         depends on HOTPLUG_CPU
1858         ---help---
1859           Set whether default state of cpu0_hotpluggable is on or off.
1860 
1861           Say Y here to enable CPU0 hotplug by default. If this switch
1862           is turned on, there is no need to give cpu0_hotplug kernel
1863           parameter and the CPU0 hotplug feature is enabled by default.
1864 
1865           Please note: there are two known CPU0 dependencies if you want
1866           to enable the CPU0 hotplug feature either by this switch or by
1867           cpu0_hotplug kernel parameter.
1868 
1869           First, resume from hibernate or suspend always starts from CPU0.
1870           So hibernate and suspend are prevented if CPU0 is offline.
1871 
1872           Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1873           offline if any interrupt can not migrate out of CPU0. There may
1874           be other CPU0 dependencies.
1875 
1876           Please make sure the dependencies are under your control before
1877           you enable this feature.
1878 
1879           Say N if you don't want to enable CPU0 hotplug feature by default.
1880           You still can enable the CPU0 hotplug feature at boot by kernel
1881           parameter cpu0_hotplug.
1882 
1883 config DEBUG_HOTPLUG_CPU0
1884         def_bool n
1885         prompt "Debug CPU0 hotplug"
1886         depends on HOTPLUG_CPU
1887         ---help---
1888           Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1889           soon as possible and boots up userspace with CPU0 offlined. User
1890           can online CPU0 back after boot time.
1891 
1892           To debug CPU0 hotplug, you need to enable CPU0 offline/online
1893           feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1894           compilation or giving cpu0_hotplug kernel parameter at boot.
1895 
1896           If unsure, say N.
1897 
1898 config COMPAT_VDSO
1899         def_bool n
1900         prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
1901         depends on X86_32 || IA32_EMULATION
1902         ---help---
1903           Certain buggy versions of glibc will crash if they are
1904           presented with a 32-bit vDSO that is not mapped at the address
1905           indicated in its segment table.
1906 
1907           The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
1908           and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
1909           49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
1910           the only released version with the bug, but OpenSUSE 9
1911           contains a buggy "glibc 2.3.2".
1912 
1913           The symptom of the bug is that everything crashes on startup, saying:
1914           dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
1915 
1916           Saying Y here changes the default value of the vdso32 boot
1917           option from 1 to 0, which turns off the 32-bit vDSO entirely.
1918           This works around the glibc bug but hurts performance.
1919 
1920           If unsure, say N: if you are compiling your own kernel, you
1921           are unlikely to be using a buggy version of glibc.
1922 
1923 config CMDLINE_BOOL
1924         bool "Built-in kernel command line"
1925         ---help---
1926           Allow for specifying boot arguments to the kernel at
1927           build time.  On some systems (e.g. embedded ones), it is
1928           necessary or convenient to provide some or all of the
1929           kernel boot arguments with the kernel itself (that is,
1930           to not rely on the boot loader to provide them.)
1931 
1932           To compile command line arguments into the kernel,
1933           set this option to 'Y', then fill in the
1934           the boot arguments in CONFIG_CMDLINE.
1935 
1936           Systems with fully functional boot loaders (i.e. non-embedded)
1937           should leave this option set to 'N'.
1938 
1939 config CMDLINE
1940         string "Built-in kernel command string"
1941         depends on CMDLINE_BOOL
1942         default ""
1943         ---help---
1944           Enter arguments here that should be compiled into the kernel
1945           image and used at boot time.  If the boot loader provides a
1946           command line at boot time, it is appended to this string to
1947           form the full kernel command line, when the system boots.
1948 
1949           However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1950           change this behavior.
1951 
1952           In most cases, the command line (whether built-in or provided
1953           by the boot loader) should specify the device for the root
1954           file system.
1955 
1956 config CMDLINE_OVERRIDE
1957         bool "Built-in command line overrides boot loader arguments"
1958         depends on CMDLINE_BOOL
1959         ---help---
1960           Set this option to 'Y' to have the kernel ignore the boot loader
1961           command line, and use ONLY the built-in command line.
1962 
1963           This is used to work around broken boot loaders.  This should
1964           be set to 'N' under normal conditions.
1965 
1966 endmenu
1967 
1968 config ARCH_ENABLE_MEMORY_HOTPLUG
1969         def_bool y
1970         depends on X86_64 || (X86_32 && HIGHMEM)
1971 
1972 config ARCH_ENABLE_MEMORY_HOTREMOVE
1973         def_bool y
1974         depends on MEMORY_HOTPLUG
1975 
1976 config USE_PERCPU_NUMA_NODE_ID
1977         def_bool y
1978         depends on NUMA
1979 
1980 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
1981         def_bool y
1982         depends on X86_64 || X86_PAE
1983 
1984 config ARCH_ENABLE_HUGEPAGE_MIGRATION
1985         def_bool y
1986         depends on X86_64 && HUGETLB_PAGE && MIGRATION
1987 
1988 menu "Power management and ACPI options"
1989 
1990 config ARCH_HIBERNATION_HEADER
1991         def_bool y
1992         depends on X86_64 && HIBERNATION
1993 
1994 source "kernel/power/Kconfig"
1995 
1996 source "drivers/acpi/Kconfig"
1997 
1998 source "drivers/sfi/Kconfig"
1999 
2000 config X86_APM_BOOT
2001         def_bool y
2002         depends on APM
2003 
2004 menuconfig APM
2005         tristate "APM (Advanced Power Management) BIOS support"
2006         depends on X86_32 && PM_SLEEP
2007         ---help---
2008           APM is a BIOS specification for saving power using several different
2009           techniques. This is mostly useful for battery powered laptops with
2010           APM compliant BIOSes. If you say Y here, the system time will be
2011           reset after a RESUME operation, the /proc/apm device will provide
2012           battery status information, and user-space programs will receive
2013           notification of APM "events" (e.g. battery status change).
2014 
2015           If you select "Y" here, you can disable actual use of the APM
2016           BIOS by passing the "apm=off" option to the kernel at boot time.
2017 
2018           Note that the APM support is almost completely disabled for
2019           machines with more than one CPU.
2020 
2021           In order to use APM, you will need supporting software. For location
2022           and more information, read <file:Documentation/power/apm-acpi.txt>
2023           and the Battery Powered Linux mini-HOWTO, available from
2024           <http://www.tldp.org/docs.html#howto>.
2025 
2026           This driver does not spin down disk drives (see the hdparm(8)
2027           manpage ("man 8 hdparm") for that), and it doesn't turn off
2028           VESA-compliant "green" monitors.
2029 
2030           This driver does not support the TI 4000M TravelMate and the ACER
2031           486/DX4/75 because they don't have compliant BIOSes. Many "green"
2032           desktop machines also don't have compliant BIOSes, and this driver
2033           may cause those machines to panic during the boot phase.
2034 
2035           Generally, if you don't have a battery in your machine, there isn't
2036           much point in using this driver and you should say N. If you get
2037           random kernel OOPSes or reboots that don't seem to be related to
2038           anything, try disabling/enabling this option (or disabling/enabling
2039           APM in your BIOS).
2040 
2041           Some other things you should try when experiencing seemingly random,
2042           "weird" problems:
2043 
2044           1) make sure that you have enough swap space and that it is
2045           enabled.
2046           2) pass the "no-hlt" option to the kernel
2047           3) switch on floating point emulation in the kernel and pass
2048           the "no387" option to the kernel
2049           4) pass the "floppy=nodma" option to the kernel
2050           5) pass the "mem=4M" option to the kernel (thereby disabling
2051           all but the first 4 MB of RAM)
2052           6) make sure that the CPU is not over clocked.
2053           7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2054           8) disable the cache from your BIOS settings
2055           9) install a fan for the video card or exchange video RAM
2056           10) install a better fan for the CPU
2057           11) exchange RAM chips
2058           12) exchange the motherboard.
2059 
2060           To compile this driver as a module, choose M here: the
2061           module will be called apm.
2062 
2063 if APM
2064 
2065 config APM_IGNORE_USER_SUSPEND
2066         bool "Ignore USER SUSPEND"
2067         ---help---
2068           This option will ignore USER SUSPEND requests. On machines with a
2069           compliant APM BIOS, you want to say N. However, on the NEC Versa M
2070           series notebooks, it is necessary to say Y because of a BIOS bug.
2071 
2072 config APM_DO_ENABLE
2073         bool "Enable PM at boot time"
2074         ---help---
2075           Enable APM features at boot time. From page 36 of the APM BIOS
2076           specification: "When disabled, the APM BIOS does not automatically
2077           power manage devices, enter the Standby State, enter the Suspend
2078           State, or take power saving steps in response to CPU Idle calls."
2079           This driver will make CPU Idle calls when Linux is idle (unless this
2080           feature is turned off -- see "Do CPU IDLE calls", below). This
2081           should always save battery power, but more complicated APM features
2082           will be dependent on your BIOS implementation. You may need to turn
2083           this option off if your computer hangs at boot time when using APM
2084           support, or if it beeps continuously instead of suspending. Turn
2085           this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2086           T400CDT. This is off by default since most machines do fine without
2087           this feature.
2088 
2089 config APM_CPU_IDLE
2090         depends on CPU_IDLE
2091         bool "Make CPU Idle calls when idle"
2092         ---help---
2093           Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2094           On some machines, this can activate improved power savings, such as
2095           a slowed CPU clock rate, when the machine is idle. These idle calls
2096           are made after the idle loop has run for some length of time (e.g.,
2097           333 mS). On some machines, this will cause a hang at boot time or
2098           whenever the CPU becomes idle. (On machines with more than one CPU,
2099           this option does nothing.)
2100 
2101 config APM_DISPLAY_BLANK
2102         bool "Enable console blanking using APM"
2103         ---help---
2104           Enable console blanking using the APM. Some laptops can use this to
2105           turn off the LCD backlight when the screen blanker of the Linux
2106           virtual console blanks the screen. Note that this is only used by
2107           the virtual console screen blanker, and won't turn off the backlight
2108           when using the X Window system. This also doesn't have anything to
2109           do with your VESA-compliant power-saving monitor. Further, this
2110           option doesn't work for all laptops -- it might not turn off your
2111           backlight at all, or it might print a lot of errors to the console,
2112           especially if you are using gpm.
2113 
2114 config APM_ALLOW_INTS
2115         bool "Allow interrupts during APM BIOS calls"
2116         ---help---
2117           Normally we disable external interrupts while we are making calls to
2118           the APM BIOS as a measure to lessen the effects of a badly behaving
2119           BIOS implementation.  The BIOS should reenable interrupts if it
2120           needs to.  Unfortunately, some BIOSes do not -- especially those in
2121           many of the newer IBM Thinkpads.  If you experience hangs when you
2122           suspend, try setting this to Y.  Otherwise, say N.
2123 
2124 endif # APM
2125 
2126 source "drivers/cpufreq/Kconfig"
2127 
2128 source "drivers/cpuidle/Kconfig"
2129 
2130 source "drivers/idle/Kconfig"
2131 
2132 endmenu
2133 
2134 
2135 menu "Bus options (PCI etc.)"
2136 
2137 config PCI
2138         bool "PCI support"
2139         default y
2140         ---help---
2141           Find out whether you have a PCI motherboard. PCI is the name of a
2142           bus system, i.e. the way the CPU talks to the other stuff inside
2143           your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2144           VESA. If you have PCI, say Y, otherwise N.
2145 
2146 choice
2147         prompt "PCI access mode"
2148         depends on X86_32 && PCI
2149         default PCI_GOANY
2150         ---help---
2151           On PCI systems, the BIOS can be used to detect the PCI devices and
2152           determine their configuration. However, some old PCI motherboards
2153           have BIOS bugs and may crash if this is done. Also, some embedded
2154           PCI-based systems don't have any BIOS at all. Linux can also try to
2155           detect the PCI hardware directly without using the BIOS.
2156 
2157           With this option, you can specify how Linux should detect the
2158           PCI devices. If you choose "BIOS", the BIOS will be used,
2159           if you choose "Direct", the BIOS won't be used, and if you
2160           choose "MMConfig", then PCI Express MMCONFIG will be used.
2161           If you choose "Any", the kernel will try MMCONFIG, then the
2162           direct access method and falls back to the BIOS if that doesn't
2163           work. If unsure, go with the default, which is "Any".
2164 
2165 config PCI_GOBIOS
2166         bool "BIOS"
2167 
2168 config PCI_GOMMCONFIG
2169         bool "MMConfig"
2170 
2171 config PCI_GODIRECT
2172         bool "Direct"
2173 
2174 config PCI_GOOLPC
2175         bool "OLPC XO-1"
2176         depends on OLPC
2177 
2178 config PCI_GOANY
2179         bool "Any"
2180 
2181 endchoice
2182 
2183 config PCI_BIOS
2184         def_bool y
2185         depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2186 
2187 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2188 config PCI_DIRECT
2189         def_bool y
2190         depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2191 
2192 config PCI_MMCONFIG
2193         def_bool y
2194         depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2195 
2196 config PCI_OLPC
2197         def_bool y
2198         depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2199 
2200 config PCI_XEN
2201         def_bool y
2202         depends on PCI && XEN
2203         select SWIOTLB_XEN
2204 
2205 config PCI_DOMAINS
2206         def_bool y
2207         depends on PCI
2208 
2209 config PCI_MMCONFIG
2210         bool "Support mmconfig PCI config space access"
2211         depends on X86_64 && PCI && ACPI
2212 
2213 config PCI_CNB20LE_QUIRK
2214         bool "Read CNB20LE Host Bridge Windows" if EXPERT
2215         depends on PCI
2216         help
2217           Read the PCI windows out of the CNB20LE host bridge. This allows
2218           PCI hotplug to work on systems with the CNB20LE chipset which do
2219           not have ACPI.
2220 
2221           There's no public spec for this chipset, and this functionality
2222           is known to be incomplete.
2223 
2224           You should say N unless you know you need this.
2225 
2226 source "drivers/pci/pcie/Kconfig"
2227 
2228 source "drivers/pci/Kconfig"
2229 
2230 # x86_64 have no ISA slots, but can have ISA-style DMA.
2231 config ISA_DMA_API
2232         bool "ISA-style DMA support" if (X86_64 && EXPERT)
2233         default y
2234         help
2235           Enables ISA-style DMA support for devices requiring such controllers.
2236           If unsure, say Y.
2237 
2238 if X86_32
2239 
2240 config ISA
2241         bool "ISA support"
2242         ---help---
2243           Find out whether you have ISA slots on your motherboard.  ISA is the
2244           name of a bus system, i.e. the way the CPU talks to the other stuff
2245           inside your box.  Other bus systems are PCI, EISA, MicroChannel
2246           (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2247           newer boards don't support it.  If you have ISA, say Y, otherwise N.
2248 
2249 config EISA
2250         bool "EISA support"
2251         depends on ISA
2252         ---help---
2253           The Extended Industry Standard Architecture (EISA) bus was
2254           developed as an open alternative to the IBM MicroChannel bus.
2255 
2256           The EISA bus provided some of the features of the IBM MicroChannel
2257           bus while maintaining backward compatibility with cards made for
2258           the older ISA bus.  The EISA bus saw limited use between 1988 and
2259           1995 when it was made obsolete by the PCI bus.
2260 
2261           Say Y here if you are building a kernel for an EISA-based machine.
2262 
2263           Otherwise, say N.
2264 
2265 source "drivers/eisa/Kconfig"
2266 
2267 config SCx200
2268         tristate "NatSemi SCx200 support"
2269         ---help---
2270           This provides basic support for National Semiconductor's
2271           (now AMD's) Geode processors.  The driver probes for the
2272           PCI-IDs of several on-chip devices, so its a good dependency
2273           for other scx200_* drivers.
2274 
2275           If compiled as a module, the driver is named scx200.
2276 
2277 config SCx200HR_TIMER
2278         tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2279         depends on SCx200
2280         default y
2281         ---help---
2282           This driver provides a clocksource built upon the on-chip
2283           27MHz high-resolution timer.  Its also a workaround for
2284           NSC Geode SC-1100's buggy TSC, which loses time when the
2285           processor goes idle (as is done by the scheduler).  The
2286           other workaround is idle=poll boot option.
2287 
2288 config OLPC
2289         bool "One Laptop Per Child support"
2290         depends on !X86_PAE
2291         select GPIOLIB
2292         select OF
2293         select OF_PROMTREE
2294         select IRQ_DOMAIN
2295         ---help---
2296           Add support for detecting the unique features of the OLPC
2297           XO hardware.
2298 
2299 config OLPC_XO1_PM
2300         bool "OLPC XO-1 Power Management"
2301         depends on OLPC && MFD_CS5535 && PM_SLEEP
2302         select MFD_CORE
2303         ---help---
2304           Add support for poweroff and suspend of the OLPC XO-1 laptop.
2305 
2306 config OLPC_XO1_RTC
2307         bool "OLPC XO-1 Real Time Clock"
2308         depends on OLPC_XO1_PM && RTC_DRV_CMOS
2309         ---help---
2310           Add support for the XO-1 real time clock, which can be used as a
2311           programmable wakeup source.
2312 
2313 config OLPC_XO1_SCI
2314         bool "OLPC XO-1 SCI extras"
2315         depends on OLPC && OLPC_XO1_PM
2316         depends on INPUT=y
2317         select POWER_SUPPLY
2318         select GPIO_CS5535
2319         select MFD_CORE
2320         ---help---
2321           Add support for SCI-based features of the OLPC XO-1 laptop:
2322            - EC-driven system wakeups
2323            - Power button
2324            - Ebook switch
2325            - Lid switch
2326            - AC adapter status updates
2327            - Battery status updates
2328 
2329 config OLPC_XO15_SCI
2330         bool "OLPC XO-1.5 SCI extras"
2331         depends on OLPC && ACPI
2332         select POWER_SUPPLY
2333         ---help---
2334           Add support for SCI-based features of the OLPC XO-1.5 laptop:
2335            - EC-driven system wakeups
2336            - AC adapter status updates
2337            - Battery status updates
2338 
2339 config ALIX
2340         bool "PCEngines ALIX System Support (LED setup)"
2341         select GPIOLIB
2342         ---help---
2343           This option enables system support for the PCEngines ALIX.
2344           At present this just sets up LEDs for GPIO control on
2345           ALIX2/3/6 boards.  However, other system specific setup should
2346           get added here.
2347 
2348           Note: You must still enable the drivers for GPIO and LED support
2349           (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2350 
2351           Note: You have to set alix.force=1 for boards with Award BIOS.
2352 
2353 config NET5501
2354         bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2355         select GPIOLIB
2356         ---help---
2357           This option enables system support for the Soekris Engineering net5501.
2358 
2359 config GEOS
2360         bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2361         select GPIOLIB
2362         depends on DMI
2363         ---help---
2364           This option enables system support for the Traverse Technologies GEOS.
2365 
2366 config TS5500
2367         bool "Technologic Systems TS-5500 platform support"
2368         depends on MELAN
2369         select CHECK_SIGNATURE
2370         select NEW_LEDS
2371         select LEDS_CLASS
2372         ---help---
2373           This option enables system support for the Technologic Systems TS-5500.
2374 
2375 endif # X86_32
2376 
2377 config AMD_NB
2378         def_bool y
2379         depends on CPU_SUP_AMD && PCI
2380 
2381 source "drivers/pcmcia/Kconfig"
2382 
2383 source "drivers/pci/hotplug/Kconfig"
2384 
2385 config RAPIDIO
2386         tristate "RapidIO support"
2387         depends on PCI
2388         default n
2389         help
2390           If enabled this option will include drivers and the core
2391           infrastructure code to support RapidIO interconnect devices.
2392 
2393 source "drivers/rapidio/Kconfig"
2394 
2395 config X86_SYSFB
2396         bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2397         help
2398           Firmwares often provide initial graphics framebuffers so the BIOS,
2399           bootloader or kernel can show basic video-output during boot for
2400           user-guidance and debugging. Historically, x86 used the VESA BIOS
2401           Extensions and EFI-framebuffers for this, which are mostly limited
2402           to x86.
2403           This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2404           framebuffers so the new generic system-framebuffer drivers can be
2405           used on x86. If the framebuffer is not compatible with the generic
2406           modes, it is adverticed as fallback platform framebuffer so legacy
2407           drivers like efifb, vesafb and uvesafb can pick it up.
2408           If this option is not selected, all system framebuffers are always
2409           marked as fallback platform framebuffers as usual.
2410 
2411           Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2412           not be able to pick up generic system framebuffers if this option
2413           is selected. You are highly encouraged to enable simplefb as
2414           replacement if you select this option. simplefb can correctly deal
2415           with generic system framebuffers. But you should still keep vesafb
2416           and others enabled as fallback if a system framebuffer is
2417           incompatible with simplefb.
2418 
2419           If unsure, say Y.
2420 
2421 endmenu
2422 
2423 
2424 menu "Executable file formats / Emulations"
2425 
2426 source "fs/Kconfig.binfmt"
2427 
2428 config IA32_EMULATION
2429         bool "IA32 Emulation"
2430         depends on X86_64
2431         select BINFMT_ELF
2432         select COMPAT_BINFMT_ELF
2433         select HAVE_UID16
2434         ---help---
2435           Include code to run legacy 32-bit programs under a
2436           64-bit kernel. You should likely turn this on, unless you're
2437           100% sure that you don't have any 32-bit programs left.
2438 
2439 config IA32_AOUT
2440         tristate "IA32 a.out support"
2441         depends on IA32_EMULATION
2442         ---help---
2443           Support old a.out binaries in the 32bit emulation.
2444 
2445 config X86_X32
2446         bool "x32 ABI for 64-bit mode"
2447         depends on X86_64 && IA32_EMULATION
2448         ---help---
2449           Include code to run binaries for the x32 native 32-bit ABI
2450           for 64-bit processors.  An x32 process gets access to the
2451           full 64-bit register file and wide data path while leaving
2452           pointers at 32 bits for smaller memory footprint.
2453 
2454           You will need a recent binutils (2.22 or later) with
2455           elf32_x86_64 support enabled to compile a kernel with this
2456           option set.
2457 
2458 config COMPAT
2459         def_bool y
2460         depends on IA32_EMULATION || X86_X32
2461         select ARCH_WANT_OLD_COMPAT_IPC
2462 
2463 if COMPAT
2464 config COMPAT_FOR_U64_ALIGNMENT
2465         def_bool y
2466 
2467 config SYSVIPC_COMPAT
2468         def_bool y
2469         depends on SYSVIPC
2470 
2471 config KEYS_COMPAT
2472         def_bool y
2473         depends on KEYS
2474 endif
2475 
2476 endmenu
2477 
2478 
2479 config HAVE_ATOMIC_IOMAP
2480         def_bool y
2481         depends on X86_32
2482 
2483 config X86_DEV_DMA_OPS
2484         bool
2485         depends on X86_64 || STA2X11
2486 
2487 config X86_DMA_REMAP
2488         bool
2489         depends on STA2X11
2490 
2491 config PMC_ATOM
2492         def_bool y
2493         depends on PCI
2494 
2495 source "net/Kconfig"
2496 
2497 source "drivers/Kconfig"
2498 
2499 source "drivers/firmware/Kconfig"
2500 
2501 source "fs/Kconfig"
2502 
2503 source "arch/x86/Kconfig.debug"
2504 
2505 source "security/Kconfig"
2506 
2507 source "crypto/Kconfig"
2508 
2509 source "arch/x86/kvm/Kconfig"
2510 
2511 source "lib/Kconfig"

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