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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         select HAVE_LIVEPATCH
 21 
 22 ### Arch settings
 23 config X86
 24         def_bool y
 25         select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
 26         select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
 27         select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
 28         select ARCH_HAS_FAST_MULTIPLIER
 29         select ARCH_HAS_GCOV_PROFILE_ALL
 30         select ARCH_MIGHT_HAVE_PC_PARPORT
 31         select ARCH_MIGHT_HAVE_PC_SERIO
 32         select HAVE_AOUT if X86_32
 33         select HAVE_UNSTABLE_SCHED_CLOCK
 34         select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
 35         select ARCH_SUPPORTS_INT128 if X86_64
 36         select HAVE_IDE
 37         select HAVE_OPROFILE
 38         select HAVE_PCSPKR_PLATFORM
 39         select HAVE_PERF_EVENTS
 40         select HAVE_IOREMAP_PROT
 41         select HAVE_KPROBES
 42         select HAVE_MEMBLOCK
 43         select HAVE_MEMBLOCK_NODE_MAP
 44         select ARCH_DISCARD_MEMBLOCK
 45         select ARCH_WANT_OPTIONAL_GPIOLIB
 46         select ARCH_WANT_FRAME_POINTERS
 47         select HAVE_DMA_ATTRS
 48         select HAVE_DMA_CONTIGUOUS
 49         select HAVE_KRETPROBES
 50         select GENERIC_EARLY_IOREMAP
 51         select HAVE_OPTPROBES
 52         select HAVE_KPROBES_ON_FTRACE
 53         select HAVE_FTRACE_MCOUNT_RECORD
 54         select HAVE_FENTRY if X86_64
 55         select HAVE_C_RECORDMCOUNT
 56         select HAVE_DYNAMIC_FTRACE
 57         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 58         select HAVE_FUNCTION_TRACER
 59         select HAVE_FUNCTION_GRAPH_TRACER
 60         select HAVE_FUNCTION_GRAPH_FP_TEST
 61         select HAVE_SYSCALL_TRACEPOINTS
 62         select SYSCTL_EXCEPTION_TRACE
 63         select HAVE_KVM
 64         select HAVE_ARCH_KGDB
 65         select HAVE_ARCH_TRACEHOOK
 66         select HAVE_GENERIC_DMA_COHERENT if X86_32
 67         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 68         select USER_STACKTRACE_SUPPORT
 69         select HAVE_REGS_AND_STACK_ACCESS_API
 70         select HAVE_DMA_API_DEBUG
 71         select HAVE_KERNEL_GZIP
 72         select HAVE_KERNEL_BZIP2
 73         select HAVE_KERNEL_LZMA
 74         select HAVE_KERNEL_XZ
 75         select HAVE_KERNEL_LZO
 76         select HAVE_KERNEL_LZ4
 77         select HAVE_HW_BREAKPOINT
 78         select HAVE_MIXED_BREAKPOINTS_REGS
 79         select PERF_EVENTS
 80         select HAVE_PERF_EVENTS_NMI
 81         select HAVE_PERF_REGS
 82         select HAVE_PERF_USER_STACK_DUMP
 83         select HAVE_DEBUG_KMEMLEAK
 84         select ANON_INODES
 85         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 86         select HAVE_CMPXCHG_LOCAL
 87         select HAVE_CMPXCHG_DOUBLE
 88         select HAVE_ARCH_KMEMCHECK
 89         select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
 90         select HAVE_USER_RETURN_NOTIFIER
 91         select ARCH_HAS_ELF_RANDOMIZE
 92         select HAVE_ARCH_JUMP_LABEL
 93         select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 94         select SPARSE_IRQ
 95         select GENERIC_FIND_FIRST_BIT
 96         select GENERIC_IRQ_PROBE
 97         select GENERIC_PENDING_IRQ if SMP
 98         select GENERIC_IRQ_SHOW
 99         select GENERIC_CLOCKEVENTS_MIN_ADJUST
100         select IRQ_FORCED_THREADING
101         select HAVE_BPF_JIT if X86_64
102         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
103         select HAVE_ARCH_HUGE_VMAP if X86_64 || (X86_32 && X86_PAE)
104         select ARCH_HAS_SG_CHAIN
105         select CLKEVT_I8253
106         select ARCH_HAVE_NMI_SAFE_CMPXCHG
107         select GENERIC_IOMAP
108         select DCACHE_WORD_ACCESS
109         select GENERIC_SMP_IDLE_THREAD
110         select ARCH_WANT_IPC_PARSE_VERSION if X86_32
111         select HAVE_ARCH_SECCOMP_FILTER
112         select BUILDTIME_EXTABLE_SORT
113         select GENERIC_CMOS_UPDATE
114         select HAVE_ARCH_SOFT_DIRTY if X86_64
115         select CLOCKSOURCE_WATCHDOG
116         select GENERIC_CLOCKEVENTS
117         select ARCH_CLOCKSOURCE_DATA
118         select CLOCKSOURCE_VALIDATE_LAST_CYCLE
119         select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
120         select GENERIC_TIME_VSYSCALL
121         select GENERIC_STRNCPY_FROM_USER
122         select GENERIC_STRNLEN_USER
123         select HAVE_CONTEXT_TRACKING if X86_64
124         select HAVE_IRQ_TIME_ACCOUNTING
125         select VIRT_TO_BUS
126         select MODULES_USE_ELF_REL if X86_32
127         select MODULES_USE_ELF_RELA if X86_64
128         select CLONE_BACKWARDS if X86_32
129         select ARCH_USE_BUILTIN_BSWAP
130         select ARCH_USE_QUEUE_RWLOCK
131         select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
132         select OLD_SIGACTION if X86_32
133         select COMPAT_OLD_SIGACTION if IA32_EMULATION
134         select RTC_LIB
135         select HAVE_DEBUG_STACKOVERFLOW
136         select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
137         select HAVE_CC_STACKPROTECTOR
138         select GENERIC_CPU_AUTOPROBE
139         select HAVE_ARCH_AUDITSYSCALL
140         select ARCH_SUPPORTS_ATOMIC_RMW
141         select HAVE_ACPI_APEI if ACPI
142         select HAVE_ACPI_APEI_NMI if ACPI
143         select ACPI_LEGACY_TABLES_LOOKUP if ACPI
144         select X86_FEATURE_NAMES if PROC_FS
145         select SRCU
146 
147 config INSTRUCTION_DECODER
148         def_bool y
149         depends on KPROBES || PERF_EVENTS || UPROBES
150 
151 config PERF_EVENTS_INTEL_UNCORE
152         def_bool y
153         depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
154 
155 config OUTPUT_FORMAT
156         string
157         default "elf32-i386" if X86_32
158         default "elf64-x86-64" if X86_64
159 
160 config ARCH_DEFCONFIG
161         string
162         default "arch/x86/configs/i386_defconfig" if X86_32
163         default "arch/x86/configs/x86_64_defconfig" if X86_64
164 
165 config LOCKDEP_SUPPORT
166         def_bool y
167 
168 config STACKTRACE_SUPPORT
169         def_bool y
170 
171 config HAVE_LATENCYTOP_SUPPORT
172         def_bool y
173 
174 config MMU
175         def_bool y
176 
177 config SBUS
178         bool
179 
180 config NEED_DMA_MAP_STATE
181         def_bool y
182         depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
183 
184 config NEED_SG_DMA_LENGTH
185         def_bool y
186 
187 config GENERIC_ISA_DMA
188         def_bool y
189         depends on ISA_DMA_API
190 
191 config GENERIC_BUG
192         def_bool y
193         depends on BUG
194         select GENERIC_BUG_RELATIVE_POINTERS if X86_64
195 
196 config GENERIC_BUG_RELATIVE_POINTERS
197         bool
198 
199 config GENERIC_HWEIGHT
200         def_bool y
201 
202 config ARCH_MAY_HAVE_PC_FDC
203         def_bool y
204         depends on ISA_DMA_API
205 
206 config RWSEM_XCHGADD_ALGORITHM
207         def_bool y
208 
209 config GENERIC_CALIBRATE_DELAY
210         def_bool y
211 
212 config ARCH_HAS_CPU_RELAX
213         def_bool y
214 
215 config ARCH_HAS_CACHE_LINE_SIZE
216         def_bool y
217 
218 config HAVE_SETUP_PER_CPU_AREA
219         def_bool y
220 
221 config NEED_PER_CPU_EMBED_FIRST_CHUNK
222         def_bool y
223 
224 config NEED_PER_CPU_PAGE_FIRST_CHUNK
225         def_bool y
226 
227 config ARCH_HIBERNATION_POSSIBLE
228         def_bool y
229 
230 config ARCH_SUSPEND_POSSIBLE
231         def_bool y
232 
233 config ARCH_WANT_HUGE_PMD_SHARE
234         def_bool y
235 
236 config ARCH_WANT_GENERAL_HUGETLB
237         def_bool y
238 
239 config ZONE_DMA32
240         def_bool y if X86_64
241 
242 config AUDIT_ARCH
243         def_bool y if X86_64
244 
245 config ARCH_SUPPORTS_OPTIMIZED_INLINING
246         def_bool y
247 
248 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
249         def_bool y
250 
251 config HAVE_INTEL_TXT
252         def_bool y
253         depends on INTEL_IOMMU && ACPI
254 
255 config X86_32_SMP
256         def_bool y
257         depends on X86_32 && SMP
258 
259 config X86_64_SMP
260         def_bool y
261         depends on X86_64 && SMP
262 
263 config X86_HT
264         def_bool y
265         depends on SMP
266 
267 config X86_32_LAZY_GS
268         def_bool y
269         depends on X86_32 && !CC_STACKPROTECTOR
270 
271 config ARCH_HWEIGHT_CFLAGS
272         string
273         default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
274         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
275 
276 config ARCH_SUPPORTS_UPROBES
277         def_bool y
278 
279 config FIX_EARLYCON_MEM
280         def_bool y
281 
282 config PGTABLE_LEVELS
283         int
284         default 4 if X86_64
285         default 3 if X86_PAE
286         default 2
287 
288 source "init/Kconfig"
289 source "kernel/Kconfig.freezer"
290 
291 menu "Processor type and features"
292 
293 config ZONE_DMA
294         bool "DMA memory allocation support" if EXPERT
295         default y
296         help
297           DMA memory allocation support allows devices with less than 32-bit
298           addressing to allocate within the first 16MB of address space.
299           Disable if no such devices will be used.
300 
301           If unsure, say Y.
302 
303 config SMP
304         bool "Symmetric multi-processing support"
305         ---help---
306           This enables support for systems with more than one CPU. If you have
307           a system with only one CPU, say N. If you have a system with more
308           than one CPU, say Y.
309 
310           If you say N here, the kernel will run on uni- and multiprocessor
311           machines, but will use only one CPU of a multiprocessor machine. If
312           you say Y here, the kernel will run on many, but not all,
313           uniprocessor machines. On a uniprocessor machine, the kernel
314           will run faster if you say N here.
315 
316           Note that if you say Y here and choose architecture "586" or
317           "Pentium" under "Processor family", the kernel will not work on 486
318           architectures. Similarly, multiprocessor kernels for the "PPro"
319           architecture may not work on all Pentium based boards.
320 
321           People using multiprocessor machines who say Y here should also say
322           Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
323           Management" code will be disabled if you say Y here.
324 
325           See also <file:Documentation/x86/i386/IO-APIC.txt>,
326           <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
327           <http://www.tldp.org/docs.html#howto>.
328 
329           If you don't know what to do here, say N.
330 
331 config X86_FEATURE_NAMES
332         bool "Processor feature human-readable names" if EMBEDDED
333         default y
334         ---help---
335           This option compiles in a table of x86 feature bits and corresponding
336           names.  This is required to support /proc/cpuinfo and a few kernel
337           messages.  You can disable this to save space, at the expense of
338           making those few kernel messages show numeric feature bits instead.
339 
340           If in doubt, say Y.
341 
342 config X86_X2APIC
343         bool "Support x2apic"
344         depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
345         ---help---
346           This enables x2apic support on CPUs that have this feature.
347 
348           This allows 32-bit apic IDs (so it can support very large systems),
349           and accesses the local apic via MSRs not via mmio.
350 
351           If you don't know what to do here, say N.
352 
353 config X86_MPPARSE
354         bool "Enable MPS table" if ACPI || SFI
355         default y
356         depends on X86_LOCAL_APIC
357         ---help---
358           For old smp systems that do not have proper acpi support. Newer systems
359           (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
360 
361 config X86_BIGSMP
362         bool "Support for big SMP systems with more than 8 CPUs"
363         depends on X86_32 && SMP
364         ---help---
365           This option is needed for the systems that have more than 8 CPUs
366 
367 config GOLDFISH
368        def_bool y
369        depends on X86_GOLDFISH
370 
371 if X86_32
372 config X86_EXTENDED_PLATFORM
373         bool "Support for extended (non-PC) x86 platforms"
374         default y
375         ---help---
376           If you disable this option then the kernel will only support
377           standard PC platforms. (which covers the vast majority of
378           systems out there.)
379 
380           If you enable this option then you'll be able to select support
381           for the following (non-PC) 32 bit x86 platforms:
382                 Goldfish (Android emulator)
383                 AMD Elan
384                 RDC R-321x SoC
385                 SGI 320/540 (Visual Workstation)
386                 STA2X11-based (e.g. Northville)
387                 Moorestown MID devices
388 
389           If you have one of these systems, or if you want to build a
390           generic distribution kernel, say Y here - otherwise say N.
391 endif
392 
393 if X86_64
394 config X86_EXTENDED_PLATFORM
395         bool "Support for extended (non-PC) x86 platforms"
396         default y
397         ---help---
398           If you disable this option then the kernel will only support
399           standard PC platforms. (which covers the vast majority of
400           systems out there.)
401 
402           If you enable this option then you'll be able to select support
403           for the following (non-PC) 64 bit x86 platforms:
404                 Numascale NumaChip
405                 ScaleMP vSMP
406                 SGI Ultraviolet
407 
408           If you have one of these systems, or if you want to build a
409           generic distribution kernel, say Y here - otherwise say N.
410 endif
411 # This is an alphabetically sorted list of 64 bit extended platforms
412 # Please maintain the alphabetic order if and when there are additions
413 config X86_NUMACHIP
414         bool "Numascale NumaChip"
415         depends on X86_64
416         depends on X86_EXTENDED_PLATFORM
417         depends on NUMA
418         depends on SMP
419         depends on X86_X2APIC
420         depends on PCI_MMCONFIG
421         ---help---
422           Adds support for Numascale NumaChip large-SMP systems. Needed to
423           enable more than ~168 cores.
424           If you don't have one of these, you should say N here.
425 
426 config X86_VSMP
427         bool "ScaleMP vSMP"
428         select HYPERVISOR_GUEST
429         select PARAVIRT
430         depends on X86_64 && PCI
431         depends on X86_EXTENDED_PLATFORM
432         depends on SMP
433         ---help---
434           Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
435           supposed to run on these EM64T-based machines.  Only choose this option
436           if you have one of these machines.
437 
438 config X86_UV
439         bool "SGI Ultraviolet"
440         depends on X86_64
441         depends on X86_EXTENDED_PLATFORM
442         depends on NUMA
443         depends on X86_X2APIC
444         ---help---
445           This option is needed in order to support SGI Ultraviolet systems.
446           If you don't have one of these, you should say N here.
447 
448 # Following is an alphabetically sorted list of 32 bit extended platforms
449 # Please maintain the alphabetic order if and when there are additions
450 
451 config X86_GOLDFISH
452        bool "Goldfish (Virtual Platform)"
453        depends on X86_EXTENDED_PLATFORM
454        ---help---
455          Enable support for the Goldfish virtual platform used primarily
456          for Android development. Unless you are building for the Android
457          Goldfish emulator say N here.
458 
459 config X86_INTEL_CE
460         bool "CE4100 TV platform"
461         depends on PCI
462         depends on PCI_GODIRECT
463         depends on X86_IO_APIC
464         depends on X86_32
465         depends on X86_EXTENDED_PLATFORM
466         select X86_REBOOTFIXUPS
467         select OF
468         select OF_EARLY_FLATTREE
469         select IRQ_DOMAIN
470         ---help---
471           Select for the Intel CE media processor (CE4100) SOC.
472           This option compiles in support for the CE4100 SOC for settop
473           boxes and media devices.
474 
475 config X86_INTEL_MID
476         bool "Intel MID platform support"
477         depends on X86_32
478         depends on X86_EXTENDED_PLATFORM
479         depends on X86_PLATFORM_DEVICES
480         depends on PCI
481         depends on PCI_GOANY
482         depends on X86_IO_APIC
483         select SFI
484         select I2C
485         select DW_APB_TIMER
486         select APB_TIMER
487         select INTEL_SCU_IPC
488         select MFD_INTEL_MSIC
489         ---help---
490           Select to build a kernel capable of supporting Intel MID (Mobile
491           Internet Device) platform systems which do not have the PCI legacy
492           interfaces. If you are building for a PC class system say N here.
493 
494           Intel MID platforms are based on an Intel processor and chipset which
495           consume less power than most of the x86 derivatives.
496 
497 config X86_INTEL_QUARK
498         bool "Intel Quark platform support"
499         depends on X86_32
500         depends on X86_EXTENDED_PLATFORM
501         depends on X86_PLATFORM_DEVICES
502         depends on X86_TSC
503         depends on PCI
504         depends on PCI_GOANY
505         depends on X86_IO_APIC
506         select IOSF_MBI
507         select INTEL_IMR
508         select COMMON_CLK
509         ---help---
510           Select to include support for Quark X1000 SoC.
511           Say Y here if you have a Quark based system such as the Arduino
512           compatible Intel Galileo.
513 
514 config X86_INTEL_LPSS
515         bool "Intel Low Power Subsystem Support"
516         depends on ACPI
517         select COMMON_CLK
518         select PINCTRL
519         ---help---
520           Select to build support for Intel Low Power Subsystem such as
521           found on Intel Lynxpoint PCH. Selecting this option enables
522           things like clock tree (common clock framework) and pincontrol
523           which are needed by the LPSS peripheral drivers.
524 
525 config X86_AMD_PLATFORM_DEVICE
526         bool "AMD ACPI2Platform devices support"
527         depends on ACPI
528         select COMMON_CLK
529         select PINCTRL
530         ---help---
531           Select to interpret AMD specific ACPI device to platform device
532           such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
533           I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
534           implemented under PINCTRL subsystem.
535 
536 config IOSF_MBI
537         tristate "Intel SoC IOSF Sideband support for SoC platforms"
538         depends on PCI
539         ---help---
540           This option enables sideband register access support for Intel SoC
541           platforms. On these platforms the IOSF sideband is used in lieu of
542           MSR's for some register accesses, mostly but not limited to thermal
543           and power. Drivers may query the availability of this device to
544           determine if they need the sideband in order to work on these
545           platforms. The sideband is available on the following SoC products.
546           This list is not meant to be exclusive.
547            - BayTrail
548            - Braswell
549            - Quark
550 
551           You should say Y if you are running a kernel on one of these SoC's.
552 
553 config IOSF_MBI_DEBUG
554         bool "Enable IOSF sideband access through debugfs"
555         depends on IOSF_MBI && DEBUG_FS
556         ---help---
557           Select this option to expose the IOSF sideband access registers (MCR,
558           MDR, MCRX) through debugfs to write and read register information from
559           different units on the SoC. This is most useful for obtaining device
560           state information for debug and analysis. As this is a general access
561           mechanism, users of this option would have specific knowledge of the
562           device they want to access.
563 
564           If you don't require the option or are in doubt, say N.
565 
566 config X86_RDC321X
567         bool "RDC R-321x SoC"
568         depends on X86_32
569         depends on X86_EXTENDED_PLATFORM
570         select M486
571         select X86_REBOOTFIXUPS
572         ---help---
573           This option is needed for RDC R-321x system-on-chip, also known
574           as R-8610-(G).
575           If you don't have one of these chips, you should say N here.
576 
577 config X86_32_NON_STANDARD
578         bool "Support non-standard 32-bit SMP architectures"
579         depends on X86_32 && SMP
580         depends on X86_EXTENDED_PLATFORM
581         ---help---
582           This option compiles in the bigsmp and STA2X11 default
583           subarchitectures.  It is intended for a generic binary
584           kernel. If you select them all, kernel will probe it one by
585           one and will fallback to default.
586 
587 # Alphabetically sorted list of Non standard 32 bit platforms
588 
589 config X86_SUPPORTS_MEMORY_FAILURE
590         def_bool y
591         # MCE code calls memory_failure():
592         depends on X86_MCE
593         # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
594         # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
595         depends on X86_64 || !SPARSEMEM
596         select ARCH_SUPPORTS_MEMORY_FAILURE
597 
598 config STA2X11
599         bool "STA2X11 Companion Chip Support"
600         depends on X86_32_NON_STANDARD && PCI
601         select X86_DEV_DMA_OPS
602         select X86_DMA_REMAP
603         select SWIOTLB
604         select MFD_STA2X11
605         select ARCH_REQUIRE_GPIOLIB
606         default n
607         ---help---
608           This adds support for boards based on the STA2X11 IO-Hub,
609           a.k.a. "ConneXt". The chip is used in place of the standard
610           PC chipset, so all "standard" peripherals are missing. If this
611           option is selected the kernel will still be able to boot on
612           standard PC machines.
613 
614 config X86_32_IRIS
615         tristate "Eurobraille/Iris poweroff module"
616         depends on X86_32
617         ---help---
618           The Iris machines from EuroBraille do not have APM or ACPI support
619           to shut themselves down properly.  A special I/O sequence is
620           needed to do so, which is what this module does at
621           kernel shutdown.
622 
623           This is only for Iris machines from EuroBraille.
624 
625           If unused, say N.
626 
627 config SCHED_OMIT_FRAME_POINTER
628         def_bool y
629         prompt "Single-depth WCHAN output"
630         depends on X86
631         ---help---
632           Calculate simpler /proc/<PID>/wchan values. If this option
633           is disabled then wchan values will recurse back to the
634           caller function. This provides more accurate wchan values,
635           at the expense of slightly more scheduling overhead.
636 
637           If in doubt, say "Y".
638 
639 menuconfig HYPERVISOR_GUEST
640         bool "Linux guest support"
641         ---help---
642           Say Y here to enable options for running Linux under various hyper-
643           visors. This option enables basic hypervisor detection and platform
644           setup.
645 
646           If you say N, all options in this submenu will be skipped and
647           disabled, and Linux guest support won't be built in.
648 
649 if HYPERVISOR_GUEST
650 
651 config PARAVIRT
652         bool "Enable paravirtualization code"
653         ---help---
654           This changes the kernel so it can modify itself when it is run
655           under a hypervisor, potentially improving performance significantly
656           over full virtualization.  However, when run without a hypervisor
657           the kernel is theoretically slower and slightly larger.
658 
659 config PARAVIRT_DEBUG
660         bool "paravirt-ops debugging"
661         depends on PARAVIRT && DEBUG_KERNEL
662         ---help---
663           Enable to debug paravirt_ops internals.  Specifically, BUG if
664           a paravirt_op is missing when it is called.
665 
666 config PARAVIRT_SPINLOCKS
667         bool "Paravirtualization layer for spinlocks"
668         depends on PARAVIRT && SMP
669         select UNINLINE_SPIN_UNLOCK
670         ---help---
671           Paravirtualized spinlocks allow a pvops backend to replace the
672           spinlock implementation with something virtualization-friendly
673           (for example, block the virtual CPU rather than spinning).
674 
675           It has a minimal impact on native kernels and gives a nice performance
676           benefit on paravirtualized KVM / Xen kernels.
677 
678           If you are unsure how to answer this question, answer Y.
679 
680 source "arch/x86/xen/Kconfig"
681 
682 config KVM_GUEST
683         bool "KVM Guest support (including kvmclock)"
684         depends on PARAVIRT
685         select PARAVIRT_CLOCK
686         default y
687         ---help---
688           This option enables various optimizations for running under the KVM
689           hypervisor. It includes a paravirtualized clock, so that instead
690           of relying on a PIT (or probably other) emulation by the
691           underlying device model, the host provides the guest with
692           timing infrastructure such as time of day, and system time
693 
694 config KVM_DEBUG_FS
695         bool "Enable debug information for KVM Guests in debugfs"
696         depends on KVM_GUEST && DEBUG_FS
697         default n
698         ---help---
699           This option enables collection of various statistics for KVM guest.
700           Statistics are displayed in debugfs filesystem. Enabling this option
701           may incur significant overhead.
702 
703 source "arch/x86/lguest/Kconfig"
704 
705 config PARAVIRT_TIME_ACCOUNTING
706         bool "Paravirtual steal time accounting"
707         depends on PARAVIRT
708         default n
709         ---help---
710           Select this option to enable fine granularity task steal time
711           accounting. Time spent executing other tasks in parallel with
712           the current vCPU is discounted from the vCPU power. To account for
713           that, there can be a small performance impact.
714 
715           If in doubt, say N here.
716 
717 config PARAVIRT_CLOCK
718         bool
719 
720 endif #HYPERVISOR_GUEST
721 
722 config NO_BOOTMEM
723         def_bool y
724 
725 source "arch/x86/Kconfig.cpu"
726 
727 config HPET_TIMER
728         def_bool X86_64
729         prompt "HPET Timer Support" if X86_32
730         ---help---
731           Use the IA-PC HPET (High Precision Event Timer) to manage
732           time in preference to the PIT and RTC, if a HPET is
733           present.
734           HPET is the next generation timer replacing legacy 8254s.
735           The HPET provides a stable time base on SMP
736           systems, unlike the TSC, but it is more expensive to access,
737           as it is off-chip.  You can find the HPET spec at
738           <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
739 
740           You can safely choose Y here.  However, HPET will only be
741           activated if the platform and the BIOS support this feature.
742           Otherwise the 8254 will be used for timing services.
743 
744           Choose N to continue using the legacy 8254 timer.
745 
746 config HPET_EMULATE_RTC
747         def_bool y
748         depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
749 
750 config APB_TIMER
751        def_bool y if X86_INTEL_MID
752        prompt "Intel MID APB Timer Support" if X86_INTEL_MID
753        select DW_APB_TIMER
754        depends on X86_INTEL_MID && SFI
755        help
756          APB timer is the replacement for 8254, HPET on X86 MID platforms.
757          The APBT provides a stable time base on SMP
758          systems, unlike the TSC, but it is more expensive to access,
759          as it is off-chip. APB timers are always running regardless of CPU
760          C states, they are used as per CPU clockevent device when possible.
761 
762 # Mark as expert because too many people got it wrong.
763 # The code disables itself when not needed.
764 config DMI
765         default y
766         select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
767         bool "Enable DMI scanning" if EXPERT
768         ---help---
769           Enabled scanning of DMI to identify machine quirks. Say Y
770           here unless you have verified that your setup is not
771           affected by entries in the DMI blacklist. Required by PNP
772           BIOS code.
773 
774 config GART_IOMMU
775         bool "Old AMD GART IOMMU support"
776         select SWIOTLB
777         depends on X86_64 && PCI && AMD_NB
778         ---help---
779           Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
780           GART based hardware IOMMUs.
781 
782           The GART supports full DMA access for devices with 32-bit access
783           limitations, on systems with more than 3 GB. This is usually needed
784           for USB, sound, many IDE/SATA chipsets and some other devices.
785 
786           Newer systems typically have a modern AMD IOMMU, supported via
787           the CONFIG_AMD_IOMMU=y config option.
788 
789           In normal configurations this driver is only active when needed:
790           there's more than 3 GB of memory and the system contains a
791           32-bit limited device.
792 
793           If unsure, say Y.
794 
795 config CALGARY_IOMMU
796         bool "IBM Calgary IOMMU support"
797         select SWIOTLB
798         depends on X86_64 && PCI
799         ---help---
800           Support for hardware IOMMUs in IBM's xSeries x366 and x460
801           systems. Needed to run systems with more than 3GB of memory
802           properly with 32-bit PCI devices that do not support DAC
803           (Double Address Cycle). Calgary also supports bus level
804           isolation, where all DMAs pass through the IOMMU.  This
805           prevents them from going anywhere except their intended
806           destination. This catches hard-to-find kernel bugs and
807           mis-behaving drivers and devices that do not use the DMA-API
808           properly to set up their DMA buffers.  The IOMMU can be
809           turned off at boot time with the iommu=off parameter.
810           Normally the kernel will make the right choice by itself.
811           If unsure, say Y.
812 
813 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
814         def_bool y
815         prompt "Should Calgary be enabled by default?"
816         depends on CALGARY_IOMMU
817         ---help---
818           Should Calgary be enabled by default? if you choose 'y', Calgary
819           will be used (if it exists). If you choose 'n', Calgary will not be
820           used even if it exists. If you choose 'n' and would like to use
821           Calgary anyway, pass 'iommu=calgary' on the kernel command line.
822           If unsure, say Y.
823 
824 # need this always selected by IOMMU for the VIA workaround
825 config SWIOTLB
826         def_bool y if X86_64
827         ---help---
828           Support for software bounce buffers used on x86-64 systems
829           which don't have a hardware IOMMU. Using this PCI devices
830           which can only access 32-bits of memory can be used on systems
831           with more than 3 GB of memory.
832           If unsure, say Y.
833 
834 config IOMMU_HELPER
835         def_bool y
836         depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
837 
838 config MAXSMP
839         bool "Enable Maximum number of SMP Processors and NUMA Nodes"
840         depends on X86_64 && SMP && DEBUG_KERNEL
841         select CPUMASK_OFFSTACK
842         ---help---
843           Enable maximum number of CPUS and NUMA Nodes for this architecture.
844           If unsure, say N.
845 
846 config NR_CPUS
847         int "Maximum number of CPUs" if SMP && !MAXSMP
848         range 2 8 if SMP && X86_32 && !X86_BIGSMP
849         range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
850         range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
851         default "1" if !SMP
852         default "8192" if MAXSMP
853         default "32" if SMP && X86_BIGSMP
854         default "8" if SMP
855         ---help---
856           This allows you to specify the maximum number of CPUs which this
857           kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
858           supported value is 4096, otherwise the maximum value is 512.  The
859           minimum value which makes sense is 2.
860 
861           This is purely to save memory - each supported CPU adds
862           approximately eight kilobytes to the kernel image.
863 
864 config SCHED_SMT
865         bool "SMT (Hyperthreading) scheduler support"
866         depends on X86_HT
867         ---help---
868           SMT scheduler support improves the CPU scheduler's decision making
869           when dealing with Intel Pentium 4 chips with HyperThreading at a
870           cost of slightly increased overhead in some places. If unsure say
871           N here.
872 
873 config SCHED_MC
874         def_bool y
875         prompt "Multi-core scheduler support"
876         depends on X86_HT
877         ---help---
878           Multi-core scheduler support improves the CPU scheduler's decision
879           making when dealing with multi-core CPU chips at a cost of slightly
880           increased overhead in some places. If unsure say N here.
881 
882 source "kernel/Kconfig.preempt"
883 
884 config UP_LATE_INIT
885        def_bool y
886        depends on !SMP && X86_LOCAL_APIC
887 
888 config X86_UP_APIC
889         bool "Local APIC support on uniprocessors" if !PCI_MSI
890         default PCI_MSI
891         depends on X86_32 && !SMP && !X86_32_NON_STANDARD
892         ---help---
893           A local APIC (Advanced Programmable Interrupt Controller) is an
894           integrated interrupt controller in the CPU. If you have a single-CPU
895           system which has a processor with a local APIC, you can say Y here to
896           enable and use it. If you say Y here even though your machine doesn't
897           have a local APIC, then the kernel will still run with no slowdown at
898           all. The local APIC supports CPU-generated self-interrupts (timer,
899           performance counters), and the NMI watchdog which detects hard
900           lockups.
901 
902 config X86_UP_IOAPIC
903         bool "IO-APIC support on uniprocessors"
904         depends on X86_UP_APIC
905         ---help---
906           An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
907           SMP-capable replacement for PC-style interrupt controllers. Most
908           SMP systems and many recent uniprocessor systems have one.
909 
910           If you have a single-CPU system with an IO-APIC, you can say Y here
911           to use it. If you say Y here even though your machine doesn't have
912           an IO-APIC, then the kernel will still run with no slowdown at all.
913 
914 config X86_LOCAL_APIC
915         def_bool y
916         depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
917         select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
918 
919 config X86_IO_APIC
920         def_bool y
921         depends on X86_LOCAL_APIC || X86_UP_IOAPIC
922         select IRQ_DOMAIN
923 
924 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
925         bool "Reroute for broken boot IRQs"
926         depends on X86_IO_APIC
927         ---help---
928           This option enables a workaround that fixes a source of
929           spurious interrupts. This is recommended when threaded
930           interrupt handling is used on systems where the generation of
931           superfluous "boot interrupts" cannot be disabled.
932 
933           Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
934           entry in the chipset's IO-APIC is masked (as, e.g. the RT
935           kernel does during interrupt handling). On chipsets where this
936           boot IRQ generation cannot be disabled, this workaround keeps
937           the original IRQ line masked so that only the equivalent "boot
938           IRQ" is delivered to the CPUs. The workaround also tells the
939           kernel to set up the IRQ handler on the boot IRQ line. In this
940           way only one interrupt is delivered to the kernel. Otherwise
941           the spurious second interrupt may cause the kernel to bring
942           down (vital) interrupt lines.
943 
944           Only affects "broken" chipsets. Interrupt sharing may be
945           increased on these systems.
946 
947 config X86_MCE
948         bool "Machine Check / overheating reporting"
949         default y
950         ---help---
951           Machine Check support allows the processor to notify the
952           kernel if it detects a problem (e.g. overheating, data corruption).
953           The action the kernel takes depends on the severity of the problem,
954           ranging from warning messages to halting the machine.
955 
956 config X86_MCE_INTEL
957         def_bool y
958         prompt "Intel MCE features"
959         depends on X86_MCE && X86_LOCAL_APIC
960         ---help---
961            Additional support for intel specific MCE features such as
962            the thermal monitor.
963 
964 config X86_MCE_AMD
965         def_bool y
966         prompt "AMD MCE features"
967         depends on X86_MCE && X86_LOCAL_APIC
968         ---help---
969            Additional support for AMD specific MCE features such as
970            the DRAM Error Threshold.
971 
972 config X86_ANCIENT_MCE
973         bool "Support for old Pentium 5 / WinChip machine checks"
974         depends on X86_32 && X86_MCE
975         ---help---
976           Include support for machine check handling on old Pentium 5 or WinChip
977           systems. These typically need to be enabled explicitly on the command
978           line.
979 
980 config X86_MCE_THRESHOLD
981         depends on X86_MCE_AMD || X86_MCE_INTEL
982         def_bool y
983 
984 config X86_MCE_INJECT
985         depends on X86_MCE
986         tristate "Machine check injector support"
987         ---help---
988           Provide support for injecting machine checks for testing purposes.
989           If you don't know what a machine check is and you don't do kernel
990           QA it is safe to say n.
991 
992 config X86_THERMAL_VECTOR
993         def_bool y
994         depends on X86_MCE_INTEL
995 
996 config VM86
997         bool "Enable VM86 support" if EXPERT
998         default y
999         depends on X86_32
1000         ---help---
1001           This option is required by programs like DOSEMU to run
1002           16-bit real mode legacy code on x86 processors. It also may
1003           be needed by software like XFree86 to initialize some video
1004           cards via BIOS. Disabling this option saves about 6K.
1005 
1006 config X86_16BIT
1007         bool "Enable support for 16-bit segments" if EXPERT
1008         default y
1009         ---help---
1010           This option is required by programs like Wine to run 16-bit
1011           protected mode legacy code on x86 processors.  Disabling
1012           this option saves about 300 bytes on i386, or around 6K text
1013           plus 16K runtime memory on x86-64,
1014 
1015 config X86_ESPFIX32
1016         def_bool y
1017         depends on X86_16BIT && X86_32
1018 
1019 config X86_ESPFIX64
1020         def_bool y
1021         depends on X86_16BIT && X86_64
1022 
1023 config X86_VSYSCALL_EMULATION
1024        bool "Enable vsyscall emulation" if EXPERT
1025        default y
1026        depends on X86_64
1027        ---help---
1028          This enables emulation of the legacy vsyscall page.  Disabling
1029          it is roughly equivalent to booting with vsyscall=none, except
1030          that it will also disable the helpful warning if a program
1031          tries to use a vsyscall.  With this option set to N, offending
1032          programs will just segfault, citing addresses of the form
1033          0xffffffffff600?00.
1034 
1035          This option is required by many programs built before 2013, and
1036          care should be used even with newer programs if set to N.
1037 
1038          Disabling this option saves about 7K of kernel size and
1039          possibly 4K of additional runtime pagetable memory.
1040 
1041 config TOSHIBA
1042         tristate "Toshiba Laptop support"
1043         depends on X86_32
1044         ---help---
1045           This adds a driver to safely access the System Management Mode of
1046           the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1047           not work on models with a Phoenix BIOS. The System Management Mode
1048           is used to set the BIOS and power saving options on Toshiba portables.
1049 
1050           For information on utilities to make use of this driver see the
1051           Toshiba Linux utilities web site at:
1052           <http://www.buzzard.org.uk/toshiba/>.
1053 
1054           Say Y if you intend to run this kernel on a Toshiba portable.
1055           Say N otherwise.
1056 
1057 config I8K
1058         tristate "Dell laptop support"
1059         select HWMON
1060         ---help---
1061           This adds a driver to safely access the System Management Mode
1062           of the CPU on the Dell Inspiron 8000. The System Management Mode
1063           is used to read cpu temperature and cooling fan status and to
1064           control the fans on the I8K portables.
1065 
1066           This driver has been tested only on the Inspiron 8000 but it may
1067           also work with other Dell laptops. You can force loading on other
1068           models by passing the parameter `force=1' to the module. Use at
1069           your own risk.
1070 
1071           For information on utilities to make use of this driver see the
1072           I8K Linux utilities web site at:
1073           <http://people.debian.org/~dz/i8k/>
1074 
1075           Say Y if you intend to run this kernel on a Dell Inspiron 8000.
1076           Say N otherwise.
1077 
1078 config X86_REBOOTFIXUPS
1079         bool "Enable X86 board specific fixups for reboot"
1080         depends on X86_32
1081         ---help---
1082           This enables chipset and/or board specific fixups to be done
1083           in order to get reboot to work correctly. This is only needed on
1084           some combinations of hardware and BIOS. The symptom, for which
1085           this config is intended, is when reboot ends with a stalled/hung
1086           system.
1087 
1088           Currently, the only fixup is for the Geode machines using
1089           CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1090 
1091           Say Y if you want to enable the fixup. Currently, it's safe to
1092           enable this option even if you don't need it.
1093           Say N otherwise.
1094 
1095 config MICROCODE
1096         tristate "CPU microcode loading support"
1097         depends on CPU_SUP_AMD || CPU_SUP_INTEL
1098         select FW_LOADER
1099         ---help---
1100 
1101           If you say Y here, you will be able to update the microcode on
1102           certain Intel and AMD processors. The Intel support is for the
1103           IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1104           Xeon etc. The AMD support is for families 0x10 and later. You will
1105           obviously need the actual microcode binary data itself which is not
1106           shipped with the Linux kernel.
1107 
1108           This option selects the general module only, you need to select
1109           at least one vendor specific module as well.
1110 
1111           To compile this driver as a module, choose M here: the module
1112           will be called microcode.
1113 
1114 config MICROCODE_INTEL
1115         bool "Intel microcode loading support"
1116         depends on MICROCODE
1117         default MICROCODE
1118         select FW_LOADER
1119         ---help---
1120           This options enables microcode patch loading support for Intel
1121           processors.
1122 
1123           For the current Intel microcode data package go to
1124           <https://downloadcenter.intel.com> and search for
1125           'Linux Processor Microcode Data File'.
1126 
1127 config MICROCODE_AMD
1128         bool "AMD microcode loading support"
1129         depends on MICROCODE
1130         select FW_LOADER
1131         ---help---
1132           If you select this option, microcode patch loading support for AMD
1133           processors will be enabled.
1134 
1135 config MICROCODE_OLD_INTERFACE
1136         def_bool y
1137         depends on MICROCODE
1138 
1139 config MICROCODE_INTEL_EARLY
1140         bool
1141 
1142 config MICROCODE_AMD_EARLY
1143         bool
1144 
1145 config MICROCODE_EARLY
1146         bool "Early load microcode"
1147         depends on MICROCODE=y && BLK_DEV_INITRD
1148         select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1149         select MICROCODE_AMD_EARLY if MICROCODE_AMD
1150         default y
1151         help
1152           This option provides functionality to read additional microcode data
1153           at the beginning of initrd image. The data tells kernel to load
1154           microcode to CPU's as early as possible. No functional change if no
1155           microcode data is glued to the initrd, therefore it's safe to say Y.
1156 
1157 config X86_MSR
1158         tristate "/dev/cpu/*/msr - Model-specific register support"
1159         ---help---
1160           This device gives privileged processes access to the x86
1161           Model-Specific Registers (MSRs).  It is a character device with
1162           major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1163           MSR accesses are directed to a specific CPU on multi-processor
1164           systems.
1165 
1166 config X86_CPUID
1167         tristate "/dev/cpu/*/cpuid - CPU information support"
1168         ---help---
1169           This device gives processes access to the x86 CPUID instruction to
1170           be executed on a specific processor.  It is a character device
1171           with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1172           /dev/cpu/31/cpuid.
1173 
1174 choice
1175         prompt "High Memory Support"
1176         default HIGHMEM4G
1177         depends on X86_32
1178 
1179 config NOHIGHMEM
1180         bool "off"
1181         ---help---
1182           Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1183           However, the address space of 32-bit x86 processors is only 4
1184           Gigabytes large. That means that, if you have a large amount of
1185           physical memory, not all of it can be "permanently mapped" by the
1186           kernel. The physical memory that's not permanently mapped is called
1187           "high memory".
1188 
1189           If you are compiling a kernel which will never run on a machine with
1190           more than 1 Gigabyte total physical RAM, answer "off" here (default
1191           choice and suitable for most users). This will result in a "3GB/1GB"
1192           split: 3GB are mapped so that each process sees a 3GB virtual memory
1193           space and the remaining part of the 4GB virtual memory space is used
1194           by the kernel to permanently map as much physical memory as
1195           possible.
1196 
1197           If the machine has between 1 and 4 Gigabytes physical RAM, then
1198           answer "4GB" here.
1199 
1200           If more than 4 Gigabytes is used then answer "64GB" here. This
1201           selection turns Intel PAE (Physical Address Extension) mode on.
1202           PAE implements 3-level paging on IA32 processors. PAE is fully
1203           supported by Linux, PAE mode is implemented on all recent Intel
1204           processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1205           then the kernel will not boot on CPUs that don't support PAE!
1206 
1207           The actual amount of total physical memory will either be
1208           auto detected or can be forced by using a kernel command line option
1209           such as "mem=256M". (Try "man bootparam" or see the documentation of
1210           your boot loader (lilo or loadlin) about how to pass options to the
1211           kernel at boot time.)
1212 
1213           If unsure, say "off".
1214 
1215 config HIGHMEM4G
1216         bool "4GB"
1217         ---help---
1218           Select this if you have a 32-bit processor and between 1 and 4
1219           gigabytes of physical RAM.
1220 
1221 config HIGHMEM64G
1222         bool "64GB"
1223         depends on !M486
1224         select X86_PAE
1225         ---help---
1226           Select this if you have a 32-bit processor and more than 4
1227           gigabytes of physical RAM.
1228 
1229 endchoice
1230 
1231 choice
1232         prompt "Memory split" if EXPERT
1233         default VMSPLIT_3G
1234         depends on X86_32
1235         ---help---
1236           Select the desired split between kernel and user memory.
1237 
1238           If the address range available to the kernel is less than the
1239           physical memory installed, the remaining memory will be available
1240           as "high memory". Accessing high memory is a little more costly
1241           than low memory, as it needs to be mapped into the kernel first.
1242           Note that increasing the kernel address space limits the range
1243           available to user programs, making the address space there
1244           tighter.  Selecting anything other than the default 3G/1G split
1245           will also likely make your kernel incompatible with binary-only
1246           kernel modules.
1247 
1248           If you are not absolutely sure what you are doing, leave this
1249           option alone!
1250 
1251         config VMSPLIT_3G
1252                 bool "3G/1G user/kernel split"
1253         config VMSPLIT_3G_OPT
1254                 depends on !X86_PAE
1255                 bool "3G/1G user/kernel split (for full 1G low memory)"
1256         config VMSPLIT_2G
1257                 bool "2G/2G user/kernel split"
1258         config VMSPLIT_2G_OPT
1259                 depends on !X86_PAE
1260                 bool "2G/2G user/kernel split (for full 2G low memory)"
1261         config VMSPLIT_1G
1262                 bool "1G/3G user/kernel split"
1263 endchoice
1264 
1265 config PAGE_OFFSET
1266         hex
1267         default 0xB0000000 if VMSPLIT_3G_OPT
1268         default 0x80000000 if VMSPLIT_2G
1269         default 0x78000000 if VMSPLIT_2G_OPT
1270         default 0x40000000 if VMSPLIT_1G
1271         default 0xC0000000
1272         depends on X86_32
1273 
1274 config HIGHMEM
1275         def_bool y
1276         depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1277 
1278 config X86_PAE
1279         bool "PAE (Physical Address Extension) Support"
1280         depends on X86_32 && !HIGHMEM4G
1281         ---help---
1282           PAE is required for NX support, and furthermore enables
1283           larger swapspace support for non-overcommit purposes. It
1284           has the cost of more pagetable lookup overhead, and also
1285           consumes more pagetable space per process.
1286 
1287 config ARCH_PHYS_ADDR_T_64BIT
1288         def_bool y
1289         depends on X86_64 || X86_PAE
1290 
1291 config ARCH_DMA_ADDR_T_64BIT
1292         def_bool y
1293         depends on X86_64 || HIGHMEM64G
1294 
1295 config X86_DIRECT_GBPAGES
1296         def_bool y
1297         depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1298         ---help---
1299           Certain kernel features effectively disable kernel
1300           linear 1 GB mappings (even if the CPU otherwise
1301           supports them), so don't confuse the user by printing
1302           that we have them enabled.
1303 
1304 # Common NUMA Features
1305 config NUMA
1306         bool "Numa Memory Allocation and Scheduler Support"
1307         depends on SMP
1308         depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1309         default y if X86_BIGSMP
1310         ---help---
1311           Enable NUMA (Non Uniform Memory Access) support.
1312 
1313           The kernel will try to allocate memory used by a CPU on the
1314           local memory controller of the CPU and add some more
1315           NUMA awareness to the kernel.
1316 
1317           For 64-bit this is recommended if the system is Intel Core i7
1318           (or later), AMD Opteron, or EM64T NUMA.
1319 
1320           For 32-bit this is only needed if you boot a 32-bit
1321           kernel on a 64-bit NUMA platform.
1322 
1323           Otherwise, you should say N.
1324 
1325 config AMD_NUMA
1326         def_bool y
1327         prompt "Old style AMD Opteron NUMA detection"
1328         depends on X86_64 && NUMA && PCI
1329         ---help---
1330           Enable AMD NUMA node topology detection.  You should say Y here if
1331           you have a multi processor AMD system. This uses an old method to
1332           read the NUMA configuration directly from the builtin Northbridge
1333           of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1334           which also takes priority if both are compiled in.
1335 
1336 config X86_64_ACPI_NUMA
1337         def_bool y
1338         prompt "ACPI NUMA detection"
1339         depends on X86_64 && NUMA && ACPI && PCI
1340         select ACPI_NUMA
1341         ---help---
1342           Enable ACPI SRAT based node topology detection.
1343 
1344 # Some NUMA nodes have memory ranges that span
1345 # other nodes.  Even though a pfn is valid and
1346 # between a node's start and end pfns, it may not
1347 # reside on that node.  See memmap_init_zone()
1348 # for details.
1349 config NODES_SPAN_OTHER_NODES
1350         def_bool y
1351         depends on X86_64_ACPI_NUMA
1352 
1353 config NUMA_EMU
1354         bool "NUMA emulation"
1355         depends on NUMA
1356         ---help---
1357           Enable NUMA emulation. A flat machine will be split
1358           into virtual nodes when booted with "numa=fake=N", where N is the
1359           number of nodes. This is only useful for debugging.
1360 
1361 config NODES_SHIFT
1362         int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1363         range 1 10
1364         default "10" if MAXSMP
1365         default "6" if X86_64
1366         default "3"
1367         depends on NEED_MULTIPLE_NODES
1368         ---help---
1369           Specify the maximum number of NUMA Nodes available on the target
1370           system.  Increases memory reserved to accommodate various tables.
1371 
1372 config ARCH_HAVE_MEMORY_PRESENT
1373         def_bool y
1374         depends on X86_32 && DISCONTIGMEM
1375 
1376 config NEED_NODE_MEMMAP_SIZE
1377         def_bool y
1378         depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1379 
1380 config ARCH_FLATMEM_ENABLE
1381         def_bool y
1382         depends on X86_32 && !NUMA
1383 
1384 config ARCH_DISCONTIGMEM_ENABLE
1385         def_bool y
1386         depends on NUMA && X86_32
1387 
1388 config ARCH_DISCONTIGMEM_DEFAULT
1389         def_bool y
1390         depends on NUMA && X86_32
1391 
1392 config ARCH_SPARSEMEM_ENABLE
1393         def_bool y
1394         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1395         select SPARSEMEM_STATIC if X86_32
1396         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1397 
1398 config ARCH_SPARSEMEM_DEFAULT
1399         def_bool y
1400         depends on X86_64
1401 
1402 config ARCH_SELECT_MEMORY_MODEL
1403         def_bool y
1404         depends on ARCH_SPARSEMEM_ENABLE
1405 
1406 config ARCH_MEMORY_PROBE
1407         bool "Enable sysfs memory/probe interface"
1408         depends on X86_64 && MEMORY_HOTPLUG
1409         help
1410           This option enables a sysfs memory/probe interface for testing.
1411           See Documentation/memory-hotplug.txt for more information.
1412           If you are unsure how to answer this question, answer N.
1413 
1414 config ARCH_PROC_KCORE_TEXT
1415         def_bool y
1416         depends on X86_64 && PROC_KCORE
1417 
1418 config ILLEGAL_POINTER_VALUE
1419        hex
1420        default 0 if X86_32
1421        default 0xdead000000000000 if X86_64
1422 
1423 source "mm/Kconfig"
1424 
1425 config X86_PMEM_LEGACY
1426         bool "Support non-standard NVDIMMs and ADR protected memory"
1427         help
1428           Treat memory marked using the non-standard e820 type of 12 as used
1429           by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1430           The kernel will offer these regions to the 'pmem' driver so
1431           they can be used for persistent storage.
1432 
1433           Say Y if unsure.
1434 
1435 config HIGHPTE
1436         bool "Allocate 3rd-level pagetables from highmem"
1437         depends on HIGHMEM
1438         ---help---
1439           The VM uses one page table entry for each page of physical memory.
1440           For systems with a lot of RAM, this can be wasteful of precious
1441           low memory.  Setting this option will put user-space page table
1442           entries in high memory.
1443 
1444 config X86_CHECK_BIOS_CORRUPTION
1445         bool "Check for low memory corruption"
1446         ---help---
1447           Periodically check for memory corruption in low memory, which
1448           is suspected to be caused by BIOS.  Even when enabled in the
1449           configuration, it is disabled at runtime.  Enable it by
1450           setting "memory_corruption_check=1" on the kernel command
1451           line.  By default it scans the low 64k of memory every 60
1452           seconds; see the memory_corruption_check_size and
1453           memory_corruption_check_period parameters in
1454           Documentation/kernel-parameters.txt to adjust this.
1455 
1456           When enabled with the default parameters, this option has
1457           almost no overhead, as it reserves a relatively small amount
1458           of memory and scans it infrequently.  It both detects corruption
1459           and prevents it from affecting the running system.
1460 
1461           It is, however, intended as a diagnostic tool; if repeatable
1462           BIOS-originated corruption always affects the same memory,
1463           you can use memmap= to prevent the kernel from using that
1464           memory.
1465 
1466 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1467         bool "Set the default setting of memory_corruption_check"
1468         depends on X86_CHECK_BIOS_CORRUPTION
1469         default y
1470         ---help---
1471           Set whether the default state of memory_corruption_check is
1472           on or off.
1473 
1474 config X86_RESERVE_LOW
1475         int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1476         default 64
1477         range 4 640
1478         ---help---
1479           Specify the amount of low memory to reserve for the BIOS.
1480 
1481           The first page contains BIOS data structures that the kernel
1482           must not use, so that page must always be reserved.
1483 
1484           By default we reserve the first 64K of physical RAM, as a
1485           number of BIOSes are known to corrupt that memory range
1486           during events such as suspend/resume or monitor cable
1487           insertion, so it must not be used by the kernel.
1488 
1489           You can set this to 4 if you are absolutely sure that you
1490           trust the BIOS to get all its memory reservations and usages
1491           right.  If you know your BIOS have problems beyond the
1492           default 64K area, you can set this to 640 to avoid using the
1493           entire low memory range.
1494 
1495           If you have doubts about the BIOS (e.g. suspend/resume does
1496           not work or there's kernel crashes after certain hardware
1497           hotplug events) then you might want to enable
1498           X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1499           typical corruption patterns.
1500 
1501           Leave this to the default value of 64 if you are unsure.
1502 
1503 config MATH_EMULATION
1504         bool
1505         prompt "Math emulation" if X86_32
1506         ---help---
1507           Linux can emulate a math coprocessor (used for floating point
1508           operations) if you don't have one. 486DX and Pentium processors have
1509           a math coprocessor built in, 486SX and 386 do not, unless you added
1510           a 487DX or 387, respectively. (The messages during boot time can
1511           give you some hints here ["man dmesg"].) Everyone needs either a
1512           coprocessor or this emulation.
1513 
1514           If you don't have a math coprocessor, you need to say Y here; if you
1515           say Y here even though you have a coprocessor, the coprocessor will
1516           be used nevertheless. (This behavior can be changed with the kernel
1517           command line option "no387", which comes handy if your coprocessor
1518           is broken. Try "man bootparam" or see the documentation of your boot
1519           loader (lilo or loadlin) about how to pass options to the kernel at
1520           boot time.) This means that it is a good idea to say Y here if you
1521           intend to use this kernel on different machines.
1522 
1523           More information about the internals of the Linux math coprocessor
1524           emulation can be found in <file:arch/x86/math-emu/README>.
1525 
1526           If you are not sure, say Y; apart from resulting in a 66 KB bigger
1527           kernel, it won't hurt.
1528 
1529 config MTRR
1530         def_bool y
1531         prompt "MTRR (Memory Type Range Register) support" if EXPERT
1532         ---help---
1533           On Intel P6 family processors (Pentium Pro, Pentium II and later)
1534           the Memory Type Range Registers (MTRRs) may be used to control
1535           processor access to memory ranges. This is most useful if you have
1536           a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1537           allows bus write transfers to be combined into a larger transfer
1538           before bursting over the PCI/AGP bus. This can increase performance
1539           of image write operations 2.5 times or more. Saying Y here creates a
1540           /proc/mtrr file which may be used to manipulate your processor's
1541           MTRRs. Typically the X server should use this.
1542 
1543           This code has a reasonably generic interface so that similar
1544           control registers on other processors can be easily supported
1545           as well:
1546 
1547           The Cyrix 6x86, 6x86MX and M II processors have Address Range
1548           Registers (ARRs) which provide a similar functionality to MTRRs. For
1549           these, the ARRs are used to emulate the MTRRs.
1550           The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1551           MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1552           write-combining. All of these processors are supported by this code
1553           and it makes sense to say Y here if you have one of them.
1554 
1555           Saying Y here also fixes a problem with buggy SMP BIOSes which only
1556           set the MTRRs for the boot CPU and not for the secondary CPUs. This
1557           can lead to all sorts of problems, so it's good to say Y here.
1558 
1559           You can safely say Y even if your machine doesn't have MTRRs, you'll
1560           just add about 9 KB to your kernel.
1561 
1562           See <file:Documentation/x86/mtrr.txt> for more information.
1563 
1564 config MTRR_SANITIZER
1565         def_bool y
1566         prompt "MTRR cleanup support"
1567         depends on MTRR
1568         ---help---
1569           Convert MTRR layout from continuous to discrete, so X drivers can
1570           add writeback entries.
1571 
1572           Can be disabled with disable_mtrr_cleanup on the kernel command line.
1573           The largest mtrr entry size for a continuous block can be set with
1574           mtrr_chunk_size.
1575 
1576           If unsure, say Y.
1577 
1578 config MTRR_SANITIZER_ENABLE_DEFAULT
1579         int "MTRR cleanup enable value (0-1)"
1580         range 0 1
1581         default "0"
1582         depends on MTRR_SANITIZER
1583         ---help---
1584           Enable mtrr cleanup default value
1585 
1586 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1587         int "MTRR cleanup spare reg num (0-7)"
1588         range 0 7
1589         default "1"
1590         depends on MTRR_SANITIZER
1591         ---help---
1592           mtrr cleanup spare entries default, it can be changed via
1593           mtrr_spare_reg_nr=N on the kernel command line.
1594 
1595 config X86_PAT
1596         def_bool y
1597         prompt "x86 PAT support" if EXPERT
1598         depends on MTRR
1599         ---help---
1600           Use PAT attributes to setup page level cache control.
1601 
1602           PATs are the modern equivalents of MTRRs and are much more
1603           flexible than MTRRs.
1604 
1605           Say N here if you see bootup problems (boot crash, boot hang,
1606           spontaneous reboots) or a non-working video driver.
1607 
1608           If unsure, say Y.
1609 
1610 config ARCH_USES_PG_UNCACHED
1611         def_bool y
1612         depends on X86_PAT
1613 
1614 config ARCH_RANDOM
1615         def_bool y
1616         prompt "x86 architectural random number generator" if EXPERT
1617         ---help---
1618           Enable the x86 architectural RDRAND instruction
1619           (Intel Bull Mountain technology) to generate random numbers.
1620           If supported, this is a high bandwidth, cryptographically
1621           secure hardware random number generator.
1622 
1623 config X86_SMAP
1624         def_bool y
1625         prompt "Supervisor Mode Access Prevention" if EXPERT
1626         ---help---
1627           Supervisor Mode Access Prevention (SMAP) is a security
1628           feature in newer Intel processors.  There is a small
1629           performance cost if this enabled and turned on; there is
1630           also a small increase in the kernel size if this is enabled.
1631 
1632           If unsure, say Y.
1633 
1634 config X86_INTEL_MPX
1635         prompt "Intel MPX (Memory Protection Extensions)"
1636         def_bool n
1637         depends on CPU_SUP_INTEL
1638         ---help---
1639           MPX provides hardware features that can be used in
1640           conjunction with compiler-instrumented code to check
1641           memory references.  It is designed to detect buffer
1642           overflow or underflow bugs.
1643 
1644           This option enables running applications which are
1645           instrumented or otherwise use MPX.  It does not use MPX
1646           itself inside the kernel or to protect the kernel
1647           against bad memory references.
1648 
1649           Enabling this option will make the kernel larger:
1650           ~8k of kernel text and 36 bytes of data on a 64-bit
1651           defconfig.  It adds a long to the 'mm_struct' which
1652           will increase the kernel memory overhead of each
1653           process and adds some branches to paths used during
1654           exec() and munmap().
1655 
1656           For details, see Documentation/x86/intel_mpx.txt
1657 
1658           If unsure, say N.
1659 
1660 config EFI
1661         bool "EFI runtime service support"
1662         depends on ACPI
1663         select UCS2_STRING
1664         select EFI_RUNTIME_WRAPPERS
1665         ---help---
1666           This enables the kernel to use EFI runtime services that are
1667           available (such as the EFI variable services).
1668 
1669           This option is only useful on systems that have EFI firmware.
1670           In addition, you should use the latest ELILO loader available
1671           at <http://elilo.sourceforge.net> in order to take advantage
1672           of EFI runtime services. However, even with this option, the
1673           resultant kernel should continue to boot on existing non-EFI
1674           platforms.
1675 
1676 config EFI_STUB
1677        bool "EFI stub support"
1678        depends on EFI && !X86_USE_3DNOW
1679        select RELOCATABLE
1680        ---help---
1681           This kernel feature allows a bzImage to be loaded directly
1682           by EFI firmware without the use of a bootloader.
1683 
1684           See Documentation/efi-stub.txt for more information.
1685 
1686 config EFI_MIXED
1687         bool "EFI mixed-mode support"
1688         depends on EFI_STUB && X86_64
1689         ---help---
1690            Enabling this feature allows a 64-bit kernel to be booted
1691            on a 32-bit firmware, provided that your CPU supports 64-bit
1692            mode.
1693 
1694            Note that it is not possible to boot a mixed-mode enabled
1695            kernel via the EFI boot stub - a bootloader that supports
1696            the EFI handover protocol must be used.
1697 
1698            If unsure, say N.
1699 
1700 config SECCOMP
1701         def_bool y
1702         prompt "Enable seccomp to safely compute untrusted bytecode"
1703         ---help---
1704           This kernel feature is useful for number crunching applications
1705           that may need to compute untrusted bytecode during their
1706           execution. By using pipes or other transports made available to
1707           the process as file descriptors supporting the read/write
1708           syscalls, it's possible to isolate those applications in
1709           their own address space using seccomp. Once seccomp is
1710           enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1711           and the task is only allowed to execute a few safe syscalls
1712           defined by each seccomp mode.
1713 
1714           If unsure, say Y. Only embedded should say N here.
1715 
1716 source kernel/Kconfig.hz
1717 
1718 config KEXEC
1719         bool "kexec system call"
1720         ---help---
1721           kexec is a system call that implements the ability to shutdown your
1722           current kernel, and to start another kernel.  It is like a reboot
1723           but it is independent of the system firmware.   And like a reboot
1724           you can start any kernel with it, not just Linux.
1725 
1726           The name comes from the similarity to the exec system call.
1727 
1728           It is an ongoing process to be certain the hardware in a machine
1729           is properly shutdown, so do not be surprised if this code does not
1730           initially work for you.  As of this writing the exact hardware
1731           interface is strongly in flux, so no good recommendation can be
1732           made.
1733 
1734 config KEXEC_FILE
1735         bool "kexec file based system call"
1736         select BUILD_BIN2C
1737         depends on KEXEC
1738         depends on X86_64
1739         depends on CRYPTO=y
1740         depends on CRYPTO_SHA256=y
1741         ---help---
1742           This is new version of kexec system call. This system call is
1743           file based and takes file descriptors as system call argument
1744           for kernel and initramfs as opposed to list of segments as
1745           accepted by previous system call.
1746 
1747 config KEXEC_VERIFY_SIG
1748         bool "Verify kernel signature during kexec_file_load() syscall"
1749         depends on KEXEC_FILE
1750         ---help---
1751           This option makes kernel signature verification mandatory for
1752           the kexec_file_load() syscall.
1753 
1754           In addition to that option, you need to enable signature
1755           verification for the corresponding kernel image type being
1756           loaded in order for this to work.
1757 
1758 config KEXEC_BZIMAGE_VERIFY_SIG
1759         bool "Enable bzImage signature verification support"
1760         depends on KEXEC_VERIFY_SIG
1761         depends on SIGNED_PE_FILE_VERIFICATION
1762         select SYSTEM_TRUSTED_KEYRING
1763         ---help---
1764           Enable bzImage signature verification support.
1765 
1766 config CRASH_DUMP
1767         bool "kernel crash dumps"
1768         depends on X86_64 || (X86_32 && HIGHMEM)
1769         ---help---
1770           Generate crash dump after being started by kexec.
1771           This should be normally only set in special crash dump kernels
1772           which are loaded in the main kernel with kexec-tools into
1773           a specially reserved region and then later executed after
1774           a crash by kdump/kexec. The crash dump kernel must be compiled
1775           to a memory address not used by the main kernel or BIOS using
1776           PHYSICAL_START, or it must be built as a relocatable image
1777           (CONFIG_RELOCATABLE=y).
1778           For more details see Documentation/kdump/kdump.txt
1779 
1780 config KEXEC_JUMP
1781         bool "kexec jump"
1782         depends on KEXEC && HIBERNATION
1783         ---help---
1784           Jump between original kernel and kexeced kernel and invoke
1785           code in physical address mode via KEXEC
1786 
1787 config PHYSICAL_START
1788         hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1789         default "0x1000000"
1790         ---help---
1791           This gives the physical address where the kernel is loaded.
1792 
1793           If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1794           bzImage will decompress itself to above physical address and
1795           run from there. Otherwise, bzImage will run from the address where
1796           it has been loaded by the boot loader and will ignore above physical
1797           address.
1798 
1799           In normal kdump cases one does not have to set/change this option
1800           as now bzImage can be compiled as a completely relocatable image
1801           (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1802           address. This option is mainly useful for the folks who don't want
1803           to use a bzImage for capturing the crash dump and want to use a
1804           vmlinux instead. vmlinux is not relocatable hence a kernel needs
1805           to be specifically compiled to run from a specific memory area
1806           (normally a reserved region) and this option comes handy.
1807 
1808           So if you are using bzImage for capturing the crash dump,
1809           leave the value here unchanged to 0x1000000 and set
1810           CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
1811           for capturing the crash dump change this value to start of
1812           the reserved region.  In other words, it can be set based on
1813           the "X" value as specified in the "crashkernel=YM@XM"
1814           command line boot parameter passed to the panic-ed
1815           kernel. Please take a look at Documentation/kdump/kdump.txt
1816           for more details about crash dumps.
1817 
1818           Usage of bzImage for capturing the crash dump is recommended as
1819           one does not have to build two kernels. Same kernel can be used
1820           as production kernel and capture kernel. Above option should have
1821           gone away after relocatable bzImage support is introduced. But it
1822           is present because there are users out there who continue to use
1823           vmlinux for dump capture. This option should go away down the
1824           line.
1825 
1826           Don't change this unless you know what you are doing.
1827 
1828 config RELOCATABLE
1829         bool "Build a relocatable kernel"
1830         default y
1831         ---help---
1832           This builds a kernel image that retains relocation information
1833           so it can be loaded someplace besides the default 1MB.
1834           The relocations tend to make the kernel binary about 10% larger,
1835           but are discarded at runtime.
1836 
1837           One use is for the kexec on panic case where the recovery kernel
1838           must live at a different physical address than the primary
1839           kernel.
1840 
1841           Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1842           it has been loaded at and the compile time physical address
1843           (CONFIG_PHYSICAL_START) is used as the minimum location.
1844 
1845 config RANDOMIZE_BASE
1846         bool "Randomize the address of the kernel image"
1847         depends on RELOCATABLE
1848         default n
1849         ---help---
1850            Randomizes the physical and virtual address at which the
1851            kernel image is decompressed, as a security feature that
1852            deters exploit attempts relying on knowledge of the location
1853            of kernel internals.
1854 
1855            Entropy is generated using the RDRAND instruction if it is
1856            supported. If RDTSC is supported, it is used as well. If
1857            neither RDRAND nor RDTSC are supported, then randomness is
1858            read from the i8254 timer.
1859 
1860            The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1861            and aligned according to PHYSICAL_ALIGN. Since the kernel is
1862            built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1863            minimum of 2MiB, only 10 bits of entropy is theoretically
1864            possible. At best, due to page table layouts, 64-bit can use
1865            9 bits of entropy and 32-bit uses 8 bits.
1866 
1867            If unsure, say N.
1868 
1869 config RANDOMIZE_BASE_MAX_OFFSET
1870         hex "Maximum kASLR offset allowed" if EXPERT
1871         depends on RANDOMIZE_BASE
1872         range 0x0 0x20000000 if X86_32
1873         default "0x20000000" if X86_32
1874         range 0x0 0x40000000 if X86_64
1875         default "0x40000000" if X86_64
1876         ---help---
1877           The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1878           memory is used to determine the maximal offset in bytes that will
1879           be applied to the kernel when kernel Address Space Layout
1880           Randomization (kASLR) is active. This must be a multiple of
1881           PHYSICAL_ALIGN.
1882 
1883           On 32-bit this is limited to 512MiB by page table layouts. The
1884           default is 512MiB.
1885 
1886           On 64-bit this is limited by how the kernel fixmap page table is
1887           positioned, so this cannot be larger than 1GiB currently. Without
1888           RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1889           and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1890           modules area will shrink to compensate, up to the current maximum
1891           1GiB to 1GiB split. The default is 1GiB.
1892 
1893           If unsure, leave at the default value.
1894 
1895 # Relocation on x86 needs some additional build support
1896 config X86_NEED_RELOCS
1897         def_bool y
1898         depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1899 
1900 config PHYSICAL_ALIGN
1901         hex "Alignment value to which kernel should be aligned"
1902         default "0x200000"
1903         range 0x2000 0x1000000 if X86_32
1904         range 0x200000 0x1000000 if X86_64
1905         ---help---
1906           This value puts the alignment restrictions on physical address
1907           where kernel is loaded and run from. Kernel is compiled for an
1908           address which meets above alignment restriction.
1909 
1910           If bootloader loads the kernel at a non-aligned address and
1911           CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1912           address aligned to above value and run from there.
1913 
1914           If bootloader loads the kernel at a non-aligned address and
1915           CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1916           load address and decompress itself to the address it has been
1917           compiled for and run from there. The address for which kernel is
1918           compiled already meets above alignment restrictions. Hence the
1919           end result is that kernel runs from a physical address meeting
1920           above alignment restrictions.
1921 
1922           On 32-bit this value must be a multiple of 0x2000. On 64-bit
1923           this value must be a multiple of 0x200000.
1924 
1925           Don't change this unless you know what you are doing.
1926 
1927 config HOTPLUG_CPU
1928         bool "Support for hot-pluggable CPUs"
1929         depends on SMP
1930         ---help---
1931           Say Y here to allow turning CPUs off and on. CPUs can be
1932           controlled through /sys/devices/system/cpu.
1933           ( Note: power management support will enable this option
1934             automatically on SMP systems. )
1935           Say N if you want to disable CPU hotplug.
1936 
1937 config BOOTPARAM_HOTPLUG_CPU0
1938         bool "Set default setting of cpu0_hotpluggable"
1939         default n
1940         depends on HOTPLUG_CPU
1941         ---help---
1942           Set whether default state of cpu0_hotpluggable is on or off.
1943 
1944           Say Y here to enable CPU0 hotplug by default. If this switch
1945           is turned on, there is no need to give cpu0_hotplug kernel
1946           parameter and the CPU0 hotplug feature is enabled by default.
1947 
1948           Please note: there are two known CPU0 dependencies if you want
1949           to enable the CPU0 hotplug feature either by this switch or by
1950           cpu0_hotplug kernel parameter.
1951 
1952           First, resume from hibernate or suspend always starts from CPU0.
1953           So hibernate and suspend are prevented if CPU0 is offline.
1954 
1955           Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1956           offline if any interrupt can not migrate out of CPU0. There may
1957           be other CPU0 dependencies.
1958 
1959           Please make sure the dependencies are under your control before
1960           you enable this feature.
1961 
1962           Say N if you don't want to enable CPU0 hotplug feature by default.
1963           You still can enable the CPU0 hotplug feature at boot by kernel
1964           parameter cpu0_hotplug.
1965 
1966 config DEBUG_HOTPLUG_CPU0
1967         def_bool n
1968         prompt "Debug CPU0 hotplug"
1969         depends on HOTPLUG_CPU
1970         ---help---
1971           Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1972           soon as possible and boots up userspace with CPU0 offlined. User
1973           can online CPU0 back after boot time.
1974 
1975           To debug CPU0 hotplug, you need to enable CPU0 offline/online
1976           feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1977           compilation or giving cpu0_hotplug kernel parameter at boot.
1978 
1979           If unsure, say N.
1980 
1981 config COMPAT_VDSO
1982         def_bool n
1983         prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
1984         depends on X86_32 || IA32_EMULATION
1985         ---help---
1986           Certain buggy versions of glibc will crash if they are
1987           presented with a 32-bit vDSO that is not mapped at the address
1988           indicated in its segment table.
1989 
1990           The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
1991           and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
1992           49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
1993           the only released version with the bug, but OpenSUSE 9
1994           contains a buggy "glibc 2.3.2".
1995 
1996           The symptom of the bug is that everything crashes on startup, saying:
1997           dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
1998 
1999           Saying Y here changes the default value of the vdso32 boot
2000           option from 1 to 0, which turns off the 32-bit vDSO entirely.
2001           This works around the glibc bug but hurts performance.
2002 
2003           If unsure, say N: if you are compiling your own kernel, you
2004           are unlikely to be using a buggy version of glibc.
2005 
2006 config CMDLINE_BOOL
2007         bool "Built-in kernel command line"
2008         ---help---
2009           Allow for specifying boot arguments to the kernel at
2010           build time.  On some systems (e.g. embedded ones), it is
2011           necessary or convenient to provide some or all of the
2012           kernel boot arguments with the kernel itself (that is,
2013           to not rely on the boot loader to provide them.)
2014 
2015           To compile command line arguments into the kernel,
2016           set this option to 'Y', then fill in the
2017           the boot arguments in CONFIG_CMDLINE.
2018 
2019           Systems with fully functional boot loaders (i.e. non-embedded)
2020           should leave this option set to 'N'.
2021 
2022 config CMDLINE
2023         string "Built-in kernel command string"
2024         depends on CMDLINE_BOOL
2025         default ""
2026         ---help---
2027           Enter arguments here that should be compiled into the kernel
2028           image and used at boot time.  If the boot loader provides a
2029           command line at boot time, it is appended to this string to
2030           form the full kernel command line, when the system boots.
2031 
2032           However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2033           change this behavior.
2034 
2035           In most cases, the command line (whether built-in or provided
2036           by the boot loader) should specify the device for the root
2037           file system.
2038 
2039 config CMDLINE_OVERRIDE
2040         bool "Built-in command line overrides boot loader arguments"
2041         depends on CMDLINE_BOOL
2042         ---help---
2043           Set this option to 'Y' to have the kernel ignore the boot loader
2044           command line, and use ONLY the built-in command line.
2045 
2046           This is used to work around broken boot loaders.  This should
2047           be set to 'N' under normal conditions.
2048 
2049 source "kernel/livepatch/Kconfig"
2050 
2051 endmenu
2052 
2053 config ARCH_ENABLE_MEMORY_HOTPLUG
2054         def_bool y
2055         depends on X86_64 || (X86_32 && HIGHMEM)
2056 
2057 config ARCH_ENABLE_MEMORY_HOTREMOVE
2058         def_bool y
2059         depends on MEMORY_HOTPLUG
2060 
2061 config USE_PERCPU_NUMA_NODE_ID
2062         def_bool y
2063         depends on NUMA
2064 
2065 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2066         def_bool y
2067         depends on X86_64 || X86_PAE
2068 
2069 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2070         def_bool y
2071         depends on X86_64 && HUGETLB_PAGE && MIGRATION
2072 
2073 menu "Power management and ACPI options"
2074 
2075 config ARCH_HIBERNATION_HEADER
2076         def_bool y
2077         depends on X86_64 && HIBERNATION
2078 
2079 source "kernel/power/Kconfig"
2080 
2081 source "drivers/acpi/Kconfig"
2082 
2083 source "drivers/sfi/Kconfig"
2084 
2085 config X86_APM_BOOT
2086         def_bool y
2087         depends on APM
2088 
2089 menuconfig APM
2090         tristate "APM (Advanced Power Management) BIOS support"
2091         depends on X86_32 && PM_SLEEP
2092         ---help---
2093           APM is a BIOS specification for saving power using several different
2094           techniques. This is mostly useful for battery powered laptops with
2095           APM compliant BIOSes. If you say Y here, the system time will be
2096           reset after a RESUME operation, the /proc/apm device will provide
2097           battery status information, and user-space programs will receive
2098           notification of APM "events" (e.g. battery status change).
2099 
2100           If you select "Y" here, you can disable actual use of the APM
2101           BIOS by passing the "apm=off" option to the kernel at boot time.
2102 
2103           Note that the APM support is almost completely disabled for
2104           machines with more than one CPU.
2105 
2106           In order to use APM, you will need supporting software. For location
2107           and more information, read <file:Documentation/power/apm-acpi.txt>
2108           and the Battery Powered Linux mini-HOWTO, available from
2109           <http://www.tldp.org/docs.html#howto>.
2110 
2111           This driver does not spin down disk drives (see the hdparm(8)
2112           manpage ("man 8 hdparm") for that), and it doesn't turn off
2113           VESA-compliant "green" monitors.
2114 
2115           This driver does not support the TI 4000M TravelMate and the ACER
2116           486/DX4/75 because they don't have compliant BIOSes. Many "green"
2117           desktop machines also don't have compliant BIOSes, and this driver
2118           may cause those machines to panic during the boot phase.
2119 
2120           Generally, if you don't have a battery in your machine, there isn't
2121           much point in using this driver and you should say N. If you get
2122           random kernel OOPSes or reboots that don't seem to be related to
2123           anything, try disabling/enabling this option (or disabling/enabling
2124           APM in your BIOS).
2125 
2126           Some other things you should try when experiencing seemingly random,
2127           "weird" problems:
2128 
2129           1) make sure that you have enough swap space and that it is
2130           enabled.
2131           2) pass the "no-hlt" option to the kernel
2132           3) switch on floating point emulation in the kernel and pass
2133           the "no387" option to the kernel
2134           4) pass the "floppy=nodma" option to the kernel
2135           5) pass the "mem=4M" option to the kernel (thereby disabling
2136           all but the first 4 MB of RAM)
2137           6) make sure that the CPU is not over clocked.
2138           7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2139           8) disable the cache from your BIOS settings
2140           9) install a fan for the video card or exchange video RAM
2141           10) install a better fan for the CPU
2142           11) exchange RAM chips
2143           12) exchange the motherboard.
2144 
2145           To compile this driver as a module, choose M here: the
2146           module will be called apm.
2147 
2148 if APM
2149 
2150 config APM_IGNORE_USER_SUSPEND
2151         bool "Ignore USER SUSPEND"
2152         ---help---
2153           This option will ignore USER SUSPEND requests. On machines with a
2154           compliant APM BIOS, you want to say N. However, on the NEC Versa M
2155           series notebooks, it is necessary to say Y because of a BIOS bug.
2156 
2157 config APM_DO_ENABLE
2158         bool "Enable PM at boot time"
2159         ---help---
2160           Enable APM features at boot time. From page 36 of the APM BIOS
2161           specification: "When disabled, the APM BIOS does not automatically
2162           power manage devices, enter the Standby State, enter the Suspend
2163           State, or take power saving steps in response to CPU Idle calls."
2164           This driver will make CPU Idle calls when Linux is idle (unless this
2165           feature is turned off -- see "Do CPU IDLE calls", below). This
2166           should always save battery power, but more complicated APM features
2167           will be dependent on your BIOS implementation. You may need to turn
2168           this option off if your computer hangs at boot time when using APM
2169           support, or if it beeps continuously instead of suspending. Turn
2170           this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2171           T400CDT. This is off by default since most machines do fine without
2172           this feature.
2173 
2174 config APM_CPU_IDLE
2175         depends on CPU_IDLE
2176         bool "Make CPU Idle calls when idle"
2177         ---help---
2178           Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2179           On some machines, this can activate improved power savings, such as
2180           a slowed CPU clock rate, when the machine is idle. These idle calls
2181           are made after the idle loop has run for some length of time (e.g.,
2182           333 mS). On some machines, this will cause a hang at boot time or
2183           whenever the CPU becomes idle. (On machines with more than one CPU,
2184           this option does nothing.)
2185 
2186 config APM_DISPLAY_BLANK
2187         bool "Enable console blanking using APM"
2188         ---help---
2189           Enable console blanking using the APM. Some laptops can use this to
2190           turn off the LCD backlight when the screen blanker of the Linux
2191           virtual console blanks the screen. Note that this is only used by
2192           the virtual console screen blanker, and won't turn off the backlight
2193           when using the X Window system. This also doesn't have anything to
2194           do with your VESA-compliant power-saving monitor. Further, this
2195           option doesn't work for all laptops -- it might not turn off your
2196           backlight at all, or it might print a lot of errors to the console,
2197           especially if you are using gpm.
2198 
2199 config APM_ALLOW_INTS
2200         bool "Allow interrupts during APM BIOS calls"
2201         ---help---
2202           Normally we disable external interrupts while we are making calls to
2203           the APM BIOS as a measure to lessen the effects of a badly behaving
2204           BIOS implementation.  The BIOS should reenable interrupts if it
2205           needs to.  Unfortunately, some BIOSes do not -- especially those in
2206           many of the newer IBM Thinkpads.  If you experience hangs when you
2207           suspend, try setting this to Y.  Otherwise, say N.
2208 
2209 endif # APM
2210 
2211 source "drivers/cpufreq/Kconfig"
2212 
2213 source "drivers/cpuidle/Kconfig"
2214 
2215 source "drivers/idle/Kconfig"
2216 
2217 endmenu
2218 
2219 
2220 menu "Bus options (PCI etc.)"
2221 
2222 config PCI
2223         bool "PCI support"
2224         default y
2225         ---help---
2226           Find out whether you have a PCI motherboard. PCI is the name of a
2227           bus system, i.e. the way the CPU talks to the other stuff inside
2228           your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2229           VESA. If you have PCI, say Y, otherwise N.
2230 
2231 choice
2232         prompt "PCI access mode"
2233         depends on X86_32 && PCI
2234         default PCI_GOANY
2235         ---help---
2236           On PCI systems, the BIOS can be used to detect the PCI devices and
2237           determine their configuration. However, some old PCI motherboards
2238           have BIOS bugs and may crash if this is done. Also, some embedded
2239           PCI-based systems don't have any BIOS at all. Linux can also try to
2240           detect the PCI hardware directly without using the BIOS.
2241 
2242           With this option, you can specify how Linux should detect the
2243           PCI devices. If you choose "BIOS", the BIOS will be used,
2244           if you choose "Direct", the BIOS won't be used, and if you
2245           choose "MMConfig", then PCI Express MMCONFIG will be used.
2246           If you choose "Any", the kernel will try MMCONFIG, then the
2247           direct access method and falls back to the BIOS if that doesn't
2248           work. If unsure, go with the default, which is "Any".
2249 
2250 config PCI_GOBIOS
2251         bool "BIOS"
2252 
2253 config PCI_GOMMCONFIG
2254         bool "MMConfig"
2255 
2256 config PCI_GODIRECT
2257         bool "Direct"
2258 
2259 config PCI_GOOLPC
2260         bool "OLPC XO-1"
2261         depends on OLPC
2262 
2263 config PCI_GOANY
2264         bool "Any"
2265 
2266 endchoice
2267 
2268 config PCI_BIOS
2269         def_bool y
2270         depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2271 
2272 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2273 config PCI_DIRECT
2274         def_bool y
2275         depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2276 
2277 config PCI_MMCONFIG
2278         def_bool y
2279         depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2280 
2281 config PCI_OLPC
2282         def_bool y
2283         depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2284 
2285 config PCI_XEN
2286         def_bool y
2287         depends on PCI && XEN
2288         select SWIOTLB_XEN
2289 
2290 config PCI_DOMAINS
2291         def_bool y
2292         depends on PCI
2293 
2294 config PCI_MMCONFIG
2295         bool "Support mmconfig PCI config space access"
2296         depends on X86_64 && PCI && ACPI
2297 
2298 config PCI_CNB20LE_QUIRK
2299         bool "Read CNB20LE Host Bridge Windows" if EXPERT
2300         depends on PCI
2301         help
2302           Read the PCI windows out of the CNB20LE host bridge. This allows
2303           PCI hotplug to work on systems with the CNB20LE chipset which do
2304           not have ACPI.
2305 
2306           There's no public spec for this chipset, and this functionality
2307           is known to be incomplete.
2308 
2309           You should say N unless you know you need this.
2310 
2311 source "drivers/pci/pcie/Kconfig"
2312 
2313 source "drivers/pci/Kconfig"
2314 
2315 # x86_64 have no ISA slots, but can have ISA-style DMA.
2316 config ISA_DMA_API
2317         bool "ISA-style DMA support" if (X86_64 && EXPERT)
2318         default y
2319         help
2320           Enables ISA-style DMA support for devices requiring such controllers.
2321           If unsure, say Y.
2322 
2323 if X86_32
2324 
2325 config ISA
2326         bool "ISA support"
2327         ---help---
2328           Find out whether you have ISA slots on your motherboard.  ISA is the
2329           name of a bus system, i.e. the way the CPU talks to the other stuff
2330           inside your box.  Other bus systems are PCI, EISA, MicroChannel
2331           (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2332           newer boards don't support it.  If you have ISA, say Y, otherwise N.
2333 
2334 config EISA
2335         bool "EISA support"
2336         depends on ISA
2337         ---help---
2338           The Extended Industry Standard Architecture (EISA) bus was
2339           developed as an open alternative to the IBM MicroChannel bus.
2340 
2341           The EISA bus provided some of the features of the IBM MicroChannel
2342           bus while maintaining backward compatibility with cards made for
2343           the older ISA bus.  The EISA bus saw limited use between 1988 and
2344           1995 when it was made obsolete by the PCI bus.
2345 
2346           Say Y here if you are building a kernel for an EISA-based machine.
2347 
2348           Otherwise, say N.
2349 
2350 source "drivers/eisa/Kconfig"
2351 
2352 config SCx200
2353         tristate "NatSemi SCx200 support"
2354         ---help---
2355           This provides basic support for National Semiconductor's
2356           (now AMD's) Geode processors.  The driver probes for the
2357           PCI-IDs of several on-chip devices, so its a good dependency
2358           for other scx200_* drivers.
2359 
2360           If compiled as a module, the driver is named scx200.
2361 
2362 config SCx200HR_TIMER
2363         tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2364         depends on SCx200
2365         default y
2366         ---help---
2367           This driver provides a clocksource built upon the on-chip
2368           27MHz high-resolution timer.  Its also a workaround for
2369           NSC Geode SC-1100's buggy TSC, which loses time when the
2370           processor goes idle (as is done by the scheduler).  The
2371           other workaround is idle=poll boot option.
2372 
2373 config OLPC
2374         bool "One Laptop Per Child support"
2375         depends on !X86_PAE
2376         select GPIOLIB
2377         select OF
2378         select OF_PROMTREE
2379         select IRQ_DOMAIN
2380         ---help---
2381           Add support for detecting the unique features of the OLPC
2382           XO hardware.
2383 
2384 config OLPC_XO1_PM
2385         bool "OLPC XO-1 Power Management"
2386         depends on OLPC && MFD_CS5535 && PM_SLEEP
2387         select MFD_CORE
2388         ---help---
2389           Add support for poweroff and suspend of the OLPC XO-1 laptop.
2390 
2391 config OLPC_XO1_RTC
2392         bool "OLPC XO-1 Real Time Clock"
2393         depends on OLPC_XO1_PM && RTC_DRV_CMOS
2394         ---help---
2395           Add support for the XO-1 real time clock, which can be used as a
2396           programmable wakeup source.
2397 
2398 config OLPC_XO1_SCI
2399         bool "OLPC XO-1 SCI extras"
2400         depends on OLPC && OLPC_XO1_PM
2401         depends on INPUT=y
2402         select POWER_SUPPLY
2403         select GPIO_CS5535
2404         select MFD_CORE
2405         ---help---
2406           Add support for SCI-based features of the OLPC XO-1 laptop:
2407            - EC-driven system wakeups
2408            - Power button
2409            - Ebook switch
2410            - Lid switch
2411            - AC adapter status updates
2412            - Battery status updates
2413 
2414 config OLPC_XO15_SCI
2415         bool "OLPC XO-1.5 SCI extras"
2416         depends on OLPC && ACPI
2417         select POWER_SUPPLY
2418         ---help---
2419           Add support for SCI-based features of the OLPC XO-1.5 laptop:
2420            - EC-driven system wakeups
2421            - AC adapter status updates
2422            - Battery status updates
2423 
2424 config ALIX
2425         bool "PCEngines ALIX System Support (LED setup)"
2426         select GPIOLIB
2427         ---help---
2428           This option enables system support for the PCEngines ALIX.
2429           At present this just sets up LEDs for GPIO control on
2430           ALIX2/3/6 boards.  However, other system specific setup should
2431           get added here.
2432 
2433           Note: You must still enable the drivers for GPIO and LED support
2434           (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2435 
2436           Note: You have to set alix.force=1 for boards with Award BIOS.
2437 
2438 config NET5501
2439         bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2440         select GPIOLIB
2441         ---help---
2442           This option enables system support for the Soekris Engineering net5501.
2443 
2444 config GEOS
2445         bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2446         select GPIOLIB
2447         depends on DMI
2448         ---help---
2449           This option enables system support for the Traverse Technologies GEOS.
2450 
2451 config TS5500
2452         bool "Technologic Systems TS-5500 platform support"
2453         depends on MELAN
2454         select CHECK_SIGNATURE
2455         select NEW_LEDS
2456         select LEDS_CLASS
2457         ---help---
2458           This option enables system support for the Technologic Systems TS-5500.
2459 
2460 endif # X86_32
2461 
2462 config AMD_NB
2463         def_bool y
2464         depends on CPU_SUP_AMD && PCI
2465 
2466 source "drivers/pcmcia/Kconfig"
2467 
2468 source "drivers/pci/hotplug/Kconfig"
2469 
2470 config RAPIDIO
2471         tristate "RapidIO support"
2472         depends on PCI
2473         default n
2474         help
2475           If enabled this option will include drivers and the core
2476           infrastructure code to support RapidIO interconnect devices.
2477 
2478 source "drivers/rapidio/Kconfig"
2479 
2480 config X86_SYSFB
2481         bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2482         help
2483           Firmwares often provide initial graphics framebuffers so the BIOS,
2484           bootloader or kernel can show basic video-output during boot for
2485           user-guidance and debugging. Historically, x86 used the VESA BIOS
2486           Extensions and EFI-framebuffers for this, which are mostly limited
2487           to x86.
2488           This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2489           framebuffers so the new generic system-framebuffer drivers can be
2490           used on x86. If the framebuffer is not compatible with the generic
2491           modes, it is adverticed as fallback platform framebuffer so legacy
2492           drivers like efifb, vesafb and uvesafb can pick it up.
2493           If this option is not selected, all system framebuffers are always
2494           marked as fallback platform framebuffers as usual.
2495 
2496           Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2497           not be able to pick up generic system framebuffers if this option
2498           is selected. You are highly encouraged to enable simplefb as
2499           replacement if you select this option. simplefb can correctly deal
2500           with generic system framebuffers. But you should still keep vesafb
2501           and others enabled as fallback if a system framebuffer is
2502           incompatible with simplefb.
2503 
2504           If unsure, say Y.
2505 
2506 endmenu
2507 
2508 
2509 menu "Executable file formats / Emulations"
2510 
2511 source "fs/Kconfig.binfmt"
2512 
2513 config IA32_EMULATION
2514         bool "IA32 Emulation"
2515         depends on X86_64
2516         select BINFMT_ELF
2517         select COMPAT_BINFMT_ELF
2518         select HAVE_UID16
2519         ---help---
2520           Include code to run legacy 32-bit programs under a
2521           64-bit kernel. You should likely turn this on, unless you're
2522           100% sure that you don't have any 32-bit programs left.
2523 
2524 config IA32_AOUT
2525         tristate "IA32 a.out support"
2526         depends on IA32_EMULATION
2527         ---help---
2528           Support old a.out binaries in the 32bit emulation.
2529 
2530 config X86_X32
2531         bool "x32 ABI for 64-bit mode"
2532         depends on X86_64 && IA32_EMULATION
2533         ---help---
2534           Include code to run binaries for the x32 native 32-bit ABI
2535           for 64-bit processors.  An x32 process gets access to the
2536           full 64-bit register file and wide data path while leaving
2537           pointers at 32 bits for smaller memory footprint.
2538 
2539           You will need a recent binutils (2.22 or later) with
2540           elf32_x86_64 support enabled to compile a kernel with this
2541           option set.
2542 
2543 config COMPAT
2544         def_bool y
2545         depends on IA32_EMULATION || X86_X32
2546         select ARCH_WANT_OLD_COMPAT_IPC
2547 
2548 if COMPAT
2549 config COMPAT_FOR_U64_ALIGNMENT
2550         def_bool y
2551 
2552 config SYSVIPC_COMPAT
2553         def_bool y
2554         depends on SYSVIPC
2555 
2556 config KEYS_COMPAT
2557         def_bool y
2558         depends on KEYS
2559 endif
2560 
2561 endmenu
2562 
2563 
2564 config HAVE_ATOMIC_IOMAP
2565         def_bool y
2566         depends on X86_32
2567 
2568 config X86_DEV_DMA_OPS
2569         bool
2570         depends on X86_64 || STA2X11
2571 
2572 config X86_DMA_REMAP
2573         bool
2574         depends on STA2X11
2575 
2576 config PMC_ATOM
2577         def_bool y
2578         depends on PCI
2579 
2580 source "net/Kconfig"
2581 
2582 source "drivers/Kconfig"
2583 
2584 source "drivers/firmware/Kconfig"
2585 
2586 source "fs/Kconfig"
2587 
2588 source "arch/x86/Kconfig.debug"
2589 
2590 source "security/Kconfig"
2591 
2592 source "crypto/Kconfig"
2593 
2594 source "arch/x86/kvm/Kconfig"
2595 
2596 source "lib/Kconfig"

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