3 bool "64-bit kernel" if ARCH = "x86"
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
20 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
21 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
23 select ARCH_CLOCKSOURCE_DATA
24 select ARCH_DISCARD_MEMBLOCK
25 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
26 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
27 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
28 select ARCH_HAS_DEVMEM_IS_ALLOWED
29 select ARCH_HAS_ELF_RANDOMIZE
30 select ARCH_HAS_FAST_MULTIPLIER
31 select ARCH_HAS_GCOV_PROFILE_ALL
32 select ARCH_HAS_KCOV if X86_64
33 select ARCH_HAS_PMEM_API if X86_64
34 select ARCH_HAS_MMIO_FLUSH
35 select ARCH_HAS_SG_CHAIN
36 select ARCH_HAS_UBSAN_SANITIZE_ALL
37 select ARCH_HAVE_NMI_SAFE_CMPXCHG
38 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
39 select ARCH_MIGHT_HAVE_PC_PARPORT
40 select ARCH_MIGHT_HAVE_PC_SERIO
41 select ARCH_SUPPORTS_ATOMIC_RMW
42 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
43 select ARCH_SUPPORTS_INT128 if X86_64
44 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
45 select ARCH_USE_BUILTIN_BSWAP
46 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
47 select ARCH_USE_QUEUED_RWLOCKS
48 select ARCH_USE_QUEUED_SPINLOCKS
49 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
50 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
51 select ARCH_WANT_FRAME_POINTERS
52 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
53 select BUILDTIME_EXTABLE_SORT
55 select CLKSRC_I8253 if X86_32
56 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
57 select CLOCKSOURCE_WATCHDOG
58 select CLONE_BACKWARDS if X86_32
59 select COMPAT_OLD_SIGACTION if IA32_EMULATION
60 select DCACHE_WORD_ACCESS
61 select EDAC_ATOMIC_SCRUB
63 select GENERIC_CLOCKEVENTS
64 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
65 select GENERIC_CLOCKEVENTS_MIN_ADJUST
66 select GENERIC_CMOS_UPDATE
67 select GENERIC_CPU_AUTOPROBE
68 select GENERIC_EARLY_IOREMAP
69 select GENERIC_FIND_FIRST_BIT
71 select GENERIC_IRQ_PROBE
72 select GENERIC_IRQ_SHOW
73 select GENERIC_PENDING_IRQ if SMP
74 select GENERIC_SMP_IDLE_THREAD
75 select GENERIC_STRNCPY_FROM_USER
76 select GENERIC_STRNLEN_USER
77 select GENERIC_TIME_VSYSCALL
78 select HAVE_ACPI_APEI if ACPI
79 select HAVE_ACPI_APEI_NMI if ACPI
80 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
81 select HAVE_AOUT if X86_32
82 select HAVE_ARCH_AUDITSYSCALL
83 select HAVE_ARCH_HARDENED_USERCOPY
84 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
85 select HAVE_ARCH_JUMP_LABEL
86 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
88 select HAVE_ARCH_KMEMCHECK
89 select HAVE_ARCH_MMAP_RND_BITS if MMU
90 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
91 select HAVE_ARCH_SECCOMP_FILTER
92 select HAVE_ARCH_SOFT_DIRTY if X86_64
93 select HAVE_ARCH_TRACEHOOK
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
95 select HAVE_ARCH_WITHIN_STACK_FRAMES
96 select HAVE_EBPF_JIT if X86_64
97 select HAVE_CC_STACKPROTECTOR
98 select HAVE_CMPXCHG_DOUBLE
99 select HAVE_CMPXCHG_LOCAL
100 select HAVE_CONTEXT_TRACKING if X86_64
101 select HAVE_COPY_THREAD_TLS
102 select HAVE_C_RECORDMCOUNT
103 select HAVE_DEBUG_KMEMLEAK
104 select HAVE_DEBUG_STACKOVERFLOW
105 select HAVE_DMA_API_DEBUG
106 select HAVE_DMA_CONTIGUOUS
107 select HAVE_DYNAMIC_FTRACE
108 select HAVE_DYNAMIC_FTRACE_WITH_REGS
109 select HAVE_EFFICIENT_UNALIGNED_ACCESS
110 select HAVE_EXIT_THREAD
111 select HAVE_FENTRY if X86_64
112 select HAVE_FTRACE_MCOUNT_RECORD
113 select HAVE_FUNCTION_GRAPH_FP_TEST
114 select HAVE_FUNCTION_GRAPH_TRACER
115 select HAVE_FUNCTION_TRACER
116 select HAVE_GCC_PLUGINS
117 select HAVE_GENERIC_DMA_COHERENT if X86_32
118 select HAVE_HW_BREAKPOINT
120 select HAVE_IOREMAP_PROT
121 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
122 select HAVE_IRQ_TIME_ACCOUNTING
123 select HAVE_KERNEL_BZIP2
124 select HAVE_KERNEL_GZIP
125 select HAVE_KERNEL_LZ4
126 select HAVE_KERNEL_LZMA
127 select HAVE_KERNEL_LZO
128 select HAVE_KERNEL_XZ
130 select HAVE_KPROBES_ON_FTRACE
131 select HAVE_KRETPROBES
133 select HAVE_LIVEPATCH if X86_64
135 select HAVE_MEMBLOCK_NODE_MAP
136 select HAVE_MIXED_BREAKPOINTS_REGS
139 select HAVE_OPTPROBES
140 select HAVE_PCSPKR_PLATFORM
141 select HAVE_PERF_EVENTS
142 select HAVE_PERF_EVENTS_NMI
143 select HAVE_PERF_REGS
144 select HAVE_PERF_USER_STACK_DUMP
145 select HAVE_REGS_AND_STACK_ACCESS_API
146 select HAVE_SYSCALL_TRACEPOINTS
147 select HAVE_UID16 if X86_32 || IA32_EMULATION
148 select HAVE_UNSTABLE_SCHED_CLOCK
149 select HAVE_USER_RETURN_NOTIFIER
150 select IRQ_FORCED_THREADING
151 select MODULES_USE_ELF_RELA if X86_64
152 select MODULES_USE_ELF_REL if X86_32
153 select OLD_SIGACTION if X86_32
154 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
157 select RTC_MC146818_LIB
160 select SYSCTL_EXCEPTION_TRACE
161 select USER_STACKTRACE_SUPPORT
163 select X86_DEV_DMA_OPS if X86_64
164 select X86_FEATURE_NAMES if PROC_FS
165 select HAVE_STACK_VALIDATION if X86_64
166 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
167 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
169 config INSTRUCTION_DECODER
171 depends on KPROBES || PERF_EVENTS || UPROBES
175 default "elf32-i386" if X86_32
176 default "elf64-x86-64" if X86_64
178 config ARCH_DEFCONFIG
180 default "arch/x86/configs/i386_defconfig" if X86_32
181 default "arch/x86/configs/x86_64_defconfig" if X86_64
183 config LOCKDEP_SUPPORT
186 config STACKTRACE_SUPPORT
192 config ARCH_MMAP_RND_BITS_MIN
196 config ARCH_MMAP_RND_BITS_MAX
200 config ARCH_MMAP_RND_COMPAT_BITS_MIN
203 config ARCH_MMAP_RND_COMPAT_BITS_MAX
209 config NEED_DMA_MAP_STATE
211 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
213 config NEED_SG_DMA_LENGTH
216 config GENERIC_ISA_DMA
218 depends on ISA_DMA_API
223 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
225 config GENERIC_BUG_RELATIVE_POINTERS
228 config GENERIC_HWEIGHT
231 config ARCH_MAY_HAVE_PC_FDC
233 depends on ISA_DMA_API
235 config RWSEM_XCHGADD_ALGORITHM
238 config GENERIC_CALIBRATE_DELAY
241 config ARCH_HAS_CPU_RELAX
244 config ARCH_HAS_CACHE_LINE_SIZE
247 config HAVE_SETUP_PER_CPU_AREA
250 config NEED_PER_CPU_EMBED_FIRST_CHUNK
253 config NEED_PER_CPU_PAGE_FIRST_CHUNK
256 config ARCH_HIBERNATION_POSSIBLE
259 config ARCH_SUSPEND_POSSIBLE
262 config ARCH_WANT_HUGE_PMD_SHARE
265 config ARCH_WANT_GENERAL_HUGETLB
274 config ARCH_SUPPORTS_OPTIMIZED_INLINING
277 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
280 config KASAN_SHADOW_OFFSET
283 default 0xdffffc0000000000
285 config HAVE_INTEL_TXT
287 depends on INTEL_IOMMU && ACPI
291 depends on X86_32 && SMP
295 depends on X86_64 && SMP
297 config X86_32_LAZY_GS
299 depends on X86_32 && !CC_STACKPROTECTOR
301 config ARCH_SUPPORTS_UPROBES
304 config FIX_EARLYCON_MEM
310 config PGTABLE_LEVELS
316 source "init/Kconfig"
317 source "kernel/Kconfig.freezer"
319 menu "Processor type and features"
322 bool "DMA memory allocation support" if EXPERT
325 DMA memory allocation support allows devices with less than 32-bit
326 addressing to allocate within the first 16MB of address space.
327 Disable if no such devices will be used.
332 bool "Symmetric multi-processing support"
334 This enables support for systems with more than one CPU. If you have
335 a system with only one CPU, say N. If you have a system with more
338 If you say N here, the kernel will run on uni- and multiprocessor
339 machines, but will use only one CPU of a multiprocessor machine. If
340 you say Y here, the kernel will run on many, but not all,
341 uniprocessor machines. On a uniprocessor machine, the kernel
342 will run faster if you say N here.
344 Note that if you say Y here and choose architecture "586" or
345 "Pentium" under "Processor family", the kernel will not work on 486
346 architectures. Similarly, multiprocessor kernels for the "PPro"
347 architecture may not work on all Pentium based boards.
349 People using multiprocessor machines who say Y here should also say
350 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
351 Management" code will be disabled if you say Y here.
353 See also <file:Documentation/x86/i386/IO-APIC.txt>,
354 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
355 <http://www.tldp.org/docs.html#howto>.
357 If you don't know what to do here, say N.
359 config X86_FEATURE_NAMES
360 bool "Processor feature human-readable names" if EMBEDDED
363 This option compiles in a table of x86 feature bits and corresponding
364 names. This is required to support /proc/cpuinfo and a few kernel
365 messages. You can disable this to save space, at the expense of
366 making those few kernel messages show numeric feature bits instead.
370 config X86_FAST_FEATURE_TESTS
371 bool "Fast CPU feature tests" if EMBEDDED
374 Some fast-paths in the kernel depend on the capabilities of the CPU.
375 Say Y here for the kernel to patch in the appropriate code at runtime
376 based on the capabilities of the CPU. The infrastructure for patching
377 code at runtime takes up some additional space; space-constrained
378 embedded systems may wish to say N here to produce smaller, slightly
382 bool "Support x2apic"
383 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
385 This enables x2apic support on CPUs that have this feature.
387 This allows 32-bit apic IDs (so it can support very large systems),
388 and accesses the local apic via MSRs not via mmio.
390 If you don't know what to do here, say N.
393 bool "Enable MPS table" if ACPI || SFI
395 depends on X86_LOCAL_APIC
397 For old smp systems that do not have proper acpi support. Newer systems
398 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
401 bool "Support for big SMP systems with more than 8 CPUs"
402 depends on X86_32 && SMP
404 This option is needed for the systems that have more than 8 CPUs
408 depends on X86_GOLDFISH
411 config X86_EXTENDED_PLATFORM
412 bool "Support for extended (non-PC) x86 platforms"
415 If you disable this option then the kernel will only support
416 standard PC platforms. (which covers the vast majority of
419 If you enable this option then you'll be able to select support
420 for the following (non-PC) 32 bit x86 platforms:
421 Goldfish (Android emulator)
424 SGI 320/540 (Visual Workstation)
425 STA2X11-based (e.g. Northville)
426 Moorestown MID devices
428 If you have one of these systems, or if you want to build a
429 generic distribution kernel, say Y here - otherwise say N.
433 config X86_EXTENDED_PLATFORM
434 bool "Support for extended (non-PC) x86 platforms"
437 If you disable this option then the kernel will only support
438 standard PC platforms. (which covers the vast majority of
441 If you enable this option then you'll be able to select support
442 for the following (non-PC) 64 bit x86 platforms:
447 If you have one of these systems, or if you want to build a
448 generic distribution kernel, say Y here - otherwise say N.
450 # This is an alphabetically sorted list of 64 bit extended platforms
451 # Please maintain the alphabetic order if and when there are additions
453 bool "Numascale NumaChip"
455 depends on X86_EXTENDED_PLATFORM
458 depends on X86_X2APIC
459 depends on PCI_MMCONFIG
461 Adds support for Numascale NumaChip large-SMP systems. Needed to
462 enable more than ~168 cores.
463 If you don't have one of these, you should say N here.
467 select HYPERVISOR_GUEST
469 depends on X86_64 && PCI
470 depends on X86_EXTENDED_PLATFORM
473 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
474 supposed to run on these EM64T-based machines. Only choose this option
475 if you have one of these machines.
478 bool "SGI Ultraviolet"
480 depends on X86_EXTENDED_PLATFORM
483 depends on X86_X2APIC
486 This option is needed in order to support SGI Ultraviolet systems.
487 If you don't have one of these, you should say N here.
489 # Following is an alphabetically sorted list of 32 bit extended platforms
490 # Please maintain the alphabetic order if and when there are additions
493 bool "Goldfish (Virtual Platform)"
494 depends on X86_EXTENDED_PLATFORM
496 Enable support for the Goldfish virtual platform used primarily
497 for Android development. Unless you are building for the Android
498 Goldfish emulator say N here.
501 bool "CE4100 TV platform"
503 depends on PCI_GODIRECT
504 depends on X86_IO_APIC
506 depends on X86_EXTENDED_PLATFORM
507 select X86_REBOOTFIXUPS
509 select OF_EARLY_FLATTREE
511 Select for the Intel CE media processor (CE4100) SOC.
512 This option compiles in support for the CE4100 SOC for settop
513 boxes and media devices.
516 bool "Intel MID platform support"
517 depends on X86_EXTENDED_PLATFORM
518 depends on X86_PLATFORM_DEVICES
520 depends on X86_64 || (PCI_GOANY && X86_32)
521 depends on X86_IO_APIC
527 select MFD_INTEL_MSIC
529 Select to build a kernel capable of supporting Intel MID (Mobile
530 Internet Device) platform systems which do not have the PCI legacy
531 interfaces. If you are building for a PC class system say N here.
533 Intel MID platforms are based on an Intel processor and chipset which
534 consume less power than most of the x86 derivatives.
536 config X86_INTEL_QUARK
537 bool "Intel Quark platform support"
539 depends on X86_EXTENDED_PLATFORM
540 depends on X86_PLATFORM_DEVICES
544 depends on X86_IO_APIC
549 Select to include support for Quark X1000 SoC.
550 Say Y here if you have a Quark based system such as the Arduino
551 compatible Intel Galileo.
553 config X86_INTEL_LPSS
554 bool "Intel Low Power Subsystem Support"
555 depends on X86 && ACPI
560 Select to build support for Intel Low Power Subsystem such as
561 found on Intel Lynxpoint PCH. Selecting this option enables
562 things like clock tree (common clock framework) and pincontrol
563 which are needed by the LPSS peripheral drivers.
565 config X86_AMD_PLATFORM_DEVICE
566 bool "AMD ACPI2Platform devices support"
571 Select to interpret AMD specific ACPI device to platform device
572 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
573 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
574 implemented under PINCTRL subsystem.
577 tristate "Intel SoC IOSF Sideband support for SoC platforms"
580 This option enables sideband register access support for Intel SoC
581 platforms. On these platforms the IOSF sideband is used in lieu of
582 MSR's for some register accesses, mostly but not limited to thermal
583 and power. Drivers may query the availability of this device to
584 determine if they need the sideband in order to work on these
585 platforms. The sideband is available on the following SoC products.
586 This list is not meant to be exclusive.
591 You should say Y if you are running a kernel on one of these SoC's.
593 config IOSF_MBI_DEBUG
594 bool "Enable IOSF sideband access through debugfs"
595 depends on IOSF_MBI && DEBUG_FS
597 Select this option to expose the IOSF sideband access registers (MCR,
598 MDR, MCRX) through debugfs to write and read register information from
599 different units on the SoC. This is most useful for obtaining device
600 state information for debug and analysis. As this is a general access
601 mechanism, users of this option would have specific knowledge of the
602 device they want to access.
604 If you don't require the option or are in doubt, say N.
607 bool "RDC R-321x SoC"
609 depends on X86_EXTENDED_PLATFORM
611 select X86_REBOOTFIXUPS
613 This option is needed for RDC R-321x system-on-chip, also known
615 If you don't have one of these chips, you should say N here.
617 config X86_32_NON_STANDARD
618 bool "Support non-standard 32-bit SMP architectures"
619 depends on X86_32 && SMP
620 depends on X86_EXTENDED_PLATFORM
622 This option compiles in the bigsmp and STA2X11 default
623 subarchitectures. It is intended for a generic binary
624 kernel. If you select them all, kernel will probe it one by
625 one and will fallback to default.
627 # Alphabetically sorted list of Non standard 32 bit platforms
629 config X86_SUPPORTS_MEMORY_FAILURE
631 # MCE code calls memory_failure():
633 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
634 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
635 depends on X86_64 || !SPARSEMEM
636 select ARCH_SUPPORTS_MEMORY_FAILURE
639 bool "STA2X11 Companion Chip Support"
640 depends on X86_32_NON_STANDARD && PCI
641 select X86_DEV_DMA_OPS
648 This adds support for boards based on the STA2X11 IO-Hub,
649 a.k.a. "ConneXt". The chip is used in place of the standard
650 PC chipset, so all "standard" peripherals are missing. If this
651 option is selected the kernel will still be able to boot on
652 standard PC machines.
655 tristate "Eurobraille/Iris poweroff module"
658 The Iris machines from EuroBraille do not have APM or ACPI support
659 to shut themselves down properly. A special I/O sequence is
660 needed to do so, which is what this module does at
663 This is only for Iris machines from EuroBraille.
667 config SCHED_OMIT_FRAME_POINTER
669 prompt "Single-depth WCHAN output"
672 Calculate simpler /proc/<PID>/wchan values. If this option
673 is disabled then wchan values will recurse back to the
674 caller function. This provides more accurate wchan values,
675 at the expense of slightly more scheduling overhead.
677 If in doubt, say "Y".
679 menuconfig HYPERVISOR_GUEST
680 bool "Linux guest support"
682 Say Y here to enable options for running Linux under various hyper-
683 visors. This option enables basic hypervisor detection and platform
686 If you say N, all options in this submenu will be skipped and
687 disabled, and Linux guest support won't be built in.
692 bool "Enable paravirtualization code"
694 This changes the kernel so it can modify itself when it is run
695 under a hypervisor, potentially improving performance significantly
696 over full virtualization. However, when run without a hypervisor
697 the kernel is theoretically slower and slightly larger.
699 config PARAVIRT_DEBUG
700 bool "paravirt-ops debugging"
701 depends on PARAVIRT && DEBUG_KERNEL
703 Enable to debug paravirt_ops internals. Specifically, BUG if
704 a paravirt_op is missing when it is called.
706 config PARAVIRT_SPINLOCKS
707 bool "Paravirtualization layer for spinlocks"
708 depends on PARAVIRT && SMP
709 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
711 Paravirtualized spinlocks allow a pvops backend to replace the
712 spinlock implementation with something virtualization-friendly
713 (for example, block the virtual CPU rather than spinning).
715 It has a minimal impact on native kernels and gives a nice performance
716 benefit on paravirtualized KVM / Xen kernels.
718 If you are unsure how to answer this question, answer Y.
720 config QUEUED_LOCK_STAT
721 bool "Paravirt queued spinlock statistics"
722 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
724 Enable the collection of statistical data on the slowpath
725 behavior of paravirtualized queued spinlocks and report
728 source "arch/x86/xen/Kconfig"
731 bool "KVM Guest support (including kvmclock)"
733 select PARAVIRT_CLOCK
736 This option enables various optimizations for running under the KVM
737 hypervisor. It includes a paravirtualized clock, so that instead
738 of relying on a PIT (or probably other) emulation by the
739 underlying device model, the host provides the guest with
740 timing infrastructure such as time of day, and system time
743 bool "Enable debug information for KVM Guests in debugfs"
744 depends on KVM_GUEST && DEBUG_FS
747 This option enables collection of various statistics for KVM guest.
748 Statistics are displayed in debugfs filesystem. Enabling this option
749 may incur significant overhead.
751 source "arch/x86/lguest/Kconfig"
753 config PARAVIRT_TIME_ACCOUNTING
754 bool "Paravirtual steal time accounting"
758 Select this option to enable fine granularity task steal time
759 accounting. Time spent executing other tasks in parallel with
760 the current vCPU is discounted from the vCPU power. To account for
761 that, there can be a small performance impact.
763 If in doubt, say N here.
765 config PARAVIRT_CLOCK
768 endif #HYPERVISOR_GUEST
773 source "arch/x86/Kconfig.cpu"
777 prompt "HPET Timer Support" if X86_32
779 Use the IA-PC HPET (High Precision Event Timer) to manage
780 time in preference to the PIT and RTC, if a HPET is
782 HPET is the next generation timer replacing legacy 8254s.
783 The HPET provides a stable time base on SMP
784 systems, unlike the TSC, but it is more expensive to access,
785 as it is off-chip. The interface used is documented
786 in the HPET spec, revision 1.
788 You can safely choose Y here. However, HPET will only be
789 activated if the platform and the BIOS support this feature.
790 Otherwise the 8254 will be used for timing services.
792 Choose N to continue using the legacy 8254 timer.
794 config HPET_EMULATE_RTC
796 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
799 def_bool y if X86_INTEL_MID
800 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
802 depends on X86_INTEL_MID && SFI
804 APB timer is the replacement for 8254, HPET on X86 MID platforms.
805 The APBT provides a stable time base on SMP
806 systems, unlike the TSC, but it is more expensive to access,
807 as it is off-chip. APB timers are always running regardless of CPU
808 C states, they are used as per CPU clockevent device when possible.
810 # Mark as expert because too many people got it wrong.
811 # The code disables itself when not needed.
814 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
815 bool "Enable DMI scanning" if EXPERT
817 Enabled scanning of DMI to identify machine quirks. Say Y
818 here unless you have verified that your setup is not
819 affected by entries in the DMI blacklist. Required by PNP
823 bool "Old AMD GART IOMMU support"
825 depends on X86_64 && PCI && AMD_NB
827 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
828 GART based hardware IOMMUs.
830 The GART supports full DMA access for devices with 32-bit access
831 limitations, on systems with more than 3 GB. This is usually needed
832 for USB, sound, many IDE/SATA chipsets and some other devices.
834 Newer systems typically have a modern AMD IOMMU, supported via
835 the CONFIG_AMD_IOMMU=y config option.
837 In normal configurations this driver is only active when needed:
838 there's more than 3 GB of memory and the system contains a
839 32-bit limited device.
844 bool "IBM Calgary IOMMU support"
846 depends on X86_64 && PCI
848 Support for hardware IOMMUs in IBM's xSeries x366 and x460
849 systems. Needed to run systems with more than 3GB of memory
850 properly with 32-bit PCI devices that do not support DAC
851 (Double Address Cycle). Calgary also supports bus level
852 isolation, where all DMAs pass through the IOMMU. This
853 prevents them from going anywhere except their intended
854 destination. This catches hard-to-find kernel bugs and
855 mis-behaving drivers and devices that do not use the DMA-API
856 properly to set up their DMA buffers. The IOMMU can be
857 turned off at boot time with the iommu=off parameter.
858 Normally the kernel will make the right choice by itself.
861 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
863 prompt "Should Calgary be enabled by default?"
864 depends on CALGARY_IOMMU
866 Should Calgary be enabled by default? if you choose 'y', Calgary
867 will be used (if it exists). If you choose 'n', Calgary will not be
868 used even if it exists. If you choose 'n' and would like to use
869 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
872 # need this always selected by IOMMU for the VIA workaround
876 Support for software bounce buffers used on x86-64 systems
877 which don't have a hardware IOMMU. Using this PCI devices
878 which can only access 32-bits of memory can be used on systems
879 with more than 3 GB of memory.
884 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
887 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
888 depends on X86_64 && SMP && DEBUG_KERNEL
889 select CPUMASK_OFFSTACK
891 Enable maximum number of CPUS and NUMA Nodes for this architecture.
895 int "Maximum number of CPUs" if SMP && !MAXSMP
896 range 2 8 if SMP && X86_32 && !X86_BIGSMP
897 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
898 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
900 default "8192" if MAXSMP
901 default "32" if SMP && X86_BIGSMP
902 default "8" if SMP && X86_32
905 This allows you to specify the maximum number of CPUs which this
906 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
907 supported value is 8192, otherwise the maximum value is 512. The
908 minimum value which makes sense is 2.
910 This is purely to save memory - each supported CPU adds
911 approximately eight kilobytes to the kernel image.
914 bool "SMT (Hyperthreading) scheduler support"
917 SMT scheduler support improves the CPU scheduler's decision making
918 when dealing with Intel Pentium 4 chips with HyperThreading at a
919 cost of slightly increased overhead in some places. If unsure say
924 prompt "Multi-core scheduler support"
927 Multi-core scheduler support improves the CPU scheduler's decision
928 making when dealing with multi-core CPU chips at a cost of slightly
929 increased overhead in some places. If unsure say N here.
931 source "kernel/Kconfig.preempt"
935 depends on !SMP && X86_LOCAL_APIC
938 bool "Local APIC support on uniprocessors" if !PCI_MSI
940 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
942 A local APIC (Advanced Programmable Interrupt Controller) is an
943 integrated interrupt controller in the CPU. If you have a single-CPU
944 system which has a processor with a local APIC, you can say Y here to
945 enable and use it. If you say Y here even though your machine doesn't
946 have a local APIC, then the kernel will still run with no slowdown at
947 all. The local APIC supports CPU-generated self-interrupts (timer,
948 performance counters), and the NMI watchdog which detects hard
952 bool "IO-APIC support on uniprocessors"
953 depends on X86_UP_APIC
955 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
956 SMP-capable replacement for PC-style interrupt controllers. Most
957 SMP systems and many recent uniprocessor systems have one.
959 If you have a single-CPU system with an IO-APIC, you can say Y here
960 to use it. If you say Y here even though your machine doesn't have
961 an IO-APIC, then the kernel will still run with no slowdown at all.
963 config X86_LOCAL_APIC
965 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
966 select IRQ_DOMAIN_HIERARCHY
967 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
971 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
973 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
974 bool "Reroute for broken boot IRQs"
975 depends on X86_IO_APIC
977 This option enables a workaround that fixes a source of
978 spurious interrupts. This is recommended when threaded
979 interrupt handling is used on systems where the generation of
980 superfluous "boot interrupts" cannot be disabled.
982 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
983 entry in the chipset's IO-APIC is masked (as, e.g. the RT
984 kernel does during interrupt handling). On chipsets where this
985 boot IRQ generation cannot be disabled, this workaround keeps
986 the original IRQ line masked so that only the equivalent "boot
987 IRQ" is delivered to the CPUs. The workaround also tells the
988 kernel to set up the IRQ handler on the boot IRQ line. In this
989 way only one interrupt is delivered to the kernel. Otherwise
990 the spurious second interrupt may cause the kernel to bring
991 down (vital) interrupt lines.
993 Only affects "broken" chipsets. Interrupt sharing may be
994 increased on these systems.
997 bool "Machine Check / overheating reporting"
998 select GENERIC_ALLOCATOR
1001 Machine Check support allows the processor to notify the
1002 kernel if it detects a problem (e.g. overheating, data corruption).
1003 The action the kernel takes depends on the severity of the problem,
1004 ranging from warning messages to halting the machine.
1006 config X86_MCE_INTEL
1008 prompt "Intel MCE features"
1009 depends on X86_MCE && X86_LOCAL_APIC
1011 Additional support for intel specific MCE features such as
1012 the thermal monitor.
1016 prompt "AMD MCE features"
1017 depends on X86_MCE && X86_LOCAL_APIC
1019 Additional support for AMD specific MCE features such as
1020 the DRAM Error Threshold.
1022 config X86_ANCIENT_MCE
1023 bool "Support for old Pentium 5 / WinChip machine checks"
1024 depends on X86_32 && X86_MCE
1026 Include support for machine check handling on old Pentium 5 or WinChip
1027 systems. These typically need to be enabled explicitly on the command
1030 config X86_MCE_THRESHOLD
1031 depends on X86_MCE_AMD || X86_MCE_INTEL
1034 config X86_MCE_INJECT
1036 tristate "Machine check injector support"
1038 Provide support for injecting machine checks for testing purposes.
1039 If you don't know what a machine check is and you don't do kernel
1040 QA it is safe to say n.
1042 config X86_THERMAL_VECTOR
1044 depends on X86_MCE_INTEL
1046 source "arch/x86/events/Kconfig"
1048 config X86_LEGACY_VM86
1049 bool "Legacy VM86 support"
1053 This option allows user programs to put the CPU into V8086
1054 mode, which is an 80286-era approximation of 16-bit real mode.
1056 Some very old versions of X and/or vbetool require this option
1057 for user mode setting. Similarly, DOSEMU will use it if
1058 available to accelerate real mode DOS programs. However, any
1059 recent version of DOSEMU, X, or vbetool should be fully
1060 functional even without kernel VM86 support, as they will all
1061 fall back to software emulation. Nevertheless, if you are using
1062 a 16-bit DOS program where 16-bit performance matters, vm86
1063 mode might be faster than emulation and you might want to
1066 Note that any app that works on a 64-bit kernel is unlikely to
1067 need this option, as 64-bit kernels don't, and can't, support
1068 V8086 mode. This option is also unrelated to 16-bit protected
1069 mode and is not needed to run most 16-bit programs under Wine.
1071 Enabling this option increases the complexity of the kernel
1072 and slows down exception handling a tiny bit.
1074 If unsure, say N here.
1078 default X86_LEGACY_VM86
1081 bool "Enable support for 16-bit segments" if EXPERT
1083 depends on MODIFY_LDT_SYSCALL
1085 This option is required by programs like Wine to run 16-bit
1086 protected mode legacy code on x86 processors. Disabling
1087 this option saves about 300 bytes on i386, or around 6K text
1088 plus 16K runtime memory on x86-64,
1092 depends on X86_16BIT && X86_32
1096 depends on X86_16BIT && X86_64
1098 config X86_VSYSCALL_EMULATION
1099 bool "Enable vsyscall emulation" if EXPERT
1103 This enables emulation of the legacy vsyscall page. Disabling
1104 it is roughly equivalent to booting with vsyscall=none, except
1105 that it will also disable the helpful warning if a program
1106 tries to use a vsyscall. With this option set to N, offending
1107 programs will just segfault, citing addresses of the form
1110 This option is required by many programs built before 2013, and
1111 care should be used even with newer programs if set to N.
1113 Disabling this option saves about 7K of kernel size and
1114 possibly 4K of additional runtime pagetable memory.
1117 tristate "Toshiba Laptop support"
1120 This adds a driver to safely access the System Management Mode of
1121 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1122 not work on models with a Phoenix BIOS. The System Management Mode
1123 is used to set the BIOS and power saving options on Toshiba portables.
1125 For information on utilities to make use of this driver see the
1126 Toshiba Linux utilities web site at:
1127 <http://www.buzzard.org.uk/toshiba/>.
1129 Say Y if you intend to run this kernel on a Toshiba portable.
1133 tristate "Dell i8k legacy laptop support"
1135 select SENSORS_DELL_SMM
1137 This option enables legacy /proc/i8k userspace interface in hwmon
1138 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1139 temperature and allows controlling fan speeds of Dell laptops via
1140 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1141 it reports also power and hotkey status. For fan speed control is
1142 needed userspace package i8kutils.
1144 Say Y if you intend to run this kernel on old Dell laptops or want to
1145 use userspace package i8kutils.
1148 config X86_REBOOTFIXUPS
1149 bool "Enable X86 board specific fixups for reboot"
1152 This enables chipset and/or board specific fixups to be done
1153 in order to get reboot to work correctly. This is only needed on
1154 some combinations of hardware and BIOS. The symptom, for which
1155 this config is intended, is when reboot ends with a stalled/hung
1158 Currently, the only fixup is for the Geode machines using
1159 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1161 Say Y if you want to enable the fixup. Currently, it's safe to
1162 enable this option even if you don't need it.
1166 bool "CPU microcode loading support"
1168 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1171 If you say Y here, you will be able to update the microcode on
1172 Intel and AMD processors. The Intel support is for the IA32 family,
1173 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1174 AMD support is for families 0x10 and later. You will obviously need
1175 the actual microcode binary data itself which is not shipped with
1178 The preferred method to load microcode from a detached initrd is described
1179 in Documentation/x86/early-microcode.txt. For that you need to enable
1180 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1181 initrd for microcode blobs.
1183 In addition, you can build-in the microcode into the kernel. For that you
1184 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1185 to the CONFIG_EXTRA_FIRMWARE config option.
1187 config MICROCODE_INTEL
1188 bool "Intel microcode loading support"
1189 depends on MICROCODE
1193 This options enables microcode patch loading support for Intel
1196 For the current Intel microcode data package go to
1197 <https://downloadcenter.intel.com> and search for
1198 'Linux Processor Microcode Data File'.
1200 config MICROCODE_AMD
1201 bool "AMD microcode loading support"
1202 depends on MICROCODE
1205 If you select this option, microcode patch loading support for AMD
1206 processors will be enabled.
1208 config MICROCODE_OLD_INTERFACE
1210 depends on MICROCODE
1213 tristate "/dev/cpu/*/msr - Model-specific register support"
1215 This device gives privileged processes access to the x86
1216 Model-Specific Registers (MSRs). It is a character device with
1217 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1218 MSR accesses are directed to a specific CPU on multi-processor
1222 tristate "/dev/cpu/*/cpuid - CPU information support"
1224 This device gives processes access to the x86 CPUID instruction to
1225 be executed on a specific processor. It is a character device
1226 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1230 prompt "High Memory Support"
1237 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1238 However, the address space of 32-bit x86 processors is only 4
1239 Gigabytes large. That means that, if you have a large amount of
1240 physical memory, not all of it can be "permanently mapped" by the
1241 kernel. The physical memory that's not permanently mapped is called
1244 If you are compiling a kernel which will never run on a machine with
1245 more than 1 Gigabyte total physical RAM, answer "off" here (default
1246 choice and suitable for most users). This will result in a "3GB/1GB"
1247 split: 3GB are mapped so that each process sees a 3GB virtual memory
1248 space and the remaining part of the 4GB virtual memory space is used
1249 by the kernel to permanently map as much physical memory as
1252 If the machine has between 1 and 4 Gigabytes physical RAM, then
1255 If more than 4 Gigabytes is used then answer "64GB" here. This
1256 selection turns Intel PAE (Physical Address Extension) mode on.
1257 PAE implements 3-level paging on IA32 processors. PAE is fully
1258 supported by Linux, PAE mode is implemented on all recent Intel
1259 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1260 then the kernel will not boot on CPUs that don't support PAE!
1262 The actual amount of total physical memory will either be
1263 auto detected or can be forced by using a kernel command line option
1264 such as "mem=256M". (Try "man bootparam" or see the documentation of
1265 your boot loader (lilo or loadlin) about how to pass options to the
1266 kernel at boot time.)
1268 If unsure, say "off".
1273 Select this if you have a 32-bit processor and between 1 and 4
1274 gigabytes of physical RAM.
1281 Select this if you have a 32-bit processor and more than 4
1282 gigabytes of physical RAM.
1287 prompt "Memory split" if EXPERT
1291 Select the desired split between kernel and user memory.
1293 If the address range available to the kernel is less than the
1294 physical memory installed, the remaining memory will be available
1295 as "high memory". Accessing high memory is a little more costly
1296 than low memory, as it needs to be mapped into the kernel first.
1297 Note that increasing the kernel address space limits the range
1298 available to user programs, making the address space there
1299 tighter. Selecting anything other than the default 3G/1G split
1300 will also likely make your kernel incompatible with binary-only
1303 If you are not absolutely sure what you are doing, leave this
1307 bool "3G/1G user/kernel split"
1308 config VMSPLIT_3G_OPT
1310 bool "3G/1G user/kernel split (for full 1G low memory)"
1312 bool "2G/2G user/kernel split"
1313 config VMSPLIT_2G_OPT
1315 bool "2G/2G user/kernel split (for full 2G low memory)"
1317 bool "1G/3G user/kernel split"
1322 default 0xB0000000 if VMSPLIT_3G_OPT
1323 default 0x80000000 if VMSPLIT_2G
1324 default 0x78000000 if VMSPLIT_2G_OPT
1325 default 0x40000000 if VMSPLIT_1G
1331 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1334 bool "PAE (Physical Address Extension) Support"
1335 depends on X86_32 && !HIGHMEM4G
1338 PAE is required for NX support, and furthermore enables
1339 larger swapspace support for non-overcommit purposes. It
1340 has the cost of more pagetable lookup overhead, and also
1341 consumes more pagetable space per process.
1343 config ARCH_PHYS_ADDR_T_64BIT
1345 depends on X86_64 || X86_PAE
1347 config ARCH_DMA_ADDR_T_64BIT
1349 depends on X86_64 || HIGHMEM64G
1351 config X86_DIRECT_GBPAGES
1353 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1355 Certain kernel features effectively disable kernel
1356 linear 1 GB mappings (even if the CPU otherwise
1357 supports them), so don't confuse the user by printing
1358 that we have them enabled.
1360 # Common NUMA Features
1362 bool "Numa Memory Allocation and Scheduler Support"
1364 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1365 default y if X86_BIGSMP
1367 Enable NUMA (Non Uniform Memory Access) support.
1369 The kernel will try to allocate memory used by a CPU on the
1370 local memory controller of the CPU and add some more
1371 NUMA awareness to the kernel.
1373 For 64-bit this is recommended if the system is Intel Core i7
1374 (or later), AMD Opteron, or EM64T NUMA.
1376 For 32-bit this is only needed if you boot a 32-bit
1377 kernel on a 64-bit NUMA platform.
1379 Otherwise, you should say N.
1383 prompt "Old style AMD Opteron NUMA detection"
1384 depends on X86_64 && NUMA && PCI
1386 Enable AMD NUMA node topology detection. You should say Y here if
1387 you have a multi processor AMD system. This uses an old method to
1388 read the NUMA configuration directly from the builtin Northbridge
1389 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1390 which also takes priority if both are compiled in.
1392 config X86_64_ACPI_NUMA
1394 prompt "ACPI NUMA detection"
1395 depends on X86_64 && NUMA && ACPI && PCI
1398 Enable ACPI SRAT based node topology detection.
1400 # Some NUMA nodes have memory ranges that span
1401 # other nodes. Even though a pfn is valid and
1402 # between a node's start and end pfns, it may not
1403 # reside on that node. See memmap_init_zone()
1405 config NODES_SPAN_OTHER_NODES
1407 depends on X86_64_ACPI_NUMA
1410 bool "NUMA emulation"
1413 Enable NUMA emulation. A flat machine will be split
1414 into virtual nodes when booted with "numa=fake=N", where N is the
1415 number of nodes. This is only useful for debugging.
1418 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1420 default "10" if MAXSMP
1421 default "6" if X86_64
1423 depends on NEED_MULTIPLE_NODES
1425 Specify the maximum number of NUMA Nodes available on the target
1426 system. Increases memory reserved to accommodate various tables.
1428 config ARCH_HAVE_MEMORY_PRESENT
1430 depends on X86_32 && DISCONTIGMEM
1432 config NEED_NODE_MEMMAP_SIZE
1434 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1436 config ARCH_FLATMEM_ENABLE
1438 depends on X86_32 && !NUMA
1440 config ARCH_DISCONTIGMEM_ENABLE
1442 depends on NUMA && X86_32
1444 config ARCH_DISCONTIGMEM_DEFAULT
1446 depends on NUMA && X86_32
1448 config ARCH_SPARSEMEM_ENABLE
1450 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1451 select SPARSEMEM_STATIC if X86_32
1452 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1454 config ARCH_SPARSEMEM_DEFAULT
1458 config ARCH_SELECT_MEMORY_MODEL
1460 depends on ARCH_SPARSEMEM_ENABLE
1462 config ARCH_MEMORY_PROBE
1463 bool "Enable sysfs memory/probe interface"
1464 depends on X86_64 && MEMORY_HOTPLUG
1466 This option enables a sysfs memory/probe interface for testing.
1467 See Documentation/memory-hotplug.txt for more information.
1468 If you are unsure how to answer this question, answer N.
1470 config ARCH_PROC_KCORE_TEXT
1472 depends on X86_64 && PROC_KCORE
1474 config ILLEGAL_POINTER_VALUE
1477 default 0xdead000000000000 if X86_64
1481 config X86_PMEM_LEGACY_DEVICE
1484 config X86_PMEM_LEGACY
1485 tristate "Support non-standard NVDIMMs and ADR protected memory"
1486 depends on PHYS_ADDR_T_64BIT
1488 select X86_PMEM_LEGACY_DEVICE
1491 Treat memory marked using the non-standard e820 type of 12 as used
1492 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1493 The kernel will offer these regions to the 'pmem' driver so
1494 they can be used for persistent storage.
1499 bool "Allocate 3rd-level pagetables from highmem"
1502 The VM uses one page table entry for each page of physical memory.
1503 For systems with a lot of RAM, this can be wasteful of precious
1504 low memory. Setting this option will put user-space page table
1505 entries in high memory.
1507 config X86_CHECK_BIOS_CORRUPTION
1508 bool "Check for low memory corruption"
1510 Periodically check for memory corruption in low memory, which
1511 is suspected to be caused by BIOS. Even when enabled in the
1512 configuration, it is disabled at runtime. Enable it by
1513 setting "memory_corruption_check=1" on the kernel command
1514 line. By default it scans the low 64k of memory every 60
1515 seconds; see the memory_corruption_check_size and
1516 memory_corruption_check_period parameters in
1517 Documentation/kernel-parameters.txt to adjust this.
1519 When enabled with the default parameters, this option has
1520 almost no overhead, as it reserves a relatively small amount
1521 of memory and scans it infrequently. It both detects corruption
1522 and prevents it from affecting the running system.
1524 It is, however, intended as a diagnostic tool; if repeatable
1525 BIOS-originated corruption always affects the same memory,
1526 you can use memmap= to prevent the kernel from using that
1529 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1530 bool "Set the default setting of memory_corruption_check"
1531 depends on X86_CHECK_BIOS_CORRUPTION
1534 Set whether the default state of memory_corruption_check is
1537 config X86_RESERVE_LOW
1538 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1542 Specify the amount of low memory to reserve for the BIOS.
1544 The first page contains BIOS data structures that the kernel
1545 must not use, so that page must always be reserved.
1547 By default we reserve the first 64K of physical RAM, as a
1548 number of BIOSes are known to corrupt that memory range
1549 during events such as suspend/resume or monitor cable
1550 insertion, so it must not be used by the kernel.
1552 You can set this to 4 if you are absolutely sure that you
1553 trust the BIOS to get all its memory reservations and usages
1554 right. If you know your BIOS have problems beyond the
1555 default 64K area, you can set this to 640 to avoid using the
1556 entire low memory range.
1558 If you have doubts about the BIOS (e.g. suspend/resume does
1559 not work or there's kernel crashes after certain hardware
1560 hotplug events) then you might want to enable
1561 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1562 typical corruption patterns.
1564 Leave this to the default value of 64 if you are unsure.
1566 config MATH_EMULATION
1568 depends on MODIFY_LDT_SYSCALL
1569 prompt "Math emulation" if X86_32
1571 Linux can emulate a math coprocessor (used for floating point
1572 operations) if you don't have one. 486DX and Pentium processors have
1573 a math coprocessor built in, 486SX and 386 do not, unless you added
1574 a 487DX or 387, respectively. (The messages during boot time can
1575 give you some hints here ["man dmesg"].) Everyone needs either a
1576 coprocessor or this emulation.
1578 If you don't have a math coprocessor, you need to say Y here; if you
1579 say Y here even though you have a coprocessor, the coprocessor will
1580 be used nevertheless. (This behavior can be changed with the kernel
1581 command line option "no387", which comes handy if your coprocessor
1582 is broken. Try "man bootparam" or see the documentation of your boot
1583 loader (lilo or loadlin) about how to pass options to the kernel at
1584 boot time.) This means that it is a good idea to say Y here if you
1585 intend to use this kernel on different machines.
1587 More information about the internals of the Linux math coprocessor
1588 emulation can be found in <file:arch/x86/math-emu/README>.
1590 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1591 kernel, it won't hurt.
1595 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1597 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1598 the Memory Type Range Registers (MTRRs) may be used to control
1599 processor access to memory ranges. This is most useful if you have
1600 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1601 allows bus write transfers to be combined into a larger transfer
1602 before bursting over the PCI/AGP bus. This can increase performance
1603 of image write operations 2.5 times or more. Saying Y here creates a
1604 /proc/mtrr file which may be used to manipulate your processor's
1605 MTRRs. Typically the X server should use this.
1607 This code has a reasonably generic interface so that similar
1608 control registers on other processors can be easily supported
1611 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1612 Registers (ARRs) which provide a similar functionality to MTRRs. For
1613 these, the ARRs are used to emulate the MTRRs.
1614 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1615 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1616 write-combining. All of these processors are supported by this code
1617 and it makes sense to say Y here if you have one of them.
1619 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1620 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1621 can lead to all sorts of problems, so it's good to say Y here.
1623 You can safely say Y even if your machine doesn't have MTRRs, you'll
1624 just add about 9 KB to your kernel.
1626 See <file:Documentation/x86/mtrr.txt> for more information.
1628 config MTRR_SANITIZER
1630 prompt "MTRR cleanup support"
1633 Convert MTRR layout from continuous to discrete, so X drivers can
1634 add writeback entries.
1636 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1637 The largest mtrr entry size for a continuous block can be set with
1642 config MTRR_SANITIZER_ENABLE_DEFAULT
1643 int "MTRR cleanup enable value (0-1)"
1646 depends on MTRR_SANITIZER
1648 Enable mtrr cleanup default value
1650 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1651 int "MTRR cleanup spare reg num (0-7)"
1654 depends on MTRR_SANITIZER
1656 mtrr cleanup spare entries default, it can be changed via
1657 mtrr_spare_reg_nr=N on the kernel command line.
1661 prompt "x86 PAT support" if EXPERT
1664 Use PAT attributes to setup page level cache control.
1666 PATs are the modern equivalents of MTRRs and are much more
1667 flexible than MTRRs.
1669 Say N here if you see bootup problems (boot crash, boot hang,
1670 spontaneous reboots) or a non-working video driver.
1674 config ARCH_USES_PG_UNCACHED
1680 prompt "x86 architectural random number generator" if EXPERT
1682 Enable the x86 architectural RDRAND instruction
1683 (Intel Bull Mountain technology) to generate random numbers.
1684 If supported, this is a high bandwidth, cryptographically
1685 secure hardware random number generator.
1689 prompt "Supervisor Mode Access Prevention" if EXPERT
1691 Supervisor Mode Access Prevention (SMAP) is a security
1692 feature in newer Intel processors. There is a small
1693 performance cost if this enabled and turned on; there is
1694 also a small increase in the kernel size if this is enabled.
1698 config X86_INTEL_MPX
1699 prompt "Intel MPX (Memory Protection Extensions)"
1701 depends on CPU_SUP_INTEL
1703 MPX provides hardware features that can be used in
1704 conjunction with compiler-instrumented code to check
1705 memory references. It is designed to detect buffer
1706 overflow or underflow bugs.
1708 This option enables running applications which are
1709 instrumented or otherwise use MPX. It does not use MPX
1710 itself inside the kernel or to protect the kernel
1711 against bad memory references.
1713 Enabling this option will make the kernel larger:
1714 ~8k of kernel text and 36 bytes of data on a 64-bit
1715 defconfig. It adds a long to the 'mm_struct' which
1716 will increase the kernel memory overhead of each
1717 process and adds some branches to paths used during
1718 exec() and munmap().
1720 For details, see Documentation/x86/intel_mpx.txt
1724 config X86_INTEL_MEMORY_PROTECTION_KEYS
1725 prompt "Intel Memory Protection Keys"
1727 # Note: only available in 64-bit mode
1728 depends on CPU_SUP_INTEL && X86_64
1730 Memory Protection Keys provides a mechanism for enforcing
1731 page-based protections, but without requiring modification of the
1732 page tables when an application changes protection domains.
1734 For details, see Documentation/x86/protection-keys.txt
1739 bool "EFI runtime service support"
1742 select EFI_RUNTIME_WRAPPERS
1744 This enables the kernel to use EFI runtime services that are
1745 available (such as the EFI variable services).
1747 This option is only useful on systems that have EFI firmware.
1748 In addition, you should use the latest ELILO loader available
1749 at <http://elilo.sourceforge.net> in order to take advantage
1750 of EFI runtime services. However, even with this option, the
1751 resultant kernel should continue to boot on existing non-EFI
1755 bool "EFI stub support"
1756 depends on EFI && !X86_USE_3DNOW
1759 This kernel feature allows a bzImage to be loaded directly
1760 by EFI firmware without the use of a bootloader.
1762 See Documentation/efi-stub.txt for more information.
1765 bool "EFI mixed-mode support"
1766 depends on EFI_STUB && X86_64
1768 Enabling this feature allows a 64-bit kernel to be booted
1769 on a 32-bit firmware, provided that your CPU supports 64-bit
1772 Note that it is not possible to boot a mixed-mode enabled
1773 kernel via the EFI boot stub - a bootloader that supports
1774 the EFI handover protocol must be used.
1780 prompt "Enable seccomp to safely compute untrusted bytecode"
1782 This kernel feature is useful for number crunching applications
1783 that may need to compute untrusted bytecode during their
1784 execution. By using pipes or other transports made available to
1785 the process as file descriptors supporting the read/write
1786 syscalls, it's possible to isolate those applications in
1787 their own address space using seccomp. Once seccomp is
1788 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1789 and the task is only allowed to execute a few safe syscalls
1790 defined by each seccomp mode.
1792 If unsure, say Y. Only embedded should say N here.
1794 source kernel/Kconfig.hz
1797 bool "kexec system call"
1800 kexec is a system call that implements the ability to shutdown your
1801 current kernel, and to start another kernel. It is like a reboot
1802 but it is independent of the system firmware. And like a reboot
1803 you can start any kernel with it, not just Linux.
1805 The name comes from the similarity to the exec system call.
1807 It is an ongoing process to be certain the hardware in a machine
1808 is properly shutdown, so do not be surprised if this code does not
1809 initially work for you. As of this writing the exact hardware
1810 interface is strongly in flux, so no good recommendation can be
1814 bool "kexec file based system call"
1819 depends on CRYPTO_SHA256=y
1821 This is new version of kexec system call. This system call is
1822 file based and takes file descriptors as system call argument
1823 for kernel and initramfs as opposed to list of segments as
1824 accepted by previous system call.
1826 config KEXEC_VERIFY_SIG
1827 bool "Verify kernel signature during kexec_file_load() syscall"
1828 depends on KEXEC_FILE
1830 This option makes kernel signature verification mandatory for
1831 the kexec_file_load() syscall.
1833 In addition to that option, you need to enable signature
1834 verification for the corresponding kernel image type being
1835 loaded in order for this to work.
1837 config KEXEC_BZIMAGE_VERIFY_SIG
1838 bool "Enable bzImage signature verification support"
1839 depends on KEXEC_VERIFY_SIG
1840 depends on SIGNED_PE_FILE_VERIFICATION
1841 select SYSTEM_TRUSTED_KEYRING
1843 Enable bzImage signature verification support.
1846 bool "kernel crash dumps"
1847 depends on X86_64 || (X86_32 && HIGHMEM)
1849 Generate crash dump after being started by kexec.
1850 This should be normally only set in special crash dump kernels
1851 which are loaded in the main kernel with kexec-tools into
1852 a specially reserved region and then later executed after
1853 a crash by kdump/kexec. The crash dump kernel must be compiled
1854 to a memory address not used by the main kernel or BIOS using
1855 PHYSICAL_START, or it must be built as a relocatable image
1856 (CONFIG_RELOCATABLE=y).
1857 For more details see Documentation/kdump/kdump.txt
1861 depends on KEXEC && HIBERNATION
1863 Jump between original kernel and kexeced kernel and invoke
1864 code in physical address mode via KEXEC
1866 config PHYSICAL_START
1867 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1870 This gives the physical address where the kernel is loaded.
1872 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1873 bzImage will decompress itself to above physical address and
1874 run from there. Otherwise, bzImage will run from the address where
1875 it has been loaded by the boot loader and will ignore above physical
1878 In normal kdump cases one does not have to set/change this option
1879 as now bzImage can be compiled as a completely relocatable image
1880 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1881 address. This option is mainly useful for the folks who don't want
1882 to use a bzImage for capturing the crash dump and want to use a
1883 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1884 to be specifically compiled to run from a specific memory area
1885 (normally a reserved region) and this option comes handy.
1887 So if you are using bzImage for capturing the crash dump,
1888 leave the value here unchanged to 0x1000000 and set
1889 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1890 for capturing the crash dump change this value to start of
1891 the reserved region. In other words, it can be set based on
1892 the "X" value as specified in the "crashkernel=YM@XM"
1893 command line boot parameter passed to the panic-ed
1894 kernel. Please take a look at Documentation/kdump/kdump.txt
1895 for more details about crash dumps.
1897 Usage of bzImage for capturing the crash dump is recommended as
1898 one does not have to build two kernels. Same kernel can be used
1899 as production kernel and capture kernel. Above option should have
1900 gone away after relocatable bzImage support is introduced. But it
1901 is present because there are users out there who continue to use
1902 vmlinux for dump capture. This option should go away down the
1905 Don't change this unless you know what you are doing.
1908 bool "Build a relocatable kernel"
1911 This builds a kernel image that retains relocation information
1912 so it can be loaded someplace besides the default 1MB.
1913 The relocations tend to make the kernel binary about 10% larger,
1914 but are discarded at runtime.
1916 One use is for the kexec on panic case where the recovery kernel
1917 must live at a different physical address than the primary
1920 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1921 it has been loaded at and the compile time physical address
1922 (CONFIG_PHYSICAL_START) is used as the minimum location.
1924 config RANDOMIZE_BASE
1925 bool "Randomize the address of the kernel image (KASLR)"
1926 depends on RELOCATABLE
1929 In support of Kernel Address Space Layout Randomization (KASLR),
1930 this randomizes the physical address at which the kernel image
1931 is decompressed and the virtual address where the kernel
1932 image is mapped, as a security feature that deters exploit
1933 attempts relying on knowledge of the location of kernel
1936 On 64-bit, the kernel physical and virtual addresses are
1937 randomized separately. The physical address will be anywhere
1938 between 16MB and the top of physical memory (up to 64TB). The
1939 virtual address will be randomized from 16MB up to 1GB (9 bits
1940 of entropy). Note that this also reduces the memory space
1941 available to kernel modules from 1.5GB to 1GB.
1943 On 32-bit, the kernel physical and virtual addresses are
1944 randomized together. They will be randomized from 16MB up to
1945 512MB (8 bits of entropy).
1947 Entropy is generated using the RDRAND instruction if it is
1948 supported. If RDTSC is supported, its value is mixed into
1949 the entropy pool as well. If neither RDRAND nor RDTSC are
1950 supported, then entropy is read from the i8254 timer. The
1951 usable entropy is limited by the kernel being built using
1952 2GB addressing, and that PHYSICAL_ALIGN must be at a
1953 minimum of 2MB. As a result, only 10 bits of entropy are
1954 theoretically possible, but the implementations are further
1955 limited due to memory layouts.
1957 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1958 time. To enable it, boot with "kaslr" on the kernel command
1959 line (which will also disable hibernation).
1963 # Relocation on x86 needs some additional build support
1964 config X86_NEED_RELOCS
1966 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1968 config PHYSICAL_ALIGN
1969 hex "Alignment value to which kernel should be aligned"
1971 range 0x2000 0x1000000 if X86_32
1972 range 0x200000 0x1000000 if X86_64
1974 This value puts the alignment restrictions on physical address
1975 where kernel is loaded and run from. Kernel is compiled for an
1976 address which meets above alignment restriction.
1978 If bootloader loads the kernel at a non-aligned address and
1979 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1980 address aligned to above value and run from there.
1982 If bootloader loads the kernel at a non-aligned address and
1983 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1984 load address and decompress itself to the address it has been
1985 compiled for and run from there. The address for which kernel is
1986 compiled already meets above alignment restrictions. Hence the
1987 end result is that kernel runs from a physical address meeting
1988 above alignment restrictions.
1990 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1991 this value must be a multiple of 0x200000.
1993 Don't change this unless you know what you are doing.
1995 config RANDOMIZE_MEMORY
1996 bool "Randomize the kernel memory sections"
1998 depends on RANDOMIZE_BASE
1999 default RANDOMIZE_BASE
2001 Randomizes the base virtual address of kernel memory sections
2002 (physical memory mapping, vmalloc & vmemmap). This security feature
2003 makes exploits relying on predictable memory locations less reliable.
2005 The order of allocations remains unchanged. Entropy is generated in
2006 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2007 configuration have in average 30,000 different possible virtual
2008 addresses for each memory section.
2012 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2013 hex "Physical memory mapping padding" if EXPERT
2014 depends on RANDOMIZE_MEMORY
2015 default "0xa" if MEMORY_HOTPLUG
2017 range 0x1 0x40 if MEMORY_HOTPLUG
2020 Define the padding in terabytes added to the existing physical
2021 memory size during kernel memory randomization. It is useful
2022 for memory hotplug support but reduces the entropy available for
2023 address randomization.
2025 If unsure, leave at the default value.
2028 bool "Support for hot-pluggable CPUs"
2031 Say Y here to allow turning CPUs off and on. CPUs can be
2032 controlled through /sys/devices/system/cpu.
2033 ( Note: power management support will enable this option
2034 automatically on SMP systems. )
2035 Say N if you want to disable CPU hotplug.
2037 config BOOTPARAM_HOTPLUG_CPU0
2038 bool "Set default setting of cpu0_hotpluggable"
2040 depends on HOTPLUG_CPU
2042 Set whether default state of cpu0_hotpluggable is on or off.
2044 Say Y here to enable CPU0 hotplug by default. If this switch
2045 is turned on, there is no need to give cpu0_hotplug kernel
2046 parameter and the CPU0 hotplug feature is enabled by default.
2048 Please note: there are two known CPU0 dependencies if you want
2049 to enable the CPU0 hotplug feature either by this switch or by
2050 cpu0_hotplug kernel parameter.
2052 First, resume from hibernate or suspend always starts from CPU0.
2053 So hibernate and suspend are prevented if CPU0 is offline.
2055 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2056 offline if any interrupt can not migrate out of CPU0. There may
2057 be other CPU0 dependencies.
2059 Please make sure the dependencies are under your control before
2060 you enable this feature.
2062 Say N if you don't want to enable CPU0 hotplug feature by default.
2063 You still can enable the CPU0 hotplug feature at boot by kernel
2064 parameter cpu0_hotplug.
2066 config DEBUG_HOTPLUG_CPU0
2068 prompt "Debug CPU0 hotplug"
2069 depends on HOTPLUG_CPU
2071 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2072 soon as possible and boots up userspace with CPU0 offlined. User
2073 can online CPU0 back after boot time.
2075 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2076 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2077 compilation or giving cpu0_hotplug kernel parameter at boot.
2083 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2084 depends on X86_32 || IA32_EMULATION
2086 Certain buggy versions of glibc will crash if they are
2087 presented with a 32-bit vDSO that is not mapped at the address
2088 indicated in its segment table.
2090 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2091 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2092 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2093 the only released version with the bug, but OpenSUSE 9
2094 contains a buggy "glibc 2.3.2".
2096 The symptom of the bug is that everything crashes on startup, saying:
2097 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2099 Saying Y here changes the default value of the vdso32 boot
2100 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2101 This works around the glibc bug but hurts performance.
2103 If unsure, say N: if you are compiling your own kernel, you
2104 are unlikely to be using a buggy version of glibc.
2107 prompt "vsyscall table for legacy applications"
2109 default LEGACY_VSYSCALL_EMULATE
2111 Legacy user code that does not know how to find the vDSO expects
2112 to be able to issue three syscalls by calling fixed addresses in
2113 kernel space. Since this location is not randomized with ASLR,
2114 it can be used to assist security vulnerability exploitation.
2116 This setting can be changed at boot time via the kernel command
2117 line parameter vsyscall=[native|emulate|none].
2119 On a system with recent enough glibc (2.14 or newer) and no
2120 static binaries, you can say None without a performance penalty
2121 to improve security.
2123 If unsure, select "Emulate".
2125 config LEGACY_VSYSCALL_NATIVE
2128 Actual executable code is located in the fixed vsyscall
2129 address mapping, implementing time() efficiently. Since
2130 this makes the mapping executable, it can be used during
2131 security vulnerability exploitation (traditionally as
2132 ROP gadgets). This configuration is not recommended.
2134 config LEGACY_VSYSCALL_EMULATE
2137 The kernel traps and emulates calls into the fixed
2138 vsyscall address mapping. This makes the mapping
2139 non-executable, but it still contains known contents,
2140 which could be used in certain rare security vulnerability
2141 exploits. This configuration is recommended when userspace
2142 still uses the vsyscall area.
2144 config LEGACY_VSYSCALL_NONE
2147 There will be no vsyscall mapping at all. This will
2148 eliminate any risk of ASLR bypass due to the vsyscall
2149 fixed address mapping. Attempts to use the vsyscalls
2150 will be reported to dmesg, so that either old or
2151 malicious userspace programs can be identified.
2156 bool "Built-in kernel command line"
2158 Allow for specifying boot arguments to the kernel at
2159 build time. On some systems (e.g. embedded ones), it is
2160 necessary or convenient to provide some or all of the
2161 kernel boot arguments with the kernel itself (that is,
2162 to not rely on the boot loader to provide them.)
2164 To compile command line arguments into the kernel,
2165 set this option to 'Y', then fill in the
2166 boot arguments in CONFIG_CMDLINE.
2168 Systems with fully functional boot loaders (i.e. non-embedded)
2169 should leave this option set to 'N'.
2172 string "Built-in kernel command string"
2173 depends on CMDLINE_BOOL
2176 Enter arguments here that should be compiled into the kernel
2177 image and used at boot time. If the boot loader provides a
2178 command line at boot time, it is appended to this string to
2179 form the full kernel command line, when the system boots.
2181 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2182 change this behavior.
2184 In most cases, the command line (whether built-in or provided
2185 by the boot loader) should specify the device for the root
2188 config CMDLINE_OVERRIDE
2189 bool "Built-in command line overrides boot loader arguments"
2190 depends on CMDLINE_BOOL
2192 Set this option to 'Y' to have the kernel ignore the boot loader
2193 command line, and use ONLY the built-in command line.
2195 This is used to work around broken boot loaders. This should
2196 be set to 'N' under normal conditions.
2198 config MODIFY_LDT_SYSCALL
2199 bool "Enable the LDT (local descriptor table)" if EXPERT
2202 Linux can allow user programs to install a per-process x86
2203 Local Descriptor Table (LDT) using the modify_ldt(2) system
2204 call. This is required to run 16-bit or segmented code such as
2205 DOSEMU or some Wine programs. It is also used by some very old
2206 threading libraries.
2208 Enabling this feature adds a small amount of overhead to
2209 context switches and increases the low-level kernel attack
2210 surface. Disabling it removes the modify_ldt(2) system call.
2212 Saying 'N' here may make sense for embedded or server kernels.
2214 source "kernel/livepatch/Kconfig"
2218 config ARCH_ENABLE_MEMORY_HOTPLUG
2220 depends on X86_64 || (X86_32 && HIGHMEM)
2222 config ARCH_ENABLE_MEMORY_HOTREMOVE
2224 depends on MEMORY_HOTPLUG
2226 config USE_PERCPU_NUMA_NODE_ID
2230 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2232 depends on X86_64 || X86_PAE
2234 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2236 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2238 menu "Power management and ACPI options"
2240 config ARCH_HIBERNATION_HEADER
2242 depends on X86_64 && HIBERNATION
2244 source "kernel/power/Kconfig"
2246 source "drivers/acpi/Kconfig"
2248 source "drivers/sfi/Kconfig"
2255 tristate "APM (Advanced Power Management) BIOS support"
2256 depends on X86_32 && PM_SLEEP
2258 APM is a BIOS specification for saving power using several different
2259 techniques. This is mostly useful for battery powered laptops with
2260 APM compliant BIOSes. If you say Y here, the system time will be
2261 reset after a RESUME operation, the /proc/apm device will provide
2262 battery status information, and user-space programs will receive
2263 notification of APM "events" (e.g. battery status change).
2265 If you select "Y" here, you can disable actual use of the APM
2266 BIOS by passing the "apm=off" option to the kernel at boot time.
2268 Note that the APM support is almost completely disabled for
2269 machines with more than one CPU.
2271 In order to use APM, you will need supporting software. For location
2272 and more information, read <file:Documentation/power/apm-acpi.txt>
2273 and the Battery Powered Linux mini-HOWTO, available from
2274 <http://www.tldp.org/docs.html#howto>.
2276 This driver does not spin down disk drives (see the hdparm(8)
2277 manpage ("man 8 hdparm") for that), and it doesn't turn off
2278 VESA-compliant "green" monitors.
2280 This driver does not support the TI 4000M TravelMate and the ACER
2281 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2282 desktop machines also don't have compliant BIOSes, and this driver
2283 may cause those machines to panic during the boot phase.
2285 Generally, if you don't have a battery in your machine, there isn't
2286 much point in using this driver and you should say N. If you get
2287 random kernel OOPSes or reboots that don't seem to be related to
2288 anything, try disabling/enabling this option (or disabling/enabling
2291 Some other things you should try when experiencing seemingly random,
2294 1) make sure that you have enough swap space and that it is
2296 2) pass the "no-hlt" option to the kernel
2297 3) switch on floating point emulation in the kernel and pass
2298 the "no387" option to the kernel
2299 4) pass the "floppy=nodma" option to the kernel
2300 5) pass the "mem=4M" option to the kernel (thereby disabling
2301 all but the first 4 MB of RAM)
2302 6) make sure that the CPU is not over clocked.
2303 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2304 8) disable the cache from your BIOS settings
2305 9) install a fan for the video card or exchange video RAM
2306 10) install a better fan for the CPU
2307 11) exchange RAM chips
2308 12) exchange the motherboard.
2310 To compile this driver as a module, choose M here: the
2311 module will be called apm.
2315 config APM_IGNORE_USER_SUSPEND
2316 bool "Ignore USER SUSPEND"
2318 This option will ignore USER SUSPEND requests. On machines with a
2319 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2320 series notebooks, it is necessary to say Y because of a BIOS bug.
2322 config APM_DO_ENABLE
2323 bool "Enable PM at boot time"
2325 Enable APM features at boot time. From page 36 of the APM BIOS
2326 specification: "When disabled, the APM BIOS does not automatically
2327 power manage devices, enter the Standby State, enter the Suspend
2328 State, or take power saving steps in response to CPU Idle calls."
2329 This driver will make CPU Idle calls when Linux is idle (unless this
2330 feature is turned off -- see "Do CPU IDLE calls", below). This
2331 should always save battery power, but more complicated APM features
2332 will be dependent on your BIOS implementation. You may need to turn
2333 this option off if your computer hangs at boot time when using APM
2334 support, or if it beeps continuously instead of suspending. Turn
2335 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2336 T400CDT. This is off by default since most machines do fine without
2341 bool "Make CPU Idle calls when idle"
2343 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2344 On some machines, this can activate improved power savings, such as
2345 a slowed CPU clock rate, when the machine is idle. These idle calls
2346 are made after the idle loop has run for some length of time (e.g.,
2347 333 mS). On some machines, this will cause a hang at boot time or
2348 whenever the CPU becomes idle. (On machines with more than one CPU,
2349 this option does nothing.)
2351 config APM_DISPLAY_BLANK
2352 bool "Enable console blanking using APM"
2354 Enable console blanking using the APM. Some laptops can use this to
2355 turn off the LCD backlight when the screen blanker of the Linux
2356 virtual console blanks the screen. Note that this is only used by
2357 the virtual console screen blanker, and won't turn off the backlight
2358 when using the X Window system. This also doesn't have anything to
2359 do with your VESA-compliant power-saving monitor. Further, this
2360 option doesn't work for all laptops -- it might not turn off your
2361 backlight at all, or it might print a lot of errors to the console,
2362 especially if you are using gpm.
2364 config APM_ALLOW_INTS
2365 bool "Allow interrupts during APM BIOS calls"
2367 Normally we disable external interrupts while we are making calls to
2368 the APM BIOS as a measure to lessen the effects of a badly behaving
2369 BIOS implementation. The BIOS should reenable interrupts if it
2370 needs to. Unfortunately, some BIOSes do not -- especially those in
2371 many of the newer IBM Thinkpads. If you experience hangs when you
2372 suspend, try setting this to Y. Otherwise, say N.
2376 source "drivers/cpufreq/Kconfig"
2378 source "drivers/cpuidle/Kconfig"
2380 source "drivers/idle/Kconfig"
2385 menu "Bus options (PCI etc.)"
2391 Find out whether you have a PCI motherboard. PCI is the name of a
2392 bus system, i.e. the way the CPU talks to the other stuff inside
2393 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2394 VESA. If you have PCI, say Y, otherwise N.
2397 prompt "PCI access mode"
2398 depends on X86_32 && PCI
2401 On PCI systems, the BIOS can be used to detect the PCI devices and
2402 determine their configuration. However, some old PCI motherboards
2403 have BIOS bugs and may crash if this is done. Also, some embedded
2404 PCI-based systems don't have any BIOS at all. Linux can also try to
2405 detect the PCI hardware directly without using the BIOS.
2407 With this option, you can specify how Linux should detect the
2408 PCI devices. If you choose "BIOS", the BIOS will be used,
2409 if you choose "Direct", the BIOS won't be used, and if you
2410 choose "MMConfig", then PCI Express MMCONFIG will be used.
2411 If you choose "Any", the kernel will try MMCONFIG, then the
2412 direct access method and falls back to the BIOS if that doesn't
2413 work. If unsure, go with the default, which is "Any".
2418 config PCI_GOMMCONFIG
2435 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2437 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2440 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2444 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2448 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2452 depends on PCI && XEN
2460 bool "Support mmconfig PCI config space access"
2461 depends on X86_64 && PCI && ACPI
2463 config PCI_CNB20LE_QUIRK
2464 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2467 Read the PCI windows out of the CNB20LE host bridge. This allows
2468 PCI hotplug to work on systems with the CNB20LE chipset which do
2471 There's no public spec for this chipset, and this functionality
2472 is known to be incomplete.
2474 You should say N unless you know you need this.
2476 source "drivers/pci/Kconfig"
2479 bool "ISA-style bus support on modern systems" if EXPERT
2482 Enables ISA-style drivers on modern systems. This is necessary to
2483 support PC/104 devices on X86_64 platforms.
2487 # x86_64 have no ISA slots, but can have ISA-style DMA.
2489 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2492 Enables ISA-style DMA support for devices requiring such controllers.
2500 Find out whether you have ISA slots on your motherboard. ISA is the
2501 name of a bus system, i.e. the way the CPU talks to the other stuff
2502 inside your box. Other bus systems are PCI, EISA, MicroChannel
2503 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2504 newer boards don't support it. If you have ISA, say Y, otherwise N.
2510 The Extended Industry Standard Architecture (EISA) bus was
2511 developed as an open alternative to the IBM MicroChannel bus.
2513 The EISA bus provided some of the features of the IBM MicroChannel
2514 bus while maintaining backward compatibility with cards made for
2515 the older ISA bus. The EISA bus saw limited use between 1988 and
2516 1995 when it was made obsolete by the PCI bus.
2518 Say Y here if you are building a kernel for an EISA-based machine.
2522 source "drivers/eisa/Kconfig"
2525 tristate "NatSemi SCx200 support"
2527 This provides basic support for National Semiconductor's
2528 (now AMD's) Geode processors. The driver probes for the
2529 PCI-IDs of several on-chip devices, so its a good dependency
2530 for other scx200_* drivers.
2532 If compiled as a module, the driver is named scx200.
2534 config SCx200HR_TIMER
2535 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2539 This driver provides a clocksource built upon the on-chip
2540 27MHz high-resolution timer. Its also a workaround for
2541 NSC Geode SC-1100's buggy TSC, which loses time when the
2542 processor goes idle (as is done by the scheduler). The
2543 other workaround is idle=poll boot option.
2546 bool "One Laptop Per Child support"
2553 Add support for detecting the unique features of the OLPC
2557 bool "OLPC XO-1 Power Management"
2558 depends on OLPC && MFD_CS5535 && PM_SLEEP
2561 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2564 bool "OLPC XO-1 Real Time Clock"
2565 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2567 Add support for the XO-1 real time clock, which can be used as a
2568 programmable wakeup source.
2571 bool "OLPC XO-1 SCI extras"
2572 depends on OLPC && OLPC_XO1_PM
2578 Add support for SCI-based features of the OLPC XO-1 laptop:
2579 - EC-driven system wakeups
2583 - AC adapter status updates
2584 - Battery status updates
2586 config OLPC_XO15_SCI
2587 bool "OLPC XO-1.5 SCI extras"
2588 depends on OLPC && ACPI
2591 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2592 - EC-driven system wakeups
2593 - AC adapter status updates
2594 - Battery status updates
2597 bool "PCEngines ALIX System Support (LED setup)"
2600 This option enables system support for the PCEngines ALIX.
2601 At present this just sets up LEDs for GPIO control on
2602 ALIX2/3/6 boards. However, other system specific setup should
2605 Note: You must still enable the drivers for GPIO and LED support
2606 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2608 Note: You have to set alix.force=1 for boards with Award BIOS.
2611 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2614 This option enables system support for the Soekris Engineering net5501.
2617 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2621 This option enables system support for the Traverse Technologies GEOS.
2624 bool "Technologic Systems TS-5500 platform support"
2626 select CHECK_SIGNATURE
2630 This option enables system support for the Technologic Systems TS-5500.
2636 depends on CPU_SUP_AMD && PCI
2638 source "drivers/pcmcia/Kconfig"
2641 tristate "RapidIO support"
2645 If enabled this option will include drivers and the core
2646 infrastructure code to support RapidIO interconnect devices.
2648 source "drivers/rapidio/Kconfig"
2651 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2653 Firmwares often provide initial graphics framebuffers so the BIOS,
2654 bootloader or kernel can show basic video-output during boot for
2655 user-guidance and debugging. Historically, x86 used the VESA BIOS
2656 Extensions and EFI-framebuffers for this, which are mostly limited
2658 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2659 framebuffers so the new generic system-framebuffer drivers can be
2660 used on x86. If the framebuffer is not compatible with the generic
2661 modes, it is adverticed as fallback platform framebuffer so legacy
2662 drivers like efifb, vesafb and uvesafb can pick it up.
2663 If this option is not selected, all system framebuffers are always
2664 marked as fallback platform framebuffers as usual.
2666 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2667 not be able to pick up generic system framebuffers if this option
2668 is selected. You are highly encouraged to enable simplefb as
2669 replacement if you select this option. simplefb can correctly deal
2670 with generic system framebuffers. But you should still keep vesafb
2671 and others enabled as fallback if a system framebuffer is
2672 incompatible with simplefb.
2679 menu "Executable file formats / Emulations"
2681 source "fs/Kconfig.binfmt"
2683 config IA32_EMULATION
2684 bool "IA32 Emulation"
2687 select COMPAT_BINFMT_ELF
2688 select ARCH_WANT_OLD_COMPAT_IPC
2690 Include code to run legacy 32-bit programs under a
2691 64-bit kernel. You should likely turn this on, unless you're
2692 100% sure that you don't have any 32-bit programs left.
2695 tristate "IA32 a.out support"
2696 depends on IA32_EMULATION
2698 Support old a.out binaries in the 32bit emulation.
2701 bool "x32 ABI for 64-bit mode"
2704 Include code to run binaries for the x32 native 32-bit ABI
2705 for 64-bit processors. An x32 process gets access to the
2706 full 64-bit register file and wide data path while leaving
2707 pointers at 32 bits for smaller memory footprint.
2709 You will need a recent binutils (2.22 or later) with
2710 elf32_x86_64 support enabled to compile a kernel with this
2715 depends on IA32_EMULATION || X86_X32
2718 config COMPAT_FOR_U64_ALIGNMENT
2721 config SYSVIPC_COMPAT
2733 config HAVE_ATOMIC_IOMAP
2737 config X86_DEV_DMA_OPS
2739 depends on X86_64 || STA2X11
2741 config X86_DMA_REMAP
2751 tristate "Volume Management Device Driver"
2754 Adds support for the Intel Volume Management Device (VMD). VMD is a
2755 secondary PCI host bridge that allows PCI Express root ports,
2756 and devices attached to them, to be removed from the default
2757 PCI domain and placed within the VMD domain. This provides
2758 more bus resources than are otherwise possible with a
2759 single domain. If you know your system provides one of these and
2760 has devices attached to it, say Y; if you are not sure, say N.
2762 source "net/Kconfig"
2764 source "drivers/Kconfig"
2766 source "drivers/firmware/Kconfig"
2770 source "arch/x86/Kconfig.debug"
2772 source "security/Kconfig"
2774 source "crypto/Kconfig"
2776 source "arch/x86/kvm/Kconfig"
2778 source "lib/Kconfig"
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