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_ATOMIC64_DEC_IF_POSITIVE
26 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
27 select ARCH_HAS_ELF_RANDOMIZE
28 select ARCH_HAS_FAST_MULTIPLIER
29 select ARCH_HAS_GCOV_PROFILE_ALL
30 select ARCH_HAS_KCOV if X86_64
31 select ARCH_HAS_PMEM_API if X86_64
32 select ARCH_HAS_MMIO_FLUSH
33 select ARCH_HAS_SG_CHAIN
34 select ARCH_HAVE_NMI_SAFE_CMPXCHG
35 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
36 select ARCH_HAS_UBSAN_SANITIZE_ALL
37 select ARCH_MIGHT_HAVE_PC_PARPORT
38 select ARCH_MIGHT_HAVE_PC_SERIO
39 select ARCH_SUPPORTS_ATOMIC_RMW
40 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
41 select ARCH_SUPPORTS_INT128 if X86_64
42 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
43 select ARCH_USE_BUILTIN_BSWAP
44 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
45 select ARCH_USE_QUEUED_RWLOCKS
46 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
47 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
48 select ARCH_WANT_FRAME_POINTERS
49 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
50 select HAVE_ARCH_MMAP_RND_BITS if MMU
51 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
52 select ARCH_WANT_OPTIONAL_GPIOLIB
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_CPU_VULNERABILITIES
69 select GENERIC_EARLY_IOREMAP
70 select GENERIC_FIND_FIRST_BIT
72 select GENERIC_IRQ_PROBE
73 select GENERIC_IRQ_SHOW
74 select GENERIC_PENDING_IRQ if SMP
75 select GENERIC_SMP_IDLE_THREAD
76 select GENERIC_STRNCPY_FROM_USER
77 select GENERIC_STRNLEN_USER
78 select GENERIC_TIME_VSYSCALL
79 select HAVE_ACPI_APEI if ACPI
80 select HAVE_ACPI_APEI_NMI if ACPI
81 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
82 select HAVE_AOUT if X86_32
83 select HAVE_ARCH_AUDITSYSCALL
84 select HAVE_ARCH_HARDENED_USERCOPY
85 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
86 select HAVE_ARCH_JUMP_LABEL
87 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
89 select HAVE_ARCH_KMEMCHECK
90 select HAVE_ARCH_SECCOMP_FILTER
91 select HAVE_ARCH_SOFT_DIRTY if X86_64
92 select HAVE_ARCH_TRACEHOOK
93 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
94 select HAVE_ARCH_WITHIN_STACK_FRAMES
95 select HAVE_EBPF_JIT if X86_64
96 select HAVE_CC_STACKPROTECTOR
97 select HAVE_CMPXCHG_DOUBLE
98 select HAVE_CMPXCHG_LOCAL
99 select HAVE_CONTEXT_TRACKING if X86_64
100 select HAVE_COPY_THREAD_TLS
101 select HAVE_C_RECORDMCOUNT
102 select HAVE_DEBUG_KMEMLEAK
103 select HAVE_DEBUG_STACKOVERFLOW
104 select HAVE_DMA_API_DEBUG
105 select HAVE_DMA_ATTRS
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_GENERIC_DMA_COHERENT if X86_32
117 select HAVE_HW_BREAKPOINT
119 select HAVE_IOREMAP_PROT
120 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
121 select HAVE_IRQ_TIME_ACCOUNTING
122 select HAVE_KERNEL_BZIP2
123 select HAVE_KERNEL_GZIP
124 select HAVE_KERNEL_LZ4
125 select HAVE_KERNEL_LZMA
126 select HAVE_KERNEL_LZO
127 select HAVE_KERNEL_XZ
129 select HAVE_KPROBES_ON_FTRACE
130 select HAVE_KRETPROBES
132 select HAVE_LIVEPATCH if X86_64
134 select HAVE_MEMBLOCK_NODE_MAP
135 select HAVE_MIXED_BREAKPOINTS_REGS
137 select HAVE_OPTPROBES
138 select HAVE_PCSPKR_PLATFORM
139 select HAVE_PERF_EVENTS
140 select HAVE_PERF_EVENTS_NMI
141 select HAVE_PERF_REGS
142 select HAVE_PERF_USER_STACK_DUMP
143 select HAVE_REGS_AND_STACK_ACCESS_API
144 select HAVE_SYSCALL_TRACEPOINTS
145 select HAVE_UID16 if X86_32 || IA32_EMULATION
146 select HAVE_UNSTABLE_SCHED_CLOCK
147 select HAVE_USER_RETURN_NOTIFIER
148 select IRQ_FORCED_THREADING
149 select MODULES_USE_ELF_RELA if X86_64
150 select MODULES_USE_ELF_REL if X86_32
151 select OLD_SIGACTION if X86_32
152 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
157 select SYSCTL_EXCEPTION_TRACE
158 select USER_STACKTRACE_SUPPORT
160 select X86_DEV_DMA_OPS if X86_64
161 select X86_FEATURE_NAMES if PROC_FS
163 config INSTRUCTION_DECODER
165 depends on KPROBES || PERF_EVENTS || UPROBES
167 config PERF_EVENTS_INTEL_UNCORE
169 depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
173 default "elf32-i386" if X86_32
174 default "elf64-x86-64" if X86_64
176 config ARCH_DEFCONFIG
178 default "arch/x86/configs/i386_defconfig" if X86_32
179 default "arch/x86/configs/x86_64_defconfig" if X86_64
181 config LOCKDEP_SUPPORT
184 config STACKTRACE_SUPPORT
187 config HAVE_LATENCYTOP_SUPPORT
193 config ARCH_MMAP_RND_BITS_MIN
197 config ARCH_MMAP_RND_BITS_MAX
201 config ARCH_MMAP_RND_COMPAT_BITS_MIN
204 config ARCH_MMAP_RND_COMPAT_BITS_MAX
210 config NEED_DMA_MAP_STATE
212 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
214 config NEED_SG_DMA_LENGTH
217 config GENERIC_ISA_DMA
219 depends on ISA_DMA_API
224 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
226 config GENERIC_BUG_RELATIVE_POINTERS
229 config GENERIC_HWEIGHT
232 config ARCH_MAY_HAVE_PC_FDC
234 depends on ISA_DMA_API
236 config RWSEM_XCHGADD_ALGORITHM
239 config GENERIC_CALIBRATE_DELAY
242 config ARCH_HAS_CPU_RELAX
245 config ARCH_HAS_CACHE_LINE_SIZE
248 config HAVE_SETUP_PER_CPU_AREA
251 config NEED_PER_CPU_EMBED_FIRST_CHUNK
254 config NEED_PER_CPU_PAGE_FIRST_CHUNK
257 config ARCH_HIBERNATION_POSSIBLE
260 config ARCH_SUSPEND_POSSIBLE
263 config ARCH_WANT_HUGE_PMD_SHARE
266 config ARCH_WANT_GENERAL_HUGETLB
275 config ARCH_SUPPORTS_OPTIMIZED_INLINING
278 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
281 config KASAN_SHADOW_OFFSET
284 default 0xdffffc0000000000
286 config HAVE_INTEL_TXT
288 depends on INTEL_IOMMU && ACPI
292 depends on X86_32 && SMP
296 depends on X86_64 && SMP
298 config X86_32_LAZY_GS
300 depends on X86_32 && !CC_STACKPROTECTOR
302 config ARCH_SUPPORTS_UPROBES
305 config FIX_EARLYCON_MEM
311 config PGTABLE_LEVELS
317 source "init/Kconfig"
318 source "kernel/Kconfig.freezer"
320 menu "Processor type and features"
323 bool "DMA memory allocation support" if EXPERT
326 DMA memory allocation support allows devices with less than 32-bit
327 addressing to allocate within the first 16MB of address space.
328 Disable if no such devices will be used.
333 bool "Symmetric multi-processing support"
335 This enables support for systems with more than one CPU. If you have
336 a system with only one CPU, say N. If you have a system with more
339 If you say N here, the kernel will run on uni- and multiprocessor
340 machines, but will use only one CPU of a multiprocessor machine. If
341 you say Y here, the kernel will run on many, but not all,
342 uniprocessor machines. On a uniprocessor machine, the kernel
343 will run faster if you say N here.
345 Note that if you say Y here and choose architecture "586" or
346 "Pentium" under "Processor family", the kernel will not work on 486
347 architectures. Similarly, multiprocessor kernels for the "PPro"
348 architecture may not work on all Pentium based boards.
350 People using multiprocessor machines who say Y here should also say
351 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
352 Management" code will be disabled if you say Y here.
354 See also <file:Documentation/x86/i386/IO-APIC.txt>,
355 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
356 <http://www.tldp.org/docs.html#howto>.
358 If you don't know what to do here, say N.
360 config X86_FEATURE_NAMES
361 bool "Processor feature human-readable names" if EMBEDDED
364 This option compiles in a table of x86 feature bits and corresponding
365 names. This is required to support /proc/cpuinfo and a few kernel
366 messages. You can disable this to save space, at the expense of
367 making those few kernel messages show numeric feature bits instead.
371 config X86_FAST_FEATURE_TESTS
372 bool "Fast CPU feature tests" if EMBEDDED
375 Some fast-paths in the kernel depend on the capabilities of the CPU.
376 Say Y here for the kernel to patch in the appropriate code at runtime
377 based on the capabilities of the CPU. The infrastructure for patching
378 code at runtime takes up some additional space; space-constrained
379 embedded systems may wish to say N here to produce smaller, slightly
383 bool "Support x2apic"
384 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
386 This enables x2apic support on CPUs that have this feature.
388 This allows 32-bit apic IDs (so it can support very large systems),
389 and accesses the local apic via MSRs not via mmio.
391 If you don't know what to do here, say N.
394 bool "Enable MPS table" if ACPI || SFI
396 depends on X86_LOCAL_APIC
398 For old smp systems that do not have proper acpi support. Newer systems
399 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
402 bool "Support for big SMP systems with more than 8 CPUs"
403 depends on X86_32 && SMP
405 This option is needed for the systems that have more than 8 CPUs
409 depends on X86_GOLDFISH
412 bool "Avoid speculative indirect branches in kernel"
415 Compile kernel with the retpoline compiler options to guard against
416 kernel-to-user data leaks by avoiding speculative indirect
417 branches. Requires a compiler with -mindirect-branch=thunk-extern
418 support for full protection. The kernel may run slower.
420 Without compiler support, at least indirect branches in assembler
421 code are eliminated. Since this includes the syscall entry path,
422 it is not entirely pointless.
425 config X86_EXTENDED_PLATFORM
426 bool "Support for extended (non-PC) x86 platforms"
429 If you disable this option then the kernel will only support
430 standard PC platforms. (which covers the vast majority of
433 If you enable this option then you'll be able to select support
434 for the following (non-PC) 32 bit x86 platforms:
435 Goldfish (Android emulator)
438 SGI 320/540 (Visual Workstation)
439 STA2X11-based (e.g. Northville)
440 Moorestown MID devices
442 If you have one of these systems, or if you want to build a
443 generic distribution kernel, say Y here - otherwise say N.
447 config X86_EXTENDED_PLATFORM
448 bool "Support for extended (non-PC) x86 platforms"
451 If you disable this option then the kernel will only support
452 standard PC platforms. (which covers the vast majority of
455 If you enable this option then you'll be able to select support
456 for the following (non-PC) 64 bit x86 platforms:
461 If you have one of these systems, or if you want to build a
462 generic distribution kernel, say Y here - otherwise say N.
464 # This is an alphabetically sorted list of 64 bit extended platforms
465 # Please maintain the alphabetic order if and when there are additions
467 bool "Numascale NumaChip"
469 depends on X86_EXTENDED_PLATFORM
472 depends on X86_X2APIC
473 depends on PCI_MMCONFIG
475 Adds support for Numascale NumaChip large-SMP systems. Needed to
476 enable more than ~168 cores.
477 If you don't have one of these, you should say N here.
481 select HYPERVISOR_GUEST
483 depends on X86_64 && PCI
484 depends on X86_EXTENDED_PLATFORM
487 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
488 supposed to run on these EM64T-based machines. Only choose this option
489 if you have one of these machines.
492 bool "SGI Ultraviolet"
494 depends on X86_EXTENDED_PLATFORM
496 depends on X86_X2APIC
499 This option is needed in order to support SGI Ultraviolet systems.
500 If you don't have one of these, you should say N here.
502 # Following is an alphabetically sorted list of 32 bit extended platforms
503 # Please maintain the alphabetic order if and when there are additions
506 bool "Goldfish (Virtual Platform)"
507 depends on X86_EXTENDED_PLATFORM
509 Enable support for the Goldfish virtual platform used primarily
510 for Android development. Unless you are building for the Android
511 Goldfish emulator say N here.
514 bool "CE4100 TV platform"
516 depends on PCI_GODIRECT
517 depends on X86_IO_APIC
519 depends on X86_EXTENDED_PLATFORM
520 select X86_REBOOTFIXUPS
522 select OF_EARLY_FLATTREE
524 Select for the Intel CE media processor (CE4100) SOC.
525 This option compiles in support for the CE4100 SOC for settop
526 boxes and media devices.
529 bool "Intel MID platform support"
531 depends on X86_EXTENDED_PLATFORM
532 depends on X86_PLATFORM_DEVICES
535 depends on X86_IO_APIC
541 select MFD_INTEL_MSIC
543 Select to build a kernel capable of supporting Intel MID (Mobile
544 Internet Device) platform systems which do not have the PCI legacy
545 interfaces. If you are building for a PC class system say N here.
547 Intel MID platforms are based on an Intel processor and chipset which
548 consume less power than most of the x86 derivatives.
550 config X86_INTEL_QUARK
551 bool "Intel Quark platform support"
553 depends on X86_EXTENDED_PLATFORM
554 depends on X86_PLATFORM_DEVICES
558 depends on X86_IO_APIC
563 Select to include support for Quark X1000 SoC.
564 Say Y here if you have a Quark based system such as the Arduino
565 compatible Intel Galileo.
567 config X86_INTEL_LPSS
568 bool "Intel Low Power Subsystem Support"
573 Select to build support for Intel Low Power Subsystem such as
574 found on Intel Lynxpoint PCH. Selecting this option enables
575 things like clock tree (common clock framework) and pincontrol
576 which are needed by the LPSS peripheral drivers.
578 config X86_AMD_PLATFORM_DEVICE
579 bool "AMD ACPI2Platform devices support"
584 Select to interpret AMD specific ACPI device to platform device
585 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
586 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
587 implemented under PINCTRL subsystem.
590 tristate "Intel SoC IOSF Sideband support for SoC platforms"
593 This option enables sideband register access support for Intel SoC
594 platforms. On these platforms the IOSF sideband is used in lieu of
595 MSR's for some register accesses, mostly but not limited to thermal
596 and power. Drivers may query the availability of this device to
597 determine if they need the sideband in order to work on these
598 platforms. The sideband is available on the following SoC products.
599 This list is not meant to be exclusive.
604 You should say Y if you are running a kernel on one of these SoC's.
606 config IOSF_MBI_DEBUG
607 bool "Enable IOSF sideband access through debugfs"
608 depends on IOSF_MBI && DEBUG_FS
610 Select this option to expose the IOSF sideband access registers (MCR,
611 MDR, MCRX) through debugfs to write and read register information from
612 different units on the SoC. This is most useful for obtaining device
613 state information for debug and analysis. As this is a general access
614 mechanism, users of this option would have specific knowledge of the
615 device they want to access.
617 If you don't require the option or are in doubt, say N.
620 bool "RDC R-321x SoC"
622 depends on X86_EXTENDED_PLATFORM
624 select X86_REBOOTFIXUPS
626 This option is needed for RDC R-321x system-on-chip, also known
628 If you don't have one of these chips, you should say N here.
630 config X86_32_NON_STANDARD
631 bool "Support non-standard 32-bit SMP architectures"
632 depends on X86_32 && SMP
633 depends on X86_EXTENDED_PLATFORM
635 This option compiles in the bigsmp and STA2X11 default
636 subarchitectures. It is intended for a generic binary
637 kernel. If you select them all, kernel will probe it one by
638 one and will fallback to default.
640 # Alphabetically sorted list of Non standard 32 bit platforms
642 config X86_SUPPORTS_MEMORY_FAILURE
644 # MCE code calls memory_failure():
646 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
647 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
648 depends on X86_64 || !SPARSEMEM
649 select ARCH_SUPPORTS_MEMORY_FAILURE
652 bool "STA2X11 Companion Chip Support"
653 depends on X86_32_NON_STANDARD && PCI
654 select X86_DEV_DMA_OPS
658 select ARCH_REQUIRE_GPIOLIB
661 This adds support for boards based on the STA2X11 IO-Hub,
662 a.k.a. "ConneXt". The chip is used in place of the standard
663 PC chipset, so all "standard" peripherals are missing. If this
664 option is selected the kernel will still be able to boot on
665 standard PC machines.
668 tristate "Eurobraille/Iris poweroff module"
671 The Iris machines from EuroBraille do not have APM or ACPI support
672 to shut themselves down properly. A special I/O sequence is
673 needed to do so, which is what this module does at
676 This is only for Iris machines from EuroBraille.
680 config SCHED_OMIT_FRAME_POINTER
682 prompt "Single-depth WCHAN output"
685 Calculate simpler /proc/<PID>/wchan values. If this option
686 is disabled then wchan values will recurse back to the
687 caller function. This provides more accurate wchan values,
688 at the expense of slightly more scheduling overhead.
690 If in doubt, say "Y".
692 menuconfig HYPERVISOR_GUEST
693 bool "Linux guest support"
695 Say Y here to enable options for running Linux under various hyper-
696 visors. This option enables basic hypervisor detection and platform
699 If you say N, all options in this submenu will be skipped and
700 disabled, and Linux guest support won't be built in.
705 bool "Enable paravirtualization code"
707 This changes the kernel so it can modify itself when it is run
708 under a hypervisor, potentially improving performance significantly
709 over full virtualization. However, when run without a hypervisor
710 the kernel is theoretically slower and slightly larger.
712 config PARAVIRT_DEBUG
713 bool "paravirt-ops debugging"
714 depends on PARAVIRT && DEBUG_KERNEL
716 Enable to debug paravirt_ops internals. Specifically, BUG if
717 a paravirt_op is missing when it is called.
719 config PARAVIRT_SPINLOCKS
720 bool "Paravirtualization layer for spinlocks"
721 depends on PARAVIRT && SMP
722 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
724 Paravirtualized spinlocks allow a pvops backend to replace the
725 spinlock implementation with something virtualization-friendly
726 (for example, block the virtual CPU rather than spinning).
728 It has a minimal impact on native kernels and gives a nice performance
729 benefit on paravirtualized KVM / Xen kernels.
731 If you are unsure how to answer this question, answer Y.
733 source "arch/x86/xen/Kconfig"
736 bool "KVM Guest support (including kvmclock)"
738 select PARAVIRT_CLOCK
741 This option enables various optimizations for running under the KVM
742 hypervisor. It includes a paravirtualized clock, so that instead
743 of relying on a PIT (or probably other) emulation by the
744 underlying device model, the host provides the guest with
745 timing infrastructure such as time of day, and system time
748 bool "Enable debug information for KVM Guests in debugfs"
749 depends on KVM_GUEST && DEBUG_FS
752 This option enables collection of various statistics for KVM guest.
753 Statistics are displayed in debugfs filesystem. Enabling this option
754 may incur significant overhead.
756 source "arch/x86/lguest/Kconfig"
758 config PARAVIRT_TIME_ACCOUNTING
759 bool "Paravirtual steal time accounting"
763 Select this option to enable fine granularity task steal time
764 accounting. Time spent executing other tasks in parallel with
765 the current vCPU is discounted from the vCPU power. To account for
766 that, there can be a small performance impact.
768 If in doubt, say N here.
770 config PARAVIRT_CLOCK
773 endif #HYPERVISOR_GUEST
778 source "arch/x86/Kconfig.cpu"
782 prompt "HPET Timer Support" if X86_32
784 Use the IA-PC HPET (High Precision Event Timer) to manage
785 time in preference to the PIT and RTC, if a HPET is
787 HPET is the next generation timer replacing legacy 8254s.
788 The HPET provides a stable time base on SMP
789 systems, unlike the TSC, but it is more expensive to access,
790 as it is off-chip. You can find the HPET spec at
791 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
793 You can safely choose Y here. However, HPET will only be
794 activated if the platform and the BIOS support this feature.
795 Otherwise the 8254 will be used for timing services.
797 Choose N to continue using the legacy 8254 timer.
799 config HPET_EMULATE_RTC
801 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
804 def_bool y if X86_INTEL_MID
805 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
807 depends on X86_INTEL_MID && SFI
809 APB timer is the replacement for 8254, HPET on X86 MID platforms.
810 The APBT provides a stable time base on SMP
811 systems, unlike the TSC, but it is more expensive to access,
812 as it is off-chip. APB timers are always running regardless of CPU
813 C states, they are used as per CPU clockevent device when possible.
815 # Mark as expert because too many people got it wrong.
816 # The code disables itself when not needed.
819 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
820 bool "Enable DMI scanning" if EXPERT
822 Enabled scanning of DMI to identify machine quirks. Say Y
823 here unless you have verified that your setup is not
824 affected by entries in the DMI blacklist. Required by PNP
828 bool "Old AMD GART IOMMU support"
830 depends on X86_64 && PCI && AMD_NB
832 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
833 GART based hardware IOMMUs.
835 The GART supports full DMA access for devices with 32-bit access
836 limitations, on systems with more than 3 GB. This is usually needed
837 for USB, sound, many IDE/SATA chipsets and some other devices.
839 Newer systems typically have a modern AMD IOMMU, supported via
840 the CONFIG_AMD_IOMMU=y config option.
842 In normal configurations this driver is only active when needed:
843 there's more than 3 GB of memory and the system contains a
844 32-bit limited device.
849 bool "IBM Calgary IOMMU support"
851 depends on X86_64 && PCI
853 Support for hardware IOMMUs in IBM's xSeries x366 and x460
854 systems. Needed to run systems with more than 3GB of memory
855 properly with 32-bit PCI devices that do not support DAC
856 (Double Address Cycle). Calgary also supports bus level
857 isolation, where all DMAs pass through the IOMMU. This
858 prevents them from going anywhere except their intended
859 destination. This catches hard-to-find kernel bugs and
860 mis-behaving drivers and devices that do not use the DMA-API
861 properly to set up their DMA buffers. The IOMMU can be
862 turned off at boot time with the iommu=off parameter.
863 Normally the kernel will make the right choice by itself.
866 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
868 prompt "Should Calgary be enabled by default?"
869 depends on CALGARY_IOMMU
871 Should Calgary be enabled by default? if you choose 'y', Calgary
872 will be used (if it exists). If you choose 'n', Calgary will not be
873 used even if it exists. If you choose 'n' and would like to use
874 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
877 # need this always selected by IOMMU for the VIA workaround
881 Support for software bounce buffers used on x86-64 systems
882 which don't have a hardware IOMMU. Using this PCI devices
883 which can only access 32-bits of memory can be used on systems
884 with more than 3 GB of memory.
889 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
892 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
893 depends on X86_64 && SMP && DEBUG_KERNEL
894 select CPUMASK_OFFSTACK
896 Enable maximum number of CPUS and NUMA Nodes for this architecture.
900 int "Maximum number of CPUs" if SMP && !MAXSMP
901 range 2 8 if SMP && X86_32 && !X86_BIGSMP
902 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
903 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
905 default "8192" if MAXSMP
906 default "32" if SMP && X86_BIGSMP
907 default "8" if SMP && X86_32
910 This allows you to specify the maximum number of CPUs which this
911 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
912 supported value is 8192, otherwise the maximum value is 512. The
913 minimum value which makes sense is 2.
915 This is purely to save memory - each supported CPU adds
916 approximately eight kilobytes to the kernel image.
923 prompt "Multi-core scheduler support"
926 Multi-core scheduler support improves the CPU scheduler's decision
927 making when dealing with multi-core CPU chips at a cost of slightly
928 increased overhead in some places. If unsure say N here.
930 source "kernel/Kconfig.preempt"
934 depends on !SMP && X86_LOCAL_APIC
937 bool "Local APIC support on uniprocessors" if !PCI_MSI
939 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
941 A local APIC (Advanced Programmable Interrupt Controller) is an
942 integrated interrupt controller in the CPU. If you have a single-CPU
943 system which has a processor with a local APIC, you can say Y here to
944 enable and use it. If you say Y here even though your machine doesn't
945 have a local APIC, then the kernel will still run with no slowdown at
946 all. The local APIC supports CPU-generated self-interrupts (timer,
947 performance counters), and the NMI watchdog which detects hard
951 bool "IO-APIC support on uniprocessors"
952 depends on X86_UP_APIC
954 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
955 SMP-capable replacement for PC-style interrupt controllers. Most
956 SMP systems and many recent uniprocessor systems have one.
958 If you have a single-CPU system with an IO-APIC, you can say Y here
959 to use it. If you say Y here even though your machine doesn't have
960 an IO-APIC, then the kernel will still run with no slowdown at all.
962 config X86_LOCAL_APIC
964 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
965 select IRQ_DOMAIN_HIERARCHY
966 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
970 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
972 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
973 bool "Reroute for broken boot IRQs"
974 depends on X86_IO_APIC
976 This option enables a workaround that fixes a source of
977 spurious interrupts. This is recommended when threaded
978 interrupt handling is used on systems where the generation of
979 superfluous "boot interrupts" cannot be disabled.
981 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
982 entry in the chipset's IO-APIC is masked (as, e.g. the RT
983 kernel does during interrupt handling). On chipsets where this
984 boot IRQ generation cannot be disabled, this workaround keeps
985 the original IRQ line masked so that only the equivalent "boot
986 IRQ" is delivered to the CPUs. The workaround also tells the
987 kernel to set up the IRQ handler on the boot IRQ line. In this
988 way only one interrupt is delivered to the kernel. Otherwise
989 the spurious second interrupt may cause the kernel to bring
990 down (vital) interrupt lines.
992 Only affects "broken" chipsets. Interrupt sharing may be
993 increased on these systems.
996 bool "Machine Check / overheating reporting"
997 select GENERIC_ALLOCATOR
1000 Machine Check support allows the processor to notify the
1001 kernel if it detects a problem (e.g. overheating, data corruption).
1002 The action the kernel takes depends on the severity of the problem,
1003 ranging from warning messages to halting the machine.
1005 config X86_MCE_INTEL
1007 prompt "Intel MCE features"
1008 depends on X86_MCE && X86_LOCAL_APIC
1010 Additional support for intel specific MCE features such as
1011 the thermal monitor.
1015 prompt "AMD MCE features"
1016 depends on X86_MCE && X86_LOCAL_APIC
1018 Additional support for AMD specific MCE features such as
1019 the DRAM Error Threshold.
1021 config X86_ANCIENT_MCE
1022 bool "Support for old Pentium 5 / WinChip machine checks"
1023 depends on X86_32 && X86_MCE
1025 Include support for machine check handling on old Pentium 5 or WinChip
1026 systems. These typically need to be enabled explicitly on the command
1029 config X86_MCE_THRESHOLD
1030 depends on X86_MCE_AMD || X86_MCE_INTEL
1033 config X86_MCE_INJECT
1034 depends on X86_MCE && X86_LOCAL_APIC
1035 tristate "Machine check injector support"
1037 Provide support for injecting machine checks for testing purposes.
1038 If you don't know what a machine check is and you don't do kernel
1039 QA it is safe to say n.
1041 config X86_THERMAL_VECTOR
1043 depends on X86_MCE_INTEL
1045 config X86_LEGACY_VM86
1046 bool "Legacy VM86 support"
1050 This option allows user programs to put the CPU into V8086
1051 mode, which is an 80286-era approximation of 16-bit real mode.
1053 Some very old versions of X and/or vbetool require this option
1054 for user mode setting. Similarly, DOSEMU will use it if
1055 available to accelerate real mode DOS programs. However, any
1056 recent version of DOSEMU, X, or vbetool should be fully
1057 functional even without kernel VM86 support, as they will all
1058 fall back to software emulation. Nevertheless, if you are using
1059 a 16-bit DOS program where 16-bit performance matters, vm86
1060 mode might be faster than emulation and you might want to
1063 Note that any app that works on a 64-bit kernel is unlikely to
1064 need this option, as 64-bit kernels don't, and can't, support
1065 V8086 mode. This option is also unrelated to 16-bit protected
1066 mode and is not needed to run most 16-bit programs under Wine.
1068 Enabling this option increases the complexity of the kernel
1069 and slows down exception handling a tiny bit.
1071 If unsure, say N here.
1075 default X86_LEGACY_VM86
1078 bool "Enable support for 16-bit segments" if EXPERT
1080 depends on MODIFY_LDT_SYSCALL
1082 This option is required by programs like Wine to run 16-bit
1083 protected mode legacy code on x86 processors. Disabling
1084 this option saves about 300 bytes on i386, or around 6K text
1085 plus 16K runtime memory on x86-64,
1089 depends on X86_16BIT && X86_32
1093 depends on X86_16BIT && X86_64
1095 config X86_VSYSCALL_EMULATION
1096 bool "Enable vsyscall emulation" if EXPERT
1100 This enables emulation of the legacy vsyscall page. Disabling
1101 it is roughly equivalent to booting with vsyscall=none, except
1102 that it will also disable the helpful warning if a program
1103 tries to use a vsyscall. With this option set to N, offending
1104 programs will just segfault, citing addresses of the form
1107 This option is required by many programs built before 2013, and
1108 care should be used even with newer programs if set to N.
1110 Disabling this option saves about 7K of kernel size and
1111 possibly 4K of additional runtime pagetable memory.
1114 tristate "Toshiba Laptop support"
1117 This adds a driver to safely access the System Management Mode of
1118 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1119 not work on models with a Phoenix BIOS. The System Management Mode
1120 is used to set the BIOS and power saving options on Toshiba portables.
1122 For information on utilities to make use of this driver see the
1123 Toshiba Linux utilities web site at:
1124 <http://www.buzzard.org.uk/toshiba/>.
1126 Say Y if you intend to run this kernel on a Toshiba portable.
1130 tristate "Dell i8k legacy laptop support"
1132 select SENSORS_DELL_SMM
1134 This option enables legacy /proc/i8k userspace interface in hwmon
1135 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1136 temperature and allows controlling fan speeds of Dell laptops via
1137 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1138 it reports also power and hotkey status. For fan speed control is
1139 needed userspace package i8kutils.
1141 Say Y if you intend to run this kernel on old Dell laptops or want to
1142 use userspace package i8kutils.
1145 config X86_REBOOTFIXUPS
1146 bool "Enable X86 board specific fixups for reboot"
1149 This enables chipset and/or board specific fixups to be done
1150 in order to get reboot to work correctly. This is only needed on
1151 some combinations of hardware and BIOS. The symptom, for which
1152 this config is intended, is when reboot ends with a stalled/hung
1155 Currently, the only fixup is for the Geode machines using
1156 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1158 Say Y if you want to enable the fixup. Currently, it's safe to
1159 enable this option even if you don't need it.
1163 bool "CPU microcode loading support"
1165 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1168 If you say Y here, you will be able to update the microcode on
1169 Intel and AMD processors. The Intel support is for the IA32 family,
1170 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1171 AMD support is for families 0x10 and later. You will obviously need
1172 the actual microcode binary data itself which is not shipped with
1175 The preferred method to load microcode from a detached initrd is described
1176 in Documentation/x86/early-microcode.txt. For that you need to enable
1177 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1178 initrd for microcode blobs.
1180 In addition, you can build-in the microcode into the kernel. For that you
1181 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1182 to the CONFIG_EXTRA_FIRMWARE config option.
1184 config MICROCODE_INTEL
1185 bool "Intel microcode loading support"
1186 depends on MICROCODE
1190 This options enables microcode patch loading support for Intel
1193 For the current Intel microcode data package go to
1194 <https://downloadcenter.intel.com> and search for
1195 'Linux Processor Microcode Data File'.
1197 config MICROCODE_AMD
1198 bool "AMD microcode loading support"
1199 depends on MICROCODE
1202 If you select this option, microcode patch loading support for AMD
1203 processors will be enabled.
1205 config MICROCODE_OLD_INTERFACE
1207 depends on MICROCODE
1210 tristate "/dev/cpu/*/msr - Model-specific register support"
1212 This device gives privileged processes access to the x86
1213 Model-Specific Registers (MSRs). It is a character device with
1214 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1215 MSR accesses are directed to a specific CPU on multi-processor
1219 tristate "/dev/cpu/*/cpuid - CPU information support"
1221 This device gives processes access to the x86 CPUID instruction to
1222 be executed on a specific processor. It is a character device
1223 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1227 prompt "High Memory Support"
1234 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1235 However, the address space of 32-bit x86 processors is only 4
1236 Gigabytes large. That means that, if you have a large amount of
1237 physical memory, not all of it can be "permanently mapped" by the
1238 kernel. The physical memory that's not permanently mapped is called
1241 If you are compiling a kernel which will never run on a machine with
1242 more than 1 Gigabyte total physical RAM, answer "off" here (default
1243 choice and suitable for most users). This will result in a "3GB/1GB"
1244 split: 3GB are mapped so that each process sees a 3GB virtual memory
1245 space and the remaining part of the 4GB virtual memory space is used
1246 by the kernel to permanently map as much physical memory as
1249 If the machine has between 1 and 4 Gigabytes physical RAM, then
1252 If more than 4 Gigabytes is used then answer "64GB" here. This
1253 selection turns Intel PAE (Physical Address Extension) mode on.
1254 PAE implements 3-level paging on IA32 processors. PAE is fully
1255 supported by Linux, PAE mode is implemented on all recent Intel
1256 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1257 then the kernel will not boot on CPUs that don't support PAE!
1259 The actual amount of total physical memory will either be
1260 auto detected or can be forced by using a kernel command line option
1261 such as "mem=256M". (Try "man bootparam" or see the documentation of
1262 your boot loader (lilo or loadlin) about how to pass options to the
1263 kernel at boot time.)
1265 If unsure, say "off".
1270 Select this if you have a 32-bit processor and between 1 and 4
1271 gigabytes of physical RAM.
1278 Select this if you have a 32-bit processor and more than 4
1279 gigabytes of physical RAM.
1284 prompt "Memory split" if EXPERT
1288 Select the desired split between kernel and user memory.
1290 If the address range available to the kernel is less than the
1291 physical memory installed, the remaining memory will be available
1292 as "high memory". Accessing high memory is a little more costly
1293 than low memory, as it needs to be mapped into the kernel first.
1294 Note that increasing the kernel address space limits the range
1295 available to user programs, making the address space there
1296 tighter. Selecting anything other than the default 3G/1G split
1297 will also likely make your kernel incompatible with binary-only
1300 If you are not absolutely sure what you are doing, leave this
1304 bool "3G/1G user/kernel split"
1305 config VMSPLIT_3G_OPT
1307 bool "3G/1G user/kernel split (for full 1G low memory)"
1309 bool "2G/2G user/kernel split"
1310 config VMSPLIT_2G_OPT
1312 bool "2G/2G user/kernel split (for full 2G low memory)"
1314 bool "1G/3G user/kernel split"
1319 default 0xB0000000 if VMSPLIT_3G_OPT
1320 default 0x80000000 if VMSPLIT_2G
1321 default 0x78000000 if VMSPLIT_2G_OPT
1322 default 0x40000000 if VMSPLIT_1G
1328 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1331 bool "PAE (Physical Address Extension) Support"
1332 depends on X86_32 && !HIGHMEM4G
1335 PAE is required for NX support, and furthermore enables
1336 larger swapspace support for non-overcommit purposes. It
1337 has the cost of more pagetable lookup overhead, and also
1338 consumes more pagetable space per process.
1340 config ARCH_PHYS_ADDR_T_64BIT
1342 depends on X86_64 || X86_PAE
1344 config ARCH_DMA_ADDR_T_64BIT
1346 depends on X86_64 || HIGHMEM64G
1348 config X86_DIRECT_GBPAGES
1350 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1352 Certain kernel features effectively disable kernel
1353 linear 1 GB mappings (even if the CPU otherwise
1354 supports them), so don't confuse the user by printing
1355 that we have them enabled.
1357 # Common NUMA Features
1359 bool "Numa Memory Allocation and Scheduler Support"
1361 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1362 default y if X86_BIGSMP
1364 Enable NUMA (Non Uniform Memory Access) support.
1366 The kernel will try to allocate memory used by a CPU on the
1367 local memory controller of the CPU and add some more
1368 NUMA awareness to the kernel.
1370 For 64-bit this is recommended if the system is Intel Core i7
1371 (or later), AMD Opteron, or EM64T NUMA.
1373 For 32-bit this is only needed if you boot a 32-bit
1374 kernel on a 64-bit NUMA platform.
1376 Otherwise, you should say N.
1380 prompt "Old style AMD Opteron NUMA detection"
1381 depends on X86_64 && NUMA && PCI
1383 Enable AMD NUMA node topology detection. You should say Y here if
1384 you have a multi processor AMD system. This uses an old method to
1385 read the NUMA configuration directly from the builtin Northbridge
1386 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1387 which also takes priority if both are compiled in.
1389 config X86_64_ACPI_NUMA
1391 prompt "ACPI NUMA detection"
1392 depends on X86_64 && NUMA && ACPI && PCI
1395 Enable ACPI SRAT based node topology detection.
1397 # Some NUMA nodes have memory ranges that span
1398 # other nodes. Even though a pfn is valid and
1399 # between a node's start and end pfns, it may not
1400 # reside on that node. See memmap_init_zone()
1402 config NODES_SPAN_OTHER_NODES
1404 depends on X86_64_ACPI_NUMA
1407 bool "NUMA emulation"
1410 Enable NUMA emulation. A flat machine will be split
1411 into virtual nodes when booted with "numa=fake=N", where N is the
1412 number of nodes. This is only useful for debugging.
1415 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1417 default "10" if MAXSMP
1418 default "6" if X86_64
1420 depends on NEED_MULTIPLE_NODES
1422 Specify the maximum number of NUMA Nodes available on the target
1423 system. Increases memory reserved to accommodate various tables.
1425 config ARCH_HAVE_MEMORY_PRESENT
1427 depends on X86_32 && DISCONTIGMEM
1429 config NEED_NODE_MEMMAP_SIZE
1431 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1433 config ARCH_FLATMEM_ENABLE
1435 depends on X86_32 && !NUMA
1437 config ARCH_DISCONTIGMEM_ENABLE
1439 depends on NUMA && X86_32
1441 config ARCH_DISCONTIGMEM_DEFAULT
1443 depends on NUMA && X86_32
1445 config ARCH_SPARSEMEM_ENABLE
1447 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1448 select SPARSEMEM_STATIC if X86_32
1449 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1451 config ARCH_SPARSEMEM_DEFAULT
1455 config ARCH_SELECT_MEMORY_MODEL
1457 depends on ARCH_SPARSEMEM_ENABLE
1459 config ARCH_MEMORY_PROBE
1460 bool "Enable sysfs memory/probe interface"
1461 depends on X86_64 && MEMORY_HOTPLUG
1463 This option enables a sysfs memory/probe interface for testing.
1464 See Documentation/memory-hotplug.txt for more information.
1465 If you are unsure how to answer this question, answer N.
1467 config ARCH_PROC_KCORE_TEXT
1469 depends on X86_64 && PROC_KCORE
1471 config ILLEGAL_POINTER_VALUE
1474 default 0xdead000000000000 if X86_64
1478 config X86_PMEM_LEGACY_DEVICE
1481 config X86_PMEM_LEGACY
1482 tristate "Support non-standard NVDIMMs and ADR protected memory"
1483 depends on PHYS_ADDR_T_64BIT
1485 select X86_PMEM_LEGACY_DEVICE
1488 Treat memory marked using the non-standard e820 type of 12 as used
1489 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1490 The kernel will offer these regions to the 'pmem' driver so
1491 they can be used for persistent storage.
1496 bool "Allocate 3rd-level pagetables from highmem"
1499 The VM uses one page table entry for each page of physical memory.
1500 For systems with a lot of RAM, this can be wasteful of precious
1501 low memory. Setting this option will put user-space page table
1502 entries in high memory.
1504 config X86_CHECK_BIOS_CORRUPTION
1505 bool "Check for low memory corruption"
1507 Periodically check for memory corruption in low memory, which
1508 is suspected to be caused by BIOS. Even when enabled in the
1509 configuration, it is disabled at runtime. Enable it by
1510 setting "memory_corruption_check=1" on the kernel command
1511 line. By default it scans the low 64k of memory every 60
1512 seconds; see the memory_corruption_check_size and
1513 memory_corruption_check_period parameters in
1514 Documentation/kernel-parameters.txt to adjust this.
1516 When enabled with the default parameters, this option has
1517 almost no overhead, as it reserves a relatively small amount
1518 of memory and scans it infrequently. It both detects corruption
1519 and prevents it from affecting the running system.
1521 It is, however, intended as a diagnostic tool; if repeatable
1522 BIOS-originated corruption always affects the same memory,
1523 you can use memmap= to prevent the kernel from using that
1526 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1527 bool "Set the default setting of memory_corruption_check"
1528 depends on X86_CHECK_BIOS_CORRUPTION
1531 Set whether the default state of memory_corruption_check is
1534 config X86_RESERVE_LOW
1535 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1539 Specify the amount of low memory to reserve for the BIOS.
1541 The first page contains BIOS data structures that the kernel
1542 must not use, so that page must always be reserved.
1544 By default we reserve the first 64K of physical RAM, as a
1545 number of BIOSes are known to corrupt that memory range
1546 during events such as suspend/resume or monitor cable
1547 insertion, so it must not be used by the kernel.
1549 You can set this to 4 if you are absolutely sure that you
1550 trust the BIOS to get all its memory reservations and usages
1551 right. If you know your BIOS have problems beyond the
1552 default 64K area, you can set this to 640 to avoid using the
1553 entire low memory range.
1555 If you have doubts about the BIOS (e.g. suspend/resume does
1556 not work or there's kernel crashes after certain hardware
1557 hotplug events) then you might want to enable
1558 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1559 typical corruption patterns.
1561 Leave this to the default value of 64 if you are unsure.
1563 config MATH_EMULATION
1565 depends on MODIFY_LDT_SYSCALL
1566 prompt "Math emulation" if X86_32
1568 Linux can emulate a math coprocessor (used for floating point
1569 operations) if you don't have one. 486DX and Pentium processors have
1570 a math coprocessor built in, 486SX and 386 do not, unless you added
1571 a 487DX or 387, respectively. (The messages during boot time can
1572 give you some hints here ["man dmesg"].) Everyone needs either a
1573 coprocessor or this emulation.
1575 If you don't have a math coprocessor, you need to say Y here; if you
1576 say Y here even though you have a coprocessor, the coprocessor will
1577 be used nevertheless. (This behavior can be changed with the kernel
1578 command line option "no387", which comes handy if your coprocessor
1579 is broken. Try "man bootparam" or see the documentation of your boot
1580 loader (lilo or loadlin) about how to pass options to the kernel at
1581 boot time.) This means that it is a good idea to say Y here if you
1582 intend to use this kernel on different machines.
1584 More information about the internals of the Linux math coprocessor
1585 emulation can be found in <file:arch/x86/math-emu/README>.
1587 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1588 kernel, it won't hurt.
1592 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1594 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1595 the Memory Type Range Registers (MTRRs) may be used to control
1596 processor access to memory ranges. This is most useful if you have
1597 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1598 allows bus write transfers to be combined into a larger transfer
1599 before bursting over the PCI/AGP bus. This can increase performance
1600 of image write operations 2.5 times or more. Saying Y here creates a
1601 /proc/mtrr file which may be used to manipulate your processor's
1602 MTRRs. Typically the X server should use this.
1604 This code has a reasonably generic interface so that similar
1605 control registers on other processors can be easily supported
1608 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1609 Registers (ARRs) which provide a similar functionality to MTRRs. For
1610 these, the ARRs are used to emulate the MTRRs.
1611 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1612 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1613 write-combining. All of these processors are supported by this code
1614 and it makes sense to say Y here if you have one of them.
1616 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1617 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1618 can lead to all sorts of problems, so it's good to say Y here.
1620 You can safely say Y even if your machine doesn't have MTRRs, you'll
1621 just add about 9 KB to your kernel.
1623 See <file:Documentation/x86/mtrr.txt> for more information.
1625 config MTRR_SANITIZER
1627 prompt "MTRR cleanup support"
1630 Convert MTRR layout from continuous to discrete, so X drivers can
1631 add writeback entries.
1633 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1634 The largest mtrr entry size for a continuous block can be set with
1639 config MTRR_SANITIZER_ENABLE_DEFAULT
1640 int "MTRR cleanup enable value (0-1)"
1643 depends on MTRR_SANITIZER
1645 Enable mtrr cleanup default value
1647 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1648 int "MTRR cleanup spare reg num (0-7)"
1651 depends on MTRR_SANITIZER
1653 mtrr cleanup spare entries default, it can be changed via
1654 mtrr_spare_reg_nr=N on the kernel command line.
1658 prompt "x86 PAT support" if EXPERT
1661 Use PAT attributes to setup page level cache control.
1663 PATs are the modern equivalents of MTRRs and are much more
1664 flexible than MTRRs.
1666 Say N here if you see bootup problems (boot crash, boot hang,
1667 spontaneous reboots) or a non-working video driver.
1671 config ARCH_USES_PG_UNCACHED
1677 prompt "x86 architectural random number generator" if EXPERT
1679 Enable the x86 architectural RDRAND instruction
1680 (Intel Bull Mountain technology) to generate random numbers.
1681 If supported, this is a high bandwidth, cryptographically
1682 secure hardware random number generator.
1686 prompt "Supervisor Mode Access Prevention" if EXPERT
1688 Supervisor Mode Access Prevention (SMAP) is a security
1689 feature in newer Intel processors. There is a small
1690 performance cost if this enabled and turned on; there is
1691 also a small increase in the kernel size if this is enabled.
1695 config X86_INTEL_MPX
1696 prompt "Intel MPX (Memory Protection Extensions)"
1698 depends on CPU_SUP_INTEL
1700 MPX provides hardware features that can be used in
1701 conjunction with compiler-instrumented code to check
1702 memory references. It is designed to detect buffer
1703 overflow or underflow bugs.
1705 This option enables running applications which are
1706 instrumented or otherwise use MPX. It does not use MPX
1707 itself inside the kernel or to protect the kernel
1708 against bad memory references.
1710 Enabling this option will make the kernel larger:
1711 ~8k of kernel text and 36 bytes of data on a 64-bit
1712 defconfig. It adds a long to the 'mm_struct' which
1713 will increase the kernel memory overhead of each
1714 process and adds some branches to paths used during
1715 exec() and munmap().
1717 For details, see Documentation/x86/intel_mpx.txt
1722 prompt "TSX enable mode"
1723 depends on CPU_SUP_INTEL
1724 default X86_INTEL_TSX_MODE_OFF
1726 Intel's TSX (Transactional Synchronization Extensions) feature
1727 allows to optimize locking protocols through lock elision which
1728 can lead to a noticeable performance boost.
1730 On the other hand it has been shown that TSX can be exploited
1731 to form side channel attacks (e.g. TAA) and chances are there
1732 will be more of those attacks discovered in the future.
1734 Therefore TSX is not enabled by default (aka tsx=off). An admin
1735 might override this decision by tsx=on the command line parameter.
1736 Even with TSX enabled, the kernel will attempt to enable the best
1737 possible TAA mitigation setting depending on the microcode available
1738 for the particular machine.
1740 This option allows to set the default tsx mode between tsx=on, =off
1741 and =auto. See Documentation/kernel-parameters.txt for more
1744 Say off if not sure, auto if TSX is in use but it should be used on safe
1745 platforms or on if TSX is in use and the security aspect of tsx is not
1748 config X86_INTEL_TSX_MODE_OFF
1751 TSX is disabled if possible - equals to tsx=off command line parameter.
1753 config X86_INTEL_TSX_MODE_ON
1756 TSX is always enabled on TSX capable HW - equals the tsx=on command
1759 config X86_INTEL_TSX_MODE_AUTO
1762 TSX is enabled on TSX capable HW that is believed to be safe against
1763 side channel attacks- equals the tsx=auto command line parameter.
1767 bool "EFI runtime service support"
1770 select EFI_RUNTIME_WRAPPERS
1772 This enables the kernel to use EFI runtime services that are
1773 available (such as the EFI variable services).
1775 This option is only useful on systems that have EFI firmware.
1776 In addition, you should use the latest ELILO loader available
1777 at <http://elilo.sourceforge.net> in order to take advantage
1778 of EFI runtime services. However, even with this option, the
1779 resultant kernel should continue to boot on existing non-EFI
1783 bool "EFI stub support"
1784 depends on EFI && !X86_USE_3DNOW
1787 This kernel feature allows a bzImage to be loaded directly
1788 by EFI firmware without the use of a bootloader.
1790 See Documentation/efi-stub.txt for more information.
1793 bool "EFI mixed-mode support"
1794 depends on EFI_STUB && X86_64
1796 Enabling this feature allows a 64-bit kernel to be booted
1797 on a 32-bit firmware, provided that your CPU supports 64-bit
1800 Note that it is not possible to boot a mixed-mode enabled
1801 kernel via the EFI boot stub - a bootloader that supports
1802 the EFI handover protocol must be used.
1808 prompt "Enable seccomp to safely compute untrusted bytecode"
1810 This kernel feature is useful for number crunching applications
1811 that may need to compute untrusted bytecode during their
1812 execution. By using pipes or other transports made available to
1813 the process as file descriptors supporting the read/write
1814 syscalls, it's possible to isolate those applications in
1815 their own address space using seccomp. Once seccomp is
1816 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1817 and the task is only allowed to execute a few safe syscalls
1818 defined by each seccomp mode.
1820 If unsure, say Y. Only embedded should say N here.
1822 source kernel/Kconfig.hz
1825 bool "kexec system call"
1828 kexec is a system call that implements the ability to shutdown your
1829 current kernel, and to start another kernel. It is like a reboot
1830 but it is independent of the system firmware. And like a reboot
1831 you can start any kernel with it, not just Linux.
1833 The name comes from the similarity to the exec system call.
1835 It is an ongoing process to be certain the hardware in a machine
1836 is properly shutdown, so do not be surprised if this code does not
1837 initially work for you. As of this writing the exact hardware
1838 interface is strongly in flux, so no good recommendation can be
1842 bool "kexec file based system call"
1847 depends on CRYPTO_SHA256=y
1849 This is new version of kexec system call. This system call is
1850 file based and takes file descriptors as system call argument
1851 for kernel and initramfs as opposed to list of segments as
1852 accepted by previous system call.
1854 config KEXEC_VERIFY_SIG
1855 bool "Verify kernel signature during kexec_file_load() syscall"
1856 depends on KEXEC_FILE
1858 This option makes kernel signature verification mandatory for
1859 the kexec_file_load() syscall.
1861 In addition to that option, you need to enable signature
1862 verification for the corresponding kernel image type being
1863 loaded in order for this to work.
1865 config KEXEC_BZIMAGE_VERIFY_SIG
1866 bool "Enable bzImage signature verification support"
1867 depends on KEXEC_VERIFY_SIG
1868 depends on SIGNED_PE_FILE_VERIFICATION
1869 select SYSTEM_TRUSTED_KEYRING
1871 Enable bzImage signature verification support.
1874 bool "kernel crash dumps"
1875 depends on X86_64 || (X86_32 && HIGHMEM)
1877 Generate crash dump after being started by kexec.
1878 This should be normally only set in special crash dump kernels
1879 which are loaded in the main kernel with kexec-tools into
1880 a specially reserved region and then later executed after
1881 a crash by kdump/kexec. The crash dump kernel must be compiled
1882 to a memory address not used by the main kernel or BIOS using
1883 PHYSICAL_START, or it must be built as a relocatable image
1884 (CONFIG_RELOCATABLE=y).
1885 For more details see Documentation/kdump/kdump.txt
1889 depends on KEXEC && HIBERNATION
1891 Jump between original kernel and kexeced kernel and invoke
1892 code in physical address mode via KEXEC
1894 config PHYSICAL_START
1895 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1898 This gives the physical address where the kernel is loaded.
1900 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1901 bzImage will decompress itself to above physical address and
1902 run from there. Otherwise, bzImage will run from the address where
1903 it has been loaded by the boot loader and will ignore above physical
1906 In normal kdump cases one does not have to set/change this option
1907 as now bzImage can be compiled as a completely relocatable image
1908 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1909 address. This option is mainly useful for the folks who don't want
1910 to use a bzImage for capturing the crash dump and want to use a
1911 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1912 to be specifically compiled to run from a specific memory area
1913 (normally a reserved region) and this option comes handy.
1915 So if you are using bzImage for capturing the crash dump,
1916 leave the value here unchanged to 0x1000000 and set
1917 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1918 for capturing the crash dump change this value to start of
1919 the reserved region. In other words, it can be set based on
1920 the "X" value as specified in the "crashkernel=YM@XM"
1921 command line boot parameter passed to the panic-ed
1922 kernel. Please take a look at Documentation/kdump/kdump.txt
1923 for more details about crash dumps.
1925 Usage of bzImage for capturing the crash dump is recommended as
1926 one does not have to build two kernels. Same kernel can be used
1927 as production kernel and capture kernel. Above option should have
1928 gone away after relocatable bzImage support is introduced. But it
1929 is present because there are users out there who continue to use
1930 vmlinux for dump capture. This option should go away down the
1933 Don't change this unless you know what you are doing.
1936 bool "Build a relocatable kernel"
1939 This builds a kernel image that retains relocation information
1940 so it can be loaded someplace besides the default 1MB.
1941 The relocations tend to make the kernel binary about 10% larger,
1942 but are discarded at runtime.
1944 One use is for the kexec on panic case where the recovery kernel
1945 must live at a different physical address than the primary
1948 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1949 it has been loaded at and the compile time physical address
1950 (CONFIG_PHYSICAL_START) is used as the minimum location.
1952 config RANDOMIZE_BASE
1953 bool "Randomize the address of the kernel image"
1954 depends on RELOCATABLE
1957 Randomizes the physical and virtual address at which the
1958 kernel image is decompressed, as a security feature that
1959 deters exploit attempts relying on knowledge of the location
1960 of kernel internals.
1962 Entropy is generated using the RDRAND instruction if it is
1963 supported. If RDTSC is supported, it is used as well. If
1964 neither RDRAND nor RDTSC are supported, then randomness is
1965 read from the i8254 timer.
1967 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1968 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1969 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1970 minimum of 2MiB, only 10 bits of entropy is theoretically
1971 possible. At best, due to page table layouts, 64-bit can use
1972 9 bits of entropy and 32-bit uses 8 bits.
1976 config RANDOMIZE_BASE_MAX_OFFSET
1977 hex "Maximum kASLR offset allowed" if EXPERT
1978 depends on RANDOMIZE_BASE
1979 range 0x0 0x20000000 if X86_32
1980 default "0x20000000" if X86_32
1981 range 0x0 0x40000000 if X86_64
1982 default "0x40000000" if X86_64
1984 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1985 memory is used to determine the maximal offset in bytes that will
1986 be applied to the kernel when kernel Address Space Layout
1987 Randomization (kASLR) is active. This must be a multiple of
1990 On 32-bit this is limited to 512MiB by page table layouts. The
1993 On 64-bit this is limited by how the kernel fixmap page table is
1994 positioned, so this cannot be larger than 1GiB currently. Without
1995 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1996 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1997 modules area will shrink to compensate, up to the current maximum
1998 1GiB to 1GiB split. The default is 1GiB.
2000 If unsure, leave at the default value.
2002 # Relocation on x86 needs some additional build support
2003 config X86_NEED_RELOCS
2005 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2007 config PHYSICAL_ALIGN
2008 hex "Alignment value to which kernel should be aligned"
2010 range 0x2000 0x1000000 if X86_32
2011 range 0x200000 0x1000000 if X86_64
2013 This value puts the alignment restrictions on physical address
2014 where kernel is loaded and run from. Kernel is compiled for an
2015 address which meets above alignment restriction.
2017 If bootloader loads the kernel at a non-aligned address and
2018 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2019 address aligned to above value and run from there.
2021 If bootloader loads the kernel at a non-aligned address and
2022 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2023 load address and decompress itself to the address it has been
2024 compiled for and run from there. The address for which kernel is
2025 compiled already meets above alignment restrictions. Hence the
2026 end result is that kernel runs from a physical address meeting
2027 above alignment restrictions.
2029 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2030 this value must be a multiple of 0x200000.
2032 Don't change this unless you know what you are doing.
2038 config BOOTPARAM_HOTPLUG_CPU0
2039 bool "Set default setting of cpu0_hotpluggable"
2041 depends on HOTPLUG_CPU
2043 Set whether default state of cpu0_hotpluggable is on or off.
2045 Say Y here to enable CPU0 hotplug by default. If this switch
2046 is turned on, there is no need to give cpu0_hotplug kernel
2047 parameter and the CPU0 hotplug feature is enabled by default.
2049 Please note: there are two known CPU0 dependencies if you want
2050 to enable the CPU0 hotplug feature either by this switch or by
2051 cpu0_hotplug kernel parameter.
2053 First, resume from hibernate or suspend always starts from CPU0.
2054 So hibernate and suspend are prevented if CPU0 is offline.
2056 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2057 offline if any interrupt can not migrate out of CPU0. There may
2058 be other CPU0 dependencies.
2060 Please make sure the dependencies are under your control before
2061 you enable this feature.
2063 Say N if you don't want to enable CPU0 hotplug feature by default.
2064 You still can enable the CPU0 hotplug feature at boot by kernel
2065 parameter cpu0_hotplug.
2067 config DEBUG_HOTPLUG_CPU0
2069 prompt "Debug CPU0 hotplug"
2070 depends on HOTPLUG_CPU
2072 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2073 soon as possible and boots up userspace with CPU0 offlined. User
2074 can online CPU0 back after boot time.
2076 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2077 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2078 compilation or giving cpu0_hotplug kernel parameter at boot.
2084 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2085 depends on X86_32 || IA32_EMULATION
2087 Certain buggy versions of glibc will crash if they are
2088 presented with a 32-bit vDSO that is not mapped at the address
2089 indicated in its segment table.
2091 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2092 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2093 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2094 the only released version with the bug, but OpenSUSE 9
2095 contains a buggy "glibc 2.3.2".
2097 The symptom of the bug is that everything crashes on startup, saying:
2098 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2100 Saying Y here changes the default value of the vdso32 boot
2101 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2102 This works around the glibc bug but hurts performance.
2104 If unsure, say N: if you are compiling your own kernel, you
2105 are unlikely to be using a buggy version of glibc.
2108 prompt "vsyscall table for legacy applications"
2110 default LEGACY_VSYSCALL_EMULATE
2112 Legacy user code that does not know how to find the vDSO expects
2113 to be able to issue three syscalls by calling fixed addresses in
2114 kernel space. Since this location is not randomized with ASLR,
2115 it can be used to assist security vulnerability exploitation.
2117 This setting can be changed at boot time via the kernel command
2118 line parameter vsyscall=[native|emulate|none].
2120 On a system with recent enough glibc (2.14 or newer) and no
2121 static binaries, you can say None without a performance penalty
2122 to improve security.
2124 If unsure, select "Emulate".
2126 config LEGACY_VSYSCALL_NATIVE
2129 Actual executable code is located in the fixed vsyscall
2130 address mapping, implementing time() efficiently. Since
2131 this makes the mapping executable, it can be used during
2132 security vulnerability exploitation (traditionally as
2133 ROP gadgets). This configuration is not recommended.
2135 config LEGACY_VSYSCALL_EMULATE
2138 The kernel traps and emulates calls into the fixed
2139 vsyscall address mapping. This makes the mapping
2140 non-executable, but it still contains known contents,
2141 which could be used in certain rare security vulnerability
2142 exploits. This configuration is recommended when userspace
2143 still uses the vsyscall area.
2145 config LEGACY_VSYSCALL_NONE
2148 There will be no vsyscall mapping at all. This will
2149 eliminate any risk of ASLR bypass due to the vsyscall
2150 fixed address mapping. Attempts to use the vsyscalls
2151 will be reported to dmesg, so that either old or
2152 malicious userspace programs can be identified.
2157 bool "Built-in kernel command line"
2159 Allow for specifying boot arguments to the kernel at
2160 build time. On some systems (e.g. embedded ones), it is
2161 necessary or convenient to provide some or all of the
2162 kernel boot arguments with the kernel itself (that is,
2163 to not rely on the boot loader to provide them.)
2165 To compile command line arguments into the kernel,
2166 set this option to 'Y', then fill in the
2167 boot arguments in CONFIG_CMDLINE.
2169 Systems with fully functional boot loaders (i.e. non-embedded)
2170 should leave this option set to 'N'.
2173 string "Built-in kernel command string"
2174 depends on CMDLINE_BOOL
2177 Enter arguments here that should be compiled into the kernel
2178 image and used at boot time. If the boot loader provides a
2179 command line at boot time, it is appended to this string to
2180 form the full kernel command line, when the system boots.
2182 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2183 change this behavior.
2185 In most cases, the command line (whether built-in or provided
2186 by the boot loader) should specify the device for the root
2189 config CMDLINE_OVERRIDE
2190 bool "Built-in command line overrides boot loader arguments"
2191 depends on CMDLINE_BOOL
2193 Set this option to 'Y' to have the kernel ignore the boot loader
2194 command line, and use ONLY the built-in command line.
2196 This is used to work around broken boot loaders. This should
2197 be set to 'N' under normal conditions.
2199 config MODIFY_LDT_SYSCALL
2200 bool "Enable the LDT (local descriptor table)" if EXPERT
2203 Linux can allow user programs to install a per-process x86
2204 Local Descriptor Table (LDT) using the modify_ldt(2) system
2205 call. This is required to run 16-bit or segmented code such as
2206 DOSEMU or some Wine programs. It is also used by some very old
2207 threading libraries.
2209 Enabling this feature adds a small amount of overhead to
2210 context switches and increases the low-level kernel attack
2211 surface. Disabling it removes the modify_ldt(2) system call.
2213 Saying 'N' here may make sense for embedded or server kernels.
2215 source "kernel/livepatch/Kconfig"
2219 config ARCH_ENABLE_MEMORY_HOTPLUG
2221 depends on X86_64 || (X86_32 && HIGHMEM)
2223 config ARCH_ENABLE_MEMORY_HOTREMOVE
2225 depends on MEMORY_HOTPLUG
2227 config USE_PERCPU_NUMA_NODE_ID
2231 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2233 depends on X86_64 || X86_PAE
2235 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2237 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2239 menu "Power management and ACPI options"
2241 config ARCH_HIBERNATION_HEADER
2243 depends on X86_64 && HIBERNATION
2245 source "kernel/power/Kconfig"
2247 source "drivers/acpi/Kconfig"
2249 source "drivers/sfi/Kconfig"
2256 tristate "APM (Advanced Power Management) BIOS support"
2257 depends on X86_32 && PM_SLEEP
2259 APM is a BIOS specification for saving power using several different
2260 techniques. This is mostly useful for battery powered laptops with
2261 APM compliant BIOSes. If you say Y here, the system time will be
2262 reset after a RESUME operation, the /proc/apm device will provide
2263 battery status information, and user-space programs will receive
2264 notification of APM "events" (e.g. battery status change).
2266 If you select "Y" here, you can disable actual use of the APM
2267 BIOS by passing the "apm=off" option to the kernel at boot time.
2269 Note that the APM support is almost completely disabled for
2270 machines with more than one CPU.
2272 In order to use APM, you will need supporting software. For location
2273 and more information, read <file:Documentation/power/apm-acpi.txt>
2274 and the Battery Powered Linux mini-HOWTO, available from
2275 <http://www.tldp.org/docs.html#howto>.
2277 This driver does not spin down disk drives (see the hdparm(8)
2278 manpage ("man 8 hdparm") for that), and it doesn't turn off
2279 VESA-compliant "green" monitors.
2281 This driver does not support the TI 4000M TravelMate and the ACER
2282 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2283 desktop machines also don't have compliant BIOSes, and this driver
2284 may cause those machines to panic during the boot phase.
2286 Generally, if you don't have a battery in your machine, there isn't
2287 much point in using this driver and you should say N. If you get
2288 random kernel OOPSes or reboots that don't seem to be related to
2289 anything, try disabling/enabling this option (or disabling/enabling
2292 Some other things you should try when experiencing seemingly random,
2295 1) make sure that you have enough swap space and that it is
2297 2) pass the "no-hlt" option to the kernel
2298 3) switch on floating point emulation in the kernel and pass
2299 the "no387" option to the kernel
2300 4) pass the "floppy=nodma" option to the kernel
2301 5) pass the "mem=4M" option to the kernel (thereby disabling
2302 all but the first 4 MB of RAM)
2303 6) make sure that the CPU is not over clocked.
2304 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2305 8) disable the cache from your BIOS settings
2306 9) install a fan for the video card or exchange video RAM
2307 10) install a better fan for the CPU
2308 11) exchange RAM chips
2309 12) exchange the motherboard.
2311 To compile this driver as a module, choose M here: the
2312 module will be called apm.
2316 config APM_IGNORE_USER_SUSPEND
2317 bool "Ignore USER SUSPEND"
2319 This option will ignore USER SUSPEND requests. On machines with a
2320 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2321 series notebooks, it is necessary to say Y because of a BIOS bug.
2323 config APM_DO_ENABLE
2324 bool "Enable PM at boot time"
2326 Enable APM features at boot time. From page 36 of the APM BIOS
2327 specification: "When disabled, the APM BIOS does not automatically
2328 power manage devices, enter the Standby State, enter the Suspend
2329 State, or take power saving steps in response to CPU Idle calls."
2330 This driver will make CPU Idle calls when Linux is idle (unless this
2331 feature is turned off -- see "Do CPU IDLE calls", below). This
2332 should always save battery power, but more complicated APM features
2333 will be dependent on your BIOS implementation. You may need to turn
2334 this option off if your computer hangs at boot time when using APM
2335 support, or if it beeps continuously instead of suspending. Turn
2336 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2337 T400CDT. This is off by default since most machines do fine without
2342 bool "Make CPU Idle calls when idle"
2344 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2345 On some machines, this can activate improved power savings, such as
2346 a slowed CPU clock rate, when the machine is idle. These idle calls
2347 are made after the idle loop has run for some length of time (e.g.,
2348 333 mS). On some machines, this will cause a hang at boot time or
2349 whenever the CPU becomes idle. (On machines with more than one CPU,
2350 this option does nothing.)
2352 config APM_DISPLAY_BLANK
2353 bool "Enable console blanking using APM"
2355 Enable console blanking using the APM. Some laptops can use this to
2356 turn off the LCD backlight when the screen blanker of the Linux
2357 virtual console blanks the screen. Note that this is only used by
2358 the virtual console screen blanker, and won't turn off the backlight
2359 when using the X Window system. This also doesn't have anything to
2360 do with your VESA-compliant power-saving monitor. Further, this
2361 option doesn't work for all laptops -- it might not turn off your
2362 backlight at all, or it might print a lot of errors to the console,
2363 especially if you are using gpm.
2365 config APM_ALLOW_INTS
2366 bool "Allow interrupts during APM BIOS calls"
2368 Normally we disable external interrupts while we are making calls to
2369 the APM BIOS as a measure to lessen the effects of a badly behaving
2370 BIOS implementation. The BIOS should reenable interrupts if it
2371 needs to. Unfortunately, some BIOSes do not -- especially those in
2372 many of the newer IBM Thinkpads. If you experience hangs when you
2373 suspend, try setting this to Y. Otherwise, say N.
2377 source "drivers/cpufreq/Kconfig"
2379 source "drivers/cpuidle/Kconfig"
2381 source "drivers/idle/Kconfig"
2386 menu "Bus options (PCI etc.)"
2392 Find out whether you have a PCI motherboard. PCI is the name of a
2393 bus system, i.e. the way the CPU talks to the other stuff inside
2394 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2395 VESA. If you have PCI, say Y, otherwise N.
2398 prompt "PCI access mode"
2399 depends on X86_32 && PCI
2402 On PCI systems, the BIOS can be used to detect the PCI devices and
2403 determine their configuration. However, some old PCI motherboards
2404 have BIOS bugs and may crash if this is done. Also, some embedded
2405 PCI-based systems don't have any BIOS at all. Linux can also try to
2406 detect the PCI hardware directly without using the BIOS.
2408 With this option, you can specify how Linux should detect the
2409 PCI devices. If you choose "BIOS", the BIOS will be used,
2410 if you choose "Direct", the BIOS won't be used, and if you
2411 choose "MMConfig", then PCI Express MMCONFIG will be used.
2412 If you choose "Any", the kernel will try MMCONFIG, then the
2413 direct access method and falls back to the BIOS if that doesn't
2414 work. If unsure, go with the default, which is "Any".
2419 config PCI_GOMMCONFIG
2436 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2438 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2441 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2445 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2449 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2453 depends on PCI && XEN
2461 bool "Support mmconfig PCI config space access"
2462 depends on X86_64 && PCI && ACPI
2464 config PCI_CNB20LE_QUIRK
2465 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2468 Read the PCI windows out of the CNB20LE host bridge. This allows
2469 PCI hotplug to work on systems with the CNB20LE chipset which do
2472 There's no public spec for this chipset, and this functionality
2473 is known to be incomplete.
2475 You should say N unless you know you need this.
2477 source "drivers/pci/pcie/Kconfig"
2479 source "drivers/pci/Kconfig"
2481 # x86_64 have no ISA slots, but can have ISA-style DMA.
2483 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2486 Enables ISA-style DMA support for devices requiring such controllers.
2494 Find out whether you have ISA slots on your motherboard. ISA is the
2495 name of a bus system, i.e. the way the CPU talks to the other stuff
2496 inside your box. Other bus systems are PCI, EISA, MicroChannel
2497 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2498 newer boards don't support it. If you have ISA, say Y, otherwise N.
2504 The Extended Industry Standard Architecture (EISA) bus was
2505 developed as an open alternative to the IBM MicroChannel bus.
2507 The EISA bus provided some of the features of the IBM MicroChannel
2508 bus while maintaining backward compatibility with cards made for
2509 the older ISA bus. The EISA bus saw limited use between 1988 and
2510 1995 when it was made obsolete by the PCI bus.
2512 Say Y here if you are building a kernel for an EISA-based machine.
2516 source "drivers/eisa/Kconfig"
2519 tristate "NatSemi SCx200 support"
2521 This provides basic support for National Semiconductor's
2522 (now AMD's) Geode processors. The driver probes for the
2523 PCI-IDs of several on-chip devices, so its a good dependency
2524 for other scx200_* drivers.
2526 If compiled as a module, the driver is named scx200.
2528 config SCx200HR_TIMER
2529 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2533 This driver provides a clocksource built upon the on-chip
2534 27MHz high-resolution timer. Its also a workaround for
2535 NSC Geode SC-1100's buggy TSC, which loses time when the
2536 processor goes idle (as is done by the scheduler). The
2537 other workaround is idle=poll boot option.
2540 bool "One Laptop Per Child support"
2547 Add support for detecting the unique features of the OLPC
2551 bool "OLPC XO-1 Power Management"
2552 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2554 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2557 bool "OLPC XO-1 Real Time Clock"
2558 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2560 Add support for the XO-1 real time clock, which can be used as a
2561 programmable wakeup source.
2564 bool "OLPC XO-1 SCI extras"
2565 depends on OLPC && OLPC_XO1_PM
2571 Add support for SCI-based features of the OLPC XO-1 laptop:
2572 - EC-driven system wakeups
2576 - AC adapter status updates
2577 - Battery status updates
2579 config OLPC_XO15_SCI
2580 bool "OLPC XO-1.5 SCI extras"
2581 depends on OLPC && ACPI
2584 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2585 - EC-driven system wakeups
2586 - AC adapter status updates
2587 - Battery status updates
2590 bool "PCEngines ALIX System Support (LED setup)"
2593 This option enables system support for the PCEngines ALIX.
2594 At present this just sets up LEDs for GPIO control on
2595 ALIX2/3/6 boards. However, other system specific setup should
2598 Note: You must still enable the drivers for GPIO and LED support
2599 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2601 Note: You have to set alix.force=1 for boards with Award BIOS.
2604 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2607 This option enables system support for the Soekris Engineering net5501.
2610 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2614 This option enables system support for the Traverse Technologies GEOS.
2617 bool "Technologic Systems TS-5500 platform support"
2619 select CHECK_SIGNATURE
2623 This option enables system support for the Technologic Systems TS-5500.
2629 depends on CPU_SUP_AMD && PCI
2631 source "drivers/pcmcia/Kconfig"
2633 source "drivers/pci/hotplug/Kconfig"
2636 tristate "RapidIO support"
2640 If enabled this option will include drivers and the core
2641 infrastructure code to support RapidIO interconnect devices.
2643 source "drivers/rapidio/Kconfig"
2646 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2648 Firmwares often provide initial graphics framebuffers so the BIOS,
2649 bootloader or kernel can show basic video-output during boot for
2650 user-guidance and debugging. Historically, x86 used the VESA BIOS
2651 Extensions and EFI-framebuffers for this, which are mostly limited
2653 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2654 framebuffers so the new generic system-framebuffer drivers can be
2655 used on x86. If the framebuffer is not compatible with the generic
2656 modes, it is adverticed as fallback platform framebuffer so legacy
2657 drivers like efifb, vesafb and uvesafb can pick it up.
2658 If this option is not selected, all system framebuffers are always
2659 marked as fallback platform framebuffers as usual.
2661 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2662 not be able to pick up generic system framebuffers if this option
2663 is selected. You are highly encouraged to enable simplefb as
2664 replacement if you select this option. simplefb can correctly deal
2665 with generic system framebuffers. But you should still keep vesafb
2666 and others enabled as fallback if a system framebuffer is
2667 incompatible with simplefb.
2674 menu "Executable file formats / Emulations"
2676 source "fs/Kconfig.binfmt"
2678 config IA32_EMULATION
2679 bool "IA32 Emulation"
2682 select COMPAT_BINFMT_ELF
2683 select ARCH_WANT_OLD_COMPAT_IPC
2685 Include code to run legacy 32-bit programs under a
2686 64-bit kernel. You should likely turn this on, unless you're
2687 100% sure that you don't have any 32-bit programs left.
2690 tristate "IA32 a.out support"
2691 depends on IA32_EMULATION
2693 Support old a.out binaries in the 32bit emulation.
2696 bool "x32 ABI for 64-bit mode"
2699 Include code to run binaries for the x32 native 32-bit ABI
2700 for 64-bit processors. An x32 process gets access to the
2701 full 64-bit register file and wide data path while leaving
2702 pointers at 32 bits for smaller memory footprint.
2704 You will need a recent binutils (2.22 or later) with
2705 elf32_x86_64 support enabled to compile a kernel with this
2710 depends on IA32_EMULATION || X86_X32
2713 config COMPAT_FOR_U64_ALIGNMENT
2716 config SYSVIPC_COMPAT
2724 config HAVE_ATOMIC_IOMAP
2728 config X86_DEV_DMA_OPS
2730 depends on X86_64 || STA2X11
2732 config X86_DMA_REMAP
2740 source "net/Kconfig"
2742 source "drivers/Kconfig"
2744 source "drivers/firmware/Kconfig"
2748 source "arch/x86/Kconfig.debug"
2750 source "security/Kconfig"
2752 source "crypto/Kconfig"
2754 source "arch/x86/kvm/Kconfig"
2756 source "lib/Kconfig"