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_DEVMEM_IS_ALLOWED
27 select ARCH_HAS_ELF_RANDOMIZE
28 select ARCH_HAS_FAST_MULTIPLIER
29 select ARCH_HAS_GCOV_PROFILE_ALL
30 select ARCH_HAS_GIGANTIC_PAGE if X86_64
31 select ARCH_HAS_KCOV if X86_64
32 select ARCH_HAS_PMEM_API if X86_64
33 select ARCH_HAS_MMIO_FLUSH
34 select ARCH_HAS_SG_CHAIN
35 select ARCH_HAS_UBSAN_SANITIZE_ALL
36 select ARCH_HAVE_NMI_SAFE_CMPXCHG
37 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
38 select ARCH_MIGHT_HAVE_PC_PARPORT
39 select ARCH_MIGHT_HAVE_PC_SERIO
40 select ARCH_SUPPORTS_ATOMIC_RMW
41 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
42 select ARCH_SUPPORTS_INT128 if X86_64
43 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
44 select ARCH_USE_BUILTIN_BSWAP
45 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
46 select ARCH_USE_QUEUED_RWLOCKS
47 select ARCH_USE_QUEUED_SPINLOCKS
48 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
49 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
50 select ARCH_WANT_FRAME_POINTERS
51 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
52 select BUILDTIME_EXTABLE_SORT
54 select CLKSRC_I8253 if X86_32
55 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
56 select CLOCKSOURCE_WATCHDOG
57 select CLONE_BACKWARDS if X86_32
58 select COMPAT_OLD_SIGACTION if IA32_EMULATION
59 select DCACHE_WORD_ACCESS
60 select EDAC_ATOMIC_SCRUB
62 select GENERIC_CLOCKEVENTS
63 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
64 select GENERIC_CLOCKEVENTS_MIN_ADJUST
65 select GENERIC_CMOS_UPDATE
66 select GENERIC_CPU_AUTOPROBE
67 select GENERIC_EARLY_IOREMAP
68 select GENERIC_FIND_FIRST_BIT
70 select GENERIC_IRQ_PROBE
71 select GENERIC_IRQ_SHOW
72 select GENERIC_PENDING_IRQ if SMP
73 select GENERIC_SMP_IDLE_THREAD
74 select GENERIC_STRNCPY_FROM_USER
75 select GENERIC_STRNLEN_USER
76 select GENERIC_TIME_VSYSCALL
77 select HAVE_ACPI_APEI if ACPI
78 select HAVE_ACPI_APEI_NMI if ACPI
79 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
80 select HAVE_AOUT if X86_32
81 select HAVE_ARCH_AUDITSYSCALL
82 select HAVE_ARCH_HARDENED_USERCOPY
83 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
84 select HAVE_ARCH_JUMP_LABEL
85 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
87 select HAVE_ARCH_KMEMCHECK
88 select HAVE_ARCH_MMAP_RND_BITS if MMU
89 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
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_ARCH_VMAP_STACK 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_TRACER
114 select HAVE_FUNCTION_TRACER
115 select HAVE_GCC_PLUGINS
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
138 select HAVE_OPTPROBES
139 select HAVE_PCSPKR_PLATFORM
140 select HAVE_PERF_EVENTS
141 select HAVE_PERF_EVENTS_NMI
142 select HAVE_PERF_REGS
143 select HAVE_PERF_USER_STACK_DUMP
144 select HAVE_REGS_AND_STACK_ACCESS_API
145 select HAVE_SYSCALL_TRACEPOINTS
146 select HAVE_UID16 if X86_32 || IA32_EMULATION
147 select HAVE_UNSTABLE_SCHED_CLOCK
148 select HAVE_USER_RETURN_NOTIFIER
149 select IRQ_FORCED_THREADING
150 select MODULES_USE_ELF_RELA if X86_64
151 select MODULES_USE_ELF_REL if X86_32
152 select OLD_SIGACTION if X86_32
153 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
156 select RTC_MC146818_LIB
159 select SYSCTL_EXCEPTION_TRACE
160 select THREAD_INFO_IN_TASK
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.
554 tristate "Mellanox Technologies platform support"
556 depends on X86_EXTENDED_PLATFORM
558 This option enables system support for the Mellanox Technologies
561 Say Y here if you are building a kernel for Mellanox system.
565 config X86_INTEL_LPSS
566 bool "Intel Low Power Subsystem Support"
567 depends on X86 && ACPI
572 Select to build support for Intel Low Power Subsystem such as
573 found on Intel Lynxpoint PCH. Selecting this option enables
574 things like clock tree (common clock framework) and pincontrol
575 which are needed by the LPSS peripheral drivers.
577 config X86_AMD_PLATFORM_DEVICE
578 bool "AMD ACPI2Platform devices support"
583 Select to interpret AMD specific ACPI device to platform device
584 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
585 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
586 implemented under PINCTRL subsystem.
589 tristate "Intel SoC IOSF Sideband support for SoC platforms"
592 This option enables sideband register access support for Intel SoC
593 platforms. On these platforms the IOSF sideband is used in lieu of
594 MSR's for some register accesses, mostly but not limited to thermal
595 and power. Drivers may query the availability of this device to
596 determine if they need the sideband in order to work on these
597 platforms. The sideband is available on the following SoC products.
598 This list is not meant to be exclusive.
603 You should say Y if you are running a kernel on one of these SoC's.
605 config IOSF_MBI_DEBUG
606 bool "Enable IOSF sideband access through debugfs"
607 depends on IOSF_MBI && DEBUG_FS
609 Select this option to expose the IOSF sideband access registers (MCR,
610 MDR, MCRX) through debugfs to write and read register information from
611 different units on the SoC. This is most useful for obtaining device
612 state information for debug and analysis. As this is a general access
613 mechanism, users of this option would have specific knowledge of the
614 device they want to access.
616 If you don't require the option or are in doubt, say N.
619 bool "RDC R-321x SoC"
621 depends on X86_EXTENDED_PLATFORM
623 select X86_REBOOTFIXUPS
625 This option is needed for RDC R-321x system-on-chip, also known
627 If you don't have one of these chips, you should say N here.
629 config X86_32_NON_STANDARD
630 bool "Support non-standard 32-bit SMP architectures"
631 depends on X86_32 && SMP
632 depends on X86_EXTENDED_PLATFORM
634 This option compiles in the bigsmp and STA2X11 default
635 subarchitectures. It is intended for a generic binary
636 kernel. If you select them all, kernel will probe it one by
637 one and will fallback to default.
639 # Alphabetically sorted list of Non standard 32 bit platforms
641 config X86_SUPPORTS_MEMORY_FAILURE
643 # MCE code calls memory_failure():
645 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
646 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
647 depends on X86_64 || !SPARSEMEM
648 select ARCH_SUPPORTS_MEMORY_FAILURE
651 bool "STA2X11 Companion Chip Support"
652 depends on X86_32_NON_STANDARD && PCI
653 select X86_DEV_DMA_OPS
660 This adds support for boards based on the STA2X11 IO-Hub,
661 a.k.a. "ConneXt". The chip is used in place of the standard
662 PC chipset, so all "standard" peripherals are missing. If this
663 option is selected the kernel will still be able to boot on
664 standard PC machines.
667 tristate "Eurobraille/Iris poweroff module"
670 The Iris machines from EuroBraille do not have APM or ACPI support
671 to shut themselves down properly. A special I/O sequence is
672 needed to do so, which is what this module does at
675 This is only for Iris machines from EuroBraille.
679 config SCHED_OMIT_FRAME_POINTER
681 prompt "Single-depth WCHAN output"
684 Calculate simpler /proc/<PID>/wchan values. If this option
685 is disabled then wchan values will recurse back to the
686 caller function. This provides more accurate wchan values,
687 at the expense of slightly more scheduling overhead.
689 If in doubt, say "Y".
691 menuconfig HYPERVISOR_GUEST
692 bool "Linux guest support"
694 Say Y here to enable options for running Linux under various hyper-
695 visors. This option enables basic hypervisor detection and platform
698 If you say N, all options in this submenu will be skipped and
699 disabled, and Linux guest support won't be built in.
704 bool "Enable paravirtualization code"
706 This changes the kernel so it can modify itself when it is run
707 under a hypervisor, potentially improving performance significantly
708 over full virtualization. However, when run without a hypervisor
709 the kernel is theoretically slower and slightly larger.
711 config PARAVIRT_DEBUG
712 bool "paravirt-ops debugging"
713 depends on PARAVIRT && DEBUG_KERNEL
715 Enable to debug paravirt_ops internals. Specifically, BUG if
716 a paravirt_op is missing when it is called.
718 config PARAVIRT_SPINLOCKS
719 bool "Paravirtualization layer for spinlocks"
720 depends on PARAVIRT && SMP
722 Paravirtualized spinlocks allow a pvops backend to replace the
723 spinlock implementation with something virtualization-friendly
724 (for example, block the virtual CPU rather than spinning).
726 It has a minimal impact on native kernels and gives a nice performance
727 benefit on paravirtualized KVM / Xen kernels.
729 If you are unsure how to answer this question, answer Y.
731 config QUEUED_LOCK_STAT
732 bool "Paravirt queued spinlock statistics"
733 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
735 Enable the collection of statistical data on the slowpath
736 behavior of paravirtualized queued spinlocks and report
739 source "arch/x86/xen/Kconfig"
742 bool "KVM Guest support (including kvmclock)"
744 select PARAVIRT_CLOCK
747 This option enables various optimizations for running under the KVM
748 hypervisor. It includes a paravirtualized clock, so that instead
749 of relying on a PIT (or probably other) emulation by the
750 underlying device model, the host provides the guest with
751 timing infrastructure such as time of day, and system time
754 bool "Enable debug information for KVM Guests in debugfs"
755 depends on KVM_GUEST && DEBUG_FS
758 This option enables collection of various statistics for KVM guest.
759 Statistics are displayed in debugfs filesystem. Enabling this option
760 may incur significant overhead.
762 source "arch/x86/lguest/Kconfig"
764 config PARAVIRT_TIME_ACCOUNTING
765 bool "Paravirtual steal time accounting"
769 Select this option to enable fine granularity task steal time
770 accounting. Time spent executing other tasks in parallel with
771 the current vCPU is discounted from the vCPU power. To account for
772 that, there can be a small performance impact.
774 If in doubt, say N here.
776 config PARAVIRT_CLOCK
779 endif #HYPERVISOR_GUEST
784 source "arch/x86/Kconfig.cpu"
788 prompt "HPET Timer Support" if X86_32
790 Use the IA-PC HPET (High Precision Event Timer) to manage
791 time in preference to the PIT and RTC, if a HPET is
793 HPET is the next generation timer replacing legacy 8254s.
794 The HPET provides a stable time base on SMP
795 systems, unlike the TSC, but it is more expensive to access,
796 as it is off-chip. The interface used is documented
797 in the HPET spec, revision 1.
799 You can safely choose Y here. However, HPET will only be
800 activated if the platform and the BIOS support this feature.
801 Otherwise the 8254 will be used for timing services.
803 Choose N to continue using the legacy 8254 timer.
805 config HPET_EMULATE_RTC
807 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
810 def_bool y if X86_INTEL_MID
811 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
813 depends on X86_INTEL_MID && SFI
815 APB timer is the replacement for 8254, HPET on X86 MID platforms.
816 The APBT provides a stable time base on SMP
817 systems, unlike the TSC, but it is more expensive to access,
818 as it is off-chip. APB timers are always running regardless of CPU
819 C states, they are used as per CPU clockevent device when possible.
821 # Mark as expert because too many people got it wrong.
822 # The code disables itself when not needed.
825 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
826 bool "Enable DMI scanning" if EXPERT
828 Enabled scanning of DMI to identify machine quirks. Say Y
829 here unless you have verified that your setup is not
830 affected by entries in the DMI blacklist. Required by PNP
834 bool "Old AMD GART IOMMU support"
836 depends on X86_64 && PCI && AMD_NB
838 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
839 GART based hardware IOMMUs.
841 The GART supports full DMA access for devices with 32-bit access
842 limitations, on systems with more than 3 GB. This is usually needed
843 for USB, sound, many IDE/SATA chipsets and some other devices.
845 Newer systems typically have a modern AMD IOMMU, supported via
846 the CONFIG_AMD_IOMMU=y config option.
848 In normal configurations this driver is only active when needed:
849 there's more than 3 GB of memory and the system contains a
850 32-bit limited device.
855 bool "IBM Calgary IOMMU support"
857 depends on X86_64 && PCI
859 Support for hardware IOMMUs in IBM's xSeries x366 and x460
860 systems. Needed to run systems with more than 3GB of memory
861 properly with 32-bit PCI devices that do not support DAC
862 (Double Address Cycle). Calgary also supports bus level
863 isolation, where all DMAs pass through the IOMMU. This
864 prevents them from going anywhere except their intended
865 destination. This catches hard-to-find kernel bugs and
866 mis-behaving drivers and devices that do not use the DMA-API
867 properly to set up their DMA buffers. The IOMMU can be
868 turned off at boot time with the iommu=off parameter.
869 Normally the kernel will make the right choice by itself.
872 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
874 prompt "Should Calgary be enabled by default?"
875 depends on CALGARY_IOMMU
877 Should Calgary be enabled by default? if you choose 'y', Calgary
878 will be used (if it exists). If you choose 'n', Calgary will not be
879 used even if it exists. If you choose 'n' and would like to use
880 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
883 # need this always selected by IOMMU for the VIA workaround
887 Support for software bounce buffers used on x86-64 systems
888 which don't have a hardware IOMMU. Using this PCI devices
889 which can only access 32-bits of memory can be used on systems
890 with more than 3 GB of memory.
895 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
898 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
899 depends on X86_64 && SMP && DEBUG_KERNEL
900 select CPUMASK_OFFSTACK
902 Enable maximum number of CPUS and NUMA Nodes for this architecture.
906 int "Maximum number of CPUs" if SMP && !MAXSMP
907 range 2 8 if SMP && X86_32 && !X86_BIGSMP
908 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
909 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
911 default "8192" if MAXSMP
912 default "32" if SMP && X86_BIGSMP
913 default "8" if SMP && X86_32
916 This allows you to specify the maximum number of CPUs which this
917 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
918 supported value is 8192, otherwise the maximum value is 512. The
919 minimum value which makes sense is 2.
921 This is purely to save memory - each supported CPU adds
922 approximately eight kilobytes to the kernel image.
925 bool "SMT (Hyperthreading) scheduler support"
928 SMT scheduler support improves the CPU scheduler's decision making
929 when dealing with Intel Pentium 4 chips with HyperThreading at a
930 cost of slightly increased overhead in some places. If unsure say
935 prompt "Multi-core scheduler support"
938 Multi-core scheduler support improves the CPU scheduler's decision
939 making when dealing with multi-core CPU chips at a cost of slightly
940 increased overhead in some places. If unsure say N here.
942 source "kernel/Kconfig.preempt"
946 depends on !SMP && X86_LOCAL_APIC
949 bool "Local APIC support on uniprocessors" if !PCI_MSI
951 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
953 A local APIC (Advanced Programmable Interrupt Controller) is an
954 integrated interrupt controller in the CPU. If you have a single-CPU
955 system which has a processor with a local APIC, you can say Y here to
956 enable and use it. If you say Y here even though your machine doesn't
957 have a local APIC, then the kernel will still run with no slowdown at
958 all. The local APIC supports CPU-generated self-interrupts (timer,
959 performance counters), and the NMI watchdog which detects hard
963 bool "IO-APIC support on uniprocessors"
964 depends on X86_UP_APIC
966 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
967 SMP-capable replacement for PC-style interrupt controllers. Most
968 SMP systems and many recent uniprocessor systems have one.
970 If you have a single-CPU system with an IO-APIC, you can say Y here
971 to use it. If you say Y here even though your machine doesn't have
972 an IO-APIC, then the kernel will still run with no slowdown at all.
974 config X86_LOCAL_APIC
976 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
977 select IRQ_DOMAIN_HIERARCHY
978 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
982 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
984 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
985 bool "Reroute for broken boot IRQs"
986 depends on X86_IO_APIC
988 This option enables a workaround that fixes a source of
989 spurious interrupts. This is recommended when threaded
990 interrupt handling is used on systems where the generation of
991 superfluous "boot interrupts" cannot be disabled.
993 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
994 entry in the chipset's IO-APIC is masked (as, e.g. the RT
995 kernel does during interrupt handling). On chipsets where this
996 boot IRQ generation cannot be disabled, this workaround keeps
997 the original IRQ line masked so that only the equivalent "boot
998 IRQ" is delivered to the CPUs. The workaround also tells the
999 kernel to set up the IRQ handler on the boot IRQ line. In this
1000 way only one interrupt is delivered to the kernel. Otherwise
1001 the spurious second interrupt may cause the kernel to bring
1002 down (vital) interrupt lines.
1004 Only affects "broken" chipsets. Interrupt sharing may be
1005 increased on these systems.
1008 bool "Machine Check / overheating reporting"
1009 select GENERIC_ALLOCATOR
1012 Machine Check support allows the processor to notify the
1013 kernel if it detects a problem (e.g. overheating, data corruption).
1014 The action the kernel takes depends on the severity of the problem,
1015 ranging from warning messages to halting the machine.
1017 config X86_MCE_INTEL
1019 prompt "Intel MCE features"
1020 depends on X86_MCE && X86_LOCAL_APIC
1022 Additional support for intel specific MCE features such as
1023 the thermal monitor.
1027 prompt "AMD MCE features"
1028 depends on X86_MCE && X86_LOCAL_APIC
1030 Additional support for AMD specific MCE features such as
1031 the DRAM Error Threshold.
1033 config X86_ANCIENT_MCE
1034 bool "Support for old Pentium 5 / WinChip machine checks"
1035 depends on X86_32 && X86_MCE
1037 Include support for machine check handling on old Pentium 5 or WinChip
1038 systems. These typically need to be enabled explicitly on the command
1041 config X86_MCE_THRESHOLD
1042 depends on X86_MCE_AMD || X86_MCE_INTEL
1045 config X86_MCE_INJECT
1047 tristate "Machine check injector support"
1049 Provide support for injecting machine checks for testing purposes.
1050 If you don't know what a machine check is and you don't do kernel
1051 QA it is safe to say n.
1053 config X86_THERMAL_VECTOR
1055 depends on X86_MCE_INTEL
1057 source "arch/x86/events/Kconfig"
1059 config X86_LEGACY_VM86
1060 bool "Legacy VM86 support"
1064 This option allows user programs to put the CPU into V8086
1065 mode, which is an 80286-era approximation of 16-bit real mode.
1067 Some very old versions of X and/or vbetool require this option
1068 for user mode setting. Similarly, DOSEMU will use it if
1069 available to accelerate real mode DOS programs. However, any
1070 recent version of DOSEMU, X, or vbetool should be fully
1071 functional even without kernel VM86 support, as they will all
1072 fall back to software emulation. Nevertheless, if you are using
1073 a 16-bit DOS program where 16-bit performance matters, vm86
1074 mode might be faster than emulation and you might want to
1077 Note that any app that works on a 64-bit kernel is unlikely to
1078 need this option, as 64-bit kernels don't, and can't, support
1079 V8086 mode. This option is also unrelated to 16-bit protected
1080 mode and is not needed to run most 16-bit programs under Wine.
1082 Enabling this option increases the complexity of the kernel
1083 and slows down exception handling a tiny bit.
1085 If unsure, say N here.
1089 default X86_LEGACY_VM86
1092 bool "Enable support for 16-bit segments" if EXPERT
1094 depends on MODIFY_LDT_SYSCALL
1096 This option is required by programs like Wine to run 16-bit
1097 protected mode legacy code on x86 processors. Disabling
1098 this option saves about 300 bytes on i386, or around 6K text
1099 plus 16K runtime memory on x86-64,
1103 depends on X86_16BIT && X86_32
1107 depends on X86_16BIT && X86_64
1109 config X86_VSYSCALL_EMULATION
1110 bool "Enable vsyscall emulation" if EXPERT
1114 This enables emulation of the legacy vsyscall page. Disabling
1115 it is roughly equivalent to booting with vsyscall=none, except
1116 that it will also disable the helpful warning if a program
1117 tries to use a vsyscall. With this option set to N, offending
1118 programs will just segfault, citing addresses of the form
1121 This option is required by many programs built before 2013, and
1122 care should be used even with newer programs if set to N.
1124 Disabling this option saves about 7K of kernel size and
1125 possibly 4K of additional runtime pagetable memory.
1128 tristate "Toshiba Laptop support"
1131 This adds a driver to safely access the System Management Mode of
1132 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1133 not work on models with a Phoenix BIOS. The System Management Mode
1134 is used to set the BIOS and power saving options on Toshiba portables.
1136 For information on utilities to make use of this driver see the
1137 Toshiba Linux utilities web site at:
1138 <http://www.buzzard.org.uk/toshiba/>.
1140 Say Y if you intend to run this kernel on a Toshiba portable.
1144 tristate "Dell i8k legacy laptop support"
1146 select SENSORS_DELL_SMM
1148 This option enables legacy /proc/i8k userspace interface in hwmon
1149 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1150 temperature and allows controlling fan speeds of Dell laptops via
1151 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1152 it reports also power and hotkey status. For fan speed control is
1153 needed userspace package i8kutils.
1155 Say Y if you intend to run this kernel on old Dell laptops or want to
1156 use userspace package i8kutils.
1159 config X86_REBOOTFIXUPS
1160 bool "Enable X86 board specific fixups for reboot"
1163 This enables chipset and/or board specific fixups to be done
1164 in order to get reboot to work correctly. This is only needed on
1165 some combinations of hardware and BIOS. The symptom, for which
1166 this config is intended, is when reboot ends with a stalled/hung
1169 Currently, the only fixup is for the Geode machines using
1170 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1172 Say Y if you want to enable the fixup. Currently, it's safe to
1173 enable this option even if you don't need it.
1177 bool "CPU microcode loading support"
1179 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1182 If you say Y here, you will be able to update the microcode on
1183 Intel and AMD processors. The Intel support is for the IA32 family,
1184 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1185 AMD support is for families 0x10 and later. You will obviously need
1186 the actual microcode binary data itself which is not shipped with
1189 The preferred method to load microcode from a detached initrd is described
1190 in Documentation/x86/early-microcode.txt. For that you need to enable
1191 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1192 initrd for microcode blobs.
1194 In addition, you can build-in the microcode into the kernel. For that you
1195 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1196 to the CONFIG_EXTRA_FIRMWARE config option.
1198 config MICROCODE_INTEL
1199 bool "Intel microcode loading support"
1200 depends on MICROCODE
1204 This options enables microcode patch loading support for Intel
1207 For the current Intel microcode data package go to
1208 <https://downloadcenter.intel.com> and search for
1209 'Linux Processor Microcode Data File'.
1211 config MICROCODE_AMD
1212 bool "AMD microcode loading support"
1213 depends on MICROCODE
1216 If you select this option, microcode patch loading support for AMD
1217 processors will be enabled.
1219 config MICROCODE_OLD_INTERFACE
1221 depends on MICROCODE
1224 tristate "/dev/cpu/*/msr - Model-specific register support"
1226 This device gives privileged processes access to the x86
1227 Model-Specific Registers (MSRs). It is a character device with
1228 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1229 MSR accesses are directed to a specific CPU on multi-processor
1233 tristate "/dev/cpu/*/cpuid - CPU information support"
1235 This device gives processes access to the x86 CPUID instruction to
1236 be executed on a specific processor. It is a character device
1237 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1241 prompt "High Memory Support"
1248 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1249 However, the address space of 32-bit x86 processors is only 4
1250 Gigabytes large. That means that, if you have a large amount of
1251 physical memory, not all of it can be "permanently mapped" by the
1252 kernel. The physical memory that's not permanently mapped is called
1255 If you are compiling a kernel which will never run on a machine with
1256 more than 1 Gigabyte total physical RAM, answer "off" here (default
1257 choice and suitable for most users). This will result in a "3GB/1GB"
1258 split: 3GB are mapped so that each process sees a 3GB virtual memory
1259 space and the remaining part of the 4GB virtual memory space is used
1260 by the kernel to permanently map as much physical memory as
1263 If the machine has between 1 and 4 Gigabytes physical RAM, then
1266 If more than 4 Gigabytes is used then answer "64GB" here. This
1267 selection turns Intel PAE (Physical Address Extension) mode on.
1268 PAE implements 3-level paging on IA32 processors. PAE is fully
1269 supported by Linux, PAE mode is implemented on all recent Intel
1270 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1271 then the kernel will not boot on CPUs that don't support PAE!
1273 The actual amount of total physical memory will either be
1274 auto detected or can be forced by using a kernel command line option
1275 such as "mem=256M". (Try "man bootparam" or see the documentation of
1276 your boot loader (lilo or loadlin) about how to pass options to the
1277 kernel at boot time.)
1279 If unsure, say "off".
1284 Select this if you have a 32-bit processor and between 1 and 4
1285 gigabytes of physical RAM.
1292 Select this if you have a 32-bit processor and more than 4
1293 gigabytes of physical RAM.
1298 prompt "Memory split" if EXPERT
1302 Select the desired split between kernel and user memory.
1304 If the address range available to the kernel is less than the
1305 physical memory installed, the remaining memory will be available
1306 as "high memory". Accessing high memory is a little more costly
1307 than low memory, as it needs to be mapped into the kernel first.
1308 Note that increasing the kernel address space limits the range
1309 available to user programs, making the address space there
1310 tighter. Selecting anything other than the default 3G/1G split
1311 will also likely make your kernel incompatible with binary-only
1314 If you are not absolutely sure what you are doing, leave this
1318 bool "3G/1G user/kernel split"
1319 config VMSPLIT_3G_OPT
1321 bool "3G/1G user/kernel split (for full 1G low memory)"
1323 bool "2G/2G user/kernel split"
1324 config VMSPLIT_2G_OPT
1326 bool "2G/2G user/kernel split (for full 2G low memory)"
1328 bool "1G/3G user/kernel split"
1333 default 0xB0000000 if VMSPLIT_3G_OPT
1334 default 0x80000000 if VMSPLIT_2G
1335 default 0x78000000 if VMSPLIT_2G_OPT
1336 default 0x40000000 if VMSPLIT_1G
1342 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1345 bool "PAE (Physical Address Extension) Support"
1346 depends on X86_32 && !HIGHMEM4G
1349 PAE is required for NX support, and furthermore enables
1350 larger swapspace support for non-overcommit purposes. It
1351 has the cost of more pagetable lookup overhead, and also
1352 consumes more pagetable space per process.
1354 config ARCH_PHYS_ADDR_T_64BIT
1356 depends on X86_64 || X86_PAE
1358 config ARCH_DMA_ADDR_T_64BIT
1360 depends on X86_64 || HIGHMEM64G
1362 config X86_DIRECT_GBPAGES
1364 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1366 Certain kernel features effectively disable kernel
1367 linear 1 GB mappings (even if the CPU otherwise
1368 supports them), so don't confuse the user by printing
1369 that we have them enabled.
1371 # Common NUMA Features
1373 bool "Numa Memory Allocation and Scheduler Support"
1375 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1376 default y if X86_BIGSMP
1378 Enable NUMA (Non Uniform Memory Access) support.
1380 The kernel will try to allocate memory used by a CPU on the
1381 local memory controller of the CPU and add some more
1382 NUMA awareness to the kernel.
1384 For 64-bit this is recommended if the system is Intel Core i7
1385 (or later), AMD Opteron, or EM64T NUMA.
1387 For 32-bit this is only needed if you boot a 32-bit
1388 kernel on a 64-bit NUMA platform.
1390 Otherwise, you should say N.
1394 prompt "Old style AMD Opteron NUMA detection"
1395 depends on X86_64 && NUMA && PCI
1397 Enable AMD NUMA node topology detection. You should say Y here if
1398 you have a multi processor AMD system. This uses an old method to
1399 read the NUMA configuration directly from the builtin Northbridge
1400 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1401 which also takes priority if both are compiled in.
1403 config X86_64_ACPI_NUMA
1405 prompt "ACPI NUMA detection"
1406 depends on X86_64 && NUMA && ACPI && PCI
1409 Enable ACPI SRAT based node topology detection.
1411 # Some NUMA nodes have memory ranges that span
1412 # other nodes. Even though a pfn is valid and
1413 # between a node's start and end pfns, it may not
1414 # reside on that node. See memmap_init_zone()
1416 config NODES_SPAN_OTHER_NODES
1418 depends on X86_64_ACPI_NUMA
1421 bool "NUMA emulation"
1424 Enable NUMA emulation. A flat machine will be split
1425 into virtual nodes when booted with "numa=fake=N", where N is the
1426 number of nodes. This is only useful for debugging.
1429 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1431 default "10" if MAXSMP
1432 default "6" if X86_64
1434 depends on NEED_MULTIPLE_NODES
1436 Specify the maximum number of NUMA Nodes available on the target
1437 system. Increases memory reserved to accommodate various tables.
1439 config ARCH_HAVE_MEMORY_PRESENT
1441 depends on X86_32 && DISCONTIGMEM
1443 config NEED_NODE_MEMMAP_SIZE
1445 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1447 config ARCH_FLATMEM_ENABLE
1449 depends on X86_32 && !NUMA
1451 config ARCH_DISCONTIGMEM_ENABLE
1453 depends on NUMA && X86_32
1455 config ARCH_DISCONTIGMEM_DEFAULT
1457 depends on NUMA && X86_32
1459 config ARCH_SPARSEMEM_ENABLE
1461 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1462 select SPARSEMEM_STATIC if X86_32
1463 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1465 config ARCH_SPARSEMEM_DEFAULT
1469 config ARCH_SELECT_MEMORY_MODEL
1471 depends on ARCH_SPARSEMEM_ENABLE
1473 config ARCH_MEMORY_PROBE
1474 bool "Enable sysfs memory/probe interface"
1475 depends on X86_64 && MEMORY_HOTPLUG
1477 This option enables a sysfs memory/probe interface for testing.
1478 See Documentation/memory-hotplug.txt for more information.
1479 If you are unsure how to answer this question, answer N.
1481 config ARCH_PROC_KCORE_TEXT
1483 depends on X86_64 && PROC_KCORE
1485 config ILLEGAL_POINTER_VALUE
1488 default 0xdead000000000000 if X86_64
1492 config X86_PMEM_LEGACY_DEVICE
1495 config X86_PMEM_LEGACY
1496 tristate "Support non-standard NVDIMMs and ADR protected memory"
1497 depends on PHYS_ADDR_T_64BIT
1499 select X86_PMEM_LEGACY_DEVICE
1502 Treat memory marked using the non-standard e820 type of 12 as used
1503 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1504 The kernel will offer these regions to the 'pmem' driver so
1505 they can be used for persistent storage.
1510 bool "Allocate 3rd-level pagetables from highmem"
1513 The VM uses one page table entry for each page of physical memory.
1514 For systems with a lot of RAM, this can be wasteful of precious
1515 low memory. Setting this option will put user-space page table
1516 entries in high memory.
1518 config X86_CHECK_BIOS_CORRUPTION
1519 bool "Check for low memory corruption"
1521 Periodically check for memory corruption in low memory, which
1522 is suspected to be caused by BIOS. Even when enabled in the
1523 configuration, it is disabled at runtime. Enable it by
1524 setting "memory_corruption_check=1" on the kernel command
1525 line. By default it scans the low 64k of memory every 60
1526 seconds; see the memory_corruption_check_size and
1527 memory_corruption_check_period parameters in
1528 Documentation/kernel-parameters.txt to adjust this.
1530 When enabled with the default parameters, this option has
1531 almost no overhead, as it reserves a relatively small amount
1532 of memory and scans it infrequently. It both detects corruption
1533 and prevents it from affecting the running system.
1535 It is, however, intended as a diagnostic tool; if repeatable
1536 BIOS-originated corruption always affects the same memory,
1537 you can use memmap= to prevent the kernel from using that
1540 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1541 bool "Set the default setting of memory_corruption_check"
1542 depends on X86_CHECK_BIOS_CORRUPTION
1545 Set whether the default state of memory_corruption_check is
1548 config X86_RESERVE_LOW
1549 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1553 Specify the amount of low memory to reserve for the BIOS.
1555 The first page contains BIOS data structures that the kernel
1556 must not use, so that page must always be reserved.
1558 By default we reserve the first 64K of physical RAM, as a
1559 number of BIOSes are known to corrupt that memory range
1560 during events such as suspend/resume or monitor cable
1561 insertion, so it must not be used by the kernel.
1563 You can set this to 4 if you are absolutely sure that you
1564 trust the BIOS to get all its memory reservations and usages
1565 right. If you know your BIOS have problems beyond the
1566 default 64K area, you can set this to 640 to avoid using the
1567 entire low memory range.
1569 If you have doubts about the BIOS (e.g. suspend/resume does
1570 not work or there's kernel crashes after certain hardware
1571 hotplug events) then you might want to enable
1572 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1573 typical corruption patterns.
1575 Leave this to the default value of 64 if you are unsure.
1577 config MATH_EMULATION
1579 depends on MODIFY_LDT_SYSCALL
1580 prompt "Math emulation" if X86_32
1582 Linux can emulate a math coprocessor (used for floating point
1583 operations) if you don't have one. 486DX and Pentium processors have
1584 a math coprocessor built in, 486SX and 386 do not, unless you added
1585 a 487DX or 387, respectively. (The messages during boot time can
1586 give you some hints here ["man dmesg"].) Everyone needs either a
1587 coprocessor or this emulation.
1589 If you don't have a math coprocessor, you need to say Y here; if you
1590 say Y here even though you have a coprocessor, the coprocessor will
1591 be used nevertheless. (This behavior can be changed with the kernel
1592 command line option "no387", which comes handy if your coprocessor
1593 is broken. Try "man bootparam" or see the documentation of your boot
1594 loader (lilo or loadlin) about how to pass options to the kernel at
1595 boot time.) This means that it is a good idea to say Y here if you
1596 intend to use this kernel on different machines.
1598 More information about the internals of the Linux math coprocessor
1599 emulation can be found in <file:arch/x86/math-emu/README>.
1601 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1602 kernel, it won't hurt.
1606 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1608 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1609 the Memory Type Range Registers (MTRRs) may be used to control
1610 processor access to memory ranges. This is most useful if you have
1611 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1612 allows bus write transfers to be combined into a larger transfer
1613 before bursting over the PCI/AGP bus. This can increase performance
1614 of image write operations 2.5 times or more. Saying Y here creates a
1615 /proc/mtrr file which may be used to manipulate your processor's
1616 MTRRs. Typically the X server should use this.
1618 This code has a reasonably generic interface so that similar
1619 control registers on other processors can be easily supported
1622 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1623 Registers (ARRs) which provide a similar functionality to MTRRs. For
1624 these, the ARRs are used to emulate the MTRRs.
1625 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1626 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1627 write-combining. All of these processors are supported by this code
1628 and it makes sense to say Y here if you have one of them.
1630 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1631 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1632 can lead to all sorts of problems, so it's good to say Y here.
1634 You can safely say Y even if your machine doesn't have MTRRs, you'll
1635 just add about 9 KB to your kernel.
1637 See <file:Documentation/x86/mtrr.txt> for more information.
1639 config MTRR_SANITIZER
1641 prompt "MTRR cleanup support"
1644 Convert MTRR layout from continuous to discrete, so X drivers can
1645 add writeback entries.
1647 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1648 The largest mtrr entry size for a continuous block can be set with
1653 config MTRR_SANITIZER_ENABLE_DEFAULT
1654 int "MTRR cleanup enable value (0-1)"
1657 depends on MTRR_SANITIZER
1659 Enable mtrr cleanup default value
1661 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1662 int "MTRR cleanup spare reg num (0-7)"
1665 depends on MTRR_SANITIZER
1667 mtrr cleanup spare entries default, it can be changed via
1668 mtrr_spare_reg_nr=N on the kernel command line.
1672 prompt "x86 PAT support" if EXPERT
1675 Use PAT attributes to setup page level cache control.
1677 PATs are the modern equivalents of MTRRs and are much more
1678 flexible than MTRRs.
1680 Say N here if you see bootup problems (boot crash, boot hang,
1681 spontaneous reboots) or a non-working video driver.
1685 config ARCH_USES_PG_UNCACHED
1691 prompt "x86 architectural random number generator" if EXPERT
1693 Enable the x86 architectural RDRAND instruction
1694 (Intel Bull Mountain technology) to generate random numbers.
1695 If supported, this is a high bandwidth, cryptographically
1696 secure hardware random number generator.
1700 prompt "Supervisor Mode Access Prevention" if EXPERT
1702 Supervisor Mode Access Prevention (SMAP) is a security
1703 feature in newer Intel processors. There is a small
1704 performance cost if this enabled and turned on; there is
1705 also a small increase in the kernel size if this is enabled.
1709 config X86_INTEL_MPX
1710 prompt "Intel MPX (Memory Protection Extensions)"
1712 depends on CPU_SUP_INTEL
1714 MPX provides hardware features that can be used in
1715 conjunction with compiler-instrumented code to check
1716 memory references. It is designed to detect buffer
1717 overflow or underflow bugs.
1719 This option enables running applications which are
1720 instrumented or otherwise use MPX. It does not use MPX
1721 itself inside the kernel or to protect the kernel
1722 against bad memory references.
1724 Enabling this option will make the kernel larger:
1725 ~8k of kernel text and 36 bytes of data on a 64-bit
1726 defconfig. It adds a long to the 'mm_struct' which
1727 will increase the kernel memory overhead of each
1728 process and adds some branches to paths used during
1729 exec() and munmap().
1731 For details, see Documentation/x86/intel_mpx.txt
1735 config X86_INTEL_MEMORY_PROTECTION_KEYS
1736 prompt "Intel Memory Protection Keys"
1738 # Note: only available in 64-bit mode
1739 depends on CPU_SUP_INTEL && X86_64
1741 Memory Protection Keys provides a mechanism for enforcing
1742 page-based protections, but without requiring modification of the
1743 page tables when an application changes protection domains.
1745 For details, see Documentation/x86/protection-keys.txt
1750 bool "EFI runtime service support"
1753 select EFI_RUNTIME_WRAPPERS
1755 This enables the kernel to use EFI runtime services that are
1756 available (such as the EFI variable services).
1758 This option is only useful on systems that have EFI firmware.
1759 In addition, you should use the latest ELILO loader available
1760 at <http://elilo.sourceforge.net> in order to take advantage
1761 of EFI runtime services. However, even with this option, the
1762 resultant kernel should continue to boot on existing non-EFI
1766 bool "EFI stub support"
1767 depends on EFI && !X86_USE_3DNOW
1770 This kernel feature allows a bzImage to be loaded directly
1771 by EFI firmware without the use of a bootloader.
1773 See Documentation/efi-stub.txt for more information.
1776 bool "EFI mixed-mode support"
1777 depends on EFI_STUB && X86_64
1779 Enabling this feature allows a 64-bit kernel to be booted
1780 on a 32-bit firmware, provided that your CPU supports 64-bit
1783 Note that it is not possible to boot a mixed-mode enabled
1784 kernel via the EFI boot stub - a bootloader that supports
1785 the EFI handover protocol must be used.
1791 prompt "Enable seccomp to safely compute untrusted bytecode"
1793 This kernel feature is useful for number crunching applications
1794 that may need to compute untrusted bytecode during their
1795 execution. By using pipes or other transports made available to
1796 the process as file descriptors supporting the read/write
1797 syscalls, it's possible to isolate those applications in
1798 their own address space using seccomp. Once seccomp is
1799 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1800 and the task is only allowed to execute a few safe syscalls
1801 defined by each seccomp mode.
1803 If unsure, say Y. Only embedded should say N here.
1805 source kernel/Kconfig.hz
1808 bool "kexec system call"
1811 kexec is a system call that implements the ability to shutdown your
1812 current kernel, and to start another kernel. It is like a reboot
1813 but it is independent of the system firmware. And like a reboot
1814 you can start any kernel with it, not just Linux.
1816 The name comes from the similarity to the exec system call.
1818 It is an ongoing process to be certain the hardware in a machine
1819 is properly shutdown, so do not be surprised if this code does not
1820 initially work for you. As of this writing the exact hardware
1821 interface is strongly in flux, so no good recommendation can be
1825 bool "kexec file based system call"
1830 depends on CRYPTO_SHA256=y
1832 This is new version of kexec system call. This system call is
1833 file based and takes file descriptors as system call argument
1834 for kernel and initramfs as opposed to list of segments as
1835 accepted by previous system call.
1837 config KEXEC_VERIFY_SIG
1838 bool "Verify kernel signature during kexec_file_load() syscall"
1839 depends on KEXEC_FILE
1841 This option makes kernel signature verification mandatory for
1842 the kexec_file_load() syscall.
1844 In addition to that option, you need to enable signature
1845 verification for the corresponding kernel image type being
1846 loaded in order for this to work.
1848 config KEXEC_BZIMAGE_VERIFY_SIG
1849 bool "Enable bzImage signature verification support"
1850 depends on KEXEC_VERIFY_SIG
1851 depends on SIGNED_PE_FILE_VERIFICATION
1852 select SYSTEM_TRUSTED_KEYRING
1854 Enable bzImage signature verification support.
1857 bool "kernel crash dumps"
1858 depends on X86_64 || (X86_32 && HIGHMEM)
1860 Generate crash dump after being started by kexec.
1861 This should be normally only set in special crash dump kernels
1862 which are loaded in the main kernel with kexec-tools into
1863 a specially reserved region and then later executed after
1864 a crash by kdump/kexec. The crash dump kernel must be compiled
1865 to a memory address not used by the main kernel or BIOS using
1866 PHYSICAL_START, or it must be built as a relocatable image
1867 (CONFIG_RELOCATABLE=y).
1868 For more details see Documentation/kdump/kdump.txt
1872 depends on KEXEC && HIBERNATION
1874 Jump between original kernel and kexeced kernel and invoke
1875 code in physical address mode via KEXEC
1877 config PHYSICAL_START
1878 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1881 This gives the physical address where the kernel is loaded.
1883 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1884 bzImage will decompress itself to above physical address and
1885 run from there. Otherwise, bzImage will run from the address where
1886 it has been loaded by the boot loader and will ignore above physical
1889 In normal kdump cases one does not have to set/change this option
1890 as now bzImage can be compiled as a completely relocatable image
1891 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1892 address. This option is mainly useful for the folks who don't want
1893 to use a bzImage for capturing the crash dump and want to use a
1894 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1895 to be specifically compiled to run from a specific memory area
1896 (normally a reserved region) and this option comes handy.
1898 So if you are using bzImage for capturing the crash dump,
1899 leave the value here unchanged to 0x1000000 and set
1900 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1901 for capturing the crash dump change this value to start of
1902 the reserved region. In other words, it can be set based on
1903 the "X" value as specified in the "crashkernel=YM@XM"
1904 command line boot parameter passed to the panic-ed
1905 kernel. Please take a look at Documentation/kdump/kdump.txt
1906 for more details about crash dumps.
1908 Usage of bzImage for capturing the crash dump is recommended as
1909 one does not have to build two kernels. Same kernel can be used
1910 as production kernel and capture kernel. Above option should have
1911 gone away after relocatable bzImage support is introduced. But it
1912 is present because there are users out there who continue to use
1913 vmlinux for dump capture. This option should go away down the
1916 Don't change this unless you know what you are doing.
1919 bool "Build a relocatable kernel"
1922 This builds a kernel image that retains relocation information
1923 so it can be loaded someplace besides the default 1MB.
1924 The relocations tend to make the kernel binary about 10% larger,
1925 but are discarded at runtime.
1927 One use is for the kexec on panic case where the recovery kernel
1928 must live at a different physical address than the primary
1931 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1932 it has been loaded at and the compile time physical address
1933 (CONFIG_PHYSICAL_START) is used as the minimum location.
1935 config RANDOMIZE_BASE
1936 bool "Randomize the address of the kernel image (KASLR)"
1937 depends on RELOCATABLE
1940 In support of Kernel Address Space Layout Randomization (KASLR),
1941 this randomizes the physical address at which the kernel image
1942 is decompressed and the virtual address where the kernel
1943 image is mapped, as a security feature that deters exploit
1944 attempts relying on knowledge of the location of kernel
1947 On 64-bit, the kernel physical and virtual addresses are
1948 randomized separately. The physical address will be anywhere
1949 between 16MB and the top of physical memory (up to 64TB). The
1950 virtual address will be randomized from 16MB up to 1GB (9 bits
1951 of entropy). Note that this also reduces the memory space
1952 available to kernel modules from 1.5GB to 1GB.
1954 On 32-bit, the kernel physical and virtual addresses are
1955 randomized together. They will be randomized from 16MB up to
1956 512MB (8 bits of entropy).
1958 Entropy is generated using the RDRAND instruction if it is
1959 supported. If RDTSC is supported, its value is mixed into
1960 the entropy pool as well. If neither RDRAND nor RDTSC are
1961 supported, then entropy is read from the i8254 timer. The
1962 usable entropy is limited by the kernel being built using
1963 2GB addressing, and that PHYSICAL_ALIGN must be at a
1964 minimum of 2MB. As a result, only 10 bits of entropy are
1965 theoretically possible, but the implementations are further
1966 limited due to memory layouts.
1968 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1969 time. To enable it, boot with "kaslr" on the kernel command
1970 line (which will also disable hibernation).
1974 # Relocation on x86 needs some additional build support
1975 config X86_NEED_RELOCS
1977 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1979 config PHYSICAL_ALIGN
1980 hex "Alignment value to which kernel should be aligned"
1982 range 0x2000 0x1000000 if X86_32
1983 range 0x200000 0x1000000 if X86_64
1985 This value puts the alignment restrictions on physical address
1986 where kernel is loaded and run from. Kernel is compiled for an
1987 address which meets above alignment restriction.
1989 If bootloader loads the kernel at a non-aligned address and
1990 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1991 address aligned to above value and run from there.
1993 If bootloader loads the kernel at a non-aligned address and
1994 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1995 load address and decompress itself to the address it has been
1996 compiled for and run from there. The address for which kernel is
1997 compiled already meets above alignment restrictions. Hence the
1998 end result is that kernel runs from a physical address meeting
1999 above alignment restrictions.
2001 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2002 this value must be a multiple of 0x200000.
2004 Don't change this unless you know what you are doing.
2006 config RANDOMIZE_MEMORY
2007 bool "Randomize the kernel memory sections"
2009 depends on RANDOMIZE_BASE
2010 default RANDOMIZE_BASE
2012 Randomizes the base virtual address of kernel memory sections
2013 (physical memory mapping, vmalloc & vmemmap). This security feature
2014 makes exploits relying on predictable memory locations less reliable.
2016 The order of allocations remains unchanged. Entropy is generated in
2017 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2018 configuration have in average 30,000 different possible virtual
2019 addresses for each memory section.
2023 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2024 hex "Physical memory mapping padding" if EXPERT
2025 depends on RANDOMIZE_MEMORY
2026 default "0xa" if MEMORY_HOTPLUG
2028 range 0x1 0x40 if MEMORY_HOTPLUG
2031 Define the padding in terabytes added to the existing physical
2032 memory size during kernel memory randomization. It is useful
2033 for memory hotplug support but reduces the entropy available for
2034 address randomization.
2036 If unsure, leave at the default value.
2039 bool "Support for hot-pluggable CPUs"
2042 Say Y here to allow turning CPUs off and on. CPUs can be
2043 controlled through /sys/devices/system/cpu.
2044 ( Note: power management support will enable this option
2045 automatically on SMP systems. )
2046 Say N if you want to disable CPU hotplug.
2048 config BOOTPARAM_HOTPLUG_CPU0
2049 bool "Set default setting of cpu0_hotpluggable"
2051 depends on HOTPLUG_CPU
2053 Set whether default state of cpu0_hotpluggable is on or off.
2055 Say Y here to enable CPU0 hotplug by default. If this switch
2056 is turned on, there is no need to give cpu0_hotplug kernel
2057 parameter and the CPU0 hotplug feature is enabled by default.
2059 Please note: there are two known CPU0 dependencies if you want
2060 to enable the CPU0 hotplug feature either by this switch or by
2061 cpu0_hotplug kernel parameter.
2063 First, resume from hibernate or suspend always starts from CPU0.
2064 So hibernate and suspend are prevented if CPU0 is offline.
2066 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2067 offline if any interrupt can not migrate out of CPU0. There may
2068 be other CPU0 dependencies.
2070 Please make sure the dependencies are under your control before
2071 you enable this feature.
2073 Say N if you don't want to enable CPU0 hotplug feature by default.
2074 You still can enable the CPU0 hotplug feature at boot by kernel
2075 parameter cpu0_hotplug.
2077 config DEBUG_HOTPLUG_CPU0
2079 prompt "Debug CPU0 hotplug"
2080 depends on HOTPLUG_CPU
2082 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2083 soon as possible and boots up userspace with CPU0 offlined. User
2084 can online CPU0 back after boot time.
2086 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2087 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2088 compilation or giving cpu0_hotplug kernel parameter at boot.
2094 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2095 depends on X86_32 || IA32_EMULATION
2097 Certain buggy versions of glibc will crash if they are
2098 presented with a 32-bit vDSO that is not mapped at the address
2099 indicated in its segment table.
2101 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2102 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2103 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2104 the only released version with the bug, but OpenSUSE 9
2105 contains a buggy "glibc 2.3.2".
2107 The symptom of the bug is that everything crashes on startup, saying:
2108 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2110 Saying Y here changes the default value of the vdso32 boot
2111 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2112 This works around the glibc bug but hurts performance.
2114 If unsure, say N: if you are compiling your own kernel, you
2115 are unlikely to be using a buggy version of glibc.
2118 prompt "vsyscall table for legacy applications"
2120 default LEGACY_VSYSCALL_EMULATE
2122 Legacy user code that does not know how to find the vDSO expects
2123 to be able to issue three syscalls by calling fixed addresses in
2124 kernel space. Since this location is not randomized with ASLR,
2125 it can be used to assist security vulnerability exploitation.
2127 This setting can be changed at boot time via the kernel command
2128 line parameter vsyscall=[native|emulate|none].
2130 On a system with recent enough glibc (2.14 or newer) and no
2131 static binaries, you can say None without a performance penalty
2132 to improve security.
2134 If unsure, select "Emulate".
2136 config LEGACY_VSYSCALL_NATIVE
2139 Actual executable code is located in the fixed vsyscall
2140 address mapping, implementing time() efficiently. Since
2141 this makes the mapping executable, it can be used during
2142 security vulnerability exploitation (traditionally as
2143 ROP gadgets). This configuration is not recommended.
2145 config LEGACY_VSYSCALL_EMULATE
2148 The kernel traps and emulates calls into the fixed
2149 vsyscall address mapping. This makes the mapping
2150 non-executable, but it still contains known contents,
2151 which could be used in certain rare security vulnerability
2152 exploits. This configuration is recommended when userspace
2153 still uses the vsyscall area.
2155 config LEGACY_VSYSCALL_NONE
2158 There will be no vsyscall mapping at all. This will
2159 eliminate any risk of ASLR bypass due to the vsyscall
2160 fixed address mapping. Attempts to use the vsyscalls
2161 will be reported to dmesg, so that either old or
2162 malicious userspace programs can be identified.
2167 bool "Built-in kernel command line"
2169 Allow for specifying boot arguments to the kernel at
2170 build time. On some systems (e.g. embedded ones), it is
2171 necessary or convenient to provide some or all of the
2172 kernel boot arguments with the kernel itself (that is,
2173 to not rely on the boot loader to provide them.)
2175 To compile command line arguments into the kernel,
2176 set this option to 'Y', then fill in the
2177 boot arguments in CONFIG_CMDLINE.
2179 Systems with fully functional boot loaders (i.e. non-embedded)
2180 should leave this option set to 'N'.
2183 string "Built-in kernel command string"
2184 depends on CMDLINE_BOOL
2187 Enter arguments here that should be compiled into the kernel
2188 image and used at boot time. If the boot loader provides a
2189 command line at boot time, it is appended to this string to
2190 form the full kernel command line, when the system boots.
2192 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2193 change this behavior.
2195 In most cases, the command line (whether built-in or provided
2196 by the boot loader) should specify the device for the root
2199 config CMDLINE_OVERRIDE
2200 bool "Built-in command line overrides boot loader arguments"
2201 depends on CMDLINE_BOOL
2203 Set this option to 'Y' to have the kernel ignore the boot loader
2204 command line, and use ONLY the built-in command line.
2206 This is used to work around broken boot loaders. This should
2207 be set to 'N' under normal conditions.
2209 config MODIFY_LDT_SYSCALL
2210 bool "Enable the LDT (local descriptor table)" if EXPERT
2213 Linux can allow user programs to install a per-process x86
2214 Local Descriptor Table (LDT) using the modify_ldt(2) system
2215 call. This is required to run 16-bit or segmented code such as
2216 DOSEMU or some Wine programs. It is also used by some very old
2217 threading libraries.
2219 Enabling this feature adds a small amount of overhead to
2220 context switches and increases the low-level kernel attack
2221 surface. Disabling it removes the modify_ldt(2) system call.
2223 Saying 'N' here may make sense for embedded or server kernels.
2225 source "kernel/livepatch/Kconfig"
2229 config ARCH_ENABLE_MEMORY_HOTPLUG
2231 depends on X86_64 || (X86_32 && HIGHMEM)
2233 config ARCH_ENABLE_MEMORY_HOTREMOVE
2235 depends on MEMORY_HOTPLUG
2237 config USE_PERCPU_NUMA_NODE_ID
2241 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2243 depends on X86_64 || X86_PAE
2245 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2247 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2249 menu "Power management and ACPI options"
2251 config ARCH_HIBERNATION_HEADER
2253 depends on X86_64 && HIBERNATION
2255 source "kernel/power/Kconfig"
2257 source "drivers/acpi/Kconfig"
2259 source "drivers/sfi/Kconfig"
2266 tristate "APM (Advanced Power Management) BIOS support"
2267 depends on X86_32 && PM_SLEEP
2269 APM is a BIOS specification for saving power using several different
2270 techniques. This is mostly useful for battery powered laptops with
2271 APM compliant BIOSes. If you say Y here, the system time will be
2272 reset after a RESUME operation, the /proc/apm device will provide
2273 battery status information, and user-space programs will receive
2274 notification of APM "events" (e.g. battery status change).
2276 If you select "Y" here, you can disable actual use of the APM
2277 BIOS by passing the "apm=off" option to the kernel at boot time.
2279 Note that the APM support is almost completely disabled for
2280 machines with more than one CPU.
2282 In order to use APM, you will need supporting software. For location
2283 and more information, read <file:Documentation/power/apm-acpi.txt>
2284 and the Battery Powered Linux mini-HOWTO, available from
2285 <http://www.tldp.org/docs.html#howto>.
2287 This driver does not spin down disk drives (see the hdparm(8)
2288 manpage ("man 8 hdparm") for that), and it doesn't turn off
2289 VESA-compliant "green" monitors.
2291 This driver does not support the TI 4000M TravelMate and the ACER
2292 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2293 desktop machines also don't have compliant BIOSes, and this driver
2294 may cause those machines to panic during the boot phase.
2296 Generally, if you don't have a battery in your machine, there isn't
2297 much point in using this driver and you should say N. If you get
2298 random kernel OOPSes or reboots that don't seem to be related to
2299 anything, try disabling/enabling this option (or disabling/enabling
2302 Some other things you should try when experiencing seemingly random,
2305 1) make sure that you have enough swap space and that it is
2307 2) pass the "no-hlt" option to the kernel
2308 3) switch on floating point emulation in the kernel and pass
2309 the "no387" option to the kernel
2310 4) pass the "floppy=nodma" option to the kernel
2311 5) pass the "mem=4M" option to the kernel (thereby disabling
2312 all but the first 4 MB of RAM)
2313 6) make sure that the CPU is not over clocked.
2314 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2315 8) disable the cache from your BIOS settings
2316 9) install a fan for the video card or exchange video RAM
2317 10) install a better fan for the CPU
2318 11) exchange RAM chips
2319 12) exchange the motherboard.
2321 To compile this driver as a module, choose M here: the
2322 module will be called apm.
2326 config APM_IGNORE_USER_SUSPEND
2327 bool "Ignore USER SUSPEND"
2329 This option will ignore USER SUSPEND requests. On machines with a
2330 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2331 series notebooks, it is necessary to say Y because of a BIOS bug.
2333 config APM_DO_ENABLE
2334 bool "Enable PM at boot time"
2336 Enable APM features at boot time. From page 36 of the APM BIOS
2337 specification: "When disabled, the APM BIOS does not automatically
2338 power manage devices, enter the Standby State, enter the Suspend
2339 State, or take power saving steps in response to CPU Idle calls."
2340 This driver will make CPU Idle calls when Linux is idle (unless this
2341 feature is turned off -- see "Do CPU IDLE calls", below). This
2342 should always save battery power, but more complicated APM features
2343 will be dependent on your BIOS implementation. You may need to turn
2344 this option off if your computer hangs at boot time when using APM
2345 support, or if it beeps continuously instead of suspending. Turn
2346 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2347 T400CDT. This is off by default since most machines do fine without
2352 bool "Make CPU Idle calls when idle"
2354 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2355 On some machines, this can activate improved power savings, such as
2356 a slowed CPU clock rate, when the machine is idle. These idle calls
2357 are made after the idle loop has run for some length of time (e.g.,
2358 333 mS). On some machines, this will cause a hang at boot time or
2359 whenever the CPU becomes idle. (On machines with more than one CPU,
2360 this option does nothing.)
2362 config APM_DISPLAY_BLANK
2363 bool "Enable console blanking using APM"
2365 Enable console blanking using the APM. Some laptops can use this to
2366 turn off the LCD backlight when the screen blanker of the Linux
2367 virtual console blanks the screen. Note that this is only used by
2368 the virtual console screen blanker, and won't turn off the backlight
2369 when using the X Window system. This also doesn't have anything to
2370 do with your VESA-compliant power-saving monitor. Further, this
2371 option doesn't work for all laptops -- it might not turn off your
2372 backlight at all, or it might print a lot of errors to the console,
2373 especially if you are using gpm.
2375 config APM_ALLOW_INTS
2376 bool "Allow interrupts during APM BIOS calls"
2378 Normally we disable external interrupts while we are making calls to
2379 the APM BIOS as a measure to lessen the effects of a badly behaving
2380 BIOS implementation. The BIOS should reenable interrupts if it
2381 needs to. Unfortunately, some BIOSes do not -- especially those in
2382 many of the newer IBM Thinkpads. If you experience hangs when you
2383 suspend, try setting this to Y. Otherwise, say N.
2387 source "drivers/cpufreq/Kconfig"
2389 source "drivers/cpuidle/Kconfig"
2391 source "drivers/idle/Kconfig"
2396 menu "Bus options (PCI etc.)"
2402 Find out whether you have a PCI motherboard. PCI is the name of a
2403 bus system, i.e. the way the CPU talks to the other stuff inside
2404 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2405 VESA. If you have PCI, say Y, otherwise N.
2408 prompt "PCI access mode"
2409 depends on X86_32 && PCI
2412 On PCI systems, the BIOS can be used to detect the PCI devices and
2413 determine their configuration. However, some old PCI motherboards
2414 have BIOS bugs and may crash if this is done. Also, some embedded
2415 PCI-based systems don't have any BIOS at all. Linux can also try to
2416 detect the PCI hardware directly without using the BIOS.
2418 With this option, you can specify how Linux should detect the
2419 PCI devices. If you choose "BIOS", the BIOS will be used,
2420 if you choose "Direct", the BIOS won't be used, and if you
2421 choose "MMConfig", then PCI Express MMCONFIG will be used.
2422 If you choose "Any", the kernel will try MMCONFIG, then the
2423 direct access method and falls back to the BIOS if that doesn't
2424 work. If unsure, go with the default, which is "Any".
2429 config PCI_GOMMCONFIG
2446 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2448 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2451 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2455 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2459 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2463 depends on PCI && XEN
2471 bool "Support mmconfig PCI config space access"
2472 depends on X86_64 && PCI && ACPI
2474 config PCI_CNB20LE_QUIRK
2475 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2478 Read the PCI windows out of the CNB20LE host bridge. This allows
2479 PCI hotplug to work on systems with the CNB20LE chipset which do
2482 There's no public spec for this chipset, and this functionality
2483 is known to be incomplete.
2485 You should say N unless you know you need this.
2487 source "drivers/pci/Kconfig"
2490 bool "ISA-style bus support on modern systems" if EXPERT
2493 Enables ISA-style drivers on modern systems. This is necessary to
2494 support PC/104 devices on X86_64 platforms.
2498 # x86_64 have no ISA slots, but can have ISA-style DMA.
2500 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2503 Enables ISA-style DMA support for devices requiring such controllers.
2511 Find out whether you have ISA slots on your motherboard. ISA is the
2512 name of a bus system, i.e. the way the CPU talks to the other stuff
2513 inside your box. Other bus systems are PCI, EISA, MicroChannel
2514 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2515 newer boards don't support it. If you have ISA, say Y, otherwise N.
2521 The Extended Industry Standard Architecture (EISA) bus was
2522 developed as an open alternative to the IBM MicroChannel bus.
2524 The EISA bus provided some of the features of the IBM MicroChannel
2525 bus while maintaining backward compatibility with cards made for
2526 the older ISA bus. The EISA bus saw limited use between 1988 and
2527 1995 when it was made obsolete by the PCI bus.
2529 Say Y here if you are building a kernel for an EISA-based machine.
2533 source "drivers/eisa/Kconfig"
2536 tristate "NatSemi SCx200 support"
2538 This provides basic support for National Semiconductor's
2539 (now AMD's) Geode processors. The driver probes for the
2540 PCI-IDs of several on-chip devices, so its a good dependency
2541 for other scx200_* drivers.
2543 If compiled as a module, the driver is named scx200.
2545 config SCx200HR_TIMER
2546 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2550 This driver provides a clocksource built upon the on-chip
2551 27MHz high-resolution timer. Its also a workaround for
2552 NSC Geode SC-1100's buggy TSC, which loses time when the
2553 processor goes idle (as is done by the scheduler). The
2554 other workaround is idle=poll boot option.
2557 bool "One Laptop Per Child support"
2564 Add support for detecting the unique features of the OLPC
2568 bool "OLPC XO-1 Power Management"
2569 depends on OLPC && MFD_CS5535 && PM_SLEEP
2572 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2575 bool "OLPC XO-1 Real Time Clock"
2576 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2578 Add support for the XO-1 real time clock, which can be used as a
2579 programmable wakeup source.
2582 bool "OLPC XO-1 SCI extras"
2583 depends on OLPC && OLPC_XO1_PM
2589 Add support for SCI-based features of the OLPC XO-1 laptop:
2590 - EC-driven system wakeups
2594 - AC adapter status updates
2595 - Battery status updates
2597 config OLPC_XO15_SCI
2598 bool "OLPC XO-1.5 SCI extras"
2599 depends on OLPC && ACPI
2602 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2603 - EC-driven system wakeups
2604 - AC adapter status updates
2605 - Battery status updates
2608 bool "PCEngines ALIX System Support (LED setup)"
2611 This option enables system support for the PCEngines ALIX.
2612 At present this just sets up LEDs for GPIO control on
2613 ALIX2/3/6 boards. However, other system specific setup should
2616 Note: You must still enable the drivers for GPIO and LED support
2617 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2619 Note: You have to set alix.force=1 for boards with Award BIOS.
2622 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2625 This option enables system support for the Soekris Engineering net5501.
2628 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2632 This option enables system support for the Traverse Technologies GEOS.
2635 bool "Technologic Systems TS-5500 platform support"
2637 select CHECK_SIGNATURE
2641 This option enables system support for the Technologic Systems TS-5500.
2647 depends on CPU_SUP_AMD && PCI
2649 source "drivers/pcmcia/Kconfig"
2652 tristate "RapidIO support"
2656 If enabled this option will include drivers and the core
2657 infrastructure code to support RapidIO interconnect devices.
2659 source "drivers/rapidio/Kconfig"
2662 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2664 Firmwares often provide initial graphics framebuffers so the BIOS,
2665 bootloader or kernel can show basic video-output during boot for
2666 user-guidance and debugging. Historically, x86 used the VESA BIOS
2667 Extensions and EFI-framebuffers for this, which are mostly limited
2669 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2670 framebuffers so the new generic system-framebuffer drivers can be
2671 used on x86. If the framebuffer is not compatible with the generic
2672 modes, it is adverticed as fallback platform framebuffer so legacy
2673 drivers like efifb, vesafb and uvesafb can pick it up.
2674 If this option is not selected, all system framebuffers are always
2675 marked as fallback platform framebuffers as usual.
2677 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2678 not be able to pick up generic system framebuffers if this option
2679 is selected. You are highly encouraged to enable simplefb as
2680 replacement if you select this option. simplefb can correctly deal
2681 with generic system framebuffers. But you should still keep vesafb
2682 and others enabled as fallback if a system framebuffer is
2683 incompatible with simplefb.
2690 menu "Executable file formats / Emulations"
2692 source "fs/Kconfig.binfmt"
2694 config IA32_EMULATION
2695 bool "IA32 Emulation"
2698 select COMPAT_BINFMT_ELF
2699 select ARCH_WANT_OLD_COMPAT_IPC
2701 Include code to run legacy 32-bit programs under a
2702 64-bit kernel. You should likely turn this on, unless you're
2703 100% sure that you don't have any 32-bit programs left.
2706 tristate "IA32 a.out support"
2707 depends on IA32_EMULATION
2709 Support old a.out binaries in the 32bit emulation.
2712 bool "x32 ABI for 64-bit mode"
2715 Include code to run binaries for the x32 native 32-bit ABI
2716 for 64-bit processors. An x32 process gets access to the
2717 full 64-bit register file and wide data path while leaving
2718 pointers at 32 bits for smaller memory footprint.
2720 You will need a recent binutils (2.22 or later) with
2721 elf32_x86_64 support enabled to compile a kernel with this
2726 depends on IA32_EMULATION || X86_X32
2729 config COMPAT_FOR_U64_ALIGNMENT
2732 config SYSVIPC_COMPAT
2744 config HAVE_ATOMIC_IOMAP
2748 config X86_DEV_DMA_OPS
2750 depends on X86_64 || STA2X11
2752 config X86_DMA_REMAP
2760 source "net/Kconfig"
2762 source "drivers/Kconfig"
2764 source "drivers/firmware/Kconfig"
2768 source "arch/x86/Kconfig.debug"
2770 source "security/Kconfig"
2772 source "crypto/Kconfig"
2774 source "arch/x86/kvm/Kconfig"
2776 source "lib/Kconfig"