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_DEVMEM_IS_ALLOWED
28 select ARCH_HAS_ELF_RANDOMIZE
29 select ARCH_HAS_FAST_MULTIPLIER
30 select ARCH_HAS_GCOV_PROFILE_ALL
31 select ARCH_HAS_PMEM_API if X86_64
32 select ARCH_HAS_MMIO_FLUSH
33 select ARCH_HAS_SG_CHAIN
34 select ARCH_HAS_UBSAN_SANITIZE_ALL
35 select ARCH_HAVE_NMI_SAFE_CMPXCHG
36 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
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_USE_QUEUED_SPINLOCKS
47 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
48 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
49 select ARCH_WANT_FRAME_POINTERS
50 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
51 select ARCH_WANT_OPTIONAL_GPIOLIB
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_HUGE_VMAP if X86_64 || X86_PAE
83 select HAVE_ARCH_JUMP_LABEL
84 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
86 select HAVE_ARCH_KMEMCHECK
87 select HAVE_ARCH_MMAP_RND_BITS if MMU
88 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
89 select HAVE_ARCH_SECCOMP_FILTER
90 select HAVE_ARCH_SOFT_DIRTY if X86_64
91 select HAVE_ARCH_TRACEHOOK
92 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
93 select HAVE_BPF_JIT if X86_64
94 select HAVE_CC_STACKPROTECTOR
95 select HAVE_CMPXCHG_DOUBLE
96 select HAVE_CMPXCHG_LOCAL
97 select HAVE_CONTEXT_TRACKING if X86_64
98 select HAVE_COPY_THREAD_TLS
99 select HAVE_C_RECORDMCOUNT
100 select HAVE_DEBUG_KMEMLEAK
101 select HAVE_DEBUG_STACKOVERFLOW
102 select HAVE_DMA_API_DEBUG
103 select HAVE_DMA_CONTIGUOUS
104 select HAVE_DYNAMIC_FTRACE
105 select HAVE_DYNAMIC_FTRACE_WITH_REGS
106 select HAVE_EFFICIENT_UNALIGNED_ACCESS
107 select HAVE_FENTRY if X86_64
108 select HAVE_FTRACE_MCOUNT_RECORD
109 select HAVE_FUNCTION_GRAPH_FP_TEST
110 select HAVE_FUNCTION_GRAPH_TRACER
111 select HAVE_FUNCTION_TRACER
112 select HAVE_GENERIC_DMA_COHERENT if X86_32
113 select HAVE_HW_BREAKPOINT
115 select HAVE_IOREMAP_PROT
116 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
117 select HAVE_IRQ_TIME_ACCOUNTING
118 select HAVE_KERNEL_BZIP2
119 select HAVE_KERNEL_GZIP
120 select HAVE_KERNEL_LZ4
121 select HAVE_KERNEL_LZMA
122 select HAVE_KERNEL_LZO
123 select HAVE_KERNEL_XZ
125 select HAVE_KPROBES_ON_FTRACE
126 select HAVE_KRETPROBES
128 select HAVE_LIVEPATCH if X86_64
130 select HAVE_MEMBLOCK_NODE_MAP
131 select HAVE_MIXED_BREAKPOINTS_REGS
133 select HAVE_OPTPROBES
134 select HAVE_PCSPKR_PLATFORM
135 select HAVE_PERF_EVENTS
136 select HAVE_PERF_EVENTS_NMI
137 select HAVE_PERF_REGS
138 select HAVE_PERF_USER_STACK_DUMP
139 select HAVE_REGS_AND_STACK_ACCESS_API
140 select HAVE_SYSCALL_TRACEPOINTS
141 select HAVE_UID16 if X86_32 || IA32_EMULATION
142 select HAVE_UNSTABLE_SCHED_CLOCK
143 select HAVE_USER_RETURN_NOTIFIER
144 select IRQ_FORCED_THREADING
145 select MODULES_USE_ELF_RELA if X86_64
146 select MODULES_USE_ELF_REL if X86_32
147 select OLD_SIGACTION if X86_32
148 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
153 select SYSCTL_EXCEPTION_TRACE
154 select USER_STACKTRACE_SUPPORT
156 select X86_DEV_DMA_OPS if X86_64
157 select X86_FEATURE_NAMES if PROC_FS
158 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
159 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
161 config INSTRUCTION_DECODER
163 depends on KPROBES || PERF_EVENTS || UPROBES
165 config PERF_EVENTS_INTEL_UNCORE
167 depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
171 default "elf32-i386" if X86_32
172 default "elf64-x86-64" if X86_64
174 config ARCH_DEFCONFIG
176 default "arch/x86/configs/i386_defconfig" if X86_32
177 default "arch/x86/configs/x86_64_defconfig" if X86_64
179 config LOCKDEP_SUPPORT
182 config STACKTRACE_SUPPORT
188 config ARCH_MMAP_RND_BITS_MIN
192 config ARCH_MMAP_RND_BITS_MAX
196 config ARCH_MMAP_RND_COMPAT_BITS_MIN
199 config ARCH_MMAP_RND_COMPAT_BITS_MAX
205 config NEED_DMA_MAP_STATE
207 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
209 config NEED_SG_DMA_LENGTH
212 config GENERIC_ISA_DMA
214 depends on ISA_DMA_API
219 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
221 config GENERIC_BUG_RELATIVE_POINTERS
224 config GENERIC_HWEIGHT
227 config ARCH_MAY_HAVE_PC_FDC
229 depends on ISA_DMA_API
231 config RWSEM_XCHGADD_ALGORITHM
234 config GENERIC_CALIBRATE_DELAY
237 config ARCH_HAS_CPU_RELAX
240 config ARCH_HAS_CACHE_LINE_SIZE
243 config HAVE_SETUP_PER_CPU_AREA
246 config NEED_PER_CPU_EMBED_FIRST_CHUNK
249 config NEED_PER_CPU_PAGE_FIRST_CHUNK
252 config ARCH_HIBERNATION_POSSIBLE
255 config ARCH_SUSPEND_POSSIBLE
258 config ARCH_WANT_HUGE_PMD_SHARE
261 config ARCH_WANT_GENERAL_HUGETLB
270 config ARCH_SUPPORTS_OPTIMIZED_INLINING
273 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
276 config KASAN_SHADOW_OFFSET
279 default 0xdffffc0000000000
281 config HAVE_INTEL_TXT
283 depends on INTEL_IOMMU && ACPI
287 depends on X86_32 && SMP
291 depends on X86_64 && SMP
293 config X86_32_LAZY_GS
295 depends on X86_32 && !CC_STACKPROTECTOR
297 config ARCH_HWEIGHT_CFLAGS
299 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
300 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
302 config ARCH_SUPPORTS_UPROBES
305 config FIX_EARLYCON_MEM
308 config PGTABLE_LEVELS
314 source "init/Kconfig"
315 source "kernel/Kconfig.freezer"
317 menu "Processor type and features"
320 bool "DMA memory allocation support" if EXPERT
323 DMA memory allocation support allows devices with less than 32-bit
324 addressing to allocate within the first 16MB of address space.
325 Disable if no such devices will be used.
330 bool "Symmetric multi-processing support"
332 This enables support for systems with more than one CPU. If you have
333 a system with only one CPU, say N. If you have a system with more
336 If you say N here, the kernel will run on uni- and multiprocessor
337 machines, but will use only one CPU of a multiprocessor machine. If
338 you say Y here, the kernel will run on many, but not all,
339 uniprocessor machines. On a uniprocessor machine, the kernel
340 will run faster if you say N here.
342 Note that if you say Y here and choose architecture "586" or
343 "Pentium" under "Processor family", the kernel will not work on 486
344 architectures. Similarly, multiprocessor kernels for the "PPro"
345 architecture may not work on all Pentium based boards.
347 People using multiprocessor machines who say Y here should also say
348 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
349 Management" code will be disabled if you say Y here.
351 See also <file:Documentation/x86/i386/IO-APIC.txt>,
352 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
353 <http://www.tldp.org/docs.html#howto>.
355 If you don't know what to do here, say N.
357 config X86_FEATURE_NAMES
358 bool "Processor feature human-readable names" if EMBEDDED
361 This option compiles in a table of x86 feature bits and corresponding
362 names. This is required to support /proc/cpuinfo and a few kernel
363 messages. You can disable this to save space, at the expense of
364 making those few kernel messages show numeric feature bits instead.
368 config X86_FAST_FEATURE_TESTS
369 bool "Fast CPU feature tests" if EMBEDDED
372 Some fast-paths in the kernel depend on the capabilities of the CPU.
373 Say Y here for the kernel to patch in the appropriate code at runtime
374 based on the capabilities of the CPU. The infrastructure for patching
375 code at runtime takes up some additional space; space-constrained
376 embedded systems may wish to say N here to produce smaller, slightly
380 bool "Support x2apic"
381 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
383 This enables x2apic support on CPUs that have this feature.
385 This allows 32-bit apic IDs (so it can support very large systems),
386 and accesses the local apic via MSRs not via mmio.
388 If you don't know what to do here, say N.
391 bool "Enable MPS table" if ACPI || SFI
393 depends on X86_LOCAL_APIC
395 For old smp systems that do not have proper acpi support. Newer systems
396 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
399 bool "Support for big SMP systems with more than 8 CPUs"
400 depends on X86_32 && SMP
402 This option is needed for the systems that have more than 8 CPUs
406 depends on X86_GOLDFISH
409 config X86_EXTENDED_PLATFORM
410 bool "Support for extended (non-PC) x86 platforms"
413 If you disable this option then the kernel will only support
414 standard PC platforms. (which covers the vast majority of
417 If you enable this option then you'll be able to select support
418 for the following (non-PC) 32 bit x86 platforms:
419 Goldfish (Android emulator)
422 SGI 320/540 (Visual Workstation)
423 STA2X11-based (e.g. Northville)
424 Moorestown MID devices
426 If you have one of these systems, or if you want to build a
427 generic distribution kernel, say Y here - otherwise say N.
431 config X86_EXTENDED_PLATFORM
432 bool "Support for extended (non-PC) x86 platforms"
435 If you disable this option then the kernel will only support
436 standard PC platforms. (which covers the vast majority of
439 If you enable this option then you'll be able to select support
440 for the following (non-PC) 64 bit x86 platforms:
445 If you have one of these systems, or if you want to build a
446 generic distribution kernel, say Y here - otherwise say N.
448 # This is an alphabetically sorted list of 64 bit extended platforms
449 # Please maintain the alphabetic order if and when there are additions
451 bool "Numascale NumaChip"
453 depends on X86_EXTENDED_PLATFORM
456 depends on X86_X2APIC
457 depends on PCI_MMCONFIG
459 Adds support for Numascale NumaChip large-SMP systems. Needed to
460 enable more than ~168 cores.
461 If you don't have one of these, you should say N here.
465 select HYPERVISOR_GUEST
467 depends on X86_64 && PCI
468 depends on X86_EXTENDED_PLATFORM
471 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
472 supposed to run on these EM64T-based machines. Only choose this option
473 if you have one of these machines.
476 bool "SGI Ultraviolet"
478 depends on X86_EXTENDED_PLATFORM
481 depends on X86_X2APIC
484 This option is needed in order to support SGI Ultraviolet systems.
485 If you don't have one of these, you should say N here.
487 # Following is an alphabetically sorted list of 32 bit extended platforms
488 # Please maintain the alphabetic order if and when there are additions
491 bool "Goldfish (Virtual Platform)"
492 depends on X86_EXTENDED_PLATFORM
494 Enable support for the Goldfish virtual platform used primarily
495 for Android development. Unless you are building for the Android
496 Goldfish emulator say N here.
499 bool "CE4100 TV platform"
501 depends on PCI_GODIRECT
502 depends on X86_IO_APIC
504 depends on X86_EXTENDED_PLATFORM
505 select X86_REBOOTFIXUPS
507 select OF_EARLY_FLATTREE
509 Select for the Intel CE media processor (CE4100) SOC.
510 This option compiles in support for the CE4100 SOC for settop
511 boxes and media devices.
514 bool "Intel MID platform support"
515 depends on X86_EXTENDED_PLATFORM
516 depends on X86_PLATFORM_DEVICES
518 depends on X86_64 || (PCI_GOANY && X86_32)
519 depends on X86_IO_APIC
525 select MFD_INTEL_MSIC
527 Select to build a kernel capable of supporting Intel MID (Mobile
528 Internet Device) platform systems which do not have the PCI legacy
529 interfaces. If you are building for a PC class system say N here.
531 Intel MID platforms are based on an Intel processor and chipset which
532 consume less power than most of the x86 derivatives.
534 config X86_INTEL_QUARK
535 bool "Intel Quark platform support"
537 depends on X86_EXTENDED_PLATFORM
538 depends on X86_PLATFORM_DEVICES
542 depends on X86_IO_APIC
547 Select to include support for Quark X1000 SoC.
548 Say Y here if you have a Quark based system such as the Arduino
549 compatible Intel Galileo.
551 config X86_INTEL_LPSS
552 bool "Intel Low Power Subsystem Support"
553 depends on X86 && ACPI
558 Select to build support for Intel Low Power Subsystem such as
559 found on Intel Lynxpoint PCH. Selecting this option enables
560 things like clock tree (common clock framework) and pincontrol
561 which are needed by the LPSS peripheral drivers.
563 config X86_AMD_PLATFORM_DEVICE
564 bool "AMD ACPI2Platform devices support"
569 Select to interpret AMD specific ACPI device to platform device
570 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
571 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
572 implemented under PINCTRL subsystem.
575 tristate "Intel SoC IOSF Sideband support for SoC platforms"
578 This option enables sideband register access support for Intel SoC
579 platforms. On these platforms the IOSF sideband is used in lieu of
580 MSR's for some register accesses, mostly but not limited to thermal
581 and power. Drivers may query the availability of this device to
582 determine if they need the sideband in order to work on these
583 platforms. The sideband is available on the following SoC products.
584 This list is not meant to be exclusive.
589 You should say Y if you are running a kernel on one of these SoC's.
591 config IOSF_MBI_DEBUG
592 bool "Enable IOSF sideband access through debugfs"
593 depends on IOSF_MBI && DEBUG_FS
595 Select this option to expose the IOSF sideband access registers (MCR,
596 MDR, MCRX) through debugfs to write and read register information from
597 different units on the SoC. This is most useful for obtaining device
598 state information for debug and analysis. As this is a general access
599 mechanism, users of this option would have specific knowledge of the
600 device they want to access.
602 If you don't require the option or are in doubt, say N.
605 bool "RDC R-321x SoC"
607 depends on X86_EXTENDED_PLATFORM
609 select X86_REBOOTFIXUPS
611 This option is needed for RDC R-321x system-on-chip, also known
613 If you don't have one of these chips, you should say N here.
615 config X86_32_NON_STANDARD
616 bool "Support non-standard 32-bit SMP architectures"
617 depends on X86_32 && SMP
618 depends on X86_EXTENDED_PLATFORM
620 This option compiles in the bigsmp and STA2X11 default
621 subarchitectures. It is intended for a generic binary
622 kernel. If you select them all, kernel will probe it one by
623 one and will fallback to default.
625 # Alphabetically sorted list of Non standard 32 bit platforms
627 config X86_SUPPORTS_MEMORY_FAILURE
629 # MCE code calls memory_failure():
631 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
632 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
633 depends on X86_64 || !SPARSEMEM
634 select ARCH_SUPPORTS_MEMORY_FAILURE
637 bool "STA2X11 Companion Chip Support"
638 depends on X86_32_NON_STANDARD && PCI
639 select X86_DEV_DMA_OPS
643 select ARCH_REQUIRE_GPIOLIB
646 This adds support for boards based on the STA2X11 IO-Hub,
647 a.k.a. "ConneXt". The chip is used in place of the standard
648 PC chipset, so all "standard" peripherals are missing. If this
649 option is selected the kernel will still be able to boot on
650 standard PC machines.
653 tristate "Eurobraille/Iris poweroff module"
656 The Iris machines from EuroBraille do not have APM or ACPI support
657 to shut themselves down properly. A special I/O sequence is
658 needed to do so, which is what this module does at
661 This is only for Iris machines from EuroBraille.
665 config SCHED_OMIT_FRAME_POINTER
667 prompt "Single-depth WCHAN output"
670 Calculate simpler /proc/<PID>/wchan values. If this option
671 is disabled then wchan values will recurse back to the
672 caller function. This provides more accurate wchan values,
673 at the expense of slightly more scheduling overhead.
675 If in doubt, say "Y".
677 menuconfig HYPERVISOR_GUEST
678 bool "Linux guest support"
680 Say Y here to enable options for running Linux under various hyper-
681 visors. This option enables basic hypervisor detection and platform
684 If you say N, all options in this submenu will be skipped and
685 disabled, and Linux guest support won't be built in.
690 bool "Enable paravirtualization code"
692 This changes the kernel so it can modify itself when it is run
693 under a hypervisor, potentially improving performance significantly
694 over full virtualization. However, when run without a hypervisor
695 the kernel is theoretically slower and slightly larger.
697 config PARAVIRT_DEBUG
698 bool "paravirt-ops debugging"
699 depends on PARAVIRT && DEBUG_KERNEL
701 Enable to debug paravirt_ops internals. Specifically, BUG if
702 a paravirt_op is missing when it is called.
704 config PARAVIRT_SPINLOCKS
705 bool "Paravirtualization layer for spinlocks"
706 depends on PARAVIRT && SMP
707 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
709 Paravirtualized spinlocks allow a pvops backend to replace the
710 spinlock implementation with something virtualization-friendly
711 (for example, block the virtual CPU rather than spinning).
713 It has a minimal impact on native kernels and gives a nice performance
714 benefit on paravirtualized KVM / Xen kernels.
716 If you are unsure how to answer this question, answer Y.
718 config QUEUED_LOCK_STAT
719 bool "Paravirt queued spinlock statistics"
720 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
722 Enable the collection of statistical data on the slowpath
723 behavior of paravirtualized queued spinlocks and report
726 source "arch/x86/xen/Kconfig"
729 bool "KVM Guest support (including kvmclock)"
731 select PARAVIRT_CLOCK
734 This option enables various optimizations for running under the KVM
735 hypervisor. It includes a paravirtualized clock, so that instead
736 of relying on a PIT (or probably other) emulation by the
737 underlying device model, the host provides the guest with
738 timing infrastructure such as time of day, and system time
741 bool "Enable debug information for KVM Guests in debugfs"
742 depends on KVM_GUEST && DEBUG_FS
745 This option enables collection of various statistics for KVM guest.
746 Statistics are displayed in debugfs filesystem. Enabling this option
747 may incur significant overhead.
749 source "arch/x86/lguest/Kconfig"
751 config PARAVIRT_TIME_ACCOUNTING
752 bool "Paravirtual steal time accounting"
756 Select this option to enable fine granularity task steal time
757 accounting. Time spent executing other tasks in parallel with
758 the current vCPU is discounted from the vCPU power. To account for
759 that, there can be a small performance impact.
761 If in doubt, say N here.
763 config PARAVIRT_CLOCK
766 endif #HYPERVISOR_GUEST
771 source "arch/x86/Kconfig.cpu"
775 prompt "HPET Timer Support" if X86_32
777 Use the IA-PC HPET (High Precision Event Timer) to manage
778 time in preference to the PIT and RTC, if a HPET is
780 HPET is the next generation timer replacing legacy 8254s.
781 The HPET provides a stable time base on SMP
782 systems, unlike the TSC, but it is more expensive to access,
783 as it is off-chip. You can find the HPET spec at
784 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
786 You can safely choose Y here. However, HPET will only be
787 activated if the platform and the BIOS support this feature.
788 Otherwise the 8254 will be used for timing services.
790 Choose N to continue using the legacy 8254 timer.
792 config HPET_EMULATE_RTC
794 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
797 def_bool y if X86_INTEL_MID
798 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
800 depends on X86_INTEL_MID && SFI
802 APB timer is the replacement for 8254, HPET on X86 MID platforms.
803 The APBT provides a stable time base on SMP
804 systems, unlike the TSC, but it is more expensive to access,
805 as it is off-chip. APB timers are always running regardless of CPU
806 C states, they are used as per CPU clockevent device when possible.
808 # Mark as expert because too many people got it wrong.
809 # The code disables itself when not needed.
812 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
813 bool "Enable DMI scanning" if EXPERT
815 Enabled scanning of DMI to identify machine quirks. Say Y
816 here unless you have verified that your setup is not
817 affected by entries in the DMI blacklist. Required by PNP
821 bool "Old AMD GART IOMMU support"
823 depends on X86_64 && PCI && AMD_NB
825 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
826 GART based hardware IOMMUs.
828 The GART supports full DMA access for devices with 32-bit access
829 limitations, on systems with more than 3 GB. This is usually needed
830 for USB, sound, many IDE/SATA chipsets and some other devices.
832 Newer systems typically have a modern AMD IOMMU, supported via
833 the CONFIG_AMD_IOMMU=y config option.
835 In normal configurations this driver is only active when needed:
836 there's more than 3 GB of memory and the system contains a
837 32-bit limited device.
842 bool "IBM Calgary IOMMU support"
844 depends on X86_64 && PCI
846 Support for hardware IOMMUs in IBM's xSeries x366 and x460
847 systems. Needed to run systems with more than 3GB of memory
848 properly with 32-bit PCI devices that do not support DAC
849 (Double Address Cycle). Calgary also supports bus level
850 isolation, where all DMAs pass through the IOMMU. This
851 prevents them from going anywhere except their intended
852 destination. This catches hard-to-find kernel bugs and
853 mis-behaving drivers and devices that do not use the DMA-API
854 properly to set up their DMA buffers. The IOMMU can be
855 turned off at boot time with the iommu=off parameter.
856 Normally the kernel will make the right choice by itself.
859 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
861 prompt "Should Calgary be enabled by default?"
862 depends on CALGARY_IOMMU
864 Should Calgary be enabled by default? if you choose 'y', Calgary
865 will be used (if it exists). If you choose 'n', Calgary will not be
866 used even if it exists. If you choose 'n' and would like to use
867 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
870 # need this always selected by IOMMU for the VIA workaround
874 Support for software bounce buffers used on x86-64 systems
875 which don't have a hardware IOMMU. Using this PCI devices
876 which can only access 32-bits of memory can be used on systems
877 with more than 3 GB of memory.
882 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
885 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
886 depends on X86_64 && SMP && DEBUG_KERNEL
887 select CPUMASK_OFFSTACK
889 Enable maximum number of CPUS and NUMA Nodes for this architecture.
893 int "Maximum number of CPUs" if SMP && !MAXSMP
894 range 2 8 if SMP && X86_32 && !X86_BIGSMP
895 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
896 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
898 default "8192" if MAXSMP
899 default "32" if SMP && X86_BIGSMP
900 default "8" if SMP && X86_32
903 This allows you to specify the maximum number of CPUs which this
904 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
905 supported value is 8192, otherwise the maximum value is 512. The
906 minimum value which makes sense is 2.
908 This is purely to save memory - each supported CPU adds
909 approximately eight kilobytes to the kernel image.
912 bool "SMT (Hyperthreading) scheduler support"
915 SMT scheduler support improves the CPU scheduler's decision making
916 when dealing with Intel Pentium 4 chips with HyperThreading at a
917 cost of slightly increased overhead in some places. If unsure say
922 prompt "Multi-core scheduler support"
925 Multi-core scheduler support improves the CPU scheduler's decision
926 making when dealing with multi-core CPU chips at a cost of slightly
927 increased overhead in some places. If unsure say N here.
929 source "kernel/Kconfig.preempt"
933 depends on !SMP && X86_LOCAL_APIC
936 bool "Local APIC support on uniprocessors" if !PCI_MSI
938 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
940 A local APIC (Advanced Programmable Interrupt Controller) is an
941 integrated interrupt controller in the CPU. If you have a single-CPU
942 system which has a processor with a local APIC, you can say Y here to
943 enable and use it. If you say Y here even though your machine doesn't
944 have a local APIC, then the kernel will still run with no slowdown at
945 all. The local APIC supports CPU-generated self-interrupts (timer,
946 performance counters), and the NMI watchdog which detects hard
950 bool "IO-APIC support on uniprocessors"
951 depends on X86_UP_APIC
953 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
954 SMP-capable replacement for PC-style interrupt controllers. Most
955 SMP systems and many recent uniprocessor systems have one.
957 If you have a single-CPU system with an IO-APIC, you can say Y here
958 to use it. If you say Y here even though your machine doesn't have
959 an IO-APIC, then the kernel will still run with no slowdown at all.
961 config X86_LOCAL_APIC
963 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
964 select IRQ_DOMAIN_HIERARCHY
965 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
969 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
971 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
972 bool "Reroute for broken boot IRQs"
973 depends on X86_IO_APIC
975 This option enables a workaround that fixes a source of
976 spurious interrupts. This is recommended when threaded
977 interrupt handling is used on systems where the generation of
978 superfluous "boot interrupts" cannot be disabled.
980 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
981 entry in the chipset's IO-APIC is masked (as, e.g. the RT
982 kernel does during interrupt handling). On chipsets where this
983 boot IRQ generation cannot be disabled, this workaround keeps
984 the original IRQ line masked so that only the equivalent "boot
985 IRQ" is delivered to the CPUs. The workaround also tells the
986 kernel to set up the IRQ handler on the boot IRQ line. In this
987 way only one interrupt is delivered to the kernel. Otherwise
988 the spurious second interrupt may cause the kernel to bring
989 down (vital) interrupt lines.
991 Only affects "broken" chipsets. Interrupt sharing may be
992 increased on these systems.
995 bool "Machine Check / overheating reporting"
996 select GENERIC_ALLOCATOR
999 Machine Check support allows the processor to notify the
1000 kernel if it detects a problem (e.g. overheating, data corruption).
1001 The action the kernel takes depends on the severity of the problem,
1002 ranging from warning messages to halting the machine.
1004 config X86_MCE_INTEL
1006 prompt "Intel MCE features"
1007 depends on X86_MCE && X86_LOCAL_APIC
1009 Additional support for intel specific MCE features such as
1010 the thermal monitor.
1014 prompt "AMD MCE features"
1015 depends on X86_MCE && X86_LOCAL_APIC
1017 Additional support for AMD specific MCE features such as
1018 the DRAM Error Threshold.
1020 config X86_ANCIENT_MCE
1021 bool "Support for old Pentium 5 / WinChip machine checks"
1022 depends on X86_32 && X86_MCE
1024 Include support for machine check handling on old Pentium 5 or WinChip
1025 systems. These typically need to be enabled explicitly on the command
1028 config X86_MCE_THRESHOLD
1029 depends on X86_MCE_AMD || X86_MCE_INTEL
1032 config X86_MCE_INJECT
1034 tristate "Machine check injector support"
1036 Provide support for injecting machine checks for testing purposes.
1037 If you don't know what a machine check is and you don't do kernel
1038 QA it is safe to say n.
1040 config X86_THERMAL_VECTOR
1042 depends on X86_MCE_INTEL
1044 config X86_LEGACY_VM86
1045 bool "Legacy VM86 support"
1049 This option allows user programs to put the CPU into V8086
1050 mode, which is an 80286-era approximation of 16-bit real mode.
1052 Some very old versions of X and/or vbetool require this option
1053 for user mode setting. Similarly, DOSEMU will use it if
1054 available to accelerate real mode DOS programs. However, any
1055 recent version of DOSEMU, X, or vbetool should be fully
1056 functional even without kernel VM86 support, as they will all
1057 fall back to software emulation. Nevertheless, if you are using
1058 a 16-bit DOS program where 16-bit performance matters, vm86
1059 mode might be faster than emulation and you might want to
1062 Note that any app that works on a 64-bit kernel is unlikely to
1063 need this option, as 64-bit kernels don't, and can't, support
1064 V8086 mode. This option is also unrelated to 16-bit protected
1065 mode and is not needed to run most 16-bit programs under Wine.
1067 Enabling this option increases the complexity of the kernel
1068 and slows down exception handling a tiny bit.
1070 If unsure, say N here.
1074 default X86_LEGACY_VM86
1077 bool "Enable support for 16-bit segments" if EXPERT
1079 depends on MODIFY_LDT_SYSCALL
1081 This option is required by programs like Wine to run 16-bit
1082 protected mode legacy code on x86 processors. Disabling
1083 this option saves about 300 bytes on i386, or around 6K text
1084 plus 16K runtime memory on x86-64,
1088 depends on X86_16BIT && X86_32
1092 depends on X86_16BIT && X86_64
1094 config X86_VSYSCALL_EMULATION
1095 bool "Enable vsyscall emulation" if EXPERT
1099 This enables emulation of the legacy vsyscall page. Disabling
1100 it is roughly equivalent to booting with vsyscall=none, except
1101 that it will also disable the helpful warning if a program
1102 tries to use a vsyscall. With this option set to N, offending
1103 programs will just segfault, citing addresses of the form
1106 This option is required by many programs built before 2013, and
1107 care should be used even with newer programs if set to N.
1109 Disabling this option saves about 7K of kernel size and
1110 possibly 4K of additional runtime pagetable memory.
1113 tristate "Toshiba Laptop support"
1116 This adds a driver to safely access the System Management Mode of
1117 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1118 not work on models with a Phoenix BIOS. The System Management Mode
1119 is used to set the BIOS and power saving options on Toshiba portables.
1121 For information on utilities to make use of this driver see the
1122 Toshiba Linux utilities web site at:
1123 <http://www.buzzard.org.uk/toshiba/>.
1125 Say Y if you intend to run this kernel on a Toshiba portable.
1129 tristate "Dell i8k legacy laptop support"
1131 select SENSORS_DELL_SMM
1133 This option enables legacy /proc/i8k userspace interface in hwmon
1134 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1135 temperature and allows controlling fan speeds of Dell laptops via
1136 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1137 it reports also power and hotkey status. For fan speed control is
1138 needed userspace package i8kutils.
1140 Say Y if you intend to run this kernel on old Dell laptops or want to
1141 use userspace package i8kutils.
1144 config X86_REBOOTFIXUPS
1145 bool "Enable X86 board specific fixups for reboot"
1148 This enables chipset and/or board specific fixups to be done
1149 in order to get reboot to work correctly. This is only needed on
1150 some combinations of hardware and BIOS. The symptom, for which
1151 this config is intended, is when reboot ends with a stalled/hung
1154 Currently, the only fixup is for the Geode machines using
1155 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1157 Say Y if you want to enable the fixup. Currently, it's safe to
1158 enable this option even if you don't need it.
1162 bool "CPU microcode loading support"
1164 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1165 depends on BLK_DEV_INITRD
1169 If you say Y here, you will be able to update the microcode on
1170 certain Intel and AMD processors. The Intel support is for the
1171 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1172 Xeon etc. The AMD support is for families 0x10 and later. You will
1173 obviously need the actual microcode binary data itself which is not
1174 shipped with the Linux kernel.
1176 This option selects the general module only, you need to select
1177 at least one vendor specific module as well.
1179 To compile this driver as a module, choose M here: the module
1180 will be called microcode.
1182 config MICROCODE_INTEL
1183 bool "Intel microcode loading support"
1184 depends on MICROCODE
1188 This options enables microcode patch loading support for Intel
1191 For the current Intel microcode data package go to
1192 <https://downloadcenter.intel.com> and search for
1193 'Linux Processor Microcode Data File'.
1195 config MICROCODE_AMD
1196 bool "AMD microcode loading support"
1197 depends on MICROCODE
1200 If you select this option, microcode patch loading support for AMD
1201 processors will be enabled.
1203 config MICROCODE_OLD_INTERFACE
1205 depends on MICROCODE
1208 tristate "/dev/cpu/*/msr - Model-specific register support"
1210 This device gives privileged processes access to the x86
1211 Model-Specific Registers (MSRs). It is a character device with
1212 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1213 MSR accesses are directed to a specific CPU on multi-processor
1217 tristate "/dev/cpu/*/cpuid - CPU information support"
1219 This device gives processes access to the x86 CPUID instruction to
1220 be executed on a specific processor. It is a character device
1221 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1225 prompt "High Memory Support"
1232 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1233 However, the address space of 32-bit x86 processors is only 4
1234 Gigabytes large. That means that, if you have a large amount of
1235 physical memory, not all of it can be "permanently mapped" by the
1236 kernel. The physical memory that's not permanently mapped is called
1239 If you are compiling a kernel which will never run on a machine with
1240 more than 1 Gigabyte total physical RAM, answer "off" here (default
1241 choice and suitable for most users). This will result in a "3GB/1GB"
1242 split: 3GB are mapped so that each process sees a 3GB virtual memory
1243 space and the remaining part of the 4GB virtual memory space is used
1244 by the kernel to permanently map as much physical memory as
1247 If the machine has between 1 and 4 Gigabytes physical RAM, then
1250 If more than 4 Gigabytes is used then answer "64GB" here. This
1251 selection turns Intel PAE (Physical Address Extension) mode on.
1252 PAE implements 3-level paging on IA32 processors. PAE is fully
1253 supported by Linux, PAE mode is implemented on all recent Intel
1254 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1255 then the kernel will not boot on CPUs that don't support PAE!
1257 The actual amount of total physical memory will either be
1258 auto detected or can be forced by using a kernel command line option
1259 such as "mem=256M". (Try "man bootparam" or see the documentation of
1260 your boot loader (lilo or loadlin) about how to pass options to the
1261 kernel at boot time.)
1263 If unsure, say "off".
1268 Select this if you have a 32-bit processor and between 1 and 4
1269 gigabytes of physical RAM.
1276 Select this if you have a 32-bit processor and more than 4
1277 gigabytes of physical RAM.
1282 prompt "Memory split" if EXPERT
1286 Select the desired split between kernel and user memory.
1288 If the address range available to the kernel is less than the
1289 physical memory installed, the remaining memory will be available
1290 as "high memory". Accessing high memory is a little more costly
1291 than low memory, as it needs to be mapped into the kernel first.
1292 Note that increasing the kernel address space limits the range
1293 available to user programs, making the address space there
1294 tighter. Selecting anything other than the default 3G/1G split
1295 will also likely make your kernel incompatible with binary-only
1298 If you are not absolutely sure what you are doing, leave this
1302 bool "3G/1G user/kernel split"
1303 config VMSPLIT_3G_OPT
1305 bool "3G/1G user/kernel split (for full 1G low memory)"
1307 bool "2G/2G user/kernel split"
1308 config VMSPLIT_2G_OPT
1310 bool "2G/2G user/kernel split (for full 2G low memory)"
1312 bool "1G/3G user/kernel split"
1317 default 0xB0000000 if VMSPLIT_3G_OPT
1318 default 0x80000000 if VMSPLIT_2G
1319 default 0x78000000 if VMSPLIT_2G_OPT
1320 default 0x40000000 if VMSPLIT_1G
1326 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1329 bool "PAE (Physical Address Extension) Support"
1330 depends on X86_32 && !HIGHMEM4G
1333 PAE is required for NX support, and furthermore enables
1334 larger swapspace support for non-overcommit purposes. It
1335 has the cost of more pagetable lookup overhead, and also
1336 consumes more pagetable space per process.
1338 config ARCH_PHYS_ADDR_T_64BIT
1340 depends on X86_64 || X86_PAE
1342 config ARCH_DMA_ADDR_T_64BIT
1344 depends on X86_64 || HIGHMEM64G
1346 config X86_DIRECT_GBPAGES
1348 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1350 Certain kernel features effectively disable kernel
1351 linear 1 GB mappings (even if the CPU otherwise
1352 supports them), so don't confuse the user by printing
1353 that we have them enabled.
1355 # Common NUMA Features
1357 bool "Numa Memory Allocation and Scheduler Support"
1359 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1360 default y if X86_BIGSMP
1362 Enable NUMA (Non Uniform Memory Access) support.
1364 The kernel will try to allocate memory used by a CPU on the
1365 local memory controller of the CPU and add some more
1366 NUMA awareness to the kernel.
1368 For 64-bit this is recommended if the system is Intel Core i7
1369 (or later), AMD Opteron, or EM64T NUMA.
1371 For 32-bit this is only needed if you boot a 32-bit
1372 kernel on a 64-bit NUMA platform.
1374 Otherwise, you should say N.
1378 prompt "Old style AMD Opteron NUMA detection"
1379 depends on X86_64 && NUMA && PCI
1381 Enable AMD NUMA node topology detection. You should say Y here if
1382 you have a multi processor AMD system. This uses an old method to
1383 read the NUMA configuration directly from the builtin Northbridge
1384 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1385 which also takes priority if both are compiled in.
1387 config X86_64_ACPI_NUMA
1389 prompt "ACPI NUMA detection"
1390 depends on X86_64 && NUMA && ACPI && PCI
1393 Enable ACPI SRAT based node topology detection.
1395 # Some NUMA nodes have memory ranges that span
1396 # other nodes. Even though a pfn is valid and
1397 # between a node's start and end pfns, it may not
1398 # reside on that node. See memmap_init_zone()
1400 config NODES_SPAN_OTHER_NODES
1402 depends on X86_64_ACPI_NUMA
1405 bool "NUMA emulation"
1408 Enable NUMA emulation. A flat machine will be split
1409 into virtual nodes when booted with "numa=fake=N", where N is the
1410 number of nodes. This is only useful for debugging.
1413 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1415 default "10" if MAXSMP
1416 default "6" if X86_64
1418 depends on NEED_MULTIPLE_NODES
1420 Specify the maximum number of NUMA Nodes available on the target
1421 system. Increases memory reserved to accommodate various tables.
1423 config ARCH_HAVE_MEMORY_PRESENT
1425 depends on X86_32 && DISCONTIGMEM
1427 config NEED_NODE_MEMMAP_SIZE
1429 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1431 config ARCH_FLATMEM_ENABLE
1433 depends on X86_32 && !NUMA
1435 config ARCH_DISCONTIGMEM_ENABLE
1437 depends on NUMA && X86_32
1439 config ARCH_DISCONTIGMEM_DEFAULT
1441 depends on NUMA && X86_32
1443 config ARCH_SPARSEMEM_ENABLE
1445 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1446 select SPARSEMEM_STATIC if X86_32
1447 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1449 config ARCH_SPARSEMEM_DEFAULT
1453 config ARCH_SELECT_MEMORY_MODEL
1455 depends on ARCH_SPARSEMEM_ENABLE
1457 config ARCH_MEMORY_PROBE
1458 bool "Enable sysfs memory/probe interface"
1459 depends on X86_64 && MEMORY_HOTPLUG
1461 This option enables a sysfs memory/probe interface for testing.
1462 See Documentation/memory-hotplug.txt for more information.
1463 If you are unsure how to answer this question, answer N.
1465 config ARCH_PROC_KCORE_TEXT
1467 depends on X86_64 && PROC_KCORE
1469 config ILLEGAL_POINTER_VALUE
1472 default 0xdead000000000000 if X86_64
1476 config X86_PMEM_LEGACY_DEVICE
1479 config X86_PMEM_LEGACY
1480 tristate "Support non-standard NVDIMMs and ADR protected memory"
1481 depends on PHYS_ADDR_T_64BIT
1483 select X86_PMEM_LEGACY_DEVICE
1486 Treat memory marked using the non-standard e820 type of 12 as used
1487 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1488 The kernel will offer these regions to the 'pmem' driver so
1489 they can be used for persistent storage.
1494 bool "Allocate 3rd-level pagetables from highmem"
1497 The VM uses one page table entry for each page of physical memory.
1498 For systems with a lot of RAM, this can be wasteful of precious
1499 low memory. Setting this option will put user-space page table
1500 entries in high memory.
1502 config X86_CHECK_BIOS_CORRUPTION
1503 bool "Check for low memory corruption"
1505 Periodically check for memory corruption in low memory, which
1506 is suspected to be caused by BIOS. Even when enabled in the
1507 configuration, it is disabled at runtime. Enable it by
1508 setting "memory_corruption_check=1" on the kernel command
1509 line. By default it scans the low 64k of memory every 60
1510 seconds; see the memory_corruption_check_size and
1511 memory_corruption_check_period parameters in
1512 Documentation/kernel-parameters.txt to adjust this.
1514 When enabled with the default parameters, this option has
1515 almost no overhead, as it reserves a relatively small amount
1516 of memory and scans it infrequently. It both detects corruption
1517 and prevents it from affecting the running system.
1519 It is, however, intended as a diagnostic tool; if repeatable
1520 BIOS-originated corruption always affects the same memory,
1521 you can use memmap= to prevent the kernel from using that
1524 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1525 bool "Set the default setting of memory_corruption_check"
1526 depends on X86_CHECK_BIOS_CORRUPTION
1529 Set whether the default state of memory_corruption_check is
1532 config X86_RESERVE_LOW
1533 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1537 Specify the amount of low memory to reserve for the BIOS.
1539 The first page contains BIOS data structures that the kernel
1540 must not use, so that page must always be reserved.
1542 By default we reserve the first 64K of physical RAM, as a
1543 number of BIOSes are known to corrupt that memory range
1544 during events such as suspend/resume or monitor cable
1545 insertion, so it must not be used by the kernel.
1547 You can set this to 4 if you are absolutely sure that you
1548 trust the BIOS to get all its memory reservations and usages
1549 right. If you know your BIOS have problems beyond the
1550 default 64K area, you can set this to 640 to avoid using the
1551 entire low memory range.
1553 If you have doubts about the BIOS (e.g. suspend/resume does
1554 not work or there's kernel crashes after certain hardware
1555 hotplug events) then you might want to enable
1556 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1557 typical corruption patterns.
1559 Leave this to the default value of 64 if you are unsure.
1561 config MATH_EMULATION
1563 depends on MODIFY_LDT_SYSCALL
1564 prompt "Math emulation" if X86_32
1566 Linux can emulate a math coprocessor (used for floating point
1567 operations) if you don't have one. 486DX and Pentium processors have
1568 a math coprocessor built in, 486SX and 386 do not, unless you added
1569 a 487DX or 387, respectively. (The messages during boot time can
1570 give you some hints here ["man dmesg"].) Everyone needs either a
1571 coprocessor or this emulation.
1573 If you don't have a math coprocessor, you need to say Y here; if you
1574 say Y here even though you have a coprocessor, the coprocessor will
1575 be used nevertheless. (This behavior can be changed with the kernel
1576 command line option "no387", which comes handy if your coprocessor
1577 is broken. Try "man bootparam" or see the documentation of your boot
1578 loader (lilo or loadlin) about how to pass options to the kernel at
1579 boot time.) This means that it is a good idea to say Y here if you
1580 intend to use this kernel on different machines.
1582 More information about the internals of the Linux math coprocessor
1583 emulation can be found in <file:arch/x86/math-emu/README>.
1585 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1586 kernel, it won't hurt.
1590 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1592 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1593 the Memory Type Range Registers (MTRRs) may be used to control
1594 processor access to memory ranges. This is most useful if you have
1595 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1596 allows bus write transfers to be combined into a larger transfer
1597 before bursting over the PCI/AGP bus. This can increase performance
1598 of image write operations 2.5 times or more. Saying Y here creates a
1599 /proc/mtrr file which may be used to manipulate your processor's
1600 MTRRs. Typically the X server should use this.
1602 This code has a reasonably generic interface so that similar
1603 control registers on other processors can be easily supported
1606 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1607 Registers (ARRs) which provide a similar functionality to MTRRs. For
1608 these, the ARRs are used to emulate the MTRRs.
1609 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1610 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1611 write-combining. All of these processors are supported by this code
1612 and it makes sense to say Y here if you have one of them.
1614 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1615 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1616 can lead to all sorts of problems, so it's good to say Y here.
1618 You can safely say Y even if your machine doesn't have MTRRs, you'll
1619 just add about 9 KB to your kernel.
1621 See <file:Documentation/x86/mtrr.txt> for more information.
1623 config MTRR_SANITIZER
1625 prompt "MTRR cleanup support"
1628 Convert MTRR layout from continuous to discrete, so X drivers can
1629 add writeback entries.
1631 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1632 The largest mtrr entry size for a continuous block can be set with
1637 config MTRR_SANITIZER_ENABLE_DEFAULT
1638 int "MTRR cleanup enable value (0-1)"
1641 depends on MTRR_SANITIZER
1643 Enable mtrr cleanup default value
1645 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1646 int "MTRR cleanup spare reg num (0-7)"
1649 depends on MTRR_SANITIZER
1651 mtrr cleanup spare entries default, it can be changed via
1652 mtrr_spare_reg_nr=N on the kernel command line.
1656 prompt "x86 PAT support" if EXPERT
1659 Use PAT attributes to setup page level cache control.
1661 PATs are the modern equivalents of MTRRs and are much more
1662 flexible than MTRRs.
1664 Say N here if you see bootup problems (boot crash, boot hang,
1665 spontaneous reboots) or a non-working video driver.
1669 config ARCH_USES_PG_UNCACHED
1675 prompt "x86 architectural random number generator" if EXPERT
1677 Enable the x86 architectural RDRAND instruction
1678 (Intel Bull Mountain technology) to generate random numbers.
1679 If supported, this is a high bandwidth, cryptographically
1680 secure hardware random number generator.
1684 prompt "Supervisor Mode Access Prevention" if EXPERT
1686 Supervisor Mode Access Prevention (SMAP) is a security
1687 feature in newer Intel processors. There is a small
1688 performance cost if this enabled and turned on; there is
1689 also a small increase in the kernel size if this is enabled.
1693 config X86_INTEL_MPX
1694 prompt "Intel MPX (Memory Protection Extensions)"
1696 depends on CPU_SUP_INTEL
1698 MPX provides hardware features that can be used in
1699 conjunction with compiler-instrumented code to check
1700 memory references. It is designed to detect buffer
1701 overflow or underflow bugs.
1703 This option enables running applications which are
1704 instrumented or otherwise use MPX. It does not use MPX
1705 itself inside the kernel or to protect the kernel
1706 against bad memory references.
1708 Enabling this option will make the kernel larger:
1709 ~8k of kernel text and 36 bytes of data on a 64-bit
1710 defconfig. It adds a long to the 'mm_struct' which
1711 will increase the kernel memory overhead of each
1712 process and adds some branches to paths used during
1713 exec() and munmap().
1715 For details, see Documentation/x86/intel_mpx.txt
1719 config X86_INTEL_MEMORY_PROTECTION_KEYS
1720 prompt "Intel Memory Protection Keys"
1722 # Note: only available in 64-bit mode
1723 depends on CPU_SUP_INTEL && X86_64
1725 Memory Protection Keys provides a mechanism for enforcing
1726 page-based protections, but without requiring modification of the
1727 page tables when an application changes protection domains.
1729 For details, see Documentation/x86/protection-keys.txt
1734 bool "EFI runtime service support"
1737 select EFI_RUNTIME_WRAPPERS
1739 This enables the kernel to use EFI runtime services that are
1740 available (such as the EFI variable services).
1742 This option is only useful on systems that have EFI firmware.
1743 In addition, you should use the latest ELILO loader available
1744 at <http://elilo.sourceforge.net> in order to take advantage
1745 of EFI runtime services. However, even with this option, the
1746 resultant kernel should continue to boot on existing non-EFI
1750 bool "EFI stub support"
1751 depends on EFI && !X86_USE_3DNOW
1754 This kernel feature allows a bzImage to be loaded directly
1755 by EFI firmware without the use of a bootloader.
1757 See Documentation/efi-stub.txt for more information.
1760 bool "EFI mixed-mode support"
1761 depends on EFI_STUB && X86_64
1763 Enabling this feature allows a 64-bit kernel to be booted
1764 on a 32-bit firmware, provided that your CPU supports 64-bit
1767 Note that it is not possible to boot a mixed-mode enabled
1768 kernel via the EFI boot stub - a bootloader that supports
1769 the EFI handover protocol must be used.
1775 prompt "Enable seccomp to safely compute untrusted bytecode"
1777 This kernel feature is useful for number crunching applications
1778 that may need to compute untrusted bytecode during their
1779 execution. By using pipes or other transports made available to
1780 the process as file descriptors supporting the read/write
1781 syscalls, it's possible to isolate those applications in
1782 their own address space using seccomp. Once seccomp is
1783 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1784 and the task is only allowed to execute a few safe syscalls
1785 defined by each seccomp mode.
1787 If unsure, say Y. Only embedded should say N here.
1789 source kernel/Kconfig.hz
1792 bool "kexec system call"
1795 kexec is a system call that implements the ability to shutdown your
1796 current kernel, and to start another kernel. It is like a reboot
1797 but it is independent of the system firmware. And like a reboot
1798 you can start any kernel with it, not just Linux.
1800 The name comes from the similarity to the exec system call.
1802 It is an ongoing process to be certain the hardware in a machine
1803 is properly shutdown, so do not be surprised if this code does not
1804 initially work for you. As of this writing the exact hardware
1805 interface is strongly in flux, so no good recommendation can be
1809 bool "kexec file based system call"
1814 depends on CRYPTO_SHA256=y
1816 This is new version of kexec system call. This system call is
1817 file based and takes file descriptors as system call argument
1818 for kernel and initramfs as opposed to list of segments as
1819 accepted by previous system call.
1821 config KEXEC_VERIFY_SIG
1822 bool "Verify kernel signature during kexec_file_load() syscall"
1823 depends on KEXEC_FILE
1825 This option makes kernel signature verification mandatory for
1826 the kexec_file_load() syscall.
1828 In addition to that option, you need to enable signature
1829 verification for the corresponding kernel image type being
1830 loaded in order for this to work.
1832 config KEXEC_BZIMAGE_VERIFY_SIG
1833 bool "Enable bzImage signature verification support"
1834 depends on KEXEC_VERIFY_SIG
1835 depends on SIGNED_PE_FILE_VERIFICATION
1836 select SYSTEM_TRUSTED_KEYRING
1838 Enable bzImage signature verification support.
1841 bool "kernel crash dumps"
1842 depends on X86_64 || (X86_32 && HIGHMEM)
1844 Generate crash dump after being started by kexec.
1845 This should be normally only set in special crash dump kernels
1846 which are loaded in the main kernel with kexec-tools into
1847 a specially reserved region and then later executed after
1848 a crash by kdump/kexec. The crash dump kernel must be compiled
1849 to a memory address not used by the main kernel or BIOS using
1850 PHYSICAL_START, or it must be built as a relocatable image
1851 (CONFIG_RELOCATABLE=y).
1852 For more details see Documentation/kdump/kdump.txt
1856 depends on KEXEC && HIBERNATION
1858 Jump between original kernel and kexeced kernel and invoke
1859 code in physical address mode via KEXEC
1861 config PHYSICAL_START
1862 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1865 This gives the physical address where the kernel is loaded.
1867 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1868 bzImage will decompress itself to above physical address and
1869 run from there. Otherwise, bzImage will run from the address where
1870 it has been loaded by the boot loader and will ignore above physical
1873 In normal kdump cases one does not have to set/change this option
1874 as now bzImage can be compiled as a completely relocatable image
1875 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1876 address. This option is mainly useful for the folks who don't want
1877 to use a bzImage for capturing the crash dump and want to use a
1878 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1879 to be specifically compiled to run from a specific memory area
1880 (normally a reserved region) and this option comes handy.
1882 So if you are using bzImage for capturing the crash dump,
1883 leave the value here unchanged to 0x1000000 and set
1884 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1885 for capturing the crash dump change this value to start of
1886 the reserved region. In other words, it can be set based on
1887 the "X" value as specified in the "crashkernel=YM@XM"
1888 command line boot parameter passed to the panic-ed
1889 kernel. Please take a look at Documentation/kdump/kdump.txt
1890 for more details about crash dumps.
1892 Usage of bzImage for capturing the crash dump is recommended as
1893 one does not have to build two kernels. Same kernel can be used
1894 as production kernel and capture kernel. Above option should have
1895 gone away after relocatable bzImage support is introduced. But it
1896 is present because there are users out there who continue to use
1897 vmlinux for dump capture. This option should go away down the
1900 Don't change this unless you know what you are doing.
1903 bool "Build a relocatable kernel"
1906 This builds a kernel image that retains relocation information
1907 so it can be loaded someplace besides the default 1MB.
1908 The relocations tend to make the kernel binary about 10% larger,
1909 but are discarded at runtime.
1911 One use is for the kexec on panic case where the recovery kernel
1912 must live at a different physical address than the primary
1915 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1916 it has been loaded at and the compile time physical address
1917 (CONFIG_PHYSICAL_START) is used as the minimum location.
1919 config RANDOMIZE_BASE
1920 bool "Randomize the address of the kernel image"
1921 depends on RELOCATABLE
1924 Randomizes the physical and virtual address at which the
1925 kernel image is decompressed, as a security feature that
1926 deters exploit attempts relying on knowledge of the location
1927 of kernel internals.
1929 Entropy is generated using the RDRAND instruction if it is
1930 supported. If RDTSC is supported, it is used as well. If
1931 neither RDRAND nor RDTSC are supported, then randomness is
1932 read from the i8254 timer.
1934 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1935 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1936 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1937 minimum of 2MiB, only 10 bits of entropy is theoretically
1938 possible. At best, due to page table layouts, 64-bit can use
1939 9 bits of entropy and 32-bit uses 8 bits.
1943 config RANDOMIZE_BASE_MAX_OFFSET
1944 hex "Maximum kASLR offset allowed" if EXPERT
1945 depends on RANDOMIZE_BASE
1946 range 0x0 0x20000000 if X86_32
1947 default "0x20000000" if X86_32
1948 range 0x0 0x40000000 if X86_64
1949 default "0x40000000" if X86_64
1951 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1952 memory is used to determine the maximal offset in bytes that will
1953 be applied to the kernel when kernel Address Space Layout
1954 Randomization (kASLR) is active. This must be a multiple of
1957 On 32-bit this is limited to 512MiB by page table layouts. The
1960 On 64-bit this is limited by how the kernel fixmap page table is
1961 positioned, so this cannot be larger than 1GiB currently. Without
1962 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1963 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1964 modules area will shrink to compensate, up to the current maximum
1965 1GiB to 1GiB split. The default is 1GiB.
1967 If unsure, leave at the default value.
1969 # Relocation on x86 needs some additional build support
1970 config X86_NEED_RELOCS
1972 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1974 config PHYSICAL_ALIGN
1975 hex "Alignment value to which kernel should be aligned"
1977 range 0x2000 0x1000000 if X86_32
1978 range 0x200000 0x1000000 if X86_64
1980 This value puts the alignment restrictions on physical address
1981 where kernel is loaded and run from. Kernel is compiled for an
1982 address which meets above alignment restriction.
1984 If bootloader loads the kernel at a non-aligned address and
1985 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1986 address aligned to above value and run from there.
1988 If bootloader loads the kernel at a non-aligned address and
1989 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1990 load address and decompress itself to the address it has been
1991 compiled for and run from there. The address for which kernel is
1992 compiled already meets above alignment restrictions. Hence the
1993 end result is that kernel runs from a physical address meeting
1994 above alignment restrictions.
1996 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1997 this value must be a multiple of 0x200000.
1999 Don't change this unless you know what you are doing.
2002 bool "Support for hot-pluggable CPUs"
2005 Say Y here to allow turning CPUs off and on. CPUs can be
2006 controlled through /sys/devices/system/cpu.
2007 ( Note: power management support will enable this option
2008 automatically on SMP systems. )
2009 Say N if you want to disable CPU hotplug.
2011 config BOOTPARAM_HOTPLUG_CPU0
2012 bool "Set default setting of cpu0_hotpluggable"
2014 depends on HOTPLUG_CPU
2016 Set whether default state of cpu0_hotpluggable is on or off.
2018 Say Y here to enable CPU0 hotplug by default. If this switch
2019 is turned on, there is no need to give cpu0_hotplug kernel
2020 parameter and the CPU0 hotplug feature is enabled by default.
2022 Please note: there are two known CPU0 dependencies if you want
2023 to enable the CPU0 hotplug feature either by this switch or by
2024 cpu0_hotplug kernel parameter.
2026 First, resume from hibernate or suspend always starts from CPU0.
2027 So hibernate and suspend are prevented if CPU0 is offline.
2029 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2030 offline if any interrupt can not migrate out of CPU0. There may
2031 be other CPU0 dependencies.
2033 Please make sure the dependencies are under your control before
2034 you enable this feature.
2036 Say N if you don't want to enable CPU0 hotplug feature by default.
2037 You still can enable the CPU0 hotplug feature at boot by kernel
2038 parameter cpu0_hotplug.
2040 config DEBUG_HOTPLUG_CPU0
2042 prompt "Debug CPU0 hotplug"
2043 depends on HOTPLUG_CPU
2045 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2046 soon as possible and boots up userspace with CPU0 offlined. User
2047 can online CPU0 back after boot time.
2049 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2050 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2051 compilation or giving cpu0_hotplug kernel parameter at boot.
2057 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2058 depends on X86_32 || IA32_EMULATION
2060 Certain buggy versions of glibc will crash if they are
2061 presented with a 32-bit vDSO that is not mapped at the address
2062 indicated in its segment table.
2064 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2065 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2066 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2067 the only released version with the bug, but OpenSUSE 9
2068 contains a buggy "glibc 2.3.2".
2070 The symptom of the bug is that everything crashes on startup, saying:
2071 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2073 Saying Y here changes the default value of the vdso32 boot
2074 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2075 This works around the glibc bug but hurts performance.
2077 If unsure, say N: if you are compiling your own kernel, you
2078 are unlikely to be using a buggy version of glibc.
2081 prompt "vsyscall table for legacy applications"
2083 default LEGACY_VSYSCALL_EMULATE
2085 Legacy user code that does not know how to find the vDSO expects
2086 to be able to issue three syscalls by calling fixed addresses in
2087 kernel space. Since this location is not randomized with ASLR,
2088 it can be used to assist security vulnerability exploitation.
2090 This setting can be changed at boot time via the kernel command
2091 line parameter vsyscall=[native|emulate|none].
2093 On a system with recent enough glibc (2.14 or newer) and no
2094 static binaries, you can say None without a performance penalty
2095 to improve security.
2097 If unsure, select "Emulate".
2099 config LEGACY_VSYSCALL_NATIVE
2102 Actual executable code is located in the fixed vsyscall
2103 address mapping, implementing time() efficiently. Since
2104 this makes the mapping executable, it can be used during
2105 security vulnerability exploitation (traditionally as
2106 ROP gadgets). This configuration is not recommended.
2108 config LEGACY_VSYSCALL_EMULATE
2111 The kernel traps and emulates calls into the fixed
2112 vsyscall address mapping. This makes the mapping
2113 non-executable, but it still contains known contents,
2114 which could be used in certain rare security vulnerability
2115 exploits. This configuration is recommended when userspace
2116 still uses the vsyscall area.
2118 config LEGACY_VSYSCALL_NONE
2121 There will be no vsyscall mapping at all. This will
2122 eliminate any risk of ASLR bypass due to the vsyscall
2123 fixed address mapping. Attempts to use the vsyscalls
2124 will be reported to dmesg, so that either old or
2125 malicious userspace programs can be identified.
2130 bool "Built-in kernel command line"
2132 Allow for specifying boot arguments to the kernel at
2133 build time. On some systems (e.g. embedded ones), it is
2134 necessary or convenient to provide some or all of the
2135 kernel boot arguments with the kernel itself (that is,
2136 to not rely on the boot loader to provide them.)
2138 To compile command line arguments into the kernel,
2139 set this option to 'Y', then fill in the
2140 boot arguments in CONFIG_CMDLINE.
2142 Systems with fully functional boot loaders (i.e. non-embedded)
2143 should leave this option set to 'N'.
2146 string "Built-in kernel command string"
2147 depends on CMDLINE_BOOL
2150 Enter arguments here that should be compiled into the kernel
2151 image and used at boot time. If the boot loader provides a
2152 command line at boot time, it is appended to this string to
2153 form the full kernel command line, when the system boots.
2155 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2156 change this behavior.
2158 In most cases, the command line (whether built-in or provided
2159 by the boot loader) should specify the device for the root
2162 config CMDLINE_OVERRIDE
2163 bool "Built-in command line overrides boot loader arguments"
2164 depends on CMDLINE_BOOL
2166 Set this option to 'Y' to have the kernel ignore the boot loader
2167 command line, and use ONLY the built-in command line.
2169 This is used to work around broken boot loaders. This should
2170 be set to 'N' under normal conditions.
2172 config MODIFY_LDT_SYSCALL
2173 bool "Enable the LDT (local descriptor table)" if EXPERT
2176 Linux can allow user programs to install a per-process x86
2177 Local Descriptor Table (LDT) using the modify_ldt(2) system
2178 call. This is required to run 16-bit or segmented code such as
2179 DOSEMU or some Wine programs. It is also used by some very old
2180 threading libraries.
2182 Enabling this feature adds a small amount of overhead to
2183 context switches and increases the low-level kernel attack
2184 surface. Disabling it removes the modify_ldt(2) system call.
2186 Saying 'N' here may make sense for embedded or server kernels.
2188 source "kernel/livepatch/Kconfig"
2192 config ARCH_ENABLE_MEMORY_HOTPLUG
2194 depends on X86_64 || (X86_32 && HIGHMEM)
2196 config ARCH_ENABLE_MEMORY_HOTREMOVE
2198 depends on MEMORY_HOTPLUG
2200 config USE_PERCPU_NUMA_NODE_ID
2204 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2206 depends on X86_64 || X86_PAE
2208 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2210 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2212 menu "Power management and ACPI options"
2214 config ARCH_HIBERNATION_HEADER
2216 depends on X86_64 && HIBERNATION
2218 source "kernel/power/Kconfig"
2220 source "drivers/acpi/Kconfig"
2222 source "drivers/sfi/Kconfig"
2229 tristate "APM (Advanced Power Management) BIOS support"
2230 depends on X86_32 && PM_SLEEP
2232 APM is a BIOS specification for saving power using several different
2233 techniques. This is mostly useful for battery powered laptops with
2234 APM compliant BIOSes. If you say Y here, the system time will be
2235 reset after a RESUME operation, the /proc/apm device will provide
2236 battery status information, and user-space programs will receive
2237 notification of APM "events" (e.g. battery status change).
2239 If you select "Y" here, you can disable actual use of the APM
2240 BIOS by passing the "apm=off" option to the kernel at boot time.
2242 Note that the APM support is almost completely disabled for
2243 machines with more than one CPU.
2245 In order to use APM, you will need supporting software. For location
2246 and more information, read <file:Documentation/power/apm-acpi.txt>
2247 and the Battery Powered Linux mini-HOWTO, available from
2248 <http://www.tldp.org/docs.html#howto>.
2250 This driver does not spin down disk drives (see the hdparm(8)
2251 manpage ("man 8 hdparm") for that), and it doesn't turn off
2252 VESA-compliant "green" monitors.
2254 This driver does not support the TI 4000M TravelMate and the ACER
2255 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2256 desktop machines also don't have compliant BIOSes, and this driver
2257 may cause those machines to panic during the boot phase.
2259 Generally, if you don't have a battery in your machine, there isn't
2260 much point in using this driver and you should say N. If you get
2261 random kernel OOPSes or reboots that don't seem to be related to
2262 anything, try disabling/enabling this option (or disabling/enabling
2265 Some other things you should try when experiencing seemingly random,
2268 1) make sure that you have enough swap space and that it is
2270 2) pass the "no-hlt" option to the kernel
2271 3) switch on floating point emulation in the kernel and pass
2272 the "no387" option to the kernel
2273 4) pass the "floppy=nodma" option to the kernel
2274 5) pass the "mem=4M" option to the kernel (thereby disabling
2275 all but the first 4 MB of RAM)
2276 6) make sure that the CPU is not over clocked.
2277 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2278 8) disable the cache from your BIOS settings
2279 9) install a fan for the video card or exchange video RAM
2280 10) install a better fan for the CPU
2281 11) exchange RAM chips
2282 12) exchange the motherboard.
2284 To compile this driver as a module, choose M here: the
2285 module will be called apm.
2289 config APM_IGNORE_USER_SUSPEND
2290 bool "Ignore USER SUSPEND"
2292 This option will ignore USER SUSPEND requests. On machines with a
2293 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2294 series notebooks, it is necessary to say Y because of a BIOS bug.
2296 config APM_DO_ENABLE
2297 bool "Enable PM at boot time"
2299 Enable APM features at boot time. From page 36 of the APM BIOS
2300 specification: "When disabled, the APM BIOS does not automatically
2301 power manage devices, enter the Standby State, enter the Suspend
2302 State, or take power saving steps in response to CPU Idle calls."
2303 This driver will make CPU Idle calls when Linux is idle (unless this
2304 feature is turned off -- see "Do CPU IDLE calls", below). This
2305 should always save battery power, but more complicated APM features
2306 will be dependent on your BIOS implementation. You may need to turn
2307 this option off if your computer hangs at boot time when using APM
2308 support, or if it beeps continuously instead of suspending. Turn
2309 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2310 T400CDT. This is off by default since most machines do fine without
2315 bool "Make CPU Idle calls when idle"
2317 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2318 On some machines, this can activate improved power savings, such as
2319 a slowed CPU clock rate, when the machine is idle. These idle calls
2320 are made after the idle loop has run for some length of time (e.g.,
2321 333 mS). On some machines, this will cause a hang at boot time or
2322 whenever the CPU becomes idle. (On machines with more than one CPU,
2323 this option does nothing.)
2325 config APM_DISPLAY_BLANK
2326 bool "Enable console blanking using APM"
2328 Enable console blanking using the APM. Some laptops can use this to
2329 turn off the LCD backlight when the screen blanker of the Linux
2330 virtual console blanks the screen. Note that this is only used by
2331 the virtual console screen blanker, and won't turn off the backlight
2332 when using the X Window system. This also doesn't have anything to
2333 do with your VESA-compliant power-saving monitor. Further, this
2334 option doesn't work for all laptops -- it might not turn off your
2335 backlight at all, or it might print a lot of errors to the console,
2336 especially if you are using gpm.
2338 config APM_ALLOW_INTS
2339 bool "Allow interrupts during APM BIOS calls"
2341 Normally we disable external interrupts while we are making calls to
2342 the APM BIOS as a measure to lessen the effects of a badly behaving
2343 BIOS implementation. The BIOS should reenable interrupts if it
2344 needs to. Unfortunately, some BIOSes do not -- especially those in
2345 many of the newer IBM Thinkpads. If you experience hangs when you
2346 suspend, try setting this to Y. Otherwise, say N.
2350 source "drivers/cpufreq/Kconfig"
2352 source "drivers/cpuidle/Kconfig"
2354 source "drivers/idle/Kconfig"
2359 menu "Bus options (PCI etc.)"
2365 Find out whether you have a PCI motherboard. PCI is the name of a
2366 bus system, i.e. the way the CPU talks to the other stuff inside
2367 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2368 VESA. If you have PCI, say Y, otherwise N.
2371 prompt "PCI access mode"
2372 depends on X86_32 && PCI
2375 On PCI systems, the BIOS can be used to detect the PCI devices and
2376 determine their configuration. However, some old PCI motherboards
2377 have BIOS bugs and may crash if this is done. Also, some embedded
2378 PCI-based systems don't have any BIOS at all. Linux can also try to
2379 detect the PCI hardware directly without using the BIOS.
2381 With this option, you can specify how Linux should detect the
2382 PCI devices. If you choose "BIOS", the BIOS will be used,
2383 if you choose "Direct", the BIOS won't be used, and if you
2384 choose "MMConfig", then PCI Express MMCONFIG will be used.
2385 If you choose "Any", the kernel will try MMCONFIG, then the
2386 direct access method and falls back to the BIOS if that doesn't
2387 work. If unsure, go with the default, which is "Any".
2392 config PCI_GOMMCONFIG
2409 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2411 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2414 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2418 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2422 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2426 depends on PCI && XEN
2434 bool "Support mmconfig PCI config space access"
2435 depends on X86_64 && PCI && ACPI
2437 config PCI_CNB20LE_QUIRK
2438 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2441 Read the PCI windows out of the CNB20LE host bridge. This allows
2442 PCI hotplug to work on systems with the CNB20LE chipset which do
2445 There's no public spec for this chipset, and this functionality
2446 is known to be incomplete.
2448 You should say N unless you know you need this.
2450 source "drivers/pci/pcie/Kconfig"
2452 source "drivers/pci/Kconfig"
2454 # x86_64 have no ISA slots, but can have ISA-style DMA.
2456 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2459 Enables ISA-style DMA support for devices requiring such controllers.
2467 Find out whether you have ISA slots on your motherboard. ISA is the
2468 name of a bus system, i.e. the way the CPU talks to the other stuff
2469 inside your box. Other bus systems are PCI, EISA, MicroChannel
2470 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2471 newer boards don't support it. If you have ISA, say Y, otherwise N.
2477 The Extended Industry Standard Architecture (EISA) bus was
2478 developed as an open alternative to the IBM MicroChannel bus.
2480 The EISA bus provided some of the features of the IBM MicroChannel
2481 bus while maintaining backward compatibility with cards made for
2482 the older ISA bus. The EISA bus saw limited use between 1988 and
2483 1995 when it was made obsolete by the PCI bus.
2485 Say Y here if you are building a kernel for an EISA-based machine.
2489 source "drivers/eisa/Kconfig"
2492 tristate "NatSemi SCx200 support"
2494 This provides basic support for National Semiconductor's
2495 (now AMD's) Geode processors. The driver probes for the
2496 PCI-IDs of several on-chip devices, so its a good dependency
2497 for other scx200_* drivers.
2499 If compiled as a module, the driver is named scx200.
2501 config SCx200HR_TIMER
2502 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2506 This driver provides a clocksource built upon the on-chip
2507 27MHz high-resolution timer. Its also a workaround for
2508 NSC Geode SC-1100's buggy TSC, which loses time when the
2509 processor goes idle (as is done by the scheduler). The
2510 other workaround is idle=poll boot option.
2513 bool "One Laptop Per Child support"
2520 Add support for detecting the unique features of the OLPC
2524 bool "OLPC XO-1 Power Management"
2525 depends on OLPC && MFD_CS5535 && PM_SLEEP
2528 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2531 bool "OLPC XO-1 Real Time Clock"
2532 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2534 Add support for the XO-1 real time clock, which can be used as a
2535 programmable wakeup source.
2538 bool "OLPC XO-1 SCI extras"
2539 depends on OLPC && OLPC_XO1_PM
2545 Add support for SCI-based features of the OLPC XO-1 laptop:
2546 - EC-driven system wakeups
2550 - AC adapter status updates
2551 - Battery status updates
2553 config OLPC_XO15_SCI
2554 bool "OLPC XO-1.5 SCI extras"
2555 depends on OLPC && ACPI
2558 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2559 - EC-driven system wakeups
2560 - AC adapter status updates
2561 - Battery status updates
2564 bool "PCEngines ALIX System Support (LED setup)"
2567 This option enables system support for the PCEngines ALIX.
2568 At present this just sets up LEDs for GPIO control on
2569 ALIX2/3/6 boards. However, other system specific setup should
2572 Note: You must still enable the drivers for GPIO and LED support
2573 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2575 Note: You have to set alix.force=1 for boards with Award BIOS.
2578 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2581 This option enables system support for the Soekris Engineering net5501.
2584 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2588 This option enables system support for the Traverse Technologies GEOS.
2591 bool "Technologic Systems TS-5500 platform support"
2593 select CHECK_SIGNATURE
2597 This option enables system support for the Technologic Systems TS-5500.
2603 depends on CPU_SUP_AMD && PCI
2605 source "drivers/pcmcia/Kconfig"
2607 source "drivers/pci/hotplug/Kconfig"
2610 tristate "RapidIO support"
2614 If enabled this option will include drivers and the core
2615 infrastructure code to support RapidIO interconnect devices.
2617 source "drivers/rapidio/Kconfig"
2620 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2622 Firmwares often provide initial graphics framebuffers so the BIOS,
2623 bootloader or kernel can show basic video-output during boot for
2624 user-guidance and debugging. Historically, x86 used the VESA BIOS
2625 Extensions and EFI-framebuffers for this, which are mostly limited
2627 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2628 framebuffers so the new generic system-framebuffer drivers can be
2629 used on x86. If the framebuffer is not compatible with the generic
2630 modes, it is adverticed as fallback platform framebuffer so legacy
2631 drivers like efifb, vesafb and uvesafb can pick it up.
2632 If this option is not selected, all system framebuffers are always
2633 marked as fallback platform framebuffers as usual.
2635 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2636 not be able to pick up generic system framebuffers if this option
2637 is selected. You are highly encouraged to enable simplefb as
2638 replacement if you select this option. simplefb can correctly deal
2639 with generic system framebuffers. But you should still keep vesafb
2640 and others enabled as fallback if a system framebuffer is
2641 incompatible with simplefb.
2648 menu "Executable file formats / Emulations"
2650 source "fs/Kconfig.binfmt"
2652 config IA32_EMULATION
2653 bool "IA32 Emulation"
2656 select COMPAT_BINFMT_ELF
2657 select ARCH_WANT_OLD_COMPAT_IPC
2659 Include code to run legacy 32-bit programs under a
2660 64-bit kernel. You should likely turn this on, unless you're
2661 100% sure that you don't have any 32-bit programs left.
2664 tristate "IA32 a.out support"
2665 depends on IA32_EMULATION
2667 Support old a.out binaries in the 32bit emulation.
2670 bool "x32 ABI for 64-bit mode"
2673 Include code to run binaries for the x32 native 32-bit ABI
2674 for 64-bit processors. An x32 process gets access to the
2675 full 64-bit register file and wide data path while leaving
2676 pointers at 32 bits for smaller memory footprint.
2678 You will need a recent binutils (2.22 or later) with
2679 elf32_x86_64 support enabled to compile a kernel with this
2684 depends on IA32_EMULATION || X86_X32
2687 config COMPAT_FOR_U64_ALIGNMENT
2690 config SYSVIPC_COMPAT
2702 config HAVE_ATOMIC_IOMAP
2706 config X86_DEV_DMA_OPS
2708 depends on X86_64 || STA2X11
2710 config X86_DMA_REMAP
2720 tristate "Volume Management Device Driver"
2723 Adds support for the Intel Volume Management Device (VMD). VMD is a
2724 secondary PCI host bridge that allows PCI Express root ports,
2725 and devices attached to them, to be removed from the default
2726 PCI domain and placed within the VMD domain. This provides
2727 more bus resources than are otherwise possible with a
2728 single domain. If you know your system provides one of these and
2729 has devices attached to it, say Y; if you are not sure, say N.
2731 source "net/Kconfig"
2733 source "drivers/Kconfig"
2735 source "drivers/firmware/Kconfig"
2739 source "arch/x86/Kconfig.debug"
2741 source "security/Kconfig"
2743 source "crypto/Kconfig"
2745 source "arch/x86/kvm/Kconfig"
2747 source "lib/Kconfig"
projects / cascardo / linux.git / blob