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
18 select X86_DEV_DMA_OPS
23 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
24 select HAVE_AOUT if X86_32
25 select HAVE_UNSTABLE_SCHED_CLOCK
26 select ARCH_SUPPORTS_NUMA_BALANCING
27 select ARCH_WANTS_PROT_NUMA_PROT_NONE
30 select HAVE_PCSPKR_PLATFORM
31 select HAVE_PERF_EVENTS
32 select HAVE_IOREMAP_PROT
35 select HAVE_MEMBLOCK_NODE_MAP
36 select ARCH_DISCARD_MEMBLOCK
37 select ARCH_WANT_OPTIONAL_GPIOLIB
38 select ARCH_WANT_FRAME_POINTERS
40 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
41 select HAVE_KRETPROBES
43 select HAVE_KPROBES_ON_FTRACE
44 select HAVE_FTRACE_MCOUNT_RECORD
45 select HAVE_FENTRY if X86_64
46 select HAVE_C_RECORDMCOUNT
47 select HAVE_DYNAMIC_FTRACE
48 select HAVE_DYNAMIC_FTRACE_WITH_REGS
49 select HAVE_FUNCTION_TRACER
50 select HAVE_FUNCTION_GRAPH_TRACER
51 select HAVE_FUNCTION_GRAPH_FP_TEST
52 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
53 select HAVE_SYSCALL_TRACEPOINTS
54 select SYSCTL_EXCEPTION_TRACE
57 select HAVE_ARCH_TRACEHOOK
58 select HAVE_GENERIC_DMA_COHERENT if X86_32
59 select HAVE_EFFICIENT_UNALIGNED_ACCESS
60 select USER_STACKTRACE_SUPPORT
61 select HAVE_REGS_AND_STACK_ACCESS_API
62 select HAVE_DMA_API_DEBUG
63 select HAVE_KERNEL_GZIP
64 select HAVE_KERNEL_BZIP2
65 select HAVE_KERNEL_LZMA
67 select HAVE_KERNEL_LZO
68 select HAVE_HW_BREAKPOINT
69 select HAVE_MIXED_BREAKPOINTS_REGS
71 select HAVE_PERF_EVENTS_NMI
73 select HAVE_PERF_USER_STACK_DUMP
74 select HAVE_DEBUG_KMEMLEAK
76 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
77 select HAVE_CMPXCHG_LOCAL
78 select HAVE_CMPXCHG_DOUBLE
79 select HAVE_ARCH_KMEMCHECK
80 select HAVE_USER_RETURN_NOTIFIER
81 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
82 select HAVE_ARCH_JUMP_LABEL
83 select HAVE_TEXT_POKE_SMP
84 select HAVE_GENERIC_HARDIRQS
85 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
87 select GENERIC_FIND_FIRST_BIT
88 select GENERIC_IRQ_PROBE
89 select GENERIC_PENDING_IRQ if SMP
90 select GENERIC_IRQ_SHOW
91 select GENERIC_CLOCKEVENTS_MIN_ADJUST
92 select IRQ_FORCED_THREADING
93 select USE_GENERIC_SMP_HELPERS if SMP
94 select HAVE_BPF_JIT if X86_64
95 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
97 select ARCH_HAVE_NMI_SAFE_CMPXCHG
99 select DCACHE_WORD_ACCESS
100 select GENERIC_SMP_IDLE_THREAD
101 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
102 select HAVE_ARCH_SECCOMP_FILTER
103 select BUILDTIME_EXTABLE_SORT
104 select GENERIC_CMOS_UPDATE
105 select CLOCKSOURCE_WATCHDOG
106 select GENERIC_CLOCKEVENTS
107 select ARCH_CLOCKSOURCE_DATA if X86_64
108 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
109 select GENERIC_TIME_VSYSCALL if X86_64
110 select KTIME_SCALAR if X86_32
111 select ALWAYS_USE_PERSISTENT_CLOCK
112 select GENERIC_STRNCPY_FROM_USER
113 select GENERIC_STRNLEN_USER
114 select HAVE_CONTEXT_TRACKING if X86_64
115 select HAVE_IRQ_TIME_ACCOUNTING
117 select MODULES_USE_ELF_REL if X86_32
118 select MODULES_USE_ELF_RELA if X86_64
119 select CLONE_BACKWARDS if X86_32
120 select ARCH_USE_BUILTIN_BSWAP
121 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
122 select OLD_SIGACTION if X86_32
123 select COMPAT_OLD_SIGACTION if IA32_EMULATION
126 config INSTRUCTION_DECODER
128 depends on KPROBES || PERF_EVENTS || UPROBES
132 default "elf32-i386" if X86_32
133 default "elf64-x86-64" if X86_64
135 config ARCH_DEFCONFIG
137 default "arch/x86/configs/i386_defconfig" if X86_32
138 default "arch/x86/configs/x86_64_defconfig" if X86_64
140 config LOCKDEP_SUPPORT
143 config STACKTRACE_SUPPORT
146 config HAVE_LATENCYTOP_SUPPORT
155 config NEED_DMA_MAP_STATE
157 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
159 config NEED_SG_DMA_LENGTH
162 config GENERIC_ISA_DMA
164 depends on ISA_DMA_API
169 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
171 config GENERIC_BUG_RELATIVE_POINTERS
174 config GENERIC_HWEIGHT
177 config ARCH_MAY_HAVE_PC_FDC
179 depends on ISA_DMA_API
181 config RWSEM_XCHGADD_ALGORITHM
184 config GENERIC_CALIBRATE_DELAY
187 config ARCH_HAS_CPU_RELAX
190 config ARCH_HAS_CACHE_LINE_SIZE
193 config ARCH_HAS_CPU_AUTOPROBE
196 config HAVE_SETUP_PER_CPU_AREA
199 config NEED_PER_CPU_EMBED_FIRST_CHUNK
202 config NEED_PER_CPU_PAGE_FIRST_CHUNK
205 config ARCH_HIBERNATION_POSSIBLE
208 config ARCH_SUSPEND_POSSIBLE
219 config ARCH_SUPPORTS_OPTIMIZED_INLINING
222 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
225 config HAVE_INTEL_TXT
227 depends on INTEL_IOMMU && ACPI
231 depends on X86_32 && SMP
235 depends on X86_64 && SMP
241 config X86_32_LAZY_GS
243 depends on X86_32 && !CC_STACKPROTECTOR
245 config ARCH_HWEIGHT_CFLAGS
247 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
248 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
250 config ARCH_CPU_PROBE_RELEASE
252 depends on HOTPLUG_CPU
254 config ARCH_SUPPORTS_UPROBES
257 source "init/Kconfig"
258 source "kernel/Kconfig.freezer"
260 menu "Processor type and features"
263 bool "DMA memory allocation support" if EXPERT
266 DMA memory allocation support allows devices with less than 32-bit
267 addressing to allocate within the first 16MB of address space.
268 Disable if no such devices will be used.
273 bool "Symmetric multi-processing support"
275 This enables support for systems with more than one CPU. If you have
276 a system with only one CPU, like most personal computers, say N. If
277 you have a system with more than one CPU, say Y.
279 If you say N here, the kernel will run on single and multiprocessor
280 machines, but will use only one CPU of a multiprocessor machine. If
281 you say Y here, the kernel will run on many, but not all,
282 singleprocessor machines. On a singleprocessor machine, the kernel
283 will run faster if you say N here.
285 Note that if you say Y here and choose architecture "586" or
286 "Pentium" under "Processor family", the kernel will not work on 486
287 architectures. Similarly, multiprocessor kernels for the "PPro"
288 architecture may not work on all Pentium based boards.
290 People using multiprocessor machines who say Y here should also say
291 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
292 Management" code will be disabled if you say Y here.
294 See also <file:Documentation/x86/i386/IO-APIC.txt>,
295 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
296 <http://www.tldp.org/docs.html#howto>.
298 If you don't know what to do here, say N.
301 bool "Support x2apic"
302 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
304 This enables x2apic support on CPUs that have this feature.
306 This allows 32-bit apic IDs (so it can support very large systems),
307 and accesses the local apic via MSRs not via mmio.
309 If you don't know what to do here, say N.
312 bool "Enable MPS table" if ACPI || SFI
314 depends on X86_LOCAL_APIC
316 For old smp systems that do not have proper acpi support. Newer systems
317 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
320 bool "Support for big SMP systems with more than 8 CPUs"
321 depends on X86_32 && SMP
323 This option is needed for the systems that have more than 8 CPUs
327 depends on X86_GOLDFISH
330 config X86_EXTENDED_PLATFORM
331 bool "Support for extended (non-PC) x86 platforms"
334 If you disable this option then the kernel will only support
335 standard PC platforms. (which covers the vast majority of
338 If you enable this option then you'll be able to select support
339 for the following (non-PC) 32 bit x86 platforms:
343 SGI 320/540 (Visual Workstation)
344 STA2X11-based (e.g. Northville)
345 Summit/EXA (IBM x440)
346 Unisys ES7000 IA32 series
347 Moorestown MID devices
349 If you have one of these systems, or if you want to build a
350 generic distribution kernel, say Y here - otherwise say N.
354 config X86_EXTENDED_PLATFORM
355 bool "Support for extended (non-PC) x86 platforms"
358 If you disable this option then the kernel will only support
359 standard PC platforms. (which covers the vast majority of
362 If you enable this option then you'll be able to select support
363 for the following (non-PC) 64 bit x86 platforms:
368 If you have one of these systems, or if you want to build a
369 generic distribution kernel, say Y here - otherwise say N.
371 # This is an alphabetically sorted list of 64 bit extended platforms
372 # Please maintain the alphabetic order if and when there are additions
374 bool "Numascale NumaChip"
376 depends on X86_EXTENDED_PLATFORM
379 depends on X86_X2APIC
380 depends on PCI_MMCONFIG
382 Adds support for Numascale NumaChip large-SMP systems. Needed to
383 enable more than ~168 cores.
384 If you don't have one of these, you should say N here.
388 select HYPERVISOR_GUEST
390 depends on X86_64 && PCI
391 depends on X86_EXTENDED_PLATFORM
394 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
395 supposed to run on these EM64T-based machines. Only choose this option
396 if you have one of these machines.
399 bool "SGI Ultraviolet"
401 depends on X86_EXTENDED_PLATFORM
403 depends on X86_X2APIC
405 This option is needed in order to support SGI Ultraviolet systems.
406 If you don't have one of these, you should say N here.
408 # Following is an alphabetically sorted list of 32 bit extended platforms
409 # Please maintain the alphabetic order if and when there are additions
412 bool "Goldfish (Virtual Platform)"
415 Enable support for the Goldfish virtual platform used primarily
416 for Android development. Unless you are building for the Android
417 Goldfish emulator say N here.
420 bool "CE4100 TV platform"
422 depends on PCI_GODIRECT
424 depends on X86_EXTENDED_PLATFORM
425 select X86_REBOOTFIXUPS
427 select OF_EARLY_FLATTREE
430 Select for the Intel CE media processor (CE4100) SOC.
431 This option compiles in support for the CE4100 SOC for settop
432 boxes and media devices.
434 config X86_WANT_INTEL_MID
435 bool "Intel MID platform support"
437 depends on X86_EXTENDED_PLATFORM
439 Select to build a kernel capable of supporting Intel MID platform
440 systems which do not have the PCI legacy interfaces (Moorestown,
441 Medfield). If you are building for a PC class system say N here.
443 if X86_WANT_INTEL_MID
449 bool "Medfield MID platform"
452 depends on X86_IO_APIC
460 select X86_PLATFORM_DEVICES
461 select MFD_INTEL_MSIC
463 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
464 Internet Device(MID) platform.
465 Unlike standard x86 PCs, Medfield does not have many legacy devices
466 nor standard legacy replacement devices/features. e.g. Medfield does
467 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
471 config X86_INTEL_LPSS
472 bool "Intel Low Power Subsystem Support"
476 Select to build support for Intel Low Power Subsystem such as
477 found on Intel Lynxpoint PCH. Selecting this option enables
478 things like clock tree (common clock framework) which are needed
479 by the LPSS peripheral drivers.
482 bool "RDC R-321x SoC"
484 depends on X86_EXTENDED_PLATFORM
486 select X86_REBOOTFIXUPS
488 This option is needed for RDC R-321x system-on-chip, also known
490 If you don't have one of these chips, you should say N here.
492 config X86_32_NON_STANDARD
493 bool "Support non-standard 32-bit SMP architectures"
494 depends on X86_32 && SMP
495 depends on X86_EXTENDED_PLATFORM
497 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
498 STA2X11, default subarchitectures. It is intended for a generic
499 binary kernel. If you select them all, kernel will probe it
500 one by one and will fallback to default.
502 # Alphabetically sorted list of Non standard 32 bit platforms
505 bool "NUMAQ (IBM/Sequent)"
506 depends on X86_32_NON_STANDARD
511 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
512 NUMA multiquad box. This changes the way that processors are
513 bootstrapped, and uses Clustered Logical APIC addressing mode instead
514 of Flat Logical. You will need a new lynxer.elf file to flash your
515 firmware with - send email to <Martin.Bligh@us.ibm.com>.
517 config X86_SUPPORTS_MEMORY_FAILURE
519 # MCE code calls memory_failure():
521 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
522 depends on !X86_NUMAQ
523 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
524 depends on X86_64 || !SPARSEMEM
525 select ARCH_SUPPORTS_MEMORY_FAILURE
528 bool "SGI 320/540 (Visual Workstation)"
529 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
530 depends on X86_32_NON_STANDARD
532 The SGI Visual Workstation series is an IA32-based workstation
533 based on SGI systems chips with some legacy PC hardware attached.
535 Say Y here to create a kernel to run on the SGI 320 or 540.
537 A kernel compiled for the Visual Workstation will run on general
538 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
541 bool "STA2X11 Companion Chip Support"
542 depends on X86_32_NON_STANDARD && PCI
543 select X86_DEV_DMA_OPS
547 select ARCH_REQUIRE_GPIOLIB
550 This adds support for boards based on the STA2X11 IO-Hub,
551 a.k.a. "ConneXt". The chip is used in place of the standard
552 PC chipset, so all "standard" peripherals are missing. If this
553 option is selected the kernel will still be able to boot on
554 standard PC machines.
557 bool "Summit/EXA (IBM x440)"
558 depends on X86_32_NON_STANDARD
560 This option is needed for IBM systems that use the Summit/EXA chipset.
561 In particular, it is needed for the x440.
564 bool "Unisys ES7000 IA32 series"
565 depends on X86_32_NON_STANDARD && X86_BIGSMP
567 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
568 supposed to run on an IA32-based Unisys ES7000 system.
571 tristate "Eurobraille/Iris poweroff module"
574 The Iris machines from EuroBraille do not have APM or ACPI support
575 to shut themselves down properly. A special I/O sequence is
576 needed to do so, which is what this module does at
579 This is only for Iris machines from EuroBraille.
583 config SCHED_OMIT_FRAME_POINTER
585 prompt "Single-depth WCHAN output"
588 Calculate simpler /proc/<PID>/wchan values. If this option
589 is disabled then wchan values will recurse back to the
590 caller function. This provides more accurate wchan values,
591 at the expense of slightly more scheduling overhead.
593 If in doubt, say "Y".
595 menuconfig HYPERVISOR_GUEST
596 bool "Linux guest support"
598 Say Y here to enable options for running Linux under various hyper-
599 visors. This option enables basic hypervisor detection and platform
602 If you say N, all options in this submenu will be skipped and
603 disabled, and Linux guest support won't be built in.
608 bool "Enable paravirtualization code"
610 This changes the kernel so it can modify itself when it is run
611 under a hypervisor, potentially improving performance significantly
612 over full virtualization. However, when run without a hypervisor
613 the kernel is theoretically slower and slightly larger.
615 config PARAVIRT_DEBUG
616 bool "paravirt-ops debugging"
617 depends on PARAVIRT && DEBUG_KERNEL
619 Enable to debug paravirt_ops internals. Specifically, BUG if
620 a paravirt_op is missing when it is called.
622 config PARAVIRT_SPINLOCKS
623 bool "Paravirtualization layer for spinlocks"
624 depends on PARAVIRT && SMP
626 Paravirtualized spinlocks allow a pvops backend to replace the
627 spinlock implementation with something virtualization-friendly
628 (for example, block the virtual CPU rather than spinning).
630 Unfortunately the downside is an up to 5% performance hit on
631 native kernels, with various workloads.
633 If you are unsure how to answer this question, answer N.
635 source "arch/x86/xen/Kconfig"
638 bool "KVM Guest support (including kvmclock)"
640 select PARAVIRT_CLOCK
643 This option enables various optimizations for running under the KVM
644 hypervisor. It includes a paravirtualized clock, so that instead
645 of relying on a PIT (or probably other) emulation by the
646 underlying device model, the host provides the guest with
647 timing infrastructure such as time of day, and system time
649 source "arch/x86/lguest/Kconfig"
651 config PARAVIRT_TIME_ACCOUNTING
652 bool "Paravirtual steal time accounting"
656 Select this option to enable fine granularity task steal time
657 accounting. Time spent executing other tasks in parallel with
658 the current vCPU is discounted from the vCPU power. To account for
659 that, there can be a small performance impact.
661 If in doubt, say N here.
663 config PARAVIRT_CLOCK
666 endif #HYPERVISOR_GUEST
674 This option adds a kernel parameter 'memtest', which allows memtest
676 memtest=0, mean disabled; -- default
677 memtest=1, mean do 1 test pattern;
679 memtest=4, mean do 4 test patterns.
680 If you are unsure how to answer this question, answer N.
682 config X86_SUMMIT_NUMA
684 depends on X86_32 && NUMA && X86_32_NON_STANDARD
686 config X86_CYCLONE_TIMER
688 depends on X86_SUMMIT
690 source "arch/x86/Kconfig.cpu"
694 prompt "HPET Timer Support" if X86_32
696 Use the IA-PC HPET (High Precision Event Timer) to manage
697 time in preference to the PIT and RTC, if a HPET is
699 HPET is the next generation timer replacing legacy 8254s.
700 The HPET provides a stable time base on SMP
701 systems, unlike the TSC, but it is more expensive to access,
702 as it is off-chip. You can find the HPET spec at
703 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
705 You can safely choose Y here. However, HPET will only be
706 activated if the platform and the BIOS support this feature.
707 Otherwise the 8254 will be used for timing services.
709 Choose N to continue using the legacy 8254 timer.
711 config HPET_EMULATE_RTC
713 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
716 def_bool y if X86_INTEL_MID
717 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
719 depends on X86_INTEL_MID && SFI
721 APB timer is the replacement for 8254, HPET on X86 MID platforms.
722 The APBT provides a stable time base on SMP
723 systems, unlike the TSC, but it is more expensive to access,
724 as it is off-chip. APB timers are always running regardless of CPU
725 C states, they are used as per CPU clockevent device when possible.
727 # Mark as expert because too many people got it wrong.
728 # The code disables itself when not needed.
731 bool "Enable DMI scanning" if EXPERT
733 Enabled scanning of DMI to identify machine quirks. Say Y
734 here unless you have verified that your setup is not
735 affected by entries in the DMI blacklist. Required by PNP
739 bool "GART IOMMU support" if EXPERT
742 depends on X86_64 && PCI && AMD_NB
744 Support for full DMA access of devices with 32bit memory access only
745 on systems with more than 3GB. This is usually needed for USB,
746 sound, many IDE/SATA chipsets and some other devices.
747 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
748 based hardware IOMMU and a software bounce buffer based IOMMU used
749 on Intel systems and as fallback.
750 The code is only active when needed (enough memory and limited
751 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
755 bool "IBM Calgary IOMMU support"
757 depends on X86_64 && PCI
759 Support for hardware IOMMUs in IBM's xSeries x366 and x460
760 systems. Needed to run systems with more than 3GB of memory
761 properly with 32-bit PCI devices that do not support DAC
762 (Double Address Cycle). Calgary also supports bus level
763 isolation, where all DMAs pass through the IOMMU. This
764 prevents them from going anywhere except their intended
765 destination. This catches hard-to-find kernel bugs and
766 mis-behaving drivers and devices that do not use the DMA-API
767 properly to set up their DMA buffers. The IOMMU can be
768 turned off at boot time with the iommu=off parameter.
769 Normally the kernel will make the right choice by itself.
772 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
774 prompt "Should Calgary be enabled by default?"
775 depends on CALGARY_IOMMU
777 Should Calgary be enabled by default? if you choose 'y', Calgary
778 will be used (if it exists). If you choose 'n', Calgary will not be
779 used even if it exists. If you choose 'n' and would like to use
780 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
783 # need this always selected by IOMMU for the VIA workaround
787 Support for software bounce buffers used on x86-64 systems
788 which don't have a hardware IOMMU. Using this PCI devices
789 which can only access 32-bits of memory can be used on systems
790 with more than 3 GB of memory.
795 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
798 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
799 depends on X86_64 && SMP && DEBUG_KERNEL
800 select CPUMASK_OFFSTACK
802 Enable maximum number of CPUS and NUMA Nodes for this architecture.
806 int "Maximum number of CPUs" if SMP && !MAXSMP
807 range 2 8 if SMP && X86_32 && !X86_BIGSMP
808 range 2 512 if SMP && !MAXSMP
810 default "4096" if MAXSMP
811 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
814 This allows you to specify the maximum number of CPUs which this
815 kernel will support. The maximum supported value is 512 and the
816 minimum value which makes sense is 2.
818 This is purely to save memory - each supported CPU adds
819 approximately eight kilobytes to the kernel image.
822 bool "SMT (Hyperthreading) scheduler support"
825 SMT scheduler support improves the CPU scheduler's decision making
826 when dealing with Intel Pentium 4 chips with HyperThreading at a
827 cost of slightly increased overhead in some places. If unsure say
832 prompt "Multi-core scheduler support"
835 Multi-core scheduler support improves the CPU scheduler's decision
836 making when dealing with multi-core CPU chips at a cost of slightly
837 increased overhead in some places. If unsure say N here.
839 source "kernel/Kconfig.preempt"
842 bool "Local APIC support on uniprocessors"
843 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
845 A local APIC (Advanced Programmable Interrupt Controller) is an
846 integrated interrupt controller in the CPU. If you have a single-CPU
847 system which has a processor with a local APIC, you can say Y here to
848 enable and use it. If you say Y here even though your machine doesn't
849 have a local APIC, then the kernel will still run with no slowdown at
850 all. The local APIC supports CPU-generated self-interrupts (timer,
851 performance counters), and the NMI watchdog which detects hard
855 bool "IO-APIC support on uniprocessors"
856 depends on X86_UP_APIC
858 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
859 SMP-capable replacement for PC-style interrupt controllers. Most
860 SMP systems and many recent uniprocessor systems have one.
862 If you have a single-CPU system with an IO-APIC, you can say Y here
863 to use it. If you say Y here even though your machine doesn't have
864 an IO-APIC, then the kernel will still run with no slowdown at all.
866 config X86_LOCAL_APIC
868 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
872 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
874 config X86_VISWS_APIC
876 depends on X86_32 && X86_VISWS
878 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
879 bool "Reroute for broken boot IRQs"
880 depends on X86_IO_APIC
882 This option enables a workaround that fixes a source of
883 spurious interrupts. This is recommended when threaded
884 interrupt handling is used on systems where the generation of
885 superfluous "boot interrupts" cannot be disabled.
887 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
888 entry in the chipset's IO-APIC is masked (as, e.g. the RT
889 kernel does during interrupt handling). On chipsets where this
890 boot IRQ generation cannot be disabled, this workaround keeps
891 the original IRQ line masked so that only the equivalent "boot
892 IRQ" is delivered to the CPUs. The workaround also tells the
893 kernel to set up the IRQ handler on the boot IRQ line. In this
894 way only one interrupt is delivered to the kernel. Otherwise
895 the spurious second interrupt may cause the kernel to bring
896 down (vital) interrupt lines.
898 Only affects "broken" chipsets. Interrupt sharing may be
899 increased on these systems.
902 bool "Machine Check / overheating reporting"
905 Machine Check support allows the processor to notify the
906 kernel if it detects a problem (e.g. overheating, data corruption).
907 The action the kernel takes depends on the severity of the problem,
908 ranging from warning messages to halting the machine.
912 prompt "Intel MCE features"
913 depends on X86_MCE && X86_LOCAL_APIC
915 Additional support for intel specific MCE features such as
920 prompt "AMD MCE features"
921 depends on X86_MCE && X86_LOCAL_APIC
923 Additional support for AMD specific MCE features such as
924 the DRAM Error Threshold.
926 config X86_ANCIENT_MCE
927 bool "Support for old Pentium 5 / WinChip machine checks"
928 depends on X86_32 && X86_MCE
930 Include support for machine check handling on old Pentium 5 or WinChip
931 systems. These typically need to be enabled explicitely on the command
934 config X86_MCE_THRESHOLD
935 depends on X86_MCE_AMD || X86_MCE_INTEL
938 config X86_MCE_INJECT
940 tristate "Machine check injector support"
942 Provide support for injecting machine checks for testing purposes.
943 If you don't know what a machine check is and you don't do kernel
944 QA it is safe to say n.
946 config X86_THERMAL_VECTOR
948 depends on X86_MCE_INTEL
951 bool "Enable VM86 support" if EXPERT
955 This option is required by programs like DOSEMU to run 16-bit legacy
956 code on X86 processors. It also may be needed by software like
957 XFree86 to initialize some video cards via BIOS. Disabling this
958 option saves about 6k.
961 tristate "Toshiba Laptop support"
964 This adds a driver to safely access the System Management Mode of
965 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
966 not work on models with a Phoenix BIOS. The System Management Mode
967 is used to set the BIOS and power saving options on Toshiba portables.
969 For information on utilities to make use of this driver see the
970 Toshiba Linux utilities web site at:
971 <http://www.buzzard.org.uk/toshiba/>.
973 Say Y if you intend to run this kernel on a Toshiba portable.
977 tristate "Dell laptop support"
980 This adds a driver to safely access the System Management Mode
981 of the CPU on the Dell Inspiron 8000. The System Management Mode
982 is used to read cpu temperature and cooling fan status and to
983 control the fans on the I8K portables.
985 This driver has been tested only on the Inspiron 8000 but it may
986 also work with other Dell laptops. You can force loading on other
987 models by passing the parameter `force=1' to the module. Use at
990 For information on utilities to make use of this driver see the
991 I8K Linux utilities web site at:
992 <http://people.debian.org/~dz/i8k/>
994 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
997 config X86_REBOOTFIXUPS
998 bool "Enable X86 board specific fixups for reboot"
1001 This enables chipset and/or board specific fixups to be done
1002 in order to get reboot to work correctly. This is only needed on
1003 some combinations of hardware and BIOS. The symptom, for which
1004 this config is intended, is when reboot ends with a stalled/hung
1007 Currently, the only fixup is for the Geode machines using
1008 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1010 Say Y if you want to enable the fixup. Currently, it's safe to
1011 enable this option even if you don't need it.
1015 tristate "CPU microcode loading support"
1019 If you say Y here, you will be able to update the microcode on
1020 certain Intel and AMD processors. The Intel support is for the
1021 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1022 Xeon etc. The AMD support is for families 0x10 and later. You will
1023 obviously need the actual microcode binary data itself which is not
1024 shipped with the Linux kernel.
1026 This option selects the general module only, you need to select
1027 at least one vendor specific module as well.
1029 To compile this driver as a module, choose M here: the module
1030 will be called microcode.
1032 config MICROCODE_INTEL
1033 bool "Intel microcode loading support"
1034 depends on MICROCODE
1038 This options enables microcode patch loading support for Intel
1041 For latest news and information on obtaining all the required
1042 Intel ingredients for this driver, check:
1043 <http://www.urbanmyth.org/microcode/>.
1045 config MICROCODE_AMD
1046 bool "AMD microcode loading support"
1047 depends on MICROCODE
1050 If you select this option, microcode patch loading support for AMD
1051 processors will be enabled.
1053 config MICROCODE_OLD_INTERFACE
1055 depends on MICROCODE
1057 config MICROCODE_INTEL_LIB
1059 depends on MICROCODE_INTEL
1061 config MICROCODE_INTEL_EARLY
1062 bool "Early load microcode"
1063 depends on MICROCODE_INTEL && BLK_DEV_INITRD
1066 This option provides functionality to read additional microcode data
1067 at the beginning of initrd image. The data tells kernel to load
1068 microcode to CPU's as early as possible. No functional change if no
1069 microcode data is glued to the initrd, therefore it's safe to say Y.
1071 config MICROCODE_EARLY
1073 depends on MICROCODE_INTEL_EARLY
1076 tristate "/dev/cpu/*/msr - Model-specific register support"
1078 This device gives privileged processes access to the x86
1079 Model-Specific Registers (MSRs). It is a character device with
1080 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1081 MSR accesses are directed to a specific CPU on multi-processor
1085 tristate "/dev/cpu/*/cpuid - CPU information support"
1087 This device gives processes access to the x86 CPUID instruction to
1088 be executed on a specific processor. It is a character device
1089 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1093 prompt "High Memory Support"
1094 default HIGHMEM64G if X86_NUMAQ
1100 depends on !X86_NUMAQ
1102 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1103 However, the address space of 32-bit x86 processors is only 4
1104 Gigabytes large. That means that, if you have a large amount of
1105 physical memory, not all of it can be "permanently mapped" by the
1106 kernel. The physical memory that's not permanently mapped is called
1109 If you are compiling a kernel which will never run on a machine with
1110 more than 1 Gigabyte total physical RAM, answer "off" here (default
1111 choice and suitable for most users). This will result in a "3GB/1GB"
1112 split: 3GB are mapped so that each process sees a 3GB virtual memory
1113 space and the remaining part of the 4GB virtual memory space is used
1114 by the kernel to permanently map as much physical memory as
1117 If the machine has between 1 and 4 Gigabytes physical RAM, then
1120 If more than 4 Gigabytes is used then answer "64GB" here. This
1121 selection turns Intel PAE (Physical Address Extension) mode on.
1122 PAE implements 3-level paging on IA32 processors. PAE is fully
1123 supported by Linux, PAE mode is implemented on all recent Intel
1124 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1125 then the kernel will not boot on CPUs that don't support PAE!
1127 The actual amount of total physical memory will either be
1128 auto detected or can be forced by using a kernel command line option
1129 such as "mem=256M". (Try "man bootparam" or see the documentation of
1130 your boot loader (lilo or loadlin) about how to pass options to the
1131 kernel at boot time.)
1133 If unsure, say "off".
1137 depends on !X86_NUMAQ
1139 Select this if you have a 32-bit processor and between 1 and 4
1140 gigabytes of physical RAM.
1147 Select this if you have a 32-bit processor and more than 4
1148 gigabytes of physical RAM.
1153 prompt "Memory split" if EXPERT
1157 Select the desired split between kernel and user memory.
1159 If the address range available to the kernel is less than the
1160 physical memory installed, the remaining memory will be available
1161 as "high memory". Accessing high memory is a little more costly
1162 than low memory, as it needs to be mapped into the kernel first.
1163 Note that increasing the kernel address space limits the range
1164 available to user programs, making the address space there
1165 tighter. Selecting anything other than the default 3G/1G split
1166 will also likely make your kernel incompatible with binary-only
1169 If you are not absolutely sure what you are doing, leave this
1173 bool "3G/1G user/kernel split"
1174 config VMSPLIT_3G_OPT
1176 bool "3G/1G user/kernel split (for full 1G low memory)"
1178 bool "2G/2G user/kernel split"
1179 config VMSPLIT_2G_OPT
1181 bool "2G/2G user/kernel split (for full 2G low memory)"
1183 bool "1G/3G user/kernel split"
1188 default 0xB0000000 if VMSPLIT_3G_OPT
1189 default 0x80000000 if VMSPLIT_2G
1190 default 0x78000000 if VMSPLIT_2G_OPT
1191 default 0x40000000 if VMSPLIT_1G
1197 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1200 bool "PAE (Physical Address Extension) Support"
1201 depends on X86_32 && !HIGHMEM4G
1203 PAE is required for NX support, and furthermore enables
1204 larger swapspace support for non-overcommit purposes. It
1205 has the cost of more pagetable lookup overhead, and also
1206 consumes more pagetable space per process.
1208 config ARCH_PHYS_ADDR_T_64BIT
1210 depends on X86_64 || X86_PAE
1212 config ARCH_DMA_ADDR_T_64BIT
1214 depends on X86_64 || HIGHMEM64G
1216 config DIRECT_GBPAGES
1217 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1221 Allow the kernel linear mapping to use 1GB pages on CPUs that
1222 support it. This can improve the kernel's performance a tiny bit by
1223 reducing TLB pressure. If in doubt, say "Y".
1225 # Common NUMA Features
1227 bool "Numa Memory Allocation and Scheduler Support"
1229 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1230 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1232 Enable NUMA (Non Uniform Memory Access) support.
1234 The kernel will try to allocate memory used by a CPU on the
1235 local memory controller of the CPU and add some more
1236 NUMA awareness to the kernel.
1238 For 64-bit this is recommended if the system is Intel Core i7
1239 (or later), AMD Opteron, or EM64T NUMA.
1241 For 32-bit this is only needed on (rare) 32-bit-only platforms
1242 that support NUMA topologies, such as NUMAQ / Summit, or if you
1243 boot a 32-bit kernel on a 64-bit NUMA platform.
1245 Otherwise, you should say N.
1247 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1248 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1252 prompt "Old style AMD Opteron NUMA detection"
1253 depends on X86_64 && NUMA && PCI
1255 Enable AMD NUMA node topology detection. You should say Y here if
1256 you have a multi processor AMD system. This uses an old method to
1257 read the NUMA configuration directly from the builtin Northbridge
1258 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1259 which also takes priority if both are compiled in.
1261 config X86_64_ACPI_NUMA
1263 prompt "ACPI NUMA detection"
1264 depends on X86_64 && NUMA && ACPI && PCI
1267 Enable ACPI SRAT based node topology detection.
1269 # Some NUMA nodes have memory ranges that span
1270 # other nodes. Even though a pfn is valid and
1271 # between a node's start and end pfns, it may not
1272 # reside on that node. See memmap_init_zone()
1274 config NODES_SPAN_OTHER_NODES
1276 depends on X86_64_ACPI_NUMA
1279 bool "NUMA emulation"
1282 Enable NUMA emulation. A flat machine will be split
1283 into virtual nodes when booted with "numa=fake=N", where N is the
1284 number of nodes. This is only useful for debugging.
1287 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1289 default "10" if MAXSMP
1290 default "6" if X86_64
1291 default "4" if X86_NUMAQ
1293 depends on NEED_MULTIPLE_NODES
1295 Specify the maximum number of NUMA Nodes available on the target
1296 system. Increases memory reserved to accommodate various tables.
1298 config ARCH_HAVE_MEMORY_PRESENT
1300 depends on X86_32 && DISCONTIGMEM
1302 config NEED_NODE_MEMMAP_SIZE
1304 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1306 config ARCH_FLATMEM_ENABLE
1308 depends on X86_32 && !NUMA
1310 config ARCH_DISCONTIGMEM_ENABLE
1312 depends on NUMA && X86_32
1314 config ARCH_DISCONTIGMEM_DEFAULT
1316 depends on NUMA && X86_32
1318 config ARCH_SPARSEMEM_ENABLE
1320 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1321 select SPARSEMEM_STATIC if X86_32
1322 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1324 config ARCH_SPARSEMEM_DEFAULT
1328 config ARCH_SELECT_MEMORY_MODEL
1330 depends on ARCH_SPARSEMEM_ENABLE
1332 config ARCH_MEMORY_PROBE
1334 depends on X86_64 && MEMORY_HOTPLUG
1336 config ARCH_PROC_KCORE_TEXT
1338 depends on X86_64 && PROC_KCORE
1340 config ILLEGAL_POINTER_VALUE
1343 default 0xdead000000000000 if X86_64
1348 bool "Allocate 3rd-level pagetables from highmem"
1351 The VM uses one page table entry for each page of physical memory.
1352 For systems with a lot of RAM, this can be wasteful of precious
1353 low memory. Setting this option will put user-space page table
1354 entries in high memory.
1356 config X86_CHECK_BIOS_CORRUPTION
1357 bool "Check for low memory corruption"
1359 Periodically check for memory corruption in low memory, which
1360 is suspected to be caused by BIOS. Even when enabled in the
1361 configuration, it is disabled at runtime. Enable it by
1362 setting "memory_corruption_check=1" on the kernel command
1363 line. By default it scans the low 64k of memory every 60
1364 seconds; see the memory_corruption_check_size and
1365 memory_corruption_check_period parameters in
1366 Documentation/kernel-parameters.txt to adjust this.
1368 When enabled with the default parameters, this option has
1369 almost no overhead, as it reserves a relatively small amount
1370 of memory and scans it infrequently. It both detects corruption
1371 and prevents it from affecting the running system.
1373 It is, however, intended as a diagnostic tool; if repeatable
1374 BIOS-originated corruption always affects the same memory,
1375 you can use memmap= to prevent the kernel from using that
1378 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1379 bool "Set the default setting of memory_corruption_check"
1380 depends on X86_CHECK_BIOS_CORRUPTION
1383 Set whether the default state of memory_corruption_check is
1386 config X86_RESERVE_LOW
1387 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1391 Specify the amount of low memory to reserve for the BIOS.
1393 The first page contains BIOS data structures that the kernel
1394 must not use, so that page must always be reserved.
1396 By default we reserve the first 64K of physical RAM, as a
1397 number of BIOSes are known to corrupt that memory range
1398 during events such as suspend/resume or monitor cable
1399 insertion, so it must not be used by the kernel.
1401 You can set this to 4 if you are absolutely sure that you
1402 trust the BIOS to get all its memory reservations and usages
1403 right. If you know your BIOS have problems beyond the
1404 default 64K area, you can set this to 640 to avoid using the
1405 entire low memory range.
1407 If you have doubts about the BIOS (e.g. suspend/resume does
1408 not work or there's kernel crashes after certain hardware
1409 hotplug events) then you might want to enable
1410 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1411 typical corruption patterns.
1413 Leave this to the default value of 64 if you are unsure.
1415 config MATH_EMULATION
1417 prompt "Math emulation" if X86_32
1419 Linux can emulate a math coprocessor (used for floating point
1420 operations) if you don't have one. 486DX and Pentium processors have
1421 a math coprocessor built in, 486SX and 386 do not, unless you added
1422 a 487DX or 387, respectively. (The messages during boot time can
1423 give you some hints here ["man dmesg"].) Everyone needs either a
1424 coprocessor or this emulation.
1426 If you don't have a math coprocessor, you need to say Y here; if you
1427 say Y here even though you have a coprocessor, the coprocessor will
1428 be used nevertheless. (This behavior can be changed with the kernel
1429 command line option "no387", which comes handy if your coprocessor
1430 is broken. Try "man bootparam" or see the documentation of your boot
1431 loader (lilo or loadlin) about how to pass options to the kernel at
1432 boot time.) This means that it is a good idea to say Y here if you
1433 intend to use this kernel on different machines.
1435 More information about the internals of the Linux math coprocessor
1436 emulation can be found in <file:arch/x86/math-emu/README>.
1438 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1439 kernel, it won't hurt.
1443 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1445 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1446 the Memory Type Range Registers (MTRRs) may be used to control
1447 processor access to memory ranges. This is most useful if you have
1448 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1449 allows bus write transfers to be combined into a larger transfer
1450 before bursting over the PCI/AGP bus. This can increase performance
1451 of image write operations 2.5 times or more. Saying Y here creates a
1452 /proc/mtrr file which may be used to manipulate your processor's
1453 MTRRs. Typically the X server should use this.
1455 This code has a reasonably generic interface so that similar
1456 control registers on other processors can be easily supported
1459 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1460 Registers (ARRs) which provide a similar functionality to MTRRs. For
1461 these, the ARRs are used to emulate the MTRRs.
1462 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1463 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1464 write-combining. All of these processors are supported by this code
1465 and it makes sense to say Y here if you have one of them.
1467 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1468 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1469 can lead to all sorts of problems, so it's good to say Y here.
1471 You can safely say Y even if your machine doesn't have MTRRs, you'll
1472 just add about 9 KB to your kernel.
1474 See <file:Documentation/x86/mtrr.txt> for more information.
1476 config MTRR_SANITIZER
1478 prompt "MTRR cleanup support"
1481 Convert MTRR layout from continuous to discrete, so X drivers can
1482 add writeback entries.
1484 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1485 The largest mtrr entry size for a continuous block can be set with
1490 config MTRR_SANITIZER_ENABLE_DEFAULT
1491 int "MTRR cleanup enable value (0-1)"
1494 depends on MTRR_SANITIZER
1496 Enable mtrr cleanup default value
1498 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1499 int "MTRR cleanup spare reg num (0-7)"
1502 depends on MTRR_SANITIZER
1504 mtrr cleanup spare entries default, it can be changed via
1505 mtrr_spare_reg_nr=N on the kernel command line.
1509 prompt "x86 PAT support" if EXPERT
1512 Use PAT attributes to setup page level cache control.
1514 PATs are the modern equivalents of MTRRs and are much more
1515 flexible than MTRRs.
1517 Say N here if you see bootup problems (boot crash, boot hang,
1518 spontaneous reboots) or a non-working video driver.
1522 config ARCH_USES_PG_UNCACHED
1528 prompt "x86 architectural random number generator" if EXPERT
1530 Enable the x86 architectural RDRAND instruction
1531 (Intel Bull Mountain technology) to generate random numbers.
1532 If supported, this is a high bandwidth, cryptographically
1533 secure hardware random number generator.
1537 prompt "Supervisor Mode Access Prevention" if EXPERT
1539 Supervisor Mode Access Prevention (SMAP) is a security
1540 feature in newer Intel processors. There is a small
1541 performance cost if this enabled and turned on; there is
1542 also a small increase in the kernel size if this is enabled.
1547 bool "EFI runtime service support"
1551 This enables the kernel to use EFI runtime services that are
1552 available (such as the EFI variable services).
1554 This option is only useful on systems that have EFI firmware.
1555 In addition, you should use the latest ELILO loader available
1556 at <http://elilo.sourceforge.net> in order to take advantage
1557 of EFI runtime services. However, even with this option, the
1558 resultant kernel should continue to boot on existing non-EFI
1562 bool "EFI stub support"
1565 This kernel feature allows a bzImage to be loaded directly
1566 by EFI firmware without the use of a bootloader.
1568 See Documentation/x86/efi-stub.txt for more information.
1572 prompt "Enable seccomp to safely compute untrusted bytecode"
1574 This kernel feature is useful for number crunching applications
1575 that may need to compute untrusted bytecode during their
1576 execution. By using pipes or other transports made available to
1577 the process as file descriptors supporting the read/write
1578 syscalls, it's possible to isolate those applications in
1579 their own address space using seccomp. Once seccomp is
1580 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1581 and the task is only allowed to execute a few safe syscalls
1582 defined by each seccomp mode.
1584 If unsure, say Y. Only embedded should say N here.
1586 config CC_STACKPROTECTOR
1587 bool "Enable -fstack-protector buffer overflow detection"
1589 This option turns on the -fstack-protector GCC feature. This
1590 feature puts, at the beginning of functions, a canary value on
1591 the stack just before the return address, and validates
1592 the value just before actually returning. Stack based buffer
1593 overflows (that need to overwrite this return address) now also
1594 overwrite the canary, which gets detected and the attack is then
1595 neutralized via a kernel panic.
1597 This feature requires gcc version 4.2 or above, or a distribution
1598 gcc with the feature backported. Older versions are automatically
1599 detected and for those versions, this configuration option is
1600 ignored. (and a warning is printed during bootup)
1602 source kernel/Kconfig.hz
1605 bool "kexec system call"
1607 kexec is a system call that implements the ability to shutdown your
1608 current kernel, and to start another kernel. It is like a reboot
1609 but it is independent of the system firmware. And like a reboot
1610 you can start any kernel with it, not just Linux.
1612 The name comes from the similarity to the exec system call.
1614 It is an ongoing process to be certain the hardware in a machine
1615 is properly shutdown, so do not be surprised if this code does not
1616 initially work for you. It may help to enable device hotplugging
1617 support. As of this writing the exact hardware interface is
1618 strongly in flux, so no good recommendation can be made.
1621 bool "kernel crash dumps"
1622 depends on X86_64 || (X86_32 && HIGHMEM)
1624 Generate crash dump after being started by kexec.
1625 This should be normally only set in special crash dump kernels
1626 which are loaded in the main kernel with kexec-tools into
1627 a specially reserved region and then later executed after
1628 a crash by kdump/kexec. The crash dump kernel must be compiled
1629 to a memory address not used by the main kernel or BIOS using
1630 PHYSICAL_START, or it must be built as a relocatable image
1631 (CONFIG_RELOCATABLE=y).
1632 For more details see Documentation/kdump/kdump.txt
1636 depends on KEXEC && HIBERNATION
1638 Jump between original kernel and kexeced kernel and invoke
1639 code in physical address mode via KEXEC
1641 config PHYSICAL_START
1642 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1645 This gives the physical address where the kernel is loaded.
1647 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1648 bzImage will decompress itself to above physical address and
1649 run from there. Otherwise, bzImage will run from the address where
1650 it has been loaded by the boot loader and will ignore above physical
1653 In normal kdump cases one does not have to set/change this option
1654 as now bzImage can be compiled as a completely relocatable image
1655 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1656 address. This option is mainly useful for the folks who don't want
1657 to use a bzImage for capturing the crash dump and want to use a
1658 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1659 to be specifically compiled to run from a specific memory area
1660 (normally a reserved region) and this option comes handy.
1662 So if you are using bzImage for capturing the crash dump,
1663 leave the value here unchanged to 0x1000000 and set
1664 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1665 for capturing the crash dump change this value to start of
1666 the reserved region. In other words, it can be set based on
1667 the "X" value as specified in the "crashkernel=YM@XM"
1668 command line boot parameter passed to the panic-ed
1669 kernel. Please take a look at Documentation/kdump/kdump.txt
1670 for more details about crash dumps.
1672 Usage of bzImage for capturing the crash dump is recommended as
1673 one does not have to build two kernels. Same kernel can be used
1674 as production kernel and capture kernel. Above option should have
1675 gone away after relocatable bzImage support is introduced. But it
1676 is present because there are users out there who continue to use
1677 vmlinux for dump capture. This option should go away down the
1680 Don't change this unless you know what you are doing.
1683 bool "Build a relocatable kernel"
1686 This builds a kernel image that retains relocation information
1687 so it can be loaded someplace besides the default 1MB.
1688 The relocations tend to make the kernel binary about 10% larger,
1689 but are discarded at runtime.
1691 One use is for the kexec on panic case where the recovery kernel
1692 must live at a different physical address than the primary
1695 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1696 it has been loaded at and the compile time physical address
1697 (CONFIG_PHYSICAL_START) is ignored.
1699 # Relocation on x86-32 needs some additional build support
1700 config X86_NEED_RELOCS
1702 depends on X86_32 && RELOCATABLE
1704 config PHYSICAL_ALIGN
1705 hex "Alignment value to which kernel should be aligned" if X86_32
1707 range 0x2000 0x1000000
1709 This value puts the alignment restrictions on physical address
1710 where kernel is loaded and run from. Kernel is compiled for an
1711 address which meets above alignment restriction.
1713 If bootloader loads the kernel at a non-aligned address and
1714 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1715 address aligned to above value and run from there.
1717 If bootloader loads the kernel at a non-aligned address and
1718 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1719 load address and decompress itself to the address it has been
1720 compiled for and run from there. The address for which kernel is
1721 compiled already meets above alignment restrictions. Hence the
1722 end result is that kernel runs from a physical address meeting
1723 above alignment restrictions.
1725 Don't change this unless you know what you are doing.
1728 bool "Support for hot-pluggable CPUs"
1729 depends on SMP && HOTPLUG
1731 Say Y here to allow turning CPUs off and on. CPUs can be
1732 controlled through /sys/devices/system/cpu.
1733 ( Note: power management support will enable this option
1734 automatically on SMP systems. )
1735 Say N if you want to disable CPU hotplug.
1737 config BOOTPARAM_HOTPLUG_CPU0
1738 bool "Set default setting of cpu0_hotpluggable"
1740 depends on HOTPLUG_CPU
1742 Set whether default state of cpu0_hotpluggable is on or off.
1744 Say Y here to enable CPU0 hotplug by default. If this switch
1745 is turned on, there is no need to give cpu0_hotplug kernel
1746 parameter and the CPU0 hotplug feature is enabled by default.
1748 Please note: there are two known CPU0 dependencies if you want
1749 to enable the CPU0 hotplug feature either by this switch or by
1750 cpu0_hotplug kernel parameter.
1752 First, resume from hibernate or suspend always starts from CPU0.
1753 So hibernate and suspend are prevented if CPU0 is offline.
1755 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1756 offline if any interrupt can not migrate out of CPU0. There may
1757 be other CPU0 dependencies.
1759 Please make sure the dependencies are under your control before
1760 you enable this feature.
1762 Say N if you don't want to enable CPU0 hotplug feature by default.
1763 You still can enable the CPU0 hotplug feature at boot by kernel
1764 parameter cpu0_hotplug.
1766 config DEBUG_HOTPLUG_CPU0
1768 prompt "Debug CPU0 hotplug"
1769 depends on HOTPLUG_CPU
1771 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1772 soon as possible and boots up userspace with CPU0 offlined. User
1773 can online CPU0 back after boot time.
1775 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1776 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1777 compilation or giving cpu0_hotplug kernel parameter at boot.
1783 prompt "Compat VDSO support"
1784 depends on X86_32 || IA32_EMULATION
1786 Map the 32-bit VDSO to the predictable old-style address too.
1788 Say N here if you are running a sufficiently recent glibc
1789 version (2.3.3 or later), to remove the high-mapped
1790 VDSO mapping and to exclusively use the randomized VDSO.
1795 bool "Built-in kernel command line"
1797 Allow for specifying boot arguments to the kernel at
1798 build time. On some systems (e.g. embedded ones), it is
1799 necessary or convenient to provide some or all of the
1800 kernel boot arguments with the kernel itself (that is,
1801 to not rely on the boot loader to provide them.)
1803 To compile command line arguments into the kernel,
1804 set this option to 'Y', then fill in the
1805 the boot arguments in CONFIG_CMDLINE.
1807 Systems with fully functional boot loaders (i.e. non-embedded)
1808 should leave this option set to 'N'.
1811 string "Built-in kernel command string"
1812 depends on CMDLINE_BOOL
1815 Enter arguments here that should be compiled into the kernel
1816 image and used at boot time. If the boot loader provides a
1817 command line at boot time, it is appended to this string to
1818 form the full kernel command line, when the system boots.
1820 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1821 change this behavior.
1823 In most cases, the command line (whether built-in or provided
1824 by the boot loader) should specify the device for the root
1827 config CMDLINE_OVERRIDE
1828 bool "Built-in command line overrides boot loader arguments"
1829 depends on CMDLINE_BOOL
1831 Set this option to 'Y' to have the kernel ignore the boot loader
1832 command line, and use ONLY the built-in command line.
1834 This is used to work around broken boot loaders. This should
1835 be set to 'N' under normal conditions.
1839 config ARCH_ENABLE_MEMORY_HOTPLUG
1841 depends on X86_64 || (X86_32 && HIGHMEM)
1843 config ARCH_ENABLE_MEMORY_HOTREMOVE
1845 depends on MEMORY_HOTPLUG
1847 config USE_PERCPU_NUMA_NODE_ID
1851 menu "Power management and ACPI options"
1853 config ARCH_HIBERNATION_HEADER
1855 depends on X86_64 && HIBERNATION
1857 source "kernel/power/Kconfig"
1859 source "drivers/acpi/Kconfig"
1861 source "drivers/sfi/Kconfig"
1868 tristate "APM (Advanced Power Management) BIOS support"
1869 depends on X86_32 && PM_SLEEP
1871 APM is a BIOS specification for saving power using several different
1872 techniques. This is mostly useful for battery powered laptops with
1873 APM compliant BIOSes. If you say Y here, the system time will be
1874 reset after a RESUME operation, the /proc/apm device will provide
1875 battery status information, and user-space programs will receive
1876 notification of APM "events" (e.g. battery status change).
1878 If you select "Y" here, you can disable actual use of the APM
1879 BIOS by passing the "apm=off" option to the kernel at boot time.
1881 Note that the APM support is almost completely disabled for
1882 machines with more than one CPU.
1884 In order to use APM, you will need supporting software. For location
1885 and more information, read <file:Documentation/power/apm-acpi.txt>
1886 and the Battery Powered Linux mini-HOWTO, available from
1887 <http://www.tldp.org/docs.html#howto>.
1889 This driver does not spin down disk drives (see the hdparm(8)
1890 manpage ("man 8 hdparm") for that), and it doesn't turn off
1891 VESA-compliant "green" monitors.
1893 This driver does not support the TI 4000M TravelMate and the ACER
1894 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1895 desktop machines also don't have compliant BIOSes, and this driver
1896 may cause those machines to panic during the boot phase.
1898 Generally, if you don't have a battery in your machine, there isn't
1899 much point in using this driver and you should say N. If you get
1900 random kernel OOPSes or reboots that don't seem to be related to
1901 anything, try disabling/enabling this option (or disabling/enabling
1904 Some other things you should try when experiencing seemingly random,
1907 1) make sure that you have enough swap space and that it is
1909 2) pass the "no-hlt" option to the kernel
1910 3) switch on floating point emulation in the kernel and pass
1911 the "no387" option to the kernel
1912 4) pass the "floppy=nodma" option to the kernel
1913 5) pass the "mem=4M" option to the kernel (thereby disabling
1914 all but the first 4 MB of RAM)
1915 6) make sure that the CPU is not over clocked.
1916 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1917 8) disable the cache from your BIOS settings
1918 9) install a fan for the video card or exchange video RAM
1919 10) install a better fan for the CPU
1920 11) exchange RAM chips
1921 12) exchange the motherboard.
1923 To compile this driver as a module, choose M here: the
1924 module will be called apm.
1928 config APM_IGNORE_USER_SUSPEND
1929 bool "Ignore USER SUSPEND"
1931 This option will ignore USER SUSPEND requests. On machines with a
1932 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1933 series notebooks, it is necessary to say Y because of a BIOS bug.
1935 config APM_DO_ENABLE
1936 bool "Enable PM at boot time"
1938 Enable APM features at boot time. From page 36 of the APM BIOS
1939 specification: "When disabled, the APM BIOS does not automatically
1940 power manage devices, enter the Standby State, enter the Suspend
1941 State, or take power saving steps in response to CPU Idle calls."
1942 This driver will make CPU Idle calls when Linux is idle (unless this
1943 feature is turned off -- see "Do CPU IDLE calls", below). This
1944 should always save battery power, but more complicated APM features
1945 will be dependent on your BIOS implementation. You may need to turn
1946 this option off if your computer hangs at boot time when using APM
1947 support, or if it beeps continuously instead of suspending. Turn
1948 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1949 T400CDT. This is off by default since most machines do fine without
1954 bool "Make CPU Idle calls when idle"
1956 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1957 On some machines, this can activate improved power savings, such as
1958 a slowed CPU clock rate, when the machine is idle. These idle calls
1959 are made after the idle loop has run for some length of time (e.g.,
1960 333 mS). On some machines, this will cause a hang at boot time or
1961 whenever the CPU becomes idle. (On machines with more than one CPU,
1962 this option does nothing.)
1964 config APM_DISPLAY_BLANK
1965 bool "Enable console blanking using APM"
1967 Enable console blanking using the APM. Some laptops can use this to
1968 turn off the LCD backlight when the screen blanker of the Linux
1969 virtual console blanks the screen. Note that this is only used by
1970 the virtual console screen blanker, and won't turn off the backlight
1971 when using the X Window system. This also doesn't have anything to
1972 do with your VESA-compliant power-saving monitor. Further, this
1973 option doesn't work for all laptops -- it might not turn off your
1974 backlight at all, or it might print a lot of errors to the console,
1975 especially if you are using gpm.
1977 config APM_ALLOW_INTS
1978 bool "Allow interrupts during APM BIOS calls"
1980 Normally we disable external interrupts while we are making calls to
1981 the APM BIOS as a measure to lessen the effects of a badly behaving
1982 BIOS implementation. The BIOS should reenable interrupts if it
1983 needs to. Unfortunately, some BIOSes do not -- especially those in
1984 many of the newer IBM Thinkpads. If you experience hangs when you
1985 suspend, try setting this to Y. Otherwise, say N.
1989 source "drivers/cpufreq/Kconfig"
1991 source "drivers/cpuidle/Kconfig"
1993 source "drivers/idle/Kconfig"
1998 menu "Bus options (PCI etc.)"
2003 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2005 Find out whether you have a PCI motherboard. PCI is the name of a
2006 bus system, i.e. the way the CPU talks to the other stuff inside
2007 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2008 VESA. If you have PCI, say Y, otherwise N.
2011 prompt "PCI access mode"
2012 depends on X86_32 && PCI
2015 On PCI systems, the BIOS can be used to detect the PCI devices and
2016 determine their configuration. However, some old PCI motherboards
2017 have BIOS bugs and may crash if this is done. Also, some embedded
2018 PCI-based systems don't have any BIOS at all. Linux can also try to
2019 detect the PCI hardware directly without using the BIOS.
2021 With this option, you can specify how Linux should detect the
2022 PCI devices. If you choose "BIOS", the BIOS will be used,
2023 if you choose "Direct", the BIOS won't be used, and if you
2024 choose "MMConfig", then PCI Express MMCONFIG will be used.
2025 If you choose "Any", the kernel will try MMCONFIG, then the
2026 direct access method and falls back to the BIOS if that doesn't
2027 work. If unsure, go with the default, which is "Any".
2032 config PCI_GOMMCONFIG
2049 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2051 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2054 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2058 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2062 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2066 depends on PCI && XEN
2074 bool "Support mmconfig PCI config space access"
2075 depends on X86_64 && PCI && ACPI
2077 config PCI_CNB20LE_QUIRK
2078 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2081 Read the PCI windows out of the CNB20LE host bridge. This allows
2082 PCI hotplug to work on systems with the CNB20LE chipset which do
2085 There's no public spec for this chipset, and this functionality
2086 is known to be incomplete.
2088 You should say N unless you know you need this.
2090 source "drivers/pci/pcie/Kconfig"
2092 source "drivers/pci/Kconfig"
2094 # x86_64 have no ISA slots, but can have ISA-style DMA.
2096 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2099 Enables ISA-style DMA support for devices requiring such controllers.
2107 Find out whether you have ISA slots on your motherboard. ISA is the
2108 name of a bus system, i.e. the way the CPU talks to the other stuff
2109 inside your box. Other bus systems are PCI, EISA, MicroChannel
2110 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2111 newer boards don't support it. If you have ISA, say Y, otherwise N.
2117 The Extended Industry Standard Architecture (EISA) bus was
2118 developed as an open alternative to the IBM MicroChannel bus.
2120 The EISA bus provided some of the features of the IBM MicroChannel
2121 bus while maintaining backward compatibility with cards made for
2122 the older ISA bus. The EISA bus saw limited use between 1988 and
2123 1995 when it was made obsolete by the PCI bus.
2125 Say Y here if you are building a kernel for an EISA-based machine.
2129 source "drivers/eisa/Kconfig"
2132 tristate "NatSemi SCx200 support"
2134 This provides basic support for National Semiconductor's
2135 (now AMD's) Geode processors. The driver probes for the
2136 PCI-IDs of several on-chip devices, so its a good dependency
2137 for other scx200_* drivers.
2139 If compiled as a module, the driver is named scx200.
2141 config SCx200HR_TIMER
2142 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2146 This driver provides a clocksource built upon the on-chip
2147 27MHz high-resolution timer. Its also a workaround for
2148 NSC Geode SC-1100's buggy TSC, which loses time when the
2149 processor goes idle (as is done by the scheduler). The
2150 other workaround is idle=poll boot option.
2153 bool "One Laptop Per Child support"
2160 Add support for detecting the unique features of the OLPC
2164 bool "OLPC XO-1 Power Management"
2165 depends on OLPC && MFD_CS5535 && PM_SLEEP
2168 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2171 bool "OLPC XO-1 Real Time Clock"
2172 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2174 Add support for the XO-1 real time clock, which can be used as a
2175 programmable wakeup source.
2178 bool "OLPC XO-1 SCI extras"
2179 depends on OLPC && OLPC_XO1_PM
2185 Add support for SCI-based features of the OLPC XO-1 laptop:
2186 - EC-driven system wakeups
2190 - AC adapter status updates
2191 - Battery status updates
2193 config OLPC_XO15_SCI
2194 bool "OLPC XO-1.5 SCI extras"
2195 depends on OLPC && ACPI
2198 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2199 - EC-driven system wakeups
2200 - AC adapter status updates
2201 - Battery status updates
2204 bool "PCEngines ALIX System Support (LED setup)"
2207 This option enables system support for the PCEngines ALIX.
2208 At present this just sets up LEDs for GPIO control on
2209 ALIX2/3/6 boards. However, other system specific setup should
2212 Note: You must still enable the drivers for GPIO and LED support
2213 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2215 Note: You have to set alix.force=1 for boards with Award BIOS.
2218 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2221 This option enables system support for the Soekris Engineering net5501.
2224 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2228 This option enables system support for the Traverse Technologies GEOS.
2231 bool "Technologic Systems TS-5500 platform support"
2233 select CHECK_SIGNATURE
2237 This option enables system support for the Technologic Systems TS-5500.
2243 depends on CPU_SUP_AMD && PCI
2245 source "drivers/pcmcia/Kconfig"
2247 source "drivers/pci/hotplug/Kconfig"
2250 bool "RapidIO support"
2254 If you say Y here, the kernel will include drivers and
2255 infrastructure code to support RapidIO interconnect devices.
2257 source "drivers/rapidio/Kconfig"
2262 menu "Executable file formats / Emulations"
2264 source "fs/Kconfig.binfmt"
2266 config IA32_EMULATION
2267 bool "IA32 Emulation"
2269 select COMPAT_BINFMT_ELF
2272 Include code to run legacy 32-bit programs under a
2273 64-bit kernel. You should likely turn this on, unless you're
2274 100% sure that you don't have any 32-bit programs left.
2277 tristate "IA32 a.out support"
2278 depends on IA32_EMULATION
2280 Support old a.out binaries in the 32bit emulation.
2283 bool "x32 ABI for 64-bit mode"
2284 depends on X86_64 && IA32_EMULATION
2286 Include code to run binaries for the x32 native 32-bit ABI
2287 for 64-bit processors. An x32 process gets access to the
2288 full 64-bit register file and wide data path while leaving
2289 pointers at 32 bits for smaller memory footprint.
2291 You will need a recent binutils (2.22 or later) with
2292 elf32_x86_64 support enabled to compile a kernel with this
2297 depends on IA32_EMULATION || X86_X32
2298 select ARCH_WANT_OLD_COMPAT_IPC
2301 config COMPAT_FOR_U64_ALIGNMENT
2304 config SYSVIPC_COMPAT
2316 config HAVE_ATOMIC_IOMAP
2320 config HAVE_TEXT_POKE_SMP
2322 select STOP_MACHINE if SMP
2324 config X86_DEV_DMA_OPS
2326 depends on X86_64 || STA2X11
2328 config X86_DMA_REMAP
2332 source "net/Kconfig"
2334 source "drivers/Kconfig"
2336 source "drivers/firmware/Kconfig"
2340 source "arch/x86/Kconfig.debug"
2342 source "security/Kconfig"
2344 source "crypto/Kconfig"
2346 source "arch/x86/kvm/Kconfig"
2348 source "lib/Kconfig"