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 HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
25 select ARCH_SUPPORTS_NUMA_BALANCING
26 select ARCH_WANTS_PROT_NUMA_PROT_NONE
29 select HAVE_PCSPKR_PLATFORM
30 select HAVE_PERF_EVENTS
31 select HAVE_IOREMAP_PROT
34 select HAVE_MEMBLOCK_NODE_MAP
35 select ARCH_DISCARD_MEMBLOCK
36 select ARCH_WANT_OPTIONAL_GPIOLIB
37 select ARCH_WANT_FRAME_POINTERS
39 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
40 select HAVE_KRETPROBES
42 select HAVE_KPROBES_ON_FTRACE
43 select HAVE_FTRACE_MCOUNT_RECORD
44 select HAVE_FENTRY if X86_64
45 select HAVE_C_RECORDMCOUNT
46 select HAVE_DYNAMIC_FTRACE
47 select HAVE_DYNAMIC_FTRACE_WITH_REGS
48 select HAVE_FUNCTION_TRACER
49 select HAVE_FUNCTION_GRAPH_TRACER
50 select HAVE_FUNCTION_GRAPH_FP_TEST
51 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
52 select HAVE_SYSCALL_TRACEPOINTS
53 select SYSCTL_EXCEPTION_TRACE
56 select HAVE_ARCH_TRACEHOOK
57 select HAVE_GENERIC_DMA_COHERENT if X86_32
58 select HAVE_EFFICIENT_UNALIGNED_ACCESS
59 select USER_STACKTRACE_SUPPORT
60 select HAVE_REGS_AND_STACK_ACCESS_API
61 select HAVE_DMA_API_DEBUG
62 select HAVE_KERNEL_GZIP
63 select HAVE_KERNEL_BZIP2
64 select HAVE_KERNEL_LZMA
66 select HAVE_KERNEL_LZO
67 select HAVE_HW_BREAKPOINT
68 select HAVE_MIXED_BREAKPOINTS_REGS
70 select HAVE_PERF_EVENTS_NMI
72 select HAVE_PERF_USER_STACK_DUMP
73 select HAVE_DEBUG_KMEMLEAK
75 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
76 select HAVE_CMPXCHG_LOCAL
77 select HAVE_CMPXCHG_DOUBLE
78 select HAVE_ARCH_KMEMCHECK
79 select HAVE_USER_RETURN_NOTIFIER
80 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
81 select HAVE_ARCH_JUMP_LABEL
82 select HAVE_TEXT_POKE_SMP
83 select HAVE_GENERIC_HARDIRQS
84 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
86 select GENERIC_FIND_FIRST_BIT
87 select GENERIC_IRQ_PROBE
88 select GENERIC_PENDING_IRQ if SMP
89 select GENERIC_IRQ_SHOW
90 select GENERIC_CLOCKEVENTS_MIN_ADJUST
91 select IRQ_FORCED_THREADING
92 select USE_GENERIC_SMP_HELPERS if SMP
93 select HAVE_BPF_JIT if X86_64
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
96 select ARCH_HAVE_NMI_SAFE_CMPXCHG
98 select DCACHE_WORD_ACCESS
99 select GENERIC_SMP_IDLE_THREAD
100 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
101 select HAVE_ARCH_SECCOMP_FILTER
102 select BUILDTIME_EXTABLE_SORT
103 select GENERIC_CMOS_UPDATE
104 select CLOCKSOURCE_WATCHDOG
105 select GENERIC_CLOCKEVENTS
106 select ARCH_CLOCKSOURCE_DATA if X86_64
107 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
108 select GENERIC_TIME_VSYSCALL if X86_64
109 select KTIME_SCALAR if X86_32
110 select ALWAYS_USE_PERSISTENT_CLOCK
111 select GENERIC_STRNCPY_FROM_USER
112 select GENERIC_STRNLEN_USER
113 select HAVE_CONTEXT_TRACKING if X86_64
114 select HAVE_IRQ_TIME_ACCOUNTING
115 select MODULES_USE_ELF_REL if X86_32
116 select MODULES_USE_ELF_RELA if X86_64
117 select CLONE_BACKWARDS if X86_32
118 select ARCH_USE_BUILTIN_BSWAP
119 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
120 select OLD_SIGACTION if X86_32
121 select COMPAT_OLD_SIGACTION if IA32_EMULATION
123 config INSTRUCTION_DECODER
125 depends on KPROBES || PERF_EVENTS || UPROBES
129 default "elf32-i386" if X86_32
130 default "elf64-x86-64" if X86_64
132 config ARCH_DEFCONFIG
134 default "arch/x86/configs/i386_defconfig" if X86_32
135 default "arch/x86/configs/x86_64_defconfig" if X86_64
137 config LOCKDEP_SUPPORT
140 config STACKTRACE_SUPPORT
143 config HAVE_LATENCYTOP_SUPPORT
152 config NEED_DMA_MAP_STATE
154 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
156 config NEED_SG_DMA_LENGTH
159 config GENERIC_ISA_DMA
161 depends on ISA_DMA_API
166 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
168 config GENERIC_BUG_RELATIVE_POINTERS
171 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_DEFAULT_IDLE
193 config ARCH_HAS_CACHE_LINE_SIZE
196 config ARCH_HAS_CPU_AUTOPROBE
199 config HAVE_SETUP_PER_CPU_AREA
202 config NEED_PER_CPU_EMBED_FIRST_CHUNK
205 config NEED_PER_CPU_PAGE_FIRST_CHUNK
208 config ARCH_HIBERNATION_POSSIBLE
211 config ARCH_SUSPEND_POSSIBLE
222 config ARCH_SUPPORTS_OPTIMIZED_INLINING
225 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
228 config HAVE_INTEL_TXT
230 depends on INTEL_IOMMU && ACPI
234 depends on X86_32 && SMP
238 depends on X86_64 && SMP
244 config X86_32_LAZY_GS
246 depends on X86_32 && !CC_STACKPROTECTOR
248 config ARCH_HWEIGHT_CFLAGS
250 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
251 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
253 config ARCH_CPU_PROBE_RELEASE
255 depends on HOTPLUG_CPU
257 config ARCH_SUPPORTS_UPROBES
260 source "init/Kconfig"
261 source "kernel/Kconfig.freezer"
263 menu "Processor type and features"
266 bool "DMA memory allocation support" if EXPERT
269 DMA memory allocation support allows devices with less than 32-bit
270 addressing to allocate within the first 16MB of address space.
271 Disable if no such devices will be used.
276 bool "Symmetric multi-processing support"
278 This enables support for systems with more than one CPU. If you have
279 a system with only one CPU, like most personal computers, say N. If
280 you have a system with more than one CPU, say Y.
282 If you say N here, the kernel will run on single and multiprocessor
283 machines, but will use only one CPU of a multiprocessor machine. If
284 you say Y here, the kernel will run on many, but not all,
285 singleprocessor machines. On a singleprocessor machine, the kernel
286 will run faster if you say N here.
288 Note that if you say Y here and choose architecture "586" or
289 "Pentium" under "Processor family", the kernel will not work on 486
290 architectures. Similarly, multiprocessor kernels for the "PPro"
291 architecture may not work on all Pentium based boards.
293 People using multiprocessor machines who say Y here should also say
294 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
295 Management" code will be disabled if you say Y here.
297 See also <file:Documentation/x86/i386/IO-APIC.txt>,
298 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
299 <http://www.tldp.org/docs.html#howto>.
301 If you don't know what to do here, say N.
304 bool "Support x2apic"
305 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
307 This enables x2apic support on CPUs that have this feature.
309 This allows 32-bit apic IDs (so it can support very large systems),
310 and accesses the local apic via MSRs not via mmio.
312 If you don't know what to do here, say N.
315 bool "Enable MPS table" if ACPI || SFI
317 depends on X86_LOCAL_APIC
319 For old smp systems that do not have proper acpi support. Newer systems
320 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
323 bool "Support for big SMP systems with more than 8 CPUs"
324 depends on X86_32 && SMP
326 This option is needed for the systems that have more than 8 CPUs
330 depends on X86_GOLDFISH
333 config X86_EXTENDED_PLATFORM
334 bool "Support for extended (non-PC) x86 platforms"
337 If you disable this option then the kernel will only support
338 standard PC platforms. (which covers the vast majority of
341 If you enable this option then you'll be able to select support
342 for the following (non-PC) 32 bit x86 platforms:
346 SGI 320/540 (Visual Workstation)
347 STA2X11-based (e.g. Northville)
348 Summit/EXA (IBM x440)
349 Unisys ES7000 IA32 series
350 Moorestown MID devices
352 If you have one of these systems, or if you want to build a
353 generic distribution kernel, say Y here - otherwise say N.
357 config X86_EXTENDED_PLATFORM
358 bool "Support for extended (non-PC) x86 platforms"
361 If you disable this option then the kernel will only support
362 standard PC platforms. (which covers the vast majority of
365 If you enable this option then you'll be able to select support
366 for the following (non-PC) 64 bit x86 platforms:
371 If you have one of these systems, or if you want to build a
372 generic distribution kernel, say Y here - otherwise say N.
374 # This is an alphabetically sorted list of 64 bit extended platforms
375 # Please maintain the alphabetic order if and when there are additions
377 bool "Numascale NumaChip"
379 depends on X86_EXTENDED_PLATFORM
382 depends on X86_X2APIC
383 depends on PCI_MMCONFIG
385 Adds support for Numascale NumaChip large-SMP systems. Needed to
386 enable more than ~168 cores.
387 If you don't have one of these, you should say N here.
391 select PARAVIRT_GUEST
393 depends on X86_64 && PCI
394 depends on X86_EXTENDED_PLATFORM
397 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
398 supposed to run on these EM64T-based machines. Only choose this option
399 if you have one of these machines.
402 bool "SGI Ultraviolet"
404 depends on X86_EXTENDED_PLATFORM
406 depends on X86_X2APIC
408 This option is needed in order to support SGI Ultraviolet systems.
409 If you don't have one of these, you should say N here.
411 # Following is an alphabetically sorted list of 32 bit extended platforms
412 # Please maintain the alphabetic order if and when there are additions
415 bool "Goldfish (Virtual Platform)"
418 Enable support for the Goldfish virtual platform used primarily
419 for Android development. Unless you are building for the Android
420 Goldfish emulator say N here.
423 bool "CE4100 TV platform"
425 depends on PCI_GODIRECT
427 depends on X86_EXTENDED_PLATFORM
428 select X86_REBOOTFIXUPS
430 select OF_EARLY_FLATTREE
433 Select for the Intel CE media processor (CE4100) SOC.
434 This option compiles in support for the CE4100 SOC for settop
435 boxes and media devices.
437 config X86_WANT_INTEL_MID
438 bool "Intel MID platform support"
440 depends on X86_EXTENDED_PLATFORM
442 Select to build a kernel capable of supporting Intel MID platform
443 systems which do not have the PCI legacy interfaces (Moorestown,
444 Medfield). If you are building for a PC class system say N here.
446 if X86_WANT_INTEL_MID
452 bool "Medfield MID platform"
455 depends on X86_IO_APIC
463 select X86_PLATFORM_DEVICES
464 select MFD_INTEL_MSIC
466 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
467 Internet Device(MID) platform.
468 Unlike standard x86 PCs, Medfield does not have many legacy devices
469 nor standard legacy replacement devices/features. e.g. Medfield does
470 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
474 config X86_INTEL_LPSS
475 bool "Intel Low Power Subsystem Support"
479 Select to build support for Intel Low Power Subsystem such as
480 found on Intel Lynxpoint PCH. Selecting this option enables
481 things like clock tree (common clock framework) which are needed
482 by the LPSS peripheral drivers.
485 bool "RDC R-321x SoC"
487 depends on X86_EXTENDED_PLATFORM
489 select X86_REBOOTFIXUPS
491 This option is needed for RDC R-321x system-on-chip, also known
493 If you don't have one of these chips, you should say N here.
495 config X86_32_NON_STANDARD
496 bool "Support non-standard 32-bit SMP architectures"
497 depends on X86_32 && SMP
498 depends on X86_EXTENDED_PLATFORM
500 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
501 STA2X11, default subarchitectures. It is intended for a generic
502 binary kernel. If you select them all, kernel will probe it
503 one by one and will fallback to default.
505 # Alphabetically sorted list of Non standard 32 bit platforms
508 bool "NUMAQ (IBM/Sequent)"
509 depends on X86_32_NON_STANDARD
514 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
515 NUMA multiquad box. This changes the way that processors are
516 bootstrapped, and uses Clustered Logical APIC addressing mode instead
517 of Flat Logical. You will need a new lynxer.elf file to flash your
518 firmware with - send email to <Martin.Bligh@us.ibm.com>.
520 config X86_SUPPORTS_MEMORY_FAILURE
522 # MCE code calls memory_failure():
524 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
525 depends on !X86_NUMAQ
526 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
527 depends on X86_64 || !SPARSEMEM
528 select ARCH_SUPPORTS_MEMORY_FAILURE
531 bool "SGI 320/540 (Visual Workstation)"
532 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
533 depends on X86_32_NON_STANDARD
535 The SGI Visual Workstation series is an IA32-based workstation
536 based on SGI systems chips with some legacy PC hardware attached.
538 Say Y here to create a kernel to run on the SGI 320 or 540.
540 A kernel compiled for the Visual Workstation will run on general
541 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
544 bool "STA2X11 Companion Chip Support"
545 depends on X86_32_NON_STANDARD && PCI
546 select X86_DEV_DMA_OPS
550 select ARCH_REQUIRE_GPIOLIB
553 This adds support for boards based on the STA2X11 IO-Hub,
554 a.k.a. "ConneXt". The chip is used in place of the standard
555 PC chipset, so all "standard" peripherals are missing. If this
556 option is selected the kernel will still be able to boot on
557 standard PC machines.
560 bool "Summit/EXA (IBM x440)"
561 depends on X86_32_NON_STANDARD
563 This option is needed for IBM systems that use the Summit/EXA chipset.
564 In particular, it is needed for the x440.
567 bool "Unisys ES7000 IA32 series"
568 depends on X86_32_NON_STANDARD && X86_BIGSMP
570 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
571 supposed to run on an IA32-based Unisys ES7000 system.
574 tristate "Eurobraille/Iris poweroff module"
577 The Iris machines from EuroBraille do not have APM or ACPI support
578 to shut themselves down properly. A special I/O sequence is
579 needed to do so, which is what this module does at
582 This is only for Iris machines from EuroBraille.
586 config SCHED_OMIT_FRAME_POINTER
588 prompt "Single-depth WCHAN output"
591 Calculate simpler /proc/<PID>/wchan values. If this option
592 is disabled then wchan values will recurse back to the
593 caller function. This provides more accurate wchan values,
594 at the expense of slightly more scheduling overhead.
596 If in doubt, say "Y".
598 menuconfig PARAVIRT_GUEST
599 bool "Paravirtualized guest support"
601 Say Y here to get to see options related to running Linux under
602 various hypervisors. This option alone does not add any kernel code.
604 If you say N, all options in this submenu will be skipped and disabled.
608 config PARAVIRT_TIME_ACCOUNTING
609 bool "Paravirtual steal time accounting"
613 Select this option to enable fine granularity task steal time
614 accounting. Time spent executing other tasks in parallel with
615 the current vCPU is discounted from the vCPU power. To account for
616 that, there can be a small performance impact.
618 If in doubt, say N here.
620 source "arch/x86/xen/Kconfig"
623 bool "KVM Guest support (including kvmclock)"
626 select PARAVIRT_CLOCK
627 default y if PARAVIRT_GUEST
629 This option enables various optimizations for running under the KVM
630 hypervisor. It includes a paravirtualized clock, so that instead
631 of relying on a PIT (or probably other) emulation by the
632 underlying device model, the host provides the guest with
633 timing infrastructure such as time of day, and system time
635 source "arch/x86/lguest/Kconfig"
638 bool "Enable paravirtualization code"
640 This changes the kernel so it can modify itself when it is run
641 under a hypervisor, potentially improving performance significantly
642 over full virtualization. However, when run without a hypervisor
643 the kernel is theoretically slower and slightly larger.
645 config PARAVIRT_SPINLOCKS
646 bool "Paravirtualization layer for spinlocks"
647 depends on PARAVIRT && SMP
649 Paravirtualized spinlocks allow a pvops backend to replace the
650 spinlock implementation with something virtualization-friendly
651 (for example, block the virtual CPU rather than spinning).
653 Unfortunately the downside is an up to 5% performance hit on
654 native kernels, with various workloads.
656 If you are unsure how to answer this question, answer N.
658 config PARAVIRT_CLOCK
663 config PARAVIRT_DEBUG
664 bool "paravirt-ops debugging"
665 depends on PARAVIRT && DEBUG_KERNEL
667 Enable to debug paravirt_ops internals. Specifically, BUG if
668 a paravirt_op is missing when it is called.
676 This option adds a kernel parameter 'memtest', which allows memtest
678 memtest=0, mean disabled; -- default
679 memtest=1, mean do 1 test pattern;
681 memtest=4, mean do 4 test patterns.
682 If you are unsure how to answer this question, answer N.
684 config X86_SUMMIT_NUMA
686 depends on X86_32 && NUMA && X86_32_NON_STANDARD
688 config X86_CYCLONE_TIMER
690 depends on X86_SUMMIT
692 source "arch/x86/Kconfig.cpu"
696 prompt "HPET Timer Support" if X86_32
698 Use the IA-PC HPET (High Precision Event Timer) to manage
699 time in preference to the PIT and RTC, if a HPET is
701 HPET is the next generation timer replacing legacy 8254s.
702 The HPET provides a stable time base on SMP
703 systems, unlike the TSC, but it is more expensive to access,
704 as it is off-chip. You can find the HPET spec at
705 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
707 You can safely choose Y here. However, HPET will only be
708 activated if the platform and the BIOS support this feature.
709 Otherwise the 8254 will be used for timing services.
711 Choose N to continue using the legacy 8254 timer.
713 config HPET_EMULATE_RTC
715 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
718 def_bool y if X86_INTEL_MID
719 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
721 depends on X86_INTEL_MID && SFI
723 APB timer is the replacement for 8254, HPET on X86 MID platforms.
724 The APBT provides a stable time base on SMP
725 systems, unlike the TSC, but it is more expensive to access,
726 as it is off-chip. APB timers are always running regardless of CPU
727 C states, they are used as per CPU clockevent device when possible.
729 # Mark as expert because too many people got it wrong.
730 # The code disables itself when not needed.
733 bool "Enable DMI scanning" if EXPERT
735 Enabled scanning of DMI to identify machine quirks. Say Y
736 here unless you have verified that your setup is not
737 affected by entries in the DMI blacklist. Required by PNP
741 bool "GART IOMMU support" if EXPERT
744 depends on X86_64 && PCI && AMD_NB
746 Support for full DMA access of devices with 32bit memory access only
747 on systems with more than 3GB. This is usually needed for USB,
748 sound, many IDE/SATA chipsets and some other devices.
749 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
750 based hardware IOMMU and a software bounce buffer based IOMMU used
751 on Intel systems and as fallback.
752 The code is only active when needed (enough memory and limited
753 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
757 bool "IBM Calgary IOMMU support"
759 depends on X86_64 && PCI
761 Support for hardware IOMMUs in IBM's xSeries x366 and x460
762 systems. Needed to run systems with more than 3GB of memory
763 properly with 32-bit PCI devices that do not support DAC
764 (Double Address Cycle). Calgary also supports bus level
765 isolation, where all DMAs pass through the IOMMU. This
766 prevents them from going anywhere except their intended
767 destination. This catches hard-to-find kernel bugs and
768 mis-behaving drivers and devices that do not use the DMA-API
769 properly to set up their DMA buffers. The IOMMU can be
770 turned off at boot time with the iommu=off parameter.
771 Normally the kernel will make the right choice by itself.
774 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
776 prompt "Should Calgary be enabled by default?"
777 depends on CALGARY_IOMMU
779 Should Calgary be enabled by default? if you choose 'y', Calgary
780 will be used (if it exists). If you choose 'n', Calgary will not be
781 used even if it exists. If you choose 'n' and would like to use
782 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
785 # need this always selected by IOMMU for the VIA workaround
789 Support for software bounce buffers used on x86-64 systems
790 which don't have a hardware IOMMU. Using this PCI devices
791 which can only access 32-bits of memory can be used on systems
792 with more than 3 GB of memory.
797 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
800 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
801 depends on X86_64 && SMP && DEBUG_KERNEL
802 select CPUMASK_OFFSTACK
804 Enable maximum number of CPUS and NUMA Nodes for this architecture.
808 int "Maximum number of CPUs" if SMP && !MAXSMP
809 range 2 8 if SMP && X86_32 && !X86_BIGSMP
810 range 2 512 if SMP && !MAXSMP
812 default "4096" if MAXSMP
813 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
816 This allows you to specify the maximum number of CPUs which this
817 kernel will support. The maximum supported value is 512 and the
818 minimum value which makes sense is 2.
820 This is purely to save memory - each supported CPU adds
821 approximately eight kilobytes to the kernel image.
824 bool "SMT (Hyperthreading) scheduler support"
827 SMT scheduler support improves the CPU scheduler's decision making
828 when dealing with Intel Pentium 4 chips with HyperThreading at a
829 cost of slightly increased overhead in some places. If unsure say
834 prompt "Multi-core scheduler support"
837 Multi-core scheduler support improves the CPU scheduler's decision
838 making when dealing with multi-core CPU chips at a cost of slightly
839 increased overhead in some places. If unsure say N here.
841 source "kernel/Kconfig.preempt"
844 bool "Local APIC support on uniprocessors"
845 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
847 A local APIC (Advanced Programmable Interrupt Controller) is an
848 integrated interrupt controller in the CPU. If you have a single-CPU
849 system which has a processor with a local APIC, you can say Y here to
850 enable and use it. If you say Y here even though your machine doesn't
851 have a local APIC, then the kernel will still run with no slowdown at
852 all. The local APIC supports CPU-generated self-interrupts (timer,
853 performance counters), and the NMI watchdog which detects hard
857 bool "IO-APIC support on uniprocessors"
858 depends on X86_UP_APIC
860 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
861 SMP-capable replacement for PC-style interrupt controllers. Most
862 SMP systems and many recent uniprocessor systems have one.
864 If you have a single-CPU system with an IO-APIC, you can say Y here
865 to use it. If you say Y here even though your machine doesn't have
866 an IO-APIC, then the kernel will still run with no slowdown at all.
868 config X86_LOCAL_APIC
870 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
874 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
876 config X86_VISWS_APIC
878 depends on X86_32 && X86_VISWS
880 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
881 bool "Reroute for broken boot IRQs"
882 depends on X86_IO_APIC
884 This option enables a workaround that fixes a source of
885 spurious interrupts. This is recommended when threaded
886 interrupt handling is used on systems where the generation of
887 superfluous "boot interrupts" cannot be disabled.
889 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
890 entry in the chipset's IO-APIC is masked (as, e.g. the RT
891 kernel does during interrupt handling). On chipsets where this
892 boot IRQ generation cannot be disabled, this workaround keeps
893 the original IRQ line masked so that only the equivalent "boot
894 IRQ" is delivered to the CPUs. The workaround also tells the
895 kernel to set up the IRQ handler on the boot IRQ line. In this
896 way only one interrupt is delivered to the kernel. Otherwise
897 the spurious second interrupt may cause the kernel to bring
898 down (vital) interrupt lines.
900 Only affects "broken" chipsets. Interrupt sharing may be
901 increased on these systems.
904 bool "Machine Check / overheating reporting"
907 Machine Check support allows the processor to notify the
908 kernel if it detects a problem (e.g. overheating, data corruption).
909 The action the kernel takes depends on the severity of the problem,
910 ranging from warning messages to halting the machine.
914 prompt "Intel MCE features"
915 depends on X86_MCE && X86_LOCAL_APIC
917 Additional support for intel specific MCE features such as
922 prompt "AMD MCE features"
923 depends on X86_MCE && X86_LOCAL_APIC
925 Additional support for AMD specific MCE features such as
926 the DRAM Error Threshold.
928 config X86_ANCIENT_MCE
929 bool "Support for old Pentium 5 / WinChip machine checks"
930 depends on X86_32 && X86_MCE
932 Include support for machine check handling on old Pentium 5 or WinChip
933 systems. These typically need to be enabled explicitely on the command
936 config X86_MCE_THRESHOLD
937 depends on X86_MCE_AMD || X86_MCE_INTEL
940 config X86_MCE_INJECT
942 tristate "Machine check injector support"
944 Provide support for injecting machine checks for testing purposes.
945 If you don't know what a machine check is and you don't do kernel
946 QA it is safe to say n.
948 config X86_THERMAL_VECTOR
950 depends on X86_MCE_INTEL
953 bool "Enable VM86 support" if EXPERT
957 This option is required by programs like DOSEMU to run 16-bit legacy
958 code on X86 processors. It also may be needed by software like
959 XFree86 to initialize some video cards via BIOS. Disabling this
960 option saves about 6k.
963 tristate "Toshiba Laptop support"
966 This adds a driver to safely access the System Management Mode of
967 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
968 not work on models with a Phoenix BIOS. The System Management Mode
969 is used to set the BIOS and power saving options on Toshiba portables.
971 For information on utilities to make use of this driver see the
972 Toshiba Linux utilities web site at:
973 <http://www.buzzard.org.uk/toshiba/>.
975 Say Y if you intend to run this kernel on a Toshiba portable.
979 tristate "Dell laptop support"
982 This adds a driver to safely access the System Management Mode
983 of the CPU on the Dell Inspiron 8000. The System Management Mode
984 is used to read cpu temperature and cooling fan status and to
985 control the fans on the I8K portables.
987 This driver has been tested only on the Inspiron 8000 but it may
988 also work with other Dell laptops. You can force loading on other
989 models by passing the parameter `force=1' to the module. Use at
992 For information on utilities to make use of this driver see the
993 I8K Linux utilities web site at:
994 <http://people.debian.org/~dz/i8k/>
996 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
999 config X86_REBOOTFIXUPS
1000 bool "Enable X86 board specific fixups for reboot"
1003 This enables chipset and/or board specific fixups to be done
1004 in order to get reboot to work correctly. This is only needed on
1005 some combinations of hardware and BIOS. The symptom, for which
1006 this config is intended, is when reboot ends with a stalled/hung
1009 Currently, the only fixup is for the Geode machines using
1010 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1012 Say Y if you want to enable the fixup. Currently, it's safe to
1013 enable this option even if you don't need it.
1017 tristate "CPU microcode loading support"
1021 If you say Y here, you will be able to update the microcode on
1022 certain Intel and AMD processors. The Intel support is for the
1023 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1024 Xeon etc. The AMD support is for families 0x10 and later. You will
1025 obviously need the actual microcode binary data itself which is not
1026 shipped with the Linux kernel.
1028 This option selects the general module only, you need to select
1029 at least one vendor specific module as well.
1031 To compile this driver as a module, choose M here: the module
1032 will be called microcode.
1034 config MICROCODE_INTEL
1035 bool "Intel microcode loading support"
1036 depends on MICROCODE
1040 This options enables microcode patch loading support for Intel
1043 For latest news and information on obtaining all the required
1044 Intel ingredients for this driver, check:
1045 <http://www.urbanmyth.org/microcode/>.
1047 config MICROCODE_AMD
1048 bool "AMD microcode loading support"
1049 depends on MICROCODE
1052 If you select this option, microcode patch loading support for AMD
1053 processors will be enabled.
1055 config MICROCODE_OLD_INTERFACE
1057 depends on MICROCODE
1059 config MICROCODE_INTEL_LIB
1061 depends on MICROCODE_INTEL
1063 config MICROCODE_INTEL_EARLY
1064 bool "Early load microcode"
1065 depends on MICROCODE_INTEL && BLK_DEV_INITRD
1068 This option provides functionality to read additional microcode data
1069 at the beginning of initrd image. The data tells kernel to load
1070 microcode to CPU's as early as possible. No functional change if no
1071 microcode data is glued to the initrd, therefore it's safe to say Y.
1073 config MICROCODE_EARLY
1075 depends on MICROCODE_INTEL_EARLY
1078 tristate "/dev/cpu/*/msr - Model-specific register support"
1080 This device gives privileged processes access to the x86
1081 Model-Specific Registers (MSRs). It is a character device with
1082 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1083 MSR accesses are directed to a specific CPU on multi-processor
1087 tristate "/dev/cpu/*/cpuid - CPU information support"
1089 This device gives processes access to the x86 CPUID instruction to
1090 be executed on a specific processor. It is a character device
1091 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1095 prompt "High Memory Support"
1096 default HIGHMEM64G if X86_NUMAQ
1102 depends on !X86_NUMAQ
1104 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1105 However, the address space of 32-bit x86 processors is only 4
1106 Gigabytes large. That means that, if you have a large amount of
1107 physical memory, not all of it can be "permanently mapped" by the
1108 kernel. The physical memory that's not permanently mapped is called
1111 If you are compiling a kernel which will never run on a machine with
1112 more than 1 Gigabyte total physical RAM, answer "off" here (default
1113 choice and suitable for most users). This will result in a "3GB/1GB"
1114 split: 3GB are mapped so that each process sees a 3GB virtual memory
1115 space and the remaining part of the 4GB virtual memory space is used
1116 by the kernel to permanently map as much physical memory as
1119 If the machine has between 1 and 4 Gigabytes physical RAM, then
1122 If more than 4 Gigabytes is used then answer "64GB" here. This
1123 selection turns Intel PAE (Physical Address Extension) mode on.
1124 PAE implements 3-level paging on IA32 processors. PAE is fully
1125 supported by Linux, PAE mode is implemented on all recent Intel
1126 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1127 then the kernel will not boot on CPUs that don't support PAE!
1129 The actual amount of total physical memory will either be
1130 auto detected or can be forced by using a kernel command line option
1131 such as "mem=256M". (Try "man bootparam" or see the documentation of
1132 your boot loader (lilo or loadlin) about how to pass options to the
1133 kernel at boot time.)
1135 If unsure, say "off".
1139 depends on !X86_NUMAQ
1141 Select this if you have a 32-bit processor and between 1 and 4
1142 gigabytes of physical RAM.
1149 Select this if you have a 32-bit processor and more than 4
1150 gigabytes of physical RAM.
1155 prompt "Memory split" if EXPERT
1159 Select the desired split between kernel and user memory.
1161 If the address range available to the kernel is less than the
1162 physical memory installed, the remaining memory will be available
1163 as "high memory". Accessing high memory is a little more costly
1164 than low memory, as it needs to be mapped into the kernel first.
1165 Note that increasing the kernel address space limits the range
1166 available to user programs, making the address space there
1167 tighter. Selecting anything other than the default 3G/1G split
1168 will also likely make your kernel incompatible with binary-only
1171 If you are not absolutely sure what you are doing, leave this
1175 bool "3G/1G user/kernel split"
1176 config VMSPLIT_3G_OPT
1178 bool "3G/1G user/kernel split (for full 1G low memory)"
1180 bool "2G/2G user/kernel split"
1181 config VMSPLIT_2G_OPT
1183 bool "2G/2G user/kernel split (for full 2G low memory)"
1185 bool "1G/3G user/kernel split"
1190 default 0xB0000000 if VMSPLIT_3G_OPT
1191 default 0x80000000 if VMSPLIT_2G
1192 default 0x78000000 if VMSPLIT_2G_OPT
1193 default 0x40000000 if VMSPLIT_1G
1199 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1202 bool "PAE (Physical Address Extension) Support"
1203 depends on X86_32 && !HIGHMEM4G
1205 PAE is required for NX support, and furthermore enables
1206 larger swapspace support for non-overcommit purposes. It
1207 has the cost of more pagetable lookup overhead, and also
1208 consumes more pagetable space per process.
1210 config ARCH_PHYS_ADDR_T_64BIT
1212 depends on X86_64 || X86_PAE
1214 config ARCH_DMA_ADDR_T_64BIT
1216 depends on X86_64 || HIGHMEM64G
1218 config DIRECT_GBPAGES
1219 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1223 Allow the kernel linear mapping to use 1GB pages on CPUs that
1224 support it. This can improve the kernel's performance a tiny bit by
1225 reducing TLB pressure. If in doubt, say "Y".
1227 # Common NUMA Features
1229 bool "Numa Memory Allocation and Scheduler Support"
1231 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1232 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1234 Enable NUMA (Non Uniform Memory Access) support.
1236 The kernel will try to allocate memory used by a CPU on the
1237 local memory controller of the CPU and add some more
1238 NUMA awareness to the kernel.
1240 For 64-bit this is recommended if the system is Intel Core i7
1241 (or later), AMD Opteron, or EM64T NUMA.
1243 For 32-bit this is only needed on (rare) 32-bit-only platforms
1244 that support NUMA topologies, such as NUMAQ / Summit, or if you
1245 boot a 32-bit kernel on a 64-bit NUMA platform.
1247 Otherwise, you should say N.
1249 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1250 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1254 prompt "Old style AMD Opteron NUMA detection"
1255 depends on X86_64 && NUMA && PCI
1257 Enable AMD NUMA node topology detection. You should say Y here if
1258 you have a multi processor AMD system. This uses an old method to
1259 read the NUMA configuration directly from the builtin Northbridge
1260 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1261 which also takes priority if both are compiled in.
1263 config X86_64_ACPI_NUMA
1265 prompt "ACPI NUMA detection"
1266 depends on X86_64 && NUMA && ACPI && PCI
1269 Enable ACPI SRAT based node topology detection.
1271 # Some NUMA nodes have memory ranges that span
1272 # other nodes. Even though a pfn is valid and
1273 # between a node's start and end pfns, it may not
1274 # reside on that node. See memmap_init_zone()
1276 config NODES_SPAN_OTHER_NODES
1278 depends on X86_64_ACPI_NUMA
1281 bool "NUMA emulation"
1284 Enable NUMA emulation. A flat machine will be split
1285 into virtual nodes when booted with "numa=fake=N", where N is the
1286 number of nodes. This is only useful for debugging.
1289 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1291 default "10" if MAXSMP
1292 default "6" if X86_64
1293 default "4" if X86_NUMAQ
1295 depends on NEED_MULTIPLE_NODES
1297 Specify the maximum number of NUMA Nodes available on the target
1298 system. Increases memory reserved to accommodate various tables.
1300 config ARCH_HAVE_MEMORY_PRESENT
1302 depends on X86_32 && DISCONTIGMEM
1304 config NEED_NODE_MEMMAP_SIZE
1306 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1308 config ARCH_FLATMEM_ENABLE
1310 depends on X86_32 && !NUMA
1312 config ARCH_DISCONTIGMEM_ENABLE
1314 depends on NUMA && X86_32
1316 config ARCH_DISCONTIGMEM_DEFAULT
1318 depends on NUMA && X86_32
1320 config ARCH_SPARSEMEM_ENABLE
1322 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1323 select SPARSEMEM_STATIC if X86_32
1324 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1326 config ARCH_SPARSEMEM_DEFAULT
1330 config ARCH_SELECT_MEMORY_MODEL
1332 depends on ARCH_SPARSEMEM_ENABLE
1334 config ARCH_MEMORY_PROBE
1336 depends on X86_64 && MEMORY_HOTPLUG
1338 config ARCH_PROC_KCORE_TEXT
1340 depends on X86_64 && PROC_KCORE
1342 config ILLEGAL_POINTER_VALUE
1345 default 0xdead000000000000 if X86_64
1350 bool "Allocate 3rd-level pagetables from highmem"
1353 The VM uses one page table entry for each page of physical memory.
1354 For systems with a lot of RAM, this can be wasteful of precious
1355 low memory. Setting this option will put user-space page table
1356 entries in high memory.
1358 config X86_CHECK_BIOS_CORRUPTION
1359 bool "Check for low memory corruption"
1361 Periodically check for memory corruption in low memory, which
1362 is suspected to be caused by BIOS. Even when enabled in the
1363 configuration, it is disabled at runtime. Enable it by
1364 setting "memory_corruption_check=1" on the kernel command
1365 line. By default it scans the low 64k of memory every 60
1366 seconds; see the memory_corruption_check_size and
1367 memory_corruption_check_period parameters in
1368 Documentation/kernel-parameters.txt to adjust this.
1370 When enabled with the default parameters, this option has
1371 almost no overhead, as it reserves a relatively small amount
1372 of memory and scans it infrequently. It both detects corruption
1373 and prevents it from affecting the running system.
1375 It is, however, intended as a diagnostic tool; if repeatable
1376 BIOS-originated corruption always affects the same memory,
1377 you can use memmap= to prevent the kernel from using that
1380 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1381 bool "Set the default setting of memory_corruption_check"
1382 depends on X86_CHECK_BIOS_CORRUPTION
1385 Set whether the default state of memory_corruption_check is
1388 config X86_RESERVE_LOW
1389 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1393 Specify the amount of low memory to reserve for the BIOS.
1395 The first page contains BIOS data structures that the kernel
1396 must not use, so that page must always be reserved.
1398 By default we reserve the first 64K of physical RAM, as a
1399 number of BIOSes are known to corrupt that memory range
1400 during events such as suspend/resume or monitor cable
1401 insertion, so it must not be used by the kernel.
1403 You can set this to 4 if you are absolutely sure that you
1404 trust the BIOS to get all its memory reservations and usages
1405 right. If you know your BIOS have problems beyond the
1406 default 64K area, you can set this to 640 to avoid using the
1407 entire low memory range.
1409 If you have doubts about the BIOS (e.g. suspend/resume does
1410 not work or there's kernel crashes after certain hardware
1411 hotplug events) then you might want to enable
1412 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1413 typical corruption patterns.
1415 Leave this to the default value of 64 if you are unsure.
1417 config MATH_EMULATION
1419 prompt "Math emulation" if X86_32
1421 Linux can emulate a math coprocessor (used for floating point
1422 operations) if you don't have one. 486DX and Pentium processors have
1423 a math coprocessor built in, 486SX and 386 do not, unless you added
1424 a 487DX or 387, respectively. (The messages during boot time can
1425 give you some hints here ["man dmesg"].) Everyone needs either a
1426 coprocessor or this emulation.
1428 If you don't have a math coprocessor, you need to say Y here; if you
1429 say Y here even though you have a coprocessor, the coprocessor will
1430 be used nevertheless. (This behavior can be changed with the kernel
1431 command line option "no387", which comes handy if your coprocessor
1432 is broken. Try "man bootparam" or see the documentation of your boot
1433 loader (lilo or loadlin) about how to pass options to the kernel at
1434 boot time.) This means that it is a good idea to say Y here if you
1435 intend to use this kernel on different machines.
1437 More information about the internals of the Linux math coprocessor
1438 emulation can be found in <file:arch/x86/math-emu/README>.
1440 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1441 kernel, it won't hurt.
1445 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1447 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1448 the Memory Type Range Registers (MTRRs) may be used to control
1449 processor access to memory ranges. This is most useful if you have
1450 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1451 allows bus write transfers to be combined into a larger transfer
1452 before bursting over the PCI/AGP bus. This can increase performance
1453 of image write operations 2.5 times or more. Saying Y here creates a
1454 /proc/mtrr file which may be used to manipulate your processor's
1455 MTRRs. Typically the X server should use this.
1457 This code has a reasonably generic interface so that similar
1458 control registers on other processors can be easily supported
1461 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1462 Registers (ARRs) which provide a similar functionality to MTRRs. For
1463 these, the ARRs are used to emulate the MTRRs.
1464 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1465 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1466 write-combining. All of these processors are supported by this code
1467 and it makes sense to say Y here if you have one of them.
1469 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1470 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1471 can lead to all sorts of problems, so it's good to say Y here.
1473 You can safely say Y even if your machine doesn't have MTRRs, you'll
1474 just add about 9 KB to your kernel.
1476 See <file:Documentation/x86/mtrr.txt> for more information.
1478 config MTRR_SANITIZER
1480 prompt "MTRR cleanup support"
1483 Convert MTRR layout from continuous to discrete, so X drivers can
1484 add writeback entries.
1486 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1487 The largest mtrr entry size for a continuous block can be set with
1492 config MTRR_SANITIZER_ENABLE_DEFAULT
1493 int "MTRR cleanup enable value (0-1)"
1496 depends on MTRR_SANITIZER
1498 Enable mtrr cleanup default value
1500 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1501 int "MTRR cleanup spare reg num (0-7)"
1504 depends on MTRR_SANITIZER
1506 mtrr cleanup spare entries default, it can be changed via
1507 mtrr_spare_reg_nr=N on the kernel command line.
1511 prompt "x86 PAT support" if EXPERT
1514 Use PAT attributes to setup page level cache control.
1516 PATs are the modern equivalents of MTRRs and are much more
1517 flexible than MTRRs.
1519 Say N here if you see bootup problems (boot crash, boot hang,
1520 spontaneous reboots) or a non-working video driver.
1524 config ARCH_USES_PG_UNCACHED
1530 prompt "x86 architectural random number generator" if EXPERT
1532 Enable the x86 architectural RDRAND instruction
1533 (Intel Bull Mountain technology) to generate random numbers.
1534 If supported, this is a high bandwidth, cryptographically
1535 secure hardware random number generator.
1539 prompt "Supervisor Mode Access Prevention" if EXPERT
1541 Supervisor Mode Access Prevention (SMAP) is a security
1542 feature in newer Intel processors. There is a small
1543 performance cost if this enabled and turned on; there is
1544 also a small increase in the kernel size if this is enabled.
1549 bool "EFI runtime service support"
1552 This enables the kernel to use EFI runtime services that are
1553 available (such as the EFI variable services).
1555 This option is only useful on systems that have EFI firmware.
1556 In addition, you should use the latest ELILO loader available
1557 at <http://elilo.sourceforge.net> in order to take advantage
1558 of EFI runtime services. However, even with this option, the
1559 resultant kernel should continue to boot on existing non-EFI
1563 bool "EFI stub support"
1566 This kernel feature allows a bzImage to be loaded directly
1567 by EFI firmware without the use of a bootloader.
1569 See Documentation/x86/efi-stub.txt for more information.
1573 prompt "Enable seccomp to safely compute untrusted bytecode"
1575 This kernel feature is useful for number crunching applications
1576 that may need to compute untrusted bytecode during their
1577 execution. By using pipes or other transports made available to
1578 the process as file descriptors supporting the read/write
1579 syscalls, it's possible to isolate those applications in
1580 their own address space using seccomp. Once seccomp is
1581 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1582 and the task is only allowed to execute a few safe syscalls
1583 defined by each seccomp mode.
1585 If unsure, say Y. Only embedded should say N here.
1587 config CC_STACKPROTECTOR
1588 bool "Enable -fstack-protector buffer overflow detection"
1590 This option turns on the -fstack-protector GCC feature. This
1591 feature puts, at the beginning of functions, a canary value on
1592 the stack just before the return address, and validates
1593 the value just before actually returning. Stack based buffer
1594 overflows (that need to overwrite this return address) now also
1595 overwrite the canary, which gets detected and the attack is then
1596 neutralized via a kernel panic.
1598 This feature requires gcc version 4.2 or above, or a distribution
1599 gcc with the feature backported. Older versions are automatically
1600 detected and for those versions, this configuration option is
1601 ignored. (and a warning is printed during bootup)
1603 source kernel/Kconfig.hz
1606 bool "kexec system call"
1608 kexec is a system call that implements the ability to shutdown your
1609 current kernel, and to start another kernel. It is like a reboot
1610 but it is independent of the system firmware. And like a reboot
1611 you can start any kernel with it, not just Linux.
1613 The name comes from the similarity to the exec system call.
1615 It is an ongoing process to be certain the hardware in a machine
1616 is properly shutdown, so do not be surprised if this code does not
1617 initially work for you. It may help to enable device hotplugging
1618 support. As of this writing the exact hardware interface is
1619 strongly in flux, so no good recommendation can be made.
1622 bool "kernel crash dumps"
1623 depends on X86_64 || (X86_32 && HIGHMEM)
1625 Generate crash dump after being started by kexec.
1626 This should be normally only set in special crash dump kernels
1627 which are loaded in the main kernel with kexec-tools into
1628 a specially reserved region and then later executed after
1629 a crash by kdump/kexec. The crash dump kernel must be compiled
1630 to a memory address not used by the main kernel or BIOS using
1631 PHYSICAL_START, or it must be built as a relocatable image
1632 (CONFIG_RELOCATABLE=y).
1633 For more details see Documentation/kdump/kdump.txt
1637 depends on KEXEC && HIBERNATION
1639 Jump between original kernel and kexeced kernel and invoke
1640 code in physical address mode via KEXEC
1642 config PHYSICAL_START
1643 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1646 This gives the physical address where the kernel is loaded.
1648 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1649 bzImage will decompress itself to above physical address and
1650 run from there. Otherwise, bzImage will run from the address where
1651 it has been loaded by the boot loader and will ignore above physical
1654 In normal kdump cases one does not have to set/change this option
1655 as now bzImage can be compiled as a completely relocatable image
1656 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1657 address. This option is mainly useful for the folks who don't want
1658 to use a bzImage for capturing the crash dump and want to use a
1659 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1660 to be specifically compiled to run from a specific memory area
1661 (normally a reserved region) and this option comes handy.
1663 So if you are using bzImage for capturing the crash dump,
1664 leave the value here unchanged to 0x1000000 and set
1665 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1666 for capturing the crash dump change this value to start of
1667 the reserved region. In other words, it can be set based on
1668 the "X" value as specified in the "crashkernel=YM@XM"
1669 command line boot parameter passed to the panic-ed
1670 kernel. Please take a look at Documentation/kdump/kdump.txt
1671 for more details about crash dumps.
1673 Usage of bzImage for capturing the crash dump is recommended as
1674 one does not have to build two kernels. Same kernel can be used
1675 as production kernel and capture kernel. Above option should have
1676 gone away after relocatable bzImage support is introduced. But it
1677 is present because there are users out there who continue to use
1678 vmlinux for dump capture. This option should go away down the
1681 Don't change this unless you know what you are doing.
1684 bool "Build a relocatable kernel"
1687 This builds a kernel image that retains relocation information
1688 so it can be loaded someplace besides the default 1MB.
1689 The relocations tend to make the kernel binary about 10% larger,
1690 but are discarded at runtime.
1692 One use is for the kexec on panic case where the recovery kernel
1693 must live at a different physical address than the primary
1696 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1697 it has been loaded at and the compile time physical address
1698 (CONFIG_PHYSICAL_START) is ignored.
1700 # Relocation on x86-32 needs some additional build support
1701 config X86_NEED_RELOCS
1703 depends on X86_32 && RELOCATABLE
1705 config PHYSICAL_ALIGN
1706 hex "Alignment value to which kernel should be aligned" if X86_32
1708 range 0x2000 0x1000000
1710 This value puts the alignment restrictions on physical address
1711 where kernel is loaded and run from. Kernel is compiled for an
1712 address which meets above alignment restriction.
1714 If bootloader loads the kernel at a non-aligned address and
1715 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1716 address aligned to above value and run from there.
1718 If bootloader loads the kernel at a non-aligned address and
1719 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1720 load address and decompress itself to the address it has been
1721 compiled for and run from there. The address for which kernel is
1722 compiled already meets above alignment restrictions. Hence the
1723 end result is that kernel runs from a physical address meeting
1724 above alignment restrictions.
1726 Don't change this unless you know what you are doing.
1729 bool "Support for hot-pluggable CPUs"
1730 depends on SMP && HOTPLUG
1732 Say Y here to allow turning CPUs off and on. CPUs can be
1733 controlled through /sys/devices/system/cpu.
1734 ( Note: power management support will enable this option
1735 automatically on SMP systems. )
1736 Say N if you want to disable CPU hotplug.
1738 config BOOTPARAM_HOTPLUG_CPU0
1739 bool "Set default setting of cpu0_hotpluggable"
1741 depends on HOTPLUG_CPU
1743 Set whether default state of cpu0_hotpluggable is on or off.
1745 Say Y here to enable CPU0 hotplug by default. If this switch
1746 is turned on, there is no need to give cpu0_hotplug kernel
1747 parameter and the CPU0 hotplug feature is enabled by default.
1749 Please note: there are two known CPU0 dependencies if you want
1750 to enable the CPU0 hotplug feature either by this switch or by
1751 cpu0_hotplug kernel parameter.
1753 First, resume from hibernate or suspend always starts from CPU0.
1754 So hibernate and suspend are prevented if CPU0 is offline.
1756 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1757 offline if any interrupt can not migrate out of CPU0. There may
1758 be other CPU0 dependencies.
1760 Please make sure the dependencies are under your control before
1761 you enable this feature.
1763 Say N if you don't want to enable CPU0 hotplug feature by default.
1764 You still can enable the CPU0 hotplug feature at boot by kernel
1765 parameter cpu0_hotplug.
1767 config DEBUG_HOTPLUG_CPU0
1769 prompt "Debug CPU0 hotplug"
1770 depends on HOTPLUG_CPU
1772 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1773 soon as possible and boots up userspace with CPU0 offlined. User
1774 can online CPU0 back after boot time.
1776 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1777 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1778 compilation or giving cpu0_hotplug kernel parameter at boot.
1784 prompt "Compat VDSO support"
1785 depends on X86_32 || IA32_EMULATION
1787 Map the 32-bit VDSO to the predictable old-style address too.
1789 Say N here if you are running a sufficiently recent glibc
1790 version (2.3.3 or later), to remove the high-mapped
1791 VDSO mapping and to exclusively use the randomized VDSO.
1796 bool "Built-in kernel command line"
1798 Allow for specifying boot arguments to the kernel at
1799 build time. On some systems (e.g. embedded ones), it is
1800 necessary or convenient to provide some or all of the
1801 kernel boot arguments with the kernel itself (that is,
1802 to not rely on the boot loader to provide them.)
1804 To compile command line arguments into the kernel,
1805 set this option to 'Y', then fill in the
1806 the boot arguments in CONFIG_CMDLINE.
1808 Systems with fully functional boot loaders (i.e. non-embedded)
1809 should leave this option set to 'N'.
1812 string "Built-in kernel command string"
1813 depends on CMDLINE_BOOL
1816 Enter arguments here that should be compiled into the kernel
1817 image and used at boot time. If the boot loader provides a
1818 command line at boot time, it is appended to this string to
1819 form the full kernel command line, when the system boots.
1821 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1822 change this behavior.
1824 In most cases, the command line (whether built-in or provided
1825 by the boot loader) should specify the device for the root
1828 config CMDLINE_OVERRIDE
1829 bool "Built-in command line overrides boot loader arguments"
1830 depends on CMDLINE_BOOL
1832 Set this option to 'Y' to have the kernel ignore the boot loader
1833 command line, and use ONLY the built-in command line.
1835 This is used to work around broken boot loaders. This should
1836 be set to 'N' under normal conditions.
1840 config ARCH_ENABLE_MEMORY_HOTPLUG
1842 depends on X86_64 || (X86_32 && HIGHMEM)
1844 config ARCH_ENABLE_MEMORY_HOTREMOVE
1846 depends on MEMORY_HOTPLUG
1848 config USE_PERCPU_NUMA_NODE_ID
1852 menu "Power management and ACPI options"
1854 config ARCH_HIBERNATION_HEADER
1856 depends on X86_64 && HIBERNATION
1858 source "kernel/power/Kconfig"
1860 source "drivers/acpi/Kconfig"
1862 source "drivers/sfi/Kconfig"
1869 tristate "APM (Advanced Power Management) BIOS support"
1870 depends on X86_32 && PM_SLEEP
1872 APM is a BIOS specification for saving power using several different
1873 techniques. This is mostly useful for battery powered laptops with
1874 APM compliant BIOSes. If you say Y here, the system time will be
1875 reset after a RESUME operation, the /proc/apm device will provide
1876 battery status information, and user-space programs will receive
1877 notification of APM "events" (e.g. battery status change).
1879 If you select "Y" here, you can disable actual use of the APM
1880 BIOS by passing the "apm=off" option to the kernel at boot time.
1882 Note that the APM support is almost completely disabled for
1883 machines with more than one CPU.
1885 In order to use APM, you will need supporting software. For location
1886 and more information, read <file:Documentation/power/apm-acpi.txt>
1887 and the Battery Powered Linux mini-HOWTO, available from
1888 <http://www.tldp.org/docs.html#howto>.
1890 This driver does not spin down disk drives (see the hdparm(8)
1891 manpage ("man 8 hdparm") for that), and it doesn't turn off
1892 VESA-compliant "green" monitors.
1894 This driver does not support the TI 4000M TravelMate and the ACER
1895 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1896 desktop machines also don't have compliant BIOSes, and this driver
1897 may cause those machines to panic during the boot phase.
1899 Generally, if you don't have a battery in your machine, there isn't
1900 much point in using this driver and you should say N. If you get
1901 random kernel OOPSes or reboots that don't seem to be related to
1902 anything, try disabling/enabling this option (or disabling/enabling
1905 Some other things you should try when experiencing seemingly random,
1908 1) make sure that you have enough swap space and that it is
1910 2) pass the "no-hlt" option to the kernel
1911 3) switch on floating point emulation in the kernel and pass
1912 the "no387" option to the kernel
1913 4) pass the "floppy=nodma" option to the kernel
1914 5) pass the "mem=4M" option to the kernel (thereby disabling
1915 all but the first 4 MB of RAM)
1916 6) make sure that the CPU is not over clocked.
1917 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1918 8) disable the cache from your BIOS settings
1919 9) install a fan for the video card or exchange video RAM
1920 10) install a better fan for the CPU
1921 11) exchange RAM chips
1922 12) exchange the motherboard.
1924 To compile this driver as a module, choose M here: the
1925 module will be called apm.
1929 config APM_IGNORE_USER_SUSPEND
1930 bool "Ignore USER SUSPEND"
1932 This option will ignore USER SUSPEND requests. On machines with a
1933 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1934 series notebooks, it is necessary to say Y because of a BIOS bug.
1936 config APM_DO_ENABLE
1937 bool "Enable PM at boot time"
1939 Enable APM features at boot time. From page 36 of the APM BIOS
1940 specification: "When disabled, the APM BIOS does not automatically
1941 power manage devices, enter the Standby State, enter the Suspend
1942 State, or take power saving steps in response to CPU Idle calls."
1943 This driver will make CPU Idle calls when Linux is idle (unless this
1944 feature is turned off -- see "Do CPU IDLE calls", below). This
1945 should always save battery power, but more complicated APM features
1946 will be dependent on your BIOS implementation. You may need to turn
1947 this option off if your computer hangs at boot time when using APM
1948 support, or if it beeps continuously instead of suspending. Turn
1949 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1950 T400CDT. This is off by default since most machines do fine without
1955 bool "Make CPU Idle calls when idle"
1957 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1958 On some machines, this can activate improved power savings, such as
1959 a slowed CPU clock rate, when the machine is idle. These idle calls
1960 are made after the idle loop has run for some length of time (e.g.,
1961 333 mS). On some machines, this will cause a hang at boot time or
1962 whenever the CPU becomes idle. (On machines with more than one CPU,
1963 this option does nothing.)
1965 config APM_DISPLAY_BLANK
1966 bool "Enable console blanking using APM"
1968 Enable console blanking using the APM. Some laptops can use this to
1969 turn off the LCD backlight when the screen blanker of the Linux
1970 virtual console blanks the screen. Note that this is only used by
1971 the virtual console screen blanker, and won't turn off the backlight
1972 when using the X Window system. This also doesn't have anything to
1973 do with your VESA-compliant power-saving monitor. Further, this
1974 option doesn't work for all laptops -- it might not turn off your
1975 backlight at all, or it might print a lot of errors to the console,
1976 especially if you are using gpm.
1978 config APM_ALLOW_INTS
1979 bool "Allow interrupts during APM BIOS calls"
1981 Normally we disable external interrupts while we are making calls to
1982 the APM BIOS as a measure to lessen the effects of a badly behaving
1983 BIOS implementation. The BIOS should reenable interrupts if it
1984 needs to. Unfortunately, some BIOSes do not -- especially those in
1985 many of the newer IBM Thinkpads. If you experience hangs when you
1986 suspend, try setting this to Y. Otherwise, say N.
1990 source "drivers/cpufreq/Kconfig"
1992 source "drivers/cpuidle/Kconfig"
1994 source "drivers/idle/Kconfig"
1999 menu "Bus options (PCI etc.)"
2004 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2006 Find out whether you have a PCI motherboard. PCI is the name of a
2007 bus system, i.e. the way the CPU talks to the other stuff inside
2008 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2009 VESA. If you have PCI, say Y, otherwise N.
2012 prompt "PCI access mode"
2013 depends on X86_32 && PCI
2016 On PCI systems, the BIOS can be used to detect the PCI devices and
2017 determine their configuration. However, some old PCI motherboards
2018 have BIOS bugs and may crash if this is done. Also, some embedded
2019 PCI-based systems don't have any BIOS at all. Linux can also try to
2020 detect the PCI hardware directly without using the BIOS.
2022 With this option, you can specify how Linux should detect the
2023 PCI devices. If you choose "BIOS", the BIOS will be used,
2024 if you choose "Direct", the BIOS won't be used, and if you
2025 choose "MMConfig", then PCI Express MMCONFIG will be used.
2026 If you choose "Any", the kernel will try MMCONFIG, then the
2027 direct access method and falls back to the BIOS if that doesn't
2028 work. If unsure, go with the default, which is "Any".
2033 config PCI_GOMMCONFIG
2050 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2052 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2055 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2059 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2063 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2067 depends on PCI && XEN
2075 bool "Support mmconfig PCI config space access"
2076 depends on X86_64 && PCI && ACPI
2078 config PCI_CNB20LE_QUIRK
2079 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2082 Read the PCI windows out of the CNB20LE host bridge. This allows
2083 PCI hotplug to work on systems with the CNB20LE chipset which do
2086 There's no public spec for this chipset, and this functionality
2087 is known to be incomplete.
2089 You should say N unless you know you need this.
2091 source "drivers/pci/pcie/Kconfig"
2093 source "drivers/pci/Kconfig"
2095 # x86_64 have no ISA slots, but can have ISA-style DMA.
2097 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2100 Enables ISA-style DMA support for devices requiring such controllers.
2108 Find out whether you have ISA slots on your motherboard. ISA is the
2109 name of a bus system, i.e. the way the CPU talks to the other stuff
2110 inside your box. Other bus systems are PCI, EISA, MicroChannel
2111 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2112 newer boards don't support it. If you have ISA, say Y, otherwise N.
2118 The Extended Industry Standard Architecture (EISA) bus was
2119 developed as an open alternative to the IBM MicroChannel bus.
2121 The EISA bus provided some of the features of the IBM MicroChannel
2122 bus while maintaining backward compatibility with cards made for
2123 the older ISA bus. The EISA bus saw limited use between 1988 and
2124 1995 when it was made obsolete by the PCI bus.
2126 Say Y here if you are building a kernel for an EISA-based machine.
2130 source "drivers/eisa/Kconfig"
2133 tristate "NatSemi SCx200 support"
2135 This provides basic support for National Semiconductor's
2136 (now AMD's) Geode processors. The driver probes for the
2137 PCI-IDs of several on-chip devices, so its a good dependency
2138 for other scx200_* drivers.
2140 If compiled as a module, the driver is named scx200.
2142 config SCx200HR_TIMER
2143 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2147 This driver provides a clocksource built upon the on-chip
2148 27MHz high-resolution timer. Its also a workaround for
2149 NSC Geode SC-1100's buggy TSC, which loses time when the
2150 processor goes idle (as is done by the scheduler). The
2151 other workaround is idle=poll boot option.
2154 bool "One Laptop Per Child support"
2161 Add support for detecting the unique features of the OLPC
2165 bool "OLPC XO-1 Power Management"
2166 depends on OLPC && MFD_CS5535 && PM_SLEEP
2169 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2172 bool "OLPC XO-1 Real Time Clock"
2173 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2175 Add support for the XO-1 real time clock, which can be used as a
2176 programmable wakeup source.
2179 bool "OLPC XO-1 SCI extras"
2180 depends on OLPC && OLPC_XO1_PM
2186 Add support for SCI-based features of the OLPC XO-1 laptop:
2187 - EC-driven system wakeups
2191 - AC adapter status updates
2192 - Battery status updates
2194 config OLPC_XO15_SCI
2195 bool "OLPC XO-1.5 SCI extras"
2196 depends on OLPC && ACPI
2199 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2200 - EC-driven system wakeups
2201 - AC adapter status updates
2202 - Battery status updates
2205 bool "PCEngines ALIX System Support (LED setup)"
2208 This option enables system support for the PCEngines ALIX.
2209 At present this just sets up LEDs for GPIO control on
2210 ALIX2/3/6 boards. However, other system specific setup should
2213 Note: You must still enable the drivers for GPIO and LED support
2214 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2216 Note: You have to set alix.force=1 for boards with Award BIOS.
2219 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2222 This option enables system support for the Soekris Engineering net5501.
2225 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2229 This option enables system support for the Traverse Technologies GEOS.
2232 bool "Technologic Systems TS-5500 platform support"
2234 select CHECK_SIGNATURE
2238 This option enables system support for the Technologic Systems TS-5500.
2244 depends on CPU_SUP_AMD && PCI
2246 source "drivers/pcmcia/Kconfig"
2248 source "drivers/pci/hotplug/Kconfig"
2251 bool "RapidIO support"
2255 If you say Y here, the kernel will include drivers and
2256 infrastructure code to support RapidIO interconnect devices.
2258 source "drivers/rapidio/Kconfig"
2263 menu "Executable file formats / Emulations"
2265 source "fs/Kconfig.binfmt"
2267 config IA32_EMULATION
2268 bool "IA32 Emulation"
2270 select COMPAT_BINFMT_ELF
2273 Include code to run legacy 32-bit programs under a
2274 64-bit kernel. You should likely turn this on, unless you're
2275 100% sure that you don't have any 32-bit programs left.
2278 tristate "IA32 a.out support"
2279 depends on IA32_EMULATION
2281 Support old a.out binaries in the 32bit emulation.
2284 bool "x32 ABI for 64-bit mode"
2285 depends on X86_64 && IA32_EMULATION
2287 Include code to run binaries for the x32 native 32-bit ABI
2288 for 64-bit processors. An x32 process gets access to the
2289 full 64-bit register file and wide data path while leaving
2290 pointers at 32 bits for smaller memory footprint.
2292 You will need a recent binutils (2.22 or later) with
2293 elf32_x86_64 support enabled to compile a kernel with this
2298 depends on IA32_EMULATION || X86_X32
2299 select ARCH_WANT_OLD_COMPAT_IPC
2302 config COMPAT_FOR_U64_ALIGNMENT
2305 config SYSVIPC_COMPAT
2317 config HAVE_ATOMIC_IOMAP
2321 config HAVE_TEXT_POKE_SMP
2323 select STOP_MACHINE if SMP
2325 config X86_DEV_DMA_OPS
2327 depends on X86_64 || STA2X11
2329 config X86_DMA_REMAP
2333 source "net/Kconfig"
2335 source "drivers/Kconfig"
2337 source "drivers/firmware/Kconfig"
2341 source "arch/x86/Kconfig.debug"
2343 source "security/Kconfig"
2345 source "crypto/Kconfig"
2347 source "arch/x86/kvm/Kconfig"
2349 source "lib/Kconfig"