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 HAVE_ARCH_SOFT_DIRTY
106 select CLOCKSOURCE_WATCHDOG
107 select GENERIC_CLOCKEVENTS
108 select ARCH_CLOCKSOURCE_DATA if X86_64
109 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
110 select GENERIC_TIME_VSYSCALL if X86_64
111 select KTIME_SCALAR if X86_32
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
125 select HAVE_DEBUG_STACKOVERFLOW
127 config INSTRUCTION_DECODER
129 depends on KPROBES || PERF_EVENTS || UPROBES
133 default "elf32-i386" if X86_32
134 default "elf64-x86-64" if X86_64
136 config ARCH_DEFCONFIG
138 default "arch/x86/configs/i386_defconfig" if X86_32
139 default "arch/x86/configs/x86_64_defconfig" if X86_64
141 config LOCKDEP_SUPPORT
144 config STACKTRACE_SUPPORT
147 config HAVE_LATENCYTOP_SUPPORT
156 config NEED_DMA_MAP_STATE
158 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
160 config NEED_SG_DMA_LENGTH
163 config GENERIC_ISA_DMA
165 depends on ISA_DMA_API
170 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
172 config GENERIC_BUG_RELATIVE_POINTERS
175 config GENERIC_HWEIGHT
178 config ARCH_MAY_HAVE_PC_FDC
180 depends on ISA_DMA_API
182 config RWSEM_XCHGADD_ALGORITHM
185 config GENERIC_CALIBRATE_DELAY
188 config ARCH_HAS_CPU_RELAX
191 config ARCH_HAS_CACHE_LINE_SIZE
194 config ARCH_HAS_CPU_AUTOPROBE
197 config HAVE_SETUP_PER_CPU_AREA
200 config NEED_PER_CPU_EMBED_FIRST_CHUNK
203 config NEED_PER_CPU_PAGE_FIRST_CHUNK
206 config ARCH_HIBERNATION_POSSIBLE
209 config ARCH_SUSPEND_POSSIBLE
212 config ARCH_WANT_HUGE_PMD_SHARE
215 config ARCH_WANT_GENERAL_HUGETLB
226 config ARCH_SUPPORTS_OPTIMIZED_INLINING
229 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
232 config HAVE_INTEL_TXT
234 depends on INTEL_IOMMU && ACPI
238 depends on X86_32 && SMP
242 depends on X86_64 && SMP
248 config X86_32_LAZY_GS
250 depends on X86_32 && !CC_STACKPROTECTOR
252 config ARCH_HWEIGHT_CFLAGS
254 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
255 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
257 config ARCH_CPU_PROBE_RELEASE
259 depends on HOTPLUG_CPU
261 config ARCH_SUPPORTS_UPROBES
264 source "init/Kconfig"
265 source "kernel/Kconfig.freezer"
267 menu "Processor type and features"
270 bool "DMA memory allocation support" if EXPERT
273 DMA memory allocation support allows devices with less than 32-bit
274 addressing to allocate within the first 16MB of address space.
275 Disable if no such devices will be used.
280 bool "Symmetric multi-processing support"
282 This enables support for systems with more than one CPU. If you have
283 a system with only one CPU, like most personal computers, say N. If
284 you have a system with more than one CPU, say Y.
286 If you say N here, the kernel will run on single and multiprocessor
287 machines, but will use only one CPU of a multiprocessor machine. If
288 you say Y here, the kernel will run on many, but not all,
289 singleprocessor machines. On a singleprocessor machine, the kernel
290 will run faster if you say N here.
292 Note that if you say Y here and choose architecture "586" or
293 "Pentium" under "Processor family", the kernel will not work on 486
294 architectures. Similarly, multiprocessor kernels for the "PPro"
295 architecture may not work on all Pentium based boards.
297 People using multiprocessor machines who say Y here should also say
298 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
299 Management" code will be disabled if you say Y here.
301 See also <file:Documentation/x86/i386/IO-APIC.txt>,
302 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
303 <http://www.tldp.org/docs.html#howto>.
305 If you don't know what to do here, say N.
308 bool "Support x2apic"
309 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
311 This enables x2apic support on CPUs that have this feature.
313 This allows 32-bit apic IDs (so it can support very large systems),
314 and accesses the local apic via MSRs not via mmio.
316 If you don't know what to do here, say N.
319 bool "Enable MPS table" if ACPI || SFI
321 depends on X86_LOCAL_APIC
323 For old smp systems that do not have proper acpi support. Newer systems
324 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
327 bool "Support for big SMP systems with more than 8 CPUs"
328 depends on X86_32 && SMP
330 This option is needed for the systems that have more than 8 CPUs
334 depends on X86_GOLDFISH
337 config X86_EXTENDED_PLATFORM
338 bool "Support for extended (non-PC) x86 platforms"
341 If you disable this option then the kernel will only support
342 standard PC platforms. (which covers the vast majority of
345 If you enable this option then you'll be able to select support
346 for the following (non-PC) 32 bit x86 platforms:
347 Goldfish (Android emulator)
351 SGI 320/540 (Visual Workstation)
352 STA2X11-based (e.g. Northville)
353 Summit/EXA (IBM x440)
354 Unisys ES7000 IA32 series
355 Moorestown MID devices
357 If you have one of these systems, or if you want to build a
358 generic distribution kernel, say Y here - otherwise say N.
362 config X86_EXTENDED_PLATFORM
363 bool "Support for extended (non-PC) x86 platforms"
366 If you disable this option then the kernel will only support
367 standard PC platforms. (which covers the vast majority of
370 If you enable this option then you'll be able to select support
371 for the following (non-PC) 64 bit x86 platforms:
376 If you have one of these systems, or if you want to build a
377 generic distribution kernel, say Y here - otherwise say N.
379 # This is an alphabetically sorted list of 64 bit extended platforms
380 # Please maintain the alphabetic order if and when there are additions
382 bool "Numascale NumaChip"
384 depends on X86_EXTENDED_PLATFORM
387 depends on X86_X2APIC
388 depends on PCI_MMCONFIG
390 Adds support for Numascale NumaChip large-SMP systems. Needed to
391 enable more than ~168 cores.
392 If you don't have one of these, you should say N here.
396 select HYPERVISOR_GUEST
398 depends on X86_64 && PCI
399 depends on X86_EXTENDED_PLATFORM
402 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
403 supposed to run on these EM64T-based machines. Only choose this option
404 if you have one of these machines.
407 bool "SGI Ultraviolet"
409 depends on X86_EXTENDED_PLATFORM
411 depends on X86_X2APIC
413 This option is needed in order to support SGI Ultraviolet systems.
414 If you don't have one of these, you should say N here.
416 # Following is an alphabetically sorted list of 32 bit extended platforms
417 # Please maintain the alphabetic order if and when there are additions
420 bool "Goldfish (Virtual Platform)"
422 depends on X86_EXTENDED_PLATFORM
424 Enable support for the Goldfish virtual platform used primarily
425 for Android development. Unless you are building for the Android
426 Goldfish emulator say N here.
429 bool "CE4100 TV platform"
431 depends on PCI_GODIRECT
433 depends on X86_EXTENDED_PLATFORM
434 select X86_REBOOTFIXUPS
436 select OF_EARLY_FLATTREE
439 Select for the Intel CE media processor (CE4100) SOC.
440 This option compiles in support for the CE4100 SOC for settop
441 boxes and media devices.
443 config X86_WANT_INTEL_MID
444 bool "Intel MID platform support"
446 depends on X86_EXTENDED_PLATFORM
448 Select to build a kernel capable of supporting Intel MID platform
449 systems which do not have the PCI legacy interfaces (Moorestown,
450 Medfield). If you are building for a PC class system say N here.
452 if X86_WANT_INTEL_MID
458 bool "Medfield MID platform"
461 depends on X86_IO_APIC
469 select X86_PLATFORM_DEVICES
470 select MFD_INTEL_MSIC
472 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
473 Internet Device(MID) platform.
474 Unlike standard x86 PCs, Medfield does not have many legacy devices
475 nor standard legacy replacement devices/features. e.g. Medfield does
476 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
480 config X86_INTEL_LPSS
481 bool "Intel Low Power Subsystem Support"
485 Select to build support for Intel Low Power Subsystem such as
486 found on Intel Lynxpoint PCH. Selecting this option enables
487 things like clock tree (common clock framework) which are needed
488 by the LPSS peripheral drivers.
491 bool "RDC R-321x SoC"
493 depends on X86_EXTENDED_PLATFORM
495 select X86_REBOOTFIXUPS
497 This option is needed for RDC R-321x system-on-chip, also known
499 If you don't have one of these chips, you should say N here.
501 config X86_32_NON_STANDARD
502 bool "Support non-standard 32-bit SMP architectures"
503 depends on X86_32 && SMP
504 depends on X86_EXTENDED_PLATFORM
506 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
507 STA2X11, default subarchitectures. It is intended for a generic
508 binary kernel. If you select them all, kernel will probe it
509 one by one and will fallback to default.
511 # Alphabetically sorted list of Non standard 32 bit platforms
514 bool "NUMAQ (IBM/Sequent)"
515 depends on X86_32_NON_STANDARD
520 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
521 NUMA multiquad box. This changes the way that processors are
522 bootstrapped, and uses Clustered Logical APIC addressing mode instead
523 of Flat Logical. You will need a new lynxer.elf file to flash your
524 firmware with - send email to <Martin.Bligh@us.ibm.com>.
526 config X86_SUPPORTS_MEMORY_FAILURE
528 # MCE code calls memory_failure():
530 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
531 depends on !X86_NUMAQ
532 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
533 depends on X86_64 || !SPARSEMEM
534 select ARCH_SUPPORTS_MEMORY_FAILURE
537 bool "SGI 320/540 (Visual Workstation)"
538 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
539 depends on X86_32_NON_STANDARD
541 The SGI Visual Workstation series is an IA32-based workstation
542 based on SGI systems chips with some legacy PC hardware attached.
544 Say Y here to create a kernel to run on the SGI 320 or 540.
546 A kernel compiled for the Visual Workstation will run on general
547 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
550 bool "STA2X11 Companion Chip Support"
551 depends on X86_32_NON_STANDARD && PCI
552 select X86_DEV_DMA_OPS
556 select ARCH_REQUIRE_GPIOLIB
559 This adds support for boards based on the STA2X11 IO-Hub,
560 a.k.a. "ConneXt". The chip is used in place of the standard
561 PC chipset, so all "standard" peripherals are missing. If this
562 option is selected the kernel will still be able to boot on
563 standard PC machines.
566 bool "Summit/EXA (IBM x440)"
567 depends on X86_32_NON_STANDARD
569 This option is needed for IBM systems that use the Summit/EXA chipset.
570 In particular, it is needed for the x440.
573 bool "Unisys ES7000 IA32 series"
574 depends on X86_32_NON_STANDARD && X86_BIGSMP
576 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
577 supposed to run on an IA32-based Unisys ES7000 system.
580 tristate "Eurobraille/Iris poweroff module"
583 The Iris machines from EuroBraille do not have APM or ACPI support
584 to shut themselves down properly. A special I/O sequence is
585 needed to do so, which is what this module does at
588 This is only for Iris machines from EuroBraille.
592 config SCHED_OMIT_FRAME_POINTER
594 prompt "Single-depth WCHAN output"
597 Calculate simpler /proc/<PID>/wchan values. If this option
598 is disabled then wchan values will recurse back to the
599 caller function. This provides more accurate wchan values,
600 at the expense of slightly more scheduling overhead.
602 If in doubt, say "Y".
604 menuconfig HYPERVISOR_GUEST
605 bool "Linux guest support"
607 Say Y here to enable options for running Linux under various hyper-
608 visors. This option enables basic hypervisor detection and platform
611 If you say N, all options in this submenu will be skipped and
612 disabled, and Linux guest support won't be built in.
617 bool "Enable paravirtualization code"
619 This changes the kernel so it can modify itself when it is run
620 under a hypervisor, potentially improving performance significantly
621 over full virtualization. However, when run without a hypervisor
622 the kernel is theoretically slower and slightly larger.
624 config PARAVIRT_DEBUG
625 bool "paravirt-ops debugging"
626 depends on PARAVIRT && DEBUG_KERNEL
628 Enable to debug paravirt_ops internals. Specifically, BUG if
629 a paravirt_op is missing when it is called.
631 config PARAVIRT_SPINLOCKS
632 bool "Paravirtualization layer for spinlocks"
633 depends on PARAVIRT && SMP
635 Paravirtualized spinlocks allow a pvops backend to replace the
636 spinlock implementation with something virtualization-friendly
637 (for example, block the virtual CPU rather than spinning).
639 Unfortunately the downside is an up to 5% performance hit on
640 native kernels, with various workloads.
642 If you are unsure how to answer this question, answer N.
644 source "arch/x86/xen/Kconfig"
647 bool "KVM Guest support (including kvmclock)"
649 select PARAVIRT_CLOCK
652 This option enables various optimizations for running under the KVM
653 hypervisor. It includes a paravirtualized clock, so that instead
654 of relying on a PIT (or probably other) emulation by the
655 underlying device model, the host provides the guest with
656 timing infrastructure such as time of day, and system time
658 source "arch/x86/lguest/Kconfig"
660 config PARAVIRT_TIME_ACCOUNTING
661 bool "Paravirtual steal time accounting"
665 Select this option to enable fine granularity task steal time
666 accounting. Time spent executing other tasks in parallel with
667 the current vCPU is discounted from the vCPU power. To account for
668 that, there can be a small performance impact.
670 If in doubt, say N here.
672 config PARAVIRT_CLOCK
675 endif #HYPERVISOR_GUEST
683 This option adds a kernel parameter 'memtest', which allows memtest
685 memtest=0, mean disabled; -- default
686 memtest=1, mean do 1 test pattern;
688 memtest=4, mean do 4 test patterns.
689 If you are unsure how to answer this question, answer N.
691 config X86_SUMMIT_NUMA
693 depends on X86_32 && NUMA && X86_32_NON_STANDARD
695 config X86_CYCLONE_TIMER
697 depends on X86_SUMMIT
699 source "arch/x86/Kconfig.cpu"
703 prompt "HPET Timer Support" if X86_32
705 Use the IA-PC HPET (High Precision Event Timer) to manage
706 time in preference to the PIT and RTC, if a HPET is
708 HPET is the next generation timer replacing legacy 8254s.
709 The HPET provides a stable time base on SMP
710 systems, unlike the TSC, but it is more expensive to access,
711 as it is off-chip. You can find the HPET spec at
712 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
714 You can safely choose Y here. However, HPET will only be
715 activated if the platform and the BIOS support this feature.
716 Otherwise the 8254 will be used for timing services.
718 Choose N to continue using the legacy 8254 timer.
720 config HPET_EMULATE_RTC
722 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
725 def_bool y if X86_INTEL_MID
726 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
728 depends on X86_INTEL_MID && SFI
730 APB timer is the replacement for 8254, HPET on X86 MID platforms.
731 The APBT provides a stable time base on SMP
732 systems, unlike the TSC, but it is more expensive to access,
733 as it is off-chip. APB timers are always running regardless of CPU
734 C states, they are used as per CPU clockevent device when possible.
736 # Mark as expert because too many people got it wrong.
737 # The code disables itself when not needed.
740 bool "Enable DMI scanning" if EXPERT
742 Enabled scanning of DMI to identify machine quirks. Say Y
743 here unless you have verified that your setup is not
744 affected by entries in the DMI blacklist. Required by PNP
748 bool "GART IOMMU support" if EXPERT
751 depends on X86_64 && PCI && AMD_NB
753 Support for full DMA access of devices with 32bit memory access only
754 on systems with more than 3GB. This is usually needed for USB,
755 sound, many IDE/SATA chipsets and some other devices.
756 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
757 based hardware IOMMU and a software bounce buffer based IOMMU used
758 on Intel systems and as fallback.
759 The code is only active when needed (enough memory and limited
760 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
764 bool "IBM Calgary IOMMU support"
766 depends on X86_64 && PCI
768 Support for hardware IOMMUs in IBM's xSeries x366 and x460
769 systems. Needed to run systems with more than 3GB of memory
770 properly with 32-bit PCI devices that do not support DAC
771 (Double Address Cycle). Calgary also supports bus level
772 isolation, where all DMAs pass through the IOMMU. This
773 prevents them from going anywhere except their intended
774 destination. This catches hard-to-find kernel bugs and
775 mis-behaving drivers and devices that do not use the DMA-API
776 properly to set up their DMA buffers. The IOMMU can be
777 turned off at boot time with the iommu=off parameter.
778 Normally the kernel will make the right choice by itself.
781 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
783 prompt "Should Calgary be enabled by default?"
784 depends on CALGARY_IOMMU
786 Should Calgary be enabled by default? if you choose 'y', Calgary
787 will be used (if it exists). If you choose 'n', Calgary will not be
788 used even if it exists. If you choose 'n' and would like to use
789 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
792 # need this always selected by IOMMU for the VIA workaround
796 Support for software bounce buffers used on x86-64 systems
797 which don't have a hardware IOMMU. Using this PCI devices
798 which can only access 32-bits of memory can be used on systems
799 with more than 3 GB of memory.
804 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
807 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
808 depends on X86_64 && SMP && DEBUG_KERNEL
809 select CPUMASK_OFFSTACK
811 Enable maximum number of CPUS and NUMA Nodes for this architecture.
815 int "Maximum number of CPUs" if SMP && !MAXSMP
816 range 2 8 if SMP && X86_32 && !X86_BIGSMP
817 range 2 512 if SMP && !MAXSMP
819 default "4096" if MAXSMP
820 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
823 This allows you to specify the maximum number of CPUs which this
824 kernel will support. The maximum supported value is 512 and the
825 minimum value which makes sense is 2.
827 This is purely to save memory - each supported CPU adds
828 approximately eight kilobytes to the kernel image.
831 bool "SMT (Hyperthreading) scheduler support"
834 SMT scheduler support improves the CPU scheduler's decision making
835 when dealing with Intel Pentium 4 chips with HyperThreading at a
836 cost of slightly increased overhead in some places. If unsure say
841 prompt "Multi-core scheduler support"
844 Multi-core scheduler support improves the CPU scheduler's decision
845 making when dealing with multi-core CPU chips at a cost of slightly
846 increased overhead in some places. If unsure say N here.
848 source "kernel/Kconfig.preempt"
851 bool "Local APIC support on uniprocessors"
852 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
854 A local APIC (Advanced Programmable Interrupt Controller) is an
855 integrated interrupt controller in the CPU. If you have a single-CPU
856 system which has a processor with a local APIC, you can say Y here to
857 enable and use it. If you say Y here even though your machine doesn't
858 have a local APIC, then the kernel will still run with no slowdown at
859 all. The local APIC supports CPU-generated self-interrupts (timer,
860 performance counters), and the NMI watchdog which detects hard
864 bool "IO-APIC support on uniprocessors"
865 depends on X86_UP_APIC
867 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
868 SMP-capable replacement for PC-style interrupt controllers. Most
869 SMP systems and many recent uniprocessor systems have one.
871 If you have a single-CPU system with an IO-APIC, you can say Y here
872 to use it. If you say Y here even though your machine doesn't have
873 an IO-APIC, then the kernel will still run with no slowdown at all.
875 config X86_LOCAL_APIC
877 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
881 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
883 config X86_VISWS_APIC
885 depends on X86_32 && X86_VISWS
887 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
888 bool "Reroute for broken boot IRQs"
889 depends on X86_IO_APIC
891 This option enables a workaround that fixes a source of
892 spurious interrupts. This is recommended when threaded
893 interrupt handling is used on systems where the generation of
894 superfluous "boot interrupts" cannot be disabled.
896 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
897 entry in the chipset's IO-APIC is masked (as, e.g. the RT
898 kernel does during interrupt handling). On chipsets where this
899 boot IRQ generation cannot be disabled, this workaround keeps
900 the original IRQ line masked so that only the equivalent "boot
901 IRQ" is delivered to the CPUs. The workaround also tells the
902 kernel to set up the IRQ handler on the boot IRQ line. In this
903 way only one interrupt is delivered to the kernel. Otherwise
904 the spurious second interrupt may cause the kernel to bring
905 down (vital) interrupt lines.
907 Only affects "broken" chipsets. Interrupt sharing may be
908 increased on these systems.
911 bool "Machine Check / overheating reporting"
914 Machine Check support allows the processor to notify the
915 kernel if it detects a problem (e.g. overheating, data corruption).
916 The action the kernel takes depends on the severity of the problem,
917 ranging from warning messages to halting the machine.
921 prompt "Intel MCE features"
922 depends on X86_MCE && X86_LOCAL_APIC
924 Additional support for intel specific MCE features such as
929 prompt "AMD MCE features"
930 depends on X86_MCE && X86_LOCAL_APIC
932 Additional support for AMD specific MCE features such as
933 the DRAM Error Threshold.
935 config X86_ANCIENT_MCE
936 bool "Support for old Pentium 5 / WinChip machine checks"
937 depends on X86_32 && X86_MCE
939 Include support for machine check handling on old Pentium 5 or WinChip
940 systems. These typically need to be enabled explicitely on the command
943 config X86_MCE_THRESHOLD
944 depends on X86_MCE_AMD || X86_MCE_INTEL
947 config X86_MCE_INJECT
949 tristate "Machine check injector support"
951 Provide support for injecting machine checks for testing purposes.
952 If you don't know what a machine check is and you don't do kernel
953 QA it is safe to say n.
955 config X86_THERMAL_VECTOR
957 depends on X86_MCE_INTEL
960 bool "Enable VM86 support" if EXPERT
964 This option is required by programs like DOSEMU to run 16-bit legacy
965 code on X86 processors. It also may be needed by software like
966 XFree86 to initialize some video cards via BIOS. Disabling this
967 option saves about 6k.
970 tristate "Toshiba Laptop support"
973 This adds a driver to safely access the System Management Mode of
974 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
975 not work on models with a Phoenix BIOS. The System Management Mode
976 is used to set the BIOS and power saving options on Toshiba portables.
978 For information on utilities to make use of this driver see the
979 Toshiba Linux utilities web site at:
980 <http://www.buzzard.org.uk/toshiba/>.
982 Say Y if you intend to run this kernel on a Toshiba portable.
986 tristate "Dell laptop support"
989 This adds a driver to safely access the System Management Mode
990 of the CPU on the Dell Inspiron 8000. The System Management Mode
991 is used to read cpu temperature and cooling fan status and to
992 control the fans on the I8K portables.
994 This driver has been tested only on the Inspiron 8000 but it may
995 also work with other Dell laptops. You can force loading on other
996 models by passing the parameter `force=1' to the module. Use at
999 For information on utilities to make use of this driver see the
1000 I8K Linux utilities web site at:
1001 <http://people.debian.org/~dz/i8k/>
1003 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
1006 config X86_REBOOTFIXUPS
1007 bool "Enable X86 board specific fixups for reboot"
1010 This enables chipset and/or board specific fixups to be done
1011 in order to get reboot to work correctly. This is only needed on
1012 some combinations of hardware and BIOS. The symptom, for which
1013 this config is intended, is when reboot ends with a stalled/hung
1016 Currently, the only fixup is for the Geode machines using
1017 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1019 Say Y if you want to enable the fixup. Currently, it's safe to
1020 enable this option even if you don't need it.
1024 tristate "CPU microcode loading support"
1028 If you say Y here, you will be able to update the microcode on
1029 certain Intel and AMD processors. The Intel support is for the
1030 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1031 Xeon etc. The AMD support is for families 0x10 and later. You will
1032 obviously need the actual microcode binary data itself which is not
1033 shipped with the Linux kernel.
1035 This option selects the general module only, you need to select
1036 at least one vendor specific module as well.
1038 To compile this driver as a module, choose M here: the module
1039 will be called microcode.
1041 config MICROCODE_INTEL
1042 bool "Intel microcode loading support"
1043 depends on MICROCODE
1047 This options enables microcode patch loading support for Intel
1050 For latest news and information on obtaining all the required
1051 Intel ingredients for this driver, check:
1052 <http://www.urbanmyth.org/microcode/>.
1054 config MICROCODE_AMD
1055 bool "AMD microcode loading support"
1056 depends on MICROCODE
1059 If you select this option, microcode patch loading support for AMD
1060 processors will be enabled.
1062 config MICROCODE_OLD_INTERFACE
1064 depends on MICROCODE
1066 config MICROCODE_INTEL_LIB
1068 depends on MICROCODE_INTEL
1070 config MICROCODE_INTEL_EARLY
1073 config MICROCODE_AMD_EARLY
1076 config MICROCODE_EARLY
1077 bool "Early load microcode"
1078 depends on MICROCODE=y && BLK_DEV_INITRD
1079 select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1080 select MICROCODE_AMD_EARLY if MICROCODE_AMD
1083 This option provides functionality to read additional microcode data
1084 at the beginning of initrd image. The data tells kernel to load
1085 microcode to CPU's as early as possible. No functional change if no
1086 microcode data is glued to the initrd, therefore it's safe to say Y.
1089 tristate "/dev/cpu/*/msr - Model-specific register support"
1091 This device gives privileged processes access to the x86
1092 Model-Specific Registers (MSRs). It is a character device with
1093 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1094 MSR accesses are directed to a specific CPU on multi-processor
1098 tristate "/dev/cpu/*/cpuid - CPU information support"
1100 This device gives processes access to the x86 CPUID instruction to
1101 be executed on a specific processor. It is a character device
1102 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1106 prompt "High Memory Support"
1107 default HIGHMEM64G if X86_NUMAQ
1113 depends on !X86_NUMAQ
1115 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1116 However, the address space of 32-bit x86 processors is only 4
1117 Gigabytes large. That means that, if you have a large amount of
1118 physical memory, not all of it can be "permanently mapped" by the
1119 kernel. The physical memory that's not permanently mapped is called
1122 If you are compiling a kernel which will never run on a machine with
1123 more than 1 Gigabyte total physical RAM, answer "off" here (default
1124 choice and suitable for most users). This will result in a "3GB/1GB"
1125 split: 3GB are mapped so that each process sees a 3GB virtual memory
1126 space and the remaining part of the 4GB virtual memory space is used
1127 by the kernel to permanently map as much physical memory as
1130 If the machine has between 1 and 4 Gigabytes physical RAM, then
1133 If more than 4 Gigabytes is used then answer "64GB" here. This
1134 selection turns Intel PAE (Physical Address Extension) mode on.
1135 PAE implements 3-level paging on IA32 processors. PAE is fully
1136 supported by Linux, PAE mode is implemented on all recent Intel
1137 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1138 then the kernel will not boot on CPUs that don't support PAE!
1140 The actual amount of total physical memory will either be
1141 auto detected or can be forced by using a kernel command line option
1142 such as "mem=256M". (Try "man bootparam" or see the documentation of
1143 your boot loader (lilo or loadlin) about how to pass options to the
1144 kernel at boot time.)
1146 If unsure, say "off".
1150 depends on !X86_NUMAQ
1152 Select this if you have a 32-bit processor and between 1 and 4
1153 gigabytes of physical RAM.
1160 Select this if you have a 32-bit processor and more than 4
1161 gigabytes of physical RAM.
1166 prompt "Memory split" if EXPERT
1170 Select the desired split between kernel and user memory.
1172 If the address range available to the kernel is less than the
1173 physical memory installed, the remaining memory will be available
1174 as "high memory". Accessing high memory is a little more costly
1175 than low memory, as it needs to be mapped into the kernel first.
1176 Note that increasing the kernel address space limits the range
1177 available to user programs, making the address space there
1178 tighter. Selecting anything other than the default 3G/1G split
1179 will also likely make your kernel incompatible with binary-only
1182 If you are not absolutely sure what you are doing, leave this
1186 bool "3G/1G user/kernel split"
1187 config VMSPLIT_3G_OPT
1189 bool "3G/1G user/kernel split (for full 1G low memory)"
1191 bool "2G/2G user/kernel split"
1192 config VMSPLIT_2G_OPT
1194 bool "2G/2G user/kernel split (for full 2G low memory)"
1196 bool "1G/3G user/kernel split"
1201 default 0xB0000000 if VMSPLIT_3G_OPT
1202 default 0x80000000 if VMSPLIT_2G
1203 default 0x78000000 if VMSPLIT_2G_OPT
1204 default 0x40000000 if VMSPLIT_1G
1210 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1213 bool "PAE (Physical Address Extension) Support"
1214 depends on X86_32 && !HIGHMEM4G
1216 PAE is required for NX support, and furthermore enables
1217 larger swapspace support for non-overcommit purposes. It
1218 has the cost of more pagetable lookup overhead, and also
1219 consumes more pagetable space per process.
1221 config ARCH_PHYS_ADDR_T_64BIT
1223 depends on X86_64 || X86_PAE
1225 config ARCH_DMA_ADDR_T_64BIT
1227 depends on X86_64 || HIGHMEM64G
1229 config DIRECT_GBPAGES
1230 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1234 Allow the kernel linear mapping to use 1GB pages on CPUs that
1235 support it. This can improve the kernel's performance a tiny bit by
1236 reducing TLB pressure. If in doubt, say "Y".
1238 # Common NUMA Features
1240 bool "Numa Memory Allocation and Scheduler Support"
1242 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1243 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1245 Enable NUMA (Non Uniform Memory Access) support.
1247 The kernel will try to allocate memory used by a CPU on the
1248 local memory controller of the CPU and add some more
1249 NUMA awareness to the kernel.
1251 For 64-bit this is recommended if the system is Intel Core i7
1252 (or later), AMD Opteron, or EM64T NUMA.
1254 For 32-bit this is only needed on (rare) 32-bit-only platforms
1255 that support NUMA topologies, such as NUMAQ / Summit, or if you
1256 boot a 32-bit kernel on a 64-bit NUMA platform.
1258 Otherwise, you should say N.
1260 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1261 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1265 prompt "Old style AMD Opteron NUMA detection"
1266 depends on X86_64 && NUMA && PCI
1268 Enable AMD NUMA node topology detection. You should say Y here if
1269 you have a multi processor AMD system. This uses an old method to
1270 read the NUMA configuration directly from the builtin Northbridge
1271 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1272 which also takes priority if both are compiled in.
1274 config X86_64_ACPI_NUMA
1276 prompt "ACPI NUMA detection"
1277 depends on X86_64 && NUMA && ACPI && PCI
1280 Enable ACPI SRAT based node topology detection.
1282 # Some NUMA nodes have memory ranges that span
1283 # other nodes. Even though a pfn is valid and
1284 # between a node's start and end pfns, it may not
1285 # reside on that node. See memmap_init_zone()
1287 config NODES_SPAN_OTHER_NODES
1289 depends on X86_64_ACPI_NUMA
1292 bool "NUMA emulation"
1295 Enable NUMA emulation. A flat machine will be split
1296 into virtual nodes when booted with "numa=fake=N", where N is the
1297 number of nodes. This is only useful for debugging.
1300 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1302 default "10" if MAXSMP
1303 default "6" if X86_64
1304 default "4" if X86_NUMAQ
1306 depends on NEED_MULTIPLE_NODES
1308 Specify the maximum number of NUMA Nodes available on the target
1309 system. Increases memory reserved to accommodate various tables.
1311 config ARCH_HAVE_MEMORY_PRESENT
1313 depends on X86_32 && DISCONTIGMEM
1315 config NEED_NODE_MEMMAP_SIZE
1317 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1319 config ARCH_FLATMEM_ENABLE
1321 depends on X86_32 && !NUMA
1323 config ARCH_DISCONTIGMEM_ENABLE
1325 depends on NUMA && X86_32
1327 config ARCH_DISCONTIGMEM_DEFAULT
1329 depends on NUMA && X86_32
1331 config ARCH_SPARSEMEM_ENABLE
1333 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1334 select SPARSEMEM_STATIC if X86_32
1335 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1337 config ARCH_SPARSEMEM_DEFAULT
1341 config ARCH_SELECT_MEMORY_MODEL
1343 depends on ARCH_SPARSEMEM_ENABLE
1345 config ARCH_MEMORY_PROBE
1347 depends on X86_64 && MEMORY_HOTPLUG
1349 config ARCH_PROC_KCORE_TEXT
1351 depends on X86_64 && PROC_KCORE
1353 config ILLEGAL_POINTER_VALUE
1356 default 0xdead000000000000 if X86_64
1361 bool "Allocate 3rd-level pagetables from highmem"
1364 The VM uses one page table entry for each page of physical memory.
1365 For systems with a lot of RAM, this can be wasteful of precious
1366 low memory. Setting this option will put user-space page table
1367 entries in high memory.
1369 config X86_CHECK_BIOS_CORRUPTION
1370 bool "Check for low memory corruption"
1372 Periodically check for memory corruption in low memory, which
1373 is suspected to be caused by BIOS. Even when enabled in the
1374 configuration, it is disabled at runtime. Enable it by
1375 setting "memory_corruption_check=1" on the kernel command
1376 line. By default it scans the low 64k of memory every 60
1377 seconds; see the memory_corruption_check_size and
1378 memory_corruption_check_period parameters in
1379 Documentation/kernel-parameters.txt to adjust this.
1381 When enabled with the default parameters, this option has
1382 almost no overhead, as it reserves a relatively small amount
1383 of memory and scans it infrequently. It both detects corruption
1384 and prevents it from affecting the running system.
1386 It is, however, intended as a diagnostic tool; if repeatable
1387 BIOS-originated corruption always affects the same memory,
1388 you can use memmap= to prevent the kernel from using that
1391 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1392 bool "Set the default setting of memory_corruption_check"
1393 depends on X86_CHECK_BIOS_CORRUPTION
1396 Set whether the default state of memory_corruption_check is
1399 config X86_RESERVE_LOW
1400 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1404 Specify the amount of low memory to reserve for the BIOS.
1406 The first page contains BIOS data structures that the kernel
1407 must not use, so that page must always be reserved.
1409 By default we reserve the first 64K of physical RAM, as a
1410 number of BIOSes are known to corrupt that memory range
1411 during events such as suspend/resume or monitor cable
1412 insertion, so it must not be used by the kernel.
1414 You can set this to 4 if you are absolutely sure that you
1415 trust the BIOS to get all its memory reservations and usages
1416 right. If you know your BIOS have problems beyond the
1417 default 64K area, you can set this to 640 to avoid using the
1418 entire low memory range.
1420 If you have doubts about the BIOS (e.g. suspend/resume does
1421 not work or there's kernel crashes after certain hardware
1422 hotplug events) then you might want to enable
1423 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1424 typical corruption patterns.
1426 Leave this to the default value of 64 if you are unsure.
1428 config MATH_EMULATION
1430 prompt "Math emulation" if X86_32
1432 Linux can emulate a math coprocessor (used for floating point
1433 operations) if you don't have one. 486DX and Pentium processors have
1434 a math coprocessor built in, 486SX and 386 do not, unless you added
1435 a 487DX or 387, respectively. (The messages during boot time can
1436 give you some hints here ["man dmesg"].) Everyone needs either a
1437 coprocessor or this emulation.
1439 If you don't have a math coprocessor, you need to say Y here; if you
1440 say Y here even though you have a coprocessor, the coprocessor will
1441 be used nevertheless. (This behavior can be changed with the kernel
1442 command line option "no387", which comes handy if your coprocessor
1443 is broken. Try "man bootparam" or see the documentation of your boot
1444 loader (lilo or loadlin) about how to pass options to the kernel at
1445 boot time.) This means that it is a good idea to say Y here if you
1446 intend to use this kernel on different machines.
1448 More information about the internals of the Linux math coprocessor
1449 emulation can be found in <file:arch/x86/math-emu/README>.
1451 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1452 kernel, it won't hurt.
1456 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1458 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1459 the Memory Type Range Registers (MTRRs) may be used to control
1460 processor access to memory ranges. This is most useful if you have
1461 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1462 allows bus write transfers to be combined into a larger transfer
1463 before bursting over the PCI/AGP bus. This can increase performance
1464 of image write operations 2.5 times or more. Saying Y here creates a
1465 /proc/mtrr file which may be used to manipulate your processor's
1466 MTRRs. Typically the X server should use this.
1468 This code has a reasonably generic interface so that similar
1469 control registers on other processors can be easily supported
1472 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1473 Registers (ARRs) which provide a similar functionality to MTRRs. For
1474 these, the ARRs are used to emulate the MTRRs.
1475 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1476 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1477 write-combining. All of these processors are supported by this code
1478 and it makes sense to say Y here if you have one of them.
1480 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1481 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1482 can lead to all sorts of problems, so it's good to say Y here.
1484 You can safely say Y even if your machine doesn't have MTRRs, you'll
1485 just add about 9 KB to your kernel.
1487 See <file:Documentation/x86/mtrr.txt> for more information.
1489 config MTRR_SANITIZER
1491 prompt "MTRR cleanup support"
1494 Convert MTRR layout from continuous to discrete, so X drivers can
1495 add writeback entries.
1497 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1498 The largest mtrr entry size for a continuous block can be set with
1503 config MTRR_SANITIZER_ENABLE_DEFAULT
1504 int "MTRR cleanup enable value (0-1)"
1507 depends on MTRR_SANITIZER
1509 Enable mtrr cleanup default value
1511 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1512 int "MTRR cleanup spare reg num (0-7)"
1515 depends on MTRR_SANITIZER
1517 mtrr cleanup spare entries default, it can be changed via
1518 mtrr_spare_reg_nr=N on the kernel command line.
1522 prompt "x86 PAT support" if EXPERT
1525 Use PAT attributes to setup page level cache control.
1527 PATs are the modern equivalents of MTRRs and are much more
1528 flexible than MTRRs.
1530 Say N here if you see bootup problems (boot crash, boot hang,
1531 spontaneous reboots) or a non-working video driver.
1535 config ARCH_USES_PG_UNCACHED
1541 prompt "x86 architectural random number generator" if EXPERT
1543 Enable the x86 architectural RDRAND instruction
1544 (Intel Bull Mountain technology) to generate random numbers.
1545 If supported, this is a high bandwidth, cryptographically
1546 secure hardware random number generator.
1550 prompt "Supervisor Mode Access Prevention" if EXPERT
1552 Supervisor Mode Access Prevention (SMAP) is a security
1553 feature in newer Intel processors. There is a small
1554 performance cost if this enabled and turned on; there is
1555 also a small increase in the kernel size if this is enabled.
1560 bool "EFI runtime service support"
1564 This enables the kernel to use EFI runtime services that are
1565 available (such as the EFI variable services).
1567 This option is only useful on systems that have EFI firmware.
1568 In addition, you should use the latest ELILO loader available
1569 at <http://elilo.sourceforge.net> in order to take advantage
1570 of EFI runtime services. However, even with this option, the
1571 resultant kernel should continue to boot on existing non-EFI
1575 bool "EFI stub support"
1578 This kernel feature allows a bzImage to be loaded directly
1579 by EFI firmware without the use of a bootloader.
1581 See Documentation/x86/efi-stub.txt for more information.
1585 prompt "Enable seccomp to safely compute untrusted bytecode"
1587 This kernel feature is useful for number crunching applications
1588 that may need to compute untrusted bytecode during their
1589 execution. By using pipes or other transports made available to
1590 the process as file descriptors supporting the read/write
1591 syscalls, it's possible to isolate those applications in
1592 their own address space using seccomp. Once seccomp is
1593 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1594 and the task is only allowed to execute a few safe syscalls
1595 defined by each seccomp mode.
1597 If unsure, say Y. Only embedded should say N here.
1599 config CC_STACKPROTECTOR
1600 bool "Enable -fstack-protector buffer overflow detection"
1602 This option turns on the -fstack-protector GCC feature. This
1603 feature puts, at the beginning of functions, a canary value on
1604 the stack just before the return address, and validates
1605 the value just before actually returning. Stack based buffer
1606 overflows (that need to overwrite this return address) now also
1607 overwrite the canary, which gets detected and the attack is then
1608 neutralized via a kernel panic.
1610 This feature requires gcc version 4.2 or above, or a distribution
1611 gcc with the feature backported. Older versions are automatically
1612 detected and for those versions, this configuration option is
1613 ignored. (and a warning is printed during bootup)
1615 source kernel/Kconfig.hz
1618 bool "kexec system call"
1620 kexec is a system call that implements the ability to shutdown your
1621 current kernel, and to start another kernel. It is like a reboot
1622 but it is independent of the system firmware. And like a reboot
1623 you can start any kernel with it, not just Linux.
1625 The name comes from the similarity to the exec system call.
1627 It is an ongoing process to be certain the hardware in a machine
1628 is properly shutdown, so do not be surprised if this code does not
1629 initially work for you. It may help to enable device hotplugging
1630 support. As of this writing the exact hardware interface is
1631 strongly in flux, so no good recommendation can be made.
1634 bool "kernel crash dumps"
1635 depends on X86_64 || (X86_32 && HIGHMEM)
1637 Generate crash dump after being started by kexec.
1638 This should be normally only set in special crash dump kernels
1639 which are loaded in the main kernel with kexec-tools into
1640 a specially reserved region and then later executed after
1641 a crash by kdump/kexec. The crash dump kernel must be compiled
1642 to a memory address not used by the main kernel or BIOS using
1643 PHYSICAL_START, or it must be built as a relocatable image
1644 (CONFIG_RELOCATABLE=y).
1645 For more details see Documentation/kdump/kdump.txt
1649 depends on KEXEC && HIBERNATION
1651 Jump between original kernel and kexeced kernel and invoke
1652 code in physical address mode via KEXEC
1654 config PHYSICAL_START
1655 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1658 This gives the physical address where the kernel is loaded.
1660 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1661 bzImage will decompress itself to above physical address and
1662 run from there. Otherwise, bzImage will run from the address where
1663 it has been loaded by the boot loader and will ignore above physical
1666 In normal kdump cases one does not have to set/change this option
1667 as now bzImage can be compiled as a completely relocatable image
1668 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1669 address. This option is mainly useful for the folks who don't want
1670 to use a bzImage for capturing the crash dump and want to use a
1671 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1672 to be specifically compiled to run from a specific memory area
1673 (normally a reserved region) and this option comes handy.
1675 So if you are using bzImage for capturing the crash dump,
1676 leave the value here unchanged to 0x1000000 and set
1677 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1678 for capturing the crash dump change this value to start of
1679 the reserved region. In other words, it can be set based on
1680 the "X" value as specified in the "crashkernel=YM@XM"
1681 command line boot parameter passed to the panic-ed
1682 kernel. Please take a look at Documentation/kdump/kdump.txt
1683 for more details about crash dumps.
1685 Usage of bzImage for capturing the crash dump is recommended as
1686 one does not have to build two kernels. Same kernel can be used
1687 as production kernel and capture kernel. Above option should have
1688 gone away after relocatable bzImage support is introduced. But it
1689 is present because there are users out there who continue to use
1690 vmlinux for dump capture. This option should go away down the
1693 Don't change this unless you know what you are doing.
1696 bool "Build a relocatable kernel"
1699 This builds a kernel image that retains relocation information
1700 so it can be loaded someplace besides the default 1MB.
1701 The relocations tend to make the kernel binary about 10% larger,
1702 but are discarded at runtime.
1704 One use is for the kexec on panic case where the recovery kernel
1705 must live at a different physical address than the primary
1708 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1709 it has been loaded at and the compile time physical address
1710 (CONFIG_PHYSICAL_START) is ignored.
1712 # Relocation on x86-32 needs some additional build support
1713 config X86_NEED_RELOCS
1715 depends on X86_32 && RELOCATABLE
1717 config PHYSICAL_ALIGN
1718 hex "Alignment value to which kernel should be aligned" if X86_32
1720 range 0x2000 0x1000000
1722 This value puts the alignment restrictions on physical address
1723 where kernel is loaded and run from. Kernel is compiled for an
1724 address which meets above alignment restriction.
1726 If bootloader loads the kernel at a non-aligned address and
1727 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1728 address aligned to above value and run from there.
1730 If bootloader loads the kernel at a non-aligned address and
1731 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1732 load address and decompress itself to the address it has been
1733 compiled for and run from there. The address for which kernel is
1734 compiled already meets above alignment restrictions. Hence the
1735 end result is that kernel runs from a physical address meeting
1736 above alignment restrictions.
1738 Don't change this unless you know what you are doing.
1741 bool "Support for hot-pluggable CPUs"
1744 Say Y here to allow turning CPUs off and on. CPUs can be
1745 controlled through /sys/devices/system/cpu.
1746 ( Note: power management support will enable this option
1747 automatically on SMP systems. )
1748 Say N if you want to disable CPU hotplug.
1750 config BOOTPARAM_HOTPLUG_CPU0
1751 bool "Set default setting of cpu0_hotpluggable"
1753 depends on HOTPLUG_CPU
1755 Set whether default state of cpu0_hotpluggable is on or off.
1757 Say Y here to enable CPU0 hotplug by default. If this switch
1758 is turned on, there is no need to give cpu0_hotplug kernel
1759 parameter and the CPU0 hotplug feature is enabled by default.
1761 Please note: there are two known CPU0 dependencies if you want
1762 to enable the CPU0 hotplug feature either by this switch or by
1763 cpu0_hotplug kernel parameter.
1765 First, resume from hibernate or suspend always starts from CPU0.
1766 So hibernate and suspend are prevented if CPU0 is offline.
1768 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1769 offline if any interrupt can not migrate out of CPU0. There may
1770 be other CPU0 dependencies.
1772 Please make sure the dependencies are under your control before
1773 you enable this feature.
1775 Say N if you don't want to enable CPU0 hotplug feature by default.
1776 You still can enable the CPU0 hotplug feature at boot by kernel
1777 parameter cpu0_hotplug.
1779 config DEBUG_HOTPLUG_CPU0
1781 prompt "Debug CPU0 hotplug"
1782 depends on HOTPLUG_CPU
1784 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1785 soon as possible and boots up userspace with CPU0 offlined. User
1786 can online CPU0 back after boot time.
1788 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1789 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1790 compilation or giving cpu0_hotplug kernel parameter at boot.
1796 prompt "Compat VDSO support"
1797 depends on X86_32 || IA32_EMULATION
1799 Map the 32-bit VDSO to the predictable old-style address too.
1801 Say N here if you are running a sufficiently recent glibc
1802 version (2.3.3 or later), to remove the high-mapped
1803 VDSO mapping and to exclusively use the randomized VDSO.
1808 bool "Built-in kernel command line"
1810 Allow for specifying boot arguments to the kernel at
1811 build time. On some systems (e.g. embedded ones), it is
1812 necessary or convenient to provide some or all of the
1813 kernel boot arguments with the kernel itself (that is,
1814 to not rely on the boot loader to provide them.)
1816 To compile command line arguments into the kernel,
1817 set this option to 'Y', then fill in the
1818 the boot arguments in CONFIG_CMDLINE.
1820 Systems with fully functional boot loaders (i.e. non-embedded)
1821 should leave this option set to 'N'.
1824 string "Built-in kernel command string"
1825 depends on CMDLINE_BOOL
1828 Enter arguments here that should be compiled into the kernel
1829 image and used at boot time. If the boot loader provides a
1830 command line at boot time, it is appended to this string to
1831 form the full kernel command line, when the system boots.
1833 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1834 change this behavior.
1836 In most cases, the command line (whether built-in or provided
1837 by the boot loader) should specify the device for the root
1840 config CMDLINE_OVERRIDE
1841 bool "Built-in command line overrides boot loader arguments"
1842 depends on CMDLINE_BOOL
1844 Set this option to 'Y' to have the kernel ignore the boot loader
1845 command line, and use ONLY the built-in command line.
1847 This is used to work around broken boot loaders. This should
1848 be set to 'N' under normal conditions.
1852 config ARCH_ENABLE_MEMORY_HOTPLUG
1854 depends on X86_64 || (X86_32 && HIGHMEM)
1856 config ARCH_ENABLE_MEMORY_HOTREMOVE
1858 depends on MEMORY_HOTPLUG
1860 config USE_PERCPU_NUMA_NODE_ID
1864 menu "Power management and ACPI options"
1866 config ARCH_HIBERNATION_HEADER
1868 depends on X86_64 && HIBERNATION
1870 source "kernel/power/Kconfig"
1872 source "drivers/acpi/Kconfig"
1874 source "drivers/sfi/Kconfig"
1881 tristate "APM (Advanced Power Management) BIOS support"
1882 depends on X86_32 && PM_SLEEP
1884 APM is a BIOS specification for saving power using several different
1885 techniques. This is mostly useful for battery powered laptops with
1886 APM compliant BIOSes. If you say Y here, the system time will be
1887 reset after a RESUME operation, the /proc/apm device will provide
1888 battery status information, and user-space programs will receive
1889 notification of APM "events" (e.g. battery status change).
1891 If you select "Y" here, you can disable actual use of the APM
1892 BIOS by passing the "apm=off" option to the kernel at boot time.
1894 Note that the APM support is almost completely disabled for
1895 machines with more than one CPU.
1897 In order to use APM, you will need supporting software. For location
1898 and more information, read <file:Documentation/power/apm-acpi.txt>
1899 and the Battery Powered Linux mini-HOWTO, available from
1900 <http://www.tldp.org/docs.html#howto>.
1902 This driver does not spin down disk drives (see the hdparm(8)
1903 manpage ("man 8 hdparm") for that), and it doesn't turn off
1904 VESA-compliant "green" monitors.
1906 This driver does not support the TI 4000M TravelMate and the ACER
1907 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1908 desktop machines also don't have compliant BIOSes, and this driver
1909 may cause those machines to panic during the boot phase.
1911 Generally, if you don't have a battery in your machine, there isn't
1912 much point in using this driver and you should say N. If you get
1913 random kernel OOPSes or reboots that don't seem to be related to
1914 anything, try disabling/enabling this option (or disabling/enabling
1917 Some other things you should try when experiencing seemingly random,
1920 1) make sure that you have enough swap space and that it is
1922 2) pass the "no-hlt" option to the kernel
1923 3) switch on floating point emulation in the kernel and pass
1924 the "no387" option to the kernel
1925 4) pass the "floppy=nodma" option to the kernel
1926 5) pass the "mem=4M" option to the kernel (thereby disabling
1927 all but the first 4 MB of RAM)
1928 6) make sure that the CPU is not over clocked.
1929 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1930 8) disable the cache from your BIOS settings
1931 9) install a fan for the video card or exchange video RAM
1932 10) install a better fan for the CPU
1933 11) exchange RAM chips
1934 12) exchange the motherboard.
1936 To compile this driver as a module, choose M here: the
1937 module will be called apm.
1941 config APM_IGNORE_USER_SUSPEND
1942 bool "Ignore USER SUSPEND"
1944 This option will ignore USER SUSPEND requests. On machines with a
1945 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1946 series notebooks, it is necessary to say Y because of a BIOS bug.
1948 config APM_DO_ENABLE
1949 bool "Enable PM at boot time"
1951 Enable APM features at boot time. From page 36 of the APM BIOS
1952 specification: "When disabled, the APM BIOS does not automatically
1953 power manage devices, enter the Standby State, enter the Suspend
1954 State, or take power saving steps in response to CPU Idle calls."
1955 This driver will make CPU Idle calls when Linux is idle (unless this
1956 feature is turned off -- see "Do CPU IDLE calls", below). This
1957 should always save battery power, but more complicated APM features
1958 will be dependent on your BIOS implementation. You may need to turn
1959 this option off if your computer hangs at boot time when using APM
1960 support, or if it beeps continuously instead of suspending. Turn
1961 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1962 T400CDT. This is off by default since most machines do fine without
1967 bool "Make CPU Idle calls when idle"
1969 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1970 On some machines, this can activate improved power savings, such as
1971 a slowed CPU clock rate, when the machine is idle. These idle calls
1972 are made after the idle loop has run for some length of time (e.g.,
1973 333 mS). On some machines, this will cause a hang at boot time or
1974 whenever the CPU becomes idle. (On machines with more than one CPU,
1975 this option does nothing.)
1977 config APM_DISPLAY_BLANK
1978 bool "Enable console blanking using APM"
1980 Enable console blanking using the APM. Some laptops can use this to
1981 turn off the LCD backlight when the screen blanker of the Linux
1982 virtual console blanks the screen. Note that this is only used by
1983 the virtual console screen blanker, and won't turn off the backlight
1984 when using the X Window system. This also doesn't have anything to
1985 do with your VESA-compliant power-saving monitor. Further, this
1986 option doesn't work for all laptops -- it might not turn off your
1987 backlight at all, or it might print a lot of errors to the console,
1988 especially if you are using gpm.
1990 config APM_ALLOW_INTS
1991 bool "Allow interrupts during APM BIOS calls"
1993 Normally we disable external interrupts while we are making calls to
1994 the APM BIOS as a measure to lessen the effects of a badly behaving
1995 BIOS implementation. The BIOS should reenable interrupts if it
1996 needs to. Unfortunately, some BIOSes do not -- especially those in
1997 many of the newer IBM Thinkpads. If you experience hangs when you
1998 suspend, try setting this to Y. Otherwise, say N.
2002 source "drivers/cpufreq/Kconfig"
2004 source "drivers/cpuidle/Kconfig"
2006 source "drivers/idle/Kconfig"
2011 menu "Bus options (PCI etc.)"
2016 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2018 Find out whether you have a PCI motherboard. PCI is the name of a
2019 bus system, i.e. the way the CPU talks to the other stuff inside
2020 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2021 VESA. If you have PCI, say Y, otherwise N.
2024 prompt "PCI access mode"
2025 depends on X86_32 && PCI
2028 On PCI systems, the BIOS can be used to detect the PCI devices and
2029 determine their configuration. However, some old PCI motherboards
2030 have BIOS bugs and may crash if this is done. Also, some embedded
2031 PCI-based systems don't have any BIOS at all. Linux can also try to
2032 detect the PCI hardware directly without using the BIOS.
2034 With this option, you can specify how Linux should detect the
2035 PCI devices. If you choose "BIOS", the BIOS will be used,
2036 if you choose "Direct", the BIOS won't be used, and if you
2037 choose "MMConfig", then PCI Express MMCONFIG will be used.
2038 If you choose "Any", the kernel will try MMCONFIG, then the
2039 direct access method and falls back to the BIOS if that doesn't
2040 work. If unsure, go with the default, which is "Any".
2045 config PCI_GOMMCONFIG
2062 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2064 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2067 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2071 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2075 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2079 depends on PCI && XEN
2087 bool "Support mmconfig PCI config space access"
2088 depends on X86_64 && PCI && ACPI
2090 config PCI_CNB20LE_QUIRK
2091 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2094 Read the PCI windows out of the CNB20LE host bridge. This allows
2095 PCI hotplug to work on systems with the CNB20LE chipset which do
2098 There's no public spec for this chipset, and this functionality
2099 is known to be incomplete.
2101 You should say N unless you know you need this.
2103 source "drivers/pci/pcie/Kconfig"
2105 source "drivers/pci/Kconfig"
2107 # x86_64 have no ISA slots, but can have ISA-style DMA.
2109 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2112 Enables ISA-style DMA support for devices requiring such controllers.
2120 Find out whether you have ISA slots on your motherboard. ISA is the
2121 name of a bus system, i.e. the way the CPU talks to the other stuff
2122 inside your box. Other bus systems are PCI, EISA, MicroChannel
2123 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2124 newer boards don't support it. If you have ISA, say Y, otherwise N.
2130 The Extended Industry Standard Architecture (EISA) bus was
2131 developed as an open alternative to the IBM MicroChannel bus.
2133 The EISA bus provided some of the features of the IBM MicroChannel
2134 bus while maintaining backward compatibility with cards made for
2135 the older ISA bus. The EISA bus saw limited use between 1988 and
2136 1995 when it was made obsolete by the PCI bus.
2138 Say Y here if you are building a kernel for an EISA-based machine.
2142 source "drivers/eisa/Kconfig"
2145 tristate "NatSemi SCx200 support"
2147 This provides basic support for National Semiconductor's
2148 (now AMD's) Geode processors. The driver probes for the
2149 PCI-IDs of several on-chip devices, so its a good dependency
2150 for other scx200_* drivers.
2152 If compiled as a module, the driver is named scx200.
2154 config SCx200HR_TIMER
2155 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2159 This driver provides a clocksource built upon the on-chip
2160 27MHz high-resolution timer. Its also a workaround for
2161 NSC Geode SC-1100's buggy TSC, which loses time when the
2162 processor goes idle (as is done by the scheduler). The
2163 other workaround is idle=poll boot option.
2166 bool "One Laptop Per Child support"
2173 Add support for detecting the unique features of the OLPC
2177 bool "OLPC XO-1 Power Management"
2178 depends on OLPC && MFD_CS5535 && PM_SLEEP
2181 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2184 bool "OLPC XO-1 Real Time Clock"
2185 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2187 Add support for the XO-1 real time clock, which can be used as a
2188 programmable wakeup source.
2191 bool "OLPC XO-1 SCI extras"
2192 depends on OLPC && OLPC_XO1_PM
2198 Add support for SCI-based features of the OLPC XO-1 laptop:
2199 - EC-driven system wakeups
2203 - AC adapter status updates
2204 - Battery status updates
2206 config OLPC_XO15_SCI
2207 bool "OLPC XO-1.5 SCI extras"
2208 depends on OLPC && ACPI
2211 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2212 - EC-driven system wakeups
2213 - AC adapter status updates
2214 - Battery status updates
2217 bool "PCEngines ALIX System Support (LED setup)"
2220 This option enables system support for the PCEngines ALIX.
2221 At present this just sets up LEDs for GPIO control on
2222 ALIX2/3/6 boards. However, other system specific setup should
2225 Note: You must still enable the drivers for GPIO and LED support
2226 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2228 Note: You have to set alix.force=1 for boards with Award BIOS.
2231 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2234 This option enables system support for the Soekris Engineering net5501.
2237 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2241 This option enables system support for the Traverse Technologies GEOS.
2244 bool "Technologic Systems TS-5500 platform support"
2246 select CHECK_SIGNATURE
2250 This option enables system support for the Technologic Systems TS-5500.
2256 depends on CPU_SUP_AMD && PCI
2258 source "drivers/pcmcia/Kconfig"
2260 source "drivers/pci/hotplug/Kconfig"
2263 tristate "RapidIO support"
2267 If enabled this option will include drivers and the core
2268 infrastructure code to support RapidIO interconnect devices.
2270 source "drivers/rapidio/Kconfig"
2275 menu "Executable file formats / Emulations"
2277 source "fs/Kconfig.binfmt"
2279 config IA32_EMULATION
2280 bool "IA32 Emulation"
2283 select COMPAT_BINFMT_ELF
2286 Include code to run legacy 32-bit programs under a
2287 64-bit kernel. You should likely turn this on, unless you're
2288 100% sure that you don't have any 32-bit programs left.
2291 tristate "IA32 a.out support"
2292 depends on IA32_EMULATION
2294 Support old a.out binaries in the 32bit emulation.
2297 bool "x32 ABI for 64-bit mode"
2298 depends on X86_64 && IA32_EMULATION
2300 Include code to run binaries for the x32 native 32-bit ABI
2301 for 64-bit processors. An x32 process gets access to the
2302 full 64-bit register file and wide data path while leaving
2303 pointers at 32 bits for smaller memory footprint.
2305 You will need a recent binutils (2.22 or later) with
2306 elf32_x86_64 support enabled to compile a kernel with this
2311 depends on IA32_EMULATION || X86_X32
2312 select ARCH_WANT_OLD_COMPAT_IPC
2315 config COMPAT_FOR_U64_ALIGNMENT
2318 config SYSVIPC_COMPAT
2330 config HAVE_ATOMIC_IOMAP
2334 config HAVE_TEXT_POKE_SMP
2336 select STOP_MACHINE if SMP
2338 config X86_DEV_DMA_OPS
2340 depends on X86_64 || STA2X11
2342 config X86_DMA_REMAP
2346 source "net/Kconfig"
2348 source "drivers/Kconfig"
2350 source "drivers/firmware/Kconfig"
2354 source "arch/x86/Kconfig.debug"
2356 source "security/Kconfig"
2358 source "crypto/Kconfig"
2360 source "arch/x86/kvm/Kconfig"
2362 source "lib/Kconfig"