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 GENERIC_IDLE_LOOP
101 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
102 select HAVE_ARCH_SECCOMP_FILTER
103 select BUILDTIME_EXTABLE_SORT
104 select GENERIC_CMOS_UPDATE
105 select CLOCKSOURCE_WATCHDOG
106 select GENERIC_CLOCKEVENTS
107 select ARCH_CLOCKSOURCE_DATA if X86_64
108 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
109 select GENERIC_TIME_VSYSCALL if X86_64
110 select KTIME_SCALAR if X86_32
111 select ALWAYS_USE_PERSISTENT_CLOCK
112 select GENERIC_STRNCPY_FROM_USER
113 select GENERIC_STRNLEN_USER
114 select HAVE_CONTEXT_TRACKING if X86_64
115 select HAVE_IRQ_TIME_ACCOUNTING
117 select MODULES_USE_ELF_REL if X86_32
118 select MODULES_USE_ELF_RELA if X86_64
119 select CLONE_BACKWARDS if X86_32
120 select ARCH_USE_BUILTIN_BSWAP
121 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
122 select OLD_SIGACTION if X86_32
123 select COMPAT_OLD_SIGACTION if IA32_EMULATION
125 config INSTRUCTION_DECODER
127 depends on KPROBES || PERF_EVENTS || UPROBES
131 default "elf32-i386" if X86_32
132 default "elf64-x86-64" if X86_64
134 config ARCH_DEFCONFIG
136 default "arch/x86/configs/i386_defconfig" if X86_32
137 default "arch/x86/configs/x86_64_defconfig" if X86_64
139 config LOCKDEP_SUPPORT
142 config STACKTRACE_SUPPORT
145 config HAVE_LATENCYTOP_SUPPORT
154 config NEED_DMA_MAP_STATE
156 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
158 config NEED_SG_DMA_LENGTH
161 config GENERIC_ISA_DMA
163 depends on ISA_DMA_API
168 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
170 config GENERIC_BUG_RELATIVE_POINTERS
173 config GENERIC_HWEIGHT
179 config ARCH_MAY_HAVE_PC_FDC
181 depends on ISA_DMA_API
183 config RWSEM_XCHGADD_ALGORITHM
186 config GENERIC_CALIBRATE_DELAY
189 config ARCH_HAS_CPU_RELAX
192 config ARCH_HAS_CACHE_LINE_SIZE
195 config ARCH_HAS_CPU_AUTOPROBE
198 config HAVE_SETUP_PER_CPU_AREA
201 config NEED_PER_CPU_EMBED_FIRST_CHUNK
204 config NEED_PER_CPU_PAGE_FIRST_CHUNK
207 config ARCH_HIBERNATION_POSSIBLE
210 config ARCH_SUSPEND_POSSIBLE
221 config ARCH_SUPPORTS_OPTIMIZED_INLINING
224 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
227 config HAVE_INTEL_TXT
229 depends on INTEL_IOMMU && ACPI
233 depends on X86_32 && SMP
237 depends on X86_64 && SMP
243 config X86_32_LAZY_GS
245 depends on X86_32 && !CC_STACKPROTECTOR
247 config ARCH_HWEIGHT_CFLAGS
249 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
250 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
252 config ARCH_CPU_PROBE_RELEASE
254 depends on HOTPLUG_CPU
256 config ARCH_SUPPORTS_UPROBES
259 source "init/Kconfig"
260 source "kernel/Kconfig.freezer"
262 menu "Processor type and features"
265 bool "DMA memory allocation support" if EXPERT
268 DMA memory allocation support allows devices with less than 32-bit
269 addressing to allocate within the first 16MB of address space.
270 Disable if no such devices will be used.
275 bool "Symmetric multi-processing support"
277 This enables support for systems with more than one CPU. If you have
278 a system with only one CPU, like most personal computers, say N. If
279 you have a system with more than one CPU, say Y.
281 If you say N here, the kernel will run on single and multiprocessor
282 machines, but will use only one CPU of a multiprocessor machine. If
283 you say Y here, the kernel will run on many, but not all,
284 singleprocessor machines. On a singleprocessor machine, the kernel
285 will run faster if you say N here.
287 Note that if you say Y here and choose architecture "586" or
288 "Pentium" under "Processor family", the kernel will not work on 486
289 architectures. Similarly, multiprocessor kernels for the "PPro"
290 architecture may not work on all Pentium based boards.
292 People using multiprocessor machines who say Y here should also say
293 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
294 Management" code will be disabled if you say Y here.
296 See also <file:Documentation/x86/i386/IO-APIC.txt>,
297 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
298 <http://www.tldp.org/docs.html#howto>.
300 If you don't know what to do here, say N.
303 bool "Support x2apic"
304 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
306 This enables x2apic support on CPUs that have this feature.
308 This allows 32-bit apic IDs (so it can support very large systems),
309 and accesses the local apic via MSRs not via mmio.
311 If you don't know what to do here, say N.
314 bool "Enable MPS table" if ACPI || SFI
316 depends on X86_LOCAL_APIC
318 For old smp systems that do not have proper acpi support. Newer systems
319 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
322 bool "Support for big SMP systems with more than 8 CPUs"
323 depends on X86_32 && SMP
325 This option is needed for the systems that have more than 8 CPUs
329 depends on X86_GOLDFISH
332 config X86_EXTENDED_PLATFORM
333 bool "Support for extended (non-PC) x86 platforms"
336 If you disable this option then the kernel will only support
337 standard PC platforms. (which covers the vast majority of
340 If you enable this option then you'll be able to select support
341 for the following (non-PC) 32 bit x86 platforms:
345 SGI 320/540 (Visual Workstation)
346 STA2X11-based (e.g. Northville)
347 Summit/EXA (IBM x440)
348 Unisys ES7000 IA32 series
349 Moorestown MID devices
351 If you have one of these systems, or if you want to build a
352 generic distribution kernel, say Y here - otherwise say N.
356 config X86_EXTENDED_PLATFORM
357 bool "Support for extended (non-PC) x86 platforms"
360 If you disable this option then the kernel will only support
361 standard PC platforms. (which covers the vast majority of
364 If you enable this option then you'll be able to select support
365 for the following (non-PC) 64 bit x86 platforms:
370 If you have one of these systems, or if you want to build a
371 generic distribution kernel, say Y here - otherwise say N.
373 # This is an alphabetically sorted list of 64 bit extended platforms
374 # Please maintain the alphabetic order if and when there are additions
376 bool "Numascale NumaChip"
378 depends on X86_EXTENDED_PLATFORM
381 depends on X86_X2APIC
382 depends on PCI_MMCONFIG
384 Adds support for Numascale NumaChip large-SMP systems. Needed to
385 enable more than ~168 cores.
386 If you don't have one of these, you should say N here.
390 select PARAVIRT_GUEST
392 depends on X86_64 && PCI
393 depends on X86_EXTENDED_PLATFORM
396 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
397 supposed to run on these EM64T-based machines. Only choose this option
398 if you have one of these machines.
401 bool "SGI Ultraviolet"
403 depends on X86_EXTENDED_PLATFORM
405 depends on X86_X2APIC
407 This option is needed in order to support SGI Ultraviolet systems.
408 If you don't have one of these, you should say N here.
410 # Following is an alphabetically sorted list of 32 bit extended platforms
411 # Please maintain the alphabetic order if and when there are additions
414 bool "Goldfish (Virtual Platform)"
417 Enable support for the Goldfish virtual platform used primarily
418 for Android development. Unless you are building for the Android
419 Goldfish emulator say N here.
422 bool "CE4100 TV platform"
424 depends on PCI_GODIRECT
426 depends on X86_EXTENDED_PLATFORM
427 select X86_REBOOTFIXUPS
429 select OF_EARLY_FLATTREE
432 Select for the Intel CE media processor (CE4100) SOC.
433 This option compiles in support for the CE4100 SOC for settop
434 boxes and media devices.
436 config X86_WANT_INTEL_MID
437 bool "Intel MID platform support"
439 depends on X86_EXTENDED_PLATFORM
441 Select to build a kernel capable of supporting Intel MID platform
442 systems which do not have the PCI legacy interfaces (Moorestown,
443 Medfield). If you are building for a PC class system say N here.
445 if X86_WANT_INTEL_MID
451 bool "Medfield MID platform"
454 depends on X86_IO_APIC
462 select X86_PLATFORM_DEVICES
463 select MFD_INTEL_MSIC
465 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
466 Internet Device(MID) platform.
467 Unlike standard x86 PCs, Medfield does not have many legacy devices
468 nor standard legacy replacement devices/features. e.g. Medfield does
469 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
473 config X86_INTEL_LPSS
474 bool "Intel Low Power Subsystem Support"
478 Select to build support for Intel Low Power Subsystem such as
479 found on Intel Lynxpoint PCH. Selecting this option enables
480 things like clock tree (common clock framework) which are needed
481 by the LPSS peripheral drivers.
484 bool "RDC R-321x SoC"
486 depends on X86_EXTENDED_PLATFORM
488 select X86_REBOOTFIXUPS
490 This option is needed for RDC R-321x system-on-chip, also known
492 If you don't have one of these chips, you should say N here.
494 config X86_32_NON_STANDARD
495 bool "Support non-standard 32-bit SMP architectures"
496 depends on X86_32 && SMP
497 depends on X86_EXTENDED_PLATFORM
499 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
500 STA2X11, default subarchitectures. It is intended for a generic
501 binary kernel. If you select them all, kernel will probe it
502 one by one and will fallback to default.
504 # Alphabetically sorted list of Non standard 32 bit platforms
507 bool "NUMAQ (IBM/Sequent)"
508 depends on X86_32_NON_STANDARD
513 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
514 NUMA multiquad box. This changes the way that processors are
515 bootstrapped, and uses Clustered Logical APIC addressing mode instead
516 of Flat Logical. You will need a new lynxer.elf file to flash your
517 firmware with - send email to <Martin.Bligh@us.ibm.com>.
519 config X86_SUPPORTS_MEMORY_FAILURE
521 # MCE code calls memory_failure():
523 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
524 depends on !X86_NUMAQ
525 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
526 depends on X86_64 || !SPARSEMEM
527 select ARCH_SUPPORTS_MEMORY_FAILURE
530 bool "SGI 320/540 (Visual Workstation)"
531 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
532 depends on X86_32_NON_STANDARD
534 The SGI Visual Workstation series is an IA32-based workstation
535 based on SGI systems chips with some legacy PC hardware attached.
537 Say Y here to create a kernel to run on the SGI 320 or 540.
539 A kernel compiled for the Visual Workstation will run on general
540 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
543 bool "STA2X11 Companion Chip Support"
544 depends on X86_32_NON_STANDARD && PCI
545 select X86_DEV_DMA_OPS
549 select ARCH_REQUIRE_GPIOLIB
552 This adds support for boards based on the STA2X11 IO-Hub,
553 a.k.a. "ConneXt". The chip is used in place of the standard
554 PC chipset, so all "standard" peripherals are missing. If this
555 option is selected the kernel will still be able to boot on
556 standard PC machines.
559 bool "Summit/EXA (IBM x440)"
560 depends on X86_32_NON_STANDARD
562 This option is needed for IBM systems that use the Summit/EXA chipset.
563 In particular, it is needed for the x440.
566 bool "Unisys ES7000 IA32 series"
567 depends on X86_32_NON_STANDARD && X86_BIGSMP
569 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
570 supposed to run on an IA32-based Unisys ES7000 system.
573 tristate "Eurobraille/Iris poweroff module"
576 The Iris machines from EuroBraille do not have APM or ACPI support
577 to shut themselves down properly. A special I/O sequence is
578 needed to do so, which is what this module does at
581 This is only for Iris machines from EuroBraille.
585 config SCHED_OMIT_FRAME_POINTER
587 prompt "Single-depth WCHAN output"
590 Calculate simpler /proc/<PID>/wchan values. If this option
591 is disabled then wchan values will recurse back to the
592 caller function. This provides more accurate wchan values,
593 at the expense of slightly more scheduling overhead.
595 If in doubt, say "Y".
597 menuconfig PARAVIRT_GUEST
598 bool "Paravirtualized guest support"
600 Say Y here to get to see options related to running Linux under
601 various hypervisors. This option alone does not add any kernel code.
603 If you say N, all options in this submenu will be skipped and disabled.
607 config PARAVIRT_TIME_ACCOUNTING
608 bool "Paravirtual steal time accounting"
612 Select this option to enable fine granularity task steal time
613 accounting. Time spent executing other tasks in parallel with
614 the current vCPU is discounted from the vCPU power. To account for
615 that, there can be a small performance impact.
617 If in doubt, say N here.
619 source "arch/x86/xen/Kconfig"
622 bool "KVM Guest support (including kvmclock)"
625 select PARAVIRT_CLOCK
626 default y if PARAVIRT_GUEST
628 This option enables various optimizations for running under the KVM
629 hypervisor. It includes a paravirtualized clock, so that instead
630 of relying on a PIT (or probably other) emulation by the
631 underlying device model, the host provides the guest with
632 timing infrastructure such as time of day, and system time
634 source "arch/x86/lguest/Kconfig"
637 bool "Enable paravirtualization code"
639 This changes the kernel so it can modify itself when it is run
640 under a hypervisor, potentially improving performance significantly
641 over full virtualization. However, when run without a hypervisor
642 the kernel is theoretically slower and slightly larger.
644 config PARAVIRT_SPINLOCKS
645 bool "Paravirtualization layer for spinlocks"
646 depends on PARAVIRT && SMP
648 Paravirtualized spinlocks allow a pvops backend to replace the
649 spinlock implementation with something virtualization-friendly
650 (for example, block the virtual CPU rather than spinning).
652 Unfortunately the downside is an up to 5% performance hit on
653 native kernels, with various workloads.
655 If you are unsure how to answer this question, answer N.
657 config PARAVIRT_CLOCK
662 config PARAVIRT_DEBUG
663 bool "paravirt-ops debugging"
664 depends on PARAVIRT && DEBUG_KERNEL
666 Enable to debug paravirt_ops internals. Specifically, BUG if
667 a paravirt_op is missing when it is called.
675 This option adds a kernel parameter 'memtest', which allows memtest
677 memtest=0, mean disabled; -- default
678 memtest=1, mean do 1 test pattern;
680 memtest=4, mean do 4 test patterns.
681 If you are unsure how to answer this question, answer N.
683 config X86_SUMMIT_NUMA
685 depends on X86_32 && NUMA && X86_32_NON_STANDARD
687 config X86_CYCLONE_TIMER
689 depends on X86_SUMMIT
691 source "arch/x86/Kconfig.cpu"
695 prompt "HPET Timer Support" if X86_32
697 Use the IA-PC HPET (High Precision Event Timer) to manage
698 time in preference to the PIT and RTC, if a HPET is
700 HPET is the next generation timer replacing legacy 8254s.
701 The HPET provides a stable time base on SMP
702 systems, unlike the TSC, but it is more expensive to access,
703 as it is off-chip. You can find the HPET spec at
704 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
706 You can safely choose Y here. However, HPET will only be
707 activated if the platform and the BIOS support this feature.
708 Otherwise the 8254 will be used for timing services.
710 Choose N to continue using the legacy 8254 timer.
712 config HPET_EMULATE_RTC
714 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
717 def_bool y if X86_INTEL_MID
718 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
720 depends on X86_INTEL_MID && SFI
722 APB timer is the replacement for 8254, HPET on X86 MID platforms.
723 The APBT provides a stable time base on SMP
724 systems, unlike the TSC, but it is more expensive to access,
725 as it is off-chip. APB timers are always running regardless of CPU
726 C states, they are used as per CPU clockevent device when possible.
728 # Mark as expert because too many people got it wrong.
729 # The code disables itself when not needed.
732 bool "Enable DMI scanning" if EXPERT
734 Enabled scanning of DMI to identify machine quirks. Say Y
735 here unless you have verified that your setup is not
736 affected by entries in the DMI blacklist. Required by PNP
740 bool "GART IOMMU support" if EXPERT
743 depends on X86_64 && PCI && AMD_NB
745 Support for full DMA access of devices with 32bit memory access only
746 on systems with more than 3GB. This is usually needed for USB,
747 sound, many IDE/SATA chipsets and some other devices.
748 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
749 based hardware IOMMU and a software bounce buffer based IOMMU used
750 on Intel systems and as fallback.
751 The code is only active when needed (enough memory and limited
752 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
756 bool "IBM Calgary IOMMU support"
758 depends on X86_64 && PCI
760 Support for hardware IOMMUs in IBM's xSeries x366 and x460
761 systems. Needed to run systems with more than 3GB of memory
762 properly with 32-bit PCI devices that do not support DAC
763 (Double Address Cycle). Calgary also supports bus level
764 isolation, where all DMAs pass through the IOMMU. This
765 prevents them from going anywhere except their intended
766 destination. This catches hard-to-find kernel bugs and
767 mis-behaving drivers and devices that do not use the DMA-API
768 properly to set up their DMA buffers. The IOMMU can be
769 turned off at boot time with the iommu=off parameter.
770 Normally the kernel will make the right choice by itself.
773 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
775 prompt "Should Calgary be enabled by default?"
776 depends on CALGARY_IOMMU
778 Should Calgary be enabled by default? if you choose 'y', Calgary
779 will be used (if it exists). If you choose 'n', Calgary will not be
780 used even if it exists. If you choose 'n' and would like to use
781 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
784 # need this always selected by IOMMU for the VIA workaround
788 Support for software bounce buffers used on x86-64 systems
789 which don't have a hardware IOMMU. Using this PCI devices
790 which can only access 32-bits of memory can be used on systems
791 with more than 3 GB of memory.
796 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
799 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
800 depends on X86_64 && SMP && DEBUG_KERNEL
801 select CPUMASK_OFFSTACK
803 Enable maximum number of CPUS and NUMA Nodes for this architecture.
807 int "Maximum number of CPUs" if SMP && !MAXSMP
808 range 2 8 if SMP && X86_32 && !X86_BIGSMP
809 range 2 512 if SMP && !MAXSMP
811 default "4096" if MAXSMP
812 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
815 This allows you to specify the maximum number of CPUs which this
816 kernel will support. The maximum supported value is 512 and the
817 minimum value which makes sense is 2.
819 This is purely to save memory - each supported CPU adds
820 approximately eight kilobytes to the kernel image.
823 bool "SMT (Hyperthreading) scheduler support"
826 SMT scheduler support improves the CPU scheduler's decision making
827 when dealing with Intel Pentium 4 chips with HyperThreading at a
828 cost of slightly increased overhead in some places. If unsure say
833 prompt "Multi-core scheduler support"
836 Multi-core scheduler support improves the CPU scheduler's decision
837 making when dealing with multi-core CPU chips at a cost of slightly
838 increased overhead in some places. If unsure say N here.
840 source "kernel/Kconfig.preempt"
843 bool "Local APIC support on uniprocessors"
844 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
846 A local APIC (Advanced Programmable Interrupt Controller) is an
847 integrated interrupt controller in the CPU. If you have a single-CPU
848 system which has a processor with a local APIC, you can say Y here to
849 enable and use it. If you say Y here even though your machine doesn't
850 have a local APIC, then the kernel will still run with no slowdown at
851 all. The local APIC supports CPU-generated self-interrupts (timer,
852 performance counters), and the NMI watchdog which detects hard
856 bool "IO-APIC support on uniprocessors"
857 depends on X86_UP_APIC
859 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
860 SMP-capable replacement for PC-style interrupt controllers. Most
861 SMP systems and many recent uniprocessor systems have one.
863 If you have a single-CPU system with an IO-APIC, you can say Y here
864 to use it. If you say Y here even though your machine doesn't have
865 an IO-APIC, then the kernel will still run with no slowdown at all.
867 config X86_LOCAL_APIC
869 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
873 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
875 config X86_VISWS_APIC
877 depends on X86_32 && X86_VISWS
879 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
880 bool "Reroute for broken boot IRQs"
881 depends on X86_IO_APIC
883 This option enables a workaround that fixes a source of
884 spurious interrupts. This is recommended when threaded
885 interrupt handling is used on systems where the generation of
886 superfluous "boot interrupts" cannot be disabled.
888 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
889 entry in the chipset's IO-APIC is masked (as, e.g. the RT
890 kernel does during interrupt handling). On chipsets where this
891 boot IRQ generation cannot be disabled, this workaround keeps
892 the original IRQ line masked so that only the equivalent "boot
893 IRQ" is delivered to the CPUs. The workaround also tells the
894 kernel to set up the IRQ handler on the boot IRQ line. In this
895 way only one interrupt is delivered to the kernel. Otherwise
896 the spurious second interrupt may cause the kernel to bring
897 down (vital) interrupt lines.
899 Only affects "broken" chipsets. Interrupt sharing may be
900 increased on these systems.
903 bool "Machine Check / overheating reporting"
906 Machine Check support allows the processor to notify the
907 kernel if it detects a problem (e.g. overheating, data corruption).
908 The action the kernel takes depends on the severity of the problem,
909 ranging from warning messages to halting the machine.
913 prompt "Intel MCE features"
914 depends on X86_MCE && X86_LOCAL_APIC
916 Additional support for intel specific MCE features such as
921 prompt "AMD MCE features"
922 depends on X86_MCE && X86_LOCAL_APIC
924 Additional support for AMD specific MCE features such as
925 the DRAM Error Threshold.
927 config X86_ANCIENT_MCE
928 bool "Support for old Pentium 5 / WinChip machine checks"
929 depends on X86_32 && X86_MCE
931 Include support for machine check handling on old Pentium 5 or WinChip
932 systems. These typically need to be enabled explicitely on the command
935 config X86_MCE_THRESHOLD
936 depends on X86_MCE_AMD || X86_MCE_INTEL
939 config X86_MCE_INJECT
941 tristate "Machine check injector support"
943 Provide support for injecting machine checks for testing purposes.
944 If you don't know what a machine check is and you don't do kernel
945 QA it is safe to say n.
947 config X86_THERMAL_VECTOR
949 depends on X86_MCE_INTEL
952 bool "Enable VM86 support" if EXPERT
956 This option is required by programs like DOSEMU to run 16-bit legacy
957 code on X86 processors. It also may be needed by software like
958 XFree86 to initialize some video cards via BIOS. Disabling this
959 option saves about 6k.
962 tristate "Toshiba Laptop support"
965 This adds a driver to safely access the System Management Mode of
966 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
967 not work on models with a Phoenix BIOS. The System Management Mode
968 is used to set the BIOS and power saving options on Toshiba portables.
970 For information on utilities to make use of this driver see the
971 Toshiba Linux utilities web site at:
972 <http://www.buzzard.org.uk/toshiba/>.
974 Say Y if you intend to run this kernel on a Toshiba portable.
978 tristate "Dell laptop support"
981 This adds a driver to safely access the System Management Mode
982 of the CPU on the Dell Inspiron 8000. The System Management Mode
983 is used to read cpu temperature and cooling fan status and to
984 control the fans on the I8K portables.
986 This driver has been tested only on the Inspiron 8000 but it may
987 also work with other Dell laptops. You can force loading on other
988 models by passing the parameter `force=1' to the module. Use at
991 For information on utilities to make use of this driver see the
992 I8K Linux utilities web site at:
993 <http://people.debian.org/~dz/i8k/>
995 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
998 config X86_REBOOTFIXUPS
999 bool "Enable X86 board specific fixups for reboot"
1002 This enables chipset and/or board specific fixups to be done
1003 in order to get reboot to work correctly. This is only needed on
1004 some combinations of hardware and BIOS. The symptom, for which
1005 this config is intended, is when reboot ends with a stalled/hung
1008 Currently, the only fixup is for the Geode machines using
1009 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1011 Say Y if you want to enable the fixup. Currently, it's safe to
1012 enable this option even if you don't need it.
1016 tristate "CPU microcode loading support"
1020 If you say Y here, you will be able to update the microcode on
1021 certain Intel and AMD processors. The Intel support is for the
1022 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1023 Xeon etc. The AMD support is for families 0x10 and later. You will
1024 obviously need the actual microcode binary data itself which is not
1025 shipped with the Linux kernel.
1027 This option selects the general module only, you need to select
1028 at least one vendor specific module as well.
1030 To compile this driver as a module, choose M here: the module
1031 will be called microcode.
1033 config MICROCODE_INTEL
1034 bool "Intel microcode loading support"
1035 depends on MICROCODE
1039 This options enables microcode patch loading support for Intel
1042 For latest news and information on obtaining all the required
1043 Intel ingredients for this driver, check:
1044 <http://www.urbanmyth.org/microcode/>.
1046 config MICROCODE_AMD
1047 bool "AMD microcode loading support"
1048 depends on MICROCODE
1051 If you select this option, microcode patch loading support for AMD
1052 processors will be enabled.
1054 config MICROCODE_OLD_INTERFACE
1056 depends on MICROCODE
1058 config MICROCODE_INTEL_LIB
1060 depends on MICROCODE_INTEL
1062 config MICROCODE_INTEL_EARLY
1063 bool "Early load microcode"
1064 depends on MICROCODE_INTEL && BLK_DEV_INITRD
1067 This option provides functionality to read additional microcode data
1068 at the beginning of initrd image. The data tells kernel to load
1069 microcode to CPU's as early as possible. No functional change if no
1070 microcode data is glued to the initrd, therefore it's safe to say Y.
1072 config MICROCODE_EARLY
1074 depends on MICROCODE_INTEL_EARLY
1077 tristate "/dev/cpu/*/msr - Model-specific register support"
1079 This device gives privileged processes access to the x86
1080 Model-Specific Registers (MSRs). It is a character device with
1081 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1082 MSR accesses are directed to a specific CPU on multi-processor
1086 tristate "/dev/cpu/*/cpuid - CPU information support"
1088 This device gives processes access to the x86 CPUID instruction to
1089 be executed on a specific processor. It is a character device
1090 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1094 prompt "High Memory Support"
1095 default HIGHMEM64G if X86_NUMAQ
1101 depends on !X86_NUMAQ
1103 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1104 However, the address space of 32-bit x86 processors is only 4
1105 Gigabytes large. That means that, if you have a large amount of
1106 physical memory, not all of it can be "permanently mapped" by the
1107 kernel. The physical memory that's not permanently mapped is called
1110 If you are compiling a kernel which will never run on a machine with
1111 more than 1 Gigabyte total physical RAM, answer "off" here (default
1112 choice and suitable for most users). This will result in a "3GB/1GB"
1113 split: 3GB are mapped so that each process sees a 3GB virtual memory
1114 space and the remaining part of the 4GB virtual memory space is used
1115 by the kernel to permanently map as much physical memory as
1118 If the machine has between 1 and 4 Gigabytes physical RAM, then
1121 If more than 4 Gigabytes is used then answer "64GB" here. This
1122 selection turns Intel PAE (Physical Address Extension) mode on.
1123 PAE implements 3-level paging on IA32 processors. PAE is fully
1124 supported by Linux, PAE mode is implemented on all recent Intel
1125 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1126 then the kernel will not boot on CPUs that don't support PAE!
1128 The actual amount of total physical memory will either be
1129 auto detected or can be forced by using a kernel command line option
1130 such as "mem=256M". (Try "man bootparam" or see the documentation of
1131 your boot loader (lilo or loadlin) about how to pass options to the
1132 kernel at boot time.)
1134 If unsure, say "off".
1138 depends on !X86_NUMAQ
1140 Select this if you have a 32-bit processor and between 1 and 4
1141 gigabytes of physical RAM.
1148 Select this if you have a 32-bit processor and more than 4
1149 gigabytes of physical RAM.
1154 prompt "Memory split" if EXPERT
1158 Select the desired split between kernel and user memory.
1160 If the address range available to the kernel is less than the
1161 physical memory installed, the remaining memory will be available
1162 as "high memory". Accessing high memory is a little more costly
1163 than low memory, as it needs to be mapped into the kernel first.
1164 Note that increasing the kernel address space limits the range
1165 available to user programs, making the address space there
1166 tighter. Selecting anything other than the default 3G/1G split
1167 will also likely make your kernel incompatible with binary-only
1170 If you are not absolutely sure what you are doing, leave this
1174 bool "3G/1G user/kernel split"
1175 config VMSPLIT_3G_OPT
1177 bool "3G/1G user/kernel split (for full 1G low memory)"
1179 bool "2G/2G user/kernel split"
1180 config VMSPLIT_2G_OPT
1182 bool "2G/2G user/kernel split (for full 2G low memory)"
1184 bool "1G/3G user/kernel split"
1189 default 0xB0000000 if VMSPLIT_3G_OPT
1190 default 0x80000000 if VMSPLIT_2G
1191 default 0x78000000 if VMSPLIT_2G_OPT
1192 default 0x40000000 if VMSPLIT_1G
1198 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1201 bool "PAE (Physical Address Extension) Support"
1202 depends on X86_32 && !HIGHMEM4G
1204 PAE is required for NX support, and furthermore enables
1205 larger swapspace support for non-overcommit purposes. It
1206 has the cost of more pagetable lookup overhead, and also
1207 consumes more pagetable space per process.
1209 config ARCH_PHYS_ADDR_T_64BIT
1211 depends on X86_64 || X86_PAE
1213 config ARCH_DMA_ADDR_T_64BIT
1215 depends on X86_64 || HIGHMEM64G
1217 config DIRECT_GBPAGES
1218 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1222 Allow the kernel linear mapping to use 1GB pages on CPUs that
1223 support it. This can improve the kernel's performance a tiny bit by
1224 reducing TLB pressure. If in doubt, say "Y".
1226 # Common NUMA Features
1228 bool "Numa Memory Allocation and Scheduler Support"
1230 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1231 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1233 Enable NUMA (Non Uniform Memory Access) support.
1235 The kernel will try to allocate memory used by a CPU on the
1236 local memory controller of the CPU and add some more
1237 NUMA awareness to the kernel.
1239 For 64-bit this is recommended if the system is Intel Core i7
1240 (or later), AMD Opteron, or EM64T NUMA.
1242 For 32-bit this is only needed on (rare) 32-bit-only platforms
1243 that support NUMA topologies, such as NUMAQ / Summit, or if you
1244 boot a 32-bit kernel on a 64-bit NUMA platform.
1246 Otherwise, you should say N.
1248 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1249 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1253 prompt "Old style AMD Opteron NUMA detection"
1254 depends on X86_64 && NUMA && PCI
1256 Enable AMD NUMA node topology detection. You should say Y here if
1257 you have a multi processor AMD system. This uses an old method to
1258 read the NUMA configuration directly from the builtin Northbridge
1259 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1260 which also takes priority if both are compiled in.
1262 config X86_64_ACPI_NUMA
1264 prompt "ACPI NUMA detection"
1265 depends on X86_64 && NUMA && ACPI && PCI
1268 Enable ACPI SRAT based node topology detection.
1270 # Some NUMA nodes have memory ranges that span
1271 # other nodes. Even though a pfn is valid and
1272 # between a node's start and end pfns, it may not
1273 # reside on that node. See memmap_init_zone()
1275 config NODES_SPAN_OTHER_NODES
1277 depends on X86_64_ACPI_NUMA
1280 bool "NUMA emulation"
1283 Enable NUMA emulation. A flat machine will be split
1284 into virtual nodes when booted with "numa=fake=N", where N is the
1285 number of nodes. This is only useful for debugging.
1288 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1290 default "10" if MAXSMP
1291 default "6" if X86_64
1292 default "4" if X86_NUMAQ
1294 depends on NEED_MULTIPLE_NODES
1296 Specify the maximum number of NUMA Nodes available on the target
1297 system. Increases memory reserved to accommodate various tables.
1299 config ARCH_HAVE_MEMORY_PRESENT
1301 depends on X86_32 && DISCONTIGMEM
1303 config NEED_NODE_MEMMAP_SIZE
1305 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1307 config ARCH_FLATMEM_ENABLE
1309 depends on X86_32 && !NUMA
1311 config ARCH_DISCONTIGMEM_ENABLE
1313 depends on NUMA && X86_32
1315 config ARCH_DISCONTIGMEM_DEFAULT
1317 depends on NUMA && X86_32
1319 config ARCH_SPARSEMEM_ENABLE
1321 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1322 select SPARSEMEM_STATIC if X86_32
1323 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1325 config ARCH_SPARSEMEM_DEFAULT
1329 config ARCH_SELECT_MEMORY_MODEL
1331 depends on ARCH_SPARSEMEM_ENABLE
1333 config ARCH_MEMORY_PROBE
1335 depends on X86_64 && MEMORY_HOTPLUG
1337 config ARCH_PROC_KCORE_TEXT
1339 depends on X86_64 && PROC_KCORE
1341 config ILLEGAL_POINTER_VALUE
1344 default 0xdead000000000000 if X86_64
1349 bool "Allocate 3rd-level pagetables from highmem"
1352 The VM uses one page table entry for each page of physical memory.
1353 For systems with a lot of RAM, this can be wasteful of precious
1354 low memory. Setting this option will put user-space page table
1355 entries in high memory.
1357 config X86_CHECK_BIOS_CORRUPTION
1358 bool "Check for low memory corruption"
1360 Periodically check for memory corruption in low memory, which
1361 is suspected to be caused by BIOS. Even when enabled in the
1362 configuration, it is disabled at runtime. Enable it by
1363 setting "memory_corruption_check=1" on the kernel command
1364 line. By default it scans the low 64k of memory every 60
1365 seconds; see the memory_corruption_check_size and
1366 memory_corruption_check_period parameters in
1367 Documentation/kernel-parameters.txt to adjust this.
1369 When enabled with the default parameters, this option has
1370 almost no overhead, as it reserves a relatively small amount
1371 of memory and scans it infrequently. It both detects corruption
1372 and prevents it from affecting the running system.
1374 It is, however, intended as a diagnostic tool; if repeatable
1375 BIOS-originated corruption always affects the same memory,
1376 you can use memmap= to prevent the kernel from using that
1379 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1380 bool "Set the default setting of memory_corruption_check"
1381 depends on X86_CHECK_BIOS_CORRUPTION
1384 Set whether the default state of memory_corruption_check is
1387 config X86_RESERVE_LOW
1388 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1392 Specify the amount of low memory to reserve for the BIOS.
1394 The first page contains BIOS data structures that the kernel
1395 must not use, so that page must always be reserved.
1397 By default we reserve the first 64K of physical RAM, as a
1398 number of BIOSes are known to corrupt that memory range
1399 during events such as suspend/resume or monitor cable
1400 insertion, so it must not be used by the kernel.
1402 You can set this to 4 if you are absolutely sure that you
1403 trust the BIOS to get all its memory reservations and usages
1404 right. If you know your BIOS have problems beyond the
1405 default 64K area, you can set this to 640 to avoid using the
1406 entire low memory range.
1408 If you have doubts about the BIOS (e.g. suspend/resume does
1409 not work or there's kernel crashes after certain hardware
1410 hotplug events) then you might want to enable
1411 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1412 typical corruption patterns.
1414 Leave this to the default value of 64 if you are unsure.
1416 config MATH_EMULATION
1418 prompt "Math emulation" if X86_32
1420 Linux can emulate a math coprocessor (used for floating point
1421 operations) if you don't have one. 486DX and Pentium processors have
1422 a math coprocessor built in, 486SX and 386 do not, unless you added
1423 a 487DX or 387, respectively. (The messages during boot time can
1424 give you some hints here ["man dmesg"].) Everyone needs either a
1425 coprocessor or this emulation.
1427 If you don't have a math coprocessor, you need to say Y here; if you
1428 say Y here even though you have a coprocessor, the coprocessor will
1429 be used nevertheless. (This behavior can be changed with the kernel
1430 command line option "no387", which comes handy if your coprocessor
1431 is broken. Try "man bootparam" or see the documentation of your boot
1432 loader (lilo or loadlin) about how to pass options to the kernel at
1433 boot time.) This means that it is a good idea to say Y here if you
1434 intend to use this kernel on different machines.
1436 More information about the internals of the Linux math coprocessor
1437 emulation can be found in <file:arch/x86/math-emu/README>.
1439 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1440 kernel, it won't hurt.
1444 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1446 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1447 the Memory Type Range Registers (MTRRs) may be used to control
1448 processor access to memory ranges. This is most useful if you have
1449 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1450 allows bus write transfers to be combined into a larger transfer
1451 before bursting over the PCI/AGP bus. This can increase performance
1452 of image write operations 2.5 times or more. Saying Y here creates a
1453 /proc/mtrr file which may be used to manipulate your processor's
1454 MTRRs. Typically the X server should use this.
1456 This code has a reasonably generic interface so that similar
1457 control registers on other processors can be easily supported
1460 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1461 Registers (ARRs) which provide a similar functionality to MTRRs. For
1462 these, the ARRs are used to emulate the MTRRs.
1463 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1464 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1465 write-combining. All of these processors are supported by this code
1466 and it makes sense to say Y here if you have one of them.
1468 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1469 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1470 can lead to all sorts of problems, so it's good to say Y here.
1472 You can safely say Y even if your machine doesn't have MTRRs, you'll
1473 just add about 9 KB to your kernel.
1475 See <file:Documentation/x86/mtrr.txt> for more information.
1477 config MTRR_SANITIZER
1479 prompt "MTRR cleanup support"
1482 Convert MTRR layout from continuous to discrete, so X drivers can
1483 add writeback entries.
1485 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1486 The largest mtrr entry size for a continuous block can be set with
1491 config MTRR_SANITIZER_ENABLE_DEFAULT
1492 int "MTRR cleanup enable value (0-1)"
1495 depends on MTRR_SANITIZER
1497 Enable mtrr cleanup default value
1499 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1500 int "MTRR cleanup spare reg num (0-7)"
1503 depends on MTRR_SANITIZER
1505 mtrr cleanup spare entries default, it can be changed via
1506 mtrr_spare_reg_nr=N on the kernel command line.
1510 prompt "x86 PAT support" if EXPERT
1513 Use PAT attributes to setup page level cache control.
1515 PATs are the modern equivalents of MTRRs and are much more
1516 flexible than MTRRs.
1518 Say N here if you see bootup problems (boot crash, boot hang,
1519 spontaneous reboots) or a non-working video driver.
1523 config ARCH_USES_PG_UNCACHED
1529 prompt "x86 architectural random number generator" if EXPERT
1531 Enable the x86 architectural RDRAND instruction
1532 (Intel Bull Mountain technology) to generate random numbers.
1533 If supported, this is a high bandwidth, cryptographically
1534 secure hardware random number generator.
1538 prompt "Supervisor Mode Access Prevention" if EXPERT
1540 Supervisor Mode Access Prevention (SMAP) is a security
1541 feature in newer Intel processors. There is a small
1542 performance cost if this enabled and turned on; there is
1543 also a small increase in the kernel size if this is enabled.
1548 bool "EFI runtime service support"
1551 This enables the kernel to use EFI runtime services that are
1552 available (such as the EFI variable services).
1554 This option is only useful on systems that have EFI firmware.
1555 In addition, you should use the latest ELILO loader available
1556 at <http://elilo.sourceforge.net> in order to take advantage
1557 of EFI runtime services. However, even with this option, the
1558 resultant kernel should continue to boot on existing non-EFI
1562 bool "EFI stub support"
1565 This kernel feature allows a bzImage to be loaded directly
1566 by EFI firmware without the use of a bootloader.
1568 See Documentation/x86/efi-stub.txt for more information.
1572 prompt "Enable seccomp to safely compute untrusted bytecode"
1574 This kernel feature is useful for number crunching applications
1575 that may need to compute untrusted bytecode during their
1576 execution. By using pipes or other transports made available to
1577 the process as file descriptors supporting the read/write
1578 syscalls, it's possible to isolate those applications in
1579 their own address space using seccomp. Once seccomp is
1580 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1581 and the task is only allowed to execute a few safe syscalls
1582 defined by each seccomp mode.
1584 If unsure, say Y. Only embedded should say N here.
1586 config CC_STACKPROTECTOR
1587 bool "Enable -fstack-protector buffer overflow detection"
1589 This option turns on the -fstack-protector GCC feature. This
1590 feature puts, at the beginning of functions, a canary value on
1591 the stack just before the return address, and validates
1592 the value just before actually returning. Stack based buffer
1593 overflows (that need to overwrite this return address) now also
1594 overwrite the canary, which gets detected and the attack is then
1595 neutralized via a kernel panic.
1597 This feature requires gcc version 4.2 or above, or a distribution
1598 gcc with the feature backported. Older versions are automatically
1599 detected and for those versions, this configuration option is
1600 ignored. (and a warning is printed during bootup)
1602 source kernel/Kconfig.hz
1605 bool "kexec system call"
1607 kexec is a system call that implements the ability to shutdown your
1608 current kernel, and to start another kernel. It is like a reboot
1609 but it is independent of the system firmware. And like a reboot
1610 you can start any kernel with it, not just Linux.
1612 The name comes from the similarity to the exec system call.
1614 It is an ongoing process to be certain the hardware in a machine
1615 is properly shutdown, so do not be surprised if this code does not
1616 initially work for you. It may help to enable device hotplugging
1617 support. As of this writing the exact hardware interface is
1618 strongly in flux, so no good recommendation can be made.
1621 bool "kernel crash dumps"
1622 depends on X86_64 || (X86_32 && HIGHMEM)
1624 Generate crash dump after being started by kexec.
1625 This should be normally only set in special crash dump kernels
1626 which are loaded in the main kernel with kexec-tools into
1627 a specially reserved region and then later executed after
1628 a crash by kdump/kexec. The crash dump kernel must be compiled
1629 to a memory address not used by the main kernel or BIOS using
1630 PHYSICAL_START, or it must be built as a relocatable image
1631 (CONFIG_RELOCATABLE=y).
1632 For more details see Documentation/kdump/kdump.txt
1636 depends on KEXEC && HIBERNATION
1638 Jump between original kernel and kexeced kernel and invoke
1639 code in physical address mode via KEXEC
1641 config PHYSICAL_START
1642 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1645 This gives the physical address where the kernel is loaded.
1647 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1648 bzImage will decompress itself to above physical address and
1649 run from there. Otherwise, bzImage will run from the address where
1650 it has been loaded by the boot loader and will ignore above physical
1653 In normal kdump cases one does not have to set/change this option
1654 as now bzImage can be compiled as a completely relocatable image
1655 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1656 address. This option is mainly useful for the folks who don't want
1657 to use a bzImage for capturing the crash dump and want to use a
1658 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1659 to be specifically compiled to run from a specific memory area
1660 (normally a reserved region) and this option comes handy.
1662 So if you are using bzImage for capturing the crash dump,
1663 leave the value here unchanged to 0x1000000 and set
1664 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1665 for capturing the crash dump change this value to start of
1666 the reserved region. In other words, it can be set based on
1667 the "X" value as specified in the "crashkernel=YM@XM"
1668 command line boot parameter passed to the panic-ed
1669 kernel. Please take a look at Documentation/kdump/kdump.txt
1670 for more details about crash dumps.
1672 Usage of bzImage for capturing the crash dump is recommended as
1673 one does not have to build two kernels. Same kernel can be used
1674 as production kernel and capture kernel. Above option should have
1675 gone away after relocatable bzImage support is introduced. But it
1676 is present because there are users out there who continue to use
1677 vmlinux for dump capture. This option should go away down the
1680 Don't change this unless you know what you are doing.
1683 bool "Build a relocatable kernel"
1686 This builds a kernel image that retains relocation information
1687 so it can be loaded someplace besides the default 1MB.
1688 The relocations tend to make the kernel binary about 10% larger,
1689 but are discarded at runtime.
1691 One use is for the kexec on panic case where the recovery kernel
1692 must live at a different physical address than the primary
1695 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1696 it has been loaded at and the compile time physical address
1697 (CONFIG_PHYSICAL_START) is ignored.
1699 # Relocation on x86-32 needs some additional build support
1700 config X86_NEED_RELOCS
1702 depends on X86_32 && RELOCATABLE
1704 config PHYSICAL_ALIGN
1705 hex "Alignment value to which kernel should be aligned" if X86_32
1707 range 0x2000 0x1000000
1709 This value puts the alignment restrictions on physical address
1710 where kernel is loaded and run from. Kernel is compiled for an
1711 address which meets above alignment restriction.
1713 If bootloader loads the kernel at a non-aligned address and
1714 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1715 address aligned to above value and run from there.
1717 If bootloader loads the kernel at a non-aligned address and
1718 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1719 load address and decompress itself to the address it has been
1720 compiled for and run from there. The address for which kernel is
1721 compiled already meets above alignment restrictions. Hence the
1722 end result is that kernel runs from a physical address meeting
1723 above alignment restrictions.
1725 Don't change this unless you know what you are doing.
1728 bool "Support for hot-pluggable CPUs"
1729 depends on SMP && HOTPLUG
1731 Say Y here to allow turning CPUs off and on. CPUs can be
1732 controlled through /sys/devices/system/cpu.
1733 ( Note: power management support will enable this option
1734 automatically on SMP systems. )
1735 Say N if you want to disable CPU hotplug.
1737 config BOOTPARAM_HOTPLUG_CPU0
1738 bool "Set default setting of cpu0_hotpluggable"
1740 depends on HOTPLUG_CPU
1742 Set whether default state of cpu0_hotpluggable is on or off.
1744 Say Y here to enable CPU0 hotplug by default. If this switch
1745 is turned on, there is no need to give cpu0_hotplug kernel
1746 parameter and the CPU0 hotplug feature is enabled by default.
1748 Please note: there are two known CPU0 dependencies if you want
1749 to enable the CPU0 hotplug feature either by this switch or by
1750 cpu0_hotplug kernel parameter.
1752 First, resume from hibernate or suspend always starts from CPU0.
1753 So hibernate and suspend are prevented if CPU0 is offline.
1755 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1756 offline if any interrupt can not migrate out of CPU0. There may
1757 be other CPU0 dependencies.
1759 Please make sure the dependencies are under your control before
1760 you enable this feature.
1762 Say N if you don't want to enable CPU0 hotplug feature by default.
1763 You still can enable the CPU0 hotplug feature at boot by kernel
1764 parameter cpu0_hotplug.
1766 config DEBUG_HOTPLUG_CPU0
1768 prompt "Debug CPU0 hotplug"
1769 depends on HOTPLUG_CPU
1771 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1772 soon as possible and boots up userspace with CPU0 offlined. User
1773 can online CPU0 back after boot time.
1775 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1776 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1777 compilation or giving cpu0_hotplug kernel parameter at boot.
1783 prompt "Compat VDSO support"
1784 depends on X86_32 || IA32_EMULATION
1786 Map the 32-bit VDSO to the predictable old-style address too.
1788 Say N here if you are running a sufficiently recent glibc
1789 version (2.3.3 or later), to remove the high-mapped
1790 VDSO mapping and to exclusively use the randomized VDSO.
1795 bool "Built-in kernel command line"
1797 Allow for specifying boot arguments to the kernel at
1798 build time. On some systems (e.g. embedded ones), it is
1799 necessary or convenient to provide some or all of the
1800 kernel boot arguments with the kernel itself (that is,
1801 to not rely on the boot loader to provide them.)
1803 To compile command line arguments into the kernel,
1804 set this option to 'Y', then fill in the
1805 the boot arguments in CONFIG_CMDLINE.
1807 Systems with fully functional boot loaders (i.e. non-embedded)
1808 should leave this option set to 'N'.
1811 string "Built-in kernel command string"
1812 depends on CMDLINE_BOOL
1815 Enter arguments here that should be compiled into the kernel
1816 image and used at boot time. If the boot loader provides a
1817 command line at boot time, it is appended to this string to
1818 form the full kernel command line, when the system boots.
1820 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1821 change this behavior.
1823 In most cases, the command line (whether built-in or provided
1824 by the boot loader) should specify the device for the root
1827 config CMDLINE_OVERRIDE
1828 bool "Built-in command line overrides boot loader arguments"
1829 depends on CMDLINE_BOOL
1831 Set this option to 'Y' to have the kernel ignore the boot loader
1832 command line, and use ONLY the built-in command line.
1834 This is used to work around broken boot loaders. This should
1835 be set to 'N' under normal conditions.
1839 config ARCH_ENABLE_MEMORY_HOTPLUG
1841 depends on X86_64 || (X86_32 && HIGHMEM)
1843 config ARCH_ENABLE_MEMORY_HOTREMOVE
1845 depends on MEMORY_HOTPLUG
1847 config USE_PERCPU_NUMA_NODE_ID
1851 menu "Power management and ACPI options"
1853 config ARCH_HIBERNATION_HEADER
1855 depends on X86_64 && HIBERNATION
1857 source "kernel/power/Kconfig"
1859 source "drivers/acpi/Kconfig"
1861 source "drivers/sfi/Kconfig"
1868 tristate "APM (Advanced Power Management) BIOS support"
1869 depends on X86_32 && PM_SLEEP
1871 APM is a BIOS specification for saving power using several different
1872 techniques. This is mostly useful for battery powered laptops with
1873 APM compliant BIOSes. If you say Y here, the system time will be
1874 reset after a RESUME operation, the /proc/apm device will provide
1875 battery status information, and user-space programs will receive
1876 notification of APM "events" (e.g. battery status change).
1878 If you select "Y" here, you can disable actual use of the APM
1879 BIOS by passing the "apm=off" option to the kernel at boot time.
1881 Note that the APM support is almost completely disabled for
1882 machines with more than one CPU.
1884 In order to use APM, you will need supporting software. For location
1885 and more information, read <file:Documentation/power/apm-acpi.txt>
1886 and the Battery Powered Linux mini-HOWTO, available from
1887 <http://www.tldp.org/docs.html#howto>.
1889 This driver does not spin down disk drives (see the hdparm(8)
1890 manpage ("man 8 hdparm") for that), and it doesn't turn off
1891 VESA-compliant "green" monitors.
1893 This driver does not support the TI 4000M TravelMate and the ACER
1894 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1895 desktop machines also don't have compliant BIOSes, and this driver
1896 may cause those machines to panic during the boot phase.
1898 Generally, if you don't have a battery in your machine, there isn't
1899 much point in using this driver and you should say N. If you get
1900 random kernel OOPSes or reboots that don't seem to be related to
1901 anything, try disabling/enabling this option (or disabling/enabling
1904 Some other things you should try when experiencing seemingly random,
1907 1) make sure that you have enough swap space and that it is
1909 2) pass the "no-hlt" option to the kernel
1910 3) switch on floating point emulation in the kernel and pass
1911 the "no387" option to the kernel
1912 4) pass the "floppy=nodma" option to the kernel
1913 5) pass the "mem=4M" option to the kernel (thereby disabling
1914 all but the first 4 MB of RAM)
1915 6) make sure that the CPU is not over clocked.
1916 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1917 8) disable the cache from your BIOS settings
1918 9) install a fan for the video card or exchange video RAM
1919 10) install a better fan for the CPU
1920 11) exchange RAM chips
1921 12) exchange the motherboard.
1923 To compile this driver as a module, choose M here: the
1924 module will be called apm.
1928 config APM_IGNORE_USER_SUSPEND
1929 bool "Ignore USER SUSPEND"
1931 This option will ignore USER SUSPEND requests. On machines with a
1932 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1933 series notebooks, it is necessary to say Y because of a BIOS bug.
1935 config APM_DO_ENABLE
1936 bool "Enable PM at boot time"
1938 Enable APM features at boot time. From page 36 of the APM BIOS
1939 specification: "When disabled, the APM BIOS does not automatically
1940 power manage devices, enter the Standby State, enter the Suspend
1941 State, or take power saving steps in response to CPU Idle calls."
1942 This driver will make CPU Idle calls when Linux is idle (unless this
1943 feature is turned off -- see "Do CPU IDLE calls", below). This
1944 should always save battery power, but more complicated APM features
1945 will be dependent on your BIOS implementation. You may need to turn
1946 this option off if your computer hangs at boot time when using APM
1947 support, or if it beeps continuously instead of suspending. Turn
1948 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1949 T400CDT. This is off by default since most machines do fine without
1954 bool "Make CPU Idle calls when idle"
1956 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1957 On some machines, this can activate improved power savings, such as
1958 a slowed CPU clock rate, when the machine is idle. These idle calls
1959 are made after the idle loop has run for some length of time (e.g.,
1960 333 mS). On some machines, this will cause a hang at boot time or
1961 whenever the CPU becomes idle. (On machines with more than one CPU,
1962 this option does nothing.)
1964 config APM_DISPLAY_BLANK
1965 bool "Enable console blanking using APM"
1967 Enable console blanking using the APM. Some laptops can use this to
1968 turn off the LCD backlight when the screen blanker of the Linux
1969 virtual console blanks the screen. Note that this is only used by
1970 the virtual console screen blanker, and won't turn off the backlight
1971 when using the X Window system. This also doesn't have anything to
1972 do with your VESA-compliant power-saving monitor. Further, this
1973 option doesn't work for all laptops -- it might not turn off your
1974 backlight at all, or it might print a lot of errors to the console,
1975 especially if you are using gpm.
1977 config APM_ALLOW_INTS
1978 bool "Allow interrupts during APM BIOS calls"
1980 Normally we disable external interrupts while we are making calls to
1981 the APM BIOS as a measure to lessen the effects of a badly behaving
1982 BIOS implementation. The BIOS should reenable interrupts if it
1983 needs to. Unfortunately, some BIOSes do not -- especially those in
1984 many of the newer IBM Thinkpads. If you experience hangs when you
1985 suspend, try setting this to Y. Otherwise, say N.
1989 source "drivers/cpufreq/Kconfig"
1991 source "drivers/cpuidle/Kconfig"
1993 source "drivers/idle/Kconfig"
1998 menu "Bus options (PCI etc.)"
2003 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2005 Find out whether you have a PCI motherboard. PCI is the name of a
2006 bus system, i.e. the way the CPU talks to the other stuff inside
2007 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2008 VESA. If you have PCI, say Y, otherwise N.
2011 prompt "PCI access mode"
2012 depends on X86_32 && PCI
2015 On PCI systems, the BIOS can be used to detect the PCI devices and
2016 determine their configuration. However, some old PCI motherboards
2017 have BIOS bugs and may crash if this is done. Also, some embedded
2018 PCI-based systems don't have any BIOS at all. Linux can also try to
2019 detect the PCI hardware directly without using the BIOS.
2021 With this option, you can specify how Linux should detect the
2022 PCI devices. If you choose "BIOS", the BIOS will be used,
2023 if you choose "Direct", the BIOS won't be used, and if you
2024 choose "MMConfig", then PCI Express MMCONFIG will be used.
2025 If you choose "Any", the kernel will try MMCONFIG, then the
2026 direct access method and falls back to the BIOS if that doesn't
2027 work. If unsure, go with the default, which is "Any".
2032 config PCI_GOMMCONFIG
2049 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2051 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2054 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2058 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2062 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2066 depends on PCI && XEN
2074 bool "Support mmconfig PCI config space access"
2075 depends on X86_64 && PCI && ACPI
2077 config PCI_CNB20LE_QUIRK
2078 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2081 Read the PCI windows out of the CNB20LE host bridge. This allows
2082 PCI hotplug to work on systems with the CNB20LE chipset which do
2085 There's no public spec for this chipset, and this functionality
2086 is known to be incomplete.
2088 You should say N unless you know you need this.
2090 source "drivers/pci/pcie/Kconfig"
2092 source "drivers/pci/Kconfig"
2094 # x86_64 have no ISA slots, but can have ISA-style DMA.
2096 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2099 Enables ISA-style DMA support for devices requiring such controllers.
2107 Find out whether you have ISA slots on your motherboard. ISA is the
2108 name of a bus system, i.e. the way the CPU talks to the other stuff
2109 inside your box. Other bus systems are PCI, EISA, MicroChannel
2110 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2111 newer boards don't support it. If you have ISA, say Y, otherwise N.
2117 The Extended Industry Standard Architecture (EISA) bus was
2118 developed as an open alternative to the IBM MicroChannel bus.
2120 The EISA bus provided some of the features of the IBM MicroChannel
2121 bus while maintaining backward compatibility with cards made for
2122 the older ISA bus. The EISA bus saw limited use between 1988 and
2123 1995 when it was made obsolete by the PCI bus.
2125 Say Y here if you are building a kernel for an EISA-based machine.
2129 source "drivers/eisa/Kconfig"
2132 tristate "NatSemi SCx200 support"
2134 This provides basic support for National Semiconductor's
2135 (now AMD's) Geode processors. The driver probes for the
2136 PCI-IDs of several on-chip devices, so its a good dependency
2137 for other scx200_* drivers.
2139 If compiled as a module, the driver is named scx200.
2141 config SCx200HR_TIMER
2142 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2146 This driver provides a clocksource built upon the on-chip
2147 27MHz high-resolution timer. Its also a workaround for
2148 NSC Geode SC-1100's buggy TSC, which loses time when the
2149 processor goes idle (as is done by the scheduler). The
2150 other workaround is idle=poll boot option.
2153 bool "One Laptop Per Child support"
2160 Add support for detecting the unique features of the OLPC
2164 bool "OLPC XO-1 Power Management"
2165 depends on OLPC && MFD_CS5535 && PM_SLEEP
2168 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2171 bool "OLPC XO-1 Real Time Clock"
2172 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2174 Add support for the XO-1 real time clock, which can be used as a
2175 programmable wakeup source.
2178 bool "OLPC XO-1 SCI extras"
2179 depends on OLPC && OLPC_XO1_PM
2185 Add support for SCI-based features of the OLPC XO-1 laptop:
2186 - EC-driven system wakeups
2190 - AC adapter status updates
2191 - Battery status updates
2193 config OLPC_XO15_SCI
2194 bool "OLPC XO-1.5 SCI extras"
2195 depends on OLPC && ACPI
2198 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2199 - EC-driven system wakeups
2200 - AC adapter status updates
2201 - Battery status updates
2204 bool "PCEngines ALIX System Support (LED setup)"
2207 This option enables system support for the PCEngines ALIX.
2208 At present this just sets up LEDs for GPIO control on
2209 ALIX2/3/6 boards. However, other system specific setup should
2212 Note: You must still enable the drivers for GPIO and LED support
2213 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2215 Note: You have to set alix.force=1 for boards with Award BIOS.
2218 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2221 This option enables system support for the Soekris Engineering net5501.
2224 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2228 This option enables system support for the Traverse Technologies GEOS.
2231 bool "Technologic Systems TS-5500 platform support"
2233 select CHECK_SIGNATURE
2237 This option enables system support for the Technologic Systems TS-5500.
2243 depends on CPU_SUP_AMD && PCI
2245 source "drivers/pcmcia/Kconfig"
2247 source "drivers/pci/hotplug/Kconfig"
2250 bool "RapidIO support"
2254 If you say Y here, the kernel will include drivers and
2255 infrastructure code to support RapidIO interconnect devices.
2257 source "drivers/rapidio/Kconfig"
2262 menu "Executable file formats / Emulations"
2264 source "fs/Kconfig.binfmt"
2266 config IA32_EMULATION
2267 bool "IA32 Emulation"
2269 select COMPAT_BINFMT_ELF
2272 Include code to run legacy 32-bit programs under a
2273 64-bit kernel. You should likely turn this on, unless you're
2274 100% sure that you don't have any 32-bit programs left.
2277 tristate "IA32 a.out support"
2278 depends on IA32_EMULATION
2280 Support old a.out binaries in the 32bit emulation.
2283 bool "x32 ABI for 64-bit mode"
2284 depends on X86_64 && IA32_EMULATION
2286 Include code to run binaries for the x32 native 32-bit ABI
2287 for 64-bit processors. An x32 process gets access to the
2288 full 64-bit register file and wide data path while leaving
2289 pointers at 32 bits for smaller memory footprint.
2291 You will need a recent binutils (2.22 or later) with
2292 elf32_x86_64 support enabled to compile a kernel with this
2297 depends on IA32_EMULATION || X86_X32
2298 select ARCH_WANT_OLD_COMPAT_IPC
2301 config COMPAT_FOR_U64_ALIGNMENT
2304 config SYSVIPC_COMPAT
2316 config HAVE_ATOMIC_IOMAP
2320 config HAVE_TEXT_POKE_SMP
2322 select STOP_MACHINE if SMP
2324 config X86_DEV_DMA_OPS
2326 depends on X86_64 || STA2X11
2328 config X86_DMA_REMAP
2332 source "net/Kconfig"
2334 source "drivers/Kconfig"
2336 source "drivers/firmware/Kconfig"
2340 source "arch/x86/Kconfig.debug"
2342 source "security/Kconfig"
2344 source "crypto/Kconfig"
2346 source "arch/x86/kvm/Kconfig"
2348 source "lib/Kconfig"