3 bool "64-bit kernel" if ARCH = "x86"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
18 select X86_DEV_DMA_OPS
23 select HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
25 select ARCH_SUPPORTS_NUMA_BALANCING
26 select ARCH_WANTS_PROT_NUMA_PROT_NONE
29 select HAVE_PCSPKR_PLATFORM
30 select HAVE_PERF_EVENTS
31 select HAVE_IOREMAP_PROT
34 select HAVE_MEMBLOCK_NODE_MAP
35 select ARCH_DISCARD_MEMBLOCK
36 select ARCH_WANT_OPTIONAL_GPIOLIB
37 select ARCH_WANT_FRAME_POINTERS
39 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
40 select HAVE_KRETPROBES
42 select HAVE_KPROBES_ON_FTRACE
43 select HAVE_FTRACE_MCOUNT_RECORD
44 select HAVE_FENTRY if X86_64
45 select HAVE_C_RECORDMCOUNT
46 select HAVE_DYNAMIC_FTRACE
47 select HAVE_DYNAMIC_FTRACE_WITH_REGS
48 select HAVE_FUNCTION_TRACER
49 select HAVE_FUNCTION_GRAPH_TRACER
50 select HAVE_FUNCTION_GRAPH_FP_TEST
51 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
52 select HAVE_SYSCALL_TRACEPOINTS
53 select SYSCTL_EXCEPTION_TRACE
56 select HAVE_ARCH_TRACEHOOK
57 select HAVE_GENERIC_DMA_COHERENT if X86_32
58 select HAVE_EFFICIENT_UNALIGNED_ACCESS
59 select USER_STACKTRACE_SUPPORT
60 select HAVE_REGS_AND_STACK_ACCESS_API
61 select HAVE_DMA_API_DEBUG
62 select HAVE_KERNEL_GZIP
63 select HAVE_KERNEL_BZIP2
64 select HAVE_KERNEL_LZMA
66 select HAVE_KERNEL_LZO
67 select HAVE_HW_BREAKPOINT
68 select HAVE_MIXED_BREAKPOINTS_REGS
70 select HAVE_PERF_EVENTS_NMI
72 select HAVE_PERF_USER_STACK_DUMP
73 select HAVE_DEBUG_KMEMLEAK
75 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
76 select HAVE_CMPXCHG_LOCAL
77 select HAVE_CMPXCHG_DOUBLE
78 select HAVE_ARCH_KMEMCHECK
79 select HAVE_USER_RETURN_NOTIFIER
80 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
81 select HAVE_ARCH_JUMP_LABEL
82 select HAVE_TEXT_POKE_SMP
83 select HAVE_GENERIC_HARDIRQS
84 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
86 select GENERIC_FIND_FIRST_BIT
87 select GENERIC_IRQ_PROBE
88 select GENERIC_PENDING_IRQ if SMP
89 select GENERIC_IRQ_SHOW
90 select GENERIC_CLOCKEVENTS_MIN_ADJUST
91 select IRQ_FORCED_THREADING
92 select USE_GENERIC_SMP_HELPERS if SMP
93 select HAVE_BPF_JIT if X86_64
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
96 select ARCH_HAVE_NMI_SAFE_CMPXCHG
98 select DCACHE_WORD_ACCESS
99 select GENERIC_SMP_IDLE_THREAD
100 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
101 select HAVE_ARCH_SECCOMP_FILTER
102 select BUILDTIME_EXTABLE_SORT
103 select GENERIC_CMOS_UPDATE
104 select CLOCKSOURCE_WATCHDOG
105 select GENERIC_CLOCKEVENTS
106 select ARCH_CLOCKSOURCE_DATA if X86_64
107 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
108 select GENERIC_TIME_VSYSCALL if X86_64
109 select KTIME_SCALAR if X86_32
110 select ALWAYS_USE_PERSISTENT_CLOCK
111 select GENERIC_STRNCPY_FROM_USER
112 select GENERIC_STRNLEN_USER
113 select HAVE_CONTEXT_TRACKING if X86_64
114 select HAVE_IRQ_TIME_ACCOUNTING
116 select MODULES_USE_ELF_REL if X86_32
117 select MODULES_USE_ELF_RELA if X86_64
118 select CLONE_BACKWARDS if X86_32
119 select ARCH_USE_BUILTIN_BSWAP
120 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
121 select OLD_SIGACTION if X86_32
122 select COMPAT_OLD_SIGACTION if IA32_EMULATION
124 config INSTRUCTION_DECODER
126 depends on KPROBES || PERF_EVENTS || UPROBES
130 default "elf32-i386" if X86_32
131 default "elf64-x86-64" if X86_64
133 config ARCH_DEFCONFIG
135 default "arch/x86/configs/i386_defconfig" if X86_32
136 default "arch/x86/configs/x86_64_defconfig" if X86_64
138 config LOCKDEP_SUPPORT
141 config STACKTRACE_SUPPORT
144 config HAVE_LATENCYTOP_SUPPORT
153 config NEED_DMA_MAP_STATE
155 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
157 config NEED_SG_DMA_LENGTH
160 config GENERIC_ISA_DMA
162 depends on ISA_DMA_API
167 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
169 config GENERIC_BUG_RELATIVE_POINTERS
172 config GENERIC_HWEIGHT
175 config ARCH_MAY_HAVE_PC_FDC
177 depends on ISA_DMA_API
179 config RWSEM_XCHGADD_ALGORITHM
182 config GENERIC_CALIBRATE_DELAY
185 config ARCH_HAS_CPU_RELAX
188 config ARCH_HAS_DEFAULT_IDLE
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
220 config ARCH_SUPPORTS_OPTIMIZED_INLINING
223 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
226 config HAVE_INTEL_TXT
228 depends on INTEL_IOMMU && ACPI
232 depends on X86_32 && SMP
236 depends on X86_64 && SMP
242 config X86_32_LAZY_GS
244 depends on X86_32 && !CC_STACKPROTECTOR
246 config ARCH_HWEIGHT_CFLAGS
248 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
249 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
251 config ARCH_CPU_PROBE_RELEASE
253 depends on HOTPLUG_CPU
255 config ARCH_SUPPORTS_UPROBES
258 source "init/Kconfig"
259 source "kernel/Kconfig.freezer"
261 menu "Processor type and features"
264 bool "DMA memory allocation support" if EXPERT
267 DMA memory allocation support allows devices with less than 32-bit
268 addressing to allocate within the first 16MB of address space.
269 Disable if no such devices will be used.
274 bool "Symmetric multi-processing support"
276 This enables support for systems with more than one CPU. If you have
277 a system with only one CPU, like most personal computers, say N. If
278 you have a system with more than one CPU, say Y.
280 If you say N here, the kernel will run on single and multiprocessor
281 machines, but will use only one CPU of a multiprocessor machine. If
282 you say Y here, the kernel will run on many, but not all,
283 singleprocessor machines. On a singleprocessor machine, the kernel
284 will run faster if you say N here.
286 Note that if you say Y here and choose architecture "586" or
287 "Pentium" under "Processor family", the kernel will not work on 486
288 architectures. Similarly, multiprocessor kernels for the "PPro"
289 architecture may not work on all Pentium based boards.
291 People using multiprocessor machines who say Y here should also say
292 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
293 Management" code will be disabled if you say Y here.
295 See also <file:Documentation/x86/i386/IO-APIC.txt>,
296 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
297 <http://www.tldp.org/docs.html#howto>.
299 If you don't know what to do here, say N.
302 bool "Support x2apic"
303 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
305 This enables x2apic support on CPUs that have this feature.
307 This allows 32-bit apic IDs (so it can support very large systems),
308 and accesses the local apic via MSRs not via mmio.
310 If you don't know what to do here, say N.
313 bool "Enable MPS table" if ACPI || SFI
315 depends on X86_LOCAL_APIC
317 For old smp systems that do not have proper acpi support. Newer systems
318 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
321 bool "Support for big SMP systems with more than 8 CPUs"
322 depends on X86_32 && SMP
324 This option is needed for the systems that have more than 8 CPUs
328 depends on X86_GOLDFISH
331 config X86_EXTENDED_PLATFORM
332 bool "Support for extended (non-PC) x86 platforms"
335 If you disable this option then the kernel will only support
336 standard PC platforms. (which covers the vast majority of
339 If you enable this option then you'll be able to select support
340 for the following (non-PC) 32 bit x86 platforms:
344 SGI 320/540 (Visual Workstation)
345 STA2X11-based (e.g. Northville)
346 Summit/EXA (IBM x440)
347 Unisys ES7000 IA32 series
348 Moorestown MID devices
350 If you have one of these systems, or if you want to build a
351 generic distribution kernel, say Y here - otherwise say N.
355 config X86_EXTENDED_PLATFORM
356 bool "Support for extended (non-PC) x86 platforms"
359 If you disable this option then the kernel will only support
360 standard PC platforms. (which covers the vast majority of
363 If you enable this option then you'll be able to select support
364 for the following (non-PC) 64 bit x86 platforms:
369 If you have one of these systems, or if you want to build a
370 generic distribution kernel, say Y here - otherwise say N.
372 # This is an alphabetically sorted list of 64 bit extended platforms
373 # Please maintain the alphabetic order if and when there are additions
375 bool "Numascale NumaChip"
377 depends on X86_EXTENDED_PLATFORM
380 depends on X86_X2APIC
381 depends on PCI_MMCONFIG
383 Adds support for Numascale NumaChip large-SMP systems. Needed to
384 enable more than ~168 cores.
385 If you don't have one of these, you should say N here.
389 select PARAVIRT_GUEST
391 depends on X86_64 && PCI
392 depends on X86_EXTENDED_PLATFORM
395 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
396 supposed to run on these EM64T-based machines. Only choose this option
397 if you have one of these machines.
400 bool "SGI Ultraviolet"
402 depends on X86_EXTENDED_PLATFORM
404 depends on X86_X2APIC
406 This option is needed in order to support SGI Ultraviolet systems.
407 If you don't have one of these, you should say N here.
409 # Following is an alphabetically sorted list of 32 bit extended platforms
410 # Please maintain the alphabetic order if and when there are additions
413 bool "Goldfish (Virtual Platform)"
416 Enable support for the Goldfish virtual platform used primarily
417 for Android development. Unless you are building for the Android
418 Goldfish emulator say N here.
421 bool "CE4100 TV platform"
423 depends on PCI_GODIRECT
425 depends on X86_EXTENDED_PLATFORM
426 select X86_REBOOTFIXUPS
428 select OF_EARLY_FLATTREE
431 Select for the Intel CE media processor (CE4100) SOC.
432 This option compiles in support for the CE4100 SOC for settop
433 boxes and media devices.
435 config X86_WANT_INTEL_MID
436 bool "Intel MID platform support"
438 depends on X86_EXTENDED_PLATFORM
440 Select to build a kernel capable of supporting Intel MID platform
441 systems which do not have the PCI legacy interfaces (Moorestown,
442 Medfield). If you are building for a PC class system say N here.
444 if X86_WANT_INTEL_MID
450 bool "Medfield MID platform"
453 depends on X86_IO_APIC
461 select X86_PLATFORM_DEVICES
462 select MFD_INTEL_MSIC
464 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
465 Internet Device(MID) platform.
466 Unlike standard x86 PCs, Medfield does not have many legacy devices
467 nor standard legacy replacement devices/features. e.g. Medfield does
468 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
472 config X86_INTEL_LPSS
473 bool "Intel Low Power Subsystem Support"
477 Select to build support for Intel Low Power Subsystem such as
478 found on Intel Lynxpoint PCH. Selecting this option enables
479 things like clock tree (common clock framework) which are needed
480 by the LPSS peripheral drivers.
483 bool "RDC R-321x SoC"
485 depends on X86_EXTENDED_PLATFORM
487 select X86_REBOOTFIXUPS
489 This option is needed for RDC R-321x system-on-chip, also known
491 If you don't have one of these chips, you should say N here.
493 config X86_32_NON_STANDARD
494 bool "Support non-standard 32-bit SMP architectures"
495 depends on X86_32 && SMP
496 depends on X86_EXTENDED_PLATFORM
498 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
499 STA2X11, default subarchitectures. It is intended for a generic
500 binary kernel. If you select them all, kernel will probe it
501 one by one and will fallback to default.
503 # Alphabetically sorted list of Non standard 32 bit platforms
506 bool "NUMAQ (IBM/Sequent)"
507 depends on X86_32_NON_STANDARD
512 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
513 NUMA multiquad box. This changes the way that processors are
514 bootstrapped, and uses Clustered Logical APIC addressing mode instead
515 of Flat Logical. You will need a new lynxer.elf file to flash your
516 firmware with - send email to <Martin.Bligh@us.ibm.com>.
518 config X86_SUPPORTS_MEMORY_FAILURE
520 # MCE code calls memory_failure():
522 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
523 depends on !X86_NUMAQ
524 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
525 depends on X86_64 || !SPARSEMEM
526 select ARCH_SUPPORTS_MEMORY_FAILURE
529 bool "SGI 320/540 (Visual Workstation)"
530 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
531 depends on X86_32_NON_STANDARD
533 The SGI Visual Workstation series is an IA32-based workstation
534 based on SGI systems chips with some legacy PC hardware attached.
536 Say Y here to create a kernel to run on the SGI 320 or 540.
538 A kernel compiled for the Visual Workstation will run on general
539 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
542 bool "STA2X11 Companion Chip Support"
543 depends on X86_32_NON_STANDARD && PCI
544 select X86_DEV_DMA_OPS
548 select ARCH_REQUIRE_GPIOLIB
551 This adds support for boards based on the STA2X11 IO-Hub,
552 a.k.a. "ConneXt". The chip is used in place of the standard
553 PC chipset, so all "standard" peripherals are missing. If this
554 option is selected the kernel will still be able to boot on
555 standard PC machines.
558 bool "Summit/EXA (IBM x440)"
559 depends on X86_32_NON_STANDARD
561 This option is needed for IBM systems that use the Summit/EXA chipset.
562 In particular, it is needed for the x440.
565 bool "Unisys ES7000 IA32 series"
566 depends on X86_32_NON_STANDARD && X86_BIGSMP
568 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
569 supposed to run on an IA32-based Unisys ES7000 system.
572 tristate "Eurobraille/Iris poweroff module"
575 The Iris machines from EuroBraille do not have APM or ACPI support
576 to shut themselves down properly. A special I/O sequence is
577 needed to do so, which is what this module does at
580 This is only for Iris machines from EuroBraille.
584 config SCHED_OMIT_FRAME_POINTER
586 prompt "Single-depth WCHAN output"
589 Calculate simpler /proc/<PID>/wchan values. If this option
590 is disabled then wchan values will recurse back to the
591 caller function. This provides more accurate wchan values,
592 at the expense of slightly more scheduling overhead.
594 If in doubt, say "Y".
596 menuconfig PARAVIRT_GUEST
597 bool "Paravirtualized guest support"
599 Say Y here to get to see options related to running Linux under
600 various hypervisors. This option alone does not add any kernel code.
602 If you say N, all options in this submenu will be skipped and disabled.
606 config PARAVIRT_TIME_ACCOUNTING
607 bool "Paravirtual steal time accounting"
611 Select this option to enable fine granularity task steal time
612 accounting. Time spent executing other tasks in parallel with
613 the current vCPU is discounted from the vCPU power. To account for
614 that, there can be a small performance impact.
616 If in doubt, say N here.
618 source "arch/x86/xen/Kconfig"
621 bool "KVM Guest support (including kvmclock)"
624 select PARAVIRT_CLOCK
625 default y if PARAVIRT_GUEST
627 This option enables various optimizations for running under the KVM
628 hypervisor. It includes a paravirtualized clock, so that instead
629 of relying on a PIT (or probably other) emulation by the
630 underlying device model, the host provides the guest with
631 timing infrastructure such as time of day, and system time
633 source "arch/x86/lguest/Kconfig"
636 bool "Enable paravirtualization code"
638 This changes the kernel so it can modify itself when it is run
639 under a hypervisor, potentially improving performance significantly
640 over full virtualization. However, when run without a hypervisor
641 the kernel is theoretically slower and slightly larger.
643 config PARAVIRT_SPINLOCKS
644 bool "Paravirtualization layer for spinlocks"
645 depends on PARAVIRT && SMP
647 Paravirtualized spinlocks allow a pvops backend to replace the
648 spinlock implementation with something virtualization-friendly
649 (for example, block the virtual CPU rather than spinning).
651 Unfortunately the downside is an up to 5% performance hit on
652 native kernels, with various workloads.
654 If you are unsure how to answer this question, answer N.
656 config PARAVIRT_CLOCK
661 config PARAVIRT_DEBUG
662 bool "paravirt-ops debugging"
663 depends on PARAVIRT && DEBUG_KERNEL
665 Enable to debug paravirt_ops internals. Specifically, BUG if
666 a paravirt_op is missing when it is called.
674 This option adds a kernel parameter 'memtest', which allows memtest
676 memtest=0, mean disabled; -- default
677 memtest=1, mean do 1 test pattern;
679 memtest=4, mean do 4 test patterns.
680 If you are unsure how to answer this question, answer N.
682 config X86_SUMMIT_NUMA
684 depends on X86_32 && NUMA && X86_32_NON_STANDARD
686 config X86_CYCLONE_TIMER
688 depends on X86_SUMMIT
690 source "arch/x86/Kconfig.cpu"
694 prompt "HPET Timer Support" if X86_32
696 Use the IA-PC HPET (High Precision Event Timer) to manage
697 time in preference to the PIT and RTC, if a HPET is
699 HPET is the next generation timer replacing legacy 8254s.
700 The HPET provides a stable time base on SMP
701 systems, unlike the TSC, but it is more expensive to access,
702 as it is off-chip. You can find the HPET spec at
703 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
705 You can safely choose Y here. However, HPET will only be
706 activated if the platform and the BIOS support this feature.
707 Otherwise the 8254 will be used for timing services.
709 Choose N to continue using the legacy 8254 timer.
711 config HPET_EMULATE_RTC
713 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
716 def_bool y if X86_INTEL_MID
717 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
719 depends on X86_INTEL_MID && SFI
721 APB timer is the replacement for 8254, HPET on X86 MID platforms.
722 The APBT provides a stable time base on SMP
723 systems, unlike the TSC, but it is more expensive to access,
724 as it is off-chip. APB timers are always running regardless of CPU
725 C states, they are used as per CPU clockevent device when possible.
727 # Mark as expert because too many people got it wrong.
728 # The code disables itself when not needed.
731 bool "Enable DMI scanning" if EXPERT
733 Enabled scanning of DMI to identify machine quirks. Say Y
734 here unless you have verified that your setup is not
735 affected by entries in the DMI blacklist. Required by PNP
739 bool "GART IOMMU support" if EXPERT
742 depends on X86_64 && PCI && AMD_NB
744 Support for full DMA access of devices with 32bit memory access only
745 on systems with more than 3GB. This is usually needed for USB,
746 sound, many IDE/SATA chipsets and some other devices.
747 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
748 based hardware IOMMU and a software bounce buffer based IOMMU used
749 on Intel systems and as fallback.
750 The code is only active when needed (enough memory and limited
751 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
755 bool "IBM Calgary IOMMU support"
757 depends on X86_64 && PCI
759 Support for hardware IOMMUs in IBM's xSeries x366 and x460
760 systems. Needed to run systems with more than 3GB of memory
761 properly with 32-bit PCI devices that do not support DAC
762 (Double Address Cycle). Calgary also supports bus level
763 isolation, where all DMAs pass through the IOMMU. This
764 prevents them from going anywhere except their intended
765 destination. This catches hard-to-find kernel bugs and
766 mis-behaving drivers and devices that do not use the DMA-API
767 properly to set up their DMA buffers. The IOMMU can be
768 turned off at boot time with the iommu=off parameter.
769 Normally the kernel will make the right choice by itself.
772 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
774 prompt "Should Calgary be enabled by default?"
775 depends on CALGARY_IOMMU
777 Should Calgary be enabled by default? if you choose 'y', Calgary
778 will be used (if it exists). If you choose 'n', Calgary will not be
779 used even if it exists. If you choose 'n' and would like to use
780 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
783 # need this always selected by IOMMU for the VIA workaround
787 Support for software bounce buffers used on x86-64 systems
788 which don't have a hardware IOMMU. Using this PCI devices
789 which can only access 32-bits of memory can be used on systems
790 with more than 3 GB of memory.
795 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
798 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
799 depends on X86_64 && SMP && DEBUG_KERNEL
800 select CPUMASK_OFFSTACK
802 Enable maximum number of CPUS and NUMA Nodes for this architecture.
806 int "Maximum number of CPUs" if SMP && !MAXSMP
807 range 2 8 if SMP && X86_32 && !X86_BIGSMP
808 range 2 512 if SMP && !MAXSMP
810 default "4096" if MAXSMP
811 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
814 This allows you to specify the maximum number of CPUs which this
815 kernel will support. The maximum supported value is 512 and the
816 minimum value which makes sense is 2.
818 This is purely to save memory - each supported CPU adds
819 approximately eight kilobytes to the kernel image.
822 bool "SMT (Hyperthreading) scheduler support"
825 SMT scheduler support improves the CPU scheduler's decision making
826 when dealing with Intel Pentium 4 chips with HyperThreading at a
827 cost of slightly increased overhead in some places. If unsure say
832 prompt "Multi-core scheduler support"
835 Multi-core scheduler support improves the CPU scheduler's decision
836 making when dealing with multi-core CPU chips at a cost of slightly
837 increased overhead in some places. If unsure say N here.
839 source "kernel/Kconfig.preempt"
842 bool "Local APIC support on uniprocessors"
843 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
845 A local APIC (Advanced Programmable Interrupt Controller) is an
846 integrated interrupt controller in the CPU. If you have a single-CPU
847 system which has a processor with a local APIC, you can say Y here to
848 enable and use it. If you say Y here even though your machine doesn't
849 have a local APIC, then the kernel will still run with no slowdown at
850 all. The local APIC supports CPU-generated self-interrupts (timer,
851 performance counters), and the NMI watchdog which detects hard
855 bool "IO-APIC support on uniprocessors"
856 depends on X86_UP_APIC
858 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
859 SMP-capable replacement for PC-style interrupt controllers. Most
860 SMP systems and many recent uniprocessor systems have one.
862 If you have a single-CPU system with an IO-APIC, you can say Y here
863 to use it. If you say Y here even though your machine doesn't have
864 an IO-APIC, then the kernel will still run with no slowdown at all.
866 config X86_LOCAL_APIC
868 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
872 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
874 config X86_VISWS_APIC
876 depends on X86_32 && X86_VISWS
878 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
879 bool "Reroute for broken boot IRQs"
880 depends on X86_IO_APIC
882 This option enables a workaround that fixes a source of
883 spurious interrupts. This is recommended when threaded
884 interrupt handling is used on systems where the generation of
885 superfluous "boot interrupts" cannot be disabled.
887 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
888 entry in the chipset's IO-APIC is masked (as, e.g. the RT
889 kernel does during interrupt handling). On chipsets where this
890 boot IRQ generation cannot be disabled, this workaround keeps
891 the original IRQ line masked so that only the equivalent "boot
892 IRQ" is delivered to the CPUs. The workaround also tells the
893 kernel to set up the IRQ handler on the boot IRQ line. In this
894 way only one interrupt is delivered to the kernel. Otherwise
895 the spurious second interrupt may cause the kernel to bring
896 down (vital) interrupt lines.
898 Only affects "broken" chipsets. Interrupt sharing may be
899 increased on these systems.
902 bool "Machine Check / overheating reporting"
905 Machine Check support allows the processor to notify the
906 kernel if it detects a problem (e.g. overheating, data corruption).
907 The action the kernel takes depends on the severity of the problem,
908 ranging from warning messages to halting the machine.
912 prompt "Intel MCE features"
913 depends on X86_MCE && X86_LOCAL_APIC
915 Additional support for intel specific MCE features such as
920 prompt "AMD MCE features"
921 depends on X86_MCE && X86_LOCAL_APIC
923 Additional support for AMD specific MCE features such as
924 the DRAM Error Threshold.
926 config X86_ANCIENT_MCE
927 bool "Support for old Pentium 5 / WinChip machine checks"
928 depends on X86_32 && X86_MCE
930 Include support for machine check handling on old Pentium 5 or WinChip
931 systems. These typically need to be enabled explicitely on the command
934 config X86_MCE_THRESHOLD
935 depends on X86_MCE_AMD || X86_MCE_INTEL
938 config X86_MCE_INJECT
940 tristate "Machine check injector support"
942 Provide support for injecting machine checks for testing purposes.
943 If you don't know what a machine check is and you don't do kernel
944 QA it is safe to say n.
946 config X86_THERMAL_VECTOR
948 depends on X86_MCE_INTEL
951 bool "Enable VM86 support" if EXPERT
955 This option is required by programs like DOSEMU to run 16-bit legacy
956 code on X86 processors. It also may be needed by software like
957 XFree86 to initialize some video cards via BIOS. Disabling this
958 option saves about 6k.
961 tristate "Toshiba Laptop support"
964 This adds a driver to safely access the System Management Mode of
965 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
966 not work on models with a Phoenix BIOS. The System Management Mode
967 is used to set the BIOS and power saving options on Toshiba portables.
969 For information on utilities to make use of this driver see the
970 Toshiba Linux utilities web site at:
971 <http://www.buzzard.org.uk/toshiba/>.
973 Say Y if you intend to run this kernel on a Toshiba portable.
977 tristate "Dell laptop support"
980 This adds a driver to safely access the System Management Mode
981 of the CPU on the Dell Inspiron 8000. The System Management Mode
982 is used to read cpu temperature and cooling fan status and to
983 control the fans on the I8K portables.
985 This driver has been tested only on the Inspiron 8000 but it may
986 also work with other Dell laptops. You can force loading on other
987 models by passing the parameter `force=1' to the module. Use at
990 For information on utilities to make use of this driver see the
991 I8K Linux utilities web site at:
992 <http://people.debian.org/~dz/i8k/>
994 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
997 config X86_REBOOTFIXUPS
998 bool "Enable X86 board specific fixups for reboot"
1001 This enables chipset and/or board specific fixups to be done
1002 in order to get reboot to work correctly. This is only needed on
1003 some combinations of hardware and BIOS. The symptom, for which
1004 this config is intended, is when reboot ends with a stalled/hung
1007 Currently, the only fixup is for the Geode machines using
1008 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1010 Say Y if you want to enable the fixup. Currently, it's safe to
1011 enable this option even if you don't need it.
1015 tristate "CPU microcode loading support"
1019 If you say Y here, you will be able to update the microcode on
1020 certain Intel and AMD processors. The Intel support is for the
1021 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1022 Xeon etc. The AMD support is for families 0x10 and later. You will
1023 obviously need the actual microcode binary data itself which is not
1024 shipped with the Linux kernel.
1026 This option selects the general module only, you need to select
1027 at least one vendor specific module as well.
1029 To compile this driver as a module, choose M here: the module
1030 will be called microcode.
1032 config MICROCODE_INTEL
1033 bool "Intel microcode loading support"
1034 depends on MICROCODE
1038 This options enables microcode patch loading support for Intel
1041 For latest news and information on obtaining all the required
1042 Intel ingredients for this driver, check:
1043 <http://www.urbanmyth.org/microcode/>.
1045 config MICROCODE_AMD
1046 bool "AMD microcode loading support"
1047 depends on MICROCODE
1050 If you select this option, microcode patch loading support for AMD
1051 processors will be enabled.
1053 config MICROCODE_OLD_INTERFACE
1055 depends on MICROCODE
1057 config MICROCODE_INTEL_LIB
1059 depends on MICROCODE_INTEL
1061 config MICROCODE_INTEL_EARLY
1062 bool "Early load microcode"
1063 depends on MICROCODE_INTEL && BLK_DEV_INITRD
1066 This option provides functionality to read additional microcode data
1067 at the beginning of initrd image. The data tells kernel to load
1068 microcode to CPU's as early as possible. No functional change if no
1069 microcode data is glued to the initrd, therefore it's safe to say Y.
1071 config MICROCODE_EARLY
1073 depends on MICROCODE_INTEL_EARLY
1076 tristate "/dev/cpu/*/msr - Model-specific register support"
1078 This device gives privileged processes access to the x86
1079 Model-Specific Registers (MSRs). It is a character device with
1080 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1081 MSR accesses are directed to a specific CPU on multi-processor
1085 tristate "/dev/cpu/*/cpuid - CPU information support"
1087 This device gives processes access to the x86 CPUID instruction to
1088 be executed on a specific processor. It is a character device
1089 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1093 prompt "High Memory Support"
1094 default HIGHMEM64G if X86_NUMAQ
1100 depends on !X86_NUMAQ
1102 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1103 However, the address space of 32-bit x86 processors is only 4
1104 Gigabytes large. That means that, if you have a large amount of
1105 physical memory, not all of it can be "permanently mapped" by the
1106 kernel. The physical memory that's not permanently mapped is called
1109 If you are compiling a kernel which will never run on a machine with
1110 more than 1 Gigabyte total physical RAM, answer "off" here (default
1111 choice and suitable for most users). This will result in a "3GB/1GB"
1112 split: 3GB are mapped so that each process sees a 3GB virtual memory
1113 space and the remaining part of the 4GB virtual memory space is used
1114 by the kernel to permanently map as much physical memory as
1117 If the machine has between 1 and 4 Gigabytes physical RAM, then
1120 If more than 4 Gigabytes is used then answer "64GB" here. This
1121 selection turns Intel PAE (Physical Address Extension) mode on.
1122 PAE implements 3-level paging on IA32 processors. PAE is fully
1123 supported by Linux, PAE mode is implemented on all recent Intel
1124 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1125 then the kernel will not boot on CPUs that don't support PAE!
1127 The actual amount of total physical memory will either be
1128 auto detected or can be forced by using a kernel command line option
1129 such as "mem=256M". (Try "man bootparam" or see the documentation of
1130 your boot loader (lilo or loadlin) about how to pass options to the
1131 kernel at boot time.)
1133 If unsure, say "off".
1137 depends on !X86_NUMAQ
1139 Select this if you have a 32-bit processor and between 1 and 4
1140 gigabytes of physical RAM.
1147 Select this if you have a 32-bit processor and more than 4
1148 gigabytes of physical RAM.
1153 prompt "Memory split" if EXPERT
1157 Select the desired split between kernel and user memory.
1159 If the address range available to the kernel is less than the
1160 physical memory installed, the remaining memory will be available
1161 as "high memory". Accessing high memory is a little more costly
1162 than low memory, as it needs to be mapped into the kernel first.
1163 Note that increasing the kernel address space limits the range
1164 available to user programs, making the address space there
1165 tighter. Selecting anything other than the default 3G/1G split
1166 will also likely make your kernel incompatible with binary-only
1169 If you are not absolutely sure what you are doing, leave this
1173 bool "3G/1G user/kernel split"
1174 config VMSPLIT_3G_OPT
1176 bool "3G/1G user/kernel split (for full 1G low memory)"
1178 bool "2G/2G user/kernel split"
1179 config VMSPLIT_2G_OPT
1181 bool "2G/2G user/kernel split (for full 2G low memory)"
1183 bool "1G/3G user/kernel split"
1188 default 0xB0000000 if VMSPLIT_3G_OPT
1189 default 0x80000000 if VMSPLIT_2G
1190 default 0x78000000 if VMSPLIT_2G_OPT
1191 default 0x40000000 if VMSPLIT_1G
1197 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1200 bool "PAE (Physical Address Extension) Support"
1201 depends on X86_32 && !HIGHMEM4G
1203 PAE is required for NX support, and furthermore enables
1204 larger swapspace support for non-overcommit purposes. It
1205 has the cost of more pagetable lookup overhead, and also
1206 consumes more pagetable space per process.
1208 config ARCH_PHYS_ADDR_T_64BIT
1210 depends on X86_64 || X86_PAE
1212 config ARCH_DMA_ADDR_T_64BIT
1214 depends on X86_64 || HIGHMEM64G
1216 config DIRECT_GBPAGES
1217 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1221 Allow the kernel linear mapping to use 1GB pages on CPUs that
1222 support it. This can improve the kernel's performance a tiny bit by
1223 reducing TLB pressure. If in doubt, say "Y".
1225 # Common NUMA Features
1227 bool "Numa Memory Allocation and Scheduler Support"
1229 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1230 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1232 Enable NUMA (Non Uniform Memory Access) support.
1234 The kernel will try to allocate memory used by a CPU on the
1235 local memory controller of the CPU and add some more
1236 NUMA awareness to the kernel.
1238 For 64-bit this is recommended if the system is Intel Core i7
1239 (or later), AMD Opteron, or EM64T NUMA.
1241 For 32-bit this is only needed on (rare) 32-bit-only platforms
1242 that support NUMA topologies, such as NUMAQ / Summit, or if you
1243 boot a 32-bit kernel on a 64-bit NUMA platform.
1245 Otherwise, you should say N.
1247 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1248 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1252 prompt "Old style AMD Opteron NUMA detection"
1253 depends on X86_64 && NUMA && PCI
1255 Enable AMD NUMA node topology detection. You should say Y here if
1256 you have a multi processor AMD system. This uses an old method to
1257 read the NUMA configuration directly from the builtin Northbridge
1258 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1259 which also takes priority if both are compiled in.
1261 config X86_64_ACPI_NUMA
1263 prompt "ACPI NUMA detection"
1264 depends on X86_64 && NUMA && ACPI && PCI
1267 Enable ACPI SRAT based node topology detection.
1269 # Some NUMA nodes have memory ranges that span
1270 # other nodes. Even though a pfn is valid and
1271 # between a node's start and end pfns, it may not
1272 # reside on that node. See memmap_init_zone()
1274 config NODES_SPAN_OTHER_NODES
1276 depends on X86_64_ACPI_NUMA
1279 bool "NUMA emulation"
1282 Enable NUMA emulation. A flat machine will be split
1283 into virtual nodes when booted with "numa=fake=N", where N is the
1284 number of nodes. This is only useful for debugging.
1287 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1289 default "10" if MAXSMP
1290 default "6" if X86_64
1291 default "4" if X86_NUMAQ
1293 depends on NEED_MULTIPLE_NODES
1295 Specify the maximum number of NUMA Nodes available on the target
1296 system. Increases memory reserved to accommodate various tables.
1298 config ARCH_HAVE_MEMORY_PRESENT
1300 depends on X86_32 && DISCONTIGMEM
1302 config NEED_NODE_MEMMAP_SIZE
1304 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1306 config ARCH_FLATMEM_ENABLE
1308 depends on X86_32 && !NUMA
1310 config ARCH_DISCONTIGMEM_ENABLE
1312 depends on NUMA && X86_32
1314 config ARCH_DISCONTIGMEM_DEFAULT
1316 depends on NUMA && X86_32
1318 config ARCH_SPARSEMEM_ENABLE
1320 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1321 select SPARSEMEM_STATIC if X86_32
1322 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1324 config ARCH_SPARSEMEM_DEFAULT
1328 config ARCH_SELECT_MEMORY_MODEL
1330 depends on ARCH_SPARSEMEM_ENABLE
1332 config ARCH_MEMORY_PROBE
1334 depends on X86_64 && MEMORY_HOTPLUG
1336 config ARCH_PROC_KCORE_TEXT
1338 depends on X86_64 && PROC_KCORE
1340 config ILLEGAL_POINTER_VALUE
1343 default 0xdead000000000000 if X86_64
1348 bool "Allocate 3rd-level pagetables from highmem"
1351 The VM uses one page table entry for each page of physical memory.
1352 For systems with a lot of RAM, this can be wasteful of precious
1353 low memory. Setting this option will put user-space page table
1354 entries in high memory.
1356 config X86_CHECK_BIOS_CORRUPTION
1357 bool "Check for low memory corruption"
1359 Periodically check for memory corruption in low memory, which
1360 is suspected to be caused by BIOS. Even when enabled in the
1361 configuration, it is disabled at runtime. Enable it by
1362 setting "memory_corruption_check=1" on the kernel command
1363 line. By default it scans the low 64k of memory every 60
1364 seconds; see the memory_corruption_check_size and
1365 memory_corruption_check_period parameters in
1366 Documentation/kernel-parameters.txt to adjust this.
1368 When enabled with the default parameters, this option has
1369 almost no overhead, as it reserves a relatively small amount
1370 of memory and scans it infrequently. It both detects corruption
1371 and prevents it from affecting the running system.
1373 It is, however, intended as a diagnostic tool; if repeatable
1374 BIOS-originated corruption always affects the same memory,
1375 you can use memmap= to prevent the kernel from using that
1378 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1379 bool "Set the default setting of memory_corruption_check"
1380 depends on X86_CHECK_BIOS_CORRUPTION
1383 Set whether the default state of memory_corruption_check is
1386 config X86_RESERVE_LOW
1387 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1391 Specify the amount of low memory to reserve for the BIOS.
1393 The first page contains BIOS data structures that the kernel
1394 must not use, so that page must always be reserved.
1396 By default we reserve the first 64K of physical RAM, as a
1397 number of BIOSes are known to corrupt that memory range
1398 during events such as suspend/resume or monitor cable
1399 insertion, so it must not be used by the kernel.
1401 You can set this to 4 if you are absolutely sure that you
1402 trust the BIOS to get all its memory reservations and usages
1403 right. If you know your BIOS have problems beyond the
1404 default 64K area, you can set this to 640 to avoid using the
1405 entire low memory range.
1407 If you have doubts about the BIOS (e.g. suspend/resume does
1408 not work or there's kernel crashes after certain hardware
1409 hotplug events) then you might want to enable
1410 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1411 typical corruption patterns.
1413 Leave this to the default value of 64 if you are unsure.
1415 config MATH_EMULATION
1417 prompt "Math emulation" if X86_32
1419 Linux can emulate a math coprocessor (used for floating point
1420 operations) if you don't have one. 486DX and Pentium processors have
1421 a math coprocessor built in, 486SX and 386 do not, unless you added
1422 a 487DX or 387, respectively. (The messages during boot time can
1423 give you some hints here ["man dmesg"].) Everyone needs either a
1424 coprocessor or this emulation.
1426 If you don't have a math coprocessor, you need to say Y here; if you
1427 say Y here even though you have a coprocessor, the coprocessor will
1428 be used nevertheless. (This behavior can be changed with the kernel
1429 command line option "no387", which comes handy if your coprocessor
1430 is broken. Try "man bootparam" or see the documentation of your boot
1431 loader (lilo or loadlin) about how to pass options to the kernel at
1432 boot time.) This means that it is a good idea to say Y here if you
1433 intend to use this kernel on different machines.
1435 More information about the internals of the Linux math coprocessor
1436 emulation can be found in <file:arch/x86/math-emu/README>.
1438 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1439 kernel, it won't hurt.
1443 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1445 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1446 the Memory Type Range Registers (MTRRs) may be used to control
1447 processor access to memory ranges. This is most useful if you have
1448 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1449 allows bus write transfers to be combined into a larger transfer
1450 before bursting over the PCI/AGP bus. This can increase performance
1451 of image write operations 2.5 times or more. Saying Y here creates a
1452 /proc/mtrr file which may be used to manipulate your processor's
1453 MTRRs. Typically the X server should use this.
1455 This code has a reasonably generic interface so that similar
1456 control registers on other processors can be easily supported
1459 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1460 Registers (ARRs) which provide a similar functionality to MTRRs. For
1461 these, the ARRs are used to emulate the MTRRs.
1462 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1463 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1464 write-combining. All of these processors are supported by this code
1465 and it makes sense to say Y here if you have one of them.
1467 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1468 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1469 can lead to all sorts of problems, so it's good to say Y here.
1471 You can safely say Y even if your machine doesn't have MTRRs, you'll
1472 just add about 9 KB to your kernel.
1474 See <file:Documentation/x86/mtrr.txt> for more information.
1476 config MTRR_SANITIZER
1478 prompt "MTRR cleanup support"
1481 Convert MTRR layout from continuous to discrete, so X drivers can
1482 add writeback entries.
1484 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1485 The largest mtrr entry size for a continuous block can be set with
1490 config MTRR_SANITIZER_ENABLE_DEFAULT
1491 int "MTRR cleanup enable value (0-1)"
1494 depends on MTRR_SANITIZER
1496 Enable mtrr cleanup default value
1498 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1499 int "MTRR cleanup spare reg num (0-7)"
1502 depends on MTRR_SANITIZER
1504 mtrr cleanup spare entries default, it can be changed via
1505 mtrr_spare_reg_nr=N on the kernel command line.
1509 prompt "x86 PAT support" if EXPERT
1512 Use PAT attributes to setup page level cache control.
1514 PATs are the modern equivalents of MTRRs and are much more
1515 flexible than MTRRs.
1517 Say N here if you see bootup problems (boot crash, boot hang,
1518 spontaneous reboots) or a non-working video driver.
1522 config ARCH_USES_PG_UNCACHED
1528 prompt "x86 architectural random number generator" if EXPERT
1530 Enable the x86 architectural RDRAND instruction
1531 (Intel Bull Mountain technology) to generate random numbers.
1532 If supported, this is a high bandwidth, cryptographically
1533 secure hardware random number generator.
1537 prompt "Supervisor Mode Access Prevention" if EXPERT
1539 Supervisor Mode Access Prevention (SMAP) is a security
1540 feature in newer Intel processors. There is a small
1541 performance cost if this enabled and turned on; there is
1542 also a small increase in the kernel size if this is enabled.
1547 bool "EFI runtime service support"
1550 This enables the kernel to use EFI runtime services that are
1551 available (such as the EFI variable services).
1553 This option is only useful on systems that have EFI firmware.
1554 In addition, you should use the latest ELILO loader available
1555 at <http://elilo.sourceforge.net> in order to take advantage
1556 of EFI runtime services. However, even with this option, the
1557 resultant kernel should continue to boot on existing non-EFI
1561 bool "EFI stub support"
1564 This kernel feature allows a bzImage to be loaded directly
1565 by EFI firmware without the use of a bootloader.
1567 See Documentation/x86/efi-stub.txt for more information.
1571 prompt "Enable seccomp to safely compute untrusted bytecode"
1573 This kernel feature is useful for number crunching applications
1574 that may need to compute untrusted bytecode during their
1575 execution. By using pipes or other transports made available to
1576 the process as file descriptors supporting the read/write
1577 syscalls, it's possible to isolate those applications in
1578 their own address space using seccomp. Once seccomp is
1579 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1580 and the task is only allowed to execute a few safe syscalls
1581 defined by each seccomp mode.
1583 If unsure, say Y. Only embedded should say N here.
1585 config CC_STACKPROTECTOR
1586 bool "Enable -fstack-protector buffer overflow detection"
1588 This option turns on the -fstack-protector GCC feature. This
1589 feature puts, at the beginning of functions, a canary value on
1590 the stack just before the return address, and validates
1591 the value just before actually returning. Stack based buffer
1592 overflows (that need to overwrite this return address) now also
1593 overwrite the canary, which gets detected and the attack is then
1594 neutralized via a kernel panic.
1596 This feature requires gcc version 4.2 or above, or a distribution
1597 gcc with the feature backported. Older versions are automatically
1598 detected and for those versions, this configuration option is
1599 ignored. (and a warning is printed during bootup)
1601 source kernel/Kconfig.hz
1604 bool "kexec system call"
1606 kexec is a system call that implements the ability to shutdown your
1607 current kernel, and to start another kernel. It is like a reboot
1608 but it is independent of the system firmware. And like a reboot
1609 you can start any kernel with it, not just Linux.
1611 The name comes from the similarity to the exec system call.
1613 It is an ongoing process to be certain the hardware in a machine
1614 is properly shutdown, so do not be surprised if this code does not
1615 initially work for you. It may help to enable device hotplugging
1616 support. As of this writing the exact hardware interface is
1617 strongly in flux, so no good recommendation can be made.
1620 bool "kernel crash dumps"
1621 depends on X86_64 || (X86_32 && HIGHMEM)
1623 Generate crash dump after being started by kexec.
1624 This should be normally only set in special crash dump kernels
1625 which are loaded in the main kernel with kexec-tools into
1626 a specially reserved region and then later executed after
1627 a crash by kdump/kexec. The crash dump kernel must be compiled
1628 to a memory address not used by the main kernel or BIOS using
1629 PHYSICAL_START, or it must be built as a relocatable image
1630 (CONFIG_RELOCATABLE=y).
1631 For more details see Documentation/kdump/kdump.txt
1635 depends on KEXEC && HIBERNATION
1637 Jump between original kernel and kexeced kernel and invoke
1638 code in physical address mode via KEXEC
1640 config PHYSICAL_START
1641 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1644 This gives the physical address where the kernel is loaded.
1646 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1647 bzImage will decompress itself to above physical address and
1648 run from there. Otherwise, bzImage will run from the address where
1649 it has been loaded by the boot loader and will ignore above physical
1652 In normal kdump cases one does not have to set/change this option
1653 as now bzImage can be compiled as a completely relocatable image
1654 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1655 address. This option is mainly useful for the folks who don't want
1656 to use a bzImage for capturing the crash dump and want to use a
1657 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1658 to be specifically compiled to run from a specific memory area
1659 (normally a reserved region) and this option comes handy.
1661 So if you are using bzImage for capturing the crash dump,
1662 leave the value here unchanged to 0x1000000 and set
1663 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1664 for capturing the crash dump change this value to start of
1665 the reserved region. In other words, it can be set based on
1666 the "X" value as specified in the "crashkernel=YM@XM"
1667 command line boot parameter passed to the panic-ed
1668 kernel. Please take a look at Documentation/kdump/kdump.txt
1669 for more details about crash dumps.
1671 Usage of bzImage for capturing the crash dump is recommended as
1672 one does not have to build two kernels. Same kernel can be used
1673 as production kernel and capture kernel. Above option should have
1674 gone away after relocatable bzImage support is introduced. But it
1675 is present because there are users out there who continue to use
1676 vmlinux for dump capture. This option should go away down the
1679 Don't change this unless you know what you are doing.
1682 bool "Build a relocatable kernel"
1685 This builds a kernel image that retains relocation information
1686 so it can be loaded someplace besides the default 1MB.
1687 The relocations tend to make the kernel binary about 10% larger,
1688 but are discarded at runtime.
1690 One use is for the kexec on panic case where the recovery kernel
1691 must live at a different physical address than the primary
1694 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1695 it has been loaded at and the compile time physical address
1696 (CONFIG_PHYSICAL_START) is ignored.
1698 # Relocation on x86-32 needs some additional build support
1699 config X86_NEED_RELOCS
1701 depends on X86_32 && RELOCATABLE
1703 config PHYSICAL_ALIGN
1704 hex "Alignment value to which kernel should be aligned" if X86_32
1706 range 0x2000 0x1000000
1708 This value puts the alignment restrictions on physical address
1709 where kernel is loaded and run from. Kernel is compiled for an
1710 address which meets above alignment restriction.
1712 If bootloader loads the kernel at a non-aligned address and
1713 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1714 address aligned to above value and run from there.
1716 If bootloader loads the kernel at a non-aligned address and
1717 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1718 load address and decompress itself to the address it has been
1719 compiled for and run from there. The address for which kernel is
1720 compiled already meets above alignment restrictions. Hence the
1721 end result is that kernel runs from a physical address meeting
1722 above alignment restrictions.
1724 Don't change this unless you know what you are doing.
1727 bool "Support for hot-pluggable CPUs"
1728 depends on SMP && HOTPLUG
1730 Say Y here to allow turning CPUs off and on. CPUs can be
1731 controlled through /sys/devices/system/cpu.
1732 ( Note: power management support will enable this option
1733 automatically on SMP systems. )
1734 Say N if you want to disable CPU hotplug.
1736 config BOOTPARAM_HOTPLUG_CPU0
1737 bool "Set default setting of cpu0_hotpluggable"
1739 depends on HOTPLUG_CPU
1741 Set whether default state of cpu0_hotpluggable is on or off.
1743 Say Y here to enable CPU0 hotplug by default. If this switch
1744 is turned on, there is no need to give cpu0_hotplug kernel
1745 parameter and the CPU0 hotplug feature is enabled by default.
1747 Please note: there are two known CPU0 dependencies if you want
1748 to enable the CPU0 hotplug feature either by this switch or by
1749 cpu0_hotplug kernel parameter.
1751 First, resume from hibernate or suspend always starts from CPU0.
1752 So hibernate and suspend are prevented if CPU0 is offline.
1754 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1755 offline if any interrupt can not migrate out of CPU0. There may
1756 be other CPU0 dependencies.
1758 Please make sure the dependencies are under your control before
1759 you enable this feature.
1761 Say N if you don't want to enable CPU0 hotplug feature by default.
1762 You still can enable the CPU0 hotplug feature at boot by kernel
1763 parameter cpu0_hotplug.
1765 config DEBUG_HOTPLUG_CPU0
1767 prompt "Debug CPU0 hotplug"
1768 depends on HOTPLUG_CPU
1770 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1771 soon as possible and boots up userspace with CPU0 offlined. User
1772 can online CPU0 back after boot time.
1774 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1775 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1776 compilation or giving cpu0_hotplug kernel parameter at boot.
1782 prompt "Compat VDSO support"
1783 depends on X86_32 || IA32_EMULATION
1785 Map the 32-bit VDSO to the predictable old-style address too.
1787 Say N here if you are running a sufficiently recent glibc
1788 version (2.3.3 or later), to remove the high-mapped
1789 VDSO mapping and to exclusively use the randomized VDSO.
1794 bool "Built-in kernel command line"
1796 Allow for specifying boot arguments to the kernel at
1797 build time. On some systems (e.g. embedded ones), it is
1798 necessary or convenient to provide some or all of the
1799 kernel boot arguments with the kernel itself (that is,
1800 to not rely on the boot loader to provide them.)
1802 To compile command line arguments into the kernel,
1803 set this option to 'Y', then fill in the
1804 the boot arguments in CONFIG_CMDLINE.
1806 Systems with fully functional boot loaders (i.e. non-embedded)
1807 should leave this option set to 'N'.
1810 string "Built-in kernel command string"
1811 depends on CMDLINE_BOOL
1814 Enter arguments here that should be compiled into the kernel
1815 image and used at boot time. If the boot loader provides a
1816 command line at boot time, it is appended to this string to
1817 form the full kernel command line, when the system boots.
1819 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1820 change this behavior.
1822 In most cases, the command line (whether built-in or provided
1823 by the boot loader) should specify the device for the root
1826 config CMDLINE_OVERRIDE
1827 bool "Built-in command line overrides boot loader arguments"
1828 depends on CMDLINE_BOOL
1830 Set this option to 'Y' to have the kernel ignore the boot loader
1831 command line, and use ONLY the built-in command line.
1833 This is used to work around broken boot loaders. This should
1834 be set to 'N' under normal conditions.
1838 config ARCH_ENABLE_MEMORY_HOTPLUG
1840 depends on X86_64 || (X86_32 && HIGHMEM)
1842 config ARCH_ENABLE_MEMORY_HOTREMOVE
1844 depends on MEMORY_HOTPLUG
1846 config USE_PERCPU_NUMA_NODE_ID
1850 menu "Power management and ACPI options"
1852 config ARCH_HIBERNATION_HEADER
1854 depends on X86_64 && HIBERNATION
1856 source "kernel/power/Kconfig"
1858 source "drivers/acpi/Kconfig"
1860 source "drivers/sfi/Kconfig"
1867 tristate "APM (Advanced Power Management) BIOS support"
1868 depends on X86_32 && PM_SLEEP
1870 APM is a BIOS specification for saving power using several different
1871 techniques. This is mostly useful for battery powered laptops with
1872 APM compliant BIOSes. If you say Y here, the system time will be
1873 reset after a RESUME operation, the /proc/apm device will provide
1874 battery status information, and user-space programs will receive
1875 notification of APM "events" (e.g. battery status change).
1877 If you select "Y" here, you can disable actual use of the APM
1878 BIOS by passing the "apm=off" option to the kernel at boot time.
1880 Note that the APM support is almost completely disabled for
1881 machines with more than one CPU.
1883 In order to use APM, you will need supporting software. For location
1884 and more information, read <file:Documentation/power/apm-acpi.txt>
1885 and the Battery Powered Linux mini-HOWTO, available from
1886 <http://www.tldp.org/docs.html#howto>.
1888 This driver does not spin down disk drives (see the hdparm(8)
1889 manpage ("man 8 hdparm") for that), and it doesn't turn off
1890 VESA-compliant "green" monitors.
1892 This driver does not support the TI 4000M TravelMate and the ACER
1893 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1894 desktop machines also don't have compliant BIOSes, and this driver
1895 may cause those machines to panic during the boot phase.
1897 Generally, if you don't have a battery in your machine, there isn't
1898 much point in using this driver and you should say N. If you get
1899 random kernel OOPSes or reboots that don't seem to be related to
1900 anything, try disabling/enabling this option (or disabling/enabling
1903 Some other things you should try when experiencing seemingly random,
1906 1) make sure that you have enough swap space and that it is
1908 2) pass the "no-hlt" option to the kernel
1909 3) switch on floating point emulation in the kernel and pass
1910 the "no387" option to the kernel
1911 4) pass the "floppy=nodma" option to the kernel
1912 5) pass the "mem=4M" option to the kernel (thereby disabling
1913 all but the first 4 MB of RAM)
1914 6) make sure that the CPU is not over clocked.
1915 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1916 8) disable the cache from your BIOS settings
1917 9) install a fan for the video card or exchange video RAM
1918 10) install a better fan for the CPU
1919 11) exchange RAM chips
1920 12) exchange the motherboard.
1922 To compile this driver as a module, choose M here: the
1923 module will be called apm.
1927 config APM_IGNORE_USER_SUSPEND
1928 bool "Ignore USER SUSPEND"
1930 This option will ignore USER SUSPEND requests. On machines with a
1931 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1932 series notebooks, it is necessary to say Y because of a BIOS bug.
1934 config APM_DO_ENABLE
1935 bool "Enable PM at boot time"
1937 Enable APM features at boot time. From page 36 of the APM BIOS
1938 specification: "When disabled, the APM BIOS does not automatically
1939 power manage devices, enter the Standby State, enter the Suspend
1940 State, or take power saving steps in response to CPU Idle calls."
1941 This driver will make CPU Idle calls when Linux is idle (unless this
1942 feature is turned off -- see "Do CPU IDLE calls", below). This
1943 should always save battery power, but more complicated APM features
1944 will be dependent on your BIOS implementation. You may need to turn
1945 this option off if your computer hangs at boot time when using APM
1946 support, or if it beeps continuously instead of suspending. Turn
1947 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1948 T400CDT. This is off by default since most machines do fine without
1953 bool "Make CPU Idle calls when idle"
1955 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1956 On some machines, this can activate improved power savings, such as
1957 a slowed CPU clock rate, when the machine is idle. These idle calls
1958 are made after the idle loop has run for some length of time (e.g.,
1959 333 mS). On some machines, this will cause a hang at boot time or
1960 whenever the CPU becomes idle. (On machines with more than one CPU,
1961 this option does nothing.)
1963 config APM_DISPLAY_BLANK
1964 bool "Enable console blanking using APM"
1966 Enable console blanking using the APM. Some laptops can use this to
1967 turn off the LCD backlight when the screen blanker of the Linux
1968 virtual console blanks the screen. Note that this is only used by
1969 the virtual console screen blanker, and won't turn off the backlight
1970 when using the X Window system. This also doesn't have anything to
1971 do with your VESA-compliant power-saving monitor. Further, this
1972 option doesn't work for all laptops -- it might not turn off your
1973 backlight at all, or it might print a lot of errors to the console,
1974 especially if you are using gpm.
1976 config APM_ALLOW_INTS
1977 bool "Allow interrupts during APM BIOS calls"
1979 Normally we disable external interrupts while we are making calls to
1980 the APM BIOS as a measure to lessen the effects of a badly behaving
1981 BIOS implementation. The BIOS should reenable interrupts if it
1982 needs to. Unfortunately, some BIOSes do not -- especially those in
1983 many of the newer IBM Thinkpads. If you experience hangs when you
1984 suspend, try setting this to Y. Otherwise, say N.
1988 source "drivers/cpufreq/Kconfig"
1990 source "drivers/cpuidle/Kconfig"
1992 source "drivers/idle/Kconfig"
1997 menu "Bus options (PCI etc.)"
2002 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2004 Find out whether you have a PCI motherboard. PCI is the name of a
2005 bus system, i.e. the way the CPU talks to the other stuff inside
2006 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2007 VESA. If you have PCI, say Y, otherwise N.
2010 prompt "PCI access mode"
2011 depends on X86_32 && PCI
2014 On PCI systems, the BIOS can be used to detect the PCI devices and
2015 determine their configuration. However, some old PCI motherboards
2016 have BIOS bugs and may crash if this is done. Also, some embedded
2017 PCI-based systems don't have any BIOS at all. Linux can also try to
2018 detect the PCI hardware directly without using the BIOS.
2020 With this option, you can specify how Linux should detect the
2021 PCI devices. If you choose "BIOS", the BIOS will be used,
2022 if you choose "Direct", the BIOS won't be used, and if you
2023 choose "MMConfig", then PCI Express MMCONFIG will be used.
2024 If you choose "Any", the kernel will try MMCONFIG, then the
2025 direct access method and falls back to the BIOS if that doesn't
2026 work. If unsure, go with the default, which is "Any".
2031 config PCI_GOMMCONFIG
2048 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2050 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2053 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2057 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2061 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2065 depends on PCI && XEN
2073 bool "Support mmconfig PCI config space access"
2074 depends on X86_64 && PCI && ACPI
2076 config PCI_CNB20LE_QUIRK
2077 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2080 Read the PCI windows out of the CNB20LE host bridge. This allows
2081 PCI hotplug to work on systems with the CNB20LE chipset which do
2084 There's no public spec for this chipset, and this functionality
2085 is known to be incomplete.
2087 You should say N unless you know you need this.
2089 source "drivers/pci/pcie/Kconfig"
2091 source "drivers/pci/Kconfig"
2093 # x86_64 have no ISA slots, but can have ISA-style DMA.
2095 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2098 Enables ISA-style DMA support for devices requiring such controllers.
2106 Find out whether you have ISA slots on your motherboard. ISA is the
2107 name of a bus system, i.e. the way the CPU talks to the other stuff
2108 inside your box. Other bus systems are PCI, EISA, MicroChannel
2109 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2110 newer boards don't support it. If you have ISA, say Y, otherwise N.
2116 The Extended Industry Standard Architecture (EISA) bus was
2117 developed as an open alternative to the IBM MicroChannel bus.
2119 The EISA bus provided some of the features of the IBM MicroChannel
2120 bus while maintaining backward compatibility with cards made for
2121 the older ISA bus. The EISA bus saw limited use between 1988 and
2122 1995 when it was made obsolete by the PCI bus.
2124 Say Y here if you are building a kernel for an EISA-based machine.
2128 source "drivers/eisa/Kconfig"
2131 tristate "NatSemi SCx200 support"
2133 This provides basic support for National Semiconductor's
2134 (now AMD's) Geode processors. The driver probes for the
2135 PCI-IDs of several on-chip devices, so its a good dependency
2136 for other scx200_* drivers.
2138 If compiled as a module, the driver is named scx200.
2140 config SCx200HR_TIMER
2141 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2145 This driver provides a clocksource built upon the on-chip
2146 27MHz high-resolution timer. Its also a workaround for
2147 NSC Geode SC-1100's buggy TSC, which loses time when the
2148 processor goes idle (as is done by the scheduler). The
2149 other workaround is idle=poll boot option.
2152 bool "One Laptop Per Child support"
2159 Add support for detecting the unique features of the OLPC
2163 bool "OLPC XO-1 Power Management"
2164 depends on OLPC && MFD_CS5535 && PM_SLEEP
2167 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2170 bool "OLPC XO-1 Real Time Clock"
2171 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2173 Add support for the XO-1 real time clock, which can be used as a
2174 programmable wakeup source.
2177 bool "OLPC XO-1 SCI extras"
2178 depends on OLPC && OLPC_XO1_PM
2184 Add support for SCI-based features of the OLPC XO-1 laptop:
2185 - EC-driven system wakeups
2189 - AC adapter status updates
2190 - Battery status updates
2192 config OLPC_XO15_SCI
2193 bool "OLPC XO-1.5 SCI extras"
2194 depends on OLPC && ACPI
2197 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2198 - EC-driven system wakeups
2199 - AC adapter status updates
2200 - Battery status updates
2203 bool "PCEngines ALIX System Support (LED setup)"
2206 This option enables system support for the PCEngines ALIX.
2207 At present this just sets up LEDs for GPIO control on
2208 ALIX2/3/6 boards. However, other system specific setup should
2211 Note: You must still enable the drivers for GPIO and LED support
2212 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2214 Note: You have to set alix.force=1 for boards with Award BIOS.
2217 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2220 This option enables system support for the Soekris Engineering net5501.
2223 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2227 This option enables system support for the Traverse Technologies GEOS.
2230 bool "Technologic Systems TS-5500 platform support"
2232 select CHECK_SIGNATURE
2236 This option enables system support for the Technologic Systems TS-5500.
2242 depends on CPU_SUP_AMD && PCI
2244 source "drivers/pcmcia/Kconfig"
2246 source "drivers/pci/hotplug/Kconfig"
2249 bool "RapidIO support"
2253 If you say Y here, the kernel will include drivers and
2254 infrastructure code to support RapidIO interconnect devices.
2256 source "drivers/rapidio/Kconfig"
2261 menu "Executable file formats / Emulations"
2263 source "fs/Kconfig.binfmt"
2265 config IA32_EMULATION
2266 bool "IA32 Emulation"
2268 select COMPAT_BINFMT_ELF
2271 Include code to run legacy 32-bit programs under a
2272 64-bit kernel. You should likely turn this on, unless you're
2273 100% sure that you don't have any 32-bit programs left.
2276 tristate "IA32 a.out support"
2277 depends on IA32_EMULATION
2279 Support old a.out binaries in the 32bit emulation.
2282 bool "x32 ABI for 64-bit mode"
2283 depends on X86_64 && IA32_EMULATION
2285 Include code to run binaries for the x32 native 32-bit ABI
2286 for 64-bit processors. An x32 process gets access to the
2287 full 64-bit register file and wide data path while leaving
2288 pointers at 32 bits for smaller memory footprint.
2290 You will need a recent binutils (2.22 or later) with
2291 elf32_x86_64 support enabled to compile a kernel with this
2296 depends on IA32_EMULATION || X86_X32
2297 select ARCH_WANT_OLD_COMPAT_IPC
2300 config COMPAT_FOR_U64_ALIGNMENT
2303 config SYSVIPC_COMPAT
2315 config HAVE_ATOMIC_IOMAP
2319 config HAVE_TEXT_POKE_SMP
2321 select STOP_MACHINE if SMP
2323 config X86_DEV_DMA_OPS
2325 depends on X86_64 || STA2X11
2327 config X86_DMA_REMAP
2331 source "net/Kconfig"
2333 source "drivers/Kconfig"
2335 source "drivers/firmware/Kconfig"
2339 source "arch/x86/Kconfig.debug"
2341 source "security/Kconfig"
2343 source "crypto/Kconfig"
2345 source "arch/x86/kvm/Kconfig"
2347 source "lib/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob