2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
21 select HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
27 select HAVE_PERF_COUNTERS if (!M386 && !M486)
28 select HAVE_IOREMAP_PROT
30 select ARCH_WANT_OPTIONAL_GPIOLIB
31 select ARCH_WANT_FRAME_POINTERS
33 select HAVE_KRETPROBES
34 select HAVE_FTRACE_MCOUNT_RECORD
35 select HAVE_DYNAMIC_FTRACE
36 select HAVE_FUNCTION_TRACER
37 select HAVE_FUNCTION_GRAPH_TRACER
38 select HAVE_FUNCTION_GRAPH_FP_TEST
39 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
40 select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
41 select HAVE_SYSCALL_TRACEPOINTS
44 select HAVE_ARCH_TRACEHOOK
45 select HAVE_GENERIC_DMA_COHERENT if X86_32
46 select HAVE_EFFICIENT_UNALIGNED_ACCESS
47 select USER_STACKTRACE_SUPPORT
48 select HAVE_DMA_API_DEBUG
49 select HAVE_KERNEL_GZIP
50 select HAVE_KERNEL_BZIP2
51 select HAVE_KERNEL_LZMA
52 select HAVE_ARCH_KMEMCHECK
56 default "elf32-i386" if X86_32
57 default "elf64-x86-64" if X86_64
61 default "arch/x86/configs/i386_defconfig" if X86_32
62 default "arch/x86/configs/x86_64_defconfig" if X86_64
67 config GENERIC_CMOS_UPDATE
70 config CLOCKSOURCE_WATCHDOG
73 config GENERIC_CLOCKEVENTS
76 config GENERIC_CLOCKEVENTS_BROADCAST
78 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
80 config LOCKDEP_SUPPORT
83 config STACKTRACE_SUPPORT
86 config HAVE_LATENCYTOP_SUPPORT
89 config FAST_CMPXCHG_LOCAL
102 config GENERIC_ISA_DMA
111 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
113 config GENERIC_BUG_RELATIVE_POINTERS
116 config GENERIC_HWEIGHT
122 config ARCH_MAY_HAVE_PC_FDC
125 config RWSEM_GENERIC_SPINLOCK
128 config RWSEM_XCHGADD_ALGORITHM
131 config ARCH_HAS_CPU_IDLE_WAIT
134 config GENERIC_CALIBRATE_DELAY
137 config GENERIC_TIME_VSYSCALL
141 config ARCH_HAS_CPU_RELAX
144 config ARCH_HAS_DEFAULT_IDLE
147 config ARCH_HAS_CACHE_LINE_SIZE
150 config HAVE_SETUP_PER_CPU_AREA
153 config NEED_PER_CPU_EMBED_FIRST_CHUNK
156 config NEED_PER_CPU_PAGE_FIRST_CHUNK
159 config HAVE_CPUMASK_OF_CPU_MAP
162 config ARCH_HIBERNATION_POSSIBLE
165 config ARCH_SUSPEND_POSSIBLE
172 config ARCH_POPULATES_NODE_MAP
179 config ARCH_SUPPORTS_OPTIMIZED_INLINING
182 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
185 config HAVE_INTEL_TXT
187 depends on EXPERIMENTAL && DMAR && ACPI
189 # Use the generic interrupt handling code in kernel/irq/:
190 config GENERIC_HARDIRQS
194 config GENERIC_HARDIRQS_NO__DO_IRQ
197 config GENERIC_IRQ_PROBE
201 config GENERIC_PENDING_IRQ
203 depends on GENERIC_HARDIRQS && SMP
206 config USE_GENERIC_SMP_HELPERS
212 depends on X86_32 && SMP
216 depends on X86_64 && SMP
223 config X86_TRAMPOLINE
225 depends on SMP || (64BIT && ACPI_SLEEP)
228 config X86_32_LAZY_GS
230 depends on X86_32 && !CC_STACKPROTECTOR
234 source "init/Kconfig"
235 source "kernel/Kconfig.freezer"
237 menu "Processor type and features"
239 source "kernel/time/Kconfig"
242 bool "Symmetric multi-processing support"
244 This enables support for systems with more than one CPU. If you have
245 a system with only one CPU, like most personal computers, say N. If
246 you have a system with more than one CPU, say Y.
248 If you say N here, the kernel will run on single and multiprocessor
249 machines, but will use only one CPU of a multiprocessor machine. If
250 you say Y here, the kernel will run on many, but not all,
251 singleprocessor machines. On a singleprocessor machine, the kernel
252 will run faster if you say N here.
254 Note that if you say Y here and choose architecture "586" or
255 "Pentium" under "Processor family", the kernel will not work on 486
256 architectures. Similarly, multiprocessor kernels for the "PPro"
257 architecture may not work on all Pentium based boards.
259 People using multiprocessor machines who say Y here should also say
260 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
261 Management" code will be disabled if you say Y here.
263 See also <file:Documentation/i386/IO-APIC.txt>,
264 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
265 <http://www.tldp.org/docs.html#howto>.
267 If you don't know what to do here, say N.
270 bool "Support x2apic"
271 depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
273 This enables x2apic support on CPUs that have this feature.
275 This allows 32-bit apic IDs (so it can support very large systems),
276 and accesses the local apic via MSRs not via mmio.
278 If you don't know what to do here, say N.
281 bool "Support sparse irq numbering"
282 depends on PCI_MSI || HT_IRQ
284 This enables support for sparse irqs. This is useful for distro
285 kernels that want to define a high CONFIG_NR_CPUS value but still
286 want to have low kernel memory footprint on smaller machines.
288 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
289 out the irq_desc[] array in a more NUMA-friendly way. )
291 If you don't know what to do here, say N.
295 depends on SPARSE_IRQ && NUMA
298 bool "Enable MPS table" if ACPI
300 depends on X86_LOCAL_APIC
302 For old smp systems that do not have proper acpi support. Newer systems
303 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
306 bool "Support for big SMP systems with more than 8 CPUs"
307 depends on X86_32 && SMP
309 This option is needed for the systems that have more than 8 CPUs
312 config X86_EXTENDED_PLATFORM
313 bool "Support for extended (non-PC) x86 platforms"
316 If you disable this option then the kernel will only support
317 standard PC platforms. (which covers the vast majority of
320 If you enable this option then you'll be able to select support
321 for the following (non-PC) 32 bit x86 platforms:
325 SGI 320/540 (Visual Workstation)
326 Summit/EXA (IBM x440)
327 Unisys ES7000 IA32 series
329 If you have one of these systems, or if you want to build a
330 generic distribution kernel, say Y here - otherwise say N.
334 config X86_EXTENDED_PLATFORM
335 bool "Support for extended (non-PC) x86 platforms"
338 If you disable this option then the kernel will only support
339 standard PC platforms. (which covers the vast majority of
342 If you enable this option then you'll be able to select support
343 for the following (non-PC) 64 bit x86 platforms:
347 If you have one of these systems, or if you want to build a
348 generic distribution kernel, say Y here - otherwise say N.
350 # This is an alphabetically sorted list of 64 bit extended platforms
351 # Please maintain the alphabetic order if and when there are additions
356 depends on X86_64 && PCI
357 depends on X86_EXTENDED_PLATFORM
359 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
360 supposed to run on these EM64T-based machines. Only choose this option
361 if you have one of these machines.
364 bool "SGI Ultraviolet"
366 depends on X86_EXTENDED_PLATFORM
368 depends on X86_X2APIC
370 This option is needed in order to support SGI Ultraviolet systems.
371 If you don't have one of these, you should say N here.
373 # Following is an alphabetically sorted list of 32 bit extended platforms
374 # Please maintain the alphabetic order if and when there are additions
379 depends on X86_EXTENDED_PLATFORM
381 Select this for an AMD Elan processor.
383 Do not use this option for K6/Athlon/Opteron processors!
385 If unsure, choose "PC-compatible" instead.
388 bool "RDC R-321x SoC"
390 depends on X86_EXTENDED_PLATFORM
392 select X86_REBOOTFIXUPS
394 This option is needed for RDC R-321x system-on-chip, also known
396 If you don't have one of these chips, you should say N here.
398 config X86_32_NON_STANDARD
399 bool "Support non-standard 32-bit SMP architectures"
400 depends on X86_32 && SMP
401 depends on X86_EXTENDED_PLATFORM
403 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
404 subarchitectures. It is intended for a generic binary kernel.
405 if you select them all, kernel will probe it one by one. and will
408 # Alphabetically sorted list of Non standard 32 bit platforms
411 bool "NUMAQ (IBM/Sequent)"
412 depends on X86_32_NON_STANDARD
416 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
417 NUMA multiquad box. This changes the way that processors are
418 bootstrapped, and uses Clustered Logical APIC addressing mode instead
419 of Flat Logical. You will need a new lynxer.elf file to flash your
420 firmware with - send email to <Martin.Bligh@us.ibm.com>.
423 bool "SGI 320/540 (Visual Workstation)"
424 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
425 depends on X86_32_NON_STANDARD
427 The SGI Visual Workstation series is an IA32-based workstation
428 based on SGI systems chips with some legacy PC hardware attached.
430 Say Y here to create a kernel to run on the SGI 320 or 540.
432 A kernel compiled for the Visual Workstation will run on general
433 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
436 bool "Summit/EXA (IBM x440)"
437 depends on X86_32_NON_STANDARD
439 This option is needed for IBM systems that use the Summit/EXA chipset.
440 In particular, it is needed for the x440.
443 bool "Unisys ES7000 IA32 series"
444 depends on X86_32_NON_STANDARD && X86_BIGSMP
446 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
447 supposed to run on an IA32-based Unisys ES7000 system.
449 config SCHED_OMIT_FRAME_POINTER
451 prompt "Single-depth WCHAN output"
454 Calculate simpler /proc/<PID>/wchan values. If this option
455 is disabled then wchan values will recurse back to the
456 caller function. This provides more accurate wchan values,
457 at the expense of slightly more scheduling overhead.
459 If in doubt, say "Y".
461 menuconfig PARAVIRT_GUEST
462 bool "Paravirtualized guest support"
464 Say Y here to get to see options related to running Linux under
465 various hypervisors. This option alone does not add any kernel code.
467 If you say N, all options in this submenu will be skipped and disabled.
471 source "arch/x86/xen/Kconfig"
474 bool "VMI Guest support"
478 VMI provides a paravirtualized interface to the VMware ESX server
479 (it could be used by other hypervisors in theory too, but is not
480 at the moment), by linking the kernel to a GPL-ed ROM module
481 provided by the hypervisor.
484 bool "KVM paravirtualized clock"
486 select PARAVIRT_CLOCK
488 Turning on this option will allow you to run a paravirtualized clock
489 when running over the KVM hypervisor. Instead of relying on a PIT
490 (or probably other) emulation by the underlying device model, the host
491 provides the guest with timing infrastructure such as time of day, and
495 bool "KVM Guest support"
498 This option enables various optimizations for running under the KVM
501 source "arch/x86/lguest/Kconfig"
504 bool "Enable paravirtualization code"
506 This changes the kernel so it can modify itself when it is run
507 under a hypervisor, potentially improving performance significantly
508 over full virtualization. However, when run without a hypervisor
509 the kernel is theoretically slower and slightly larger.
511 config PARAVIRT_SPINLOCKS
512 bool "Paravirtualization layer for spinlocks"
513 depends on PARAVIRT && SMP && EXPERIMENTAL
515 Paravirtualized spinlocks allow a pvops backend to replace the
516 spinlock implementation with something virtualization-friendly
517 (for example, block the virtual CPU rather than spinning).
519 Unfortunately the downside is an up to 5% performance hit on
520 native kernels, with various workloads.
522 If you are unsure how to answer this question, answer N.
524 config PARAVIRT_CLOCK
530 config PARAVIRT_DEBUG
531 bool "paravirt-ops debugging"
532 depends on PARAVIRT && DEBUG_KERNEL
534 Enable to debug paravirt_ops internals. Specifically, BUG if
535 a paravirt_op is missing when it is called.
540 This option adds a kernel parameter 'memtest', which allows memtest
542 memtest=0, mean disabled; -- default
543 memtest=1, mean do 1 test pattern;
545 memtest=4, mean do 4 test patterns.
546 If you are unsure how to answer this question, answer N.
548 config X86_SUMMIT_NUMA
550 depends on X86_32 && NUMA && X86_32_NON_STANDARD
552 config X86_CYCLONE_TIMER
554 depends on X86_32_NON_STANDARD
556 source "arch/x86/Kconfig.cpu"
560 prompt "HPET Timer Support" if X86_32
562 Use the IA-PC HPET (High Precision Event Timer) to manage
563 time in preference to the PIT and RTC, if a HPET is
565 HPET is the next generation timer replacing legacy 8254s.
566 The HPET provides a stable time base on SMP
567 systems, unlike the TSC, but it is more expensive to access,
568 as it is off-chip. You can find the HPET spec at
569 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
571 You can safely choose Y here. However, HPET will only be
572 activated if the platform and the BIOS support this feature.
573 Otherwise the 8254 will be used for timing services.
575 Choose N to continue using the legacy 8254 timer.
577 config HPET_EMULATE_RTC
579 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
581 # Mark as embedded because too many people got it wrong.
582 # The code disables itself when not needed.
585 bool "Enable DMI scanning" if EMBEDDED
587 Enabled scanning of DMI to identify machine quirks. Say Y
588 here unless you have verified that your setup is not
589 affected by entries in the DMI blacklist. Required by PNP
593 bool "GART IOMMU support" if EMBEDDED
596 depends on X86_64 && PCI
598 Support for full DMA access of devices with 32bit memory access only
599 on systems with more than 3GB. This is usually needed for USB,
600 sound, many IDE/SATA chipsets and some other devices.
601 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
602 based hardware IOMMU and a software bounce buffer based IOMMU used
603 on Intel systems and as fallback.
604 The code is only active when needed (enough memory and limited
605 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
609 bool "IBM Calgary IOMMU support"
611 depends on X86_64 && PCI && EXPERIMENTAL
613 Support for hardware IOMMUs in IBM's xSeries x366 and x460
614 systems. Needed to run systems with more than 3GB of memory
615 properly with 32-bit PCI devices that do not support DAC
616 (Double Address Cycle). Calgary also supports bus level
617 isolation, where all DMAs pass through the IOMMU. This
618 prevents them from going anywhere except their intended
619 destination. This catches hard-to-find kernel bugs and
620 mis-behaving drivers and devices that do not use the DMA-API
621 properly to set up their DMA buffers. The IOMMU can be
622 turned off at boot time with the iommu=off parameter.
623 Normally the kernel will make the right choice by itself.
626 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
628 prompt "Should Calgary be enabled by default?"
629 depends on CALGARY_IOMMU
631 Should Calgary be enabled by default? if you choose 'y', Calgary
632 will be used (if it exists). If you choose 'n', Calgary will not be
633 used even if it exists. If you choose 'n' and would like to use
634 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
638 bool "AMD IOMMU support"
641 depends on X86_64 && PCI && ACPI
643 With this option you can enable support for AMD IOMMU hardware in
644 your system. An IOMMU is a hardware component which provides
645 remapping of DMA memory accesses from devices. With an AMD IOMMU you
646 can isolate the the DMA memory of different devices and protect the
647 system from misbehaving device drivers or hardware.
649 You can find out if your system has an AMD IOMMU if you look into
650 your BIOS for an option to enable it or if you have an IVRS ACPI
653 config AMD_IOMMU_STATS
654 bool "Export AMD IOMMU statistics to debugfs"
658 This option enables code in the AMD IOMMU driver to collect various
659 statistics about whats happening in the driver and exports that
660 information to userspace via debugfs.
663 # need this always selected by IOMMU for the VIA workaround
667 Support for software bounce buffers used on x86-64 systems
668 which don't have a hardware IOMMU (e.g. the current generation
669 of Intel's x86-64 CPUs). Using this PCI devices which can only
670 access 32-bits of memory can be used on systems with more than
671 3 GB of memory. If unsure, say Y.
674 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
677 def_bool (AMD_IOMMU || DMAR)
680 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
681 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
682 select CPUMASK_OFFSTACK
685 Configure maximum number of CPUS and NUMA Nodes for this architecture.
689 int "Maximum number of CPUs" if SMP && !MAXSMP
690 range 2 8 if SMP && X86_32 && !X86_BIGSMP
691 range 2 512 if SMP && !MAXSMP
693 default "4096" if MAXSMP
694 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
697 This allows you to specify the maximum number of CPUs which this
698 kernel will support. The maximum supported value is 512 and the
699 minimum value which makes sense is 2.
701 This is purely to save memory - each supported CPU adds
702 approximately eight kilobytes to the kernel image.
705 bool "SMT (Hyperthreading) scheduler support"
708 SMT scheduler support improves the CPU scheduler's decision making
709 when dealing with Intel Pentium 4 chips with HyperThreading at a
710 cost of slightly increased overhead in some places. If unsure say
715 prompt "Multi-core scheduler support"
718 Multi-core scheduler support improves the CPU scheduler's decision
719 making when dealing with multi-core CPU chips at a cost of slightly
720 increased overhead in some places. If unsure say N here.
722 source "kernel/Kconfig.preempt"
725 bool "Local APIC support on uniprocessors"
726 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
728 A local APIC (Advanced Programmable Interrupt Controller) is an
729 integrated interrupt controller in the CPU. If you have a single-CPU
730 system which has a processor with a local APIC, you can say Y here to
731 enable and use it. If you say Y here even though your machine doesn't
732 have a local APIC, then the kernel will still run with no slowdown at
733 all. The local APIC supports CPU-generated self-interrupts (timer,
734 performance counters), and the NMI watchdog which detects hard
738 bool "IO-APIC support on uniprocessors"
739 depends on X86_UP_APIC
741 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
742 SMP-capable replacement for PC-style interrupt controllers. Most
743 SMP systems and many recent uniprocessor systems have one.
745 If you have a single-CPU system with an IO-APIC, you can say Y here
746 to use it. If you say Y here even though your machine doesn't have
747 an IO-APIC, then the kernel will still run with no slowdown at all.
749 config X86_LOCAL_APIC
751 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
755 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
757 config X86_VISWS_APIC
759 depends on X86_32 && X86_VISWS
761 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
762 bool "Reroute for broken boot IRQs"
764 depends on X86_IO_APIC
766 This option enables a workaround that fixes a source of
767 spurious interrupts. This is recommended when threaded
768 interrupt handling is used on systems where the generation of
769 superfluous "boot interrupts" cannot be disabled.
771 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
772 entry in the chipset's IO-APIC is masked (as, e.g. the RT
773 kernel does during interrupt handling). On chipsets where this
774 boot IRQ generation cannot be disabled, this workaround keeps
775 the original IRQ line masked so that only the equivalent "boot
776 IRQ" is delivered to the CPUs. The workaround also tells the
777 kernel to set up the IRQ handler on the boot IRQ line. In this
778 way only one interrupt is delivered to the kernel. Otherwise
779 the spurious second interrupt may cause the kernel to bring
780 down (vital) interrupt lines.
782 Only affects "broken" chipsets. Interrupt sharing may be
783 increased on these systems.
786 bool "Machine Check / overheating reporting"
788 Machine Check support allows the processor to notify the
789 kernel if it detects a problem (e.g. overheating, data corruption).
790 The action the kernel takes depends on the severity of the problem,
791 ranging from warning messages to halting the machine.
795 prompt "Intel MCE features"
796 depends on X86_MCE && X86_LOCAL_APIC
798 Additional support for intel specific MCE features such as
803 prompt "AMD MCE features"
804 depends on X86_MCE && X86_LOCAL_APIC
806 Additional support for AMD specific MCE features such as
807 the DRAM Error Threshold.
809 config X86_ANCIENT_MCE
811 depends on X86_32 && X86_MCE
812 prompt "Support for old Pentium 5 / WinChip machine checks"
814 Include support for machine check handling on old Pentium 5 or WinChip
815 systems. These typically need to be enabled explicitely on the command
818 config X86_MCE_THRESHOLD
819 depends on X86_MCE_AMD || X86_MCE_INTEL
823 config X86_MCE_INJECT
825 tristate "Machine check injector support"
827 Provide support for injecting machine checks for testing purposes.
828 If you don't know what a machine check is and you don't do kernel
829 QA it is safe to say n.
831 config X86_THERMAL_VECTOR
833 depends on X86_MCE_INTEL
836 bool "Enable VM86 support" if EMBEDDED
840 This option is required by programs like DOSEMU to run 16-bit legacy
841 code on X86 processors. It also may be needed by software like
842 XFree86 to initialize some video cards via BIOS. Disabling this
843 option saves about 6k.
846 tristate "Toshiba Laptop support"
849 This adds a driver to safely access the System Management Mode of
850 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
851 not work on models with a Phoenix BIOS. The System Management Mode
852 is used to set the BIOS and power saving options on Toshiba portables.
854 For information on utilities to make use of this driver see the
855 Toshiba Linux utilities web site at:
856 <http://www.buzzard.org.uk/toshiba/>.
858 Say Y if you intend to run this kernel on a Toshiba portable.
862 tristate "Dell laptop support"
864 This adds a driver to safely access the System Management Mode
865 of the CPU on the Dell Inspiron 8000. The System Management Mode
866 is used to read cpu temperature and cooling fan status and to
867 control the fans on the I8K portables.
869 This driver has been tested only on the Inspiron 8000 but it may
870 also work with other Dell laptops. You can force loading on other
871 models by passing the parameter `force=1' to the module. Use at
874 For information on utilities to make use of this driver see the
875 I8K Linux utilities web site at:
876 <http://people.debian.org/~dz/i8k/>
878 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
881 config X86_REBOOTFIXUPS
882 bool "Enable X86 board specific fixups for reboot"
885 This enables chipset and/or board specific fixups to be done
886 in order to get reboot to work correctly. This is only needed on
887 some combinations of hardware and BIOS. The symptom, for which
888 this config is intended, is when reboot ends with a stalled/hung
891 Currently, the only fixup is for the Geode machines using
892 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
894 Say Y if you want to enable the fixup. Currently, it's safe to
895 enable this option even if you don't need it.
899 tristate "/dev/cpu/microcode - microcode support"
902 If you say Y here, you will be able to update the microcode on
903 certain Intel and AMD processors. The Intel support is for the
904 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
905 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
906 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
907 You will obviously need the actual microcode binary data itself
908 which is not shipped with the Linux kernel.
910 This option selects the general module only, you need to select
911 at least one vendor specific module as well.
913 To compile this driver as a module, choose M here: the
914 module will be called microcode.
916 config MICROCODE_INTEL
917 bool "Intel microcode patch loading support"
922 This options enables microcode patch loading support for Intel
925 For latest news and information on obtaining all the required
926 Intel ingredients for this driver, check:
927 <http://www.urbanmyth.org/microcode/>.
930 bool "AMD microcode patch loading support"
934 If you select this option, microcode patch loading support for AMD
935 processors will be enabled.
937 config MICROCODE_OLD_INTERFACE
942 tristate "/dev/cpu/*/msr - Model-specific register support"
944 This device gives privileged processes access to the x86
945 Model-Specific Registers (MSRs). It is a character device with
946 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
947 MSR accesses are directed to a specific CPU on multi-processor
951 tristate "/dev/cpu/*/cpuid - CPU information support"
953 This device gives processes access to the x86 CPUID instruction to
954 be executed on a specific processor. It is a character device
955 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
959 tristate "/sys/kernel/debug/x86/cpu/* - CPU Debug support"
961 If you select this option, this will provide various x86 CPUs
962 information through debugfs.
965 prompt "High Memory Support"
966 default HIGHMEM4G if !X86_NUMAQ
967 default HIGHMEM64G if X86_NUMAQ
972 depends on !X86_NUMAQ
974 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
975 However, the address space of 32-bit x86 processors is only 4
976 Gigabytes large. That means that, if you have a large amount of
977 physical memory, not all of it can be "permanently mapped" by the
978 kernel. The physical memory that's not permanently mapped is called
981 If you are compiling a kernel which will never run on a machine with
982 more than 1 Gigabyte total physical RAM, answer "off" here (default
983 choice and suitable for most users). This will result in a "3GB/1GB"
984 split: 3GB are mapped so that each process sees a 3GB virtual memory
985 space and the remaining part of the 4GB virtual memory space is used
986 by the kernel to permanently map as much physical memory as
989 If the machine has between 1 and 4 Gigabytes physical RAM, then
992 If more than 4 Gigabytes is used then answer "64GB" here. This
993 selection turns Intel PAE (Physical Address Extension) mode on.
994 PAE implements 3-level paging on IA32 processors. PAE is fully
995 supported by Linux, PAE mode is implemented on all recent Intel
996 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
997 then the kernel will not boot on CPUs that don't support PAE!
999 The actual amount of total physical memory will either be
1000 auto detected or can be forced by using a kernel command line option
1001 such as "mem=256M". (Try "man bootparam" or see the documentation of
1002 your boot loader (lilo or loadlin) about how to pass options to the
1003 kernel at boot time.)
1005 If unsure, say "off".
1009 depends on !X86_NUMAQ
1011 Select this if you have a 32-bit processor and between 1 and 4
1012 gigabytes of physical RAM.
1016 depends on !M386 && !M486
1019 Select this if you have a 32-bit processor and more than 4
1020 gigabytes of physical RAM.
1025 depends on EXPERIMENTAL
1026 prompt "Memory split" if EMBEDDED
1030 Select the desired split between kernel and user memory.
1032 If the address range available to the kernel is less than the
1033 physical memory installed, the remaining memory will be available
1034 as "high memory". Accessing high memory is a little more costly
1035 than low memory, as it needs to be mapped into the kernel first.
1036 Note that increasing the kernel address space limits the range
1037 available to user programs, making the address space there
1038 tighter. Selecting anything other than the default 3G/1G split
1039 will also likely make your kernel incompatible with binary-only
1042 If you are not absolutely sure what you are doing, leave this
1046 bool "3G/1G user/kernel split"
1047 config VMSPLIT_3G_OPT
1049 bool "3G/1G user/kernel split (for full 1G low memory)"
1051 bool "2G/2G user/kernel split"
1052 config VMSPLIT_2G_OPT
1054 bool "2G/2G user/kernel split (for full 2G low memory)"
1056 bool "1G/3G user/kernel split"
1061 default 0xB0000000 if VMSPLIT_3G_OPT
1062 default 0x80000000 if VMSPLIT_2G
1063 default 0x78000000 if VMSPLIT_2G_OPT
1064 default 0x40000000 if VMSPLIT_1G
1070 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1073 bool "PAE (Physical Address Extension) Support"
1074 depends on X86_32 && !HIGHMEM4G
1076 PAE is required for NX support, and furthermore enables
1077 larger swapspace support for non-overcommit purposes. It
1078 has the cost of more pagetable lookup overhead, and also
1079 consumes more pagetable space per process.
1081 config ARCH_PHYS_ADDR_T_64BIT
1082 def_bool X86_64 || X86_PAE
1084 config DIRECT_GBPAGES
1085 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1089 Allow the kernel linear mapping to use 1GB pages on CPUs that
1090 support it. This can improve the kernel's performance a tiny bit by
1091 reducing TLB pressure. If in doubt, say "Y".
1093 # Common NUMA Features
1095 bool "Numa Memory Allocation and Scheduler Support"
1097 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1098 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1100 Enable NUMA (Non Uniform Memory Access) support.
1102 The kernel will try to allocate memory used by a CPU on the
1103 local memory controller of the CPU and add some more
1104 NUMA awareness to the kernel.
1106 For 64-bit this is recommended if the system is Intel Core i7
1107 (or later), AMD Opteron, or EM64T NUMA.
1109 For 32-bit this is only needed on (rare) 32-bit-only platforms
1110 that support NUMA topologies, such as NUMAQ / Summit, or if you
1111 boot a 32-bit kernel on a 64-bit NUMA platform.
1113 Otherwise, you should say N.
1115 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1116 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1120 prompt "Old style AMD Opteron NUMA detection"
1121 depends on X86_64 && NUMA && PCI
1123 Enable K8 NUMA node topology detection. You should say Y here if
1124 you have a multi processor AMD K8 system. This uses an old
1125 method to read the NUMA configuration directly from the builtin
1126 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1127 instead, which also takes priority if both are compiled in.
1129 config X86_64_ACPI_NUMA
1131 prompt "ACPI NUMA detection"
1132 depends on X86_64 && NUMA && ACPI && PCI
1135 Enable ACPI SRAT based node topology detection.
1137 # Some NUMA nodes have memory ranges that span
1138 # other nodes. Even though a pfn is valid and
1139 # between a node's start and end pfns, it may not
1140 # reside on that node. See memmap_init_zone()
1142 config NODES_SPAN_OTHER_NODES
1144 depends on X86_64_ACPI_NUMA
1147 bool "NUMA emulation"
1148 depends on X86_64 && NUMA
1150 Enable NUMA emulation. A flat machine will be split
1151 into virtual nodes when booted with "numa=fake=N", where N is the
1152 number of nodes. This is only useful for debugging.
1155 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1157 default "9" if MAXSMP
1158 default "6" if X86_64
1159 default "4" if X86_NUMAQ
1161 depends on NEED_MULTIPLE_NODES
1163 Specify the maximum number of NUMA Nodes available on the target
1164 system. Increases memory reserved to accommodate various tables.
1166 config HAVE_ARCH_BOOTMEM
1168 depends on X86_32 && NUMA
1170 config ARCH_HAVE_MEMORY_PRESENT
1172 depends on X86_32 && DISCONTIGMEM
1174 config NEED_NODE_MEMMAP_SIZE
1176 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1178 config HAVE_ARCH_ALLOC_REMAP
1180 depends on X86_32 && NUMA
1182 config ARCH_FLATMEM_ENABLE
1184 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1186 config ARCH_DISCONTIGMEM_ENABLE
1188 depends on NUMA && X86_32
1190 config ARCH_DISCONTIGMEM_DEFAULT
1192 depends on NUMA && X86_32
1194 config ARCH_SPARSEMEM_DEFAULT
1198 config ARCH_SPARSEMEM_ENABLE
1200 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1201 select SPARSEMEM_STATIC if X86_32
1202 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1204 config ARCH_SELECT_MEMORY_MODEL
1206 depends on ARCH_SPARSEMEM_ENABLE
1208 config ARCH_MEMORY_PROBE
1210 depends on MEMORY_HOTPLUG
1215 bool "Allocate 3rd-level pagetables from highmem"
1216 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1218 The VM uses one page table entry for each page of physical memory.
1219 For systems with a lot of RAM, this can be wasteful of precious
1220 low memory. Setting this option will put user-space page table
1221 entries in high memory.
1223 config X86_CHECK_BIOS_CORRUPTION
1224 bool "Check for low memory corruption"
1226 Periodically check for memory corruption in low memory, which
1227 is suspected to be caused by BIOS. Even when enabled in the
1228 configuration, it is disabled at runtime. Enable it by
1229 setting "memory_corruption_check=1" on the kernel command
1230 line. By default it scans the low 64k of memory every 60
1231 seconds; see the memory_corruption_check_size and
1232 memory_corruption_check_period parameters in
1233 Documentation/kernel-parameters.txt to adjust this.
1235 When enabled with the default parameters, this option has
1236 almost no overhead, as it reserves a relatively small amount
1237 of memory and scans it infrequently. It both detects corruption
1238 and prevents it from affecting the running system.
1240 It is, however, intended as a diagnostic tool; if repeatable
1241 BIOS-originated corruption always affects the same memory,
1242 you can use memmap= to prevent the kernel from using that
1245 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1246 bool "Set the default setting of memory_corruption_check"
1247 depends on X86_CHECK_BIOS_CORRUPTION
1250 Set whether the default state of memory_corruption_check is
1253 config X86_RESERVE_LOW_64K
1254 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1257 Reserve the first 64K of physical RAM on BIOSes that are known
1258 to potentially corrupt that memory range. A numbers of BIOSes are
1259 known to utilize this area during suspend/resume, so it must not
1260 be used by the kernel.
1262 Set this to N if you are absolutely sure that you trust the BIOS
1263 to get all its memory reservations and usages right.
1265 If you have doubts about the BIOS (e.g. suspend/resume does not
1266 work or there's kernel crashes after certain hardware hotplug
1267 events) and it's not AMI or Phoenix, then you might want to enable
1268 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1269 corruption patterns.
1273 config MATH_EMULATION
1275 prompt "Math emulation" if X86_32
1277 Linux can emulate a math coprocessor (used for floating point
1278 operations) if you don't have one. 486DX and Pentium processors have
1279 a math coprocessor built in, 486SX and 386 do not, unless you added
1280 a 487DX or 387, respectively. (The messages during boot time can
1281 give you some hints here ["man dmesg"].) Everyone needs either a
1282 coprocessor or this emulation.
1284 If you don't have a math coprocessor, you need to say Y here; if you
1285 say Y here even though you have a coprocessor, the coprocessor will
1286 be used nevertheless. (This behavior can be changed with the kernel
1287 command line option "no387", which comes handy if your coprocessor
1288 is broken. Try "man bootparam" or see the documentation of your boot
1289 loader (lilo or loadlin) about how to pass options to the kernel at
1290 boot time.) This means that it is a good idea to say Y here if you
1291 intend to use this kernel on different machines.
1293 More information about the internals of the Linux math coprocessor
1294 emulation can be found in <file:arch/x86/math-emu/README>.
1296 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1297 kernel, it won't hurt.
1300 bool "MTRR (Memory Type Range Register) support"
1302 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1303 the Memory Type Range Registers (MTRRs) may be used to control
1304 processor access to memory ranges. This is most useful if you have
1305 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1306 allows bus write transfers to be combined into a larger transfer
1307 before bursting over the PCI/AGP bus. This can increase performance
1308 of image write operations 2.5 times or more. Saying Y here creates a
1309 /proc/mtrr file which may be used to manipulate your processor's
1310 MTRRs. Typically the X server should use this.
1312 This code has a reasonably generic interface so that similar
1313 control registers on other processors can be easily supported
1316 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1317 Registers (ARRs) which provide a similar functionality to MTRRs. For
1318 these, the ARRs are used to emulate the MTRRs.
1319 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1320 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1321 write-combining. All of these processors are supported by this code
1322 and it makes sense to say Y here if you have one of them.
1324 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1325 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1326 can lead to all sorts of problems, so it's good to say Y here.
1328 You can safely say Y even if your machine doesn't have MTRRs, you'll
1329 just add about 9 KB to your kernel.
1331 See <file:Documentation/x86/mtrr.txt> for more information.
1333 config MTRR_SANITIZER
1335 prompt "MTRR cleanup support"
1338 Convert MTRR layout from continuous to discrete, so X drivers can
1339 add writeback entries.
1341 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1342 The largest mtrr entry size for a continuous block can be set with
1347 config MTRR_SANITIZER_ENABLE_DEFAULT
1348 int "MTRR cleanup enable value (0-1)"
1351 depends on MTRR_SANITIZER
1353 Enable mtrr cleanup default value
1355 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1356 int "MTRR cleanup spare reg num (0-7)"
1359 depends on MTRR_SANITIZER
1361 mtrr cleanup spare entries default, it can be changed via
1362 mtrr_spare_reg_nr=N on the kernel command line.
1366 prompt "x86 PAT support"
1369 Use PAT attributes to setup page level cache control.
1371 PATs are the modern equivalents of MTRRs and are much more
1372 flexible than MTRRs.
1374 Say N here if you see bootup problems (boot crash, boot hang,
1375 spontaneous reboots) or a non-working video driver.
1379 config ARCH_USES_PG_UNCACHED
1384 bool "EFI runtime service support"
1387 This enables the kernel to use EFI runtime services that are
1388 available (such as the EFI variable services).
1390 This option is only useful on systems that have EFI firmware.
1391 In addition, you should use the latest ELILO loader available
1392 at <http://elilo.sourceforge.net> in order to take advantage
1393 of EFI runtime services. However, even with this option, the
1394 resultant kernel should continue to boot on existing non-EFI
1399 prompt "Enable seccomp to safely compute untrusted bytecode"
1401 This kernel feature is useful for number crunching applications
1402 that may need to compute untrusted bytecode during their
1403 execution. By using pipes or other transports made available to
1404 the process as file descriptors supporting the read/write
1405 syscalls, it's possible to isolate those applications in
1406 their own address space using seccomp. Once seccomp is
1407 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1408 and the task is only allowed to execute a few safe syscalls
1409 defined by each seccomp mode.
1411 If unsure, say Y. Only embedded should say N here.
1413 config CC_STACKPROTECTOR_ALL
1416 config CC_STACKPROTECTOR
1417 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1418 select CC_STACKPROTECTOR_ALL
1420 This option turns on the -fstack-protector GCC feature. This
1421 feature puts, at the beginning of functions, a canary value on
1422 the stack just before the return address, and validates
1423 the value just before actually returning. Stack based buffer
1424 overflows (that need to overwrite this return address) now also
1425 overwrite the canary, which gets detected and the attack is then
1426 neutralized via a kernel panic.
1428 This feature requires gcc version 4.2 or above, or a distribution
1429 gcc with the feature backported. Older versions are automatically
1430 detected and for those versions, this configuration option is
1431 ignored. (and a warning is printed during bootup)
1433 source kernel/Kconfig.hz
1436 bool "kexec system call"
1438 kexec is a system call that implements the ability to shutdown your
1439 current kernel, and to start another kernel. It is like a reboot
1440 but it is independent of the system firmware. And like a reboot
1441 you can start any kernel with it, not just Linux.
1443 The name comes from the similarity to the exec system call.
1445 It is an ongoing process to be certain the hardware in a machine
1446 is properly shutdown, so do not be surprised if this code does not
1447 initially work for you. It may help to enable device hotplugging
1448 support. As of this writing the exact hardware interface is
1449 strongly in flux, so no good recommendation can be made.
1452 bool "kernel crash dumps"
1453 depends on X86_64 || (X86_32 && HIGHMEM)
1455 Generate crash dump after being started by kexec.
1456 This should be normally only set in special crash dump kernels
1457 which are loaded in the main kernel with kexec-tools into
1458 a specially reserved region and then later executed after
1459 a crash by kdump/kexec. The crash dump kernel must be compiled
1460 to a memory address not used by the main kernel or BIOS using
1461 PHYSICAL_START, or it must be built as a relocatable image
1462 (CONFIG_RELOCATABLE=y).
1463 For more details see Documentation/kdump/kdump.txt
1466 bool "kexec jump (EXPERIMENTAL)"
1467 depends on EXPERIMENTAL
1468 depends on KEXEC && HIBERNATION
1470 Jump between original kernel and kexeced kernel and invoke
1471 code in physical address mode via KEXEC
1473 config PHYSICAL_START
1474 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1477 This gives the physical address where the kernel is loaded.
1479 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1480 bzImage will decompress itself to above physical address and
1481 run from there. Otherwise, bzImage will run from the address where
1482 it has been loaded by the boot loader and will ignore above physical
1485 In normal kdump cases one does not have to set/change this option
1486 as now bzImage can be compiled as a completely relocatable image
1487 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1488 address. This option is mainly useful for the folks who don't want
1489 to use a bzImage for capturing the crash dump and want to use a
1490 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1491 to be specifically compiled to run from a specific memory area
1492 (normally a reserved region) and this option comes handy.
1494 So if you are using bzImage for capturing the crash dump,
1495 leave the value here unchanged to 0x1000000 and set
1496 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1497 for capturing the crash dump change this value to start of
1498 the reserved region. In other words, it can be set based on
1499 the "X" value as specified in the "crashkernel=YM@XM"
1500 command line boot parameter passed to the panic-ed
1501 kernel. Please take a look at Documentation/kdump/kdump.txt
1502 for more details about crash dumps.
1504 Usage of bzImage for capturing the crash dump is recommended as
1505 one does not have to build two kernels. Same kernel can be used
1506 as production kernel and capture kernel. Above option should have
1507 gone away after relocatable bzImage support is introduced. But it
1508 is present because there are users out there who continue to use
1509 vmlinux for dump capture. This option should go away down the
1512 Don't change this unless you know what you are doing.
1515 bool "Build a relocatable kernel"
1518 This builds a kernel image that retains relocation information
1519 so it can be loaded someplace besides the default 1MB.
1520 The relocations tend to make the kernel binary about 10% larger,
1521 but are discarded at runtime.
1523 One use is for the kexec on panic case where the recovery kernel
1524 must live at a different physical address than the primary
1527 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1528 it has been loaded at and the compile time physical address
1529 (CONFIG_PHYSICAL_START) is ignored.
1531 # Relocation on x86-32 needs some additional build support
1532 config X86_NEED_RELOCS
1534 depends on X86_32 && RELOCATABLE
1536 config PHYSICAL_ALIGN
1538 prompt "Alignment value to which kernel should be aligned" if X86_32
1540 range 0x2000 0x1000000
1542 This value puts the alignment restrictions on physical address
1543 where kernel is loaded and run from. Kernel is compiled for an
1544 address which meets above alignment restriction.
1546 If bootloader loads the kernel at a non-aligned address and
1547 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1548 address aligned to above value and run from there.
1550 If bootloader loads the kernel at a non-aligned address and
1551 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1552 load address and decompress itself to the address it has been
1553 compiled for and run from there. The address for which kernel is
1554 compiled already meets above alignment restrictions. Hence the
1555 end result is that kernel runs from a physical address meeting
1556 above alignment restrictions.
1558 Don't change this unless you know what you are doing.
1561 bool "Support for hot-pluggable CPUs"
1562 depends on SMP && HOTPLUG
1564 Say Y here to allow turning CPUs off and on. CPUs can be
1565 controlled through /sys/devices/system/cpu.
1566 ( Note: power management support will enable this option
1567 automatically on SMP systems. )
1568 Say N if you want to disable CPU hotplug.
1572 prompt "Compat VDSO support"
1573 depends on X86_32 || IA32_EMULATION
1575 Map the 32-bit VDSO to the predictable old-style address too.
1577 Say N here if you are running a sufficiently recent glibc
1578 version (2.3.3 or later), to remove the high-mapped
1579 VDSO mapping and to exclusively use the randomized VDSO.
1584 bool "Built-in kernel command line"
1587 Allow for specifying boot arguments to the kernel at
1588 build time. On some systems (e.g. embedded ones), it is
1589 necessary or convenient to provide some or all of the
1590 kernel boot arguments with the kernel itself (that is,
1591 to not rely on the boot loader to provide them.)
1593 To compile command line arguments into the kernel,
1594 set this option to 'Y', then fill in the
1595 the boot arguments in CONFIG_CMDLINE.
1597 Systems with fully functional boot loaders (i.e. non-embedded)
1598 should leave this option set to 'N'.
1601 string "Built-in kernel command string"
1602 depends on CMDLINE_BOOL
1605 Enter arguments here that should be compiled into the kernel
1606 image and used at boot time. If the boot loader provides a
1607 command line at boot time, it is appended to this string to
1608 form the full kernel command line, when the system boots.
1610 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1611 change this behavior.
1613 In most cases, the command line (whether built-in or provided
1614 by the boot loader) should specify the device for the root
1617 config CMDLINE_OVERRIDE
1618 bool "Built-in command line overrides boot loader arguments"
1620 depends on CMDLINE_BOOL
1622 Set this option to 'Y' to have the kernel ignore the boot loader
1623 command line, and use ONLY the built-in command line.
1625 This is used to work around broken boot loaders. This should
1626 be set to 'N' under normal conditions.
1630 config ARCH_ENABLE_MEMORY_HOTPLUG
1632 depends on X86_64 || (X86_32 && HIGHMEM)
1634 config ARCH_ENABLE_MEMORY_HOTREMOVE
1636 depends on MEMORY_HOTPLUG
1638 config HAVE_ARCH_EARLY_PFN_TO_NID
1642 menu "Power management and ACPI options"
1644 config ARCH_HIBERNATION_HEADER
1646 depends on X86_64 && HIBERNATION
1648 source "kernel/power/Kconfig"
1650 source "drivers/acpi/Kconfig"
1655 depends on APM || APM_MODULE
1658 tristate "APM (Advanced Power Management) BIOS support"
1659 depends on X86_32 && PM_SLEEP
1661 APM is a BIOS specification for saving power using several different
1662 techniques. This is mostly useful for battery powered laptops with
1663 APM compliant BIOSes. If you say Y here, the system time will be
1664 reset after a RESUME operation, the /proc/apm device will provide
1665 battery status information, and user-space programs will receive
1666 notification of APM "events" (e.g. battery status change).
1668 If you select "Y" here, you can disable actual use of the APM
1669 BIOS by passing the "apm=off" option to the kernel at boot time.
1671 Note that the APM support is almost completely disabled for
1672 machines with more than one CPU.
1674 In order to use APM, you will need supporting software. For location
1675 and more information, read <file:Documentation/power/pm.txt> and the
1676 Battery Powered Linux mini-HOWTO, available from
1677 <http://www.tldp.org/docs.html#howto>.
1679 This driver does not spin down disk drives (see the hdparm(8)
1680 manpage ("man 8 hdparm") for that), and it doesn't turn off
1681 VESA-compliant "green" monitors.
1683 This driver does not support the TI 4000M TravelMate and the ACER
1684 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1685 desktop machines also don't have compliant BIOSes, and this driver
1686 may cause those machines to panic during the boot phase.
1688 Generally, if you don't have a battery in your machine, there isn't
1689 much point in using this driver and you should say N. If you get
1690 random kernel OOPSes or reboots that don't seem to be related to
1691 anything, try disabling/enabling this option (or disabling/enabling
1694 Some other things you should try when experiencing seemingly random,
1697 1) make sure that you have enough swap space and that it is
1699 2) pass the "no-hlt" option to the kernel
1700 3) switch on floating point emulation in the kernel and pass
1701 the "no387" option to the kernel
1702 4) pass the "floppy=nodma" option to the kernel
1703 5) pass the "mem=4M" option to the kernel (thereby disabling
1704 all but the first 4 MB of RAM)
1705 6) make sure that the CPU is not over clocked.
1706 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1707 8) disable the cache from your BIOS settings
1708 9) install a fan for the video card or exchange video RAM
1709 10) install a better fan for the CPU
1710 11) exchange RAM chips
1711 12) exchange the motherboard.
1713 To compile this driver as a module, choose M here: the
1714 module will be called apm.
1718 config APM_IGNORE_USER_SUSPEND
1719 bool "Ignore USER SUSPEND"
1721 This option will ignore USER SUSPEND requests. On machines with a
1722 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1723 series notebooks, it is necessary to say Y because of a BIOS bug.
1725 config APM_DO_ENABLE
1726 bool "Enable PM at boot time"
1728 Enable APM features at boot time. From page 36 of the APM BIOS
1729 specification: "When disabled, the APM BIOS does not automatically
1730 power manage devices, enter the Standby State, enter the Suspend
1731 State, or take power saving steps in response to CPU Idle calls."
1732 This driver will make CPU Idle calls when Linux is idle (unless this
1733 feature is turned off -- see "Do CPU IDLE calls", below). This
1734 should always save battery power, but more complicated APM features
1735 will be dependent on your BIOS implementation. You may need to turn
1736 this option off if your computer hangs at boot time when using APM
1737 support, or if it beeps continuously instead of suspending. Turn
1738 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1739 T400CDT. This is off by default since most machines do fine without
1743 bool "Make CPU Idle calls when idle"
1745 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1746 On some machines, this can activate improved power savings, such as
1747 a slowed CPU clock rate, when the machine is idle. These idle calls
1748 are made after the idle loop has run for some length of time (e.g.,
1749 333 mS). On some machines, this will cause a hang at boot time or
1750 whenever the CPU becomes idle. (On machines with more than one CPU,
1751 this option does nothing.)
1753 config APM_DISPLAY_BLANK
1754 bool "Enable console blanking using APM"
1756 Enable console blanking using the APM. Some laptops can use this to
1757 turn off the LCD backlight when the screen blanker of the Linux
1758 virtual console blanks the screen. Note that this is only used by
1759 the virtual console screen blanker, and won't turn off the backlight
1760 when using the X Window system. This also doesn't have anything to
1761 do with your VESA-compliant power-saving monitor. Further, this
1762 option doesn't work for all laptops -- it might not turn off your
1763 backlight at all, or it might print a lot of errors to the console,
1764 especially if you are using gpm.
1766 config APM_ALLOW_INTS
1767 bool "Allow interrupts during APM BIOS calls"
1769 Normally we disable external interrupts while we are making calls to
1770 the APM BIOS as a measure to lessen the effects of a badly behaving
1771 BIOS implementation. The BIOS should reenable interrupts if it
1772 needs to. Unfortunately, some BIOSes do not -- especially those in
1773 many of the newer IBM Thinkpads. If you experience hangs when you
1774 suspend, try setting this to Y. Otherwise, say N.
1778 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1780 source "drivers/cpuidle/Kconfig"
1782 source "drivers/idle/Kconfig"
1787 menu "Bus options (PCI etc.)"
1792 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1794 Find out whether you have a PCI motherboard. PCI is the name of a
1795 bus system, i.e. the way the CPU talks to the other stuff inside
1796 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1797 VESA. If you have PCI, say Y, otherwise N.
1800 prompt "PCI access mode"
1801 depends on X86_32 && PCI
1804 On PCI systems, the BIOS can be used to detect the PCI devices and
1805 determine their configuration. However, some old PCI motherboards
1806 have BIOS bugs and may crash if this is done. Also, some embedded
1807 PCI-based systems don't have any BIOS at all. Linux can also try to
1808 detect the PCI hardware directly without using the BIOS.
1810 With this option, you can specify how Linux should detect the
1811 PCI devices. If you choose "BIOS", the BIOS will be used,
1812 if you choose "Direct", the BIOS won't be used, and if you
1813 choose "MMConfig", then PCI Express MMCONFIG will be used.
1814 If you choose "Any", the kernel will try MMCONFIG, then the
1815 direct access method and falls back to the BIOS if that doesn't
1816 work. If unsure, go with the default, which is "Any".
1821 config PCI_GOMMCONFIG
1838 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1840 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1843 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1847 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1851 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1858 bool "Support mmconfig PCI config space access"
1859 depends on X86_64 && PCI && ACPI
1862 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1863 depends on PCI_MSI && ACPI && EXPERIMENTAL
1865 DMA remapping (DMAR) devices support enables independent address
1866 translations for Direct Memory Access (DMA) from devices.
1867 These DMA remapping devices are reported via ACPI tables
1868 and include PCI device scope covered by these DMA
1871 config DMAR_DEFAULT_ON
1873 prompt "Enable DMA Remapping Devices by default"
1876 Selecting this option will enable a DMAR device at boot time if
1877 one is found. If this option is not selected, DMAR support can
1878 be enabled by passing intel_iommu=on to the kernel. It is
1879 recommended you say N here while the DMAR code remains
1882 config DMAR_BROKEN_GFX_WA
1884 prompt "Workaround broken graphics drivers (going away soon)"
1887 Current Graphics drivers tend to use physical address
1888 for DMA and avoid using DMA APIs. Setting this config
1889 option permits the IOMMU driver to set a unity map for
1890 all the OS-visible memory. Hence the driver can continue
1891 to use physical addresses for DMA, at least until this
1892 option is removed in the 2.6.32 kernel.
1894 config DMAR_FLOPPY_WA
1898 Floppy disk drivers are known to bypass DMA API calls
1899 thereby failing to work when IOMMU is enabled. This
1900 workaround will setup a 1:1 mapping for the first
1901 16MiB to make floppy (an ISA device) work.
1904 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1905 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1907 Supports Interrupt remapping for IO-APIC and MSI devices.
1908 To use x2apic mode in the CPU's which support x2APIC enhancements or
1909 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1911 source "drivers/pci/pcie/Kconfig"
1913 source "drivers/pci/Kconfig"
1915 # x86_64 have no ISA slots, but do have ISA-style DMA.
1924 Find out whether you have ISA slots on your motherboard. ISA is the
1925 name of a bus system, i.e. the way the CPU talks to the other stuff
1926 inside your box. Other bus systems are PCI, EISA, MicroChannel
1927 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1928 newer boards don't support it. If you have ISA, say Y, otherwise N.
1934 The Extended Industry Standard Architecture (EISA) bus was
1935 developed as an open alternative to the IBM MicroChannel bus.
1937 The EISA bus provided some of the features of the IBM MicroChannel
1938 bus while maintaining backward compatibility with cards made for
1939 the older ISA bus. The EISA bus saw limited use between 1988 and
1940 1995 when it was made obsolete by the PCI bus.
1942 Say Y here if you are building a kernel for an EISA-based machine.
1946 source "drivers/eisa/Kconfig"
1951 MicroChannel Architecture is found in some IBM PS/2 machines and
1952 laptops. It is a bus system similar to PCI or ISA. See
1953 <file:Documentation/mca.txt> (and especially the web page given
1954 there) before attempting to build an MCA bus kernel.
1956 source "drivers/mca/Kconfig"
1959 tristate "NatSemi SCx200 support"
1961 This provides basic support for National Semiconductor's
1962 (now AMD's) Geode processors. The driver probes for the
1963 PCI-IDs of several on-chip devices, so its a good dependency
1964 for other scx200_* drivers.
1966 If compiled as a module, the driver is named scx200.
1968 config SCx200HR_TIMER
1969 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1970 depends on SCx200 && GENERIC_TIME
1973 This driver provides a clocksource built upon the on-chip
1974 27MHz high-resolution timer. Its also a workaround for
1975 NSC Geode SC-1100's buggy TSC, which loses time when the
1976 processor goes idle (as is done by the scheduler). The
1977 other workaround is idle=poll boot option.
1979 config GEODE_MFGPT_TIMER
1981 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1982 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1984 This driver provides a clock event source based on the MFGPT
1985 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1986 MFGPTs have a better resolution and max interval than the
1987 generic PIT, and are suitable for use as high-res timers.
1990 bool "One Laptop Per Child support"
1993 Add support for detecting the unique features of the OLPC
2000 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
2002 source "drivers/pcmcia/Kconfig"
2004 source "drivers/pci/hotplug/Kconfig"
2009 menu "Executable file formats / Emulations"
2011 source "fs/Kconfig.binfmt"
2013 config IA32_EMULATION
2014 bool "IA32 Emulation"
2016 select COMPAT_BINFMT_ELF
2018 Include code to run 32-bit programs under a 64-bit kernel. You should
2019 likely turn this on, unless you're 100% sure that you don't have any
2020 32-bit programs left.
2023 tristate "IA32 a.out support"
2024 depends on IA32_EMULATION
2026 Support old a.out binaries in the 32bit emulation.
2030 depends on IA32_EMULATION
2032 config COMPAT_FOR_U64_ALIGNMENT
2036 config SYSVIPC_COMPAT
2038 depends on COMPAT && SYSVIPC
2043 config HAVE_ATOMIC_IOMAP
2047 source "net/Kconfig"
2049 source "drivers/Kconfig"
2051 source "drivers/firmware/Kconfig"
2055 source "arch/x86/Kconfig.debug"
2057 source "security/Kconfig"
2059 source "crypto/Kconfig"
2061 source "arch/x86/kvm/Kconfig"
2063 source "lib/Kconfig"