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_IOREMAP_PROT
29 select ARCH_WANT_OPTIONAL_GPIOLIB
30 select ARCH_WANT_FRAME_POINTERS
31 select HAVE_KRETPROBES
32 select HAVE_FTRACE_MCOUNT_RECORD
33 select HAVE_DYNAMIC_FTRACE
34 select HAVE_FUNCTION_TRACER
35 select HAVE_FUNCTION_GRAPH_TRACER
36 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
39 select HAVE_ARCH_TRACEHOOK
40 select HAVE_GENERIC_DMA_COHERENT if X86_32
41 select HAVE_EFFICIENT_UNALIGNED_ACCESS
42 select USER_STACKTRACE_SUPPORT
46 default "arch/x86/configs/i386_defconfig" if X86_32
47 default "arch/x86/configs/x86_64_defconfig" if X86_64
52 config GENERIC_CMOS_UPDATE
55 config CLOCKSOURCE_WATCHDOG
58 config GENERIC_CLOCKEVENTS
61 config GENERIC_CLOCKEVENTS_BROADCAST
63 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
65 config LOCKDEP_SUPPORT
68 config STACKTRACE_SUPPORT
71 config HAVE_LATENCYTOP_SUPPORT
74 config FAST_CMPXCHG_LOCAL
87 config GENERIC_ISA_DMA
96 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
98 config GENERIC_BUG_RELATIVE_POINTERS
101 config GENERIC_HWEIGHT
107 config ARCH_MAY_HAVE_PC_FDC
110 config RWSEM_GENERIC_SPINLOCK
113 config RWSEM_XCHGADD_ALGORITHM
116 config ARCH_HAS_CPU_IDLE_WAIT
119 config GENERIC_CALIBRATE_DELAY
122 config GENERIC_TIME_VSYSCALL
126 config ARCH_HAS_CPU_RELAX
129 config ARCH_HAS_DEFAULT_IDLE
132 config ARCH_HAS_CACHE_LINE_SIZE
135 config HAVE_SETUP_PER_CPU_AREA
138 config HAVE_CPUMASK_OF_CPU_MAP
141 config ARCH_HIBERNATION_POSSIBLE
145 config ARCH_SUSPEND_POSSIBLE
152 config ARCH_POPULATES_NODE_MAP
159 config ARCH_SUPPORTS_OPTIMIZED_INLINING
162 # Use the generic interrupt handling code in kernel/irq/:
163 config GENERIC_HARDIRQS
167 config GENERIC_IRQ_PROBE
171 config GENERIC_PENDING_IRQ
173 depends on GENERIC_HARDIRQS && SMP
178 depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
181 config USE_GENERIC_SMP_HELPERS
187 depends on X86_32 && SMP
191 depends on X86_64 && SMP
196 depends on (X86_32 && !X86_VOYAGER) || X86_64
199 config X86_BIOS_REBOOT
201 depends on !X86_VOYAGER
204 config X86_TRAMPOLINE
206 depends on X86_SMP || (X86_VOYAGER && SMP) || (64BIT && ACPI_SLEEP)
211 source "init/Kconfig"
212 source "kernel/Kconfig.freezer"
214 menu "Processor type and features"
216 source "kernel/time/Kconfig"
219 bool "Symmetric multi-processing support"
221 This enables support for systems with more than one CPU. If you have
222 a system with only one CPU, like most personal computers, say N. If
223 you have a system with more than one CPU, say Y.
225 If you say N here, the kernel will run on single and multiprocessor
226 machines, but will use only one CPU of a multiprocessor machine. If
227 you say Y here, the kernel will run on many, but not all,
228 singleprocessor machines. On a singleprocessor machine, the kernel
229 will run faster if you say N here.
231 Note that if you say Y here and choose architecture "586" or
232 "Pentium" under "Processor family", the kernel will not work on 486
233 architectures. Similarly, multiprocessor kernels for the "PPro"
234 architecture may not work on all Pentium based boards.
236 People using multiprocessor machines who say Y here should also say
237 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
238 Management" code will be disabled if you say Y here.
240 See also <file:Documentation/i386/IO-APIC.txt>,
241 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
242 <http://www.tldp.org/docs.html#howto>.
244 If you don't know what to do here, say N.
246 config X86_HAS_BOOT_CPU_ID
248 depends on X86_VOYAGER
251 bool "Support sparse irq numbering"
252 depends on PCI_MSI || HT_IRQ
254 This enables support for sparse irqs. This is useful for distro
255 kernels that want to define a high CONFIG_NR_CPUS value but still
256 want to have low kernel memory footprint on smaller machines.
258 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
259 out the irq_desc[] array in a more NUMA-friendly way. )
261 If you don't know what to do here, say N.
263 config NUMA_MIGRATE_IRQ_DESC
264 bool "Move irq desc when changing irq smp_affinity"
265 depends on SPARSE_IRQ && NUMA
268 This enables moving irq_desc to cpu/node that irq will use handled.
270 If you don't know what to do here, say N.
272 config X86_FIND_SMP_CONFIG
274 depends on X86_MPPARSE || X86_VOYAGER
277 bool "Enable MPS table" if ACPI
279 depends on X86_LOCAL_APIC
281 For old smp systems that do not have proper acpi support. Newer systems
282 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
285 prompt "Subarchitecture Type"
291 Choose this option if your computer is a standard PC or compatible.
297 Select this for an AMD Elan processor.
299 Do not use this option for K6/Athlon/Opteron processors!
301 If unsure, choose "PC-compatible" instead.
305 depends on X86_32 && SMP && !PCI && BROKEN
307 Voyager is an MCA-based 32-way capable SMP architecture proprietary
308 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
312 If you do not specifically know you have a Voyager based machine,
313 say N here, otherwise the kernel you build will not be bootable.
315 config X86_GENERICARCH
316 bool "Generic architecture"
319 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
320 subarchitectures. It is intended for a generic binary kernel.
321 if you select them all, kernel will probe it one by one. and will
327 bool "NUMAQ (IBM/Sequent)"
328 depends on SMP && X86_32 && PCI && X86_MPPARSE
331 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
332 NUMA multiquad box. This changes the way that processors are
333 bootstrapped, and uses Clustered Logical APIC addressing mode instead
334 of Flat Logical. You will need a new lynxer.elf file to flash your
335 firmware with - send email to <Martin.Bligh@us.ibm.com>.
338 bool "Summit/EXA (IBM x440)"
339 depends on X86_32 && SMP
341 This option is needed for IBM systems that use the Summit/EXA chipset.
342 In particular, it is needed for the x440.
345 bool "Support for Unisys ES7000 IA32 series"
346 depends on X86_32 && SMP
348 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
349 supposed to run on an IA32-based Unisys ES7000 system.
352 bool "Support for big SMP systems with more than 8 CPUs"
353 depends on X86_32 && SMP
355 This option is needed for the systems that have more than 8 CPUs
356 and if the system is not of any sub-arch type above.
361 bool "Support for ScaleMP vSMP"
363 depends on X86_64 && PCI
365 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
366 supposed to run on these EM64T-based machines. Only choose this option
367 if you have one of these machines.
372 bool "SGI 320/540 (Visual Workstation)"
373 depends on X86_32 && PCI && !X86_VOYAGER && X86_MPPARSE && PCI_GODIRECT
375 The SGI Visual Workstation series is an IA32-based workstation
376 based on SGI systems chips with some legacy PC hardware attached.
378 Say Y here to create a kernel to run on the SGI 320 or 540.
380 A kernel compiled for the Visual Workstation will run on general
381 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
384 bool "RDC R-321x SoC"
387 select X86_REBOOTFIXUPS
389 This option is needed for RDC R-321x system-on-chip, also known
391 If you don't have one of these chips, you should say N here.
394 bool "SGI Ultraviolet"
397 This option is needed in order to support SGI Ultraviolet systems.
398 If you don't have one of these, you should say N here.
400 config SCHED_OMIT_FRAME_POINTER
402 prompt "Single-depth WCHAN output"
405 Calculate simpler /proc/<PID>/wchan values. If this option
406 is disabled then wchan values will recurse back to the
407 caller function. This provides more accurate wchan values,
408 at the expense of slightly more scheduling overhead.
410 If in doubt, say "Y".
412 menuconfig PARAVIRT_GUEST
413 bool "Paravirtualized guest support"
415 Say Y here to get to see options related to running Linux under
416 various hypervisors. This option alone does not add any kernel code.
418 If you say N, all options in this submenu will be skipped and disabled.
422 source "arch/x86/xen/Kconfig"
425 bool "VMI Guest support"
428 depends on !X86_VOYAGER
430 VMI provides a paravirtualized interface to the VMware ESX server
431 (it could be used by other hypervisors in theory too, but is not
432 at the moment), by linking the kernel to a GPL-ed ROM module
433 provided by the hypervisor.
436 bool "KVM paravirtualized clock"
438 select PARAVIRT_CLOCK
439 depends on !X86_VOYAGER
441 Turning on this option will allow you to run a paravirtualized clock
442 when running over the KVM hypervisor. Instead of relying on a PIT
443 (or probably other) emulation by the underlying device model, the host
444 provides the guest with timing infrastructure such as time of day, and
448 bool "KVM Guest support"
450 depends on !X86_VOYAGER
452 This option enables various optimizations for running under the KVM
455 source "arch/x86/lguest/Kconfig"
458 bool "Enable paravirtualization code"
459 depends on !X86_VOYAGER
461 This changes the kernel so it can modify itself when it is run
462 under a hypervisor, potentially improving performance significantly
463 over full virtualization. However, when run without a hypervisor
464 the kernel is theoretically slower and slightly larger.
466 config PARAVIRT_CLOCK
472 config PARAVIRT_DEBUG
473 bool "paravirt-ops debugging"
474 depends on PARAVIRT && DEBUG_KERNEL
476 Enable to debug paravirt_ops internals. Specifically, BUG if
477 a paravirt_op is missing when it is called.
482 This option adds a kernel parameter 'memtest', which allows memtest
484 memtest=0, mean disabled; -- default
485 memtest=1, mean do 1 test pattern;
487 memtest=4, mean do 4 test patterns.
488 If you are unsure how to answer this question, answer N.
490 config X86_SUMMIT_NUMA
492 depends on X86_32 && NUMA && X86_GENERICARCH
494 config X86_CYCLONE_TIMER
496 depends on X86_GENERICARCH
498 source "arch/x86/Kconfig.cpu"
502 prompt "HPET Timer Support" if X86_32
504 Use the IA-PC HPET (High Precision Event Timer) to manage
505 time in preference to the PIT and RTC, if a HPET is
507 HPET is the next generation timer replacing legacy 8254s.
508 The HPET provides a stable time base on SMP
509 systems, unlike the TSC, but it is more expensive to access,
510 as it is off-chip. You can find the HPET spec at
511 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
513 You can safely choose Y here. However, HPET will only be
514 activated if the platform and the BIOS support this feature.
515 Otherwise the 8254 will be used for timing services.
517 Choose N to continue using the legacy 8254 timer.
519 config HPET_EMULATE_RTC
521 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
523 # Mark as embedded because too many people got it wrong.
524 # The code disables itself when not needed.
527 bool "Enable DMI scanning" if EMBEDDED
529 Enabled scanning of DMI to identify machine quirks. Say Y
530 here unless you have verified that your setup is not
531 affected by entries in the DMI blacklist. Required by PNP
535 bool "GART IOMMU support" if EMBEDDED
539 depends on X86_64 && PCI
541 Support for full DMA access of devices with 32bit memory access only
542 on systems with more than 3GB. This is usually needed for USB,
543 sound, many IDE/SATA chipsets and some other devices.
544 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
545 based hardware IOMMU and a software bounce buffer based IOMMU used
546 on Intel systems and as fallback.
547 The code is only active when needed (enough memory and limited
548 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
552 bool "IBM Calgary IOMMU support"
554 depends on X86_64 && PCI && EXPERIMENTAL
556 Support for hardware IOMMUs in IBM's xSeries x366 and x460
557 systems. Needed to run systems with more than 3GB of memory
558 properly with 32-bit PCI devices that do not support DAC
559 (Double Address Cycle). Calgary also supports bus level
560 isolation, where all DMAs pass through the IOMMU. This
561 prevents them from going anywhere except their intended
562 destination. This catches hard-to-find kernel bugs and
563 mis-behaving drivers and devices that do not use the DMA-API
564 properly to set up their DMA buffers. The IOMMU can be
565 turned off at boot time with the iommu=off parameter.
566 Normally the kernel will make the right choice by itself.
569 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
571 prompt "Should Calgary be enabled by default?"
572 depends on CALGARY_IOMMU
574 Should Calgary be enabled by default? if you choose 'y', Calgary
575 will be used (if it exists). If you choose 'n', Calgary will not be
576 used even if it exists. If you choose 'n' and would like to use
577 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
581 bool "AMD IOMMU support"
584 depends on X86_64 && PCI && ACPI
586 With this option you can enable support for AMD IOMMU hardware in
587 your system. An IOMMU is a hardware component which provides
588 remapping of DMA memory accesses from devices. With an AMD IOMMU you
589 can isolate the the DMA memory of different devices and protect the
590 system from misbehaving device drivers or hardware.
592 You can find out if your system has an AMD IOMMU if you look into
593 your BIOS for an option to enable it or if you have an IVRS ACPI
596 config AMD_IOMMU_STATS
597 bool "Export AMD IOMMU statistics to debugfs"
601 This option enables code in the AMD IOMMU driver to collect various
602 statistics about whats happening in the driver and exports that
603 information to userspace via debugfs.
606 # need this always selected by IOMMU for the VIA workaround
610 Support for software bounce buffers used on x86-64 systems
611 which don't have a hardware IOMMU (e.g. the current generation
612 of Intel's x86-64 CPUs). Using this PCI devices which can only
613 access 32-bits of memory can be used on systems with more than
614 3 GB of memory. If unsure, say Y.
617 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
620 def_bool (AMD_IOMMU || DMAR)
623 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
624 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
625 select CPUMASK_OFFSTACK
628 Configure maximum number of CPUS and NUMA Nodes for this architecture.
632 int "Maximum number of CPUs" if SMP && !MAXSMP
633 range 2 512 if SMP && !MAXSMP
635 default "4096" if MAXSMP
636 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
639 This allows you to specify the maximum number of CPUs which this
640 kernel will support. The maximum supported value is 512 and the
641 minimum value which makes sense is 2.
643 This is purely to save memory - each supported CPU adds
644 approximately eight kilobytes to the kernel image.
647 bool "SMT (Hyperthreading) scheduler support"
650 SMT scheduler support improves the CPU scheduler's decision making
651 when dealing with Intel Pentium 4 chips with HyperThreading at a
652 cost of slightly increased overhead in some places. If unsure say
657 prompt "Multi-core scheduler support"
660 Multi-core scheduler support improves the CPU scheduler's decision
661 making when dealing with multi-core CPU chips at a cost of slightly
662 increased overhead in some places. If unsure say N here.
664 source "kernel/Kconfig.preempt"
667 bool "Local APIC support on uniprocessors"
668 depends on X86_32 && !SMP && !(X86_VOYAGER || X86_GENERICARCH)
670 A local APIC (Advanced Programmable Interrupt Controller) is an
671 integrated interrupt controller in the CPU. If you have a single-CPU
672 system which has a processor with a local APIC, you can say Y here to
673 enable and use it. If you say Y here even though your machine doesn't
674 have a local APIC, then the kernel will still run with no slowdown at
675 all. The local APIC supports CPU-generated self-interrupts (timer,
676 performance counters), and the NMI watchdog which detects hard
680 bool "IO-APIC support on uniprocessors"
681 depends on X86_UP_APIC
683 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
684 SMP-capable replacement for PC-style interrupt controllers. Most
685 SMP systems and many recent uniprocessor systems have one.
687 If you have a single-CPU system with an IO-APIC, you can say Y here
688 to use it. If you say Y here even though your machine doesn't have
689 an IO-APIC, then the kernel will still run with no slowdown at all.
691 config X86_LOCAL_APIC
693 depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
697 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
699 config X86_VISWS_APIC
701 depends on X86_32 && X86_VISWS
703 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
704 bool "Reroute for broken boot IRQs"
706 depends on X86_IO_APIC
708 This option enables a workaround that fixes a source of
709 spurious interrupts. This is recommended when threaded
710 interrupt handling is used on systems where the generation of
711 superfluous "boot interrupts" cannot be disabled.
713 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
714 entry in the chipset's IO-APIC is masked (as, e.g. the RT
715 kernel does during interrupt handling). On chipsets where this
716 boot IRQ generation cannot be disabled, this workaround keeps
717 the original IRQ line masked so that only the equivalent "boot
718 IRQ" is delivered to the CPUs. The workaround also tells the
719 kernel to set up the IRQ handler on the boot IRQ line. In this
720 way only one interrupt is delivered to the kernel. Otherwise
721 the spurious second interrupt may cause the kernel to bring
722 down (vital) interrupt lines.
724 Only affects "broken" chipsets. Interrupt sharing may be
725 increased on these systems.
728 bool "Machine Check Exception"
729 depends on !X86_VOYAGER
731 Machine Check Exception support allows the processor to notify the
732 kernel if it detects a problem (e.g. overheating, component failure).
733 The action the kernel takes depends on the severity of the problem,
734 ranging from a warning message on the console, to halting the machine.
735 Your processor must be a Pentium or newer to support this - check the
736 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
737 have a design flaw which leads to false MCE events - hence MCE is
738 disabled on all P5 processors, unless explicitly enabled with "mce"
739 as a boot argument. Similarly, if MCE is built in and creates a
740 problem on some new non-standard machine, you can boot with "nomce"
741 to disable it. MCE support simply ignores non-MCE processors like
742 the 386 and 486, so nearly everyone can say Y here.
746 prompt "Intel MCE features"
747 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
749 Additional support for intel specific MCE features such as
754 prompt "AMD MCE features"
755 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
757 Additional support for AMD specific MCE features such as
758 the DRAM Error Threshold.
760 config X86_MCE_NONFATAL
761 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
762 depends on X86_32 && X86_MCE
764 Enabling this feature starts a timer that triggers every 5 seconds which
765 will look at the machine check registers to see if anything happened.
766 Non-fatal problems automatically get corrected (but still logged).
767 Disable this if you don't want to see these messages.
768 Seeing the messages this option prints out may be indicative of dying
769 or out-of-spec (ie, overclocked) hardware.
770 This option only does something on certain CPUs.
771 (AMD Athlon/Duron and Intel Pentium 4)
773 config X86_MCE_P4THERMAL
774 bool "check for P4 thermal throttling interrupt."
775 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
777 Enabling this feature will cause a message to be printed when the P4
778 enters thermal throttling.
781 bool "Enable VM86 support" if EMBEDDED
785 This option is required by programs like DOSEMU to run 16-bit legacy
786 code on X86 processors. It also may be needed by software like
787 XFree86 to initialize some video cards via BIOS. Disabling this
788 option saves about 6k.
791 tristate "Toshiba Laptop support"
794 This adds a driver to safely access the System Management Mode of
795 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
796 not work on models with a Phoenix BIOS. The System Management Mode
797 is used to set the BIOS and power saving options on Toshiba portables.
799 For information on utilities to make use of this driver see the
800 Toshiba Linux utilities web site at:
801 <http://www.buzzard.org.uk/toshiba/>.
803 Say Y if you intend to run this kernel on a Toshiba portable.
807 tristate "Dell laptop support"
809 This adds a driver to safely access the System Management Mode
810 of the CPU on the Dell Inspiron 8000. The System Management Mode
811 is used to read cpu temperature and cooling fan status and to
812 control the fans on the I8K portables.
814 This driver has been tested only on the Inspiron 8000 but it may
815 also work with other Dell laptops. You can force loading on other
816 models by passing the parameter `force=1' to the module. Use at
819 For information on utilities to make use of this driver see the
820 I8K Linux utilities web site at:
821 <http://people.debian.org/~dz/i8k/>
823 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
826 config X86_REBOOTFIXUPS
827 bool "Enable X86 board specific fixups for reboot"
830 This enables chipset and/or board specific fixups to be done
831 in order to get reboot to work correctly. This is only needed on
832 some combinations of hardware and BIOS. The symptom, for which
833 this config is intended, is when reboot ends with a stalled/hung
836 Currently, the only fixup is for the Geode machines using
837 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
839 Say Y if you want to enable the fixup. Currently, it's safe to
840 enable this option even if you don't need it.
844 tristate "/dev/cpu/microcode - microcode support"
847 If you say Y here, you will be able to update the microcode on
848 certain Intel and AMD processors. The Intel support is for the
849 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
850 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
851 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
852 You will obviously need the actual microcode binary data itself
853 which is not shipped with the Linux kernel.
855 This option selects the general module only, you need to select
856 at least one vendor specific module as well.
858 To compile this driver as a module, choose M here: the
859 module will be called microcode.
861 config MICROCODE_INTEL
862 bool "Intel microcode patch loading support"
867 This options enables microcode patch loading support for Intel
870 For latest news and information on obtaining all the required
871 Intel ingredients for this driver, check:
872 <http://www.urbanmyth.org/microcode/>.
875 bool "AMD microcode patch loading support"
879 If you select this option, microcode patch loading support for AMD
880 processors will be enabled.
882 config MICROCODE_OLD_INTERFACE
887 tristate "/dev/cpu/*/msr - Model-specific register support"
889 This device gives privileged processes access to the x86
890 Model-Specific Registers (MSRs). It is a character device with
891 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
892 MSR accesses are directed to a specific CPU on multi-processor
896 tristate "/dev/cpu/*/cpuid - CPU information support"
898 This device gives processes access to the x86 CPUID instruction to
899 be executed on a specific processor. It is a character device
900 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
904 prompt "High Memory Support"
905 default HIGHMEM4G if !X86_NUMAQ
906 default HIGHMEM64G if X86_NUMAQ
911 depends on !X86_NUMAQ
913 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
914 However, the address space of 32-bit x86 processors is only 4
915 Gigabytes large. That means that, if you have a large amount of
916 physical memory, not all of it can be "permanently mapped" by the
917 kernel. The physical memory that's not permanently mapped is called
920 If you are compiling a kernel which will never run on a machine with
921 more than 1 Gigabyte total physical RAM, answer "off" here (default
922 choice and suitable for most users). This will result in a "3GB/1GB"
923 split: 3GB are mapped so that each process sees a 3GB virtual memory
924 space and the remaining part of the 4GB virtual memory space is used
925 by the kernel to permanently map as much physical memory as
928 If the machine has between 1 and 4 Gigabytes physical RAM, then
931 If more than 4 Gigabytes is used then answer "64GB" here. This
932 selection turns Intel PAE (Physical Address Extension) mode on.
933 PAE implements 3-level paging on IA32 processors. PAE is fully
934 supported by Linux, PAE mode is implemented on all recent Intel
935 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
936 then the kernel will not boot on CPUs that don't support PAE!
938 The actual amount of total physical memory will either be
939 auto detected or can be forced by using a kernel command line option
940 such as "mem=256M". (Try "man bootparam" or see the documentation of
941 your boot loader (lilo or loadlin) about how to pass options to the
942 kernel at boot time.)
944 If unsure, say "off".
948 depends on !X86_NUMAQ
950 Select this if you have a 32-bit processor and between 1 and 4
951 gigabytes of physical RAM.
955 depends on !M386 && !M486
958 Select this if you have a 32-bit processor and more than 4
959 gigabytes of physical RAM.
964 depends on EXPERIMENTAL
965 prompt "Memory split" if EMBEDDED
969 Select the desired split between kernel and user memory.
971 If the address range available to the kernel is less than the
972 physical memory installed, the remaining memory will be available
973 as "high memory". Accessing high memory is a little more costly
974 than low memory, as it needs to be mapped into the kernel first.
975 Note that increasing the kernel address space limits the range
976 available to user programs, making the address space there
977 tighter. Selecting anything other than the default 3G/1G split
978 will also likely make your kernel incompatible with binary-only
981 If you are not absolutely sure what you are doing, leave this
985 bool "3G/1G user/kernel split"
986 config VMSPLIT_3G_OPT
988 bool "3G/1G user/kernel split (for full 1G low memory)"
990 bool "2G/2G user/kernel split"
991 config VMSPLIT_2G_OPT
993 bool "2G/2G user/kernel split (for full 2G low memory)"
995 bool "1G/3G user/kernel split"
1000 default 0xB0000000 if VMSPLIT_3G_OPT
1001 default 0x80000000 if VMSPLIT_2G
1002 default 0x78000000 if VMSPLIT_2G_OPT
1003 default 0x40000000 if VMSPLIT_1G
1009 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1012 bool "PAE (Physical Address Extension) Support"
1013 depends on X86_32 && !HIGHMEM4G
1015 PAE is required for NX support, and furthermore enables
1016 larger swapspace support for non-overcommit purposes. It
1017 has the cost of more pagetable lookup overhead, and also
1018 consumes more pagetable space per process.
1020 config ARCH_PHYS_ADDR_T_64BIT
1021 def_bool X86_64 || X86_PAE
1023 config DIRECT_GBPAGES
1024 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1028 Allow the kernel linear mapping to use 1GB pages on CPUs that
1029 support it. This can improve the kernel's performance a tiny bit by
1030 reducing TLB pressure. If in doubt, say "Y".
1032 # Common NUMA Features
1034 bool "Numa Memory Allocation and Scheduler Support"
1036 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1038 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1040 Enable NUMA (Non Uniform Memory Access) support.
1042 The kernel will try to allocate memory used by a CPU on the
1043 local memory controller of the CPU and add some more
1044 NUMA awareness to the kernel.
1046 For 64-bit this is recommended if the system is Intel Core i7
1047 (or later), AMD Opteron, or EM64T NUMA.
1049 For 32-bit this is only needed on (rare) 32-bit-only platforms
1050 that support NUMA topologies, such as NUMAQ / Summit, or if you
1051 boot a 32-bit kernel on a 64-bit NUMA platform.
1053 Otherwise, you should say N.
1055 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1056 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1060 prompt "Old style AMD Opteron NUMA detection"
1061 depends on X86_64 && NUMA && PCI
1063 Enable K8 NUMA node topology detection. You should say Y here if
1064 you have a multi processor AMD K8 system. This uses an old
1065 method to read the NUMA configuration directly from the builtin
1066 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1067 instead, which also takes priority if both are compiled in.
1069 config X86_64_ACPI_NUMA
1071 prompt "ACPI NUMA detection"
1072 depends on X86_64 && NUMA && ACPI && PCI
1075 Enable ACPI SRAT based node topology detection.
1077 # Some NUMA nodes have memory ranges that span
1078 # other nodes. Even though a pfn is valid and
1079 # between a node's start and end pfns, it may not
1080 # reside on that node. See memmap_init_zone()
1082 config NODES_SPAN_OTHER_NODES
1084 depends on X86_64_ACPI_NUMA
1087 bool "NUMA emulation"
1088 depends on X86_64 && NUMA
1090 Enable NUMA emulation. A flat machine will be split
1091 into virtual nodes when booted with "numa=fake=N", where N is the
1092 number of nodes. This is only useful for debugging.
1095 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1097 default "9" if MAXSMP
1098 default "6" if X86_64
1099 default "4" if X86_NUMAQ
1101 depends on NEED_MULTIPLE_NODES
1103 Specify the maximum number of NUMA Nodes available on the target
1104 system. Increases memory reserved to accomodate various tables.
1106 config HAVE_ARCH_BOOTMEM_NODE
1108 depends on X86_32 && NUMA
1110 config ARCH_HAVE_MEMORY_PRESENT
1112 depends on X86_32 && DISCONTIGMEM
1114 config NEED_NODE_MEMMAP_SIZE
1116 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1118 config HAVE_ARCH_ALLOC_REMAP
1120 depends on X86_32 && NUMA
1122 config ARCH_FLATMEM_ENABLE
1124 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1126 config ARCH_DISCONTIGMEM_ENABLE
1128 depends on NUMA && X86_32
1130 config ARCH_DISCONTIGMEM_DEFAULT
1132 depends on NUMA && X86_32
1134 config ARCH_SPARSEMEM_DEFAULT
1138 config ARCH_SPARSEMEM_ENABLE
1140 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC) || X86_GENERICARCH
1141 select SPARSEMEM_STATIC if X86_32
1142 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1144 config ARCH_SELECT_MEMORY_MODEL
1146 depends on ARCH_SPARSEMEM_ENABLE
1148 config ARCH_MEMORY_PROBE
1150 depends on MEMORY_HOTPLUG
1155 bool "Allocate 3rd-level pagetables from highmem"
1156 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1158 The VM uses one page table entry for each page of physical memory.
1159 For systems with a lot of RAM, this can be wasteful of precious
1160 low memory. Setting this option will put user-space page table
1161 entries in high memory.
1163 config X86_CHECK_BIOS_CORRUPTION
1164 bool "Check for low memory corruption"
1166 Periodically check for memory corruption in low memory, which
1167 is suspected to be caused by BIOS. Even when enabled in the
1168 configuration, it is disabled at runtime. Enable it by
1169 setting "memory_corruption_check=1" on the kernel command
1170 line. By default it scans the low 64k of memory every 60
1171 seconds; see the memory_corruption_check_size and
1172 memory_corruption_check_period parameters in
1173 Documentation/kernel-parameters.txt to adjust this.
1175 When enabled with the default parameters, this option has
1176 almost no overhead, as it reserves a relatively small amount
1177 of memory and scans it infrequently. It both detects corruption
1178 and prevents it from affecting the running system.
1180 It is, however, intended as a diagnostic tool; if repeatable
1181 BIOS-originated corruption always affects the same memory,
1182 you can use memmap= to prevent the kernel from using that
1185 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1186 bool "Set the default setting of memory_corruption_check"
1187 depends on X86_CHECK_BIOS_CORRUPTION
1190 Set whether the default state of memory_corruption_check is
1193 config X86_RESERVE_LOW_64K
1194 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1197 Reserve the first 64K of physical RAM on BIOSes that are known
1198 to potentially corrupt that memory range. A numbers of BIOSes are
1199 known to utilize this area during suspend/resume, so it must not
1200 be used by the kernel.
1202 Set this to N if you are absolutely sure that you trust the BIOS
1203 to get all its memory reservations and usages right.
1205 If you have doubts about the BIOS (e.g. suspend/resume does not
1206 work or there's kernel crashes after certain hardware hotplug
1207 events) and it's not AMI or Phoenix, then you might want to enable
1208 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1209 corruption patterns.
1213 config MATH_EMULATION
1215 prompt "Math emulation" if X86_32
1217 Linux can emulate a math coprocessor (used for floating point
1218 operations) if you don't have one. 486DX and Pentium processors have
1219 a math coprocessor built in, 486SX and 386 do not, unless you added
1220 a 487DX or 387, respectively. (The messages during boot time can
1221 give you some hints here ["man dmesg"].) Everyone needs either a
1222 coprocessor or this emulation.
1224 If you don't have a math coprocessor, you need to say Y here; if you
1225 say Y here even though you have a coprocessor, the coprocessor will
1226 be used nevertheless. (This behavior can be changed with the kernel
1227 command line option "no387", which comes handy if your coprocessor
1228 is broken. Try "man bootparam" or see the documentation of your boot
1229 loader (lilo or loadlin) about how to pass options to the kernel at
1230 boot time.) This means that it is a good idea to say Y here if you
1231 intend to use this kernel on different machines.
1233 More information about the internals of the Linux math coprocessor
1234 emulation can be found in <file:arch/x86/math-emu/README>.
1236 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1237 kernel, it won't hurt.
1240 bool "MTRR (Memory Type Range Register) support"
1242 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1243 the Memory Type Range Registers (MTRRs) may be used to control
1244 processor access to memory ranges. This is most useful if you have
1245 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1246 allows bus write transfers to be combined into a larger transfer
1247 before bursting over the PCI/AGP bus. This can increase performance
1248 of image write operations 2.5 times or more. Saying Y here creates a
1249 /proc/mtrr file which may be used to manipulate your processor's
1250 MTRRs. Typically the X server should use this.
1252 This code has a reasonably generic interface so that similar
1253 control registers on other processors can be easily supported
1256 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1257 Registers (ARRs) which provide a similar functionality to MTRRs. For
1258 these, the ARRs are used to emulate the MTRRs.
1259 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1260 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1261 write-combining. All of these processors are supported by this code
1262 and it makes sense to say Y here if you have one of them.
1264 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1265 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1266 can lead to all sorts of problems, so it's good to say Y here.
1268 You can safely say Y even if your machine doesn't have MTRRs, you'll
1269 just add about 9 KB to your kernel.
1271 See <file:Documentation/x86/mtrr.txt> for more information.
1273 config MTRR_SANITIZER
1275 prompt "MTRR cleanup support"
1278 Convert MTRR layout from continuous to discrete, so X drivers can
1279 add writeback entries.
1281 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1282 The largest mtrr entry size for a continous block can be set with
1287 config MTRR_SANITIZER_ENABLE_DEFAULT
1288 int "MTRR cleanup enable value (0-1)"
1291 depends on MTRR_SANITIZER
1293 Enable mtrr cleanup default value
1295 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1296 int "MTRR cleanup spare reg num (0-7)"
1299 depends on MTRR_SANITIZER
1301 mtrr cleanup spare entries default, it can be changed via
1302 mtrr_spare_reg_nr=N on the kernel command line.
1306 prompt "x86 PAT support"
1309 Use PAT attributes to setup page level cache control.
1311 PATs are the modern equivalents of MTRRs and are much more
1312 flexible than MTRRs.
1314 Say N here if you see bootup problems (boot crash, boot hang,
1315 spontaneous reboots) or a non-working video driver.
1320 bool "EFI runtime service support"
1323 This enables the kernel to use EFI runtime services that are
1324 available (such as the EFI variable services).
1326 This option is only useful on systems that have EFI firmware.
1327 In addition, you should use the latest ELILO loader available
1328 at <http://elilo.sourceforge.net> in order to take advantage
1329 of EFI runtime services. However, even with this option, the
1330 resultant kernel should continue to boot on existing non-EFI
1335 prompt "Enable seccomp to safely compute untrusted bytecode"
1337 This kernel feature is useful for number crunching applications
1338 that may need to compute untrusted bytecode during their
1339 execution. By using pipes or other transports made available to
1340 the process as file descriptors supporting the read/write
1341 syscalls, it's possible to isolate those applications in
1342 their own address space using seccomp. Once seccomp is
1343 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1344 and the task is only allowed to execute a few safe syscalls
1345 defined by each seccomp mode.
1347 If unsure, say Y. Only embedded should say N here.
1349 config CC_STACKPROTECTOR_ALL
1352 config CC_STACKPROTECTOR
1353 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1355 select CC_STACKPROTECTOR_ALL
1357 This option turns on the -fstack-protector GCC feature. This
1358 feature puts, at the beginning of functions, a canary value on
1359 the stack just before the return address, and validates
1360 the value just before actually returning. Stack based buffer
1361 overflows (that need to overwrite this return address) now also
1362 overwrite the canary, which gets detected and the attack is then
1363 neutralized via a kernel panic.
1365 This feature requires gcc version 4.2 or above, or a distribution
1366 gcc with the feature backported. Older versions are automatically
1367 detected and for those versions, this configuration option is
1368 ignored. (and a warning is printed during bootup)
1370 source kernel/Kconfig.hz
1373 bool "kexec system call"
1374 depends on X86_BIOS_REBOOT
1376 kexec is a system call that implements the ability to shutdown your
1377 current kernel, and to start another kernel. It is like a reboot
1378 but it is independent of the system firmware. And like a reboot
1379 you can start any kernel with it, not just Linux.
1381 The name comes from the similarity to the exec system call.
1383 It is an ongoing process to be certain the hardware in a machine
1384 is properly shutdown, so do not be surprised if this code does not
1385 initially work for you. It may help to enable device hotplugging
1386 support. As of this writing the exact hardware interface is
1387 strongly in flux, so no good recommendation can be made.
1390 bool "kernel crash dumps"
1391 depends on X86_64 || (X86_32 && HIGHMEM)
1393 Generate crash dump after being started by kexec.
1394 This should be normally only set in special crash dump kernels
1395 which are loaded in the main kernel with kexec-tools into
1396 a specially reserved region and then later executed after
1397 a crash by kdump/kexec. The crash dump kernel must be compiled
1398 to a memory address not used by the main kernel or BIOS using
1399 PHYSICAL_START, or it must be built as a relocatable image
1400 (CONFIG_RELOCATABLE=y).
1401 For more details see Documentation/kdump/kdump.txt
1404 bool "kexec jump (EXPERIMENTAL)"
1405 depends on EXPERIMENTAL
1406 depends on KEXEC && HIBERNATION && X86_32
1408 Jump between original kernel and kexeced kernel and invoke
1409 code in physical address mode via KEXEC
1411 config PHYSICAL_START
1412 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1413 default "0x1000000" if X86_NUMAQ
1414 default "0x200000" if X86_64
1417 This gives the physical address where the kernel is loaded.
1419 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1420 bzImage will decompress itself to above physical address and
1421 run from there. Otherwise, bzImage will run from the address where
1422 it has been loaded by the boot loader and will ignore above physical
1425 In normal kdump cases one does not have to set/change this option
1426 as now bzImage can be compiled as a completely relocatable image
1427 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1428 address. This option is mainly useful for the folks who don't want
1429 to use a bzImage for capturing the crash dump and want to use a
1430 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1431 to be specifically compiled to run from a specific memory area
1432 (normally a reserved region) and this option comes handy.
1434 So if you are using bzImage for capturing the crash dump, leave
1435 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1436 Otherwise if you plan to use vmlinux for capturing the crash dump
1437 change this value to start of the reserved region (Typically 16MB
1438 0x1000000). In other words, it can be set based on the "X" value as
1439 specified in the "crashkernel=YM@XM" command line boot parameter
1440 passed to the panic-ed kernel. Typically this parameter is set as
1441 crashkernel=64M@16M. Please take a look at
1442 Documentation/kdump/kdump.txt for more details about crash dumps.
1444 Usage of bzImage for capturing the crash dump is recommended as
1445 one does not have to build two kernels. Same kernel can be used
1446 as production kernel and capture kernel. Above option should have
1447 gone away after relocatable bzImage support is introduced. But it
1448 is present because there are users out there who continue to use
1449 vmlinux for dump capture. This option should go away down the
1452 Don't change this unless you know what you are doing.
1455 bool "Build a relocatable kernel (EXPERIMENTAL)"
1456 depends on EXPERIMENTAL
1458 This builds a kernel image that retains relocation information
1459 so it can be loaded someplace besides the default 1MB.
1460 The relocations tend to make the kernel binary about 10% larger,
1461 but are discarded at runtime.
1463 One use is for the kexec on panic case where the recovery kernel
1464 must live at a different physical address than the primary
1467 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1468 it has been loaded at and the compile time physical address
1469 (CONFIG_PHYSICAL_START) is ignored.
1471 config PHYSICAL_ALIGN
1473 prompt "Alignment value to which kernel should be aligned" if X86_32
1474 default "0x100000" if X86_32
1475 default "0x200000" if X86_64
1476 range 0x2000 0x400000
1478 This value puts the alignment restrictions on physical address
1479 where kernel is loaded and run from. Kernel is compiled for an
1480 address which meets above alignment restriction.
1482 If bootloader loads the kernel at a non-aligned address and
1483 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1484 address aligned to above value and run from there.
1486 If bootloader loads the kernel at a non-aligned address and
1487 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1488 load address and decompress itself to the address it has been
1489 compiled for and run from there. The address for which kernel is
1490 compiled already meets above alignment restrictions. Hence the
1491 end result is that kernel runs from a physical address meeting
1492 above alignment restrictions.
1494 Don't change this unless you know what you are doing.
1497 bool "Support for hot-pluggable CPUs"
1498 depends on SMP && HOTPLUG && !X86_VOYAGER
1500 Say Y here to allow turning CPUs off and on. CPUs can be
1501 controlled through /sys/devices/system/cpu.
1502 ( Note: power management support will enable this option
1503 automatically on SMP systems. )
1504 Say N if you want to disable CPU hotplug.
1508 prompt "Compat VDSO support"
1509 depends on X86_32 || IA32_EMULATION
1511 Map the 32-bit VDSO to the predictable old-style address too.
1513 Say N here if you are running a sufficiently recent glibc
1514 version (2.3.3 or later), to remove the high-mapped
1515 VDSO mapping and to exclusively use the randomized VDSO.
1520 bool "Built-in kernel command line"
1523 Allow for specifying boot arguments to the kernel at
1524 build time. On some systems (e.g. embedded ones), it is
1525 necessary or convenient to provide some or all of the
1526 kernel boot arguments with the kernel itself (that is,
1527 to not rely on the boot loader to provide them.)
1529 To compile command line arguments into the kernel,
1530 set this option to 'Y', then fill in the
1531 the boot arguments in CONFIG_CMDLINE.
1533 Systems with fully functional boot loaders (i.e. non-embedded)
1534 should leave this option set to 'N'.
1537 string "Built-in kernel command string"
1538 depends on CMDLINE_BOOL
1541 Enter arguments here that should be compiled into the kernel
1542 image and used at boot time. If the boot loader provides a
1543 command line at boot time, it is appended to this string to
1544 form the full kernel command line, when the system boots.
1546 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1547 change this behavior.
1549 In most cases, the command line (whether built-in or provided
1550 by the boot loader) should specify the device for the root
1553 config CMDLINE_OVERRIDE
1554 bool "Built-in command line overrides boot loader arguments"
1556 depends on CMDLINE_BOOL
1558 Set this option to 'Y' to have the kernel ignore the boot loader
1559 command line, and use ONLY the built-in command line.
1561 This is used to work around broken boot loaders. This should
1562 be set to 'N' under normal conditions.
1566 config ARCH_ENABLE_MEMORY_HOTPLUG
1568 depends on X86_64 || (X86_32 && HIGHMEM)
1570 config ARCH_ENABLE_MEMORY_HOTREMOVE
1572 depends on MEMORY_HOTPLUG
1574 config HAVE_ARCH_EARLY_PFN_TO_NID
1578 menu "Power management and ACPI options"
1579 depends on !X86_VOYAGER
1581 config ARCH_HIBERNATION_HEADER
1583 depends on X86_64 && HIBERNATION
1585 source "kernel/power/Kconfig"
1587 source "drivers/acpi/Kconfig"
1592 depends on APM || APM_MODULE
1595 tristate "APM (Advanced Power Management) BIOS support"
1596 depends on X86_32 && PM_SLEEP
1598 APM is a BIOS specification for saving power using several different
1599 techniques. This is mostly useful for battery powered laptops with
1600 APM compliant BIOSes. If you say Y here, the system time will be
1601 reset after a RESUME operation, the /proc/apm device will provide
1602 battery status information, and user-space programs will receive
1603 notification of APM "events" (e.g. battery status change).
1605 If you select "Y" here, you can disable actual use of the APM
1606 BIOS by passing the "apm=off" option to the kernel at boot time.
1608 Note that the APM support is almost completely disabled for
1609 machines with more than one CPU.
1611 In order to use APM, you will need supporting software. For location
1612 and more information, read <file:Documentation/power/pm.txt> and the
1613 Battery Powered Linux mini-HOWTO, available from
1614 <http://www.tldp.org/docs.html#howto>.
1616 This driver does not spin down disk drives (see the hdparm(8)
1617 manpage ("man 8 hdparm") for that), and it doesn't turn off
1618 VESA-compliant "green" monitors.
1620 This driver does not support the TI 4000M TravelMate and the ACER
1621 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1622 desktop machines also don't have compliant BIOSes, and this driver
1623 may cause those machines to panic during the boot phase.
1625 Generally, if you don't have a battery in your machine, there isn't
1626 much point in using this driver and you should say N. If you get
1627 random kernel OOPSes or reboots that don't seem to be related to
1628 anything, try disabling/enabling this option (or disabling/enabling
1631 Some other things you should try when experiencing seemingly random,
1634 1) make sure that you have enough swap space and that it is
1636 2) pass the "no-hlt" option to the kernel
1637 3) switch on floating point emulation in the kernel and pass
1638 the "no387" option to the kernel
1639 4) pass the "floppy=nodma" option to the kernel
1640 5) pass the "mem=4M" option to the kernel (thereby disabling
1641 all but the first 4 MB of RAM)
1642 6) make sure that the CPU is not over clocked.
1643 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1644 8) disable the cache from your BIOS settings
1645 9) install a fan for the video card or exchange video RAM
1646 10) install a better fan for the CPU
1647 11) exchange RAM chips
1648 12) exchange the motherboard.
1650 To compile this driver as a module, choose M here: the
1651 module will be called apm.
1655 config APM_IGNORE_USER_SUSPEND
1656 bool "Ignore USER SUSPEND"
1658 This option will ignore USER SUSPEND requests. On machines with a
1659 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1660 series notebooks, it is necessary to say Y because of a BIOS bug.
1662 config APM_DO_ENABLE
1663 bool "Enable PM at boot time"
1665 Enable APM features at boot time. From page 36 of the APM BIOS
1666 specification: "When disabled, the APM BIOS does not automatically
1667 power manage devices, enter the Standby State, enter the Suspend
1668 State, or take power saving steps in response to CPU Idle calls."
1669 This driver will make CPU Idle calls when Linux is idle (unless this
1670 feature is turned off -- see "Do CPU IDLE calls", below). This
1671 should always save battery power, but more complicated APM features
1672 will be dependent on your BIOS implementation. You may need to turn
1673 this option off if your computer hangs at boot time when using APM
1674 support, or if it beeps continuously instead of suspending. Turn
1675 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1676 T400CDT. This is off by default since most machines do fine without
1680 bool "Make CPU Idle calls when idle"
1682 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1683 On some machines, this can activate improved power savings, such as
1684 a slowed CPU clock rate, when the machine is idle. These idle calls
1685 are made after the idle loop has run for some length of time (e.g.,
1686 333 mS). On some machines, this will cause a hang at boot time or
1687 whenever the CPU becomes idle. (On machines with more than one CPU,
1688 this option does nothing.)
1690 config APM_DISPLAY_BLANK
1691 bool "Enable console blanking using APM"
1693 Enable console blanking using the APM. Some laptops can use this to
1694 turn off the LCD backlight when the screen blanker of the Linux
1695 virtual console blanks the screen. Note that this is only used by
1696 the virtual console screen blanker, and won't turn off the backlight
1697 when using the X Window system. This also doesn't have anything to
1698 do with your VESA-compliant power-saving monitor. Further, this
1699 option doesn't work for all laptops -- it might not turn off your
1700 backlight at all, or it might print a lot of errors to the console,
1701 especially if you are using gpm.
1703 config APM_ALLOW_INTS
1704 bool "Allow interrupts during APM BIOS calls"
1706 Normally we disable external interrupts while we are making calls to
1707 the APM BIOS as a measure to lessen the effects of a badly behaving
1708 BIOS implementation. The BIOS should reenable interrupts if it
1709 needs to. Unfortunately, some BIOSes do not -- especially those in
1710 many of the newer IBM Thinkpads. If you experience hangs when you
1711 suspend, try setting this to Y. Otherwise, say N.
1715 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1717 source "drivers/cpuidle/Kconfig"
1719 source "drivers/idle/Kconfig"
1724 menu "Bus options (PCI etc.)"
1729 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1731 Find out whether you have a PCI motherboard. PCI is the name of a
1732 bus system, i.e. the way the CPU talks to the other stuff inside
1733 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1734 VESA. If you have PCI, say Y, otherwise N.
1737 prompt "PCI access mode"
1738 depends on X86_32 && PCI
1741 On PCI systems, the BIOS can be used to detect the PCI devices and
1742 determine their configuration. However, some old PCI motherboards
1743 have BIOS bugs and may crash if this is done. Also, some embedded
1744 PCI-based systems don't have any BIOS at all. Linux can also try to
1745 detect the PCI hardware directly without using the BIOS.
1747 With this option, you can specify how Linux should detect the
1748 PCI devices. If you choose "BIOS", the BIOS will be used,
1749 if you choose "Direct", the BIOS won't be used, and if you
1750 choose "MMConfig", then PCI Express MMCONFIG will be used.
1751 If you choose "Any", the kernel will try MMCONFIG, then the
1752 direct access method and falls back to the BIOS if that doesn't
1753 work. If unsure, go with the default, which is "Any".
1758 config PCI_GOMMCONFIG
1775 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1777 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1780 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1784 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1788 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1795 bool "Support mmconfig PCI config space access"
1796 depends on X86_64 && PCI && ACPI
1799 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1800 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1802 DMA remapping (DMAR) devices support enables independent address
1803 translations for Direct Memory Access (DMA) from devices.
1804 These DMA remapping devices are reported via ACPI tables
1805 and include PCI device scope covered by these DMA
1810 prompt "Support for Graphics workaround"
1813 Current Graphics drivers tend to use physical address
1814 for DMA and avoid using DMA APIs. Setting this config
1815 option permits the IOMMU driver to set a unity map for
1816 all the OS-visible memory. Hence the driver can continue
1817 to use physical addresses for DMA.
1819 config DMAR_FLOPPY_WA
1823 Floppy disk drivers are know to bypass DMA API calls
1824 thereby failing to work when IOMMU is enabled. This
1825 workaround will setup a 1:1 mapping for the first
1826 16M to make floppy (an ISA device) work.
1829 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1830 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1832 Supports Interrupt remapping for IO-APIC and MSI devices.
1833 To use x2apic mode in the CPU's which support x2APIC enhancements or
1834 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1836 source "drivers/pci/pcie/Kconfig"
1838 source "drivers/pci/Kconfig"
1840 # x86_64 have no ISA slots, but do have ISA-style DMA.
1848 depends on !X86_VOYAGER
1850 Find out whether you have ISA slots on your motherboard. ISA is the
1851 name of a bus system, i.e. the way the CPU talks to the other stuff
1852 inside your box. Other bus systems are PCI, EISA, MicroChannel
1853 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1854 newer boards don't support it. If you have ISA, say Y, otherwise N.
1860 The Extended Industry Standard Architecture (EISA) bus was
1861 developed as an open alternative to the IBM MicroChannel bus.
1863 The EISA bus provided some of the features of the IBM MicroChannel
1864 bus while maintaining backward compatibility with cards made for
1865 the older ISA bus. The EISA bus saw limited use between 1988 and
1866 1995 when it was made obsolete by the PCI bus.
1868 Say Y here if you are building a kernel for an EISA-based machine.
1872 source "drivers/eisa/Kconfig"
1877 MicroChannel Architecture is found in some IBM PS/2 machines and
1878 laptops. It is a bus system similar to PCI or ISA. See
1879 <file:Documentation/mca.txt> (and especially the web page given
1880 there) before attempting to build an MCA bus kernel.
1882 source "drivers/mca/Kconfig"
1885 tristate "NatSemi SCx200 support"
1887 This provides basic support for National Semiconductor's
1888 (now AMD's) Geode processors. The driver probes for the
1889 PCI-IDs of several on-chip devices, so its a good dependency
1890 for other scx200_* drivers.
1892 If compiled as a module, the driver is named scx200.
1894 config SCx200HR_TIMER
1895 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1896 depends on SCx200 && GENERIC_TIME
1899 This driver provides a clocksource built upon the on-chip
1900 27MHz high-resolution timer. Its also a workaround for
1901 NSC Geode SC-1100's buggy TSC, which loses time when the
1902 processor goes idle (as is done by the scheduler). The
1903 other workaround is idle=poll boot option.
1905 config GEODE_MFGPT_TIMER
1907 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1908 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1910 This driver provides a clock event source based on the MFGPT
1911 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1912 MFGPTs have a better resolution and max interval than the
1913 generic PIT, and are suitable for use as high-res timers.
1916 bool "One Laptop Per Child support"
1919 Add support for detecting the unique features of the OLPC
1926 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1928 source "drivers/pcmcia/Kconfig"
1930 source "drivers/pci/hotplug/Kconfig"
1935 menu "Executable file formats / Emulations"
1937 source "fs/Kconfig.binfmt"
1939 config IA32_EMULATION
1940 bool "IA32 Emulation"
1942 select COMPAT_BINFMT_ELF
1944 Include code to run 32-bit programs under a 64-bit kernel. You should
1945 likely turn this on, unless you're 100% sure that you don't have any
1946 32-bit programs left.
1949 tristate "IA32 a.out support"
1950 depends on IA32_EMULATION
1952 Support old a.out binaries in the 32bit emulation.
1956 depends on IA32_EMULATION
1958 config COMPAT_FOR_U64_ALIGNMENT
1962 config SYSVIPC_COMPAT
1964 depends on COMPAT && SYSVIPC
1969 config HAVE_ATOMIC_IOMAP
1973 source "net/Kconfig"
1975 source "drivers/Kconfig"
1977 source "drivers/firmware/Kconfig"
1981 source "arch/x86/Kconfig.debug"
1983 source "security/Kconfig"
1985 source "crypto/Kconfig"
1987 source "arch/x86/kvm/Kconfig"
1989 source "lib/Kconfig"
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