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 HAVE_KRETPROBES
31 select HAVE_FTRACE_MCOUNT_RECORD
32 select HAVE_DYNAMIC_FTRACE
33 select HAVE_FUNCTION_TRACER
34 select HAVE_FUNCTION_GRAPH_TRACER
35 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
36 select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
37 select HAVE_ARCH_KGDB if !X86_VOYAGER
38 select HAVE_ARCH_TRACEHOOK
39 select HAVE_GENERIC_DMA_COHERENT if X86_32
40 select HAVE_EFFICIENT_UNALIGNED_ACCESS
41 select USER_STACKTRACE_SUPPORT
45 default "arch/x86/configs/i386_defconfig" if X86_32
46 default "arch/x86/configs/x86_64_defconfig" if X86_64
51 config GENERIC_CMOS_UPDATE
54 config CLOCKSOURCE_WATCHDOG
57 config GENERIC_CLOCKEVENTS
60 config GENERIC_CLOCKEVENTS_BROADCAST
62 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
64 config LOCKDEP_SUPPORT
67 config STACKTRACE_SUPPORT
70 config HAVE_LATENCYTOP_SUPPORT
73 config FAST_CMPXCHG_LOCAL
86 config GENERIC_ISA_DMA
95 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
97 config GENERIC_BUG_RELATIVE_POINTERS
100 config GENERIC_HWEIGHT
106 config ARCH_MAY_HAVE_PC_FDC
109 config RWSEM_GENERIC_SPINLOCK
112 config RWSEM_XCHGADD_ALGORITHM
115 config ARCH_HAS_CPU_IDLE_WAIT
118 config GENERIC_CALIBRATE_DELAY
121 config GENERIC_TIME_VSYSCALL
125 config ARCH_HAS_CPU_RELAX
128 config ARCH_HAS_DEFAULT_IDLE
131 config ARCH_HAS_CACHE_LINE_SIZE
134 config HAVE_SETUP_PER_CPU_AREA
135 def_bool X86_64_SMP || (X86_SMP && !X86_VOYAGER)
137 config HAVE_CPUMASK_OF_CPU_MAP
140 config ARCH_HIBERNATION_POSSIBLE
142 depends on !SMP || !X86_VOYAGER
144 config ARCH_SUSPEND_POSSIBLE
146 depends on !X86_VOYAGER
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 || BROKEN) && !PCI
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.
393 config SCHED_OMIT_FRAME_POINTER
395 prompt "Single-depth WCHAN output"
398 Calculate simpler /proc/<PID>/wchan values. If this option
399 is disabled then wchan values will recurse back to the
400 caller function. This provides more accurate wchan values,
401 at the expense of slightly more scheduling overhead.
403 If in doubt, say "Y".
405 menuconfig PARAVIRT_GUEST
406 bool "Paravirtualized guest support"
408 Say Y here to get to see options related to running Linux under
409 various hypervisors. This option alone does not add any kernel code.
411 If you say N, all options in this submenu will be skipped and disabled.
415 source "arch/x86/xen/Kconfig"
418 bool "VMI Guest support"
421 depends on !X86_VOYAGER
423 VMI provides a paravirtualized interface to the VMware ESX server
424 (it could be used by other hypervisors in theory too, but is not
425 at the moment), by linking the kernel to a GPL-ed ROM module
426 provided by the hypervisor.
429 bool "KVM paravirtualized clock"
431 select PARAVIRT_CLOCK
432 depends on !X86_VOYAGER
434 Turning on this option will allow you to run a paravirtualized clock
435 when running over the KVM hypervisor. Instead of relying on a PIT
436 (or probably other) emulation by the underlying device model, the host
437 provides the guest with timing infrastructure such as time of day, and
441 bool "KVM Guest support"
443 depends on !X86_VOYAGER
445 This option enables various optimizations for running under the KVM
448 source "arch/x86/lguest/Kconfig"
451 bool "Enable paravirtualization code"
452 depends on !X86_VOYAGER
454 This changes the kernel so it can modify itself when it is run
455 under a hypervisor, potentially improving performance significantly
456 over full virtualization. However, when run without a hypervisor
457 the kernel is theoretically slower and slightly larger.
459 config PARAVIRT_CLOCK
465 config PARAVIRT_DEBUG
466 bool "paravirt-ops debugging"
467 depends on PARAVIRT && DEBUG_KERNEL
469 Enable to debug paravirt_ops internals. Specifically, BUG if
470 a paravirt_op is missing when it is called.
475 This option adds a kernel parameter 'memtest', which allows memtest
477 memtest=0, mean disabled; -- default
478 memtest=1, mean do 1 test pattern;
480 memtest=4, mean do 4 test patterns.
481 If you are unsure how to answer this question, answer N.
483 config X86_SUMMIT_NUMA
485 depends on X86_32 && NUMA && X86_GENERICARCH
487 config X86_CYCLONE_TIMER
489 depends on X86_GENERICARCH
491 source "arch/x86/Kconfig.cpu"
495 prompt "HPET Timer Support" if X86_32
497 Use the IA-PC HPET (High Precision Event Timer) to manage
498 time in preference to the PIT and RTC, if a HPET is
500 HPET is the next generation timer replacing legacy 8254s.
501 The HPET provides a stable time base on SMP
502 systems, unlike the TSC, but it is more expensive to access,
503 as it is off-chip. You can find the HPET spec at
504 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
506 You can safely choose Y here. However, HPET will only be
507 activated if the platform and the BIOS support this feature.
508 Otherwise the 8254 will be used for timing services.
510 Choose N to continue using the legacy 8254 timer.
512 config HPET_EMULATE_RTC
514 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
516 # Mark as embedded because too many people got it wrong.
517 # The code disables itself when not needed.
520 bool "Enable DMI scanning" if EMBEDDED
522 Enabled scanning of DMI to identify machine quirks. Say Y
523 here unless you have verified that your setup is not
524 affected by entries in the DMI blacklist. Required by PNP
528 bool "GART IOMMU support" if EMBEDDED
532 depends on X86_64 && PCI
534 Support for full DMA access of devices with 32bit memory access only
535 on systems with more than 3GB. This is usually needed for USB,
536 sound, many IDE/SATA chipsets and some other devices.
537 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
538 based hardware IOMMU and a software bounce buffer based IOMMU used
539 on Intel systems and as fallback.
540 The code is only active when needed (enough memory and limited
541 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
545 bool "IBM Calgary IOMMU support"
547 depends on X86_64 && PCI && EXPERIMENTAL
549 Support for hardware IOMMUs in IBM's xSeries x366 and x460
550 systems. Needed to run systems with more than 3GB of memory
551 properly with 32-bit PCI devices that do not support DAC
552 (Double Address Cycle). Calgary also supports bus level
553 isolation, where all DMAs pass through the IOMMU. This
554 prevents them from going anywhere except their intended
555 destination. This catches hard-to-find kernel bugs and
556 mis-behaving drivers and devices that do not use the DMA-API
557 properly to set up their DMA buffers. The IOMMU can be
558 turned off at boot time with the iommu=off parameter.
559 Normally the kernel will make the right choice by itself.
562 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
564 prompt "Should Calgary be enabled by default?"
565 depends on CALGARY_IOMMU
567 Should Calgary be enabled by default? if you choose 'y', Calgary
568 will be used (if it exists). If you choose 'n', Calgary will not be
569 used even if it exists. If you choose 'n' and would like to use
570 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
574 bool "AMD IOMMU support"
577 depends on X86_64 && PCI && ACPI
579 With this option you can enable support for AMD IOMMU hardware in
580 your system. An IOMMU is a hardware component which provides
581 remapping of DMA memory accesses from devices. With an AMD IOMMU you
582 can isolate the the DMA memory of different devices and protect the
583 system from misbehaving device drivers or hardware.
585 You can find out if your system has an AMD IOMMU if you look into
586 your BIOS for an option to enable it or if you have an IVRS ACPI
589 # need this always selected by IOMMU for the VIA workaround
593 Support for software bounce buffers used on x86-64 systems
594 which don't have a hardware IOMMU (e.g. the current generation
595 of Intel's x86-64 CPUs). Using this PCI devices which can only
596 access 32-bits of memory can be used on systems with more than
597 3 GB of memory. If unsure, say Y.
600 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
603 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
604 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
605 select CPUMASK_OFFSTACK
608 Configure maximum number of CPUS and NUMA Nodes for this architecture.
612 int "Maximum number of CPUs" if SMP && !MAXSMP
613 range 2 512 if SMP && !MAXSMP
615 default "4096" if MAXSMP
616 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
619 This allows you to specify the maximum number of CPUs which this
620 kernel will support. The maximum supported value is 512 and the
621 minimum value which makes sense is 2.
623 This is purely to save memory - each supported CPU adds
624 approximately eight kilobytes to the kernel image.
627 bool "SMT (Hyperthreading) scheduler support"
630 SMT scheduler support improves the CPU scheduler's decision making
631 when dealing with Intel Pentium 4 chips with HyperThreading at a
632 cost of slightly increased overhead in some places. If unsure say
637 prompt "Multi-core scheduler support"
640 Multi-core scheduler support improves the CPU scheduler's decision
641 making when dealing with multi-core CPU chips at a cost of slightly
642 increased overhead in some places. If unsure say N here.
644 source "kernel/Kconfig.preempt"
647 bool "Local APIC support on uniprocessors"
648 depends on X86_32 && !SMP && !(X86_VOYAGER || X86_GENERICARCH)
650 A local APIC (Advanced Programmable Interrupt Controller) is an
651 integrated interrupt controller in the CPU. If you have a single-CPU
652 system which has a processor with a local APIC, you can say Y here to
653 enable and use it. If you say Y here even though your machine doesn't
654 have a local APIC, then the kernel will still run with no slowdown at
655 all. The local APIC supports CPU-generated self-interrupts (timer,
656 performance counters), and the NMI watchdog which detects hard
660 bool "IO-APIC support on uniprocessors"
661 depends on X86_UP_APIC
663 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
664 SMP-capable replacement for PC-style interrupt controllers. Most
665 SMP systems and many recent uniprocessor systems have one.
667 If you have a single-CPU system with an IO-APIC, you can say Y here
668 to use it. If you say Y here even though your machine doesn't have
669 an IO-APIC, then the kernel will still run with no slowdown at all.
671 config X86_LOCAL_APIC
673 depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
677 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
679 config X86_VISWS_APIC
681 depends on X86_32 && X86_VISWS
683 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
684 bool "Reroute for broken boot IRQs"
686 depends on X86_IO_APIC
688 This option enables a workaround that fixes a source of
689 spurious interrupts. This is recommended when threaded
690 interrupt handling is used on systems where the generation of
691 superfluous "boot interrupts" cannot be disabled.
693 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
694 entry in the chipset's IO-APIC is masked (as, e.g. the RT
695 kernel does during interrupt handling). On chipsets where this
696 boot IRQ generation cannot be disabled, this workaround keeps
697 the original IRQ line masked so that only the equivalent "boot
698 IRQ" is delivered to the CPUs. The workaround also tells the
699 kernel to set up the IRQ handler on the boot IRQ line. In this
700 way only one interrupt is delivered to the kernel. Otherwise
701 the spurious second interrupt may cause the kernel to bring
702 down (vital) interrupt lines.
704 Only affects "broken" chipsets. Interrupt sharing may be
705 increased on these systems.
708 bool "Machine Check Exception"
709 depends on !X86_VOYAGER
711 Machine Check Exception support allows the processor to notify the
712 kernel if it detects a problem (e.g. overheating, component failure).
713 The action the kernel takes depends on the severity of the problem,
714 ranging from a warning message on the console, to halting the machine.
715 Your processor must be a Pentium or newer to support this - check the
716 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
717 have a design flaw which leads to false MCE events - hence MCE is
718 disabled on all P5 processors, unless explicitly enabled with "mce"
719 as a boot argument. Similarly, if MCE is built in and creates a
720 problem on some new non-standard machine, you can boot with "nomce"
721 to disable it. MCE support simply ignores non-MCE processors like
722 the 386 and 486, so nearly everyone can say Y here.
726 prompt "Intel MCE features"
727 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
729 Additional support for intel specific MCE features such as
734 prompt "AMD MCE features"
735 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
737 Additional support for AMD specific MCE features such as
738 the DRAM Error Threshold.
740 config X86_MCE_NONFATAL
741 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
742 depends on X86_32 && X86_MCE
744 Enabling this feature starts a timer that triggers every 5 seconds which
745 will look at the machine check registers to see if anything happened.
746 Non-fatal problems automatically get corrected (but still logged).
747 Disable this if you don't want to see these messages.
748 Seeing the messages this option prints out may be indicative of dying
749 or out-of-spec (ie, overclocked) hardware.
750 This option only does something on certain CPUs.
751 (AMD Athlon/Duron and Intel Pentium 4)
753 config X86_MCE_P4THERMAL
754 bool "check for P4 thermal throttling interrupt."
755 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
757 Enabling this feature will cause a message to be printed when the P4
758 enters thermal throttling.
761 bool "Enable VM86 support" if EMBEDDED
765 This option is required by programs like DOSEMU to run 16-bit legacy
766 code on X86 processors. It also may be needed by software like
767 XFree86 to initialize some video cards via BIOS. Disabling this
768 option saves about 6k.
771 tristate "Toshiba Laptop support"
774 This adds a driver to safely access the System Management Mode of
775 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
776 not work on models with a Phoenix BIOS. The System Management Mode
777 is used to set the BIOS and power saving options on Toshiba portables.
779 For information on utilities to make use of this driver see the
780 Toshiba Linux utilities web site at:
781 <http://www.buzzard.org.uk/toshiba/>.
783 Say Y if you intend to run this kernel on a Toshiba portable.
787 tristate "Dell laptop support"
789 This adds a driver to safely access the System Management Mode
790 of the CPU on the Dell Inspiron 8000. The System Management Mode
791 is used to read cpu temperature and cooling fan status and to
792 control the fans on the I8K portables.
794 This driver has been tested only on the Inspiron 8000 but it may
795 also work with other Dell laptops. You can force loading on other
796 models by passing the parameter `force=1' to the module. Use at
799 For information on utilities to make use of this driver see the
800 I8K Linux utilities web site at:
801 <http://people.debian.org/~dz/i8k/>
803 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
806 config X86_REBOOTFIXUPS
807 bool "Enable X86 board specific fixups for reboot"
810 This enables chipset and/or board specific fixups to be done
811 in order to get reboot to work correctly. This is only needed on
812 some combinations of hardware and BIOS. The symptom, for which
813 this config is intended, is when reboot ends with a stalled/hung
816 Currently, the only fixup is for the Geode machines using
817 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
819 Say Y if you want to enable the fixup. Currently, it's safe to
820 enable this option even if you don't need it.
824 tristate "/dev/cpu/microcode - microcode support"
827 If you say Y here, you will be able to update the microcode on
828 certain Intel and AMD processors. The Intel support is for the
829 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
830 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
831 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
832 You will obviously need the actual microcode binary data itself
833 which is not shipped with the Linux kernel.
835 This option selects the general module only, you need to select
836 at least one vendor specific module as well.
838 To compile this driver as a module, choose M here: the
839 module will be called microcode.
841 config MICROCODE_INTEL
842 bool "Intel microcode patch loading support"
847 This options enables microcode patch loading support for Intel
850 For latest news and information on obtaining all the required
851 Intel ingredients for this driver, check:
852 <http://www.urbanmyth.org/microcode/>.
855 bool "AMD microcode patch loading support"
859 If you select this option, microcode patch loading support for AMD
860 processors will be enabled.
862 config MICROCODE_OLD_INTERFACE
867 tristate "/dev/cpu/*/msr - Model-specific register support"
869 This device gives privileged processes access to the x86
870 Model-Specific Registers (MSRs). It is a character device with
871 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
872 MSR accesses are directed to a specific CPU on multi-processor
876 tristate "/dev/cpu/*/cpuid - CPU information support"
878 This device gives processes access to the x86 CPUID instruction to
879 be executed on a specific processor. It is a character device
880 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
884 prompt "High Memory Support"
885 default HIGHMEM4G if !X86_NUMAQ
886 default HIGHMEM64G if X86_NUMAQ
891 depends on !X86_NUMAQ
893 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
894 However, the address space of 32-bit x86 processors is only 4
895 Gigabytes large. That means that, if you have a large amount of
896 physical memory, not all of it can be "permanently mapped" by the
897 kernel. The physical memory that's not permanently mapped is called
900 If you are compiling a kernel which will never run on a machine with
901 more than 1 Gigabyte total physical RAM, answer "off" here (default
902 choice and suitable for most users). This will result in a "3GB/1GB"
903 split: 3GB are mapped so that each process sees a 3GB virtual memory
904 space and the remaining part of the 4GB virtual memory space is used
905 by the kernel to permanently map as much physical memory as
908 If the machine has between 1 and 4 Gigabytes physical RAM, then
911 If more than 4 Gigabytes is used then answer "64GB" here. This
912 selection turns Intel PAE (Physical Address Extension) mode on.
913 PAE implements 3-level paging on IA32 processors. PAE is fully
914 supported by Linux, PAE mode is implemented on all recent Intel
915 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
916 then the kernel will not boot on CPUs that don't support PAE!
918 The actual amount of total physical memory will either be
919 auto detected or can be forced by using a kernel command line option
920 such as "mem=256M". (Try "man bootparam" or see the documentation of
921 your boot loader (lilo or loadlin) about how to pass options to the
922 kernel at boot time.)
924 If unsure, say "off".
928 depends on !X86_NUMAQ
930 Select this if you have a 32-bit processor and between 1 and 4
931 gigabytes of physical RAM.
935 depends on !M386 && !M486
938 Select this if you have a 32-bit processor and more than 4
939 gigabytes of physical RAM.
944 depends on EXPERIMENTAL
945 prompt "Memory split" if EMBEDDED
949 Select the desired split between kernel and user memory.
951 If the address range available to the kernel is less than the
952 physical memory installed, the remaining memory will be available
953 as "high memory". Accessing high memory is a little more costly
954 than low memory, as it needs to be mapped into the kernel first.
955 Note that increasing the kernel address space limits the range
956 available to user programs, making the address space there
957 tighter. Selecting anything other than the default 3G/1G split
958 will also likely make your kernel incompatible with binary-only
961 If you are not absolutely sure what you are doing, leave this
965 bool "3G/1G user/kernel split"
966 config VMSPLIT_3G_OPT
968 bool "3G/1G user/kernel split (for full 1G low memory)"
970 bool "2G/2G user/kernel split"
971 config VMSPLIT_2G_OPT
973 bool "2G/2G user/kernel split (for full 2G low memory)"
975 bool "1G/3G user/kernel split"
980 default 0xB0000000 if VMSPLIT_3G_OPT
981 default 0x80000000 if VMSPLIT_2G
982 default 0x78000000 if VMSPLIT_2G_OPT
983 default 0x40000000 if VMSPLIT_1G
989 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
992 bool "PAE (Physical Address Extension) Support"
993 depends on X86_32 && !HIGHMEM4G
995 PAE is required for NX support, and furthermore enables
996 larger swapspace support for non-overcommit purposes. It
997 has the cost of more pagetable lookup overhead, and also
998 consumes more pagetable space per process.
1000 config ARCH_PHYS_ADDR_T_64BIT
1001 def_bool X86_64 || X86_PAE
1003 config DIRECT_GBPAGES
1004 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1008 Allow the kernel linear mapping to use 1GB pages on CPUs that
1009 support it. This can improve the kernel's performance a tiny bit by
1010 reducing TLB pressure. If in doubt, say "Y".
1012 # Common NUMA Features
1014 bool "Numa Memory Allocation and Scheduler Support"
1016 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1018 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1020 Enable NUMA (Non Uniform Memory Access) support.
1022 The kernel will try to allocate memory used by a CPU on the
1023 local memory controller of the CPU and add some more
1024 NUMA awareness to the kernel.
1026 For 64-bit this is recommended if the system is Intel Core i7
1027 (or later), AMD Opteron, or EM64T NUMA.
1029 For 32-bit this is only needed on (rare) 32-bit-only platforms
1030 that support NUMA topologies, such as NUMAQ / Summit, or if you
1031 boot a 32-bit kernel on a 64-bit NUMA platform.
1033 Otherwise, you should say N.
1035 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1036 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1040 prompt "Old style AMD Opteron NUMA detection"
1041 depends on X86_64 && NUMA && PCI
1043 Enable K8 NUMA node topology detection. You should say Y here if
1044 you have a multi processor AMD K8 system. This uses an old
1045 method to read the NUMA configuration directly from the builtin
1046 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1047 instead, which also takes priority if both are compiled in.
1049 config X86_64_ACPI_NUMA
1051 prompt "ACPI NUMA detection"
1052 depends on X86_64 && NUMA && ACPI && PCI
1055 Enable ACPI SRAT based node topology detection.
1057 # Some NUMA nodes have memory ranges that span
1058 # other nodes. Even though a pfn is valid and
1059 # between a node's start and end pfns, it may not
1060 # reside on that node. See memmap_init_zone()
1062 config NODES_SPAN_OTHER_NODES
1064 depends on X86_64_ACPI_NUMA
1067 bool "NUMA emulation"
1068 depends on X86_64 && NUMA
1070 Enable NUMA emulation. A flat machine will be split
1071 into virtual nodes when booted with "numa=fake=N", where N is the
1072 number of nodes. This is only useful for debugging.
1075 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1077 default "9" if MAXSMP
1078 default "6" if X86_64
1079 default "4" if X86_NUMAQ
1081 depends on NEED_MULTIPLE_NODES
1083 Specify the maximum number of NUMA Nodes available on the target
1084 system. Increases memory reserved to accomodate various tables.
1086 config HAVE_ARCH_BOOTMEM_NODE
1088 depends on X86_32 && NUMA
1090 config ARCH_HAVE_MEMORY_PRESENT
1092 depends on X86_32 && DISCONTIGMEM
1094 config NEED_NODE_MEMMAP_SIZE
1096 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1098 config HAVE_ARCH_ALLOC_REMAP
1100 depends on X86_32 && NUMA
1102 config ARCH_FLATMEM_ENABLE
1104 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1106 config ARCH_DISCONTIGMEM_ENABLE
1108 depends on NUMA && X86_32
1110 config ARCH_DISCONTIGMEM_DEFAULT
1112 depends on NUMA && X86_32
1114 config ARCH_SPARSEMEM_DEFAULT
1118 config ARCH_SPARSEMEM_ENABLE
1120 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC) || X86_GENERICARCH
1121 select SPARSEMEM_STATIC if X86_32
1122 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1124 config ARCH_SELECT_MEMORY_MODEL
1126 depends on ARCH_SPARSEMEM_ENABLE
1128 config ARCH_MEMORY_PROBE
1130 depends on MEMORY_HOTPLUG
1135 bool "Allocate 3rd-level pagetables from highmem"
1136 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1138 The VM uses one page table entry for each page of physical memory.
1139 For systems with a lot of RAM, this can be wasteful of precious
1140 low memory. Setting this option will put user-space page table
1141 entries in high memory.
1143 config X86_CHECK_BIOS_CORRUPTION
1144 bool "Check for low memory corruption"
1146 Periodically check for memory corruption in low memory, which
1147 is suspected to be caused by BIOS. Even when enabled in the
1148 configuration, it is disabled at runtime. Enable it by
1149 setting "memory_corruption_check=1" on the kernel command
1150 line. By default it scans the low 64k of memory every 60
1151 seconds; see the memory_corruption_check_size and
1152 memory_corruption_check_period parameters in
1153 Documentation/kernel-parameters.txt to adjust this.
1155 When enabled with the default parameters, this option has
1156 almost no overhead, as it reserves a relatively small amount
1157 of memory and scans it infrequently. It both detects corruption
1158 and prevents it from affecting the running system.
1160 It is, however, intended as a diagnostic tool; if repeatable
1161 BIOS-originated corruption always affects the same memory,
1162 you can use memmap= to prevent the kernel from using that
1165 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1166 bool "Set the default setting of memory_corruption_check"
1167 depends on X86_CHECK_BIOS_CORRUPTION
1170 Set whether the default state of memory_corruption_check is
1173 config X86_RESERVE_LOW_64K
1174 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1177 Reserve the first 64K of physical RAM on BIOSes that are known
1178 to potentially corrupt that memory range. A numbers of BIOSes are
1179 known to utilize this area during suspend/resume, so it must not
1180 be used by the kernel.
1182 Set this to N if you are absolutely sure that you trust the BIOS
1183 to get all its memory reservations and usages right.
1185 If you have doubts about the BIOS (e.g. suspend/resume does not
1186 work or there's kernel crashes after certain hardware hotplug
1187 events) and it's not AMI or Phoenix, then you might want to enable
1188 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1189 corruption patterns.
1193 config MATH_EMULATION
1195 prompt "Math emulation" if X86_32
1197 Linux can emulate a math coprocessor (used for floating point
1198 operations) if you don't have one. 486DX and Pentium processors have
1199 a math coprocessor built in, 486SX and 386 do not, unless you added
1200 a 487DX or 387, respectively. (The messages during boot time can
1201 give you some hints here ["man dmesg"].) Everyone needs either a
1202 coprocessor or this emulation.
1204 If you don't have a math coprocessor, you need to say Y here; if you
1205 say Y here even though you have a coprocessor, the coprocessor will
1206 be used nevertheless. (This behavior can be changed with the kernel
1207 command line option "no387", which comes handy if your coprocessor
1208 is broken. Try "man bootparam" or see the documentation of your boot
1209 loader (lilo or loadlin) about how to pass options to the kernel at
1210 boot time.) This means that it is a good idea to say Y here if you
1211 intend to use this kernel on different machines.
1213 More information about the internals of the Linux math coprocessor
1214 emulation can be found in <file:arch/x86/math-emu/README>.
1216 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1217 kernel, it won't hurt.
1220 bool "MTRR (Memory Type Range Register) support"
1222 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1223 the Memory Type Range Registers (MTRRs) may be used to control
1224 processor access to memory ranges. This is most useful if you have
1225 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1226 allows bus write transfers to be combined into a larger transfer
1227 before bursting over the PCI/AGP bus. This can increase performance
1228 of image write operations 2.5 times or more. Saying Y here creates a
1229 /proc/mtrr file which may be used to manipulate your processor's
1230 MTRRs. Typically the X server should use this.
1232 This code has a reasonably generic interface so that similar
1233 control registers on other processors can be easily supported
1236 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1237 Registers (ARRs) which provide a similar functionality to MTRRs. For
1238 these, the ARRs are used to emulate the MTRRs.
1239 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1240 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1241 write-combining. All of these processors are supported by this code
1242 and it makes sense to say Y here if you have one of them.
1244 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1245 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1246 can lead to all sorts of problems, so it's good to say Y here.
1248 You can safely say Y even if your machine doesn't have MTRRs, you'll
1249 just add about 9 KB to your kernel.
1251 See <file:Documentation/x86/mtrr.txt> for more information.
1253 config MTRR_SANITIZER
1255 prompt "MTRR cleanup support"
1258 Convert MTRR layout from continuous to discrete, so X drivers can
1259 add writeback entries.
1261 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1262 The largest mtrr entry size for a continous block can be set with
1267 config MTRR_SANITIZER_ENABLE_DEFAULT
1268 int "MTRR cleanup enable value (0-1)"
1271 depends on MTRR_SANITIZER
1273 Enable mtrr cleanup default value
1275 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1276 int "MTRR cleanup spare reg num (0-7)"
1279 depends on MTRR_SANITIZER
1281 mtrr cleanup spare entries default, it can be changed via
1282 mtrr_spare_reg_nr=N on the kernel command line.
1286 prompt "x86 PAT support"
1289 Use PAT attributes to setup page level cache control.
1291 PATs are the modern equivalents of MTRRs and are much more
1292 flexible than MTRRs.
1294 Say N here if you see bootup problems (boot crash, boot hang,
1295 spontaneous reboots) or a non-working video driver.
1300 bool "EFI runtime service support"
1303 This enables the kernel to use EFI runtime services that are
1304 available (such as the EFI variable services).
1306 This option is only useful on systems that have EFI firmware.
1307 In addition, you should use the latest ELILO loader available
1308 at <http://elilo.sourceforge.net> in order to take advantage
1309 of EFI runtime services. However, even with this option, the
1310 resultant kernel should continue to boot on existing non-EFI
1315 prompt "Enable seccomp to safely compute untrusted bytecode"
1317 This kernel feature is useful for number crunching applications
1318 that may need to compute untrusted bytecode during their
1319 execution. By using pipes or other transports made available to
1320 the process as file descriptors supporting the read/write
1321 syscalls, it's possible to isolate those applications in
1322 their own address space using seccomp. Once seccomp is
1323 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1324 and the task is only allowed to execute a few safe syscalls
1325 defined by each seccomp mode.
1327 If unsure, say Y. Only embedded should say N here.
1329 config CC_STACKPROTECTOR
1330 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1331 depends on X86_64 && EXPERIMENTAL && BROKEN
1333 This option turns on the -fstack-protector GCC feature. This
1334 feature puts, at the beginning of critical functions, a canary
1335 value on the stack just before the return address, and validates
1336 the value just before actually returning. Stack based buffer
1337 overflows (that need to overwrite this return address) now also
1338 overwrite the canary, which gets detected and the attack is then
1339 neutralized via a kernel panic.
1341 This feature requires gcc version 4.2 or above, or a distribution
1342 gcc with the feature backported. Older versions are automatically
1343 detected and for those versions, this configuration option is ignored.
1345 config CC_STACKPROTECTOR_ALL
1346 bool "Use stack-protector for all functions"
1347 depends on CC_STACKPROTECTOR
1349 Normally, GCC only inserts the canary value protection for
1350 functions that use large-ish on-stack buffers. By enabling
1351 this option, GCC will be asked to do this for ALL functions.
1353 source kernel/Kconfig.hz
1356 bool "kexec system call"
1357 depends on X86_BIOS_REBOOT
1359 kexec is a system call that implements the ability to shutdown your
1360 current kernel, and to start another kernel. It is like a reboot
1361 but it is independent of the system firmware. And like a reboot
1362 you can start any kernel with it, not just Linux.
1364 The name comes from the similarity to the exec system call.
1366 It is an ongoing process to be certain the hardware in a machine
1367 is properly shutdown, so do not be surprised if this code does not
1368 initially work for you. It may help to enable device hotplugging
1369 support. As of this writing the exact hardware interface is
1370 strongly in flux, so no good recommendation can be made.
1373 bool "kernel crash dumps"
1374 depends on X86_64 || (X86_32 && HIGHMEM)
1376 Generate crash dump after being started by kexec.
1377 This should be normally only set in special crash dump kernels
1378 which are loaded in the main kernel with kexec-tools into
1379 a specially reserved region and then later executed after
1380 a crash by kdump/kexec. The crash dump kernel must be compiled
1381 to a memory address not used by the main kernel or BIOS using
1382 PHYSICAL_START, or it must be built as a relocatable image
1383 (CONFIG_RELOCATABLE=y).
1384 For more details see Documentation/kdump/kdump.txt
1387 bool "kexec jump (EXPERIMENTAL)"
1388 depends on EXPERIMENTAL
1389 depends on KEXEC && HIBERNATION && X86_32
1391 Jump between original kernel and kexeced kernel and invoke
1392 code in physical address mode via KEXEC
1394 config PHYSICAL_START
1395 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1396 default "0x1000000" if X86_NUMAQ
1397 default "0x200000" if X86_64
1400 This gives the physical address where the kernel is loaded.
1402 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1403 bzImage will decompress itself to above physical address and
1404 run from there. Otherwise, bzImage will run from the address where
1405 it has been loaded by the boot loader and will ignore above physical
1408 In normal kdump cases one does not have to set/change this option
1409 as now bzImage can be compiled as a completely relocatable image
1410 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1411 address. This option is mainly useful for the folks who don't want
1412 to use a bzImage for capturing the crash dump and want to use a
1413 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1414 to be specifically compiled to run from a specific memory area
1415 (normally a reserved region) and this option comes handy.
1417 So if you are using bzImage for capturing the crash dump, leave
1418 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1419 Otherwise if you plan to use vmlinux for capturing the crash dump
1420 change this value to start of the reserved region (Typically 16MB
1421 0x1000000). In other words, it can be set based on the "X" value as
1422 specified in the "crashkernel=YM@XM" command line boot parameter
1423 passed to the panic-ed kernel. Typically this parameter is set as
1424 crashkernel=64M@16M. Please take a look at
1425 Documentation/kdump/kdump.txt for more details about crash dumps.
1427 Usage of bzImage for capturing the crash dump is recommended as
1428 one does not have to build two kernels. Same kernel can be used
1429 as production kernel and capture kernel. Above option should have
1430 gone away after relocatable bzImage support is introduced. But it
1431 is present because there are users out there who continue to use
1432 vmlinux for dump capture. This option should go away down the
1435 Don't change this unless you know what you are doing.
1438 bool "Build a relocatable kernel (EXPERIMENTAL)"
1439 depends on EXPERIMENTAL
1441 This builds a kernel image that retains relocation information
1442 so it can be loaded someplace besides the default 1MB.
1443 The relocations tend to make the kernel binary about 10% larger,
1444 but are discarded at runtime.
1446 One use is for the kexec on panic case where the recovery kernel
1447 must live at a different physical address than the primary
1450 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1451 it has been loaded at and the compile time physical address
1452 (CONFIG_PHYSICAL_START) is ignored.
1454 config PHYSICAL_ALIGN
1456 prompt "Alignment value to which kernel should be aligned" if X86_32
1457 default "0x100000" if X86_32
1458 default "0x200000" if X86_64
1459 range 0x2000 0x400000
1461 This value puts the alignment restrictions on physical address
1462 where kernel is loaded and run from. Kernel is compiled for an
1463 address which meets above alignment restriction.
1465 If bootloader loads the kernel at a non-aligned address and
1466 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1467 address aligned to above value and run from there.
1469 If bootloader loads the kernel at a non-aligned address and
1470 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1471 load address and decompress itself to the address it has been
1472 compiled for and run from there. The address for which kernel is
1473 compiled already meets above alignment restrictions. Hence the
1474 end result is that kernel runs from a physical address meeting
1475 above alignment restrictions.
1477 Don't change this unless you know what you are doing.
1480 bool "Support for hot-pluggable CPUs"
1481 depends on SMP && HOTPLUG && !X86_VOYAGER
1483 Say Y here to allow turning CPUs off and on. CPUs can be
1484 controlled through /sys/devices/system/cpu.
1485 ( Note: power management support will enable this option
1486 automatically on SMP systems. )
1487 Say N if you want to disable CPU hotplug.
1491 prompt "Compat VDSO support"
1492 depends on X86_32 || IA32_EMULATION
1494 Map the 32-bit VDSO to the predictable old-style address too.
1496 Say N here if you are running a sufficiently recent glibc
1497 version (2.3.3 or later), to remove the high-mapped
1498 VDSO mapping and to exclusively use the randomized VDSO.
1503 bool "Built-in kernel command line"
1506 Allow for specifying boot arguments to the kernel at
1507 build time. On some systems (e.g. embedded ones), it is
1508 necessary or convenient to provide some or all of the
1509 kernel boot arguments with the kernel itself (that is,
1510 to not rely on the boot loader to provide them.)
1512 To compile command line arguments into the kernel,
1513 set this option to 'Y', then fill in the
1514 the boot arguments in CONFIG_CMDLINE.
1516 Systems with fully functional boot loaders (i.e. non-embedded)
1517 should leave this option set to 'N'.
1520 string "Built-in kernel command string"
1521 depends on CMDLINE_BOOL
1524 Enter arguments here that should be compiled into the kernel
1525 image and used at boot time. If the boot loader provides a
1526 command line at boot time, it is appended to this string to
1527 form the full kernel command line, when the system boots.
1529 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1530 change this behavior.
1532 In most cases, the command line (whether built-in or provided
1533 by the boot loader) should specify the device for the root
1536 config CMDLINE_OVERRIDE
1537 bool "Built-in command line overrides boot loader arguments"
1539 depends on CMDLINE_BOOL
1541 Set this option to 'Y' to have the kernel ignore the boot loader
1542 command line, and use ONLY the built-in command line.
1544 This is used to work around broken boot loaders. This should
1545 be set to 'N' under normal conditions.
1549 config ARCH_ENABLE_MEMORY_HOTPLUG
1551 depends on X86_64 || (X86_32 && HIGHMEM)
1553 config ARCH_ENABLE_MEMORY_HOTREMOVE
1555 depends on MEMORY_HOTPLUG
1557 config HAVE_ARCH_EARLY_PFN_TO_NID
1561 menu "Power management and ACPI options"
1562 depends on !X86_VOYAGER
1564 config ARCH_HIBERNATION_HEADER
1566 depends on X86_64 && HIBERNATION
1568 source "kernel/power/Kconfig"
1570 source "drivers/acpi/Kconfig"
1575 depends on APM || APM_MODULE
1578 tristate "APM (Advanced Power Management) BIOS support"
1579 depends on X86_32 && PM_SLEEP
1581 APM is a BIOS specification for saving power using several different
1582 techniques. This is mostly useful for battery powered laptops with
1583 APM compliant BIOSes. If you say Y here, the system time will be
1584 reset after a RESUME operation, the /proc/apm device will provide
1585 battery status information, and user-space programs will receive
1586 notification of APM "events" (e.g. battery status change).
1588 If you select "Y" here, you can disable actual use of the APM
1589 BIOS by passing the "apm=off" option to the kernel at boot time.
1591 Note that the APM support is almost completely disabled for
1592 machines with more than one CPU.
1594 In order to use APM, you will need supporting software. For location
1595 and more information, read <file:Documentation/power/pm.txt> and the
1596 Battery Powered Linux mini-HOWTO, available from
1597 <http://www.tldp.org/docs.html#howto>.
1599 This driver does not spin down disk drives (see the hdparm(8)
1600 manpage ("man 8 hdparm") for that), and it doesn't turn off
1601 VESA-compliant "green" monitors.
1603 This driver does not support the TI 4000M TravelMate and the ACER
1604 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1605 desktop machines also don't have compliant BIOSes, and this driver
1606 may cause those machines to panic during the boot phase.
1608 Generally, if you don't have a battery in your machine, there isn't
1609 much point in using this driver and you should say N. If you get
1610 random kernel OOPSes or reboots that don't seem to be related to
1611 anything, try disabling/enabling this option (or disabling/enabling
1614 Some other things you should try when experiencing seemingly random,
1617 1) make sure that you have enough swap space and that it is
1619 2) pass the "no-hlt" option to the kernel
1620 3) switch on floating point emulation in the kernel and pass
1621 the "no387" option to the kernel
1622 4) pass the "floppy=nodma" option to the kernel
1623 5) pass the "mem=4M" option to the kernel (thereby disabling
1624 all but the first 4 MB of RAM)
1625 6) make sure that the CPU is not over clocked.
1626 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1627 8) disable the cache from your BIOS settings
1628 9) install a fan for the video card or exchange video RAM
1629 10) install a better fan for the CPU
1630 11) exchange RAM chips
1631 12) exchange the motherboard.
1633 To compile this driver as a module, choose M here: the
1634 module will be called apm.
1638 config APM_IGNORE_USER_SUSPEND
1639 bool "Ignore USER SUSPEND"
1641 This option will ignore USER SUSPEND requests. On machines with a
1642 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1643 series notebooks, it is necessary to say Y because of a BIOS bug.
1645 config APM_DO_ENABLE
1646 bool "Enable PM at boot time"
1648 Enable APM features at boot time. From page 36 of the APM BIOS
1649 specification: "When disabled, the APM BIOS does not automatically
1650 power manage devices, enter the Standby State, enter the Suspend
1651 State, or take power saving steps in response to CPU Idle calls."
1652 This driver will make CPU Idle calls when Linux is idle (unless this
1653 feature is turned off -- see "Do CPU IDLE calls", below). This
1654 should always save battery power, but more complicated APM features
1655 will be dependent on your BIOS implementation. You may need to turn
1656 this option off if your computer hangs at boot time when using APM
1657 support, or if it beeps continuously instead of suspending. Turn
1658 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1659 T400CDT. This is off by default since most machines do fine without
1663 bool "Make CPU Idle calls when idle"
1665 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1666 On some machines, this can activate improved power savings, such as
1667 a slowed CPU clock rate, when the machine is idle. These idle calls
1668 are made after the idle loop has run for some length of time (e.g.,
1669 333 mS). On some machines, this will cause a hang at boot time or
1670 whenever the CPU becomes idle. (On machines with more than one CPU,
1671 this option does nothing.)
1673 config APM_DISPLAY_BLANK
1674 bool "Enable console blanking using APM"
1676 Enable console blanking using the APM. Some laptops can use this to
1677 turn off the LCD backlight when the screen blanker of the Linux
1678 virtual console blanks the screen. Note that this is only used by
1679 the virtual console screen blanker, and won't turn off the backlight
1680 when using the X Window system. This also doesn't have anything to
1681 do with your VESA-compliant power-saving monitor. Further, this
1682 option doesn't work for all laptops -- it might not turn off your
1683 backlight at all, or it might print a lot of errors to the console,
1684 especially if you are using gpm.
1686 config APM_ALLOW_INTS
1687 bool "Allow interrupts during APM BIOS calls"
1689 Normally we disable external interrupts while we are making calls to
1690 the APM BIOS as a measure to lessen the effects of a badly behaving
1691 BIOS implementation. The BIOS should reenable interrupts if it
1692 needs to. Unfortunately, some BIOSes do not -- especially those in
1693 many of the newer IBM Thinkpads. If you experience hangs when you
1694 suspend, try setting this to Y. Otherwise, say N.
1698 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1700 source "drivers/cpuidle/Kconfig"
1702 source "drivers/idle/Kconfig"
1707 menu "Bus options (PCI etc.)"
1712 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1714 Find out whether you have a PCI motherboard. PCI is the name of a
1715 bus system, i.e. the way the CPU talks to the other stuff inside
1716 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1717 VESA. If you have PCI, say Y, otherwise N.
1720 prompt "PCI access mode"
1721 depends on X86_32 && PCI
1724 On PCI systems, the BIOS can be used to detect the PCI devices and
1725 determine their configuration. However, some old PCI motherboards
1726 have BIOS bugs and may crash if this is done. Also, some embedded
1727 PCI-based systems don't have any BIOS at all. Linux can also try to
1728 detect the PCI hardware directly without using the BIOS.
1730 With this option, you can specify how Linux should detect the
1731 PCI devices. If you choose "BIOS", the BIOS will be used,
1732 if you choose "Direct", the BIOS won't be used, and if you
1733 choose "MMConfig", then PCI Express MMCONFIG will be used.
1734 If you choose "Any", the kernel will try MMCONFIG, then the
1735 direct access method and falls back to the BIOS if that doesn't
1736 work. If unsure, go with the default, which is "Any".
1741 config PCI_GOMMCONFIG
1758 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1760 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1763 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1767 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1771 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1778 bool "Support mmconfig PCI config space access"
1779 depends on X86_64 && PCI && ACPI
1782 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1783 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1785 DMA remapping (DMAR) devices support enables independent address
1786 translations for Direct Memory Access (DMA) from devices.
1787 These DMA remapping devices are reported via ACPI tables
1788 and include PCI device scope covered by these DMA
1793 prompt "Support for Graphics workaround"
1796 Current Graphics drivers tend to use physical address
1797 for DMA and avoid using DMA APIs. Setting this config
1798 option permits the IOMMU driver to set a unity map for
1799 all the OS-visible memory. Hence the driver can continue
1800 to use physical addresses for DMA.
1802 config DMAR_FLOPPY_WA
1806 Floppy disk drivers are know to bypass DMA API calls
1807 thereby failing to work when IOMMU is enabled. This
1808 workaround will setup a 1:1 mapping for the first
1809 16M to make floppy (an ISA device) work.
1812 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1813 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1815 Supports Interrupt remapping for IO-APIC and MSI devices.
1816 To use x2apic mode in the CPU's which support x2APIC enhancements or
1817 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1819 source "drivers/pci/pcie/Kconfig"
1821 source "drivers/pci/Kconfig"
1823 # x86_64 have no ISA slots, but do have ISA-style DMA.
1831 depends on !X86_VOYAGER
1833 Find out whether you have ISA slots on your motherboard. ISA is the
1834 name of a bus system, i.e. the way the CPU talks to the other stuff
1835 inside your box. Other bus systems are PCI, EISA, MicroChannel
1836 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1837 newer boards don't support it. If you have ISA, say Y, otherwise N.
1843 The Extended Industry Standard Architecture (EISA) bus was
1844 developed as an open alternative to the IBM MicroChannel bus.
1846 The EISA bus provided some of the features of the IBM MicroChannel
1847 bus while maintaining backward compatibility with cards made for
1848 the older ISA bus. The EISA bus saw limited use between 1988 and
1849 1995 when it was made obsolete by the PCI bus.
1851 Say Y here if you are building a kernel for an EISA-based machine.
1855 source "drivers/eisa/Kconfig"
1858 bool "MCA support" if !X86_VOYAGER
1859 default y if X86_VOYAGER
1861 MicroChannel Architecture is found in some IBM PS/2 machines and
1862 laptops. It is a bus system similar to PCI or ISA. See
1863 <file:Documentation/mca.txt> (and especially the web page given
1864 there) before attempting to build an MCA bus kernel.
1866 source "drivers/mca/Kconfig"
1869 tristate "NatSemi SCx200 support"
1870 depends on !X86_VOYAGER
1872 This provides basic support for National Semiconductor's
1873 (now AMD's) Geode processors. The driver probes for the
1874 PCI-IDs of several on-chip devices, so its a good dependency
1875 for other scx200_* drivers.
1877 If compiled as a module, the driver is named scx200.
1879 config SCx200HR_TIMER
1880 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1881 depends on SCx200 && GENERIC_TIME
1884 This driver provides a clocksource built upon the on-chip
1885 27MHz high-resolution timer. Its also a workaround for
1886 NSC Geode SC-1100's buggy TSC, which loses time when the
1887 processor goes idle (as is done by the scheduler). The
1888 other workaround is idle=poll boot option.
1890 config GEODE_MFGPT_TIMER
1892 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1893 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1895 This driver provides a clock event source based on the MFGPT
1896 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1897 MFGPTs have a better resolution and max interval than the
1898 generic PIT, and are suitable for use as high-res timers.
1901 bool "One Laptop Per Child support"
1904 Add support for detecting the unique features of the OLPC
1911 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1913 source "drivers/pcmcia/Kconfig"
1915 source "drivers/pci/hotplug/Kconfig"
1920 menu "Executable file formats / Emulations"
1922 source "fs/Kconfig.binfmt"
1924 config IA32_EMULATION
1925 bool "IA32 Emulation"
1927 select COMPAT_BINFMT_ELF
1929 Include code to run 32-bit programs under a 64-bit kernel. You should
1930 likely turn this on, unless you're 100% sure that you don't have any
1931 32-bit programs left.
1934 tristate "IA32 a.out support"
1935 depends on IA32_EMULATION
1937 Support old a.out binaries in the 32bit emulation.
1941 depends on IA32_EMULATION
1943 config COMPAT_FOR_U64_ALIGNMENT
1947 config SYSVIPC_COMPAT
1949 depends on COMPAT && SYSVIPC
1954 config HAVE_ATOMIC_IOMAP
1958 source "net/Kconfig"
1960 source "drivers/Kconfig"
1962 source "drivers/firmware/Kconfig"
1966 source "arch/x86/Kconfig.debug"
1968 source "security/Kconfig"
1970 source "crypto/Kconfig"
1972 source "arch/x86/kvm/Kconfig"
1974 source "lib/Kconfig"
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