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 def_bool (AMD_IOMMU || DMAR)
606 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
607 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
608 select CPUMASK_OFFSTACK
611 Configure maximum number of CPUS and NUMA Nodes for this architecture.
615 int "Maximum number of CPUs" if SMP && !MAXSMP
616 range 2 512 if SMP && !MAXSMP
618 default "4096" if MAXSMP
619 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
622 This allows you to specify the maximum number of CPUs which this
623 kernel will support. The maximum supported value is 512 and the
624 minimum value which makes sense is 2.
626 This is purely to save memory - each supported CPU adds
627 approximately eight kilobytes to the kernel image.
630 bool "SMT (Hyperthreading) scheduler support"
633 SMT scheduler support improves the CPU scheduler's decision making
634 when dealing with Intel Pentium 4 chips with HyperThreading at a
635 cost of slightly increased overhead in some places. If unsure say
640 prompt "Multi-core scheduler support"
643 Multi-core scheduler support improves the CPU scheduler's decision
644 making when dealing with multi-core CPU chips at a cost of slightly
645 increased overhead in some places. If unsure say N here.
647 source "kernel/Kconfig.preempt"
650 bool "Local APIC support on uniprocessors"
651 depends on X86_32 && !SMP && !(X86_VOYAGER || X86_GENERICARCH)
653 A local APIC (Advanced Programmable Interrupt Controller) is an
654 integrated interrupt controller in the CPU. If you have a single-CPU
655 system which has a processor with a local APIC, you can say Y here to
656 enable and use it. If you say Y here even though your machine doesn't
657 have a local APIC, then the kernel will still run with no slowdown at
658 all. The local APIC supports CPU-generated self-interrupts (timer,
659 performance counters), and the NMI watchdog which detects hard
663 bool "IO-APIC support on uniprocessors"
664 depends on X86_UP_APIC
666 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
667 SMP-capable replacement for PC-style interrupt controllers. Most
668 SMP systems and many recent uniprocessor systems have one.
670 If you have a single-CPU system with an IO-APIC, you can say Y here
671 to use it. If you say Y here even though your machine doesn't have
672 an IO-APIC, then the kernel will still run with no slowdown at all.
674 config X86_LOCAL_APIC
676 depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
680 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
682 config X86_VISWS_APIC
684 depends on X86_32 && X86_VISWS
686 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
687 bool "Reroute for broken boot IRQs"
689 depends on X86_IO_APIC
691 This option enables a workaround that fixes a source of
692 spurious interrupts. This is recommended when threaded
693 interrupt handling is used on systems where the generation of
694 superfluous "boot interrupts" cannot be disabled.
696 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
697 entry in the chipset's IO-APIC is masked (as, e.g. the RT
698 kernel does during interrupt handling). On chipsets where this
699 boot IRQ generation cannot be disabled, this workaround keeps
700 the original IRQ line masked so that only the equivalent "boot
701 IRQ" is delivered to the CPUs. The workaround also tells the
702 kernel to set up the IRQ handler on the boot IRQ line. In this
703 way only one interrupt is delivered to the kernel. Otherwise
704 the spurious second interrupt may cause the kernel to bring
705 down (vital) interrupt lines.
707 Only affects "broken" chipsets. Interrupt sharing may be
708 increased on these systems.
711 bool "Machine Check Exception"
712 depends on !X86_VOYAGER
714 Machine Check Exception support allows the processor to notify the
715 kernel if it detects a problem (e.g. overheating, component failure).
716 The action the kernel takes depends on the severity of the problem,
717 ranging from a warning message on the console, to halting the machine.
718 Your processor must be a Pentium or newer to support this - check the
719 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
720 have a design flaw which leads to false MCE events - hence MCE is
721 disabled on all P5 processors, unless explicitly enabled with "mce"
722 as a boot argument. Similarly, if MCE is built in and creates a
723 problem on some new non-standard machine, you can boot with "nomce"
724 to disable it. MCE support simply ignores non-MCE processors like
725 the 386 and 486, so nearly everyone can say Y here.
729 prompt "Intel MCE features"
730 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
732 Additional support for intel specific MCE features such as
737 prompt "AMD MCE features"
738 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
740 Additional support for AMD specific MCE features such as
741 the DRAM Error Threshold.
743 config X86_MCE_NONFATAL
744 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
745 depends on X86_32 && X86_MCE
747 Enabling this feature starts a timer that triggers every 5 seconds which
748 will look at the machine check registers to see if anything happened.
749 Non-fatal problems automatically get corrected (but still logged).
750 Disable this if you don't want to see these messages.
751 Seeing the messages this option prints out may be indicative of dying
752 or out-of-spec (ie, overclocked) hardware.
753 This option only does something on certain CPUs.
754 (AMD Athlon/Duron and Intel Pentium 4)
756 config X86_MCE_P4THERMAL
757 bool "check for P4 thermal throttling interrupt."
758 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
760 Enabling this feature will cause a message to be printed when the P4
761 enters thermal throttling.
764 bool "Enable VM86 support" if EMBEDDED
768 This option is required by programs like DOSEMU to run 16-bit legacy
769 code on X86 processors. It also may be needed by software like
770 XFree86 to initialize some video cards via BIOS. Disabling this
771 option saves about 6k.
774 tristate "Toshiba Laptop support"
777 This adds a driver to safely access the System Management Mode of
778 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
779 not work on models with a Phoenix BIOS. The System Management Mode
780 is used to set the BIOS and power saving options on Toshiba portables.
782 For information on utilities to make use of this driver see the
783 Toshiba Linux utilities web site at:
784 <http://www.buzzard.org.uk/toshiba/>.
786 Say Y if you intend to run this kernel on a Toshiba portable.
790 tristate "Dell laptop support"
792 This adds a driver to safely access the System Management Mode
793 of the CPU on the Dell Inspiron 8000. The System Management Mode
794 is used to read cpu temperature and cooling fan status and to
795 control the fans on the I8K portables.
797 This driver has been tested only on the Inspiron 8000 but it may
798 also work with other Dell laptops. You can force loading on other
799 models by passing the parameter `force=1' to the module. Use at
802 For information on utilities to make use of this driver see the
803 I8K Linux utilities web site at:
804 <http://people.debian.org/~dz/i8k/>
806 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
809 config X86_REBOOTFIXUPS
810 bool "Enable X86 board specific fixups for reboot"
813 This enables chipset and/or board specific fixups to be done
814 in order to get reboot to work correctly. This is only needed on
815 some combinations of hardware and BIOS. The symptom, for which
816 this config is intended, is when reboot ends with a stalled/hung
819 Currently, the only fixup is for the Geode machines using
820 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
822 Say Y if you want to enable the fixup. Currently, it's safe to
823 enable this option even if you don't need it.
827 tristate "/dev/cpu/microcode - microcode support"
830 If you say Y here, you will be able to update the microcode on
831 certain Intel and AMD processors. The Intel support is for the
832 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
833 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
834 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
835 You will obviously need the actual microcode binary data itself
836 which is not shipped with the Linux kernel.
838 This option selects the general module only, you need to select
839 at least one vendor specific module as well.
841 To compile this driver as a module, choose M here: the
842 module will be called microcode.
844 config MICROCODE_INTEL
845 bool "Intel microcode patch loading support"
850 This options enables microcode patch loading support for Intel
853 For latest news and information on obtaining all the required
854 Intel ingredients for this driver, check:
855 <http://www.urbanmyth.org/microcode/>.
858 bool "AMD microcode patch loading support"
862 If you select this option, microcode patch loading support for AMD
863 processors will be enabled.
865 config MICROCODE_OLD_INTERFACE
870 tristate "/dev/cpu/*/msr - Model-specific register support"
872 This device gives privileged processes access to the x86
873 Model-Specific Registers (MSRs). It is a character device with
874 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
875 MSR accesses are directed to a specific CPU on multi-processor
879 tristate "/dev/cpu/*/cpuid - CPU information support"
881 This device gives processes access to the x86 CPUID instruction to
882 be executed on a specific processor. It is a character device
883 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
887 prompt "High Memory Support"
888 default HIGHMEM4G if !X86_NUMAQ
889 default HIGHMEM64G if X86_NUMAQ
894 depends on !X86_NUMAQ
896 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
897 However, the address space of 32-bit x86 processors is only 4
898 Gigabytes large. That means that, if you have a large amount of
899 physical memory, not all of it can be "permanently mapped" by the
900 kernel. The physical memory that's not permanently mapped is called
903 If you are compiling a kernel which will never run on a machine with
904 more than 1 Gigabyte total physical RAM, answer "off" here (default
905 choice and suitable for most users). This will result in a "3GB/1GB"
906 split: 3GB are mapped so that each process sees a 3GB virtual memory
907 space and the remaining part of the 4GB virtual memory space is used
908 by the kernel to permanently map as much physical memory as
911 If the machine has between 1 and 4 Gigabytes physical RAM, then
914 If more than 4 Gigabytes is used then answer "64GB" here. This
915 selection turns Intel PAE (Physical Address Extension) mode on.
916 PAE implements 3-level paging on IA32 processors. PAE is fully
917 supported by Linux, PAE mode is implemented on all recent Intel
918 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
919 then the kernel will not boot on CPUs that don't support PAE!
921 The actual amount of total physical memory will either be
922 auto detected or can be forced by using a kernel command line option
923 such as "mem=256M". (Try "man bootparam" or see the documentation of
924 your boot loader (lilo or loadlin) about how to pass options to the
925 kernel at boot time.)
927 If unsure, say "off".
931 depends on !X86_NUMAQ
933 Select this if you have a 32-bit processor and between 1 and 4
934 gigabytes of physical RAM.
938 depends on !M386 && !M486
941 Select this if you have a 32-bit processor and more than 4
942 gigabytes of physical RAM.
947 depends on EXPERIMENTAL
948 prompt "Memory split" if EMBEDDED
952 Select the desired split between kernel and user memory.
954 If the address range available to the kernel is less than the
955 physical memory installed, the remaining memory will be available
956 as "high memory". Accessing high memory is a little more costly
957 than low memory, as it needs to be mapped into the kernel first.
958 Note that increasing the kernel address space limits the range
959 available to user programs, making the address space there
960 tighter. Selecting anything other than the default 3G/1G split
961 will also likely make your kernel incompatible with binary-only
964 If you are not absolutely sure what you are doing, leave this
968 bool "3G/1G user/kernel split"
969 config VMSPLIT_3G_OPT
971 bool "3G/1G user/kernel split (for full 1G low memory)"
973 bool "2G/2G user/kernel split"
974 config VMSPLIT_2G_OPT
976 bool "2G/2G user/kernel split (for full 2G low memory)"
978 bool "1G/3G user/kernel split"
983 default 0xB0000000 if VMSPLIT_3G_OPT
984 default 0x80000000 if VMSPLIT_2G
985 default 0x78000000 if VMSPLIT_2G_OPT
986 default 0x40000000 if VMSPLIT_1G
992 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
995 bool "PAE (Physical Address Extension) Support"
996 depends on X86_32 && !HIGHMEM4G
998 PAE is required for NX support, and furthermore enables
999 larger swapspace support for non-overcommit purposes. It
1000 has the cost of more pagetable lookup overhead, and also
1001 consumes more pagetable space per process.
1003 config ARCH_PHYS_ADDR_T_64BIT
1004 def_bool X86_64 || X86_PAE
1006 config DIRECT_GBPAGES
1007 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1011 Allow the kernel linear mapping to use 1GB pages on CPUs that
1012 support it. This can improve the kernel's performance a tiny bit by
1013 reducing TLB pressure. If in doubt, say "Y".
1015 # Common NUMA Features
1017 bool "Numa Memory Allocation and Scheduler Support"
1019 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1021 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1023 Enable NUMA (Non Uniform Memory Access) support.
1025 The kernel will try to allocate memory used by a CPU on the
1026 local memory controller of the CPU and add some more
1027 NUMA awareness to the kernel.
1029 For 64-bit this is recommended if the system is Intel Core i7
1030 (or later), AMD Opteron, or EM64T NUMA.
1032 For 32-bit this is only needed on (rare) 32-bit-only platforms
1033 that support NUMA topologies, such as NUMAQ / Summit, or if you
1034 boot a 32-bit kernel on a 64-bit NUMA platform.
1036 Otherwise, you should say N.
1038 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1039 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1043 prompt "Old style AMD Opteron NUMA detection"
1044 depends on X86_64 && NUMA && PCI
1046 Enable K8 NUMA node topology detection. You should say Y here if
1047 you have a multi processor AMD K8 system. This uses an old
1048 method to read the NUMA configuration directly from the builtin
1049 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1050 instead, which also takes priority if both are compiled in.
1052 config X86_64_ACPI_NUMA
1054 prompt "ACPI NUMA detection"
1055 depends on X86_64 && NUMA && ACPI && PCI
1058 Enable ACPI SRAT based node topology detection.
1060 # Some NUMA nodes have memory ranges that span
1061 # other nodes. Even though a pfn is valid and
1062 # between a node's start and end pfns, it may not
1063 # reside on that node. See memmap_init_zone()
1065 config NODES_SPAN_OTHER_NODES
1067 depends on X86_64_ACPI_NUMA
1070 bool "NUMA emulation"
1071 depends on X86_64 && NUMA
1073 Enable NUMA emulation. A flat machine will be split
1074 into virtual nodes when booted with "numa=fake=N", where N is the
1075 number of nodes. This is only useful for debugging.
1078 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1080 default "9" if MAXSMP
1081 default "6" if X86_64
1082 default "4" if X86_NUMAQ
1084 depends on NEED_MULTIPLE_NODES
1086 Specify the maximum number of NUMA Nodes available on the target
1087 system. Increases memory reserved to accomodate various tables.
1089 config HAVE_ARCH_BOOTMEM_NODE
1091 depends on X86_32 && NUMA
1093 config ARCH_HAVE_MEMORY_PRESENT
1095 depends on X86_32 && DISCONTIGMEM
1097 config NEED_NODE_MEMMAP_SIZE
1099 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1101 config HAVE_ARCH_ALLOC_REMAP
1103 depends on X86_32 && NUMA
1105 config ARCH_FLATMEM_ENABLE
1107 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1109 config ARCH_DISCONTIGMEM_ENABLE
1111 depends on NUMA && X86_32
1113 config ARCH_DISCONTIGMEM_DEFAULT
1115 depends on NUMA && X86_32
1117 config ARCH_SPARSEMEM_DEFAULT
1121 config ARCH_SPARSEMEM_ENABLE
1123 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC) || X86_GENERICARCH
1124 select SPARSEMEM_STATIC if X86_32
1125 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1127 config ARCH_SELECT_MEMORY_MODEL
1129 depends on ARCH_SPARSEMEM_ENABLE
1131 config ARCH_MEMORY_PROBE
1133 depends on MEMORY_HOTPLUG
1138 bool "Allocate 3rd-level pagetables from highmem"
1139 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1141 The VM uses one page table entry for each page of physical memory.
1142 For systems with a lot of RAM, this can be wasteful of precious
1143 low memory. Setting this option will put user-space page table
1144 entries in high memory.
1146 config X86_CHECK_BIOS_CORRUPTION
1147 bool "Check for low memory corruption"
1149 Periodically check for memory corruption in low memory, which
1150 is suspected to be caused by BIOS. Even when enabled in the
1151 configuration, it is disabled at runtime. Enable it by
1152 setting "memory_corruption_check=1" on the kernel command
1153 line. By default it scans the low 64k of memory every 60
1154 seconds; see the memory_corruption_check_size and
1155 memory_corruption_check_period parameters in
1156 Documentation/kernel-parameters.txt to adjust this.
1158 When enabled with the default parameters, this option has
1159 almost no overhead, as it reserves a relatively small amount
1160 of memory and scans it infrequently. It both detects corruption
1161 and prevents it from affecting the running system.
1163 It is, however, intended as a diagnostic tool; if repeatable
1164 BIOS-originated corruption always affects the same memory,
1165 you can use memmap= to prevent the kernel from using that
1168 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1169 bool "Set the default setting of memory_corruption_check"
1170 depends on X86_CHECK_BIOS_CORRUPTION
1173 Set whether the default state of memory_corruption_check is
1176 config X86_RESERVE_LOW_64K
1177 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1180 Reserve the first 64K of physical RAM on BIOSes that are known
1181 to potentially corrupt that memory range. A numbers of BIOSes are
1182 known to utilize this area during suspend/resume, so it must not
1183 be used by the kernel.
1185 Set this to N if you are absolutely sure that you trust the BIOS
1186 to get all its memory reservations and usages right.
1188 If you have doubts about the BIOS (e.g. suspend/resume does not
1189 work or there's kernel crashes after certain hardware hotplug
1190 events) and it's not AMI or Phoenix, then you might want to enable
1191 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1192 corruption patterns.
1196 config MATH_EMULATION
1198 prompt "Math emulation" if X86_32
1200 Linux can emulate a math coprocessor (used for floating point
1201 operations) if you don't have one. 486DX and Pentium processors have
1202 a math coprocessor built in, 486SX and 386 do not, unless you added
1203 a 487DX or 387, respectively. (The messages during boot time can
1204 give you some hints here ["man dmesg"].) Everyone needs either a
1205 coprocessor or this emulation.
1207 If you don't have a math coprocessor, you need to say Y here; if you
1208 say Y here even though you have a coprocessor, the coprocessor will
1209 be used nevertheless. (This behavior can be changed with the kernel
1210 command line option "no387", which comes handy if your coprocessor
1211 is broken. Try "man bootparam" or see the documentation of your boot
1212 loader (lilo or loadlin) about how to pass options to the kernel at
1213 boot time.) This means that it is a good idea to say Y here if you
1214 intend to use this kernel on different machines.
1216 More information about the internals of the Linux math coprocessor
1217 emulation can be found in <file:arch/x86/math-emu/README>.
1219 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1220 kernel, it won't hurt.
1223 bool "MTRR (Memory Type Range Register) support"
1225 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1226 the Memory Type Range Registers (MTRRs) may be used to control
1227 processor access to memory ranges. This is most useful if you have
1228 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1229 allows bus write transfers to be combined into a larger transfer
1230 before bursting over the PCI/AGP bus. This can increase performance
1231 of image write operations 2.5 times or more. Saying Y here creates a
1232 /proc/mtrr file which may be used to manipulate your processor's
1233 MTRRs. Typically the X server should use this.
1235 This code has a reasonably generic interface so that similar
1236 control registers on other processors can be easily supported
1239 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1240 Registers (ARRs) which provide a similar functionality to MTRRs. For
1241 these, the ARRs are used to emulate the MTRRs.
1242 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1243 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1244 write-combining. All of these processors are supported by this code
1245 and it makes sense to say Y here if you have one of them.
1247 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1248 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1249 can lead to all sorts of problems, so it's good to say Y here.
1251 You can safely say Y even if your machine doesn't have MTRRs, you'll
1252 just add about 9 KB to your kernel.
1254 See <file:Documentation/x86/mtrr.txt> for more information.
1256 config MTRR_SANITIZER
1258 prompt "MTRR cleanup support"
1261 Convert MTRR layout from continuous to discrete, so X drivers can
1262 add writeback entries.
1264 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1265 The largest mtrr entry size for a continous block can be set with
1270 config MTRR_SANITIZER_ENABLE_DEFAULT
1271 int "MTRR cleanup enable value (0-1)"
1274 depends on MTRR_SANITIZER
1276 Enable mtrr cleanup default value
1278 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1279 int "MTRR cleanup spare reg num (0-7)"
1282 depends on MTRR_SANITIZER
1284 mtrr cleanup spare entries default, it can be changed via
1285 mtrr_spare_reg_nr=N on the kernel command line.
1289 prompt "x86 PAT support"
1292 Use PAT attributes to setup page level cache control.
1294 PATs are the modern equivalents of MTRRs and are much more
1295 flexible than MTRRs.
1297 Say N here if you see bootup problems (boot crash, boot hang,
1298 spontaneous reboots) or a non-working video driver.
1303 bool "EFI runtime service support"
1306 This enables the kernel to use EFI runtime services that are
1307 available (such as the EFI variable services).
1309 This option is only useful on systems that have EFI firmware.
1310 In addition, you should use the latest ELILO loader available
1311 at <http://elilo.sourceforge.net> in order to take advantage
1312 of EFI runtime services. However, even with this option, the
1313 resultant kernel should continue to boot on existing non-EFI
1318 prompt "Enable seccomp to safely compute untrusted bytecode"
1320 This kernel feature is useful for number crunching applications
1321 that may need to compute untrusted bytecode during their
1322 execution. By using pipes or other transports made available to
1323 the process as file descriptors supporting the read/write
1324 syscalls, it's possible to isolate those applications in
1325 their own address space using seccomp. Once seccomp is
1326 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1327 and the task is only allowed to execute a few safe syscalls
1328 defined by each seccomp mode.
1330 If unsure, say Y. Only embedded should say N here.
1332 config CC_STACKPROTECTOR
1333 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1334 depends on X86_64 && EXPERIMENTAL && BROKEN
1336 This option turns on the -fstack-protector GCC feature. This
1337 feature puts, at the beginning of critical functions, a canary
1338 value on the stack just before the return address, and validates
1339 the value just before actually returning. Stack based buffer
1340 overflows (that need to overwrite this return address) now also
1341 overwrite the canary, which gets detected and the attack is then
1342 neutralized via a kernel panic.
1344 This feature requires gcc version 4.2 or above, or a distribution
1345 gcc with the feature backported. Older versions are automatically
1346 detected and for those versions, this configuration option is ignored.
1348 config CC_STACKPROTECTOR_ALL
1349 bool "Use stack-protector for all functions"
1350 depends on CC_STACKPROTECTOR
1352 Normally, GCC only inserts the canary value protection for
1353 functions that use large-ish on-stack buffers. By enabling
1354 this option, GCC will be asked to do this for ALL functions.
1356 source kernel/Kconfig.hz
1359 bool "kexec system call"
1360 depends on X86_BIOS_REBOOT
1362 kexec is a system call that implements the ability to shutdown your
1363 current kernel, and to start another kernel. It is like a reboot
1364 but it is independent of the system firmware. And like a reboot
1365 you can start any kernel with it, not just Linux.
1367 The name comes from the similarity to the exec system call.
1369 It is an ongoing process to be certain the hardware in a machine
1370 is properly shutdown, so do not be surprised if this code does not
1371 initially work for you. It may help to enable device hotplugging
1372 support. As of this writing the exact hardware interface is
1373 strongly in flux, so no good recommendation can be made.
1376 bool "kernel crash dumps"
1377 depends on X86_64 || (X86_32 && HIGHMEM)
1379 Generate crash dump after being started by kexec.
1380 This should be normally only set in special crash dump kernels
1381 which are loaded in the main kernel with kexec-tools into
1382 a specially reserved region and then later executed after
1383 a crash by kdump/kexec. The crash dump kernel must be compiled
1384 to a memory address not used by the main kernel or BIOS using
1385 PHYSICAL_START, or it must be built as a relocatable image
1386 (CONFIG_RELOCATABLE=y).
1387 For more details see Documentation/kdump/kdump.txt
1390 bool "kexec jump (EXPERIMENTAL)"
1391 depends on EXPERIMENTAL
1392 depends on KEXEC && HIBERNATION && X86_32
1394 Jump between original kernel and kexeced kernel and invoke
1395 code in physical address mode via KEXEC
1397 config PHYSICAL_START
1398 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1399 default "0x1000000" if X86_NUMAQ
1400 default "0x200000" if X86_64
1403 This gives the physical address where the kernel is loaded.
1405 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1406 bzImage will decompress itself to above physical address and
1407 run from there. Otherwise, bzImage will run from the address where
1408 it has been loaded by the boot loader and will ignore above physical
1411 In normal kdump cases one does not have to set/change this option
1412 as now bzImage can be compiled as a completely relocatable image
1413 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1414 address. This option is mainly useful for the folks who don't want
1415 to use a bzImage for capturing the crash dump and want to use a
1416 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1417 to be specifically compiled to run from a specific memory area
1418 (normally a reserved region) and this option comes handy.
1420 So if you are using bzImage for capturing the crash dump, leave
1421 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1422 Otherwise if you plan to use vmlinux for capturing the crash dump
1423 change this value to start of the reserved region (Typically 16MB
1424 0x1000000). In other words, it can be set based on the "X" value as
1425 specified in the "crashkernel=YM@XM" command line boot parameter
1426 passed to the panic-ed kernel. Typically this parameter is set as
1427 crashkernel=64M@16M. Please take a look at
1428 Documentation/kdump/kdump.txt for more details about crash dumps.
1430 Usage of bzImage for capturing the crash dump is recommended as
1431 one does not have to build two kernels. Same kernel can be used
1432 as production kernel and capture kernel. Above option should have
1433 gone away after relocatable bzImage support is introduced. But it
1434 is present because there are users out there who continue to use
1435 vmlinux for dump capture. This option should go away down the
1438 Don't change this unless you know what you are doing.
1441 bool "Build a relocatable kernel (EXPERIMENTAL)"
1442 depends on EXPERIMENTAL
1444 This builds a kernel image that retains relocation information
1445 so it can be loaded someplace besides the default 1MB.
1446 The relocations tend to make the kernel binary about 10% larger,
1447 but are discarded at runtime.
1449 One use is for the kexec on panic case where the recovery kernel
1450 must live at a different physical address than the primary
1453 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1454 it has been loaded at and the compile time physical address
1455 (CONFIG_PHYSICAL_START) is ignored.
1457 config PHYSICAL_ALIGN
1459 prompt "Alignment value to which kernel should be aligned" if X86_32
1460 default "0x100000" if X86_32
1461 default "0x200000" if X86_64
1462 range 0x2000 0x400000
1464 This value puts the alignment restrictions on physical address
1465 where kernel is loaded and run from. Kernel is compiled for an
1466 address which meets above alignment restriction.
1468 If bootloader loads the kernel at a non-aligned address and
1469 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1470 address aligned to above value and run from there.
1472 If bootloader loads the kernel at a non-aligned address and
1473 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1474 load address and decompress itself to the address it has been
1475 compiled for and run from there. The address for which kernel is
1476 compiled already meets above alignment restrictions. Hence the
1477 end result is that kernel runs from a physical address meeting
1478 above alignment restrictions.
1480 Don't change this unless you know what you are doing.
1483 bool "Support for hot-pluggable CPUs"
1484 depends on SMP && HOTPLUG && !X86_VOYAGER
1486 Say Y here to allow turning CPUs off and on. CPUs can be
1487 controlled through /sys/devices/system/cpu.
1488 ( Note: power management support will enable this option
1489 automatically on SMP systems. )
1490 Say N if you want to disable CPU hotplug.
1494 prompt "Compat VDSO support"
1495 depends on X86_32 || IA32_EMULATION
1497 Map the 32-bit VDSO to the predictable old-style address too.
1499 Say N here if you are running a sufficiently recent glibc
1500 version (2.3.3 or later), to remove the high-mapped
1501 VDSO mapping and to exclusively use the randomized VDSO.
1506 bool "Built-in kernel command line"
1509 Allow for specifying boot arguments to the kernel at
1510 build time. On some systems (e.g. embedded ones), it is
1511 necessary or convenient to provide some or all of the
1512 kernel boot arguments with the kernel itself (that is,
1513 to not rely on the boot loader to provide them.)
1515 To compile command line arguments into the kernel,
1516 set this option to 'Y', then fill in the
1517 the boot arguments in CONFIG_CMDLINE.
1519 Systems with fully functional boot loaders (i.e. non-embedded)
1520 should leave this option set to 'N'.
1523 string "Built-in kernel command string"
1524 depends on CMDLINE_BOOL
1527 Enter arguments here that should be compiled into the kernel
1528 image and used at boot time. If the boot loader provides a
1529 command line at boot time, it is appended to this string to
1530 form the full kernel command line, when the system boots.
1532 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1533 change this behavior.
1535 In most cases, the command line (whether built-in or provided
1536 by the boot loader) should specify the device for the root
1539 config CMDLINE_OVERRIDE
1540 bool "Built-in command line overrides boot loader arguments"
1542 depends on CMDLINE_BOOL
1544 Set this option to 'Y' to have the kernel ignore the boot loader
1545 command line, and use ONLY the built-in command line.
1547 This is used to work around broken boot loaders. This should
1548 be set to 'N' under normal conditions.
1552 config ARCH_ENABLE_MEMORY_HOTPLUG
1554 depends on X86_64 || (X86_32 && HIGHMEM)
1556 config ARCH_ENABLE_MEMORY_HOTREMOVE
1558 depends on MEMORY_HOTPLUG
1560 config HAVE_ARCH_EARLY_PFN_TO_NID
1564 menu "Power management and ACPI options"
1565 depends on !X86_VOYAGER
1567 config ARCH_HIBERNATION_HEADER
1569 depends on X86_64 && HIBERNATION
1571 source "kernel/power/Kconfig"
1573 source "drivers/acpi/Kconfig"
1578 depends on APM || APM_MODULE
1581 tristate "APM (Advanced Power Management) BIOS support"
1582 depends on X86_32 && PM_SLEEP
1584 APM is a BIOS specification for saving power using several different
1585 techniques. This is mostly useful for battery powered laptops with
1586 APM compliant BIOSes. If you say Y here, the system time will be
1587 reset after a RESUME operation, the /proc/apm device will provide
1588 battery status information, and user-space programs will receive
1589 notification of APM "events" (e.g. battery status change).
1591 If you select "Y" here, you can disable actual use of the APM
1592 BIOS by passing the "apm=off" option to the kernel at boot time.
1594 Note that the APM support is almost completely disabled for
1595 machines with more than one CPU.
1597 In order to use APM, you will need supporting software. For location
1598 and more information, read <file:Documentation/power/pm.txt> and the
1599 Battery Powered Linux mini-HOWTO, available from
1600 <http://www.tldp.org/docs.html#howto>.
1602 This driver does not spin down disk drives (see the hdparm(8)
1603 manpage ("man 8 hdparm") for that), and it doesn't turn off
1604 VESA-compliant "green" monitors.
1606 This driver does not support the TI 4000M TravelMate and the ACER
1607 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1608 desktop machines also don't have compliant BIOSes, and this driver
1609 may cause those machines to panic during the boot phase.
1611 Generally, if you don't have a battery in your machine, there isn't
1612 much point in using this driver and you should say N. If you get
1613 random kernel OOPSes or reboots that don't seem to be related to
1614 anything, try disabling/enabling this option (or disabling/enabling
1617 Some other things you should try when experiencing seemingly random,
1620 1) make sure that you have enough swap space and that it is
1622 2) pass the "no-hlt" option to the kernel
1623 3) switch on floating point emulation in the kernel and pass
1624 the "no387" option to the kernel
1625 4) pass the "floppy=nodma" option to the kernel
1626 5) pass the "mem=4M" option to the kernel (thereby disabling
1627 all but the first 4 MB of RAM)
1628 6) make sure that the CPU is not over clocked.
1629 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1630 8) disable the cache from your BIOS settings
1631 9) install a fan for the video card or exchange video RAM
1632 10) install a better fan for the CPU
1633 11) exchange RAM chips
1634 12) exchange the motherboard.
1636 To compile this driver as a module, choose M here: the
1637 module will be called apm.
1641 config APM_IGNORE_USER_SUSPEND
1642 bool "Ignore USER SUSPEND"
1644 This option will ignore USER SUSPEND requests. On machines with a
1645 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1646 series notebooks, it is necessary to say Y because of a BIOS bug.
1648 config APM_DO_ENABLE
1649 bool "Enable PM at boot time"
1651 Enable APM features at boot time. From page 36 of the APM BIOS
1652 specification: "When disabled, the APM BIOS does not automatically
1653 power manage devices, enter the Standby State, enter the Suspend
1654 State, or take power saving steps in response to CPU Idle calls."
1655 This driver will make CPU Idle calls when Linux is idle (unless this
1656 feature is turned off -- see "Do CPU IDLE calls", below). This
1657 should always save battery power, but more complicated APM features
1658 will be dependent on your BIOS implementation. You may need to turn
1659 this option off if your computer hangs at boot time when using APM
1660 support, or if it beeps continuously instead of suspending. Turn
1661 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1662 T400CDT. This is off by default since most machines do fine without
1666 bool "Make CPU Idle calls when idle"
1668 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1669 On some machines, this can activate improved power savings, such as
1670 a slowed CPU clock rate, when the machine is idle. These idle calls
1671 are made after the idle loop has run for some length of time (e.g.,
1672 333 mS). On some machines, this will cause a hang at boot time or
1673 whenever the CPU becomes idle. (On machines with more than one CPU,
1674 this option does nothing.)
1676 config APM_DISPLAY_BLANK
1677 bool "Enable console blanking using APM"
1679 Enable console blanking using the APM. Some laptops can use this to
1680 turn off the LCD backlight when the screen blanker of the Linux
1681 virtual console blanks the screen. Note that this is only used by
1682 the virtual console screen blanker, and won't turn off the backlight
1683 when using the X Window system. This also doesn't have anything to
1684 do with your VESA-compliant power-saving monitor. Further, this
1685 option doesn't work for all laptops -- it might not turn off your
1686 backlight at all, or it might print a lot of errors to the console,
1687 especially if you are using gpm.
1689 config APM_ALLOW_INTS
1690 bool "Allow interrupts during APM BIOS calls"
1692 Normally we disable external interrupts while we are making calls to
1693 the APM BIOS as a measure to lessen the effects of a badly behaving
1694 BIOS implementation. The BIOS should reenable interrupts if it
1695 needs to. Unfortunately, some BIOSes do not -- especially those in
1696 many of the newer IBM Thinkpads. If you experience hangs when you
1697 suspend, try setting this to Y. Otherwise, say N.
1701 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1703 source "drivers/cpuidle/Kconfig"
1705 source "drivers/idle/Kconfig"
1710 menu "Bus options (PCI etc.)"
1715 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1717 Find out whether you have a PCI motherboard. PCI is the name of a
1718 bus system, i.e. the way the CPU talks to the other stuff inside
1719 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1720 VESA. If you have PCI, say Y, otherwise N.
1723 prompt "PCI access mode"
1724 depends on X86_32 && PCI
1727 On PCI systems, the BIOS can be used to detect the PCI devices and
1728 determine their configuration. However, some old PCI motherboards
1729 have BIOS bugs and may crash if this is done. Also, some embedded
1730 PCI-based systems don't have any BIOS at all. Linux can also try to
1731 detect the PCI hardware directly without using the BIOS.
1733 With this option, you can specify how Linux should detect the
1734 PCI devices. If you choose "BIOS", the BIOS will be used,
1735 if you choose "Direct", the BIOS won't be used, and if you
1736 choose "MMConfig", then PCI Express MMCONFIG will be used.
1737 If you choose "Any", the kernel will try MMCONFIG, then the
1738 direct access method and falls back to the BIOS if that doesn't
1739 work. If unsure, go with the default, which is "Any".
1744 config PCI_GOMMCONFIG
1761 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1763 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1766 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1770 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1774 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1781 bool "Support mmconfig PCI config space access"
1782 depends on X86_64 && PCI && ACPI
1785 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1786 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1788 DMA remapping (DMAR) devices support enables independent address
1789 translations for Direct Memory Access (DMA) from devices.
1790 These DMA remapping devices are reported via ACPI tables
1791 and include PCI device scope covered by these DMA
1796 prompt "Support for Graphics workaround"
1799 Current Graphics drivers tend to use physical address
1800 for DMA and avoid using DMA APIs. Setting this config
1801 option permits the IOMMU driver to set a unity map for
1802 all the OS-visible memory. Hence the driver can continue
1803 to use physical addresses for DMA.
1805 config DMAR_FLOPPY_WA
1809 Floppy disk drivers are know to bypass DMA API calls
1810 thereby failing to work when IOMMU is enabled. This
1811 workaround will setup a 1:1 mapping for the first
1812 16M to make floppy (an ISA device) work.
1815 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1816 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1818 Supports Interrupt remapping for IO-APIC and MSI devices.
1819 To use x2apic mode in the CPU's which support x2APIC enhancements or
1820 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1822 source "drivers/pci/pcie/Kconfig"
1824 source "drivers/pci/Kconfig"
1826 # x86_64 have no ISA slots, but do have ISA-style DMA.
1834 depends on !X86_VOYAGER
1836 Find out whether you have ISA slots on your motherboard. ISA is the
1837 name of a bus system, i.e. the way the CPU talks to the other stuff
1838 inside your box. Other bus systems are PCI, EISA, MicroChannel
1839 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1840 newer boards don't support it. If you have ISA, say Y, otherwise N.
1846 The Extended Industry Standard Architecture (EISA) bus was
1847 developed as an open alternative to the IBM MicroChannel bus.
1849 The EISA bus provided some of the features of the IBM MicroChannel
1850 bus while maintaining backward compatibility with cards made for
1851 the older ISA bus. The EISA bus saw limited use between 1988 and
1852 1995 when it was made obsolete by the PCI bus.
1854 Say Y here if you are building a kernel for an EISA-based machine.
1858 source "drivers/eisa/Kconfig"
1861 bool "MCA support" if !X86_VOYAGER
1862 default y if X86_VOYAGER
1864 MicroChannel Architecture is found in some IBM PS/2 machines and
1865 laptops. It is a bus system similar to PCI or ISA. See
1866 <file:Documentation/mca.txt> (and especially the web page given
1867 there) before attempting to build an MCA bus kernel.
1869 source "drivers/mca/Kconfig"
1872 tristate "NatSemi SCx200 support"
1873 depends on !X86_VOYAGER
1875 This provides basic support for National Semiconductor's
1876 (now AMD's) Geode processors. The driver probes for the
1877 PCI-IDs of several on-chip devices, so its a good dependency
1878 for other scx200_* drivers.
1880 If compiled as a module, the driver is named scx200.
1882 config SCx200HR_TIMER
1883 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1884 depends on SCx200 && GENERIC_TIME
1887 This driver provides a clocksource built upon the on-chip
1888 27MHz high-resolution timer. Its also a workaround for
1889 NSC Geode SC-1100's buggy TSC, which loses time when the
1890 processor goes idle (as is done by the scheduler). The
1891 other workaround is idle=poll boot option.
1893 config GEODE_MFGPT_TIMER
1895 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1896 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1898 This driver provides a clock event source based on the MFGPT
1899 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1900 MFGPTs have a better resolution and max interval than the
1901 generic PIT, and are suitable for use as high-res timers.
1904 bool "One Laptop Per Child support"
1907 Add support for detecting the unique features of the OLPC
1914 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1916 source "drivers/pcmcia/Kconfig"
1918 source "drivers/pci/hotplug/Kconfig"
1923 menu "Executable file formats / Emulations"
1925 source "fs/Kconfig.binfmt"
1927 config IA32_EMULATION
1928 bool "IA32 Emulation"
1930 select COMPAT_BINFMT_ELF
1932 Include code to run 32-bit programs under a 64-bit kernel. You should
1933 likely turn this on, unless you're 100% sure that you don't have any
1934 32-bit programs left.
1937 tristate "IA32 a.out support"
1938 depends on IA32_EMULATION
1940 Support old a.out binaries in the 32bit emulation.
1944 depends on IA32_EMULATION
1946 config COMPAT_FOR_U64_ALIGNMENT
1950 config SYSVIPC_COMPAT
1952 depends on COMPAT && SYSVIPC
1957 config HAVE_ATOMIC_IOMAP
1961 source "net/Kconfig"
1963 source "drivers/Kconfig"
1965 source "drivers/firmware/Kconfig"
1969 source "arch/x86/Kconfig.debug"
1971 source "security/Kconfig"
1973 source "crypto/Kconfig"
1975 source "arch/x86/kvm/Kconfig"
1977 source "lib/Kconfig"
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