2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
21 select HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
27 select HAVE_IOREMAP_PROT
29 select ARCH_WANT_OPTIONAL_GPIOLIB
30 select ARCH_WANT_FRAME_POINTERS
31 select HAVE_KRETPROBES
32 select HAVE_FTRACE_MCOUNT_RECORD
33 select HAVE_DYNAMIC_FTRACE
34 select HAVE_FUNCTION_TRACER
35 select HAVE_FUNCTION_GRAPH_TRACER
36 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
39 select HAVE_ARCH_TRACEHOOK
40 select HAVE_GENERIC_DMA_COHERENT if X86_32
41 select HAVE_EFFICIENT_UNALIGNED_ACCESS
42 select USER_STACKTRACE_SUPPORT
46 default "arch/x86/configs/i386_defconfig" if X86_32
47 default "arch/x86/configs/x86_64_defconfig" if X86_64
52 config GENERIC_CMOS_UPDATE
55 config CLOCKSOURCE_WATCHDOG
58 config GENERIC_CLOCKEVENTS
61 config GENERIC_CLOCKEVENTS_BROADCAST
63 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
65 config LOCKDEP_SUPPORT
68 config STACKTRACE_SUPPORT
71 config HAVE_LATENCYTOP_SUPPORT
74 config FAST_CMPXCHG_LOCAL
87 config GENERIC_ISA_DMA
96 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
98 config GENERIC_BUG_RELATIVE_POINTERS
101 config GENERIC_HWEIGHT
107 config ARCH_MAY_HAVE_PC_FDC
110 config RWSEM_GENERIC_SPINLOCK
113 config RWSEM_XCHGADD_ALGORITHM
116 config ARCH_HAS_CPU_IDLE_WAIT
119 config GENERIC_CALIBRATE_DELAY
122 config GENERIC_TIME_VSYSCALL
126 config ARCH_HAS_CPU_RELAX
129 config ARCH_HAS_DEFAULT_IDLE
132 config ARCH_HAS_CACHE_LINE_SIZE
135 config HAVE_SETUP_PER_CPU_AREA
138 config HAVE_CPUMASK_OF_CPU_MAP
141 config ARCH_HIBERNATION_POSSIBLE
144 config ARCH_SUSPEND_POSSIBLE
151 config ARCH_POPULATES_NODE_MAP
158 config ARCH_SUPPORTS_OPTIMIZED_INLINING
161 # Use the generic interrupt handling code in kernel/irq/:
162 config GENERIC_HARDIRQS
166 config GENERIC_IRQ_PROBE
170 config GENERIC_PENDING_IRQ
172 depends on GENERIC_HARDIRQS && SMP
175 config USE_GENERIC_SMP_HELPERS
181 depends on X86_32 && SMP
185 depends on X86_64 && SMP
192 config X86_TRAMPOLINE
194 depends on SMP || (64BIT && ACPI_SLEEP)
199 source "init/Kconfig"
200 source "kernel/Kconfig.freezer"
202 menu "Processor type and features"
204 source "kernel/time/Kconfig"
207 bool "Symmetric multi-processing support"
209 This enables support for systems with more than one CPU. If you have
210 a system with only one CPU, like most personal computers, say N. If
211 you have a system with more than one CPU, say Y.
213 If you say N here, the kernel will run on single and multiprocessor
214 machines, but will use only one CPU of a multiprocessor machine. If
215 you say Y here, the kernel will run on many, but not all,
216 singleprocessor machines. On a singleprocessor machine, the kernel
217 will run faster if you say N here.
219 Note that if you say Y here and choose architecture "586" or
220 "Pentium" under "Processor family", the kernel will not work on 486
221 architectures. Similarly, multiprocessor kernels for the "PPro"
222 architecture may not work on all Pentium based boards.
224 People using multiprocessor machines who say Y here should also say
225 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
226 Management" code will be disabled if you say Y here.
228 See also <file:Documentation/i386/IO-APIC.txt>,
229 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
230 <http://www.tldp.org/docs.html#howto>.
232 If you don't know what to do here, say N.
235 bool "Support sparse irq numbering"
236 depends on PCI_MSI || HT_IRQ
238 This enables support for sparse irqs. This is useful for distro
239 kernels that want to define a high CONFIG_NR_CPUS value but still
240 want to have low kernel memory footprint on smaller machines.
242 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
243 out the irq_desc[] array in a more NUMA-friendly way. )
245 If you don't know what to do here, say N.
247 config NUMA_MIGRATE_IRQ_DESC
248 bool "Move irq desc when changing irq smp_affinity"
249 depends on SPARSE_IRQ && NUMA
252 This enables moving irq_desc to cpu/node that irq will use handled.
254 If you don't know what to do here, say N.
257 bool "Enable MPS table" if ACPI
259 depends on X86_LOCAL_APIC
261 For old smp systems that do not have proper acpi support. Newer systems
262 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
265 bool "Support for big SMP systems with more than 8 CPUs"
266 depends on X86_32 && SMP
268 This option is needed for the systems that have more than 8 CPUs
270 config X86_EXTENDED_PLATFORM
271 bool "Support for extended (non-PC) x86 platforms"
274 If you disable this option then the kernel will only support
275 standard PC platforms. (which covers the vast majority of
278 If you enable this option then you'll be able to select a number
279 of non-PC x86 platforms.
281 If you have one of these systems, or if you want to build a
282 generic distribution kernel, say Y here - otherwise say N.
284 # This is an alphabetically sorted list of 64 bit extended platforms
285 # Please maintain the alphabetic order if and when there are additions
290 depends on X86_64 && PCI
291 depends on X86_EXTENDED_PLATFORM
293 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
294 supposed to run on these EM64T-based machines. Only choose this option
295 if you have one of these machines.
298 bool "SGI Ultraviolet"
300 depends on X86_EXTENDED_PLATFORM
302 This option is needed in order to support SGI Ultraviolet systems.
303 If you don't have one of these, you should say N here.
305 # Following is an alphabetically sorted list of 32 bit extended platforms
306 # Please maintain the alphabetic order if and when there are additions
311 depends on X86_EXTENDED_PLATFORM
313 Select this for an AMD Elan processor.
315 Do not use this option for K6/Athlon/Opteron processors!
317 If unsure, choose "PC-compatible" instead.
320 bool "RDC R-321x SoC"
322 depends on X86_EXTENDED_PLATFORM
324 select X86_REBOOTFIXUPS
326 This option is needed for RDC R-321x system-on-chip, also known
328 If you don't have one of these chips, you should say N here.
330 config X86_32_NON_STANDARD
331 bool "Support non-standard 32-bit SMP architectures"
332 depends on X86_32 && SMP
333 depends on X86_EXTENDED_PLATFORM
335 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
336 subarchitectures. It is intended for a generic binary kernel.
337 if you select them all, kernel will probe it one by one. and will
340 # Alphabetically sorted list of Non standard 32 bit platforms
343 bool "NUMAQ (IBM/Sequent)"
344 depends on X86_32_NON_STANDARD
348 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
349 NUMA multiquad box. This changes the way that processors are
350 bootstrapped, and uses Clustered Logical APIC addressing mode instead
351 of Flat Logical. You will need a new lynxer.elf file to flash your
352 firmware with - send email to <Martin.Bligh@us.ibm.com>.
355 bool "SGI 320/540 (Visual Workstation)"
356 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
357 depends on X86_32_NON_STANDARD
359 The SGI Visual Workstation series is an IA32-based workstation
360 based on SGI systems chips with some legacy PC hardware attached.
362 Say Y here to create a kernel to run on the SGI 320 or 540.
364 A kernel compiled for the Visual Workstation will run on general
365 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
368 bool "Summit/EXA (IBM x440)"
369 depends on X86_32_NON_STANDARD
371 This option is needed for IBM systems that use the Summit/EXA chipset.
372 In particular, it is needed for the x440.
375 bool "Unisys ES7000 IA32 series"
376 depends on X86_32_NON_STANDARD && X86_BIGSMP
378 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
379 supposed to run on an IA32-based Unisys ES7000 system.
383 depends on SMP && !PCI && BROKEN
384 depends on X86_32_NON_STANDARD
386 Voyager is an MCA-based 32-way capable SMP architecture proprietary
387 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
391 If you do not specifically know you have a Voyager based machine,
392 say N here, otherwise the kernel you build will not be bootable.
394 config SCHED_OMIT_FRAME_POINTER
396 prompt "Single-depth WCHAN output"
399 Calculate simpler /proc/<PID>/wchan values. If this option
400 is disabled then wchan values will recurse back to the
401 caller function. This provides more accurate wchan values,
402 at the expense of slightly more scheduling overhead.
404 If in doubt, say "Y".
406 menuconfig PARAVIRT_GUEST
407 bool "Paravirtualized guest support"
409 Say Y here to get to see options related to running Linux under
410 various hypervisors. This option alone does not add any kernel code.
412 If you say N, all options in this submenu will be skipped and disabled.
416 source "arch/x86/xen/Kconfig"
419 bool "VMI Guest support"
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
433 Turning on this option will allow you to run a paravirtualized clock
434 when running over the KVM hypervisor. Instead of relying on a PIT
435 (or probably other) emulation by the underlying device model, the host
436 provides the guest with timing infrastructure such as time of day, and
440 bool "KVM Guest support"
443 This option enables various optimizations for running under the KVM
446 source "arch/x86/lguest/Kconfig"
449 bool "Enable paravirtualization code"
451 This changes the kernel so it can modify itself when it is run
452 under a hypervisor, potentially improving performance significantly
453 over full virtualization. However, when run without a hypervisor
454 the kernel is theoretically slower and slightly larger.
456 config PARAVIRT_CLOCK
462 config PARAVIRT_DEBUG
463 bool "paravirt-ops debugging"
464 depends on PARAVIRT && DEBUG_KERNEL
466 Enable to debug paravirt_ops internals. Specifically, BUG if
467 a paravirt_op is missing when it is called.
472 This option adds a kernel parameter 'memtest', which allows memtest
474 memtest=0, mean disabled; -- default
475 memtest=1, mean do 1 test pattern;
477 memtest=4, mean do 4 test patterns.
478 If you are unsure how to answer this question, answer N.
480 config X86_SUMMIT_NUMA
482 depends on X86_32 && NUMA && X86_32_NON_STANDARD
484 config X86_CYCLONE_TIMER
486 depends on X86_32_NON_STANDARD
488 source "arch/x86/Kconfig.cpu"
492 prompt "HPET Timer Support" if X86_32
494 Use the IA-PC HPET (High Precision Event Timer) to manage
495 time in preference to the PIT and RTC, if a HPET is
497 HPET is the next generation timer replacing legacy 8254s.
498 The HPET provides a stable time base on SMP
499 systems, unlike the TSC, but it is more expensive to access,
500 as it is off-chip. You can find the HPET spec at
501 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
503 You can safely choose Y here. However, HPET will only be
504 activated if the platform and the BIOS support this feature.
505 Otherwise the 8254 will be used for timing services.
507 Choose N to continue using the legacy 8254 timer.
509 config HPET_EMULATE_RTC
511 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
513 # Mark as embedded because too many people got it wrong.
514 # The code disables itself when not needed.
517 bool "Enable DMI scanning" if EMBEDDED
519 Enabled scanning of DMI to identify machine quirks. Say Y
520 here unless you have verified that your setup is not
521 affected by entries in the DMI blacklist. Required by PNP
525 bool "GART IOMMU support" if EMBEDDED
529 depends on X86_64 && PCI
531 Support for full DMA access of devices with 32bit memory access only
532 on systems with more than 3GB. This is usually needed for USB,
533 sound, many IDE/SATA chipsets and some other devices.
534 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
535 based hardware IOMMU and a software bounce buffer based IOMMU used
536 on Intel systems and as fallback.
537 The code is only active when needed (enough memory and limited
538 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
542 bool "IBM Calgary IOMMU support"
544 depends on X86_64 && PCI && EXPERIMENTAL
546 Support for hardware IOMMUs in IBM's xSeries x366 and x460
547 systems. Needed to run systems with more than 3GB of memory
548 properly with 32-bit PCI devices that do not support DAC
549 (Double Address Cycle). Calgary also supports bus level
550 isolation, where all DMAs pass through the IOMMU. This
551 prevents them from going anywhere except their intended
552 destination. This catches hard-to-find kernel bugs and
553 mis-behaving drivers and devices that do not use the DMA-API
554 properly to set up their DMA buffers. The IOMMU can be
555 turned off at boot time with the iommu=off parameter.
556 Normally the kernel will make the right choice by itself.
559 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
561 prompt "Should Calgary be enabled by default?"
562 depends on CALGARY_IOMMU
564 Should Calgary be enabled by default? if you choose 'y', Calgary
565 will be used (if it exists). If you choose 'n', Calgary will not be
566 used even if it exists. If you choose 'n' and would like to use
567 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
571 bool "AMD IOMMU support"
574 depends on X86_64 && PCI && ACPI
576 With this option you can enable support for AMD IOMMU hardware in
577 your system. An IOMMU is a hardware component which provides
578 remapping of DMA memory accesses from devices. With an AMD IOMMU you
579 can isolate the the DMA memory of different devices and protect the
580 system from misbehaving device drivers or hardware.
582 You can find out if your system has an AMD IOMMU if you look into
583 your BIOS for an option to enable it or if you have an IVRS ACPI
586 config AMD_IOMMU_STATS
587 bool "Export AMD IOMMU statistics to debugfs"
591 This option enables code in the AMD IOMMU driver to collect various
592 statistics about whats happening in the driver and exports that
593 information to userspace via debugfs.
596 # need this always selected by IOMMU for the VIA workaround
600 Support for software bounce buffers used on x86-64 systems
601 which don't have a hardware IOMMU (e.g. the current generation
602 of Intel's x86-64 CPUs). Using this PCI devices which can only
603 access 32-bits of memory can be used on systems with more than
604 3 GB of memory. If unsure, say Y.
607 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
610 def_bool (AMD_IOMMU || DMAR)
613 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
614 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
615 select CPUMASK_OFFSTACK
618 Configure maximum number of CPUS and NUMA Nodes for this architecture.
622 int "Maximum number of CPUs" if SMP && !MAXSMP
623 range 2 512 if SMP && !MAXSMP
625 default "4096" if MAXSMP
626 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
629 This allows you to specify the maximum number of CPUs which this
630 kernel will support. The maximum supported value is 512 and the
631 minimum value which makes sense is 2.
633 This is purely to save memory - each supported CPU adds
634 approximately eight kilobytes to the kernel image.
637 bool "SMT (Hyperthreading) scheduler support"
640 SMT scheduler support improves the CPU scheduler's decision making
641 when dealing with Intel Pentium 4 chips with HyperThreading at a
642 cost of slightly increased overhead in some places. If unsure say
647 prompt "Multi-core scheduler support"
650 Multi-core scheduler support improves the CPU scheduler's decision
651 making when dealing with multi-core CPU chips at a cost of slightly
652 increased overhead in some places. If unsure say N here.
654 source "kernel/Kconfig.preempt"
657 bool "Local APIC support on uniprocessors"
658 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
660 A local APIC (Advanced Programmable Interrupt Controller) is an
661 integrated interrupt controller in the CPU. If you have a single-CPU
662 system which has a processor with a local APIC, you can say Y here to
663 enable and use it. If you say Y here even though your machine doesn't
664 have a local APIC, then the kernel will still run with no slowdown at
665 all. The local APIC supports CPU-generated self-interrupts (timer,
666 performance counters), and the NMI watchdog which detects hard
670 bool "IO-APIC support on uniprocessors"
671 depends on X86_UP_APIC
673 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
674 SMP-capable replacement for PC-style interrupt controllers. Most
675 SMP systems and many recent uniprocessor systems have one.
677 If you have a single-CPU system with an IO-APIC, you can say Y here
678 to use it. If you say Y here even though your machine doesn't have
679 an IO-APIC, then the kernel will still run with no slowdown at all.
681 config X86_LOCAL_APIC
683 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
687 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
689 config X86_VISWS_APIC
691 depends on X86_32 && X86_VISWS
693 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
694 bool "Reroute for broken boot IRQs"
696 depends on X86_IO_APIC
698 This option enables a workaround that fixes a source of
699 spurious interrupts. This is recommended when threaded
700 interrupt handling is used on systems where the generation of
701 superfluous "boot interrupts" cannot be disabled.
703 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
704 entry in the chipset's IO-APIC is masked (as, e.g. the RT
705 kernel does during interrupt handling). On chipsets where this
706 boot IRQ generation cannot be disabled, this workaround keeps
707 the original IRQ line masked so that only the equivalent "boot
708 IRQ" is delivered to the CPUs. The workaround also tells the
709 kernel to set up the IRQ handler on the boot IRQ line. In this
710 way only one interrupt is delivered to the kernel. Otherwise
711 the spurious second interrupt may cause the kernel to bring
712 down (vital) interrupt lines.
714 Only affects "broken" chipsets. Interrupt sharing may be
715 increased on these systems.
718 bool "Machine Check Exception"
720 Machine Check Exception support allows the processor to notify the
721 kernel if it detects a problem (e.g. overheating, component failure).
722 The action the kernel takes depends on the severity of the problem,
723 ranging from a warning message on the console, to halting the machine.
724 Your processor must be a Pentium or newer to support this - check the
725 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
726 have a design flaw which leads to false MCE events - hence MCE is
727 disabled on all P5 processors, unless explicitly enabled with "mce"
728 as a boot argument. Similarly, if MCE is built in and creates a
729 problem on some new non-standard machine, you can boot with "nomce"
730 to disable it. MCE support simply ignores non-MCE processors like
731 the 386 and 486, so nearly everyone can say Y here.
735 prompt "Intel MCE features"
736 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
738 Additional support for intel specific MCE features such as
743 prompt "AMD MCE features"
744 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
746 Additional support for AMD specific MCE features such as
747 the DRAM Error Threshold.
749 config X86_MCE_NONFATAL
750 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
751 depends on X86_32 && X86_MCE
753 Enabling this feature starts a timer that triggers every 5 seconds which
754 will look at the machine check registers to see if anything happened.
755 Non-fatal problems automatically get corrected (but still logged).
756 Disable this if you don't want to see these messages.
757 Seeing the messages this option prints out may be indicative of dying
758 or out-of-spec (ie, overclocked) hardware.
759 This option only does something on certain CPUs.
760 (AMD Athlon/Duron and Intel Pentium 4)
762 config X86_MCE_P4THERMAL
763 bool "check for P4 thermal throttling interrupt."
764 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
766 Enabling this feature will cause a message to be printed when the P4
767 enters thermal throttling.
770 bool "Enable VM86 support" if EMBEDDED
774 This option is required by programs like DOSEMU to run 16-bit legacy
775 code on X86 processors. It also may be needed by software like
776 XFree86 to initialize some video cards via BIOS. Disabling this
777 option saves about 6k.
780 tristate "Toshiba Laptop support"
783 This adds a driver to safely access the System Management Mode of
784 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
785 not work on models with a Phoenix BIOS. The System Management Mode
786 is used to set the BIOS and power saving options on Toshiba portables.
788 For information on utilities to make use of this driver see the
789 Toshiba Linux utilities web site at:
790 <http://www.buzzard.org.uk/toshiba/>.
792 Say Y if you intend to run this kernel on a Toshiba portable.
796 tristate "Dell laptop support"
798 This adds a driver to safely access the System Management Mode
799 of the CPU on the Dell Inspiron 8000. The System Management Mode
800 is used to read cpu temperature and cooling fan status and to
801 control the fans on the I8K portables.
803 This driver has been tested only on the Inspiron 8000 but it may
804 also work with other Dell laptops. You can force loading on other
805 models by passing the parameter `force=1' to the module. Use at
808 For information on utilities to make use of this driver see the
809 I8K Linux utilities web site at:
810 <http://people.debian.org/~dz/i8k/>
812 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
815 config X86_REBOOTFIXUPS
816 bool "Enable X86 board specific fixups for reboot"
819 This enables chipset and/or board specific fixups to be done
820 in order to get reboot to work correctly. This is only needed on
821 some combinations of hardware and BIOS. The symptom, for which
822 this config is intended, is when reboot ends with a stalled/hung
825 Currently, the only fixup is for the Geode machines using
826 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
828 Say Y if you want to enable the fixup. Currently, it's safe to
829 enable this option even if you don't need it.
833 tristate "/dev/cpu/microcode - microcode support"
836 If you say Y here, you will be able to update the microcode on
837 certain Intel and AMD processors. The Intel support is for the
838 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
839 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
840 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
841 You will obviously need the actual microcode binary data itself
842 which is not shipped with the Linux kernel.
844 This option selects the general module only, you need to select
845 at least one vendor specific module as well.
847 To compile this driver as a module, choose M here: the
848 module will be called microcode.
850 config MICROCODE_INTEL
851 bool "Intel microcode patch loading support"
856 This options enables microcode patch loading support for Intel
859 For latest news and information on obtaining all the required
860 Intel ingredients for this driver, check:
861 <http://www.urbanmyth.org/microcode/>.
864 bool "AMD microcode patch loading support"
868 If you select this option, microcode patch loading support for AMD
869 processors will be enabled.
871 config MICROCODE_OLD_INTERFACE
876 tristate "/dev/cpu/*/msr - Model-specific register support"
878 This device gives privileged processes access to the x86
879 Model-Specific Registers (MSRs). It is a character device with
880 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
881 MSR accesses are directed to a specific CPU on multi-processor
885 tristate "/dev/cpu/*/cpuid - CPU information support"
887 This device gives processes access to the x86 CPUID instruction to
888 be executed on a specific processor. It is a character device
889 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
893 prompt "High Memory Support"
894 default HIGHMEM4G if !X86_NUMAQ
895 default HIGHMEM64G if X86_NUMAQ
900 depends on !X86_NUMAQ
902 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
903 However, the address space of 32-bit x86 processors is only 4
904 Gigabytes large. That means that, if you have a large amount of
905 physical memory, not all of it can be "permanently mapped" by the
906 kernel. The physical memory that's not permanently mapped is called
909 If you are compiling a kernel which will never run on a machine with
910 more than 1 Gigabyte total physical RAM, answer "off" here (default
911 choice and suitable for most users). This will result in a "3GB/1GB"
912 split: 3GB are mapped so that each process sees a 3GB virtual memory
913 space and the remaining part of the 4GB virtual memory space is used
914 by the kernel to permanently map as much physical memory as
917 If the machine has between 1 and 4 Gigabytes physical RAM, then
920 If more than 4 Gigabytes is used then answer "64GB" here. This
921 selection turns Intel PAE (Physical Address Extension) mode on.
922 PAE implements 3-level paging on IA32 processors. PAE is fully
923 supported by Linux, PAE mode is implemented on all recent Intel
924 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
925 then the kernel will not boot on CPUs that don't support PAE!
927 The actual amount of total physical memory will either be
928 auto detected or can be forced by using a kernel command line option
929 such as "mem=256M". (Try "man bootparam" or see the documentation of
930 your boot loader (lilo or loadlin) about how to pass options to the
931 kernel at boot time.)
933 If unsure, say "off".
937 depends on !X86_NUMAQ
939 Select this if you have a 32-bit processor and between 1 and 4
940 gigabytes of physical RAM.
944 depends on !M386 && !M486
947 Select this if you have a 32-bit processor and more than 4
948 gigabytes of physical RAM.
953 depends on EXPERIMENTAL
954 prompt "Memory split" if EMBEDDED
958 Select the desired split between kernel and user memory.
960 If the address range available to the kernel is less than the
961 physical memory installed, the remaining memory will be available
962 as "high memory". Accessing high memory is a little more costly
963 than low memory, as it needs to be mapped into the kernel first.
964 Note that increasing the kernel address space limits the range
965 available to user programs, making the address space there
966 tighter. Selecting anything other than the default 3G/1G split
967 will also likely make your kernel incompatible with binary-only
970 If you are not absolutely sure what you are doing, leave this
974 bool "3G/1G user/kernel split"
975 config VMSPLIT_3G_OPT
977 bool "3G/1G user/kernel split (for full 1G low memory)"
979 bool "2G/2G user/kernel split"
980 config VMSPLIT_2G_OPT
982 bool "2G/2G user/kernel split (for full 2G low memory)"
984 bool "1G/3G user/kernel split"
989 default 0xB0000000 if VMSPLIT_3G_OPT
990 default 0x80000000 if VMSPLIT_2G
991 default 0x78000000 if VMSPLIT_2G_OPT
992 default 0x40000000 if VMSPLIT_1G
998 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1001 bool "PAE (Physical Address Extension) Support"
1002 depends on X86_32 && !HIGHMEM4G
1004 PAE is required for NX support, and furthermore enables
1005 larger swapspace support for non-overcommit purposes. It
1006 has the cost of more pagetable lookup overhead, and also
1007 consumes more pagetable space per process.
1009 config ARCH_PHYS_ADDR_T_64BIT
1010 def_bool X86_64 || X86_PAE
1012 config DIRECT_GBPAGES
1013 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1017 Allow the kernel linear mapping to use 1GB pages on CPUs that
1018 support it. This can improve the kernel's performance a tiny bit by
1019 reducing TLB pressure. If in doubt, say "Y".
1021 # Common NUMA Features
1023 bool "Numa Memory Allocation and Scheduler Support"
1025 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1026 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1028 Enable NUMA (Non Uniform Memory Access) support.
1030 The kernel will try to allocate memory used by a CPU on the
1031 local memory controller of the CPU and add some more
1032 NUMA awareness to the kernel.
1034 For 64-bit this is recommended if the system is Intel Core i7
1035 (or later), AMD Opteron, or EM64T NUMA.
1037 For 32-bit this is only needed on (rare) 32-bit-only platforms
1038 that support NUMA topologies, such as NUMAQ / Summit, or if you
1039 boot a 32-bit kernel on a 64-bit NUMA platform.
1041 Otherwise, you should say N.
1043 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1044 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1048 prompt "Old style AMD Opteron NUMA detection"
1049 depends on X86_64 && NUMA && PCI
1051 Enable K8 NUMA node topology detection. You should say Y here if
1052 you have a multi processor AMD K8 system. This uses an old
1053 method to read the NUMA configuration directly from the builtin
1054 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1055 instead, which also takes priority if both are compiled in.
1057 config X86_64_ACPI_NUMA
1059 prompt "ACPI NUMA detection"
1060 depends on X86_64 && NUMA && ACPI && PCI
1063 Enable ACPI SRAT based node topology detection.
1065 # Some NUMA nodes have memory ranges that span
1066 # other nodes. Even though a pfn is valid and
1067 # between a node's start and end pfns, it may not
1068 # reside on that node. See memmap_init_zone()
1070 config NODES_SPAN_OTHER_NODES
1072 depends on X86_64_ACPI_NUMA
1075 bool "NUMA emulation"
1076 depends on X86_64 && NUMA
1078 Enable NUMA emulation. A flat machine will be split
1079 into virtual nodes when booted with "numa=fake=N", where N is the
1080 number of nodes. This is only useful for debugging.
1083 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1085 default "9" if MAXSMP
1086 default "6" if X86_64
1087 default "4" if X86_NUMAQ
1089 depends on NEED_MULTIPLE_NODES
1091 Specify the maximum number of NUMA Nodes available on the target
1092 system. Increases memory reserved to accomodate various tables.
1094 config HAVE_ARCH_BOOTMEM_NODE
1096 depends on X86_32 && NUMA
1098 config ARCH_HAVE_MEMORY_PRESENT
1100 depends on X86_32 && DISCONTIGMEM
1102 config NEED_NODE_MEMMAP_SIZE
1104 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1106 config HAVE_ARCH_ALLOC_REMAP
1108 depends on X86_32 && NUMA
1110 config ARCH_FLATMEM_ENABLE
1112 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1114 config ARCH_DISCONTIGMEM_ENABLE
1116 depends on NUMA && X86_32
1118 config ARCH_DISCONTIGMEM_DEFAULT
1120 depends on NUMA && X86_32
1122 config ARCH_SPARSEMEM_DEFAULT
1126 config ARCH_SPARSEMEM_ENABLE
1128 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1129 select SPARSEMEM_STATIC if X86_32
1130 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1132 config ARCH_SELECT_MEMORY_MODEL
1134 depends on ARCH_SPARSEMEM_ENABLE
1136 config ARCH_MEMORY_PROBE
1138 depends on MEMORY_HOTPLUG
1143 bool "Allocate 3rd-level pagetables from highmem"
1144 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1146 The VM uses one page table entry for each page of physical memory.
1147 For systems with a lot of RAM, this can be wasteful of precious
1148 low memory. Setting this option will put user-space page table
1149 entries in high memory.
1151 config X86_CHECK_BIOS_CORRUPTION
1152 bool "Check for low memory corruption"
1154 Periodically check for memory corruption in low memory, which
1155 is suspected to be caused by BIOS. Even when enabled in the
1156 configuration, it is disabled at runtime. Enable it by
1157 setting "memory_corruption_check=1" on the kernel command
1158 line. By default it scans the low 64k of memory every 60
1159 seconds; see the memory_corruption_check_size and
1160 memory_corruption_check_period parameters in
1161 Documentation/kernel-parameters.txt to adjust this.
1163 When enabled with the default parameters, this option has
1164 almost no overhead, as it reserves a relatively small amount
1165 of memory and scans it infrequently. It both detects corruption
1166 and prevents it from affecting the running system.
1168 It is, however, intended as a diagnostic tool; if repeatable
1169 BIOS-originated corruption always affects the same memory,
1170 you can use memmap= to prevent the kernel from using that
1173 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1174 bool "Set the default setting of memory_corruption_check"
1175 depends on X86_CHECK_BIOS_CORRUPTION
1178 Set whether the default state of memory_corruption_check is
1181 config X86_RESERVE_LOW_64K
1182 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1185 Reserve the first 64K of physical RAM on BIOSes that are known
1186 to potentially corrupt that memory range. A numbers of BIOSes are
1187 known to utilize this area during suspend/resume, so it must not
1188 be used by the kernel.
1190 Set this to N if you are absolutely sure that you trust the BIOS
1191 to get all its memory reservations and usages right.
1193 If you have doubts about the BIOS (e.g. suspend/resume does not
1194 work or there's kernel crashes after certain hardware hotplug
1195 events) and it's not AMI or Phoenix, then you might want to enable
1196 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1197 corruption patterns.
1201 config MATH_EMULATION
1203 prompt "Math emulation" if X86_32
1205 Linux can emulate a math coprocessor (used for floating point
1206 operations) if you don't have one. 486DX and Pentium processors have
1207 a math coprocessor built in, 486SX and 386 do not, unless you added
1208 a 487DX or 387, respectively. (The messages during boot time can
1209 give you some hints here ["man dmesg"].) Everyone needs either a
1210 coprocessor or this emulation.
1212 If you don't have a math coprocessor, you need to say Y here; if you
1213 say Y here even though you have a coprocessor, the coprocessor will
1214 be used nevertheless. (This behavior can be changed with the kernel
1215 command line option "no387", which comes handy if your coprocessor
1216 is broken. Try "man bootparam" or see the documentation of your boot
1217 loader (lilo or loadlin) about how to pass options to the kernel at
1218 boot time.) This means that it is a good idea to say Y here if you
1219 intend to use this kernel on different machines.
1221 More information about the internals of the Linux math coprocessor
1222 emulation can be found in <file:arch/x86/math-emu/README>.
1224 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1225 kernel, it won't hurt.
1228 bool "MTRR (Memory Type Range Register) support"
1230 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1231 the Memory Type Range Registers (MTRRs) may be used to control
1232 processor access to memory ranges. This is most useful if you have
1233 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1234 allows bus write transfers to be combined into a larger transfer
1235 before bursting over the PCI/AGP bus. This can increase performance
1236 of image write operations 2.5 times or more. Saying Y here creates a
1237 /proc/mtrr file which may be used to manipulate your processor's
1238 MTRRs. Typically the X server should use this.
1240 This code has a reasonably generic interface so that similar
1241 control registers on other processors can be easily supported
1244 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1245 Registers (ARRs) which provide a similar functionality to MTRRs. For
1246 these, the ARRs are used to emulate the MTRRs.
1247 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1248 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1249 write-combining. All of these processors are supported by this code
1250 and it makes sense to say Y here if you have one of them.
1252 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1253 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1254 can lead to all sorts of problems, so it's good to say Y here.
1256 You can safely say Y even if your machine doesn't have MTRRs, you'll
1257 just add about 9 KB to your kernel.
1259 See <file:Documentation/x86/mtrr.txt> for more information.
1261 config MTRR_SANITIZER
1263 prompt "MTRR cleanup support"
1266 Convert MTRR layout from continuous to discrete, so X drivers can
1267 add writeback entries.
1269 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1270 The largest mtrr entry size for a continous block can be set with
1275 config MTRR_SANITIZER_ENABLE_DEFAULT
1276 int "MTRR cleanup enable value (0-1)"
1279 depends on MTRR_SANITIZER
1281 Enable mtrr cleanup default value
1283 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1284 int "MTRR cleanup spare reg num (0-7)"
1287 depends on MTRR_SANITIZER
1289 mtrr cleanup spare entries default, it can be changed via
1290 mtrr_spare_reg_nr=N on the kernel command line.
1294 prompt "x86 PAT support"
1297 Use PAT attributes to setup page level cache control.
1299 PATs are the modern equivalents of MTRRs and are much more
1300 flexible than MTRRs.
1302 Say N here if you see bootup problems (boot crash, boot hang,
1303 spontaneous reboots) or a non-working video driver.
1308 bool "EFI runtime service support"
1311 This enables the kernel to use EFI runtime services that are
1312 available (such as the EFI variable services).
1314 This option is only useful on systems that have EFI firmware.
1315 In addition, you should use the latest ELILO loader available
1316 at <http://elilo.sourceforge.net> in order to take advantage
1317 of EFI runtime services. However, even with this option, the
1318 resultant kernel should continue to boot on existing non-EFI
1323 prompt "Enable seccomp to safely compute untrusted bytecode"
1325 This kernel feature is useful for number crunching applications
1326 that may need to compute untrusted bytecode during their
1327 execution. By using pipes or other transports made available to
1328 the process as file descriptors supporting the read/write
1329 syscalls, it's possible to isolate those applications in
1330 their own address space using seccomp. Once seccomp is
1331 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1332 and the task is only allowed to execute a few safe syscalls
1333 defined by each seccomp mode.
1335 If unsure, say Y. Only embedded should say N here.
1337 config CC_STACKPROTECTOR_ALL
1340 config CC_STACKPROTECTOR
1341 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1343 select CC_STACKPROTECTOR_ALL
1345 This option turns on the -fstack-protector GCC feature. This
1346 feature puts, at the beginning of functions, a canary value on
1347 the stack just before the return address, and validates
1348 the value just before actually returning. Stack based buffer
1349 overflows (that need to overwrite this return address) now also
1350 overwrite the canary, which gets detected and the attack is then
1351 neutralized via a kernel panic.
1353 This feature requires gcc version 4.2 or above, or a distribution
1354 gcc with the feature backported. Older versions are automatically
1355 detected and for those versions, this configuration option is
1356 ignored. (and a warning is printed during bootup)
1358 source kernel/Kconfig.hz
1361 bool "kexec system call"
1363 kexec is a system call that implements the ability to shutdown your
1364 current kernel, and to start another kernel. It is like a reboot
1365 but it is independent of the system firmware. And like a reboot
1366 you can start any kernel with it, not just Linux.
1368 The name comes from the similarity to the exec system call.
1370 It is an ongoing process to be certain the hardware in a machine
1371 is properly shutdown, so do not be surprised if this code does not
1372 initially work for you. It may help to enable device hotplugging
1373 support. As of this writing the exact hardware interface is
1374 strongly in flux, so no good recommendation can be made.
1377 bool "kernel crash dumps"
1378 depends on X86_64 || (X86_32 && HIGHMEM)
1380 Generate crash dump after being started by kexec.
1381 This should be normally only set in special crash dump kernels
1382 which are loaded in the main kernel with kexec-tools into
1383 a specially reserved region and then later executed after
1384 a crash by kdump/kexec. The crash dump kernel must be compiled
1385 to a memory address not used by the main kernel or BIOS using
1386 PHYSICAL_START, or it must be built as a relocatable image
1387 (CONFIG_RELOCATABLE=y).
1388 For more details see Documentation/kdump/kdump.txt
1391 bool "kexec jump (EXPERIMENTAL)"
1392 depends on EXPERIMENTAL
1393 depends on KEXEC && HIBERNATION && X86_32
1395 Jump between original kernel and kexeced kernel and invoke
1396 code in physical address mode via KEXEC
1398 config PHYSICAL_START
1399 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1400 default "0x1000000" if X86_NUMAQ
1401 default "0x200000" if X86_64
1404 This gives the physical address where the kernel is loaded.
1406 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1407 bzImage will decompress itself to above physical address and
1408 run from there. Otherwise, bzImage will run from the address where
1409 it has been loaded by the boot loader and will ignore above physical
1412 In normal kdump cases one does not have to set/change this option
1413 as now bzImage can be compiled as a completely relocatable image
1414 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1415 address. This option is mainly useful for the folks who don't want
1416 to use a bzImage for capturing the crash dump and want to use a
1417 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1418 to be specifically compiled to run from a specific memory area
1419 (normally a reserved region) and this option comes handy.
1421 So if you are using bzImage for capturing the crash dump, leave
1422 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1423 Otherwise if you plan to use vmlinux for capturing the crash dump
1424 change this value to start of the reserved region (Typically 16MB
1425 0x1000000). In other words, it can be set based on the "X" value as
1426 specified in the "crashkernel=YM@XM" command line boot parameter
1427 passed to the panic-ed kernel. Typically this parameter is set as
1428 crashkernel=64M@16M. Please take a look at
1429 Documentation/kdump/kdump.txt for more details about crash dumps.
1431 Usage of bzImage for capturing the crash dump is recommended as
1432 one does not have to build two kernels. Same kernel can be used
1433 as production kernel and capture kernel. Above option should have
1434 gone away after relocatable bzImage support is introduced. But it
1435 is present because there are users out there who continue to use
1436 vmlinux for dump capture. This option should go away down the
1439 Don't change this unless you know what you are doing.
1442 bool "Build a relocatable kernel (EXPERIMENTAL)"
1443 depends on EXPERIMENTAL
1445 This builds a kernel image that retains relocation information
1446 so it can be loaded someplace besides the default 1MB.
1447 The relocations tend to make the kernel binary about 10% larger,
1448 but are discarded at runtime.
1450 One use is for the kexec on panic case where the recovery kernel
1451 must live at a different physical address than the primary
1454 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1455 it has been loaded at and the compile time physical address
1456 (CONFIG_PHYSICAL_START) is ignored.
1458 config PHYSICAL_ALIGN
1460 prompt "Alignment value to which kernel should be aligned" if X86_32
1461 default "0x100000" if X86_32
1462 default "0x200000" if X86_64
1463 range 0x2000 0x400000
1465 This value puts the alignment restrictions on physical address
1466 where kernel is loaded and run from. Kernel is compiled for an
1467 address which meets above alignment restriction.
1469 If bootloader loads the kernel at a non-aligned address and
1470 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1471 address aligned to above value and run from there.
1473 If bootloader loads the kernel at a non-aligned address and
1474 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1475 load address and decompress itself to the address it has been
1476 compiled for and run from there. The address for which kernel is
1477 compiled already meets above alignment restrictions. Hence the
1478 end result is that kernel runs from a physical address meeting
1479 above alignment restrictions.
1481 Don't change this unless you know what you are doing.
1484 bool "Support for hot-pluggable CPUs"
1485 depends on SMP && HOTPLUG
1487 Say Y here to allow turning CPUs off and on. CPUs can be
1488 controlled through /sys/devices/system/cpu.
1489 ( Note: power management support will enable this option
1490 automatically on SMP systems. )
1491 Say N if you want to disable CPU hotplug.
1495 prompt "Compat VDSO support"
1496 depends on X86_32 || IA32_EMULATION
1498 Map the 32-bit VDSO to the predictable old-style address too.
1500 Say N here if you are running a sufficiently recent glibc
1501 version (2.3.3 or later), to remove the high-mapped
1502 VDSO mapping and to exclusively use the randomized VDSO.
1507 bool "Built-in kernel command line"
1510 Allow for specifying boot arguments to the kernel at
1511 build time. On some systems (e.g. embedded ones), it is
1512 necessary or convenient to provide some or all of the
1513 kernel boot arguments with the kernel itself (that is,
1514 to not rely on the boot loader to provide them.)
1516 To compile command line arguments into the kernel,
1517 set this option to 'Y', then fill in the
1518 the boot arguments in CONFIG_CMDLINE.
1520 Systems with fully functional boot loaders (i.e. non-embedded)
1521 should leave this option set to 'N'.
1524 string "Built-in kernel command string"
1525 depends on CMDLINE_BOOL
1528 Enter arguments here that should be compiled into the kernel
1529 image and used at boot time. If the boot loader provides a
1530 command line at boot time, it is appended to this string to
1531 form the full kernel command line, when the system boots.
1533 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1534 change this behavior.
1536 In most cases, the command line (whether built-in or provided
1537 by the boot loader) should specify the device for the root
1540 config CMDLINE_OVERRIDE
1541 bool "Built-in command line overrides boot loader arguments"
1543 depends on CMDLINE_BOOL
1545 Set this option to 'Y' to have the kernel ignore the boot loader
1546 command line, and use ONLY the built-in command line.
1548 This is used to work around broken boot loaders. This should
1549 be set to 'N' under normal conditions.
1553 config ARCH_ENABLE_MEMORY_HOTPLUG
1555 depends on X86_64 || (X86_32 && HIGHMEM)
1557 config ARCH_ENABLE_MEMORY_HOTREMOVE
1559 depends on MEMORY_HOTPLUG
1561 config HAVE_ARCH_EARLY_PFN_TO_NID
1565 menu "Power management and ACPI options"
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
1794 config DMAR_DEFAULT_ON
1796 prompt "Enable DMA Remapping Devices by default"
1799 Selecting this option will enable a DMAR device at boot time if
1800 one is found. If this option is not selected, DMAR support can
1801 be enabled by passing intel_iommu=on to the kernel. It is
1802 recommended you say N here while the DMAR code remains
1807 prompt "Support for Graphics workaround"
1810 Current Graphics drivers tend to use physical address
1811 for DMA and avoid using DMA APIs. Setting this config
1812 option permits the IOMMU driver to set a unity map for
1813 all the OS-visible memory. Hence the driver can continue
1814 to use physical addresses for DMA.
1816 config DMAR_FLOPPY_WA
1820 Floppy disk drivers are know to bypass DMA API calls
1821 thereby failing to work when IOMMU is enabled. This
1822 workaround will setup a 1:1 mapping for the first
1823 16M to make floppy (an ISA device) work.
1826 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1827 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1829 Supports Interrupt remapping for IO-APIC and MSI devices.
1830 To use x2apic mode in the CPU's which support x2APIC enhancements or
1831 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1833 source "drivers/pci/pcie/Kconfig"
1835 source "drivers/pci/Kconfig"
1837 # x86_64 have no ISA slots, but do have ISA-style DMA.
1846 Find out whether you have ISA slots on your motherboard. ISA is the
1847 name of a bus system, i.e. the way the CPU talks to the other stuff
1848 inside your box. Other bus systems are PCI, EISA, MicroChannel
1849 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1850 newer boards don't support it. If you have ISA, say Y, otherwise N.
1856 The Extended Industry Standard Architecture (EISA) bus was
1857 developed as an open alternative to the IBM MicroChannel bus.
1859 The EISA bus provided some of the features of the IBM MicroChannel
1860 bus while maintaining backward compatibility with cards made for
1861 the older ISA bus. The EISA bus saw limited use between 1988 and
1862 1995 when it was made obsolete by the PCI bus.
1864 Say Y here if you are building a kernel for an EISA-based machine.
1868 source "drivers/eisa/Kconfig"
1873 MicroChannel Architecture is found in some IBM PS/2 machines and
1874 laptops. It is a bus system similar to PCI or ISA. See
1875 <file:Documentation/mca.txt> (and especially the web page given
1876 there) before attempting to build an MCA bus kernel.
1878 source "drivers/mca/Kconfig"
1881 tristate "NatSemi SCx200 support"
1883 This provides basic support for National Semiconductor's
1884 (now AMD's) Geode processors. The driver probes for the
1885 PCI-IDs of several on-chip devices, so its a good dependency
1886 for other scx200_* drivers.
1888 If compiled as a module, the driver is named scx200.
1890 config SCx200HR_TIMER
1891 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1892 depends on SCx200 && GENERIC_TIME
1895 This driver provides a clocksource built upon the on-chip
1896 27MHz high-resolution timer. Its also a workaround for
1897 NSC Geode SC-1100's buggy TSC, which loses time when the
1898 processor goes idle (as is done by the scheduler). The
1899 other workaround is idle=poll boot option.
1901 config GEODE_MFGPT_TIMER
1903 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1904 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1906 This driver provides a clock event source based on the MFGPT
1907 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1908 MFGPTs have a better resolution and max interval than the
1909 generic PIT, and are suitable for use as high-res timers.
1912 bool "One Laptop Per Child support"
1915 Add support for detecting the unique features of the OLPC
1922 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1924 source "drivers/pcmcia/Kconfig"
1926 source "drivers/pci/hotplug/Kconfig"
1931 menu "Executable file formats / Emulations"
1933 source "fs/Kconfig.binfmt"
1935 config IA32_EMULATION
1936 bool "IA32 Emulation"
1938 select COMPAT_BINFMT_ELF
1940 Include code to run 32-bit programs under a 64-bit kernel. You should
1941 likely turn this on, unless you're 100% sure that you don't have any
1942 32-bit programs left.
1945 tristate "IA32 a.out support"
1946 depends on IA32_EMULATION
1948 Support old a.out binaries in the 32bit emulation.
1952 depends on IA32_EMULATION
1954 config COMPAT_FOR_U64_ALIGNMENT
1958 config SYSVIPC_COMPAT
1960 depends on COMPAT && SYSVIPC
1965 config HAVE_ATOMIC_IOMAP
1969 source "net/Kconfig"
1971 source "drivers/Kconfig"
1973 source "drivers/firmware/Kconfig"
1977 source "arch/x86/Kconfig.debug"
1979 source "security/Kconfig"
1981 source "crypto/Kconfig"
1983 source "arch/x86/kvm/Kconfig"
1985 source "lib/Kconfig"
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