2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
21 select HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
27 select HAVE_IOREMAP_PROT
29 select ARCH_WANT_OPTIONAL_GPIOLIB
30 select ARCH_WANT_FRAME_POINTERS
31 select HAVE_KRETPROBES
32 select HAVE_FTRACE_MCOUNT_RECORD
33 select HAVE_DYNAMIC_FTRACE
34 select HAVE_FUNCTION_TRACER
35 select HAVE_FUNCTION_GRAPH_TRACER
36 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
39 select HAVE_ARCH_TRACEHOOK
40 select HAVE_GENERIC_DMA_COHERENT if X86_32
41 select HAVE_EFFICIENT_UNALIGNED_ACCESS
42 select USER_STACKTRACE_SUPPORT
46 default "arch/x86/configs/i386_defconfig" if X86_32
47 default "arch/x86/configs/x86_64_defconfig" if X86_64
52 config GENERIC_CMOS_UPDATE
55 config CLOCKSOURCE_WATCHDOG
58 config GENERIC_CLOCKEVENTS
61 config GENERIC_CLOCKEVENTS_BROADCAST
63 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
65 config LOCKDEP_SUPPORT
68 config STACKTRACE_SUPPORT
71 config HAVE_LATENCYTOP_SUPPORT
74 config FAST_CMPXCHG_LOCAL
87 config GENERIC_ISA_DMA
96 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
98 config GENERIC_BUG_RELATIVE_POINTERS
101 config GENERIC_HWEIGHT
107 config ARCH_MAY_HAVE_PC_FDC
110 config RWSEM_GENERIC_SPINLOCK
113 config RWSEM_XCHGADD_ALGORITHM
116 config ARCH_HAS_CPU_IDLE_WAIT
119 config GENERIC_CALIBRATE_DELAY
122 config GENERIC_TIME_VSYSCALL
126 config ARCH_HAS_CPU_RELAX
129 config ARCH_HAS_DEFAULT_IDLE
132 config ARCH_HAS_CACHE_LINE_SIZE
135 config HAVE_SETUP_PER_CPU_AREA
138 config HAVE_CPUMASK_OF_CPU_MAP
141 config ARCH_HIBERNATION_POSSIBLE
145 config ARCH_SUSPEND_POSSIBLE
152 config ARCH_POPULATES_NODE_MAP
159 config ARCH_SUPPORTS_OPTIMIZED_INLINING
162 # Use the generic interrupt handling code in kernel/irq/:
163 config GENERIC_HARDIRQS
167 config GENERIC_IRQ_PROBE
171 config GENERIC_PENDING_IRQ
173 depends on GENERIC_HARDIRQS && SMP
176 config USE_GENERIC_SMP_HELPERS
182 depends on X86_32 && SMP
186 depends on X86_64 && SMP
193 config X86_TRAMPOLINE
195 depends on SMP || (64BIT && ACPI_SLEEP)
200 source "init/Kconfig"
201 source "kernel/Kconfig.freezer"
203 menu "Processor type and features"
205 source "kernel/time/Kconfig"
208 bool "Symmetric multi-processing support"
210 This enables support for systems with more than one CPU. If you have
211 a system with only one CPU, like most personal computers, say N. If
212 you have a system with more than one CPU, say Y.
214 If you say N here, the kernel will run on single and multiprocessor
215 machines, but will use only one CPU of a multiprocessor machine. If
216 you say Y here, the kernel will run on many, but not all,
217 singleprocessor machines. On a singleprocessor machine, the kernel
218 will run faster if you say N here.
220 Note that if you say Y here and choose architecture "586" or
221 "Pentium" under "Processor family", the kernel will not work on 486
222 architectures. Similarly, multiprocessor kernels for the "PPro"
223 architecture may not work on all Pentium based boards.
225 People using multiprocessor machines who say Y here should also say
226 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
227 Management" code will be disabled if you say Y here.
229 See also <file:Documentation/i386/IO-APIC.txt>,
230 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
231 <http://www.tldp.org/docs.html#howto>.
233 If you don't know what to do here, say N.
236 bool "Support sparse irq numbering"
237 depends on PCI_MSI || HT_IRQ
239 This enables support for sparse irqs. This is useful for distro
240 kernels that want to define a high CONFIG_NR_CPUS value but still
241 want to have low kernel memory footprint on smaller machines.
243 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
244 out the irq_desc[] array in a more NUMA-friendly way. )
246 If you don't know what to do here, say N.
248 config NUMA_MIGRATE_IRQ_DESC
249 bool "Move irq desc when changing irq smp_affinity"
250 depends on SPARSE_IRQ && NUMA
253 This enables moving irq_desc to cpu/node that irq will use handled.
255 If you don't know what to do here, say N.
258 bool "Enable MPS table" if ACPI
260 depends on X86_LOCAL_APIC
262 For old smp systems that do not have proper acpi support. Newer systems
263 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
266 prompt "Subarchitecture Type"
272 Choose this option if your computer is a standard PC or compatible.
278 Select this for an AMD Elan processor.
280 Do not use this option for K6/Athlon/Opteron processors!
282 If unsure, choose "PC-compatible" instead.
286 depends on X86_32 && SMP && !PCI && BROKEN
288 Voyager is an MCA-based 32-way capable SMP architecture proprietary
289 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
293 If you do not specifically know you have a Voyager based machine,
294 say N here, otherwise the kernel you build will not be bootable.
296 config X86_GENERICARCH
297 bool "Generic architecture"
300 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
301 subarchitectures. It is intended for a generic binary kernel.
302 if you select them all, kernel will probe it one by one. and will
308 bool "NUMAQ (IBM/Sequent)"
309 depends on SMP && X86_32 && PCI && X86_MPPARSE
312 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
313 NUMA multiquad box. This changes the way that processors are
314 bootstrapped, and uses Clustered Logical APIC addressing mode instead
315 of Flat Logical. You will need a new lynxer.elf file to flash your
316 firmware with - send email to <Martin.Bligh@us.ibm.com>.
319 bool "Summit/EXA (IBM x440)"
320 depends on X86_32 && SMP
322 This option is needed for IBM systems that use the Summit/EXA chipset.
323 In particular, it is needed for the x440.
326 bool "Support for Unisys ES7000 IA32 series"
327 depends on X86_32 && SMP
329 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
330 supposed to run on an IA32-based Unisys ES7000 system.
333 bool "Support for big SMP systems with more than 8 CPUs"
334 depends on X86_32 && SMP
336 This option is needed for the systems that have more than 8 CPUs
337 and if the system is not of any sub-arch type above.
342 bool "Support for ScaleMP vSMP"
344 depends on X86_64 && PCI
346 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
347 supposed to run on these EM64T-based machines. Only choose this option
348 if you have one of these machines.
353 bool "SGI 320/540 (Visual Workstation)"
354 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
356 The SGI Visual Workstation series is an IA32-based workstation
357 based on SGI systems chips with some legacy PC hardware attached.
359 Say Y here to create a kernel to run on the SGI 320 or 540.
361 A kernel compiled for the Visual Workstation will run on general
362 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
365 bool "RDC R-321x SoC"
368 select X86_REBOOTFIXUPS
370 This option is needed for RDC R-321x system-on-chip, also known
372 If you don't have one of these chips, you should say N here.
375 bool "SGI Ultraviolet"
378 This option is needed in order to support SGI Ultraviolet systems.
379 If you don't have one of these, you should say N here.
381 config SCHED_OMIT_FRAME_POINTER
383 prompt "Single-depth WCHAN output"
386 Calculate simpler /proc/<PID>/wchan values. If this option
387 is disabled then wchan values will recurse back to the
388 caller function. This provides more accurate wchan values,
389 at the expense of slightly more scheduling overhead.
391 If in doubt, say "Y".
393 menuconfig PARAVIRT_GUEST
394 bool "Paravirtualized guest support"
396 Say Y here to get to see options related to running Linux under
397 various hypervisors. This option alone does not add any kernel code.
399 If you say N, all options in this submenu will be skipped and disabled.
403 source "arch/x86/xen/Kconfig"
406 bool "VMI Guest support"
410 VMI provides a paravirtualized interface to the VMware ESX server
411 (it could be used by other hypervisors in theory too, but is not
412 at the moment), by linking the kernel to a GPL-ed ROM module
413 provided by the hypervisor.
416 bool "KVM paravirtualized clock"
418 select PARAVIRT_CLOCK
420 Turning on this option will allow you to run a paravirtualized clock
421 when running over the KVM hypervisor. Instead of relying on a PIT
422 (or probably other) emulation by the underlying device model, the host
423 provides the guest with timing infrastructure such as time of day, and
427 bool "KVM Guest support"
430 This option enables various optimizations for running under the KVM
433 source "arch/x86/lguest/Kconfig"
436 bool "Enable paravirtualization code"
437 depends on !X86_VOYAGER
439 This changes the kernel so it can modify itself when it is run
440 under a hypervisor, potentially improving performance significantly
441 over full virtualization. However, when run without a hypervisor
442 the kernel is theoretically slower and slightly larger.
444 config PARAVIRT_CLOCK
450 config PARAVIRT_DEBUG
451 bool "paravirt-ops debugging"
452 depends on PARAVIRT && DEBUG_KERNEL
454 Enable to debug paravirt_ops internals. Specifically, BUG if
455 a paravirt_op is missing when it is called.
460 This option adds a kernel parameter 'memtest', which allows memtest
462 memtest=0, mean disabled; -- default
463 memtest=1, mean do 1 test pattern;
465 memtest=4, mean do 4 test patterns.
466 If you are unsure how to answer this question, answer N.
468 config X86_SUMMIT_NUMA
470 depends on X86_32 && NUMA && X86_GENERICARCH
472 config X86_CYCLONE_TIMER
474 depends on X86_GENERICARCH
476 source "arch/x86/Kconfig.cpu"
480 prompt "HPET Timer Support" if X86_32
482 Use the IA-PC HPET (High Precision Event Timer) to manage
483 time in preference to the PIT and RTC, if a HPET is
485 HPET is the next generation timer replacing legacy 8254s.
486 The HPET provides a stable time base on SMP
487 systems, unlike the TSC, but it is more expensive to access,
488 as it is off-chip. You can find the HPET spec at
489 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
491 You can safely choose Y here. However, HPET will only be
492 activated if the platform and the BIOS support this feature.
493 Otherwise the 8254 will be used for timing services.
495 Choose N to continue using the legacy 8254 timer.
497 config HPET_EMULATE_RTC
499 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
501 # Mark as embedded because too many people got it wrong.
502 # The code disables itself when not needed.
505 bool "Enable DMI scanning" if EMBEDDED
507 Enabled scanning of DMI to identify machine quirks. Say Y
508 here unless you have verified that your setup is not
509 affected by entries in the DMI blacklist. Required by PNP
513 bool "GART IOMMU support" if EMBEDDED
517 depends on X86_64 && PCI
519 Support for full DMA access of devices with 32bit memory access only
520 on systems with more than 3GB. This is usually needed for USB,
521 sound, many IDE/SATA chipsets and some other devices.
522 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
523 based hardware IOMMU and a software bounce buffer based IOMMU used
524 on Intel systems and as fallback.
525 The code is only active when needed (enough memory and limited
526 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
530 bool "IBM Calgary IOMMU support"
532 depends on X86_64 && PCI && EXPERIMENTAL
534 Support for hardware IOMMUs in IBM's xSeries x366 and x460
535 systems. Needed to run systems with more than 3GB of memory
536 properly with 32-bit PCI devices that do not support DAC
537 (Double Address Cycle). Calgary also supports bus level
538 isolation, where all DMAs pass through the IOMMU. This
539 prevents them from going anywhere except their intended
540 destination. This catches hard-to-find kernel bugs and
541 mis-behaving drivers and devices that do not use the DMA-API
542 properly to set up their DMA buffers. The IOMMU can be
543 turned off at boot time with the iommu=off parameter.
544 Normally the kernel will make the right choice by itself.
547 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
549 prompt "Should Calgary be enabled by default?"
550 depends on CALGARY_IOMMU
552 Should Calgary be enabled by default? if you choose 'y', Calgary
553 will be used (if it exists). If you choose 'n', Calgary will not be
554 used even if it exists. If you choose 'n' and would like to use
555 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
559 bool "AMD IOMMU support"
562 depends on X86_64 && PCI && ACPI
564 With this option you can enable support for AMD IOMMU hardware in
565 your system. An IOMMU is a hardware component which provides
566 remapping of DMA memory accesses from devices. With an AMD IOMMU you
567 can isolate the the DMA memory of different devices and protect the
568 system from misbehaving device drivers or hardware.
570 You can find out if your system has an AMD IOMMU if you look into
571 your BIOS for an option to enable it or if you have an IVRS ACPI
574 config AMD_IOMMU_STATS
575 bool "Export AMD IOMMU statistics to debugfs"
579 This option enables code in the AMD IOMMU driver to collect various
580 statistics about whats happening in the driver and exports that
581 information to userspace via debugfs.
584 # need this always selected by IOMMU for the VIA workaround
588 Support for software bounce buffers used on x86-64 systems
589 which don't have a hardware IOMMU (e.g. the current generation
590 of Intel's x86-64 CPUs). Using this PCI devices which can only
591 access 32-bits of memory can be used on systems with more than
592 3 GB of memory. If unsure, say Y.
595 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
598 def_bool (AMD_IOMMU || DMAR)
601 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
602 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
603 select CPUMASK_OFFSTACK
606 Configure maximum number of CPUS and NUMA Nodes for this architecture.
610 int "Maximum number of CPUs" if SMP && !MAXSMP
611 range 2 512 if SMP && !MAXSMP
613 default "4096" if MAXSMP
614 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
617 This allows you to specify the maximum number of CPUs which this
618 kernel will support. The maximum supported value is 512 and the
619 minimum value which makes sense is 2.
621 This is purely to save memory - each supported CPU adds
622 approximately eight kilobytes to the kernel image.
625 bool "SMT (Hyperthreading) scheduler support"
628 SMT scheduler support improves the CPU scheduler's decision making
629 when dealing with Intel Pentium 4 chips with HyperThreading at a
630 cost of slightly increased overhead in some places. If unsure say
635 prompt "Multi-core scheduler support"
638 Multi-core scheduler support improves the CPU scheduler's decision
639 making when dealing with multi-core CPU chips at a cost of slightly
640 increased overhead in some places. If unsure say N here.
642 source "kernel/Kconfig.preempt"
645 bool "Local APIC support on uniprocessors"
646 depends on X86_32 && !SMP && !(X86_VOYAGER || X86_GENERICARCH)
648 A local APIC (Advanced Programmable Interrupt Controller) is an
649 integrated interrupt controller in the CPU. If you have a single-CPU
650 system which has a processor with a local APIC, you can say Y here to
651 enable and use it. If you say Y here even though your machine doesn't
652 have a local APIC, then the kernel will still run with no slowdown at
653 all. The local APIC supports CPU-generated self-interrupts (timer,
654 performance counters), and the NMI watchdog which detects hard
658 bool "IO-APIC support on uniprocessors"
659 depends on X86_UP_APIC
661 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
662 SMP-capable replacement for PC-style interrupt controllers. Most
663 SMP systems and many recent uniprocessor systems have one.
665 If you have a single-CPU system with an IO-APIC, you can say Y here
666 to use it. If you say Y here even though your machine doesn't have
667 an IO-APIC, then the kernel will still run with no slowdown at all.
669 config X86_LOCAL_APIC
671 depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
675 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
677 config X86_VISWS_APIC
679 depends on X86_32 && X86_VISWS
681 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
682 bool "Reroute for broken boot IRQs"
684 depends on X86_IO_APIC
686 This option enables a workaround that fixes a source of
687 spurious interrupts. This is recommended when threaded
688 interrupt handling is used on systems where the generation of
689 superfluous "boot interrupts" cannot be disabled.
691 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
692 entry in the chipset's IO-APIC is masked (as, e.g. the RT
693 kernel does during interrupt handling). On chipsets where this
694 boot IRQ generation cannot be disabled, this workaround keeps
695 the original IRQ line masked so that only the equivalent "boot
696 IRQ" is delivered to the CPUs. The workaround also tells the
697 kernel to set up the IRQ handler on the boot IRQ line. In this
698 way only one interrupt is delivered to the kernel. Otherwise
699 the spurious second interrupt may cause the kernel to bring
700 down (vital) interrupt lines.
702 Only affects "broken" chipsets. Interrupt sharing may be
703 increased on these systems.
706 bool "Machine Check Exception"
707 depends on !X86_VOYAGER
709 Machine Check Exception support allows the processor to notify the
710 kernel if it detects a problem (e.g. overheating, component failure).
711 The action the kernel takes depends on the severity of the problem,
712 ranging from a warning message on the console, to halting the machine.
713 Your processor must be a Pentium or newer to support this - check the
714 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
715 have a design flaw which leads to false MCE events - hence MCE is
716 disabled on all P5 processors, unless explicitly enabled with "mce"
717 as a boot argument. Similarly, if MCE is built in and creates a
718 problem on some new non-standard machine, you can boot with "nomce"
719 to disable it. MCE support simply ignores non-MCE processors like
720 the 386 and 486, so nearly everyone can say Y here.
724 prompt "Intel MCE features"
725 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
727 Additional support for intel specific MCE features such as
732 prompt "AMD MCE features"
733 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
735 Additional support for AMD specific MCE features such as
736 the DRAM Error Threshold.
738 config X86_MCE_NONFATAL
739 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
740 depends on X86_32 && X86_MCE
742 Enabling this feature starts a timer that triggers every 5 seconds which
743 will look at the machine check registers to see if anything happened.
744 Non-fatal problems automatically get corrected (but still logged).
745 Disable this if you don't want to see these messages.
746 Seeing the messages this option prints out may be indicative of dying
747 or out-of-spec (ie, overclocked) hardware.
748 This option only does something on certain CPUs.
749 (AMD Athlon/Duron and Intel Pentium 4)
751 config X86_MCE_P4THERMAL
752 bool "check for P4 thermal throttling interrupt."
753 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
755 Enabling this feature will cause a message to be printed when the P4
756 enters thermal throttling.
759 bool "Enable VM86 support" if EMBEDDED
763 This option is required by programs like DOSEMU to run 16-bit legacy
764 code on X86 processors. It also may be needed by software like
765 XFree86 to initialize some video cards via BIOS. Disabling this
766 option saves about 6k.
769 tristate "Toshiba Laptop support"
772 This adds a driver to safely access the System Management Mode of
773 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
774 not work on models with a Phoenix BIOS. The System Management Mode
775 is used to set the BIOS and power saving options on Toshiba portables.
777 For information on utilities to make use of this driver see the
778 Toshiba Linux utilities web site at:
779 <http://www.buzzard.org.uk/toshiba/>.
781 Say Y if you intend to run this kernel on a Toshiba portable.
785 tristate "Dell laptop support"
787 This adds a driver to safely access the System Management Mode
788 of the CPU on the Dell Inspiron 8000. The System Management Mode
789 is used to read cpu temperature and cooling fan status and to
790 control the fans on the I8K portables.
792 This driver has been tested only on the Inspiron 8000 but it may
793 also work with other Dell laptops. You can force loading on other
794 models by passing the parameter `force=1' to the module. Use at
797 For information on utilities to make use of this driver see the
798 I8K Linux utilities web site at:
799 <http://people.debian.org/~dz/i8k/>
801 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
804 config X86_REBOOTFIXUPS
805 bool "Enable X86 board specific fixups for reboot"
808 This enables chipset and/or board specific fixups to be done
809 in order to get reboot to work correctly. This is only needed on
810 some combinations of hardware and BIOS. The symptom, for which
811 this config is intended, is when reboot ends with a stalled/hung
814 Currently, the only fixup is for the Geode machines using
815 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
817 Say Y if you want to enable the fixup. Currently, it's safe to
818 enable this option even if you don't need it.
822 tristate "/dev/cpu/microcode - microcode support"
825 If you say Y here, you will be able to update the microcode on
826 certain Intel and AMD processors. The Intel support is for the
827 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
828 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
829 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
830 You will obviously need the actual microcode binary data itself
831 which is not shipped with the Linux kernel.
833 This option selects the general module only, you need to select
834 at least one vendor specific module as well.
836 To compile this driver as a module, choose M here: the
837 module will be called microcode.
839 config MICROCODE_INTEL
840 bool "Intel microcode patch loading support"
845 This options enables microcode patch loading support for Intel
848 For latest news and information on obtaining all the required
849 Intel ingredients for this driver, check:
850 <http://www.urbanmyth.org/microcode/>.
853 bool "AMD microcode patch loading support"
857 If you select this option, microcode patch loading support for AMD
858 processors will be enabled.
860 config MICROCODE_OLD_INTERFACE
865 tristate "/dev/cpu/*/msr - Model-specific register support"
867 This device gives privileged processes access to the x86
868 Model-Specific Registers (MSRs). It is a character device with
869 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
870 MSR accesses are directed to a specific CPU on multi-processor
874 tristate "/dev/cpu/*/cpuid - CPU information support"
876 This device gives processes access to the x86 CPUID instruction to
877 be executed on a specific processor. It is a character device
878 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
882 prompt "High Memory Support"
883 default HIGHMEM4G if !X86_NUMAQ
884 default HIGHMEM64G if X86_NUMAQ
889 depends on !X86_NUMAQ
891 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
892 However, the address space of 32-bit x86 processors is only 4
893 Gigabytes large. That means that, if you have a large amount of
894 physical memory, not all of it can be "permanently mapped" by the
895 kernel. The physical memory that's not permanently mapped is called
898 If you are compiling a kernel which will never run on a machine with
899 more than 1 Gigabyte total physical RAM, answer "off" here (default
900 choice and suitable for most users). This will result in a "3GB/1GB"
901 split: 3GB are mapped so that each process sees a 3GB virtual memory
902 space and the remaining part of the 4GB virtual memory space is used
903 by the kernel to permanently map as much physical memory as
906 If the machine has between 1 and 4 Gigabytes physical RAM, then
909 If more than 4 Gigabytes is used then answer "64GB" here. This
910 selection turns Intel PAE (Physical Address Extension) mode on.
911 PAE implements 3-level paging on IA32 processors. PAE is fully
912 supported by Linux, PAE mode is implemented on all recent Intel
913 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
914 then the kernel will not boot on CPUs that don't support PAE!
916 The actual amount of total physical memory will either be
917 auto detected or can be forced by using a kernel command line option
918 such as "mem=256M". (Try "man bootparam" or see the documentation of
919 your boot loader (lilo or loadlin) about how to pass options to the
920 kernel at boot time.)
922 If unsure, say "off".
926 depends on !X86_NUMAQ
928 Select this if you have a 32-bit processor and between 1 and 4
929 gigabytes of physical RAM.
933 depends on !M386 && !M486
936 Select this if you have a 32-bit processor and more than 4
937 gigabytes of physical RAM.
942 depends on EXPERIMENTAL
943 prompt "Memory split" if EMBEDDED
947 Select the desired split between kernel and user memory.
949 If the address range available to the kernel is less than the
950 physical memory installed, the remaining memory will be available
951 as "high memory". Accessing high memory is a little more costly
952 than low memory, as it needs to be mapped into the kernel first.
953 Note that increasing the kernel address space limits the range
954 available to user programs, making the address space there
955 tighter. Selecting anything other than the default 3G/1G split
956 will also likely make your kernel incompatible with binary-only
959 If you are not absolutely sure what you are doing, leave this
963 bool "3G/1G user/kernel split"
964 config VMSPLIT_3G_OPT
966 bool "3G/1G user/kernel split (for full 1G low memory)"
968 bool "2G/2G user/kernel split"
969 config VMSPLIT_2G_OPT
971 bool "2G/2G user/kernel split (for full 2G low memory)"
973 bool "1G/3G user/kernel split"
978 default 0xB0000000 if VMSPLIT_3G_OPT
979 default 0x80000000 if VMSPLIT_2G
980 default 0x78000000 if VMSPLIT_2G_OPT
981 default 0x40000000 if VMSPLIT_1G
987 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
990 bool "PAE (Physical Address Extension) Support"
991 depends on X86_32 && !HIGHMEM4G
993 PAE is required for NX support, and furthermore enables
994 larger swapspace support for non-overcommit purposes. It
995 has the cost of more pagetable lookup overhead, and also
996 consumes more pagetable space per process.
998 config ARCH_PHYS_ADDR_T_64BIT
999 def_bool X86_64 || X86_PAE
1001 config DIRECT_GBPAGES
1002 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1006 Allow the kernel linear mapping to use 1GB pages on CPUs that
1007 support it. This can improve the kernel's performance a tiny bit by
1008 reducing TLB pressure. If in doubt, say "Y".
1010 # Common NUMA Features
1012 bool "Numa Memory Allocation and Scheduler Support"
1014 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1016 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1018 Enable NUMA (Non Uniform Memory Access) support.
1020 The kernel will try to allocate memory used by a CPU on the
1021 local memory controller of the CPU and add some more
1022 NUMA awareness to the kernel.
1024 For 64-bit this is recommended if the system is Intel Core i7
1025 (or later), AMD Opteron, or EM64T NUMA.
1027 For 32-bit this is only needed on (rare) 32-bit-only platforms
1028 that support NUMA topologies, such as NUMAQ / Summit, or if you
1029 boot a 32-bit kernel on a 64-bit NUMA platform.
1031 Otherwise, you should say N.
1033 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1034 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1038 prompt "Old style AMD Opteron NUMA detection"
1039 depends on X86_64 && NUMA && PCI
1041 Enable K8 NUMA node topology detection. You should say Y here if
1042 you have a multi processor AMD K8 system. This uses an old
1043 method to read the NUMA configuration directly from the builtin
1044 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1045 instead, which also takes priority if both are compiled in.
1047 config X86_64_ACPI_NUMA
1049 prompt "ACPI NUMA detection"
1050 depends on X86_64 && NUMA && ACPI && PCI
1053 Enable ACPI SRAT based node topology detection.
1055 # Some NUMA nodes have memory ranges that span
1056 # other nodes. Even though a pfn is valid and
1057 # between a node's start and end pfns, it may not
1058 # reside on that node. See memmap_init_zone()
1060 config NODES_SPAN_OTHER_NODES
1062 depends on X86_64_ACPI_NUMA
1065 bool "NUMA emulation"
1066 depends on X86_64 && NUMA
1068 Enable NUMA emulation. A flat machine will be split
1069 into virtual nodes when booted with "numa=fake=N", where N is the
1070 number of nodes. This is only useful for debugging.
1073 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1075 default "9" if MAXSMP
1076 default "6" if X86_64
1077 default "4" if X86_NUMAQ
1079 depends on NEED_MULTIPLE_NODES
1081 Specify the maximum number of NUMA Nodes available on the target
1082 system. Increases memory reserved to accomodate various tables.
1084 config HAVE_ARCH_BOOTMEM_NODE
1086 depends on X86_32 && NUMA
1088 config ARCH_HAVE_MEMORY_PRESENT
1090 depends on X86_32 && DISCONTIGMEM
1092 config NEED_NODE_MEMMAP_SIZE
1094 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1096 config HAVE_ARCH_ALLOC_REMAP
1098 depends on X86_32 && NUMA
1100 config ARCH_FLATMEM_ENABLE
1102 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1104 config ARCH_DISCONTIGMEM_ENABLE
1106 depends on NUMA && X86_32
1108 config ARCH_DISCONTIGMEM_DEFAULT
1110 depends on NUMA && X86_32
1112 config ARCH_SPARSEMEM_DEFAULT
1116 config ARCH_SPARSEMEM_ENABLE
1118 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC) || X86_GENERICARCH
1119 select SPARSEMEM_STATIC if X86_32
1120 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1122 config ARCH_SELECT_MEMORY_MODEL
1124 depends on ARCH_SPARSEMEM_ENABLE
1126 config ARCH_MEMORY_PROBE
1128 depends on MEMORY_HOTPLUG
1133 bool "Allocate 3rd-level pagetables from highmem"
1134 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1136 The VM uses one page table entry for each page of physical memory.
1137 For systems with a lot of RAM, this can be wasteful of precious
1138 low memory. Setting this option will put user-space page table
1139 entries in high memory.
1141 config X86_CHECK_BIOS_CORRUPTION
1142 bool "Check for low memory corruption"
1144 Periodically check for memory corruption in low memory, which
1145 is suspected to be caused by BIOS. Even when enabled in the
1146 configuration, it is disabled at runtime. Enable it by
1147 setting "memory_corruption_check=1" on the kernel command
1148 line. By default it scans the low 64k of memory every 60
1149 seconds; see the memory_corruption_check_size and
1150 memory_corruption_check_period parameters in
1151 Documentation/kernel-parameters.txt to adjust this.
1153 When enabled with the default parameters, this option has
1154 almost no overhead, as it reserves a relatively small amount
1155 of memory and scans it infrequently. It both detects corruption
1156 and prevents it from affecting the running system.
1158 It is, however, intended as a diagnostic tool; if repeatable
1159 BIOS-originated corruption always affects the same memory,
1160 you can use memmap= to prevent the kernel from using that
1163 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1164 bool "Set the default setting of memory_corruption_check"
1165 depends on X86_CHECK_BIOS_CORRUPTION
1168 Set whether the default state of memory_corruption_check is
1171 config X86_RESERVE_LOW_64K
1172 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1175 Reserve the first 64K of physical RAM on BIOSes that are known
1176 to potentially corrupt that memory range. A numbers of BIOSes are
1177 known to utilize this area during suspend/resume, so it must not
1178 be used by the kernel.
1180 Set this to N if you are absolutely sure that you trust the BIOS
1181 to get all its memory reservations and usages right.
1183 If you have doubts about the BIOS (e.g. suspend/resume does not
1184 work or there's kernel crashes after certain hardware hotplug
1185 events) and it's not AMI or Phoenix, then you might want to enable
1186 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1187 corruption patterns.
1191 config MATH_EMULATION
1193 prompt "Math emulation" if X86_32
1195 Linux can emulate a math coprocessor (used for floating point
1196 operations) if you don't have one. 486DX and Pentium processors have
1197 a math coprocessor built in, 486SX and 386 do not, unless you added
1198 a 487DX or 387, respectively. (The messages during boot time can
1199 give you some hints here ["man dmesg"].) Everyone needs either a
1200 coprocessor or this emulation.
1202 If you don't have a math coprocessor, you need to say Y here; if you
1203 say Y here even though you have a coprocessor, the coprocessor will
1204 be used nevertheless. (This behavior can be changed with the kernel
1205 command line option "no387", which comes handy if your coprocessor
1206 is broken. Try "man bootparam" or see the documentation of your boot
1207 loader (lilo or loadlin) about how to pass options to the kernel at
1208 boot time.) This means that it is a good idea to say Y here if you
1209 intend to use this kernel on different machines.
1211 More information about the internals of the Linux math coprocessor
1212 emulation can be found in <file:arch/x86/math-emu/README>.
1214 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1215 kernel, it won't hurt.
1218 bool "MTRR (Memory Type Range Register) support"
1220 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1221 the Memory Type Range Registers (MTRRs) may be used to control
1222 processor access to memory ranges. This is most useful if you have
1223 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1224 allows bus write transfers to be combined into a larger transfer
1225 before bursting over the PCI/AGP bus. This can increase performance
1226 of image write operations 2.5 times or more. Saying Y here creates a
1227 /proc/mtrr file which may be used to manipulate your processor's
1228 MTRRs. Typically the X server should use this.
1230 This code has a reasonably generic interface so that similar
1231 control registers on other processors can be easily supported
1234 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1235 Registers (ARRs) which provide a similar functionality to MTRRs. For
1236 these, the ARRs are used to emulate the MTRRs.
1237 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1238 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1239 write-combining. All of these processors are supported by this code
1240 and it makes sense to say Y here if you have one of them.
1242 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1243 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1244 can lead to all sorts of problems, so it's good to say Y here.
1246 You can safely say Y even if your machine doesn't have MTRRs, you'll
1247 just add about 9 KB to your kernel.
1249 See <file:Documentation/x86/mtrr.txt> for more information.
1251 config MTRR_SANITIZER
1253 prompt "MTRR cleanup support"
1256 Convert MTRR layout from continuous to discrete, so X drivers can
1257 add writeback entries.
1259 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1260 The largest mtrr entry size for a continous block can be set with
1265 config MTRR_SANITIZER_ENABLE_DEFAULT
1266 int "MTRR cleanup enable value (0-1)"
1269 depends on MTRR_SANITIZER
1271 Enable mtrr cleanup default value
1273 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1274 int "MTRR cleanup spare reg num (0-7)"
1277 depends on MTRR_SANITIZER
1279 mtrr cleanup spare entries default, it can be changed via
1280 mtrr_spare_reg_nr=N on the kernel command line.
1284 prompt "x86 PAT support"
1287 Use PAT attributes to setup page level cache control.
1289 PATs are the modern equivalents of MTRRs and are much more
1290 flexible than MTRRs.
1292 Say N here if you see bootup problems (boot crash, boot hang,
1293 spontaneous reboots) or a non-working video driver.
1298 bool "EFI runtime service support"
1301 This enables the kernel to use EFI runtime services that are
1302 available (such as the EFI variable services).
1304 This option is only useful on systems that have EFI firmware.
1305 In addition, you should use the latest ELILO loader available
1306 at <http://elilo.sourceforge.net> in order to take advantage
1307 of EFI runtime services. However, even with this option, the
1308 resultant kernel should continue to boot on existing non-EFI
1313 prompt "Enable seccomp to safely compute untrusted bytecode"
1315 This kernel feature is useful for number crunching applications
1316 that may need to compute untrusted bytecode during their
1317 execution. By using pipes or other transports made available to
1318 the process as file descriptors supporting the read/write
1319 syscalls, it's possible to isolate those applications in
1320 their own address space using seccomp. Once seccomp is
1321 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1322 and the task is only allowed to execute a few safe syscalls
1323 defined by each seccomp mode.
1325 If unsure, say Y. Only embedded should say N here.
1327 config CC_STACKPROTECTOR_ALL
1330 config CC_STACKPROTECTOR
1331 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1333 select CC_STACKPROTECTOR_ALL
1335 This option turns on the -fstack-protector GCC feature. This
1336 feature puts, at the beginning of functions, a canary value on
1337 the stack just before the return address, and validates
1338 the value just before actually returning. Stack based buffer
1339 overflows (that need to overwrite this return address) now also
1340 overwrite the canary, which gets detected and the attack is then
1341 neutralized via a kernel panic.
1343 This feature requires gcc version 4.2 or above, or a distribution
1344 gcc with the feature backported. Older versions are automatically
1345 detected and for those versions, this configuration option is
1346 ignored. (and a warning is printed during bootup)
1348 source kernel/Kconfig.hz
1351 bool "kexec system call"
1353 kexec is a system call that implements the ability to shutdown your
1354 current kernel, and to start another kernel. It is like a reboot
1355 but it is independent of the system firmware. And like a reboot
1356 you can start any kernel with it, not just Linux.
1358 The name comes from the similarity to the exec system call.
1360 It is an ongoing process to be certain the hardware in a machine
1361 is properly shutdown, so do not be surprised if this code does not
1362 initially work for you. It may help to enable device hotplugging
1363 support. As of this writing the exact hardware interface is
1364 strongly in flux, so no good recommendation can be made.
1367 bool "kernel crash dumps"
1368 depends on X86_64 || (X86_32 && HIGHMEM)
1370 Generate crash dump after being started by kexec.
1371 This should be normally only set in special crash dump kernels
1372 which are loaded in the main kernel with kexec-tools into
1373 a specially reserved region and then later executed after
1374 a crash by kdump/kexec. The crash dump kernel must be compiled
1375 to a memory address not used by the main kernel or BIOS using
1376 PHYSICAL_START, or it must be built as a relocatable image
1377 (CONFIG_RELOCATABLE=y).
1378 For more details see Documentation/kdump/kdump.txt
1381 bool "kexec jump (EXPERIMENTAL)"
1382 depends on EXPERIMENTAL
1383 depends on KEXEC && HIBERNATION && X86_32
1385 Jump between original kernel and kexeced kernel and invoke
1386 code in physical address mode via KEXEC
1388 config PHYSICAL_START
1389 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1390 default "0x1000000" if X86_NUMAQ
1391 default "0x200000" if X86_64
1394 This gives the physical address where the kernel is loaded.
1396 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1397 bzImage will decompress itself to above physical address and
1398 run from there. Otherwise, bzImage will run from the address where
1399 it has been loaded by the boot loader and will ignore above physical
1402 In normal kdump cases one does not have to set/change this option
1403 as now bzImage can be compiled as a completely relocatable image
1404 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1405 address. This option is mainly useful for the folks who don't want
1406 to use a bzImage for capturing the crash dump and want to use a
1407 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1408 to be specifically compiled to run from a specific memory area
1409 (normally a reserved region) and this option comes handy.
1411 So if you are using bzImage for capturing the crash dump, leave
1412 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1413 Otherwise if you plan to use vmlinux for capturing the crash dump
1414 change this value to start of the reserved region (Typically 16MB
1415 0x1000000). In other words, it can be set based on the "X" value as
1416 specified in the "crashkernel=YM@XM" command line boot parameter
1417 passed to the panic-ed kernel. Typically this parameter is set as
1418 crashkernel=64M@16M. Please take a look at
1419 Documentation/kdump/kdump.txt for more details about crash dumps.
1421 Usage of bzImage for capturing the crash dump is recommended as
1422 one does not have to build two kernels. Same kernel can be used
1423 as production kernel and capture kernel. Above option should have
1424 gone away after relocatable bzImage support is introduced. But it
1425 is present because there are users out there who continue to use
1426 vmlinux for dump capture. This option should go away down the
1429 Don't change this unless you know what you are doing.
1432 bool "Build a relocatable kernel (EXPERIMENTAL)"
1433 depends on EXPERIMENTAL
1435 This builds a kernel image that retains relocation information
1436 so it can be loaded someplace besides the default 1MB.
1437 The relocations tend to make the kernel binary about 10% larger,
1438 but are discarded at runtime.
1440 One use is for the kexec on panic case where the recovery kernel
1441 must live at a different physical address than the primary
1444 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1445 it has been loaded at and the compile time physical address
1446 (CONFIG_PHYSICAL_START) is ignored.
1448 config PHYSICAL_ALIGN
1450 prompt "Alignment value to which kernel should be aligned" if X86_32
1451 default "0x100000" if X86_32
1452 default "0x200000" if X86_64
1453 range 0x2000 0x400000
1455 This value puts the alignment restrictions on physical address
1456 where kernel is loaded and run from. Kernel is compiled for an
1457 address which meets above alignment restriction.
1459 If bootloader loads the kernel at a non-aligned address and
1460 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1461 address aligned to above value and run from there.
1463 If bootloader loads the kernel at a non-aligned address and
1464 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1465 load address and decompress itself to the address it has been
1466 compiled for and run from there. The address for which kernel is
1467 compiled already meets above alignment restrictions. Hence the
1468 end result is that kernel runs from a physical address meeting
1469 above alignment restrictions.
1471 Don't change this unless you know what you are doing.
1474 bool "Support for hot-pluggable CPUs"
1475 depends on SMP && HOTPLUG && !X86_VOYAGER
1477 Say Y here to allow turning CPUs off and on. CPUs can be
1478 controlled through /sys/devices/system/cpu.
1479 ( Note: power management support will enable this option
1480 automatically on SMP systems. )
1481 Say N if you want to disable CPU hotplug.
1485 prompt "Compat VDSO support"
1486 depends on X86_32 || IA32_EMULATION
1488 Map the 32-bit VDSO to the predictable old-style address too.
1490 Say N here if you are running a sufficiently recent glibc
1491 version (2.3.3 or later), to remove the high-mapped
1492 VDSO mapping and to exclusively use the randomized VDSO.
1497 bool "Built-in kernel command line"
1500 Allow for specifying boot arguments to the kernel at
1501 build time. On some systems (e.g. embedded ones), it is
1502 necessary or convenient to provide some or all of the
1503 kernel boot arguments with the kernel itself (that is,
1504 to not rely on the boot loader to provide them.)
1506 To compile command line arguments into the kernel,
1507 set this option to 'Y', then fill in the
1508 the boot arguments in CONFIG_CMDLINE.
1510 Systems with fully functional boot loaders (i.e. non-embedded)
1511 should leave this option set to 'N'.
1514 string "Built-in kernel command string"
1515 depends on CMDLINE_BOOL
1518 Enter arguments here that should be compiled into the kernel
1519 image and used at boot time. If the boot loader provides a
1520 command line at boot time, it is appended to this string to
1521 form the full kernel command line, when the system boots.
1523 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1524 change this behavior.
1526 In most cases, the command line (whether built-in or provided
1527 by the boot loader) should specify the device for the root
1530 config CMDLINE_OVERRIDE
1531 bool "Built-in command line overrides boot loader arguments"
1533 depends on CMDLINE_BOOL
1535 Set this option to 'Y' to have the kernel ignore the boot loader
1536 command line, and use ONLY the built-in command line.
1538 This is used to work around broken boot loaders. This should
1539 be set to 'N' under normal conditions.
1543 config ARCH_ENABLE_MEMORY_HOTPLUG
1545 depends on X86_64 || (X86_32 && HIGHMEM)
1547 config ARCH_ENABLE_MEMORY_HOTREMOVE
1549 depends on MEMORY_HOTPLUG
1551 config HAVE_ARCH_EARLY_PFN_TO_NID
1555 menu "Power management and ACPI options"
1556 depends on !X86_VOYAGER
1558 config ARCH_HIBERNATION_HEADER
1560 depends on X86_64 && HIBERNATION
1562 source "kernel/power/Kconfig"
1564 source "drivers/acpi/Kconfig"
1569 depends on APM || APM_MODULE
1572 tristate "APM (Advanced Power Management) BIOS support"
1573 depends on X86_32 && PM_SLEEP
1575 APM is a BIOS specification for saving power using several different
1576 techniques. This is mostly useful for battery powered laptops with
1577 APM compliant BIOSes. If you say Y here, the system time will be
1578 reset after a RESUME operation, the /proc/apm device will provide
1579 battery status information, and user-space programs will receive
1580 notification of APM "events" (e.g. battery status change).
1582 If you select "Y" here, you can disable actual use of the APM
1583 BIOS by passing the "apm=off" option to the kernel at boot time.
1585 Note that the APM support is almost completely disabled for
1586 machines with more than one CPU.
1588 In order to use APM, you will need supporting software. For location
1589 and more information, read <file:Documentation/power/pm.txt> and the
1590 Battery Powered Linux mini-HOWTO, available from
1591 <http://www.tldp.org/docs.html#howto>.
1593 This driver does not spin down disk drives (see the hdparm(8)
1594 manpage ("man 8 hdparm") for that), and it doesn't turn off
1595 VESA-compliant "green" monitors.
1597 This driver does not support the TI 4000M TravelMate and the ACER
1598 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1599 desktop machines also don't have compliant BIOSes, and this driver
1600 may cause those machines to panic during the boot phase.
1602 Generally, if you don't have a battery in your machine, there isn't
1603 much point in using this driver and you should say N. If you get
1604 random kernel OOPSes or reboots that don't seem to be related to
1605 anything, try disabling/enabling this option (or disabling/enabling
1608 Some other things you should try when experiencing seemingly random,
1611 1) make sure that you have enough swap space and that it is
1613 2) pass the "no-hlt" option to the kernel
1614 3) switch on floating point emulation in the kernel and pass
1615 the "no387" option to the kernel
1616 4) pass the "floppy=nodma" option to the kernel
1617 5) pass the "mem=4M" option to the kernel (thereby disabling
1618 all but the first 4 MB of RAM)
1619 6) make sure that the CPU is not over clocked.
1620 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1621 8) disable the cache from your BIOS settings
1622 9) install a fan for the video card or exchange video RAM
1623 10) install a better fan for the CPU
1624 11) exchange RAM chips
1625 12) exchange the motherboard.
1627 To compile this driver as a module, choose M here: the
1628 module will be called apm.
1632 config APM_IGNORE_USER_SUSPEND
1633 bool "Ignore USER SUSPEND"
1635 This option will ignore USER SUSPEND requests. On machines with a
1636 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1637 series notebooks, it is necessary to say Y because of a BIOS bug.
1639 config APM_DO_ENABLE
1640 bool "Enable PM at boot time"
1642 Enable APM features at boot time. From page 36 of the APM BIOS
1643 specification: "When disabled, the APM BIOS does not automatically
1644 power manage devices, enter the Standby State, enter the Suspend
1645 State, or take power saving steps in response to CPU Idle calls."
1646 This driver will make CPU Idle calls when Linux is idle (unless this
1647 feature is turned off -- see "Do CPU IDLE calls", below). This
1648 should always save battery power, but more complicated APM features
1649 will be dependent on your BIOS implementation. You may need to turn
1650 this option off if your computer hangs at boot time when using APM
1651 support, or if it beeps continuously instead of suspending. Turn
1652 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1653 T400CDT. This is off by default since most machines do fine without
1657 bool "Make CPU Idle calls when idle"
1659 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1660 On some machines, this can activate improved power savings, such as
1661 a slowed CPU clock rate, when the machine is idle. These idle calls
1662 are made after the idle loop has run for some length of time (e.g.,
1663 333 mS). On some machines, this will cause a hang at boot time or
1664 whenever the CPU becomes idle. (On machines with more than one CPU,
1665 this option does nothing.)
1667 config APM_DISPLAY_BLANK
1668 bool "Enable console blanking using APM"
1670 Enable console blanking using the APM. Some laptops can use this to
1671 turn off the LCD backlight when the screen blanker of the Linux
1672 virtual console blanks the screen. Note that this is only used by
1673 the virtual console screen blanker, and won't turn off the backlight
1674 when using the X Window system. This also doesn't have anything to
1675 do with your VESA-compliant power-saving monitor. Further, this
1676 option doesn't work for all laptops -- it might not turn off your
1677 backlight at all, or it might print a lot of errors to the console,
1678 especially if you are using gpm.
1680 config APM_ALLOW_INTS
1681 bool "Allow interrupts during APM BIOS calls"
1683 Normally we disable external interrupts while we are making calls to
1684 the APM BIOS as a measure to lessen the effects of a badly behaving
1685 BIOS implementation. The BIOS should reenable interrupts if it
1686 needs to. Unfortunately, some BIOSes do not -- especially those in
1687 many of the newer IBM Thinkpads. If you experience hangs when you
1688 suspend, try setting this to Y. Otherwise, say N.
1692 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1694 source "drivers/cpuidle/Kconfig"
1696 source "drivers/idle/Kconfig"
1701 menu "Bus options (PCI etc.)"
1706 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1708 Find out whether you have a PCI motherboard. PCI is the name of a
1709 bus system, i.e. the way the CPU talks to the other stuff inside
1710 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1711 VESA. If you have PCI, say Y, otherwise N.
1714 prompt "PCI access mode"
1715 depends on X86_32 && PCI
1718 On PCI systems, the BIOS can be used to detect the PCI devices and
1719 determine their configuration. However, some old PCI motherboards
1720 have BIOS bugs and may crash if this is done. Also, some embedded
1721 PCI-based systems don't have any BIOS at all. Linux can also try to
1722 detect the PCI hardware directly without using the BIOS.
1724 With this option, you can specify how Linux should detect the
1725 PCI devices. If you choose "BIOS", the BIOS will be used,
1726 if you choose "Direct", the BIOS won't be used, and if you
1727 choose "MMConfig", then PCI Express MMCONFIG will be used.
1728 If you choose "Any", the kernel will try MMCONFIG, then the
1729 direct access method and falls back to the BIOS if that doesn't
1730 work. If unsure, go with the default, which is "Any".
1735 config PCI_GOMMCONFIG
1752 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1754 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1757 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1761 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1765 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1772 bool "Support mmconfig PCI config space access"
1773 depends on X86_64 && PCI && ACPI
1776 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1777 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1779 DMA remapping (DMAR) devices support enables independent address
1780 translations for Direct Memory Access (DMA) from devices.
1781 These DMA remapping devices are reported via ACPI tables
1782 and include PCI device scope covered by these DMA
1787 prompt "Support for Graphics workaround"
1790 Current Graphics drivers tend to use physical address
1791 for DMA and avoid using DMA APIs. Setting this config
1792 option permits the IOMMU driver to set a unity map for
1793 all the OS-visible memory. Hence the driver can continue
1794 to use physical addresses for DMA.
1796 config DMAR_FLOPPY_WA
1800 Floppy disk drivers are know to bypass DMA API calls
1801 thereby failing to work when IOMMU is enabled. This
1802 workaround will setup a 1:1 mapping for the first
1803 16M to make floppy (an ISA device) work.
1806 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1807 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1809 Supports Interrupt remapping for IO-APIC and MSI devices.
1810 To use x2apic mode in the CPU's which support x2APIC enhancements or
1811 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1813 source "drivers/pci/pcie/Kconfig"
1815 source "drivers/pci/Kconfig"
1817 # x86_64 have no ISA slots, but do have ISA-style DMA.
1825 depends on !X86_VOYAGER
1827 Find out whether you have ISA slots on your motherboard. ISA is the
1828 name of a bus system, i.e. the way the CPU talks to the other stuff
1829 inside your box. Other bus systems are PCI, EISA, MicroChannel
1830 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1831 newer boards don't support it. If you have ISA, say Y, otherwise N.
1837 The Extended Industry Standard Architecture (EISA) bus was
1838 developed as an open alternative to the IBM MicroChannel bus.
1840 The EISA bus provided some of the features of the IBM MicroChannel
1841 bus while maintaining backward compatibility with cards made for
1842 the older ISA bus. The EISA bus saw limited use between 1988 and
1843 1995 when it was made obsolete by the PCI bus.
1845 Say Y here if you are building a kernel for an EISA-based machine.
1849 source "drivers/eisa/Kconfig"
1854 MicroChannel Architecture is found in some IBM PS/2 machines and
1855 laptops. It is a bus system similar to PCI or ISA. See
1856 <file:Documentation/mca.txt> (and especially the web page given
1857 there) before attempting to build an MCA bus kernel.
1859 source "drivers/mca/Kconfig"
1862 tristate "NatSemi SCx200 support"
1864 This provides basic support for National Semiconductor's
1865 (now AMD's) Geode processors. The driver probes for the
1866 PCI-IDs of several on-chip devices, so its a good dependency
1867 for other scx200_* drivers.
1869 If compiled as a module, the driver is named scx200.
1871 config SCx200HR_TIMER
1872 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1873 depends on SCx200 && GENERIC_TIME
1876 This driver provides a clocksource built upon the on-chip
1877 27MHz high-resolution timer. Its also a workaround for
1878 NSC Geode SC-1100's buggy TSC, which loses time when the
1879 processor goes idle (as is done by the scheduler). The
1880 other workaround is idle=poll boot option.
1882 config GEODE_MFGPT_TIMER
1884 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1885 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1887 This driver provides a clock event source based on the MFGPT
1888 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1889 MFGPTs have a better resolution and max interval than the
1890 generic PIT, and are suitable for use as high-res timers.
1893 bool "One Laptop Per Child support"
1896 Add support for detecting the unique features of the OLPC
1903 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1905 source "drivers/pcmcia/Kconfig"
1907 source "drivers/pci/hotplug/Kconfig"
1912 menu "Executable file formats / Emulations"
1914 source "fs/Kconfig.binfmt"
1916 config IA32_EMULATION
1917 bool "IA32 Emulation"
1919 select COMPAT_BINFMT_ELF
1921 Include code to run 32-bit programs under a 64-bit kernel. You should
1922 likely turn this on, unless you're 100% sure that you don't have any
1923 32-bit programs left.
1926 tristate "IA32 a.out support"
1927 depends on IA32_EMULATION
1929 Support old a.out binaries in the 32bit emulation.
1933 depends on IA32_EMULATION
1935 config COMPAT_FOR_U64_ALIGNMENT
1939 config SYSVIPC_COMPAT
1941 depends on COMPAT && SYSVIPC
1946 config HAVE_ATOMIC_IOMAP
1950 source "net/Kconfig"
1952 source "drivers/Kconfig"
1954 source "drivers/firmware/Kconfig"
1958 source "arch/x86/Kconfig.debug"
1960 source "security/Kconfig"
1962 source "crypto/Kconfig"
1964 source "arch/x86/kvm/Kconfig"
1966 source "lib/Kconfig"
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