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.
276 config X86_NON_STANDARD
277 bool "Support for non-standard x86 platforms"
279 If you disable this option then the kernel will only support
280 standard PC platforms. (which covers the vast majority of
283 If you enable this option then you'll be able to select a number
284 of less common non-PC x86 platforms: VisWS, RDC321, SGI/UV.
286 If you have one of these systems, or if you want to build a
287 generic distribution kernel, say Y here - otherwise say N.
290 bool "SGI 320/540 (Visual Workstation)"
291 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
292 depends on X86_NON_STANDARD
294 The SGI Visual Workstation series is an IA32-based workstation
295 based on SGI systems chips with some legacy PC hardware attached.
297 Say Y here to create a kernel to run on the SGI 320 or 540.
299 A kernel compiled for the Visual Workstation will run on general
300 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
303 bool "RDC R-321x SoC"
305 depends on X86_NON_STANDARD
307 select X86_REBOOTFIXUPS
309 This option is needed for RDC R-321x system-on-chip, also known
311 If you don't have one of these chips, you should say N here.
314 bool "SGI Ultraviolet"
316 depends on X86_NON_STANDARD
318 This option is needed in order to support SGI Ultraviolet systems.
319 If you don't have one of these, you should say N here.
322 bool "Support for ScaleMP vSMP"
324 depends on X86_64 && PCI
325 depends on X86_NON_STANDARD
327 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
328 supposed to run on these EM64T-based machines. Only choose this option
329 if you have one of these machines.
334 depends on X86_NON_STANDARD
336 Select this for an AMD Elan processor.
338 Do not use this option for K6/Athlon/Opteron processors!
340 If unsure, choose "PC-compatible" instead.
344 depends on X86_32 && SMP && !PCI && BROKEN
345 depends on X86_NON_STANDARD
347 Voyager is an MCA-based 32-way capable SMP architecture proprietary
348 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
352 If you do not specifically know you have a Voyager based machine,
353 say N here, otherwise the kernel you build will not be bootable.
355 config X86_GENERICARCH
356 bool "Support non-standard 32-bit SMP architectures"
357 depends on X86_32 && SMP
358 depends on X86_NON_STANDARD
360 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
361 subarchitectures. It is intended for a generic binary kernel.
362 if you select them all, kernel will probe it one by one. and will
366 bool "NUMAQ (IBM/Sequent)"
367 depends on X86_GENERICARCH
371 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
372 NUMA multiquad box. This changes the way that processors are
373 bootstrapped, and uses Clustered Logical APIC addressing mode instead
374 of Flat Logical. You will need a new lynxer.elf file to flash your
375 firmware with - send email to <Martin.Bligh@us.ibm.com>.
378 bool "Summit/EXA (IBM x440)"
379 depends on X86_GENERICARCH
381 This option is needed for IBM systems that use the Summit/EXA chipset.
382 In particular, it is needed for the x440.
385 bool "Support for Unisys ES7000 IA32 series"
386 depends on X86_GENERICARCH
388 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
389 supposed to run on an IA32-based Unisys ES7000 system.
392 bool "Support for big SMP systems with more than 8 CPUs"
393 depends on X86_GENERICARCH
395 This option is needed for the systems that have more than 8 CPUs
396 and if the system is not of any sub-arch type above.
398 config SCHED_OMIT_FRAME_POINTER
400 prompt "Single-depth WCHAN output"
403 Calculate simpler /proc/<PID>/wchan values. If this option
404 is disabled then wchan values will recurse back to the
405 caller function. This provides more accurate wchan values,
406 at the expense of slightly more scheduling overhead.
408 If in doubt, say "Y".
410 menuconfig PARAVIRT_GUEST
411 bool "Paravirtualized guest support"
413 Say Y here to get to see options related to running Linux under
414 various hypervisors. This option alone does not add any kernel code.
416 If you say N, all options in this submenu will be skipped and disabled.
420 source "arch/x86/xen/Kconfig"
423 bool "VMI Guest support"
427 VMI provides a paravirtualized interface to the VMware ESX server
428 (it could be used by other hypervisors in theory too, but is not
429 at the moment), by linking the kernel to a GPL-ed ROM module
430 provided by the hypervisor.
433 bool "KVM paravirtualized clock"
435 select PARAVIRT_CLOCK
437 Turning on this option will allow you to run a paravirtualized clock
438 when running over the KVM hypervisor. Instead of relying on a PIT
439 (or probably other) emulation by the underlying device model, the host
440 provides the guest with timing infrastructure such as time of day, and
444 bool "KVM Guest support"
447 This option enables various optimizations for running under the KVM
450 source "arch/x86/lguest/Kconfig"
453 bool "Enable paravirtualization code"
455 This changes the kernel so it can modify itself when it is run
456 under a hypervisor, potentially improving performance significantly
457 over full virtualization. However, when run without a hypervisor
458 the kernel is theoretically slower and slightly larger.
460 config PARAVIRT_CLOCK
466 config PARAVIRT_DEBUG
467 bool "paravirt-ops debugging"
468 depends on PARAVIRT && DEBUG_KERNEL
470 Enable to debug paravirt_ops internals. Specifically, BUG if
471 a paravirt_op is missing when it is called.
476 This option adds a kernel parameter 'memtest', which allows memtest
478 memtest=0, mean disabled; -- default
479 memtest=1, mean do 1 test pattern;
481 memtest=4, mean do 4 test patterns.
482 If you are unsure how to answer this question, answer N.
484 config X86_SUMMIT_NUMA
486 depends on X86_32 && NUMA && X86_GENERICARCH
488 config X86_CYCLONE_TIMER
490 depends on X86_GENERICARCH
492 source "arch/x86/Kconfig.cpu"
496 prompt "HPET Timer Support" if X86_32
498 Use the IA-PC HPET (High Precision Event Timer) to manage
499 time in preference to the PIT and RTC, if a HPET is
501 HPET is the next generation timer replacing legacy 8254s.
502 The HPET provides a stable time base on SMP
503 systems, unlike the TSC, but it is more expensive to access,
504 as it is off-chip. You can find the HPET spec at
505 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
507 You can safely choose Y here. However, HPET will only be
508 activated if the platform and the BIOS support this feature.
509 Otherwise the 8254 will be used for timing services.
511 Choose N to continue using the legacy 8254 timer.
513 config HPET_EMULATE_RTC
515 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
517 # Mark as embedded because too many people got it wrong.
518 # The code disables itself when not needed.
521 bool "Enable DMI scanning" if EMBEDDED
523 Enabled scanning of DMI to identify machine quirks. Say Y
524 here unless you have verified that your setup is not
525 affected by entries in the DMI blacklist. Required by PNP
529 bool "GART IOMMU support" if EMBEDDED
533 depends on X86_64 && PCI
535 Support for full DMA access of devices with 32bit memory access only
536 on systems with more than 3GB. This is usually needed for USB,
537 sound, many IDE/SATA chipsets and some other devices.
538 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
539 based hardware IOMMU and a software bounce buffer based IOMMU used
540 on Intel systems and as fallback.
541 The code is only active when needed (enough memory and limited
542 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
546 bool "IBM Calgary IOMMU support"
548 depends on X86_64 && PCI && EXPERIMENTAL
550 Support for hardware IOMMUs in IBM's xSeries x366 and x460
551 systems. Needed to run systems with more than 3GB of memory
552 properly with 32-bit PCI devices that do not support DAC
553 (Double Address Cycle). Calgary also supports bus level
554 isolation, where all DMAs pass through the IOMMU. This
555 prevents them from going anywhere except their intended
556 destination. This catches hard-to-find kernel bugs and
557 mis-behaving drivers and devices that do not use the DMA-API
558 properly to set up their DMA buffers. The IOMMU can be
559 turned off at boot time with the iommu=off parameter.
560 Normally the kernel will make the right choice by itself.
563 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
565 prompt "Should Calgary be enabled by default?"
566 depends on CALGARY_IOMMU
568 Should Calgary be enabled by default? if you choose 'y', Calgary
569 will be used (if it exists). If you choose 'n', Calgary will not be
570 used even if it exists. If you choose 'n' and would like to use
571 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
575 bool "AMD IOMMU support"
578 depends on X86_64 && PCI && ACPI
580 With this option you can enable support for AMD IOMMU hardware in
581 your system. An IOMMU is a hardware component which provides
582 remapping of DMA memory accesses from devices. With an AMD IOMMU you
583 can isolate the the DMA memory of different devices and protect the
584 system from misbehaving device drivers or hardware.
586 You can find out if your system has an AMD IOMMU if you look into
587 your BIOS for an option to enable it or if you have an IVRS ACPI
590 config AMD_IOMMU_STATS
591 bool "Export AMD IOMMU statistics to debugfs"
595 This option enables code in the AMD IOMMU driver to collect various
596 statistics about whats happening in the driver and exports that
597 information to userspace via debugfs.
600 # need this always selected by IOMMU for the VIA workaround
604 Support for software bounce buffers used on x86-64 systems
605 which don't have a hardware IOMMU (e.g. the current generation
606 of Intel's x86-64 CPUs). Using this PCI devices which can only
607 access 32-bits of memory can be used on systems with more than
608 3 GB of memory. If unsure, say Y.
611 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
614 def_bool (AMD_IOMMU || DMAR)
617 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
618 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
619 select CPUMASK_OFFSTACK
622 Configure maximum number of CPUS and NUMA Nodes for this architecture.
626 int "Maximum number of CPUs" if SMP && !MAXSMP
627 range 2 512 if SMP && !MAXSMP
629 default "4096" if MAXSMP
630 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
633 This allows you to specify the maximum number of CPUs which this
634 kernel will support. The maximum supported value is 512 and the
635 minimum value which makes sense is 2.
637 This is purely to save memory - each supported CPU adds
638 approximately eight kilobytes to the kernel image.
641 bool "SMT (Hyperthreading) scheduler support"
644 SMT scheduler support improves the CPU scheduler's decision making
645 when dealing with Intel Pentium 4 chips with HyperThreading at a
646 cost of slightly increased overhead in some places. If unsure say
651 prompt "Multi-core scheduler support"
654 Multi-core scheduler support improves the CPU scheduler's decision
655 making when dealing with multi-core CPU chips at a cost of slightly
656 increased overhead in some places. If unsure say N here.
658 source "kernel/Kconfig.preempt"
661 bool "Local APIC support on uniprocessors"
662 depends on X86_32 && !SMP && !X86_GENERICARCH
664 A local APIC (Advanced Programmable Interrupt Controller) is an
665 integrated interrupt controller in the CPU. If you have a single-CPU
666 system which has a processor with a local APIC, you can say Y here to
667 enable and use it. If you say Y here even though your machine doesn't
668 have a local APIC, then the kernel will still run with no slowdown at
669 all. The local APIC supports CPU-generated self-interrupts (timer,
670 performance counters), and the NMI watchdog which detects hard
674 bool "IO-APIC support on uniprocessors"
675 depends on X86_UP_APIC
677 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
678 SMP-capable replacement for PC-style interrupt controllers. Most
679 SMP systems and many recent uniprocessor systems have one.
681 If you have a single-CPU system with an IO-APIC, you can say Y here
682 to use it. If you say Y here even though your machine doesn't have
683 an IO-APIC, then the kernel will still run with no slowdown at all.
685 config X86_LOCAL_APIC
687 depends on X86_64 || SMP || X86_GENERICARCH || X86_UP_APIC
691 depends on X86_64 || SMP || X86_GENERICARCH || X86_UP_APIC
693 config X86_VISWS_APIC
695 depends on X86_32 && X86_VISWS
697 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
698 bool "Reroute for broken boot IRQs"
700 depends on X86_IO_APIC
702 This option enables a workaround that fixes a source of
703 spurious interrupts. This is recommended when threaded
704 interrupt handling is used on systems where the generation of
705 superfluous "boot interrupts" cannot be disabled.
707 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
708 entry in the chipset's IO-APIC is masked (as, e.g. the RT
709 kernel does during interrupt handling). On chipsets where this
710 boot IRQ generation cannot be disabled, this workaround keeps
711 the original IRQ line masked so that only the equivalent "boot
712 IRQ" is delivered to the CPUs. The workaround also tells the
713 kernel to set up the IRQ handler on the boot IRQ line. In this
714 way only one interrupt is delivered to the kernel. Otherwise
715 the spurious second interrupt may cause the kernel to bring
716 down (vital) interrupt lines.
718 Only affects "broken" chipsets. Interrupt sharing may be
719 increased on these systems.
722 bool "Machine Check Exception"
724 Machine Check Exception support allows the processor to notify the
725 kernel if it detects a problem (e.g. overheating, component failure).
726 The action the kernel takes depends on the severity of the problem,
727 ranging from a warning message on the console, to halting the machine.
728 Your processor must be a Pentium or newer to support this - check the
729 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
730 have a design flaw which leads to false MCE events - hence MCE is
731 disabled on all P5 processors, unless explicitly enabled with "mce"
732 as a boot argument. Similarly, if MCE is built in and creates a
733 problem on some new non-standard machine, you can boot with "nomce"
734 to disable it. MCE support simply ignores non-MCE processors like
735 the 386 and 486, so nearly everyone can say Y here.
739 prompt "Intel MCE features"
740 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
742 Additional support for intel specific MCE features such as
747 prompt "AMD MCE features"
748 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
750 Additional support for AMD specific MCE features such as
751 the DRAM Error Threshold.
753 config X86_MCE_NONFATAL
754 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
755 depends on X86_32 && X86_MCE
757 Enabling this feature starts a timer that triggers every 5 seconds which
758 will look at the machine check registers to see if anything happened.
759 Non-fatal problems automatically get corrected (but still logged).
760 Disable this if you don't want to see these messages.
761 Seeing the messages this option prints out may be indicative of dying
762 or out-of-spec (ie, overclocked) hardware.
763 This option only does something on certain CPUs.
764 (AMD Athlon/Duron and Intel Pentium 4)
766 config X86_MCE_P4THERMAL
767 bool "check for P4 thermal throttling interrupt."
768 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
770 Enabling this feature will cause a message to be printed when the P4
771 enters thermal throttling.
774 bool "Enable VM86 support" if EMBEDDED
778 This option is required by programs like DOSEMU to run 16-bit legacy
779 code on X86 processors. It also may be needed by software like
780 XFree86 to initialize some video cards via BIOS. Disabling this
781 option saves about 6k.
784 tristate "Toshiba Laptop support"
787 This adds a driver to safely access the System Management Mode of
788 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
789 not work on models with a Phoenix BIOS. The System Management Mode
790 is used to set the BIOS and power saving options on Toshiba portables.
792 For information on utilities to make use of this driver see the
793 Toshiba Linux utilities web site at:
794 <http://www.buzzard.org.uk/toshiba/>.
796 Say Y if you intend to run this kernel on a Toshiba portable.
800 tristate "Dell laptop support"
802 This adds a driver to safely access the System Management Mode
803 of the CPU on the Dell Inspiron 8000. The System Management Mode
804 is used to read cpu temperature and cooling fan status and to
805 control the fans on the I8K portables.
807 This driver has been tested only on the Inspiron 8000 but it may
808 also work with other Dell laptops. You can force loading on other
809 models by passing the parameter `force=1' to the module. Use at
812 For information on utilities to make use of this driver see the
813 I8K Linux utilities web site at:
814 <http://people.debian.org/~dz/i8k/>
816 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
819 config X86_REBOOTFIXUPS
820 bool "Enable X86 board specific fixups for reboot"
823 This enables chipset and/or board specific fixups to be done
824 in order to get reboot to work correctly. This is only needed on
825 some combinations of hardware and BIOS. The symptom, for which
826 this config is intended, is when reboot ends with a stalled/hung
829 Currently, the only fixup is for the Geode machines using
830 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
832 Say Y if you want to enable the fixup. Currently, it's safe to
833 enable this option even if you don't need it.
837 tristate "/dev/cpu/microcode - microcode support"
840 If you say Y here, you will be able to update the microcode on
841 certain Intel and AMD processors. The Intel support is for the
842 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
843 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
844 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
845 You will obviously need the actual microcode binary data itself
846 which is not shipped with the Linux kernel.
848 This option selects the general module only, you need to select
849 at least one vendor specific module as well.
851 To compile this driver as a module, choose M here: the
852 module will be called microcode.
854 config MICROCODE_INTEL
855 bool "Intel microcode patch loading support"
860 This options enables microcode patch loading support for Intel
863 For latest news and information on obtaining all the required
864 Intel ingredients for this driver, check:
865 <http://www.urbanmyth.org/microcode/>.
868 bool "AMD microcode patch loading support"
872 If you select this option, microcode patch loading support for AMD
873 processors will be enabled.
875 config MICROCODE_OLD_INTERFACE
880 tristate "/dev/cpu/*/msr - Model-specific register support"
882 This device gives privileged processes access to the x86
883 Model-Specific Registers (MSRs). It is a character device with
884 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
885 MSR accesses are directed to a specific CPU on multi-processor
889 tristate "/dev/cpu/*/cpuid - CPU information support"
891 This device gives processes access to the x86 CPUID instruction to
892 be executed on a specific processor. It is a character device
893 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
897 prompt "High Memory Support"
898 default HIGHMEM4G if !X86_NUMAQ
899 default HIGHMEM64G if X86_NUMAQ
904 depends on !X86_NUMAQ
906 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
907 However, the address space of 32-bit x86 processors is only 4
908 Gigabytes large. That means that, if you have a large amount of
909 physical memory, not all of it can be "permanently mapped" by the
910 kernel. The physical memory that's not permanently mapped is called
913 If you are compiling a kernel which will never run on a machine with
914 more than 1 Gigabyte total physical RAM, answer "off" here (default
915 choice and suitable for most users). This will result in a "3GB/1GB"
916 split: 3GB are mapped so that each process sees a 3GB virtual memory
917 space and the remaining part of the 4GB virtual memory space is used
918 by the kernel to permanently map as much physical memory as
921 If the machine has between 1 and 4 Gigabytes physical RAM, then
924 If more than 4 Gigabytes is used then answer "64GB" here. This
925 selection turns Intel PAE (Physical Address Extension) mode on.
926 PAE implements 3-level paging on IA32 processors. PAE is fully
927 supported by Linux, PAE mode is implemented on all recent Intel
928 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
929 then the kernel will not boot on CPUs that don't support PAE!
931 The actual amount of total physical memory will either be
932 auto detected or can be forced by using a kernel command line option
933 such as "mem=256M". (Try "man bootparam" or see the documentation of
934 your boot loader (lilo or loadlin) about how to pass options to the
935 kernel at boot time.)
937 If unsure, say "off".
941 depends on !X86_NUMAQ
943 Select this if you have a 32-bit processor and between 1 and 4
944 gigabytes of physical RAM.
948 depends on !M386 && !M486
951 Select this if you have a 32-bit processor and more than 4
952 gigabytes of physical RAM.
957 depends on EXPERIMENTAL
958 prompt "Memory split" if EMBEDDED
962 Select the desired split between kernel and user memory.
964 If the address range available to the kernel is less than the
965 physical memory installed, the remaining memory will be available
966 as "high memory". Accessing high memory is a little more costly
967 than low memory, as it needs to be mapped into the kernel first.
968 Note that increasing the kernel address space limits the range
969 available to user programs, making the address space there
970 tighter. Selecting anything other than the default 3G/1G split
971 will also likely make your kernel incompatible with binary-only
974 If you are not absolutely sure what you are doing, leave this
978 bool "3G/1G user/kernel split"
979 config VMSPLIT_3G_OPT
981 bool "3G/1G user/kernel split (for full 1G low memory)"
983 bool "2G/2G user/kernel split"
984 config VMSPLIT_2G_OPT
986 bool "2G/2G user/kernel split (for full 2G low memory)"
988 bool "1G/3G user/kernel split"
993 default 0xB0000000 if VMSPLIT_3G_OPT
994 default 0x80000000 if VMSPLIT_2G
995 default 0x78000000 if VMSPLIT_2G_OPT
996 default 0x40000000 if VMSPLIT_1G
1002 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1005 bool "PAE (Physical Address Extension) Support"
1006 depends on X86_32 && !HIGHMEM4G
1008 PAE is required for NX support, and furthermore enables
1009 larger swapspace support for non-overcommit purposes. It
1010 has the cost of more pagetable lookup overhead, and also
1011 consumes more pagetable space per process.
1013 config ARCH_PHYS_ADDR_T_64BIT
1014 def_bool X86_64 || X86_PAE
1016 config DIRECT_GBPAGES
1017 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1021 Allow the kernel linear mapping to use 1GB pages on CPUs that
1022 support it. This can improve the kernel's performance a tiny bit by
1023 reducing TLB pressure. If in doubt, say "Y".
1025 # Common NUMA Features
1027 bool "Numa Memory Allocation and Scheduler Support"
1029 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1031 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1033 Enable NUMA (Non Uniform Memory Access) support.
1035 The kernel will try to allocate memory used by a CPU on the
1036 local memory controller of the CPU and add some more
1037 NUMA awareness to the kernel.
1039 For 64-bit this is recommended if the system is Intel Core i7
1040 (or later), AMD Opteron, or EM64T NUMA.
1042 For 32-bit this is only needed on (rare) 32-bit-only platforms
1043 that support NUMA topologies, such as NUMAQ / Summit, or if you
1044 boot a 32-bit kernel on a 64-bit NUMA platform.
1046 Otherwise, you should say N.
1048 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1049 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1053 prompt "Old style AMD Opteron NUMA detection"
1054 depends on X86_64 && NUMA && PCI
1056 Enable K8 NUMA node topology detection. You should say Y here if
1057 you have a multi processor AMD K8 system. This uses an old
1058 method to read the NUMA configuration directly from the builtin
1059 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1060 instead, which also takes priority if both are compiled in.
1062 config X86_64_ACPI_NUMA
1064 prompt "ACPI NUMA detection"
1065 depends on X86_64 && NUMA && ACPI && PCI
1068 Enable ACPI SRAT based node topology detection.
1070 # Some NUMA nodes have memory ranges that span
1071 # other nodes. Even though a pfn is valid and
1072 # between a node's start and end pfns, it may not
1073 # reside on that node. See memmap_init_zone()
1075 config NODES_SPAN_OTHER_NODES
1077 depends on X86_64_ACPI_NUMA
1080 bool "NUMA emulation"
1081 depends on X86_64 && NUMA
1083 Enable NUMA emulation. A flat machine will be split
1084 into virtual nodes when booted with "numa=fake=N", where N is the
1085 number of nodes. This is only useful for debugging.
1088 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1090 default "9" if MAXSMP
1091 default "6" if X86_64
1092 default "4" if X86_NUMAQ
1094 depends on NEED_MULTIPLE_NODES
1096 Specify the maximum number of NUMA Nodes available on the target
1097 system. Increases memory reserved to accomodate various tables.
1099 config HAVE_ARCH_BOOTMEM_NODE
1101 depends on X86_32 && NUMA
1103 config ARCH_HAVE_MEMORY_PRESENT
1105 depends on X86_32 && DISCONTIGMEM
1107 config NEED_NODE_MEMMAP_SIZE
1109 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1111 config HAVE_ARCH_ALLOC_REMAP
1113 depends on X86_32 && NUMA
1115 config ARCH_FLATMEM_ENABLE
1117 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1119 config ARCH_DISCONTIGMEM_ENABLE
1121 depends on NUMA && X86_32
1123 config ARCH_DISCONTIGMEM_DEFAULT
1125 depends on NUMA && X86_32
1127 config ARCH_SPARSEMEM_DEFAULT
1131 config ARCH_SPARSEMEM_ENABLE
1133 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC) || X86_GENERICARCH
1134 select SPARSEMEM_STATIC if X86_32
1135 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1137 config ARCH_SELECT_MEMORY_MODEL
1139 depends on ARCH_SPARSEMEM_ENABLE
1141 config ARCH_MEMORY_PROBE
1143 depends on MEMORY_HOTPLUG
1148 bool "Allocate 3rd-level pagetables from highmem"
1149 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1151 The VM uses one page table entry for each page of physical memory.
1152 For systems with a lot of RAM, this can be wasteful of precious
1153 low memory. Setting this option will put user-space page table
1154 entries in high memory.
1156 config X86_CHECK_BIOS_CORRUPTION
1157 bool "Check for low memory corruption"
1159 Periodically check for memory corruption in low memory, which
1160 is suspected to be caused by BIOS. Even when enabled in the
1161 configuration, it is disabled at runtime. Enable it by
1162 setting "memory_corruption_check=1" on the kernel command
1163 line. By default it scans the low 64k of memory every 60
1164 seconds; see the memory_corruption_check_size and
1165 memory_corruption_check_period parameters in
1166 Documentation/kernel-parameters.txt to adjust this.
1168 When enabled with the default parameters, this option has
1169 almost no overhead, as it reserves a relatively small amount
1170 of memory and scans it infrequently. It both detects corruption
1171 and prevents it from affecting the running system.
1173 It is, however, intended as a diagnostic tool; if repeatable
1174 BIOS-originated corruption always affects the same memory,
1175 you can use memmap= to prevent the kernel from using that
1178 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1179 bool "Set the default setting of memory_corruption_check"
1180 depends on X86_CHECK_BIOS_CORRUPTION
1183 Set whether the default state of memory_corruption_check is
1186 config X86_RESERVE_LOW_64K
1187 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1190 Reserve the first 64K of physical RAM on BIOSes that are known
1191 to potentially corrupt that memory range. A numbers of BIOSes are
1192 known to utilize this area during suspend/resume, so it must not
1193 be used by the kernel.
1195 Set this to N if you are absolutely sure that you trust the BIOS
1196 to get all its memory reservations and usages right.
1198 If you have doubts about the BIOS (e.g. suspend/resume does not
1199 work or there's kernel crashes after certain hardware hotplug
1200 events) and it's not AMI or Phoenix, then you might want to enable
1201 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1202 corruption patterns.
1206 config MATH_EMULATION
1208 prompt "Math emulation" if X86_32
1210 Linux can emulate a math coprocessor (used for floating point
1211 operations) if you don't have one. 486DX and Pentium processors have
1212 a math coprocessor built in, 486SX and 386 do not, unless you added
1213 a 487DX or 387, respectively. (The messages during boot time can
1214 give you some hints here ["man dmesg"].) Everyone needs either a
1215 coprocessor or this emulation.
1217 If you don't have a math coprocessor, you need to say Y here; if you
1218 say Y here even though you have a coprocessor, the coprocessor will
1219 be used nevertheless. (This behavior can be changed with the kernel
1220 command line option "no387", which comes handy if your coprocessor
1221 is broken. Try "man bootparam" or see the documentation of your boot
1222 loader (lilo or loadlin) about how to pass options to the kernel at
1223 boot time.) This means that it is a good idea to say Y here if you
1224 intend to use this kernel on different machines.
1226 More information about the internals of the Linux math coprocessor
1227 emulation can be found in <file:arch/x86/math-emu/README>.
1229 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1230 kernel, it won't hurt.
1233 bool "MTRR (Memory Type Range Register) support"
1235 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1236 the Memory Type Range Registers (MTRRs) may be used to control
1237 processor access to memory ranges. This is most useful if you have
1238 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1239 allows bus write transfers to be combined into a larger transfer
1240 before bursting over the PCI/AGP bus. This can increase performance
1241 of image write operations 2.5 times or more. Saying Y here creates a
1242 /proc/mtrr file which may be used to manipulate your processor's
1243 MTRRs. Typically the X server should use this.
1245 This code has a reasonably generic interface so that similar
1246 control registers on other processors can be easily supported
1249 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1250 Registers (ARRs) which provide a similar functionality to MTRRs. For
1251 these, the ARRs are used to emulate the MTRRs.
1252 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1253 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1254 write-combining. All of these processors are supported by this code
1255 and it makes sense to say Y here if you have one of them.
1257 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1258 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1259 can lead to all sorts of problems, so it's good to say Y here.
1261 You can safely say Y even if your machine doesn't have MTRRs, you'll
1262 just add about 9 KB to your kernel.
1264 See <file:Documentation/x86/mtrr.txt> for more information.
1266 config MTRR_SANITIZER
1268 prompt "MTRR cleanup support"
1271 Convert MTRR layout from continuous to discrete, so X drivers can
1272 add writeback entries.
1274 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1275 The largest mtrr entry size for a continous block can be set with
1280 config MTRR_SANITIZER_ENABLE_DEFAULT
1281 int "MTRR cleanup enable value (0-1)"
1284 depends on MTRR_SANITIZER
1286 Enable mtrr cleanup default value
1288 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1289 int "MTRR cleanup spare reg num (0-7)"
1292 depends on MTRR_SANITIZER
1294 mtrr cleanup spare entries default, it can be changed via
1295 mtrr_spare_reg_nr=N on the kernel command line.
1299 prompt "x86 PAT support"
1302 Use PAT attributes to setup page level cache control.
1304 PATs are the modern equivalents of MTRRs and are much more
1305 flexible than MTRRs.
1307 Say N here if you see bootup problems (boot crash, boot hang,
1308 spontaneous reboots) or a non-working video driver.
1313 bool "EFI runtime service support"
1316 This enables the kernel to use EFI runtime services that are
1317 available (such as the EFI variable services).
1319 This option is only useful on systems that have EFI firmware.
1320 In addition, you should use the latest ELILO loader available
1321 at <http://elilo.sourceforge.net> in order to take advantage
1322 of EFI runtime services. However, even with this option, the
1323 resultant kernel should continue to boot on existing non-EFI
1328 prompt "Enable seccomp to safely compute untrusted bytecode"
1330 This kernel feature is useful for number crunching applications
1331 that may need to compute untrusted bytecode during their
1332 execution. By using pipes or other transports made available to
1333 the process as file descriptors supporting the read/write
1334 syscalls, it's possible to isolate those applications in
1335 their own address space using seccomp. Once seccomp is
1336 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1337 and the task is only allowed to execute a few safe syscalls
1338 defined by each seccomp mode.
1340 If unsure, say Y. Only embedded should say N here.
1342 config CC_STACKPROTECTOR_ALL
1345 config CC_STACKPROTECTOR
1346 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1348 select CC_STACKPROTECTOR_ALL
1350 This option turns on the -fstack-protector GCC feature. This
1351 feature puts, at the beginning of functions, a canary value on
1352 the stack just before the return address, and validates
1353 the value just before actually returning. Stack based buffer
1354 overflows (that need to overwrite this return address) now also
1355 overwrite the canary, which gets detected and the attack is then
1356 neutralized via a kernel panic.
1358 This feature requires gcc version 4.2 or above, or a distribution
1359 gcc with the feature backported. Older versions are automatically
1360 detected and for those versions, this configuration option is
1361 ignored. (and a warning is printed during bootup)
1363 source kernel/Kconfig.hz
1366 bool "kexec system call"
1368 kexec is a system call that implements the ability to shutdown your
1369 current kernel, and to start another kernel. It is like a reboot
1370 but it is independent of the system firmware. And like a reboot
1371 you can start any kernel with it, not just Linux.
1373 The name comes from the similarity to the exec system call.
1375 It is an ongoing process to be certain the hardware in a machine
1376 is properly shutdown, so do not be surprised if this code does not
1377 initially work for you. It may help to enable device hotplugging
1378 support. As of this writing the exact hardware interface is
1379 strongly in flux, so no good recommendation can be made.
1382 bool "kernel crash dumps"
1383 depends on X86_64 || (X86_32 && HIGHMEM)
1385 Generate crash dump after being started by kexec.
1386 This should be normally only set in special crash dump kernels
1387 which are loaded in the main kernel with kexec-tools into
1388 a specially reserved region and then later executed after
1389 a crash by kdump/kexec. The crash dump kernel must be compiled
1390 to a memory address not used by the main kernel or BIOS using
1391 PHYSICAL_START, or it must be built as a relocatable image
1392 (CONFIG_RELOCATABLE=y).
1393 For more details see Documentation/kdump/kdump.txt
1396 bool "kexec jump (EXPERIMENTAL)"
1397 depends on EXPERIMENTAL
1398 depends on KEXEC && HIBERNATION && X86_32
1400 Jump between original kernel and kexeced kernel and invoke
1401 code in physical address mode via KEXEC
1403 config PHYSICAL_START
1404 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1405 default "0x1000000" if X86_NUMAQ
1406 default "0x200000" if X86_64
1409 This gives the physical address where the kernel is loaded.
1411 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1412 bzImage will decompress itself to above physical address and
1413 run from there. Otherwise, bzImage will run from the address where
1414 it has been loaded by the boot loader and will ignore above physical
1417 In normal kdump cases one does not have to set/change this option
1418 as now bzImage can be compiled as a completely relocatable image
1419 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1420 address. This option is mainly useful for the folks who don't want
1421 to use a bzImage for capturing the crash dump and want to use a
1422 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1423 to be specifically compiled to run from a specific memory area
1424 (normally a reserved region) and this option comes handy.
1426 So if you are using bzImage for capturing the crash dump, leave
1427 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1428 Otherwise if you plan to use vmlinux for capturing the crash dump
1429 change this value to start of the reserved region (Typically 16MB
1430 0x1000000). In other words, it can be set based on the "X" value as
1431 specified in the "crashkernel=YM@XM" command line boot parameter
1432 passed to the panic-ed kernel. Typically this parameter is set as
1433 crashkernel=64M@16M. Please take a look at
1434 Documentation/kdump/kdump.txt for more details about crash dumps.
1436 Usage of bzImage for capturing the crash dump is recommended as
1437 one does not have to build two kernels. Same kernel can be used
1438 as production kernel and capture kernel. Above option should have
1439 gone away after relocatable bzImage support is introduced. But it
1440 is present because there are users out there who continue to use
1441 vmlinux for dump capture. This option should go away down the
1444 Don't change this unless you know what you are doing.
1447 bool "Build a relocatable kernel (EXPERIMENTAL)"
1448 depends on EXPERIMENTAL
1450 This builds a kernel image that retains relocation information
1451 so it can be loaded someplace besides the default 1MB.
1452 The relocations tend to make the kernel binary about 10% larger,
1453 but are discarded at runtime.
1455 One use is for the kexec on panic case where the recovery kernel
1456 must live at a different physical address than the primary
1459 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1460 it has been loaded at and the compile time physical address
1461 (CONFIG_PHYSICAL_START) is ignored.
1463 config PHYSICAL_ALIGN
1465 prompt "Alignment value to which kernel should be aligned" if X86_32
1466 default "0x100000" if X86_32
1467 default "0x200000" if X86_64
1468 range 0x2000 0x400000
1470 This value puts the alignment restrictions on physical address
1471 where kernel is loaded and run from. Kernel is compiled for an
1472 address which meets above alignment restriction.
1474 If bootloader loads the kernel at a non-aligned address and
1475 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1476 address aligned to above value and run from there.
1478 If bootloader loads the kernel at a non-aligned address and
1479 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1480 load address and decompress itself to the address it has been
1481 compiled for and run from there. The address for which kernel is
1482 compiled already meets above alignment restrictions. Hence the
1483 end result is that kernel runs from a physical address meeting
1484 above alignment restrictions.
1486 Don't change this unless you know what you are doing.
1489 bool "Support for hot-pluggable CPUs"
1490 depends on SMP && HOTPLUG
1492 Say Y here to allow turning CPUs off and on. CPUs can be
1493 controlled through /sys/devices/system/cpu.
1494 ( Note: power management support will enable this option
1495 automatically on SMP systems. )
1496 Say N if you want to disable CPU hotplug.
1500 prompt "Compat VDSO support"
1501 depends on X86_32 || IA32_EMULATION
1503 Map the 32-bit VDSO to the predictable old-style address too.
1505 Say N here if you are running a sufficiently recent glibc
1506 version (2.3.3 or later), to remove the high-mapped
1507 VDSO mapping and to exclusively use the randomized VDSO.
1512 bool "Built-in kernel command line"
1515 Allow for specifying boot arguments to the kernel at
1516 build time. On some systems (e.g. embedded ones), it is
1517 necessary or convenient to provide some or all of the
1518 kernel boot arguments with the kernel itself (that is,
1519 to not rely on the boot loader to provide them.)
1521 To compile command line arguments into the kernel,
1522 set this option to 'Y', then fill in the
1523 the boot arguments in CONFIG_CMDLINE.
1525 Systems with fully functional boot loaders (i.e. non-embedded)
1526 should leave this option set to 'N'.
1529 string "Built-in kernel command string"
1530 depends on CMDLINE_BOOL
1533 Enter arguments here that should be compiled into the kernel
1534 image and used at boot time. If the boot loader provides a
1535 command line at boot time, it is appended to this string to
1536 form the full kernel command line, when the system boots.
1538 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1539 change this behavior.
1541 In most cases, the command line (whether built-in or provided
1542 by the boot loader) should specify the device for the root
1545 config CMDLINE_OVERRIDE
1546 bool "Built-in command line overrides boot loader arguments"
1548 depends on CMDLINE_BOOL
1550 Set this option to 'Y' to have the kernel ignore the boot loader
1551 command line, and use ONLY the built-in command line.
1553 This is used to work around broken boot loaders. This should
1554 be set to 'N' under normal conditions.
1558 config ARCH_ENABLE_MEMORY_HOTPLUG
1560 depends on X86_64 || (X86_32 && HIGHMEM)
1562 config ARCH_ENABLE_MEMORY_HOTREMOVE
1564 depends on MEMORY_HOTPLUG
1566 config HAVE_ARCH_EARLY_PFN_TO_NID
1570 menu "Power management and ACPI options"
1572 config ARCH_HIBERNATION_HEADER
1574 depends on X86_64 && HIBERNATION
1576 source "kernel/power/Kconfig"
1578 source "drivers/acpi/Kconfig"
1583 depends on APM || APM_MODULE
1586 tristate "APM (Advanced Power Management) BIOS support"
1587 depends on X86_32 && PM_SLEEP
1589 APM is a BIOS specification for saving power using several different
1590 techniques. This is mostly useful for battery powered laptops with
1591 APM compliant BIOSes. If you say Y here, the system time will be
1592 reset after a RESUME operation, the /proc/apm device will provide
1593 battery status information, and user-space programs will receive
1594 notification of APM "events" (e.g. battery status change).
1596 If you select "Y" here, you can disable actual use of the APM
1597 BIOS by passing the "apm=off" option to the kernel at boot time.
1599 Note that the APM support is almost completely disabled for
1600 machines with more than one CPU.
1602 In order to use APM, you will need supporting software. For location
1603 and more information, read <file:Documentation/power/pm.txt> and the
1604 Battery Powered Linux mini-HOWTO, available from
1605 <http://www.tldp.org/docs.html#howto>.
1607 This driver does not spin down disk drives (see the hdparm(8)
1608 manpage ("man 8 hdparm") for that), and it doesn't turn off
1609 VESA-compliant "green" monitors.
1611 This driver does not support the TI 4000M TravelMate and the ACER
1612 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1613 desktop machines also don't have compliant BIOSes, and this driver
1614 may cause those machines to panic during the boot phase.
1616 Generally, if you don't have a battery in your machine, there isn't
1617 much point in using this driver and you should say N. If you get
1618 random kernel OOPSes or reboots that don't seem to be related to
1619 anything, try disabling/enabling this option (or disabling/enabling
1622 Some other things you should try when experiencing seemingly random,
1625 1) make sure that you have enough swap space and that it is
1627 2) pass the "no-hlt" option to the kernel
1628 3) switch on floating point emulation in the kernel and pass
1629 the "no387" option to the kernel
1630 4) pass the "floppy=nodma" option to the kernel
1631 5) pass the "mem=4M" option to the kernel (thereby disabling
1632 all but the first 4 MB of RAM)
1633 6) make sure that the CPU is not over clocked.
1634 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1635 8) disable the cache from your BIOS settings
1636 9) install a fan for the video card or exchange video RAM
1637 10) install a better fan for the CPU
1638 11) exchange RAM chips
1639 12) exchange the motherboard.
1641 To compile this driver as a module, choose M here: the
1642 module will be called apm.
1646 config APM_IGNORE_USER_SUSPEND
1647 bool "Ignore USER SUSPEND"
1649 This option will ignore USER SUSPEND requests. On machines with a
1650 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1651 series notebooks, it is necessary to say Y because of a BIOS bug.
1653 config APM_DO_ENABLE
1654 bool "Enable PM at boot time"
1656 Enable APM features at boot time. From page 36 of the APM BIOS
1657 specification: "When disabled, the APM BIOS does not automatically
1658 power manage devices, enter the Standby State, enter the Suspend
1659 State, or take power saving steps in response to CPU Idle calls."
1660 This driver will make CPU Idle calls when Linux is idle (unless this
1661 feature is turned off -- see "Do CPU IDLE calls", below). This
1662 should always save battery power, but more complicated APM features
1663 will be dependent on your BIOS implementation. You may need to turn
1664 this option off if your computer hangs at boot time when using APM
1665 support, or if it beeps continuously instead of suspending. Turn
1666 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1667 T400CDT. This is off by default since most machines do fine without
1671 bool "Make CPU Idle calls when idle"
1673 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1674 On some machines, this can activate improved power savings, such as
1675 a slowed CPU clock rate, when the machine is idle. These idle calls
1676 are made after the idle loop has run for some length of time (e.g.,
1677 333 mS). On some machines, this will cause a hang at boot time or
1678 whenever the CPU becomes idle. (On machines with more than one CPU,
1679 this option does nothing.)
1681 config APM_DISPLAY_BLANK
1682 bool "Enable console blanking using APM"
1684 Enable console blanking using the APM. Some laptops can use this to
1685 turn off the LCD backlight when the screen blanker of the Linux
1686 virtual console blanks the screen. Note that this is only used by
1687 the virtual console screen blanker, and won't turn off the backlight
1688 when using the X Window system. This also doesn't have anything to
1689 do with your VESA-compliant power-saving monitor. Further, this
1690 option doesn't work for all laptops -- it might not turn off your
1691 backlight at all, or it might print a lot of errors to the console,
1692 especially if you are using gpm.
1694 config APM_ALLOW_INTS
1695 bool "Allow interrupts during APM BIOS calls"
1697 Normally we disable external interrupts while we are making calls to
1698 the APM BIOS as a measure to lessen the effects of a badly behaving
1699 BIOS implementation. The BIOS should reenable interrupts if it
1700 needs to. Unfortunately, some BIOSes do not -- especially those in
1701 many of the newer IBM Thinkpads. If you experience hangs when you
1702 suspend, try setting this to Y. Otherwise, say N.
1706 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1708 source "drivers/cpuidle/Kconfig"
1710 source "drivers/idle/Kconfig"
1715 menu "Bus options (PCI etc.)"
1720 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1722 Find out whether you have a PCI motherboard. PCI is the name of a
1723 bus system, i.e. the way the CPU talks to the other stuff inside
1724 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1725 VESA. If you have PCI, say Y, otherwise N.
1728 prompt "PCI access mode"
1729 depends on X86_32 && PCI
1732 On PCI systems, the BIOS can be used to detect the PCI devices and
1733 determine their configuration. However, some old PCI motherboards
1734 have BIOS bugs and may crash if this is done. Also, some embedded
1735 PCI-based systems don't have any BIOS at all. Linux can also try to
1736 detect the PCI hardware directly without using the BIOS.
1738 With this option, you can specify how Linux should detect the
1739 PCI devices. If you choose "BIOS", the BIOS will be used,
1740 if you choose "Direct", the BIOS won't be used, and if you
1741 choose "MMConfig", then PCI Express MMCONFIG will be used.
1742 If you choose "Any", the kernel will try MMCONFIG, then the
1743 direct access method and falls back to the BIOS if that doesn't
1744 work. If unsure, go with the default, which is "Any".
1749 config PCI_GOMMCONFIG
1766 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1768 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1771 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1775 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1779 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1786 bool "Support mmconfig PCI config space access"
1787 depends on X86_64 && PCI && ACPI
1790 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1791 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1793 DMA remapping (DMAR) devices support enables independent address
1794 translations for Direct Memory Access (DMA) from devices.
1795 These DMA remapping devices are reported via ACPI tables
1796 and include PCI device scope covered by these DMA
1801 prompt "Support for Graphics workaround"
1804 Current Graphics drivers tend to use physical address
1805 for DMA and avoid using DMA APIs. Setting this config
1806 option permits the IOMMU driver to set a unity map for
1807 all the OS-visible memory. Hence the driver can continue
1808 to use physical addresses for DMA.
1810 config DMAR_FLOPPY_WA
1814 Floppy disk drivers are know to bypass DMA API calls
1815 thereby failing to work when IOMMU is enabled. This
1816 workaround will setup a 1:1 mapping for the first
1817 16M to make floppy (an ISA device) work.
1820 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1821 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1823 Supports Interrupt remapping for IO-APIC and MSI devices.
1824 To use x2apic mode in the CPU's which support x2APIC enhancements or
1825 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1827 source "drivers/pci/pcie/Kconfig"
1829 source "drivers/pci/Kconfig"
1831 # x86_64 have no ISA slots, but do have ISA-style DMA.
1840 Find out whether you have ISA slots on your motherboard. ISA is the
1841 name of a bus system, i.e. the way the CPU talks to the other stuff
1842 inside your box. Other bus systems are PCI, EISA, MicroChannel
1843 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1844 newer boards don't support it. If you have ISA, say Y, otherwise N.
1850 The Extended Industry Standard Architecture (EISA) bus was
1851 developed as an open alternative to the IBM MicroChannel bus.
1853 The EISA bus provided some of the features of the IBM MicroChannel
1854 bus while maintaining backward compatibility with cards made for
1855 the older ISA bus. The EISA bus saw limited use between 1988 and
1856 1995 when it was made obsolete by the PCI bus.
1858 Say Y here if you are building a kernel for an EISA-based machine.
1862 source "drivers/eisa/Kconfig"
1867 MicroChannel Architecture is found in some IBM PS/2 machines and
1868 laptops. It is a bus system similar to PCI or ISA. See
1869 <file:Documentation/mca.txt> (and especially the web page given
1870 there) before attempting to build an MCA bus kernel.
1872 source "drivers/mca/Kconfig"
1875 tristate "NatSemi SCx200 support"
1877 This provides basic support for National Semiconductor's
1878 (now AMD's) Geode processors. The driver probes for the
1879 PCI-IDs of several on-chip devices, so its a good dependency
1880 for other scx200_* drivers.
1882 If compiled as a module, the driver is named scx200.
1884 config SCx200HR_TIMER
1885 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1886 depends on SCx200 && GENERIC_TIME
1889 This driver provides a clocksource built upon the on-chip
1890 27MHz high-resolution timer. Its also a workaround for
1891 NSC Geode SC-1100's buggy TSC, which loses time when the
1892 processor goes idle (as is done by the scheduler). The
1893 other workaround is idle=poll boot option.
1895 config GEODE_MFGPT_TIMER
1897 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1898 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1900 This driver provides a clock event source based on the MFGPT
1901 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1902 MFGPTs have a better resolution and max interval than the
1903 generic PIT, and are suitable for use as high-res timers.
1906 bool "One Laptop Per Child support"
1909 Add support for detecting the unique features of the OLPC
1916 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1918 source "drivers/pcmcia/Kconfig"
1920 source "drivers/pci/hotplug/Kconfig"
1925 menu "Executable file formats / Emulations"
1927 source "fs/Kconfig.binfmt"
1929 config IA32_EMULATION
1930 bool "IA32 Emulation"
1932 select COMPAT_BINFMT_ELF
1934 Include code to run 32-bit programs under a 64-bit kernel. You should
1935 likely turn this on, unless you're 100% sure that you don't have any
1936 32-bit programs left.
1939 tristate "IA32 a.out support"
1940 depends on IA32_EMULATION
1942 Support old a.out binaries in the 32bit emulation.
1946 depends on IA32_EMULATION
1948 config COMPAT_FOR_U64_ALIGNMENT
1952 config SYSVIPC_COMPAT
1954 depends on COMPAT && SYSVIPC
1959 config HAVE_ATOMIC_IOMAP
1963 source "net/Kconfig"
1965 source "drivers/Kconfig"
1967 source "drivers/firmware/Kconfig"
1971 source "arch/x86/Kconfig.debug"
1973 source "security/Kconfig"
1975 source "crypto/Kconfig"
1977 source "arch/x86/kvm/Kconfig"
1979 source "lib/Kconfig"
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