2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
21 select HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
27 select HAVE_IOREMAP_PROT
29 select ARCH_WANT_OPTIONAL_GPIOLIB
30 select HAVE_KRETPROBES
31 select HAVE_FTRACE_MCOUNT_RECORD
32 select HAVE_DYNAMIC_FTRACE
33 select HAVE_FUNCTION_TRACER
34 select HAVE_FUNCTION_GRAPH_TRACER
35 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
36 select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
37 select HAVE_ARCH_KGDB if !X86_VOYAGER
38 select HAVE_ARCH_TRACEHOOK
39 select HAVE_GENERIC_DMA_COHERENT if X86_32
40 select HAVE_EFFICIENT_UNALIGNED_ACCESS
41 select USER_STACKTRACE_SUPPORT
45 default "arch/x86/configs/i386_defconfig" if X86_32
46 default "arch/x86/configs/x86_64_defconfig" if X86_64
51 config GENERIC_CMOS_UPDATE
54 config CLOCKSOURCE_WATCHDOG
57 config GENERIC_CLOCKEVENTS
60 config GENERIC_CLOCKEVENTS_BROADCAST
62 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
64 config LOCKDEP_SUPPORT
67 config STACKTRACE_SUPPORT
70 config HAVE_LATENCYTOP_SUPPORT
73 config FAST_CMPXCHG_LOCAL
86 config GENERIC_ISA_DMA
95 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
97 config GENERIC_BUG_RELATIVE_POINTERS
100 config GENERIC_HWEIGHT
106 config ARCH_MAY_HAVE_PC_FDC
109 config RWSEM_GENERIC_SPINLOCK
112 config RWSEM_XCHGADD_ALGORITHM
115 config ARCH_HAS_CPU_IDLE_WAIT
118 config GENERIC_CALIBRATE_DELAY
121 config GENERIC_TIME_VSYSCALL
125 config ARCH_HAS_CPU_RELAX
128 config ARCH_HAS_DEFAULT_IDLE
131 config ARCH_HAS_CACHE_LINE_SIZE
134 config HAVE_SETUP_PER_CPU_AREA
135 def_bool X86_64_SMP || (X86_SMP && !X86_VOYAGER)
137 config HAVE_CPUMASK_OF_CPU_MAP
140 config ARCH_HIBERNATION_POSSIBLE
142 depends on !SMP || !X86_VOYAGER
144 config ARCH_SUSPEND_POSSIBLE
146 depends on !X86_VOYAGER
152 config ARCH_POPULATES_NODE_MAP
159 config ARCH_SUPPORTS_OPTIMIZED_INLINING
162 # Use the generic interrupt handling code in kernel/irq/:
163 config GENERIC_HARDIRQS
167 config GENERIC_IRQ_PROBE
171 config GENERIC_PENDING_IRQ
173 depends on GENERIC_HARDIRQS && SMP
178 depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
181 config USE_GENERIC_SMP_HELPERS
187 depends on X86_32 && SMP
191 depends on X86_64 && SMP
196 depends on (X86_32 && !X86_VOYAGER) || X86_64
199 config X86_BIOS_REBOOT
201 depends on !X86_VOYAGER
204 config X86_TRAMPOLINE
206 depends on X86_SMP || (X86_VOYAGER && SMP) || (64BIT && ACPI_SLEEP)
211 source "init/Kconfig"
212 source "kernel/Kconfig.freezer"
214 menu "Processor type and features"
216 source "kernel/time/Kconfig"
219 bool "Symmetric multi-processing support"
221 This enables support for systems with more than one CPU. If you have
222 a system with only one CPU, like most personal computers, say N. If
223 you have a system with more than one CPU, say Y.
225 If you say N here, the kernel will run on single and multiprocessor
226 machines, but will use only one CPU of a multiprocessor machine. If
227 you say Y here, the kernel will run on many, but not all,
228 singleprocessor machines. On a singleprocessor machine, the kernel
229 will run faster if you say N here.
231 Note that if you say Y here and choose architecture "586" or
232 "Pentium" under "Processor family", the kernel will not work on 486
233 architectures. Similarly, multiprocessor kernels for the "PPro"
234 architecture may not work on all Pentium based boards.
236 People using multiprocessor machines who say Y here should also say
237 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
238 Management" code will be disabled if you say Y here.
240 See also <file:Documentation/i386/IO-APIC.txt>,
241 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
242 <http://www.tldp.org/docs.html#howto>.
244 If you don't know what to do here, say N.
246 config X86_HAS_BOOT_CPU_ID
248 depends on X86_VOYAGER
251 bool "Support sparse irq numbering"
252 depends on PCI_MSI || HT_IRQ
254 This enables support for sparse irqs. This is useful for distro
255 kernels that want to define a high CONFIG_NR_CPUS value but still
256 want to have low kernel memory footprint on smaller machines.
258 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
259 out the irq_desc[] array in a more NUMA-friendly way. )
261 If you don't know what to do here, say N.
263 config NUMA_MIGRATE_IRQ_DESC
264 bool "Move irq desc when changing irq smp_affinity"
265 depends on SPARSE_IRQ && NUMA
268 This enables moving irq_desc to cpu/node that irq will use handled.
270 If you don't know what to do here, say N.
272 config X86_FIND_SMP_CONFIG
274 depends on X86_MPPARSE || X86_VOYAGER
277 bool "Enable MPS table" if ACPI
279 depends on X86_LOCAL_APIC
281 For old smp systems that do not have proper acpi support. Newer systems
282 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
285 prompt "Subarchitecture Type"
291 Choose this option if your computer is a standard PC or compatible.
297 Select this for an AMD Elan processor.
299 Do not use this option for K6/Athlon/Opteron processors!
301 If unsure, choose "PC-compatible" instead.
305 depends on X86_32 && (SMP || BROKEN) && !PCI
307 Voyager is an MCA-based 32-way capable SMP architecture proprietary
308 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
312 If you do not specifically know you have a Voyager based machine,
313 say N here, otherwise the kernel you build will not be bootable.
315 config X86_GENERICARCH
316 bool "Generic architecture"
319 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
320 subarchitectures. It is intended for a generic binary kernel.
321 if you select them all, kernel will probe it one by one. and will
327 bool "NUMAQ (IBM/Sequent)"
328 depends on SMP && X86_32 && PCI && X86_MPPARSE
331 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
332 NUMA multiquad box. This changes the way that processors are
333 bootstrapped, and uses Clustered Logical APIC addressing mode instead
334 of Flat Logical. You will need a new lynxer.elf file to flash your
335 firmware with - send email to <Martin.Bligh@us.ibm.com>.
338 bool "Summit/EXA (IBM x440)"
339 depends on X86_32 && SMP
341 This option is needed for IBM systems that use the Summit/EXA chipset.
342 In particular, it is needed for the x440.
345 bool "Support for Unisys ES7000 IA32 series"
346 depends on X86_32 && SMP
348 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
349 supposed to run on an IA32-based Unisys ES7000 system.
352 bool "Support for big SMP systems with more than 8 CPUs"
353 depends on X86_32 && SMP
355 This option is needed for the systems that have more than 8 CPUs
356 and if the system is not of any sub-arch type above.
361 bool "Support for ScaleMP vSMP"
363 depends on X86_64 && PCI
365 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
366 supposed to run on these EM64T-based machines. Only choose this option
367 if you have one of these machines.
372 bool "SGI 320/540 (Visual Workstation)"
373 depends on X86_32 && PCI && !X86_VOYAGER && X86_MPPARSE && PCI_GODIRECT
375 The SGI Visual Workstation series is an IA32-based workstation
376 based on SGI systems chips with some legacy PC hardware attached.
378 Say Y here to create a kernel to run on the SGI 320 or 540.
380 A kernel compiled for the Visual Workstation will run on general
381 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
384 bool "RDC R-321x SoC"
387 select X86_REBOOTFIXUPS
389 This option is needed for RDC R-321x system-on-chip, also known
391 If you don't have one of these chips, you should say N here.
393 config SCHED_OMIT_FRAME_POINTER
395 prompt "Single-depth WCHAN output"
398 Calculate simpler /proc/<PID>/wchan values. If this option
399 is disabled then wchan values will recurse back to the
400 caller function. This provides more accurate wchan values,
401 at the expense of slightly more scheduling overhead.
403 If in doubt, say "Y".
405 menuconfig PARAVIRT_GUEST
406 bool "Paravirtualized guest support"
408 Say Y here to get to see options related to running Linux under
409 various hypervisors. This option alone does not add any kernel code.
411 If you say N, all options in this submenu will be skipped and disabled.
415 source "arch/x86/xen/Kconfig"
418 bool "VMI Guest support"
421 depends on !X86_VOYAGER
423 VMI provides a paravirtualized interface to the VMware ESX server
424 (it could be used by other hypervisors in theory too, but is not
425 at the moment), by linking the kernel to a GPL-ed ROM module
426 provided by the hypervisor.
429 bool "KVM paravirtualized clock"
431 select PARAVIRT_CLOCK
432 depends on !X86_VOYAGER
434 Turning on this option will allow you to run a paravirtualized clock
435 when running over the KVM hypervisor. Instead of relying on a PIT
436 (or probably other) emulation by the underlying device model, the host
437 provides the guest with timing infrastructure such as time of day, and
441 bool "KVM Guest support"
443 depends on !X86_VOYAGER
445 This option enables various optimizations for running under the KVM
448 source "arch/x86/lguest/Kconfig"
451 bool "Enable paravirtualization code"
452 depends on !X86_VOYAGER
454 This changes the kernel so it can modify itself when it is run
455 under a hypervisor, potentially improving performance significantly
456 over full virtualization. However, when run without a hypervisor
457 the kernel is theoretically slower and slightly larger.
459 config PARAVIRT_CLOCK
465 config PARAVIRT_DEBUG
466 bool "paravirt-ops debugging"
467 depends on PARAVIRT && DEBUG_KERNEL
469 Enable to debug paravirt_ops internals. Specifically, BUG if
470 a paravirt_op is missing when it is called.
475 This option adds a kernel parameter 'memtest', which allows memtest
477 memtest=0, mean disabled; -- default
478 memtest=1, mean do 1 test pattern;
480 memtest=4, mean do 4 test patterns.
481 If you are unsure how to answer this question, answer N.
483 config X86_SUMMIT_NUMA
485 depends on X86_32 && NUMA && X86_GENERICARCH
487 config X86_CYCLONE_TIMER
489 depends on X86_GENERICARCH
491 source "arch/x86/Kconfig.cpu"
495 prompt "HPET Timer Support" if X86_32
497 Use the IA-PC HPET (High Precision Event Timer) to manage
498 time in preference to the PIT and RTC, if a HPET is
500 HPET is the next generation timer replacing legacy 8254s.
501 The HPET provides a stable time base on SMP
502 systems, unlike the TSC, but it is more expensive to access,
503 as it is off-chip. You can find the HPET spec at
504 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
506 You can safely choose Y here. However, HPET will only be
507 activated if the platform and the BIOS support this feature.
508 Otherwise the 8254 will be used for timing services.
510 Choose N to continue using the legacy 8254 timer.
512 config HPET_EMULATE_RTC
514 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
516 # Mark as embedded because too many people got it wrong.
517 # The code disables itself when not needed.
520 bool "Enable DMI scanning" if EMBEDDED
522 Enabled scanning of DMI to identify machine quirks. Say Y
523 here unless you have verified that your setup is not
524 affected by entries in the DMI blacklist. Required by PNP
528 bool "GART IOMMU support" if EMBEDDED
532 depends on X86_64 && PCI
534 Support for full DMA access of devices with 32bit memory access only
535 on systems with more than 3GB. This is usually needed for USB,
536 sound, many IDE/SATA chipsets and some other devices.
537 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
538 based hardware IOMMU and a software bounce buffer based IOMMU used
539 on Intel systems and as fallback.
540 The code is only active when needed (enough memory and limited
541 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
545 bool "IBM Calgary IOMMU support"
547 depends on X86_64 && PCI && EXPERIMENTAL
549 Support for hardware IOMMUs in IBM's xSeries x366 and x460
550 systems. Needed to run systems with more than 3GB of memory
551 properly with 32-bit PCI devices that do not support DAC
552 (Double Address Cycle). Calgary also supports bus level
553 isolation, where all DMAs pass through the IOMMU. This
554 prevents them from going anywhere except their intended
555 destination. This catches hard-to-find kernel bugs and
556 mis-behaving drivers and devices that do not use the DMA-API
557 properly to set up their DMA buffers. The IOMMU can be
558 turned off at boot time with the iommu=off parameter.
559 Normally the kernel will make the right choice by itself.
562 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
564 prompt "Should Calgary be enabled by default?"
565 depends on CALGARY_IOMMU
567 Should Calgary be enabled by default? if you choose 'y', Calgary
568 will be used (if it exists). If you choose 'n', Calgary will not be
569 used even if it exists. If you choose 'n' and would like to use
570 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
574 bool "AMD IOMMU support"
577 depends on X86_64 && PCI && ACPI
579 With this option you can enable support for AMD IOMMU hardware in
580 your system. An IOMMU is a hardware component which provides
581 remapping of DMA memory accesses from devices. With an AMD IOMMU you
582 can isolate the the DMA memory of different devices and protect the
583 system from misbehaving device drivers or hardware.
585 You can find out if your system has an AMD IOMMU if you look into
586 your BIOS for an option to enable it or if you have an IVRS ACPI
589 # need this always selected by IOMMU for the VIA workaround
593 Support for software bounce buffers used on x86-64 systems
594 which don't have a hardware IOMMU (e.g. the current generation
595 of Intel's x86-64 CPUs). Using this PCI devices which can only
596 access 32-bits of memory can be used on systems with more than
597 3 GB of memory. If unsure, say Y.
600 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
603 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
604 depends on X86_64 && SMP && BROKEN
607 Configure maximum number of CPUS and NUMA Nodes for this architecture.
611 int "Maximum number of CPUs (2-512)" if !MAXSMP
614 default "4096" if MAXSMP
615 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
618 This allows you to specify the maximum number of CPUs which this
619 kernel will support. The maximum supported value is 512 and the
620 minimum value which makes sense is 2.
622 This is purely to save memory - each supported CPU adds
623 approximately eight kilobytes to the kernel image.
626 bool "SMT (Hyperthreading) scheduler support"
629 SMT scheduler support improves the CPU scheduler's decision making
630 when dealing with Intel Pentium 4 chips with HyperThreading at a
631 cost of slightly increased overhead in some places. If unsure say
636 prompt "Multi-core scheduler support"
639 Multi-core scheduler support improves the CPU scheduler's decision
640 making when dealing with multi-core CPU chips at a cost of slightly
641 increased overhead in some places. If unsure say N here.
643 source "kernel/Kconfig.preempt"
646 bool "Local APIC support on uniprocessors"
647 depends on X86_32 && !SMP && !(X86_VOYAGER || X86_GENERICARCH)
649 A local APIC (Advanced Programmable Interrupt Controller) is an
650 integrated interrupt controller in the CPU. If you have a single-CPU
651 system which has a processor with a local APIC, you can say Y here to
652 enable and use it. If you say Y here even though your machine doesn't
653 have a local APIC, then the kernel will still run with no slowdown at
654 all. The local APIC supports CPU-generated self-interrupts (timer,
655 performance counters), and the NMI watchdog which detects hard
659 bool "IO-APIC support on uniprocessors"
660 depends on X86_UP_APIC
662 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
663 SMP-capable replacement for PC-style interrupt controllers. Most
664 SMP systems and many recent uniprocessor systems have one.
666 If you have a single-CPU system with an IO-APIC, you can say Y here
667 to use it. If you say Y here even though your machine doesn't have
668 an IO-APIC, then the kernel will still run with no slowdown at all.
670 config X86_LOCAL_APIC
672 depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
676 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
678 config X86_VISWS_APIC
680 depends on X86_32 && X86_VISWS
682 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
683 bool "Reroute for broken boot IRQs"
685 depends on X86_IO_APIC
687 This option enables a workaround that fixes a source of
688 spurious interrupts. This is recommended when threaded
689 interrupt handling is used on systems where the generation of
690 superfluous "boot interrupts" cannot be disabled.
692 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
693 entry in the chipset's IO-APIC is masked (as, e.g. the RT
694 kernel does during interrupt handling). On chipsets where this
695 boot IRQ generation cannot be disabled, this workaround keeps
696 the original IRQ line masked so that only the equivalent "boot
697 IRQ" is delivered to the CPUs. The workaround also tells the
698 kernel to set up the IRQ handler on the boot IRQ line. In this
699 way only one interrupt is delivered to the kernel. Otherwise
700 the spurious second interrupt may cause the kernel to bring
701 down (vital) interrupt lines.
703 Only affects "broken" chipsets. Interrupt sharing may be
704 increased on these systems.
707 bool "Machine Check Exception"
708 depends on !X86_VOYAGER
710 Machine Check Exception support allows the processor to notify the
711 kernel if it detects a problem (e.g. overheating, component failure).
712 The action the kernel takes depends on the severity of the problem,
713 ranging from a warning message on the console, to halting the machine.
714 Your processor must be a Pentium or newer to support this - check the
715 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
716 have a design flaw which leads to false MCE events - hence MCE is
717 disabled on all P5 processors, unless explicitly enabled with "mce"
718 as a boot argument. Similarly, if MCE is built in and creates a
719 problem on some new non-standard machine, you can boot with "nomce"
720 to disable it. MCE support simply ignores non-MCE processors like
721 the 386 and 486, so nearly everyone can say Y here.
725 prompt "Intel MCE features"
726 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
728 Additional support for intel specific MCE features such as
733 prompt "AMD MCE features"
734 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
736 Additional support for AMD specific MCE features such as
737 the DRAM Error Threshold.
739 config X86_MCE_NONFATAL
740 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
741 depends on X86_32 && X86_MCE
743 Enabling this feature starts a timer that triggers every 5 seconds which
744 will look at the machine check registers to see if anything happened.
745 Non-fatal problems automatically get corrected (but still logged).
746 Disable this if you don't want to see these messages.
747 Seeing the messages this option prints out may be indicative of dying
748 or out-of-spec (ie, overclocked) hardware.
749 This option only does something on certain CPUs.
750 (AMD Athlon/Duron and Intel Pentium 4)
752 config X86_MCE_P4THERMAL
753 bool "check for P4 thermal throttling interrupt."
754 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
756 Enabling this feature will cause a message to be printed when the P4
757 enters thermal throttling.
760 bool "Enable VM86 support" if EMBEDDED
764 This option is required by programs like DOSEMU to run 16-bit legacy
765 code on X86 processors. It also may be needed by software like
766 XFree86 to initialize some video cards via BIOS. Disabling this
767 option saves about 6k.
770 tristate "Toshiba Laptop support"
773 This adds a driver to safely access the System Management Mode of
774 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
775 not work on models with a Phoenix BIOS. The System Management Mode
776 is used to set the BIOS and power saving options on Toshiba portables.
778 For information on utilities to make use of this driver see the
779 Toshiba Linux utilities web site at:
780 <http://www.buzzard.org.uk/toshiba/>.
782 Say Y if you intend to run this kernel on a Toshiba portable.
786 tristate "Dell laptop support"
788 This adds a driver to safely access the System Management Mode
789 of the CPU on the Dell Inspiron 8000. The System Management Mode
790 is used to read cpu temperature and cooling fan status and to
791 control the fans on the I8K portables.
793 This driver has been tested only on the Inspiron 8000 but it may
794 also work with other Dell laptops. You can force loading on other
795 models by passing the parameter `force=1' to the module. Use at
798 For information on utilities to make use of this driver see the
799 I8K Linux utilities web site at:
800 <http://people.debian.org/~dz/i8k/>
802 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
805 config X86_REBOOTFIXUPS
806 bool "Enable X86 board specific fixups for reboot"
809 This enables chipset and/or board specific fixups to be done
810 in order to get reboot to work correctly. This is only needed on
811 some combinations of hardware and BIOS. The symptom, for which
812 this config is intended, is when reboot ends with a stalled/hung
815 Currently, the only fixup is for the Geode machines using
816 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
818 Say Y if you want to enable the fixup. Currently, it's safe to
819 enable this option even if you don't need it.
823 tristate "/dev/cpu/microcode - microcode support"
826 If you say Y here, you will be able to update the microcode on
827 certain Intel and AMD processors. The Intel support is for the
828 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
829 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
830 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
831 You will obviously need the actual microcode binary data itself
832 which is not shipped with the Linux kernel.
834 This option selects the general module only, you need to select
835 at least one vendor specific module as well.
837 To compile this driver as a module, choose M here: the
838 module will be called microcode.
840 config MICROCODE_INTEL
841 bool "Intel microcode patch loading support"
846 This options enables microcode patch loading support for Intel
849 For latest news and information on obtaining all the required
850 Intel ingredients for this driver, check:
851 <http://www.urbanmyth.org/microcode/>.
854 bool "AMD microcode patch loading support"
858 If you select this option, microcode patch loading support for AMD
859 processors will be enabled.
861 config MICROCODE_OLD_INTERFACE
866 tristate "/dev/cpu/*/msr - Model-specific register support"
868 This device gives privileged processes access to the x86
869 Model-Specific Registers (MSRs). It is a character device with
870 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
871 MSR accesses are directed to a specific CPU on multi-processor
875 tristate "/dev/cpu/*/cpuid - CPU information support"
877 This device gives processes access to the x86 CPUID instruction to
878 be executed on a specific processor. It is a character device
879 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
883 prompt "High Memory Support"
884 default HIGHMEM4G if !X86_NUMAQ
885 default HIGHMEM64G if X86_NUMAQ
890 depends on !X86_NUMAQ
892 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
893 However, the address space of 32-bit x86 processors is only 4
894 Gigabytes large. That means that, if you have a large amount of
895 physical memory, not all of it can be "permanently mapped" by the
896 kernel. The physical memory that's not permanently mapped is called
899 If you are compiling a kernel which will never run on a machine with
900 more than 1 Gigabyte total physical RAM, answer "off" here (default
901 choice and suitable for most users). This will result in a "3GB/1GB"
902 split: 3GB are mapped so that each process sees a 3GB virtual memory
903 space and the remaining part of the 4GB virtual memory space is used
904 by the kernel to permanently map as much physical memory as
907 If the machine has between 1 and 4 Gigabytes physical RAM, then
910 If more than 4 Gigabytes is used then answer "64GB" here. This
911 selection turns Intel PAE (Physical Address Extension) mode on.
912 PAE implements 3-level paging on IA32 processors. PAE is fully
913 supported by Linux, PAE mode is implemented on all recent Intel
914 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
915 then the kernel will not boot on CPUs that don't support PAE!
917 The actual amount of total physical memory will either be
918 auto detected or can be forced by using a kernel command line option
919 such as "mem=256M". (Try "man bootparam" or see the documentation of
920 your boot loader (lilo or loadlin) about how to pass options to the
921 kernel at boot time.)
923 If unsure, say "off".
927 depends on !X86_NUMAQ
929 Select this if you have a 32-bit processor and between 1 and 4
930 gigabytes of physical RAM.
934 depends on !M386 && !M486
937 Select this if you have a 32-bit processor and more than 4
938 gigabytes of physical RAM.
943 depends on EXPERIMENTAL
944 prompt "Memory split" if EMBEDDED
948 Select the desired split between kernel and user memory.
950 If the address range available to the kernel is less than the
951 physical memory installed, the remaining memory will be available
952 as "high memory". Accessing high memory is a little more costly
953 than low memory, as it needs to be mapped into the kernel first.
954 Note that increasing the kernel address space limits the range
955 available to user programs, making the address space there
956 tighter. Selecting anything other than the default 3G/1G split
957 will also likely make your kernel incompatible with binary-only
960 If you are not absolutely sure what you are doing, leave this
964 bool "3G/1G user/kernel split"
965 config VMSPLIT_3G_OPT
967 bool "3G/1G user/kernel split (for full 1G low memory)"
969 bool "2G/2G user/kernel split"
970 config VMSPLIT_2G_OPT
972 bool "2G/2G user/kernel split (for full 2G low memory)"
974 bool "1G/3G user/kernel split"
979 default 0xB0000000 if VMSPLIT_3G_OPT
980 default 0x80000000 if VMSPLIT_2G
981 default 0x78000000 if VMSPLIT_2G_OPT
982 default 0x40000000 if VMSPLIT_1G
988 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
991 bool "PAE (Physical Address Extension) Support"
992 depends on X86_32 && !HIGHMEM4G
994 PAE is required for NX support, and furthermore enables
995 larger swapspace support for non-overcommit purposes. It
996 has the cost of more pagetable lookup overhead, and also
997 consumes more pagetable space per process.
999 config ARCH_PHYS_ADDR_T_64BIT
1000 def_bool X86_64 || X86_PAE
1002 config DIRECT_GBPAGES
1003 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1007 Allow the kernel linear mapping to use 1GB pages on CPUs that
1008 support it. This can improve the kernel's performance a tiny bit by
1009 reducing TLB pressure. If in doubt, say "Y".
1011 # Common NUMA Features
1013 bool "Numa Memory Allocation and Scheduler Support"
1015 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1017 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1019 Enable NUMA (Non Uniform Memory Access) support.
1021 The kernel will try to allocate memory used by a CPU on the
1022 local memory controller of the CPU and add some more
1023 NUMA awareness to the kernel.
1025 For 64-bit this is recommended if the system is Intel Core i7
1026 (or later), AMD Opteron, or EM64T NUMA.
1028 For 32-bit this is only needed on (rare) 32-bit-only platforms
1029 that support NUMA topologies, such as NUMAQ / Summit, or if you
1030 boot a 32-bit kernel on a 64-bit NUMA platform.
1032 Otherwise, you should say N.
1034 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1035 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1039 prompt "Old style AMD Opteron NUMA detection"
1040 depends on X86_64 && NUMA && PCI
1042 Enable K8 NUMA node topology detection. You should say Y here if
1043 you have a multi processor AMD K8 system. This uses an old
1044 method to read the NUMA configuration directly from the builtin
1045 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1046 instead, which also takes priority if both are compiled in.
1048 config X86_64_ACPI_NUMA
1050 prompt "ACPI NUMA detection"
1051 depends on X86_64 && NUMA && ACPI && PCI
1054 Enable ACPI SRAT based node topology detection.
1056 # Some NUMA nodes have memory ranges that span
1057 # other nodes. Even though a pfn is valid and
1058 # between a node's start and end pfns, it may not
1059 # reside on that node. See memmap_init_zone()
1061 config NODES_SPAN_OTHER_NODES
1063 depends on X86_64_ACPI_NUMA
1066 bool "NUMA emulation"
1067 depends on X86_64 && NUMA
1069 Enable NUMA emulation. A flat machine will be split
1070 into virtual nodes when booted with "numa=fake=N", where N is the
1071 number of nodes. This is only useful for debugging.
1074 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1076 default "9" if MAXSMP
1077 default "6" if X86_64
1078 default "4" if X86_NUMAQ
1080 depends on NEED_MULTIPLE_NODES
1082 Specify the maximum number of NUMA Nodes available on the target
1083 system. Increases memory reserved to accomodate various tables.
1085 config HAVE_ARCH_BOOTMEM_NODE
1087 depends on X86_32 && NUMA
1089 config ARCH_HAVE_MEMORY_PRESENT
1091 depends on X86_32 && DISCONTIGMEM
1093 config NEED_NODE_MEMMAP_SIZE
1095 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1097 config HAVE_ARCH_ALLOC_REMAP
1099 depends on X86_32 && NUMA
1101 config ARCH_FLATMEM_ENABLE
1103 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1105 config ARCH_DISCONTIGMEM_ENABLE
1107 depends on NUMA && X86_32
1109 config ARCH_DISCONTIGMEM_DEFAULT
1111 depends on NUMA && X86_32
1113 config ARCH_SPARSEMEM_DEFAULT
1117 config ARCH_SPARSEMEM_ENABLE
1119 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC) || X86_GENERICARCH
1120 select SPARSEMEM_STATIC if X86_32
1121 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1123 config ARCH_SELECT_MEMORY_MODEL
1125 depends on ARCH_SPARSEMEM_ENABLE
1127 config ARCH_MEMORY_PROBE
1129 depends on MEMORY_HOTPLUG
1134 bool "Allocate 3rd-level pagetables from highmem"
1135 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1137 The VM uses one page table entry for each page of physical memory.
1138 For systems with a lot of RAM, this can be wasteful of precious
1139 low memory. Setting this option will put user-space page table
1140 entries in high memory.
1142 config X86_CHECK_BIOS_CORRUPTION
1143 bool "Check for low memory corruption"
1145 Periodically check for memory corruption in low memory, which
1146 is suspected to be caused by BIOS. Even when enabled in the
1147 configuration, it is disabled at runtime. Enable it by
1148 setting "memory_corruption_check=1" on the kernel command
1149 line. By default it scans the low 64k of memory every 60
1150 seconds; see the memory_corruption_check_size and
1151 memory_corruption_check_period parameters in
1152 Documentation/kernel-parameters.txt to adjust this.
1154 When enabled with the default parameters, this option has
1155 almost no overhead, as it reserves a relatively small amount
1156 of memory and scans it infrequently. It both detects corruption
1157 and prevents it from affecting the running system.
1159 It is, however, intended as a diagnostic tool; if repeatable
1160 BIOS-originated corruption always affects the same memory,
1161 you can use memmap= to prevent the kernel from using that
1164 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1165 bool "Set the default setting of memory_corruption_check"
1166 depends on X86_CHECK_BIOS_CORRUPTION
1169 Set whether the default state of memory_corruption_check is
1172 config X86_RESERVE_LOW_64K
1173 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1176 Reserve the first 64K of physical RAM on BIOSes that are known
1177 to potentially corrupt that memory range. A numbers of BIOSes are
1178 known to utilize this area during suspend/resume, so it must not
1179 be used by the kernel.
1181 Set this to N if you are absolutely sure that you trust the BIOS
1182 to get all its memory reservations and usages right.
1184 If you have doubts about the BIOS (e.g. suspend/resume does not
1185 work or there's kernel crashes after certain hardware hotplug
1186 events) and it's not AMI or Phoenix, then you might want to enable
1187 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1188 corruption patterns.
1192 config MATH_EMULATION
1194 prompt "Math emulation" if X86_32
1196 Linux can emulate a math coprocessor (used for floating point
1197 operations) if you don't have one. 486DX and Pentium processors have
1198 a math coprocessor built in, 486SX and 386 do not, unless you added
1199 a 487DX or 387, respectively. (The messages during boot time can
1200 give you some hints here ["man dmesg"].) Everyone needs either a
1201 coprocessor or this emulation.
1203 If you don't have a math coprocessor, you need to say Y here; if you
1204 say Y here even though you have a coprocessor, the coprocessor will
1205 be used nevertheless. (This behavior can be changed with the kernel
1206 command line option "no387", which comes handy if your coprocessor
1207 is broken. Try "man bootparam" or see the documentation of your boot
1208 loader (lilo or loadlin) about how to pass options to the kernel at
1209 boot time.) This means that it is a good idea to say Y here if you
1210 intend to use this kernel on different machines.
1212 More information about the internals of the Linux math coprocessor
1213 emulation can be found in <file:arch/x86/math-emu/README>.
1215 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1216 kernel, it won't hurt.
1219 bool "MTRR (Memory Type Range Register) support"
1221 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1222 the Memory Type Range Registers (MTRRs) may be used to control
1223 processor access to memory ranges. This is most useful if you have
1224 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1225 allows bus write transfers to be combined into a larger transfer
1226 before bursting over the PCI/AGP bus. This can increase performance
1227 of image write operations 2.5 times or more. Saying Y here creates a
1228 /proc/mtrr file which may be used to manipulate your processor's
1229 MTRRs. Typically the X server should use this.
1231 This code has a reasonably generic interface so that similar
1232 control registers on other processors can be easily supported
1235 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1236 Registers (ARRs) which provide a similar functionality to MTRRs. For
1237 these, the ARRs are used to emulate the MTRRs.
1238 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1239 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1240 write-combining. All of these processors are supported by this code
1241 and it makes sense to say Y here if you have one of them.
1243 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1244 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1245 can lead to all sorts of problems, so it's good to say Y here.
1247 You can safely say Y even if your machine doesn't have MTRRs, you'll
1248 just add about 9 KB to your kernel.
1250 See <file:Documentation/x86/mtrr.txt> for more information.
1252 config MTRR_SANITIZER
1254 prompt "MTRR cleanup support"
1257 Convert MTRR layout from continuous to discrete, so X drivers can
1258 add writeback entries.
1260 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1261 The largest mtrr entry size for a continous block can be set with
1266 config MTRR_SANITIZER_ENABLE_DEFAULT
1267 int "MTRR cleanup enable value (0-1)"
1270 depends on MTRR_SANITIZER
1272 Enable mtrr cleanup default value
1274 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1275 int "MTRR cleanup spare reg num (0-7)"
1278 depends on MTRR_SANITIZER
1280 mtrr cleanup spare entries default, it can be changed via
1281 mtrr_spare_reg_nr=N on the kernel command line.
1285 prompt "x86 PAT support"
1288 Use PAT attributes to setup page level cache control.
1290 PATs are the modern equivalents of MTRRs and are much more
1291 flexible than MTRRs.
1293 Say N here if you see bootup problems (boot crash, boot hang,
1294 spontaneous reboots) or a non-working video driver.
1299 bool "EFI runtime service support"
1302 This enables the kernel to use EFI runtime services that are
1303 available (such as the EFI variable services).
1305 This option is only useful on systems that have EFI firmware.
1306 In addition, you should use the latest ELILO loader available
1307 at <http://elilo.sourceforge.net> in order to take advantage
1308 of EFI runtime services. However, even with this option, the
1309 resultant kernel should continue to boot on existing non-EFI
1314 prompt "Enable seccomp to safely compute untrusted bytecode"
1316 This kernel feature is useful for number crunching applications
1317 that may need to compute untrusted bytecode during their
1318 execution. By using pipes or other transports made available to
1319 the process as file descriptors supporting the read/write
1320 syscalls, it's possible to isolate those applications in
1321 their own address space using seccomp. Once seccomp is
1322 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1323 and the task is only allowed to execute a few safe syscalls
1324 defined by each seccomp mode.
1326 If unsure, say Y. Only embedded should say N here.
1328 config CC_STACKPROTECTOR
1329 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1330 depends on X86_64 && EXPERIMENTAL && BROKEN
1332 This option turns on the -fstack-protector GCC feature. This
1333 feature puts, at the beginning of critical functions, a canary
1334 value on the stack just before the return address, and validates
1335 the value just before actually returning. Stack based buffer
1336 overflows (that need to overwrite this return address) now also
1337 overwrite the canary, which gets detected and the attack is then
1338 neutralized via a kernel panic.
1340 This feature requires gcc version 4.2 or above, or a distribution
1341 gcc with the feature backported. Older versions are automatically
1342 detected and for those versions, this configuration option is ignored.
1344 config CC_STACKPROTECTOR_ALL
1345 bool "Use stack-protector for all functions"
1346 depends on CC_STACKPROTECTOR
1348 Normally, GCC only inserts the canary value protection for
1349 functions that use large-ish on-stack buffers. By enabling
1350 this option, GCC will be asked to do this for ALL functions.
1352 source kernel/Kconfig.hz
1355 bool "kexec system call"
1356 depends on X86_BIOS_REBOOT
1358 kexec is a system call that implements the ability to shutdown your
1359 current kernel, and to start another kernel. It is like a reboot
1360 but it is independent of the system firmware. And like a reboot
1361 you can start any kernel with it, not just Linux.
1363 The name comes from the similarity to the exec system call.
1365 It is an ongoing process to be certain the hardware in a machine
1366 is properly shutdown, so do not be surprised if this code does not
1367 initially work for you. It may help to enable device hotplugging
1368 support. As of this writing the exact hardware interface is
1369 strongly in flux, so no good recommendation can be made.
1372 bool "kernel crash dumps"
1373 depends on X86_64 || (X86_32 && HIGHMEM)
1375 Generate crash dump after being started by kexec.
1376 This should be normally only set in special crash dump kernels
1377 which are loaded in the main kernel with kexec-tools into
1378 a specially reserved region and then later executed after
1379 a crash by kdump/kexec. The crash dump kernel must be compiled
1380 to a memory address not used by the main kernel or BIOS using
1381 PHYSICAL_START, or it must be built as a relocatable image
1382 (CONFIG_RELOCATABLE=y).
1383 For more details see Documentation/kdump/kdump.txt
1386 bool "kexec jump (EXPERIMENTAL)"
1387 depends on EXPERIMENTAL
1388 depends on KEXEC && HIBERNATION && X86_32
1390 Jump between original kernel and kexeced kernel and invoke
1391 code in physical address mode via KEXEC
1393 config PHYSICAL_START
1394 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1395 default "0x1000000" if X86_NUMAQ
1396 default "0x200000" if X86_64
1399 This gives the physical address where the kernel is loaded.
1401 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1402 bzImage will decompress itself to above physical address and
1403 run from there. Otherwise, bzImage will run from the address where
1404 it has been loaded by the boot loader and will ignore above physical
1407 In normal kdump cases one does not have to set/change this option
1408 as now bzImage can be compiled as a completely relocatable image
1409 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1410 address. This option is mainly useful for the folks who don't want
1411 to use a bzImage for capturing the crash dump and want to use a
1412 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1413 to be specifically compiled to run from a specific memory area
1414 (normally a reserved region) and this option comes handy.
1416 So if you are using bzImage for capturing the crash dump, leave
1417 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1418 Otherwise if you plan to use vmlinux for capturing the crash dump
1419 change this value to start of the reserved region (Typically 16MB
1420 0x1000000). In other words, it can be set based on the "X" value as
1421 specified in the "crashkernel=YM@XM" command line boot parameter
1422 passed to the panic-ed kernel. Typically this parameter is set as
1423 crashkernel=64M@16M. Please take a look at
1424 Documentation/kdump/kdump.txt for more details about crash dumps.
1426 Usage of bzImage for capturing the crash dump is recommended as
1427 one does not have to build two kernels. Same kernel can be used
1428 as production kernel and capture kernel. Above option should have
1429 gone away after relocatable bzImage support is introduced. But it
1430 is present because there are users out there who continue to use
1431 vmlinux for dump capture. This option should go away down the
1434 Don't change this unless you know what you are doing.
1437 bool "Build a relocatable kernel (EXPERIMENTAL)"
1438 depends on EXPERIMENTAL
1440 This builds a kernel image that retains relocation information
1441 so it can be loaded someplace besides the default 1MB.
1442 The relocations tend to make the kernel binary about 10% larger,
1443 but are discarded at runtime.
1445 One use is for the kexec on panic case where the recovery kernel
1446 must live at a different physical address than the primary
1449 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1450 it has been loaded at and the compile time physical address
1451 (CONFIG_PHYSICAL_START) is ignored.
1453 config PHYSICAL_ALIGN
1455 prompt "Alignment value to which kernel should be aligned" if X86_32
1456 default "0x100000" if X86_32
1457 default "0x200000" if X86_64
1458 range 0x2000 0x400000
1460 This value puts the alignment restrictions on physical address
1461 where kernel is loaded and run from. Kernel is compiled for an
1462 address which meets above alignment restriction.
1464 If bootloader loads the kernel at a non-aligned address and
1465 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1466 address aligned to above value and run from there.
1468 If bootloader loads the kernel at a non-aligned address and
1469 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1470 load address and decompress itself to the address it has been
1471 compiled for and run from there. The address for which kernel is
1472 compiled already meets above alignment restrictions. Hence the
1473 end result is that kernel runs from a physical address meeting
1474 above alignment restrictions.
1476 Don't change this unless you know what you are doing.
1479 bool "Support for hot-pluggable CPUs"
1480 depends on SMP && HOTPLUG && !X86_VOYAGER
1482 Say Y here to allow turning CPUs off and on. CPUs can be
1483 controlled through /sys/devices/system/cpu.
1484 ( Note: power management support will enable this option
1485 automatically on SMP systems. )
1486 Say N if you want to disable CPU hotplug.
1490 prompt "Compat VDSO support"
1491 depends on X86_32 || IA32_EMULATION
1493 Map the 32-bit VDSO to the predictable old-style address too.
1495 Say N here if you are running a sufficiently recent glibc
1496 version (2.3.3 or later), to remove the high-mapped
1497 VDSO mapping and to exclusively use the randomized VDSO.
1502 bool "Built-in kernel command line"
1505 Allow for specifying boot arguments to the kernel at
1506 build time. On some systems (e.g. embedded ones), it is
1507 necessary or convenient to provide some or all of the
1508 kernel boot arguments with the kernel itself (that is,
1509 to not rely on the boot loader to provide them.)
1511 To compile command line arguments into the kernel,
1512 set this option to 'Y', then fill in the
1513 the boot arguments in CONFIG_CMDLINE.
1515 Systems with fully functional boot loaders (i.e. non-embedded)
1516 should leave this option set to 'N'.
1519 string "Built-in kernel command string"
1520 depends on CMDLINE_BOOL
1523 Enter arguments here that should be compiled into the kernel
1524 image and used at boot time. If the boot loader provides a
1525 command line at boot time, it is appended to this string to
1526 form the full kernel command line, when the system boots.
1528 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1529 change this behavior.
1531 In most cases, the command line (whether built-in or provided
1532 by the boot loader) should specify the device for the root
1535 config CMDLINE_OVERRIDE
1536 bool "Built-in command line overrides boot loader arguments"
1538 depends on CMDLINE_BOOL
1540 Set this option to 'Y' to have the kernel ignore the boot loader
1541 command line, and use ONLY the built-in command line.
1543 This is used to work around broken boot loaders. This should
1544 be set to 'N' under normal conditions.
1548 config ARCH_ENABLE_MEMORY_HOTPLUG
1550 depends on X86_64 || (X86_32 && HIGHMEM)
1552 config ARCH_ENABLE_MEMORY_HOTREMOVE
1554 depends on MEMORY_HOTPLUG
1556 config HAVE_ARCH_EARLY_PFN_TO_NID
1560 menu "Power management and ACPI options"
1561 depends on !X86_VOYAGER
1563 config ARCH_HIBERNATION_HEADER
1565 depends on X86_64 && HIBERNATION
1567 source "kernel/power/Kconfig"
1569 source "drivers/acpi/Kconfig"
1574 depends on APM || APM_MODULE
1577 tristate "APM (Advanced Power Management) BIOS support"
1578 depends on X86_32 && PM_SLEEP
1580 APM is a BIOS specification for saving power using several different
1581 techniques. This is mostly useful for battery powered laptops with
1582 APM compliant BIOSes. If you say Y here, the system time will be
1583 reset after a RESUME operation, the /proc/apm device will provide
1584 battery status information, and user-space programs will receive
1585 notification of APM "events" (e.g. battery status change).
1587 If you select "Y" here, you can disable actual use of the APM
1588 BIOS by passing the "apm=off" option to the kernel at boot time.
1590 Note that the APM support is almost completely disabled for
1591 machines with more than one CPU.
1593 In order to use APM, you will need supporting software. For location
1594 and more information, read <file:Documentation/power/pm.txt> and the
1595 Battery Powered Linux mini-HOWTO, available from
1596 <http://www.tldp.org/docs.html#howto>.
1598 This driver does not spin down disk drives (see the hdparm(8)
1599 manpage ("man 8 hdparm") for that), and it doesn't turn off
1600 VESA-compliant "green" monitors.
1602 This driver does not support the TI 4000M TravelMate and the ACER
1603 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1604 desktop machines also don't have compliant BIOSes, and this driver
1605 may cause those machines to panic during the boot phase.
1607 Generally, if you don't have a battery in your machine, there isn't
1608 much point in using this driver and you should say N. If you get
1609 random kernel OOPSes or reboots that don't seem to be related to
1610 anything, try disabling/enabling this option (or disabling/enabling
1613 Some other things you should try when experiencing seemingly random,
1616 1) make sure that you have enough swap space and that it is
1618 2) pass the "no-hlt" option to the kernel
1619 3) switch on floating point emulation in the kernel and pass
1620 the "no387" option to the kernel
1621 4) pass the "floppy=nodma" option to the kernel
1622 5) pass the "mem=4M" option to the kernel (thereby disabling
1623 all but the first 4 MB of RAM)
1624 6) make sure that the CPU is not over clocked.
1625 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1626 8) disable the cache from your BIOS settings
1627 9) install a fan for the video card or exchange video RAM
1628 10) install a better fan for the CPU
1629 11) exchange RAM chips
1630 12) exchange the motherboard.
1632 To compile this driver as a module, choose M here: the
1633 module will be called apm.
1637 config APM_IGNORE_USER_SUSPEND
1638 bool "Ignore USER SUSPEND"
1640 This option will ignore USER SUSPEND requests. On machines with a
1641 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1642 series notebooks, it is necessary to say Y because of a BIOS bug.
1644 config APM_DO_ENABLE
1645 bool "Enable PM at boot time"
1647 Enable APM features at boot time. From page 36 of the APM BIOS
1648 specification: "When disabled, the APM BIOS does not automatically
1649 power manage devices, enter the Standby State, enter the Suspend
1650 State, or take power saving steps in response to CPU Idle calls."
1651 This driver will make CPU Idle calls when Linux is idle (unless this
1652 feature is turned off -- see "Do CPU IDLE calls", below). This
1653 should always save battery power, but more complicated APM features
1654 will be dependent on your BIOS implementation. You may need to turn
1655 this option off if your computer hangs at boot time when using APM
1656 support, or if it beeps continuously instead of suspending. Turn
1657 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1658 T400CDT. This is off by default since most machines do fine without
1662 bool "Make CPU Idle calls when idle"
1664 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1665 On some machines, this can activate improved power savings, such as
1666 a slowed CPU clock rate, when the machine is idle. These idle calls
1667 are made after the idle loop has run for some length of time (e.g.,
1668 333 mS). On some machines, this will cause a hang at boot time or
1669 whenever the CPU becomes idle. (On machines with more than one CPU,
1670 this option does nothing.)
1672 config APM_DISPLAY_BLANK
1673 bool "Enable console blanking using APM"
1675 Enable console blanking using the APM. Some laptops can use this to
1676 turn off the LCD backlight when the screen blanker of the Linux
1677 virtual console blanks the screen. Note that this is only used by
1678 the virtual console screen blanker, and won't turn off the backlight
1679 when using the X Window system. This also doesn't have anything to
1680 do with your VESA-compliant power-saving monitor. Further, this
1681 option doesn't work for all laptops -- it might not turn off your
1682 backlight at all, or it might print a lot of errors to the console,
1683 especially if you are using gpm.
1685 config APM_ALLOW_INTS
1686 bool "Allow interrupts during APM BIOS calls"
1688 Normally we disable external interrupts while we are making calls to
1689 the APM BIOS as a measure to lessen the effects of a badly behaving
1690 BIOS implementation. The BIOS should reenable interrupts if it
1691 needs to. Unfortunately, some BIOSes do not -- especially those in
1692 many of the newer IBM Thinkpads. If you experience hangs when you
1693 suspend, try setting this to Y. Otherwise, say N.
1697 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1699 source "drivers/cpuidle/Kconfig"
1701 source "drivers/idle/Kconfig"
1706 menu "Bus options (PCI etc.)"
1711 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1713 Find out whether you have a PCI motherboard. PCI is the name of a
1714 bus system, i.e. the way the CPU talks to the other stuff inside
1715 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1716 VESA. If you have PCI, say Y, otherwise N.
1719 prompt "PCI access mode"
1720 depends on X86_32 && PCI
1723 On PCI systems, the BIOS can be used to detect the PCI devices and
1724 determine their configuration. However, some old PCI motherboards
1725 have BIOS bugs and may crash if this is done. Also, some embedded
1726 PCI-based systems don't have any BIOS at all. Linux can also try to
1727 detect the PCI hardware directly without using the BIOS.
1729 With this option, you can specify how Linux should detect the
1730 PCI devices. If you choose "BIOS", the BIOS will be used,
1731 if you choose "Direct", the BIOS won't be used, and if you
1732 choose "MMConfig", then PCI Express MMCONFIG will be used.
1733 If you choose "Any", the kernel will try MMCONFIG, then the
1734 direct access method and falls back to the BIOS if that doesn't
1735 work. If unsure, go with the default, which is "Any".
1740 config PCI_GOMMCONFIG
1757 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1759 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1762 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1766 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1770 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1777 bool "Support mmconfig PCI config space access"
1778 depends on X86_64 && PCI && ACPI
1781 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1782 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1784 DMA remapping (DMAR) devices support enables independent address
1785 translations for Direct Memory Access (DMA) from devices.
1786 These DMA remapping devices are reported via ACPI tables
1787 and include PCI device scope covered by these DMA
1792 prompt "Support for Graphics workaround"
1795 Current Graphics drivers tend to use physical address
1796 for DMA and avoid using DMA APIs. Setting this config
1797 option permits the IOMMU driver to set a unity map for
1798 all the OS-visible memory. Hence the driver can continue
1799 to use physical addresses for DMA.
1801 config DMAR_FLOPPY_WA
1805 Floppy disk drivers are know to bypass DMA API calls
1806 thereby failing to work when IOMMU is enabled. This
1807 workaround will setup a 1:1 mapping for the first
1808 16M to make floppy (an ISA device) work.
1811 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1812 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1814 Supports Interrupt remapping for IO-APIC and MSI devices.
1815 To use x2apic mode in the CPU's which support x2APIC enhancements or
1816 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1818 source "drivers/pci/pcie/Kconfig"
1820 source "drivers/pci/Kconfig"
1822 # x86_64 have no ISA slots, but do have ISA-style DMA.
1830 depends on !X86_VOYAGER
1832 Find out whether you have ISA slots on your motherboard. ISA is the
1833 name of a bus system, i.e. the way the CPU talks to the other stuff
1834 inside your box. Other bus systems are PCI, EISA, MicroChannel
1835 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1836 newer boards don't support it. If you have ISA, say Y, otherwise N.
1842 The Extended Industry Standard Architecture (EISA) bus was
1843 developed as an open alternative to the IBM MicroChannel bus.
1845 The EISA bus provided some of the features of the IBM MicroChannel
1846 bus while maintaining backward compatibility with cards made for
1847 the older ISA bus. The EISA bus saw limited use between 1988 and
1848 1995 when it was made obsolete by the PCI bus.
1850 Say Y here if you are building a kernel for an EISA-based machine.
1854 source "drivers/eisa/Kconfig"
1857 bool "MCA support" if !X86_VOYAGER
1858 default y if X86_VOYAGER
1860 MicroChannel Architecture is found in some IBM PS/2 machines and
1861 laptops. It is a bus system similar to PCI or ISA. See
1862 <file:Documentation/mca.txt> (and especially the web page given
1863 there) before attempting to build an MCA bus kernel.
1865 source "drivers/mca/Kconfig"
1868 tristate "NatSemi SCx200 support"
1869 depends on !X86_VOYAGER
1871 This provides basic support for National Semiconductor's
1872 (now AMD's) Geode processors. The driver probes for the
1873 PCI-IDs of several on-chip devices, so its a good dependency
1874 for other scx200_* drivers.
1876 If compiled as a module, the driver is named scx200.
1878 config SCx200HR_TIMER
1879 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1880 depends on SCx200 && GENERIC_TIME
1883 This driver provides a clocksource built upon the on-chip
1884 27MHz high-resolution timer. Its also a workaround for
1885 NSC Geode SC-1100's buggy TSC, which loses time when the
1886 processor goes idle (as is done by the scheduler). The
1887 other workaround is idle=poll boot option.
1889 config GEODE_MFGPT_TIMER
1891 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1892 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1894 This driver provides a clock event source based on the MFGPT
1895 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1896 MFGPTs have a better resolution and max interval than the
1897 generic PIT, and are suitable for use as high-res timers.
1900 bool "One Laptop Per Child support"
1903 Add support for detecting the unique features of the OLPC
1910 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1912 source "drivers/pcmcia/Kconfig"
1914 source "drivers/pci/hotplug/Kconfig"
1919 menu "Executable file formats / Emulations"
1921 source "fs/Kconfig.binfmt"
1923 config IA32_EMULATION
1924 bool "IA32 Emulation"
1926 select COMPAT_BINFMT_ELF
1928 Include code to run 32-bit programs under a 64-bit kernel. You should
1929 likely turn this on, unless you're 100% sure that you don't have any
1930 32-bit programs left.
1933 tristate "IA32 a.out support"
1934 depends on IA32_EMULATION
1936 Support old a.out binaries in the 32bit emulation.
1940 depends on IA32_EMULATION
1942 config COMPAT_FOR_U64_ALIGNMENT
1946 config SYSVIPC_COMPAT
1948 depends on COMPAT && SYSVIPC
1953 config HAVE_ATOMIC_IOMAP
1957 source "net/Kconfig"
1959 source "drivers/Kconfig"
1961 source "drivers/firmware/Kconfig"
1965 source "arch/x86/Kconfig.debug"
1967 source "security/Kconfig"
1969 source "crypto/Kconfig"
1971 source "arch/x86/kvm/Kconfig"
1973 source "lib/Kconfig"
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