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
37 select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
38 select HAVE_FTRACE_SYSCALLS
41 select HAVE_ARCH_TRACEHOOK
42 select HAVE_GENERIC_DMA_COHERENT if X86_32
43 select HAVE_EFFICIENT_UNALIGNED_ACCESS
44 select USER_STACKTRACE_SUPPORT
45 select HAVE_DMA_API_DEBUG
46 select HAVE_KERNEL_GZIP
47 select HAVE_KERNEL_BZIP2
48 select HAVE_KERNEL_LZMA
52 default "arch/x86/configs/i386_defconfig" if X86_32
53 default "arch/x86/configs/x86_64_defconfig" if X86_64
58 config GENERIC_CMOS_UPDATE
61 config CLOCKSOURCE_WATCHDOG
64 config GENERIC_CLOCKEVENTS
67 config GENERIC_CLOCKEVENTS_BROADCAST
69 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
71 config LOCKDEP_SUPPORT
74 config STACKTRACE_SUPPORT
77 config HAVE_LATENCYTOP_SUPPORT
80 config FAST_CMPXCHG_LOCAL
93 config GENERIC_ISA_DMA
102 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
104 config GENERIC_BUG_RELATIVE_POINTERS
107 config GENERIC_HWEIGHT
113 config ARCH_MAY_HAVE_PC_FDC
116 config RWSEM_GENERIC_SPINLOCK
119 config RWSEM_XCHGADD_ALGORITHM
122 config ARCH_HAS_CPU_IDLE_WAIT
125 config GENERIC_CALIBRATE_DELAY
128 config GENERIC_TIME_VSYSCALL
132 config ARCH_HAS_CPU_RELAX
135 config ARCH_HAS_DEFAULT_IDLE
138 config ARCH_HAS_CACHE_LINE_SIZE
141 config HAVE_SETUP_PER_CPU_AREA
144 config HAVE_DYNAMIC_PER_CPU_AREA
147 config HAVE_CPUMASK_OF_CPU_MAP
150 config ARCH_HIBERNATION_POSSIBLE
153 config ARCH_SUSPEND_POSSIBLE
160 config ARCH_POPULATES_NODE_MAP
167 config ARCH_SUPPORTS_OPTIMIZED_INLINING
170 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
173 # Use the generic interrupt handling code in kernel/irq/:
174 config GENERIC_HARDIRQS
178 config GENERIC_HARDIRQS_NO__DO_IRQ
181 config GENERIC_IRQ_PROBE
185 config GENERIC_PENDING_IRQ
187 depends on GENERIC_HARDIRQS && SMP
190 config USE_GENERIC_SMP_HELPERS
196 depends on X86_32 && SMP
200 depends on X86_64 && SMP
207 config X86_TRAMPOLINE
209 depends on SMP || (64BIT && ACPI_SLEEP)
212 config X86_32_LAZY_GS
214 depends on X86_32 && !CC_STACKPROTECTOR
218 source "init/Kconfig"
219 source "kernel/Kconfig.freezer"
221 menu "Processor type and features"
223 source "kernel/time/Kconfig"
226 bool "Symmetric multi-processing support"
228 This enables support for systems with more than one CPU. If you have
229 a system with only one CPU, like most personal computers, say N. If
230 you have a system with more than one CPU, say Y.
232 If you say N here, the kernel will run on single and multiprocessor
233 machines, but will use only one CPU of a multiprocessor machine. If
234 you say Y here, the kernel will run on many, but not all,
235 singleprocessor machines. On a singleprocessor machine, the kernel
236 will run faster if you say N here.
238 Note that if you say Y here and choose architecture "586" or
239 "Pentium" under "Processor family", the kernel will not work on 486
240 architectures. Similarly, multiprocessor kernels for the "PPro"
241 architecture may not work on all Pentium based boards.
243 People using multiprocessor machines who say Y here should also say
244 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
245 Management" code will be disabled if you say Y here.
247 See also <file:Documentation/i386/IO-APIC.txt>,
248 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
249 <http://www.tldp.org/docs.html#howto>.
251 If you don't know what to do here, say N.
254 bool "Support x2apic"
255 depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
257 This enables x2apic support on CPUs that have this feature.
259 This allows 32-bit apic IDs (so it can support very large systems),
260 and accesses the local apic via MSRs not via mmio.
262 If you don't know what to do here, say N.
265 bool "Support sparse irq numbering"
266 depends on PCI_MSI || HT_IRQ
268 This enables support for sparse irqs. This is useful for distro
269 kernels that want to define a high CONFIG_NR_CPUS value but still
270 want to have low kernel memory footprint on smaller machines.
272 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
273 out the irq_desc[] array in a more NUMA-friendly way. )
275 If you don't know what to do here, say N.
279 depends on SPARSE_IRQ && NUMA
282 bool "Enable MPS table" if ACPI
284 depends on X86_LOCAL_APIC
286 For old smp systems that do not have proper acpi support. Newer systems
287 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
290 bool "Support for big SMP systems with more than 8 CPUs"
291 depends on X86_32 && SMP
293 This option is needed for the systems that have more than 8 CPUs
296 config X86_EXTENDED_PLATFORM
297 bool "Support for extended (non-PC) x86 platforms"
300 If you disable this option then the kernel will only support
301 standard PC platforms. (which covers the vast majority of
304 If you enable this option then you'll be able to select support
305 for the following (non-PC) 32 bit x86 platforms:
309 SGI 320/540 (Visual Workstation)
310 Summit/EXA (IBM x440)
311 Unisys ES7000 IA32 series
313 If you have one of these systems, or if you want to build a
314 generic distribution kernel, say Y here - otherwise say N.
318 config X86_EXTENDED_PLATFORM
319 bool "Support for extended (non-PC) x86 platforms"
322 If you disable this option then the kernel will only support
323 standard PC platforms. (which covers the vast majority of
326 If you enable this option then you'll be able to select support
327 for the following (non-PC) 64 bit x86 platforms:
331 If you have one of these systems, or if you want to build a
332 generic distribution kernel, say Y here - otherwise say N.
334 # This is an alphabetically sorted list of 64 bit extended platforms
335 # Please maintain the alphabetic order if and when there are additions
340 depends on X86_64 && PCI
341 depends on X86_EXTENDED_PLATFORM
343 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
344 supposed to run on these EM64T-based machines. Only choose this option
345 if you have one of these machines.
348 bool "SGI Ultraviolet"
350 depends on X86_EXTENDED_PLATFORM
352 depends on X86_X2APIC
354 This option is needed in order to support SGI Ultraviolet systems.
355 If you don't have one of these, you should say N here.
357 # Following is an alphabetically sorted list of 32 bit extended platforms
358 # Please maintain the alphabetic order if and when there are additions
363 depends on X86_EXTENDED_PLATFORM
365 Select this for an AMD Elan processor.
367 Do not use this option for K6/Athlon/Opteron processors!
369 If unsure, choose "PC-compatible" instead.
372 bool "RDC R-321x SoC"
374 depends on X86_EXTENDED_PLATFORM
376 select X86_REBOOTFIXUPS
378 This option is needed for RDC R-321x system-on-chip, also known
380 If you don't have one of these chips, you should say N here.
382 config X86_32_NON_STANDARD
383 bool "Support non-standard 32-bit SMP architectures"
384 depends on X86_32 && SMP
385 depends on X86_EXTENDED_PLATFORM
387 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
388 subarchitectures. It is intended for a generic binary kernel.
389 if you select them all, kernel will probe it one by one. and will
392 # Alphabetically sorted list of Non standard 32 bit platforms
395 bool "NUMAQ (IBM/Sequent)"
396 depends on X86_32_NON_STANDARD
400 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
401 NUMA multiquad box. This changes the way that processors are
402 bootstrapped, and uses Clustered Logical APIC addressing mode instead
403 of Flat Logical. You will need a new lynxer.elf file to flash your
404 firmware with - send email to <Martin.Bligh@us.ibm.com>.
407 bool "SGI 320/540 (Visual Workstation)"
408 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
409 depends on X86_32_NON_STANDARD
411 The SGI Visual Workstation series is an IA32-based workstation
412 based on SGI systems chips with some legacy PC hardware attached.
414 Say Y here to create a kernel to run on the SGI 320 or 540.
416 A kernel compiled for the Visual Workstation will run on general
417 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
420 bool "Summit/EXA (IBM x440)"
421 depends on X86_32_NON_STANDARD
423 This option is needed for IBM systems that use the Summit/EXA chipset.
424 In particular, it is needed for the x440.
427 bool "Unisys ES7000 IA32 series"
428 depends on X86_32_NON_STANDARD && X86_BIGSMP
430 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
431 supposed to run on an IA32-based Unisys ES7000 system.
433 config SCHED_OMIT_FRAME_POINTER
435 prompt "Single-depth WCHAN output"
438 Calculate simpler /proc/<PID>/wchan values. If this option
439 is disabled then wchan values will recurse back to the
440 caller function. This provides more accurate wchan values,
441 at the expense of slightly more scheduling overhead.
443 If in doubt, say "Y".
445 menuconfig PARAVIRT_GUEST
446 bool "Paravirtualized guest support"
448 Say Y here to get to see options related to running Linux under
449 various hypervisors. This option alone does not add any kernel code.
451 If you say N, all options in this submenu will be skipped and disabled.
455 source "arch/x86/xen/Kconfig"
458 bool "VMI Guest support"
462 VMI provides a paravirtualized interface to the VMware ESX server
463 (it could be used by other hypervisors in theory too, but is not
464 at the moment), by linking the kernel to a GPL-ed ROM module
465 provided by the hypervisor.
468 bool "KVM paravirtualized clock"
470 select PARAVIRT_CLOCK
472 Turning on this option will allow you to run a paravirtualized clock
473 when running over the KVM hypervisor. Instead of relying on a PIT
474 (or probably other) emulation by the underlying device model, the host
475 provides the guest with timing infrastructure such as time of day, and
479 bool "KVM Guest support"
482 This option enables various optimizations for running under the KVM
485 source "arch/x86/lguest/Kconfig"
488 bool "Enable paravirtualization code"
490 This changes the kernel so it can modify itself when it is run
491 under a hypervisor, potentially improving performance significantly
492 over full virtualization. However, when run without a hypervisor
493 the kernel is theoretically slower and slightly larger.
495 config PARAVIRT_SPINLOCKS
496 bool "Paravirtualization layer for spinlocks"
497 depends on PARAVIRT && SMP && EXPERIMENTAL
499 Paravirtualized spinlocks allow a pvops backend to replace the
500 spinlock implementation with something virtualization-friendly
501 (for example, block the virtual CPU rather than spinning).
503 Unfortunately the downside is an up to 5% performance hit on
504 native kernels, with various workloads.
506 If you are unsure how to answer this question, answer N.
508 config PARAVIRT_CLOCK
514 config PARAVIRT_DEBUG
515 bool "paravirt-ops debugging"
516 depends on PARAVIRT && DEBUG_KERNEL
518 Enable to debug paravirt_ops internals. Specifically, BUG if
519 a paravirt_op is missing when it is called.
524 This option adds a kernel parameter 'memtest', which allows memtest
526 memtest=0, mean disabled; -- default
527 memtest=1, mean do 1 test pattern;
529 memtest=4, mean do 4 test patterns.
530 If you are unsure how to answer this question, answer N.
532 config X86_SUMMIT_NUMA
534 depends on X86_32 && NUMA && X86_32_NON_STANDARD
536 config X86_CYCLONE_TIMER
538 depends on X86_32_NON_STANDARD
540 source "arch/x86/Kconfig.cpu"
544 prompt "HPET Timer Support" if X86_32
546 Use the IA-PC HPET (High Precision Event Timer) to manage
547 time in preference to the PIT and RTC, if a HPET is
549 HPET is the next generation timer replacing legacy 8254s.
550 The HPET provides a stable time base on SMP
551 systems, unlike the TSC, but it is more expensive to access,
552 as it is off-chip. You can find the HPET spec at
553 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
555 You can safely choose Y here. However, HPET will only be
556 activated if the platform and the BIOS support this feature.
557 Otherwise the 8254 will be used for timing services.
559 Choose N to continue using the legacy 8254 timer.
561 config HPET_EMULATE_RTC
563 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
565 # Mark as embedded because too many people got it wrong.
566 # The code disables itself when not needed.
569 bool "Enable DMI scanning" if EMBEDDED
571 Enabled scanning of DMI to identify machine quirks. Say Y
572 here unless you have verified that your setup is not
573 affected by entries in the DMI blacklist. Required by PNP
577 bool "GART IOMMU support" if EMBEDDED
581 depends on X86_64 && PCI
583 Support for full DMA access of devices with 32bit memory access only
584 on systems with more than 3GB. This is usually needed for USB,
585 sound, many IDE/SATA chipsets and some other devices.
586 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
587 based hardware IOMMU and a software bounce buffer based IOMMU used
588 on Intel systems and as fallback.
589 The code is only active when needed (enough memory and limited
590 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
594 bool "IBM Calgary IOMMU support"
596 depends on X86_64 && PCI && EXPERIMENTAL
598 Support for hardware IOMMUs in IBM's xSeries x366 and x460
599 systems. Needed to run systems with more than 3GB of memory
600 properly with 32-bit PCI devices that do not support DAC
601 (Double Address Cycle). Calgary also supports bus level
602 isolation, where all DMAs pass through the IOMMU. This
603 prevents them from going anywhere except their intended
604 destination. This catches hard-to-find kernel bugs and
605 mis-behaving drivers and devices that do not use the DMA-API
606 properly to set up their DMA buffers. The IOMMU can be
607 turned off at boot time with the iommu=off parameter.
608 Normally the kernel will make the right choice by itself.
611 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
613 prompt "Should Calgary be enabled by default?"
614 depends on CALGARY_IOMMU
616 Should Calgary be enabled by default? if you choose 'y', Calgary
617 will be used (if it exists). If you choose 'n', Calgary will not be
618 used even if it exists. If you choose 'n' and would like to use
619 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
623 bool "AMD IOMMU support"
626 depends on X86_64 && PCI && ACPI
628 With this option you can enable support for AMD IOMMU hardware in
629 your system. An IOMMU is a hardware component which provides
630 remapping of DMA memory accesses from devices. With an AMD IOMMU you
631 can isolate the the DMA memory of different devices and protect the
632 system from misbehaving device drivers or hardware.
634 You can find out if your system has an AMD IOMMU if you look into
635 your BIOS for an option to enable it or if you have an IVRS ACPI
638 config AMD_IOMMU_STATS
639 bool "Export AMD IOMMU statistics to debugfs"
643 This option enables code in the AMD IOMMU driver to collect various
644 statistics about whats happening in the driver and exports that
645 information to userspace via debugfs.
648 # need this always selected by IOMMU for the VIA workaround
652 Support for software bounce buffers used on x86-64 systems
653 which don't have a hardware IOMMU (e.g. the current generation
654 of Intel's x86-64 CPUs). Using this PCI devices which can only
655 access 32-bits of memory can be used on systems with more than
656 3 GB of memory. If unsure, say Y.
659 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
662 def_bool (AMD_IOMMU || DMAR)
665 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
666 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
667 select CPUMASK_OFFSTACK
670 Configure maximum number of CPUS and NUMA Nodes for this architecture.
674 int "Maximum number of CPUs" if SMP && !MAXSMP
675 range 2 8 if SMP && X86_32 && !X86_BIGSMP
676 range 2 512 if SMP && !MAXSMP
678 default "4096" if MAXSMP
679 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
682 This allows you to specify the maximum number of CPUs which this
683 kernel will support. The maximum supported value is 512 and the
684 minimum value which makes sense is 2.
686 This is purely to save memory - each supported CPU adds
687 approximately eight kilobytes to the kernel image.
690 bool "SMT (Hyperthreading) scheduler support"
693 SMT scheduler support improves the CPU scheduler's decision making
694 when dealing with Intel Pentium 4 chips with HyperThreading at a
695 cost of slightly increased overhead in some places. If unsure say
700 prompt "Multi-core scheduler support"
703 Multi-core scheduler support improves the CPU scheduler's decision
704 making when dealing with multi-core CPU chips at a cost of slightly
705 increased overhead in some places. If unsure say N here.
707 source "kernel/Kconfig.preempt"
710 bool "Local APIC support on uniprocessors"
711 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
713 A local APIC (Advanced Programmable Interrupt Controller) is an
714 integrated interrupt controller in the CPU. If you have a single-CPU
715 system which has a processor with a local APIC, you can say Y here to
716 enable and use it. If you say Y here even though your machine doesn't
717 have a local APIC, then the kernel will still run with no slowdown at
718 all. The local APIC supports CPU-generated self-interrupts (timer,
719 performance counters), and the NMI watchdog which detects hard
723 bool "IO-APIC support on uniprocessors"
724 depends on X86_UP_APIC
726 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
727 SMP-capable replacement for PC-style interrupt controllers. Most
728 SMP systems and many recent uniprocessor systems have one.
730 If you have a single-CPU system with an IO-APIC, you can say Y here
731 to use it. If you say Y here even though your machine doesn't have
732 an IO-APIC, then the kernel will still run with no slowdown at all.
734 config X86_LOCAL_APIC
736 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
740 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
742 config X86_VISWS_APIC
744 depends on X86_32 && X86_VISWS
746 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
747 bool "Reroute for broken boot IRQs"
749 depends on X86_IO_APIC
751 This option enables a workaround that fixes a source of
752 spurious interrupts. This is recommended when threaded
753 interrupt handling is used on systems where the generation of
754 superfluous "boot interrupts" cannot be disabled.
756 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
757 entry in the chipset's IO-APIC is masked (as, e.g. the RT
758 kernel does during interrupt handling). On chipsets where this
759 boot IRQ generation cannot be disabled, this workaround keeps
760 the original IRQ line masked so that only the equivalent "boot
761 IRQ" is delivered to the CPUs. The workaround also tells the
762 kernel to set up the IRQ handler on the boot IRQ line. In this
763 way only one interrupt is delivered to the kernel. Otherwise
764 the spurious second interrupt may cause the kernel to bring
765 down (vital) interrupt lines.
767 Only affects "broken" chipsets. Interrupt sharing may be
768 increased on these systems.
771 bool "Machine Check Exception"
773 Machine Check Exception support allows the processor to notify the
774 kernel if it detects a problem (e.g. overheating, component failure).
775 The action the kernel takes depends on the severity of the problem,
776 ranging from a warning message on the console, to halting the machine.
777 Your processor must be a Pentium or newer to support this - check the
778 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
779 have a design flaw which leads to false MCE events - hence MCE is
780 disabled on all P5 processors, unless explicitly enabled with "mce"
781 as a boot argument. Similarly, if MCE is built in and creates a
782 problem on some new non-standard machine, you can boot with "nomce"
783 to disable it. MCE support simply ignores non-MCE processors like
784 the 386 and 486, so nearly everyone can say Y here.
788 prompt "Intel MCE features"
789 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
791 Additional support for intel specific MCE features such as
796 prompt "AMD MCE features"
797 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
799 Additional support for AMD specific MCE features such as
800 the DRAM Error Threshold.
802 config X86_MCE_THRESHOLD
803 depends on X86_MCE_AMD || X86_MCE_INTEL
807 config X86_MCE_NONFATAL
808 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
809 depends on X86_32 && X86_MCE
811 Enabling this feature starts a timer that triggers every 5 seconds which
812 will look at the machine check registers to see if anything happened.
813 Non-fatal problems automatically get corrected (but still logged).
814 Disable this if you don't want to see these messages.
815 Seeing the messages this option prints out may be indicative of dying
816 or out-of-spec (ie, overclocked) hardware.
817 This option only does something on certain CPUs.
818 (AMD Athlon/Duron and Intel Pentium 4)
820 config X86_MCE_P4THERMAL
821 bool "check for P4 thermal throttling interrupt."
822 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
824 Enabling this feature will cause a message to be printed when the P4
825 enters thermal throttling.
828 bool "Enable VM86 support" if EMBEDDED
832 This option is required by programs like DOSEMU to run 16-bit legacy
833 code on X86 processors. It also may be needed by software like
834 XFree86 to initialize some video cards via BIOS. Disabling this
835 option saves about 6k.
838 tristate "Toshiba Laptop support"
841 This adds a driver to safely access the System Management Mode of
842 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
843 not work on models with a Phoenix BIOS. The System Management Mode
844 is used to set the BIOS and power saving options on Toshiba portables.
846 For information on utilities to make use of this driver see the
847 Toshiba Linux utilities web site at:
848 <http://www.buzzard.org.uk/toshiba/>.
850 Say Y if you intend to run this kernel on a Toshiba portable.
854 tristate "Dell laptop support"
856 This adds a driver to safely access the System Management Mode
857 of the CPU on the Dell Inspiron 8000. The System Management Mode
858 is used to read cpu temperature and cooling fan status and to
859 control the fans on the I8K portables.
861 This driver has been tested only on the Inspiron 8000 but it may
862 also work with other Dell laptops. You can force loading on other
863 models by passing the parameter `force=1' to the module. Use at
866 For information on utilities to make use of this driver see the
867 I8K Linux utilities web site at:
868 <http://people.debian.org/~dz/i8k/>
870 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
873 config X86_REBOOTFIXUPS
874 bool "Enable X86 board specific fixups for reboot"
877 This enables chipset and/or board specific fixups to be done
878 in order to get reboot to work correctly. This is only needed on
879 some combinations of hardware and BIOS. The symptom, for which
880 this config is intended, is when reboot ends with a stalled/hung
883 Currently, the only fixup is for the Geode machines using
884 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
886 Say Y if you want to enable the fixup. Currently, it's safe to
887 enable this option even if you don't need it.
891 tristate "/dev/cpu/microcode - microcode support"
894 If you say Y here, you will be able to update the microcode on
895 certain Intel and AMD processors. The Intel support is for the
896 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
897 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
898 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
899 You will obviously need the actual microcode binary data itself
900 which is not shipped with the Linux kernel.
902 This option selects the general module only, you need to select
903 at least one vendor specific module as well.
905 To compile this driver as a module, choose M here: the
906 module will be called microcode.
908 config MICROCODE_INTEL
909 bool "Intel microcode patch loading support"
914 This options enables microcode patch loading support for Intel
917 For latest news and information on obtaining all the required
918 Intel ingredients for this driver, check:
919 <http://www.urbanmyth.org/microcode/>.
922 bool "AMD microcode patch loading support"
926 If you select this option, microcode patch loading support for AMD
927 processors will be enabled.
929 config MICROCODE_OLD_INTERFACE
934 tristate "/dev/cpu/*/msr - Model-specific register support"
936 This device gives privileged processes access to the x86
937 Model-Specific Registers (MSRs). It is a character device with
938 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
939 MSR accesses are directed to a specific CPU on multi-processor
943 tristate "/dev/cpu/*/cpuid - CPU information support"
945 This device gives processes access to the x86 CPUID instruction to
946 be executed on a specific processor. It is a character device
947 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
951 tristate "/sys/kernel/debug/x86/cpu/* - CPU Debug support"
953 If you select this option, this will provide various x86 CPUs
954 information through debugfs.
957 prompt "High Memory Support"
958 default HIGHMEM4G if !X86_NUMAQ
959 default HIGHMEM64G if X86_NUMAQ
964 depends on !X86_NUMAQ
966 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
967 However, the address space of 32-bit x86 processors is only 4
968 Gigabytes large. That means that, if you have a large amount of
969 physical memory, not all of it can be "permanently mapped" by the
970 kernel. The physical memory that's not permanently mapped is called
973 If you are compiling a kernel which will never run on a machine with
974 more than 1 Gigabyte total physical RAM, answer "off" here (default
975 choice and suitable for most users). This will result in a "3GB/1GB"
976 split: 3GB are mapped so that each process sees a 3GB virtual memory
977 space and the remaining part of the 4GB virtual memory space is used
978 by the kernel to permanently map as much physical memory as
981 If the machine has between 1 and 4 Gigabytes physical RAM, then
984 If more than 4 Gigabytes is used then answer "64GB" here. This
985 selection turns Intel PAE (Physical Address Extension) mode on.
986 PAE implements 3-level paging on IA32 processors. PAE is fully
987 supported by Linux, PAE mode is implemented on all recent Intel
988 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
989 then the kernel will not boot on CPUs that don't support PAE!
991 The actual amount of total physical memory will either be
992 auto detected or can be forced by using a kernel command line option
993 such as "mem=256M". (Try "man bootparam" or see the documentation of
994 your boot loader (lilo or loadlin) about how to pass options to the
995 kernel at boot time.)
997 If unsure, say "off".
1001 depends on !X86_NUMAQ
1003 Select this if you have a 32-bit processor and between 1 and 4
1004 gigabytes of physical RAM.
1008 depends on !M386 && !M486
1011 Select this if you have a 32-bit processor and more than 4
1012 gigabytes of physical RAM.
1017 depends on EXPERIMENTAL
1018 prompt "Memory split" if EMBEDDED
1022 Select the desired split between kernel and user memory.
1024 If the address range available to the kernel is less than the
1025 physical memory installed, the remaining memory will be available
1026 as "high memory". Accessing high memory is a little more costly
1027 than low memory, as it needs to be mapped into the kernel first.
1028 Note that increasing the kernel address space limits the range
1029 available to user programs, making the address space there
1030 tighter. Selecting anything other than the default 3G/1G split
1031 will also likely make your kernel incompatible with binary-only
1034 If you are not absolutely sure what you are doing, leave this
1038 bool "3G/1G user/kernel split"
1039 config VMSPLIT_3G_OPT
1041 bool "3G/1G user/kernel split (for full 1G low memory)"
1043 bool "2G/2G user/kernel split"
1044 config VMSPLIT_2G_OPT
1046 bool "2G/2G user/kernel split (for full 2G low memory)"
1048 bool "1G/3G user/kernel split"
1053 default 0xB0000000 if VMSPLIT_3G_OPT
1054 default 0x80000000 if VMSPLIT_2G
1055 default 0x78000000 if VMSPLIT_2G_OPT
1056 default 0x40000000 if VMSPLIT_1G
1062 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1065 bool "PAE (Physical Address Extension) Support"
1066 depends on X86_32 && !HIGHMEM4G
1068 PAE is required for NX support, and furthermore enables
1069 larger swapspace support for non-overcommit purposes. It
1070 has the cost of more pagetable lookup overhead, and also
1071 consumes more pagetable space per process.
1073 config ARCH_PHYS_ADDR_T_64BIT
1074 def_bool X86_64 || X86_PAE
1076 config DIRECT_GBPAGES
1077 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1081 Allow the kernel linear mapping to use 1GB pages on CPUs that
1082 support it. This can improve the kernel's performance a tiny bit by
1083 reducing TLB pressure. If in doubt, say "Y".
1085 # Common NUMA Features
1087 bool "Numa Memory Allocation and Scheduler Support"
1089 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1090 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1092 Enable NUMA (Non Uniform Memory Access) support.
1094 The kernel will try to allocate memory used by a CPU on the
1095 local memory controller of the CPU and add some more
1096 NUMA awareness to the kernel.
1098 For 64-bit this is recommended if the system is Intel Core i7
1099 (or later), AMD Opteron, or EM64T NUMA.
1101 For 32-bit this is only needed on (rare) 32-bit-only platforms
1102 that support NUMA topologies, such as NUMAQ / Summit, or if you
1103 boot a 32-bit kernel on a 64-bit NUMA platform.
1105 Otherwise, you should say N.
1107 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1108 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1112 prompt "Old style AMD Opteron NUMA detection"
1113 depends on X86_64 && NUMA && PCI
1115 Enable K8 NUMA node topology detection. You should say Y here if
1116 you have a multi processor AMD K8 system. This uses an old
1117 method to read the NUMA configuration directly from the builtin
1118 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1119 instead, which also takes priority if both are compiled in.
1121 config X86_64_ACPI_NUMA
1123 prompt "ACPI NUMA detection"
1124 depends on X86_64 && NUMA && ACPI && PCI
1127 Enable ACPI SRAT based node topology detection.
1129 # Some NUMA nodes have memory ranges that span
1130 # other nodes. Even though a pfn is valid and
1131 # between a node's start and end pfns, it may not
1132 # reside on that node. See memmap_init_zone()
1134 config NODES_SPAN_OTHER_NODES
1136 depends on X86_64_ACPI_NUMA
1139 bool "NUMA emulation"
1140 depends on X86_64 && NUMA
1142 Enable NUMA emulation. A flat machine will be split
1143 into virtual nodes when booted with "numa=fake=N", where N is the
1144 number of nodes. This is only useful for debugging.
1147 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1149 default "9" if MAXSMP
1150 default "6" if X86_64
1151 default "4" if X86_NUMAQ
1153 depends on NEED_MULTIPLE_NODES
1155 Specify the maximum number of NUMA Nodes available on the target
1156 system. Increases memory reserved to accommodate various tables.
1158 config HAVE_ARCH_BOOTMEM
1160 depends on X86_32 && NUMA
1162 config ARCH_HAVE_MEMORY_PRESENT
1164 depends on X86_32 && DISCONTIGMEM
1166 config NEED_NODE_MEMMAP_SIZE
1168 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1170 config HAVE_ARCH_ALLOC_REMAP
1172 depends on X86_32 && NUMA
1174 config ARCH_FLATMEM_ENABLE
1176 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1178 config ARCH_DISCONTIGMEM_ENABLE
1180 depends on NUMA && X86_32
1182 config ARCH_DISCONTIGMEM_DEFAULT
1184 depends on NUMA && X86_32
1186 config ARCH_SPARSEMEM_DEFAULT
1190 config ARCH_SPARSEMEM_ENABLE
1192 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1193 select SPARSEMEM_STATIC if X86_32
1194 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1196 config ARCH_SELECT_MEMORY_MODEL
1198 depends on ARCH_SPARSEMEM_ENABLE
1200 config ARCH_MEMORY_PROBE
1202 depends on MEMORY_HOTPLUG
1207 bool "Allocate 3rd-level pagetables from highmem"
1208 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1210 The VM uses one page table entry for each page of physical memory.
1211 For systems with a lot of RAM, this can be wasteful of precious
1212 low memory. Setting this option will put user-space page table
1213 entries in high memory.
1215 config X86_CHECK_BIOS_CORRUPTION
1216 bool "Check for low memory corruption"
1218 Periodically check for memory corruption in low memory, which
1219 is suspected to be caused by BIOS. Even when enabled in the
1220 configuration, it is disabled at runtime. Enable it by
1221 setting "memory_corruption_check=1" on the kernel command
1222 line. By default it scans the low 64k of memory every 60
1223 seconds; see the memory_corruption_check_size and
1224 memory_corruption_check_period parameters in
1225 Documentation/kernel-parameters.txt to adjust this.
1227 When enabled with the default parameters, this option has
1228 almost no overhead, as it reserves a relatively small amount
1229 of memory and scans it infrequently. It both detects corruption
1230 and prevents it from affecting the running system.
1232 It is, however, intended as a diagnostic tool; if repeatable
1233 BIOS-originated corruption always affects the same memory,
1234 you can use memmap= to prevent the kernel from using that
1237 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1238 bool "Set the default setting of memory_corruption_check"
1239 depends on X86_CHECK_BIOS_CORRUPTION
1242 Set whether the default state of memory_corruption_check is
1245 config X86_RESERVE_LOW_64K
1246 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1249 Reserve the first 64K of physical RAM on BIOSes that are known
1250 to potentially corrupt that memory range. A numbers of BIOSes are
1251 known to utilize this area during suspend/resume, so it must not
1252 be used by the kernel.
1254 Set this to N if you are absolutely sure that you trust the BIOS
1255 to get all its memory reservations and usages right.
1257 If you have doubts about the BIOS (e.g. suspend/resume does not
1258 work or there's kernel crashes after certain hardware hotplug
1259 events) and it's not AMI or Phoenix, then you might want to enable
1260 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1261 corruption patterns.
1265 config MATH_EMULATION
1267 prompt "Math emulation" if X86_32
1269 Linux can emulate a math coprocessor (used for floating point
1270 operations) if you don't have one. 486DX and Pentium processors have
1271 a math coprocessor built in, 486SX and 386 do not, unless you added
1272 a 487DX or 387, respectively. (The messages during boot time can
1273 give you some hints here ["man dmesg"].) Everyone needs either a
1274 coprocessor or this emulation.
1276 If you don't have a math coprocessor, you need to say Y here; if you
1277 say Y here even though you have a coprocessor, the coprocessor will
1278 be used nevertheless. (This behavior can be changed with the kernel
1279 command line option "no387", which comes handy if your coprocessor
1280 is broken. Try "man bootparam" or see the documentation of your boot
1281 loader (lilo or loadlin) about how to pass options to the kernel at
1282 boot time.) This means that it is a good idea to say Y here if you
1283 intend to use this kernel on different machines.
1285 More information about the internals of the Linux math coprocessor
1286 emulation can be found in <file:arch/x86/math-emu/README>.
1288 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1289 kernel, it won't hurt.
1292 bool "MTRR (Memory Type Range Register) support"
1294 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1295 the Memory Type Range Registers (MTRRs) may be used to control
1296 processor access to memory ranges. This is most useful if you have
1297 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1298 allows bus write transfers to be combined into a larger transfer
1299 before bursting over the PCI/AGP bus. This can increase performance
1300 of image write operations 2.5 times or more. Saying Y here creates a
1301 /proc/mtrr file which may be used to manipulate your processor's
1302 MTRRs. Typically the X server should use this.
1304 This code has a reasonably generic interface so that similar
1305 control registers on other processors can be easily supported
1308 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1309 Registers (ARRs) which provide a similar functionality to MTRRs. For
1310 these, the ARRs are used to emulate the MTRRs.
1311 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1312 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1313 write-combining. All of these processors are supported by this code
1314 and it makes sense to say Y here if you have one of them.
1316 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1317 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1318 can lead to all sorts of problems, so it's good to say Y here.
1320 You can safely say Y even if your machine doesn't have MTRRs, you'll
1321 just add about 9 KB to your kernel.
1323 See <file:Documentation/x86/mtrr.txt> for more information.
1325 config MTRR_SANITIZER
1327 prompt "MTRR cleanup support"
1330 Convert MTRR layout from continuous to discrete, so X drivers can
1331 add writeback entries.
1333 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1334 The largest mtrr entry size for a continuous block can be set with
1339 config MTRR_SANITIZER_ENABLE_DEFAULT
1340 int "MTRR cleanup enable value (0-1)"
1343 depends on MTRR_SANITIZER
1345 Enable mtrr cleanup default value
1347 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1348 int "MTRR cleanup spare reg num (0-7)"
1351 depends on MTRR_SANITIZER
1353 mtrr cleanup spare entries default, it can be changed via
1354 mtrr_spare_reg_nr=N on the kernel command line.
1358 prompt "x86 PAT support"
1361 Use PAT attributes to setup page level cache control.
1363 PATs are the modern equivalents of MTRRs and are much more
1364 flexible than MTRRs.
1366 Say N here if you see bootup problems (boot crash, boot hang,
1367 spontaneous reboots) or a non-working video driver.
1372 bool "EFI runtime service support"
1375 This enables the kernel to use EFI runtime services that are
1376 available (such as the EFI variable services).
1378 This option is only useful on systems that have EFI firmware.
1379 In addition, you should use the latest ELILO loader available
1380 at <http://elilo.sourceforge.net> in order to take advantage
1381 of EFI runtime services. However, even with this option, the
1382 resultant kernel should continue to boot on existing non-EFI
1387 prompt "Enable seccomp to safely compute untrusted bytecode"
1389 This kernel feature is useful for number crunching applications
1390 that may need to compute untrusted bytecode during their
1391 execution. By using pipes or other transports made available to
1392 the process as file descriptors supporting the read/write
1393 syscalls, it's possible to isolate those applications in
1394 their own address space using seccomp. Once seccomp is
1395 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1396 and the task is only allowed to execute a few safe syscalls
1397 defined by each seccomp mode.
1399 If unsure, say Y. Only embedded should say N here.
1401 config CC_STACKPROTECTOR_ALL
1404 config CC_STACKPROTECTOR
1405 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1406 select CC_STACKPROTECTOR_ALL
1408 This option turns on the -fstack-protector GCC feature. This
1409 feature puts, at the beginning of functions, a canary value on
1410 the stack just before the return address, and validates
1411 the value just before actually returning. Stack based buffer
1412 overflows (that need to overwrite this return address) now also
1413 overwrite the canary, which gets detected and the attack is then
1414 neutralized via a kernel panic.
1416 This feature requires gcc version 4.2 or above, or a distribution
1417 gcc with the feature backported. Older versions are automatically
1418 detected and for those versions, this configuration option is
1419 ignored. (and a warning is printed during bootup)
1421 source kernel/Kconfig.hz
1424 bool "kexec system call"
1426 kexec is a system call that implements the ability to shutdown your
1427 current kernel, and to start another kernel. It is like a reboot
1428 but it is independent of the system firmware. And like a reboot
1429 you can start any kernel with it, not just Linux.
1431 The name comes from the similarity to the exec system call.
1433 It is an ongoing process to be certain the hardware in a machine
1434 is properly shutdown, so do not be surprised if this code does not
1435 initially work for you. It may help to enable device hotplugging
1436 support. As of this writing the exact hardware interface is
1437 strongly in flux, so no good recommendation can be made.
1440 bool "kernel crash dumps"
1441 depends on X86_64 || (X86_32 && HIGHMEM)
1443 Generate crash dump after being started by kexec.
1444 This should be normally only set in special crash dump kernels
1445 which are loaded in the main kernel with kexec-tools into
1446 a specially reserved region and then later executed after
1447 a crash by kdump/kexec. The crash dump kernel must be compiled
1448 to a memory address not used by the main kernel or BIOS using
1449 PHYSICAL_START, or it must be built as a relocatable image
1450 (CONFIG_RELOCATABLE=y).
1451 For more details see Documentation/kdump/kdump.txt
1454 bool "kexec jump (EXPERIMENTAL)"
1455 depends on EXPERIMENTAL
1456 depends on KEXEC && HIBERNATION
1458 Jump between original kernel and kexeced kernel and invoke
1459 code in physical address mode via KEXEC
1461 config PHYSICAL_START
1462 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1463 default "0x1000000" if X86_NUMAQ
1464 default "0x200000" if X86_64
1467 This gives the physical address where the kernel is loaded.
1469 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1470 bzImage will decompress itself to above physical address and
1471 run from there. Otherwise, bzImage will run from the address where
1472 it has been loaded by the boot loader and will ignore above physical
1475 In normal kdump cases one does not have to set/change this option
1476 as now bzImage can be compiled as a completely relocatable image
1477 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1478 address. This option is mainly useful for the folks who don't want
1479 to use a bzImage for capturing the crash dump and want to use a
1480 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1481 to be specifically compiled to run from a specific memory area
1482 (normally a reserved region) and this option comes handy.
1484 So if you are using bzImage for capturing the crash dump, leave
1485 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1486 Otherwise if you plan to use vmlinux for capturing the crash dump
1487 change this value to start of the reserved region (Typically 16MB
1488 0x1000000). In other words, it can be set based on the "X" value as
1489 specified in the "crashkernel=YM@XM" command line boot parameter
1490 passed to the panic-ed kernel. Typically this parameter is set as
1491 crashkernel=64M@16M. Please take a look at
1492 Documentation/kdump/kdump.txt for more details about crash dumps.
1494 Usage of bzImage for capturing the crash dump is recommended as
1495 one does not have to build two kernels. Same kernel can be used
1496 as production kernel and capture kernel. Above option should have
1497 gone away after relocatable bzImage support is introduced. But it
1498 is present because there are users out there who continue to use
1499 vmlinux for dump capture. This option should go away down the
1502 Don't change this unless you know what you are doing.
1505 bool "Build a relocatable kernel (EXPERIMENTAL)"
1506 depends on EXPERIMENTAL
1508 This builds a kernel image that retains relocation information
1509 so it can be loaded someplace besides the default 1MB.
1510 The relocations tend to make the kernel binary about 10% larger,
1511 but are discarded at runtime.
1513 One use is for the kexec on panic case where the recovery kernel
1514 must live at a different physical address than the primary
1517 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1518 it has been loaded at and the compile time physical address
1519 (CONFIG_PHYSICAL_START) is ignored.
1521 config PHYSICAL_ALIGN
1523 prompt "Alignment value to which kernel should be aligned" if X86_32
1524 default "0x100000" if X86_32
1525 default "0x200000" if X86_64
1526 range 0x2000 0x400000
1528 This value puts the alignment restrictions on physical address
1529 where kernel is loaded and run from. Kernel is compiled for an
1530 address which meets above alignment restriction.
1532 If bootloader loads the kernel at a non-aligned address and
1533 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1534 address aligned to above value and run from there.
1536 If bootloader loads the kernel at a non-aligned address and
1537 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1538 load address and decompress itself to the address it has been
1539 compiled for and run from there. The address for which kernel is
1540 compiled already meets above alignment restrictions. Hence the
1541 end result is that kernel runs from a physical address meeting
1542 above alignment restrictions.
1544 Don't change this unless you know what you are doing.
1547 bool "Support for hot-pluggable CPUs"
1548 depends on SMP && HOTPLUG
1550 Say Y here to allow turning CPUs off and on. CPUs can be
1551 controlled through /sys/devices/system/cpu.
1552 ( Note: power management support will enable this option
1553 automatically on SMP systems. )
1554 Say N if you want to disable CPU hotplug.
1558 prompt "Compat VDSO support"
1559 depends on X86_32 || IA32_EMULATION
1561 Map the 32-bit VDSO to the predictable old-style address too.
1563 Say N here if you are running a sufficiently recent glibc
1564 version (2.3.3 or later), to remove the high-mapped
1565 VDSO mapping and to exclusively use the randomized VDSO.
1570 bool "Built-in kernel command line"
1573 Allow for specifying boot arguments to the kernel at
1574 build time. On some systems (e.g. embedded ones), it is
1575 necessary or convenient to provide some or all of the
1576 kernel boot arguments with the kernel itself (that is,
1577 to not rely on the boot loader to provide them.)
1579 To compile command line arguments into the kernel,
1580 set this option to 'Y', then fill in the
1581 the boot arguments in CONFIG_CMDLINE.
1583 Systems with fully functional boot loaders (i.e. non-embedded)
1584 should leave this option set to 'N'.
1587 string "Built-in kernel command string"
1588 depends on CMDLINE_BOOL
1591 Enter arguments here that should be compiled into the kernel
1592 image and used at boot time. If the boot loader provides a
1593 command line at boot time, it is appended to this string to
1594 form the full kernel command line, when the system boots.
1596 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1597 change this behavior.
1599 In most cases, the command line (whether built-in or provided
1600 by the boot loader) should specify the device for the root
1603 config CMDLINE_OVERRIDE
1604 bool "Built-in command line overrides boot loader arguments"
1606 depends on CMDLINE_BOOL
1608 Set this option to 'Y' to have the kernel ignore the boot loader
1609 command line, and use ONLY the built-in command line.
1611 This is used to work around broken boot loaders. This should
1612 be set to 'N' under normal conditions.
1616 config ARCH_ENABLE_MEMORY_HOTPLUG
1618 depends on X86_64 || (X86_32 && HIGHMEM)
1620 config ARCH_ENABLE_MEMORY_HOTREMOVE
1622 depends on MEMORY_HOTPLUG
1624 config HAVE_ARCH_EARLY_PFN_TO_NID
1628 menu "Power management and ACPI options"
1630 config ARCH_HIBERNATION_HEADER
1632 depends on X86_64 && HIBERNATION
1634 source "kernel/power/Kconfig"
1636 source "drivers/acpi/Kconfig"
1641 depends on APM || APM_MODULE
1644 tristate "APM (Advanced Power Management) BIOS support"
1645 depends on X86_32 && PM_SLEEP
1647 APM is a BIOS specification for saving power using several different
1648 techniques. This is mostly useful for battery powered laptops with
1649 APM compliant BIOSes. If you say Y here, the system time will be
1650 reset after a RESUME operation, the /proc/apm device will provide
1651 battery status information, and user-space programs will receive
1652 notification of APM "events" (e.g. battery status change).
1654 If you select "Y" here, you can disable actual use of the APM
1655 BIOS by passing the "apm=off" option to the kernel at boot time.
1657 Note that the APM support is almost completely disabled for
1658 machines with more than one CPU.
1660 In order to use APM, you will need supporting software. For location
1661 and more information, read <file:Documentation/power/pm.txt> and the
1662 Battery Powered Linux mini-HOWTO, available from
1663 <http://www.tldp.org/docs.html#howto>.
1665 This driver does not spin down disk drives (see the hdparm(8)
1666 manpage ("man 8 hdparm") for that), and it doesn't turn off
1667 VESA-compliant "green" monitors.
1669 This driver does not support the TI 4000M TravelMate and the ACER
1670 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1671 desktop machines also don't have compliant BIOSes, and this driver
1672 may cause those machines to panic during the boot phase.
1674 Generally, if you don't have a battery in your machine, there isn't
1675 much point in using this driver and you should say N. If you get
1676 random kernel OOPSes or reboots that don't seem to be related to
1677 anything, try disabling/enabling this option (or disabling/enabling
1680 Some other things you should try when experiencing seemingly random,
1683 1) make sure that you have enough swap space and that it is
1685 2) pass the "no-hlt" option to the kernel
1686 3) switch on floating point emulation in the kernel and pass
1687 the "no387" option to the kernel
1688 4) pass the "floppy=nodma" option to the kernel
1689 5) pass the "mem=4M" option to the kernel (thereby disabling
1690 all but the first 4 MB of RAM)
1691 6) make sure that the CPU is not over clocked.
1692 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1693 8) disable the cache from your BIOS settings
1694 9) install a fan for the video card or exchange video RAM
1695 10) install a better fan for the CPU
1696 11) exchange RAM chips
1697 12) exchange the motherboard.
1699 To compile this driver as a module, choose M here: the
1700 module will be called apm.
1704 config APM_IGNORE_USER_SUSPEND
1705 bool "Ignore USER SUSPEND"
1707 This option will ignore USER SUSPEND requests. On machines with a
1708 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1709 series notebooks, it is necessary to say Y because of a BIOS bug.
1711 config APM_DO_ENABLE
1712 bool "Enable PM at boot time"
1714 Enable APM features at boot time. From page 36 of the APM BIOS
1715 specification: "When disabled, the APM BIOS does not automatically
1716 power manage devices, enter the Standby State, enter the Suspend
1717 State, or take power saving steps in response to CPU Idle calls."
1718 This driver will make CPU Idle calls when Linux is idle (unless this
1719 feature is turned off -- see "Do CPU IDLE calls", below). This
1720 should always save battery power, but more complicated APM features
1721 will be dependent on your BIOS implementation. You may need to turn
1722 this option off if your computer hangs at boot time when using APM
1723 support, or if it beeps continuously instead of suspending. Turn
1724 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1725 T400CDT. This is off by default since most machines do fine without
1729 bool "Make CPU Idle calls when idle"
1731 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1732 On some machines, this can activate improved power savings, such as
1733 a slowed CPU clock rate, when the machine is idle. These idle calls
1734 are made after the idle loop has run for some length of time (e.g.,
1735 333 mS). On some machines, this will cause a hang at boot time or
1736 whenever the CPU becomes idle. (On machines with more than one CPU,
1737 this option does nothing.)
1739 config APM_DISPLAY_BLANK
1740 bool "Enable console blanking using APM"
1742 Enable console blanking using the APM. Some laptops can use this to
1743 turn off the LCD backlight when the screen blanker of the Linux
1744 virtual console blanks the screen. Note that this is only used by
1745 the virtual console screen blanker, and won't turn off the backlight
1746 when using the X Window system. This also doesn't have anything to
1747 do with your VESA-compliant power-saving monitor. Further, this
1748 option doesn't work for all laptops -- it might not turn off your
1749 backlight at all, or it might print a lot of errors to the console,
1750 especially if you are using gpm.
1752 config APM_ALLOW_INTS
1753 bool "Allow interrupts during APM BIOS calls"
1755 Normally we disable external interrupts while we are making calls to
1756 the APM BIOS as a measure to lessen the effects of a badly behaving
1757 BIOS implementation. The BIOS should reenable interrupts if it
1758 needs to. Unfortunately, some BIOSes do not -- especially those in
1759 many of the newer IBM Thinkpads. If you experience hangs when you
1760 suspend, try setting this to Y. Otherwise, say N.
1764 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1766 source "drivers/cpuidle/Kconfig"
1768 source "drivers/idle/Kconfig"
1773 menu "Bus options (PCI etc.)"
1778 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1780 Find out whether you have a PCI motherboard. PCI is the name of a
1781 bus system, i.e. the way the CPU talks to the other stuff inside
1782 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1783 VESA. If you have PCI, say Y, otherwise N.
1786 prompt "PCI access mode"
1787 depends on X86_32 && PCI
1790 On PCI systems, the BIOS can be used to detect the PCI devices and
1791 determine their configuration. However, some old PCI motherboards
1792 have BIOS bugs and may crash if this is done. Also, some embedded
1793 PCI-based systems don't have any BIOS at all. Linux can also try to
1794 detect the PCI hardware directly without using the BIOS.
1796 With this option, you can specify how Linux should detect the
1797 PCI devices. If you choose "BIOS", the BIOS will be used,
1798 if you choose "Direct", the BIOS won't be used, and if you
1799 choose "MMConfig", then PCI Express MMCONFIG will be used.
1800 If you choose "Any", the kernel will try MMCONFIG, then the
1801 direct access method and falls back to the BIOS if that doesn't
1802 work. If unsure, go with the default, which is "Any".
1807 config PCI_GOMMCONFIG
1824 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1826 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1829 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1833 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1837 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1844 bool "Support mmconfig PCI config space access"
1845 depends on X86_64 && PCI && ACPI
1848 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1849 depends on PCI_MSI && ACPI && EXPERIMENTAL
1851 DMA remapping (DMAR) devices support enables independent address
1852 translations for Direct Memory Access (DMA) from devices.
1853 These DMA remapping devices are reported via ACPI tables
1854 and include PCI device scope covered by these DMA
1857 config DMAR_DEFAULT_ON
1859 prompt "Enable DMA Remapping Devices by default"
1862 Selecting this option will enable a DMAR device at boot time if
1863 one is found. If this option is not selected, DMAR support can
1864 be enabled by passing intel_iommu=on to the kernel. It is
1865 recommended you say N here while the DMAR code remains
1870 prompt "Support for Graphics workaround"
1873 Current Graphics drivers tend to use physical address
1874 for DMA and avoid using DMA APIs. Setting this config
1875 option permits the IOMMU driver to set a unity map for
1876 all the OS-visible memory. Hence the driver can continue
1877 to use physical addresses for DMA.
1879 config DMAR_FLOPPY_WA
1883 Floppy disk drivers are know to bypass DMA API calls
1884 thereby failing to work when IOMMU is enabled. This
1885 workaround will setup a 1:1 mapping for the first
1886 16M to make floppy (an ISA device) work.
1889 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1890 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1892 Supports Interrupt remapping for IO-APIC and MSI devices.
1893 To use x2apic mode in the CPU's which support x2APIC enhancements or
1894 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1896 source "drivers/pci/pcie/Kconfig"
1898 source "drivers/pci/Kconfig"
1900 # x86_64 have no ISA slots, but do have ISA-style DMA.
1909 Find out whether you have ISA slots on your motherboard. ISA is the
1910 name of a bus system, i.e. the way the CPU talks to the other stuff
1911 inside your box. Other bus systems are PCI, EISA, MicroChannel
1912 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1913 newer boards don't support it. If you have ISA, say Y, otherwise N.
1919 The Extended Industry Standard Architecture (EISA) bus was
1920 developed as an open alternative to the IBM MicroChannel bus.
1922 The EISA bus provided some of the features of the IBM MicroChannel
1923 bus while maintaining backward compatibility with cards made for
1924 the older ISA bus. The EISA bus saw limited use between 1988 and
1925 1995 when it was made obsolete by the PCI bus.
1927 Say Y here if you are building a kernel for an EISA-based machine.
1931 source "drivers/eisa/Kconfig"
1936 MicroChannel Architecture is found in some IBM PS/2 machines and
1937 laptops. It is a bus system similar to PCI or ISA. See
1938 <file:Documentation/mca.txt> (and especially the web page given
1939 there) before attempting to build an MCA bus kernel.
1941 source "drivers/mca/Kconfig"
1944 tristate "NatSemi SCx200 support"
1946 This provides basic support for National Semiconductor's
1947 (now AMD's) Geode processors. The driver probes for the
1948 PCI-IDs of several on-chip devices, so its a good dependency
1949 for other scx200_* drivers.
1951 If compiled as a module, the driver is named scx200.
1953 config SCx200HR_TIMER
1954 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1955 depends on SCx200 && GENERIC_TIME
1958 This driver provides a clocksource built upon the on-chip
1959 27MHz high-resolution timer. Its also a workaround for
1960 NSC Geode SC-1100's buggy TSC, which loses time when the
1961 processor goes idle (as is done by the scheduler). The
1962 other workaround is idle=poll boot option.
1964 config GEODE_MFGPT_TIMER
1966 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1967 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1969 This driver provides a clock event source based on the MFGPT
1970 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1971 MFGPTs have a better resolution and max interval than the
1972 generic PIT, and are suitable for use as high-res timers.
1975 bool "One Laptop Per Child support"
1978 Add support for detecting the unique features of the OLPC
1985 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1987 source "drivers/pcmcia/Kconfig"
1989 source "drivers/pci/hotplug/Kconfig"
1994 menu "Executable file formats / Emulations"
1996 source "fs/Kconfig.binfmt"
1998 config IA32_EMULATION
1999 bool "IA32 Emulation"
2001 select COMPAT_BINFMT_ELF
2003 Include code to run 32-bit programs under a 64-bit kernel. You should
2004 likely turn this on, unless you're 100% sure that you don't have any
2005 32-bit programs left.
2008 tristate "IA32 a.out support"
2009 depends on IA32_EMULATION
2011 Support old a.out binaries in the 32bit emulation.
2015 depends on IA32_EMULATION
2017 config COMPAT_FOR_U64_ALIGNMENT
2021 config SYSVIPC_COMPAT
2023 depends on COMPAT && SYSVIPC
2028 config HAVE_ATOMIC_IOMAP
2032 source "net/Kconfig"
2034 source "drivers/Kconfig"
2036 source "drivers/firmware/Kconfig"
2040 source "arch/x86/Kconfig.debug"
2042 source "security/Kconfig"
2044 source "crypto/Kconfig"
2046 source "arch/x86/kvm/Kconfig"
2048 source "lib/Kconfig"
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob