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
258 This enables x2apic support on CPUs that have this feature.
260 This allows 32-bit apic IDs (so it can support very large systems),
261 and accesses the local apic via MSRs not via mmio.
263 ( On certain CPU models you may need to enable INTR_REMAP too,
264 to get functional x2apic mode. )
266 If you don't know what to do here, say N.
269 bool "Support sparse irq numbering"
270 depends on PCI_MSI || HT_IRQ
272 This enables support for sparse irqs. This is useful for distro
273 kernels that want to define a high CONFIG_NR_CPUS value but still
274 want to have low kernel memory footprint on smaller machines.
276 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
277 out the irq_desc[] array in a more NUMA-friendly way. )
279 If you don't know what to do here, say N.
281 config NUMA_MIGRATE_IRQ_DESC
282 bool "Move irq desc when changing irq smp_affinity"
283 depends on SPARSE_IRQ && NUMA
286 This enables moving irq_desc to cpu/node that irq will use handled.
288 If you don't know what to do here, say N.
291 bool "Enable MPS table" if ACPI
293 depends on X86_LOCAL_APIC
295 For old smp systems that do not have proper acpi support. Newer systems
296 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
299 bool "Support for big SMP systems with more than 8 CPUs"
300 depends on X86_32 && SMP
302 This option is needed for the systems that have more than 8 CPUs
305 config X86_EXTENDED_PLATFORM
306 bool "Support for extended (non-PC) x86 platforms"
309 If you disable this option then the kernel will only support
310 standard PC platforms. (which covers the vast majority of
313 If you enable this option then you'll be able to select support
314 for the following (non-PC) 32 bit x86 platforms:
318 SGI 320/540 (Visual Workstation)
319 Summit/EXA (IBM x440)
320 Unisys ES7000 IA32 series
322 If you have one of these systems, or if you want to build a
323 generic distribution kernel, say Y here - otherwise say N.
327 config X86_EXTENDED_PLATFORM
328 bool "Support for extended (non-PC) x86 platforms"
331 If you disable this option then the kernel will only support
332 standard PC platforms. (which covers the vast majority of
335 If you enable this option then you'll be able to select support
336 for the following (non-PC) 64 bit x86 platforms:
340 If you have one of these systems, or if you want to build a
341 generic distribution kernel, say Y here - otherwise say N.
343 # This is an alphabetically sorted list of 64 bit extended platforms
344 # Please maintain the alphabetic order if and when there are additions
349 depends on X86_64 && PCI
350 depends on X86_EXTENDED_PLATFORM
352 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
353 supposed to run on these EM64T-based machines. Only choose this option
354 if you have one of these machines.
357 bool "SGI Ultraviolet"
359 depends on X86_EXTENDED_PLATFORM
362 This option is needed in order to support SGI Ultraviolet systems.
363 If you don't have one of these, you should say N here.
365 # Following is an alphabetically sorted list of 32 bit extended platforms
366 # Please maintain the alphabetic order if and when there are additions
371 depends on X86_EXTENDED_PLATFORM
373 Select this for an AMD Elan processor.
375 Do not use this option for K6/Athlon/Opteron processors!
377 If unsure, choose "PC-compatible" instead.
380 bool "RDC R-321x SoC"
382 depends on X86_EXTENDED_PLATFORM
384 select X86_REBOOTFIXUPS
386 This option is needed for RDC R-321x system-on-chip, also known
388 If you don't have one of these chips, you should say N here.
390 config X86_32_NON_STANDARD
391 bool "Support non-standard 32-bit SMP architectures"
392 depends on X86_32 && SMP
393 depends on X86_EXTENDED_PLATFORM
395 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
396 subarchitectures. It is intended for a generic binary kernel.
397 if you select them all, kernel will probe it one by one. and will
400 # Alphabetically sorted list of Non standard 32 bit platforms
403 bool "NUMAQ (IBM/Sequent)"
404 depends on X86_32_NON_STANDARD
408 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
409 NUMA multiquad box. This changes the way that processors are
410 bootstrapped, and uses Clustered Logical APIC addressing mode instead
411 of Flat Logical. You will need a new lynxer.elf file to flash your
412 firmware with - send email to <Martin.Bligh@us.ibm.com>.
415 bool "SGI 320/540 (Visual Workstation)"
416 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
417 depends on X86_32_NON_STANDARD
419 The SGI Visual Workstation series is an IA32-based workstation
420 based on SGI systems chips with some legacy PC hardware attached.
422 Say Y here to create a kernel to run on the SGI 320 or 540.
424 A kernel compiled for the Visual Workstation will run on general
425 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
428 bool "Summit/EXA (IBM x440)"
429 depends on X86_32_NON_STANDARD
431 This option is needed for IBM systems that use the Summit/EXA chipset.
432 In particular, it is needed for the x440.
435 bool "Unisys ES7000 IA32 series"
436 depends on X86_32_NON_STANDARD && X86_BIGSMP
438 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
439 supposed to run on an IA32-based Unisys ES7000 system.
441 config SCHED_OMIT_FRAME_POINTER
443 prompt "Single-depth WCHAN output"
446 Calculate simpler /proc/<PID>/wchan values. If this option
447 is disabled then wchan values will recurse back to the
448 caller function. This provides more accurate wchan values,
449 at the expense of slightly more scheduling overhead.
451 If in doubt, say "Y".
453 menuconfig PARAVIRT_GUEST
454 bool "Paravirtualized guest support"
456 Say Y here to get to see options related to running Linux under
457 various hypervisors. This option alone does not add any kernel code.
459 If you say N, all options in this submenu will be skipped and disabled.
463 source "arch/x86/xen/Kconfig"
466 bool "VMI Guest support"
470 VMI provides a paravirtualized interface to the VMware ESX server
471 (it could be used by other hypervisors in theory too, but is not
472 at the moment), by linking the kernel to a GPL-ed ROM module
473 provided by the hypervisor.
476 bool "KVM paravirtualized clock"
478 select PARAVIRT_CLOCK
480 Turning on this option will allow you to run a paravirtualized clock
481 when running over the KVM hypervisor. Instead of relying on a PIT
482 (or probably other) emulation by the underlying device model, the host
483 provides the guest with timing infrastructure such as time of day, and
487 bool "KVM Guest support"
490 This option enables various optimizations for running under the KVM
493 source "arch/x86/lguest/Kconfig"
496 bool "Enable paravirtualization code"
498 This changes the kernel so it can modify itself when it is run
499 under a hypervisor, potentially improving performance significantly
500 over full virtualization. However, when run without a hypervisor
501 the kernel is theoretically slower and slightly larger.
503 config PARAVIRT_CLOCK
509 config PARAVIRT_DEBUG
510 bool "paravirt-ops debugging"
511 depends on PARAVIRT && DEBUG_KERNEL
513 Enable to debug paravirt_ops internals. Specifically, BUG if
514 a paravirt_op is missing when it is called.
519 This option adds a kernel parameter 'memtest', which allows memtest
521 memtest=0, mean disabled; -- default
522 memtest=1, mean do 1 test pattern;
524 memtest=4, mean do 4 test patterns.
525 If you are unsure how to answer this question, answer N.
527 config X86_SUMMIT_NUMA
529 depends on X86_32 && NUMA && X86_32_NON_STANDARD
531 config X86_CYCLONE_TIMER
533 depends on X86_32_NON_STANDARD
535 source "arch/x86/Kconfig.cpu"
539 prompt "HPET Timer Support" if X86_32
541 Use the IA-PC HPET (High Precision Event Timer) to manage
542 time in preference to the PIT and RTC, if a HPET is
544 HPET is the next generation timer replacing legacy 8254s.
545 The HPET provides a stable time base on SMP
546 systems, unlike the TSC, but it is more expensive to access,
547 as it is off-chip. You can find the HPET spec at
548 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
550 You can safely choose Y here. However, HPET will only be
551 activated if the platform and the BIOS support this feature.
552 Otherwise the 8254 will be used for timing services.
554 Choose N to continue using the legacy 8254 timer.
556 config HPET_EMULATE_RTC
558 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
560 # Mark as embedded because too many people got it wrong.
561 # The code disables itself when not needed.
564 bool "Enable DMI scanning" if EMBEDDED
566 Enabled scanning of DMI to identify machine quirks. Say Y
567 here unless you have verified that your setup is not
568 affected by entries in the DMI blacklist. Required by PNP
572 bool "GART IOMMU support" if EMBEDDED
576 depends on X86_64 && PCI
578 Support for full DMA access of devices with 32bit memory access only
579 on systems with more than 3GB. This is usually needed for USB,
580 sound, many IDE/SATA chipsets and some other devices.
581 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
582 based hardware IOMMU and a software bounce buffer based IOMMU used
583 on Intel systems and as fallback.
584 The code is only active when needed (enough memory and limited
585 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
589 bool "IBM Calgary IOMMU support"
591 depends on X86_64 && PCI && EXPERIMENTAL
593 Support for hardware IOMMUs in IBM's xSeries x366 and x460
594 systems. Needed to run systems with more than 3GB of memory
595 properly with 32-bit PCI devices that do not support DAC
596 (Double Address Cycle). Calgary also supports bus level
597 isolation, where all DMAs pass through the IOMMU. This
598 prevents them from going anywhere except their intended
599 destination. This catches hard-to-find kernel bugs and
600 mis-behaving drivers and devices that do not use the DMA-API
601 properly to set up their DMA buffers. The IOMMU can be
602 turned off at boot time with the iommu=off parameter.
603 Normally the kernel will make the right choice by itself.
606 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
608 prompt "Should Calgary be enabled by default?"
609 depends on CALGARY_IOMMU
611 Should Calgary be enabled by default? if you choose 'y', Calgary
612 will be used (if it exists). If you choose 'n', Calgary will not be
613 used even if it exists. If you choose 'n' and would like to use
614 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
618 bool "AMD IOMMU support"
621 depends on X86_64 && PCI && ACPI
623 With this option you can enable support for AMD IOMMU hardware in
624 your system. An IOMMU is a hardware component which provides
625 remapping of DMA memory accesses from devices. With an AMD IOMMU you
626 can isolate the the DMA memory of different devices and protect the
627 system from misbehaving device drivers or hardware.
629 You can find out if your system has an AMD IOMMU if you look into
630 your BIOS for an option to enable it or if you have an IVRS ACPI
633 config AMD_IOMMU_STATS
634 bool "Export AMD IOMMU statistics to debugfs"
638 This option enables code in the AMD IOMMU driver to collect various
639 statistics about whats happening in the driver and exports that
640 information to userspace via debugfs.
643 # need this always selected by IOMMU for the VIA workaround
647 Support for software bounce buffers used on x86-64 systems
648 which don't have a hardware IOMMU (e.g. the current generation
649 of Intel's x86-64 CPUs). Using this PCI devices which can only
650 access 32-bits of memory can be used on systems with more than
651 3 GB of memory. If unsure, say Y.
654 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
657 def_bool (AMD_IOMMU || DMAR)
660 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
661 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
662 select CPUMASK_OFFSTACK
665 Configure maximum number of CPUS and NUMA Nodes for this architecture.
669 int "Maximum number of CPUs" if SMP && !MAXSMP
670 range 2 512 if SMP && !MAXSMP
672 default "4096" if MAXSMP
673 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
676 This allows you to specify the maximum number of CPUs which this
677 kernel will support. The maximum supported value is 512 and the
678 minimum value which makes sense is 2.
680 This is purely to save memory - each supported CPU adds
681 approximately eight kilobytes to the kernel image.
684 bool "SMT (Hyperthreading) scheduler support"
687 SMT scheduler support improves the CPU scheduler's decision making
688 when dealing with Intel Pentium 4 chips with HyperThreading at a
689 cost of slightly increased overhead in some places. If unsure say
694 prompt "Multi-core scheduler support"
697 Multi-core scheduler support improves the CPU scheduler's decision
698 making when dealing with multi-core CPU chips at a cost of slightly
699 increased overhead in some places. If unsure say N here.
701 source "kernel/Kconfig.preempt"
704 bool "Local APIC support on uniprocessors"
705 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
707 A local APIC (Advanced Programmable Interrupt Controller) is an
708 integrated interrupt controller in the CPU. If you have a single-CPU
709 system which has a processor with a local APIC, you can say Y here to
710 enable and use it. If you say Y here even though your machine doesn't
711 have a local APIC, then the kernel will still run with no slowdown at
712 all. The local APIC supports CPU-generated self-interrupts (timer,
713 performance counters), and the NMI watchdog which detects hard
717 bool "IO-APIC support on uniprocessors"
718 depends on X86_UP_APIC
720 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
721 SMP-capable replacement for PC-style interrupt controllers. Most
722 SMP systems and many recent uniprocessor systems have one.
724 If you have a single-CPU system with an IO-APIC, you can say Y here
725 to use it. If you say Y here even though your machine doesn't have
726 an IO-APIC, then the kernel will still run with no slowdown at all.
728 config X86_LOCAL_APIC
730 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
731 select HAVE_PERF_COUNTERS if (!M386 && !M486)
735 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
737 config X86_VISWS_APIC
739 depends on X86_32 && X86_VISWS
741 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
742 bool "Reroute for broken boot IRQs"
744 depends on X86_IO_APIC
746 This option enables a workaround that fixes a source of
747 spurious interrupts. This is recommended when threaded
748 interrupt handling is used on systems where the generation of
749 superfluous "boot interrupts" cannot be disabled.
751 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
752 entry in the chipset's IO-APIC is masked (as, e.g. the RT
753 kernel does during interrupt handling). On chipsets where this
754 boot IRQ generation cannot be disabled, this workaround keeps
755 the original IRQ line masked so that only the equivalent "boot
756 IRQ" is delivered to the CPUs. The workaround also tells the
757 kernel to set up the IRQ handler on the boot IRQ line. In this
758 way only one interrupt is delivered to the kernel. Otherwise
759 the spurious second interrupt may cause the kernel to bring
760 down (vital) interrupt lines.
762 Only affects "broken" chipsets. Interrupt sharing may be
763 increased on these systems.
766 bool "Machine Check Exception"
768 Machine Check Exception support allows the processor to notify the
769 kernel if it detects a problem (e.g. overheating, component failure).
770 The action the kernel takes depends on the severity of the problem,
771 ranging from a warning message on the console, to halting the machine.
772 Your processor must be a Pentium or newer to support this - check the
773 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
774 have a design flaw which leads to false MCE events - hence MCE is
775 disabled on all P5 processors, unless explicitly enabled with "mce"
776 as a boot argument. Similarly, if MCE is built in and creates a
777 problem on some new non-standard machine, you can boot with "nomce"
778 to disable it. MCE support simply ignores non-MCE processors like
779 the 386 and 486, so nearly everyone can say Y here.
783 prompt "Intel MCE features"
784 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
786 Additional support for intel specific MCE features such as
791 prompt "AMD MCE features"
792 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
794 Additional support for AMD specific MCE features such as
795 the DRAM Error Threshold.
797 config X86_MCE_THRESHOLD
798 depends on X86_MCE_AMD || X86_MCE_INTEL
802 config X86_MCE_NONFATAL
803 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
804 depends on X86_32 && X86_MCE
806 Enabling this feature starts a timer that triggers every 5 seconds which
807 will look at the machine check registers to see if anything happened.
808 Non-fatal problems automatically get corrected (but still logged).
809 Disable this if you don't want to see these messages.
810 Seeing the messages this option prints out may be indicative of dying
811 or out-of-spec (ie, overclocked) hardware.
812 This option only does something on certain CPUs.
813 (AMD Athlon/Duron and Intel Pentium 4)
815 config X86_MCE_P4THERMAL
816 bool "check for P4 thermal throttling interrupt."
817 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
819 Enabling this feature will cause a message to be printed when the P4
820 enters thermal throttling.
823 bool "Enable VM86 support" if EMBEDDED
827 This option is required by programs like DOSEMU to run 16-bit legacy
828 code on X86 processors. It also may be needed by software like
829 XFree86 to initialize some video cards via BIOS. Disabling this
830 option saves about 6k.
833 tristate "Toshiba Laptop support"
836 This adds a driver to safely access the System Management Mode of
837 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
838 not work on models with a Phoenix BIOS. The System Management Mode
839 is used to set the BIOS and power saving options on Toshiba portables.
841 For information on utilities to make use of this driver see the
842 Toshiba Linux utilities web site at:
843 <http://www.buzzard.org.uk/toshiba/>.
845 Say Y if you intend to run this kernel on a Toshiba portable.
849 tristate "Dell laptop support"
851 This adds a driver to safely access the System Management Mode
852 of the CPU on the Dell Inspiron 8000. The System Management Mode
853 is used to read cpu temperature and cooling fan status and to
854 control the fans on the I8K portables.
856 This driver has been tested only on the Inspiron 8000 but it may
857 also work with other Dell laptops. You can force loading on other
858 models by passing the parameter `force=1' to the module. Use at
861 For information on utilities to make use of this driver see the
862 I8K Linux utilities web site at:
863 <http://people.debian.org/~dz/i8k/>
865 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
868 config X86_REBOOTFIXUPS
869 bool "Enable X86 board specific fixups for reboot"
872 This enables chipset and/or board specific fixups to be done
873 in order to get reboot to work correctly. This is only needed on
874 some combinations of hardware and BIOS. The symptom, for which
875 this config is intended, is when reboot ends with a stalled/hung
878 Currently, the only fixup is for the Geode machines using
879 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
881 Say Y if you want to enable the fixup. Currently, it's safe to
882 enable this option even if you don't need it.
886 tristate "/dev/cpu/microcode - microcode support"
889 If you say Y here, you will be able to update the microcode on
890 certain Intel and AMD processors. The Intel support is for the
891 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
892 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
893 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
894 You will obviously need the actual microcode binary data itself
895 which is not shipped with the Linux kernel.
897 This option selects the general module only, you need to select
898 at least one vendor specific module as well.
900 To compile this driver as a module, choose M here: the
901 module will be called microcode.
903 config MICROCODE_INTEL
904 bool "Intel microcode patch loading support"
909 This options enables microcode patch loading support for Intel
912 For latest news and information on obtaining all the required
913 Intel ingredients for this driver, check:
914 <http://www.urbanmyth.org/microcode/>.
917 bool "AMD microcode patch loading support"
921 If you select this option, microcode patch loading support for AMD
922 processors will be enabled.
924 config MICROCODE_OLD_INTERFACE
929 tristate "/dev/cpu/*/msr - Model-specific register support"
931 This device gives privileged processes access to the x86
932 Model-Specific Registers (MSRs). It is a character device with
933 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
934 MSR accesses are directed to a specific CPU on multi-processor
938 tristate "/dev/cpu/*/cpuid - CPU information support"
940 This device gives processes access to the x86 CPUID instruction to
941 be executed on a specific processor. It is a character device
942 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
946 tristate "/sys/kernel/debug/x86/cpu/* - CPU Debug support"
948 If you select this option, this will provide various x86 CPUs
949 information through debugfs.
952 prompt "High Memory Support"
953 default HIGHMEM4G if !X86_NUMAQ
954 default HIGHMEM64G if X86_NUMAQ
959 depends on !X86_NUMAQ
961 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
962 However, the address space of 32-bit x86 processors is only 4
963 Gigabytes large. That means that, if you have a large amount of
964 physical memory, not all of it can be "permanently mapped" by the
965 kernel. The physical memory that's not permanently mapped is called
968 If you are compiling a kernel which will never run on a machine with
969 more than 1 Gigabyte total physical RAM, answer "off" here (default
970 choice and suitable for most users). This will result in a "3GB/1GB"
971 split: 3GB are mapped so that each process sees a 3GB virtual memory
972 space and the remaining part of the 4GB virtual memory space is used
973 by the kernel to permanently map as much physical memory as
976 If the machine has between 1 and 4 Gigabytes physical RAM, then
979 If more than 4 Gigabytes is used then answer "64GB" here. This
980 selection turns Intel PAE (Physical Address Extension) mode on.
981 PAE implements 3-level paging on IA32 processors. PAE is fully
982 supported by Linux, PAE mode is implemented on all recent Intel
983 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
984 then the kernel will not boot on CPUs that don't support PAE!
986 The actual amount of total physical memory will either be
987 auto detected or can be forced by using a kernel command line option
988 such as "mem=256M". (Try "man bootparam" or see the documentation of
989 your boot loader (lilo or loadlin) about how to pass options to the
990 kernel at boot time.)
992 If unsure, say "off".
996 depends on !X86_NUMAQ
998 Select this if you have a 32-bit processor and between 1 and 4
999 gigabytes of physical RAM.
1003 depends on !M386 && !M486
1006 Select this if you have a 32-bit processor and more than 4
1007 gigabytes of physical RAM.
1012 depends on EXPERIMENTAL
1013 prompt "Memory split" if EMBEDDED
1017 Select the desired split between kernel and user memory.
1019 If the address range available to the kernel is less than the
1020 physical memory installed, the remaining memory will be available
1021 as "high memory". Accessing high memory is a little more costly
1022 than low memory, as it needs to be mapped into the kernel first.
1023 Note that increasing the kernel address space limits the range
1024 available to user programs, making the address space there
1025 tighter. Selecting anything other than the default 3G/1G split
1026 will also likely make your kernel incompatible with binary-only
1029 If you are not absolutely sure what you are doing, leave this
1033 bool "3G/1G user/kernel split"
1034 config VMSPLIT_3G_OPT
1036 bool "3G/1G user/kernel split (for full 1G low memory)"
1038 bool "2G/2G user/kernel split"
1039 config VMSPLIT_2G_OPT
1041 bool "2G/2G user/kernel split (for full 2G low memory)"
1043 bool "1G/3G user/kernel split"
1048 default 0xB0000000 if VMSPLIT_3G_OPT
1049 default 0x80000000 if VMSPLIT_2G
1050 default 0x78000000 if VMSPLIT_2G_OPT
1051 default 0x40000000 if VMSPLIT_1G
1057 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1060 bool "PAE (Physical Address Extension) Support"
1061 depends on X86_32 && !HIGHMEM4G
1063 PAE is required for NX support, and furthermore enables
1064 larger swapspace support for non-overcommit purposes. It
1065 has the cost of more pagetable lookup overhead, and also
1066 consumes more pagetable space per process.
1068 config ARCH_PHYS_ADDR_T_64BIT
1069 def_bool X86_64 || X86_PAE
1071 config DIRECT_GBPAGES
1072 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1076 Allow the kernel linear mapping to use 1GB pages on CPUs that
1077 support it. This can improve the kernel's performance a tiny bit by
1078 reducing TLB pressure. If in doubt, say "Y".
1080 # Common NUMA Features
1082 bool "Numa Memory Allocation and Scheduler Support"
1084 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1085 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1087 Enable NUMA (Non Uniform Memory Access) support.
1089 The kernel will try to allocate memory used by a CPU on the
1090 local memory controller of the CPU and add some more
1091 NUMA awareness to the kernel.
1093 For 64-bit this is recommended if the system is Intel Core i7
1094 (or later), AMD Opteron, or EM64T NUMA.
1096 For 32-bit this is only needed on (rare) 32-bit-only platforms
1097 that support NUMA topologies, such as NUMAQ / Summit, or if you
1098 boot a 32-bit kernel on a 64-bit NUMA platform.
1100 Otherwise, you should say N.
1102 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1103 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1107 prompt "Old style AMD Opteron NUMA detection"
1108 depends on X86_64 && NUMA && PCI
1110 Enable K8 NUMA node topology detection. You should say Y here if
1111 you have a multi processor AMD K8 system. This uses an old
1112 method to read the NUMA configuration directly from the builtin
1113 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1114 instead, which also takes priority if both are compiled in.
1116 config X86_64_ACPI_NUMA
1118 prompt "ACPI NUMA detection"
1119 depends on X86_64 && NUMA && ACPI && PCI
1122 Enable ACPI SRAT based node topology detection.
1124 # Some NUMA nodes have memory ranges that span
1125 # other nodes. Even though a pfn is valid and
1126 # between a node's start and end pfns, it may not
1127 # reside on that node. See memmap_init_zone()
1129 config NODES_SPAN_OTHER_NODES
1131 depends on X86_64_ACPI_NUMA
1134 bool "NUMA emulation"
1135 depends on X86_64 && NUMA
1137 Enable NUMA emulation. A flat machine will be split
1138 into virtual nodes when booted with "numa=fake=N", where N is the
1139 number of nodes. This is only useful for debugging.
1142 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1144 default "9" if MAXSMP
1145 default "6" if X86_64
1146 default "4" if X86_NUMAQ
1148 depends on NEED_MULTIPLE_NODES
1150 Specify the maximum number of NUMA Nodes available on the target
1151 system. Increases memory reserved to accommodate various tables.
1153 config HAVE_ARCH_BOOTMEM
1155 depends on X86_32 && NUMA
1157 config ARCH_HAVE_MEMORY_PRESENT
1159 depends on X86_32 && DISCONTIGMEM
1161 config NEED_NODE_MEMMAP_SIZE
1163 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1165 config HAVE_ARCH_ALLOC_REMAP
1167 depends on X86_32 && NUMA
1169 config ARCH_FLATMEM_ENABLE
1171 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1173 config ARCH_DISCONTIGMEM_ENABLE
1175 depends on NUMA && X86_32
1177 config ARCH_DISCONTIGMEM_DEFAULT
1179 depends on NUMA && X86_32
1181 config ARCH_SPARSEMEM_DEFAULT
1185 config ARCH_SPARSEMEM_ENABLE
1187 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1188 select SPARSEMEM_STATIC if X86_32
1189 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1191 config ARCH_SELECT_MEMORY_MODEL
1193 depends on ARCH_SPARSEMEM_ENABLE
1195 config ARCH_MEMORY_PROBE
1197 depends on MEMORY_HOTPLUG
1202 bool "Allocate 3rd-level pagetables from highmem"
1203 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1205 The VM uses one page table entry for each page of physical memory.
1206 For systems with a lot of RAM, this can be wasteful of precious
1207 low memory. Setting this option will put user-space page table
1208 entries in high memory.
1210 config X86_CHECK_BIOS_CORRUPTION
1211 bool "Check for low memory corruption"
1213 Periodically check for memory corruption in low memory, which
1214 is suspected to be caused by BIOS. Even when enabled in the
1215 configuration, it is disabled at runtime. Enable it by
1216 setting "memory_corruption_check=1" on the kernel command
1217 line. By default it scans the low 64k of memory every 60
1218 seconds; see the memory_corruption_check_size and
1219 memory_corruption_check_period parameters in
1220 Documentation/kernel-parameters.txt to adjust this.
1222 When enabled with the default parameters, this option has
1223 almost no overhead, as it reserves a relatively small amount
1224 of memory and scans it infrequently. It both detects corruption
1225 and prevents it from affecting the running system.
1227 It is, however, intended as a diagnostic tool; if repeatable
1228 BIOS-originated corruption always affects the same memory,
1229 you can use memmap= to prevent the kernel from using that
1232 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1233 bool "Set the default setting of memory_corruption_check"
1234 depends on X86_CHECK_BIOS_CORRUPTION
1237 Set whether the default state of memory_corruption_check is
1240 config X86_RESERVE_LOW_64K
1241 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1244 Reserve the first 64K of physical RAM on BIOSes that are known
1245 to potentially corrupt that memory range. A numbers of BIOSes are
1246 known to utilize this area during suspend/resume, so it must not
1247 be used by the kernel.
1249 Set this to N if you are absolutely sure that you trust the BIOS
1250 to get all its memory reservations and usages right.
1252 If you have doubts about the BIOS (e.g. suspend/resume does not
1253 work or there's kernel crashes after certain hardware hotplug
1254 events) and it's not AMI or Phoenix, then you might want to enable
1255 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1256 corruption patterns.
1260 config MATH_EMULATION
1262 prompt "Math emulation" if X86_32
1264 Linux can emulate a math coprocessor (used for floating point
1265 operations) if you don't have one. 486DX and Pentium processors have
1266 a math coprocessor built in, 486SX and 386 do not, unless you added
1267 a 487DX or 387, respectively. (The messages during boot time can
1268 give you some hints here ["man dmesg"].) Everyone needs either a
1269 coprocessor or this emulation.
1271 If you don't have a math coprocessor, you need to say Y here; if you
1272 say Y here even though you have a coprocessor, the coprocessor will
1273 be used nevertheless. (This behavior can be changed with the kernel
1274 command line option "no387", which comes handy if your coprocessor
1275 is broken. Try "man bootparam" or see the documentation of your boot
1276 loader (lilo or loadlin) about how to pass options to the kernel at
1277 boot time.) This means that it is a good idea to say Y here if you
1278 intend to use this kernel on different machines.
1280 More information about the internals of the Linux math coprocessor
1281 emulation can be found in <file:arch/x86/math-emu/README>.
1283 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1284 kernel, it won't hurt.
1287 bool "MTRR (Memory Type Range Register) support"
1289 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1290 the Memory Type Range Registers (MTRRs) may be used to control
1291 processor access to memory ranges. This is most useful if you have
1292 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1293 allows bus write transfers to be combined into a larger transfer
1294 before bursting over the PCI/AGP bus. This can increase performance
1295 of image write operations 2.5 times or more. Saying Y here creates a
1296 /proc/mtrr file which may be used to manipulate your processor's
1297 MTRRs. Typically the X server should use this.
1299 This code has a reasonably generic interface so that similar
1300 control registers on other processors can be easily supported
1303 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1304 Registers (ARRs) which provide a similar functionality to MTRRs. For
1305 these, the ARRs are used to emulate the MTRRs.
1306 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1307 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1308 write-combining. All of these processors are supported by this code
1309 and it makes sense to say Y here if you have one of them.
1311 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1312 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1313 can lead to all sorts of problems, so it's good to say Y here.
1315 You can safely say Y even if your machine doesn't have MTRRs, you'll
1316 just add about 9 KB to your kernel.
1318 See <file:Documentation/x86/mtrr.txt> for more information.
1320 config MTRR_SANITIZER
1322 prompt "MTRR cleanup support"
1325 Convert MTRR layout from continuous to discrete, so X drivers can
1326 add writeback entries.
1328 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1329 The largest mtrr entry size for a continuous block can be set with
1334 config MTRR_SANITIZER_ENABLE_DEFAULT
1335 int "MTRR cleanup enable value (0-1)"
1338 depends on MTRR_SANITIZER
1340 Enable mtrr cleanup default value
1342 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1343 int "MTRR cleanup spare reg num (0-7)"
1346 depends on MTRR_SANITIZER
1348 mtrr cleanup spare entries default, it can be changed via
1349 mtrr_spare_reg_nr=N on the kernel command line.
1353 prompt "x86 PAT support"
1356 Use PAT attributes to setup page level cache control.
1358 PATs are the modern equivalents of MTRRs and are much more
1359 flexible than MTRRs.
1361 Say N here if you see bootup problems (boot crash, boot hang,
1362 spontaneous reboots) or a non-working video driver.
1367 bool "EFI runtime service support"
1370 This enables the kernel to use EFI runtime services that are
1371 available (such as the EFI variable services).
1373 This option is only useful on systems that have EFI firmware.
1374 In addition, you should use the latest ELILO loader available
1375 at <http://elilo.sourceforge.net> in order to take advantage
1376 of EFI runtime services. However, even with this option, the
1377 resultant kernel should continue to boot on existing non-EFI
1382 prompt "Enable seccomp to safely compute untrusted bytecode"
1384 This kernel feature is useful for number crunching applications
1385 that may need to compute untrusted bytecode during their
1386 execution. By using pipes or other transports made available to
1387 the process as file descriptors supporting the read/write
1388 syscalls, it's possible to isolate those applications in
1389 their own address space using seccomp. Once seccomp is
1390 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1391 and the task is only allowed to execute a few safe syscalls
1392 defined by each seccomp mode.
1394 If unsure, say Y. Only embedded should say N here.
1396 config CC_STACKPROTECTOR_ALL
1399 config CC_STACKPROTECTOR
1400 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1401 select CC_STACKPROTECTOR_ALL
1403 This option turns on the -fstack-protector GCC feature. This
1404 feature puts, at the beginning of functions, a canary value on
1405 the stack just before the return address, and validates
1406 the value just before actually returning. Stack based buffer
1407 overflows (that need to overwrite this return address) now also
1408 overwrite the canary, which gets detected and the attack is then
1409 neutralized via a kernel panic.
1411 This feature requires gcc version 4.2 or above, or a distribution
1412 gcc with the feature backported. Older versions are automatically
1413 detected and for those versions, this configuration option is
1414 ignored. (and a warning is printed during bootup)
1416 source kernel/Kconfig.hz
1419 bool "kexec system call"
1421 kexec is a system call that implements the ability to shutdown your
1422 current kernel, and to start another kernel. It is like a reboot
1423 but it is independent of the system firmware. And like a reboot
1424 you can start any kernel with it, not just Linux.
1426 The name comes from the similarity to the exec system call.
1428 It is an ongoing process to be certain the hardware in a machine
1429 is properly shutdown, so do not be surprised if this code does not
1430 initially work for you. It may help to enable device hotplugging
1431 support. As of this writing the exact hardware interface is
1432 strongly in flux, so no good recommendation can be made.
1435 bool "kernel crash dumps"
1436 depends on X86_64 || (X86_32 && HIGHMEM)
1438 Generate crash dump after being started by kexec.
1439 This should be normally only set in special crash dump kernels
1440 which are loaded in the main kernel with kexec-tools into
1441 a specially reserved region and then later executed after
1442 a crash by kdump/kexec. The crash dump kernel must be compiled
1443 to a memory address not used by the main kernel or BIOS using
1444 PHYSICAL_START, or it must be built as a relocatable image
1445 (CONFIG_RELOCATABLE=y).
1446 For more details see Documentation/kdump/kdump.txt
1449 bool "kexec jump (EXPERIMENTAL)"
1450 depends on EXPERIMENTAL
1451 depends on KEXEC && HIBERNATION
1453 Jump between original kernel and kexeced kernel and invoke
1454 code in physical address mode via KEXEC
1456 config PHYSICAL_START
1457 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1458 default "0x1000000" if X86_NUMAQ
1459 default "0x200000" if X86_64
1462 This gives the physical address where the kernel is loaded.
1464 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1465 bzImage will decompress itself to above physical address and
1466 run from there. Otherwise, bzImage will run from the address where
1467 it has been loaded by the boot loader and will ignore above physical
1470 In normal kdump cases one does not have to set/change this option
1471 as now bzImage can be compiled as a completely relocatable image
1472 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1473 address. This option is mainly useful for the folks who don't want
1474 to use a bzImage for capturing the crash dump and want to use a
1475 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1476 to be specifically compiled to run from a specific memory area
1477 (normally a reserved region) and this option comes handy.
1479 So if you are using bzImage for capturing the crash dump, leave
1480 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1481 Otherwise if you plan to use vmlinux for capturing the crash dump
1482 change this value to start of the reserved region (Typically 16MB
1483 0x1000000). In other words, it can be set based on the "X" value as
1484 specified in the "crashkernel=YM@XM" command line boot parameter
1485 passed to the panic-ed kernel. Typically this parameter is set as
1486 crashkernel=64M@16M. Please take a look at
1487 Documentation/kdump/kdump.txt for more details about crash dumps.
1489 Usage of bzImage for capturing the crash dump is recommended as
1490 one does not have to build two kernels. Same kernel can be used
1491 as production kernel and capture kernel. Above option should have
1492 gone away after relocatable bzImage support is introduced. But it
1493 is present because there are users out there who continue to use
1494 vmlinux for dump capture. This option should go away down the
1497 Don't change this unless you know what you are doing.
1500 bool "Build a relocatable kernel (EXPERIMENTAL)"
1501 depends on EXPERIMENTAL
1503 This builds a kernel image that retains relocation information
1504 so it can be loaded someplace besides the default 1MB.
1505 The relocations tend to make the kernel binary about 10% larger,
1506 but are discarded at runtime.
1508 One use is for the kexec on panic case where the recovery kernel
1509 must live at a different physical address than the primary
1512 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1513 it has been loaded at and the compile time physical address
1514 (CONFIG_PHYSICAL_START) is ignored.
1516 config PHYSICAL_ALIGN
1518 prompt "Alignment value to which kernel should be aligned" if X86_32
1519 default "0x100000" if X86_32
1520 default "0x200000" if X86_64
1521 range 0x2000 0x400000
1523 This value puts the alignment restrictions on physical address
1524 where kernel is loaded and run from. Kernel is compiled for an
1525 address which meets above alignment restriction.
1527 If bootloader loads the kernel at a non-aligned address and
1528 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1529 address aligned to above value and run from there.
1531 If bootloader loads the kernel at a non-aligned address and
1532 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1533 load address and decompress itself to the address it has been
1534 compiled for and run from there. The address for which kernel is
1535 compiled already meets above alignment restrictions. Hence the
1536 end result is that kernel runs from a physical address meeting
1537 above alignment restrictions.
1539 Don't change this unless you know what you are doing.
1542 bool "Support for hot-pluggable CPUs"
1543 depends on SMP && HOTPLUG
1545 Say Y here to allow turning CPUs off and on. CPUs can be
1546 controlled through /sys/devices/system/cpu.
1547 ( Note: power management support will enable this option
1548 automatically on SMP systems. )
1549 Say N if you want to disable CPU hotplug.
1553 prompt "Compat VDSO support"
1554 depends on X86_32 || IA32_EMULATION
1556 Map the 32-bit VDSO to the predictable old-style address too.
1558 Say N here if you are running a sufficiently recent glibc
1559 version (2.3.3 or later), to remove the high-mapped
1560 VDSO mapping and to exclusively use the randomized VDSO.
1565 bool "Built-in kernel command line"
1568 Allow for specifying boot arguments to the kernel at
1569 build time. On some systems (e.g. embedded ones), it is
1570 necessary or convenient to provide some or all of the
1571 kernel boot arguments with the kernel itself (that is,
1572 to not rely on the boot loader to provide them.)
1574 To compile command line arguments into the kernel,
1575 set this option to 'Y', then fill in the
1576 the boot arguments in CONFIG_CMDLINE.
1578 Systems with fully functional boot loaders (i.e. non-embedded)
1579 should leave this option set to 'N'.
1582 string "Built-in kernel command string"
1583 depends on CMDLINE_BOOL
1586 Enter arguments here that should be compiled into the kernel
1587 image and used at boot time. If the boot loader provides a
1588 command line at boot time, it is appended to this string to
1589 form the full kernel command line, when the system boots.
1591 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1592 change this behavior.
1594 In most cases, the command line (whether built-in or provided
1595 by the boot loader) should specify the device for the root
1598 config CMDLINE_OVERRIDE
1599 bool "Built-in command line overrides boot loader arguments"
1601 depends on CMDLINE_BOOL
1603 Set this option to 'Y' to have the kernel ignore the boot loader
1604 command line, and use ONLY the built-in command line.
1606 This is used to work around broken boot loaders. This should
1607 be set to 'N' under normal conditions.
1611 config ARCH_ENABLE_MEMORY_HOTPLUG
1613 depends on X86_64 || (X86_32 && HIGHMEM)
1615 config ARCH_ENABLE_MEMORY_HOTREMOVE
1617 depends on MEMORY_HOTPLUG
1619 config HAVE_ARCH_EARLY_PFN_TO_NID
1623 menu "Power management and ACPI options"
1625 config ARCH_HIBERNATION_HEADER
1627 depends on X86_64 && HIBERNATION
1629 source "kernel/power/Kconfig"
1631 source "drivers/acpi/Kconfig"
1636 depends on APM || APM_MODULE
1639 tristate "APM (Advanced Power Management) BIOS support"
1640 depends on X86_32 && PM_SLEEP
1642 APM is a BIOS specification for saving power using several different
1643 techniques. This is mostly useful for battery powered laptops with
1644 APM compliant BIOSes. If you say Y here, the system time will be
1645 reset after a RESUME operation, the /proc/apm device will provide
1646 battery status information, and user-space programs will receive
1647 notification of APM "events" (e.g. battery status change).
1649 If you select "Y" here, you can disable actual use of the APM
1650 BIOS by passing the "apm=off" option to the kernel at boot time.
1652 Note that the APM support is almost completely disabled for
1653 machines with more than one CPU.
1655 In order to use APM, you will need supporting software. For location
1656 and more information, read <file:Documentation/power/pm.txt> and the
1657 Battery Powered Linux mini-HOWTO, available from
1658 <http://www.tldp.org/docs.html#howto>.
1660 This driver does not spin down disk drives (see the hdparm(8)
1661 manpage ("man 8 hdparm") for that), and it doesn't turn off
1662 VESA-compliant "green" monitors.
1664 This driver does not support the TI 4000M TravelMate and the ACER
1665 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1666 desktop machines also don't have compliant BIOSes, and this driver
1667 may cause those machines to panic during the boot phase.
1669 Generally, if you don't have a battery in your machine, there isn't
1670 much point in using this driver and you should say N. If you get
1671 random kernel OOPSes or reboots that don't seem to be related to
1672 anything, try disabling/enabling this option (or disabling/enabling
1675 Some other things you should try when experiencing seemingly random,
1678 1) make sure that you have enough swap space and that it is
1680 2) pass the "no-hlt" option to the kernel
1681 3) switch on floating point emulation in the kernel and pass
1682 the "no387" option to the kernel
1683 4) pass the "floppy=nodma" option to the kernel
1684 5) pass the "mem=4M" option to the kernel (thereby disabling
1685 all but the first 4 MB of RAM)
1686 6) make sure that the CPU is not over clocked.
1687 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1688 8) disable the cache from your BIOS settings
1689 9) install a fan for the video card or exchange video RAM
1690 10) install a better fan for the CPU
1691 11) exchange RAM chips
1692 12) exchange the motherboard.
1694 To compile this driver as a module, choose M here: the
1695 module will be called apm.
1699 config APM_IGNORE_USER_SUSPEND
1700 bool "Ignore USER SUSPEND"
1702 This option will ignore USER SUSPEND requests. On machines with a
1703 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1704 series notebooks, it is necessary to say Y because of a BIOS bug.
1706 config APM_DO_ENABLE
1707 bool "Enable PM at boot time"
1709 Enable APM features at boot time. From page 36 of the APM BIOS
1710 specification: "When disabled, the APM BIOS does not automatically
1711 power manage devices, enter the Standby State, enter the Suspend
1712 State, or take power saving steps in response to CPU Idle calls."
1713 This driver will make CPU Idle calls when Linux is idle (unless this
1714 feature is turned off -- see "Do CPU IDLE calls", below). This
1715 should always save battery power, but more complicated APM features
1716 will be dependent on your BIOS implementation. You may need to turn
1717 this option off if your computer hangs at boot time when using APM
1718 support, or if it beeps continuously instead of suspending. Turn
1719 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1720 T400CDT. This is off by default since most machines do fine without
1724 bool "Make CPU Idle calls when idle"
1726 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1727 On some machines, this can activate improved power savings, such as
1728 a slowed CPU clock rate, when the machine is idle. These idle calls
1729 are made after the idle loop has run for some length of time (e.g.,
1730 333 mS). On some machines, this will cause a hang at boot time or
1731 whenever the CPU becomes idle. (On machines with more than one CPU,
1732 this option does nothing.)
1734 config APM_DISPLAY_BLANK
1735 bool "Enable console blanking using APM"
1737 Enable console blanking using the APM. Some laptops can use this to
1738 turn off the LCD backlight when the screen blanker of the Linux
1739 virtual console blanks the screen. Note that this is only used by
1740 the virtual console screen blanker, and won't turn off the backlight
1741 when using the X Window system. This also doesn't have anything to
1742 do with your VESA-compliant power-saving monitor. Further, this
1743 option doesn't work for all laptops -- it might not turn off your
1744 backlight at all, or it might print a lot of errors to the console,
1745 especially if you are using gpm.
1747 config APM_ALLOW_INTS
1748 bool "Allow interrupts during APM BIOS calls"
1750 Normally we disable external interrupts while we are making calls to
1751 the APM BIOS as a measure to lessen the effects of a badly behaving
1752 BIOS implementation. The BIOS should reenable interrupts if it
1753 needs to. Unfortunately, some BIOSes do not -- especially those in
1754 many of the newer IBM Thinkpads. If you experience hangs when you
1755 suspend, try setting this to Y. Otherwise, say N.
1759 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1761 source "drivers/cpuidle/Kconfig"
1763 source "drivers/idle/Kconfig"
1768 menu "Bus options (PCI etc.)"
1773 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1775 Find out whether you have a PCI motherboard. PCI is the name of a
1776 bus system, i.e. the way the CPU talks to the other stuff inside
1777 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1778 VESA. If you have PCI, say Y, otherwise N.
1781 prompt "PCI access mode"
1782 depends on X86_32 && PCI
1785 On PCI systems, the BIOS can be used to detect the PCI devices and
1786 determine their configuration. However, some old PCI motherboards
1787 have BIOS bugs and may crash if this is done. Also, some embedded
1788 PCI-based systems don't have any BIOS at all. Linux can also try to
1789 detect the PCI hardware directly without using the BIOS.
1791 With this option, you can specify how Linux should detect the
1792 PCI devices. If you choose "BIOS", the BIOS will be used,
1793 if you choose "Direct", the BIOS won't be used, and if you
1794 choose "MMConfig", then PCI Express MMCONFIG will be used.
1795 If you choose "Any", the kernel will try MMCONFIG, then the
1796 direct access method and falls back to the BIOS if that doesn't
1797 work. If unsure, go with the default, which is "Any".
1802 config PCI_GOMMCONFIG
1819 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1821 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1824 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1828 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1832 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1839 bool "Support mmconfig PCI config space access"
1840 depends on X86_64 && PCI && ACPI
1843 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1844 depends on PCI_MSI && ACPI && EXPERIMENTAL
1846 DMA remapping (DMAR) devices support enables independent address
1847 translations for Direct Memory Access (DMA) from devices.
1848 These DMA remapping devices are reported via ACPI tables
1849 and include PCI device scope covered by these DMA
1852 config DMAR_DEFAULT_ON
1854 prompt "Enable DMA Remapping Devices by default"
1857 Selecting this option will enable a DMAR device at boot time if
1858 one is found. If this option is not selected, DMAR support can
1859 be enabled by passing intel_iommu=on to the kernel. It is
1860 recommended you say N here while the DMAR code remains
1865 prompt "Support for Graphics workaround"
1868 Current Graphics drivers tend to use physical address
1869 for DMA and avoid using DMA APIs. Setting this config
1870 option permits the IOMMU driver to set a unity map for
1871 all the OS-visible memory. Hence the driver can continue
1872 to use physical addresses for DMA.
1874 config DMAR_FLOPPY_WA
1878 Floppy disk drivers are know to bypass DMA API calls
1879 thereby failing to work when IOMMU is enabled. This
1880 workaround will setup a 1:1 mapping for the first
1881 16M to make floppy (an ISA device) work.
1884 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1885 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1887 Supports Interrupt remapping for IO-APIC and MSI devices.
1888 To use x2apic mode in the CPU's which support x2APIC enhancements or
1889 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1891 source "drivers/pci/pcie/Kconfig"
1893 source "drivers/pci/Kconfig"
1895 # x86_64 have no ISA slots, but do have ISA-style DMA.
1904 Find out whether you have ISA slots on your motherboard. ISA is the
1905 name of a bus system, i.e. the way the CPU talks to the other stuff
1906 inside your box. Other bus systems are PCI, EISA, MicroChannel
1907 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1908 newer boards don't support it. If you have ISA, say Y, otherwise N.
1914 The Extended Industry Standard Architecture (EISA) bus was
1915 developed as an open alternative to the IBM MicroChannel bus.
1917 The EISA bus provided some of the features of the IBM MicroChannel
1918 bus while maintaining backward compatibility with cards made for
1919 the older ISA bus. The EISA bus saw limited use between 1988 and
1920 1995 when it was made obsolete by the PCI bus.
1922 Say Y here if you are building a kernel for an EISA-based machine.
1926 source "drivers/eisa/Kconfig"
1931 MicroChannel Architecture is found in some IBM PS/2 machines and
1932 laptops. It is a bus system similar to PCI or ISA. See
1933 <file:Documentation/mca.txt> (and especially the web page given
1934 there) before attempting to build an MCA bus kernel.
1936 source "drivers/mca/Kconfig"
1939 tristate "NatSemi SCx200 support"
1941 This provides basic support for National Semiconductor's
1942 (now AMD's) Geode processors. The driver probes for the
1943 PCI-IDs of several on-chip devices, so its a good dependency
1944 for other scx200_* drivers.
1946 If compiled as a module, the driver is named scx200.
1948 config SCx200HR_TIMER
1949 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1950 depends on SCx200 && GENERIC_TIME
1953 This driver provides a clocksource built upon the on-chip
1954 27MHz high-resolution timer. Its also a workaround for
1955 NSC Geode SC-1100's buggy TSC, which loses time when the
1956 processor goes idle (as is done by the scheduler). The
1957 other workaround is idle=poll boot option.
1959 config GEODE_MFGPT_TIMER
1961 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1962 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1964 This driver provides a clock event source based on the MFGPT
1965 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1966 MFGPTs have a better resolution and max interval than the
1967 generic PIT, and are suitable for use as high-res timers.
1970 bool "One Laptop Per Child support"
1973 Add support for detecting the unique features of the OLPC
1980 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1982 source "drivers/pcmcia/Kconfig"
1984 source "drivers/pci/hotplug/Kconfig"
1989 menu "Executable file formats / Emulations"
1991 source "fs/Kconfig.binfmt"
1993 config IA32_EMULATION
1994 bool "IA32 Emulation"
1996 select COMPAT_BINFMT_ELF
1998 Include code to run 32-bit programs under a 64-bit kernel. You should
1999 likely turn this on, unless you're 100% sure that you don't have any
2000 32-bit programs left.
2003 tristate "IA32 a.out support"
2004 depends on IA32_EMULATION
2006 Support old a.out binaries in the 32bit emulation.
2010 depends on IA32_EMULATION
2012 config COMPAT_FOR_U64_ALIGNMENT
2016 config SYSVIPC_COMPAT
2018 depends on COMPAT && SYSVIPC
2023 config HAVE_ATOMIC_IOMAP
2027 source "net/Kconfig"
2029 source "drivers/Kconfig"
2031 source "drivers/firmware/Kconfig"
2035 source "arch/x86/Kconfig.debug"
2037 source "security/Kconfig"
2039 source "crypto/Kconfig"
2041 source "arch/x86/kvm/Kconfig"
2043 source "lib/Kconfig"
projects / linux-2.6 / blob