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_PERF_COUNTERS if (!M386 && !M486)
28 select HAVE_IOREMAP_PROT
30 select ARCH_WANT_OPTIONAL_GPIOLIB
31 select ARCH_WANT_FRAME_POINTERS
33 select HAVE_KRETPROBES
34 select HAVE_FTRACE_MCOUNT_RECORD
35 select HAVE_DYNAMIC_FTRACE
36 select HAVE_FUNCTION_TRACER
37 select HAVE_FUNCTION_GRAPH_TRACER
38 select HAVE_FUNCTION_GRAPH_FP_TEST
39 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
40 select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
41 select HAVE_SYSCALL_TRACEPOINTS
44 select HAVE_ARCH_TRACEHOOK
45 select HAVE_GENERIC_DMA_COHERENT if X86_32
46 select HAVE_EFFICIENT_UNALIGNED_ACCESS
47 select USER_STACKTRACE_SUPPORT
48 select HAVE_DMA_API_DEBUG
49 select HAVE_KERNEL_GZIP
50 select HAVE_KERNEL_BZIP2
51 select HAVE_KERNEL_LZMA
52 select HAVE_ARCH_KMEMCHECK
56 default "elf32-i386" if X86_32
57 default "elf64-x86-64" if X86_64
61 default "arch/x86/configs/i386_defconfig" if X86_32
62 default "arch/x86/configs/x86_64_defconfig" if X86_64
67 config GENERIC_CMOS_UPDATE
70 config CLOCKSOURCE_WATCHDOG
73 config GENERIC_CLOCKEVENTS
76 config GENERIC_CLOCKEVENTS_BROADCAST
78 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
80 config LOCKDEP_SUPPORT
83 config STACKTRACE_SUPPORT
86 config HAVE_LATENCYTOP_SUPPORT
89 config FAST_CMPXCHG_LOCAL
102 config GENERIC_ISA_DMA
111 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
113 config GENERIC_BUG_RELATIVE_POINTERS
116 config GENERIC_HWEIGHT
122 config ARCH_MAY_HAVE_PC_FDC
125 config RWSEM_GENERIC_SPINLOCK
128 config RWSEM_XCHGADD_ALGORITHM
131 config ARCH_HAS_CPU_IDLE_WAIT
134 config GENERIC_CALIBRATE_DELAY
137 config GENERIC_TIME_VSYSCALL
141 config ARCH_HAS_CPU_RELAX
144 config ARCH_HAS_DEFAULT_IDLE
147 config ARCH_HAS_CACHE_LINE_SIZE
150 config HAVE_SETUP_PER_CPU_AREA
153 config HAVE_DYNAMIC_PER_CPU_AREA
156 config HAVE_CPUMASK_OF_CPU_MAP
159 config ARCH_HIBERNATION_POSSIBLE
162 config ARCH_SUSPEND_POSSIBLE
169 config ARCH_POPULATES_NODE_MAP
176 config ARCH_SUPPORTS_OPTIMIZED_INLINING
179 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
182 config HAVE_INTEL_TXT
184 depends on EXPERIMENTAL && DMAR && ACPI
186 # Use the generic interrupt handling code in kernel/irq/:
187 config GENERIC_HARDIRQS
191 config GENERIC_HARDIRQS_NO__DO_IRQ
194 config GENERIC_IRQ_PROBE
198 config GENERIC_PENDING_IRQ
200 depends on GENERIC_HARDIRQS && SMP
203 config USE_GENERIC_SMP_HELPERS
209 depends on X86_32 && SMP
213 depends on X86_64 && SMP
220 config X86_TRAMPOLINE
222 depends on SMP || (64BIT && ACPI_SLEEP)
225 config X86_32_LAZY_GS
227 depends on X86_32 && !CC_STACKPROTECTOR
231 source "init/Kconfig"
232 source "kernel/Kconfig.freezer"
234 menu "Processor type and features"
236 source "kernel/time/Kconfig"
239 bool "Symmetric multi-processing support"
241 This enables support for systems with more than one CPU. If you have
242 a system with only one CPU, like most personal computers, say N. If
243 you have a system with more than one CPU, say Y.
245 If you say N here, the kernel will run on single and multiprocessor
246 machines, but will use only one CPU of a multiprocessor machine. If
247 you say Y here, the kernel will run on many, but not all,
248 singleprocessor machines. On a singleprocessor machine, the kernel
249 will run faster if you say N here.
251 Note that if you say Y here and choose architecture "586" or
252 "Pentium" under "Processor family", the kernel will not work on 486
253 architectures. Similarly, multiprocessor kernels for the "PPro"
254 architecture may not work on all Pentium based boards.
256 People using multiprocessor machines who say Y here should also say
257 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
258 Management" code will be disabled if you say Y here.
260 See also <file:Documentation/i386/IO-APIC.txt>,
261 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
262 <http://www.tldp.org/docs.html#howto>.
264 If you don't know what to do here, say N.
267 bool "Support x2apic"
268 depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
270 This enables x2apic support on CPUs that have this feature.
272 This allows 32-bit apic IDs (so it can support very large systems),
273 and accesses the local apic via MSRs not via mmio.
275 If you don't know what to do here, say N.
278 bool "Support sparse irq numbering"
279 depends on PCI_MSI || HT_IRQ
281 This enables support for sparse irqs. This is useful for distro
282 kernels that want to define a high CONFIG_NR_CPUS value but still
283 want to have low kernel memory footprint on smaller machines.
285 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
286 out the irq_desc[] array in a more NUMA-friendly way. )
288 If you don't know what to do here, say N.
292 depends on SPARSE_IRQ && NUMA
295 bool "Enable MPS table" if ACPI
297 depends on X86_LOCAL_APIC
299 For old smp systems that do not have proper acpi support. Newer systems
300 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
303 bool "Support for big SMP systems with more than 8 CPUs"
304 depends on X86_32 && SMP
306 This option is needed for the systems that have more than 8 CPUs
309 config X86_EXTENDED_PLATFORM
310 bool "Support for extended (non-PC) x86 platforms"
313 If you disable this option then the kernel will only support
314 standard PC platforms. (which covers the vast majority of
317 If you enable this option then you'll be able to select support
318 for the following (non-PC) 32 bit x86 platforms:
322 SGI 320/540 (Visual Workstation)
323 Summit/EXA (IBM x440)
324 Unisys ES7000 IA32 series
326 If you have one of these systems, or if you want to build a
327 generic distribution kernel, say Y here - otherwise say N.
331 config X86_EXTENDED_PLATFORM
332 bool "Support for extended (non-PC) x86 platforms"
335 If you disable this option then the kernel will only support
336 standard PC platforms. (which covers the vast majority of
339 If you enable this option then you'll be able to select support
340 for the following (non-PC) 64 bit x86 platforms:
344 If you have one of these systems, or if you want to build a
345 generic distribution kernel, say Y here - otherwise say N.
347 # This is an alphabetically sorted list of 64 bit extended platforms
348 # Please maintain the alphabetic order if and when there are additions
353 depends on X86_64 && PCI
354 depends on X86_EXTENDED_PLATFORM
356 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
357 supposed to run on these EM64T-based machines. Only choose this option
358 if you have one of these machines.
361 bool "SGI Ultraviolet"
363 depends on X86_EXTENDED_PLATFORM
365 depends on X86_X2APIC
367 This option is needed in order to support SGI Ultraviolet systems.
368 If you don't have one of these, you should say N here.
370 # Following is an alphabetically sorted list of 32 bit extended platforms
371 # Please maintain the alphabetic order if and when there are additions
376 depends on X86_EXTENDED_PLATFORM
378 Select this for an AMD Elan processor.
380 Do not use this option for K6/Athlon/Opteron processors!
382 If unsure, choose "PC-compatible" instead.
385 bool "RDC R-321x SoC"
387 depends on X86_EXTENDED_PLATFORM
389 select X86_REBOOTFIXUPS
391 This option is needed for RDC R-321x system-on-chip, also known
393 If you don't have one of these chips, you should say N here.
395 config X86_32_NON_STANDARD
396 bool "Support non-standard 32-bit SMP architectures"
397 depends on X86_32 && SMP
398 depends on X86_EXTENDED_PLATFORM
400 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
401 subarchitectures. It is intended for a generic binary kernel.
402 if you select them all, kernel will probe it one by one. and will
405 # Alphabetically sorted list of Non standard 32 bit platforms
408 bool "NUMAQ (IBM/Sequent)"
409 depends on X86_32_NON_STANDARD
413 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
414 NUMA multiquad box. This changes the way that processors are
415 bootstrapped, and uses Clustered Logical APIC addressing mode instead
416 of Flat Logical. You will need a new lynxer.elf file to flash your
417 firmware with - send email to <Martin.Bligh@us.ibm.com>.
420 bool "SGI 320/540 (Visual Workstation)"
421 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
422 depends on X86_32_NON_STANDARD
424 The SGI Visual Workstation series is an IA32-based workstation
425 based on SGI systems chips with some legacy PC hardware attached.
427 Say Y here to create a kernel to run on the SGI 320 or 540.
429 A kernel compiled for the Visual Workstation will run on general
430 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
433 bool "Summit/EXA (IBM x440)"
434 depends on X86_32_NON_STANDARD
436 This option is needed for IBM systems that use the Summit/EXA chipset.
437 In particular, it is needed for the x440.
440 bool "Unisys ES7000 IA32 series"
441 depends on X86_32_NON_STANDARD && X86_BIGSMP
443 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
444 supposed to run on an IA32-based Unisys ES7000 system.
446 config SCHED_OMIT_FRAME_POINTER
448 prompt "Single-depth WCHAN output"
451 Calculate simpler /proc/<PID>/wchan values. If this option
452 is disabled then wchan values will recurse back to the
453 caller function. This provides more accurate wchan values,
454 at the expense of slightly more scheduling overhead.
456 If in doubt, say "Y".
458 menuconfig PARAVIRT_GUEST
459 bool "Paravirtualized guest support"
461 Say Y here to get to see options related to running Linux under
462 various hypervisors. This option alone does not add any kernel code.
464 If you say N, all options in this submenu will be skipped and disabled.
468 source "arch/x86/xen/Kconfig"
471 bool "VMI Guest support"
475 VMI provides a paravirtualized interface to the VMware ESX server
476 (it could be used by other hypervisors in theory too, but is not
477 at the moment), by linking the kernel to a GPL-ed ROM module
478 provided by the hypervisor.
481 bool "KVM paravirtualized clock"
483 select PARAVIRT_CLOCK
485 Turning on this option will allow you to run a paravirtualized clock
486 when running over the KVM hypervisor. Instead of relying on a PIT
487 (or probably other) emulation by the underlying device model, the host
488 provides the guest with timing infrastructure such as time of day, and
492 bool "KVM Guest support"
495 This option enables various optimizations for running under the KVM
498 source "arch/x86/lguest/Kconfig"
501 bool "Enable paravirtualization code"
503 This changes the kernel so it can modify itself when it is run
504 under a hypervisor, potentially improving performance significantly
505 over full virtualization. However, when run without a hypervisor
506 the kernel is theoretically slower and slightly larger.
508 config PARAVIRT_SPINLOCKS
509 bool "Paravirtualization layer for spinlocks"
510 depends on PARAVIRT && SMP && EXPERIMENTAL
512 Paravirtualized spinlocks allow a pvops backend to replace the
513 spinlock implementation with something virtualization-friendly
514 (for example, block the virtual CPU rather than spinning).
516 Unfortunately the downside is an up to 5% performance hit on
517 native kernels, with various workloads.
519 If you are unsure how to answer this question, answer N.
521 config PARAVIRT_CLOCK
527 config PARAVIRT_DEBUG
528 bool "paravirt-ops debugging"
529 depends on PARAVIRT && DEBUG_KERNEL
531 Enable to debug paravirt_ops internals. Specifically, BUG if
532 a paravirt_op is missing when it is called.
537 This option adds a kernel parameter 'memtest', which allows memtest
539 memtest=0, mean disabled; -- default
540 memtest=1, mean do 1 test pattern;
542 memtest=4, mean do 4 test patterns.
543 If you are unsure how to answer this question, answer N.
545 config X86_SUMMIT_NUMA
547 depends on X86_32 && NUMA && X86_32_NON_STANDARD
549 config X86_CYCLONE_TIMER
551 depends on X86_32_NON_STANDARD
553 source "arch/x86/Kconfig.cpu"
557 prompt "HPET Timer Support" if X86_32
559 Use the IA-PC HPET (High Precision Event Timer) to manage
560 time in preference to the PIT and RTC, if a HPET is
562 HPET is the next generation timer replacing legacy 8254s.
563 The HPET provides a stable time base on SMP
564 systems, unlike the TSC, but it is more expensive to access,
565 as it is off-chip. You can find the HPET spec at
566 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
568 You can safely choose Y here. However, HPET will only be
569 activated if the platform and the BIOS support this feature.
570 Otherwise the 8254 will be used for timing services.
572 Choose N to continue using the legacy 8254 timer.
574 config HPET_EMULATE_RTC
576 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
578 # Mark as embedded because too many people got it wrong.
579 # The code disables itself when not needed.
582 bool "Enable DMI scanning" if EMBEDDED
584 Enabled scanning of DMI to identify machine quirks. Say Y
585 here unless you have verified that your setup is not
586 affected by entries in the DMI blacklist. Required by PNP
590 bool "GART IOMMU support" if EMBEDDED
593 depends on X86_64 && PCI
595 Support for full DMA access of devices with 32bit memory access only
596 on systems with more than 3GB. This is usually needed for USB,
597 sound, many IDE/SATA chipsets and some other devices.
598 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
599 based hardware IOMMU and a software bounce buffer based IOMMU used
600 on Intel systems and as fallback.
601 The code is only active when needed (enough memory and limited
602 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
606 bool "IBM Calgary IOMMU support"
608 depends on X86_64 && PCI && EXPERIMENTAL
610 Support for hardware IOMMUs in IBM's xSeries x366 and x460
611 systems. Needed to run systems with more than 3GB of memory
612 properly with 32-bit PCI devices that do not support DAC
613 (Double Address Cycle). Calgary also supports bus level
614 isolation, where all DMAs pass through the IOMMU. This
615 prevents them from going anywhere except their intended
616 destination. This catches hard-to-find kernel bugs and
617 mis-behaving drivers and devices that do not use the DMA-API
618 properly to set up their DMA buffers. The IOMMU can be
619 turned off at boot time with the iommu=off parameter.
620 Normally the kernel will make the right choice by itself.
623 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
625 prompt "Should Calgary be enabled by default?"
626 depends on CALGARY_IOMMU
628 Should Calgary be enabled by default? if you choose 'y', Calgary
629 will be used (if it exists). If you choose 'n', Calgary will not be
630 used even if it exists. If you choose 'n' and would like to use
631 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
635 bool "AMD IOMMU support"
638 depends on X86_64 && PCI && ACPI
640 With this option you can enable support for AMD IOMMU hardware in
641 your system. An IOMMU is a hardware component which provides
642 remapping of DMA memory accesses from devices. With an AMD IOMMU you
643 can isolate the the DMA memory of different devices and protect the
644 system from misbehaving device drivers or hardware.
646 You can find out if your system has an AMD IOMMU if you look into
647 your BIOS for an option to enable it or if you have an IVRS ACPI
650 config AMD_IOMMU_STATS
651 bool "Export AMD IOMMU statistics to debugfs"
655 This option enables code in the AMD IOMMU driver to collect various
656 statistics about whats happening in the driver and exports that
657 information to userspace via debugfs.
660 # need this always selected by IOMMU for the VIA workaround
664 Support for software bounce buffers used on x86-64 systems
665 which don't have a hardware IOMMU (e.g. the current generation
666 of Intel's x86-64 CPUs). Using this PCI devices which can only
667 access 32-bits of memory can be used on systems with more than
668 3 GB of memory. If unsure, say Y.
671 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
674 def_bool (AMD_IOMMU || DMAR)
677 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
678 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
679 select CPUMASK_OFFSTACK
682 Configure maximum number of CPUS and NUMA Nodes for this architecture.
686 int "Maximum number of CPUs" if SMP && !MAXSMP
687 range 2 8 if SMP && X86_32 && !X86_BIGSMP
688 range 2 512 if SMP && !MAXSMP
690 default "4096" if MAXSMP
691 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
694 This allows you to specify the maximum number of CPUs which this
695 kernel will support. The maximum supported value is 512 and the
696 minimum value which makes sense is 2.
698 This is purely to save memory - each supported CPU adds
699 approximately eight kilobytes to the kernel image.
702 bool "SMT (Hyperthreading) scheduler support"
705 SMT scheduler support improves the CPU scheduler's decision making
706 when dealing with Intel Pentium 4 chips with HyperThreading at a
707 cost of slightly increased overhead in some places. If unsure say
712 prompt "Multi-core scheduler support"
715 Multi-core scheduler support improves the CPU scheduler's decision
716 making when dealing with multi-core CPU chips at a cost of slightly
717 increased overhead in some places. If unsure say N here.
719 source "kernel/Kconfig.preempt"
722 bool "Local APIC support on uniprocessors"
723 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
725 A local APIC (Advanced Programmable Interrupt Controller) is an
726 integrated interrupt controller in the CPU. If you have a single-CPU
727 system which has a processor with a local APIC, you can say Y here to
728 enable and use it. If you say Y here even though your machine doesn't
729 have a local APIC, then the kernel will still run with no slowdown at
730 all. The local APIC supports CPU-generated self-interrupts (timer,
731 performance counters), and the NMI watchdog which detects hard
735 bool "IO-APIC support on uniprocessors"
736 depends on X86_UP_APIC
738 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
739 SMP-capable replacement for PC-style interrupt controllers. Most
740 SMP systems and many recent uniprocessor systems have one.
742 If you have a single-CPU system with an IO-APIC, you can say Y here
743 to use it. If you say Y here even though your machine doesn't have
744 an IO-APIC, then the kernel will still run with no slowdown at all.
746 config X86_LOCAL_APIC
748 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
752 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
754 config X86_VISWS_APIC
756 depends on X86_32 && X86_VISWS
758 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
759 bool "Reroute for broken boot IRQs"
761 depends on X86_IO_APIC
763 This option enables a workaround that fixes a source of
764 spurious interrupts. This is recommended when threaded
765 interrupt handling is used on systems where the generation of
766 superfluous "boot interrupts" cannot be disabled.
768 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
769 entry in the chipset's IO-APIC is masked (as, e.g. the RT
770 kernel does during interrupt handling). On chipsets where this
771 boot IRQ generation cannot be disabled, this workaround keeps
772 the original IRQ line masked so that only the equivalent "boot
773 IRQ" is delivered to the CPUs. The workaround also tells the
774 kernel to set up the IRQ handler on the boot IRQ line. In this
775 way only one interrupt is delivered to the kernel. Otherwise
776 the spurious second interrupt may cause the kernel to bring
777 down (vital) interrupt lines.
779 Only affects "broken" chipsets. Interrupt sharing may be
780 increased on these systems.
783 bool "Machine Check Exception"
785 Machine Check Exception support allows the processor to notify the
786 kernel if it detects a problem (e.g. overheating, component failure).
787 The action the kernel takes depends on the severity of the problem,
788 ranging from a warning message on the console, to halting the machine.
789 Your processor must be a Pentium or newer to support this - check the
790 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
791 have a design flaw which leads to false MCE events - hence MCE is
792 disabled on all P5 processors, unless explicitly enabled with "mce"
793 as a boot argument. Similarly, if MCE is built in and creates a
794 problem on some new non-standard machine, you can boot with "nomce"
795 to disable it. MCE support simply ignores non-MCE processors like
796 the 386 and 486, so nearly everyone can say Y here.
799 depends on X86_32 && X86_MCE
800 bool "Use legacy machine check code (will go away)"
802 select X86_ANCIENT_MCE
804 Use the old i386 machine check code. This is merely intended for
805 testing in a transition period. Try this if you run into any machine
806 check related software problems, but report the problem to
807 linux-kernel. When in doubt say no.
812 default y if (!X86_OLD_MCE && X86_32) || X86_64
816 prompt "Intel MCE features"
817 depends on X86_NEW_MCE && X86_LOCAL_APIC
819 Additional support for intel specific MCE features such as
824 prompt "AMD MCE features"
825 depends on X86_NEW_MCE && X86_LOCAL_APIC
827 Additional support for AMD specific MCE features such as
828 the DRAM Error Threshold.
830 config X86_ANCIENT_MCE
833 prompt "Support for old Pentium 5 / WinChip machine checks"
835 Include support for machine check handling on old Pentium 5 or WinChip
836 systems. These typically need to be enabled explicitely on the command
839 config X86_MCE_THRESHOLD
840 depends on X86_MCE_AMD || X86_MCE_INTEL
844 config X86_MCE_INJECT
845 depends on X86_NEW_MCE
846 tristate "Machine check injector support"
848 Provide support for injecting machine checks for testing purposes.
849 If you don't know what a machine check is and you don't do kernel
850 QA it is safe to say n.
852 config X86_MCE_NONFATAL
853 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
854 depends on X86_OLD_MCE
856 Enabling this feature starts a timer that triggers every 5 seconds which
857 will look at the machine check registers to see if anything happened.
858 Non-fatal problems automatically get corrected (but still logged).
859 Disable this if you don't want to see these messages.
860 Seeing the messages this option prints out may be indicative of dying
861 or out-of-spec (ie, overclocked) hardware.
862 This option only does something on certain CPUs.
863 (AMD Athlon/Duron and Intel Pentium 4)
865 config X86_MCE_P4THERMAL
866 bool "check for P4 thermal throttling interrupt."
867 depends on X86_OLD_MCE && X86_MCE && (X86_UP_APIC || SMP)
869 Enabling this feature will cause a message to be printed when the P4
870 enters thermal throttling.
872 config X86_THERMAL_VECTOR
874 depends on X86_MCE_P4THERMAL || X86_MCE_INTEL
877 bool "Enable VM86 support" if EMBEDDED
881 This option is required by programs like DOSEMU to run 16-bit legacy
882 code on X86 processors. It also may be needed by software like
883 XFree86 to initialize some video cards via BIOS. Disabling this
884 option saves about 6k.
887 tristate "Toshiba Laptop support"
890 This adds a driver to safely access the System Management Mode of
891 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
892 not work on models with a Phoenix BIOS. The System Management Mode
893 is used to set the BIOS and power saving options on Toshiba portables.
895 For information on utilities to make use of this driver see the
896 Toshiba Linux utilities web site at:
897 <http://www.buzzard.org.uk/toshiba/>.
899 Say Y if you intend to run this kernel on a Toshiba portable.
903 tristate "Dell laptop support"
905 This adds a driver to safely access the System Management Mode
906 of the CPU on the Dell Inspiron 8000. The System Management Mode
907 is used to read cpu temperature and cooling fan status and to
908 control the fans on the I8K portables.
910 This driver has been tested only on the Inspiron 8000 but it may
911 also work with other Dell laptops. You can force loading on other
912 models by passing the parameter `force=1' to the module. Use at
915 For information on utilities to make use of this driver see the
916 I8K Linux utilities web site at:
917 <http://people.debian.org/~dz/i8k/>
919 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
922 config X86_REBOOTFIXUPS
923 bool "Enable X86 board specific fixups for reboot"
926 This enables chipset and/or board specific fixups to be done
927 in order to get reboot to work correctly. This is only needed on
928 some combinations of hardware and BIOS. The symptom, for which
929 this config is intended, is when reboot ends with a stalled/hung
932 Currently, the only fixup is for the Geode machines using
933 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
935 Say Y if you want to enable the fixup. Currently, it's safe to
936 enable this option even if you don't need it.
940 tristate "/dev/cpu/microcode - microcode support"
943 If you say Y here, you will be able to update the microcode on
944 certain Intel and AMD processors. The Intel support is for the
945 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
946 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
947 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
948 You will obviously need the actual microcode binary data itself
949 which is not shipped with the Linux kernel.
951 This option selects the general module only, you need to select
952 at least one vendor specific module as well.
954 To compile this driver as a module, choose M here: the
955 module will be called microcode.
957 config MICROCODE_INTEL
958 bool "Intel microcode patch loading support"
963 This options enables microcode patch loading support for Intel
966 For latest news and information on obtaining all the required
967 Intel ingredients for this driver, check:
968 <http://www.urbanmyth.org/microcode/>.
971 bool "AMD microcode patch loading support"
975 If you select this option, microcode patch loading support for AMD
976 processors will be enabled.
978 config MICROCODE_OLD_INTERFACE
983 tristate "/dev/cpu/*/msr - Model-specific register support"
985 This device gives privileged processes access to the x86
986 Model-Specific Registers (MSRs). It is a character device with
987 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
988 MSR accesses are directed to a specific CPU on multi-processor
992 tristate "/dev/cpu/*/cpuid - CPU information support"
994 This device gives processes access to the x86 CPUID instruction to
995 be executed on a specific processor. It is a character device
996 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1000 tristate "/sys/kernel/debug/x86/cpu/* - CPU Debug support"
1002 If you select this option, this will provide various x86 CPUs
1003 information through debugfs.
1006 prompt "High Memory Support"
1007 default HIGHMEM4G if !X86_NUMAQ
1008 default HIGHMEM64G if X86_NUMAQ
1013 depends on !X86_NUMAQ
1015 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1016 However, the address space of 32-bit x86 processors is only 4
1017 Gigabytes large. That means that, if you have a large amount of
1018 physical memory, not all of it can be "permanently mapped" by the
1019 kernel. The physical memory that's not permanently mapped is called
1022 If you are compiling a kernel which will never run on a machine with
1023 more than 1 Gigabyte total physical RAM, answer "off" here (default
1024 choice and suitable for most users). This will result in a "3GB/1GB"
1025 split: 3GB are mapped so that each process sees a 3GB virtual memory
1026 space and the remaining part of the 4GB virtual memory space is used
1027 by the kernel to permanently map as much physical memory as
1030 If the machine has between 1 and 4 Gigabytes physical RAM, then
1033 If more than 4 Gigabytes is used then answer "64GB" here. This
1034 selection turns Intel PAE (Physical Address Extension) mode on.
1035 PAE implements 3-level paging on IA32 processors. PAE is fully
1036 supported by Linux, PAE mode is implemented on all recent Intel
1037 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1038 then the kernel will not boot on CPUs that don't support PAE!
1040 The actual amount of total physical memory will either be
1041 auto detected or can be forced by using a kernel command line option
1042 such as "mem=256M". (Try "man bootparam" or see the documentation of
1043 your boot loader (lilo or loadlin) about how to pass options to the
1044 kernel at boot time.)
1046 If unsure, say "off".
1050 depends on !X86_NUMAQ
1052 Select this if you have a 32-bit processor and between 1 and 4
1053 gigabytes of physical RAM.
1057 depends on !M386 && !M486
1060 Select this if you have a 32-bit processor and more than 4
1061 gigabytes of physical RAM.
1066 depends on EXPERIMENTAL
1067 prompt "Memory split" if EMBEDDED
1071 Select the desired split between kernel and user memory.
1073 If the address range available to the kernel is less than the
1074 physical memory installed, the remaining memory will be available
1075 as "high memory". Accessing high memory is a little more costly
1076 than low memory, as it needs to be mapped into the kernel first.
1077 Note that increasing the kernel address space limits the range
1078 available to user programs, making the address space there
1079 tighter. Selecting anything other than the default 3G/1G split
1080 will also likely make your kernel incompatible with binary-only
1083 If you are not absolutely sure what you are doing, leave this
1087 bool "3G/1G user/kernel split"
1088 config VMSPLIT_3G_OPT
1090 bool "3G/1G user/kernel split (for full 1G low memory)"
1092 bool "2G/2G user/kernel split"
1093 config VMSPLIT_2G_OPT
1095 bool "2G/2G user/kernel split (for full 2G low memory)"
1097 bool "1G/3G user/kernel split"
1102 default 0xB0000000 if VMSPLIT_3G_OPT
1103 default 0x80000000 if VMSPLIT_2G
1104 default 0x78000000 if VMSPLIT_2G_OPT
1105 default 0x40000000 if VMSPLIT_1G
1111 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1114 bool "PAE (Physical Address Extension) Support"
1115 depends on X86_32 && !HIGHMEM4G
1117 PAE is required for NX support, and furthermore enables
1118 larger swapspace support for non-overcommit purposes. It
1119 has the cost of more pagetable lookup overhead, and also
1120 consumes more pagetable space per process.
1122 config ARCH_PHYS_ADDR_T_64BIT
1123 def_bool X86_64 || X86_PAE
1125 config DIRECT_GBPAGES
1126 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1130 Allow the kernel linear mapping to use 1GB pages on CPUs that
1131 support it. This can improve the kernel's performance a tiny bit by
1132 reducing TLB pressure. If in doubt, say "Y".
1134 # Common NUMA Features
1136 bool "Numa Memory Allocation and Scheduler Support"
1138 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1139 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1141 Enable NUMA (Non Uniform Memory Access) support.
1143 The kernel will try to allocate memory used by a CPU on the
1144 local memory controller of the CPU and add some more
1145 NUMA awareness to the kernel.
1147 For 64-bit this is recommended if the system is Intel Core i7
1148 (or later), AMD Opteron, or EM64T NUMA.
1150 For 32-bit this is only needed on (rare) 32-bit-only platforms
1151 that support NUMA topologies, such as NUMAQ / Summit, or if you
1152 boot a 32-bit kernel on a 64-bit NUMA platform.
1154 Otherwise, you should say N.
1156 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1157 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1161 prompt "Old style AMD Opteron NUMA detection"
1162 depends on X86_64 && NUMA && PCI
1164 Enable K8 NUMA node topology detection. You should say Y here if
1165 you have a multi processor AMD K8 system. This uses an old
1166 method to read the NUMA configuration directly from the builtin
1167 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1168 instead, which also takes priority if both are compiled in.
1170 config X86_64_ACPI_NUMA
1172 prompt "ACPI NUMA detection"
1173 depends on X86_64 && NUMA && ACPI && PCI
1176 Enable ACPI SRAT based node topology detection.
1178 # Some NUMA nodes have memory ranges that span
1179 # other nodes. Even though a pfn is valid and
1180 # between a node's start and end pfns, it may not
1181 # reside on that node. See memmap_init_zone()
1183 config NODES_SPAN_OTHER_NODES
1185 depends on X86_64_ACPI_NUMA
1188 bool "NUMA emulation"
1189 depends on X86_64 && NUMA
1191 Enable NUMA emulation. A flat machine will be split
1192 into virtual nodes when booted with "numa=fake=N", where N is the
1193 number of nodes. This is only useful for debugging.
1196 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1198 default "9" if MAXSMP
1199 default "6" if X86_64
1200 default "4" if X86_NUMAQ
1202 depends on NEED_MULTIPLE_NODES
1204 Specify the maximum number of NUMA Nodes available on the target
1205 system. Increases memory reserved to accommodate various tables.
1207 config HAVE_ARCH_BOOTMEM
1209 depends on X86_32 && NUMA
1211 config ARCH_HAVE_MEMORY_PRESENT
1213 depends on X86_32 && DISCONTIGMEM
1215 config NEED_NODE_MEMMAP_SIZE
1217 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1219 config HAVE_ARCH_ALLOC_REMAP
1221 depends on X86_32 && NUMA
1223 config ARCH_FLATMEM_ENABLE
1225 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1227 config ARCH_DISCONTIGMEM_ENABLE
1229 depends on NUMA && X86_32
1231 config ARCH_DISCONTIGMEM_DEFAULT
1233 depends on NUMA && X86_32
1235 config ARCH_SPARSEMEM_DEFAULT
1239 config ARCH_SPARSEMEM_ENABLE
1241 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1242 select SPARSEMEM_STATIC if X86_32
1243 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1245 config ARCH_SELECT_MEMORY_MODEL
1247 depends on ARCH_SPARSEMEM_ENABLE
1249 config ARCH_MEMORY_PROBE
1251 depends on MEMORY_HOTPLUG
1256 bool "Allocate 3rd-level pagetables from highmem"
1257 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1259 The VM uses one page table entry for each page of physical memory.
1260 For systems with a lot of RAM, this can be wasteful of precious
1261 low memory. Setting this option will put user-space page table
1262 entries in high memory.
1264 config X86_CHECK_BIOS_CORRUPTION
1265 bool "Check for low memory corruption"
1267 Periodically check for memory corruption in low memory, which
1268 is suspected to be caused by BIOS. Even when enabled in the
1269 configuration, it is disabled at runtime. Enable it by
1270 setting "memory_corruption_check=1" on the kernel command
1271 line. By default it scans the low 64k of memory every 60
1272 seconds; see the memory_corruption_check_size and
1273 memory_corruption_check_period parameters in
1274 Documentation/kernel-parameters.txt to adjust this.
1276 When enabled with the default parameters, this option has
1277 almost no overhead, as it reserves a relatively small amount
1278 of memory and scans it infrequently. It both detects corruption
1279 and prevents it from affecting the running system.
1281 It is, however, intended as a diagnostic tool; if repeatable
1282 BIOS-originated corruption always affects the same memory,
1283 you can use memmap= to prevent the kernel from using that
1286 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1287 bool "Set the default setting of memory_corruption_check"
1288 depends on X86_CHECK_BIOS_CORRUPTION
1291 Set whether the default state of memory_corruption_check is
1294 config X86_RESERVE_LOW_64K
1295 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1298 Reserve the first 64K of physical RAM on BIOSes that are known
1299 to potentially corrupt that memory range. A numbers of BIOSes are
1300 known to utilize this area during suspend/resume, so it must not
1301 be used by the kernel.
1303 Set this to N if you are absolutely sure that you trust the BIOS
1304 to get all its memory reservations and usages right.
1306 If you have doubts about the BIOS (e.g. suspend/resume does not
1307 work or there's kernel crashes after certain hardware hotplug
1308 events) and it's not AMI or Phoenix, then you might want to enable
1309 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1310 corruption patterns.
1314 config MATH_EMULATION
1316 prompt "Math emulation" if X86_32
1318 Linux can emulate a math coprocessor (used for floating point
1319 operations) if you don't have one. 486DX and Pentium processors have
1320 a math coprocessor built in, 486SX and 386 do not, unless you added
1321 a 487DX or 387, respectively. (The messages during boot time can
1322 give you some hints here ["man dmesg"].) Everyone needs either a
1323 coprocessor or this emulation.
1325 If you don't have a math coprocessor, you need to say Y here; if you
1326 say Y here even though you have a coprocessor, the coprocessor will
1327 be used nevertheless. (This behavior can be changed with the kernel
1328 command line option "no387", which comes handy if your coprocessor
1329 is broken. Try "man bootparam" or see the documentation of your boot
1330 loader (lilo or loadlin) about how to pass options to the kernel at
1331 boot time.) This means that it is a good idea to say Y here if you
1332 intend to use this kernel on different machines.
1334 More information about the internals of the Linux math coprocessor
1335 emulation can be found in <file:arch/x86/math-emu/README>.
1337 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1338 kernel, it won't hurt.
1341 bool "MTRR (Memory Type Range Register) support"
1343 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1344 the Memory Type Range Registers (MTRRs) may be used to control
1345 processor access to memory ranges. This is most useful if you have
1346 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1347 allows bus write transfers to be combined into a larger transfer
1348 before bursting over the PCI/AGP bus. This can increase performance
1349 of image write operations 2.5 times or more. Saying Y here creates a
1350 /proc/mtrr file which may be used to manipulate your processor's
1351 MTRRs. Typically the X server should use this.
1353 This code has a reasonably generic interface so that similar
1354 control registers on other processors can be easily supported
1357 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1358 Registers (ARRs) which provide a similar functionality to MTRRs. For
1359 these, the ARRs are used to emulate the MTRRs.
1360 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1361 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1362 write-combining. All of these processors are supported by this code
1363 and it makes sense to say Y here if you have one of them.
1365 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1366 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1367 can lead to all sorts of problems, so it's good to say Y here.
1369 You can safely say Y even if your machine doesn't have MTRRs, you'll
1370 just add about 9 KB to your kernel.
1372 See <file:Documentation/x86/mtrr.txt> for more information.
1374 config MTRR_SANITIZER
1376 prompt "MTRR cleanup support"
1379 Convert MTRR layout from continuous to discrete, so X drivers can
1380 add writeback entries.
1382 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1383 The largest mtrr entry size for a continuous block can be set with
1388 config MTRR_SANITIZER_ENABLE_DEFAULT
1389 int "MTRR cleanup enable value (0-1)"
1392 depends on MTRR_SANITIZER
1394 Enable mtrr cleanup default value
1396 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1397 int "MTRR cleanup spare reg num (0-7)"
1400 depends on MTRR_SANITIZER
1402 mtrr cleanup spare entries default, it can be changed via
1403 mtrr_spare_reg_nr=N on the kernel command line.
1407 prompt "x86 PAT support"
1410 Use PAT attributes to setup page level cache control.
1412 PATs are the modern equivalents of MTRRs and are much more
1413 flexible than MTRRs.
1415 Say N here if you see bootup problems (boot crash, boot hang,
1416 spontaneous reboots) or a non-working video driver.
1421 bool "EFI runtime service support"
1424 This enables the kernel to use EFI runtime services that are
1425 available (such as the EFI variable services).
1427 This option is only useful on systems that have EFI firmware.
1428 In addition, you should use the latest ELILO loader available
1429 at <http://elilo.sourceforge.net> in order to take advantage
1430 of EFI runtime services. However, even with this option, the
1431 resultant kernel should continue to boot on existing non-EFI
1436 prompt "Enable seccomp to safely compute untrusted bytecode"
1438 This kernel feature is useful for number crunching applications
1439 that may need to compute untrusted bytecode during their
1440 execution. By using pipes or other transports made available to
1441 the process as file descriptors supporting the read/write
1442 syscalls, it's possible to isolate those applications in
1443 their own address space using seccomp. Once seccomp is
1444 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1445 and the task is only allowed to execute a few safe syscalls
1446 defined by each seccomp mode.
1448 If unsure, say Y. Only embedded should say N here.
1450 config CC_STACKPROTECTOR_ALL
1453 config CC_STACKPROTECTOR
1454 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1455 select CC_STACKPROTECTOR_ALL
1457 This option turns on the -fstack-protector GCC feature. This
1458 feature puts, at the beginning of functions, a canary value on
1459 the stack just before the return address, and validates
1460 the value just before actually returning. Stack based buffer
1461 overflows (that need to overwrite this return address) now also
1462 overwrite the canary, which gets detected and the attack is then
1463 neutralized via a kernel panic.
1465 This feature requires gcc version 4.2 or above, or a distribution
1466 gcc with the feature backported. Older versions are automatically
1467 detected and for those versions, this configuration option is
1468 ignored. (and a warning is printed during bootup)
1470 source kernel/Kconfig.hz
1473 bool "kexec system call"
1475 kexec is a system call that implements the ability to shutdown your
1476 current kernel, and to start another kernel. It is like a reboot
1477 but it is independent of the system firmware. And like a reboot
1478 you can start any kernel with it, not just Linux.
1480 The name comes from the similarity to the exec system call.
1482 It is an ongoing process to be certain the hardware in a machine
1483 is properly shutdown, so do not be surprised if this code does not
1484 initially work for you. It may help to enable device hotplugging
1485 support. As of this writing the exact hardware interface is
1486 strongly in flux, so no good recommendation can be made.
1489 bool "kernel crash dumps"
1490 depends on X86_64 || (X86_32 && HIGHMEM)
1492 Generate crash dump after being started by kexec.
1493 This should be normally only set in special crash dump kernels
1494 which are loaded in the main kernel with kexec-tools into
1495 a specially reserved region and then later executed after
1496 a crash by kdump/kexec. The crash dump kernel must be compiled
1497 to a memory address not used by the main kernel or BIOS using
1498 PHYSICAL_START, or it must be built as a relocatable image
1499 (CONFIG_RELOCATABLE=y).
1500 For more details see Documentation/kdump/kdump.txt
1503 bool "kexec jump (EXPERIMENTAL)"
1504 depends on EXPERIMENTAL
1505 depends on KEXEC && HIBERNATION
1507 Jump between original kernel and kexeced kernel and invoke
1508 code in physical address mode via KEXEC
1510 config PHYSICAL_START
1511 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1514 This gives the physical address where the kernel is loaded.
1516 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1517 bzImage will decompress itself to above physical address and
1518 run from there. Otherwise, bzImage will run from the address where
1519 it has been loaded by the boot loader and will ignore above physical
1522 In normal kdump cases one does not have to set/change this option
1523 as now bzImage can be compiled as a completely relocatable image
1524 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1525 address. This option is mainly useful for the folks who don't want
1526 to use a bzImage for capturing the crash dump and want to use a
1527 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1528 to be specifically compiled to run from a specific memory area
1529 (normally a reserved region) and this option comes handy.
1531 So if you are using bzImage for capturing the crash dump,
1532 leave the value here unchanged to 0x1000000 and set
1533 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1534 for capturing the crash dump change this value to start of
1535 the reserved region. In other words, it can be set based on
1536 the "X" value as specified in the "crashkernel=YM@XM"
1537 command line boot parameter passed to the panic-ed
1538 kernel. Please take a look at Documentation/kdump/kdump.txt
1539 for more details about crash dumps.
1541 Usage of bzImage for capturing the crash dump is recommended as
1542 one does not have to build two kernels. Same kernel can be used
1543 as production kernel and capture kernel. Above option should have
1544 gone away after relocatable bzImage support is introduced. But it
1545 is present because there are users out there who continue to use
1546 vmlinux for dump capture. This option should go away down the
1549 Don't change this unless you know what you are doing.
1552 bool "Build a relocatable kernel"
1555 This builds a kernel image that retains relocation information
1556 so it can be loaded someplace besides the default 1MB.
1557 The relocations tend to make the kernel binary about 10% larger,
1558 but are discarded at runtime.
1560 One use is for the kexec on panic case where the recovery kernel
1561 must live at a different physical address than the primary
1564 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1565 it has been loaded at and the compile time physical address
1566 (CONFIG_PHYSICAL_START) is ignored.
1568 # Relocation on x86-32 needs some additional build support
1569 config X86_NEED_RELOCS
1571 depends on X86_32 && RELOCATABLE
1573 config PHYSICAL_ALIGN
1575 prompt "Alignment value to which kernel should be aligned" if X86_32
1577 range 0x2000 0x1000000
1579 This value puts the alignment restrictions on physical address
1580 where kernel is loaded and run from. Kernel is compiled for an
1581 address which meets above alignment restriction.
1583 If bootloader loads the kernel at a non-aligned address and
1584 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1585 address aligned to above value and run from there.
1587 If bootloader loads the kernel at a non-aligned address and
1588 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1589 load address and decompress itself to the address it has been
1590 compiled for and run from there. The address for which kernel is
1591 compiled already meets above alignment restrictions. Hence the
1592 end result is that kernel runs from a physical address meeting
1593 above alignment restrictions.
1595 Don't change this unless you know what you are doing.
1598 bool "Support for hot-pluggable CPUs"
1599 depends on SMP && HOTPLUG
1601 Say Y here to allow turning CPUs off and on. CPUs can be
1602 controlled through /sys/devices/system/cpu.
1603 ( Note: power management support will enable this option
1604 automatically on SMP systems. )
1605 Say N if you want to disable CPU hotplug.
1609 prompt "Compat VDSO support"
1610 depends on X86_32 || IA32_EMULATION
1612 Map the 32-bit VDSO to the predictable old-style address too.
1614 Say N here if you are running a sufficiently recent glibc
1615 version (2.3.3 or later), to remove the high-mapped
1616 VDSO mapping and to exclusively use the randomized VDSO.
1621 bool "Built-in kernel command line"
1624 Allow for specifying boot arguments to the kernel at
1625 build time. On some systems (e.g. embedded ones), it is
1626 necessary or convenient to provide some or all of the
1627 kernel boot arguments with the kernel itself (that is,
1628 to not rely on the boot loader to provide them.)
1630 To compile command line arguments into the kernel,
1631 set this option to 'Y', then fill in the
1632 the boot arguments in CONFIG_CMDLINE.
1634 Systems with fully functional boot loaders (i.e. non-embedded)
1635 should leave this option set to 'N'.
1638 string "Built-in kernel command string"
1639 depends on CMDLINE_BOOL
1642 Enter arguments here that should be compiled into the kernel
1643 image and used at boot time. If the boot loader provides a
1644 command line at boot time, it is appended to this string to
1645 form the full kernel command line, when the system boots.
1647 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1648 change this behavior.
1650 In most cases, the command line (whether built-in or provided
1651 by the boot loader) should specify the device for the root
1654 config CMDLINE_OVERRIDE
1655 bool "Built-in command line overrides boot loader arguments"
1657 depends on CMDLINE_BOOL
1659 Set this option to 'Y' to have the kernel ignore the boot loader
1660 command line, and use ONLY the built-in command line.
1662 This is used to work around broken boot loaders. This should
1663 be set to 'N' under normal conditions.
1667 config ARCH_ENABLE_MEMORY_HOTPLUG
1669 depends on X86_64 || (X86_32 && HIGHMEM)
1671 config ARCH_ENABLE_MEMORY_HOTREMOVE
1673 depends on MEMORY_HOTPLUG
1675 config HAVE_ARCH_EARLY_PFN_TO_NID
1679 menu "Power management and ACPI options"
1681 config ARCH_HIBERNATION_HEADER
1683 depends on X86_64 && HIBERNATION
1685 source "kernel/power/Kconfig"
1687 source "drivers/acpi/Kconfig"
1692 depends on APM || APM_MODULE
1695 tristate "APM (Advanced Power Management) BIOS support"
1696 depends on X86_32 && PM_SLEEP
1698 APM is a BIOS specification for saving power using several different
1699 techniques. This is mostly useful for battery powered laptops with
1700 APM compliant BIOSes. If you say Y here, the system time will be
1701 reset after a RESUME operation, the /proc/apm device will provide
1702 battery status information, and user-space programs will receive
1703 notification of APM "events" (e.g. battery status change).
1705 If you select "Y" here, you can disable actual use of the APM
1706 BIOS by passing the "apm=off" option to the kernel at boot time.
1708 Note that the APM support is almost completely disabled for
1709 machines with more than one CPU.
1711 In order to use APM, you will need supporting software. For location
1712 and more information, read <file:Documentation/power/pm.txt> and the
1713 Battery Powered Linux mini-HOWTO, available from
1714 <http://www.tldp.org/docs.html#howto>.
1716 This driver does not spin down disk drives (see the hdparm(8)
1717 manpage ("man 8 hdparm") for that), and it doesn't turn off
1718 VESA-compliant "green" monitors.
1720 This driver does not support the TI 4000M TravelMate and the ACER
1721 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1722 desktop machines also don't have compliant BIOSes, and this driver
1723 may cause those machines to panic during the boot phase.
1725 Generally, if you don't have a battery in your machine, there isn't
1726 much point in using this driver and you should say N. If you get
1727 random kernel OOPSes or reboots that don't seem to be related to
1728 anything, try disabling/enabling this option (or disabling/enabling
1731 Some other things you should try when experiencing seemingly random,
1734 1) make sure that you have enough swap space and that it is
1736 2) pass the "no-hlt" option to the kernel
1737 3) switch on floating point emulation in the kernel and pass
1738 the "no387" option to the kernel
1739 4) pass the "floppy=nodma" option to the kernel
1740 5) pass the "mem=4M" option to the kernel (thereby disabling
1741 all but the first 4 MB of RAM)
1742 6) make sure that the CPU is not over clocked.
1743 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1744 8) disable the cache from your BIOS settings
1745 9) install a fan for the video card or exchange video RAM
1746 10) install a better fan for the CPU
1747 11) exchange RAM chips
1748 12) exchange the motherboard.
1750 To compile this driver as a module, choose M here: the
1751 module will be called apm.
1755 config APM_IGNORE_USER_SUSPEND
1756 bool "Ignore USER SUSPEND"
1758 This option will ignore USER SUSPEND requests. On machines with a
1759 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1760 series notebooks, it is necessary to say Y because of a BIOS bug.
1762 config APM_DO_ENABLE
1763 bool "Enable PM at boot time"
1765 Enable APM features at boot time. From page 36 of the APM BIOS
1766 specification: "When disabled, the APM BIOS does not automatically
1767 power manage devices, enter the Standby State, enter the Suspend
1768 State, or take power saving steps in response to CPU Idle calls."
1769 This driver will make CPU Idle calls when Linux is idle (unless this
1770 feature is turned off -- see "Do CPU IDLE calls", below). This
1771 should always save battery power, but more complicated APM features
1772 will be dependent on your BIOS implementation. You may need to turn
1773 this option off if your computer hangs at boot time when using APM
1774 support, or if it beeps continuously instead of suspending. Turn
1775 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1776 T400CDT. This is off by default since most machines do fine without
1780 bool "Make CPU Idle calls when idle"
1782 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1783 On some machines, this can activate improved power savings, such as
1784 a slowed CPU clock rate, when the machine is idle. These idle calls
1785 are made after the idle loop has run for some length of time (e.g.,
1786 333 mS). On some machines, this will cause a hang at boot time or
1787 whenever the CPU becomes idle. (On machines with more than one CPU,
1788 this option does nothing.)
1790 config APM_DISPLAY_BLANK
1791 bool "Enable console blanking using APM"
1793 Enable console blanking using the APM. Some laptops can use this to
1794 turn off the LCD backlight when the screen blanker of the Linux
1795 virtual console blanks the screen. Note that this is only used by
1796 the virtual console screen blanker, and won't turn off the backlight
1797 when using the X Window system. This also doesn't have anything to
1798 do with your VESA-compliant power-saving monitor. Further, this
1799 option doesn't work for all laptops -- it might not turn off your
1800 backlight at all, or it might print a lot of errors to the console,
1801 especially if you are using gpm.
1803 config APM_ALLOW_INTS
1804 bool "Allow interrupts during APM BIOS calls"
1806 Normally we disable external interrupts while we are making calls to
1807 the APM BIOS as a measure to lessen the effects of a badly behaving
1808 BIOS implementation. The BIOS should reenable interrupts if it
1809 needs to. Unfortunately, some BIOSes do not -- especially those in
1810 many of the newer IBM Thinkpads. If you experience hangs when you
1811 suspend, try setting this to Y. Otherwise, say N.
1815 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1817 source "drivers/cpuidle/Kconfig"
1819 source "drivers/idle/Kconfig"
1824 menu "Bus options (PCI etc.)"
1829 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1831 Find out whether you have a PCI motherboard. PCI is the name of a
1832 bus system, i.e. the way the CPU talks to the other stuff inside
1833 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1834 VESA. If you have PCI, say Y, otherwise N.
1837 prompt "PCI access mode"
1838 depends on X86_32 && PCI
1841 On PCI systems, the BIOS can be used to detect the PCI devices and
1842 determine their configuration. However, some old PCI motherboards
1843 have BIOS bugs and may crash if this is done. Also, some embedded
1844 PCI-based systems don't have any BIOS at all. Linux can also try to
1845 detect the PCI hardware directly without using the BIOS.
1847 With this option, you can specify how Linux should detect the
1848 PCI devices. If you choose "BIOS", the BIOS will be used,
1849 if you choose "Direct", the BIOS won't be used, and if you
1850 choose "MMConfig", then PCI Express MMCONFIG will be used.
1851 If you choose "Any", the kernel will try MMCONFIG, then the
1852 direct access method and falls back to the BIOS if that doesn't
1853 work. If unsure, go with the default, which is "Any".
1858 config PCI_GOMMCONFIG
1875 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1877 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1880 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1884 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1888 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1895 bool "Support mmconfig PCI config space access"
1896 depends on X86_64 && PCI && ACPI
1899 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1900 depends on PCI_MSI && ACPI && EXPERIMENTAL
1902 DMA remapping (DMAR) devices support enables independent address
1903 translations for Direct Memory Access (DMA) from devices.
1904 These DMA remapping devices are reported via ACPI tables
1905 and include PCI device scope covered by these DMA
1908 config DMAR_DEFAULT_ON
1910 prompt "Enable DMA Remapping Devices by default"
1913 Selecting this option will enable a DMAR device at boot time if
1914 one is found. If this option is not selected, DMAR support can
1915 be enabled by passing intel_iommu=on to the kernel. It is
1916 recommended you say N here while the DMAR code remains
1919 config DMAR_BROKEN_GFX_WA
1921 prompt "Workaround broken graphics drivers (going away soon)"
1924 Current Graphics drivers tend to use physical address
1925 for DMA and avoid using DMA APIs. Setting this config
1926 option permits the IOMMU driver to set a unity map for
1927 all the OS-visible memory. Hence the driver can continue
1928 to use physical addresses for DMA, at least until this
1929 option is removed in the 2.6.32 kernel.
1931 config DMAR_FLOPPY_WA
1935 Floppy disk drivers are known to bypass DMA API calls
1936 thereby failing to work when IOMMU is enabled. This
1937 workaround will setup a 1:1 mapping for the first
1938 16MiB to make floppy (an ISA device) work.
1941 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1942 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1944 Supports Interrupt remapping for IO-APIC and MSI devices.
1945 To use x2apic mode in the CPU's which support x2APIC enhancements or
1946 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1948 source "drivers/pci/pcie/Kconfig"
1950 source "drivers/pci/Kconfig"
1952 # x86_64 have no ISA slots, but do have ISA-style DMA.
1961 Find out whether you have ISA slots on your motherboard. ISA is the
1962 name of a bus system, i.e. the way the CPU talks to the other stuff
1963 inside your box. Other bus systems are PCI, EISA, MicroChannel
1964 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1965 newer boards don't support it. If you have ISA, say Y, otherwise N.
1971 The Extended Industry Standard Architecture (EISA) bus was
1972 developed as an open alternative to the IBM MicroChannel bus.
1974 The EISA bus provided some of the features of the IBM MicroChannel
1975 bus while maintaining backward compatibility with cards made for
1976 the older ISA bus. The EISA bus saw limited use between 1988 and
1977 1995 when it was made obsolete by the PCI bus.
1979 Say Y here if you are building a kernel for an EISA-based machine.
1983 source "drivers/eisa/Kconfig"
1988 MicroChannel Architecture is found in some IBM PS/2 machines and
1989 laptops. It is a bus system similar to PCI or ISA. See
1990 <file:Documentation/mca.txt> (and especially the web page given
1991 there) before attempting to build an MCA bus kernel.
1993 source "drivers/mca/Kconfig"
1996 tristate "NatSemi SCx200 support"
1998 This provides basic support for National Semiconductor's
1999 (now AMD's) Geode processors. The driver probes for the
2000 PCI-IDs of several on-chip devices, so its a good dependency
2001 for other scx200_* drivers.
2003 If compiled as a module, the driver is named scx200.
2005 config SCx200HR_TIMER
2006 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2007 depends on SCx200 && GENERIC_TIME
2010 This driver provides a clocksource built upon the on-chip
2011 27MHz high-resolution timer. Its also a workaround for
2012 NSC Geode SC-1100's buggy TSC, which loses time when the
2013 processor goes idle (as is done by the scheduler). The
2014 other workaround is idle=poll boot option.
2016 config GEODE_MFGPT_TIMER
2018 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
2019 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
2021 This driver provides a clock event source based on the MFGPT
2022 timer(s) in the CS5535 and CS5536 companion chip for the geode.
2023 MFGPTs have a better resolution and max interval than the
2024 generic PIT, and are suitable for use as high-res timers.
2027 bool "One Laptop Per Child support"
2030 Add support for detecting the unique features of the OLPC
2037 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
2039 source "drivers/pcmcia/Kconfig"
2041 source "drivers/pci/hotplug/Kconfig"
2046 menu "Executable file formats / Emulations"
2048 source "fs/Kconfig.binfmt"
2050 config IA32_EMULATION
2051 bool "IA32 Emulation"
2053 select COMPAT_BINFMT_ELF
2055 Include code to run 32-bit programs under a 64-bit kernel. You should
2056 likely turn this on, unless you're 100% sure that you don't have any
2057 32-bit programs left.
2060 tristate "IA32 a.out support"
2061 depends on IA32_EMULATION
2063 Support old a.out binaries in the 32bit emulation.
2067 depends on IA32_EMULATION
2069 config COMPAT_FOR_U64_ALIGNMENT
2073 config SYSVIPC_COMPAT
2075 depends on COMPAT && SYSVIPC
2080 config HAVE_ATOMIC_IOMAP
2084 source "net/Kconfig"
2086 source "drivers/Kconfig"
2088 source "drivers/firmware/Kconfig"
2092 source "arch/x86/Kconfig.debug"
2094 source "security/Kconfig"
2096 source "crypto/Kconfig"
2098 source "arch/x86/kvm/Kconfig"
2100 source "lib/Kconfig"