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_EVENTS 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_KERNEL_LZO
53 select HAVE_HW_BREAKPOINT
56 select HAVE_ARCH_KMEMCHECK
57 select HAVE_USER_RETURN_NOTIFIER
61 default "elf32-i386" if X86_32
62 default "elf64-x86-64" if X86_64
66 default "arch/x86/configs/i386_defconfig" if X86_32
67 default "arch/x86/configs/x86_64_defconfig" if X86_64
72 config GENERIC_CMOS_UPDATE
75 config CLOCKSOURCE_WATCHDOG
78 config GENERIC_CLOCKEVENTS
81 config GENERIC_CLOCKEVENTS_BROADCAST
83 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
85 config LOCKDEP_SUPPORT
88 config STACKTRACE_SUPPORT
91 config HAVE_LATENCYTOP_SUPPORT
103 config GENERIC_ISA_DMA
112 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
114 config GENERIC_BUG_RELATIVE_POINTERS
117 config GENERIC_HWEIGHT
123 config ARCH_MAY_HAVE_PC_FDC
126 config RWSEM_GENERIC_SPINLOCK
129 config RWSEM_XCHGADD_ALGORITHM
132 config ARCH_HAS_CPU_IDLE_WAIT
135 config GENERIC_CALIBRATE_DELAY
138 config GENERIC_TIME_VSYSCALL
142 config ARCH_HAS_CPU_RELAX
145 config ARCH_HAS_DEFAULT_IDLE
148 config ARCH_HAS_CACHE_LINE_SIZE
151 config HAVE_SETUP_PER_CPU_AREA
154 config NEED_PER_CPU_EMBED_FIRST_CHUNK
157 config NEED_PER_CPU_PAGE_FIRST_CHUNK
160 config HAVE_CPUMASK_OF_CPU_MAP
163 config ARCH_HIBERNATION_POSSIBLE
166 config ARCH_SUSPEND_POSSIBLE
173 config ARCH_POPULATES_NODE_MAP
180 config ARCH_SUPPORTS_OPTIMIZED_INLINING
183 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
186 config HAVE_INTEL_TXT
188 depends on EXPERIMENTAL && DMAR && ACPI
190 # Use the generic interrupt handling code in kernel/irq/:
191 config GENERIC_HARDIRQS
195 config GENERIC_HARDIRQS_NO__DO_IRQ
198 config GENERIC_IRQ_PROBE
202 config GENERIC_PENDING_IRQ
204 depends on GENERIC_HARDIRQS && SMP
207 config USE_GENERIC_SMP_HELPERS
213 depends on X86_32 && SMP
217 depends on X86_64 && SMP
224 config X86_TRAMPOLINE
226 depends on SMP || (64BIT && ACPI_SLEEP)
229 config X86_32_LAZY_GS
231 depends on X86_32 && !CC_STACKPROTECTOR
235 source "init/Kconfig"
236 source "kernel/Kconfig.freezer"
238 menu "Processor type and features"
240 source "kernel/time/Kconfig"
243 bool "Symmetric multi-processing support"
245 This enables support for systems with more than one CPU. If you have
246 a system with only one CPU, like most personal computers, say N. If
247 you have a system with more than one CPU, say Y.
249 If you say N here, the kernel will run on single and multiprocessor
250 machines, but will use only one CPU of a multiprocessor machine. If
251 you say Y here, the kernel will run on many, but not all,
252 singleprocessor machines. On a singleprocessor machine, the kernel
253 will run faster if you say N here.
255 Note that if you say Y here and choose architecture "586" or
256 "Pentium" under "Processor family", the kernel will not work on 486
257 architectures. Similarly, multiprocessor kernels for the "PPro"
258 architecture may not work on all Pentium based boards.
260 People using multiprocessor machines who say Y here should also say
261 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
262 Management" code will be disabled if you say Y here.
264 See also <file:Documentation/i386/IO-APIC.txt>,
265 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
266 <http://www.tldp.org/docs.html#howto>.
268 If you don't know what to do here, say N.
271 bool "Support x2apic"
272 depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
274 This enables x2apic support on CPUs that have this feature.
276 This allows 32-bit apic IDs (so it can support very large systems),
277 and accesses the local apic via MSRs not via mmio.
279 If you don't know what to do here, say N.
282 bool "Support sparse irq numbering"
283 depends on PCI_MSI || HT_IRQ
285 This enables support for sparse irqs. This is useful for distro
286 kernels that want to define a high CONFIG_NR_CPUS value but still
287 want to have low kernel memory footprint on smaller machines.
289 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
290 out the irq_desc[] array in a more NUMA-friendly way. )
292 If you don't know what to do here, say N.
296 depends on SPARSE_IRQ && NUMA
299 bool "Enable MPS table" if ACPI
301 depends on X86_LOCAL_APIC
303 For old smp systems that do not have proper acpi support. Newer systems
304 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
307 bool "Support for big SMP systems with more than 8 CPUs"
308 depends on X86_32 && SMP
310 This option is needed for the systems that have more than 8 CPUs
313 config X86_EXTENDED_PLATFORM
314 bool "Support for extended (non-PC) x86 platforms"
317 If you disable this option then the kernel will only support
318 standard PC platforms. (which covers the vast majority of
321 If you enable this option then you'll be able to select support
322 for the following (non-PC) 32 bit x86 platforms:
326 SGI 320/540 (Visual Workstation)
327 Summit/EXA (IBM x440)
328 Unisys ES7000 IA32 series
329 Moorestown MID devices
331 If you have one of these systems, or if you want to build a
332 generic distribution kernel, say Y here - otherwise say N.
336 config X86_EXTENDED_PLATFORM
337 bool "Support for extended (non-PC) x86 platforms"
340 If you disable this option then the kernel will only support
341 standard PC platforms. (which covers the vast majority of
344 If you enable this option then you'll be able to select support
345 for the following (non-PC) 64 bit x86 platforms:
349 If you have one of these systems, or if you want to build a
350 generic distribution kernel, say Y here - otherwise say N.
352 # This is an alphabetically sorted list of 64 bit extended platforms
353 # Please maintain the alphabetic order if and when there are additions
358 depends on X86_64 && PCI
359 depends on X86_EXTENDED_PLATFORM
361 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
362 supposed to run on these EM64T-based machines. Only choose this option
363 if you have one of these machines.
366 bool "SGI Ultraviolet"
368 depends on X86_EXTENDED_PLATFORM
370 depends on X86_X2APIC
372 This option is needed in order to support SGI Ultraviolet systems.
373 If you don't have one of these, you should say N here.
375 # Following is an alphabetically sorted list of 32 bit extended platforms
376 # Please maintain the alphabetic order if and when there are additions
381 depends on X86_EXTENDED_PLATFORM
383 Select this for an AMD Elan processor.
385 Do not use this option for K6/Athlon/Opteron processors!
387 If unsure, choose "PC-compatible" instead.
390 bool "Moorestown MID platform"
392 depends on X86_EXTENDED_PLATFORM
395 Moorestown is Intel's Low Power Intel Architecture (LPIA) based Moblin
396 Internet Device(MID) platform. Moorestown consists of two chips:
397 Lincroft (CPU core, graphics, and memory controller) and Langwell IOH.
398 Unlike standard x86 PCs, Moorestown does not have many legacy devices
399 nor standard legacy replacement devices/features. e.g. Moorestown does
400 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
403 bool "RDC R-321x SoC"
405 depends on X86_EXTENDED_PLATFORM
407 select X86_REBOOTFIXUPS
409 This option is needed for RDC R-321x system-on-chip, also known
411 If you don't have one of these chips, you should say N here.
413 config X86_32_NON_STANDARD
414 bool "Support non-standard 32-bit SMP architectures"
415 depends on X86_32 && SMP
416 depends on X86_EXTENDED_PLATFORM
418 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
419 subarchitectures. It is intended for a generic binary kernel.
420 if you select them all, kernel will probe it one by one. and will
423 # Alphabetically sorted list of Non standard 32 bit platforms
426 bool "NUMAQ (IBM/Sequent)"
427 depends on X86_32_NON_STANDARD
431 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
432 NUMA multiquad box. This changes the way that processors are
433 bootstrapped, and uses Clustered Logical APIC addressing mode instead
434 of Flat Logical. You will need a new lynxer.elf file to flash your
435 firmware with - send email to <Martin.Bligh@us.ibm.com>.
437 config X86_SUPPORTS_MEMORY_FAILURE
439 # MCE code calls memory_failure():
441 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
442 depends on !X86_NUMAQ
443 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
444 depends on X86_64 || !SPARSEMEM
445 select ARCH_SUPPORTS_MEMORY_FAILURE
449 bool "SGI 320/540 (Visual Workstation)"
450 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
451 depends on X86_32_NON_STANDARD
453 The SGI Visual Workstation series is an IA32-based workstation
454 based on SGI systems chips with some legacy PC hardware attached.
456 Say Y here to create a kernel to run on the SGI 320 or 540.
458 A kernel compiled for the Visual Workstation will run on general
459 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
462 bool "Summit/EXA (IBM x440)"
463 depends on X86_32_NON_STANDARD
465 This option is needed for IBM systems that use the Summit/EXA chipset.
466 In particular, it is needed for the x440.
469 bool "Unisys ES7000 IA32 series"
470 depends on X86_32_NON_STANDARD && X86_BIGSMP
472 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
473 supposed to run on an IA32-based Unisys ES7000 system.
475 config SCHED_OMIT_FRAME_POINTER
477 prompt "Single-depth WCHAN output"
480 Calculate simpler /proc/<PID>/wchan values. If this option
481 is disabled then wchan values will recurse back to the
482 caller function. This provides more accurate wchan values,
483 at the expense of slightly more scheduling overhead.
485 If in doubt, say "Y".
487 menuconfig PARAVIRT_GUEST
488 bool "Paravirtualized guest support"
490 Say Y here to get to see options related to running Linux under
491 various hypervisors. This option alone does not add any kernel code.
493 If you say N, all options in this submenu will be skipped and disabled.
497 source "arch/x86/xen/Kconfig"
500 bool "VMI Guest support (DEPRECATED)"
504 VMI provides a paravirtualized interface to the VMware ESX server
505 (it could be used by other hypervisors in theory too, but is not
506 at the moment), by linking the kernel to a GPL-ed ROM module
507 provided by the hypervisor.
509 As of September 2009, VMware has started a phased retirement
510 of this feature from VMware's products. Please see
511 feature-removal-schedule.txt for details. If you are
512 planning to enable this option, please note that you cannot
513 live migrate a VMI enabled VM to a future VMware product,
514 which doesn't support VMI. So if you expect your kernel to
515 seamlessly migrate to newer VMware products, keep this
519 bool "KVM paravirtualized clock"
521 select PARAVIRT_CLOCK
523 Turning on this option will allow you to run a paravirtualized clock
524 when running over the KVM hypervisor. Instead of relying on a PIT
525 (or probably other) emulation by the underlying device model, the host
526 provides the guest with timing infrastructure such as time of day, and
530 bool "KVM Guest support"
533 This option enables various optimizations for running under the KVM
536 source "arch/x86/lguest/Kconfig"
539 bool "Enable paravirtualization code"
541 This changes the kernel so it can modify itself when it is run
542 under a hypervisor, potentially improving performance significantly
543 over full virtualization. However, when run without a hypervisor
544 the kernel is theoretically slower and slightly larger.
546 config PARAVIRT_SPINLOCKS
547 bool "Paravirtualization layer for spinlocks"
548 depends on PARAVIRT && SMP && EXPERIMENTAL
550 Paravirtualized spinlocks allow a pvops backend to replace the
551 spinlock implementation with something virtualization-friendly
552 (for example, block the virtual CPU rather than spinning).
554 Unfortunately the downside is an up to 5% performance hit on
555 native kernels, with various workloads.
557 If you are unsure how to answer this question, answer N.
559 config PARAVIRT_CLOCK
565 config PARAVIRT_DEBUG
566 bool "paravirt-ops debugging"
567 depends on PARAVIRT && DEBUG_KERNEL
569 Enable to debug paravirt_ops internals. Specifically, BUG if
570 a paravirt_op is missing when it is called.
575 This option adds a kernel parameter 'memtest', which allows memtest
577 memtest=0, mean disabled; -- default
578 memtest=1, mean do 1 test pattern;
580 memtest=4, mean do 4 test patterns.
581 If you are unsure how to answer this question, answer N.
583 config X86_SUMMIT_NUMA
585 depends on X86_32 && NUMA && X86_32_NON_STANDARD
587 config X86_CYCLONE_TIMER
589 depends on X86_32_NON_STANDARD
591 source "arch/x86/Kconfig.cpu"
595 prompt "HPET Timer Support" if X86_32
597 Use the IA-PC HPET (High Precision Event Timer) to manage
598 time in preference to the PIT and RTC, if a HPET is
600 HPET is the next generation timer replacing legacy 8254s.
601 The HPET provides a stable time base on SMP
602 systems, unlike the TSC, but it is more expensive to access,
603 as it is off-chip. You can find the HPET spec at
604 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
606 You can safely choose Y here. However, HPET will only be
607 activated if the platform and the BIOS support this feature.
608 Otherwise the 8254 will be used for timing services.
610 Choose N to continue using the legacy 8254 timer.
612 config HPET_EMULATE_RTC
614 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
618 prompt "Langwell APB Timer Support" if X86_MRST
620 APB timer is the replacement for 8254, HPET on X86 MID platforms.
621 The APBT provides a stable time base on SMP
622 systems, unlike the TSC, but it is more expensive to access,
623 as it is off-chip. APB timers are always running regardless of CPU
624 C states, they are used as per CPU clockevent device when possible.
626 # Mark as embedded because too many people got it wrong.
627 # The code disables itself when not needed.
630 bool "Enable DMI scanning" if EMBEDDED
632 Enabled scanning of DMI to identify machine quirks. Say Y
633 here unless you have verified that your setup is not
634 affected by entries in the DMI blacklist. Required by PNP
638 bool "GART IOMMU support" if EMBEDDED
641 depends on X86_64 && PCI
643 Support for full DMA access of devices with 32bit memory access only
644 on systems with more than 3GB. This is usually needed for USB,
645 sound, many IDE/SATA chipsets and some other devices.
646 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
647 based hardware IOMMU and a software bounce buffer based IOMMU used
648 on Intel systems and as fallback.
649 The code is only active when needed (enough memory and limited
650 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
654 bool "IBM Calgary IOMMU support"
656 depends on X86_64 && PCI && EXPERIMENTAL
658 Support for hardware IOMMUs in IBM's xSeries x366 and x460
659 systems. Needed to run systems with more than 3GB of memory
660 properly with 32-bit PCI devices that do not support DAC
661 (Double Address Cycle). Calgary also supports bus level
662 isolation, where all DMAs pass through the IOMMU. This
663 prevents them from going anywhere except their intended
664 destination. This catches hard-to-find kernel bugs and
665 mis-behaving drivers and devices that do not use the DMA-API
666 properly to set up their DMA buffers. The IOMMU can be
667 turned off at boot time with the iommu=off parameter.
668 Normally the kernel will make the right choice by itself.
671 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
673 prompt "Should Calgary be enabled by default?"
674 depends on CALGARY_IOMMU
676 Should Calgary be enabled by default? if you choose 'y', Calgary
677 will be used (if it exists). If you choose 'n', Calgary will not be
678 used even if it exists. If you choose 'n' and would like to use
679 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
683 bool "AMD IOMMU support"
686 depends on X86_64 && PCI && ACPI
688 With this option you can enable support for AMD IOMMU hardware in
689 your system. An IOMMU is a hardware component which provides
690 remapping of DMA memory accesses from devices. With an AMD IOMMU you
691 can isolate the the DMA memory of different devices and protect the
692 system from misbehaving device drivers or hardware.
694 You can find out if your system has an AMD IOMMU if you look into
695 your BIOS for an option to enable it or if you have an IVRS ACPI
698 config AMD_IOMMU_STATS
699 bool "Export AMD IOMMU statistics to debugfs"
703 This option enables code in the AMD IOMMU driver to collect various
704 statistics about whats happening in the driver and exports that
705 information to userspace via debugfs.
708 # need this always selected by IOMMU for the VIA workaround
712 Support for software bounce buffers used on x86-64 systems
713 which don't have a hardware IOMMU (e.g. the current generation
714 of Intel's x86-64 CPUs). Using this PCI devices which can only
715 access 32-bits of memory can be used on systems with more than
716 3 GB of memory. If unsure, say Y.
719 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
722 def_bool (AMD_IOMMU || DMAR)
725 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
726 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
727 select CPUMASK_OFFSTACK
730 Configure maximum number of CPUS and NUMA Nodes for this architecture.
734 int "Maximum number of CPUs" if SMP && !MAXSMP
735 range 2 8 if SMP && X86_32 && !X86_BIGSMP
736 range 2 512 if SMP && !MAXSMP
738 default "4096" if MAXSMP
739 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
742 This allows you to specify the maximum number of CPUs which this
743 kernel will support. The maximum supported value is 512 and the
744 minimum value which makes sense is 2.
746 This is purely to save memory - each supported CPU adds
747 approximately eight kilobytes to the kernel image.
750 bool "SMT (Hyperthreading) scheduler support"
753 SMT scheduler support improves the CPU scheduler's decision making
754 when dealing with Intel Pentium 4 chips with HyperThreading at a
755 cost of slightly increased overhead in some places. If unsure say
760 prompt "Multi-core scheduler support"
763 Multi-core scheduler support improves the CPU scheduler's decision
764 making when dealing with multi-core CPU chips at a cost of slightly
765 increased overhead in some places. If unsure say N here.
767 source "kernel/Kconfig.preempt"
770 bool "Local APIC support on uniprocessors"
771 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
773 A local APIC (Advanced Programmable Interrupt Controller) is an
774 integrated interrupt controller in the CPU. If you have a single-CPU
775 system which has a processor with a local APIC, you can say Y here to
776 enable and use it. If you say Y here even though your machine doesn't
777 have a local APIC, then the kernel will still run with no slowdown at
778 all. The local APIC supports CPU-generated self-interrupts (timer,
779 performance counters), and the NMI watchdog which detects hard
783 bool "IO-APIC support on uniprocessors"
784 depends on X86_UP_APIC
786 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
787 SMP-capable replacement for PC-style interrupt controllers. Most
788 SMP systems and many recent uniprocessor systems have one.
790 If you have a single-CPU system with an IO-APIC, you can say Y here
791 to use it. If you say Y here even though your machine doesn't have
792 an IO-APIC, then the kernel will still run with no slowdown at all.
794 config X86_LOCAL_APIC
796 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
800 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
802 config X86_VISWS_APIC
804 depends on X86_32 && X86_VISWS
806 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
807 bool "Reroute for broken boot IRQs"
809 depends on X86_IO_APIC
811 This option enables a workaround that fixes a source of
812 spurious interrupts. This is recommended when threaded
813 interrupt handling is used on systems where the generation of
814 superfluous "boot interrupts" cannot be disabled.
816 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
817 entry in the chipset's IO-APIC is masked (as, e.g. the RT
818 kernel does during interrupt handling). On chipsets where this
819 boot IRQ generation cannot be disabled, this workaround keeps
820 the original IRQ line masked so that only the equivalent "boot
821 IRQ" is delivered to the CPUs. The workaround also tells the
822 kernel to set up the IRQ handler on the boot IRQ line. In this
823 way only one interrupt is delivered to the kernel. Otherwise
824 the spurious second interrupt may cause the kernel to bring
825 down (vital) interrupt lines.
827 Only affects "broken" chipsets. Interrupt sharing may be
828 increased on these systems.
831 bool "Machine Check / overheating reporting"
833 Machine Check support allows the processor to notify the
834 kernel if it detects a problem (e.g. overheating, data corruption).
835 The action the kernel takes depends on the severity of the problem,
836 ranging from warning messages to halting the machine.
840 prompt "Intel MCE features"
841 depends on X86_MCE && X86_LOCAL_APIC
843 Additional support for intel specific MCE features such as
848 prompt "AMD MCE features"
849 depends on X86_MCE && X86_LOCAL_APIC
851 Additional support for AMD specific MCE features such as
852 the DRAM Error Threshold.
854 config X86_ANCIENT_MCE
856 depends on X86_32 && X86_MCE
857 prompt "Support for old Pentium 5 / WinChip machine checks"
859 Include support for machine check handling on old Pentium 5 or WinChip
860 systems. These typically need to be enabled explicitely on the command
863 config X86_MCE_THRESHOLD
864 depends on X86_MCE_AMD || X86_MCE_INTEL
868 config X86_MCE_INJECT
870 tristate "Machine check injector support"
872 Provide support for injecting machine checks for testing purposes.
873 If you don't know what a machine check is and you don't do kernel
874 QA it is safe to say n.
876 config X86_THERMAL_VECTOR
878 depends on X86_MCE_INTEL
881 bool "Enable VM86 support" if EMBEDDED
885 This option is required by programs like DOSEMU to run 16-bit legacy
886 code on X86 processors. It also may be needed by software like
887 XFree86 to initialize some video cards via BIOS. Disabling this
888 option saves about 6k.
891 tristate "Toshiba Laptop support"
894 This adds a driver to safely access the System Management Mode of
895 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
896 not work on models with a Phoenix BIOS. The System Management Mode
897 is used to set the BIOS and power saving options on Toshiba portables.
899 For information on utilities to make use of this driver see the
900 Toshiba Linux utilities web site at:
901 <http://www.buzzard.org.uk/toshiba/>.
903 Say Y if you intend to run this kernel on a Toshiba portable.
907 tristate "Dell laptop support"
909 This adds a driver to safely access the System Management Mode
910 of the CPU on the Dell Inspiron 8000. The System Management Mode
911 is used to read cpu temperature and cooling fan status and to
912 control the fans on the I8K portables.
914 This driver has been tested only on the Inspiron 8000 but it may
915 also work with other Dell laptops. You can force loading on other
916 models by passing the parameter `force=1' to the module. Use at
919 For information on utilities to make use of this driver see the
920 I8K Linux utilities web site at:
921 <http://people.debian.org/~dz/i8k/>
923 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
926 config X86_REBOOTFIXUPS
927 bool "Enable X86 board specific fixups for reboot"
930 This enables chipset and/or board specific fixups to be done
931 in order to get reboot to work correctly. This is only needed on
932 some combinations of hardware and BIOS. The symptom, for which
933 this config is intended, is when reboot ends with a stalled/hung
936 Currently, the only fixup is for the Geode machines using
937 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
939 Say Y if you want to enable the fixup. Currently, it's safe to
940 enable this option even if you don't need it.
944 tristate "/dev/cpu/microcode - microcode support"
947 If you say Y here, you will be able to update the microcode on
948 certain Intel and AMD processors. The Intel support is for the
949 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
950 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
951 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
952 You will obviously need the actual microcode binary data itself
953 which is not shipped with the Linux kernel.
955 This option selects the general module only, you need to select
956 at least one vendor specific module as well.
958 To compile this driver as a module, choose M here: the
959 module will be called microcode.
961 config MICROCODE_INTEL
962 bool "Intel microcode patch loading support"
967 This options enables microcode patch loading support for Intel
970 For latest news and information on obtaining all the required
971 Intel ingredients for this driver, check:
972 <http://www.urbanmyth.org/microcode/>.
975 bool "AMD microcode patch loading support"
979 If you select this option, microcode patch loading support for AMD
980 processors will be enabled.
982 config MICROCODE_OLD_INTERFACE
987 tristate "/dev/cpu/*/msr - Model-specific register support"
989 This device gives privileged processes access to the x86
990 Model-Specific Registers (MSRs). It is a character device with
991 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
992 MSR accesses are directed to a specific CPU on multi-processor
996 tristate "/dev/cpu/*/cpuid - CPU information support"
998 This device gives processes access to the x86 CPUID instruction to
999 be executed on a specific processor. It is a character device
1000 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1004 prompt "High Memory Support"
1005 default HIGHMEM4G if !X86_NUMAQ
1006 default HIGHMEM64G if X86_NUMAQ
1011 depends on !X86_NUMAQ
1013 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1014 However, the address space of 32-bit x86 processors is only 4
1015 Gigabytes large. That means that, if you have a large amount of
1016 physical memory, not all of it can be "permanently mapped" by the
1017 kernel. The physical memory that's not permanently mapped is called
1020 If you are compiling a kernel which will never run on a machine with
1021 more than 1 Gigabyte total physical RAM, answer "off" here (default
1022 choice and suitable for most users). This will result in a "3GB/1GB"
1023 split: 3GB are mapped so that each process sees a 3GB virtual memory
1024 space and the remaining part of the 4GB virtual memory space is used
1025 by the kernel to permanently map as much physical memory as
1028 If the machine has between 1 and 4 Gigabytes physical RAM, then
1031 If more than 4 Gigabytes is used then answer "64GB" here. This
1032 selection turns Intel PAE (Physical Address Extension) mode on.
1033 PAE implements 3-level paging on IA32 processors. PAE is fully
1034 supported by Linux, PAE mode is implemented on all recent Intel
1035 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1036 then the kernel will not boot on CPUs that don't support PAE!
1038 The actual amount of total physical memory will either be
1039 auto detected or can be forced by using a kernel command line option
1040 such as "mem=256M". (Try "man bootparam" or see the documentation of
1041 your boot loader (lilo or loadlin) about how to pass options to the
1042 kernel at boot time.)
1044 If unsure, say "off".
1048 depends on !X86_NUMAQ
1050 Select this if you have a 32-bit processor and between 1 and 4
1051 gigabytes of physical RAM.
1055 depends on !M386 && !M486
1058 Select this if you have a 32-bit processor and more than 4
1059 gigabytes of physical RAM.
1064 depends on EXPERIMENTAL
1065 prompt "Memory split" if EMBEDDED
1069 Select the desired split between kernel and user memory.
1071 If the address range available to the kernel is less than the
1072 physical memory installed, the remaining memory will be available
1073 as "high memory". Accessing high memory is a little more costly
1074 than low memory, as it needs to be mapped into the kernel first.
1075 Note that increasing the kernel address space limits the range
1076 available to user programs, making the address space there
1077 tighter. Selecting anything other than the default 3G/1G split
1078 will also likely make your kernel incompatible with binary-only
1081 If you are not absolutely sure what you are doing, leave this
1085 bool "3G/1G user/kernel split"
1086 config VMSPLIT_3G_OPT
1088 bool "3G/1G user/kernel split (for full 1G low memory)"
1090 bool "2G/2G user/kernel split"
1091 config VMSPLIT_2G_OPT
1093 bool "2G/2G user/kernel split (for full 2G low memory)"
1095 bool "1G/3G user/kernel split"
1100 default 0xB0000000 if VMSPLIT_3G_OPT
1101 default 0x80000000 if VMSPLIT_2G
1102 default 0x78000000 if VMSPLIT_2G_OPT
1103 default 0x40000000 if VMSPLIT_1G
1109 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1112 bool "PAE (Physical Address Extension) Support"
1113 depends on X86_32 && !HIGHMEM4G
1115 PAE is required for NX support, and furthermore enables
1116 larger swapspace support for non-overcommit purposes. It
1117 has the cost of more pagetable lookup overhead, and also
1118 consumes more pagetable space per process.
1120 config ARCH_PHYS_ADDR_T_64BIT
1121 def_bool X86_64 || X86_PAE
1123 config DIRECT_GBPAGES
1124 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1128 Allow the kernel linear mapping to use 1GB pages on CPUs that
1129 support it. This can improve the kernel's performance a tiny bit by
1130 reducing TLB pressure. If in doubt, say "Y".
1132 # Common NUMA Features
1134 bool "Numa Memory Allocation and Scheduler Support"
1136 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1137 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1139 Enable NUMA (Non Uniform Memory Access) support.
1141 The kernel will try to allocate memory used by a CPU on the
1142 local memory controller of the CPU and add some more
1143 NUMA awareness to the kernel.
1145 For 64-bit this is recommended if the system is Intel Core i7
1146 (or later), AMD Opteron, or EM64T NUMA.
1148 For 32-bit this is only needed on (rare) 32-bit-only platforms
1149 that support NUMA topologies, such as NUMAQ / Summit, or if you
1150 boot a 32-bit kernel on a 64-bit NUMA platform.
1152 Otherwise, you should say N.
1154 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1155 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1159 prompt "Old style AMD Opteron NUMA detection"
1160 depends on X86_64 && NUMA && PCI
1162 Enable K8 NUMA node topology detection. You should say Y here if
1163 you have a multi processor AMD K8 system. This uses an old
1164 method to read the NUMA configuration directly from the builtin
1165 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1166 instead, which also takes priority if both are compiled in.
1168 config X86_64_ACPI_NUMA
1170 prompt "ACPI NUMA detection"
1171 depends on X86_64 && NUMA && ACPI && PCI
1174 Enable ACPI SRAT based node topology detection.
1176 # Some NUMA nodes have memory ranges that span
1177 # other nodes. Even though a pfn is valid and
1178 # between a node's start and end pfns, it may not
1179 # reside on that node. See memmap_init_zone()
1181 config NODES_SPAN_OTHER_NODES
1183 depends on X86_64_ACPI_NUMA
1186 bool "NUMA emulation"
1187 depends on X86_64 && NUMA
1189 Enable NUMA emulation. A flat machine will be split
1190 into virtual nodes when booted with "numa=fake=N", where N is the
1191 number of nodes. This is only useful for debugging.
1194 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1196 default "9" if MAXSMP
1197 default "6" if X86_64
1198 default "4" if X86_NUMAQ
1200 depends on NEED_MULTIPLE_NODES
1202 Specify the maximum number of NUMA Nodes available on the target
1203 system. Increases memory reserved to accommodate various tables.
1205 config HAVE_ARCH_BOOTMEM
1207 depends on X86_32 && NUMA
1209 config ARCH_HAVE_MEMORY_PRESENT
1211 depends on X86_32 && DISCONTIGMEM
1213 config NEED_NODE_MEMMAP_SIZE
1215 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1217 config HAVE_ARCH_ALLOC_REMAP
1219 depends on X86_32 && NUMA
1221 config ARCH_FLATMEM_ENABLE
1223 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1225 config ARCH_DISCONTIGMEM_ENABLE
1227 depends on NUMA && X86_32
1229 config ARCH_DISCONTIGMEM_DEFAULT
1231 depends on NUMA && X86_32
1233 config ARCH_PROC_KCORE_TEXT
1235 depends on X86_64 && PROC_KCORE
1237 config ARCH_SPARSEMEM_DEFAULT
1241 config ARCH_SPARSEMEM_ENABLE
1243 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1244 select SPARSEMEM_STATIC if X86_32
1245 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1247 config ARCH_SELECT_MEMORY_MODEL
1249 depends on ARCH_SPARSEMEM_ENABLE
1251 config ARCH_MEMORY_PROBE
1253 depends on MEMORY_HOTPLUG
1255 config ILLEGAL_POINTER_VALUE
1258 default 0xdead000000000000 if X86_64
1263 bool "Allocate 3rd-level pagetables from highmem"
1264 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1266 The VM uses one page table entry for each page of physical memory.
1267 For systems with a lot of RAM, this can be wasteful of precious
1268 low memory. Setting this option will put user-space page table
1269 entries in high memory.
1271 config X86_CHECK_BIOS_CORRUPTION
1272 bool "Check for low memory corruption"
1274 Periodically check for memory corruption in low memory, which
1275 is suspected to be caused by BIOS. Even when enabled in the
1276 configuration, it is disabled at runtime. Enable it by
1277 setting "memory_corruption_check=1" on the kernel command
1278 line. By default it scans the low 64k of memory every 60
1279 seconds; see the memory_corruption_check_size and
1280 memory_corruption_check_period parameters in
1281 Documentation/kernel-parameters.txt to adjust this.
1283 When enabled with the default parameters, this option has
1284 almost no overhead, as it reserves a relatively small amount
1285 of memory and scans it infrequently. It both detects corruption
1286 and prevents it from affecting the running system.
1288 It is, however, intended as a diagnostic tool; if repeatable
1289 BIOS-originated corruption always affects the same memory,
1290 you can use memmap= to prevent the kernel from using that
1293 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1294 bool "Set the default setting of memory_corruption_check"
1295 depends on X86_CHECK_BIOS_CORRUPTION
1298 Set whether the default state of memory_corruption_check is
1301 config X86_RESERVE_LOW_64K
1302 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1305 Reserve the first 64K of physical RAM on BIOSes that are known
1306 to potentially corrupt that memory range. A numbers of BIOSes are
1307 known to utilize this area during suspend/resume, so it must not
1308 be used by the kernel.
1310 Set this to N if you are absolutely sure that you trust the BIOS
1311 to get all its memory reservations and usages right.
1313 If you have doubts about the BIOS (e.g. suspend/resume does not
1314 work or there's kernel crashes after certain hardware hotplug
1315 events) and it's not AMI or Phoenix, then you might want to enable
1316 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1317 corruption patterns.
1321 config MATH_EMULATION
1323 prompt "Math emulation" if X86_32
1325 Linux can emulate a math coprocessor (used for floating point
1326 operations) if you don't have one. 486DX and Pentium processors have
1327 a math coprocessor built in, 486SX and 386 do not, unless you added
1328 a 487DX or 387, respectively. (The messages during boot time can
1329 give you some hints here ["man dmesg"].) Everyone needs either a
1330 coprocessor or this emulation.
1332 If you don't have a math coprocessor, you need to say Y here; if you
1333 say Y here even though you have a coprocessor, the coprocessor will
1334 be used nevertheless. (This behavior can be changed with the kernel
1335 command line option "no387", which comes handy if your coprocessor
1336 is broken. Try "man bootparam" or see the documentation of your boot
1337 loader (lilo or loadlin) about how to pass options to the kernel at
1338 boot time.) This means that it is a good idea to say Y here if you
1339 intend to use this kernel on different machines.
1341 More information about the internals of the Linux math coprocessor
1342 emulation can be found in <file:arch/x86/math-emu/README>.
1344 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1345 kernel, it won't hurt.
1350 prompt "MTRR (Memory Type Range Register) support" if EMBEDDED
1352 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1353 the Memory Type Range Registers (MTRRs) may be used to control
1354 processor access to memory ranges. This is most useful if you have
1355 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1356 allows bus write transfers to be combined into a larger transfer
1357 before bursting over the PCI/AGP bus. This can increase performance
1358 of image write operations 2.5 times or more. Saying Y here creates a
1359 /proc/mtrr file which may be used to manipulate your processor's
1360 MTRRs. Typically the X server should use this.
1362 This code has a reasonably generic interface so that similar
1363 control registers on other processors can be easily supported
1366 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1367 Registers (ARRs) which provide a similar functionality to MTRRs. For
1368 these, the ARRs are used to emulate the MTRRs.
1369 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1370 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1371 write-combining. All of these processors are supported by this code
1372 and it makes sense to say Y here if you have one of them.
1374 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1375 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1376 can lead to all sorts of problems, so it's good to say Y here.
1378 You can safely say Y even if your machine doesn't have MTRRs, you'll
1379 just add about 9 KB to your kernel.
1381 See <file:Documentation/x86/mtrr.txt> for more information.
1383 config MTRR_SANITIZER
1385 prompt "MTRR cleanup support"
1388 Convert MTRR layout from continuous to discrete, so X drivers can
1389 add writeback entries.
1391 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1392 The largest mtrr entry size for a continuous block can be set with
1397 config MTRR_SANITIZER_ENABLE_DEFAULT
1398 int "MTRR cleanup enable value (0-1)"
1401 depends on MTRR_SANITIZER
1403 Enable mtrr cleanup default value
1405 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1406 int "MTRR cleanup spare reg num (0-7)"
1409 depends on MTRR_SANITIZER
1411 mtrr cleanup spare entries default, it can be changed via
1412 mtrr_spare_reg_nr=N on the kernel command line.
1417 prompt "x86 PAT support" if EMBEDDED
1420 Use PAT attributes to setup page level cache control.
1422 PATs are the modern equivalents of MTRRs and are much more
1423 flexible than MTRRs.
1425 Say N here if you see bootup problems (boot crash, boot hang,
1426 spontaneous reboots) or a non-working video driver.
1430 config ARCH_USES_PG_UNCACHED
1435 bool "EFI runtime service support"
1438 This enables the kernel to use EFI runtime services that are
1439 available (such as the EFI variable services).
1441 This option is only useful on systems that have EFI firmware.
1442 In addition, you should use the latest ELILO loader available
1443 at <http://elilo.sourceforge.net> in order to take advantage
1444 of EFI runtime services. However, even with this option, the
1445 resultant kernel should continue to boot on existing non-EFI
1450 prompt "Enable seccomp to safely compute untrusted bytecode"
1452 This kernel feature is useful for number crunching applications
1453 that may need to compute untrusted bytecode during their
1454 execution. By using pipes or other transports made available to
1455 the process as file descriptors supporting the read/write
1456 syscalls, it's possible to isolate those applications in
1457 their own address space using seccomp. Once seccomp is
1458 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1459 and the task is only allowed to execute a few safe syscalls
1460 defined by each seccomp mode.
1462 If unsure, say Y. Only embedded should say N here.
1464 config CC_STACKPROTECTOR
1465 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1467 This option turns on the -fstack-protector GCC feature. This
1468 feature puts, at the beginning of functions, a canary value on
1469 the stack just before the return address, and validates
1470 the value just before actually returning. Stack based buffer
1471 overflows (that need to overwrite this return address) now also
1472 overwrite the canary, which gets detected and the attack is then
1473 neutralized via a kernel panic.
1475 This feature requires gcc version 4.2 or above, or a distribution
1476 gcc with the feature backported. Older versions are automatically
1477 detected and for those versions, this configuration option is
1478 ignored. (and a warning is printed during bootup)
1480 source kernel/Kconfig.hz
1483 bool "kexec system call"
1485 kexec is a system call that implements the ability to shutdown your
1486 current kernel, and to start another kernel. It is like a reboot
1487 but it is independent of the system firmware. And like a reboot
1488 you can start any kernel with it, not just Linux.
1490 The name comes from the similarity to the exec system call.
1492 It is an ongoing process to be certain the hardware in a machine
1493 is properly shutdown, so do not be surprised if this code does not
1494 initially work for you. It may help to enable device hotplugging
1495 support. As of this writing the exact hardware interface is
1496 strongly in flux, so no good recommendation can be made.
1499 bool "kernel crash dumps"
1500 depends on X86_64 || (X86_32 && HIGHMEM)
1502 Generate crash dump after being started by kexec.
1503 This should be normally only set in special crash dump kernels
1504 which are loaded in the main kernel with kexec-tools into
1505 a specially reserved region and then later executed after
1506 a crash by kdump/kexec. The crash dump kernel must be compiled
1507 to a memory address not used by the main kernel or BIOS using
1508 PHYSICAL_START, or it must be built as a relocatable image
1509 (CONFIG_RELOCATABLE=y).
1510 For more details see Documentation/kdump/kdump.txt
1513 bool "kexec jump (EXPERIMENTAL)"
1514 depends on EXPERIMENTAL
1515 depends on KEXEC && HIBERNATION
1517 Jump between original kernel and kexeced kernel and invoke
1518 code in physical address mode via KEXEC
1520 config PHYSICAL_START
1521 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1524 This gives the physical address where the kernel is loaded.
1526 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1527 bzImage will decompress itself to above physical address and
1528 run from there. Otherwise, bzImage will run from the address where
1529 it has been loaded by the boot loader and will ignore above physical
1532 In normal kdump cases one does not have to set/change this option
1533 as now bzImage can be compiled as a completely relocatable image
1534 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1535 address. This option is mainly useful for the folks who don't want
1536 to use a bzImage for capturing the crash dump and want to use a
1537 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1538 to be specifically compiled to run from a specific memory area
1539 (normally a reserved region) and this option comes handy.
1541 So if you are using bzImage for capturing the crash dump,
1542 leave the value here unchanged to 0x1000000 and set
1543 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1544 for capturing the crash dump change this value to start of
1545 the reserved region. In other words, it can be set based on
1546 the "X" value as specified in the "crashkernel=YM@XM"
1547 command line boot parameter passed to the panic-ed
1548 kernel. Please take a look at Documentation/kdump/kdump.txt
1549 for more details about crash dumps.
1551 Usage of bzImage for capturing the crash dump is recommended as
1552 one does not have to build two kernels. Same kernel can be used
1553 as production kernel and capture kernel. Above option should have
1554 gone away after relocatable bzImage support is introduced. But it
1555 is present because there are users out there who continue to use
1556 vmlinux for dump capture. This option should go away down the
1559 Don't change this unless you know what you are doing.
1562 bool "Build a relocatable kernel"
1565 This builds a kernel image that retains relocation information
1566 so it can be loaded someplace besides the default 1MB.
1567 The relocations tend to make the kernel binary about 10% larger,
1568 but are discarded at runtime.
1570 One use is for the kexec on panic case where the recovery kernel
1571 must live at a different physical address than the primary
1574 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1575 it has been loaded at and the compile time physical address
1576 (CONFIG_PHYSICAL_START) is ignored.
1578 # Relocation on x86-32 needs some additional build support
1579 config X86_NEED_RELOCS
1581 depends on X86_32 && RELOCATABLE
1583 config PHYSICAL_ALIGN
1585 prompt "Alignment value to which kernel should be aligned" if X86_32
1587 range 0x2000 0x1000000
1589 This value puts the alignment restrictions on physical address
1590 where kernel is loaded and run from. Kernel is compiled for an
1591 address which meets above alignment restriction.
1593 If bootloader loads the kernel at a non-aligned address and
1594 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1595 address aligned to above value and run from there.
1597 If bootloader loads the kernel at a non-aligned address and
1598 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1599 load address and decompress itself to the address it has been
1600 compiled for and run from there. The address for which kernel is
1601 compiled already meets above alignment restrictions. Hence the
1602 end result is that kernel runs from a physical address meeting
1603 above alignment restrictions.
1605 Don't change this unless you know what you are doing.
1608 bool "Support for hot-pluggable CPUs"
1609 depends on SMP && HOTPLUG
1611 Say Y here to allow turning CPUs off and on. CPUs can be
1612 controlled through /sys/devices/system/cpu.
1613 ( Note: power management support will enable this option
1614 automatically on SMP systems. )
1615 Say N if you want to disable CPU hotplug.
1619 prompt "Compat VDSO support"
1620 depends on X86_32 || IA32_EMULATION
1622 Map the 32-bit VDSO to the predictable old-style address too.
1624 Say N here if you are running a sufficiently recent glibc
1625 version (2.3.3 or later), to remove the high-mapped
1626 VDSO mapping and to exclusively use the randomized VDSO.
1631 bool "Built-in kernel command line"
1634 Allow for specifying boot arguments to the kernel at
1635 build time. On some systems (e.g. embedded ones), it is
1636 necessary or convenient to provide some or all of the
1637 kernel boot arguments with the kernel itself (that is,
1638 to not rely on the boot loader to provide them.)
1640 To compile command line arguments into the kernel,
1641 set this option to 'Y', then fill in the
1642 the boot arguments in CONFIG_CMDLINE.
1644 Systems with fully functional boot loaders (i.e. non-embedded)
1645 should leave this option set to 'N'.
1648 string "Built-in kernel command string"
1649 depends on CMDLINE_BOOL
1652 Enter arguments here that should be compiled into the kernel
1653 image and used at boot time. If the boot loader provides a
1654 command line at boot time, it is appended to this string to
1655 form the full kernel command line, when the system boots.
1657 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1658 change this behavior.
1660 In most cases, the command line (whether built-in or provided
1661 by the boot loader) should specify the device for the root
1664 config CMDLINE_OVERRIDE
1665 bool "Built-in command line overrides boot loader arguments"
1667 depends on CMDLINE_BOOL
1669 Set this option to 'Y' to have the kernel ignore the boot loader
1670 command line, and use ONLY the built-in command line.
1672 This is used to work around broken boot loaders. This should
1673 be set to 'N' under normal conditions.
1677 config ARCH_ENABLE_MEMORY_HOTPLUG
1679 depends on X86_64 || (X86_32 && HIGHMEM)
1681 config ARCH_ENABLE_MEMORY_HOTREMOVE
1683 depends on MEMORY_HOTPLUG
1685 config HAVE_ARCH_EARLY_PFN_TO_NID
1689 menu "Power management and ACPI options"
1691 config ARCH_HIBERNATION_HEADER
1693 depends on X86_64 && HIBERNATION
1695 source "kernel/power/Kconfig"
1697 source "drivers/acpi/Kconfig"
1699 source "drivers/sfi/Kconfig"
1704 depends on APM || APM_MODULE
1707 tristate "APM (Advanced Power Management) BIOS support"
1708 depends on X86_32 && PM_SLEEP
1710 APM is a BIOS specification for saving power using several different
1711 techniques. This is mostly useful for battery powered laptops with
1712 APM compliant BIOSes. If you say Y here, the system time will be
1713 reset after a RESUME operation, the /proc/apm device will provide
1714 battery status information, and user-space programs will receive
1715 notification of APM "events" (e.g. battery status change).
1717 If you select "Y" here, you can disable actual use of the APM
1718 BIOS by passing the "apm=off" option to the kernel at boot time.
1720 Note that the APM support is almost completely disabled for
1721 machines with more than one CPU.
1723 In order to use APM, you will need supporting software. For location
1724 and more information, read <file:Documentation/power/pm.txt> and the
1725 Battery Powered Linux mini-HOWTO, available from
1726 <http://www.tldp.org/docs.html#howto>.
1728 This driver does not spin down disk drives (see the hdparm(8)
1729 manpage ("man 8 hdparm") for that), and it doesn't turn off
1730 VESA-compliant "green" monitors.
1732 This driver does not support the TI 4000M TravelMate and the ACER
1733 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1734 desktop machines also don't have compliant BIOSes, and this driver
1735 may cause those machines to panic during the boot phase.
1737 Generally, if you don't have a battery in your machine, there isn't
1738 much point in using this driver and you should say N. If you get
1739 random kernel OOPSes or reboots that don't seem to be related to
1740 anything, try disabling/enabling this option (or disabling/enabling
1743 Some other things you should try when experiencing seemingly random,
1746 1) make sure that you have enough swap space and that it is
1748 2) pass the "no-hlt" option to the kernel
1749 3) switch on floating point emulation in the kernel and pass
1750 the "no387" option to the kernel
1751 4) pass the "floppy=nodma" option to the kernel
1752 5) pass the "mem=4M" option to the kernel (thereby disabling
1753 all but the first 4 MB of RAM)
1754 6) make sure that the CPU is not over clocked.
1755 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1756 8) disable the cache from your BIOS settings
1757 9) install a fan for the video card or exchange video RAM
1758 10) install a better fan for the CPU
1759 11) exchange RAM chips
1760 12) exchange the motherboard.
1762 To compile this driver as a module, choose M here: the
1763 module will be called apm.
1767 config APM_IGNORE_USER_SUSPEND
1768 bool "Ignore USER SUSPEND"
1770 This option will ignore USER SUSPEND requests. On machines with a
1771 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1772 series notebooks, it is necessary to say Y because of a BIOS bug.
1774 config APM_DO_ENABLE
1775 bool "Enable PM at boot time"
1777 Enable APM features at boot time. From page 36 of the APM BIOS
1778 specification: "When disabled, the APM BIOS does not automatically
1779 power manage devices, enter the Standby State, enter the Suspend
1780 State, or take power saving steps in response to CPU Idle calls."
1781 This driver will make CPU Idle calls when Linux is idle (unless this
1782 feature is turned off -- see "Do CPU IDLE calls", below). This
1783 should always save battery power, but more complicated APM features
1784 will be dependent on your BIOS implementation. You may need to turn
1785 this option off if your computer hangs at boot time when using APM
1786 support, or if it beeps continuously instead of suspending. Turn
1787 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1788 T400CDT. This is off by default since most machines do fine without
1792 bool "Make CPU Idle calls when idle"
1794 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1795 On some machines, this can activate improved power savings, such as
1796 a slowed CPU clock rate, when the machine is idle. These idle calls
1797 are made after the idle loop has run for some length of time (e.g.,
1798 333 mS). On some machines, this will cause a hang at boot time or
1799 whenever the CPU becomes idle. (On machines with more than one CPU,
1800 this option does nothing.)
1802 config APM_DISPLAY_BLANK
1803 bool "Enable console blanking using APM"
1805 Enable console blanking using the APM. Some laptops can use this to
1806 turn off the LCD backlight when the screen blanker of the Linux
1807 virtual console blanks the screen. Note that this is only used by
1808 the virtual console screen blanker, and won't turn off the backlight
1809 when using the X Window system. This also doesn't have anything to
1810 do with your VESA-compliant power-saving monitor. Further, this
1811 option doesn't work for all laptops -- it might not turn off your
1812 backlight at all, or it might print a lot of errors to the console,
1813 especially if you are using gpm.
1815 config APM_ALLOW_INTS
1816 bool "Allow interrupts during APM BIOS calls"
1818 Normally we disable external interrupts while we are making calls to
1819 the APM BIOS as a measure to lessen the effects of a badly behaving
1820 BIOS implementation. The BIOS should reenable interrupts if it
1821 needs to. Unfortunately, some BIOSes do not -- especially those in
1822 many of the newer IBM Thinkpads. If you experience hangs when you
1823 suspend, try setting this to Y. Otherwise, say N.
1827 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1829 source "drivers/cpuidle/Kconfig"
1831 source "drivers/idle/Kconfig"
1836 menu "Bus options (PCI etc.)"
1841 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1843 Find out whether you have a PCI motherboard. PCI is the name of a
1844 bus system, i.e. the way the CPU talks to the other stuff inside
1845 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1846 VESA. If you have PCI, say Y, otherwise N.
1849 prompt "PCI access mode"
1850 depends on X86_32 && PCI
1853 On PCI systems, the BIOS can be used to detect the PCI devices and
1854 determine their configuration. However, some old PCI motherboards
1855 have BIOS bugs and may crash if this is done. Also, some embedded
1856 PCI-based systems don't have any BIOS at all. Linux can also try to
1857 detect the PCI hardware directly without using the BIOS.
1859 With this option, you can specify how Linux should detect the
1860 PCI devices. If you choose "BIOS", the BIOS will be used,
1861 if you choose "Direct", the BIOS won't be used, and if you
1862 choose "MMConfig", then PCI Express MMCONFIG will be used.
1863 If you choose "Any", the kernel will try MMCONFIG, then the
1864 direct access method and falls back to the BIOS if that doesn't
1865 work. If unsure, go with the default, which is "Any".
1870 config PCI_GOMMCONFIG
1887 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1889 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1892 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1896 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
1900 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1907 bool "Support mmconfig PCI config space access"
1908 depends on X86_64 && PCI && ACPI
1911 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1912 depends on PCI_MSI && ACPI && EXPERIMENTAL
1914 DMA remapping (DMAR) devices support enables independent address
1915 translations for Direct Memory Access (DMA) from devices.
1916 These DMA remapping devices are reported via ACPI tables
1917 and include PCI device scope covered by these DMA
1920 config DMAR_DEFAULT_ON
1922 prompt "Enable DMA Remapping Devices by default"
1925 Selecting this option will enable a DMAR device at boot time if
1926 one is found. If this option is not selected, DMAR support can
1927 be enabled by passing intel_iommu=on to the kernel. It is
1928 recommended you say N here while the DMAR code remains
1931 config DMAR_BROKEN_GFX_WA
1933 prompt "Workaround broken graphics drivers (going away soon)"
1934 depends on DMAR && BROKEN
1936 Current Graphics drivers tend to use physical address
1937 for DMA and avoid using DMA APIs. Setting this config
1938 option permits the IOMMU driver to set a unity map for
1939 all the OS-visible memory. Hence the driver can continue
1940 to use physical addresses for DMA, at least until this
1941 option is removed in the 2.6.32 kernel.
1943 config DMAR_FLOPPY_WA
1947 Floppy disk drivers are known to bypass DMA API calls
1948 thereby failing to work when IOMMU is enabled. This
1949 workaround will setup a 1:1 mapping for the first
1950 16MiB to make floppy (an ISA device) work.
1953 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1954 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1956 Supports Interrupt remapping for IO-APIC and MSI devices.
1957 To use x2apic mode in the CPU's which support x2APIC enhancements or
1958 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1960 source "drivers/pci/pcie/Kconfig"
1962 source "drivers/pci/Kconfig"
1964 # x86_64 have no ISA slots, but do have ISA-style DMA.
1973 Find out whether you have ISA slots on your motherboard. ISA is the
1974 name of a bus system, i.e. the way the CPU talks to the other stuff
1975 inside your box. Other bus systems are PCI, EISA, MicroChannel
1976 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1977 newer boards don't support it. If you have ISA, say Y, otherwise N.
1983 The Extended Industry Standard Architecture (EISA) bus was
1984 developed as an open alternative to the IBM MicroChannel bus.
1986 The EISA bus provided some of the features of the IBM MicroChannel
1987 bus while maintaining backward compatibility with cards made for
1988 the older ISA bus. The EISA bus saw limited use between 1988 and
1989 1995 when it was made obsolete by the PCI bus.
1991 Say Y here if you are building a kernel for an EISA-based machine.
1995 source "drivers/eisa/Kconfig"
2000 MicroChannel Architecture is found in some IBM PS/2 machines and
2001 laptops. It is a bus system similar to PCI or ISA. See
2002 <file:Documentation/mca.txt> (and especially the web page given
2003 there) before attempting to build an MCA bus kernel.
2005 source "drivers/mca/Kconfig"
2008 tristate "NatSemi SCx200 support"
2010 This provides basic support for National Semiconductor's
2011 (now AMD's) Geode processors. The driver probes for the
2012 PCI-IDs of several on-chip devices, so its a good dependency
2013 for other scx200_* drivers.
2015 If compiled as a module, the driver is named scx200.
2017 config SCx200HR_TIMER
2018 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2019 depends on SCx200 && GENERIC_TIME
2022 This driver provides a clocksource built upon the on-chip
2023 27MHz high-resolution timer. Its also a workaround for
2024 NSC Geode SC-1100's buggy TSC, which loses time when the
2025 processor goes idle (as is done by the scheduler). The
2026 other workaround is idle=poll boot option.
2029 bool "One Laptop Per Child support"
2033 Add support for detecting the unique features of the OLPC
2040 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
2042 source "drivers/pcmcia/Kconfig"
2044 source "drivers/pci/hotplug/Kconfig"
2049 menu "Executable file formats / Emulations"
2051 source "fs/Kconfig.binfmt"
2053 config IA32_EMULATION
2054 bool "IA32 Emulation"
2056 select COMPAT_BINFMT_ELF
2058 Include code to run 32-bit programs under a 64-bit kernel. You should
2059 likely turn this on, unless you're 100% sure that you don't have any
2060 32-bit programs left.
2063 tristate "IA32 a.out support"
2064 depends on IA32_EMULATION
2066 Support old a.out binaries in the 32bit emulation.
2070 depends on IA32_EMULATION
2072 config COMPAT_FOR_U64_ALIGNMENT
2076 config SYSVIPC_COMPAT
2078 depends on COMPAT && SYSVIPC
2083 config HAVE_ATOMIC_IOMAP
2087 source "net/Kconfig"
2089 source "drivers/Kconfig"
2091 source "drivers/firmware/Kconfig"
2095 source "arch/x86/Kconfig.debug"
2097 source "security/Kconfig"
2099 source "crypto/Kconfig"
2101 source "arch/x86/kvm/Kconfig"
2103 source "lib/Kconfig"
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