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
35 select HAVE_FTRACE_MCOUNT_RECORD
36 select HAVE_DYNAMIC_FTRACE
37 select HAVE_FUNCTION_TRACER
38 select HAVE_FUNCTION_GRAPH_TRACER
39 select HAVE_FUNCTION_GRAPH_FP_TEST
40 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
41 select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
42 select HAVE_SYSCALL_TRACEPOINTS
45 select HAVE_ARCH_TRACEHOOK
46 select HAVE_GENERIC_DMA_COHERENT if X86_32
47 select HAVE_EFFICIENT_UNALIGNED_ACCESS
48 select USER_STACKTRACE_SUPPORT
49 select HAVE_REGS_AND_STACK_ACCESS_API
50 select HAVE_DMA_API_DEBUG
51 select HAVE_KERNEL_GZIP
52 select HAVE_KERNEL_BZIP2
53 select HAVE_KERNEL_LZMA
54 select HAVE_KERNEL_LZO
55 select HAVE_HW_BREAKPOINT
58 select HAVE_ARCH_KMEMCHECK
59 select HAVE_USER_RETURN_NOTIFIER
61 config INSTRUCTION_DECODER
62 def_bool (KPROBES || PERF_EVENTS)
66 default "elf32-i386" if X86_32
67 default "elf64-x86-64" if X86_64
71 default "arch/x86/configs/i386_defconfig" if X86_32
72 default "arch/x86/configs/x86_64_defconfig" if X86_64
77 config GENERIC_CMOS_UPDATE
80 config CLOCKSOURCE_WATCHDOG
83 config GENERIC_CLOCKEVENTS
86 config GENERIC_CLOCKEVENTS_BROADCAST
88 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
90 config LOCKDEP_SUPPORT
93 config STACKTRACE_SUPPORT
96 config HAVE_LATENCYTOP_SUPPORT
108 config GENERIC_ISA_DMA
117 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
119 config GENERIC_BUG_RELATIVE_POINTERS
122 config GENERIC_HWEIGHT
128 config ARCH_MAY_HAVE_PC_FDC
131 config RWSEM_GENERIC_SPINLOCK
134 config RWSEM_XCHGADD_ALGORITHM
137 config ARCH_HAS_CPU_IDLE_WAIT
140 config GENERIC_CALIBRATE_DELAY
143 config GENERIC_TIME_VSYSCALL
147 config ARCH_HAS_CPU_RELAX
150 config ARCH_HAS_DEFAULT_IDLE
153 config ARCH_HAS_CACHE_LINE_SIZE
156 config HAVE_SETUP_PER_CPU_AREA
159 config NEED_PER_CPU_EMBED_FIRST_CHUNK
162 config NEED_PER_CPU_PAGE_FIRST_CHUNK
165 config HAVE_CPUMASK_OF_CPU_MAP
168 config ARCH_HIBERNATION_POSSIBLE
171 config ARCH_SUSPEND_POSSIBLE
178 config ARCH_POPULATES_NODE_MAP
185 config ARCH_SUPPORTS_OPTIMIZED_INLINING
188 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
191 config HAVE_EARLY_RES
194 config HAVE_INTEL_TXT
196 depends on EXPERIMENTAL && DMAR && ACPI
198 # Use the generic interrupt handling code in kernel/irq/:
199 config GENERIC_HARDIRQS
203 config GENERIC_HARDIRQS_NO__DO_IRQ
206 config GENERIC_IRQ_PROBE
210 config GENERIC_PENDING_IRQ
212 depends on GENERIC_HARDIRQS && SMP
215 config USE_GENERIC_SMP_HELPERS
221 depends on X86_32 && SMP
225 depends on X86_64 && SMP
232 config X86_TRAMPOLINE
234 depends on SMP || (64BIT && ACPI_SLEEP)
237 config X86_32_LAZY_GS
239 depends on X86_32 && !CC_STACKPROTECTOR
243 source "init/Kconfig"
244 source "kernel/Kconfig.freezer"
246 menu "Processor type and features"
248 source "kernel/time/Kconfig"
251 bool "Symmetric multi-processing support"
253 This enables support for systems with more than one CPU. If you have
254 a system with only one CPU, like most personal computers, say N. If
255 you have a system with more than one CPU, say Y.
257 If you say N here, the kernel will run on single and multiprocessor
258 machines, but will use only one CPU of a multiprocessor machine. If
259 you say Y here, the kernel will run on many, but not all,
260 singleprocessor machines. On a singleprocessor machine, the kernel
261 will run faster if you say N here.
263 Note that if you say Y here and choose architecture "586" or
264 "Pentium" under "Processor family", the kernel will not work on 486
265 architectures. Similarly, multiprocessor kernels for the "PPro"
266 architecture may not work on all Pentium based boards.
268 People using multiprocessor machines who say Y here should also say
269 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
270 Management" code will be disabled if you say Y here.
272 See also <file:Documentation/i386/IO-APIC.txt>,
273 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
274 <http://www.tldp.org/docs.html#howto>.
276 If you don't know what to do here, say N.
279 bool "Support x2apic"
280 depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
282 This enables x2apic support on CPUs that have this feature.
284 This allows 32-bit apic IDs (so it can support very large systems),
285 and accesses the local apic via MSRs not via mmio.
287 If you don't know what to do here, say N.
290 bool "Support sparse irq numbering"
291 depends on PCI_MSI || HT_IRQ
293 This enables support for sparse irqs. This is useful for distro
294 kernels that want to define a high CONFIG_NR_CPUS value but still
295 want to have low kernel memory footprint on smaller machines.
297 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
298 out the irq_desc[] array in a more NUMA-friendly way. )
300 If you don't know what to do here, say N.
304 depends on SPARSE_IRQ && NUMA
307 bool "Enable MPS table" if ACPI
309 depends on X86_LOCAL_APIC
311 For old smp systems that do not have proper acpi support. Newer systems
312 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
315 bool "Support for big SMP systems with more than 8 CPUs"
316 depends on X86_32 && SMP
318 This option is needed for the systems that have more than 8 CPUs
321 config X86_EXTENDED_PLATFORM
322 bool "Support for extended (non-PC) x86 platforms"
325 If you disable this option then the kernel will only support
326 standard PC platforms. (which covers the vast majority of
329 If you enable this option then you'll be able to select support
330 for the following (non-PC) 32 bit x86 platforms:
334 SGI 320/540 (Visual Workstation)
335 Summit/EXA (IBM x440)
336 Unisys ES7000 IA32 series
337 Moorestown MID devices
339 If you have one of these systems, or if you want to build a
340 generic distribution kernel, say Y here - otherwise say N.
344 config X86_EXTENDED_PLATFORM
345 bool "Support for extended (non-PC) x86 platforms"
348 If you disable this option then the kernel will only support
349 standard PC platforms. (which covers the vast majority of
352 If you enable this option then you'll be able to select support
353 for the following (non-PC) 64 bit x86 platforms:
357 If you have one of these systems, or if you want to build a
358 generic distribution kernel, say Y here - otherwise say N.
360 # This is an alphabetically sorted list of 64 bit extended platforms
361 # Please maintain the alphabetic order if and when there are additions
366 depends on X86_64 && PCI
367 depends on X86_EXTENDED_PLATFORM
369 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
370 supposed to run on these EM64T-based machines. Only choose this option
371 if you have one of these machines.
374 bool "SGI Ultraviolet"
376 depends on X86_EXTENDED_PLATFORM
378 depends on X86_X2APIC
380 This option is needed in order to support SGI Ultraviolet systems.
381 If you don't have one of these, you should say N here.
383 # Following is an alphabetically sorted list of 32 bit extended platforms
384 # Please maintain the alphabetic order if and when there are additions
389 depends on X86_EXTENDED_PLATFORM
391 Select this for an AMD Elan processor.
393 Do not use this option for K6/Athlon/Opteron processors!
395 If unsure, choose "PC-compatible" instead.
398 bool "Moorestown MID platform"
402 depends on X86_EXTENDED_PLATFORM
403 depends on X86_IO_APIC
406 Moorestown is Intel's Low Power Intel Architecture (LPIA) based Moblin
407 Internet Device(MID) platform. Moorestown consists of two chips:
408 Lincroft (CPU core, graphics, and memory controller) and Langwell IOH.
409 Unlike standard x86 PCs, Moorestown does not have many legacy devices
410 nor standard legacy replacement devices/features. e.g. Moorestown does
411 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
414 bool "RDC R-321x SoC"
416 depends on X86_EXTENDED_PLATFORM
418 select X86_REBOOTFIXUPS
420 This option is needed for RDC R-321x system-on-chip, also known
422 If you don't have one of these chips, you should say N here.
424 config X86_32_NON_STANDARD
425 bool "Support non-standard 32-bit SMP architectures"
426 depends on X86_32 && SMP
427 depends on X86_EXTENDED_PLATFORM
429 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
430 subarchitectures. It is intended for a generic binary kernel.
431 if you select them all, kernel will probe it one by one. and will
434 # Alphabetically sorted list of Non standard 32 bit platforms
437 bool "NUMAQ (IBM/Sequent)"
438 depends on X86_32_NON_STANDARD
443 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
444 NUMA multiquad box. This changes the way that processors are
445 bootstrapped, and uses Clustered Logical APIC addressing mode instead
446 of Flat Logical. You will need a new lynxer.elf file to flash your
447 firmware with - send email to <Martin.Bligh@us.ibm.com>.
449 config X86_SUPPORTS_MEMORY_FAILURE
451 # MCE code calls memory_failure():
453 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
454 depends on !X86_NUMAQ
455 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
456 depends on X86_64 || !SPARSEMEM
457 select ARCH_SUPPORTS_MEMORY_FAILURE
461 bool "SGI 320/540 (Visual Workstation)"
462 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
463 depends on X86_32_NON_STANDARD
465 The SGI Visual Workstation series is an IA32-based workstation
466 based on SGI systems chips with some legacy PC hardware attached.
468 Say Y here to create a kernel to run on the SGI 320 or 540.
470 A kernel compiled for the Visual Workstation will run on general
471 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
474 bool "Summit/EXA (IBM x440)"
475 depends on X86_32_NON_STANDARD
477 This option is needed for IBM systems that use the Summit/EXA chipset.
478 In particular, it is needed for the x440.
481 bool "Unisys ES7000 IA32 series"
482 depends on X86_32_NON_STANDARD && X86_BIGSMP
484 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
485 supposed to run on an IA32-based Unisys ES7000 system.
487 config SCHED_OMIT_FRAME_POINTER
489 prompt "Single-depth WCHAN output"
492 Calculate simpler /proc/<PID>/wchan values. If this option
493 is disabled then wchan values will recurse back to the
494 caller function. This provides more accurate wchan values,
495 at the expense of slightly more scheduling overhead.
497 If in doubt, say "Y".
499 menuconfig PARAVIRT_GUEST
500 bool "Paravirtualized guest support"
502 Say Y here to get to see options related to running Linux under
503 various hypervisors. This option alone does not add any kernel code.
505 If you say N, all options in this submenu will be skipped and disabled.
509 source "arch/x86/xen/Kconfig"
512 bool "VMI Guest support (DEPRECATED)"
516 VMI provides a paravirtualized interface to the VMware ESX server
517 (it could be used by other hypervisors in theory too, but is not
518 at the moment), by linking the kernel to a GPL-ed ROM module
519 provided by the hypervisor.
521 As of September 2009, VMware has started a phased retirement
522 of this feature from VMware's products. Please see
523 feature-removal-schedule.txt for details. If you are
524 planning to enable this option, please note that you cannot
525 live migrate a VMI enabled VM to a future VMware product,
526 which doesn't support VMI. So if you expect your kernel to
527 seamlessly migrate to newer VMware products, keep this
531 bool "KVM paravirtualized clock"
533 select PARAVIRT_CLOCK
535 Turning on this option will allow you to run a paravirtualized clock
536 when running over the KVM hypervisor. Instead of relying on a PIT
537 (or probably other) emulation by the underlying device model, the host
538 provides the guest with timing infrastructure such as time of day, and
542 bool "KVM Guest support"
545 This option enables various optimizations for running under the KVM
548 source "arch/x86/lguest/Kconfig"
551 bool "Enable paravirtualization code"
553 This changes the kernel so it can modify itself when it is run
554 under a hypervisor, potentially improving performance significantly
555 over full virtualization. However, when run without a hypervisor
556 the kernel is theoretically slower and slightly larger.
558 config PARAVIRT_SPINLOCKS
559 bool "Paravirtualization layer for spinlocks"
560 depends on PARAVIRT && SMP && EXPERIMENTAL
562 Paravirtualized spinlocks allow a pvops backend to replace the
563 spinlock implementation with something virtualization-friendly
564 (for example, block the virtual CPU rather than spinning).
566 Unfortunately the downside is an up to 5% performance hit on
567 native kernels, with various workloads.
569 If you are unsure how to answer this question, answer N.
571 config PARAVIRT_CLOCK
577 config PARAVIRT_DEBUG
578 bool "paravirt-ops debugging"
579 depends on PARAVIRT && DEBUG_KERNEL
581 Enable to debug paravirt_ops internals. Specifically, BUG if
582 a paravirt_op is missing when it is called.
586 bool "Disable Bootmem code"
588 Use early_res directly instead of bootmem before slab is ready.
589 - allocator (buddy) [generic]
590 - early allocator (bootmem) [generic]
591 - very early allocator (reserve_early*()) [x86]
592 - very very early allocator (early brk model) [x86]
593 So reduce one layer between early allocator to final allocator
599 This option adds a kernel parameter 'memtest', which allows memtest
601 memtest=0, mean disabled; -- default
602 memtest=1, mean do 1 test pattern;
604 memtest=4, mean do 4 test patterns.
605 If you are unsure how to answer this question, answer N.
607 config X86_SUMMIT_NUMA
609 depends on X86_32 && NUMA && X86_32_NON_STANDARD
611 config X86_CYCLONE_TIMER
613 depends on X86_32_NON_STANDARD
615 source "arch/x86/Kconfig.cpu"
619 prompt "HPET Timer Support" if X86_32
621 Use the IA-PC HPET (High Precision Event Timer) to manage
622 time in preference to the PIT and RTC, if a HPET is
624 HPET is the next generation timer replacing legacy 8254s.
625 The HPET provides a stable time base on SMP
626 systems, unlike the TSC, but it is more expensive to access,
627 as it is off-chip. You can find the HPET spec at
628 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
630 You can safely choose Y here. However, HPET will only be
631 activated if the platform and the BIOS support this feature.
632 Otherwise the 8254 will be used for timing services.
634 Choose N to continue using the legacy 8254 timer.
636 config HPET_EMULATE_RTC
638 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
642 prompt "Langwell APB Timer Support" if X86_MRST
644 APB timer is the replacement for 8254, HPET on X86 MID platforms.
645 The APBT provides a stable time base on SMP
646 systems, unlike the TSC, but it is more expensive to access,
647 as it is off-chip. APB timers are always running regardless of CPU
648 C states, they are used as per CPU clockevent device when possible.
650 # Mark as embedded because too many people got it wrong.
651 # The code disables itself when not needed.
654 bool "Enable DMI scanning" if EMBEDDED
656 Enabled scanning of DMI to identify machine quirks. Say Y
657 here unless you have verified that your setup is not
658 affected by entries in the DMI blacklist. Required by PNP
662 bool "GART IOMMU support" if EMBEDDED
665 depends on X86_64 && PCI
667 Support for full DMA access of devices with 32bit memory access only
668 on systems with more than 3GB. This is usually needed for USB,
669 sound, many IDE/SATA chipsets and some other devices.
670 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
671 based hardware IOMMU and a software bounce buffer based IOMMU used
672 on Intel systems and as fallback.
673 The code is only active when needed (enough memory and limited
674 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
678 bool "IBM Calgary IOMMU support"
680 depends on X86_64 && PCI && EXPERIMENTAL
682 Support for hardware IOMMUs in IBM's xSeries x366 and x460
683 systems. Needed to run systems with more than 3GB of memory
684 properly with 32-bit PCI devices that do not support DAC
685 (Double Address Cycle). Calgary also supports bus level
686 isolation, where all DMAs pass through the IOMMU. This
687 prevents them from going anywhere except their intended
688 destination. This catches hard-to-find kernel bugs and
689 mis-behaving drivers and devices that do not use the DMA-API
690 properly to set up their DMA buffers. The IOMMU can be
691 turned off at boot time with the iommu=off parameter.
692 Normally the kernel will make the right choice by itself.
695 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
697 prompt "Should Calgary be enabled by default?"
698 depends on CALGARY_IOMMU
700 Should Calgary be enabled by default? if you choose 'y', Calgary
701 will be used (if it exists). If you choose 'n', Calgary will not be
702 used even if it exists. If you choose 'n' and would like to use
703 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
707 bool "AMD IOMMU support"
710 depends on X86_64 && PCI && ACPI
712 With this option you can enable support for AMD IOMMU hardware in
713 your system. An IOMMU is a hardware component which provides
714 remapping of DMA memory accesses from devices. With an AMD IOMMU you
715 can isolate the the DMA memory of different devices and protect the
716 system from misbehaving device drivers or hardware.
718 You can find out if your system has an AMD IOMMU if you look into
719 your BIOS for an option to enable it or if you have an IVRS ACPI
722 config AMD_IOMMU_STATS
723 bool "Export AMD IOMMU statistics to debugfs"
727 This option enables code in the AMD IOMMU driver to collect various
728 statistics about whats happening in the driver and exports that
729 information to userspace via debugfs.
732 # need this always selected by IOMMU for the VIA workaround
736 Support for software bounce buffers used on x86-64 systems
737 which don't have a hardware IOMMU (e.g. the current generation
738 of Intel's x86-64 CPUs). Using this PCI devices which can only
739 access 32-bits of memory can be used on systems with more than
740 3 GB of memory. If unsure, say Y.
743 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
746 def_bool (AMD_IOMMU || DMAR)
749 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
750 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
751 select CPUMASK_OFFSTACK
754 Configure maximum number of CPUS and NUMA Nodes for this architecture.
758 int "Maximum number of CPUs" if SMP && !MAXSMP
759 range 2 8 if SMP && X86_32 && !X86_BIGSMP
760 range 2 512 if SMP && !MAXSMP
762 default "4096" if MAXSMP
763 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
766 This allows you to specify the maximum number of CPUs which this
767 kernel will support. The maximum supported value is 512 and the
768 minimum value which makes sense is 2.
770 This is purely to save memory - each supported CPU adds
771 approximately eight kilobytes to the kernel image.
774 bool "SMT (Hyperthreading) scheduler support"
777 SMT scheduler support improves the CPU scheduler's decision making
778 when dealing with Intel Pentium 4 chips with HyperThreading at a
779 cost of slightly increased overhead in some places. If unsure say
784 prompt "Multi-core scheduler support"
787 Multi-core scheduler support improves the CPU scheduler's decision
788 making when dealing with multi-core CPU chips at a cost of slightly
789 increased overhead in some places. If unsure say N here.
791 source "kernel/Kconfig.preempt"
794 bool "Local APIC support on uniprocessors"
795 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
797 A local APIC (Advanced Programmable Interrupt Controller) is an
798 integrated interrupt controller in the CPU. If you have a single-CPU
799 system which has a processor with a local APIC, you can say Y here to
800 enable and use it. If you say Y here even though your machine doesn't
801 have a local APIC, then the kernel will still run with no slowdown at
802 all. The local APIC supports CPU-generated self-interrupts (timer,
803 performance counters), and the NMI watchdog which detects hard
807 bool "IO-APIC support on uniprocessors"
808 depends on X86_UP_APIC
810 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
811 SMP-capable replacement for PC-style interrupt controllers. Most
812 SMP systems and many recent uniprocessor systems have one.
814 If you have a single-CPU system with an IO-APIC, you can say Y here
815 to use it. If you say Y here even though your machine doesn't have
816 an IO-APIC, then the kernel will still run with no slowdown at all.
818 config X86_LOCAL_APIC
820 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
824 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
826 config X86_VISWS_APIC
828 depends on X86_32 && X86_VISWS
830 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
831 bool "Reroute for broken boot IRQs"
833 depends on X86_IO_APIC
835 This option enables a workaround that fixes a source of
836 spurious interrupts. This is recommended when threaded
837 interrupt handling is used on systems where the generation of
838 superfluous "boot interrupts" cannot be disabled.
840 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
841 entry in the chipset's IO-APIC is masked (as, e.g. the RT
842 kernel does during interrupt handling). On chipsets where this
843 boot IRQ generation cannot be disabled, this workaround keeps
844 the original IRQ line masked so that only the equivalent "boot
845 IRQ" is delivered to the CPUs. The workaround also tells the
846 kernel to set up the IRQ handler on the boot IRQ line. In this
847 way only one interrupt is delivered to the kernel. Otherwise
848 the spurious second interrupt may cause the kernel to bring
849 down (vital) interrupt lines.
851 Only affects "broken" chipsets. Interrupt sharing may be
852 increased on these systems.
855 bool "Machine Check / overheating reporting"
857 Machine Check support allows the processor to notify the
858 kernel if it detects a problem (e.g. overheating, data corruption).
859 The action the kernel takes depends on the severity of the problem,
860 ranging from warning messages to halting the machine.
864 prompt "Intel MCE features"
865 depends on X86_MCE && X86_LOCAL_APIC
867 Additional support for intel specific MCE features such as
872 prompt "AMD MCE features"
873 depends on X86_MCE && X86_LOCAL_APIC
875 Additional support for AMD specific MCE features such as
876 the DRAM Error Threshold.
878 config X86_ANCIENT_MCE
880 depends on X86_32 && X86_MCE
881 prompt "Support for old Pentium 5 / WinChip machine checks"
883 Include support for machine check handling on old Pentium 5 or WinChip
884 systems. These typically need to be enabled explicitely on the command
887 config X86_MCE_THRESHOLD
888 depends on X86_MCE_AMD || X86_MCE_INTEL
892 config X86_MCE_INJECT
894 tristate "Machine check injector support"
896 Provide support for injecting machine checks for testing purposes.
897 If you don't know what a machine check is and you don't do kernel
898 QA it is safe to say n.
900 config X86_THERMAL_VECTOR
902 depends on X86_MCE_INTEL
905 bool "Enable VM86 support" if EMBEDDED
909 This option is required by programs like DOSEMU to run 16-bit legacy
910 code on X86 processors. It also may be needed by software like
911 XFree86 to initialize some video cards via BIOS. Disabling this
912 option saves about 6k.
915 tristate "Toshiba Laptop support"
918 This adds a driver to safely access the System Management Mode of
919 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
920 not work on models with a Phoenix BIOS. The System Management Mode
921 is used to set the BIOS and power saving options on Toshiba portables.
923 For information on utilities to make use of this driver see the
924 Toshiba Linux utilities web site at:
925 <http://www.buzzard.org.uk/toshiba/>.
927 Say Y if you intend to run this kernel on a Toshiba portable.
931 tristate "Dell laptop support"
933 This adds a driver to safely access the System Management Mode
934 of the CPU on the Dell Inspiron 8000. The System Management Mode
935 is used to read cpu temperature and cooling fan status and to
936 control the fans on the I8K portables.
938 This driver has been tested only on the Inspiron 8000 but it may
939 also work with other Dell laptops. You can force loading on other
940 models by passing the parameter `force=1' to the module. Use at
943 For information on utilities to make use of this driver see the
944 I8K Linux utilities web site at:
945 <http://people.debian.org/~dz/i8k/>
947 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
950 config X86_REBOOTFIXUPS
951 bool "Enable X86 board specific fixups for reboot"
954 This enables chipset and/or board specific fixups to be done
955 in order to get reboot to work correctly. This is only needed on
956 some combinations of hardware and BIOS. The symptom, for which
957 this config is intended, is when reboot ends with a stalled/hung
960 Currently, the only fixup is for the Geode machines using
961 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
963 Say Y if you want to enable the fixup. Currently, it's safe to
964 enable this option even if you don't need it.
968 tristate "/dev/cpu/microcode - microcode support"
971 If you say Y here, you will be able to update the microcode on
972 certain Intel and AMD processors. The Intel support is for the
973 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
974 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
975 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
976 You will obviously need the actual microcode binary data itself
977 which is not shipped with the Linux kernel.
979 This option selects the general module only, you need to select
980 at least one vendor specific module as well.
982 To compile this driver as a module, choose M here: the
983 module will be called microcode.
985 config MICROCODE_INTEL
986 bool "Intel microcode patch loading support"
991 This options enables microcode patch loading support for Intel
994 For latest news and information on obtaining all the required
995 Intel ingredients for this driver, check:
996 <http://www.urbanmyth.org/microcode/>.
999 bool "AMD microcode patch loading support"
1000 depends on MICROCODE
1003 If you select this option, microcode patch loading support for AMD
1004 processors will be enabled.
1006 config MICROCODE_OLD_INTERFACE
1008 depends on MICROCODE
1011 tristate "/dev/cpu/*/msr - Model-specific register support"
1013 This device gives privileged processes access to the x86
1014 Model-Specific Registers (MSRs). It is a character device with
1015 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1016 MSR accesses are directed to a specific CPU on multi-processor
1020 tristate "/dev/cpu/*/cpuid - CPU information support"
1022 This device gives processes access to the x86 CPUID instruction to
1023 be executed on a specific processor. It is a character device
1024 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1028 prompt "High Memory Support"
1029 default HIGHMEM4G if !X86_NUMAQ
1030 default HIGHMEM64G if X86_NUMAQ
1035 depends on !X86_NUMAQ
1037 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1038 However, the address space of 32-bit x86 processors is only 4
1039 Gigabytes large. That means that, if you have a large amount of
1040 physical memory, not all of it can be "permanently mapped" by the
1041 kernel. The physical memory that's not permanently mapped is called
1044 If you are compiling a kernel which will never run on a machine with
1045 more than 1 Gigabyte total physical RAM, answer "off" here (default
1046 choice and suitable for most users). This will result in a "3GB/1GB"
1047 split: 3GB are mapped so that each process sees a 3GB virtual memory
1048 space and the remaining part of the 4GB virtual memory space is used
1049 by the kernel to permanently map as much physical memory as
1052 If the machine has between 1 and 4 Gigabytes physical RAM, then
1055 If more than 4 Gigabytes is used then answer "64GB" here. This
1056 selection turns Intel PAE (Physical Address Extension) mode on.
1057 PAE implements 3-level paging on IA32 processors. PAE is fully
1058 supported by Linux, PAE mode is implemented on all recent Intel
1059 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1060 then the kernel will not boot on CPUs that don't support PAE!
1062 The actual amount of total physical memory will either be
1063 auto detected or can be forced by using a kernel command line option
1064 such as "mem=256M". (Try "man bootparam" or see the documentation of
1065 your boot loader (lilo or loadlin) about how to pass options to the
1066 kernel at boot time.)
1068 If unsure, say "off".
1072 depends on !X86_NUMAQ
1074 Select this if you have a 32-bit processor and between 1 and 4
1075 gigabytes of physical RAM.
1079 depends on !M386 && !M486
1082 Select this if you have a 32-bit processor and more than 4
1083 gigabytes of physical RAM.
1088 depends on EXPERIMENTAL
1089 prompt "Memory split" if EMBEDDED
1093 Select the desired split between kernel and user memory.
1095 If the address range available to the kernel is less than the
1096 physical memory installed, the remaining memory will be available
1097 as "high memory". Accessing high memory is a little more costly
1098 than low memory, as it needs to be mapped into the kernel first.
1099 Note that increasing the kernel address space limits the range
1100 available to user programs, making the address space there
1101 tighter. Selecting anything other than the default 3G/1G split
1102 will also likely make your kernel incompatible with binary-only
1105 If you are not absolutely sure what you are doing, leave this
1109 bool "3G/1G user/kernel split"
1110 config VMSPLIT_3G_OPT
1112 bool "3G/1G user/kernel split (for full 1G low memory)"
1114 bool "2G/2G user/kernel split"
1115 config VMSPLIT_2G_OPT
1117 bool "2G/2G user/kernel split (for full 2G low memory)"
1119 bool "1G/3G user/kernel split"
1124 default 0xB0000000 if VMSPLIT_3G_OPT
1125 default 0x80000000 if VMSPLIT_2G
1126 default 0x78000000 if VMSPLIT_2G_OPT
1127 default 0x40000000 if VMSPLIT_1G
1133 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1136 bool "PAE (Physical Address Extension) Support"
1137 depends on X86_32 && !HIGHMEM4G
1139 PAE is required for NX support, and furthermore enables
1140 larger swapspace support for non-overcommit purposes. It
1141 has the cost of more pagetable lookup overhead, and also
1142 consumes more pagetable space per process.
1144 config ARCH_PHYS_ADDR_T_64BIT
1145 def_bool X86_64 || X86_PAE
1147 config DIRECT_GBPAGES
1148 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1152 Allow the kernel linear mapping to use 1GB pages on CPUs that
1153 support it. This can improve the kernel's performance a tiny bit by
1154 reducing TLB pressure. If in doubt, say "Y".
1156 # Common NUMA Features
1158 bool "Numa Memory Allocation and Scheduler Support"
1160 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1161 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1163 Enable NUMA (Non Uniform Memory Access) support.
1165 The kernel will try to allocate memory used by a CPU on the
1166 local memory controller of the CPU and add some more
1167 NUMA awareness to the kernel.
1169 For 64-bit this is recommended if the system is Intel Core i7
1170 (or later), AMD Opteron, or EM64T NUMA.
1172 For 32-bit this is only needed on (rare) 32-bit-only platforms
1173 that support NUMA topologies, such as NUMAQ / Summit, or if you
1174 boot a 32-bit kernel on a 64-bit NUMA platform.
1176 Otherwise, you should say N.
1178 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1179 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1183 prompt "Old style AMD Opteron NUMA detection"
1184 depends on X86_64 && NUMA && PCI
1186 Enable K8 NUMA node topology detection. You should say Y here if
1187 you have a multi processor AMD K8 system. This uses an old
1188 method to read the NUMA configuration directly from the builtin
1189 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1190 instead, which also takes priority if both are compiled in.
1192 config X86_64_ACPI_NUMA
1194 prompt "ACPI NUMA detection"
1195 depends on X86_64 && NUMA && ACPI && PCI
1198 Enable ACPI SRAT based node topology detection.
1200 # Some NUMA nodes have memory ranges that span
1201 # other nodes. Even though a pfn is valid and
1202 # between a node's start and end pfns, it may not
1203 # reside on that node. See memmap_init_zone()
1205 config NODES_SPAN_OTHER_NODES
1207 depends on X86_64_ACPI_NUMA
1210 bool "NUMA emulation"
1211 depends on X86_64 && NUMA
1213 Enable NUMA emulation. A flat machine will be split
1214 into virtual nodes when booted with "numa=fake=N", where N is the
1215 number of nodes. This is only useful for debugging.
1218 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1220 default "9" if MAXSMP
1221 default "6" if X86_64
1222 default "4" if X86_NUMAQ
1224 depends on NEED_MULTIPLE_NODES
1226 Specify the maximum number of NUMA Nodes available on the target
1227 system. Increases memory reserved to accommodate various tables.
1229 config HAVE_ARCH_BOOTMEM
1231 depends on X86_32 && NUMA
1233 config ARCH_HAVE_MEMORY_PRESENT
1235 depends on X86_32 && DISCONTIGMEM
1237 config NEED_NODE_MEMMAP_SIZE
1239 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1241 config HAVE_ARCH_ALLOC_REMAP
1243 depends on X86_32 && NUMA
1245 config ARCH_FLATMEM_ENABLE
1247 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1249 config ARCH_DISCONTIGMEM_ENABLE
1251 depends on NUMA && X86_32
1253 config ARCH_DISCONTIGMEM_DEFAULT
1255 depends on NUMA && X86_32
1257 config ARCH_PROC_KCORE_TEXT
1259 depends on X86_64 && PROC_KCORE
1261 config ARCH_SPARSEMEM_DEFAULT
1265 config ARCH_SPARSEMEM_ENABLE
1267 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1268 select SPARSEMEM_STATIC if X86_32
1269 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1271 config ARCH_SELECT_MEMORY_MODEL
1273 depends on ARCH_SPARSEMEM_ENABLE
1275 config ARCH_MEMORY_PROBE
1277 depends on MEMORY_HOTPLUG
1279 config ILLEGAL_POINTER_VALUE
1282 default 0xdead000000000000 if X86_64
1287 bool "Allocate 3rd-level pagetables from highmem"
1288 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1290 The VM uses one page table entry for each page of physical memory.
1291 For systems with a lot of RAM, this can be wasteful of precious
1292 low memory. Setting this option will put user-space page table
1293 entries in high memory.
1295 config X86_CHECK_BIOS_CORRUPTION
1296 bool "Check for low memory corruption"
1298 Periodically check for memory corruption in low memory, which
1299 is suspected to be caused by BIOS. Even when enabled in the
1300 configuration, it is disabled at runtime. Enable it by
1301 setting "memory_corruption_check=1" on the kernel command
1302 line. By default it scans the low 64k of memory every 60
1303 seconds; see the memory_corruption_check_size and
1304 memory_corruption_check_period parameters in
1305 Documentation/kernel-parameters.txt to adjust this.
1307 When enabled with the default parameters, this option has
1308 almost no overhead, as it reserves a relatively small amount
1309 of memory and scans it infrequently. It both detects corruption
1310 and prevents it from affecting the running system.
1312 It is, however, intended as a diagnostic tool; if repeatable
1313 BIOS-originated corruption always affects the same memory,
1314 you can use memmap= to prevent the kernel from using that
1317 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1318 bool "Set the default setting of memory_corruption_check"
1319 depends on X86_CHECK_BIOS_CORRUPTION
1322 Set whether the default state of memory_corruption_check is
1325 config X86_RESERVE_LOW_64K
1326 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1329 Reserve the first 64K of physical RAM on BIOSes that are known
1330 to potentially corrupt that memory range. A numbers of BIOSes are
1331 known to utilize this area during suspend/resume, so it must not
1332 be used by the kernel.
1334 Set this to N if you are absolutely sure that you trust the BIOS
1335 to get all its memory reservations and usages right.
1337 If you have doubts about the BIOS (e.g. suspend/resume does not
1338 work or there's kernel crashes after certain hardware hotplug
1339 events) and it's not AMI or Phoenix, then you might want to enable
1340 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1341 corruption patterns.
1345 config MATH_EMULATION
1347 prompt "Math emulation" if X86_32
1349 Linux can emulate a math coprocessor (used for floating point
1350 operations) if you don't have one. 486DX and Pentium processors have
1351 a math coprocessor built in, 486SX and 386 do not, unless you added
1352 a 487DX or 387, respectively. (The messages during boot time can
1353 give you some hints here ["man dmesg"].) Everyone needs either a
1354 coprocessor or this emulation.
1356 If you don't have a math coprocessor, you need to say Y here; if you
1357 say Y here even though you have a coprocessor, the coprocessor will
1358 be used nevertheless. (This behavior can be changed with the kernel
1359 command line option "no387", which comes handy if your coprocessor
1360 is broken. Try "man bootparam" or see the documentation of your boot
1361 loader (lilo or loadlin) about how to pass options to the kernel at
1362 boot time.) This means that it is a good idea to say Y here if you
1363 intend to use this kernel on different machines.
1365 More information about the internals of the Linux math coprocessor
1366 emulation can be found in <file:arch/x86/math-emu/README>.
1368 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1369 kernel, it won't hurt.
1374 prompt "MTRR (Memory Type Range Register) support" if EMBEDDED
1376 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1377 the Memory Type Range Registers (MTRRs) may be used to control
1378 processor access to memory ranges. This is most useful if you have
1379 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1380 allows bus write transfers to be combined into a larger transfer
1381 before bursting over the PCI/AGP bus. This can increase performance
1382 of image write operations 2.5 times or more. Saying Y here creates a
1383 /proc/mtrr file which may be used to manipulate your processor's
1384 MTRRs. Typically the X server should use this.
1386 This code has a reasonably generic interface so that similar
1387 control registers on other processors can be easily supported
1390 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1391 Registers (ARRs) which provide a similar functionality to MTRRs. For
1392 these, the ARRs are used to emulate the MTRRs.
1393 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1394 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1395 write-combining. All of these processors are supported by this code
1396 and it makes sense to say Y here if you have one of them.
1398 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1399 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1400 can lead to all sorts of problems, so it's good to say Y here.
1402 You can safely say Y even if your machine doesn't have MTRRs, you'll
1403 just add about 9 KB to your kernel.
1405 See <file:Documentation/x86/mtrr.txt> for more information.
1407 config MTRR_SANITIZER
1409 prompt "MTRR cleanup support"
1412 Convert MTRR layout from continuous to discrete, so X drivers can
1413 add writeback entries.
1415 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1416 The largest mtrr entry size for a continuous block can be set with
1421 config MTRR_SANITIZER_ENABLE_DEFAULT
1422 int "MTRR cleanup enable value (0-1)"
1425 depends on MTRR_SANITIZER
1427 Enable mtrr cleanup default value
1429 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1430 int "MTRR cleanup spare reg num (0-7)"
1433 depends on MTRR_SANITIZER
1435 mtrr cleanup spare entries default, it can be changed via
1436 mtrr_spare_reg_nr=N on the kernel command line.
1441 prompt "x86 PAT support" if EMBEDDED
1444 Use PAT attributes to setup page level cache control.
1446 PATs are the modern equivalents of MTRRs and are much more
1447 flexible than MTRRs.
1449 Say N here if you see bootup problems (boot crash, boot hang,
1450 spontaneous reboots) or a non-working video driver.
1454 config ARCH_USES_PG_UNCACHED
1459 bool "EFI runtime service support"
1462 This enables the kernel to use EFI runtime services that are
1463 available (such as the EFI variable services).
1465 This option is only useful on systems that have EFI firmware.
1466 In addition, you should use the latest ELILO loader available
1467 at <http://elilo.sourceforge.net> in order to take advantage
1468 of EFI runtime services. However, even with this option, the
1469 resultant kernel should continue to boot on existing non-EFI
1474 prompt "Enable seccomp to safely compute untrusted bytecode"
1476 This kernel feature is useful for number crunching applications
1477 that may need to compute untrusted bytecode during their
1478 execution. By using pipes or other transports made available to
1479 the process as file descriptors supporting the read/write
1480 syscalls, it's possible to isolate those applications in
1481 their own address space using seccomp. Once seccomp is
1482 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1483 and the task is only allowed to execute a few safe syscalls
1484 defined by each seccomp mode.
1486 If unsure, say Y. Only embedded should say N here.
1488 config CC_STACKPROTECTOR
1489 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1491 This option turns on the -fstack-protector GCC feature. This
1492 feature puts, at the beginning of functions, a canary value on
1493 the stack just before the return address, and validates
1494 the value just before actually returning. Stack based buffer
1495 overflows (that need to overwrite this return address) now also
1496 overwrite the canary, which gets detected and the attack is then
1497 neutralized via a kernel panic.
1499 This feature requires gcc version 4.2 or above, or a distribution
1500 gcc with the feature backported. Older versions are automatically
1501 detected and for those versions, this configuration option is
1502 ignored. (and a warning is printed during bootup)
1504 source kernel/Kconfig.hz
1507 bool "kexec system call"
1509 kexec is a system call that implements the ability to shutdown your
1510 current kernel, and to start another kernel. It is like a reboot
1511 but it is independent of the system firmware. And like a reboot
1512 you can start any kernel with it, not just Linux.
1514 The name comes from the similarity to the exec system call.
1516 It is an ongoing process to be certain the hardware in a machine
1517 is properly shutdown, so do not be surprised if this code does not
1518 initially work for you. It may help to enable device hotplugging
1519 support. As of this writing the exact hardware interface is
1520 strongly in flux, so no good recommendation can be made.
1523 bool "kernel crash dumps"
1524 depends on X86_64 || (X86_32 && HIGHMEM)
1526 Generate crash dump after being started by kexec.
1527 This should be normally only set in special crash dump kernels
1528 which are loaded in the main kernel with kexec-tools into
1529 a specially reserved region and then later executed after
1530 a crash by kdump/kexec. The crash dump kernel must be compiled
1531 to a memory address not used by the main kernel or BIOS using
1532 PHYSICAL_START, or it must be built as a relocatable image
1533 (CONFIG_RELOCATABLE=y).
1534 For more details see Documentation/kdump/kdump.txt
1537 bool "kexec jump (EXPERIMENTAL)"
1538 depends on EXPERIMENTAL
1539 depends on KEXEC && HIBERNATION
1541 Jump between original kernel and kexeced kernel and invoke
1542 code in physical address mode via KEXEC
1544 config PHYSICAL_START
1545 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1548 This gives the physical address where the kernel is loaded.
1550 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1551 bzImage will decompress itself to above physical address and
1552 run from there. Otherwise, bzImage will run from the address where
1553 it has been loaded by the boot loader and will ignore above physical
1556 In normal kdump cases one does not have to set/change this option
1557 as now bzImage can be compiled as a completely relocatable image
1558 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1559 address. This option is mainly useful for the folks who don't want
1560 to use a bzImage for capturing the crash dump and want to use a
1561 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1562 to be specifically compiled to run from a specific memory area
1563 (normally a reserved region) and this option comes handy.
1565 So if you are using bzImage for capturing the crash dump,
1566 leave the value here unchanged to 0x1000000 and set
1567 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1568 for capturing the crash dump change this value to start of
1569 the reserved region. In other words, it can be set based on
1570 the "X" value as specified in the "crashkernel=YM@XM"
1571 command line boot parameter passed to the panic-ed
1572 kernel. Please take a look at Documentation/kdump/kdump.txt
1573 for more details about crash dumps.
1575 Usage of bzImage for capturing the crash dump is recommended as
1576 one does not have to build two kernels. Same kernel can be used
1577 as production kernel and capture kernel. Above option should have
1578 gone away after relocatable bzImage support is introduced. But it
1579 is present because there are users out there who continue to use
1580 vmlinux for dump capture. This option should go away down the
1583 Don't change this unless you know what you are doing.
1586 bool "Build a relocatable kernel"
1589 This builds a kernel image that retains relocation information
1590 so it can be loaded someplace besides the default 1MB.
1591 The relocations tend to make the kernel binary about 10% larger,
1592 but are discarded at runtime.
1594 One use is for the kexec on panic case where the recovery kernel
1595 must live at a different physical address than the primary
1598 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1599 it has been loaded at and the compile time physical address
1600 (CONFIG_PHYSICAL_START) is ignored.
1602 # Relocation on x86-32 needs some additional build support
1603 config X86_NEED_RELOCS
1605 depends on X86_32 && RELOCATABLE
1607 config PHYSICAL_ALIGN
1609 prompt "Alignment value to which kernel should be aligned" if X86_32
1611 range 0x2000 0x1000000
1613 This value puts the alignment restrictions on physical address
1614 where kernel is loaded and run from. Kernel is compiled for an
1615 address which meets above alignment restriction.
1617 If bootloader loads the kernel at a non-aligned address and
1618 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1619 address aligned to above value and run from there.
1621 If bootloader loads the kernel at a non-aligned address and
1622 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1623 load address and decompress itself to the address it has been
1624 compiled for and run from there. The address for which kernel is
1625 compiled already meets above alignment restrictions. Hence the
1626 end result is that kernel runs from a physical address meeting
1627 above alignment restrictions.
1629 Don't change this unless you know what you are doing.
1632 bool "Support for hot-pluggable CPUs"
1633 depends on SMP && HOTPLUG
1635 Say Y here to allow turning CPUs off and on. CPUs can be
1636 controlled through /sys/devices/system/cpu.
1637 ( Note: power management support will enable this option
1638 automatically on SMP systems. )
1639 Say N if you want to disable CPU hotplug.
1643 prompt "Compat VDSO support"
1644 depends on X86_32 || IA32_EMULATION
1646 Map the 32-bit VDSO to the predictable old-style address too.
1648 Say N here if you are running a sufficiently recent glibc
1649 version (2.3.3 or later), to remove the high-mapped
1650 VDSO mapping and to exclusively use the randomized VDSO.
1655 bool "Built-in kernel command line"
1658 Allow for specifying boot arguments to the kernel at
1659 build time. On some systems (e.g. embedded ones), it is
1660 necessary or convenient to provide some or all of the
1661 kernel boot arguments with the kernel itself (that is,
1662 to not rely on the boot loader to provide them.)
1664 To compile command line arguments into the kernel,
1665 set this option to 'Y', then fill in the
1666 the boot arguments in CONFIG_CMDLINE.
1668 Systems with fully functional boot loaders (i.e. non-embedded)
1669 should leave this option set to 'N'.
1672 string "Built-in kernel command string"
1673 depends on CMDLINE_BOOL
1676 Enter arguments here that should be compiled into the kernel
1677 image and used at boot time. If the boot loader provides a
1678 command line at boot time, it is appended to this string to
1679 form the full kernel command line, when the system boots.
1681 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1682 change this behavior.
1684 In most cases, the command line (whether built-in or provided
1685 by the boot loader) should specify the device for the root
1688 config CMDLINE_OVERRIDE
1689 bool "Built-in command line overrides boot loader arguments"
1691 depends on CMDLINE_BOOL
1693 Set this option to 'Y' to have the kernel ignore the boot loader
1694 command line, and use ONLY the built-in command line.
1696 This is used to work around broken boot loaders. This should
1697 be set to 'N' under normal conditions.
1701 config ARCH_ENABLE_MEMORY_HOTPLUG
1703 depends on X86_64 || (X86_32 && HIGHMEM)
1705 config ARCH_ENABLE_MEMORY_HOTREMOVE
1707 depends on MEMORY_HOTPLUG
1709 config HAVE_ARCH_EARLY_PFN_TO_NID
1713 menu "Power management and ACPI options"
1715 config ARCH_HIBERNATION_HEADER
1717 depends on X86_64 && HIBERNATION
1719 source "kernel/power/Kconfig"
1721 source "drivers/acpi/Kconfig"
1723 source "drivers/sfi/Kconfig"
1728 depends on APM || APM_MODULE
1731 tristate "APM (Advanced Power Management) BIOS support"
1732 depends on X86_32 && PM_SLEEP
1734 APM is a BIOS specification for saving power using several different
1735 techniques. This is mostly useful for battery powered laptops with
1736 APM compliant BIOSes. If you say Y here, the system time will be
1737 reset after a RESUME operation, the /proc/apm device will provide
1738 battery status information, and user-space programs will receive
1739 notification of APM "events" (e.g. battery status change).
1741 If you select "Y" here, you can disable actual use of the APM
1742 BIOS by passing the "apm=off" option to the kernel at boot time.
1744 Note that the APM support is almost completely disabled for
1745 machines with more than one CPU.
1747 In order to use APM, you will need supporting software. For location
1748 and more information, read <file:Documentation/power/pm.txt> and the
1749 Battery Powered Linux mini-HOWTO, available from
1750 <http://www.tldp.org/docs.html#howto>.
1752 This driver does not spin down disk drives (see the hdparm(8)
1753 manpage ("man 8 hdparm") for that), and it doesn't turn off
1754 VESA-compliant "green" monitors.
1756 This driver does not support the TI 4000M TravelMate and the ACER
1757 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1758 desktop machines also don't have compliant BIOSes, and this driver
1759 may cause those machines to panic during the boot phase.
1761 Generally, if you don't have a battery in your machine, there isn't
1762 much point in using this driver and you should say N. If you get
1763 random kernel OOPSes or reboots that don't seem to be related to
1764 anything, try disabling/enabling this option (or disabling/enabling
1767 Some other things you should try when experiencing seemingly random,
1770 1) make sure that you have enough swap space and that it is
1772 2) pass the "no-hlt" option to the kernel
1773 3) switch on floating point emulation in the kernel and pass
1774 the "no387" option to the kernel
1775 4) pass the "floppy=nodma" option to the kernel
1776 5) pass the "mem=4M" option to the kernel (thereby disabling
1777 all but the first 4 MB of RAM)
1778 6) make sure that the CPU is not over clocked.
1779 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1780 8) disable the cache from your BIOS settings
1781 9) install a fan for the video card or exchange video RAM
1782 10) install a better fan for the CPU
1783 11) exchange RAM chips
1784 12) exchange the motherboard.
1786 To compile this driver as a module, choose M here: the
1787 module will be called apm.
1791 config APM_IGNORE_USER_SUSPEND
1792 bool "Ignore USER SUSPEND"
1794 This option will ignore USER SUSPEND requests. On machines with a
1795 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1796 series notebooks, it is necessary to say Y because of a BIOS bug.
1798 config APM_DO_ENABLE
1799 bool "Enable PM at boot time"
1801 Enable APM features at boot time. From page 36 of the APM BIOS
1802 specification: "When disabled, the APM BIOS does not automatically
1803 power manage devices, enter the Standby State, enter the Suspend
1804 State, or take power saving steps in response to CPU Idle calls."
1805 This driver will make CPU Idle calls when Linux is idle (unless this
1806 feature is turned off -- see "Do CPU IDLE calls", below). This
1807 should always save battery power, but more complicated APM features
1808 will be dependent on your BIOS implementation. You may need to turn
1809 this option off if your computer hangs at boot time when using APM
1810 support, or if it beeps continuously instead of suspending. Turn
1811 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1812 T400CDT. This is off by default since most machines do fine without
1816 bool "Make CPU Idle calls when idle"
1818 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1819 On some machines, this can activate improved power savings, such as
1820 a slowed CPU clock rate, when the machine is idle. These idle calls
1821 are made after the idle loop has run for some length of time (e.g.,
1822 333 mS). On some machines, this will cause a hang at boot time or
1823 whenever the CPU becomes idle. (On machines with more than one CPU,
1824 this option does nothing.)
1826 config APM_DISPLAY_BLANK
1827 bool "Enable console blanking using APM"
1829 Enable console blanking using the APM. Some laptops can use this to
1830 turn off the LCD backlight when the screen blanker of the Linux
1831 virtual console blanks the screen. Note that this is only used by
1832 the virtual console screen blanker, and won't turn off the backlight
1833 when using the X Window system. This also doesn't have anything to
1834 do with your VESA-compliant power-saving monitor. Further, this
1835 option doesn't work for all laptops -- it might not turn off your
1836 backlight at all, or it might print a lot of errors to the console,
1837 especially if you are using gpm.
1839 config APM_ALLOW_INTS
1840 bool "Allow interrupts during APM BIOS calls"
1842 Normally we disable external interrupts while we are making calls to
1843 the APM BIOS as a measure to lessen the effects of a badly behaving
1844 BIOS implementation. The BIOS should reenable interrupts if it
1845 needs to. Unfortunately, some BIOSes do not -- especially those in
1846 many of the newer IBM Thinkpads. If you experience hangs when you
1847 suspend, try setting this to Y. Otherwise, say N.
1851 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1853 source "drivers/cpuidle/Kconfig"
1855 source "drivers/idle/Kconfig"
1860 menu "Bus options (PCI etc.)"
1865 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1867 Find out whether you have a PCI motherboard. PCI is the name of a
1868 bus system, i.e. the way the CPU talks to the other stuff inside
1869 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1870 VESA. If you have PCI, say Y, otherwise N.
1873 prompt "PCI access mode"
1874 depends on X86_32 && PCI
1877 On PCI systems, the BIOS can be used to detect the PCI devices and
1878 determine their configuration. However, some old PCI motherboards
1879 have BIOS bugs and may crash if this is done. Also, some embedded
1880 PCI-based systems don't have any BIOS at all. Linux can also try to
1881 detect the PCI hardware directly without using the BIOS.
1883 With this option, you can specify how Linux should detect the
1884 PCI devices. If you choose "BIOS", the BIOS will be used,
1885 if you choose "Direct", the BIOS won't be used, and if you
1886 choose "MMConfig", then PCI Express MMCONFIG will be used.
1887 If you choose "Any", the kernel will try MMCONFIG, then the
1888 direct access method and falls back to the BIOS if that doesn't
1889 work. If unsure, go with the default, which is "Any".
1894 config PCI_GOMMCONFIG
1911 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1913 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1916 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1920 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
1924 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1931 bool "Support mmconfig PCI config space access"
1932 depends on X86_64 && PCI && ACPI
1935 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1936 depends on PCI_MSI && ACPI && EXPERIMENTAL
1938 DMA remapping (DMAR) devices support enables independent address
1939 translations for Direct Memory Access (DMA) from devices.
1940 These DMA remapping devices are reported via ACPI tables
1941 and include PCI device scope covered by these DMA
1944 config DMAR_DEFAULT_ON
1946 prompt "Enable DMA Remapping Devices by default"
1949 Selecting this option will enable a DMAR device at boot time if
1950 one is found. If this option is not selected, DMAR support can
1951 be enabled by passing intel_iommu=on to the kernel. It is
1952 recommended you say N here while the DMAR code remains
1955 config DMAR_BROKEN_GFX_WA
1957 prompt "Workaround broken graphics drivers (going away soon)"
1958 depends on DMAR && BROKEN
1960 Current Graphics drivers tend to use physical address
1961 for DMA and avoid using DMA APIs. Setting this config
1962 option permits the IOMMU driver to set a unity map for
1963 all the OS-visible memory. Hence the driver can continue
1964 to use physical addresses for DMA, at least until this
1965 option is removed in the 2.6.32 kernel.
1967 config DMAR_FLOPPY_WA
1971 Floppy disk drivers are known to bypass DMA API calls
1972 thereby failing to work when IOMMU is enabled. This
1973 workaround will setup a 1:1 mapping for the first
1974 16MiB to make floppy (an ISA device) work.
1977 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1978 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1980 Supports Interrupt remapping for IO-APIC and MSI devices.
1981 To use x2apic mode in the CPU's which support x2APIC enhancements or
1982 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1984 source "drivers/pci/pcie/Kconfig"
1986 source "drivers/pci/Kconfig"
1988 # x86_64 have no ISA slots, but do have ISA-style DMA.
1997 Find out whether you have ISA slots on your motherboard. ISA is the
1998 name of a bus system, i.e. the way the CPU talks to the other stuff
1999 inside your box. Other bus systems are PCI, EISA, MicroChannel
2000 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2001 newer boards don't support it. If you have ISA, say Y, otherwise N.
2007 The Extended Industry Standard Architecture (EISA) bus was
2008 developed as an open alternative to the IBM MicroChannel bus.
2010 The EISA bus provided some of the features of the IBM MicroChannel
2011 bus while maintaining backward compatibility with cards made for
2012 the older ISA bus. The EISA bus saw limited use between 1988 and
2013 1995 when it was made obsolete by the PCI bus.
2015 Say Y here if you are building a kernel for an EISA-based machine.
2019 source "drivers/eisa/Kconfig"
2024 MicroChannel Architecture is found in some IBM PS/2 machines and
2025 laptops. It is a bus system similar to PCI or ISA. See
2026 <file:Documentation/mca.txt> (and especially the web page given
2027 there) before attempting to build an MCA bus kernel.
2029 source "drivers/mca/Kconfig"
2032 tristate "NatSemi SCx200 support"
2034 This provides basic support for National Semiconductor's
2035 (now AMD's) Geode processors. The driver probes for the
2036 PCI-IDs of several on-chip devices, so its a good dependency
2037 for other scx200_* drivers.
2039 If compiled as a module, the driver is named scx200.
2041 config SCx200HR_TIMER
2042 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2043 depends on SCx200 && GENERIC_TIME
2046 This driver provides a clocksource built upon the on-chip
2047 27MHz high-resolution timer. Its also a workaround for
2048 NSC Geode SC-1100's buggy TSC, which loses time when the
2049 processor goes idle (as is done by the scheduler). The
2050 other workaround is idle=poll boot option.
2053 bool "One Laptop Per Child support"
2057 Add support for detecting the unique features of the OLPC
2064 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
2066 source "drivers/pcmcia/Kconfig"
2068 source "drivers/pci/hotplug/Kconfig"
2073 menu "Executable file formats / Emulations"
2075 source "fs/Kconfig.binfmt"
2077 config IA32_EMULATION
2078 bool "IA32 Emulation"
2080 select COMPAT_BINFMT_ELF
2082 Include code to run 32-bit programs under a 64-bit kernel. You should
2083 likely turn this on, unless you're 100% sure that you don't have any
2084 32-bit programs left.
2087 tristate "IA32 a.out support"
2088 depends on IA32_EMULATION
2090 Support old a.out binaries in the 32bit emulation.
2094 depends on IA32_EMULATION
2096 config COMPAT_FOR_U64_ALIGNMENT
2100 config SYSVIPC_COMPAT
2102 depends on COMPAT && SYSVIPC
2107 config HAVE_ATOMIC_IOMAP
2111 source "net/Kconfig"
2113 source "drivers/Kconfig"
2115 source "drivers/firmware/Kconfig"
2119 source "arch/x86/Kconfig.debug"
2121 source "security/Kconfig"
2123 source "crypto/Kconfig"
2125 source "arch/x86/kvm/Kconfig"
2127 source "lib/Kconfig"