3 bool "64-bit kernel" if ARCH = "x86"
4 default ARCH = "x86_64"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
19 select HAVE_AOUT if X86_32
20 select HAVE_UNSTABLE_SCHED_CLOCK
23 select HAVE_PERF_EVENTS
25 select HAVE_IOREMAP_PROT
28 select ARCH_WANT_OPTIONAL_GPIOLIB
29 select ARCH_WANT_FRAME_POINTERS
31 select HAVE_KRETPROBES
33 select HAVE_FTRACE_MCOUNT_RECORD
34 select HAVE_C_RECORDMCOUNT
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_REGS_AND_STACK_ACCESS_API
49 select HAVE_DMA_API_DEBUG
50 select HAVE_KERNEL_GZIP
51 select HAVE_KERNEL_BZIP2
52 select HAVE_KERNEL_LZMA
54 select HAVE_KERNEL_LZO
55 select HAVE_HW_BREAKPOINT
56 select HAVE_MIXED_BREAKPOINTS_REGS
58 select HAVE_PERF_EVENTS_NMI
60 select HAVE_ARCH_KMEMCHECK
61 select HAVE_USER_RETURN_NOTIFIER
62 select HAVE_ARCH_JUMP_LABEL
63 select HAVE_TEXT_POKE_SMP
64 select HAVE_GENERIC_HARDIRQS
65 select HAVE_SPARSE_IRQ
66 select GENERIC_FIND_FIRST_BIT
67 select GENERIC_IRQ_PROBE
68 select GENERIC_PENDING_IRQ if SMP
69 select GENERIC_IRQ_SHOW
70 select IRQ_FORCED_THREADING
71 select USE_GENERIC_SMP_HELPERS if SMP
72 select HAVE_BPF_JIT if (X86_64 && NET)
74 config INSTRUCTION_DECODER
75 def_bool (KPROBES || PERF_EVENTS)
79 default "elf32-i386" if X86_32
80 default "elf64-x86-64" if X86_64
84 default "arch/x86/configs/i386_defconfig" if X86_32
85 default "arch/x86/configs/x86_64_defconfig" if X86_64
87 config GENERIC_CMOS_UPDATE
90 config CLOCKSOURCE_WATCHDOG
93 config GENERIC_CLOCKEVENTS
96 config GENERIC_CLOCKEVENTS_BROADCAST
98 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
100 config LOCKDEP_SUPPORT
103 config STACKTRACE_SUPPORT
106 config HAVE_LATENCYTOP_SUPPORT
113 bool "DMA memory allocation support" if EXPERT
116 DMA memory allocation support allows devices with less than 32-bit
117 addressing to allocate within the first 16MB of address space.
118 Disable if no such devices will be used.
125 config NEED_DMA_MAP_STATE
126 def_bool (X86_64 || DMAR || DMA_API_DEBUG)
128 config NEED_SG_DMA_LENGTH
131 config GENERIC_ISA_DMA
140 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
142 config GENERIC_BUG_RELATIVE_POINTERS
145 config GENERIC_HWEIGHT
151 config ARCH_MAY_HAVE_PC_FDC
154 config RWSEM_GENERIC_SPINLOCK
157 config RWSEM_XCHGADD_ALGORITHM
160 config ARCH_HAS_CPU_IDLE_WAIT
163 config GENERIC_CALIBRATE_DELAY
166 config GENERIC_TIME_VSYSCALL
170 config ARCH_HAS_CPU_RELAX
173 config ARCH_HAS_DEFAULT_IDLE
176 config ARCH_HAS_CACHE_LINE_SIZE
179 config HAVE_SETUP_PER_CPU_AREA
182 config NEED_PER_CPU_EMBED_FIRST_CHUNK
185 config NEED_PER_CPU_PAGE_FIRST_CHUNK
188 config HAVE_CPUMASK_OF_CPU_MAP
191 config ARCH_HIBERNATION_POSSIBLE
194 config ARCH_SUSPEND_POSSIBLE
201 config ARCH_POPULATES_NODE_MAP
208 config ARCH_SUPPORTS_OPTIMIZED_INLINING
211 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
214 config HAVE_INTEL_TXT
216 depends on EXPERIMENTAL && DMAR && ACPI
220 depends on X86_32 && SMP
224 depends on X86_64 && SMP
230 config X86_32_LAZY_GS
232 depends on X86_32 && !CC_STACKPROTECTOR
234 config ARCH_HWEIGHT_CFLAGS
236 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
237 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
242 config ARCH_CPU_PROBE_RELEASE
244 depends on HOTPLUG_CPU
246 source "init/Kconfig"
247 source "kernel/Kconfig.freezer"
249 menu "Processor type and features"
251 source "kernel/time/Kconfig"
254 bool "Symmetric multi-processing support"
256 This enables support for systems with more than one CPU. If you have
257 a system with only one CPU, like most personal computers, say N. If
258 you have a system with more than one CPU, say Y.
260 If you say N here, the kernel will run on single and multiprocessor
261 machines, but will use only one CPU of a multiprocessor machine. If
262 you say Y here, the kernel will run on many, but not all,
263 singleprocessor machines. On a singleprocessor machine, the kernel
264 will run faster if you say N here.
266 Note that if you say Y here and choose architecture "586" or
267 "Pentium" under "Processor family", the kernel will not work on 486
268 architectures. Similarly, multiprocessor kernels for the "PPro"
269 architecture may not work on all Pentium based boards.
271 People using multiprocessor machines who say Y here should also say
272 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
273 Management" code will be disabled if you say Y here.
275 See also <file:Documentation/i386/IO-APIC.txt>,
276 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
277 <http://www.tldp.org/docs.html#howto>.
279 If you don't know what to do here, say N.
282 bool "Support x2apic"
283 depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
285 This enables x2apic support on CPUs that have this feature.
287 This allows 32-bit apic IDs (so it can support very large systems),
288 and accesses the local apic via MSRs not via mmio.
290 If you don't know what to do here, say N.
293 bool "Enable MPS table" if ACPI
295 depends on X86_LOCAL_APIC
297 For old smp systems that do not have proper acpi support. Newer systems
298 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
301 bool "Support for big SMP systems with more than 8 CPUs"
302 depends on X86_32 && SMP
304 This option is needed for the systems that have more than 8 CPUs
307 config X86_EXTENDED_PLATFORM
308 bool "Support for extended (non-PC) x86 platforms"
311 If you disable this option then the kernel will only support
312 standard PC platforms. (which covers the vast majority of
315 If you enable this option then you'll be able to select support
316 for the following (non-PC) 32 bit x86 platforms:
320 SGI 320/540 (Visual Workstation)
321 Summit/EXA (IBM x440)
322 Unisys ES7000 IA32 series
323 Moorestown MID devices
325 If you have one of these systems, or if you want to build a
326 generic distribution kernel, say Y here - otherwise say N.
330 config X86_EXTENDED_PLATFORM
331 bool "Support for extended (non-PC) x86 platforms"
334 If you disable this option then the kernel will only support
335 standard PC platforms. (which covers the vast majority of
338 If you enable this option then you'll be able to select support
339 for the following (non-PC) 64 bit x86 platforms:
343 If you have one of these systems, or if you want to build a
344 generic distribution kernel, say Y here - otherwise say N.
346 # This is an alphabetically sorted list of 64 bit extended platforms
347 # Please maintain the alphabetic order if and when there are additions
351 select PARAVIRT_GUEST
353 depends on X86_64 && PCI
354 depends on X86_EXTENDED_PLATFORM
356 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
357 supposed to run on these EM64T-based machines. Only choose this option
358 if you have one of these machines.
361 bool "SGI Ultraviolet"
363 depends on X86_EXTENDED_PLATFORM
365 depends on X86_X2APIC
367 This option is needed in order to support SGI Ultraviolet systems.
368 If you don't have one of these, you should say N here.
370 # Following is an alphabetically sorted list of 32 bit extended platforms
371 # Please maintain the alphabetic order if and when there are additions
374 bool "CE4100 TV platform"
376 depends on PCI_GODIRECT
378 depends on X86_EXTENDED_PLATFORM
379 select X86_REBOOTFIXUPS
381 select OF_EARLY_FLATTREE
383 Select for the Intel CE media processor (CE4100) SOC.
384 This option compiles in support for the CE4100 SOC for settop
385 boxes and media devices.
388 bool "Moorestown MID platform"
392 depends on X86_EXTENDED_PLATFORM
393 depends on X86_IO_APIC
398 select X86_PLATFORM_DEVICES
400 Moorestown is Intel's Low Power Intel Architecture (LPIA) based Moblin
401 Internet Device(MID) platform. Moorestown consists of two chips:
402 Lincroft (CPU core, graphics, and memory controller) and Langwell IOH.
403 Unlike standard x86 PCs, Moorestown does not have many legacy devices
404 nor standard legacy replacement devices/features. e.g. Moorestown does
405 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
408 bool "RDC R-321x SoC"
410 depends on X86_EXTENDED_PLATFORM
412 select X86_REBOOTFIXUPS
414 This option is needed for RDC R-321x system-on-chip, also known
416 If you don't have one of these chips, you should say N here.
418 config X86_32_NON_STANDARD
419 bool "Support non-standard 32-bit SMP architectures"
420 depends on X86_32 && SMP
421 depends on X86_EXTENDED_PLATFORM
423 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
424 subarchitectures. It is intended for a generic binary kernel.
425 if you select them all, kernel will probe it one by one. and will
428 # Alphabetically sorted list of Non standard 32 bit platforms
431 bool "NUMAQ (IBM/Sequent)"
432 depends on X86_32_NON_STANDARD
437 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
438 NUMA multiquad box. This changes the way that processors are
439 bootstrapped, and uses Clustered Logical APIC addressing mode instead
440 of Flat Logical. You will need a new lynxer.elf file to flash your
441 firmware with - send email to <Martin.Bligh@us.ibm.com>.
443 config X86_SUPPORTS_MEMORY_FAILURE
445 # MCE code calls memory_failure():
447 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
448 depends on !X86_NUMAQ
449 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
450 depends on X86_64 || !SPARSEMEM
451 select ARCH_SUPPORTS_MEMORY_FAILURE
454 bool "SGI 320/540 (Visual Workstation)"
455 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
456 depends on X86_32_NON_STANDARD
458 The SGI Visual Workstation series is an IA32-based workstation
459 based on SGI systems chips with some legacy PC hardware attached.
461 Say Y here to create a kernel to run on the SGI 320 or 540.
463 A kernel compiled for the Visual Workstation will run on general
464 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
467 bool "Summit/EXA (IBM x440)"
468 depends on X86_32_NON_STANDARD
470 This option is needed for IBM systems that use the Summit/EXA chipset.
471 In particular, it is needed for the x440.
474 bool "Unisys ES7000 IA32 series"
475 depends on X86_32_NON_STANDARD && X86_BIGSMP
477 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
478 supposed to run on an IA32-based Unisys ES7000 system.
481 tristate "Eurobraille/Iris poweroff module"
484 The Iris machines from EuroBraille do not have APM or ACPI support
485 to shut themselves down properly. A special I/O sequence is
486 needed to do so, which is what this module does at
489 This is only for Iris machines from EuroBraille.
493 config SCHED_OMIT_FRAME_POINTER
495 prompt "Single-depth WCHAN output"
498 Calculate simpler /proc/<PID>/wchan values. If this option
499 is disabled then wchan values will recurse back to the
500 caller function. This provides more accurate wchan values,
501 at the expense of slightly more scheduling overhead.
503 If in doubt, say "Y".
505 menuconfig PARAVIRT_GUEST
506 bool "Paravirtualized guest support"
508 Say Y here to get to see options related to running Linux under
509 various hypervisors. This option alone does not add any kernel code.
511 If you say N, all options in this submenu will be skipped and disabled.
515 source "arch/x86/xen/Kconfig"
518 bool "KVM paravirtualized clock"
520 select PARAVIRT_CLOCK
522 Turning on this option will allow you to run a paravirtualized clock
523 when running over the KVM hypervisor. Instead of relying on a PIT
524 (or probably other) emulation by the underlying device model, the host
525 provides the guest with timing infrastructure such as time of day, and
529 bool "KVM Guest support"
532 This option enables various optimizations for running under the KVM
535 source "arch/x86/lguest/Kconfig"
538 bool "Enable paravirtualization code"
540 This changes the kernel so it can modify itself when it is run
541 under a hypervisor, potentially improving performance significantly
542 over full virtualization. However, when run without a hypervisor
543 the kernel is theoretically slower and slightly larger.
545 config PARAVIRT_SPINLOCKS
546 bool "Paravirtualization layer for spinlocks"
547 depends on PARAVIRT && SMP && EXPERIMENTAL
549 Paravirtualized spinlocks allow a pvops backend to replace the
550 spinlock implementation with something virtualization-friendly
551 (for example, block the virtual CPU rather than spinning).
553 Unfortunately the downside is an up to 5% performance hit on
554 native kernels, with various workloads.
556 If you are unsure how to answer this question, answer N.
558 config PARAVIRT_CLOCK
563 config PARAVIRT_DEBUG
564 bool "paravirt-ops debugging"
565 depends on PARAVIRT && DEBUG_KERNEL
567 Enable to debug paravirt_ops internals. Specifically, BUG if
568 a paravirt_op is missing when it is called.
576 This option adds a kernel parameter 'memtest', which allows memtest
578 memtest=0, mean disabled; -- default
579 memtest=1, mean do 1 test pattern;
581 memtest=4, mean do 4 test patterns.
582 If you are unsure how to answer this question, answer N.
584 config X86_SUMMIT_NUMA
586 depends on X86_32 && NUMA && X86_32_NON_STANDARD
588 config X86_CYCLONE_TIMER
590 depends on X86_32_NON_STANDARD
592 source "arch/x86/Kconfig.cpu"
596 prompt "HPET Timer Support" if X86_32
598 Use the IA-PC HPET (High Precision Event Timer) to manage
599 time in preference to the PIT and RTC, if a HPET is
601 HPET is the next generation timer replacing legacy 8254s.
602 The HPET provides a stable time base on SMP
603 systems, unlike the TSC, but it is more expensive to access,
604 as it is off-chip. You can find the HPET spec at
605 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
607 You can safely choose Y here. However, HPET will only be
608 activated if the platform and the BIOS support this feature.
609 Otherwise the 8254 will be used for timing services.
611 Choose N to continue using the legacy 8254 timer.
613 config HPET_EMULATE_RTC
615 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
619 prompt "Langwell APB Timer Support" if X86_MRST
621 APB timer is the replacement for 8254, HPET on X86 MID platforms.
622 The APBT provides a stable time base on SMP
623 systems, unlike the TSC, but it is more expensive to access,
624 as it is off-chip. APB timers are always running regardless of CPU
625 C states, they are used as per CPU clockevent device when possible.
627 # Mark as expert because too many people got it wrong.
628 # The code disables itself when not needed.
631 bool "Enable DMI scanning" if EXPERT
633 Enabled scanning of DMI to identify machine quirks. Say Y
634 here unless you have verified that your setup is not
635 affected by entries in the DMI blacklist. Required by PNP
639 bool "GART IOMMU support" if EXPERT
642 depends on X86_64 && PCI && AMD_NB
644 Support for full DMA access of devices with 32bit memory access only
645 on systems with more than 3GB. This is usually needed for USB,
646 sound, many IDE/SATA chipsets and some other devices.
647 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
648 based hardware IOMMU and a software bounce buffer based IOMMU used
649 on Intel systems and as fallback.
650 The code is only active when needed (enough memory and limited
651 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
655 bool "IBM Calgary IOMMU support"
657 depends on X86_64 && PCI && EXPERIMENTAL
659 Support for hardware IOMMUs in IBM's xSeries x366 and x460
660 systems. Needed to run systems with more than 3GB of memory
661 properly with 32-bit PCI devices that do not support DAC
662 (Double Address Cycle). Calgary also supports bus level
663 isolation, where all DMAs pass through the IOMMU. This
664 prevents them from going anywhere except their intended
665 destination. This catches hard-to-find kernel bugs and
666 mis-behaving drivers and devices that do not use the DMA-API
667 properly to set up their DMA buffers. The IOMMU can be
668 turned off at boot time with the iommu=off parameter.
669 Normally the kernel will make the right choice by itself.
672 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
674 prompt "Should Calgary be enabled by default?"
675 depends on CALGARY_IOMMU
677 Should Calgary be enabled by default? if you choose 'y', Calgary
678 will be used (if it exists). If you choose 'n', Calgary will not be
679 used even if it exists. If you choose 'n' and would like to use
680 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
683 # need this always selected by IOMMU for the VIA workaround
687 Support for software bounce buffers used on x86-64 systems
688 which don't have a hardware IOMMU (e.g. the current generation
689 of Intel's x86-64 CPUs). Using this PCI devices which can only
690 access 32-bits of memory can be used on systems with more than
691 3 GB of memory. If unsure, say Y.
694 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
697 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
698 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
699 select CPUMASK_OFFSTACK
701 Enable maximum number of CPUS and NUMA Nodes for this architecture.
705 int "Maximum number of CPUs" if SMP && !MAXSMP
706 range 2 8 if SMP && X86_32 && !X86_BIGSMP
707 range 2 512 if SMP && !MAXSMP
709 default "4096" if MAXSMP
710 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
713 This allows you to specify the maximum number of CPUs which this
714 kernel will support. The maximum supported value is 512 and the
715 minimum value which makes sense is 2.
717 This is purely to save memory - each supported CPU adds
718 approximately eight kilobytes to the kernel image.
721 bool "SMT (Hyperthreading) scheduler support"
724 SMT scheduler support improves the CPU scheduler's decision making
725 when dealing with Intel Pentium 4 chips with HyperThreading at a
726 cost of slightly increased overhead in some places. If unsure say
731 prompt "Multi-core scheduler support"
734 Multi-core scheduler support improves the CPU scheduler's decision
735 making when dealing with multi-core CPU chips at a cost of slightly
736 increased overhead in some places. If unsure say N here.
738 config IRQ_TIME_ACCOUNTING
739 bool "Fine granularity task level IRQ time accounting"
742 Select this option to enable fine granularity task irq time
743 accounting. This is done by reading a timestamp on each
744 transitions between softirq and hardirq state, so there can be a
745 small performance impact.
747 If in doubt, say N here.
749 source "kernel/Kconfig.preempt"
752 bool "Local APIC support on uniprocessors"
753 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
755 A local APIC (Advanced Programmable Interrupt Controller) is an
756 integrated interrupt controller in the CPU. If you have a single-CPU
757 system which has a processor with a local APIC, you can say Y here to
758 enable and use it. If you say Y here even though your machine doesn't
759 have a local APIC, then the kernel will still run with no slowdown at
760 all. The local APIC supports CPU-generated self-interrupts (timer,
761 performance counters), and the NMI watchdog which detects hard
765 bool "IO-APIC support on uniprocessors"
766 depends on X86_UP_APIC
768 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
769 SMP-capable replacement for PC-style interrupt controllers. Most
770 SMP systems and many recent uniprocessor systems have one.
772 If you have a single-CPU system with an IO-APIC, you can say Y here
773 to use it. If you say Y here even though your machine doesn't have
774 an IO-APIC, then the kernel will still run with no slowdown at all.
776 config X86_LOCAL_APIC
778 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
782 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
784 config X86_VISWS_APIC
786 depends on X86_32 && X86_VISWS
788 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
789 bool "Reroute for broken boot IRQs"
790 depends on X86_IO_APIC
792 This option enables a workaround that fixes a source of
793 spurious interrupts. This is recommended when threaded
794 interrupt handling is used on systems where the generation of
795 superfluous "boot interrupts" cannot be disabled.
797 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
798 entry in the chipset's IO-APIC is masked (as, e.g. the RT
799 kernel does during interrupt handling). On chipsets where this
800 boot IRQ generation cannot be disabled, this workaround keeps
801 the original IRQ line masked so that only the equivalent "boot
802 IRQ" is delivered to the CPUs. The workaround also tells the
803 kernel to set up the IRQ handler on the boot IRQ line. In this
804 way only one interrupt is delivered to the kernel. Otherwise
805 the spurious second interrupt may cause the kernel to bring
806 down (vital) interrupt lines.
808 Only affects "broken" chipsets. Interrupt sharing may be
809 increased on these systems.
812 bool "Machine Check / overheating reporting"
814 Machine Check support allows the processor to notify the
815 kernel if it detects a problem (e.g. overheating, data corruption).
816 The action the kernel takes depends on the severity of the problem,
817 ranging from warning messages to halting the machine.
821 prompt "Intel MCE features"
822 depends on X86_MCE && X86_LOCAL_APIC
824 Additional support for intel specific MCE features such as
829 prompt "AMD MCE features"
830 depends on X86_MCE && X86_LOCAL_APIC
832 Additional support for AMD specific MCE features such as
833 the DRAM Error Threshold.
835 config X86_ANCIENT_MCE
836 bool "Support for old Pentium 5 / WinChip machine checks"
837 depends on X86_32 && X86_MCE
839 Include support for machine check handling on old Pentium 5 or WinChip
840 systems. These typically need to be enabled explicitely on the command
843 config X86_MCE_THRESHOLD
844 depends on X86_MCE_AMD || X86_MCE_INTEL
847 config X86_MCE_INJECT
849 tristate "Machine check injector support"
851 Provide support for injecting machine checks for testing purposes.
852 If you don't know what a machine check is and you don't do kernel
853 QA it is safe to say n.
855 config X86_THERMAL_VECTOR
857 depends on X86_MCE_INTEL
860 bool "Enable VM86 support" if EXPERT
864 This option is required by programs like DOSEMU to run 16-bit legacy
865 code on X86 processors. It also may be needed by software like
866 XFree86 to initialize some video cards via BIOS. Disabling this
867 option saves about 6k.
870 tristate "Toshiba Laptop support"
873 This adds a driver to safely access the System Management Mode of
874 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
875 not work on models with a Phoenix BIOS. The System Management Mode
876 is used to set the BIOS and power saving options on Toshiba portables.
878 For information on utilities to make use of this driver see the
879 Toshiba Linux utilities web site at:
880 <http://www.buzzard.org.uk/toshiba/>.
882 Say Y if you intend to run this kernel on a Toshiba portable.
886 tristate "Dell laptop support"
889 This adds a driver to safely access the System Management Mode
890 of the CPU on the Dell Inspiron 8000. The System Management Mode
891 is used to read cpu temperature and cooling fan status and to
892 control the fans on the I8K portables.
894 This driver has been tested only on the Inspiron 8000 but it may
895 also work with other Dell laptops. You can force loading on other
896 models by passing the parameter `force=1' to the module. Use at
899 For information on utilities to make use of this driver see the
900 I8K Linux utilities web site at:
901 <http://people.debian.org/~dz/i8k/>
903 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
906 config X86_REBOOTFIXUPS
907 bool "Enable X86 board specific fixups for reboot"
910 This enables chipset and/or board specific fixups to be done
911 in order to get reboot to work correctly. This is only needed on
912 some combinations of hardware and BIOS. The symptom, for which
913 this config is intended, is when reboot ends with a stalled/hung
916 Currently, the only fixup is for the Geode machines using
917 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
919 Say Y if you want to enable the fixup. Currently, it's safe to
920 enable this option even if you don't need it.
924 tristate "/dev/cpu/microcode - microcode support"
927 If you say Y here, you will be able to update the microcode on
928 certain Intel and AMD processors. The Intel support is for the
929 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
930 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
931 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
932 You will obviously need the actual microcode binary data itself
933 which is not shipped with the Linux kernel.
935 This option selects the general module only, you need to select
936 at least one vendor specific module as well.
938 To compile this driver as a module, choose M here: the
939 module will be called microcode.
941 config MICROCODE_INTEL
942 bool "Intel microcode patch loading support"
947 This options enables microcode patch loading support for Intel
950 For latest news and information on obtaining all the required
951 Intel ingredients for this driver, check:
952 <http://www.urbanmyth.org/microcode/>.
955 bool "AMD microcode patch loading support"
959 If you select this option, microcode patch loading support for AMD
960 processors will be enabled.
962 config MICROCODE_OLD_INTERFACE
967 tristate "/dev/cpu/*/msr - Model-specific register support"
969 This device gives privileged processes access to the x86
970 Model-Specific Registers (MSRs). It is a character device with
971 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
972 MSR accesses are directed to a specific CPU on multi-processor
976 tristate "/dev/cpu/*/cpuid - CPU information support"
978 This device gives processes access to the x86 CPUID instruction to
979 be executed on a specific processor. It is a character device
980 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
984 prompt "High Memory Support"
985 default HIGHMEM64G if X86_NUMAQ
991 depends on !X86_NUMAQ
993 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
994 However, the address space of 32-bit x86 processors is only 4
995 Gigabytes large. That means that, if you have a large amount of
996 physical memory, not all of it can be "permanently mapped" by the
997 kernel. The physical memory that's not permanently mapped is called
1000 If you are compiling a kernel which will never run on a machine with
1001 more than 1 Gigabyte total physical RAM, answer "off" here (default
1002 choice and suitable for most users). This will result in a "3GB/1GB"
1003 split: 3GB are mapped so that each process sees a 3GB virtual memory
1004 space and the remaining part of the 4GB virtual memory space is used
1005 by the kernel to permanently map as much physical memory as
1008 If the machine has between 1 and 4 Gigabytes physical RAM, then
1011 If more than 4 Gigabytes is used then answer "64GB" here. This
1012 selection turns Intel PAE (Physical Address Extension) mode on.
1013 PAE implements 3-level paging on IA32 processors. PAE is fully
1014 supported by Linux, PAE mode is implemented on all recent Intel
1015 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1016 then the kernel will not boot on CPUs that don't support PAE!
1018 The actual amount of total physical memory will either be
1019 auto detected or can be forced by using a kernel command line option
1020 such as "mem=256M". (Try "man bootparam" or see the documentation of
1021 your boot loader (lilo or loadlin) about how to pass options to the
1022 kernel at boot time.)
1024 If unsure, say "off".
1028 depends on !X86_NUMAQ
1030 Select this if you have a 32-bit processor and between 1 and 4
1031 gigabytes of physical RAM.
1035 depends on !M386 && !M486
1038 Select this if you have a 32-bit processor and more than 4
1039 gigabytes of physical RAM.
1044 depends on EXPERIMENTAL
1045 prompt "Memory split" if EXPERT
1049 Select the desired split between kernel and user memory.
1051 If the address range available to the kernel is less than the
1052 physical memory installed, the remaining memory will be available
1053 as "high memory". Accessing high memory is a little more costly
1054 than low memory, as it needs to be mapped into the kernel first.
1055 Note that increasing the kernel address space limits the range
1056 available to user programs, making the address space there
1057 tighter. Selecting anything other than the default 3G/1G split
1058 will also likely make your kernel incompatible with binary-only
1061 If you are not absolutely sure what you are doing, leave this
1065 bool "3G/1G user/kernel split"
1066 config VMSPLIT_3G_OPT
1068 bool "3G/1G user/kernel split (for full 1G low memory)"
1070 bool "2G/2G user/kernel split"
1071 config VMSPLIT_2G_OPT
1073 bool "2G/2G user/kernel split (for full 2G low memory)"
1075 bool "1G/3G user/kernel split"
1080 default 0xB0000000 if VMSPLIT_3G_OPT
1081 default 0x80000000 if VMSPLIT_2G
1082 default 0x78000000 if VMSPLIT_2G_OPT
1083 default 0x40000000 if VMSPLIT_1G
1089 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1092 bool "PAE (Physical Address Extension) Support"
1093 depends on X86_32 && !HIGHMEM4G
1095 PAE is required for NX support, and furthermore enables
1096 larger swapspace support for non-overcommit purposes. It
1097 has the cost of more pagetable lookup overhead, and also
1098 consumes more pagetable space per process.
1100 config ARCH_PHYS_ADDR_T_64BIT
1101 def_bool X86_64 || X86_PAE
1103 config ARCH_DMA_ADDR_T_64BIT
1104 def_bool X86_64 || HIGHMEM64G
1106 config DIRECT_GBPAGES
1107 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1111 Allow the kernel linear mapping to use 1GB pages on CPUs that
1112 support it. This can improve the kernel's performance a tiny bit by
1113 reducing TLB pressure. If in doubt, say "Y".
1115 # Common NUMA Features
1117 bool "Numa Memory Allocation and Scheduler Support"
1119 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1120 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1122 Enable NUMA (Non Uniform Memory Access) support.
1124 The kernel will try to allocate memory used by a CPU on the
1125 local memory controller of the CPU and add some more
1126 NUMA awareness to the kernel.
1128 For 64-bit this is recommended if the system is Intel Core i7
1129 (or later), AMD Opteron, or EM64T NUMA.
1131 For 32-bit this is only needed on (rare) 32-bit-only platforms
1132 that support NUMA topologies, such as NUMAQ / Summit, or if you
1133 boot a 32-bit kernel on a 64-bit NUMA platform.
1135 Otherwise, you should say N.
1137 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1138 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1142 prompt "Old style AMD Opteron NUMA detection"
1143 depends on NUMA && PCI
1145 Enable AMD NUMA node topology detection. You should say Y here if
1146 you have a multi processor AMD system. This uses an old method to
1147 read the NUMA configuration directly from the builtin Northbridge
1148 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1149 which also takes priority if both are compiled in.
1151 config X86_64_ACPI_NUMA
1153 prompt "ACPI NUMA detection"
1154 depends on X86_64 && NUMA && ACPI && PCI
1157 Enable ACPI SRAT based node topology detection.
1159 # Some NUMA nodes have memory ranges that span
1160 # other nodes. Even though a pfn is valid and
1161 # between a node's start and end pfns, it may not
1162 # reside on that node. See memmap_init_zone()
1164 config NODES_SPAN_OTHER_NODES
1166 depends on X86_64_ACPI_NUMA
1169 bool "NUMA emulation"
1172 Enable NUMA emulation. A flat machine will be split
1173 into virtual nodes when booted with "numa=fake=N", where N is the
1174 number of nodes. This is only useful for debugging.
1177 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1179 default "10" if MAXSMP
1180 default "6" if X86_64
1181 default "4" if X86_NUMAQ
1183 depends on NEED_MULTIPLE_NODES
1185 Specify the maximum number of NUMA Nodes available on the target
1186 system. Increases memory reserved to accommodate various tables.
1188 config HAVE_ARCH_BOOTMEM
1190 depends on X86_32 && NUMA
1192 config HAVE_ARCH_ALLOC_REMAP
1194 depends on X86_32 && NUMA
1196 config ARCH_HAVE_MEMORY_PRESENT
1198 depends on X86_32 && DISCONTIGMEM
1200 config NEED_NODE_MEMMAP_SIZE
1202 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1204 config ARCH_FLATMEM_ENABLE
1206 depends on X86_32 && !NUMA
1208 config ARCH_DISCONTIGMEM_ENABLE
1210 depends on NUMA && X86_32
1212 config ARCH_DISCONTIGMEM_DEFAULT
1214 depends on NUMA && X86_32
1216 config ARCH_SPARSEMEM_ENABLE
1218 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1219 select SPARSEMEM_STATIC if X86_32
1220 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1222 config ARCH_SPARSEMEM_DEFAULT
1226 config ARCH_SELECT_MEMORY_MODEL
1228 depends on ARCH_SPARSEMEM_ENABLE
1230 config ARCH_MEMORY_PROBE
1232 depends on MEMORY_HOTPLUG
1234 config ARCH_PROC_KCORE_TEXT
1236 depends on X86_64 && PROC_KCORE
1238 config ILLEGAL_POINTER_VALUE
1241 default 0xdead000000000000 if X86_64
1246 bool "Allocate 3rd-level pagetables from highmem"
1249 The VM uses one page table entry for each page of physical memory.
1250 For systems with a lot of RAM, this can be wasteful of precious
1251 low memory. Setting this option will put user-space page table
1252 entries in high memory.
1254 config X86_CHECK_BIOS_CORRUPTION
1255 bool "Check for low memory corruption"
1257 Periodically check for memory corruption in low memory, which
1258 is suspected to be caused by BIOS. Even when enabled in the
1259 configuration, it is disabled at runtime. Enable it by
1260 setting "memory_corruption_check=1" on the kernel command
1261 line. By default it scans the low 64k of memory every 60
1262 seconds; see the memory_corruption_check_size and
1263 memory_corruption_check_period parameters in
1264 Documentation/kernel-parameters.txt to adjust this.
1266 When enabled with the default parameters, this option has
1267 almost no overhead, as it reserves a relatively small amount
1268 of memory and scans it infrequently. It both detects corruption
1269 and prevents it from affecting the running system.
1271 It is, however, intended as a diagnostic tool; if repeatable
1272 BIOS-originated corruption always affects the same memory,
1273 you can use memmap= to prevent the kernel from using that
1276 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1277 bool "Set the default setting of memory_corruption_check"
1278 depends on X86_CHECK_BIOS_CORRUPTION
1281 Set whether the default state of memory_corruption_check is
1284 config X86_RESERVE_LOW
1285 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1289 Specify the amount of low memory to reserve for the BIOS.
1291 The first page contains BIOS data structures that the kernel
1292 must not use, so that page must always be reserved.
1294 By default we reserve the first 64K of physical RAM, as a
1295 number of BIOSes are known to corrupt that memory range
1296 during events such as suspend/resume or monitor cable
1297 insertion, so it must not be used by the kernel.
1299 You can set this to 4 if you are absolutely sure that you
1300 trust the BIOS to get all its memory reservations and usages
1301 right. If you know your BIOS have problems beyond the
1302 default 64K area, you can set this to 640 to avoid using the
1303 entire low memory range.
1305 If you have doubts about the BIOS (e.g. suspend/resume does
1306 not work or there's kernel crashes after certain hardware
1307 hotplug events) then you might want to enable
1308 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1309 typical corruption patterns.
1311 Leave this to the default value of 64 if you are unsure.
1313 config MATH_EMULATION
1315 prompt "Math emulation" if X86_32
1317 Linux can emulate a math coprocessor (used for floating point
1318 operations) if you don't have one. 486DX and Pentium processors have
1319 a math coprocessor built in, 486SX and 386 do not, unless you added
1320 a 487DX or 387, respectively. (The messages during boot time can
1321 give you some hints here ["man dmesg"].) Everyone needs either a
1322 coprocessor or this emulation.
1324 If you don't have a math coprocessor, you need to say Y here; if you
1325 say Y here even though you have a coprocessor, the coprocessor will
1326 be used nevertheless. (This behavior can be changed with the kernel
1327 command line option "no387", which comes handy if your coprocessor
1328 is broken. Try "man bootparam" or see the documentation of your boot
1329 loader (lilo or loadlin) about how to pass options to the kernel at
1330 boot time.) This means that it is a good idea to say Y here if you
1331 intend to use this kernel on different machines.
1333 More information about the internals of the Linux math coprocessor
1334 emulation can be found in <file:arch/x86/math-emu/README>.
1336 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1337 kernel, it won't hurt.
1341 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1343 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1344 the Memory Type Range Registers (MTRRs) may be used to control
1345 processor access to memory ranges. This is most useful if you have
1346 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1347 allows bus write transfers to be combined into a larger transfer
1348 before bursting over the PCI/AGP bus. This can increase performance
1349 of image write operations 2.5 times or more. Saying Y here creates a
1350 /proc/mtrr file which may be used to manipulate your processor's
1351 MTRRs. Typically the X server should use this.
1353 This code has a reasonably generic interface so that similar
1354 control registers on other processors can be easily supported
1357 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1358 Registers (ARRs) which provide a similar functionality to MTRRs. For
1359 these, the ARRs are used to emulate the MTRRs.
1360 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1361 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1362 write-combining. All of these processors are supported by this code
1363 and it makes sense to say Y here if you have one of them.
1365 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1366 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1367 can lead to all sorts of problems, so it's good to say Y here.
1369 You can safely say Y even if your machine doesn't have MTRRs, you'll
1370 just add about 9 KB to your kernel.
1372 See <file:Documentation/x86/mtrr.txt> for more information.
1374 config MTRR_SANITIZER
1376 prompt "MTRR cleanup support"
1379 Convert MTRR layout from continuous to discrete, so X drivers can
1380 add writeback entries.
1382 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1383 The largest mtrr entry size for a continuous block can be set with
1388 config MTRR_SANITIZER_ENABLE_DEFAULT
1389 int "MTRR cleanup enable value (0-1)"
1392 depends on MTRR_SANITIZER
1394 Enable mtrr cleanup default value
1396 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1397 int "MTRR cleanup spare reg num (0-7)"
1400 depends on MTRR_SANITIZER
1402 mtrr cleanup spare entries default, it can be changed via
1403 mtrr_spare_reg_nr=N on the kernel command line.
1407 prompt "x86 PAT support" if EXPERT
1410 Use PAT attributes to setup page level cache control.
1412 PATs are the modern equivalents of MTRRs and are much more
1413 flexible than MTRRs.
1415 Say N here if you see bootup problems (boot crash, boot hang,
1416 spontaneous reboots) or a non-working video driver.
1420 config ARCH_USES_PG_UNCACHED
1425 bool "EFI runtime service support"
1428 This enables the kernel to use EFI runtime services that are
1429 available (such as the EFI variable services).
1431 This option is only useful on systems that have EFI firmware.
1432 In addition, you should use the latest ELILO loader available
1433 at <http://elilo.sourceforge.net> in order to take advantage
1434 of EFI runtime services. However, even with this option, the
1435 resultant kernel should continue to boot on existing non-EFI
1440 prompt "Enable seccomp to safely compute untrusted bytecode"
1442 This kernel feature is useful for number crunching applications
1443 that may need to compute untrusted bytecode during their
1444 execution. By using pipes or other transports made available to
1445 the process as file descriptors supporting the read/write
1446 syscalls, it's possible to isolate those applications in
1447 their own address space using seccomp. Once seccomp is
1448 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1449 and the task is only allowed to execute a few safe syscalls
1450 defined by each seccomp mode.
1452 If unsure, say Y. Only embedded should say N here.
1454 config CC_STACKPROTECTOR
1455 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1457 This option turns on the -fstack-protector GCC feature. This
1458 feature puts, at the beginning of functions, a canary value on
1459 the stack just before the return address, and validates
1460 the value just before actually returning. Stack based buffer
1461 overflows (that need to overwrite this return address) now also
1462 overwrite the canary, which gets detected and the attack is then
1463 neutralized via a kernel panic.
1465 This feature requires gcc version 4.2 or above, or a distribution
1466 gcc with the feature backported. Older versions are automatically
1467 detected and for those versions, this configuration option is
1468 ignored. (and a warning is printed during bootup)
1470 source kernel/Kconfig.hz
1473 bool "kexec system call"
1475 kexec is a system call that implements the ability to shutdown your
1476 current kernel, and to start another kernel. It is like a reboot
1477 but it is independent of the system firmware. And like a reboot
1478 you can start any kernel with it, not just Linux.
1480 The name comes from the similarity to the exec system call.
1482 It is an ongoing process to be certain the hardware in a machine
1483 is properly shutdown, so do not be surprised if this code does not
1484 initially work for you. It may help to enable device hotplugging
1485 support. As of this writing the exact hardware interface is
1486 strongly in flux, so no good recommendation can be made.
1489 bool "kernel crash dumps"
1490 depends on X86_64 || (X86_32 && HIGHMEM)
1492 Generate crash dump after being started by kexec.
1493 This should be normally only set in special crash dump kernels
1494 which are loaded in the main kernel with kexec-tools into
1495 a specially reserved region and then later executed after
1496 a crash by kdump/kexec. The crash dump kernel must be compiled
1497 to a memory address not used by the main kernel or BIOS using
1498 PHYSICAL_START, or it must be built as a relocatable image
1499 (CONFIG_RELOCATABLE=y).
1500 For more details see Documentation/kdump/kdump.txt
1503 bool "kexec jump (EXPERIMENTAL)"
1504 depends on EXPERIMENTAL
1505 depends on KEXEC && HIBERNATION
1507 Jump between original kernel and kexeced kernel and invoke
1508 code in physical address mode via KEXEC
1510 config PHYSICAL_START
1511 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1514 This gives the physical address where the kernel is loaded.
1516 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1517 bzImage will decompress itself to above physical address and
1518 run from there. Otherwise, bzImage will run from the address where
1519 it has been loaded by the boot loader and will ignore above physical
1522 In normal kdump cases one does not have to set/change this option
1523 as now bzImage can be compiled as a completely relocatable image
1524 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1525 address. This option is mainly useful for the folks who don't want
1526 to use a bzImage for capturing the crash dump and want to use a
1527 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1528 to be specifically compiled to run from a specific memory area
1529 (normally a reserved region) and this option comes handy.
1531 So if you are using bzImage for capturing the crash dump,
1532 leave the value here unchanged to 0x1000000 and set
1533 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1534 for capturing the crash dump change this value to start of
1535 the reserved region. In other words, it can be set based on
1536 the "X" value as specified in the "crashkernel=YM@XM"
1537 command line boot parameter passed to the panic-ed
1538 kernel. Please take a look at Documentation/kdump/kdump.txt
1539 for more details about crash dumps.
1541 Usage of bzImage for capturing the crash dump is recommended as
1542 one does not have to build two kernels. Same kernel can be used
1543 as production kernel and capture kernel. Above option should have
1544 gone away after relocatable bzImage support is introduced. But it
1545 is present because there are users out there who continue to use
1546 vmlinux for dump capture. This option should go away down the
1549 Don't change this unless you know what you are doing.
1552 bool "Build a relocatable kernel"
1555 This builds a kernel image that retains relocation information
1556 so it can be loaded someplace besides the default 1MB.
1557 The relocations tend to make the kernel binary about 10% larger,
1558 but are discarded at runtime.
1560 One use is for the kexec on panic case where the recovery kernel
1561 must live at a different physical address than the primary
1564 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1565 it has been loaded at and the compile time physical address
1566 (CONFIG_PHYSICAL_START) is ignored.
1568 # Relocation on x86-32 needs some additional build support
1569 config X86_NEED_RELOCS
1571 depends on X86_32 && RELOCATABLE
1573 config PHYSICAL_ALIGN
1574 hex "Alignment value to which kernel should be aligned" if X86_32
1576 range 0x2000 0x1000000
1578 This value puts the alignment restrictions on physical address
1579 where kernel is loaded and run from. Kernel is compiled for an
1580 address which meets above alignment restriction.
1582 If bootloader loads the kernel at a non-aligned address and
1583 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1584 address aligned to above value and run from there.
1586 If bootloader loads the kernel at a non-aligned address and
1587 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1588 load address and decompress itself to the address it has been
1589 compiled for and run from there. The address for which kernel is
1590 compiled already meets above alignment restrictions. Hence the
1591 end result is that kernel runs from a physical address meeting
1592 above alignment restrictions.
1594 Don't change this unless you know what you are doing.
1597 bool "Support for hot-pluggable CPUs"
1598 depends on SMP && HOTPLUG
1600 Say Y here to allow turning CPUs off and on. CPUs can be
1601 controlled through /sys/devices/system/cpu.
1602 ( Note: power management support will enable this option
1603 automatically on SMP systems. )
1604 Say N if you want to disable CPU hotplug.
1608 prompt "Compat VDSO support"
1609 depends on X86_32 || IA32_EMULATION
1611 Map the 32-bit VDSO to the predictable old-style address too.
1613 Say N here if you are running a sufficiently recent glibc
1614 version (2.3.3 or later), to remove the high-mapped
1615 VDSO mapping and to exclusively use the randomized VDSO.
1620 bool "Built-in kernel command line"
1622 Allow for specifying boot arguments to the kernel at
1623 build time. On some systems (e.g. embedded ones), it is
1624 necessary or convenient to provide some or all of the
1625 kernel boot arguments with the kernel itself (that is,
1626 to not rely on the boot loader to provide them.)
1628 To compile command line arguments into the kernel,
1629 set this option to 'Y', then fill in the
1630 the boot arguments in CONFIG_CMDLINE.
1632 Systems with fully functional boot loaders (i.e. non-embedded)
1633 should leave this option set to 'N'.
1636 string "Built-in kernel command string"
1637 depends on CMDLINE_BOOL
1640 Enter arguments here that should be compiled into the kernel
1641 image and used at boot time. If the boot loader provides a
1642 command line at boot time, it is appended to this string to
1643 form the full kernel command line, when the system boots.
1645 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1646 change this behavior.
1648 In most cases, the command line (whether built-in or provided
1649 by the boot loader) should specify the device for the root
1652 config CMDLINE_OVERRIDE
1653 bool "Built-in command line overrides boot loader arguments"
1654 depends on CMDLINE_BOOL
1656 Set this option to 'Y' to have the kernel ignore the boot loader
1657 command line, and use ONLY the built-in command line.
1659 This is used to work around broken boot loaders. This should
1660 be set to 'N' under normal conditions.
1664 config ARCH_ENABLE_MEMORY_HOTPLUG
1666 depends on X86_64 || (X86_32 && HIGHMEM)
1668 config ARCH_ENABLE_MEMORY_HOTREMOVE
1670 depends on MEMORY_HOTPLUG
1672 config USE_PERCPU_NUMA_NODE_ID
1676 menu "Power management and ACPI options"
1678 config ARCH_HIBERNATION_HEADER
1680 depends on X86_64 && HIBERNATION
1682 source "kernel/power/Kconfig"
1684 source "drivers/acpi/Kconfig"
1686 source "drivers/sfi/Kconfig"
1690 depends on APM || APM_MODULE
1693 tristate "APM (Advanced Power Management) BIOS support"
1694 depends on X86_32 && PM_SLEEP
1696 APM is a BIOS specification for saving power using several different
1697 techniques. This is mostly useful for battery powered laptops with
1698 APM compliant BIOSes. If you say Y here, the system time will be
1699 reset after a RESUME operation, the /proc/apm device will provide
1700 battery status information, and user-space programs will receive
1701 notification of APM "events" (e.g. battery status change).
1703 If you select "Y" here, you can disable actual use of the APM
1704 BIOS by passing the "apm=off" option to the kernel at boot time.
1706 Note that the APM support is almost completely disabled for
1707 machines with more than one CPU.
1709 In order to use APM, you will need supporting software. For location
1710 and more information, read <file:Documentation/power/pm.txt> and the
1711 Battery Powered Linux mini-HOWTO, available from
1712 <http://www.tldp.org/docs.html#howto>.
1714 This driver does not spin down disk drives (see the hdparm(8)
1715 manpage ("man 8 hdparm") for that), and it doesn't turn off
1716 VESA-compliant "green" monitors.
1718 This driver does not support the TI 4000M TravelMate and the ACER
1719 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1720 desktop machines also don't have compliant BIOSes, and this driver
1721 may cause those machines to panic during the boot phase.
1723 Generally, if you don't have a battery in your machine, there isn't
1724 much point in using this driver and you should say N. If you get
1725 random kernel OOPSes or reboots that don't seem to be related to
1726 anything, try disabling/enabling this option (or disabling/enabling
1729 Some other things you should try when experiencing seemingly random,
1732 1) make sure that you have enough swap space and that it is
1734 2) pass the "no-hlt" option to the kernel
1735 3) switch on floating point emulation in the kernel and pass
1736 the "no387" option to the kernel
1737 4) pass the "floppy=nodma" option to the kernel
1738 5) pass the "mem=4M" option to the kernel (thereby disabling
1739 all but the first 4 MB of RAM)
1740 6) make sure that the CPU is not over clocked.
1741 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1742 8) disable the cache from your BIOS settings
1743 9) install a fan for the video card or exchange video RAM
1744 10) install a better fan for the CPU
1745 11) exchange RAM chips
1746 12) exchange the motherboard.
1748 To compile this driver as a module, choose M here: the
1749 module will be called apm.
1753 config APM_IGNORE_USER_SUSPEND
1754 bool "Ignore USER SUSPEND"
1756 This option will ignore USER SUSPEND requests. On machines with a
1757 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1758 series notebooks, it is necessary to say Y because of a BIOS bug.
1760 config APM_DO_ENABLE
1761 bool "Enable PM at boot time"
1763 Enable APM features at boot time. From page 36 of the APM BIOS
1764 specification: "When disabled, the APM BIOS does not automatically
1765 power manage devices, enter the Standby State, enter the Suspend
1766 State, or take power saving steps in response to CPU Idle calls."
1767 This driver will make CPU Idle calls when Linux is idle (unless this
1768 feature is turned off -- see "Do CPU IDLE calls", below). This
1769 should always save battery power, but more complicated APM features
1770 will be dependent on your BIOS implementation. You may need to turn
1771 this option off if your computer hangs at boot time when using APM
1772 support, or if it beeps continuously instead of suspending. Turn
1773 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1774 T400CDT. This is off by default since most machines do fine without
1778 bool "Make CPU Idle calls when idle"
1780 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1781 On some machines, this can activate improved power savings, such as
1782 a slowed CPU clock rate, when the machine is idle. These idle calls
1783 are made after the idle loop has run for some length of time (e.g.,
1784 333 mS). On some machines, this will cause a hang at boot time or
1785 whenever the CPU becomes idle. (On machines with more than one CPU,
1786 this option does nothing.)
1788 config APM_DISPLAY_BLANK
1789 bool "Enable console blanking using APM"
1791 Enable console blanking using the APM. Some laptops can use this to
1792 turn off the LCD backlight when the screen blanker of the Linux
1793 virtual console blanks the screen. Note that this is only used by
1794 the virtual console screen blanker, and won't turn off the backlight
1795 when using the X Window system. This also doesn't have anything to
1796 do with your VESA-compliant power-saving monitor. Further, this
1797 option doesn't work for all laptops -- it might not turn off your
1798 backlight at all, or it might print a lot of errors to the console,
1799 especially if you are using gpm.
1801 config APM_ALLOW_INTS
1802 bool "Allow interrupts during APM BIOS calls"
1804 Normally we disable external interrupts while we are making calls to
1805 the APM BIOS as a measure to lessen the effects of a badly behaving
1806 BIOS implementation. The BIOS should reenable interrupts if it
1807 needs to. Unfortunately, some BIOSes do not -- especially those in
1808 many of the newer IBM Thinkpads. If you experience hangs when you
1809 suspend, try setting this to Y. Otherwise, say N.
1813 source "drivers/cpufreq/Kconfig"
1815 source "drivers/cpuidle/Kconfig"
1817 source "drivers/idle/Kconfig"
1822 menu "Bus options (PCI etc.)"
1827 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1829 Find out whether you have a PCI motherboard. PCI is the name of a
1830 bus system, i.e. the way the CPU talks to the other stuff inside
1831 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1832 VESA. If you have PCI, say Y, otherwise N.
1835 prompt "PCI access mode"
1836 depends on X86_32 && PCI
1839 On PCI systems, the BIOS can be used to detect the PCI devices and
1840 determine their configuration. However, some old PCI motherboards
1841 have BIOS bugs and may crash if this is done. Also, some embedded
1842 PCI-based systems don't have any BIOS at all. Linux can also try to
1843 detect the PCI hardware directly without using the BIOS.
1845 With this option, you can specify how Linux should detect the
1846 PCI devices. If you choose "BIOS", the BIOS will be used,
1847 if you choose "Direct", the BIOS won't be used, and if you
1848 choose "MMConfig", then PCI Express MMCONFIG will be used.
1849 If you choose "Any", the kernel will try MMCONFIG, then the
1850 direct access method and falls back to the BIOS if that doesn't
1851 work. If unsure, go with the default, which is "Any".
1856 config PCI_GOMMCONFIG
1873 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1875 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1878 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1882 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
1886 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1890 depends on PCI && XEN
1898 bool "Support mmconfig PCI config space access"
1899 depends on X86_64 && PCI && ACPI
1901 config PCI_CNB20LE_QUIRK
1902 bool "Read CNB20LE Host Bridge Windows" if EXPERT
1904 depends on PCI && EXPERIMENTAL
1906 Read the PCI windows out of the CNB20LE host bridge. This allows
1907 PCI hotplug to work on systems with the CNB20LE chipset which do
1910 There's no public spec for this chipset, and this functionality
1911 is known to be incomplete.
1913 You should say N unless you know you need this.
1915 source "drivers/pci/pcie/Kconfig"
1917 source "drivers/pci/Kconfig"
1919 # x86_64 have no ISA slots, but can have ISA-style DMA.
1921 bool "ISA-style DMA support" if (X86_64 && EXPERT)
1924 Enables ISA-style DMA support for devices requiring such controllers.
1932 Find out whether you have ISA slots on your motherboard. ISA is the
1933 name of a bus system, i.e. the way the CPU talks to the other stuff
1934 inside your box. Other bus systems are PCI, EISA, MicroChannel
1935 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1936 newer boards don't support it. If you have ISA, say Y, otherwise N.
1942 The Extended Industry Standard Architecture (EISA) bus was
1943 developed as an open alternative to the IBM MicroChannel bus.
1945 The EISA bus provided some of the features of the IBM MicroChannel
1946 bus while maintaining backward compatibility with cards made for
1947 the older ISA bus. The EISA bus saw limited use between 1988 and
1948 1995 when it was made obsolete by the PCI bus.
1950 Say Y here if you are building a kernel for an EISA-based machine.
1954 source "drivers/eisa/Kconfig"
1959 MicroChannel Architecture is found in some IBM PS/2 machines and
1960 laptops. It is a bus system similar to PCI or ISA. See
1961 <file:Documentation/mca.txt> (and especially the web page given
1962 there) before attempting to build an MCA bus kernel.
1964 source "drivers/mca/Kconfig"
1967 tristate "NatSemi SCx200 support"
1969 This provides basic support for National Semiconductor's
1970 (now AMD's) Geode processors. The driver probes for the
1971 PCI-IDs of several on-chip devices, so its a good dependency
1972 for other scx200_* drivers.
1974 If compiled as a module, the driver is named scx200.
1976 config SCx200HR_TIMER
1977 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1981 This driver provides a clocksource built upon the on-chip
1982 27MHz high-resolution timer. Its also a workaround for
1983 NSC Geode SC-1100's buggy TSC, which loses time when the
1984 processor goes idle (as is done by the scheduler). The
1985 other workaround is idle=poll boot option.
1988 bool "One Laptop Per Child support"
1994 Add support for detecting the unique features of the OLPC
1998 tristate "OLPC XO-1 support"
1999 depends on OLPC && MFD_CS5535
2001 Add support for non-essential features of the OLPC XO-1 laptop.
2007 depends on CPU_SUP_AMD && PCI
2009 source "drivers/pcmcia/Kconfig"
2011 source "drivers/pci/hotplug/Kconfig"
2014 bool "RapidIO support"
2018 If you say Y here, the kernel will include drivers and
2019 infrastructure code to support RapidIO interconnect devices.
2021 source "drivers/rapidio/Kconfig"
2026 menu "Executable file formats / Emulations"
2028 source "fs/Kconfig.binfmt"
2030 config IA32_EMULATION
2031 bool "IA32 Emulation"
2033 select COMPAT_BINFMT_ELF
2035 Include code to run 32-bit programs under a 64-bit kernel. You should
2036 likely turn this on, unless you're 100% sure that you don't have any
2037 32-bit programs left.
2040 tristate "IA32 a.out support"
2041 depends on IA32_EMULATION
2043 Support old a.out binaries in the 32bit emulation.
2047 depends on IA32_EMULATION
2049 config COMPAT_FOR_U64_ALIGNMENT
2053 config SYSVIPC_COMPAT
2055 depends on COMPAT && SYSVIPC
2059 depends on COMPAT && KEYS
2065 config HAVE_ATOMIC_IOMAP
2069 config HAVE_TEXT_POKE_SMP
2071 select STOP_MACHINE if SMP
2073 source "net/Kconfig"
2075 source "drivers/Kconfig"
2077 source "drivers/firmware/Kconfig"
2081 source "arch/x86/Kconfig.debug"
2083 source "security/Kconfig"
2085 source "crypto/Kconfig"
2087 source "arch/x86/kvm/Kconfig"
2089 source "lib/Kconfig"