3 bool "64-bit kernel" if ARCH = "x86"
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
18 select X86_DEV_DMA_OPS
23 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
24 select HAVE_AOUT if X86_32
25 select HAVE_UNSTABLE_SCHED_CLOCK
26 select ARCH_SUPPORTS_NUMA_BALANCING
27 select ARCH_WANTS_PROT_NUMA_PROT_NONE
30 select HAVE_PCSPKR_PLATFORM
31 select HAVE_PERF_EVENTS
32 select HAVE_IOREMAP_PROT
35 select HAVE_MEMBLOCK_NODE_MAP
36 select ARCH_DISCARD_MEMBLOCK
37 select ARCH_WANT_OPTIONAL_GPIOLIB
38 select ARCH_WANT_FRAME_POINTERS
40 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
41 select HAVE_KRETPROBES
43 select HAVE_KPROBES_ON_FTRACE
44 select HAVE_FTRACE_MCOUNT_RECORD
45 select HAVE_FENTRY if X86_64
46 select HAVE_C_RECORDMCOUNT
47 select HAVE_DYNAMIC_FTRACE
48 select HAVE_DYNAMIC_FTRACE_WITH_REGS
49 select HAVE_FUNCTION_TRACER
50 select HAVE_FUNCTION_GRAPH_TRACER
51 select HAVE_FUNCTION_GRAPH_FP_TEST
52 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
53 select HAVE_SYSCALL_TRACEPOINTS
54 select SYSCTL_EXCEPTION_TRACE
57 select HAVE_ARCH_TRACEHOOK
58 select HAVE_GENERIC_DMA_COHERENT if X86_32
59 select HAVE_EFFICIENT_UNALIGNED_ACCESS
60 select USER_STACKTRACE_SUPPORT
61 select HAVE_REGS_AND_STACK_ACCESS_API
62 select HAVE_DMA_API_DEBUG
63 select HAVE_KERNEL_GZIP
64 select HAVE_KERNEL_BZIP2
65 select HAVE_KERNEL_LZMA
67 select HAVE_KERNEL_LZO
68 select HAVE_HW_BREAKPOINT
69 select HAVE_MIXED_BREAKPOINTS_REGS
71 select HAVE_PERF_EVENTS_NMI
73 select HAVE_PERF_USER_STACK_DUMP
74 select HAVE_DEBUG_KMEMLEAK
76 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
77 select HAVE_CMPXCHG_LOCAL
78 select HAVE_CMPXCHG_DOUBLE
79 select HAVE_ARCH_KMEMCHECK
80 select HAVE_USER_RETURN_NOTIFIER
81 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
82 select HAVE_ARCH_JUMP_LABEL
83 select HAVE_TEXT_POKE_SMP
84 select HAVE_GENERIC_HARDIRQS
85 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
87 select GENERIC_FIND_FIRST_BIT
88 select GENERIC_IRQ_PROBE
89 select GENERIC_PENDING_IRQ if SMP
90 select GENERIC_IRQ_SHOW
91 select GENERIC_CLOCKEVENTS_MIN_ADJUST
92 select IRQ_FORCED_THREADING
93 select USE_GENERIC_SMP_HELPERS if SMP
94 select HAVE_BPF_JIT if X86_64
95 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
97 select ARCH_HAVE_NMI_SAFE_CMPXCHG
99 select DCACHE_WORD_ACCESS
100 select GENERIC_SMP_IDLE_THREAD
101 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
102 select HAVE_ARCH_SECCOMP_FILTER
103 select BUILDTIME_EXTABLE_SORT
104 select GENERIC_CMOS_UPDATE
105 select CLOCKSOURCE_WATCHDOG
106 select GENERIC_CLOCKEVENTS
107 select ARCH_CLOCKSOURCE_DATA if X86_64
108 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
109 select GENERIC_TIME_VSYSCALL if X86_64
110 select KTIME_SCALAR if X86_32
111 select GENERIC_STRNCPY_FROM_USER
112 select GENERIC_STRNLEN_USER
113 select HAVE_CONTEXT_TRACKING if X86_64
114 select HAVE_IRQ_TIME_ACCOUNTING
116 select MODULES_USE_ELF_REL if X86_32
117 select MODULES_USE_ELF_RELA if X86_64
118 select CLONE_BACKWARDS if X86_32
119 select ARCH_USE_BUILTIN_BSWAP
120 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
121 select OLD_SIGACTION if X86_32
122 select COMPAT_OLD_SIGACTION if IA32_EMULATION
125 config INSTRUCTION_DECODER
127 depends on KPROBES || PERF_EVENTS || UPROBES
131 default "elf32-i386" if X86_32
132 default "elf64-x86-64" if X86_64
134 config ARCH_DEFCONFIG
136 default "arch/x86/configs/i386_defconfig" if X86_32
137 default "arch/x86/configs/x86_64_defconfig" if X86_64
139 config LOCKDEP_SUPPORT
142 config STACKTRACE_SUPPORT
145 config HAVE_LATENCYTOP_SUPPORT
154 config NEED_DMA_MAP_STATE
156 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
158 config NEED_SG_DMA_LENGTH
161 config GENERIC_ISA_DMA
163 depends on ISA_DMA_API
168 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
170 config GENERIC_BUG_RELATIVE_POINTERS
173 config GENERIC_HWEIGHT
176 config ARCH_MAY_HAVE_PC_FDC
178 depends on ISA_DMA_API
180 config RWSEM_XCHGADD_ALGORITHM
183 config GENERIC_CALIBRATE_DELAY
186 config ARCH_HAS_CPU_RELAX
189 config ARCH_HAS_CACHE_LINE_SIZE
192 config ARCH_HAS_CPU_AUTOPROBE
195 config HAVE_SETUP_PER_CPU_AREA
198 config NEED_PER_CPU_EMBED_FIRST_CHUNK
201 config NEED_PER_CPU_PAGE_FIRST_CHUNK
204 config ARCH_HIBERNATION_POSSIBLE
207 config ARCH_SUSPEND_POSSIBLE
218 config ARCH_SUPPORTS_OPTIMIZED_INLINING
221 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
224 config HAVE_INTEL_TXT
226 depends on INTEL_IOMMU && ACPI
230 depends on X86_32 && SMP
234 depends on X86_64 && SMP
240 config X86_32_LAZY_GS
242 depends on X86_32 && !CC_STACKPROTECTOR
244 config ARCH_HWEIGHT_CFLAGS
246 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
247 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
249 config ARCH_CPU_PROBE_RELEASE
251 depends on HOTPLUG_CPU
253 config ARCH_SUPPORTS_UPROBES
256 source "init/Kconfig"
257 source "kernel/Kconfig.freezer"
259 menu "Processor type and features"
262 bool "DMA memory allocation support" if EXPERT
265 DMA memory allocation support allows devices with less than 32-bit
266 addressing to allocate within the first 16MB of address space.
267 Disable if no such devices will be used.
272 bool "Symmetric multi-processing support"
274 This enables support for systems with more than one CPU. If you have
275 a system with only one CPU, like most personal computers, say N. If
276 you have a system with more than one CPU, say Y.
278 If you say N here, the kernel will run on single and multiprocessor
279 machines, but will use only one CPU of a multiprocessor machine. If
280 you say Y here, the kernel will run on many, but not all,
281 singleprocessor machines. On a singleprocessor machine, the kernel
282 will run faster if you say N here.
284 Note that if you say Y here and choose architecture "586" or
285 "Pentium" under "Processor family", the kernel will not work on 486
286 architectures. Similarly, multiprocessor kernels for the "PPro"
287 architecture may not work on all Pentium based boards.
289 People using multiprocessor machines who say Y here should also say
290 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
291 Management" code will be disabled if you say Y here.
293 See also <file:Documentation/x86/i386/IO-APIC.txt>,
294 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
295 <http://www.tldp.org/docs.html#howto>.
297 If you don't know what to do here, say N.
300 bool "Support x2apic"
301 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
303 This enables x2apic support on CPUs that have this feature.
305 This allows 32-bit apic IDs (so it can support very large systems),
306 and accesses the local apic via MSRs not via mmio.
308 If you don't know what to do here, say N.
311 bool "Enable MPS table" if ACPI || SFI
313 depends on X86_LOCAL_APIC
315 For old smp systems that do not have proper acpi support. Newer systems
316 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
319 bool "Support for big SMP systems with more than 8 CPUs"
320 depends on X86_32 && SMP
322 This option is needed for the systems that have more than 8 CPUs
326 depends on X86_GOLDFISH
329 config X86_EXTENDED_PLATFORM
330 bool "Support for extended (non-PC) x86 platforms"
333 If you disable this option then the kernel will only support
334 standard PC platforms. (which covers the vast majority of
337 If you enable this option then you'll be able to select support
338 for the following (non-PC) 32 bit x86 platforms:
339 Goldfish (Android emulator)
343 SGI 320/540 (Visual Workstation)
344 STA2X11-based (e.g. Northville)
345 Summit/EXA (IBM x440)
346 Unisys ES7000 IA32 series
347 Moorestown MID devices
349 If you have one of these systems, or if you want to build a
350 generic distribution kernel, say Y here - otherwise say N.
354 config X86_EXTENDED_PLATFORM
355 bool "Support for extended (non-PC) x86 platforms"
358 If you disable this option then the kernel will only support
359 standard PC platforms. (which covers the vast majority of
362 If you enable this option then you'll be able to select support
363 for the following (non-PC) 64 bit x86 platforms:
368 If you have one of these systems, or if you want to build a
369 generic distribution kernel, say Y here - otherwise say N.
371 # This is an alphabetically sorted list of 64 bit extended platforms
372 # Please maintain the alphabetic order if and when there are additions
374 bool "Numascale NumaChip"
376 depends on X86_EXTENDED_PLATFORM
379 depends on X86_X2APIC
380 depends on PCI_MMCONFIG
382 Adds support for Numascale NumaChip large-SMP systems. Needed to
383 enable more than ~168 cores.
384 If you don't have one of these, you should say N here.
388 select HYPERVISOR_GUEST
390 depends on X86_64 && PCI
391 depends on X86_EXTENDED_PLATFORM
394 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
395 supposed to run on these EM64T-based machines. Only choose this option
396 if you have one of these machines.
399 bool "SGI Ultraviolet"
401 depends on X86_EXTENDED_PLATFORM
403 depends on X86_X2APIC
405 This option is needed in order to support SGI Ultraviolet systems.
406 If you don't have one of these, you should say N here.
408 # Following is an alphabetically sorted list of 32 bit extended platforms
409 # Please maintain the alphabetic order if and when there are additions
412 bool "Goldfish (Virtual Platform)"
414 depends on X86_EXTENDED_PLATFORM
416 Enable support for the Goldfish virtual platform used primarily
417 for Android development. Unless you are building for the Android
418 Goldfish emulator say N here.
421 bool "CE4100 TV platform"
423 depends on PCI_GODIRECT
425 depends on X86_EXTENDED_PLATFORM
426 select X86_REBOOTFIXUPS
428 select OF_EARLY_FLATTREE
431 Select for the Intel CE media processor (CE4100) SOC.
432 This option compiles in support for the CE4100 SOC for settop
433 boxes and media devices.
435 config X86_WANT_INTEL_MID
436 bool "Intel MID platform support"
438 depends on X86_EXTENDED_PLATFORM
440 Select to build a kernel capable of supporting Intel MID platform
441 systems which do not have the PCI legacy interfaces (Moorestown,
442 Medfield). If you are building for a PC class system say N here.
444 if X86_WANT_INTEL_MID
450 bool "Medfield MID platform"
453 depends on X86_IO_APIC
461 select X86_PLATFORM_DEVICES
462 select MFD_INTEL_MSIC
464 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
465 Internet Device(MID) platform.
466 Unlike standard x86 PCs, Medfield does not have many legacy devices
467 nor standard legacy replacement devices/features. e.g. Medfield does
468 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
472 config X86_INTEL_LPSS
473 bool "Intel Low Power Subsystem Support"
477 Select to build support for Intel Low Power Subsystem such as
478 found on Intel Lynxpoint PCH. Selecting this option enables
479 things like clock tree (common clock framework) which are needed
480 by the LPSS peripheral drivers.
483 bool "RDC R-321x SoC"
485 depends on X86_EXTENDED_PLATFORM
487 select X86_REBOOTFIXUPS
489 This option is needed for RDC R-321x system-on-chip, also known
491 If you don't have one of these chips, you should say N here.
493 config X86_32_NON_STANDARD
494 bool "Support non-standard 32-bit SMP architectures"
495 depends on X86_32 && SMP
496 depends on X86_EXTENDED_PLATFORM
498 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
499 STA2X11, default subarchitectures. It is intended for a generic
500 binary kernel. If you select them all, kernel will probe it
501 one by one and will fallback to default.
503 # Alphabetically sorted list of Non standard 32 bit platforms
506 bool "NUMAQ (IBM/Sequent)"
507 depends on X86_32_NON_STANDARD
512 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
513 NUMA multiquad box. This changes the way that processors are
514 bootstrapped, and uses Clustered Logical APIC addressing mode instead
515 of Flat Logical. You will need a new lynxer.elf file to flash your
516 firmware with - send email to <Martin.Bligh@us.ibm.com>.
518 config X86_SUPPORTS_MEMORY_FAILURE
520 # MCE code calls memory_failure():
522 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
523 depends on !X86_NUMAQ
524 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
525 depends on X86_64 || !SPARSEMEM
526 select ARCH_SUPPORTS_MEMORY_FAILURE
529 bool "SGI 320/540 (Visual Workstation)"
530 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
531 depends on X86_32_NON_STANDARD
533 The SGI Visual Workstation series is an IA32-based workstation
534 based on SGI systems chips with some legacy PC hardware attached.
536 Say Y here to create a kernel to run on the SGI 320 or 540.
538 A kernel compiled for the Visual Workstation will run on general
539 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
542 bool "STA2X11 Companion Chip Support"
543 depends on X86_32_NON_STANDARD && PCI
544 select X86_DEV_DMA_OPS
548 select ARCH_REQUIRE_GPIOLIB
551 This adds support for boards based on the STA2X11 IO-Hub,
552 a.k.a. "ConneXt". The chip is used in place of the standard
553 PC chipset, so all "standard" peripherals are missing. If this
554 option is selected the kernel will still be able to boot on
555 standard PC machines.
558 bool "Summit/EXA (IBM x440)"
559 depends on X86_32_NON_STANDARD
561 This option is needed for IBM systems that use the Summit/EXA chipset.
562 In particular, it is needed for the x440.
565 bool "Unisys ES7000 IA32 series"
566 depends on X86_32_NON_STANDARD && X86_BIGSMP
568 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
569 supposed to run on an IA32-based Unisys ES7000 system.
572 tristate "Eurobraille/Iris poweroff module"
575 The Iris machines from EuroBraille do not have APM or ACPI support
576 to shut themselves down properly. A special I/O sequence is
577 needed to do so, which is what this module does at
580 This is only for Iris machines from EuroBraille.
584 config SCHED_OMIT_FRAME_POINTER
586 prompt "Single-depth WCHAN output"
589 Calculate simpler /proc/<PID>/wchan values. If this option
590 is disabled then wchan values will recurse back to the
591 caller function. This provides more accurate wchan values,
592 at the expense of slightly more scheduling overhead.
594 If in doubt, say "Y".
596 menuconfig HYPERVISOR_GUEST
597 bool "Linux guest support"
599 Say Y here to enable options for running Linux under various hyper-
600 visors. This option enables basic hypervisor detection and platform
603 If you say N, all options in this submenu will be skipped and
604 disabled, and Linux guest support won't be built in.
609 bool "Enable paravirtualization code"
611 This changes the kernel so it can modify itself when it is run
612 under a hypervisor, potentially improving performance significantly
613 over full virtualization. However, when run without a hypervisor
614 the kernel is theoretically slower and slightly larger.
616 config PARAVIRT_DEBUG
617 bool "paravirt-ops debugging"
618 depends on PARAVIRT && DEBUG_KERNEL
620 Enable to debug paravirt_ops internals. Specifically, BUG if
621 a paravirt_op is missing when it is called.
623 config PARAVIRT_SPINLOCKS
624 bool "Paravirtualization layer for spinlocks"
625 depends on PARAVIRT && SMP
627 Paravirtualized spinlocks allow a pvops backend to replace the
628 spinlock implementation with something virtualization-friendly
629 (for example, block the virtual CPU rather than spinning).
631 Unfortunately the downside is an up to 5% performance hit on
632 native kernels, with various workloads.
634 If you are unsure how to answer this question, answer N.
636 source "arch/x86/xen/Kconfig"
639 bool "KVM Guest support (including kvmclock)"
641 select PARAVIRT_CLOCK
644 This option enables various optimizations for running under the KVM
645 hypervisor. It includes a paravirtualized clock, so that instead
646 of relying on a PIT (or probably other) emulation by the
647 underlying device model, the host provides the guest with
648 timing infrastructure such as time of day, and system time
650 source "arch/x86/lguest/Kconfig"
652 config PARAVIRT_TIME_ACCOUNTING
653 bool "Paravirtual steal time accounting"
657 Select this option to enable fine granularity task steal time
658 accounting. Time spent executing other tasks in parallel with
659 the current vCPU is discounted from the vCPU power. To account for
660 that, there can be a small performance impact.
662 If in doubt, say N here.
664 config PARAVIRT_CLOCK
667 endif #HYPERVISOR_GUEST
675 This option adds a kernel parameter 'memtest', which allows memtest
677 memtest=0, mean disabled; -- default
678 memtest=1, mean do 1 test pattern;
680 memtest=4, mean do 4 test patterns.
681 If you are unsure how to answer this question, answer N.
683 config X86_SUMMIT_NUMA
685 depends on X86_32 && NUMA && X86_32_NON_STANDARD
687 config X86_CYCLONE_TIMER
689 depends on X86_SUMMIT
691 source "arch/x86/Kconfig.cpu"
695 prompt "HPET Timer Support" if X86_32
697 Use the IA-PC HPET (High Precision Event Timer) to manage
698 time in preference to the PIT and RTC, if a HPET is
700 HPET is the next generation timer replacing legacy 8254s.
701 The HPET provides a stable time base on SMP
702 systems, unlike the TSC, but it is more expensive to access,
703 as it is off-chip. You can find the HPET spec at
704 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
706 You can safely choose Y here. However, HPET will only be
707 activated if the platform and the BIOS support this feature.
708 Otherwise the 8254 will be used for timing services.
710 Choose N to continue using the legacy 8254 timer.
712 config HPET_EMULATE_RTC
714 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
717 def_bool y if X86_INTEL_MID
718 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
720 depends on X86_INTEL_MID && SFI
722 APB timer is the replacement for 8254, HPET on X86 MID platforms.
723 The APBT provides a stable time base on SMP
724 systems, unlike the TSC, but it is more expensive to access,
725 as it is off-chip. APB timers are always running regardless of CPU
726 C states, they are used as per CPU clockevent device when possible.
728 # Mark as expert because too many people got it wrong.
729 # The code disables itself when not needed.
732 bool "Enable DMI scanning" if EXPERT
734 Enabled scanning of DMI to identify machine quirks. Say Y
735 here unless you have verified that your setup is not
736 affected by entries in the DMI blacklist. Required by PNP
740 bool "GART IOMMU support" if EXPERT
743 depends on X86_64 && PCI && AMD_NB
745 Support for full DMA access of devices with 32bit memory access only
746 on systems with more than 3GB. This is usually needed for USB,
747 sound, many IDE/SATA chipsets and some other devices.
748 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
749 based hardware IOMMU and a software bounce buffer based IOMMU used
750 on Intel systems and as fallback.
751 The code is only active when needed (enough memory and limited
752 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
756 bool "IBM Calgary IOMMU support"
758 depends on X86_64 && PCI
760 Support for hardware IOMMUs in IBM's xSeries x366 and x460
761 systems. Needed to run systems with more than 3GB of memory
762 properly with 32-bit PCI devices that do not support DAC
763 (Double Address Cycle). Calgary also supports bus level
764 isolation, where all DMAs pass through the IOMMU. This
765 prevents them from going anywhere except their intended
766 destination. This catches hard-to-find kernel bugs and
767 mis-behaving drivers and devices that do not use the DMA-API
768 properly to set up their DMA buffers. The IOMMU can be
769 turned off at boot time with the iommu=off parameter.
770 Normally the kernel will make the right choice by itself.
773 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
775 prompt "Should Calgary be enabled by default?"
776 depends on CALGARY_IOMMU
778 Should Calgary be enabled by default? if you choose 'y', Calgary
779 will be used (if it exists). If you choose 'n', Calgary will not be
780 used even if it exists. If you choose 'n' and would like to use
781 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
784 # need this always selected by IOMMU for the VIA workaround
788 Support for software bounce buffers used on x86-64 systems
789 which don't have a hardware IOMMU. Using this PCI devices
790 which can only access 32-bits of memory can be used on systems
791 with more than 3 GB of memory.
796 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
799 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
800 depends on X86_64 && SMP && DEBUG_KERNEL
801 select CPUMASK_OFFSTACK
803 Enable maximum number of CPUS and NUMA Nodes for this architecture.
807 int "Maximum number of CPUs" if SMP && !MAXSMP
808 range 2 8 if SMP && X86_32 && !X86_BIGSMP
809 range 2 512 if SMP && !MAXSMP
811 default "4096" if MAXSMP
812 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
815 This allows you to specify the maximum number of CPUs which this
816 kernel will support. The maximum supported value is 512 and the
817 minimum value which makes sense is 2.
819 This is purely to save memory - each supported CPU adds
820 approximately eight kilobytes to the kernel image.
823 bool "SMT (Hyperthreading) scheduler support"
826 SMT scheduler support improves the CPU scheduler's decision making
827 when dealing with Intel Pentium 4 chips with HyperThreading at a
828 cost of slightly increased overhead in some places. If unsure say
833 prompt "Multi-core scheduler support"
836 Multi-core scheduler support improves the CPU scheduler's decision
837 making when dealing with multi-core CPU chips at a cost of slightly
838 increased overhead in some places. If unsure say N here.
840 source "kernel/Kconfig.preempt"
843 bool "Local APIC support on uniprocessors"
844 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
846 A local APIC (Advanced Programmable Interrupt Controller) is an
847 integrated interrupt controller in the CPU. If you have a single-CPU
848 system which has a processor with a local APIC, you can say Y here to
849 enable and use it. If you say Y here even though your machine doesn't
850 have a local APIC, then the kernel will still run with no slowdown at
851 all. The local APIC supports CPU-generated self-interrupts (timer,
852 performance counters), and the NMI watchdog which detects hard
856 bool "IO-APIC support on uniprocessors"
857 depends on X86_UP_APIC
859 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
860 SMP-capable replacement for PC-style interrupt controllers. Most
861 SMP systems and many recent uniprocessor systems have one.
863 If you have a single-CPU system with an IO-APIC, you can say Y here
864 to use it. If you say Y here even though your machine doesn't have
865 an IO-APIC, then the kernel will still run with no slowdown at all.
867 config X86_LOCAL_APIC
869 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
873 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
875 config X86_VISWS_APIC
877 depends on X86_32 && X86_VISWS
879 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
880 bool "Reroute for broken boot IRQs"
881 depends on X86_IO_APIC
883 This option enables a workaround that fixes a source of
884 spurious interrupts. This is recommended when threaded
885 interrupt handling is used on systems where the generation of
886 superfluous "boot interrupts" cannot be disabled.
888 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
889 entry in the chipset's IO-APIC is masked (as, e.g. the RT
890 kernel does during interrupt handling). On chipsets where this
891 boot IRQ generation cannot be disabled, this workaround keeps
892 the original IRQ line masked so that only the equivalent "boot
893 IRQ" is delivered to the CPUs. The workaround also tells the
894 kernel to set up the IRQ handler on the boot IRQ line. In this
895 way only one interrupt is delivered to the kernel. Otherwise
896 the spurious second interrupt may cause the kernel to bring
897 down (vital) interrupt lines.
899 Only affects "broken" chipsets. Interrupt sharing may be
900 increased on these systems.
903 bool "Machine Check / overheating reporting"
906 Machine Check support allows the processor to notify the
907 kernel if it detects a problem (e.g. overheating, data corruption).
908 The action the kernel takes depends on the severity of the problem,
909 ranging from warning messages to halting the machine.
913 prompt "Intel MCE features"
914 depends on X86_MCE && X86_LOCAL_APIC
916 Additional support for intel specific MCE features such as
921 prompt "AMD MCE features"
922 depends on X86_MCE && X86_LOCAL_APIC
924 Additional support for AMD specific MCE features such as
925 the DRAM Error Threshold.
927 config X86_ANCIENT_MCE
928 bool "Support for old Pentium 5 / WinChip machine checks"
929 depends on X86_32 && X86_MCE
931 Include support for machine check handling on old Pentium 5 or WinChip
932 systems. These typically need to be enabled explicitely on the command
935 config X86_MCE_THRESHOLD
936 depends on X86_MCE_AMD || X86_MCE_INTEL
939 config X86_MCE_INJECT
941 tristate "Machine check injector support"
943 Provide support for injecting machine checks for testing purposes.
944 If you don't know what a machine check is and you don't do kernel
945 QA it is safe to say n.
947 config X86_THERMAL_VECTOR
949 depends on X86_MCE_INTEL
952 bool "Enable VM86 support" if EXPERT
956 This option is required by programs like DOSEMU to run 16-bit legacy
957 code on X86 processors. It also may be needed by software like
958 XFree86 to initialize some video cards via BIOS. Disabling this
959 option saves about 6k.
962 tristate "Toshiba Laptop support"
965 This adds a driver to safely access the System Management Mode of
966 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
967 not work on models with a Phoenix BIOS. The System Management Mode
968 is used to set the BIOS and power saving options on Toshiba portables.
970 For information on utilities to make use of this driver see the
971 Toshiba Linux utilities web site at:
972 <http://www.buzzard.org.uk/toshiba/>.
974 Say Y if you intend to run this kernel on a Toshiba portable.
978 tristate "Dell laptop support"
981 This adds a driver to safely access the System Management Mode
982 of the CPU on the Dell Inspiron 8000. The System Management Mode
983 is used to read cpu temperature and cooling fan status and to
984 control the fans on the I8K portables.
986 This driver has been tested only on the Inspiron 8000 but it may
987 also work with other Dell laptops. You can force loading on other
988 models by passing the parameter `force=1' to the module. Use at
991 For information on utilities to make use of this driver see the
992 I8K Linux utilities web site at:
993 <http://people.debian.org/~dz/i8k/>
995 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
998 config X86_REBOOTFIXUPS
999 bool "Enable X86 board specific fixups for reboot"
1002 This enables chipset and/or board specific fixups to be done
1003 in order to get reboot to work correctly. This is only needed on
1004 some combinations of hardware and BIOS. The symptom, for which
1005 this config is intended, is when reboot ends with a stalled/hung
1008 Currently, the only fixup is for the Geode machines using
1009 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1011 Say Y if you want to enable the fixup. Currently, it's safe to
1012 enable this option even if you don't need it.
1016 tristate "CPU microcode loading support"
1020 If you say Y here, you will be able to update the microcode on
1021 certain Intel and AMD processors. The Intel support is for the
1022 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1023 Xeon etc. The AMD support is for families 0x10 and later. You will
1024 obviously need the actual microcode binary data itself which is not
1025 shipped with the Linux kernel.
1027 This option selects the general module only, you need to select
1028 at least one vendor specific module as well.
1030 To compile this driver as a module, choose M here: the module
1031 will be called microcode.
1033 config MICROCODE_INTEL
1034 bool "Intel microcode loading support"
1035 depends on MICROCODE
1039 This options enables microcode patch loading support for Intel
1042 For latest news and information on obtaining all the required
1043 Intel ingredients for this driver, check:
1044 <http://www.urbanmyth.org/microcode/>.
1046 config MICROCODE_AMD
1047 bool "AMD microcode loading support"
1048 depends on MICROCODE
1051 If you select this option, microcode patch loading support for AMD
1052 processors will be enabled.
1054 config MICROCODE_OLD_INTERFACE
1056 depends on MICROCODE
1058 config MICROCODE_INTEL_LIB
1060 depends on MICROCODE_INTEL
1062 config MICROCODE_INTEL_EARLY
1065 config MICROCODE_AMD_EARLY
1068 config MICROCODE_EARLY
1069 bool "Early load microcode"
1070 depends on MICROCODE=y && BLK_DEV_INITRD
1071 select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1072 select MICROCODE_AMD_EARLY if MICROCODE_AMD
1075 This option provides functionality to read additional microcode data
1076 at the beginning of initrd image. The data tells kernel to load
1077 microcode to CPU's as early as possible. No functional change if no
1078 microcode data is glued to the initrd, therefore it's safe to say Y.
1081 tristate "/dev/cpu/*/msr - Model-specific register support"
1083 This device gives privileged processes access to the x86
1084 Model-Specific Registers (MSRs). It is a character device with
1085 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1086 MSR accesses are directed to a specific CPU on multi-processor
1090 tristate "/dev/cpu/*/cpuid - CPU information support"
1092 This device gives processes access to the x86 CPUID instruction to
1093 be executed on a specific processor. It is a character device
1094 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1098 prompt "High Memory Support"
1099 default HIGHMEM64G if X86_NUMAQ
1105 depends on !X86_NUMAQ
1107 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1108 However, the address space of 32-bit x86 processors is only 4
1109 Gigabytes large. That means that, if you have a large amount of
1110 physical memory, not all of it can be "permanently mapped" by the
1111 kernel. The physical memory that's not permanently mapped is called
1114 If you are compiling a kernel which will never run on a machine with
1115 more than 1 Gigabyte total physical RAM, answer "off" here (default
1116 choice and suitable for most users). This will result in a "3GB/1GB"
1117 split: 3GB are mapped so that each process sees a 3GB virtual memory
1118 space and the remaining part of the 4GB virtual memory space is used
1119 by the kernel to permanently map as much physical memory as
1122 If the machine has between 1 and 4 Gigabytes physical RAM, then
1125 If more than 4 Gigabytes is used then answer "64GB" here. This
1126 selection turns Intel PAE (Physical Address Extension) mode on.
1127 PAE implements 3-level paging on IA32 processors. PAE is fully
1128 supported by Linux, PAE mode is implemented on all recent Intel
1129 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1130 then the kernel will not boot on CPUs that don't support PAE!
1132 The actual amount of total physical memory will either be
1133 auto detected or can be forced by using a kernel command line option
1134 such as "mem=256M". (Try "man bootparam" or see the documentation of
1135 your boot loader (lilo or loadlin) about how to pass options to the
1136 kernel at boot time.)
1138 If unsure, say "off".
1142 depends on !X86_NUMAQ
1144 Select this if you have a 32-bit processor and between 1 and 4
1145 gigabytes of physical RAM.
1152 Select this if you have a 32-bit processor and more than 4
1153 gigabytes of physical RAM.
1158 prompt "Memory split" if EXPERT
1162 Select the desired split between kernel and user memory.
1164 If the address range available to the kernel is less than the
1165 physical memory installed, the remaining memory will be available
1166 as "high memory". Accessing high memory is a little more costly
1167 than low memory, as it needs to be mapped into the kernel first.
1168 Note that increasing the kernel address space limits the range
1169 available to user programs, making the address space there
1170 tighter. Selecting anything other than the default 3G/1G split
1171 will also likely make your kernel incompatible with binary-only
1174 If you are not absolutely sure what you are doing, leave this
1178 bool "3G/1G user/kernel split"
1179 config VMSPLIT_3G_OPT
1181 bool "3G/1G user/kernel split (for full 1G low memory)"
1183 bool "2G/2G user/kernel split"
1184 config VMSPLIT_2G_OPT
1186 bool "2G/2G user/kernel split (for full 2G low memory)"
1188 bool "1G/3G user/kernel split"
1193 default 0xB0000000 if VMSPLIT_3G_OPT
1194 default 0x80000000 if VMSPLIT_2G
1195 default 0x78000000 if VMSPLIT_2G_OPT
1196 default 0x40000000 if VMSPLIT_1G
1202 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1205 bool "PAE (Physical Address Extension) Support"
1206 depends on X86_32 && !HIGHMEM4G
1208 PAE is required for NX support, and furthermore enables
1209 larger swapspace support for non-overcommit purposes. It
1210 has the cost of more pagetable lookup overhead, and also
1211 consumes more pagetable space per process.
1213 config ARCH_PHYS_ADDR_T_64BIT
1215 depends on X86_64 || X86_PAE
1217 config ARCH_DMA_ADDR_T_64BIT
1219 depends on X86_64 || HIGHMEM64G
1221 config DIRECT_GBPAGES
1222 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1226 Allow the kernel linear mapping to use 1GB pages on CPUs that
1227 support it. This can improve the kernel's performance a tiny bit by
1228 reducing TLB pressure. If in doubt, say "Y".
1230 # Common NUMA Features
1232 bool "Numa Memory Allocation and Scheduler Support"
1234 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1235 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1237 Enable NUMA (Non Uniform Memory Access) support.
1239 The kernel will try to allocate memory used by a CPU on the
1240 local memory controller of the CPU and add some more
1241 NUMA awareness to the kernel.
1243 For 64-bit this is recommended if the system is Intel Core i7
1244 (or later), AMD Opteron, or EM64T NUMA.
1246 For 32-bit this is only needed on (rare) 32-bit-only platforms
1247 that support NUMA topologies, such as NUMAQ / Summit, or if you
1248 boot a 32-bit kernel on a 64-bit NUMA platform.
1250 Otherwise, you should say N.
1252 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1253 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1257 prompt "Old style AMD Opteron NUMA detection"
1258 depends on X86_64 && NUMA && PCI
1260 Enable AMD NUMA node topology detection. You should say Y here if
1261 you have a multi processor AMD system. This uses an old method to
1262 read the NUMA configuration directly from the builtin Northbridge
1263 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1264 which also takes priority if both are compiled in.
1266 config X86_64_ACPI_NUMA
1268 prompt "ACPI NUMA detection"
1269 depends on X86_64 && NUMA && ACPI && PCI
1272 Enable ACPI SRAT based node topology detection.
1274 # Some NUMA nodes have memory ranges that span
1275 # other nodes. Even though a pfn is valid and
1276 # between a node's start and end pfns, it may not
1277 # reside on that node. See memmap_init_zone()
1279 config NODES_SPAN_OTHER_NODES
1281 depends on X86_64_ACPI_NUMA
1284 bool "NUMA emulation"
1287 Enable NUMA emulation. A flat machine will be split
1288 into virtual nodes when booted with "numa=fake=N", where N is the
1289 number of nodes. This is only useful for debugging.
1292 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1294 default "10" if MAXSMP
1295 default "6" if X86_64
1296 default "4" if X86_NUMAQ
1298 depends on NEED_MULTIPLE_NODES
1300 Specify the maximum number of NUMA Nodes available on the target
1301 system. Increases memory reserved to accommodate various tables.
1303 config ARCH_HAVE_MEMORY_PRESENT
1305 depends on X86_32 && DISCONTIGMEM
1307 config NEED_NODE_MEMMAP_SIZE
1309 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1311 config ARCH_FLATMEM_ENABLE
1313 depends on X86_32 && !NUMA
1315 config ARCH_DISCONTIGMEM_ENABLE
1317 depends on NUMA && X86_32
1319 config ARCH_DISCONTIGMEM_DEFAULT
1321 depends on NUMA && X86_32
1323 config ARCH_SPARSEMEM_ENABLE
1325 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1326 select SPARSEMEM_STATIC if X86_32
1327 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1329 config ARCH_SPARSEMEM_DEFAULT
1333 config ARCH_SELECT_MEMORY_MODEL
1335 depends on ARCH_SPARSEMEM_ENABLE
1337 config ARCH_MEMORY_PROBE
1339 depends on X86_64 && MEMORY_HOTPLUG
1341 config ARCH_PROC_KCORE_TEXT
1343 depends on X86_64 && PROC_KCORE
1345 config ILLEGAL_POINTER_VALUE
1348 default 0xdead000000000000 if X86_64
1353 bool "Allocate 3rd-level pagetables from highmem"
1356 The VM uses one page table entry for each page of physical memory.
1357 For systems with a lot of RAM, this can be wasteful of precious
1358 low memory. Setting this option will put user-space page table
1359 entries in high memory.
1361 config X86_CHECK_BIOS_CORRUPTION
1362 bool "Check for low memory corruption"
1364 Periodically check for memory corruption in low memory, which
1365 is suspected to be caused by BIOS. Even when enabled in the
1366 configuration, it is disabled at runtime. Enable it by
1367 setting "memory_corruption_check=1" on the kernel command
1368 line. By default it scans the low 64k of memory every 60
1369 seconds; see the memory_corruption_check_size and
1370 memory_corruption_check_period parameters in
1371 Documentation/kernel-parameters.txt to adjust this.
1373 When enabled with the default parameters, this option has
1374 almost no overhead, as it reserves a relatively small amount
1375 of memory and scans it infrequently. It both detects corruption
1376 and prevents it from affecting the running system.
1378 It is, however, intended as a diagnostic tool; if repeatable
1379 BIOS-originated corruption always affects the same memory,
1380 you can use memmap= to prevent the kernel from using that
1383 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1384 bool "Set the default setting of memory_corruption_check"
1385 depends on X86_CHECK_BIOS_CORRUPTION
1388 Set whether the default state of memory_corruption_check is
1391 config X86_RESERVE_LOW
1392 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1396 Specify the amount of low memory to reserve for the BIOS.
1398 The first page contains BIOS data structures that the kernel
1399 must not use, so that page must always be reserved.
1401 By default we reserve the first 64K of physical RAM, as a
1402 number of BIOSes are known to corrupt that memory range
1403 during events such as suspend/resume or monitor cable
1404 insertion, so it must not be used by the kernel.
1406 You can set this to 4 if you are absolutely sure that you
1407 trust the BIOS to get all its memory reservations and usages
1408 right. If you know your BIOS have problems beyond the
1409 default 64K area, you can set this to 640 to avoid using the
1410 entire low memory range.
1412 If you have doubts about the BIOS (e.g. suspend/resume does
1413 not work or there's kernel crashes after certain hardware
1414 hotplug events) then you might want to enable
1415 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1416 typical corruption patterns.
1418 Leave this to the default value of 64 if you are unsure.
1420 config MATH_EMULATION
1422 prompt "Math emulation" if X86_32
1424 Linux can emulate a math coprocessor (used for floating point
1425 operations) if you don't have one. 486DX and Pentium processors have
1426 a math coprocessor built in, 486SX and 386 do not, unless you added
1427 a 487DX or 387, respectively. (The messages during boot time can
1428 give you some hints here ["man dmesg"].) Everyone needs either a
1429 coprocessor or this emulation.
1431 If you don't have a math coprocessor, you need to say Y here; if you
1432 say Y here even though you have a coprocessor, the coprocessor will
1433 be used nevertheless. (This behavior can be changed with the kernel
1434 command line option "no387", which comes handy if your coprocessor
1435 is broken. Try "man bootparam" or see the documentation of your boot
1436 loader (lilo or loadlin) about how to pass options to the kernel at
1437 boot time.) This means that it is a good idea to say Y here if you
1438 intend to use this kernel on different machines.
1440 More information about the internals of the Linux math coprocessor
1441 emulation can be found in <file:arch/x86/math-emu/README>.
1443 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1444 kernel, it won't hurt.
1448 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1450 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1451 the Memory Type Range Registers (MTRRs) may be used to control
1452 processor access to memory ranges. This is most useful if you have
1453 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1454 allows bus write transfers to be combined into a larger transfer
1455 before bursting over the PCI/AGP bus. This can increase performance
1456 of image write operations 2.5 times or more. Saying Y here creates a
1457 /proc/mtrr file which may be used to manipulate your processor's
1458 MTRRs. Typically the X server should use this.
1460 This code has a reasonably generic interface so that similar
1461 control registers on other processors can be easily supported
1464 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1465 Registers (ARRs) which provide a similar functionality to MTRRs. For
1466 these, the ARRs are used to emulate the MTRRs.
1467 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1468 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1469 write-combining. All of these processors are supported by this code
1470 and it makes sense to say Y here if you have one of them.
1472 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1473 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1474 can lead to all sorts of problems, so it's good to say Y here.
1476 You can safely say Y even if your machine doesn't have MTRRs, you'll
1477 just add about 9 KB to your kernel.
1479 See <file:Documentation/x86/mtrr.txt> for more information.
1481 config MTRR_SANITIZER
1483 prompt "MTRR cleanup support"
1486 Convert MTRR layout from continuous to discrete, so X drivers can
1487 add writeback entries.
1489 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1490 The largest mtrr entry size for a continuous block can be set with
1495 config MTRR_SANITIZER_ENABLE_DEFAULT
1496 int "MTRR cleanup enable value (0-1)"
1499 depends on MTRR_SANITIZER
1501 Enable mtrr cleanup default value
1503 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1504 int "MTRR cleanup spare reg num (0-7)"
1507 depends on MTRR_SANITIZER
1509 mtrr cleanup spare entries default, it can be changed via
1510 mtrr_spare_reg_nr=N on the kernel command line.
1514 prompt "x86 PAT support" if EXPERT
1517 Use PAT attributes to setup page level cache control.
1519 PATs are the modern equivalents of MTRRs and are much more
1520 flexible than MTRRs.
1522 Say N here if you see bootup problems (boot crash, boot hang,
1523 spontaneous reboots) or a non-working video driver.
1527 config ARCH_USES_PG_UNCACHED
1533 prompt "x86 architectural random number generator" if EXPERT
1535 Enable the x86 architectural RDRAND instruction
1536 (Intel Bull Mountain technology) to generate random numbers.
1537 If supported, this is a high bandwidth, cryptographically
1538 secure hardware random number generator.
1542 prompt "Supervisor Mode Access Prevention" if EXPERT
1544 Supervisor Mode Access Prevention (SMAP) is a security
1545 feature in newer Intel processors. There is a small
1546 performance cost if this enabled and turned on; there is
1547 also a small increase in the kernel size if this is enabled.
1552 bool "EFI runtime service support"
1556 This enables the kernel to use EFI runtime services that are
1557 available (such as the EFI variable services).
1559 This option is only useful on systems that have EFI firmware.
1560 In addition, you should use the latest ELILO loader available
1561 at <http://elilo.sourceforge.net> in order to take advantage
1562 of EFI runtime services. However, even with this option, the
1563 resultant kernel should continue to boot on existing non-EFI
1567 bool "EFI stub support"
1570 This kernel feature allows a bzImage to be loaded directly
1571 by EFI firmware without the use of a bootloader.
1573 See Documentation/x86/efi-stub.txt for more information.
1577 prompt "Enable seccomp to safely compute untrusted bytecode"
1579 This kernel feature is useful for number crunching applications
1580 that may need to compute untrusted bytecode during their
1581 execution. By using pipes or other transports made available to
1582 the process as file descriptors supporting the read/write
1583 syscalls, it's possible to isolate those applications in
1584 their own address space using seccomp. Once seccomp is
1585 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1586 and the task is only allowed to execute a few safe syscalls
1587 defined by each seccomp mode.
1589 If unsure, say Y. Only embedded should say N here.
1591 config CC_STACKPROTECTOR
1592 bool "Enable -fstack-protector buffer overflow detection"
1594 This option turns on the -fstack-protector GCC feature. This
1595 feature puts, at the beginning of functions, a canary value on
1596 the stack just before the return address, and validates
1597 the value just before actually returning. Stack based buffer
1598 overflows (that need to overwrite this return address) now also
1599 overwrite the canary, which gets detected and the attack is then
1600 neutralized via a kernel panic.
1602 This feature requires gcc version 4.2 or above, or a distribution
1603 gcc with the feature backported. Older versions are automatically
1604 detected and for those versions, this configuration option is
1605 ignored. (and a warning is printed during bootup)
1607 source kernel/Kconfig.hz
1610 bool "kexec system call"
1612 kexec is a system call that implements the ability to shutdown your
1613 current kernel, and to start another kernel. It is like a reboot
1614 but it is independent of the system firmware. And like a reboot
1615 you can start any kernel with it, not just Linux.
1617 The name comes from the similarity to the exec system call.
1619 It is an ongoing process to be certain the hardware in a machine
1620 is properly shutdown, so do not be surprised if this code does not
1621 initially work for you. It may help to enable device hotplugging
1622 support. As of this writing the exact hardware interface is
1623 strongly in flux, so no good recommendation can be made.
1626 bool "kernel crash dumps"
1627 depends on X86_64 || (X86_32 && HIGHMEM)
1629 Generate crash dump after being started by kexec.
1630 This should be normally only set in special crash dump kernels
1631 which are loaded in the main kernel with kexec-tools into
1632 a specially reserved region and then later executed after
1633 a crash by kdump/kexec. The crash dump kernel must be compiled
1634 to a memory address not used by the main kernel or BIOS using
1635 PHYSICAL_START, or it must be built as a relocatable image
1636 (CONFIG_RELOCATABLE=y).
1637 For more details see Documentation/kdump/kdump.txt
1641 depends on KEXEC && HIBERNATION
1643 Jump between original kernel and kexeced kernel and invoke
1644 code in physical address mode via KEXEC
1646 config PHYSICAL_START
1647 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1650 This gives the physical address where the kernel is loaded.
1652 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1653 bzImage will decompress itself to above physical address and
1654 run from there. Otherwise, bzImage will run from the address where
1655 it has been loaded by the boot loader and will ignore above physical
1658 In normal kdump cases one does not have to set/change this option
1659 as now bzImage can be compiled as a completely relocatable image
1660 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1661 address. This option is mainly useful for the folks who don't want
1662 to use a bzImage for capturing the crash dump and want to use a
1663 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1664 to be specifically compiled to run from a specific memory area
1665 (normally a reserved region) and this option comes handy.
1667 So if you are using bzImage for capturing the crash dump,
1668 leave the value here unchanged to 0x1000000 and set
1669 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1670 for capturing the crash dump change this value to start of
1671 the reserved region. In other words, it can be set based on
1672 the "X" value as specified in the "crashkernel=YM@XM"
1673 command line boot parameter passed to the panic-ed
1674 kernel. Please take a look at Documentation/kdump/kdump.txt
1675 for more details about crash dumps.
1677 Usage of bzImage for capturing the crash dump is recommended as
1678 one does not have to build two kernels. Same kernel can be used
1679 as production kernel and capture kernel. Above option should have
1680 gone away after relocatable bzImage support is introduced. But it
1681 is present because there are users out there who continue to use
1682 vmlinux for dump capture. This option should go away down the
1685 Don't change this unless you know what you are doing.
1688 bool "Build a relocatable kernel"
1691 This builds a kernel image that retains relocation information
1692 so it can be loaded someplace besides the default 1MB.
1693 The relocations tend to make the kernel binary about 10% larger,
1694 but are discarded at runtime.
1696 One use is for the kexec on panic case where the recovery kernel
1697 must live at a different physical address than the primary
1700 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1701 it has been loaded at and the compile time physical address
1702 (CONFIG_PHYSICAL_START) is ignored.
1704 # Relocation on x86-32 needs some additional build support
1705 config X86_NEED_RELOCS
1707 depends on X86_32 && RELOCATABLE
1709 config PHYSICAL_ALIGN
1710 hex "Alignment value to which kernel should be aligned" if X86_32
1712 range 0x2000 0x1000000
1714 This value puts the alignment restrictions on physical address
1715 where kernel is loaded and run from. Kernel is compiled for an
1716 address which meets above alignment restriction.
1718 If bootloader loads the kernel at a non-aligned address and
1719 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1720 address aligned to above value and run from there.
1722 If bootloader loads the kernel at a non-aligned address and
1723 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1724 load address and decompress itself to the address it has been
1725 compiled for and run from there. The address for which kernel is
1726 compiled already meets above alignment restrictions. Hence the
1727 end result is that kernel runs from a physical address meeting
1728 above alignment restrictions.
1730 Don't change this unless you know what you are doing.
1733 bool "Support for hot-pluggable CPUs"
1736 Say Y here to allow turning CPUs off and on. CPUs can be
1737 controlled through /sys/devices/system/cpu.
1738 ( Note: power management support will enable this option
1739 automatically on SMP systems. )
1740 Say N if you want to disable CPU hotplug.
1742 config BOOTPARAM_HOTPLUG_CPU0
1743 bool "Set default setting of cpu0_hotpluggable"
1745 depends on HOTPLUG_CPU
1747 Set whether default state of cpu0_hotpluggable is on or off.
1749 Say Y here to enable CPU0 hotplug by default. If this switch
1750 is turned on, there is no need to give cpu0_hotplug kernel
1751 parameter and the CPU0 hotplug feature is enabled by default.
1753 Please note: there are two known CPU0 dependencies if you want
1754 to enable the CPU0 hotplug feature either by this switch or by
1755 cpu0_hotplug kernel parameter.
1757 First, resume from hibernate or suspend always starts from CPU0.
1758 So hibernate and suspend are prevented if CPU0 is offline.
1760 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1761 offline if any interrupt can not migrate out of CPU0. There may
1762 be other CPU0 dependencies.
1764 Please make sure the dependencies are under your control before
1765 you enable this feature.
1767 Say N if you don't want to enable CPU0 hotplug feature by default.
1768 You still can enable the CPU0 hotplug feature at boot by kernel
1769 parameter cpu0_hotplug.
1771 config DEBUG_HOTPLUG_CPU0
1773 prompt "Debug CPU0 hotplug"
1774 depends on HOTPLUG_CPU
1776 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1777 soon as possible and boots up userspace with CPU0 offlined. User
1778 can online CPU0 back after boot time.
1780 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1781 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1782 compilation or giving cpu0_hotplug kernel parameter at boot.
1788 prompt "Compat VDSO support"
1789 depends on X86_32 || IA32_EMULATION
1791 Map the 32-bit VDSO to the predictable old-style address too.
1793 Say N here if you are running a sufficiently recent glibc
1794 version (2.3.3 or later), to remove the high-mapped
1795 VDSO mapping and to exclusively use the randomized VDSO.
1800 bool "Built-in kernel command line"
1802 Allow for specifying boot arguments to the kernel at
1803 build time. On some systems (e.g. embedded ones), it is
1804 necessary or convenient to provide some or all of the
1805 kernel boot arguments with the kernel itself (that is,
1806 to not rely on the boot loader to provide them.)
1808 To compile command line arguments into the kernel,
1809 set this option to 'Y', then fill in the
1810 the boot arguments in CONFIG_CMDLINE.
1812 Systems with fully functional boot loaders (i.e. non-embedded)
1813 should leave this option set to 'N'.
1816 string "Built-in kernel command string"
1817 depends on CMDLINE_BOOL
1820 Enter arguments here that should be compiled into the kernel
1821 image and used at boot time. If the boot loader provides a
1822 command line at boot time, it is appended to this string to
1823 form the full kernel command line, when the system boots.
1825 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1826 change this behavior.
1828 In most cases, the command line (whether built-in or provided
1829 by the boot loader) should specify the device for the root
1832 config CMDLINE_OVERRIDE
1833 bool "Built-in command line overrides boot loader arguments"
1834 depends on CMDLINE_BOOL
1836 Set this option to 'Y' to have the kernel ignore the boot loader
1837 command line, and use ONLY the built-in command line.
1839 This is used to work around broken boot loaders. This should
1840 be set to 'N' under normal conditions.
1844 config ARCH_ENABLE_MEMORY_HOTPLUG
1846 depends on X86_64 || (X86_32 && HIGHMEM)
1848 config ARCH_ENABLE_MEMORY_HOTREMOVE
1850 depends on MEMORY_HOTPLUG
1852 config USE_PERCPU_NUMA_NODE_ID
1856 menu "Power management and ACPI options"
1858 config ARCH_HIBERNATION_HEADER
1860 depends on X86_64 && HIBERNATION
1862 source "kernel/power/Kconfig"
1864 source "drivers/acpi/Kconfig"
1866 source "drivers/sfi/Kconfig"
1873 tristate "APM (Advanced Power Management) BIOS support"
1874 depends on X86_32 && PM_SLEEP
1876 APM is a BIOS specification for saving power using several different
1877 techniques. This is mostly useful for battery powered laptops with
1878 APM compliant BIOSes. If you say Y here, the system time will be
1879 reset after a RESUME operation, the /proc/apm device will provide
1880 battery status information, and user-space programs will receive
1881 notification of APM "events" (e.g. battery status change).
1883 If you select "Y" here, you can disable actual use of the APM
1884 BIOS by passing the "apm=off" option to the kernel at boot time.
1886 Note that the APM support is almost completely disabled for
1887 machines with more than one CPU.
1889 In order to use APM, you will need supporting software. For location
1890 and more information, read <file:Documentation/power/apm-acpi.txt>
1891 and the Battery Powered Linux mini-HOWTO, available from
1892 <http://www.tldp.org/docs.html#howto>.
1894 This driver does not spin down disk drives (see the hdparm(8)
1895 manpage ("man 8 hdparm") for that), and it doesn't turn off
1896 VESA-compliant "green" monitors.
1898 This driver does not support the TI 4000M TravelMate and the ACER
1899 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1900 desktop machines also don't have compliant BIOSes, and this driver
1901 may cause those machines to panic during the boot phase.
1903 Generally, if you don't have a battery in your machine, there isn't
1904 much point in using this driver and you should say N. If you get
1905 random kernel OOPSes or reboots that don't seem to be related to
1906 anything, try disabling/enabling this option (or disabling/enabling
1909 Some other things you should try when experiencing seemingly random,
1912 1) make sure that you have enough swap space and that it is
1914 2) pass the "no-hlt" option to the kernel
1915 3) switch on floating point emulation in the kernel and pass
1916 the "no387" option to the kernel
1917 4) pass the "floppy=nodma" option to the kernel
1918 5) pass the "mem=4M" option to the kernel (thereby disabling
1919 all but the first 4 MB of RAM)
1920 6) make sure that the CPU is not over clocked.
1921 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1922 8) disable the cache from your BIOS settings
1923 9) install a fan for the video card or exchange video RAM
1924 10) install a better fan for the CPU
1925 11) exchange RAM chips
1926 12) exchange the motherboard.
1928 To compile this driver as a module, choose M here: the
1929 module will be called apm.
1933 config APM_IGNORE_USER_SUSPEND
1934 bool "Ignore USER SUSPEND"
1936 This option will ignore USER SUSPEND requests. On machines with a
1937 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1938 series notebooks, it is necessary to say Y because of a BIOS bug.
1940 config APM_DO_ENABLE
1941 bool "Enable PM at boot time"
1943 Enable APM features at boot time. From page 36 of the APM BIOS
1944 specification: "When disabled, the APM BIOS does not automatically
1945 power manage devices, enter the Standby State, enter the Suspend
1946 State, or take power saving steps in response to CPU Idle calls."
1947 This driver will make CPU Idle calls when Linux is idle (unless this
1948 feature is turned off -- see "Do CPU IDLE calls", below). This
1949 should always save battery power, but more complicated APM features
1950 will be dependent on your BIOS implementation. You may need to turn
1951 this option off if your computer hangs at boot time when using APM
1952 support, or if it beeps continuously instead of suspending. Turn
1953 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1954 T400CDT. This is off by default since most machines do fine without
1959 bool "Make CPU Idle calls when idle"
1961 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1962 On some machines, this can activate improved power savings, such as
1963 a slowed CPU clock rate, when the machine is idle. These idle calls
1964 are made after the idle loop has run for some length of time (e.g.,
1965 333 mS). On some machines, this will cause a hang at boot time or
1966 whenever the CPU becomes idle. (On machines with more than one CPU,
1967 this option does nothing.)
1969 config APM_DISPLAY_BLANK
1970 bool "Enable console blanking using APM"
1972 Enable console blanking using the APM. Some laptops can use this to
1973 turn off the LCD backlight when the screen blanker of the Linux
1974 virtual console blanks the screen. Note that this is only used by
1975 the virtual console screen blanker, and won't turn off the backlight
1976 when using the X Window system. This also doesn't have anything to
1977 do with your VESA-compliant power-saving monitor. Further, this
1978 option doesn't work for all laptops -- it might not turn off your
1979 backlight at all, or it might print a lot of errors to the console,
1980 especially if you are using gpm.
1982 config APM_ALLOW_INTS
1983 bool "Allow interrupts during APM BIOS calls"
1985 Normally we disable external interrupts while we are making calls to
1986 the APM BIOS as a measure to lessen the effects of a badly behaving
1987 BIOS implementation. The BIOS should reenable interrupts if it
1988 needs to. Unfortunately, some BIOSes do not -- especially those in
1989 many of the newer IBM Thinkpads. If you experience hangs when you
1990 suspend, try setting this to Y. Otherwise, say N.
1994 source "drivers/cpufreq/Kconfig"
1996 source "drivers/cpuidle/Kconfig"
1998 source "drivers/idle/Kconfig"
2003 menu "Bus options (PCI etc.)"
2008 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2010 Find out whether you have a PCI motherboard. PCI is the name of a
2011 bus system, i.e. the way the CPU talks to the other stuff inside
2012 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2013 VESA. If you have PCI, say Y, otherwise N.
2016 prompt "PCI access mode"
2017 depends on X86_32 && PCI
2020 On PCI systems, the BIOS can be used to detect the PCI devices and
2021 determine their configuration. However, some old PCI motherboards
2022 have BIOS bugs and may crash if this is done. Also, some embedded
2023 PCI-based systems don't have any BIOS at all. Linux can also try to
2024 detect the PCI hardware directly without using the BIOS.
2026 With this option, you can specify how Linux should detect the
2027 PCI devices. If you choose "BIOS", the BIOS will be used,
2028 if you choose "Direct", the BIOS won't be used, and if you
2029 choose "MMConfig", then PCI Express MMCONFIG will be used.
2030 If you choose "Any", the kernel will try MMCONFIG, then the
2031 direct access method and falls back to the BIOS if that doesn't
2032 work. If unsure, go with the default, which is "Any".
2037 config PCI_GOMMCONFIG
2054 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2056 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2059 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2063 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2067 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2071 depends on PCI && XEN
2079 bool "Support mmconfig PCI config space access"
2080 depends on X86_64 && PCI && ACPI
2082 config PCI_CNB20LE_QUIRK
2083 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2086 Read the PCI windows out of the CNB20LE host bridge. This allows
2087 PCI hotplug to work on systems with the CNB20LE chipset which do
2090 There's no public spec for this chipset, and this functionality
2091 is known to be incomplete.
2093 You should say N unless you know you need this.
2095 source "drivers/pci/pcie/Kconfig"
2097 source "drivers/pci/Kconfig"
2099 # x86_64 have no ISA slots, but can have ISA-style DMA.
2101 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2104 Enables ISA-style DMA support for devices requiring such controllers.
2112 Find out whether you have ISA slots on your motherboard. ISA is the
2113 name of a bus system, i.e. the way the CPU talks to the other stuff
2114 inside your box. Other bus systems are PCI, EISA, MicroChannel
2115 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2116 newer boards don't support it. If you have ISA, say Y, otherwise N.
2122 The Extended Industry Standard Architecture (EISA) bus was
2123 developed as an open alternative to the IBM MicroChannel bus.
2125 The EISA bus provided some of the features of the IBM MicroChannel
2126 bus while maintaining backward compatibility with cards made for
2127 the older ISA bus. The EISA bus saw limited use between 1988 and
2128 1995 when it was made obsolete by the PCI bus.
2130 Say Y here if you are building a kernel for an EISA-based machine.
2134 source "drivers/eisa/Kconfig"
2137 tristate "NatSemi SCx200 support"
2139 This provides basic support for National Semiconductor's
2140 (now AMD's) Geode processors. The driver probes for the
2141 PCI-IDs of several on-chip devices, so its a good dependency
2142 for other scx200_* drivers.
2144 If compiled as a module, the driver is named scx200.
2146 config SCx200HR_TIMER
2147 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2151 This driver provides a clocksource built upon the on-chip
2152 27MHz high-resolution timer. Its also a workaround for
2153 NSC Geode SC-1100's buggy TSC, which loses time when the
2154 processor goes idle (as is done by the scheduler). The
2155 other workaround is idle=poll boot option.
2158 bool "One Laptop Per Child support"
2165 Add support for detecting the unique features of the OLPC
2169 bool "OLPC XO-1 Power Management"
2170 depends on OLPC && MFD_CS5535 && PM_SLEEP
2173 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2176 bool "OLPC XO-1 Real Time Clock"
2177 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2179 Add support for the XO-1 real time clock, which can be used as a
2180 programmable wakeup source.
2183 bool "OLPC XO-1 SCI extras"
2184 depends on OLPC && OLPC_XO1_PM
2190 Add support for SCI-based features of the OLPC XO-1 laptop:
2191 - EC-driven system wakeups
2195 - AC adapter status updates
2196 - Battery status updates
2198 config OLPC_XO15_SCI
2199 bool "OLPC XO-1.5 SCI extras"
2200 depends on OLPC && ACPI
2203 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2204 - EC-driven system wakeups
2205 - AC adapter status updates
2206 - Battery status updates
2209 bool "PCEngines ALIX System Support (LED setup)"
2212 This option enables system support for the PCEngines ALIX.
2213 At present this just sets up LEDs for GPIO control on
2214 ALIX2/3/6 boards. However, other system specific setup should
2217 Note: You must still enable the drivers for GPIO and LED support
2218 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2220 Note: You have to set alix.force=1 for boards with Award BIOS.
2223 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2226 This option enables system support for the Soekris Engineering net5501.
2229 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2233 This option enables system support for the Traverse Technologies GEOS.
2236 bool "Technologic Systems TS-5500 platform support"
2238 select CHECK_SIGNATURE
2242 This option enables system support for the Technologic Systems TS-5500.
2248 depends on CPU_SUP_AMD && PCI
2250 source "drivers/pcmcia/Kconfig"
2252 source "drivers/pci/hotplug/Kconfig"
2255 bool "RapidIO support"
2259 If you say Y here, the kernel will include drivers and
2260 infrastructure code to support RapidIO interconnect devices.
2262 source "drivers/rapidio/Kconfig"
2267 menu "Executable file formats / Emulations"
2269 source "fs/Kconfig.binfmt"
2271 config IA32_EMULATION
2272 bool "IA32 Emulation"
2275 select COMPAT_BINFMT_ELF
2278 Include code to run legacy 32-bit programs under a
2279 64-bit kernel. You should likely turn this on, unless you're
2280 100% sure that you don't have any 32-bit programs left.
2283 tristate "IA32 a.out support"
2284 depends on IA32_EMULATION
2286 Support old a.out binaries in the 32bit emulation.
2289 bool "x32 ABI for 64-bit mode"
2290 depends on X86_64 && IA32_EMULATION
2292 Include code to run binaries for the x32 native 32-bit ABI
2293 for 64-bit processors. An x32 process gets access to the
2294 full 64-bit register file and wide data path while leaving
2295 pointers at 32 bits for smaller memory footprint.
2297 You will need a recent binutils (2.22 or later) with
2298 elf32_x86_64 support enabled to compile a kernel with this
2303 depends on IA32_EMULATION || X86_X32
2304 select ARCH_WANT_OLD_COMPAT_IPC
2307 config COMPAT_FOR_U64_ALIGNMENT
2310 config SYSVIPC_COMPAT
2322 config HAVE_ATOMIC_IOMAP
2326 config HAVE_TEXT_POKE_SMP
2328 select STOP_MACHINE if SMP
2330 config X86_DEV_DMA_OPS
2332 depends on X86_64 || STA2X11
2334 config X86_DMA_REMAP
2338 source "net/Kconfig"
2340 source "drivers/Kconfig"
2342 source "drivers/firmware/Kconfig"
2346 source "arch/x86/Kconfig.debug"
2348 source "security/Kconfig"
2350 source "crypto/Kconfig"
2352 source "arch/x86/kvm/Kconfig"
2354 source "lib/Kconfig"