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 HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
25 select ARCH_SUPPORTS_NUMA_BALANCING
26 select ARCH_WANTS_PROT_NUMA_PROT_NONE
29 select HAVE_PCSPKR_PLATFORM
30 select HAVE_PERF_EVENTS
31 select HAVE_IOREMAP_PROT
34 select HAVE_MEMBLOCK_NODE_MAP
35 select ARCH_DISCARD_MEMBLOCK
36 select ARCH_WANT_OPTIONAL_GPIOLIB
37 select ARCH_WANT_FRAME_POINTERS
39 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
40 select HAVE_KRETPROBES
42 select HAVE_KPROBES_ON_FTRACE
43 select HAVE_FTRACE_MCOUNT_RECORD
44 select HAVE_FENTRY if X86_64
45 select HAVE_C_RECORDMCOUNT
46 select HAVE_DYNAMIC_FTRACE
47 select HAVE_DYNAMIC_FTRACE_WITH_REGS
48 select HAVE_FUNCTION_TRACER
49 select HAVE_FUNCTION_GRAPH_TRACER
50 select HAVE_FUNCTION_GRAPH_FP_TEST
51 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
52 select HAVE_SYSCALL_TRACEPOINTS
53 select SYSCTL_EXCEPTION_TRACE
56 select HAVE_ARCH_TRACEHOOK
57 select HAVE_GENERIC_DMA_COHERENT if X86_32
58 select HAVE_EFFICIENT_UNALIGNED_ACCESS
59 select USER_STACKTRACE_SUPPORT
60 select HAVE_REGS_AND_STACK_ACCESS_API
61 select HAVE_DMA_API_DEBUG
62 select HAVE_KERNEL_GZIP
63 select HAVE_KERNEL_BZIP2
64 select HAVE_KERNEL_LZMA
66 select HAVE_KERNEL_LZO
67 select HAVE_HW_BREAKPOINT
68 select HAVE_MIXED_BREAKPOINTS_REGS
70 select HAVE_PERF_EVENTS_NMI
72 select HAVE_PERF_USER_STACK_DUMP
73 select HAVE_DEBUG_KMEMLEAK
75 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
76 select HAVE_CMPXCHG_LOCAL
77 select HAVE_CMPXCHG_DOUBLE
78 select HAVE_ARCH_KMEMCHECK
79 select HAVE_USER_RETURN_NOTIFIER
80 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
81 select HAVE_ARCH_JUMP_LABEL
82 select HAVE_TEXT_POKE_SMP
83 select HAVE_GENERIC_HARDIRQS
84 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
86 select GENERIC_FIND_FIRST_BIT
87 select GENERIC_IRQ_PROBE
88 select GENERIC_PENDING_IRQ if SMP
89 select GENERIC_IRQ_SHOW
90 select GENERIC_CLOCKEVENTS_MIN_ADJUST
91 select IRQ_FORCED_THREADING
92 select USE_GENERIC_SMP_HELPERS if SMP
93 select HAVE_BPF_JIT if X86_64
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
96 select ARCH_HAVE_NMI_SAFE_CMPXCHG
98 select DCACHE_WORD_ACCESS
99 select GENERIC_SMP_IDLE_THREAD
100 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
101 select HAVE_ARCH_SECCOMP_FILTER
102 select BUILDTIME_EXTABLE_SORT
103 select GENERIC_CMOS_UPDATE
104 select CLOCKSOURCE_WATCHDOG
105 select GENERIC_CLOCKEVENTS
106 select ARCH_CLOCKSOURCE_DATA if X86_64
107 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
108 select GENERIC_TIME_VSYSCALL if X86_64
109 select KTIME_SCALAR if X86_32
110 select ALWAYS_USE_PERSISTENT_CLOCK
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
115 select MODULES_USE_ELF_REL if X86_32
116 select MODULES_USE_ELF_RELA if X86_64
117 select CLONE_BACKWARDS if X86_32
118 select GENERIC_SIGALTSTACK
119 select ARCH_USE_BUILTIN_BSWAP
121 config INSTRUCTION_DECODER
123 depends on KPROBES || PERF_EVENTS || UPROBES
127 default "elf32-i386" if X86_32
128 default "elf64-x86-64" if X86_64
130 config ARCH_DEFCONFIG
132 default "arch/x86/configs/i386_defconfig" if X86_32
133 default "arch/x86/configs/x86_64_defconfig" if X86_64
135 config LOCKDEP_SUPPORT
138 config STACKTRACE_SUPPORT
141 config HAVE_LATENCYTOP_SUPPORT
150 config NEED_DMA_MAP_STATE
152 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
154 config NEED_SG_DMA_LENGTH
157 config GENERIC_ISA_DMA
159 depends on ISA_DMA_API
164 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
166 config GENERIC_BUG_RELATIVE_POINTERS
169 config GENERIC_HWEIGHT
175 config ARCH_MAY_HAVE_PC_FDC
177 depends on ISA_DMA_API
179 config RWSEM_XCHGADD_ALGORITHM
182 config GENERIC_CALIBRATE_DELAY
185 config ARCH_HAS_CPU_RELAX
188 config ARCH_HAS_DEFAULT_IDLE
191 config ARCH_HAS_CACHE_LINE_SIZE
194 config ARCH_HAS_CPU_AUTOPROBE
197 config HAVE_SETUP_PER_CPU_AREA
200 config NEED_PER_CPU_EMBED_FIRST_CHUNK
203 config NEED_PER_CPU_PAGE_FIRST_CHUNK
206 config ARCH_HIBERNATION_POSSIBLE
209 config ARCH_SUSPEND_POSSIBLE
220 config ARCH_SUPPORTS_OPTIMIZED_INLINING
223 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
226 config HAVE_INTEL_TXT
228 depends on EXPERIMENTAL && INTEL_IOMMU && ACPI
232 depends on X86_32 && SMP
236 depends on X86_64 && SMP
242 config X86_32_LAZY_GS
244 depends on X86_32 && !CC_STACKPROTECTOR
246 config ARCH_HWEIGHT_CFLAGS
248 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
249 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
251 config ARCH_CPU_PROBE_RELEASE
253 depends on HOTPLUG_CPU
255 config ARCH_SUPPORTS_UPROBES
258 source "init/Kconfig"
259 source "kernel/Kconfig.freezer"
261 menu "Processor type and features"
264 bool "DMA memory allocation support" if EXPERT
267 DMA memory allocation support allows devices with less than 32-bit
268 addressing to allocate within the first 16MB of address space.
269 Disable if no such devices will be used.
274 bool "Symmetric multi-processing support"
276 This enables support for systems with more than one CPU. If you have
277 a system with only one CPU, like most personal computers, say N. If
278 you have a system with more than one CPU, say Y.
280 If you say N here, the kernel will run on single and multiprocessor
281 machines, but will use only one CPU of a multiprocessor machine. If
282 you say Y here, the kernel will run on many, but not all,
283 singleprocessor machines. On a singleprocessor machine, the kernel
284 will run faster if you say N here.
286 Note that if you say Y here and choose architecture "586" or
287 "Pentium" under "Processor family", the kernel will not work on 486
288 architectures. Similarly, multiprocessor kernels for the "PPro"
289 architecture may not work on all Pentium based boards.
291 People using multiprocessor machines who say Y here should also say
292 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
293 Management" code will be disabled if you say Y here.
295 See also <file:Documentation/x86/i386/IO-APIC.txt>,
296 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
297 <http://www.tldp.org/docs.html#howto>.
299 If you don't know what to do here, say N.
302 bool "Support x2apic"
303 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
305 This enables x2apic support on CPUs that have this feature.
307 This allows 32-bit apic IDs (so it can support very large systems),
308 and accesses the local apic via MSRs not via mmio.
310 If you don't know what to do here, say N.
313 bool "Enable MPS table" if ACPI || SFI
315 depends on X86_LOCAL_APIC
317 For old smp systems that do not have proper acpi support. Newer systems
318 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
321 bool "Support for big SMP systems with more than 8 CPUs"
322 depends on X86_32 && SMP
324 This option is needed for the systems that have more than 8 CPUs
328 depends on X86_GOLDFISH
331 config X86_EXTENDED_PLATFORM
332 bool "Support for extended (non-PC) x86 platforms"
335 If you disable this option then the kernel will only support
336 standard PC platforms. (which covers the vast majority of
339 If you enable this option then you'll be able to select support
340 for the following (non-PC) 32 bit x86 platforms:
344 SGI 320/540 (Visual Workstation)
345 STA2X11-based (e.g. Northville)
346 Summit/EXA (IBM x440)
347 Unisys ES7000 IA32 series
348 Moorestown MID devices
350 If you have one of these systems, or if you want to build a
351 generic distribution kernel, say Y here - otherwise say N.
355 config X86_EXTENDED_PLATFORM
356 bool "Support for extended (non-PC) x86 platforms"
359 If you disable this option then the kernel will only support
360 standard PC platforms. (which covers the vast majority of
363 If you enable this option then you'll be able to select support
364 for the following (non-PC) 64 bit x86 platforms:
369 If you have one of these systems, or if you want to build a
370 generic distribution kernel, say Y here - otherwise say N.
372 # This is an alphabetically sorted list of 64 bit extended platforms
373 # Please maintain the alphabetic order if and when there are additions
375 bool "Numascale NumaChip"
377 depends on X86_EXTENDED_PLATFORM
380 depends on X86_X2APIC
381 depends on PCI_MMCONFIG
383 Adds support for Numascale NumaChip large-SMP systems. Needed to
384 enable more than ~168 cores.
385 If you don't have one of these, you should say N here.
389 select PARAVIRT_GUEST
391 depends on X86_64 && PCI
392 depends on X86_EXTENDED_PLATFORM
395 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
396 supposed to run on these EM64T-based machines. Only choose this option
397 if you have one of these machines.
400 bool "SGI Ultraviolet"
402 depends on X86_EXTENDED_PLATFORM
404 depends on X86_X2APIC
406 This option is needed in order to support SGI Ultraviolet systems.
407 If you don't have one of these, you should say N here.
409 # Following is an alphabetically sorted list of 32 bit extended platforms
410 # Please maintain the alphabetic order if and when there are additions
413 bool "Goldfish (Virtual 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 PARAVIRT_GUEST
597 bool "Paravirtualized guest support"
599 Say Y here to get to see options related to running Linux under
600 various hypervisors. This option alone does not add any kernel code.
602 If you say N, all options in this submenu will be skipped and disabled.
606 config PARAVIRT_TIME_ACCOUNTING
607 bool "Paravirtual steal time accounting"
611 Select this option to enable fine granularity task steal time
612 accounting. Time spent executing other tasks in parallel with
613 the current vCPU is discounted from the vCPU power. To account for
614 that, there can be a small performance impact.
616 If in doubt, say N here.
618 source "arch/x86/xen/Kconfig"
621 bool "KVM Guest support (including kvmclock)"
624 select PARAVIRT_CLOCK
625 default y if PARAVIRT_GUEST
627 This option enables various optimizations for running under the KVM
628 hypervisor. It includes a paravirtualized clock, so that instead
629 of relying on a PIT (or probably other) emulation by the
630 underlying device model, the host provides the guest with
631 timing infrastructure such as time of day, and system time
633 source "arch/x86/lguest/Kconfig"
636 bool "Enable paravirtualization code"
638 This changes the kernel so it can modify itself when it is run
639 under a hypervisor, potentially improving performance significantly
640 over full virtualization. However, when run without a hypervisor
641 the kernel is theoretically slower and slightly larger.
643 config PARAVIRT_SPINLOCKS
644 bool "Paravirtualization layer for spinlocks"
645 depends on PARAVIRT && SMP && EXPERIMENTAL
647 Paravirtualized spinlocks allow a pvops backend to replace the
648 spinlock implementation with something virtualization-friendly
649 (for example, block the virtual CPU rather than spinning).
651 Unfortunately the downside is an up to 5% performance hit on
652 native kernels, with various workloads.
654 If you are unsure how to answer this question, answer N.
656 config PARAVIRT_CLOCK
661 config PARAVIRT_DEBUG
662 bool "paravirt-ops debugging"
663 depends on PARAVIRT && DEBUG_KERNEL
665 Enable to debug paravirt_ops internals. Specifically, BUG if
666 a paravirt_op is missing when it is called.
674 This option adds a kernel parameter 'memtest', which allows memtest
676 memtest=0, mean disabled; -- default
677 memtest=1, mean do 1 test pattern;
679 memtest=4, mean do 4 test patterns.
680 If you are unsure how to answer this question, answer N.
682 config X86_SUMMIT_NUMA
684 depends on X86_32 && NUMA && X86_32_NON_STANDARD
686 config X86_CYCLONE_TIMER
688 depends on X86_SUMMIT
690 source "arch/x86/Kconfig.cpu"
694 prompt "HPET Timer Support" if X86_32
696 Use the IA-PC HPET (High Precision Event Timer) to manage
697 time in preference to the PIT and RTC, if a HPET is
699 HPET is the next generation timer replacing legacy 8254s.
700 The HPET provides a stable time base on SMP
701 systems, unlike the TSC, but it is more expensive to access,
702 as it is off-chip. You can find the HPET spec at
703 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
705 You can safely choose Y here. However, HPET will only be
706 activated if the platform and the BIOS support this feature.
707 Otherwise the 8254 will be used for timing services.
709 Choose N to continue using the legacy 8254 timer.
711 config HPET_EMULATE_RTC
713 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
716 def_bool y if X86_INTEL_MID
717 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
719 depends on X86_INTEL_MID && SFI
721 APB timer is the replacement for 8254, HPET on X86 MID platforms.
722 The APBT provides a stable time base on SMP
723 systems, unlike the TSC, but it is more expensive to access,
724 as it is off-chip. APB timers are always running regardless of CPU
725 C states, they are used as per CPU clockevent device when possible.
727 # Mark as expert because too many people got it wrong.
728 # The code disables itself when not needed.
731 bool "Enable DMI scanning" if EXPERT
733 Enabled scanning of DMI to identify machine quirks. Say Y
734 here unless you have verified that your setup is not
735 affected by entries in the DMI blacklist. Required by PNP
739 bool "GART IOMMU support" if EXPERT
742 depends on X86_64 && PCI && AMD_NB
744 Support for full DMA access of devices with 32bit memory access only
745 on systems with more than 3GB. This is usually needed for USB,
746 sound, many IDE/SATA chipsets and some other devices.
747 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
748 based hardware IOMMU and a software bounce buffer based IOMMU used
749 on Intel systems and as fallback.
750 The code is only active when needed (enough memory and limited
751 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
755 bool "IBM Calgary IOMMU support"
757 depends on X86_64 && PCI && EXPERIMENTAL
759 Support for hardware IOMMUs in IBM's xSeries x366 and x460
760 systems. Needed to run systems with more than 3GB of memory
761 properly with 32-bit PCI devices that do not support DAC
762 (Double Address Cycle). Calgary also supports bus level
763 isolation, where all DMAs pass through the IOMMU. This
764 prevents them from going anywhere except their intended
765 destination. This catches hard-to-find kernel bugs and
766 mis-behaving drivers and devices that do not use the DMA-API
767 properly to set up their DMA buffers. The IOMMU can be
768 turned off at boot time with the iommu=off parameter.
769 Normally the kernel will make the right choice by itself.
772 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
774 prompt "Should Calgary be enabled by default?"
775 depends on CALGARY_IOMMU
777 Should Calgary be enabled by default? if you choose 'y', Calgary
778 will be used (if it exists). If you choose 'n', Calgary will not be
779 used even if it exists. If you choose 'n' and would like to use
780 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
783 # need this always selected by IOMMU for the VIA workaround
787 Support for software bounce buffers used on x86-64 systems
788 which don't have a hardware IOMMU. Using this PCI devices
789 which can only access 32-bits of memory can be used on systems
790 with more than 3 GB of memory.
795 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
798 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
799 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
800 select CPUMASK_OFFSTACK
802 Enable maximum number of CPUS and NUMA Nodes for this architecture.
806 int "Maximum number of CPUs" if SMP && !MAXSMP
807 range 2 8 if SMP && X86_32 && !X86_BIGSMP
808 range 2 512 if SMP && !MAXSMP
810 default "4096" if MAXSMP
811 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
814 This allows you to specify the maximum number of CPUs which this
815 kernel will support. The maximum supported value is 512 and the
816 minimum value which makes sense is 2.
818 This is purely to save memory - each supported CPU adds
819 approximately eight kilobytes to the kernel image.
822 bool "SMT (Hyperthreading) scheduler support"
825 SMT scheduler support improves the CPU scheduler's decision making
826 when dealing with Intel Pentium 4 chips with HyperThreading at a
827 cost of slightly increased overhead in some places. If unsure say
832 prompt "Multi-core scheduler support"
835 Multi-core scheduler support improves the CPU scheduler's decision
836 making when dealing with multi-core CPU chips at a cost of slightly
837 increased overhead in some places. If unsure say N here.
839 source "kernel/Kconfig.preempt"
842 bool "Local APIC support on uniprocessors"
843 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
845 A local APIC (Advanced Programmable Interrupt Controller) is an
846 integrated interrupt controller in the CPU. If you have a single-CPU
847 system which has a processor with a local APIC, you can say Y here to
848 enable and use it. If you say Y here even though your machine doesn't
849 have a local APIC, then the kernel will still run with no slowdown at
850 all. The local APIC supports CPU-generated self-interrupts (timer,
851 performance counters), and the NMI watchdog which detects hard
855 bool "IO-APIC support on uniprocessors"
856 depends on X86_UP_APIC
858 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
859 SMP-capable replacement for PC-style interrupt controllers. Most
860 SMP systems and many recent uniprocessor systems have one.
862 If you have a single-CPU system with an IO-APIC, you can say Y here
863 to use it. If you say Y here even though your machine doesn't have
864 an IO-APIC, then the kernel will still run with no slowdown at all.
866 config X86_LOCAL_APIC
868 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
872 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
874 config X86_VISWS_APIC
876 depends on X86_32 && X86_VISWS
878 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
879 bool "Reroute for broken boot IRQs"
880 depends on X86_IO_APIC
882 This option enables a workaround that fixes a source of
883 spurious interrupts. This is recommended when threaded
884 interrupt handling is used on systems where the generation of
885 superfluous "boot interrupts" cannot be disabled.
887 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
888 entry in the chipset's IO-APIC is masked (as, e.g. the RT
889 kernel does during interrupt handling). On chipsets where this
890 boot IRQ generation cannot be disabled, this workaround keeps
891 the original IRQ line masked so that only the equivalent "boot
892 IRQ" is delivered to the CPUs. The workaround also tells the
893 kernel to set up the IRQ handler on the boot IRQ line. In this
894 way only one interrupt is delivered to the kernel. Otherwise
895 the spurious second interrupt may cause the kernel to bring
896 down (vital) interrupt lines.
898 Only affects "broken" chipsets. Interrupt sharing may be
899 increased on these systems.
902 bool "Machine Check / overheating reporting"
905 Machine Check support allows the processor to notify the
906 kernel if it detects a problem (e.g. overheating, data corruption).
907 The action the kernel takes depends on the severity of the problem,
908 ranging from warning messages to halting the machine.
912 prompt "Intel MCE features"
913 depends on X86_MCE && X86_LOCAL_APIC
915 Additional support for intel specific MCE features such as
920 prompt "AMD MCE features"
921 depends on X86_MCE && X86_LOCAL_APIC
923 Additional support for AMD specific MCE features such as
924 the DRAM Error Threshold.
926 config X86_ANCIENT_MCE
927 bool "Support for old Pentium 5 / WinChip machine checks"
928 depends on X86_32 && X86_MCE
930 Include support for machine check handling on old Pentium 5 or WinChip
931 systems. These typically need to be enabled explicitely on the command
934 config X86_MCE_THRESHOLD
935 depends on X86_MCE_AMD || X86_MCE_INTEL
938 config X86_MCE_INJECT
940 tristate "Machine check injector support"
942 Provide support for injecting machine checks for testing purposes.
943 If you don't know what a machine check is and you don't do kernel
944 QA it is safe to say n.
946 config X86_THERMAL_VECTOR
948 depends on X86_MCE_INTEL
951 bool "Enable VM86 support" if EXPERT
955 This option is required by programs like DOSEMU to run 16-bit legacy
956 code on X86 processors. It also may be needed by software like
957 XFree86 to initialize some video cards via BIOS. Disabling this
958 option saves about 6k.
961 tristate "Toshiba Laptop support"
964 This adds a driver to safely access the System Management Mode of
965 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
966 not work on models with a Phoenix BIOS. The System Management Mode
967 is used to set the BIOS and power saving options on Toshiba portables.
969 For information on utilities to make use of this driver see the
970 Toshiba Linux utilities web site at:
971 <http://www.buzzard.org.uk/toshiba/>.
973 Say Y if you intend to run this kernel on a Toshiba portable.
977 tristate "Dell laptop support"
980 This adds a driver to safely access the System Management Mode
981 of the CPU on the Dell Inspiron 8000. The System Management Mode
982 is used to read cpu temperature and cooling fan status and to
983 control the fans on the I8K portables.
985 This driver has been tested only on the Inspiron 8000 but it may
986 also work with other Dell laptops. You can force loading on other
987 models by passing the parameter `force=1' to the module. Use at
990 For information on utilities to make use of this driver see the
991 I8K Linux utilities web site at:
992 <http://people.debian.org/~dz/i8k/>
994 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
997 config X86_REBOOTFIXUPS
998 bool "Enable X86 board specific fixups for reboot"
1001 This enables chipset and/or board specific fixups to be done
1002 in order to get reboot to work correctly. This is only needed on
1003 some combinations of hardware and BIOS. The symptom, for which
1004 this config is intended, is when reboot ends with a stalled/hung
1007 Currently, the only fixup is for the Geode machines using
1008 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1010 Say Y if you want to enable the fixup. Currently, it's safe to
1011 enable this option even if you don't need it.
1015 tristate "CPU microcode loading support"
1019 If you say Y here, you will be able to update the microcode on
1020 certain Intel and AMD processors. The Intel support is for the
1021 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1022 Xeon etc. The AMD support is for families 0x10 and later. You will
1023 obviously need the actual microcode binary data itself which is not
1024 shipped with the Linux kernel.
1026 This option selects the general module only, you need to select
1027 at least one vendor specific module as well.
1029 To compile this driver as a module, choose M here: the module
1030 will be called microcode.
1032 config MICROCODE_INTEL
1033 bool "Intel microcode loading support"
1034 depends on MICROCODE
1038 This options enables microcode patch loading support for Intel
1041 For latest news and information on obtaining all the required
1042 Intel ingredients for this driver, check:
1043 <http://www.urbanmyth.org/microcode/>.
1045 config MICROCODE_AMD
1046 bool "AMD microcode loading support"
1047 depends on MICROCODE
1050 If you select this option, microcode patch loading support for AMD
1051 processors will be enabled.
1053 config MICROCODE_OLD_INTERFACE
1055 depends on MICROCODE
1058 tristate "/dev/cpu/*/msr - Model-specific register support"
1060 This device gives privileged processes access to the x86
1061 Model-Specific Registers (MSRs). It is a character device with
1062 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1063 MSR accesses are directed to a specific CPU on multi-processor
1067 tristate "/dev/cpu/*/cpuid - CPU information support"
1069 This device gives processes access to the x86 CPUID instruction to
1070 be executed on a specific processor. It is a character device
1071 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1075 prompt "High Memory Support"
1076 default HIGHMEM64G if X86_NUMAQ
1082 depends on !X86_NUMAQ
1084 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1085 However, the address space of 32-bit x86 processors is only 4
1086 Gigabytes large. That means that, if you have a large amount of
1087 physical memory, not all of it can be "permanently mapped" by the
1088 kernel. The physical memory that's not permanently mapped is called
1091 If you are compiling a kernel which will never run on a machine with
1092 more than 1 Gigabyte total physical RAM, answer "off" here (default
1093 choice and suitable for most users). This will result in a "3GB/1GB"
1094 split: 3GB are mapped so that each process sees a 3GB virtual memory
1095 space and the remaining part of the 4GB virtual memory space is used
1096 by the kernel to permanently map as much physical memory as
1099 If the machine has between 1 and 4 Gigabytes physical RAM, then
1102 If more than 4 Gigabytes is used then answer "64GB" here. This
1103 selection turns Intel PAE (Physical Address Extension) mode on.
1104 PAE implements 3-level paging on IA32 processors. PAE is fully
1105 supported by Linux, PAE mode is implemented on all recent Intel
1106 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1107 then the kernel will not boot on CPUs that don't support PAE!
1109 The actual amount of total physical memory will either be
1110 auto detected or can be forced by using a kernel command line option
1111 such as "mem=256M". (Try "man bootparam" or see the documentation of
1112 your boot loader (lilo or loadlin) about how to pass options to the
1113 kernel at boot time.)
1115 If unsure, say "off".
1119 depends on !X86_NUMAQ
1121 Select this if you have a 32-bit processor and between 1 and 4
1122 gigabytes of physical RAM.
1129 Select this if you have a 32-bit processor and more than 4
1130 gigabytes of physical RAM.
1135 depends on EXPERIMENTAL
1136 prompt "Memory split" if EXPERT
1140 Select the desired split between kernel and user memory.
1142 If the address range available to the kernel is less than the
1143 physical memory installed, the remaining memory will be available
1144 as "high memory". Accessing high memory is a little more costly
1145 than low memory, as it needs to be mapped into the kernel first.
1146 Note that increasing the kernel address space limits the range
1147 available to user programs, making the address space there
1148 tighter. Selecting anything other than the default 3G/1G split
1149 will also likely make your kernel incompatible with binary-only
1152 If you are not absolutely sure what you are doing, leave this
1156 bool "3G/1G user/kernel split"
1157 config VMSPLIT_3G_OPT
1159 bool "3G/1G user/kernel split (for full 1G low memory)"
1161 bool "2G/2G user/kernel split"
1162 config VMSPLIT_2G_OPT
1164 bool "2G/2G user/kernel split (for full 2G low memory)"
1166 bool "1G/3G user/kernel split"
1171 default 0xB0000000 if VMSPLIT_3G_OPT
1172 default 0x80000000 if VMSPLIT_2G
1173 default 0x78000000 if VMSPLIT_2G_OPT
1174 default 0x40000000 if VMSPLIT_1G
1180 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1183 bool "PAE (Physical Address Extension) Support"
1184 depends on X86_32 && !HIGHMEM4G
1186 PAE is required for NX support, and furthermore enables
1187 larger swapspace support for non-overcommit purposes. It
1188 has the cost of more pagetable lookup overhead, and also
1189 consumes more pagetable space per process.
1191 config ARCH_PHYS_ADDR_T_64BIT
1193 depends on X86_64 || X86_PAE
1195 config ARCH_DMA_ADDR_T_64BIT
1197 depends on X86_64 || HIGHMEM64G
1199 config DIRECT_GBPAGES
1200 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1204 Allow the kernel linear mapping to use 1GB pages on CPUs that
1205 support it. This can improve the kernel's performance a tiny bit by
1206 reducing TLB pressure. If in doubt, say "Y".
1208 # Common NUMA Features
1210 bool "Numa Memory Allocation and Scheduler Support"
1212 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1213 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1215 Enable NUMA (Non Uniform Memory Access) support.
1217 The kernel will try to allocate memory used by a CPU on the
1218 local memory controller of the CPU and add some more
1219 NUMA awareness to the kernel.
1221 For 64-bit this is recommended if the system is Intel Core i7
1222 (or later), AMD Opteron, or EM64T NUMA.
1224 For 32-bit this is only needed on (rare) 32-bit-only platforms
1225 that support NUMA topologies, such as NUMAQ / Summit, or if you
1226 boot a 32-bit kernel on a 64-bit NUMA platform.
1228 Otherwise, you should say N.
1230 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1231 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1235 prompt "Old style AMD Opteron NUMA detection"
1236 depends on X86_64 && NUMA && PCI
1238 Enable AMD NUMA node topology detection. You should say Y here if
1239 you have a multi processor AMD system. This uses an old method to
1240 read the NUMA configuration directly from the builtin Northbridge
1241 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1242 which also takes priority if both are compiled in.
1244 config X86_64_ACPI_NUMA
1246 prompt "ACPI NUMA detection"
1247 depends on X86_64 && NUMA && ACPI && PCI
1250 Enable ACPI SRAT based node topology detection.
1252 # Some NUMA nodes have memory ranges that span
1253 # other nodes. Even though a pfn is valid and
1254 # between a node's start and end pfns, it may not
1255 # reside on that node. See memmap_init_zone()
1257 config NODES_SPAN_OTHER_NODES
1259 depends on X86_64_ACPI_NUMA
1262 bool "NUMA emulation"
1265 Enable NUMA emulation. A flat machine will be split
1266 into virtual nodes when booted with "numa=fake=N", where N is the
1267 number of nodes. This is only useful for debugging.
1270 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1272 default "10" if MAXSMP
1273 default "6" if X86_64
1274 default "4" if X86_NUMAQ
1276 depends on NEED_MULTIPLE_NODES
1278 Specify the maximum number of NUMA Nodes available on the target
1279 system. Increases memory reserved to accommodate various tables.
1281 config HAVE_ARCH_ALLOC_REMAP
1283 depends on X86_32 && NUMA
1285 config ARCH_HAVE_MEMORY_PRESENT
1287 depends on X86_32 && DISCONTIGMEM
1289 config NEED_NODE_MEMMAP_SIZE
1291 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1293 config ARCH_FLATMEM_ENABLE
1295 depends on X86_32 && !NUMA
1297 config ARCH_DISCONTIGMEM_ENABLE
1299 depends on NUMA && X86_32
1301 config ARCH_DISCONTIGMEM_DEFAULT
1303 depends on NUMA && X86_32
1305 config ARCH_SPARSEMEM_ENABLE
1307 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1308 select SPARSEMEM_STATIC if X86_32
1309 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1311 config ARCH_SPARSEMEM_DEFAULT
1315 config ARCH_SELECT_MEMORY_MODEL
1317 depends on ARCH_SPARSEMEM_ENABLE
1319 config ARCH_MEMORY_PROBE
1321 depends on X86_64 && MEMORY_HOTPLUG
1323 config ARCH_PROC_KCORE_TEXT
1325 depends on X86_64 && PROC_KCORE
1327 config ILLEGAL_POINTER_VALUE
1330 default 0xdead000000000000 if X86_64
1335 bool "Allocate 3rd-level pagetables from highmem"
1338 The VM uses one page table entry for each page of physical memory.
1339 For systems with a lot of RAM, this can be wasteful of precious
1340 low memory. Setting this option will put user-space page table
1341 entries in high memory.
1343 config X86_CHECK_BIOS_CORRUPTION
1344 bool "Check for low memory corruption"
1346 Periodically check for memory corruption in low memory, which
1347 is suspected to be caused by BIOS. Even when enabled in the
1348 configuration, it is disabled at runtime. Enable it by
1349 setting "memory_corruption_check=1" on the kernel command
1350 line. By default it scans the low 64k of memory every 60
1351 seconds; see the memory_corruption_check_size and
1352 memory_corruption_check_period parameters in
1353 Documentation/kernel-parameters.txt to adjust this.
1355 When enabled with the default parameters, this option has
1356 almost no overhead, as it reserves a relatively small amount
1357 of memory and scans it infrequently. It both detects corruption
1358 and prevents it from affecting the running system.
1360 It is, however, intended as a diagnostic tool; if repeatable
1361 BIOS-originated corruption always affects the same memory,
1362 you can use memmap= to prevent the kernel from using that
1365 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1366 bool "Set the default setting of memory_corruption_check"
1367 depends on X86_CHECK_BIOS_CORRUPTION
1370 Set whether the default state of memory_corruption_check is
1373 config X86_RESERVE_LOW
1374 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1378 Specify the amount of low memory to reserve for the BIOS.
1380 The first page contains BIOS data structures that the kernel
1381 must not use, so that page must always be reserved.
1383 By default we reserve the first 64K of physical RAM, as a
1384 number of BIOSes are known to corrupt that memory range
1385 during events such as suspend/resume or monitor cable
1386 insertion, so it must not be used by the kernel.
1388 You can set this to 4 if you are absolutely sure that you
1389 trust the BIOS to get all its memory reservations and usages
1390 right. If you know your BIOS have problems beyond the
1391 default 64K area, you can set this to 640 to avoid using the
1392 entire low memory range.
1394 If you have doubts about the BIOS (e.g. suspend/resume does
1395 not work or there's kernel crashes after certain hardware
1396 hotplug events) then you might want to enable
1397 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1398 typical corruption patterns.
1400 Leave this to the default value of 64 if you are unsure.
1402 config MATH_EMULATION
1404 prompt "Math emulation" if X86_32
1406 Linux can emulate a math coprocessor (used for floating point
1407 operations) if you don't have one. 486DX and Pentium processors have
1408 a math coprocessor built in, 486SX and 386 do not, unless you added
1409 a 487DX or 387, respectively. (The messages during boot time can
1410 give you some hints here ["man dmesg"].) Everyone needs either a
1411 coprocessor or this emulation.
1413 If you don't have a math coprocessor, you need to say Y here; if you
1414 say Y here even though you have a coprocessor, the coprocessor will
1415 be used nevertheless. (This behavior can be changed with the kernel
1416 command line option "no387", which comes handy if your coprocessor
1417 is broken. Try "man bootparam" or see the documentation of your boot
1418 loader (lilo or loadlin) about how to pass options to the kernel at
1419 boot time.) This means that it is a good idea to say Y here if you
1420 intend to use this kernel on different machines.
1422 More information about the internals of the Linux math coprocessor
1423 emulation can be found in <file:arch/x86/math-emu/README>.
1425 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1426 kernel, it won't hurt.
1430 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1432 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1433 the Memory Type Range Registers (MTRRs) may be used to control
1434 processor access to memory ranges. This is most useful if you have
1435 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1436 allows bus write transfers to be combined into a larger transfer
1437 before bursting over the PCI/AGP bus. This can increase performance
1438 of image write operations 2.5 times or more. Saying Y here creates a
1439 /proc/mtrr file which may be used to manipulate your processor's
1440 MTRRs. Typically the X server should use this.
1442 This code has a reasonably generic interface so that similar
1443 control registers on other processors can be easily supported
1446 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1447 Registers (ARRs) which provide a similar functionality to MTRRs. For
1448 these, the ARRs are used to emulate the MTRRs.
1449 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1450 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1451 write-combining. All of these processors are supported by this code
1452 and it makes sense to say Y here if you have one of them.
1454 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1455 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1456 can lead to all sorts of problems, so it's good to say Y here.
1458 You can safely say Y even if your machine doesn't have MTRRs, you'll
1459 just add about 9 KB to your kernel.
1461 See <file:Documentation/x86/mtrr.txt> for more information.
1463 config MTRR_SANITIZER
1465 prompt "MTRR cleanup support"
1468 Convert MTRR layout from continuous to discrete, so X drivers can
1469 add writeback entries.
1471 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1472 The largest mtrr entry size for a continuous block can be set with
1477 config MTRR_SANITIZER_ENABLE_DEFAULT
1478 int "MTRR cleanup enable value (0-1)"
1481 depends on MTRR_SANITIZER
1483 Enable mtrr cleanup default value
1485 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1486 int "MTRR cleanup spare reg num (0-7)"
1489 depends on MTRR_SANITIZER
1491 mtrr cleanup spare entries default, it can be changed via
1492 mtrr_spare_reg_nr=N on the kernel command line.
1496 prompt "x86 PAT support" if EXPERT
1499 Use PAT attributes to setup page level cache control.
1501 PATs are the modern equivalents of MTRRs and are much more
1502 flexible than MTRRs.
1504 Say N here if you see bootup problems (boot crash, boot hang,
1505 spontaneous reboots) or a non-working video driver.
1509 config ARCH_USES_PG_UNCACHED
1515 prompt "x86 architectural random number generator" if EXPERT
1517 Enable the x86 architectural RDRAND instruction
1518 (Intel Bull Mountain technology) to generate random numbers.
1519 If supported, this is a high bandwidth, cryptographically
1520 secure hardware random number generator.
1524 prompt "Supervisor Mode Access Prevention" if EXPERT
1526 Supervisor Mode Access Prevention (SMAP) is a security
1527 feature in newer Intel processors. There is a small
1528 performance cost if this enabled and turned on; there is
1529 also a small increase in the kernel size if this is enabled.
1534 bool "EFI runtime service support"
1537 This enables the kernel to use EFI runtime services that are
1538 available (such as the EFI variable services).
1540 This option is only useful on systems that have EFI firmware.
1541 In addition, you should use the latest ELILO loader available
1542 at <http://elilo.sourceforge.net> in order to take advantage
1543 of EFI runtime services. However, even with this option, the
1544 resultant kernel should continue to boot on existing non-EFI
1548 bool "EFI stub support"
1551 This kernel feature allows a bzImage to be loaded directly
1552 by EFI firmware without the use of a bootloader.
1554 See Documentation/x86/efi-stub.txt for more information.
1558 prompt "Enable seccomp to safely compute untrusted bytecode"
1560 This kernel feature is useful for number crunching applications
1561 that may need to compute untrusted bytecode during their
1562 execution. By using pipes or other transports made available to
1563 the process as file descriptors supporting the read/write
1564 syscalls, it's possible to isolate those applications in
1565 their own address space using seccomp. Once seccomp is
1566 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1567 and the task is only allowed to execute a few safe syscalls
1568 defined by each seccomp mode.
1570 If unsure, say Y. Only embedded should say N here.
1572 config CC_STACKPROTECTOR
1573 bool "Enable -fstack-protector buffer overflow detection"
1575 This option turns on the -fstack-protector GCC feature. This
1576 feature puts, at the beginning of functions, a canary value on
1577 the stack just before the return address, and validates
1578 the value just before actually returning. Stack based buffer
1579 overflows (that need to overwrite this return address) now also
1580 overwrite the canary, which gets detected and the attack is then
1581 neutralized via a kernel panic.
1583 This feature requires gcc version 4.2 or above, or a distribution
1584 gcc with the feature backported. Older versions are automatically
1585 detected and for those versions, this configuration option is
1586 ignored. (and a warning is printed during bootup)
1588 source kernel/Kconfig.hz
1591 bool "kexec system call"
1593 kexec is a system call that implements the ability to shutdown your
1594 current kernel, and to start another kernel. It is like a reboot
1595 but it is independent of the system firmware. And like a reboot
1596 you can start any kernel with it, not just Linux.
1598 The name comes from the similarity to the exec system call.
1600 It is an ongoing process to be certain the hardware in a machine
1601 is properly shutdown, so do not be surprised if this code does not
1602 initially work for you. It may help to enable device hotplugging
1603 support. As of this writing the exact hardware interface is
1604 strongly in flux, so no good recommendation can be made.
1607 bool "kernel crash dumps"
1608 depends on X86_64 || (X86_32 && HIGHMEM)
1610 Generate crash dump after being started by kexec.
1611 This should be normally only set in special crash dump kernels
1612 which are loaded in the main kernel with kexec-tools into
1613 a specially reserved region and then later executed after
1614 a crash by kdump/kexec. The crash dump kernel must be compiled
1615 to a memory address not used by the main kernel or BIOS using
1616 PHYSICAL_START, or it must be built as a relocatable image
1617 (CONFIG_RELOCATABLE=y).
1618 For more details see Documentation/kdump/kdump.txt
1621 bool "kexec jump (EXPERIMENTAL)"
1622 depends on EXPERIMENTAL
1623 depends on KEXEC && HIBERNATION
1625 Jump between original kernel and kexeced kernel and invoke
1626 code in physical address mode via KEXEC
1628 config PHYSICAL_START
1629 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1632 This gives the physical address where the kernel is loaded.
1634 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1635 bzImage will decompress itself to above physical address and
1636 run from there. Otherwise, bzImage will run from the address where
1637 it has been loaded by the boot loader and will ignore above physical
1640 In normal kdump cases one does not have to set/change this option
1641 as now bzImage can be compiled as a completely relocatable image
1642 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1643 address. This option is mainly useful for the folks who don't want
1644 to use a bzImage for capturing the crash dump and want to use a
1645 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1646 to be specifically compiled to run from a specific memory area
1647 (normally a reserved region) and this option comes handy.
1649 So if you are using bzImage for capturing the crash dump,
1650 leave the value here unchanged to 0x1000000 and set
1651 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1652 for capturing the crash dump change this value to start of
1653 the reserved region. In other words, it can be set based on
1654 the "X" value as specified in the "crashkernel=YM@XM"
1655 command line boot parameter passed to the panic-ed
1656 kernel. Please take a look at Documentation/kdump/kdump.txt
1657 for more details about crash dumps.
1659 Usage of bzImage for capturing the crash dump is recommended as
1660 one does not have to build two kernels. Same kernel can be used
1661 as production kernel and capture kernel. Above option should have
1662 gone away after relocatable bzImage support is introduced. But it
1663 is present because there are users out there who continue to use
1664 vmlinux for dump capture. This option should go away down the
1667 Don't change this unless you know what you are doing.
1670 bool "Build a relocatable kernel"
1673 This builds a kernel image that retains relocation information
1674 so it can be loaded someplace besides the default 1MB.
1675 The relocations tend to make the kernel binary about 10% larger,
1676 but are discarded at runtime.
1678 One use is for the kexec on panic case where the recovery kernel
1679 must live at a different physical address than the primary
1682 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1683 it has been loaded at and the compile time physical address
1684 (CONFIG_PHYSICAL_START) is ignored.
1686 # Relocation on x86-32 needs some additional build support
1687 config X86_NEED_RELOCS
1689 depends on X86_32 && RELOCATABLE
1691 config PHYSICAL_ALIGN
1692 hex "Alignment value to which kernel should be aligned" if X86_32
1694 range 0x2000 0x1000000
1696 This value puts the alignment restrictions on physical address
1697 where kernel is loaded and run from. Kernel is compiled for an
1698 address which meets above alignment restriction.
1700 If bootloader loads the kernel at a non-aligned address and
1701 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1702 address aligned to above value and run from there.
1704 If bootloader loads the kernel at a non-aligned address and
1705 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1706 load address and decompress itself to the address it has been
1707 compiled for and run from there. The address for which kernel is
1708 compiled already meets above alignment restrictions. Hence the
1709 end result is that kernel runs from a physical address meeting
1710 above alignment restrictions.
1712 Don't change this unless you know what you are doing.
1715 bool "Support for hot-pluggable CPUs"
1716 depends on SMP && HOTPLUG
1718 Say Y here to allow turning CPUs off and on. CPUs can be
1719 controlled through /sys/devices/system/cpu.
1720 ( Note: power management support will enable this option
1721 automatically on SMP systems. )
1722 Say N if you want to disable CPU hotplug.
1724 config BOOTPARAM_HOTPLUG_CPU0
1725 bool "Set default setting of cpu0_hotpluggable"
1727 depends on HOTPLUG_CPU && EXPERIMENTAL
1729 Set whether default state of cpu0_hotpluggable is on or off.
1731 Say Y here to enable CPU0 hotplug by default. If this switch
1732 is turned on, there is no need to give cpu0_hotplug kernel
1733 parameter and the CPU0 hotplug feature is enabled by default.
1735 Please note: there are two known CPU0 dependencies if you want
1736 to enable the CPU0 hotplug feature either by this switch or by
1737 cpu0_hotplug kernel parameter.
1739 First, resume from hibernate or suspend always starts from CPU0.
1740 So hibernate and suspend are prevented if CPU0 is offline.
1742 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1743 offline if any interrupt can not migrate out of CPU0. There may
1744 be other CPU0 dependencies.
1746 Please make sure the dependencies are under your control before
1747 you enable this feature.
1749 Say N if you don't want to enable CPU0 hotplug feature by default.
1750 You still can enable the CPU0 hotplug feature at boot by kernel
1751 parameter cpu0_hotplug.
1753 config DEBUG_HOTPLUG_CPU0
1755 prompt "Debug CPU0 hotplug"
1756 depends on HOTPLUG_CPU && EXPERIMENTAL
1758 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1759 soon as possible and boots up userspace with CPU0 offlined. User
1760 can online CPU0 back after boot time.
1762 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1763 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1764 compilation or giving cpu0_hotplug kernel parameter at boot.
1770 prompt "Compat VDSO support"
1771 depends on X86_32 || IA32_EMULATION
1773 Map the 32-bit VDSO to the predictable old-style address too.
1775 Say N here if you are running a sufficiently recent glibc
1776 version (2.3.3 or later), to remove the high-mapped
1777 VDSO mapping and to exclusively use the randomized VDSO.
1782 bool "Built-in kernel command line"
1784 Allow for specifying boot arguments to the kernel at
1785 build time. On some systems (e.g. embedded ones), it is
1786 necessary or convenient to provide some or all of the
1787 kernel boot arguments with the kernel itself (that is,
1788 to not rely on the boot loader to provide them.)
1790 To compile command line arguments into the kernel,
1791 set this option to 'Y', then fill in the
1792 the boot arguments in CONFIG_CMDLINE.
1794 Systems with fully functional boot loaders (i.e. non-embedded)
1795 should leave this option set to 'N'.
1798 string "Built-in kernel command string"
1799 depends on CMDLINE_BOOL
1802 Enter arguments here that should be compiled into the kernel
1803 image and used at boot time. If the boot loader provides a
1804 command line at boot time, it is appended to this string to
1805 form the full kernel command line, when the system boots.
1807 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1808 change this behavior.
1810 In most cases, the command line (whether built-in or provided
1811 by the boot loader) should specify the device for the root
1814 config CMDLINE_OVERRIDE
1815 bool "Built-in command line overrides boot loader arguments"
1816 depends on CMDLINE_BOOL
1818 Set this option to 'Y' to have the kernel ignore the boot loader
1819 command line, and use ONLY the built-in command line.
1821 This is used to work around broken boot loaders. This should
1822 be set to 'N' under normal conditions.
1826 config ARCH_ENABLE_MEMORY_HOTPLUG
1828 depends on X86_64 || (X86_32 && HIGHMEM)
1830 config ARCH_ENABLE_MEMORY_HOTREMOVE
1832 depends on MEMORY_HOTPLUG
1834 config USE_PERCPU_NUMA_NODE_ID
1838 menu "Power management and ACPI options"
1840 config ARCH_HIBERNATION_HEADER
1842 depends on X86_64 && HIBERNATION
1844 source "kernel/power/Kconfig"
1846 source "drivers/acpi/Kconfig"
1848 source "drivers/sfi/Kconfig"
1855 tristate "APM (Advanced Power Management) BIOS support"
1856 depends on X86_32 && PM_SLEEP
1858 APM is a BIOS specification for saving power using several different
1859 techniques. This is mostly useful for battery powered laptops with
1860 APM compliant BIOSes. If you say Y here, the system time will be
1861 reset after a RESUME operation, the /proc/apm device will provide
1862 battery status information, and user-space programs will receive
1863 notification of APM "events" (e.g. battery status change).
1865 If you select "Y" here, you can disable actual use of the APM
1866 BIOS by passing the "apm=off" option to the kernel at boot time.
1868 Note that the APM support is almost completely disabled for
1869 machines with more than one CPU.
1871 In order to use APM, you will need supporting software. For location
1872 and more information, read <file:Documentation/power/apm-acpi.txt>
1873 and the Battery Powered Linux mini-HOWTO, available from
1874 <http://www.tldp.org/docs.html#howto>.
1876 This driver does not spin down disk drives (see the hdparm(8)
1877 manpage ("man 8 hdparm") for that), and it doesn't turn off
1878 VESA-compliant "green" monitors.
1880 This driver does not support the TI 4000M TravelMate and the ACER
1881 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1882 desktop machines also don't have compliant BIOSes, and this driver
1883 may cause those machines to panic during the boot phase.
1885 Generally, if you don't have a battery in your machine, there isn't
1886 much point in using this driver and you should say N. If you get
1887 random kernel OOPSes or reboots that don't seem to be related to
1888 anything, try disabling/enabling this option (or disabling/enabling
1891 Some other things you should try when experiencing seemingly random,
1894 1) make sure that you have enough swap space and that it is
1896 2) pass the "no-hlt" option to the kernel
1897 3) switch on floating point emulation in the kernel and pass
1898 the "no387" option to the kernel
1899 4) pass the "floppy=nodma" option to the kernel
1900 5) pass the "mem=4M" option to the kernel (thereby disabling
1901 all but the first 4 MB of RAM)
1902 6) make sure that the CPU is not over clocked.
1903 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1904 8) disable the cache from your BIOS settings
1905 9) install a fan for the video card or exchange video RAM
1906 10) install a better fan for the CPU
1907 11) exchange RAM chips
1908 12) exchange the motherboard.
1910 To compile this driver as a module, choose M here: the
1911 module will be called apm.
1915 config APM_IGNORE_USER_SUSPEND
1916 bool "Ignore USER SUSPEND"
1918 This option will ignore USER SUSPEND requests. On machines with a
1919 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1920 series notebooks, it is necessary to say Y because of a BIOS bug.
1922 config APM_DO_ENABLE
1923 bool "Enable PM at boot time"
1925 Enable APM features at boot time. From page 36 of the APM BIOS
1926 specification: "When disabled, the APM BIOS does not automatically
1927 power manage devices, enter the Standby State, enter the Suspend
1928 State, or take power saving steps in response to CPU Idle calls."
1929 This driver will make CPU Idle calls when Linux is idle (unless this
1930 feature is turned off -- see "Do CPU IDLE calls", below). This
1931 should always save battery power, but more complicated APM features
1932 will be dependent on your BIOS implementation. You may need to turn
1933 this option off if your computer hangs at boot time when using APM
1934 support, or if it beeps continuously instead of suspending. Turn
1935 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1936 T400CDT. This is off by default since most machines do fine without
1941 bool "Make CPU Idle calls when idle"
1943 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1944 On some machines, this can activate improved power savings, such as
1945 a slowed CPU clock rate, when the machine is idle. These idle calls
1946 are made after the idle loop has run for some length of time (e.g.,
1947 333 mS). On some machines, this will cause a hang at boot time or
1948 whenever the CPU becomes idle. (On machines with more than one CPU,
1949 this option does nothing.)
1951 config APM_DISPLAY_BLANK
1952 bool "Enable console blanking using APM"
1954 Enable console blanking using the APM. Some laptops can use this to
1955 turn off the LCD backlight when the screen blanker of the Linux
1956 virtual console blanks the screen. Note that this is only used by
1957 the virtual console screen blanker, and won't turn off the backlight
1958 when using the X Window system. This also doesn't have anything to
1959 do with your VESA-compliant power-saving monitor. Further, this
1960 option doesn't work for all laptops -- it might not turn off your
1961 backlight at all, or it might print a lot of errors to the console,
1962 especially if you are using gpm.
1964 config APM_ALLOW_INTS
1965 bool "Allow interrupts during APM BIOS calls"
1967 Normally we disable external interrupts while we are making calls to
1968 the APM BIOS as a measure to lessen the effects of a badly behaving
1969 BIOS implementation. The BIOS should reenable interrupts if it
1970 needs to. Unfortunately, some BIOSes do not -- especially those in
1971 many of the newer IBM Thinkpads. If you experience hangs when you
1972 suspend, try setting this to Y. Otherwise, say N.
1976 source "drivers/cpufreq/Kconfig"
1978 source "drivers/cpuidle/Kconfig"
1980 source "drivers/idle/Kconfig"
1985 menu "Bus options (PCI etc.)"
1990 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1992 Find out whether you have a PCI motherboard. PCI is the name of a
1993 bus system, i.e. the way the CPU talks to the other stuff inside
1994 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1995 VESA. If you have PCI, say Y, otherwise N.
1998 prompt "PCI access mode"
1999 depends on X86_32 && PCI
2002 On PCI systems, the BIOS can be used to detect the PCI devices and
2003 determine their configuration. However, some old PCI motherboards
2004 have BIOS bugs and may crash if this is done. Also, some embedded
2005 PCI-based systems don't have any BIOS at all. Linux can also try to
2006 detect the PCI hardware directly without using the BIOS.
2008 With this option, you can specify how Linux should detect the
2009 PCI devices. If you choose "BIOS", the BIOS will be used,
2010 if you choose "Direct", the BIOS won't be used, and if you
2011 choose "MMConfig", then PCI Express MMCONFIG will be used.
2012 If you choose "Any", the kernel will try MMCONFIG, then the
2013 direct access method and falls back to the BIOS if that doesn't
2014 work. If unsure, go with the default, which is "Any".
2019 config PCI_GOMMCONFIG
2036 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2038 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2041 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2045 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2049 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2053 depends on PCI && XEN
2061 bool "Support mmconfig PCI config space access"
2062 depends on X86_64 && PCI && ACPI
2064 config PCI_CNB20LE_QUIRK
2065 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2066 depends on PCI && EXPERIMENTAL
2068 Read the PCI windows out of the CNB20LE host bridge. This allows
2069 PCI hotplug to work on systems with the CNB20LE chipset which do
2072 There's no public spec for this chipset, and this functionality
2073 is known to be incomplete.
2075 You should say N unless you know you need this.
2077 source "drivers/pci/pcie/Kconfig"
2079 source "drivers/pci/Kconfig"
2081 # x86_64 have no ISA slots, but can have ISA-style DMA.
2083 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2086 Enables ISA-style DMA support for devices requiring such controllers.
2094 Find out whether you have ISA slots on your motherboard. ISA is the
2095 name of a bus system, i.e. the way the CPU talks to the other stuff
2096 inside your box. Other bus systems are PCI, EISA, MicroChannel
2097 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2098 newer boards don't support it. If you have ISA, say Y, otherwise N.
2104 The Extended Industry Standard Architecture (EISA) bus was
2105 developed as an open alternative to the IBM MicroChannel bus.
2107 The EISA bus provided some of the features of the IBM MicroChannel
2108 bus while maintaining backward compatibility with cards made for
2109 the older ISA bus. The EISA bus saw limited use between 1988 and
2110 1995 when it was made obsolete by the PCI bus.
2112 Say Y here if you are building a kernel for an EISA-based machine.
2116 source "drivers/eisa/Kconfig"
2119 tristate "NatSemi SCx200 support"
2121 This provides basic support for National Semiconductor's
2122 (now AMD's) Geode processors. The driver probes for the
2123 PCI-IDs of several on-chip devices, so its a good dependency
2124 for other scx200_* drivers.
2126 If compiled as a module, the driver is named scx200.
2128 config SCx200HR_TIMER
2129 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2133 This driver provides a clocksource built upon the on-chip
2134 27MHz high-resolution timer. Its also a workaround for
2135 NSC Geode SC-1100's buggy TSC, which loses time when the
2136 processor goes idle (as is done by the scheduler). The
2137 other workaround is idle=poll boot option.
2140 bool "One Laptop Per Child support"
2147 Add support for detecting the unique features of the OLPC
2151 bool "OLPC XO-1 Power Management"
2152 depends on OLPC && MFD_CS5535 && PM_SLEEP
2155 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2158 bool "OLPC XO-1 Real Time Clock"
2159 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2161 Add support for the XO-1 real time clock, which can be used as a
2162 programmable wakeup source.
2165 bool "OLPC XO-1 SCI extras"
2166 depends on OLPC && OLPC_XO1_PM
2172 Add support for SCI-based features of the OLPC XO-1 laptop:
2173 - EC-driven system wakeups
2177 - AC adapter status updates
2178 - Battery status updates
2180 config OLPC_XO15_SCI
2181 bool "OLPC XO-1.5 SCI extras"
2182 depends on OLPC && ACPI
2185 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2186 - EC-driven system wakeups
2187 - AC adapter status updates
2188 - Battery status updates
2191 bool "PCEngines ALIX System Support (LED setup)"
2194 This option enables system support for the PCEngines ALIX.
2195 At present this just sets up LEDs for GPIO control on
2196 ALIX2/3/6 boards. However, other system specific setup should
2199 Note: You must still enable the drivers for GPIO and LED support
2200 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2202 Note: You have to set alix.force=1 for boards with Award BIOS.
2205 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2208 This option enables system support for the Soekris Engineering net5501.
2211 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2215 This option enables system support for the Traverse Technologies GEOS.
2218 bool "Technologic Systems TS-5500 platform support"
2220 select CHECK_SIGNATURE
2224 This option enables system support for the Technologic Systems TS-5500.
2230 depends on CPU_SUP_AMD && PCI
2232 source "drivers/pcmcia/Kconfig"
2234 source "drivers/pci/hotplug/Kconfig"
2237 bool "RapidIO support"
2241 If you say Y here, the kernel will include drivers and
2242 infrastructure code to support RapidIO interconnect devices.
2244 source "drivers/rapidio/Kconfig"
2249 menu "Executable file formats / Emulations"
2251 source "fs/Kconfig.binfmt"
2253 config IA32_EMULATION
2254 bool "IA32 Emulation"
2256 select COMPAT_BINFMT_ELF
2259 Include code to run legacy 32-bit programs under a
2260 64-bit kernel. You should likely turn this on, unless you're
2261 100% sure that you don't have any 32-bit programs left.
2264 tristate "IA32 a.out support"
2265 depends on IA32_EMULATION
2267 Support old a.out binaries in the 32bit emulation.
2270 bool "x32 ABI for 64-bit mode (EXPERIMENTAL)"
2271 depends on X86_64 && IA32_EMULATION && EXPERIMENTAL
2273 Include code to run binaries for the x32 native 32-bit ABI
2274 for 64-bit processors. An x32 process gets access to the
2275 full 64-bit register file and wide data path while leaving
2276 pointers at 32 bits for smaller memory footprint.
2278 You will need a recent binutils (2.22 or later) with
2279 elf32_x86_64 support enabled to compile a kernel with this
2284 depends on IA32_EMULATION || X86_X32
2285 select ARCH_WANT_OLD_COMPAT_IPC
2288 config COMPAT_FOR_U64_ALIGNMENT
2291 config SYSVIPC_COMPAT
2303 config HAVE_ATOMIC_IOMAP
2307 config HAVE_TEXT_POKE_SMP
2309 select STOP_MACHINE if SMP
2311 config X86_DEV_DMA_OPS
2313 depends on X86_64 || STA2X11
2315 config X86_DMA_REMAP
2319 source "net/Kconfig"
2321 source "drivers/Kconfig"
2323 source "drivers/firmware/Kconfig"
2327 source "arch/x86/Kconfig.debug"
2329 source "security/Kconfig"
2331 source "crypto/Kconfig"
2333 source "arch/x86/kvm/Kconfig"
2335 source "lib/Kconfig"
projects / firefly-linux-kernel-4.4.55.git / blob