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 GENERIC_IDLE_LOOP
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 ALWAYS_USE_PERSISTENT_CLOCK
112 select GENERIC_STRNCPY_FROM_USER
113 select GENERIC_STRNLEN_USER
114 select HAVE_CONTEXT_TRACKING if X86_64
115 select HAVE_IRQ_TIME_ACCOUNTING
117 select MODULES_USE_ELF_REL if X86_32
118 select MODULES_USE_ELF_RELA if X86_64
119 select CLONE_BACKWARDS if X86_32
120 select ARCH_USE_BUILTIN_BSWAP
121 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
122 select OLD_SIGACTION if X86_32
123 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
179 config ARCH_MAY_HAVE_PC_FDC
181 depends on ISA_DMA_API
183 config RWSEM_XCHGADD_ALGORITHM
186 config GENERIC_CALIBRATE_DELAY
189 config ARCH_HAS_CPU_RELAX
192 config ARCH_HAS_DEFAULT_IDLE
195 config ARCH_HAS_CACHE_LINE_SIZE
198 config ARCH_HAS_CPU_AUTOPROBE
201 config HAVE_SETUP_PER_CPU_AREA
204 config NEED_PER_CPU_EMBED_FIRST_CHUNK
207 config NEED_PER_CPU_PAGE_FIRST_CHUNK
210 config ARCH_HIBERNATION_POSSIBLE
213 config ARCH_SUSPEND_POSSIBLE
224 config ARCH_SUPPORTS_OPTIMIZED_INLINING
227 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
230 config HAVE_INTEL_TXT
232 depends on INTEL_IOMMU && ACPI
236 depends on X86_32 && SMP
240 depends on X86_64 && SMP
246 config X86_32_LAZY_GS
248 depends on X86_32 && !CC_STACKPROTECTOR
250 config ARCH_HWEIGHT_CFLAGS
252 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
253 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
255 config ARCH_CPU_PROBE_RELEASE
257 depends on HOTPLUG_CPU
259 config ARCH_SUPPORTS_UPROBES
262 source "init/Kconfig"
263 source "kernel/Kconfig.freezer"
265 menu "Processor type and features"
268 bool "DMA memory allocation support" if EXPERT
271 DMA memory allocation support allows devices with less than 32-bit
272 addressing to allocate within the first 16MB of address space.
273 Disable if no such devices will be used.
278 bool "Symmetric multi-processing support"
280 This enables support for systems with more than one CPU. If you have
281 a system with only one CPU, like most personal computers, say N. If
282 you have a system with more than one CPU, say Y.
284 If you say N here, the kernel will run on single and multiprocessor
285 machines, but will use only one CPU of a multiprocessor machine. If
286 you say Y here, the kernel will run on many, but not all,
287 singleprocessor machines. On a singleprocessor machine, the kernel
288 will run faster if you say N here.
290 Note that if you say Y here and choose architecture "586" or
291 "Pentium" under "Processor family", the kernel will not work on 486
292 architectures. Similarly, multiprocessor kernels for the "PPro"
293 architecture may not work on all Pentium based boards.
295 People using multiprocessor machines who say Y here should also say
296 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
297 Management" code will be disabled if you say Y here.
299 See also <file:Documentation/x86/i386/IO-APIC.txt>,
300 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
301 <http://www.tldp.org/docs.html#howto>.
303 If you don't know what to do here, say N.
306 bool "Support x2apic"
307 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
309 This enables x2apic support on CPUs that have this feature.
311 This allows 32-bit apic IDs (so it can support very large systems),
312 and accesses the local apic via MSRs not via mmio.
314 If you don't know what to do here, say N.
317 bool "Enable MPS table" if ACPI || SFI
319 depends on X86_LOCAL_APIC
321 For old smp systems that do not have proper acpi support. Newer systems
322 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
325 bool "Support for big SMP systems with more than 8 CPUs"
326 depends on X86_32 && SMP
328 This option is needed for the systems that have more than 8 CPUs
332 depends on X86_GOLDFISH
335 config X86_EXTENDED_PLATFORM
336 bool "Support for extended (non-PC) x86 platforms"
339 If you disable this option then the kernel will only support
340 standard PC platforms. (which covers the vast majority of
343 If you enable this option then you'll be able to select support
344 for the following (non-PC) 32 bit x86 platforms:
348 SGI 320/540 (Visual Workstation)
349 STA2X11-based (e.g. Northville)
350 Summit/EXA (IBM x440)
351 Unisys ES7000 IA32 series
352 Moorestown MID devices
354 If you have one of these systems, or if you want to build a
355 generic distribution kernel, say Y here - otherwise say N.
359 config X86_EXTENDED_PLATFORM
360 bool "Support for extended (non-PC) x86 platforms"
363 If you disable this option then the kernel will only support
364 standard PC platforms. (which covers the vast majority of
367 If you enable this option then you'll be able to select support
368 for the following (non-PC) 64 bit x86 platforms:
373 If you have one of these systems, or if you want to build a
374 generic distribution kernel, say Y here - otherwise say N.
376 # This is an alphabetically sorted list of 64 bit extended platforms
377 # Please maintain the alphabetic order if and when there are additions
379 bool "Numascale NumaChip"
381 depends on X86_EXTENDED_PLATFORM
384 depends on X86_X2APIC
385 depends on PCI_MMCONFIG
387 Adds support for Numascale NumaChip large-SMP systems. Needed to
388 enable more than ~168 cores.
389 If you don't have one of these, you should say N here.
393 select PARAVIRT_GUEST
395 depends on X86_64 && PCI
396 depends on X86_EXTENDED_PLATFORM
399 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
400 supposed to run on these EM64T-based machines. Only choose this option
401 if you have one of these machines.
404 bool "SGI Ultraviolet"
406 depends on X86_EXTENDED_PLATFORM
408 depends on X86_X2APIC
410 This option is needed in order to support SGI Ultraviolet systems.
411 If you don't have one of these, you should say N here.
413 # Following is an alphabetically sorted list of 32 bit extended platforms
414 # Please maintain the alphabetic order if and when there are additions
417 bool "Goldfish (Virtual Platform)"
420 Enable support for the Goldfish virtual platform used primarily
421 for Android development. Unless you are building for the Android
422 Goldfish emulator say N here.
425 bool "CE4100 TV platform"
427 depends on PCI_GODIRECT
429 depends on X86_EXTENDED_PLATFORM
430 select X86_REBOOTFIXUPS
432 select OF_EARLY_FLATTREE
435 Select for the Intel CE media processor (CE4100) SOC.
436 This option compiles in support for the CE4100 SOC for settop
437 boxes and media devices.
439 config X86_WANT_INTEL_MID
440 bool "Intel MID platform support"
442 depends on X86_EXTENDED_PLATFORM
444 Select to build a kernel capable of supporting Intel MID platform
445 systems which do not have the PCI legacy interfaces (Moorestown,
446 Medfield). If you are building for a PC class system say N here.
448 if X86_WANT_INTEL_MID
454 bool "Medfield MID platform"
457 depends on X86_IO_APIC
465 select X86_PLATFORM_DEVICES
466 select MFD_INTEL_MSIC
468 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
469 Internet Device(MID) platform.
470 Unlike standard x86 PCs, Medfield does not have many legacy devices
471 nor standard legacy replacement devices/features. e.g. Medfield does
472 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
476 config X86_INTEL_LPSS
477 bool "Intel Low Power Subsystem Support"
481 Select to build support for Intel Low Power Subsystem such as
482 found on Intel Lynxpoint PCH. Selecting this option enables
483 things like clock tree (common clock framework) which are needed
484 by the LPSS peripheral drivers.
487 bool "RDC R-321x SoC"
489 depends on X86_EXTENDED_PLATFORM
491 select X86_REBOOTFIXUPS
493 This option is needed for RDC R-321x system-on-chip, also known
495 If you don't have one of these chips, you should say N here.
497 config X86_32_NON_STANDARD
498 bool "Support non-standard 32-bit SMP architectures"
499 depends on X86_32 && SMP
500 depends on X86_EXTENDED_PLATFORM
502 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
503 STA2X11, default subarchitectures. It is intended for a generic
504 binary kernel. If you select them all, kernel will probe it
505 one by one and will fallback to default.
507 # Alphabetically sorted list of Non standard 32 bit platforms
510 bool "NUMAQ (IBM/Sequent)"
511 depends on X86_32_NON_STANDARD
516 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
517 NUMA multiquad box. This changes the way that processors are
518 bootstrapped, and uses Clustered Logical APIC addressing mode instead
519 of Flat Logical. You will need a new lynxer.elf file to flash your
520 firmware with - send email to <Martin.Bligh@us.ibm.com>.
522 config X86_SUPPORTS_MEMORY_FAILURE
524 # MCE code calls memory_failure():
526 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
527 depends on !X86_NUMAQ
528 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
529 depends on X86_64 || !SPARSEMEM
530 select ARCH_SUPPORTS_MEMORY_FAILURE
533 bool "SGI 320/540 (Visual Workstation)"
534 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
535 depends on X86_32_NON_STANDARD
537 The SGI Visual Workstation series is an IA32-based workstation
538 based on SGI systems chips with some legacy PC hardware attached.
540 Say Y here to create a kernel to run on the SGI 320 or 540.
542 A kernel compiled for the Visual Workstation will run on general
543 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
546 bool "STA2X11 Companion Chip Support"
547 depends on X86_32_NON_STANDARD && PCI
548 select X86_DEV_DMA_OPS
552 select ARCH_REQUIRE_GPIOLIB
555 This adds support for boards based on the STA2X11 IO-Hub,
556 a.k.a. "ConneXt". The chip is used in place of the standard
557 PC chipset, so all "standard" peripherals are missing. If this
558 option is selected the kernel will still be able to boot on
559 standard PC machines.
562 bool "Summit/EXA (IBM x440)"
563 depends on X86_32_NON_STANDARD
565 This option is needed for IBM systems that use the Summit/EXA chipset.
566 In particular, it is needed for the x440.
569 bool "Unisys ES7000 IA32 series"
570 depends on X86_32_NON_STANDARD && X86_BIGSMP
572 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
573 supposed to run on an IA32-based Unisys ES7000 system.
576 tristate "Eurobraille/Iris poweroff module"
579 The Iris machines from EuroBraille do not have APM or ACPI support
580 to shut themselves down properly. A special I/O sequence is
581 needed to do so, which is what this module does at
584 This is only for Iris machines from EuroBraille.
588 config SCHED_OMIT_FRAME_POINTER
590 prompt "Single-depth WCHAN output"
593 Calculate simpler /proc/<PID>/wchan values. If this option
594 is disabled then wchan values will recurse back to the
595 caller function. This provides more accurate wchan values,
596 at the expense of slightly more scheduling overhead.
598 If in doubt, say "Y".
600 menuconfig PARAVIRT_GUEST
601 bool "Paravirtualized guest support"
603 Say Y here to get to see options related to running Linux under
604 various hypervisors. This option alone does not add any kernel code.
606 If you say N, all options in this submenu will be skipped and disabled.
610 config PARAVIRT_TIME_ACCOUNTING
611 bool "Paravirtual steal time accounting"
615 Select this option to enable fine granularity task steal time
616 accounting. Time spent executing other tasks in parallel with
617 the current vCPU is discounted from the vCPU power. To account for
618 that, there can be a small performance impact.
620 If in doubt, say N here.
622 source "arch/x86/xen/Kconfig"
625 bool "KVM Guest support (including kvmclock)"
628 select PARAVIRT_CLOCK
629 default y if PARAVIRT_GUEST
631 This option enables various optimizations for running under the KVM
632 hypervisor. It includes a paravirtualized clock, so that instead
633 of relying on a PIT (or probably other) emulation by the
634 underlying device model, the host provides the guest with
635 timing infrastructure such as time of day, and system time
637 source "arch/x86/lguest/Kconfig"
640 bool "Enable paravirtualization code"
642 This changes the kernel so it can modify itself when it is run
643 under a hypervisor, potentially improving performance significantly
644 over full virtualization. However, when run without a hypervisor
645 the kernel is theoretically slower and slightly larger.
647 config PARAVIRT_SPINLOCKS
648 bool "Paravirtualization layer for spinlocks"
649 depends on PARAVIRT && SMP
651 Paravirtualized spinlocks allow a pvops backend to replace the
652 spinlock implementation with something virtualization-friendly
653 (for example, block the virtual CPU rather than spinning).
655 Unfortunately the downside is an up to 5% performance hit on
656 native kernels, with various workloads.
658 If you are unsure how to answer this question, answer N.
660 config PARAVIRT_CLOCK
665 config PARAVIRT_DEBUG
666 bool "paravirt-ops debugging"
667 depends on PARAVIRT && DEBUG_KERNEL
669 Enable to debug paravirt_ops internals. Specifically, BUG if
670 a paravirt_op is missing when it is called.
678 This option adds a kernel parameter 'memtest', which allows memtest
680 memtest=0, mean disabled; -- default
681 memtest=1, mean do 1 test pattern;
683 memtest=4, mean do 4 test patterns.
684 If you are unsure how to answer this question, answer N.
686 config X86_SUMMIT_NUMA
688 depends on X86_32 && NUMA && X86_32_NON_STANDARD
690 config X86_CYCLONE_TIMER
692 depends on X86_SUMMIT
694 source "arch/x86/Kconfig.cpu"
698 prompt "HPET Timer Support" if X86_32
700 Use the IA-PC HPET (High Precision Event Timer) to manage
701 time in preference to the PIT and RTC, if a HPET is
703 HPET is the next generation timer replacing legacy 8254s.
704 The HPET provides a stable time base on SMP
705 systems, unlike the TSC, but it is more expensive to access,
706 as it is off-chip. You can find the HPET spec at
707 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
709 You can safely choose Y here. However, HPET will only be
710 activated if the platform and the BIOS support this feature.
711 Otherwise the 8254 will be used for timing services.
713 Choose N to continue using the legacy 8254 timer.
715 config HPET_EMULATE_RTC
717 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
720 def_bool y if X86_INTEL_MID
721 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
723 depends on X86_INTEL_MID && SFI
725 APB timer is the replacement for 8254, HPET on X86 MID platforms.
726 The APBT provides a stable time base on SMP
727 systems, unlike the TSC, but it is more expensive to access,
728 as it is off-chip. APB timers are always running regardless of CPU
729 C states, they are used as per CPU clockevent device when possible.
731 # Mark as expert because too many people got it wrong.
732 # The code disables itself when not needed.
735 bool "Enable DMI scanning" if EXPERT
737 Enabled scanning of DMI to identify machine quirks. Say Y
738 here unless you have verified that your setup is not
739 affected by entries in the DMI blacklist. Required by PNP
743 bool "GART IOMMU support" if EXPERT
746 depends on X86_64 && PCI && AMD_NB
748 Support for full DMA access of devices with 32bit memory access only
749 on systems with more than 3GB. This is usually needed for USB,
750 sound, many IDE/SATA chipsets and some other devices.
751 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
752 based hardware IOMMU and a software bounce buffer based IOMMU used
753 on Intel systems and as fallback.
754 The code is only active when needed (enough memory and limited
755 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
759 bool "IBM Calgary IOMMU support"
761 depends on X86_64 && PCI
763 Support for hardware IOMMUs in IBM's xSeries x366 and x460
764 systems. Needed to run systems with more than 3GB of memory
765 properly with 32-bit PCI devices that do not support DAC
766 (Double Address Cycle). Calgary also supports bus level
767 isolation, where all DMAs pass through the IOMMU. This
768 prevents them from going anywhere except their intended
769 destination. This catches hard-to-find kernel bugs and
770 mis-behaving drivers and devices that do not use the DMA-API
771 properly to set up their DMA buffers. The IOMMU can be
772 turned off at boot time with the iommu=off parameter.
773 Normally the kernel will make the right choice by itself.
776 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
778 prompt "Should Calgary be enabled by default?"
779 depends on CALGARY_IOMMU
781 Should Calgary be enabled by default? if you choose 'y', Calgary
782 will be used (if it exists). If you choose 'n', Calgary will not be
783 used even if it exists. If you choose 'n' and would like to use
784 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
787 # need this always selected by IOMMU for the VIA workaround
791 Support for software bounce buffers used on x86-64 systems
792 which don't have a hardware IOMMU. Using this PCI devices
793 which can only access 32-bits of memory can be used on systems
794 with more than 3 GB of memory.
799 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
802 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
803 depends on X86_64 && SMP && DEBUG_KERNEL
804 select CPUMASK_OFFSTACK
806 Enable maximum number of CPUS and NUMA Nodes for this architecture.
810 int "Maximum number of CPUs" if SMP && !MAXSMP
811 range 2 8 if SMP && X86_32 && !X86_BIGSMP
812 range 2 512 if SMP && !MAXSMP
814 default "4096" if MAXSMP
815 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
818 This allows you to specify the maximum number of CPUs which this
819 kernel will support. The maximum supported value is 512 and the
820 minimum value which makes sense is 2.
822 This is purely to save memory - each supported CPU adds
823 approximately eight kilobytes to the kernel image.
826 bool "SMT (Hyperthreading) scheduler support"
829 SMT scheduler support improves the CPU scheduler's decision making
830 when dealing with Intel Pentium 4 chips with HyperThreading at a
831 cost of slightly increased overhead in some places. If unsure say
836 prompt "Multi-core scheduler support"
839 Multi-core scheduler support improves the CPU scheduler's decision
840 making when dealing with multi-core CPU chips at a cost of slightly
841 increased overhead in some places. If unsure say N here.
843 source "kernel/Kconfig.preempt"
846 bool "Local APIC support on uniprocessors"
847 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
849 A local APIC (Advanced Programmable Interrupt Controller) is an
850 integrated interrupt controller in the CPU. If you have a single-CPU
851 system which has a processor with a local APIC, you can say Y here to
852 enable and use it. If you say Y here even though your machine doesn't
853 have a local APIC, then the kernel will still run with no slowdown at
854 all. The local APIC supports CPU-generated self-interrupts (timer,
855 performance counters), and the NMI watchdog which detects hard
859 bool "IO-APIC support on uniprocessors"
860 depends on X86_UP_APIC
862 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
863 SMP-capable replacement for PC-style interrupt controllers. Most
864 SMP systems and many recent uniprocessor systems have one.
866 If you have a single-CPU system with an IO-APIC, you can say Y here
867 to use it. If you say Y here even though your machine doesn't have
868 an IO-APIC, then the kernel will still run with no slowdown at all.
870 config X86_LOCAL_APIC
872 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
876 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
878 config X86_VISWS_APIC
880 depends on X86_32 && X86_VISWS
882 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
883 bool "Reroute for broken boot IRQs"
884 depends on X86_IO_APIC
886 This option enables a workaround that fixes a source of
887 spurious interrupts. This is recommended when threaded
888 interrupt handling is used on systems where the generation of
889 superfluous "boot interrupts" cannot be disabled.
891 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
892 entry in the chipset's IO-APIC is masked (as, e.g. the RT
893 kernel does during interrupt handling). On chipsets where this
894 boot IRQ generation cannot be disabled, this workaround keeps
895 the original IRQ line masked so that only the equivalent "boot
896 IRQ" is delivered to the CPUs. The workaround also tells the
897 kernel to set up the IRQ handler on the boot IRQ line. In this
898 way only one interrupt is delivered to the kernel. Otherwise
899 the spurious second interrupt may cause the kernel to bring
900 down (vital) interrupt lines.
902 Only affects "broken" chipsets. Interrupt sharing may be
903 increased on these systems.
906 bool "Machine Check / overheating reporting"
909 Machine Check support allows the processor to notify the
910 kernel if it detects a problem (e.g. overheating, data corruption).
911 The action the kernel takes depends on the severity of the problem,
912 ranging from warning messages to halting the machine.
916 prompt "Intel MCE features"
917 depends on X86_MCE && X86_LOCAL_APIC
919 Additional support for intel specific MCE features such as
924 prompt "AMD MCE features"
925 depends on X86_MCE && X86_LOCAL_APIC
927 Additional support for AMD specific MCE features such as
928 the DRAM Error Threshold.
930 config X86_ANCIENT_MCE
931 bool "Support for old Pentium 5 / WinChip machine checks"
932 depends on X86_32 && X86_MCE
934 Include support for machine check handling on old Pentium 5 or WinChip
935 systems. These typically need to be enabled explicitely on the command
938 config X86_MCE_THRESHOLD
939 depends on X86_MCE_AMD || X86_MCE_INTEL
942 config X86_MCE_INJECT
944 tristate "Machine check injector support"
946 Provide support for injecting machine checks for testing purposes.
947 If you don't know what a machine check is and you don't do kernel
948 QA it is safe to say n.
950 config X86_THERMAL_VECTOR
952 depends on X86_MCE_INTEL
955 bool "Enable VM86 support" if EXPERT
959 This option is required by programs like DOSEMU to run 16-bit legacy
960 code on X86 processors. It also may be needed by software like
961 XFree86 to initialize some video cards via BIOS. Disabling this
962 option saves about 6k.
965 tristate "Toshiba Laptop support"
968 This adds a driver to safely access the System Management Mode of
969 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
970 not work on models with a Phoenix BIOS. The System Management Mode
971 is used to set the BIOS and power saving options on Toshiba portables.
973 For information on utilities to make use of this driver see the
974 Toshiba Linux utilities web site at:
975 <http://www.buzzard.org.uk/toshiba/>.
977 Say Y if you intend to run this kernel on a Toshiba portable.
981 tristate "Dell laptop support"
984 This adds a driver to safely access the System Management Mode
985 of the CPU on the Dell Inspiron 8000. The System Management Mode
986 is used to read cpu temperature and cooling fan status and to
987 control the fans on the I8K portables.
989 This driver has been tested only on the Inspiron 8000 but it may
990 also work with other Dell laptops. You can force loading on other
991 models by passing the parameter `force=1' to the module. Use at
994 For information on utilities to make use of this driver see the
995 I8K Linux utilities web site at:
996 <http://people.debian.org/~dz/i8k/>
998 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
1001 config X86_REBOOTFIXUPS
1002 bool "Enable X86 board specific fixups for reboot"
1005 This enables chipset and/or board specific fixups to be done
1006 in order to get reboot to work correctly. This is only needed on
1007 some combinations of hardware and BIOS. The symptom, for which
1008 this config is intended, is when reboot ends with a stalled/hung
1011 Currently, the only fixup is for the Geode machines using
1012 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1014 Say Y if you want to enable the fixup. Currently, it's safe to
1015 enable this option even if you don't need it.
1019 tristate "CPU microcode loading support"
1023 If you say Y here, you will be able to update the microcode on
1024 certain Intel and AMD processors. The Intel support is for the
1025 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1026 Xeon etc. The AMD support is for families 0x10 and later. You will
1027 obviously need the actual microcode binary data itself which is not
1028 shipped with the Linux kernel.
1030 This option selects the general module only, you need to select
1031 at least one vendor specific module as well.
1033 To compile this driver as a module, choose M here: the module
1034 will be called microcode.
1036 config MICROCODE_INTEL
1037 bool "Intel microcode loading support"
1038 depends on MICROCODE
1042 This options enables microcode patch loading support for Intel
1045 For latest news and information on obtaining all the required
1046 Intel ingredients for this driver, check:
1047 <http://www.urbanmyth.org/microcode/>.
1049 config MICROCODE_AMD
1050 bool "AMD microcode loading support"
1051 depends on MICROCODE
1054 If you select this option, microcode patch loading support for AMD
1055 processors will be enabled.
1057 config MICROCODE_OLD_INTERFACE
1059 depends on MICROCODE
1061 config MICROCODE_INTEL_LIB
1063 depends on MICROCODE_INTEL
1065 config MICROCODE_INTEL_EARLY
1066 bool "Early load microcode"
1067 depends on MICROCODE_INTEL && BLK_DEV_INITRD
1070 This option provides functionality to read additional microcode data
1071 at the beginning of initrd image. The data tells kernel to load
1072 microcode to CPU's as early as possible. No functional change if no
1073 microcode data is glued to the initrd, therefore it's safe to say Y.
1075 config MICROCODE_EARLY
1077 depends on MICROCODE_INTEL_EARLY
1080 tristate "/dev/cpu/*/msr - Model-specific register support"
1082 This device gives privileged processes access to the x86
1083 Model-Specific Registers (MSRs). It is a character device with
1084 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1085 MSR accesses are directed to a specific CPU on multi-processor
1089 tristate "/dev/cpu/*/cpuid - CPU information support"
1091 This device gives processes access to the x86 CPUID instruction to
1092 be executed on a specific processor. It is a character device
1093 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1097 prompt "High Memory Support"
1098 default HIGHMEM64G if X86_NUMAQ
1104 depends on !X86_NUMAQ
1106 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1107 However, the address space of 32-bit x86 processors is only 4
1108 Gigabytes large. That means that, if you have a large amount of
1109 physical memory, not all of it can be "permanently mapped" by the
1110 kernel. The physical memory that's not permanently mapped is called
1113 If you are compiling a kernel which will never run on a machine with
1114 more than 1 Gigabyte total physical RAM, answer "off" here (default
1115 choice and suitable for most users). This will result in a "3GB/1GB"
1116 split: 3GB are mapped so that each process sees a 3GB virtual memory
1117 space and the remaining part of the 4GB virtual memory space is used
1118 by the kernel to permanently map as much physical memory as
1121 If the machine has between 1 and 4 Gigabytes physical RAM, then
1124 If more than 4 Gigabytes is used then answer "64GB" here. This
1125 selection turns Intel PAE (Physical Address Extension) mode on.
1126 PAE implements 3-level paging on IA32 processors. PAE is fully
1127 supported by Linux, PAE mode is implemented on all recent Intel
1128 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1129 then the kernel will not boot on CPUs that don't support PAE!
1131 The actual amount of total physical memory will either be
1132 auto detected or can be forced by using a kernel command line option
1133 such as "mem=256M". (Try "man bootparam" or see the documentation of
1134 your boot loader (lilo or loadlin) about how to pass options to the
1135 kernel at boot time.)
1137 If unsure, say "off".
1141 depends on !X86_NUMAQ
1143 Select this if you have a 32-bit processor and between 1 and 4
1144 gigabytes of physical RAM.
1151 Select this if you have a 32-bit processor and more than 4
1152 gigabytes of physical RAM.
1157 prompt "Memory split" if EXPERT
1161 Select the desired split between kernel and user memory.
1163 If the address range available to the kernel is less than the
1164 physical memory installed, the remaining memory will be available
1165 as "high memory". Accessing high memory is a little more costly
1166 than low memory, as it needs to be mapped into the kernel first.
1167 Note that increasing the kernel address space limits the range
1168 available to user programs, making the address space there
1169 tighter. Selecting anything other than the default 3G/1G split
1170 will also likely make your kernel incompatible with binary-only
1173 If you are not absolutely sure what you are doing, leave this
1177 bool "3G/1G user/kernel split"
1178 config VMSPLIT_3G_OPT
1180 bool "3G/1G user/kernel split (for full 1G low memory)"
1182 bool "2G/2G user/kernel split"
1183 config VMSPLIT_2G_OPT
1185 bool "2G/2G user/kernel split (for full 2G low memory)"
1187 bool "1G/3G user/kernel split"
1192 default 0xB0000000 if VMSPLIT_3G_OPT
1193 default 0x80000000 if VMSPLIT_2G
1194 default 0x78000000 if VMSPLIT_2G_OPT
1195 default 0x40000000 if VMSPLIT_1G
1201 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1204 bool "PAE (Physical Address Extension) Support"
1205 depends on X86_32 && !HIGHMEM4G
1207 PAE is required for NX support, and furthermore enables
1208 larger swapspace support for non-overcommit purposes. It
1209 has the cost of more pagetable lookup overhead, and also
1210 consumes more pagetable space per process.
1212 config ARCH_PHYS_ADDR_T_64BIT
1214 depends on X86_64 || X86_PAE
1216 config ARCH_DMA_ADDR_T_64BIT
1218 depends on X86_64 || HIGHMEM64G
1220 config DIRECT_GBPAGES
1221 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1225 Allow the kernel linear mapping to use 1GB pages on CPUs that
1226 support it. This can improve the kernel's performance a tiny bit by
1227 reducing TLB pressure. If in doubt, say "Y".
1229 # Common NUMA Features
1231 bool "Numa Memory Allocation and Scheduler Support"
1233 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1234 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1236 Enable NUMA (Non Uniform Memory Access) support.
1238 The kernel will try to allocate memory used by a CPU on the
1239 local memory controller of the CPU and add some more
1240 NUMA awareness to the kernel.
1242 For 64-bit this is recommended if the system is Intel Core i7
1243 (or later), AMD Opteron, or EM64T NUMA.
1245 For 32-bit this is only needed on (rare) 32-bit-only platforms
1246 that support NUMA topologies, such as NUMAQ / Summit, or if you
1247 boot a 32-bit kernel on a 64-bit NUMA platform.
1249 Otherwise, you should say N.
1251 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1252 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1256 prompt "Old style AMD Opteron NUMA detection"
1257 depends on X86_64 && NUMA && PCI
1259 Enable AMD NUMA node topology detection. You should say Y here if
1260 you have a multi processor AMD system. This uses an old method to
1261 read the NUMA configuration directly from the builtin Northbridge
1262 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1263 which also takes priority if both are compiled in.
1265 config X86_64_ACPI_NUMA
1267 prompt "ACPI NUMA detection"
1268 depends on X86_64 && NUMA && ACPI && PCI
1271 Enable ACPI SRAT based node topology detection.
1273 # Some NUMA nodes have memory ranges that span
1274 # other nodes. Even though a pfn is valid and
1275 # between a node's start and end pfns, it may not
1276 # reside on that node. See memmap_init_zone()
1278 config NODES_SPAN_OTHER_NODES
1280 depends on X86_64_ACPI_NUMA
1283 bool "NUMA emulation"
1286 Enable NUMA emulation. A flat machine will be split
1287 into virtual nodes when booted with "numa=fake=N", where N is the
1288 number of nodes. This is only useful for debugging.
1291 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1293 default "10" if MAXSMP
1294 default "6" if X86_64
1295 default "4" if X86_NUMAQ
1297 depends on NEED_MULTIPLE_NODES
1299 Specify the maximum number of NUMA Nodes available on the target
1300 system. Increases memory reserved to accommodate various tables.
1302 config ARCH_HAVE_MEMORY_PRESENT
1304 depends on X86_32 && DISCONTIGMEM
1306 config NEED_NODE_MEMMAP_SIZE
1308 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1310 config ARCH_FLATMEM_ENABLE
1312 depends on X86_32 && !NUMA
1314 config ARCH_DISCONTIGMEM_ENABLE
1316 depends on NUMA && X86_32
1318 config ARCH_DISCONTIGMEM_DEFAULT
1320 depends on NUMA && X86_32
1322 config ARCH_SPARSEMEM_ENABLE
1324 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1325 select SPARSEMEM_STATIC if X86_32
1326 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1328 config ARCH_SPARSEMEM_DEFAULT
1332 config ARCH_SELECT_MEMORY_MODEL
1334 depends on ARCH_SPARSEMEM_ENABLE
1336 config ARCH_MEMORY_PROBE
1338 depends on X86_64 && MEMORY_HOTPLUG
1340 config ARCH_PROC_KCORE_TEXT
1342 depends on X86_64 && PROC_KCORE
1344 config ILLEGAL_POINTER_VALUE
1347 default 0xdead000000000000 if X86_64
1352 bool "Allocate 3rd-level pagetables from highmem"
1355 The VM uses one page table entry for each page of physical memory.
1356 For systems with a lot of RAM, this can be wasteful of precious
1357 low memory. Setting this option will put user-space page table
1358 entries in high memory.
1360 config X86_CHECK_BIOS_CORRUPTION
1361 bool "Check for low memory corruption"
1363 Periodically check for memory corruption in low memory, which
1364 is suspected to be caused by BIOS. Even when enabled in the
1365 configuration, it is disabled at runtime. Enable it by
1366 setting "memory_corruption_check=1" on the kernel command
1367 line. By default it scans the low 64k of memory every 60
1368 seconds; see the memory_corruption_check_size and
1369 memory_corruption_check_period parameters in
1370 Documentation/kernel-parameters.txt to adjust this.
1372 When enabled with the default parameters, this option has
1373 almost no overhead, as it reserves a relatively small amount
1374 of memory and scans it infrequently. It both detects corruption
1375 and prevents it from affecting the running system.
1377 It is, however, intended as a diagnostic tool; if repeatable
1378 BIOS-originated corruption always affects the same memory,
1379 you can use memmap= to prevent the kernel from using that
1382 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1383 bool "Set the default setting of memory_corruption_check"
1384 depends on X86_CHECK_BIOS_CORRUPTION
1387 Set whether the default state of memory_corruption_check is
1390 config X86_RESERVE_LOW
1391 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1395 Specify the amount of low memory to reserve for the BIOS.
1397 The first page contains BIOS data structures that the kernel
1398 must not use, so that page must always be reserved.
1400 By default we reserve the first 64K of physical RAM, as a
1401 number of BIOSes are known to corrupt that memory range
1402 during events such as suspend/resume or monitor cable
1403 insertion, so it must not be used by the kernel.
1405 You can set this to 4 if you are absolutely sure that you
1406 trust the BIOS to get all its memory reservations and usages
1407 right. If you know your BIOS have problems beyond the
1408 default 64K area, you can set this to 640 to avoid using the
1409 entire low memory range.
1411 If you have doubts about the BIOS (e.g. suspend/resume does
1412 not work or there's kernel crashes after certain hardware
1413 hotplug events) then you might want to enable
1414 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1415 typical corruption patterns.
1417 Leave this to the default value of 64 if you are unsure.
1419 config MATH_EMULATION
1421 prompt "Math emulation" if X86_32
1423 Linux can emulate a math coprocessor (used for floating point
1424 operations) if you don't have one. 486DX and Pentium processors have
1425 a math coprocessor built in, 486SX and 386 do not, unless you added
1426 a 487DX or 387, respectively. (The messages during boot time can
1427 give you some hints here ["man dmesg"].) Everyone needs either a
1428 coprocessor or this emulation.
1430 If you don't have a math coprocessor, you need to say Y here; if you
1431 say Y here even though you have a coprocessor, the coprocessor will
1432 be used nevertheless. (This behavior can be changed with the kernel
1433 command line option "no387", which comes handy if your coprocessor
1434 is broken. Try "man bootparam" or see the documentation of your boot
1435 loader (lilo or loadlin) about how to pass options to the kernel at
1436 boot time.) This means that it is a good idea to say Y here if you
1437 intend to use this kernel on different machines.
1439 More information about the internals of the Linux math coprocessor
1440 emulation can be found in <file:arch/x86/math-emu/README>.
1442 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1443 kernel, it won't hurt.
1447 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1449 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1450 the Memory Type Range Registers (MTRRs) may be used to control
1451 processor access to memory ranges. This is most useful if you have
1452 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1453 allows bus write transfers to be combined into a larger transfer
1454 before bursting over the PCI/AGP bus. This can increase performance
1455 of image write operations 2.5 times or more. Saying Y here creates a
1456 /proc/mtrr file which may be used to manipulate your processor's
1457 MTRRs. Typically the X server should use this.
1459 This code has a reasonably generic interface so that similar
1460 control registers on other processors can be easily supported
1463 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1464 Registers (ARRs) which provide a similar functionality to MTRRs. For
1465 these, the ARRs are used to emulate the MTRRs.
1466 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1467 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1468 write-combining. All of these processors are supported by this code
1469 and it makes sense to say Y here if you have one of them.
1471 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1472 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1473 can lead to all sorts of problems, so it's good to say Y here.
1475 You can safely say Y even if your machine doesn't have MTRRs, you'll
1476 just add about 9 KB to your kernel.
1478 See <file:Documentation/x86/mtrr.txt> for more information.
1480 config MTRR_SANITIZER
1482 prompt "MTRR cleanup support"
1485 Convert MTRR layout from continuous to discrete, so X drivers can
1486 add writeback entries.
1488 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1489 The largest mtrr entry size for a continuous block can be set with
1494 config MTRR_SANITIZER_ENABLE_DEFAULT
1495 int "MTRR cleanup enable value (0-1)"
1498 depends on MTRR_SANITIZER
1500 Enable mtrr cleanup default value
1502 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1503 int "MTRR cleanup spare reg num (0-7)"
1506 depends on MTRR_SANITIZER
1508 mtrr cleanup spare entries default, it can be changed via
1509 mtrr_spare_reg_nr=N on the kernel command line.
1513 prompt "x86 PAT support" if EXPERT
1516 Use PAT attributes to setup page level cache control.
1518 PATs are the modern equivalents of MTRRs and are much more
1519 flexible than MTRRs.
1521 Say N here if you see bootup problems (boot crash, boot hang,
1522 spontaneous reboots) or a non-working video driver.
1526 config ARCH_USES_PG_UNCACHED
1532 prompt "x86 architectural random number generator" if EXPERT
1534 Enable the x86 architectural RDRAND instruction
1535 (Intel Bull Mountain technology) to generate random numbers.
1536 If supported, this is a high bandwidth, cryptographically
1537 secure hardware random number generator.
1541 prompt "Supervisor Mode Access Prevention" if EXPERT
1543 Supervisor Mode Access Prevention (SMAP) is a security
1544 feature in newer Intel processors. There is a small
1545 performance cost if this enabled and turned on; there is
1546 also a small increase in the kernel size if this is enabled.
1551 bool "EFI runtime service support"
1554 This enables the kernel to use EFI runtime services that are
1555 available (such as the EFI variable services).
1557 This option is only useful on systems that have EFI firmware.
1558 In addition, you should use the latest ELILO loader available
1559 at <http://elilo.sourceforge.net> in order to take advantage
1560 of EFI runtime services. However, even with this option, the
1561 resultant kernel should continue to boot on existing non-EFI
1565 bool "EFI stub support"
1568 This kernel feature allows a bzImage to be loaded directly
1569 by EFI firmware without the use of a bootloader.
1571 See Documentation/x86/efi-stub.txt for more information.
1575 prompt "Enable seccomp to safely compute untrusted bytecode"
1577 This kernel feature is useful for number crunching applications
1578 that may need to compute untrusted bytecode during their
1579 execution. By using pipes or other transports made available to
1580 the process as file descriptors supporting the read/write
1581 syscalls, it's possible to isolate those applications in
1582 their own address space using seccomp. Once seccomp is
1583 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1584 and the task is only allowed to execute a few safe syscalls
1585 defined by each seccomp mode.
1587 If unsure, say Y. Only embedded should say N here.
1589 config CC_STACKPROTECTOR
1590 bool "Enable -fstack-protector buffer overflow detection"
1592 This option turns on the -fstack-protector GCC feature. This
1593 feature puts, at the beginning of functions, a canary value on
1594 the stack just before the return address, and validates
1595 the value just before actually returning. Stack based buffer
1596 overflows (that need to overwrite this return address) now also
1597 overwrite the canary, which gets detected and the attack is then
1598 neutralized via a kernel panic.
1600 This feature requires gcc version 4.2 or above, or a distribution
1601 gcc with the feature backported. Older versions are automatically
1602 detected and for those versions, this configuration option is
1603 ignored. (and a warning is printed during bootup)
1605 source kernel/Kconfig.hz
1608 bool "kexec system call"
1610 kexec is a system call that implements the ability to shutdown your
1611 current kernel, and to start another kernel. It is like a reboot
1612 but it is independent of the system firmware. And like a reboot
1613 you can start any kernel with it, not just Linux.
1615 The name comes from the similarity to the exec system call.
1617 It is an ongoing process to be certain the hardware in a machine
1618 is properly shutdown, so do not be surprised if this code does not
1619 initially work for you. It may help to enable device hotplugging
1620 support. As of this writing the exact hardware interface is
1621 strongly in flux, so no good recommendation can be made.
1624 bool "kernel crash dumps"
1625 depends on X86_64 || (X86_32 && HIGHMEM)
1627 Generate crash dump after being started by kexec.
1628 This should be normally only set in special crash dump kernels
1629 which are loaded in the main kernel with kexec-tools into
1630 a specially reserved region and then later executed after
1631 a crash by kdump/kexec. The crash dump kernel must be compiled
1632 to a memory address not used by the main kernel or BIOS using
1633 PHYSICAL_START, or it must be built as a relocatable image
1634 (CONFIG_RELOCATABLE=y).
1635 For more details see Documentation/kdump/kdump.txt
1639 depends on KEXEC && HIBERNATION
1641 Jump between original kernel and kexeced kernel and invoke
1642 code in physical address mode via KEXEC
1644 config PHYSICAL_START
1645 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1648 This gives the physical address where the kernel is loaded.
1650 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1651 bzImage will decompress itself to above physical address and
1652 run from there. Otherwise, bzImage will run from the address where
1653 it has been loaded by the boot loader and will ignore above physical
1656 In normal kdump cases one does not have to set/change this option
1657 as now bzImage can be compiled as a completely relocatable image
1658 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1659 address. This option is mainly useful for the folks who don't want
1660 to use a bzImage for capturing the crash dump and want to use a
1661 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1662 to be specifically compiled to run from a specific memory area
1663 (normally a reserved region) and this option comes handy.
1665 So if you are using bzImage for capturing the crash dump,
1666 leave the value here unchanged to 0x1000000 and set
1667 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1668 for capturing the crash dump change this value to start of
1669 the reserved region. In other words, it can be set based on
1670 the "X" value as specified in the "crashkernel=YM@XM"
1671 command line boot parameter passed to the panic-ed
1672 kernel. Please take a look at Documentation/kdump/kdump.txt
1673 for more details about crash dumps.
1675 Usage of bzImage for capturing the crash dump is recommended as
1676 one does not have to build two kernels. Same kernel can be used
1677 as production kernel and capture kernel. Above option should have
1678 gone away after relocatable bzImage support is introduced. But it
1679 is present because there are users out there who continue to use
1680 vmlinux for dump capture. This option should go away down the
1683 Don't change this unless you know what you are doing.
1686 bool "Build a relocatable kernel"
1689 This builds a kernel image that retains relocation information
1690 so it can be loaded someplace besides the default 1MB.
1691 The relocations tend to make the kernel binary about 10% larger,
1692 but are discarded at runtime.
1694 One use is for the kexec on panic case where the recovery kernel
1695 must live at a different physical address than the primary
1698 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1699 it has been loaded at and the compile time physical address
1700 (CONFIG_PHYSICAL_START) is ignored.
1702 # Relocation on x86-32 needs some additional build support
1703 config X86_NEED_RELOCS
1705 depends on X86_32 && RELOCATABLE
1707 config PHYSICAL_ALIGN
1708 hex "Alignment value to which kernel should be aligned" if X86_32
1710 range 0x2000 0x1000000
1712 This value puts the alignment restrictions on physical address
1713 where kernel is loaded and run from. Kernel is compiled for an
1714 address which meets above alignment restriction.
1716 If bootloader loads the kernel at a non-aligned address and
1717 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1718 address aligned to above value and run from there.
1720 If bootloader loads the kernel at a non-aligned address and
1721 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1722 load address and decompress itself to the address it has been
1723 compiled for and run from there. The address for which kernel is
1724 compiled already meets above alignment restrictions. Hence the
1725 end result is that kernel runs from a physical address meeting
1726 above alignment restrictions.
1728 Don't change this unless you know what you are doing.
1731 bool "Support for hot-pluggable CPUs"
1732 depends on SMP && HOTPLUG
1734 Say Y here to allow turning CPUs off and on. CPUs can be
1735 controlled through /sys/devices/system/cpu.
1736 ( Note: power management support will enable this option
1737 automatically on SMP systems. )
1738 Say N if you want to disable CPU hotplug.
1740 config BOOTPARAM_HOTPLUG_CPU0
1741 bool "Set default setting of cpu0_hotpluggable"
1743 depends on HOTPLUG_CPU
1745 Set whether default state of cpu0_hotpluggable is on or off.
1747 Say Y here to enable CPU0 hotplug by default. If this switch
1748 is turned on, there is no need to give cpu0_hotplug kernel
1749 parameter and the CPU0 hotplug feature is enabled by default.
1751 Please note: there are two known CPU0 dependencies if you want
1752 to enable the CPU0 hotplug feature either by this switch or by
1753 cpu0_hotplug kernel parameter.
1755 First, resume from hibernate or suspend always starts from CPU0.
1756 So hibernate and suspend are prevented if CPU0 is offline.
1758 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1759 offline if any interrupt can not migrate out of CPU0. There may
1760 be other CPU0 dependencies.
1762 Please make sure the dependencies are under your control before
1763 you enable this feature.
1765 Say N if you don't want to enable CPU0 hotplug feature by default.
1766 You still can enable the CPU0 hotplug feature at boot by kernel
1767 parameter cpu0_hotplug.
1769 config DEBUG_HOTPLUG_CPU0
1771 prompt "Debug CPU0 hotplug"
1772 depends on HOTPLUG_CPU
1774 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1775 soon as possible and boots up userspace with CPU0 offlined. User
1776 can online CPU0 back after boot time.
1778 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1779 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1780 compilation or giving cpu0_hotplug kernel parameter at boot.
1786 prompt "Compat VDSO support"
1787 depends on X86_32 || IA32_EMULATION
1789 Map the 32-bit VDSO to the predictable old-style address too.
1791 Say N here if you are running a sufficiently recent glibc
1792 version (2.3.3 or later), to remove the high-mapped
1793 VDSO mapping and to exclusively use the randomized VDSO.
1798 bool "Built-in kernel command line"
1800 Allow for specifying boot arguments to the kernel at
1801 build time. On some systems (e.g. embedded ones), it is
1802 necessary or convenient to provide some or all of the
1803 kernel boot arguments with the kernel itself (that is,
1804 to not rely on the boot loader to provide them.)
1806 To compile command line arguments into the kernel,
1807 set this option to 'Y', then fill in the
1808 the boot arguments in CONFIG_CMDLINE.
1810 Systems with fully functional boot loaders (i.e. non-embedded)
1811 should leave this option set to 'N'.
1814 string "Built-in kernel command string"
1815 depends on CMDLINE_BOOL
1818 Enter arguments here that should be compiled into the kernel
1819 image and used at boot time. If the boot loader provides a
1820 command line at boot time, it is appended to this string to
1821 form the full kernel command line, when the system boots.
1823 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1824 change this behavior.
1826 In most cases, the command line (whether built-in or provided
1827 by the boot loader) should specify the device for the root
1830 config CMDLINE_OVERRIDE
1831 bool "Built-in command line overrides boot loader arguments"
1832 depends on CMDLINE_BOOL
1834 Set this option to 'Y' to have the kernel ignore the boot loader
1835 command line, and use ONLY the built-in command line.
1837 This is used to work around broken boot loaders. This should
1838 be set to 'N' under normal conditions.
1842 config ARCH_ENABLE_MEMORY_HOTPLUG
1844 depends on X86_64 || (X86_32 && HIGHMEM)
1846 config ARCH_ENABLE_MEMORY_HOTREMOVE
1848 depends on MEMORY_HOTPLUG
1850 config USE_PERCPU_NUMA_NODE_ID
1854 menu "Power management and ACPI options"
1856 config ARCH_HIBERNATION_HEADER
1858 depends on X86_64 && HIBERNATION
1860 source "kernel/power/Kconfig"
1862 source "drivers/acpi/Kconfig"
1864 source "drivers/sfi/Kconfig"
1871 tristate "APM (Advanced Power Management) BIOS support"
1872 depends on X86_32 && PM_SLEEP
1874 APM is a BIOS specification for saving power using several different
1875 techniques. This is mostly useful for battery powered laptops with
1876 APM compliant BIOSes. If you say Y here, the system time will be
1877 reset after a RESUME operation, the /proc/apm device will provide
1878 battery status information, and user-space programs will receive
1879 notification of APM "events" (e.g. battery status change).
1881 If you select "Y" here, you can disable actual use of the APM
1882 BIOS by passing the "apm=off" option to the kernel at boot time.
1884 Note that the APM support is almost completely disabled for
1885 machines with more than one CPU.
1887 In order to use APM, you will need supporting software. For location
1888 and more information, read <file:Documentation/power/apm-acpi.txt>
1889 and the Battery Powered Linux mini-HOWTO, available from
1890 <http://www.tldp.org/docs.html#howto>.
1892 This driver does not spin down disk drives (see the hdparm(8)
1893 manpage ("man 8 hdparm") for that), and it doesn't turn off
1894 VESA-compliant "green" monitors.
1896 This driver does not support the TI 4000M TravelMate and the ACER
1897 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1898 desktop machines also don't have compliant BIOSes, and this driver
1899 may cause those machines to panic during the boot phase.
1901 Generally, if you don't have a battery in your machine, there isn't
1902 much point in using this driver and you should say N. If you get
1903 random kernel OOPSes or reboots that don't seem to be related to
1904 anything, try disabling/enabling this option (or disabling/enabling
1907 Some other things you should try when experiencing seemingly random,
1910 1) make sure that you have enough swap space and that it is
1912 2) pass the "no-hlt" option to the kernel
1913 3) switch on floating point emulation in the kernel and pass
1914 the "no387" option to the kernel
1915 4) pass the "floppy=nodma" option to the kernel
1916 5) pass the "mem=4M" option to the kernel (thereby disabling
1917 all but the first 4 MB of RAM)
1918 6) make sure that the CPU is not over clocked.
1919 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1920 8) disable the cache from your BIOS settings
1921 9) install a fan for the video card or exchange video RAM
1922 10) install a better fan for the CPU
1923 11) exchange RAM chips
1924 12) exchange the motherboard.
1926 To compile this driver as a module, choose M here: the
1927 module will be called apm.
1931 config APM_IGNORE_USER_SUSPEND
1932 bool "Ignore USER SUSPEND"
1934 This option will ignore USER SUSPEND requests. On machines with a
1935 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1936 series notebooks, it is necessary to say Y because of a BIOS bug.
1938 config APM_DO_ENABLE
1939 bool "Enable PM at boot time"
1941 Enable APM features at boot time. From page 36 of the APM BIOS
1942 specification: "When disabled, the APM BIOS does not automatically
1943 power manage devices, enter the Standby State, enter the Suspend
1944 State, or take power saving steps in response to CPU Idle calls."
1945 This driver will make CPU Idle calls when Linux is idle (unless this
1946 feature is turned off -- see "Do CPU IDLE calls", below). This
1947 should always save battery power, but more complicated APM features
1948 will be dependent on your BIOS implementation. You may need to turn
1949 this option off if your computer hangs at boot time when using APM
1950 support, or if it beeps continuously instead of suspending. Turn
1951 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1952 T400CDT. This is off by default since most machines do fine without
1957 bool "Make CPU Idle calls when idle"
1959 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1960 On some machines, this can activate improved power savings, such as
1961 a slowed CPU clock rate, when the machine is idle. These idle calls
1962 are made after the idle loop has run for some length of time (e.g.,
1963 333 mS). On some machines, this will cause a hang at boot time or
1964 whenever the CPU becomes idle. (On machines with more than one CPU,
1965 this option does nothing.)
1967 config APM_DISPLAY_BLANK
1968 bool "Enable console blanking using APM"
1970 Enable console blanking using the APM. Some laptops can use this to
1971 turn off the LCD backlight when the screen blanker of the Linux
1972 virtual console blanks the screen. Note that this is only used by
1973 the virtual console screen blanker, and won't turn off the backlight
1974 when using the X Window system. This also doesn't have anything to
1975 do with your VESA-compliant power-saving monitor. Further, this
1976 option doesn't work for all laptops -- it might not turn off your
1977 backlight at all, or it might print a lot of errors to the console,
1978 especially if you are using gpm.
1980 config APM_ALLOW_INTS
1981 bool "Allow interrupts during APM BIOS calls"
1983 Normally we disable external interrupts while we are making calls to
1984 the APM BIOS as a measure to lessen the effects of a badly behaving
1985 BIOS implementation. The BIOS should reenable interrupts if it
1986 needs to. Unfortunately, some BIOSes do not -- especially those in
1987 many of the newer IBM Thinkpads. If you experience hangs when you
1988 suspend, try setting this to Y. Otherwise, say N.
1992 source "drivers/cpufreq/Kconfig"
1994 source "drivers/cpuidle/Kconfig"
1996 source "drivers/idle/Kconfig"
2001 menu "Bus options (PCI etc.)"
2006 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2008 Find out whether you have a PCI motherboard. PCI is the name of a
2009 bus system, i.e. the way the CPU talks to the other stuff inside
2010 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2011 VESA. If you have PCI, say Y, otherwise N.
2014 prompt "PCI access mode"
2015 depends on X86_32 && PCI
2018 On PCI systems, the BIOS can be used to detect the PCI devices and
2019 determine their configuration. However, some old PCI motherboards
2020 have BIOS bugs and may crash if this is done. Also, some embedded
2021 PCI-based systems don't have any BIOS at all. Linux can also try to
2022 detect the PCI hardware directly without using the BIOS.
2024 With this option, you can specify how Linux should detect the
2025 PCI devices. If you choose "BIOS", the BIOS will be used,
2026 if you choose "Direct", the BIOS won't be used, and if you
2027 choose "MMConfig", then PCI Express MMCONFIG will be used.
2028 If you choose "Any", the kernel will try MMCONFIG, then the
2029 direct access method and falls back to the BIOS if that doesn't
2030 work. If unsure, go with the default, which is "Any".
2035 config PCI_GOMMCONFIG
2052 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2054 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2057 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2061 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2065 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2069 depends on PCI && XEN
2077 bool "Support mmconfig PCI config space access"
2078 depends on X86_64 && PCI && ACPI
2080 config PCI_CNB20LE_QUIRK
2081 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2084 Read the PCI windows out of the CNB20LE host bridge. This allows
2085 PCI hotplug to work on systems with the CNB20LE chipset which do
2088 There's no public spec for this chipset, and this functionality
2089 is known to be incomplete.
2091 You should say N unless you know you need this.
2093 source "drivers/pci/pcie/Kconfig"
2095 source "drivers/pci/Kconfig"
2097 # x86_64 have no ISA slots, but can have ISA-style DMA.
2099 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2102 Enables ISA-style DMA support for devices requiring such controllers.
2110 Find out whether you have ISA slots on your motherboard. ISA is the
2111 name of a bus system, i.e. the way the CPU talks to the other stuff
2112 inside your box. Other bus systems are PCI, EISA, MicroChannel
2113 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2114 newer boards don't support it. If you have ISA, say Y, otherwise N.
2120 The Extended Industry Standard Architecture (EISA) bus was
2121 developed as an open alternative to the IBM MicroChannel bus.
2123 The EISA bus provided some of the features of the IBM MicroChannel
2124 bus while maintaining backward compatibility with cards made for
2125 the older ISA bus. The EISA bus saw limited use between 1988 and
2126 1995 when it was made obsolete by the PCI bus.
2128 Say Y here if you are building a kernel for an EISA-based machine.
2132 source "drivers/eisa/Kconfig"
2135 tristate "NatSemi SCx200 support"
2137 This provides basic support for National Semiconductor's
2138 (now AMD's) Geode processors. The driver probes for the
2139 PCI-IDs of several on-chip devices, so its a good dependency
2140 for other scx200_* drivers.
2142 If compiled as a module, the driver is named scx200.
2144 config SCx200HR_TIMER
2145 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2149 This driver provides a clocksource built upon the on-chip
2150 27MHz high-resolution timer. Its also a workaround for
2151 NSC Geode SC-1100's buggy TSC, which loses time when the
2152 processor goes idle (as is done by the scheduler). The
2153 other workaround is idle=poll boot option.
2156 bool "One Laptop Per Child support"
2163 Add support for detecting the unique features of the OLPC
2167 bool "OLPC XO-1 Power Management"
2168 depends on OLPC && MFD_CS5535 && PM_SLEEP
2171 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2174 bool "OLPC XO-1 Real Time Clock"
2175 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2177 Add support for the XO-1 real time clock, which can be used as a
2178 programmable wakeup source.
2181 bool "OLPC XO-1 SCI extras"
2182 depends on OLPC && OLPC_XO1_PM
2188 Add support for SCI-based features of the OLPC XO-1 laptop:
2189 - EC-driven system wakeups
2193 - AC adapter status updates
2194 - Battery status updates
2196 config OLPC_XO15_SCI
2197 bool "OLPC XO-1.5 SCI extras"
2198 depends on OLPC && ACPI
2201 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2202 - EC-driven system wakeups
2203 - AC adapter status updates
2204 - Battery status updates
2207 bool "PCEngines ALIX System Support (LED setup)"
2210 This option enables system support for the PCEngines ALIX.
2211 At present this just sets up LEDs for GPIO control on
2212 ALIX2/3/6 boards. However, other system specific setup should
2215 Note: You must still enable the drivers for GPIO and LED support
2216 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2218 Note: You have to set alix.force=1 for boards with Award BIOS.
2221 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2224 This option enables system support for the Soekris Engineering net5501.
2227 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2231 This option enables system support for the Traverse Technologies GEOS.
2234 bool "Technologic Systems TS-5500 platform support"
2236 select CHECK_SIGNATURE
2240 This option enables system support for the Technologic Systems TS-5500.
2246 depends on CPU_SUP_AMD && PCI
2248 source "drivers/pcmcia/Kconfig"
2250 source "drivers/pci/hotplug/Kconfig"
2253 bool "RapidIO support"
2257 If you say Y here, the kernel will include drivers and
2258 infrastructure code to support RapidIO interconnect devices.
2260 source "drivers/rapidio/Kconfig"
2265 menu "Executable file formats / Emulations"
2267 source "fs/Kconfig.binfmt"
2269 config IA32_EMULATION
2270 bool "IA32 Emulation"
2272 select COMPAT_BINFMT_ELF
2275 Include code to run legacy 32-bit programs under a
2276 64-bit kernel. You should likely turn this on, unless you're
2277 100% sure that you don't have any 32-bit programs left.
2280 tristate "IA32 a.out support"
2281 depends on IA32_EMULATION
2283 Support old a.out binaries in the 32bit emulation.
2286 bool "x32 ABI for 64-bit mode"
2287 depends on X86_64 && IA32_EMULATION
2289 Include code to run binaries for the x32 native 32-bit ABI
2290 for 64-bit processors. An x32 process gets access to the
2291 full 64-bit register file and wide data path while leaving
2292 pointers at 32 bits for smaller memory footprint.
2294 You will need a recent binutils (2.22 or later) with
2295 elf32_x86_64 support enabled to compile a kernel with this
2300 depends on IA32_EMULATION || X86_X32
2301 select ARCH_WANT_OLD_COMPAT_IPC
2304 config COMPAT_FOR_U64_ALIGNMENT
2307 config SYSVIPC_COMPAT
2319 config HAVE_ATOMIC_IOMAP
2323 config HAVE_TEXT_POKE_SMP
2325 select STOP_MACHINE if SMP
2327 config X86_DEV_DMA_OPS
2329 depends on X86_64 || STA2X11
2331 config X86_DMA_REMAP
2335 source "net/Kconfig"
2337 source "drivers/Kconfig"
2339 source "drivers/firmware/Kconfig"
2343 source "arch/x86/Kconfig.debug"
2345 source "security/Kconfig"
2347 source "crypto/Kconfig"
2349 source "arch/x86/kvm/Kconfig"
2351 source "lib/Kconfig"
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blob