3 bool "64-bit kernel" if ARCH = "x86"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
18 select X86_DEV_DMA_OPS
23 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
24 select HAVE_AOUT if X86_32
25 select HAVE_UNSTABLE_SCHED_CLOCK
26 select ARCH_SUPPORTS_NUMA_BALANCING
27 select ARCH_WANTS_PROT_NUMA_PROT_NONE
30 select HAVE_PCSPKR_PLATFORM
31 select HAVE_PERF_EVENTS
32 select HAVE_IOREMAP_PROT
35 select HAVE_MEMBLOCK_NODE_MAP
36 select ARCH_DISCARD_MEMBLOCK
37 select ARCH_WANT_OPTIONAL_GPIOLIB
38 select ARCH_WANT_FRAME_POINTERS
40 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
41 select HAVE_KRETPROBES
43 select HAVE_KPROBES_ON_FTRACE
44 select HAVE_FTRACE_MCOUNT_RECORD
45 select HAVE_FENTRY if X86_64
46 select HAVE_C_RECORDMCOUNT
47 select HAVE_DYNAMIC_FTRACE
48 select HAVE_DYNAMIC_FTRACE_WITH_REGS
49 select HAVE_FUNCTION_TRACER
50 select HAVE_FUNCTION_GRAPH_TRACER
51 select HAVE_FUNCTION_GRAPH_FP_TEST
52 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
53 select HAVE_SYSCALL_TRACEPOINTS
54 select SYSCTL_EXCEPTION_TRACE
57 select HAVE_ARCH_TRACEHOOK
58 select HAVE_GENERIC_DMA_COHERENT if X86_32
59 select HAVE_EFFICIENT_UNALIGNED_ACCESS
60 select USER_STACKTRACE_SUPPORT
61 select HAVE_REGS_AND_STACK_ACCESS_API
62 select HAVE_DMA_API_DEBUG
63 select HAVE_KERNEL_GZIP
64 select HAVE_KERNEL_BZIP2
65 select HAVE_KERNEL_LZMA
67 select HAVE_KERNEL_LZO
68 select HAVE_KERNEL_LZ4
69 select HAVE_HW_BREAKPOINT
70 select HAVE_MIXED_BREAKPOINTS_REGS
72 select HAVE_PERF_EVENTS_NMI
74 select HAVE_PERF_USER_STACK_DUMP
75 select HAVE_DEBUG_KMEMLEAK
77 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
78 select HAVE_CMPXCHG_LOCAL
79 select HAVE_CMPXCHG_DOUBLE
80 select HAVE_ARCH_KMEMCHECK
81 select HAVE_USER_RETURN_NOTIFIER
82 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
83 select HAVE_ARCH_JUMP_LABEL
84 select HAVE_TEXT_POKE_SMP
85 select HAVE_GENERIC_HARDIRQS
86 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
88 select GENERIC_FIND_FIRST_BIT
89 select GENERIC_IRQ_PROBE
90 select GENERIC_PENDING_IRQ if SMP
91 select GENERIC_IRQ_SHOW
92 select GENERIC_CLOCKEVENTS_MIN_ADJUST
93 select IRQ_FORCED_THREADING
94 select USE_GENERIC_SMP_HELPERS if SMP
95 select HAVE_BPF_JIT if X86_64
96 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
98 select ARCH_HAVE_NMI_SAFE_CMPXCHG
100 select DCACHE_WORD_ACCESS
101 select GENERIC_SMP_IDLE_THREAD
102 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
103 select HAVE_ARCH_SECCOMP_FILTER
104 select BUILDTIME_EXTABLE_SORT
105 select GENERIC_CMOS_UPDATE
106 select HAVE_ARCH_SOFT_DIRTY
107 select CLOCKSOURCE_WATCHDOG
108 select GENERIC_CLOCKEVENTS
109 select ARCH_CLOCKSOURCE_DATA if X86_64
110 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
111 select GENERIC_TIME_VSYSCALL if X86_64
112 select KTIME_SCALAR if X86_32
113 select GENERIC_STRNCPY_FROM_USER
114 select GENERIC_STRNLEN_USER
115 select HAVE_CONTEXT_TRACKING if X86_64
116 select HAVE_IRQ_TIME_ACCOUNTING
118 select MODULES_USE_ELF_REL if X86_32
119 select MODULES_USE_ELF_RELA if X86_64
120 select CLONE_BACKWARDS if X86_32
121 select ARCH_USE_BUILTIN_BSWAP
122 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
123 select OLD_SIGACTION if X86_32
124 select COMPAT_OLD_SIGACTION if IA32_EMULATION
126 select HAVE_DEBUG_STACKOVERFLOW
128 config INSTRUCTION_DECODER
130 depends on KPROBES || PERF_EVENTS || UPROBES
134 default "elf32-i386" if X86_32
135 default "elf64-x86-64" if X86_64
137 config ARCH_DEFCONFIG
139 default "arch/x86/configs/i386_defconfig" if X86_32
140 default "arch/x86/configs/x86_64_defconfig" if X86_64
142 config LOCKDEP_SUPPORT
145 config STACKTRACE_SUPPORT
148 config HAVE_LATENCYTOP_SUPPORT
157 config NEED_DMA_MAP_STATE
159 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
161 config NEED_SG_DMA_LENGTH
164 config GENERIC_ISA_DMA
166 depends on ISA_DMA_API
171 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
173 config GENERIC_BUG_RELATIVE_POINTERS
176 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_CACHE_LINE_SIZE
195 config ARCH_HAS_CPU_AUTOPROBE
198 config HAVE_SETUP_PER_CPU_AREA
201 config NEED_PER_CPU_EMBED_FIRST_CHUNK
204 config NEED_PER_CPU_PAGE_FIRST_CHUNK
207 config ARCH_HIBERNATION_POSSIBLE
210 config ARCH_SUSPEND_POSSIBLE
213 config ARCH_WANT_HUGE_PMD_SHARE
216 config ARCH_WANT_GENERAL_HUGETLB
227 config ARCH_SUPPORTS_OPTIMIZED_INLINING
230 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
233 config HAVE_INTEL_TXT
235 depends on INTEL_IOMMU && ACPI
239 depends on X86_32 && SMP
243 depends on X86_64 && SMP
249 config X86_32_LAZY_GS
251 depends on X86_32 && !CC_STACKPROTECTOR
253 config ARCH_HWEIGHT_CFLAGS
255 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
256 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
258 config ARCH_CPU_PROBE_RELEASE
260 depends on HOTPLUG_CPU
262 config ARCH_SUPPORTS_UPROBES
265 source "init/Kconfig"
266 source "kernel/Kconfig.freezer"
268 menu "Processor type and features"
271 bool "DMA memory allocation support" if EXPERT
274 DMA memory allocation support allows devices with less than 32-bit
275 addressing to allocate within the first 16MB of address space.
276 Disable if no such devices will be used.
281 bool "Symmetric multi-processing support"
283 This enables support for systems with more than one CPU. If you have
284 a system with only one CPU, like most personal computers, say N. If
285 you have a system with more than one CPU, say Y.
287 If you say N here, the kernel will run on single and multiprocessor
288 machines, but will use only one CPU of a multiprocessor machine. If
289 you say Y here, the kernel will run on many, but not all,
290 singleprocessor machines. On a singleprocessor machine, the kernel
291 will run faster if you say N here.
293 Note that if you say Y here and choose architecture "586" or
294 "Pentium" under "Processor family", the kernel will not work on 486
295 architectures. Similarly, multiprocessor kernels for the "PPro"
296 architecture may not work on all Pentium based boards.
298 People using multiprocessor machines who say Y here should also say
299 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
300 Management" code will be disabled if you say Y here.
302 See also <file:Documentation/x86/i386/IO-APIC.txt>,
303 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
304 <http://www.tldp.org/docs.html#howto>.
306 If you don't know what to do here, say N.
309 bool "Support x2apic"
310 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
312 This enables x2apic support on CPUs that have this feature.
314 This allows 32-bit apic IDs (so it can support very large systems),
315 and accesses the local apic via MSRs not via mmio.
317 If you don't know what to do here, say N.
320 bool "Enable MPS table" if ACPI || SFI
322 depends on X86_LOCAL_APIC
324 For old smp systems that do not have proper acpi support. Newer systems
325 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
328 bool "Support for big SMP systems with more than 8 CPUs"
329 depends on X86_32 && SMP
331 This option is needed for the systems that have more than 8 CPUs
335 depends on X86_GOLDFISH
338 config X86_EXTENDED_PLATFORM
339 bool "Support for extended (non-PC) x86 platforms"
342 If you disable this option then the kernel will only support
343 standard PC platforms. (which covers the vast majority of
346 If you enable this option then you'll be able to select support
347 for the following (non-PC) 32 bit x86 platforms:
348 Goldfish (Android emulator)
352 SGI 320/540 (Visual Workstation)
353 STA2X11-based (e.g. Northville)
354 Summit/EXA (IBM x440)
355 Unisys ES7000 IA32 series
356 Moorestown MID devices
358 If you have one of these systems, or if you want to build a
359 generic distribution kernel, say Y here - otherwise say N.
363 config X86_EXTENDED_PLATFORM
364 bool "Support for extended (non-PC) x86 platforms"
367 If you disable this option then the kernel will only support
368 standard PC platforms. (which covers the vast majority of
371 If you enable this option then you'll be able to select support
372 for the following (non-PC) 64 bit x86 platforms:
377 If you have one of these systems, or if you want to build a
378 generic distribution kernel, say Y here - otherwise say N.
380 # This is an alphabetically sorted list of 64 bit extended platforms
381 # Please maintain the alphabetic order if and when there are additions
383 bool "Numascale NumaChip"
385 depends on X86_EXTENDED_PLATFORM
388 depends on X86_X2APIC
389 depends on PCI_MMCONFIG
391 Adds support for Numascale NumaChip large-SMP systems. Needed to
392 enable more than ~168 cores.
393 If you don't have one of these, you should say N here.
397 select HYPERVISOR_GUEST
399 depends on X86_64 && PCI
400 depends on X86_EXTENDED_PLATFORM
403 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
404 supposed to run on these EM64T-based machines. Only choose this option
405 if you have one of these machines.
408 bool "SGI Ultraviolet"
410 depends on X86_EXTENDED_PLATFORM
412 depends on X86_X2APIC
414 This option is needed in order to support SGI Ultraviolet systems.
415 If you don't have one of these, you should say N here.
417 # Following is an alphabetically sorted list of 32 bit extended platforms
418 # Please maintain the alphabetic order if and when there are additions
421 bool "Goldfish (Virtual Platform)"
423 depends on X86_EXTENDED_PLATFORM
425 Enable support for the Goldfish virtual platform used primarily
426 for Android development. Unless you are building for the Android
427 Goldfish emulator say N here.
430 bool "CE4100 TV platform"
432 depends on PCI_GODIRECT
434 depends on X86_EXTENDED_PLATFORM
435 select X86_REBOOTFIXUPS
437 select OF_EARLY_FLATTREE
440 Select for the Intel CE media processor (CE4100) SOC.
441 This option compiles in support for the CE4100 SOC for settop
442 boxes and media devices.
444 config X86_WANT_INTEL_MID
445 bool "Intel MID platform support"
447 depends on X86_EXTENDED_PLATFORM
449 Select to build a kernel capable of supporting Intel MID platform
450 systems which do not have the PCI legacy interfaces (Moorestown,
451 Medfield). If you are building for a PC class system say N here.
453 if X86_WANT_INTEL_MID
459 bool "Medfield MID platform"
462 depends on X86_IO_APIC
470 select X86_PLATFORM_DEVICES
471 select MFD_INTEL_MSIC
473 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
474 Internet Device(MID) platform.
475 Unlike standard x86 PCs, Medfield does not have many legacy devices
476 nor standard legacy replacement devices/features. e.g. Medfield does
477 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
481 config X86_INTEL_LPSS
482 bool "Intel Low Power Subsystem Support"
486 Select to build support for Intel Low Power Subsystem such as
487 found on Intel Lynxpoint PCH. Selecting this option enables
488 things like clock tree (common clock framework) which are needed
489 by the LPSS peripheral drivers.
492 bool "RDC R-321x SoC"
494 depends on X86_EXTENDED_PLATFORM
496 select X86_REBOOTFIXUPS
498 This option is needed for RDC R-321x system-on-chip, also known
500 If you don't have one of these chips, you should say N here.
502 config X86_32_NON_STANDARD
503 bool "Support non-standard 32-bit SMP architectures"
504 depends on X86_32 && SMP
505 depends on X86_EXTENDED_PLATFORM
507 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
508 STA2X11, default subarchitectures. It is intended for a generic
509 binary kernel. If you select them all, kernel will probe it
510 one by one and will fallback to default.
512 # Alphabetically sorted list of Non standard 32 bit platforms
515 bool "NUMAQ (IBM/Sequent)"
516 depends on X86_32_NON_STANDARD
521 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
522 NUMA multiquad box. This changes the way that processors are
523 bootstrapped, and uses Clustered Logical APIC addressing mode instead
524 of Flat Logical. You will need a new lynxer.elf file to flash your
525 firmware with - send email to <Martin.Bligh@us.ibm.com>.
527 config X86_SUPPORTS_MEMORY_FAILURE
529 # MCE code calls memory_failure():
531 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
532 depends on !X86_NUMAQ
533 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
534 depends on X86_64 || !SPARSEMEM
535 select ARCH_SUPPORTS_MEMORY_FAILURE
538 bool "SGI 320/540 (Visual Workstation)"
539 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
540 depends on X86_32_NON_STANDARD
542 The SGI Visual Workstation series is an IA32-based workstation
543 based on SGI systems chips with some legacy PC hardware attached.
545 Say Y here to create a kernel to run on the SGI 320 or 540.
547 A kernel compiled for the Visual Workstation will run on general
548 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
551 bool "STA2X11 Companion Chip Support"
552 depends on X86_32_NON_STANDARD && PCI
553 select X86_DEV_DMA_OPS
557 select ARCH_REQUIRE_GPIOLIB
560 This adds support for boards based on the STA2X11 IO-Hub,
561 a.k.a. "ConneXt". The chip is used in place of the standard
562 PC chipset, so all "standard" peripherals are missing. If this
563 option is selected the kernel will still be able to boot on
564 standard PC machines.
567 bool "Summit/EXA (IBM x440)"
568 depends on X86_32_NON_STANDARD
570 This option is needed for IBM systems that use the Summit/EXA chipset.
571 In particular, it is needed for the x440.
574 bool "Unisys ES7000 IA32 series"
575 depends on X86_32_NON_STANDARD && X86_BIGSMP
577 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
578 supposed to run on an IA32-based Unisys ES7000 system.
581 tristate "Eurobraille/Iris poweroff module"
584 The Iris machines from EuroBraille do not have APM or ACPI support
585 to shut themselves down properly. A special I/O sequence is
586 needed to do so, which is what this module does at
589 This is only for Iris machines from EuroBraille.
593 config SCHED_OMIT_FRAME_POINTER
595 prompt "Single-depth WCHAN output"
598 Calculate simpler /proc/<PID>/wchan values. If this option
599 is disabled then wchan values will recurse back to the
600 caller function. This provides more accurate wchan values,
601 at the expense of slightly more scheduling overhead.
603 If in doubt, say "Y".
605 menuconfig HYPERVISOR_GUEST
606 bool "Linux guest support"
608 Say Y here to enable options for running Linux under various hyper-
609 visors. This option enables basic hypervisor detection and platform
612 If you say N, all options in this submenu will be skipped and
613 disabled, and Linux guest support won't be built in.
618 bool "Enable paravirtualization code"
620 This changes the kernel so it can modify itself when it is run
621 under a hypervisor, potentially improving performance significantly
622 over full virtualization. However, when run without a hypervisor
623 the kernel is theoretically slower and slightly larger.
625 config PARAVIRT_DEBUG
626 bool "paravirt-ops debugging"
627 depends on PARAVIRT && DEBUG_KERNEL
629 Enable to debug paravirt_ops internals. Specifically, BUG if
630 a paravirt_op is missing when it is called.
632 config PARAVIRT_SPINLOCKS
633 bool "Paravirtualization layer for spinlocks"
634 depends on PARAVIRT && SMP
636 Paravirtualized spinlocks allow a pvops backend to replace the
637 spinlock implementation with something virtualization-friendly
638 (for example, block the virtual CPU rather than spinning).
640 Unfortunately the downside is an up to 5% performance hit on
641 native kernels, with various workloads.
643 If you are unsure how to answer this question, answer N.
645 source "arch/x86/xen/Kconfig"
648 bool "KVM Guest support (including kvmclock)"
650 select PARAVIRT_CLOCK
653 This option enables various optimizations for running under the KVM
654 hypervisor. It includes a paravirtualized clock, so that instead
655 of relying on a PIT (or probably other) emulation by the
656 underlying device model, the host provides the guest with
657 timing infrastructure such as time of day, and system time
659 source "arch/x86/lguest/Kconfig"
661 config PARAVIRT_TIME_ACCOUNTING
662 bool "Paravirtual steal time accounting"
666 Select this option to enable fine granularity task steal time
667 accounting. Time spent executing other tasks in parallel with
668 the current vCPU is discounted from the vCPU power. To account for
669 that, there can be a small performance impact.
671 If in doubt, say N here.
673 config PARAVIRT_CLOCK
676 endif #HYPERVISOR_GUEST
684 This option adds a kernel parameter 'memtest', which allows memtest
686 memtest=0, mean disabled; -- default
687 memtest=1, mean do 1 test pattern;
689 memtest=4, mean do 4 test patterns.
690 If you are unsure how to answer this question, answer N.
692 config X86_SUMMIT_NUMA
694 depends on X86_32 && NUMA && X86_32_NON_STANDARD
696 config X86_CYCLONE_TIMER
698 depends on X86_SUMMIT
700 source "arch/x86/Kconfig.cpu"
704 prompt "HPET Timer Support" if X86_32
706 Use the IA-PC HPET (High Precision Event Timer) to manage
707 time in preference to the PIT and RTC, if a HPET is
709 HPET is the next generation timer replacing legacy 8254s.
710 The HPET provides a stable time base on SMP
711 systems, unlike the TSC, but it is more expensive to access,
712 as it is off-chip. You can find the HPET spec at
713 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
715 You can safely choose Y here. However, HPET will only be
716 activated if the platform and the BIOS support this feature.
717 Otherwise the 8254 will be used for timing services.
719 Choose N to continue using the legacy 8254 timer.
721 config HPET_EMULATE_RTC
723 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
726 def_bool y if X86_INTEL_MID
727 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
729 depends on X86_INTEL_MID && SFI
731 APB timer is the replacement for 8254, HPET on X86 MID platforms.
732 The APBT provides a stable time base on SMP
733 systems, unlike the TSC, but it is more expensive to access,
734 as it is off-chip. APB timers are always running regardless of CPU
735 C states, they are used as per CPU clockevent device when possible.
737 # Mark as expert because too many people got it wrong.
738 # The code disables itself when not needed.
741 bool "Enable DMI scanning" if EXPERT
743 Enabled scanning of DMI to identify machine quirks. Say Y
744 here unless you have verified that your setup is not
745 affected by entries in the DMI blacklist. Required by PNP
749 bool "GART IOMMU support" if EXPERT
752 depends on X86_64 && PCI && AMD_NB
754 Support for full DMA access of devices with 32bit memory access only
755 on systems with more than 3GB. This is usually needed for USB,
756 sound, many IDE/SATA chipsets and some other devices.
757 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
758 based hardware IOMMU and a software bounce buffer based IOMMU used
759 on Intel systems and as fallback.
760 The code is only active when needed (enough memory and limited
761 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
765 bool "IBM Calgary IOMMU support"
767 depends on X86_64 && PCI
769 Support for hardware IOMMUs in IBM's xSeries x366 and x460
770 systems. Needed to run systems with more than 3GB of memory
771 properly with 32-bit PCI devices that do not support DAC
772 (Double Address Cycle). Calgary also supports bus level
773 isolation, where all DMAs pass through the IOMMU. This
774 prevents them from going anywhere except their intended
775 destination. This catches hard-to-find kernel bugs and
776 mis-behaving drivers and devices that do not use the DMA-API
777 properly to set up their DMA buffers. The IOMMU can be
778 turned off at boot time with the iommu=off parameter.
779 Normally the kernel will make the right choice by itself.
782 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
784 prompt "Should Calgary be enabled by default?"
785 depends on CALGARY_IOMMU
787 Should Calgary be enabled by default? if you choose 'y', Calgary
788 will be used (if it exists). If you choose 'n', Calgary will not be
789 used even if it exists. If you choose 'n' and would like to use
790 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
793 # need this always selected by IOMMU for the VIA workaround
797 Support for software bounce buffers used on x86-64 systems
798 which don't have a hardware IOMMU. Using this PCI devices
799 which can only access 32-bits of memory can be used on systems
800 with more than 3 GB of memory.
805 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
808 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
809 depends on X86_64 && SMP && DEBUG_KERNEL
810 select CPUMASK_OFFSTACK
812 Enable maximum number of CPUS and NUMA Nodes for this architecture.
816 int "Maximum number of CPUs" if SMP && !MAXSMP
817 range 2 8 if SMP && X86_32 && !X86_BIGSMP
818 range 2 512 if SMP && !MAXSMP
820 default "4096" if MAXSMP
821 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
824 This allows you to specify the maximum number of CPUs which this
825 kernel will support. The maximum supported value is 512 and the
826 minimum value which makes sense is 2.
828 This is purely to save memory - each supported CPU adds
829 approximately eight kilobytes to the kernel image.
832 bool "SMT (Hyperthreading) scheduler support"
835 SMT scheduler support improves the CPU scheduler's decision making
836 when dealing with Intel Pentium 4 chips with HyperThreading at a
837 cost of slightly increased overhead in some places. If unsure say
842 prompt "Multi-core scheduler support"
845 Multi-core scheduler support improves the CPU scheduler's decision
846 making when dealing with multi-core CPU chips at a cost of slightly
847 increased overhead in some places. If unsure say N here.
849 source "kernel/Kconfig.preempt"
852 bool "Local APIC support on uniprocessors"
853 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
855 A local APIC (Advanced Programmable Interrupt Controller) is an
856 integrated interrupt controller in the CPU. If you have a single-CPU
857 system which has a processor with a local APIC, you can say Y here to
858 enable and use it. If you say Y here even though your machine doesn't
859 have a local APIC, then the kernel will still run with no slowdown at
860 all. The local APIC supports CPU-generated self-interrupts (timer,
861 performance counters), and the NMI watchdog which detects hard
865 bool "IO-APIC support on uniprocessors"
866 depends on X86_UP_APIC
868 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
869 SMP-capable replacement for PC-style interrupt controllers. Most
870 SMP systems and many recent uniprocessor systems have one.
872 If you have a single-CPU system with an IO-APIC, you can say Y here
873 to use it. If you say Y here even though your machine doesn't have
874 an IO-APIC, then the kernel will still run with no slowdown at all.
876 config X86_LOCAL_APIC
878 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
882 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
884 config X86_VISWS_APIC
886 depends on X86_32 && X86_VISWS
888 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
889 bool "Reroute for broken boot IRQs"
890 depends on X86_IO_APIC
892 This option enables a workaround that fixes a source of
893 spurious interrupts. This is recommended when threaded
894 interrupt handling is used on systems where the generation of
895 superfluous "boot interrupts" cannot be disabled.
897 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
898 entry in the chipset's IO-APIC is masked (as, e.g. the RT
899 kernel does during interrupt handling). On chipsets where this
900 boot IRQ generation cannot be disabled, this workaround keeps
901 the original IRQ line masked so that only the equivalent "boot
902 IRQ" is delivered to the CPUs. The workaround also tells the
903 kernel to set up the IRQ handler on the boot IRQ line. In this
904 way only one interrupt is delivered to the kernel. Otherwise
905 the spurious second interrupt may cause the kernel to bring
906 down (vital) interrupt lines.
908 Only affects "broken" chipsets. Interrupt sharing may be
909 increased on these systems.
912 bool "Machine Check / overheating reporting"
915 Machine Check support allows the processor to notify the
916 kernel if it detects a problem (e.g. overheating, data corruption).
917 The action the kernel takes depends on the severity of the problem,
918 ranging from warning messages to halting the machine.
922 prompt "Intel MCE features"
923 depends on X86_MCE && X86_LOCAL_APIC
925 Additional support for intel specific MCE features such as
930 prompt "AMD MCE features"
931 depends on X86_MCE && X86_LOCAL_APIC
933 Additional support for AMD specific MCE features such as
934 the DRAM Error Threshold.
936 config X86_ANCIENT_MCE
937 bool "Support for old Pentium 5 / WinChip machine checks"
938 depends on X86_32 && X86_MCE
940 Include support for machine check handling on old Pentium 5 or WinChip
941 systems. These typically need to be enabled explicitely on the command
944 config X86_MCE_THRESHOLD
945 depends on X86_MCE_AMD || X86_MCE_INTEL
948 config X86_MCE_INJECT
950 tristate "Machine check injector support"
952 Provide support for injecting machine checks for testing purposes.
953 If you don't know what a machine check is and you don't do kernel
954 QA it is safe to say n.
956 config X86_THERMAL_VECTOR
958 depends on X86_MCE_INTEL
961 bool "Enable VM86 support" if EXPERT
965 This option is required by programs like DOSEMU to run 16-bit legacy
966 code on X86 processors. It also may be needed by software like
967 XFree86 to initialize some video cards via BIOS. Disabling this
968 option saves about 6k.
971 tristate "Toshiba Laptop support"
974 This adds a driver to safely access the System Management Mode of
975 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
976 not work on models with a Phoenix BIOS. The System Management Mode
977 is used to set the BIOS and power saving options on Toshiba portables.
979 For information on utilities to make use of this driver see the
980 Toshiba Linux utilities web site at:
981 <http://www.buzzard.org.uk/toshiba/>.
983 Say Y if you intend to run this kernel on a Toshiba portable.
987 tristate "Dell laptop support"
990 This adds a driver to safely access the System Management Mode
991 of the CPU on the Dell Inspiron 8000. The System Management Mode
992 is used to read cpu temperature and cooling fan status and to
993 control the fans on the I8K portables.
995 This driver has been tested only on the Inspiron 8000 but it may
996 also work with other Dell laptops. You can force loading on other
997 models by passing the parameter `force=1' to the module. Use at
1000 For information on utilities to make use of this driver see the
1001 I8K Linux utilities web site at:
1002 <http://people.debian.org/~dz/i8k/>
1004 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
1007 config X86_REBOOTFIXUPS
1008 bool "Enable X86 board specific fixups for reboot"
1011 This enables chipset and/or board specific fixups to be done
1012 in order to get reboot to work correctly. This is only needed on
1013 some combinations of hardware and BIOS. The symptom, for which
1014 this config is intended, is when reboot ends with a stalled/hung
1017 Currently, the only fixup is for the Geode machines using
1018 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1020 Say Y if you want to enable the fixup. Currently, it's safe to
1021 enable this option even if you don't need it.
1025 tristate "CPU microcode loading support"
1029 If you say Y here, you will be able to update the microcode on
1030 certain Intel and AMD processors. The Intel support is for the
1031 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1032 Xeon etc. The AMD support is for families 0x10 and later. You will
1033 obviously need the actual microcode binary data itself which is not
1034 shipped with the Linux kernel.
1036 This option selects the general module only, you need to select
1037 at least one vendor specific module as well.
1039 To compile this driver as a module, choose M here: the module
1040 will be called microcode.
1042 config MICROCODE_INTEL
1043 bool "Intel microcode loading support"
1044 depends on MICROCODE
1048 This options enables microcode patch loading support for Intel
1051 For latest news and information on obtaining all the required
1052 Intel ingredients for this driver, check:
1053 <http://www.urbanmyth.org/microcode/>.
1055 config MICROCODE_AMD
1056 bool "AMD microcode loading support"
1057 depends on MICROCODE
1060 If you select this option, microcode patch loading support for AMD
1061 processors will be enabled.
1063 config MICROCODE_OLD_INTERFACE
1065 depends on MICROCODE
1067 config MICROCODE_INTEL_LIB
1069 depends on MICROCODE_INTEL
1071 config MICROCODE_INTEL_EARLY
1074 config MICROCODE_AMD_EARLY
1077 config MICROCODE_EARLY
1078 bool "Early load microcode"
1079 depends on MICROCODE=y && BLK_DEV_INITRD
1080 select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1081 select MICROCODE_AMD_EARLY if MICROCODE_AMD
1084 This option provides functionality to read additional microcode data
1085 at the beginning of initrd image. The data tells kernel to load
1086 microcode to CPU's as early as possible. No functional change if no
1087 microcode data is glued to the initrd, therefore it's safe to say Y.
1090 tristate "/dev/cpu/*/msr - Model-specific register support"
1092 This device gives privileged processes access to the x86
1093 Model-Specific Registers (MSRs). It is a character device with
1094 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1095 MSR accesses are directed to a specific CPU on multi-processor
1099 tristate "/dev/cpu/*/cpuid - CPU information support"
1101 This device gives processes access to the x86 CPUID instruction to
1102 be executed on a specific processor. It is a character device
1103 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1107 prompt "High Memory Support"
1108 default HIGHMEM64G if X86_NUMAQ
1114 depends on !X86_NUMAQ
1116 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1117 However, the address space of 32-bit x86 processors is only 4
1118 Gigabytes large. That means that, if you have a large amount of
1119 physical memory, not all of it can be "permanently mapped" by the
1120 kernel. The physical memory that's not permanently mapped is called
1123 If you are compiling a kernel which will never run on a machine with
1124 more than 1 Gigabyte total physical RAM, answer "off" here (default
1125 choice and suitable for most users). This will result in a "3GB/1GB"
1126 split: 3GB are mapped so that each process sees a 3GB virtual memory
1127 space and the remaining part of the 4GB virtual memory space is used
1128 by the kernel to permanently map as much physical memory as
1131 If the machine has between 1 and 4 Gigabytes physical RAM, then
1134 If more than 4 Gigabytes is used then answer "64GB" here. This
1135 selection turns Intel PAE (Physical Address Extension) mode on.
1136 PAE implements 3-level paging on IA32 processors. PAE is fully
1137 supported by Linux, PAE mode is implemented on all recent Intel
1138 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1139 then the kernel will not boot on CPUs that don't support PAE!
1141 The actual amount of total physical memory will either be
1142 auto detected or can be forced by using a kernel command line option
1143 such as "mem=256M". (Try "man bootparam" or see the documentation of
1144 your boot loader (lilo or loadlin) about how to pass options to the
1145 kernel at boot time.)
1147 If unsure, say "off".
1151 depends on !X86_NUMAQ
1153 Select this if you have a 32-bit processor and between 1 and 4
1154 gigabytes of physical RAM.
1161 Select this if you have a 32-bit processor and more than 4
1162 gigabytes of physical RAM.
1167 prompt "Memory split" if EXPERT
1171 Select the desired split between kernel and user memory.
1173 If the address range available to the kernel is less than the
1174 physical memory installed, the remaining memory will be available
1175 as "high memory". Accessing high memory is a little more costly
1176 than low memory, as it needs to be mapped into the kernel first.
1177 Note that increasing the kernel address space limits the range
1178 available to user programs, making the address space there
1179 tighter. Selecting anything other than the default 3G/1G split
1180 will also likely make your kernel incompatible with binary-only
1183 If you are not absolutely sure what you are doing, leave this
1187 bool "3G/1G user/kernel split"
1188 config VMSPLIT_3G_OPT
1190 bool "3G/1G user/kernel split (for full 1G low memory)"
1192 bool "2G/2G user/kernel split"
1193 config VMSPLIT_2G_OPT
1195 bool "2G/2G user/kernel split (for full 2G low memory)"
1197 bool "1G/3G user/kernel split"
1202 default 0xB0000000 if VMSPLIT_3G_OPT
1203 default 0x80000000 if VMSPLIT_2G
1204 default 0x78000000 if VMSPLIT_2G_OPT
1205 default 0x40000000 if VMSPLIT_1G
1211 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1214 bool "PAE (Physical Address Extension) Support"
1215 depends on X86_32 && !HIGHMEM4G
1217 PAE is required for NX support, and furthermore enables
1218 larger swapspace support for non-overcommit purposes. It
1219 has the cost of more pagetable lookup overhead, and also
1220 consumes more pagetable space per process.
1222 config ARCH_PHYS_ADDR_T_64BIT
1224 depends on X86_64 || X86_PAE
1226 config ARCH_DMA_ADDR_T_64BIT
1228 depends on X86_64 || HIGHMEM64G
1230 config DIRECT_GBPAGES
1231 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1235 Allow the kernel linear mapping to use 1GB pages on CPUs that
1236 support it. This can improve the kernel's performance a tiny bit by
1237 reducing TLB pressure. If in doubt, say "Y".
1239 # Common NUMA Features
1241 bool "Numa Memory Allocation and Scheduler Support"
1243 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI))
1244 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1246 Enable NUMA (Non Uniform Memory Access) support.
1248 The kernel will try to allocate memory used by a CPU on the
1249 local memory controller of the CPU and add some more
1250 NUMA awareness to the kernel.
1252 For 64-bit this is recommended if the system is Intel Core i7
1253 (or later), AMD Opteron, or EM64T NUMA.
1255 For 32-bit this is only needed on (rare) 32-bit-only platforms
1256 that support NUMA topologies, such as NUMAQ / Summit, or if you
1257 boot a 32-bit kernel on a 64-bit NUMA platform.
1259 Otherwise, you should say N.
1261 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1262 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1266 prompt "Old style AMD Opteron NUMA detection"
1267 depends on X86_64 && NUMA && PCI
1269 Enable AMD NUMA node topology detection. You should say Y here if
1270 you have a multi processor AMD system. This uses an old method to
1271 read the NUMA configuration directly from the builtin Northbridge
1272 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1273 which also takes priority if both are compiled in.
1275 config X86_64_ACPI_NUMA
1277 prompt "ACPI NUMA detection"
1278 depends on X86_64 && NUMA && ACPI && PCI
1281 Enable ACPI SRAT based node topology detection.
1283 # Some NUMA nodes have memory ranges that span
1284 # other nodes. Even though a pfn is valid and
1285 # between a node's start and end pfns, it may not
1286 # reside on that node. See memmap_init_zone()
1288 config NODES_SPAN_OTHER_NODES
1290 depends on X86_64_ACPI_NUMA
1293 bool "NUMA emulation"
1296 Enable NUMA emulation. A flat machine will be split
1297 into virtual nodes when booted with "numa=fake=N", where N is the
1298 number of nodes. This is only useful for debugging.
1301 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1303 default "10" if MAXSMP
1304 default "6" if X86_64
1305 default "4" if X86_NUMAQ
1307 depends on NEED_MULTIPLE_NODES
1309 Specify the maximum number of NUMA Nodes available on the target
1310 system. Increases memory reserved to accommodate various tables.
1312 config ARCH_HAVE_MEMORY_PRESENT
1314 depends on X86_32 && DISCONTIGMEM
1316 config NEED_NODE_MEMMAP_SIZE
1318 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1320 config ARCH_FLATMEM_ENABLE
1322 depends on X86_32 && !NUMA
1324 config ARCH_DISCONTIGMEM_ENABLE
1326 depends on NUMA && X86_32
1328 config ARCH_DISCONTIGMEM_DEFAULT
1330 depends on NUMA && X86_32
1332 config ARCH_SPARSEMEM_ENABLE
1334 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1335 select SPARSEMEM_STATIC if X86_32
1336 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1338 config ARCH_SPARSEMEM_DEFAULT
1342 config ARCH_SELECT_MEMORY_MODEL
1344 depends on ARCH_SPARSEMEM_ENABLE
1346 config ARCH_MEMORY_PROBE
1348 depends on X86_64 && MEMORY_HOTPLUG
1350 config ARCH_PROC_KCORE_TEXT
1352 depends on X86_64 && PROC_KCORE
1354 config ILLEGAL_POINTER_VALUE
1357 default 0xdead000000000000 if X86_64
1362 bool "Allocate 3rd-level pagetables from highmem"
1365 The VM uses one page table entry for each page of physical memory.
1366 For systems with a lot of RAM, this can be wasteful of precious
1367 low memory. Setting this option will put user-space page table
1368 entries in high memory.
1370 config X86_CHECK_BIOS_CORRUPTION
1371 bool "Check for low memory corruption"
1373 Periodically check for memory corruption in low memory, which
1374 is suspected to be caused by BIOS. Even when enabled in the
1375 configuration, it is disabled at runtime. Enable it by
1376 setting "memory_corruption_check=1" on the kernel command
1377 line. By default it scans the low 64k of memory every 60
1378 seconds; see the memory_corruption_check_size and
1379 memory_corruption_check_period parameters in
1380 Documentation/kernel-parameters.txt to adjust this.
1382 When enabled with the default parameters, this option has
1383 almost no overhead, as it reserves a relatively small amount
1384 of memory and scans it infrequently. It both detects corruption
1385 and prevents it from affecting the running system.
1387 It is, however, intended as a diagnostic tool; if repeatable
1388 BIOS-originated corruption always affects the same memory,
1389 you can use memmap= to prevent the kernel from using that
1392 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1393 bool "Set the default setting of memory_corruption_check"
1394 depends on X86_CHECK_BIOS_CORRUPTION
1397 Set whether the default state of memory_corruption_check is
1400 config X86_RESERVE_LOW
1401 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1405 Specify the amount of low memory to reserve for the BIOS.
1407 The first page contains BIOS data structures that the kernel
1408 must not use, so that page must always be reserved.
1410 By default we reserve the first 64K of physical RAM, as a
1411 number of BIOSes are known to corrupt that memory range
1412 during events such as suspend/resume or monitor cable
1413 insertion, so it must not be used by the kernel.
1415 You can set this to 4 if you are absolutely sure that you
1416 trust the BIOS to get all its memory reservations and usages
1417 right. If you know your BIOS have problems beyond the
1418 default 64K area, you can set this to 640 to avoid using the
1419 entire low memory range.
1421 If you have doubts about the BIOS (e.g. suspend/resume does
1422 not work or there's kernel crashes after certain hardware
1423 hotplug events) then you might want to enable
1424 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1425 typical corruption patterns.
1427 Leave this to the default value of 64 if you are unsure.
1429 config MATH_EMULATION
1431 prompt "Math emulation" if X86_32
1433 Linux can emulate a math coprocessor (used for floating point
1434 operations) if you don't have one. 486DX and Pentium processors have
1435 a math coprocessor built in, 486SX and 386 do not, unless you added
1436 a 487DX or 387, respectively. (The messages during boot time can
1437 give you some hints here ["man dmesg"].) Everyone needs either a
1438 coprocessor or this emulation.
1440 If you don't have a math coprocessor, you need to say Y here; if you
1441 say Y here even though you have a coprocessor, the coprocessor will
1442 be used nevertheless. (This behavior can be changed with the kernel
1443 command line option "no387", which comes handy if your coprocessor
1444 is broken. Try "man bootparam" or see the documentation of your boot
1445 loader (lilo or loadlin) about how to pass options to the kernel at
1446 boot time.) This means that it is a good idea to say Y here if you
1447 intend to use this kernel on different machines.
1449 More information about the internals of the Linux math coprocessor
1450 emulation can be found in <file:arch/x86/math-emu/README>.
1452 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1453 kernel, it won't hurt.
1457 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1459 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1460 the Memory Type Range Registers (MTRRs) may be used to control
1461 processor access to memory ranges. This is most useful if you have
1462 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1463 allows bus write transfers to be combined into a larger transfer
1464 before bursting over the PCI/AGP bus. This can increase performance
1465 of image write operations 2.5 times or more. Saying Y here creates a
1466 /proc/mtrr file which may be used to manipulate your processor's
1467 MTRRs. Typically the X server should use this.
1469 This code has a reasonably generic interface so that similar
1470 control registers on other processors can be easily supported
1473 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1474 Registers (ARRs) which provide a similar functionality to MTRRs. For
1475 these, the ARRs are used to emulate the MTRRs.
1476 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1477 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1478 write-combining. All of these processors are supported by this code
1479 and it makes sense to say Y here if you have one of them.
1481 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1482 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1483 can lead to all sorts of problems, so it's good to say Y here.
1485 You can safely say Y even if your machine doesn't have MTRRs, you'll
1486 just add about 9 KB to your kernel.
1488 See <file:Documentation/x86/mtrr.txt> for more information.
1490 config MTRR_SANITIZER
1492 prompt "MTRR cleanup support"
1495 Convert MTRR layout from continuous to discrete, so X drivers can
1496 add writeback entries.
1498 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1499 The largest mtrr entry size for a continuous block can be set with
1504 config MTRR_SANITIZER_ENABLE_DEFAULT
1505 int "MTRR cleanup enable value (0-1)"
1508 depends on MTRR_SANITIZER
1510 Enable mtrr cleanup default value
1512 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1513 int "MTRR cleanup spare reg num (0-7)"
1516 depends on MTRR_SANITIZER
1518 mtrr cleanup spare entries default, it can be changed via
1519 mtrr_spare_reg_nr=N on the kernel command line.
1523 prompt "x86 PAT support" if EXPERT
1526 Use PAT attributes to setup page level cache control.
1528 PATs are the modern equivalents of MTRRs and are much more
1529 flexible than MTRRs.
1531 Say N here if you see bootup problems (boot crash, boot hang,
1532 spontaneous reboots) or a non-working video driver.
1536 config ARCH_USES_PG_UNCACHED
1542 prompt "x86 architectural random number generator" if EXPERT
1544 Enable the x86 architectural RDRAND instruction
1545 (Intel Bull Mountain technology) to generate random numbers.
1546 If supported, this is a high bandwidth, cryptographically
1547 secure hardware random number generator.
1551 prompt "Supervisor Mode Access Prevention" if EXPERT
1553 Supervisor Mode Access Prevention (SMAP) is a security
1554 feature in newer Intel processors. There is a small
1555 performance cost if this enabled and turned on; there is
1556 also a small increase in the kernel size if this is enabled.
1561 bool "EFI runtime service support"
1565 This enables the kernel to use EFI runtime services that are
1566 available (such as the EFI variable services).
1568 This option is only useful on systems that have EFI firmware.
1569 In addition, you should use the latest ELILO loader available
1570 at <http://elilo.sourceforge.net> in order to take advantage
1571 of EFI runtime services. However, even with this option, the
1572 resultant kernel should continue to boot on existing non-EFI
1576 bool "EFI stub support"
1579 This kernel feature allows a bzImage to be loaded directly
1580 by EFI firmware without the use of a bootloader.
1582 See Documentation/x86/efi-stub.txt for more information.
1586 prompt "Enable seccomp to safely compute untrusted bytecode"
1588 This kernel feature is useful for number crunching applications
1589 that may need to compute untrusted bytecode during their
1590 execution. By using pipes or other transports made available to
1591 the process as file descriptors supporting the read/write
1592 syscalls, it's possible to isolate those applications in
1593 their own address space using seccomp. Once seccomp is
1594 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1595 and the task is only allowed to execute a few safe syscalls
1596 defined by each seccomp mode.
1598 If unsure, say Y. Only embedded should say N here.
1600 config CC_STACKPROTECTOR
1601 bool "Enable -fstack-protector buffer overflow detection"
1603 This option turns on the -fstack-protector GCC feature. This
1604 feature puts, at the beginning of functions, a canary value on
1605 the stack just before the return address, and validates
1606 the value just before actually returning. Stack based buffer
1607 overflows (that need to overwrite this return address) now also
1608 overwrite the canary, which gets detected and the attack is then
1609 neutralized via a kernel panic.
1611 This feature requires gcc version 4.2 or above, or a distribution
1612 gcc with the feature backported. Older versions are automatically
1613 detected and for those versions, this configuration option is
1614 ignored. (and a warning is printed during bootup)
1616 source kernel/Kconfig.hz
1619 bool "kexec system call"
1621 kexec is a system call that implements the ability to shutdown your
1622 current kernel, and to start another kernel. It is like a reboot
1623 but it is independent of the system firmware. And like a reboot
1624 you can start any kernel with it, not just Linux.
1626 The name comes from the similarity to the exec system call.
1628 It is an ongoing process to be certain the hardware in a machine
1629 is properly shutdown, so do not be surprised if this code does not
1630 initially work for you. It may help to enable device hotplugging
1631 support. As of this writing the exact hardware interface is
1632 strongly in flux, so no good recommendation can be made.
1635 bool "kernel crash dumps"
1636 depends on X86_64 || (X86_32 && HIGHMEM)
1638 Generate crash dump after being started by kexec.
1639 This should be normally only set in special crash dump kernels
1640 which are loaded in the main kernel with kexec-tools into
1641 a specially reserved region and then later executed after
1642 a crash by kdump/kexec. The crash dump kernel must be compiled
1643 to a memory address not used by the main kernel or BIOS using
1644 PHYSICAL_START, or it must be built as a relocatable image
1645 (CONFIG_RELOCATABLE=y).
1646 For more details see Documentation/kdump/kdump.txt
1650 depends on KEXEC && HIBERNATION
1652 Jump between original kernel and kexeced kernel and invoke
1653 code in physical address mode via KEXEC
1655 config PHYSICAL_START
1656 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1659 This gives the physical address where the kernel is loaded.
1661 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1662 bzImage will decompress itself to above physical address and
1663 run from there. Otherwise, bzImage will run from the address where
1664 it has been loaded by the boot loader and will ignore above physical
1667 In normal kdump cases one does not have to set/change this option
1668 as now bzImage can be compiled as a completely relocatable image
1669 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1670 address. This option is mainly useful for the folks who don't want
1671 to use a bzImage for capturing the crash dump and want to use a
1672 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1673 to be specifically compiled to run from a specific memory area
1674 (normally a reserved region) and this option comes handy.
1676 So if you are using bzImage for capturing the crash dump,
1677 leave the value here unchanged to 0x1000000 and set
1678 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1679 for capturing the crash dump change this value to start of
1680 the reserved region. In other words, it can be set based on
1681 the "X" value as specified in the "crashkernel=YM@XM"
1682 command line boot parameter passed to the panic-ed
1683 kernel. Please take a look at Documentation/kdump/kdump.txt
1684 for more details about crash dumps.
1686 Usage of bzImage for capturing the crash dump is recommended as
1687 one does not have to build two kernels. Same kernel can be used
1688 as production kernel and capture kernel. Above option should have
1689 gone away after relocatable bzImage support is introduced. But it
1690 is present because there are users out there who continue to use
1691 vmlinux for dump capture. This option should go away down the
1694 Don't change this unless you know what you are doing.
1697 bool "Build a relocatable kernel"
1700 This builds a kernel image that retains relocation information
1701 so it can be loaded someplace besides the default 1MB.
1702 The relocations tend to make the kernel binary about 10% larger,
1703 but are discarded at runtime.
1705 One use is for the kexec on panic case where the recovery kernel
1706 must live at a different physical address than the primary
1709 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1710 it has been loaded at and the compile time physical address
1711 (CONFIG_PHYSICAL_START) is ignored.
1713 # Relocation on x86-32 needs some additional build support
1714 config X86_NEED_RELOCS
1716 depends on X86_32 && RELOCATABLE
1718 config PHYSICAL_ALIGN
1719 hex "Alignment value to which kernel should be aligned" if X86_32
1721 range 0x2000 0x1000000
1723 This value puts the alignment restrictions on physical address
1724 where kernel is loaded and run from. Kernel is compiled for an
1725 address which meets above alignment restriction.
1727 If bootloader loads the kernel at a non-aligned address and
1728 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1729 address aligned to above value and run from there.
1731 If bootloader loads the kernel at a non-aligned address and
1732 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1733 load address and decompress itself to the address it has been
1734 compiled for and run from there. The address for which kernel is
1735 compiled already meets above alignment restrictions. Hence the
1736 end result is that kernel runs from a physical address meeting
1737 above alignment restrictions.
1739 Don't change this unless you know what you are doing.
1742 bool "Support for hot-pluggable CPUs"
1745 Say Y here to allow turning CPUs off and on. CPUs can be
1746 controlled through /sys/devices/system/cpu.
1747 ( Note: power management support will enable this option
1748 automatically on SMP systems. )
1749 Say N if you want to disable CPU hotplug.
1751 config BOOTPARAM_HOTPLUG_CPU0
1752 bool "Set default setting of cpu0_hotpluggable"
1754 depends on HOTPLUG_CPU
1756 Set whether default state of cpu0_hotpluggable is on or off.
1758 Say Y here to enable CPU0 hotplug by default. If this switch
1759 is turned on, there is no need to give cpu0_hotplug kernel
1760 parameter and the CPU0 hotplug feature is enabled by default.
1762 Please note: there are two known CPU0 dependencies if you want
1763 to enable the CPU0 hotplug feature either by this switch or by
1764 cpu0_hotplug kernel parameter.
1766 First, resume from hibernate or suspend always starts from CPU0.
1767 So hibernate and suspend are prevented if CPU0 is offline.
1769 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1770 offline if any interrupt can not migrate out of CPU0. There may
1771 be other CPU0 dependencies.
1773 Please make sure the dependencies are under your control before
1774 you enable this feature.
1776 Say N if you don't want to enable CPU0 hotplug feature by default.
1777 You still can enable the CPU0 hotplug feature at boot by kernel
1778 parameter cpu0_hotplug.
1780 config DEBUG_HOTPLUG_CPU0
1782 prompt "Debug CPU0 hotplug"
1783 depends on HOTPLUG_CPU
1785 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1786 soon as possible and boots up userspace with CPU0 offlined. User
1787 can online CPU0 back after boot time.
1789 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1790 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1791 compilation or giving cpu0_hotplug kernel parameter at boot.
1797 prompt "Compat VDSO support"
1798 depends on X86_32 || IA32_EMULATION
1800 Map the 32-bit VDSO to the predictable old-style address too.
1802 Say N here if you are running a sufficiently recent glibc
1803 version (2.3.3 or later), to remove the high-mapped
1804 VDSO mapping and to exclusively use the randomized VDSO.
1809 bool "Built-in kernel command line"
1811 Allow for specifying boot arguments to the kernel at
1812 build time. On some systems (e.g. embedded ones), it is
1813 necessary or convenient to provide some or all of the
1814 kernel boot arguments with the kernel itself (that is,
1815 to not rely on the boot loader to provide them.)
1817 To compile command line arguments into the kernel,
1818 set this option to 'Y', then fill in the
1819 the boot arguments in CONFIG_CMDLINE.
1821 Systems with fully functional boot loaders (i.e. non-embedded)
1822 should leave this option set to 'N'.
1825 string "Built-in kernel command string"
1826 depends on CMDLINE_BOOL
1829 Enter arguments here that should be compiled into the kernel
1830 image and used at boot time. If the boot loader provides a
1831 command line at boot time, it is appended to this string to
1832 form the full kernel command line, when the system boots.
1834 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1835 change this behavior.
1837 In most cases, the command line (whether built-in or provided
1838 by the boot loader) should specify the device for the root
1841 config CMDLINE_OVERRIDE
1842 bool "Built-in command line overrides boot loader arguments"
1843 depends on CMDLINE_BOOL
1845 Set this option to 'Y' to have the kernel ignore the boot loader
1846 command line, and use ONLY the built-in command line.
1848 This is used to work around broken boot loaders. This should
1849 be set to 'N' under normal conditions.
1853 config ARCH_ENABLE_MEMORY_HOTPLUG
1855 depends on X86_64 || (X86_32 && HIGHMEM)
1857 config ARCH_ENABLE_MEMORY_HOTREMOVE
1859 depends on MEMORY_HOTPLUG
1861 config USE_PERCPU_NUMA_NODE_ID
1865 menu "Power management and ACPI options"
1867 config ARCH_HIBERNATION_HEADER
1869 depends on X86_64 && HIBERNATION
1871 source "kernel/power/Kconfig"
1873 source "drivers/acpi/Kconfig"
1875 source "drivers/sfi/Kconfig"
1882 tristate "APM (Advanced Power Management) BIOS support"
1883 depends on X86_32 && PM_SLEEP
1885 APM is a BIOS specification for saving power using several different
1886 techniques. This is mostly useful for battery powered laptops with
1887 APM compliant BIOSes. If you say Y here, the system time will be
1888 reset after a RESUME operation, the /proc/apm device will provide
1889 battery status information, and user-space programs will receive
1890 notification of APM "events" (e.g. battery status change).
1892 If you select "Y" here, you can disable actual use of the APM
1893 BIOS by passing the "apm=off" option to the kernel at boot time.
1895 Note that the APM support is almost completely disabled for
1896 machines with more than one CPU.
1898 In order to use APM, you will need supporting software. For location
1899 and more information, read <file:Documentation/power/apm-acpi.txt>
1900 and the Battery Powered Linux mini-HOWTO, available from
1901 <http://www.tldp.org/docs.html#howto>.
1903 This driver does not spin down disk drives (see the hdparm(8)
1904 manpage ("man 8 hdparm") for that), and it doesn't turn off
1905 VESA-compliant "green" monitors.
1907 This driver does not support the TI 4000M TravelMate and the ACER
1908 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1909 desktop machines also don't have compliant BIOSes, and this driver
1910 may cause those machines to panic during the boot phase.
1912 Generally, if you don't have a battery in your machine, there isn't
1913 much point in using this driver and you should say N. If you get
1914 random kernel OOPSes or reboots that don't seem to be related to
1915 anything, try disabling/enabling this option (or disabling/enabling
1918 Some other things you should try when experiencing seemingly random,
1921 1) make sure that you have enough swap space and that it is
1923 2) pass the "no-hlt" option to the kernel
1924 3) switch on floating point emulation in the kernel and pass
1925 the "no387" option to the kernel
1926 4) pass the "floppy=nodma" option to the kernel
1927 5) pass the "mem=4M" option to the kernel (thereby disabling
1928 all but the first 4 MB of RAM)
1929 6) make sure that the CPU is not over clocked.
1930 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1931 8) disable the cache from your BIOS settings
1932 9) install a fan for the video card or exchange video RAM
1933 10) install a better fan for the CPU
1934 11) exchange RAM chips
1935 12) exchange the motherboard.
1937 To compile this driver as a module, choose M here: the
1938 module will be called apm.
1942 config APM_IGNORE_USER_SUSPEND
1943 bool "Ignore USER SUSPEND"
1945 This option will ignore USER SUSPEND requests. On machines with a
1946 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1947 series notebooks, it is necessary to say Y because of a BIOS bug.
1949 config APM_DO_ENABLE
1950 bool "Enable PM at boot time"
1952 Enable APM features at boot time. From page 36 of the APM BIOS
1953 specification: "When disabled, the APM BIOS does not automatically
1954 power manage devices, enter the Standby State, enter the Suspend
1955 State, or take power saving steps in response to CPU Idle calls."
1956 This driver will make CPU Idle calls when Linux is idle (unless this
1957 feature is turned off -- see "Do CPU IDLE calls", below). This
1958 should always save battery power, but more complicated APM features
1959 will be dependent on your BIOS implementation. You may need to turn
1960 this option off if your computer hangs at boot time when using APM
1961 support, or if it beeps continuously instead of suspending. Turn
1962 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1963 T400CDT. This is off by default since most machines do fine without
1968 bool "Make CPU Idle calls when idle"
1970 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1971 On some machines, this can activate improved power savings, such as
1972 a slowed CPU clock rate, when the machine is idle. These idle calls
1973 are made after the idle loop has run for some length of time (e.g.,
1974 333 mS). On some machines, this will cause a hang at boot time or
1975 whenever the CPU becomes idle. (On machines with more than one CPU,
1976 this option does nothing.)
1978 config APM_DISPLAY_BLANK
1979 bool "Enable console blanking using APM"
1981 Enable console blanking using the APM. Some laptops can use this to
1982 turn off the LCD backlight when the screen blanker of the Linux
1983 virtual console blanks the screen. Note that this is only used by
1984 the virtual console screen blanker, and won't turn off the backlight
1985 when using the X Window system. This also doesn't have anything to
1986 do with your VESA-compliant power-saving monitor. Further, this
1987 option doesn't work for all laptops -- it might not turn off your
1988 backlight at all, or it might print a lot of errors to the console,
1989 especially if you are using gpm.
1991 config APM_ALLOW_INTS
1992 bool "Allow interrupts during APM BIOS calls"
1994 Normally we disable external interrupts while we are making calls to
1995 the APM BIOS as a measure to lessen the effects of a badly behaving
1996 BIOS implementation. The BIOS should reenable interrupts if it
1997 needs to. Unfortunately, some BIOSes do not -- especially those in
1998 many of the newer IBM Thinkpads. If you experience hangs when you
1999 suspend, try setting this to Y. Otherwise, say N.
2003 source "drivers/cpufreq/Kconfig"
2005 source "drivers/cpuidle/Kconfig"
2007 source "drivers/idle/Kconfig"
2012 menu "Bus options (PCI etc.)"
2017 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
2019 Find out whether you have a PCI motherboard. PCI is the name of a
2020 bus system, i.e. the way the CPU talks to the other stuff inside
2021 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2022 VESA. If you have PCI, say Y, otherwise N.
2025 prompt "PCI access mode"
2026 depends on X86_32 && PCI
2029 On PCI systems, the BIOS can be used to detect the PCI devices and
2030 determine their configuration. However, some old PCI motherboards
2031 have BIOS bugs and may crash if this is done. Also, some embedded
2032 PCI-based systems don't have any BIOS at all. Linux can also try to
2033 detect the PCI hardware directly without using the BIOS.
2035 With this option, you can specify how Linux should detect the
2036 PCI devices. If you choose "BIOS", the BIOS will be used,
2037 if you choose "Direct", the BIOS won't be used, and if you
2038 choose "MMConfig", then PCI Express MMCONFIG will be used.
2039 If you choose "Any", the kernel will try MMCONFIG, then the
2040 direct access method and falls back to the BIOS if that doesn't
2041 work. If unsure, go with the default, which is "Any".
2046 config PCI_GOMMCONFIG
2063 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2065 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2068 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2072 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2076 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2080 depends on PCI && XEN
2088 bool "Support mmconfig PCI config space access"
2089 depends on X86_64 && PCI && ACPI
2091 config PCI_CNB20LE_QUIRK
2092 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2095 Read the PCI windows out of the CNB20LE host bridge. This allows
2096 PCI hotplug to work on systems with the CNB20LE chipset which do
2099 There's no public spec for this chipset, and this functionality
2100 is known to be incomplete.
2102 You should say N unless you know you need this.
2104 source "drivers/pci/pcie/Kconfig"
2106 source "drivers/pci/Kconfig"
2108 # x86_64 have no ISA slots, but can have ISA-style DMA.
2110 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2113 Enables ISA-style DMA support for devices requiring such controllers.
2121 Find out whether you have ISA slots on your motherboard. ISA is the
2122 name of a bus system, i.e. the way the CPU talks to the other stuff
2123 inside your box. Other bus systems are PCI, EISA, MicroChannel
2124 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2125 newer boards don't support it. If you have ISA, say Y, otherwise N.
2131 The Extended Industry Standard Architecture (EISA) bus was
2132 developed as an open alternative to the IBM MicroChannel bus.
2134 The EISA bus provided some of the features of the IBM MicroChannel
2135 bus while maintaining backward compatibility with cards made for
2136 the older ISA bus. The EISA bus saw limited use between 1988 and
2137 1995 when it was made obsolete by the PCI bus.
2139 Say Y here if you are building a kernel for an EISA-based machine.
2143 source "drivers/eisa/Kconfig"
2146 tristate "NatSemi SCx200 support"
2148 This provides basic support for National Semiconductor's
2149 (now AMD's) Geode processors. The driver probes for the
2150 PCI-IDs of several on-chip devices, so its a good dependency
2151 for other scx200_* drivers.
2153 If compiled as a module, the driver is named scx200.
2155 config SCx200HR_TIMER
2156 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2160 This driver provides a clocksource built upon the on-chip
2161 27MHz high-resolution timer. Its also a workaround for
2162 NSC Geode SC-1100's buggy TSC, which loses time when the
2163 processor goes idle (as is done by the scheduler). The
2164 other workaround is idle=poll boot option.
2167 bool "One Laptop Per Child support"
2174 Add support for detecting the unique features of the OLPC
2178 bool "OLPC XO-1 Power Management"
2179 depends on OLPC && MFD_CS5535 && PM_SLEEP
2182 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2185 bool "OLPC XO-1 Real Time Clock"
2186 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2188 Add support for the XO-1 real time clock, which can be used as a
2189 programmable wakeup source.
2192 bool "OLPC XO-1 SCI extras"
2193 depends on OLPC && OLPC_XO1_PM
2199 Add support for SCI-based features of the OLPC XO-1 laptop:
2200 - EC-driven system wakeups
2204 - AC adapter status updates
2205 - Battery status updates
2207 config OLPC_XO15_SCI
2208 bool "OLPC XO-1.5 SCI extras"
2209 depends on OLPC && ACPI
2212 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2213 - EC-driven system wakeups
2214 - AC adapter status updates
2215 - Battery status updates
2218 bool "PCEngines ALIX System Support (LED setup)"
2221 This option enables system support for the PCEngines ALIX.
2222 At present this just sets up LEDs for GPIO control on
2223 ALIX2/3/6 boards. However, other system specific setup should
2226 Note: You must still enable the drivers for GPIO and LED support
2227 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2229 Note: You have to set alix.force=1 for boards with Award BIOS.
2232 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2235 This option enables system support for the Soekris Engineering net5501.
2238 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2242 This option enables system support for the Traverse Technologies GEOS.
2245 bool "Technologic Systems TS-5500 platform support"
2247 select CHECK_SIGNATURE
2251 This option enables system support for the Technologic Systems TS-5500.
2257 depends on CPU_SUP_AMD && PCI
2259 source "drivers/pcmcia/Kconfig"
2261 source "drivers/pci/hotplug/Kconfig"
2264 tristate "RapidIO support"
2268 If enabled this option will include drivers and the core
2269 infrastructure code to support RapidIO interconnect devices.
2271 source "drivers/rapidio/Kconfig"
2276 menu "Executable file formats / Emulations"
2278 source "fs/Kconfig.binfmt"
2280 config IA32_EMULATION
2281 bool "IA32 Emulation"
2284 select COMPAT_BINFMT_ELF
2287 Include code to run legacy 32-bit programs under a
2288 64-bit kernel. You should likely turn this on, unless you're
2289 100% sure that you don't have any 32-bit programs left.
2292 tristate "IA32 a.out support"
2293 depends on IA32_EMULATION
2295 Support old a.out binaries in the 32bit emulation.
2298 bool "x32 ABI for 64-bit mode"
2299 depends on X86_64 && IA32_EMULATION
2301 Include code to run binaries for the x32 native 32-bit ABI
2302 for 64-bit processors. An x32 process gets access to the
2303 full 64-bit register file and wide data path while leaving
2304 pointers at 32 bits for smaller memory footprint.
2306 You will need a recent binutils (2.22 or later) with
2307 elf32_x86_64 support enabled to compile a kernel with this
2312 depends on IA32_EMULATION || X86_X32
2313 select ARCH_WANT_OLD_COMPAT_IPC
2316 config COMPAT_FOR_U64_ALIGNMENT
2319 config SYSVIPC_COMPAT
2331 config HAVE_ATOMIC_IOMAP
2335 config HAVE_TEXT_POKE_SMP
2337 select STOP_MACHINE if SMP
2339 config X86_DEV_DMA_OPS
2341 depends on X86_64 || STA2X11
2343 config X86_DMA_REMAP
2347 source "net/Kconfig"
2349 source "drivers/Kconfig"
2351 source "drivers/firmware/Kconfig"
2355 source "arch/x86/Kconfig.debug"
2357 source "security/Kconfig"
2359 source "crypto/Kconfig"
2361 source "arch/x86/kvm/Kconfig"
2363 source "lib/Kconfig"
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blob