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
20 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
21 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
23 select ARCH_CLOCKSOURCE_DATA
24 select ARCH_DISCARD_MEMBLOCK
25 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
26 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
27 select ARCH_HAS_DEVMEM_IS_ALLOWED
28 select ARCH_HAS_ELF_RANDOMIZE
29 select ARCH_HAS_FAST_MULTIPLIER
30 select ARCH_HAS_GCOV_PROFILE_ALL
31 select ARCH_HAS_KCOV if X86_64
32 select ARCH_HAS_PMEM_API if X86_64
33 select ARCH_HAS_MMIO_FLUSH
34 select ARCH_HAS_SG_CHAIN
35 select ARCH_HAS_UBSAN_SANITIZE_ALL
36 select ARCH_HAVE_NMI_SAFE_CMPXCHG
37 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
38 select ARCH_MIGHT_HAVE_PC_PARPORT
39 select ARCH_MIGHT_HAVE_PC_SERIO
40 select ARCH_SUPPORTS_ATOMIC_RMW
41 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
42 select ARCH_SUPPORTS_INT128 if X86_64
43 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
44 select ARCH_USE_BUILTIN_BSWAP
45 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
46 select ARCH_USE_QUEUED_RWLOCKS
47 select ARCH_USE_QUEUED_SPINLOCKS
48 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
49 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
50 select ARCH_WANT_FRAME_POINTERS
51 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
52 select ARCH_WANT_OPTIONAL_GPIOLIB
53 select BUILDTIME_EXTABLE_SORT
55 select CLKSRC_I8253 if X86_32
56 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
57 select CLOCKSOURCE_WATCHDOG
58 select CLONE_BACKWARDS if X86_32
59 select COMPAT_OLD_SIGACTION if IA32_EMULATION
60 select DCACHE_WORD_ACCESS
61 select EDAC_ATOMIC_SCRUB
63 select GENERIC_CLOCKEVENTS
64 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
65 select GENERIC_CLOCKEVENTS_MIN_ADJUST
66 select GENERIC_CMOS_UPDATE
67 select GENERIC_CPU_AUTOPROBE
68 select GENERIC_EARLY_IOREMAP
69 select GENERIC_FIND_FIRST_BIT
71 select GENERIC_IRQ_PROBE
72 select GENERIC_IRQ_SHOW
73 select GENERIC_PENDING_IRQ if SMP
74 select GENERIC_SMP_IDLE_THREAD
75 select GENERIC_STRNCPY_FROM_USER
76 select GENERIC_STRNLEN_USER
77 select GENERIC_TIME_VSYSCALL
78 select HAVE_ACPI_APEI if ACPI
79 select HAVE_ACPI_APEI_NMI if ACPI
80 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
81 select HAVE_AOUT if X86_32
82 select HAVE_ARCH_AUDITSYSCALL
83 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
84 select HAVE_ARCH_JUMP_LABEL
85 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
87 select HAVE_ARCH_KMEMCHECK
88 select HAVE_ARCH_MMAP_RND_BITS if MMU
89 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
90 select HAVE_ARCH_SECCOMP_FILTER
91 select HAVE_ARCH_SOFT_DIRTY if X86_64
92 select HAVE_ARCH_TRACEHOOK
93 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
94 select HAVE_EBPF_JIT if X86_64
95 select HAVE_CC_STACKPROTECTOR
96 select HAVE_CMPXCHG_DOUBLE
97 select HAVE_CMPXCHG_LOCAL
98 select HAVE_CONTEXT_TRACKING if X86_64
99 select HAVE_COPY_THREAD_TLS
100 select HAVE_C_RECORDMCOUNT
101 select HAVE_DEBUG_KMEMLEAK
102 select HAVE_DEBUG_STACKOVERFLOW
103 select HAVE_DMA_API_DEBUG
104 select HAVE_DMA_CONTIGUOUS
105 select HAVE_DYNAMIC_FTRACE
106 select HAVE_DYNAMIC_FTRACE_WITH_REGS
107 select HAVE_EFFICIENT_UNALIGNED_ACCESS
108 select HAVE_EXIT_THREAD
109 select HAVE_FENTRY if X86_64
110 select HAVE_FTRACE_MCOUNT_RECORD
111 select HAVE_FUNCTION_GRAPH_FP_TEST
112 select HAVE_FUNCTION_GRAPH_TRACER
113 select HAVE_FUNCTION_TRACER
114 select HAVE_GCC_PLUGINS
115 select HAVE_GENERIC_DMA_COHERENT if X86_32
116 select HAVE_HW_BREAKPOINT
118 select HAVE_IOREMAP_PROT
119 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
120 select HAVE_IRQ_TIME_ACCOUNTING
121 select HAVE_KERNEL_BZIP2
122 select HAVE_KERNEL_GZIP
123 select HAVE_KERNEL_LZ4
124 select HAVE_KERNEL_LZMA
125 select HAVE_KERNEL_LZO
126 select HAVE_KERNEL_XZ
128 select HAVE_KPROBES_ON_FTRACE
129 select HAVE_KRETPROBES
131 select HAVE_LIVEPATCH if X86_64
133 select HAVE_MEMBLOCK_NODE_MAP
134 select HAVE_MIXED_BREAKPOINTS_REGS
137 select HAVE_OPTPROBES
138 select HAVE_PCSPKR_PLATFORM
139 select HAVE_PERF_EVENTS
140 select HAVE_PERF_EVENTS_NMI
141 select HAVE_PERF_REGS
142 select HAVE_PERF_USER_STACK_DUMP
143 select HAVE_REGS_AND_STACK_ACCESS_API
144 select HAVE_SYSCALL_TRACEPOINTS
145 select HAVE_UID16 if X86_32 || IA32_EMULATION
146 select HAVE_UNSTABLE_SCHED_CLOCK
147 select HAVE_USER_RETURN_NOTIFIER
148 select IRQ_FORCED_THREADING
149 select MODULES_USE_ELF_RELA if X86_64
150 select MODULES_USE_ELF_REL if X86_32
151 select OLD_SIGACTION if X86_32
152 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
157 select SYSCTL_EXCEPTION_TRACE
158 select USER_STACKTRACE_SUPPORT
160 select X86_DEV_DMA_OPS if X86_64
161 select X86_FEATURE_NAMES if PROC_FS
162 select HAVE_STACK_VALIDATION if X86_64
163 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
164 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
166 config INSTRUCTION_DECODER
168 depends on KPROBES || PERF_EVENTS || UPROBES
172 default "elf32-i386" if X86_32
173 default "elf64-x86-64" if X86_64
175 config ARCH_DEFCONFIG
177 default "arch/x86/configs/i386_defconfig" if X86_32
178 default "arch/x86/configs/x86_64_defconfig" if X86_64
180 config LOCKDEP_SUPPORT
183 config STACKTRACE_SUPPORT
189 config ARCH_MMAP_RND_BITS_MIN
193 config ARCH_MMAP_RND_BITS_MAX
197 config ARCH_MMAP_RND_COMPAT_BITS_MIN
200 config ARCH_MMAP_RND_COMPAT_BITS_MAX
206 config NEED_DMA_MAP_STATE
208 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
210 config NEED_SG_DMA_LENGTH
213 config GENERIC_ISA_DMA
215 depends on ISA_DMA_API
220 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
222 config GENERIC_BUG_RELATIVE_POINTERS
225 config GENERIC_HWEIGHT
228 config ARCH_MAY_HAVE_PC_FDC
230 depends on ISA_DMA_API
232 config RWSEM_XCHGADD_ALGORITHM
235 config GENERIC_CALIBRATE_DELAY
238 config ARCH_HAS_CPU_RELAX
241 config ARCH_HAS_CACHE_LINE_SIZE
244 config HAVE_SETUP_PER_CPU_AREA
247 config NEED_PER_CPU_EMBED_FIRST_CHUNK
250 config NEED_PER_CPU_PAGE_FIRST_CHUNK
253 config ARCH_HIBERNATION_POSSIBLE
256 config ARCH_SUSPEND_POSSIBLE
259 config ARCH_WANT_HUGE_PMD_SHARE
262 config ARCH_WANT_GENERAL_HUGETLB
271 config ARCH_SUPPORTS_OPTIMIZED_INLINING
274 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
277 config KASAN_SHADOW_OFFSET
280 default 0xdffffc0000000000
282 config HAVE_INTEL_TXT
284 depends on INTEL_IOMMU && ACPI
288 depends on X86_32 && SMP
292 depends on X86_64 && SMP
294 config X86_32_LAZY_GS
296 depends on X86_32 && !CC_STACKPROTECTOR
298 config ARCH_HWEIGHT_CFLAGS
300 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
301 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
303 config ARCH_SUPPORTS_UPROBES
306 config FIX_EARLYCON_MEM
312 config PGTABLE_LEVELS
318 source "init/Kconfig"
319 source "kernel/Kconfig.freezer"
321 menu "Processor type and features"
324 bool "DMA memory allocation support" if EXPERT
327 DMA memory allocation support allows devices with less than 32-bit
328 addressing to allocate within the first 16MB of address space.
329 Disable if no such devices will be used.
334 bool "Symmetric multi-processing support"
336 This enables support for systems with more than one CPU. If you have
337 a system with only one CPU, say N. If you have a system with more
340 If you say N here, the kernel will run on uni- and multiprocessor
341 machines, but will use only one CPU of a multiprocessor machine. If
342 you say Y here, the kernel will run on many, but not all,
343 uniprocessor machines. On a uniprocessor machine, the kernel
344 will run faster if you say N here.
346 Note that if you say Y here and choose architecture "586" or
347 "Pentium" under "Processor family", the kernel will not work on 486
348 architectures. Similarly, multiprocessor kernels for the "PPro"
349 architecture may not work on all Pentium based boards.
351 People using multiprocessor machines who say Y here should also say
352 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
353 Management" code will be disabled if you say Y here.
355 See also <file:Documentation/x86/i386/IO-APIC.txt>,
356 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
357 <http://www.tldp.org/docs.html#howto>.
359 If you don't know what to do here, say N.
361 config X86_FEATURE_NAMES
362 bool "Processor feature human-readable names" if EMBEDDED
365 This option compiles in a table of x86 feature bits and corresponding
366 names. This is required to support /proc/cpuinfo and a few kernel
367 messages. You can disable this to save space, at the expense of
368 making those few kernel messages show numeric feature bits instead.
372 config X86_FAST_FEATURE_TESTS
373 bool "Fast CPU feature tests" if EMBEDDED
376 Some fast-paths in the kernel depend on the capabilities of the CPU.
377 Say Y here for the kernel to patch in the appropriate code at runtime
378 based on the capabilities of the CPU. The infrastructure for patching
379 code at runtime takes up some additional space; space-constrained
380 embedded systems may wish to say N here to produce smaller, slightly
384 bool "Support x2apic"
385 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
387 This enables x2apic support on CPUs that have this feature.
389 This allows 32-bit apic IDs (so it can support very large systems),
390 and accesses the local apic via MSRs not via mmio.
392 If you don't know what to do here, say N.
395 bool "Enable MPS table" if ACPI || SFI
397 depends on X86_LOCAL_APIC
399 For old smp systems that do not have proper acpi support. Newer systems
400 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
403 bool "Support for big SMP systems with more than 8 CPUs"
404 depends on X86_32 && SMP
406 This option is needed for the systems that have more than 8 CPUs
410 depends on X86_GOLDFISH
413 config X86_EXTENDED_PLATFORM
414 bool "Support for extended (non-PC) x86 platforms"
417 If you disable this option then the kernel will only support
418 standard PC platforms. (which covers the vast majority of
421 If you enable this option then you'll be able to select support
422 for the following (non-PC) 32 bit x86 platforms:
423 Goldfish (Android emulator)
426 SGI 320/540 (Visual Workstation)
427 STA2X11-based (e.g. Northville)
428 Moorestown MID devices
430 If you have one of these systems, or if you want to build a
431 generic distribution kernel, say Y here - otherwise say N.
435 config X86_EXTENDED_PLATFORM
436 bool "Support for extended (non-PC) x86 platforms"
439 If you disable this option then the kernel will only support
440 standard PC platforms. (which covers the vast majority of
443 If you enable this option then you'll be able to select support
444 for the following (non-PC) 64 bit x86 platforms:
449 If you have one of these systems, or if you want to build a
450 generic distribution kernel, say Y here - otherwise say N.
452 # This is an alphabetically sorted list of 64 bit extended platforms
453 # Please maintain the alphabetic order if and when there are additions
455 bool "Numascale NumaChip"
457 depends on X86_EXTENDED_PLATFORM
460 depends on X86_X2APIC
461 depends on PCI_MMCONFIG
463 Adds support for Numascale NumaChip large-SMP systems. Needed to
464 enable more than ~168 cores.
465 If you don't have one of these, you should say N here.
469 select HYPERVISOR_GUEST
471 depends on X86_64 && PCI
472 depends on X86_EXTENDED_PLATFORM
475 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
476 supposed to run on these EM64T-based machines. Only choose this option
477 if you have one of these machines.
480 bool "SGI Ultraviolet"
482 depends on X86_EXTENDED_PLATFORM
485 depends on X86_X2APIC
488 This option is needed in order to support SGI Ultraviolet systems.
489 If you don't have one of these, you should say N here.
491 # Following is an alphabetically sorted list of 32 bit extended platforms
492 # Please maintain the alphabetic order if and when there are additions
495 bool "Goldfish (Virtual Platform)"
496 depends on X86_EXTENDED_PLATFORM
498 Enable support for the Goldfish virtual platform used primarily
499 for Android development. Unless you are building for the Android
500 Goldfish emulator say N here.
503 bool "CE4100 TV platform"
505 depends on PCI_GODIRECT
506 depends on X86_IO_APIC
508 depends on X86_EXTENDED_PLATFORM
509 select X86_REBOOTFIXUPS
511 select OF_EARLY_FLATTREE
513 Select for the Intel CE media processor (CE4100) SOC.
514 This option compiles in support for the CE4100 SOC for settop
515 boxes and media devices.
518 bool "Intel MID platform support"
519 depends on X86_EXTENDED_PLATFORM
520 depends on X86_PLATFORM_DEVICES
522 depends on X86_64 || (PCI_GOANY && X86_32)
523 depends on X86_IO_APIC
529 select MFD_INTEL_MSIC
531 Select to build a kernel capable of supporting Intel MID (Mobile
532 Internet Device) platform systems which do not have the PCI legacy
533 interfaces. If you are building for a PC class system say N here.
535 Intel MID platforms are based on an Intel processor and chipset which
536 consume less power than most of the x86 derivatives.
538 config X86_INTEL_QUARK
539 bool "Intel Quark platform support"
541 depends on X86_EXTENDED_PLATFORM
542 depends on X86_PLATFORM_DEVICES
546 depends on X86_IO_APIC
551 Select to include support for Quark X1000 SoC.
552 Say Y here if you have a Quark based system such as the Arduino
553 compatible Intel Galileo.
555 config X86_INTEL_LPSS
556 bool "Intel Low Power Subsystem Support"
557 depends on X86 && ACPI
562 Select to build support for Intel Low Power Subsystem such as
563 found on Intel Lynxpoint PCH. Selecting this option enables
564 things like clock tree (common clock framework) and pincontrol
565 which are needed by the LPSS peripheral drivers.
567 config X86_AMD_PLATFORM_DEVICE
568 bool "AMD ACPI2Platform devices support"
573 Select to interpret AMD specific ACPI device to platform device
574 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
575 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
576 implemented under PINCTRL subsystem.
579 tristate "Intel SoC IOSF Sideband support for SoC platforms"
582 This option enables sideband register access support for Intel SoC
583 platforms. On these platforms the IOSF sideband is used in lieu of
584 MSR's for some register accesses, mostly but not limited to thermal
585 and power. Drivers may query the availability of this device to
586 determine if they need the sideband in order to work on these
587 platforms. The sideband is available on the following SoC products.
588 This list is not meant to be exclusive.
593 You should say Y if you are running a kernel on one of these SoC's.
595 config IOSF_MBI_DEBUG
596 bool "Enable IOSF sideband access through debugfs"
597 depends on IOSF_MBI && DEBUG_FS
599 Select this option to expose the IOSF sideband access registers (MCR,
600 MDR, MCRX) through debugfs to write and read register information from
601 different units on the SoC. This is most useful for obtaining device
602 state information for debug and analysis. As this is a general access
603 mechanism, users of this option would have specific knowledge of the
604 device they want to access.
606 If you don't require the option or are in doubt, say N.
609 bool "RDC R-321x SoC"
611 depends on X86_EXTENDED_PLATFORM
613 select X86_REBOOTFIXUPS
615 This option is needed for RDC R-321x system-on-chip, also known
617 If you don't have one of these chips, you should say N here.
619 config X86_32_NON_STANDARD
620 bool "Support non-standard 32-bit SMP architectures"
621 depends on X86_32 && SMP
622 depends on X86_EXTENDED_PLATFORM
624 This option compiles in the bigsmp and STA2X11 default
625 subarchitectures. It is intended for a generic binary
626 kernel. If you select them all, kernel will probe it one by
627 one and will fallback to default.
629 # Alphabetically sorted list of Non standard 32 bit platforms
631 config X86_SUPPORTS_MEMORY_FAILURE
633 # MCE code calls memory_failure():
635 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
636 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
637 depends on X86_64 || !SPARSEMEM
638 select ARCH_SUPPORTS_MEMORY_FAILURE
641 bool "STA2X11 Companion Chip Support"
642 depends on X86_32_NON_STANDARD && PCI
643 select X86_DEV_DMA_OPS
647 select ARCH_REQUIRE_GPIOLIB
650 This adds support for boards based on the STA2X11 IO-Hub,
651 a.k.a. "ConneXt". The chip is used in place of the standard
652 PC chipset, so all "standard" peripherals are missing. If this
653 option is selected the kernel will still be able to boot on
654 standard PC machines.
657 tristate "Eurobraille/Iris poweroff module"
660 The Iris machines from EuroBraille do not have APM or ACPI support
661 to shut themselves down properly. A special I/O sequence is
662 needed to do so, which is what this module does at
665 This is only for Iris machines from EuroBraille.
669 config SCHED_OMIT_FRAME_POINTER
671 prompt "Single-depth WCHAN output"
674 Calculate simpler /proc/<PID>/wchan values. If this option
675 is disabled then wchan values will recurse back to the
676 caller function. This provides more accurate wchan values,
677 at the expense of slightly more scheduling overhead.
679 If in doubt, say "Y".
681 menuconfig HYPERVISOR_GUEST
682 bool "Linux guest support"
684 Say Y here to enable options for running Linux under various hyper-
685 visors. This option enables basic hypervisor detection and platform
688 If you say N, all options in this submenu will be skipped and
689 disabled, and Linux guest support won't be built in.
694 bool "Enable paravirtualization code"
696 This changes the kernel so it can modify itself when it is run
697 under a hypervisor, potentially improving performance significantly
698 over full virtualization. However, when run without a hypervisor
699 the kernel is theoretically slower and slightly larger.
701 config PARAVIRT_DEBUG
702 bool "paravirt-ops debugging"
703 depends on PARAVIRT && DEBUG_KERNEL
705 Enable to debug paravirt_ops internals. Specifically, BUG if
706 a paravirt_op is missing when it is called.
708 config PARAVIRT_SPINLOCKS
709 bool "Paravirtualization layer for spinlocks"
710 depends on PARAVIRT && SMP
711 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
713 Paravirtualized spinlocks allow a pvops backend to replace the
714 spinlock implementation with something virtualization-friendly
715 (for example, block the virtual CPU rather than spinning).
717 It has a minimal impact on native kernels and gives a nice performance
718 benefit on paravirtualized KVM / Xen kernels.
720 If you are unsure how to answer this question, answer Y.
722 config QUEUED_LOCK_STAT
723 bool "Paravirt queued spinlock statistics"
724 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
726 Enable the collection of statistical data on the slowpath
727 behavior of paravirtualized queued spinlocks and report
730 source "arch/x86/xen/Kconfig"
733 bool "KVM Guest support (including kvmclock)"
735 select PARAVIRT_CLOCK
738 This option enables various optimizations for running under the KVM
739 hypervisor. It includes a paravirtualized clock, so that instead
740 of relying on a PIT (or probably other) emulation by the
741 underlying device model, the host provides the guest with
742 timing infrastructure such as time of day, and system time
745 bool "Enable debug information for KVM Guests in debugfs"
746 depends on KVM_GUEST && DEBUG_FS
749 This option enables collection of various statistics for KVM guest.
750 Statistics are displayed in debugfs filesystem. Enabling this option
751 may incur significant overhead.
753 source "arch/x86/lguest/Kconfig"
755 config PARAVIRT_TIME_ACCOUNTING
756 bool "Paravirtual steal time accounting"
760 Select this option to enable fine granularity task steal time
761 accounting. Time spent executing other tasks in parallel with
762 the current vCPU is discounted from the vCPU power. To account for
763 that, there can be a small performance impact.
765 If in doubt, say N here.
767 config PARAVIRT_CLOCK
770 endif #HYPERVISOR_GUEST
775 source "arch/x86/Kconfig.cpu"
779 prompt "HPET Timer Support" if X86_32
781 Use the IA-PC HPET (High Precision Event Timer) to manage
782 time in preference to the PIT and RTC, if a HPET is
784 HPET is the next generation timer replacing legacy 8254s.
785 The HPET provides a stable time base on SMP
786 systems, unlike the TSC, but it is more expensive to access,
787 as it is off-chip. The interface used is documented
788 in the HPET spec, revision 1.
790 You can safely choose Y here. However, HPET will only be
791 activated if the platform and the BIOS support this feature.
792 Otherwise the 8254 will be used for timing services.
794 Choose N to continue using the legacy 8254 timer.
796 config HPET_EMULATE_RTC
798 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
801 def_bool y if X86_INTEL_MID
802 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
804 depends on X86_INTEL_MID && SFI
806 APB timer is the replacement for 8254, HPET on X86 MID platforms.
807 The APBT provides a stable time base on SMP
808 systems, unlike the TSC, but it is more expensive to access,
809 as it is off-chip. APB timers are always running regardless of CPU
810 C states, they are used as per CPU clockevent device when possible.
812 # Mark as expert because too many people got it wrong.
813 # The code disables itself when not needed.
816 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
817 bool "Enable DMI scanning" if EXPERT
819 Enabled scanning of DMI to identify machine quirks. Say Y
820 here unless you have verified that your setup is not
821 affected by entries in the DMI blacklist. Required by PNP
825 bool "Old AMD GART IOMMU support"
827 depends on X86_64 && PCI && AMD_NB
829 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
830 GART based hardware IOMMUs.
832 The GART supports full DMA access for devices with 32-bit access
833 limitations, on systems with more than 3 GB. This is usually needed
834 for USB, sound, many IDE/SATA chipsets and some other devices.
836 Newer systems typically have a modern AMD IOMMU, supported via
837 the CONFIG_AMD_IOMMU=y config option.
839 In normal configurations this driver is only active when needed:
840 there's more than 3 GB of memory and the system contains a
841 32-bit limited device.
846 bool "IBM Calgary IOMMU support"
848 depends on X86_64 && PCI
850 Support for hardware IOMMUs in IBM's xSeries x366 and x460
851 systems. Needed to run systems with more than 3GB of memory
852 properly with 32-bit PCI devices that do not support DAC
853 (Double Address Cycle). Calgary also supports bus level
854 isolation, where all DMAs pass through the IOMMU. This
855 prevents them from going anywhere except their intended
856 destination. This catches hard-to-find kernel bugs and
857 mis-behaving drivers and devices that do not use the DMA-API
858 properly to set up their DMA buffers. The IOMMU can be
859 turned off at boot time with the iommu=off parameter.
860 Normally the kernel will make the right choice by itself.
863 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
865 prompt "Should Calgary be enabled by default?"
866 depends on CALGARY_IOMMU
868 Should Calgary be enabled by default? if you choose 'y', Calgary
869 will be used (if it exists). If you choose 'n', Calgary will not be
870 used even if it exists. If you choose 'n' and would like to use
871 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
874 # need this always selected by IOMMU for the VIA workaround
878 Support for software bounce buffers used on x86-64 systems
879 which don't have a hardware IOMMU. Using this PCI devices
880 which can only access 32-bits of memory can be used on systems
881 with more than 3 GB of memory.
886 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
889 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
890 depends on X86_64 && SMP && DEBUG_KERNEL
891 select CPUMASK_OFFSTACK
893 Enable maximum number of CPUS and NUMA Nodes for this architecture.
897 int "Maximum number of CPUs" if SMP && !MAXSMP
898 range 2 8 if SMP && X86_32 && !X86_BIGSMP
899 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
900 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
902 default "8192" if MAXSMP
903 default "32" if SMP && X86_BIGSMP
904 default "8" if SMP && X86_32
907 This allows you to specify the maximum number of CPUs which this
908 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
909 supported value is 8192, otherwise the maximum value is 512. The
910 minimum value which makes sense is 2.
912 This is purely to save memory - each supported CPU adds
913 approximately eight kilobytes to the kernel image.
916 bool "SMT (Hyperthreading) scheduler support"
919 SMT scheduler support improves the CPU scheduler's decision making
920 when dealing with Intel Pentium 4 chips with HyperThreading at a
921 cost of slightly increased overhead in some places. If unsure say
926 prompt "Multi-core scheduler support"
929 Multi-core scheduler support improves the CPU scheduler's decision
930 making when dealing with multi-core CPU chips at a cost of slightly
931 increased overhead in some places. If unsure say N here.
933 source "kernel/Kconfig.preempt"
937 depends on !SMP && X86_LOCAL_APIC
940 bool "Local APIC support on uniprocessors" if !PCI_MSI
942 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
944 A local APIC (Advanced Programmable Interrupt Controller) is an
945 integrated interrupt controller in the CPU. If you have a single-CPU
946 system which has a processor with a local APIC, you can say Y here to
947 enable and use it. If you say Y here even though your machine doesn't
948 have a local APIC, then the kernel will still run with no slowdown at
949 all. The local APIC supports CPU-generated self-interrupts (timer,
950 performance counters), and the NMI watchdog which detects hard
954 bool "IO-APIC support on uniprocessors"
955 depends on X86_UP_APIC
957 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
958 SMP-capable replacement for PC-style interrupt controllers. Most
959 SMP systems and many recent uniprocessor systems have one.
961 If you have a single-CPU system with an IO-APIC, you can say Y here
962 to use it. If you say Y here even though your machine doesn't have
963 an IO-APIC, then the kernel will still run with no slowdown at all.
965 config X86_LOCAL_APIC
967 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
968 select IRQ_DOMAIN_HIERARCHY
969 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
973 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
975 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
976 bool "Reroute for broken boot IRQs"
977 depends on X86_IO_APIC
979 This option enables a workaround that fixes a source of
980 spurious interrupts. This is recommended when threaded
981 interrupt handling is used on systems where the generation of
982 superfluous "boot interrupts" cannot be disabled.
984 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
985 entry in the chipset's IO-APIC is masked (as, e.g. the RT
986 kernel does during interrupt handling). On chipsets where this
987 boot IRQ generation cannot be disabled, this workaround keeps
988 the original IRQ line masked so that only the equivalent "boot
989 IRQ" is delivered to the CPUs. The workaround also tells the
990 kernel to set up the IRQ handler on the boot IRQ line. In this
991 way only one interrupt is delivered to the kernel. Otherwise
992 the spurious second interrupt may cause the kernel to bring
993 down (vital) interrupt lines.
995 Only affects "broken" chipsets. Interrupt sharing may be
996 increased on these systems.
999 bool "Machine Check / overheating reporting"
1000 select GENERIC_ALLOCATOR
1003 Machine Check support allows the processor to notify the
1004 kernel if it detects a problem (e.g. overheating, data corruption).
1005 The action the kernel takes depends on the severity of the problem,
1006 ranging from warning messages to halting the machine.
1008 config X86_MCE_INTEL
1010 prompt "Intel MCE features"
1011 depends on X86_MCE && X86_LOCAL_APIC
1013 Additional support for intel specific MCE features such as
1014 the thermal monitor.
1018 prompt "AMD MCE features"
1019 depends on X86_MCE && X86_LOCAL_APIC
1021 Additional support for AMD specific MCE features such as
1022 the DRAM Error Threshold.
1024 config X86_ANCIENT_MCE
1025 bool "Support for old Pentium 5 / WinChip machine checks"
1026 depends on X86_32 && X86_MCE
1028 Include support for machine check handling on old Pentium 5 or WinChip
1029 systems. These typically need to be enabled explicitly on the command
1032 config X86_MCE_THRESHOLD
1033 depends on X86_MCE_AMD || X86_MCE_INTEL
1036 config X86_MCE_INJECT
1038 tristate "Machine check injector support"
1040 Provide support for injecting machine checks for testing purposes.
1041 If you don't know what a machine check is and you don't do kernel
1042 QA it is safe to say n.
1044 config X86_THERMAL_VECTOR
1046 depends on X86_MCE_INTEL
1048 source "arch/x86/events/Kconfig"
1050 config X86_LEGACY_VM86
1051 bool "Legacy VM86 support"
1055 This option allows user programs to put the CPU into V8086
1056 mode, which is an 80286-era approximation of 16-bit real mode.
1058 Some very old versions of X and/or vbetool require this option
1059 for user mode setting. Similarly, DOSEMU will use it if
1060 available to accelerate real mode DOS programs. However, any
1061 recent version of DOSEMU, X, or vbetool should be fully
1062 functional even without kernel VM86 support, as they will all
1063 fall back to software emulation. Nevertheless, if you are using
1064 a 16-bit DOS program where 16-bit performance matters, vm86
1065 mode might be faster than emulation and you might want to
1068 Note that any app that works on a 64-bit kernel is unlikely to
1069 need this option, as 64-bit kernels don't, and can't, support
1070 V8086 mode. This option is also unrelated to 16-bit protected
1071 mode and is not needed to run most 16-bit programs under Wine.
1073 Enabling this option increases the complexity of the kernel
1074 and slows down exception handling a tiny bit.
1076 If unsure, say N here.
1080 default X86_LEGACY_VM86
1083 bool "Enable support for 16-bit segments" if EXPERT
1085 depends on MODIFY_LDT_SYSCALL
1087 This option is required by programs like Wine to run 16-bit
1088 protected mode legacy code on x86 processors. Disabling
1089 this option saves about 300 bytes on i386, or around 6K text
1090 plus 16K runtime memory on x86-64,
1094 depends on X86_16BIT && X86_32
1098 depends on X86_16BIT && X86_64
1100 config X86_VSYSCALL_EMULATION
1101 bool "Enable vsyscall emulation" if EXPERT
1105 This enables emulation of the legacy vsyscall page. Disabling
1106 it is roughly equivalent to booting with vsyscall=none, except
1107 that it will also disable the helpful warning if a program
1108 tries to use a vsyscall. With this option set to N, offending
1109 programs will just segfault, citing addresses of the form
1112 This option is required by many programs built before 2013, and
1113 care should be used even with newer programs if set to N.
1115 Disabling this option saves about 7K of kernel size and
1116 possibly 4K of additional runtime pagetable memory.
1119 tristate "Toshiba Laptop support"
1122 This adds a driver to safely access the System Management Mode of
1123 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1124 not work on models with a Phoenix BIOS. The System Management Mode
1125 is used to set the BIOS and power saving options on Toshiba portables.
1127 For information on utilities to make use of this driver see the
1128 Toshiba Linux utilities web site at:
1129 <http://www.buzzard.org.uk/toshiba/>.
1131 Say Y if you intend to run this kernel on a Toshiba portable.
1135 tristate "Dell i8k legacy laptop support"
1137 select SENSORS_DELL_SMM
1139 This option enables legacy /proc/i8k userspace interface in hwmon
1140 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1141 temperature and allows controlling fan speeds of Dell laptops via
1142 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1143 it reports also power and hotkey status. For fan speed control is
1144 needed userspace package i8kutils.
1146 Say Y if you intend to run this kernel on old Dell laptops or want to
1147 use userspace package i8kutils.
1150 config X86_REBOOTFIXUPS
1151 bool "Enable X86 board specific fixups for reboot"
1154 This enables chipset and/or board specific fixups to be done
1155 in order to get reboot to work correctly. This is only needed on
1156 some combinations of hardware and BIOS. The symptom, for which
1157 this config is intended, is when reboot ends with a stalled/hung
1160 Currently, the only fixup is for the Geode machines using
1161 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1163 Say Y if you want to enable the fixup. Currently, it's safe to
1164 enable this option even if you don't need it.
1168 bool "CPU microcode loading support"
1170 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1173 If you say Y here, you will be able to update the microcode on
1174 Intel and AMD processors. The Intel support is for the IA32 family,
1175 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1176 AMD support is for families 0x10 and later. You will obviously need
1177 the actual microcode binary data itself which is not shipped with
1180 The preferred method to load microcode from a detached initrd is described
1181 in Documentation/x86/early-microcode.txt. For that you need to enable
1182 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1183 initrd for microcode blobs.
1185 In addition, you can build-in the microcode into the kernel. For that you
1186 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1187 to the CONFIG_EXTRA_FIRMWARE config option.
1189 config MICROCODE_INTEL
1190 bool "Intel microcode loading support"
1191 depends on MICROCODE
1195 This options enables microcode patch loading support for Intel
1198 For the current Intel microcode data package go to
1199 <https://downloadcenter.intel.com> and search for
1200 'Linux Processor Microcode Data File'.
1202 config MICROCODE_AMD
1203 bool "AMD microcode loading support"
1204 depends on MICROCODE
1207 If you select this option, microcode patch loading support for AMD
1208 processors will be enabled.
1210 config MICROCODE_OLD_INTERFACE
1212 depends on MICROCODE
1215 tristate "/dev/cpu/*/msr - Model-specific register support"
1217 This device gives privileged processes access to the x86
1218 Model-Specific Registers (MSRs). It is a character device with
1219 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1220 MSR accesses are directed to a specific CPU on multi-processor
1224 tristate "/dev/cpu/*/cpuid - CPU information support"
1226 This device gives processes access to the x86 CPUID instruction to
1227 be executed on a specific processor. It is a character device
1228 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1232 prompt "High Memory Support"
1239 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1240 However, the address space of 32-bit x86 processors is only 4
1241 Gigabytes large. That means that, if you have a large amount of
1242 physical memory, not all of it can be "permanently mapped" by the
1243 kernel. The physical memory that's not permanently mapped is called
1246 If you are compiling a kernel which will never run on a machine with
1247 more than 1 Gigabyte total physical RAM, answer "off" here (default
1248 choice and suitable for most users). This will result in a "3GB/1GB"
1249 split: 3GB are mapped so that each process sees a 3GB virtual memory
1250 space and the remaining part of the 4GB virtual memory space is used
1251 by the kernel to permanently map as much physical memory as
1254 If the machine has between 1 and 4 Gigabytes physical RAM, then
1257 If more than 4 Gigabytes is used then answer "64GB" here. This
1258 selection turns Intel PAE (Physical Address Extension) mode on.
1259 PAE implements 3-level paging on IA32 processors. PAE is fully
1260 supported by Linux, PAE mode is implemented on all recent Intel
1261 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1262 then the kernel will not boot on CPUs that don't support PAE!
1264 The actual amount of total physical memory will either be
1265 auto detected or can be forced by using a kernel command line option
1266 such as "mem=256M". (Try "man bootparam" or see the documentation of
1267 your boot loader (lilo or loadlin) about how to pass options to the
1268 kernel at boot time.)
1270 If unsure, say "off".
1275 Select this if you have a 32-bit processor and between 1 and 4
1276 gigabytes of physical RAM.
1283 Select this if you have a 32-bit processor and more than 4
1284 gigabytes of physical RAM.
1289 prompt "Memory split" if EXPERT
1293 Select the desired split between kernel and user memory.
1295 If the address range available to the kernel is less than the
1296 physical memory installed, the remaining memory will be available
1297 as "high memory". Accessing high memory is a little more costly
1298 than low memory, as it needs to be mapped into the kernel first.
1299 Note that increasing the kernel address space limits the range
1300 available to user programs, making the address space there
1301 tighter. Selecting anything other than the default 3G/1G split
1302 will also likely make your kernel incompatible with binary-only
1305 If you are not absolutely sure what you are doing, leave this
1309 bool "3G/1G user/kernel split"
1310 config VMSPLIT_3G_OPT
1312 bool "3G/1G user/kernel split (for full 1G low memory)"
1314 bool "2G/2G user/kernel split"
1315 config VMSPLIT_2G_OPT
1317 bool "2G/2G user/kernel split (for full 2G low memory)"
1319 bool "1G/3G user/kernel split"
1324 default 0xB0000000 if VMSPLIT_3G_OPT
1325 default 0x80000000 if VMSPLIT_2G
1326 default 0x78000000 if VMSPLIT_2G_OPT
1327 default 0x40000000 if VMSPLIT_1G
1333 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1336 bool "PAE (Physical Address Extension) Support"
1337 depends on X86_32 && !HIGHMEM4G
1340 PAE is required for NX support, and furthermore enables
1341 larger swapspace support for non-overcommit purposes. It
1342 has the cost of more pagetable lookup overhead, and also
1343 consumes more pagetable space per process.
1345 config ARCH_PHYS_ADDR_T_64BIT
1347 depends on X86_64 || X86_PAE
1349 config ARCH_DMA_ADDR_T_64BIT
1351 depends on X86_64 || HIGHMEM64G
1353 config X86_DIRECT_GBPAGES
1355 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1357 Certain kernel features effectively disable kernel
1358 linear 1 GB mappings (even if the CPU otherwise
1359 supports them), so don't confuse the user by printing
1360 that we have them enabled.
1362 # Common NUMA Features
1364 bool "Numa Memory Allocation and Scheduler Support"
1366 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1367 default y if X86_BIGSMP
1369 Enable NUMA (Non Uniform Memory Access) support.
1371 The kernel will try to allocate memory used by a CPU on the
1372 local memory controller of the CPU and add some more
1373 NUMA awareness to the kernel.
1375 For 64-bit this is recommended if the system is Intel Core i7
1376 (or later), AMD Opteron, or EM64T NUMA.
1378 For 32-bit this is only needed if you boot a 32-bit
1379 kernel on a 64-bit NUMA platform.
1381 Otherwise, you should say N.
1385 prompt "Old style AMD Opteron NUMA detection"
1386 depends on X86_64 && NUMA && PCI
1388 Enable AMD NUMA node topology detection. You should say Y here if
1389 you have a multi processor AMD system. This uses an old method to
1390 read the NUMA configuration directly from the builtin Northbridge
1391 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1392 which also takes priority if both are compiled in.
1394 config X86_64_ACPI_NUMA
1396 prompt "ACPI NUMA detection"
1397 depends on X86_64 && NUMA && ACPI && PCI
1400 Enable ACPI SRAT based node topology detection.
1402 # Some NUMA nodes have memory ranges that span
1403 # other nodes. Even though a pfn is valid and
1404 # between a node's start and end pfns, it may not
1405 # reside on that node. See memmap_init_zone()
1407 config NODES_SPAN_OTHER_NODES
1409 depends on X86_64_ACPI_NUMA
1412 bool "NUMA emulation"
1415 Enable NUMA emulation. A flat machine will be split
1416 into virtual nodes when booted with "numa=fake=N", where N is the
1417 number of nodes. This is only useful for debugging.
1420 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1422 default "10" if MAXSMP
1423 default "6" if X86_64
1425 depends on NEED_MULTIPLE_NODES
1427 Specify the maximum number of NUMA Nodes available on the target
1428 system. Increases memory reserved to accommodate various tables.
1430 config ARCH_HAVE_MEMORY_PRESENT
1432 depends on X86_32 && DISCONTIGMEM
1434 config NEED_NODE_MEMMAP_SIZE
1436 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1438 config ARCH_FLATMEM_ENABLE
1440 depends on X86_32 && !NUMA
1442 config ARCH_DISCONTIGMEM_ENABLE
1444 depends on NUMA && X86_32
1446 config ARCH_DISCONTIGMEM_DEFAULT
1448 depends on NUMA && X86_32
1450 config ARCH_SPARSEMEM_ENABLE
1452 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1453 select SPARSEMEM_STATIC if X86_32
1454 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1456 config ARCH_SPARSEMEM_DEFAULT
1460 config ARCH_SELECT_MEMORY_MODEL
1462 depends on ARCH_SPARSEMEM_ENABLE
1464 config ARCH_MEMORY_PROBE
1465 bool "Enable sysfs memory/probe interface"
1466 depends on X86_64 && MEMORY_HOTPLUG
1468 This option enables a sysfs memory/probe interface for testing.
1469 See Documentation/memory-hotplug.txt for more information.
1470 If you are unsure how to answer this question, answer N.
1472 config ARCH_PROC_KCORE_TEXT
1474 depends on X86_64 && PROC_KCORE
1476 config ILLEGAL_POINTER_VALUE
1479 default 0xdead000000000000 if X86_64
1483 config X86_PMEM_LEGACY_DEVICE
1486 config X86_PMEM_LEGACY
1487 tristate "Support non-standard NVDIMMs and ADR protected memory"
1488 depends on PHYS_ADDR_T_64BIT
1490 select X86_PMEM_LEGACY_DEVICE
1493 Treat memory marked using the non-standard e820 type of 12 as used
1494 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1495 The kernel will offer these regions to the 'pmem' driver so
1496 they can be used for persistent storage.
1501 bool "Allocate 3rd-level pagetables from highmem"
1504 The VM uses one page table entry for each page of physical memory.
1505 For systems with a lot of RAM, this can be wasteful of precious
1506 low memory. Setting this option will put user-space page table
1507 entries in high memory.
1509 config X86_CHECK_BIOS_CORRUPTION
1510 bool "Check for low memory corruption"
1512 Periodically check for memory corruption in low memory, which
1513 is suspected to be caused by BIOS. Even when enabled in the
1514 configuration, it is disabled at runtime. Enable it by
1515 setting "memory_corruption_check=1" on the kernel command
1516 line. By default it scans the low 64k of memory every 60
1517 seconds; see the memory_corruption_check_size and
1518 memory_corruption_check_period parameters in
1519 Documentation/kernel-parameters.txt to adjust this.
1521 When enabled with the default parameters, this option has
1522 almost no overhead, as it reserves a relatively small amount
1523 of memory and scans it infrequently. It both detects corruption
1524 and prevents it from affecting the running system.
1526 It is, however, intended as a diagnostic tool; if repeatable
1527 BIOS-originated corruption always affects the same memory,
1528 you can use memmap= to prevent the kernel from using that
1531 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1532 bool "Set the default setting of memory_corruption_check"
1533 depends on X86_CHECK_BIOS_CORRUPTION
1536 Set whether the default state of memory_corruption_check is
1539 config X86_RESERVE_LOW
1540 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1544 Specify the amount of low memory to reserve for the BIOS.
1546 The first page contains BIOS data structures that the kernel
1547 must not use, so that page must always be reserved.
1549 By default we reserve the first 64K of physical RAM, as a
1550 number of BIOSes are known to corrupt that memory range
1551 during events such as suspend/resume or monitor cable
1552 insertion, so it must not be used by the kernel.
1554 You can set this to 4 if you are absolutely sure that you
1555 trust the BIOS to get all its memory reservations and usages
1556 right. If you know your BIOS have problems beyond the
1557 default 64K area, you can set this to 640 to avoid using the
1558 entire low memory range.
1560 If you have doubts about the BIOS (e.g. suspend/resume does
1561 not work or there's kernel crashes after certain hardware
1562 hotplug events) then you might want to enable
1563 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1564 typical corruption patterns.
1566 Leave this to the default value of 64 if you are unsure.
1568 config MATH_EMULATION
1570 depends on MODIFY_LDT_SYSCALL
1571 prompt "Math emulation" if X86_32
1573 Linux can emulate a math coprocessor (used for floating point
1574 operations) if you don't have one. 486DX and Pentium processors have
1575 a math coprocessor built in, 486SX and 386 do not, unless you added
1576 a 487DX or 387, respectively. (The messages during boot time can
1577 give you some hints here ["man dmesg"].) Everyone needs either a
1578 coprocessor or this emulation.
1580 If you don't have a math coprocessor, you need to say Y here; if you
1581 say Y here even though you have a coprocessor, the coprocessor will
1582 be used nevertheless. (This behavior can be changed with the kernel
1583 command line option "no387", which comes handy if your coprocessor
1584 is broken. Try "man bootparam" or see the documentation of your boot
1585 loader (lilo or loadlin) about how to pass options to the kernel at
1586 boot time.) This means that it is a good idea to say Y here if you
1587 intend to use this kernel on different machines.
1589 More information about the internals of the Linux math coprocessor
1590 emulation can be found in <file:arch/x86/math-emu/README>.
1592 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1593 kernel, it won't hurt.
1597 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1599 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1600 the Memory Type Range Registers (MTRRs) may be used to control
1601 processor access to memory ranges. This is most useful if you have
1602 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1603 allows bus write transfers to be combined into a larger transfer
1604 before bursting over the PCI/AGP bus. This can increase performance
1605 of image write operations 2.5 times or more. Saying Y here creates a
1606 /proc/mtrr file which may be used to manipulate your processor's
1607 MTRRs. Typically the X server should use this.
1609 This code has a reasonably generic interface so that similar
1610 control registers on other processors can be easily supported
1613 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1614 Registers (ARRs) which provide a similar functionality to MTRRs. For
1615 these, the ARRs are used to emulate the MTRRs.
1616 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1617 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1618 write-combining. All of these processors are supported by this code
1619 and it makes sense to say Y here if you have one of them.
1621 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1622 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1623 can lead to all sorts of problems, so it's good to say Y here.
1625 You can safely say Y even if your machine doesn't have MTRRs, you'll
1626 just add about 9 KB to your kernel.
1628 See <file:Documentation/x86/mtrr.txt> for more information.
1630 config MTRR_SANITIZER
1632 prompt "MTRR cleanup support"
1635 Convert MTRR layout from continuous to discrete, so X drivers can
1636 add writeback entries.
1638 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1639 The largest mtrr entry size for a continuous block can be set with
1644 config MTRR_SANITIZER_ENABLE_DEFAULT
1645 int "MTRR cleanup enable value (0-1)"
1648 depends on MTRR_SANITIZER
1650 Enable mtrr cleanup default value
1652 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1653 int "MTRR cleanup spare reg num (0-7)"
1656 depends on MTRR_SANITIZER
1658 mtrr cleanup spare entries default, it can be changed via
1659 mtrr_spare_reg_nr=N on the kernel command line.
1663 prompt "x86 PAT support" if EXPERT
1666 Use PAT attributes to setup page level cache control.
1668 PATs are the modern equivalents of MTRRs and are much more
1669 flexible than MTRRs.
1671 Say N here if you see bootup problems (boot crash, boot hang,
1672 spontaneous reboots) or a non-working video driver.
1676 config ARCH_USES_PG_UNCACHED
1682 prompt "x86 architectural random number generator" if EXPERT
1684 Enable the x86 architectural RDRAND instruction
1685 (Intel Bull Mountain technology) to generate random numbers.
1686 If supported, this is a high bandwidth, cryptographically
1687 secure hardware random number generator.
1691 prompt "Supervisor Mode Access Prevention" if EXPERT
1693 Supervisor Mode Access Prevention (SMAP) is a security
1694 feature in newer Intel processors. There is a small
1695 performance cost if this enabled and turned on; there is
1696 also a small increase in the kernel size if this is enabled.
1700 config X86_INTEL_MPX
1701 prompt "Intel MPX (Memory Protection Extensions)"
1703 depends on CPU_SUP_INTEL
1705 MPX provides hardware features that can be used in
1706 conjunction with compiler-instrumented code to check
1707 memory references. It is designed to detect buffer
1708 overflow or underflow bugs.
1710 This option enables running applications which are
1711 instrumented or otherwise use MPX. It does not use MPX
1712 itself inside the kernel or to protect the kernel
1713 against bad memory references.
1715 Enabling this option will make the kernel larger:
1716 ~8k of kernel text and 36 bytes of data on a 64-bit
1717 defconfig. It adds a long to the 'mm_struct' which
1718 will increase the kernel memory overhead of each
1719 process and adds some branches to paths used during
1720 exec() and munmap().
1722 For details, see Documentation/x86/intel_mpx.txt
1726 config X86_INTEL_MEMORY_PROTECTION_KEYS
1727 prompt "Intel Memory Protection Keys"
1729 # Note: only available in 64-bit mode
1730 depends on CPU_SUP_INTEL && X86_64
1732 Memory Protection Keys provides a mechanism for enforcing
1733 page-based protections, but without requiring modification of the
1734 page tables when an application changes protection domains.
1736 For details, see Documentation/x86/protection-keys.txt
1741 bool "EFI runtime service support"
1744 select EFI_RUNTIME_WRAPPERS
1746 This enables the kernel to use EFI runtime services that are
1747 available (such as the EFI variable services).
1749 This option is only useful on systems that have EFI firmware.
1750 In addition, you should use the latest ELILO loader available
1751 at <http://elilo.sourceforge.net> in order to take advantage
1752 of EFI runtime services. However, even with this option, the
1753 resultant kernel should continue to boot on existing non-EFI
1757 bool "EFI stub support"
1758 depends on EFI && !X86_USE_3DNOW
1761 This kernel feature allows a bzImage to be loaded directly
1762 by EFI firmware without the use of a bootloader.
1764 See Documentation/efi-stub.txt for more information.
1767 bool "EFI mixed-mode support"
1768 depends on EFI_STUB && X86_64
1770 Enabling this feature allows a 64-bit kernel to be booted
1771 on a 32-bit firmware, provided that your CPU supports 64-bit
1774 Note that it is not possible to boot a mixed-mode enabled
1775 kernel via the EFI boot stub - a bootloader that supports
1776 the EFI handover protocol must be used.
1782 prompt "Enable seccomp to safely compute untrusted bytecode"
1784 This kernel feature is useful for number crunching applications
1785 that may need to compute untrusted bytecode during their
1786 execution. By using pipes or other transports made available to
1787 the process as file descriptors supporting the read/write
1788 syscalls, it's possible to isolate those applications in
1789 their own address space using seccomp. Once seccomp is
1790 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1791 and the task is only allowed to execute a few safe syscalls
1792 defined by each seccomp mode.
1794 If unsure, say Y. Only embedded should say N here.
1796 source kernel/Kconfig.hz
1799 bool "kexec system call"
1802 kexec is a system call that implements the ability to shutdown your
1803 current kernel, and to start another kernel. It is like a reboot
1804 but it is independent of the system firmware. And like a reboot
1805 you can start any kernel with it, not just Linux.
1807 The name comes from the similarity to the exec system call.
1809 It is an ongoing process to be certain the hardware in a machine
1810 is properly shutdown, so do not be surprised if this code does not
1811 initially work for you. As of this writing the exact hardware
1812 interface is strongly in flux, so no good recommendation can be
1816 bool "kexec file based system call"
1821 depends on CRYPTO_SHA256=y
1823 This is new version of kexec system call. This system call is
1824 file based and takes file descriptors as system call argument
1825 for kernel and initramfs as opposed to list of segments as
1826 accepted by previous system call.
1828 config KEXEC_VERIFY_SIG
1829 bool "Verify kernel signature during kexec_file_load() syscall"
1830 depends on KEXEC_FILE
1832 This option makes kernel signature verification mandatory for
1833 the kexec_file_load() syscall.
1835 In addition to that option, you need to enable signature
1836 verification for the corresponding kernel image type being
1837 loaded in order for this to work.
1839 config KEXEC_BZIMAGE_VERIFY_SIG
1840 bool "Enable bzImage signature verification support"
1841 depends on KEXEC_VERIFY_SIG
1842 depends on SIGNED_PE_FILE_VERIFICATION
1843 select SYSTEM_TRUSTED_KEYRING
1845 Enable bzImage signature verification support.
1848 bool "kernel crash dumps"
1849 depends on X86_64 || (X86_32 && HIGHMEM)
1851 Generate crash dump after being started by kexec.
1852 This should be normally only set in special crash dump kernels
1853 which are loaded in the main kernel with kexec-tools into
1854 a specially reserved region and then later executed after
1855 a crash by kdump/kexec. The crash dump kernel must be compiled
1856 to a memory address not used by the main kernel or BIOS using
1857 PHYSICAL_START, or it must be built as a relocatable image
1858 (CONFIG_RELOCATABLE=y).
1859 For more details see Documentation/kdump/kdump.txt
1863 depends on KEXEC && HIBERNATION
1865 Jump between original kernel and kexeced kernel and invoke
1866 code in physical address mode via KEXEC
1868 config PHYSICAL_START
1869 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1872 This gives the physical address where the kernel is loaded.
1874 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1875 bzImage will decompress itself to above physical address and
1876 run from there. Otherwise, bzImage will run from the address where
1877 it has been loaded by the boot loader and will ignore above physical
1880 In normal kdump cases one does not have to set/change this option
1881 as now bzImage can be compiled as a completely relocatable image
1882 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1883 address. This option is mainly useful for the folks who don't want
1884 to use a bzImage for capturing the crash dump and want to use a
1885 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1886 to be specifically compiled to run from a specific memory area
1887 (normally a reserved region) and this option comes handy.
1889 So if you are using bzImage for capturing the crash dump,
1890 leave the value here unchanged to 0x1000000 and set
1891 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1892 for capturing the crash dump change this value to start of
1893 the reserved region. In other words, it can be set based on
1894 the "X" value as specified in the "crashkernel=YM@XM"
1895 command line boot parameter passed to the panic-ed
1896 kernel. Please take a look at Documentation/kdump/kdump.txt
1897 for more details about crash dumps.
1899 Usage of bzImage for capturing the crash dump is recommended as
1900 one does not have to build two kernels. Same kernel can be used
1901 as production kernel and capture kernel. Above option should have
1902 gone away after relocatable bzImage support is introduced. But it
1903 is present because there are users out there who continue to use
1904 vmlinux for dump capture. This option should go away down the
1907 Don't change this unless you know what you are doing.
1910 bool "Build a relocatable kernel"
1913 This builds a kernel image that retains relocation information
1914 so it can be loaded someplace besides the default 1MB.
1915 The relocations tend to make the kernel binary about 10% larger,
1916 but are discarded at runtime.
1918 One use is for the kexec on panic case where the recovery kernel
1919 must live at a different physical address than the primary
1922 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1923 it has been loaded at and the compile time physical address
1924 (CONFIG_PHYSICAL_START) is used as the minimum location.
1926 config RANDOMIZE_BASE
1927 bool "Randomize the address of the kernel image (KASLR)"
1928 depends on RELOCATABLE
1931 In support of Kernel Address Space Layout Randomization (KASLR),
1932 this randomizes the physical address at which the kernel image
1933 is decompressed and the virtual address where the kernel
1934 image is mapped, as a security feature that deters exploit
1935 attempts relying on knowledge of the location of kernel
1938 The kernel physical and virtual address can be randomized
1939 from 16MB up to 1GB on 64-bit and 512MB on 32-bit. (Note that
1940 using RANDOMIZE_BASE reduces the memory space available to
1941 kernel modules from 1.5GB to 1GB.)
1943 Entropy is generated using the RDRAND instruction if it is
1944 supported. If RDTSC is supported, its value is mixed into
1945 the entropy pool as well. If neither RDRAND nor RDTSC are
1946 supported, then entropy is read from the i8254 timer.
1948 Since the kernel is built using 2GB addressing, and
1949 PHYSICAL_ALIGN must be at a minimum of 2MB, only 10 bits of
1950 entropy is theoretically possible. Currently, with the
1951 default value for PHYSICAL_ALIGN and due to page table
1952 layouts, 64-bit uses 9 bits of entropy and 32-bit uses 8 bits.
1954 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1955 time. To enable it, boot with "kaslr" on the kernel command
1956 line (which will also disable hibernation).
1960 # Relocation on x86 needs some additional build support
1961 config X86_NEED_RELOCS
1963 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1965 config PHYSICAL_ALIGN
1966 hex "Alignment value to which kernel should be aligned"
1968 range 0x2000 0x1000000 if X86_32
1969 range 0x200000 0x1000000 if X86_64
1971 This value puts the alignment restrictions on physical address
1972 where kernel is loaded and run from. Kernel is compiled for an
1973 address which meets above alignment restriction.
1975 If bootloader loads the kernel at a non-aligned address and
1976 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1977 address aligned to above value and run from there.
1979 If bootloader loads the kernel at a non-aligned address and
1980 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1981 load address and decompress itself to the address it has been
1982 compiled for and run from there. The address for which kernel is
1983 compiled already meets above alignment restrictions. Hence the
1984 end result is that kernel runs from a physical address meeting
1985 above alignment restrictions.
1987 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1988 this value must be a multiple of 0x200000.
1990 Don't change this unless you know what you are doing.
1993 bool "Support for hot-pluggable CPUs"
1996 Say Y here to allow turning CPUs off and on. CPUs can be
1997 controlled through /sys/devices/system/cpu.
1998 ( Note: power management support will enable this option
1999 automatically on SMP systems. )
2000 Say N if you want to disable CPU hotplug.
2002 config BOOTPARAM_HOTPLUG_CPU0
2003 bool "Set default setting of cpu0_hotpluggable"
2005 depends on HOTPLUG_CPU
2007 Set whether default state of cpu0_hotpluggable is on or off.
2009 Say Y here to enable CPU0 hotplug by default. If this switch
2010 is turned on, there is no need to give cpu0_hotplug kernel
2011 parameter and the CPU0 hotplug feature is enabled by default.
2013 Please note: there are two known CPU0 dependencies if you want
2014 to enable the CPU0 hotplug feature either by this switch or by
2015 cpu0_hotplug kernel parameter.
2017 First, resume from hibernate or suspend always starts from CPU0.
2018 So hibernate and suspend are prevented if CPU0 is offline.
2020 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2021 offline if any interrupt can not migrate out of CPU0. There may
2022 be other CPU0 dependencies.
2024 Please make sure the dependencies are under your control before
2025 you enable this feature.
2027 Say N if you don't want to enable CPU0 hotplug feature by default.
2028 You still can enable the CPU0 hotplug feature at boot by kernel
2029 parameter cpu0_hotplug.
2031 config DEBUG_HOTPLUG_CPU0
2033 prompt "Debug CPU0 hotplug"
2034 depends on HOTPLUG_CPU
2036 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2037 soon as possible and boots up userspace with CPU0 offlined. User
2038 can online CPU0 back after boot time.
2040 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2041 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2042 compilation or giving cpu0_hotplug kernel parameter at boot.
2048 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2049 depends on X86_32 || IA32_EMULATION
2051 Certain buggy versions of glibc will crash if they are
2052 presented with a 32-bit vDSO that is not mapped at the address
2053 indicated in its segment table.
2055 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2056 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2057 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2058 the only released version with the bug, but OpenSUSE 9
2059 contains a buggy "glibc 2.3.2".
2061 The symptom of the bug is that everything crashes on startup, saying:
2062 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2064 Saying Y here changes the default value of the vdso32 boot
2065 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2066 This works around the glibc bug but hurts performance.
2068 If unsure, say N: if you are compiling your own kernel, you
2069 are unlikely to be using a buggy version of glibc.
2072 prompt "vsyscall table for legacy applications"
2074 default LEGACY_VSYSCALL_EMULATE
2076 Legacy user code that does not know how to find the vDSO expects
2077 to be able to issue three syscalls by calling fixed addresses in
2078 kernel space. Since this location is not randomized with ASLR,
2079 it can be used to assist security vulnerability exploitation.
2081 This setting can be changed at boot time via the kernel command
2082 line parameter vsyscall=[native|emulate|none].
2084 On a system with recent enough glibc (2.14 or newer) and no
2085 static binaries, you can say None without a performance penalty
2086 to improve security.
2088 If unsure, select "Emulate".
2090 config LEGACY_VSYSCALL_NATIVE
2093 Actual executable code is located in the fixed vsyscall
2094 address mapping, implementing time() efficiently. Since
2095 this makes the mapping executable, it can be used during
2096 security vulnerability exploitation (traditionally as
2097 ROP gadgets). This configuration is not recommended.
2099 config LEGACY_VSYSCALL_EMULATE
2102 The kernel traps and emulates calls into the fixed
2103 vsyscall address mapping. This makes the mapping
2104 non-executable, but it still contains known contents,
2105 which could be used in certain rare security vulnerability
2106 exploits. This configuration is recommended when userspace
2107 still uses the vsyscall area.
2109 config LEGACY_VSYSCALL_NONE
2112 There will be no vsyscall mapping at all. This will
2113 eliminate any risk of ASLR bypass due to the vsyscall
2114 fixed address mapping. Attempts to use the vsyscalls
2115 will be reported to dmesg, so that either old or
2116 malicious userspace programs can be identified.
2121 bool "Built-in kernel command line"
2123 Allow for specifying boot arguments to the kernel at
2124 build time. On some systems (e.g. embedded ones), it is
2125 necessary or convenient to provide some or all of the
2126 kernel boot arguments with the kernel itself (that is,
2127 to not rely on the boot loader to provide them.)
2129 To compile command line arguments into the kernel,
2130 set this option to 'Y', then fill in the
2131 boot arguments in CONFIG_CMDLINE.
2133 Systems with fully functional boot loaders (i.e. non-embedded)
2134 should leave this option set to 'N'.
2137 string "Built-in kernel command string"
2138 depends on CMDLINE_BOOL
2141 Enter arguments here that should be compiled into the kernel
2142 image and used at boot time. If the boot loader provides a
2143 command line at boot time, it is appended to this string to
2144 form the full kernel command line, when the system boots.
2146 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2147 change this behavior.
2149 In most cases, the command line (whether built-in or provided
2150 by the boot loader) should specify the device for the root
2153 config CMDLINE_OVERRIDE
2154 bool "Built-in command line overrides boot loader arguments"
2155 depends on CMDLINE_BOOL
2157 Set this option to 'Y' to have the kernel ignore the boot loader
2158 command line, and use ONLY the built-in command line.
2160 This is used to work around broken boot loaders. This should
2161 be set to 'N' under normal conditions.
2163 config MODIFY_LDT_SYSCALL
2164 bool "Enable the LDT (local descriptor table)" if EXPERT
2167 Linux can allow user programs to install a per-process x86
2168 Local Descriptor Table (LDT) using the modify_ldt(2) system
2169 call. This is required to run 16-bit or segmented code such as
2170 DOSEMU or some Wine programs. It is also used by some very old
2171 threading libraries.
2173 Enabling this feature adds a small amount of overhead to
2174 context switches and increases the low-level kernel attack
2175 surface. Disabling it removes the modify_ldt(2) system call.
2177 Saying 'N' here may make sense for embedded or server kernels.
2179 source "kernel/livepatch/Kconfig"
2183 config ARCH_ENABLE_MEMORY_HOTPLUG
2185 depends on X86_64 || (X86_32 && HIGHMEM)
2187 config ARCH_ENABLE_MEMORY_HOTREMOVE
2189 depends on MEMORY_HOTPLUG
2191 config USE_PERCPU_NUMA_NODE_ID
2195 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2197 depends on X86_64 || X86_PAE
2199 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2201 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2203 menu "Power management and ACPI options"
2205 config ARCH_HIBERNATION_HEADER
2207 depends on X86_64 && HIBERNATION
2209 source "kernel/power/Kconfig"
2211 source "drivers/acpi/Kconfig"
2213 source "drivers/sfi/Kconfig"
2220 tristate "APM (Advanced Power Management) BIOS support"
2221 depends on X86_32 && PM_SLEEP
2223 APM is a BIOS specification for saving power using several different
2224 techniques. This is mostly useful for battery powered laptops with
2225 APM compliant BIOSes. If you say Y here, the system time will be
2226 reset after a RESUME operation, the /proc/apm device will provide
2227 battery status information, and user-space programs will receive
2228 notification of APM "events" (e.g. battery status change).
2230 If you select "Y" here, you can disable actual use of the APM
2231 BIOS by passing the "apm=off" option to the kernel at boot time.
2233 Note that the APM support is almost completely disabled for
2234 machines with more than one CPU.
2236 In order to use APM, you will need supporting software. For location
2237 and more information, read <file:Documentation/power/apm-acpi.txt>
2238 and the Battery Powered Linux mini-HOWTO, available from
2239 <http://www.tldp.org/docs.html#howto>.
2241 This driver does not spin down disk drives (see the hdparm(8)
2242 manpage ("man 8 hdparm") for that), and it doesn't turn off
2243 VESA-compliant "green" monitors.
2245 This driver does not support the TI 4000M TravelMate and the ACER
2246 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2247 desktop machines also don't have compliant BIOSes, and this driver
2248 may cause those machines to panic during the boot phase.
2250 Generally, if you don't have a battery in your machine, there isn't
2251 much point in using this driver and you should say N. If you get
2252 random kernel OOPSes or reboots that don't seem to be related to
2253 anything, try disabling/enabling this option (or disabling/enabling
2256 Some other things you should try when experiencing seemingly random,
2259 1) make sure that you have enough swap space and that it is
2261 2) pass the "no-hlt" option to the kernel
2262 3) switch on floating point emulation in the kernel and pass
2263 the "no387" option to the kernel
2264 4) pass the "floppy=nodma" option to the kernel
2265 5) pass the "mem=4M" option to the kernel (thereby disabling
2266 all but the first 4 MB of RAM)
2267 6) make sure that the CPU is not over clocked.
2268 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2269 8) disable the cache from your BIOS settings
2270 9) install a fan for the video card or exchange video RAM
2271 10) install a better fan for the CPU
2272 11) exchange RAM chips
2273 12) exchange the motherboard.
2275 To compile this driver as a module, choose M here: the
2276 module will be called apm.
2280 config APM_IGNORE_USER_SUSPEND
2281 bool "Ignore USER SUSPEND"
2283 This option will ignore USER SUSPEND requests. On machines with a
2284 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2285 series notebooks, it is necessary to say Y because of a BIOS bug.
2287 config APM_DO_ENABLE
2288 bool "Enable PM at boot time"
2290 Enable APM features at boot time. From page 36 of the APM BIOS
2291 specification: "When disabled, the APM BIOS does not automatically
2292 power manage devices, enter the Standby State, enter the Suspend
2293 State, or take power saving steps in response to CPU Idle calls."
2294 This driver will make CPU Idle calls when Linux is idle (unless this
2295 feature is turned off -- see "Do CPU IDLE calls", below). This
2296 should always save battery power, but more complicated APM features
2297 will be dependent on your BIOS implementation. You may need to turn
2298 this option off if your computer hangs at boot time when using APM
2299 support, or if it beeps continuously instead of suspending. Turn
2300 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2301 T400CDT. This is off by default since most machines do fine without
2306 bool "Make CPU Idle calls when idle"
2308 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2309 On some machines, this can activate improved power savings, such as
2310 a slowed CPU clock rate, when the machine is idle. These idle calls
2311 are made after the idle loop has run for some length of time (e.g.,
2312 333 mS). On some machines, this will cause a hang at boot time or
2313 whenever the CPU becomes idle. (On machines with more than one CPU,
2314 this option does nothing.)
2316 config APM_DISPLAY_BLANK
2317 bool "Enable console blanking using APM"
2319 Enable console blanking using the APM. Some laptops can use this to
2320 turn off the LCD backlight when the screen blanker of the Linux
2321 virtual console blanks the screen. Note that this is only used by
2322 the virtual console screen blanker, and won't turn off the backlight
2323 when using the X Window system. This also doesn't have anything to
2324 do with your VESA-compliant power-saving monitor. Further, this
2325 option doesn't work for all laptops -- it might not turn off your
2326 backlight at all, or it might print a lot of errors to the console,
2327 especially if you are using gpm.
2329 config APM_ALLOW_INTS
2330 bool "Allow interrupts during APM BIOS calls"
2332 Normally we disable external interrupts while we are making calls to
2333 the APM BIOS as a measure to lessen the effects of a badly behaving
2334 BIOS implementation. The BIOS should reenable interrupts if it
2335 needs to. Unfortunately, some BIOSes do not -- especially those in
2336 many of the newer IBM Thinkpads. If you experience hangs when you
2337 suspend, try setting this to Y. Otherwise, say N.
2341 source "drivers/cpufreq/Kconfig"
2343 source "drivers/cpuidle/Kconfig"
2345 source "drivers/idle/Kconfig"
2350 menu "Bus options (PCI etc.)"
2356 Find out whether you have a PCI motherboard. PCI is the name of a
2357 bus system, i.e. the way the CPU talks to the other stuff inside
2358 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2359 VESA. If you have PCI, say Y, otherwise N.
2362 prompt "PCI access mode"
2363 depends on X86_32 && PCI
2366 On PCI systems, the BIOS can be used to detect the PCI devices and
2367 determine their configuration. However, some old PCI motherboards
2368 have BIOS bugs and may crash if this is done. Also, some embedded
2369 PCI-based systems don't have any BIOS at all. Linux can also try to
2370 detect the PCI hardware directly without using the BIOS.
2372 With this option, you can specify how Linux should detect the
2373 PCI devices. If you choose "BIOS", the BIOS will be used,
2374 if you choose "Direct", the BIOS won't be used, and if you
2375 choose "MMConfig", then PCI Express MMCONFIG will be used.
2376 If you choose "Any", the kernel will try MMCONFIG, then the
2377 direct access method and falls back to the BIOS if that doesn't
2378 work. If unsure, go with the default, which is "Any".
2383 config PCI_GOMMCONFIG
2400 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2402 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2405 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2409 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2413 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2417 depends on PCI && XEN
2425 bool "Support mmconfig PCI config space access"
2426 depends on X86_64 && PCI && ACPI
2428 config PCI_CNB20LE_QUIRK
2429 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2432 Read the PCI windows out of the CNB20LE host bridge. This allows
2433 PCI hotplug to work on systems with the CNB20LE chipset which do
2436 There's no public spec for this chipset, and this functionality
2437 is known to be incomplete.
2439 You should say N unless you know you need this.
2441 source "drivers/pci/Kconfig"
2443 # x86_64 have no ISA slots, but can have ISA-style DMA.
2445 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2448 Enables ISA-style DMA support for devices requiring such controllers.
2456 Find out whether you have ISA slots on your motherboard. ISA is the
2457 name of a bus system, i.e. the way the CPU talks to the other stuff
2458 inside your box. Other bus systems are PCI, EISA, MicroChannel
2459 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2460 newer boards don't support it. If you have ISA, say Y, otherwise N.
2466 The Extended Industry Standard Architecture (EISA) bus was
2467 developed as an open alternative to the IBM MicroChannel bus.
2469 The EISA bus provided some of the features of the IBM MicroChannel
2470 bus while maintaining backward compatibility with cards made for
2471 the older ISA bus. The EISA bus saw limited use between 1988 and
2472 1995 when it was made obsolete by the PCI bus.
2474 Say Y here if you are building a kernel for an EISA-based machine.
2478 source "drivers/eisa/Kconfig"
2481 tristate "NatSemi SCx200 support"
2483 This provides basic support for National Semiconductor's
2484 (now AMD's) Geode processors. The driver probes for the
2485 PCI-IDs of several on-chip devices, so its a good dependency
2486 for other scx200_* drivers.
2488 If compiled as a module, the driver is named scx200.
2490 config SCx200HR_TIMER
2491 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2495 This driver provides a clocksource built upon the on-chip
2496 27MHz high-resolution timer. Its also a workaround for
2497 NSC Geode SC-1100's buggy TSC, which loses time when the
2498 processor goes idle (as is done by the scheduler). The
2499 other workaround is idle=poll boot option.
2502 bool "One Laptop Per Child support"
2509 Add support for detecting the unique features of the OLPC
2513 bool "OLPC XO-1 Power Management"
2514 depends on OLPC && MFD_CS5535 && PM_SLEEP
2517 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2520 bool "OLPC XO-1 Real Time Clock"
2521 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2523 Add support for the XO-1 real time clock, which can be used as a
2524 programmable wakeup source.
2527 bool "OLPC XO-1 SCI extras"
2528 depends on OLPC && OLPC_XO1_PM
2534 Add support for SCI-based features of the OLPC XO-1 laptop:
2535 - EC-driven system wakeups
2539 - AC adapter status updates
2540 - Battery status updates
2542 config OLPC_XO15_SCI
2543 bool "OLPC XO-1.5 SCI extras"
2544 depends on OLPC && ACPI
2547 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2548 - EC-driven system wakeups
2549 - AC adapter status updates
2550 - Battery status updates
2553 bool "PCEngines ALIX System Support (LED setup)"
2556 This option enables system support for the PCEngines ALIX.
2557 At present this just sets up LEDs for GPIO control on
2558 ALIX2/3/6 boards. However, other system specific setup should
2561 Note: You must still enable the drivers for GPIO and LED support
2562 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2564 Note: You have to set alix.force=1 for boards with Award BIOS.
2567 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2570 This option enables system support for the Soekris Engineering net5501.
2573 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2577 This option enables system support for the Traverse Technologies GEOS.
2580 bool "Technologic Systems TS-5500 platform support"
2582 select CHECK_SIGNATURE
2586 This option enables system support for the Technologic Systems TS-5500.
2592 depends on CPU_SUP_AMD && PCI
2594 source "drivers/pcmcia/Kconfig"
2597 tristate "RapidIO support"
2601 If enabled this option will include drivers and the core
2602 infrastructure code to support RapidIO interconnect devices.
2604 source "drivers/rapidio/Kconfig"
2607 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2609 Firmwares often provide initial graphics framebuffers so the BIOS,
2610 bootloader or kernel can show basic video-output during boot for
2611 user-guidance and debugging. Historically, x86 used the VESA BIOS
2612 Extensions and EFI-framebuffers for this, which are mostly limited
2614 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2615 framebuffers so the new generic system-framebuffer drivers can be
2616 used on x86. If the framebuffer is not compatible with the generic
2617 modes, it is adverticed as fallback platform framebuffer so legacy
2618 drivers like efifb, vesafb and uvesafb can pick it up.
2619 If this option is not selected, all system framebuffers are always
2620 marked as fallback platform framebuffers as usual.
2622 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2623 not be able to pick up generic system framebuffers if this option
2624 is selected. You are highly encouraged to enable simplefb as
2625 replacement if you select this option. simplefb can correctly deal
2626 with generic system framebuffers. But you should still keep vesafb
2627 and others enabled as fallback if a system framebuffer is
2628 incompatible with simplefb.
2635 menu "Executable file formats / Emulations"
2637 source "fs/Kconfig.binfmt"
2639 config IA32_EMULATION
2640 bool "IA32 Emulation"
2643 select COMPAT_BINFMT_ELF
2644 select ARCH_WANT_OLD_COMPAT_IPC
2646 Include code to run legacy 32-bit programs under a
2647 64-bit kernel. You should likely turn this on, unless you're
2648 100% sure that you don't have any 32-bit programs left.
2651 tristate "IA32 a.out support"
2652 depends on IA32_EMULATION
2654 Support old a.out binaries in the 32bit emulation.
2657 bool "x32 ABI for 64-bit mode"
2660 Include code to run binaries for the x32 native 32-bit ABI
2661 for 64-bit processors. An x32 process gets access to the
2662 full 64-bit register file and wide data path while leaving
2663 pointers at 32 bits for smaller memory footprint.
2665 You will need a recent binutils (2.22 or later) with
2666 elf32_x86_64 support enabled to compile a kernel with this
2671 depends on IA32_EMULATION || X86_X32
2674 config COMPAT_FOR_U64_ALIGNMENT
2677 config SYSVIPC_COMPAT
2689 config HAVE_ATOMIC_IOMAP
2693 config X86_DEV_DMA_OPS
2695 depends on X86_64 || STA2X11
2697 config X86_DMA_REMAP
2707 tristate "Volume Management Device Driver"
2710 Adds support for the Intel Volume Management Device (VMD). VMD is a
2711 secondary PCI host bridge that allows PCI Express root ports,
2712 and devices attached to them, to be removed from the default
2713 PCI domain and placed within the VMD domain. This provides
2714 more bus resources than are otherwise possible with a
2715 single domain. If you know your system provides one of these and
2716 has devices attached to it, say Y; if you are not sure, say N.
2718 source "net/Kconfig"
2720 source "drivers/Kconfig"
2722 source "drivers/firmware/Kconfig"
2726 source "arch/x86/Kconfig.debug"
2728 source "security/Kconfig"
2730 source "crypto/Kconfig"
2732 source "arch/x86/kvm/Kconfig"
2734 source "lib/Kconfig"