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_BPF_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_FENTRY if X86_64
109 select HAVE_FTRACE_MCOUNT_RECORD
110 select HAVE_FUNCTION_GRAPH_FP_TEST
111 select HAVE_FUNCTION_GRAPH_TRACER
112 select HAVE_FUNCTION_TRACER
113 select HAVE_GENERIC_DMA_COHERENT if X86_32
114 select HAVE_HW_BREAKPOINT
116 select HAVE_IOREMAP_PROT
117 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
118 select HAVE_IRQ_TIME_ACCOUNTING
119 select HAVE_KERNEL_BZIP2
120 select HAVE_KERNEL_GZIP
121 select HAVE_KERNEL_LZ4
122 select HAVE_KERNEL_LZMA
123 select HAVE_KERNEL_LZO
124 select HAVE_KERNEL_XZ
126 select HAVE_KPROBES_ON_FTRACE
127 select HAVE_KRETPROBES
129 select HAVE_LIVEPATCH if X86_64
131 select HAVE_MEMBLOCK_NODE_MAP
132 select HAVE_MIXED_BREAKPOINTS_REGS
134 select HAVE_OPTPROBES
135 select HAVE_PCSPKR_PLATFORM
136 select HAVE_PERF_EVENTS
137 select HAVE_PERF_EVENTS_NMI
138 select HAVE_PERF_REGS
139 select HAVE_PERF_USER_STACK_DUMP
140 select HAVE_REGS_AND_STACK_ACCESS_API
141 select HAVE_SYSCALL_TRACEPOINTS
142 select HAVE_UID16 if X86_32 || IA32_EMULATION
143 select HAVE_UNSTABLE_SCHED_CLOCK
144 select HAVE_USER_RETURN_NOTIFIER
145 select IRQ_FORCED_THREADING
146 select MODULES_USE_ELF_RELA if X86_64
147 select MODULES_USE_ELF_REL if X86_32
148 select OLD_SIGACTION if X86_32
149 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
154 select SYSCTL_EXCEPTION_TRACE
155 select USER_STACKTRACE_SUPPORT
157 select X86_DEV_DMA_OPS if X86_64
158 select X86_FEATURE_NAMES if PROC_FS
159 select HAVE_STACK_VALIDATION if X86_64
160 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
161 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
163 config INSTRUCTION_DECODER
165 depends on KPROBES || PERF_EVENTS || UPROBES
167 config PERF_EVENTS_INTEL_UNCORE
169 depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
173 default "elf32-i386" if X86_32
174 default "elf64-x86-64" if X86_64
176 config ARCH_DEFCONFIG
178 default "arch/x86/configs/i386_defconfig" if X86_32
179 default "arch/x86/configs/x86_64_defconfig" if X86_64
181 config LOCKDEP_SUPPORT
184 config STACKTRACE_SUPPORT
190 config ARCH_MMAP_RND_BITS_MIN
194 config ARCH_MMAP_RND_BITS_MAX
198 config ARCH_MMAP_RND_COMPAT_BITS_MIN
201 config ARCH_MMAP_RND_COMPAT_BITS_MAX
207 config NEED_DMA_MAP_STATE
209 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
211 config NEED_SG_DMA_LENGTH
214 config GENERIC_ISA_DMA
216 depends on ISA_DMA_API
221 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
223 config GENERIC_BUG_RELATIVE_POINTERS
226 config GENERIC_HWEIGHT
229 config ARCH_MAY_HAVE_PC_FDC
231 depends on ISA_DMA_API
233 config RWSEM_XCHGADD_ALGORITHM
236 config GENERIC_CALIBRATE_DELAY
239 config ARCH_HAS_CPU_RELAX
242 config ARCH_HAS_CACHE_LINE_SIZE
245 config HAVE_SETUP_PER_CPU_AREA
248 config NEED_PER_CPU_EMBED_FIRST_CHUNK
251 config NEED_PER_CPU_PAGE_FIRST_CHUNK
254 config ARCH_HIBERNATION_POSSIBLE
257 config ARCH_SUSPEND_POSSIBLE
260 config ARCH_WANT_HUGE_PMD_SHARE
263 config ARCH_WANT_GENERAL_HUGETLB
272 config ARCH_SUPPORTS_OPTIMIZED_INLINING
275 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
278 config KASAN_SHADOW_OFFSET
281 default 0xdffffc0000000000
283 config HAVE_INTEL_TXT
285 depends on INTEL_IOMMU && ACPI
289 depends on X86_32 && SMP
293 depends on X86_64 && SMP
295 config X86_32_LAZY_GS
297 depends on X86_32 && !CC_STACKPROTECTOR
299 config ARCH_HWEIGHT_CFLAGS
301 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
302 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
304 config ARCH_SUPPORTS_UPROBES
307 config FIX_EARLYCON_MEM
313 config PGTABLE_LEVELS
319 source "init/Kconfig"
320 source "kernel/Kconfig.freezer"
322 menu "Processor type and features"
325 bool "DMA memory allocation support" if EXPERT
328 DMA memory allocation support allows devices with less than 32-bit
329 addressing to allocate within the first 16MB of address space.
330 Disable if no such devices will be used.
335 bool "Symmetric multi-processing support"
337 This enables support for systems with more than one CPU. If you have
338 a system with only one CPU, say N. If you have a system with more
341 If you say N here, the kernel will run on uni- and multiprocessor
342 machines, but will use only one CPU of a multiprocessor machine. If
343 you say Y here, the kernel will run on many, but not all,
344 uniprocessor machines. On a uniprocessor machine, the kernel
345 will run faster if you say N here.
347 Note that if you say Y here and choose architecture "586" or
348 "Pentium" under "Processor family", the kernel will not work on 486
349 architectures. Similarly, multiprocessor kernels for the "PPro"
350 architecture may not work on all Pentium based boards.
352 People using multiprocessor machines who say Y here should also say
353 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
354 Management" code will be disabled if you say Y here.
356 See also <file:Documentation/x86/i386/IO-APIC.txt>,
357 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
358 <http://www.tldp.org/docs.html#howto>.
360 If you don't know what to do here, say N.
362 config X86_FEATURE_NAMES
363 bool "Processor feature human-readable names" if EMBEDDED
366 This option compiles in a table of x86 feature bits and corresponding
367 names. This is required to support /proc/cpuinfo and a few kernel
368 messages. You can disable this to save space, at the expense of
369 making those few kernel messages show numeric feature bits instead.
373 config X86_FAST_FEATURE_TESTS
374 bool "Fast CPU feature tests" if EMBEDDED
377 Some fast-paths in the kernel depend on the capabilities of the CPU.
378 Say Y here for the kernel to patch in the appropriate code at runtime
379 based on the capabilities of the CPU. The infrastructure for patching
380 code at runtime takes up some additional space; space-constrained
381 embedded systems may wish to say N here to produce smaller, slightly
385 bool "Support x2apic"
386 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
388 This enables x2apic support on CPUs that have this feature.
390 This allows 32-bit apic IDs (so it can support very large systems),
391 and accesses the local apic via MSRs not via mmio.
393 If you don't know what to do here, say N.
396 bool "Enable MPS table" if ACPI || SFI
398 depends on X86_LOCAL_APIC
400 For old smp systems that do not have proper acpi support. Newer systems
401 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
404 bool "Support for big SMP systems with more than 8 CPUs"
405 depends on X86_32 && SMP
407 This option is needed for the systems that have more than 8 CPUs
411 depends on X86_GOLDFISH
414 config X86_EXTENDED_PLATFORM
415 bool "Support for extended (non-PC) x86 platforms"
418 If you disable this option then the kernel will only support
419 standard PC platforms. (which covers the vast majority of
422 If you enable this option then you'll be able to select support
423 for the following (non-PC) 32 bit x86 platforms:
424 Goldfish (Android emulator)
427 SGI 320/540 (Visual Workstation)
428 STA2X11-based (e.g. Northville)
429 Moorestown MID devices
431 If you have one of these systems, or if you want to build a
432 generic distribution kernel, say Y here - otherwise say N.
436 config X86_EXTENDED_PLATFORM
437 bool "Support for extended (non-PC) x86 platforms"
440 If you disable this option then the kernel will only support
441 standard PC platforms. (which covers the vast majority of
444 If you enable this option then you'll be able to select support
445 for the following (non-PC) 64 bit x86 platforms:
450 If you have one of these systems, or if you want to build a
451 generic distribution kernel, say Y here - otherwise say N.
453 # This is an alphabetically sorted list of 64 bit extended platforms
454 # Please maintain the alphabetic order if and when there are additions
456 bool "Numascale NumaChip"
458 depends on X86_EXTENDED_PLATFORM
461 depends on X86_X2APIC
462 depends on PCI_MMCONFIG
464 Adds support for Numascale NumaChip large-SMP systems. Needed to
465 enable more than ~168 cores.
466 If you don't have one of these, you should say N here.
470 select HYPERVISOR_GUEST
472 depends on X86_64 && PCI
473 depends on X86_EXTENDED_PLATFORM
476 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
477 supposed to run on these EM64T-based machines. Only choose this option
478 if you have one of these machines.
481 bool "SGI Ultraviolet"
483 depends on X86_EXTENDED_PLATFORM
486 depends on X86_X2APIC
489 This option is needed in order to support SGI Ultraviolet systems.
490 If you don't have one of these, you should say N here.
492 # Following is an alphabetically sorted list of 32 bit extended platforms
493 # Please maintain the alphabetic order if and when there are additions
496 bool "Goldfish (Virtual Platform)"
497 depends on X86_EXTENDED_PLATFORM
499 Enable support for the Goldfish virtual platform used primarily
500 for Android development. Unless you are building for the Android
501 Goldfish emulator say N here.
504 bool "CE4100 TV platform"
506 depends on PCI_GODIRECT
507 depends on X86_IO_APIC
509 depends on X86_EXTENDED_PLATFORM
510 select X86_REBOOTFIXUPS
512 select OF_EARLY_FLATTREE
514 Select for the Intel CE media processor (CE4100) SOC.
515 This option compiles in support for the CE4100 SOC for settop
516 boxes and media devices.
519 bool "Intel MID platform support"
520 depends on X86_EXTENDED_PLATFORM
521 depends on X86_PLATFORM_DEVICES
523 depends on X86_64 || (PCI_GOANY && X86_32)
524 depends on X86_IO_APIC
530 select MFD_INTEL_MSIC
532 Select to build a kernel capable of supporting Intel MID (Mobile
533 Internet Device) platform systems which do not have the PCI legacy
534 interfaces. If you are building for a PC class system say N here.
536 Intel MID platforms are based on an Intel processor and chipset which
537 consume less power than most of the x86 derivatives.
539 config X86_INTEL_QUARK
540 bool "Intel Quark platform support"
542 depends on X86_EXTENDED_PLATFORM
543 depends on X86_PLATFORM_DEVICES
547 depends on X86_IO_APIC
552 Select to include support for Quark X1000 SoC.
553 Say Y here if you have a Quark based system such as the Arduino
554 compatible Intel Galileo.
556 config X86_INTEL_LPSS
557 bool "Intel Low Power Subsystem Support"
558 depends on X86 && ACPI
563 Select to build support for Intel Low Power Subsystem such as
564 found on Intel Lynxpoint PCH. Selecting this option enables
565 things like clock tree (common clock framework) and pincontrol
566 which are needed by the LPSS peripheral drivers.
568 config X86_AMD_PLATFORM_DEVICE
569 bool "AMD ACPI2Platform devices support"
574 Select to interpret AMD specific ACPI device to platform device
575 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
576 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
577 implemented under PINCTRL subsystem.
580 tristate "Intel SoC IOSF Sideband support for SoC platforms"
583 This option enables sideband register access support for Intel SoC
584 platforms. On these platforms the IOSF sideband is used in lieu of
585 MSR's for some register accesses, mostly but not limited to thermal
586 and power. Drivers may query the availability of this device to
587 determine if they need the sideband in order to work on these
588 platforms. The sideband is available on the following SoC products.
589 This list is not meant to be exclusive.
594 You should say Y if you are running a kernel on one of these SoC's.
596 config IOSF_MBI_DEBUG
597 bool "Enable IOSF sideband access through debugfs"
598 depends on IOSF_MBI && DEBUG_FS
600 Select this option to expose the IOSF sideband access registers (MCR,
601 MDR, MCRX) through debugfs to write and read register information from
602 different units on the SoC. This is most useful for obtaining device
603 state information for debug and analysis. As this is a general access
604 mechanism, users of this option would have specific knowledge of the
605 device they want to access.
607 If you don't require the option or are in doubt, say N.
610 bool "RDC R-321x SoC"
612 depends on X86_EXTENDED_PLATFORM
614 select X86_REBOOTFIXUPS
616 This option is needed for RDC R-321x system-on-chip, also known
618 If you don't have one of these chips, you should say N here.
620 config X86_32_NON_STANDARD
621 bool "Support non-standard 32-bit SMP architectures"
622 depends on X86_32 && SMP
623 depends on X86_EXTENDED_PLATFORM
625 This option compiles in the bigsmp and STA2X11 default
626 subarchitectures. It is intended for a generic binary
627 kernel. If you select them all, kernel will probe it one by
628 one and will fallback to default.
630 # Alphabetically sorted list of Non standard 32 bit platforms
632 config X86_SUPPORTS_MEMORY_FAILURE
634 # MCE code calls memory_failure():
636 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
637 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
638 depends on X86_64 || !SPARSEMEM
639 select ARCH_SUPPORTS_MEMORY_FAILURE
642 bool "STA2X11 Companion Chip Support"
643 depends on X86_32_NON_STANDARD && PCI
644 select X86_DEV_DMA_OPS
648 select ARCH_REQUIRE_GPIOLIB
651 This adds support for boards based on the STA2X11 IO-Hub,
652 a.k.a. "ConneXt". The chip is used in place of the standard
653 PC chipset, so all "standard" peripherals are missing. If this
654 option is selected the kernel will still be able to boot on
655 standard PC machines.
658 tristate "Eurobraille/Iris poweroff module"
661 The Iris machines from EuroBraille do not have APM or ACPI support
662 to shut themselves down properly. A special I/O sequence is
663 needed to do so, which is what this module does at
666 This is only for Iris machines from EuroBraille.
670 config SCHED_OMIT_FRAME_POINTER
672 prompt "Single-depth WCHAN output"
675 Calculate simpler /proc/<PID>/wchan values. If this option
676 is disabled then wchan values will recurse back to the
677 caller function. This provides more accurate wchan values,
678 at the expense of slightly more scheduling overhead.
680 If in doubt, say "Y".
682 menuconfig HYPERVISOR_GUEST
683 bool "Linux guest support"
685 Say Y here to enable options for running Linux under various hyper-
686 visors. This option enables basic hypervisor detection and platform
689 If you say N, all options in this submenu will be skipped and
690 disabled, and Linux guest support won't be built in.
695 bool "Enable paravirtualization code"
697 This changes the kernel so it can modify itself when it is run
698 under a hypervisor, potentially improving performance significantly
699 over full virtualization. However, when run without a hypervisor
700 the kernel is theoretically slower and slightly larger.
702 config PARAVIRT_DEBUG
703 bool "paravirt-ops debugging"
704 depends on PARAVIRT && DEBUG_KERNEL
706 Enable to debug paravirt_ops internals. Specifically, BUG if
707 a paravirt_op is missing when it is called.
709 config PARAVIRT_SPINLOCKS
710 bool "Paravirtualization layer for spinlocks"
711 depends on PARAVIRT && SMP
712 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
714 Paravirtualized spinlocks allow a pvops backend to replace the
715 spinlock implementation with something virtualization-friendly
716 (for example, block the virtual CPU rather than spinning).
718 It has a minimal impact on native kernels and gives a nice performance
719 benefit on paravirtualized KVM / Xen kernels.
721 If you are unsure how to answer this question, answer Y.
723 config QUEUED_LOCK_STAT
724 bool "Paravirt queued spinlock statistics"
725 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
727 Enable the collection of statistical data on the slowpath
728 behavior of paravirtualized queued spinlocks and report
731 source "arch/x86/xen/Kconfig"
734 bool "KVM Guest support (including kvmclock)"
736 select PARAVIRT_CLOCK
739 This option enables various optimizations for running under the KVM
740 hypervisor. It includes a paravirtualized clock, so that instead
741 of relying on a PIT (or probably other) emulation by the
742 underlying device model, the host provides the guest with
743 timing infrastructure such as time of day, and system time
746 bool "Enable debug information for KVM Guests in debugfs"
747 depends on KVM_GUEST && DEBUG_FS
750 This option enables collection of various statistics for KVM guest.
751 Statistics are displayed in debugfs filesystem. Enabling this option
752 may incur significant overhead.
754 source "arch/x86/lguest/Kconfig"
756 config PARAVIRT_TIME_ACCOUNTING
757 bool "Paravirtual steal time accounting"
761 Select this option to enable fine granularity task steal time
762 accounting. Time spent executing other tasks in parallel with
763 the current vCPU is discounted from the vCPU power. To account for
764 that, there can be a small performance impact.
766 If in doubt, say N here.
768 config PARAVIRT_CLOCK
771 endif #HYPERVISOR_GUEST
776 source "arch/x86/Kconfig.cpu"
780 prompt "HPET Timer Support" if X86_32
782 Use the IA-PC HPET (High Precision Event Timer) to manage
783 time in preference to the PIT and RTC, if a HPET is
785 HPET is the next generation timer replacing legacy 8254s.
786 The HPET provides a stable time base on SMP
787 systems, unlike the TSC, but it is more expensive to access,
788 as it is off-chip. The interface used is documented
789 in the HPET spec, revision 1.
791 You can safely choose Y here. However, HPET will only be
792 activated if the platform and the BIOS support this feature.
793 Otherwise the 8254 will be used for timing services.
795 Choose N to continue using the legacy 8254 timer.
797 config HPET_EMULATE_RTC
799 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
802 def_bool y if X86_INTEL_MID
803 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
805 depends on X86_INTEL_MID && SFI
807 APB timer is the replacement for 8254, HPET on X86 MID platforms.
808 The APBT provides a stable time base on SMP
809 systems, unlike the TSC, but it is more expensive to access,
810 as it is off-chip. APB timers are always running regardless of CPU
811 C states, they are used as per CPU clockevent device when possible.
813 # Mark as expert because too many people got it wrong.
814 # The code disables itself when not needed.
817 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
818 bool "Enable DMI scanning" if EXPERT
820 Enabled scanning of DMI to identify machine quirks. Say Y
821 here unless you have verified that your setup is not
822 affected by entries in the DMI blacklist. Required by PNP
826 bool "Old AMD GART IOMMU support"
828 depends on X86_64 && PCI && AMD_NB
830 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
831 GART based hardware IOMMUs.
833 The GART supports full DMA access for devices with 32-bit access
834 limitations, on systems with more than 3 GB. This is usually needed
835 for USB, sound, many IDE/SATA chipsets and some other devices.
837 Newer systems typically have a modern AMD IOMMU, supported via
838 the CONFIG_AMD_IOMMU=y config option.
840 In normal configurations this driver is only active when needed:
841 there's more than 3 GB of memory and the system contains a
842 32-bit limited device.
847 bool "IBM Calgary IOMMU support"
849 depends on X86_64 && PCI
851 Support for hardware IOMMUs in IBM's xSeries x366 and x460
852 systems. Needed to run systems with more than 3GB of memory
853 properly with 32-bit PCI devices that do not support DAC
854 (Double Address Cycle). Calgary also supports bus level
855 isolation, where all DMAs pass through the IOMMU. This
856 prevents them from going anywhere except their intended
857 destination. This catches hard-to-find kernel bugs and
858 mis-behaving drivers and devices that do not use the DMA-API
859 properly to set up their DMA buffers. The IOMMU can be
860 turned off at boot time with the iommu=off parameter.
861 Normally the kernel will make the right choice by itself.
864 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
866 prompt "Should Calgary be enabled by default?"
867 depends on CALGARY_IOMMU
869 Should Calgary be enabled by default? if you choose 'y', Calgary
870 will be used (if it exists). If you choose 'n', Calgary will not be
871 used even if it exists. If you choose 'n' and would like to use
872 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
875 # need this always selected by IOMMU for the VIA workaround
879 Support for software bounce buffers used on x86-64 systems
880 which don't have a hardware IOMMU. Using this PCI devices
881 which can only access 32-bits of memory can be used on systems
882 with more than 3 GB of memory.
887 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
890 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
891 depends on X86_64 && SMP && DEBUG_KERNEL
892 select CPUMASK_OFFSTACK
894 Enable maximum number of CPUS and NUMA Nodes for this architecture.
898 int "Maximum number of CPUs" if SMP && !MAXSMP
899 range 2 8 if SMP && X86_32 && !X86_BIGSMP
900 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
901 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
903 default "8192" if MAXSMP
904 default "32" if SMP && X86_BIGSMP
905 default "8" if SMP && X86_32
908 This allows you to specify the maximum number of CPUs which this
909 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
910 supported value is 8192, otherwise the maximum value is 512. The
911 minimum value which makes sense is 2.
913 This is purely to save memory - each supported CPU adds
914 approximately eight kilobytes to the kernel image.
917 bool "SMT (Hyperthreading) scheduler support"
920 SMT scheduler support improves the CPU scheduler's decision making
921 when dealing with Intel Pentium 4 chips with HyperThreading at a
922 cost of slightly increased overhead in some places. If unsure say
927 prompt "Multi-core scheduler support"
930 Multi-core scheduler support improves the CPU scheduler's decision
931 making when dealing with multi-core CPU chips at a cost of slightly
932 increased overhead in some places. If unsure say N here.
934 source "kernel/Kconfig.preempt"
938 depends on !SMP && X86_LOCAL_APIC
941 bool "Local APIC support on uniprocessors" if !PCI_MSI
943 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
945 A local APIC (Advanced Programmable Interrupt Controller) is an
946 integrated interrupt controller in the CPU. If you have a single-CPU
947 system which has a processor with a local APIC, you can say Y here to
948 enable and use it. If you say Y here even though your machine doesn't
949 have a local APIC, then the kernel will still run with no slowdown at
950 all. The local APIC supports CPU-generated self-interrupts (timer,
951 performance counters), and the NMI watchdog which detects hard
955 bool "IO-APIC support on uniprocessors"
956 depends on X86_UP_APIC
958 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
959 SMP-capable replacement for PC-style interrupt controllers. Most
960 SMP systems and many recent uniprocessor systems have one.
962 If you have a single-CPU system with an IO-APIC, you can say Y here
963 to use it. If you say Y here even though your machine doesn't have
964 an IO-APIC, then the kernel will still run with no slowdown at all.
966 config X86_LOCAL_APIC
968 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
969 select IRQ_DOMAIN_HIERARCHY
970 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
974 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
976 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
977 bool "Reroute for broken boot IRQs"
978 depends on X86_IO_APIC
980 This option enables a workaround that fixes a source of
981 spurious interrupts. This is recommended when threaded
982 interrupt handling is used on systems where the generation of
983 superfluous "boot interrupts" cannot be disabled.
985 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
986 entry in the chipset's IO-APIC is masked (as, e.g. the RT
987 kernel does during interrupt handling). On chipsets where this
988 boot IRQ generation cannot be disabled, this workaround keeps
989 the original IRQ line masked so that only the equivalent "boot
990 IRQ" is delivered to the CPUs. The workaround also tells the
991 kernel to set up the IRQ handler on the boot IRQ line. In this
992 way only one interrupt is delivered to the kernel. Otherwise
993 the spurious second interrupt may cause the kernel to bring
994 down (vital) interrupt lines.
996 Only affects "broken" chipsets. Interrupt sharing may be
997 increased on these systems.
1000 bool "Machine Check / overheating reporting"
1001 select GENERIC_ALLOCATOR
1004 Machine Check support allows the processor to notify the
1005 kernel if it detects a problem (e.g. overheating, data corruption).
1006 The action the kernel takes depends on the severity of the problem,
1007 ranging from warning messages to halting the machine.
1009 config X86_MCE_INTEL
1011 prompt "Intel MCE features"
1012 depends on X86_MCE && X86_LOCAL_APIC
1014 Additional support for intel specific MCE features such as
1015 the thermal monitor.
1019 prompt "AMD MCE features"
1020 depends on X86_MCE && X86_LOCAL_APIC
1022 Additional support for AMD specific MCE features such as
1023 the DRAM Error Threshold.
1025 config X86_ANCIENT_MCE
1026 bool "Support for old Pentium 5 / WinChip machine checks"
1027 depends on X86_32 && X86_MCE
1029 Include support for machine check handling on old Pentium 5 or WinChip
1030 systems. These typically need to be enabled explicitly on the command
1033 config X86_MCE_THRESHOLD
1034 depends on X86_MCE_AMD || X86_MCE_INTEL
1037 config X86_MCE_INJECT
1039 tristate "Machine check injector support"
1041 Provide support for injecting machine checks for testing purposes.
1042 If you don't know what a machine check is and you don't do kernel
1043 QA it is safe to say n.
1045 config X86_THERMAL_VECTOR
1047 depends on X86_MCE_INTEL
1049 config X86_LEGACY_VM86
1050 bool "Legacy VM86 support"
1054 This option allows user programs to put the CPU into V8086
1055 mode, which is an 80286-era approximation of 16-bit real mode.
1057 Some very old versions of X and/or vbetool require this option
1058 for user mode setting. Similarly, DOSEMU will use it if
1059 available to accelerate real mode DOS programs. However, any
1060 recent version of DOSEMU, X, or vbetool should be fully
1061 functional even without kernel VM86 support, as they will all
1062 fall back to software emulation. Nevertheless, if you are using
1063 a 16-bit DOS program where 16-bit performance matters, vm86
1064 mode might be faster than emulation and you might want to
1067 Note that any app that works on a 64-bit kernel is unlikely to
1068 need this option, as 64-bit kernels don't, and can't, support
1069 V8086 mode. This option is also unrelated to 16-bit protected
1070 mode and is not needed to run most 16-bit programs under Wine.
1072 Enabling this option increases the complexity of the kernel
1073 and slows down exception handling a tiny bit.
1075 If unsure, say N here.
1079 default X86_LEGACY_VM86
1082 bool "Enable support for 16-bit segments" if EXPERT
1084 depends on MODIFY_LDT_SYSCALL
1086 This option is required by programs like Wine to run 16-bit
1087 protected mode legacy code on x86 processors. Disabling
1088 this option saves about 300 bytes on i386, or around 6K text
1089 plus 16K runtime memory on x86-64,
1093 depends on X86_16BIT && X86_32
1097 depends on X86_16BIT && X86_64
1099 config X86_VSYSCALL_EMULATION
1100 bool "Enable vsyscall emulation" if EXPERT
1104 This enables emulation of the legacy vsyscall page. Disabling
1105 it is roughly equivalent to booting with vsyscall=none, except
1106 that it will also disable the helpful warning if a program
1107 tries to use a vsyscall. With this option set to N, offending
1108 programs will just segfault, citing addresses of the form
1111 This option is required by many programs built before 2013, and
1112 care should be used even with newer programs if set to N.
1114 Disabling this option saves about 7K of kernel size and
1115 possibly 4K of additional runtime pagetable memory.
1118 tristate "Toshiba Laptop support"
1121 This adds a driver to safely access the System Management Mode of
1122 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1123 not work on models with a Phoenix BIOS. The System Management Mode
1124 is used to set the BIOS and power saving options on Toshiba portables.
1126 For information on utilities to make use of this driver see the
1127 Toshiba Linux utilities web site at:
1128 <http://www.buzzard.org.uk/toshiba/>.
1130 Say Y if you intend to run this kernel on a Toshiba portable.
1134 tristate "Dell i8k legacy laptop support"
1136 select SENSORS_DELL_SMM
1138 This option enables legacy /proc/i8k userspace interface in hwmon
1139 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1140 temperature and allows controlling fan speeds of Dell laptops via
1141 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1142 it reports also power and hotkey status. For fan speed control is
1143 needed userspace package i8kutils.
1145 Say Y if you intend to run this kernel on old Dell laptops or want to
1146 use userspace package i8kutils.
1149 config X86_REBOOTFIXUPS
1150 bool "Enable X86 board specific fixups for reboot"
1153 This enables chipset and/or board specific fixups to be done
1154 in order to get reboot to work correctly. This is only needed on
1155 some combinations of hardware and BIOS. The symptom, for which
1156 this config is intended, is when reboot ends with a stalled/hung
1159 Currently, the only fixup is for the Geode machines using
1160 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1162 Say Y if you want to enable the fixup. Currently, it's safe to
1163 enable this option even if you don't need it.
1167 bool "CPU microcode loading support"
1169 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1172 If you say Y here, you will be able to update the microcode on
1173 Intel and AMD processors. The Intel support is for the IA32 family,
1174 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1175 AMD support is for families 0x10 and later. You will obviously need
1176 the actual microcode binary data itself which is not shipped with
1179 The preferred method to load microcode from a detached initrd is described
1180 in Documentation/x86/early-microcode.txt. For that you need to enable
1181 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1182 initrd for microcode blobs.
1184 In addition, you can build-in the microcode into the kernel. For that you
1185 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1186 to the CONFIG_EXTRA_FIRMWARE config option.
1188 config MICROCODE_INTEL
1189 bool "Intel microcode loading support"
1190 depends on MICROCODE
1194 This options enables microcode patch loading support for Intel
1197 For the current Intel microcode data package go to
1198 <https://downloadcenter.intel.com> and search for
1199 'Linux Processor Microcode Data File'.
1201 config MICROCODE_AMD
1202 bool "AMD microcode loading support"
1203 depends on MICROCODE
1206 If you select this option, microcode patch loading support for AMD
1207 processors will be enabled.
1209 config MICROCODE_OLD_INTERFACE
1211 depends on MICROCODE
1214 tristate "/dev/cpu/*/msr - Model-specific register support"
1216 This device gives privileged processes access to the x86
1217 Model-Specific Registers (MSRs). It is a character device with
1218 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1219 MSR accesses are directed to a specific CPU on multi-processor
1223 tristate "/dev/cpu/*/cpuid - CPU information support"
1225 This device gives processes access to the x86 CPUID instruction to
1226 be executed on a specific processor. It is a character device
1227 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1231 prompt "High Memory Support"
1238 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1239 However, the address space of 32-bit x86 processors is only 4
1240 Gigabytes large. That means that, if you have a large amount of
1241 physical memory, not all of it can be "permanently mapped" by the
1242 kernel. The physical memory that's not permanently mapped is called
1245 If you are compiling a kernel which will never run on a machine with
1246 more than 1 Gigabyte total physical RAM, answer "off" here (default
1247 choice and suitable for most users). This will result in a "3GB/1GB"
1248 split: 3GB are mapped so that each process sees a 3GB virtual memory
1249 space and the remaining part of the 4GB virtual memory space is used
1250 by the kernel to permanently map as much physical memory as
1253 If the machine has between 1 and 4 Gigabytes physical RAM, then
1256 If more than 4 Gigabytes is used then answer "64GB" here. This
1257 selection turns Intel PAE (Physical Address Extension) mode on.
1258 PAE implements 3-level paging on IA32 processors. PAE is fully
1259 supported by Linux, PAE mode is implemented on all recent Intel
1260 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1261 then the kernel will not boot on CPUs that don't support PAE!
1263 The actual amount of total physical memory will either be
1264 auto detected or can be forced by using a kernel command line option
1265 such as "mem=256M". (Try "man bootparam" or see the documentation of
1266 your boot loader (lilo or loadlin) about how to pass options to the
1267 kernel at boot time.)
1269 If unsure, say "off".
1274 Select this if you have a 32-bit processor and between 1 and 4
1275 gigabytes of physical RAM.
1282 Select this if you have a 32-bit processor and more than 4
1283 gigabytes of physical RAM.
1288 prompt "Memory split" if EXPERT
1292 Select the desired split between kernel and user memory.
1294 If the address range available to the kernel is less than the
1295 physical memory installed, the remaining memory will be available
1296 as "high memory". Accessing high memory is a little more costly
1297 than low memory, as it needs to be mapped into the kernel first.
1298 Note that increasing the kernel address space limits the range
1299 available to user programs, making the address space there
1300 tighter. Selecting anything other than the default 3G/1G split
1301 will also likely make your kernel incompatible with binary-only
1304 If you are not absolutely sure what you are doing, leave this
1308 bool "3G/1G user/kernel split"
1309 config VMSPLIT_3G_OPT
1311 bool "3G/1G user/kernel split (for full 1G low memory)"
1313 bool "2G/2G user/kernel split"
1314 config VMSPLIT_2G_OPT
1316 bool "2G/2G user/kernel split (for full 2G low memory)"
1318 bool "1G/3G user/kernel split"
1323 default 0xB0000000 if VMSPLIT_3G_OPT
1324 default 0x80000000 if VMSPLIT_2G
1325 default 0x78000000 if VMSPLIT_2G_OPT
1326 default 0x40000000 if VMSPLIT_1G
1332 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1335 bool "PAE (Physical Address Extension) Support"
1336 depends on X86_32 && !HIGHMEM4G
1339 PAE is required for NX support, and furthermore enables
1340 larger swapspace support for non-overcommit purposes. It
1341 has the cost of more pagetable lookup overhead, and also
1342 consumes more pagetable space per process.
1344 config ARCH_PHYS_ADDR_T_64BIT
1346 depends on X86_64 || X86_PAE
1348 config ARCH_DMA_ADDR_T_64BIT
1350 depends on X86_64 || HIGHMEM64G
1352 config X86_DIRECT_GBPAGES
1354 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1356 Certain kernel features effectively disable kernel
1357 linear 1 GB mappings (even if the CPU otherwise
1358 supports them), so don't confuse the user by printing
1359 that we have them enabled.
1361 # Common NUMA Features
1363 bool "Numa Memory Allocation and Scheduler Support"
1365 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1366 default y if X86_BIGSMP
1368 Enable NUMA (Non Uniform Memory Access) support.
1370 The kernel will try to allocate memory used by a CPU on the
1371 local memory controller of the CPU and add some more
1372 NUMA awareness to the kernel.
1374 For 64-bit this is recommended if the system is Intel Core i7
1375 (or later), AMD Opteron, or EM64T NUMA.
1377 For 32-bit this is only needed if you boot a 32-bit
1378 kernel on a 64-bit NUMA platform.
1380 Otherwise, you should say N.
1384 prompt "Old style AMD Opteron NUMA detection"
1385 depends on X86_64 && NUMA && PCI
1387 Enable AMD NUMA node topology detection. You should say Y here if
1388 you have a multi processor AMD system. This uses an old method to
1389 read the NUMA configuration directly from the builtin Northbridge
1390 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1391 which also takes priority if both are compiled in.
1393 config X86_64_ACPI_NUMA
1395 prompt "ACPI NUMA detection"
1396 depends on X86_64 && NUMA && ACPI && PCI
1399 Enable ACPI SRAT based node topology detection.
1401 # Some NUMA nodes have memory ranges that span
1402 # other nodes. Even though a pfn is valid and
1403 # between a node's start and end pfns, it may not
1404 # reside on that node. See memmap_init_zone()
1406 config NODES_SPAN_OTHER_NODES
1408 depends on X86_64_ACPI_NUMA
1411 bool "NUMA emulation"
1414 Enable NUMA emulation. A flat machine will be split
1415 into virtual nodes when booted with "numa=fake=N", where N is the
1416 number of nodes. This is only useful for debugging.
1419 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1421 default "10" if MAXSMP
1422 default "6" if X86_64
1424 depends on NEED_MULTIPLE_NODES
1426 Specify the maximum number of NUMA Nodes available on the target
1427 system. Increases memory reserved to accommodate various tables.
1429 config ARCH_HAVE_MEMORY_PRESENT
1431 depends on X86_32 && DISCONTIGMEM
1433 config NEED_NODE_MEMMAP_SIZE
1435 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1437 config ARCH_FLATMEM_ENABLE
1439 depends on X86_32 && !NUMA
1441 config ARCH_DISCONTIGMEM_ENABLE
1443 depends on NUMA && X86_32
1445 config ARCH_DISCONTIGMEM_DEFAULT
1447 depends on NUMA && X86_32
1449 config ARCH_SPARSEMEM_ENABLE
1451 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1452 select SPARSEMEM_STATIC if X86_32
1453 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1455 config ARCH_SPARSEMEM_DEFAULT
1459 config ARCH_SELECT_MEMORY_MODEL
1461 depends on ARCH_SPARSEMEM_ENABLE
1463 config ARCH_MEMORY_PROBE
1464 bool "Enable sysfs memory/probe interface"
1465 depends on X86_64 && MEMORY_HOTPLUG
1467 This option enables a sysfs memory/probe interface for testing.
1468 See Documentation/memory-hotplug.txt for more information.
1469 If you are unsure how to answer this question, answer N.
1471 config ARCH_PROC_KCORE_TEXT
1473 depends on X86_64 && PROC_KCORE
1475 config ILLEGAL_POINTER_VALUE
1478 default 0xdead000000000000 if X86_64
1482 config X86_PMEM_LEGACY_DEVICE
1485 config X86_PMEM_LEGACY
1486 tristate "Support non-standard NVDIMMs and ADR protected memory"
1487 depends on PHYS_ADDR_T_64BIT
1489 select X86_PMEM_LEGACY_DEVICE
1492 Treat memory marked using the non-standard e820 type of 12 as used
1493 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1494 The kernel will offer these regions to the 'pmem' driver so
1495 they can be used for persistent storage.
1500 bool "Allocate 3rd-level pagetables from highmem"
1503 The VM uses one page table entry for each page of physical memory.
1504 For systems with a lot of RAM, this can be wasteful of precious
1505 low memory. Setting this option will put user-space page table
1506 entries in high memory.
1508 config X86_CHECK_BIOS_CORRUPTION
1509 bool "Check for low memory corruption"
1511 Periodically check for memory corruption in low memory, which
1512 is suspected to be caused by BIOS. Even when enabled in the
1513 configuration, it is disabled at runtime. Enable it by
1514 setting "memory_corruption_check=1" on the kernel command
1515 line. By default it scans the low 64k of memory every 60
1516 seconds; see the memory_corruption_check_size and
1517 memory_corruption_check_period parameters in
1518 Documentation/kernel-parameters.txt to adjust this.
1520 When enabled with the default parameters, this option has
1521 almost no overhead, as it reserves a relatively small amount
1522 of memory and scans it infrequently. It both detects corruption
1523 and prevents it from affecting the running system.
1525 It is, however, intended as a diagnostic tool; if repeatable
1526 BIOS-originated corruption always affects the same memory,
1527 you can use memmap= to prevent the kernel from using that
1530 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1531 bool "Set the default setting of memory_corruption_check"
1532 depends on X86_CHECK_BIOS_CORRUPTION
1535 Set whether the default state of memory_corruption_check is
1538 config X86_RESERVE_LOW
1539 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1543 Specify the amount of low memory to reserve for the BIOS.
1545 The first page contains BIOS data structures that the kernel
1546 must not use, so that page must always be reserved.
1548 By default we reserve the first 64K of physical RAM, as a
1549 number of BIOSes are known to corrupt that memory range
1550 during events such as suspend/resume or monitor cable
1551 insertion, so it must not be used by the kernel.
1553 You can set this to 4 if you are absolutely sure that you
1554 trust the BIOS to get all its memory reservations and usages
1555 right. If you know your BIOS have problems beyond the
1556 default 64K area, you can set this to 640 to avoid using the
1557 entire low memory range.
1559 If you have doubts about the BIOS (e.g. suspend/resume does
1560 not work or there's kernel crashes after certain hardware
1561 hotplug events) then you might want to enable
1562 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1563 typical corruption patterns.
1565 Leave this to the default value of 64 if you are unsure.
1567 config MATH_EMULATION
1569 depends on MODIFY_LDT_SYSCALL
1570 prompt "Math emulation" if X86_32
1572 Linux can emulate a math coprocessor (used for floating point
1573 operations) if you don't have one. 486DX and Pentium processors have
1574 a math coprocessor built in, 486SX and 386 do not, unless you added
1575 a 487DX or 387, respectively. (The messages during boot time can
1576 give you some hints here ["man dmesg"].) Everyone needs either a
1577 coprocessor or this emulation.
1579 If you don't have a math coprocessor, you need to say Y here; if you
1580 say Y here even though you have a coprocessor, the coprocessor will
1581 be used nevertheless. (This behavior can be changed with the kernel
1582 command line option "no387", which comes handy if your coprocessor
1583 is broken. Try "man bootparam" or see the documentation of your boot
1584 loader (lilo or loadlin) about how to pass options to the kernel at
1585 boot time.) This means that it is a good idea to say Y here if you
1586 intend to use this kernel on different machines.
1588 More information about the internals of the Linux math coprocessor
1589 emulation can be found in <file:arch/x86/math-emu/README>.
1591 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1592 kernel, it won't hurt.
1596 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1598 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1599 the Memory Type Range Registers (MTRRs) may be used to control
1600 processor access to memory ranges. This is most useful if you have
1601 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1602 allows bus write transfers to be combined into a larger transfer
1603 before bursting over the PCI/AGP bus. This can increase performance
1604 of image write operations 2.5 times or more. Saying Y here creates a
1605 /proc/mtrr file which may be used to manipulate your processor's
1606 MTRRs. Typically the X server should use this.
1608 This code has a reasonably generic interface so that similar
1609 control registers on other processors can be easily supported
1612 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1613 Registers (ARRs) which provide a similar functionality to MTRRs. For
1614 these, the ARRs are used to emulate the MTRRs.
1615 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1616 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1617 write-combining. All of these processors are supported by this code
1618 and it makes sense to say Y here if you have one of them.
1620 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1621 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1622 can lead to all sorts of problems, so it's good to say Y here.
1624 You can safely say Y even if your machine doesn't have MTRRs, you'll
1625 just add about 9 KB to your kernel.
1627 See <file:Documentation/x86/mtrr.txt> for more information.
1629 config MTRR_SANITIZER
1631 prompt "MTRR cleanup support"
1634 Convert MTRR layout from continuous to discrete, so X drivers can
1635 add writeback entries.
1637 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1638 The largest mtrr entry size for a continuous block can be set with
1643 config MTRR_SANITIZER_ENABLE_DEFAULT
1644 int "MTRR cleanup enable value (0-1)"
1647 depends on MTRR_SANITIZER
1649 Enable mtrr cleanup default value
1651 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1652 int "MTRR cleanup spare reg num (0-7)"
1655 depends on MTRR_SANITIZER
1657 mtrr cleanup spare entries default, it can be changed via
1658 mtrr_spare_reg_nr=N on the kernel command line.
1662 prompt "x86 PAT support" if EXPERT
1665 Use PAT attributes to setup page level cache control.
1667 PATs are the modern equivalents of MTRRs and are much more
1668 flexible than MTRRs.
1670 Say N here if you see bootup problems (boot crash, boot hang,
1671 spontaneous reboots) or a non-working video driver.
1675 config ARCH_USES_PG_UNCACHED
1681 prompt "x86 architectural random number generator" if EXPERT
1683 Enable the x86 architectural RDRAND instruction
1684 (Intel Bull Mountain technology) to generate random numbers.
1685 If supported, this is a high bandwidth, cryptographically
1686 secure hardware random number generator.
1690 prompt "Supervisor Mode Access Prevention" if EXPERT
1692 Supervisor Mode Access Prevention (SMAP) is a security
1693 feature in newer Intel processors. There is a small
1694 performance cost if this enabled and turned on; there is
1695 also a small increase in the kernel size if this is enabled.
1699 config X86_INTEL_MPX
1700 prompt "Intel MPX (Memory Protection Extensions)"
1702 depends on CPU_SUP_INTEL
1704 MPX provides hardware features that can be used in
1705 conjunction with compiler-instrumented code to check
1706 memory references. It is designed to detect buffer
1707 overflow or underflow bugs.
1709 This option enables running applications which are
1710 instrumented or otherwise use MPX. It does not use MPX
1711 itself inside the kernel or to protect the kernel
1712 against bad memory references.
1714 Enabling this option will make the kernel larger:
1715 ~8k of kernel text and 36 bytes of data on a 64-bit
1716 defconfig. It adds a long to the 'mm_struct' which
1717 will increase the kernel memory overhead of each
1718 process and adds some branches to paths used during
1719 exec() and munmap().
1721 For details, see Documentation/x86/intel_mpx.txt
1725 config X86_INTEL_MEMORY_PROTECTION_KEYS
1726 prompt "Intel Memory Protection Keys"
1728 # Note: only available in 64-bit mode
1729 depends on CPU_SUP_INTEL && X86_64
1731 Memory Protection Keys provides a mechanism for enforcing
1732 page-based protections, but without requiring modification of the
1733 page tables when an application changes protection domains.
1735 For details, see Documentation/x86/protection-keys.txt
1740 bool "EFI runtime service support"
1743 select EFI_RUNTIME_WRAPPERS
1745 This enables the kernel to use EFI runtime services that are
1746 available (such as the EFI variable services).
1748 This option is only useful on systems that have EFI firmware.
1749 In addition, you should use the latest ELILO loader available
1750 at <http://elilo.sourceforge.net> in order to take advantage
1751 of EFI runtime services. However, even with this option, the
1752 resultant kernel should continue to boot on existing non-EFI
1756 bool "EFI stub support"
1757 depends on EFI && !X86_USE_3DNOW
1760 This kernel feature allows a bzImage to be loaded directly
1761 by EFI firmware without the use of a bootloader.
1763 See Documentation/efi-stub.txt for more information.
1766 bool "EFI mixed-mode support"
1767 depends on EFI_STUB && X86_64
1769 Enabling this feature allows a 64-bit kernel to be booted
1770 on a 32-bit firmware, provided that your CPU supports 64-bit
1773 Note that it is not possible to boot a mixed-mode enabled
1774 kernel via the EFI boot stub - a bootloader that supports
1775 the EFI handover protocol must be used.
1781 prompt "Enable seccomp to safely compute untrusted bytecode"
1783 This kernel feature is useful for number crunching applications
1784 that may need to compute untrusted bytecode during their
1785 execution. By using pipes or other transports made available to
1786 the process as file descriptors supporting the read/write
1787 syscalls, it's possible to isolate those applications in
1788 their own address space using seccomp. Once seccomp is
1789 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1790 and the task is only allowed to execute a few safe syscalls
1791 defined by each seccomp mode.
1793 If unsure, say Y. Only embedded should say N here.
1795 source kernel/Kconfig.hz
1798 bool "kexec system call"
1801 kexec is a system call that implements the ability to shutdown your
1802 current kernel, and to start another kernel. It is like a reboot
1803 but it is independent of the system firmware. And like a reboot
1804 you can start any kernel with it, not just Linux.
1806 The name comes from the similarity to the exec system call.
1808 It is an ongoing process to be certain the hardware in a machine
1809 is properly shutdown, so do not be surprised if this code does not
1810 initially work for you. As of this writing the exact hardware
1811 interface is strongly in flux, so no good recommendation can be
1815 bool "kexec file based system call"
1820 depends on CRYPTO_SHA256=y
1822 This is new version of kexec system call. This system call is
1823 file based and takes file descriptors as system call argument
1824 for kernel and initramfs as opposed to list of segments as
1825 accepted by previous system call.
1827 config KEXEC_VERIFY_SIG
1828 bool "Verify kernel signature during kexec_file_load() syscall"
1829 depends on KEXEC_FILE
1831 This option makes kernel signature verification mandatory for
1832 the kexec_file_load() syscall.
1834 In addition to that option, you need to enable signature
1835 verification for the corresponding kernel image type being
1836 loaded in order for this to work.
1838 config KEXEC_BZIMAGE_VERIFY_SIG
1839 bool "Enable bzImage signature verification support"
1840 depends on KEXEC_VERIFY_SIG
1841 depends on SIGNED_PE_FILE_VERIFICATION
1842 select SYSTEM_TRUSTED_KEYRING
1844 Enable bzImage signature verification support.
1847 bool "kernel crash dumps"
1848 depends on X86_64 || (X86_32 && HIGHMEM)
1850 Generate crash dump after being started by kexec.
1851 This should be normally only set in special crash dump kernels
1852 which are loaded in the main kernel with kexec-tools into
1853 a specially reserved region and then later executed after
1854 a crash by kdump/kexec. The crash dump kernel must be compiled
1855 to a memory address not used by the main kernel or BIOS using
1856 PHYSICAL_START, or it must be built as a relocatable image
1857 (CONFIG_RELOCATABLE=y).
1858 For more details see Documentation/kdump/kdump.txt
1862 depends on KEXEC && HIBERNATION
1864 Jump between original kernel and kexeced kernel and invoke
1865 code in physical address mode via KEXEC
1867 config PHYSICAL_START
1868 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1871 This gives the physical address where the kernel is loaded.
1873 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1874 bzImage will decompress itself to above physical address and
1875 run from there. Otherwise, bzImage will run from the address where
1876 it has been loaded by the boot loader and will ignore above physical
1879 In normal kdump cases one does not have to set/change this option
1880 as now bzImage can be compiled as a completely relocatable image
1881 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1882 address. This option is mainly useful for the folks who don't want
1883 to use a bzImage for capturing the crash dump and want to use a
1884 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1885 to be specifically compiled to run from a specific memory area
1886 (normally a reserved region) and this option comes handy.
1888 So if you are using bzImage for capturing the crash dump,
1889 leave the value here unchanged to 0x1000000 and set
1890 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1891 for capturing the crash dump change this value to start of
1892 the reserved region. In other words, it can be set based on
1893 the "X" value as specified in the "crashkernel=YM@XM"
1894 command line boot parameter passed to the panic-ed
1895 kernel. Please take a look at Documentation/kdump/kdump.txt
1896 for more details about crash dumps.
1898 Usage of bzImage for capturing the crash dump is recommended as
1899 one does not have to build two kernels. Same kernel can be used
1900 as production kernel and capture kernel. Above option should have
1901 gone away after relocatable bzImage support is introduced. But it
1902 is present because there are users out there who continue to use
1903 vmlinux for dump capture. This option should go away down the
1906 Don't change this unless you know what you are doing.
1909 bool "Build a relocatable kernel"
1912 This builds a kernel image that retains relocation information
1913 so it can be loaded someplace besides the default 1MB.
1914 The relocations tend to make the kernel binary about 10% larger,
1915 but are discarded at runtime.
1917 One use is for the kexec on panic case where the recovery kernel
1918 must live at a different physical address than the primary
1921 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1922 it has been loaded at and the compile time physical address
1923 (CONFIG_PHYSICAL_START) is used as the minimum location.
1925 config RANDOMIZE_BASE
1926 bool "Randomize the address of the kernel image"
1927 depends on RELOCATABLE
1930 Randomizes the physical and virtual address at which the
1931 kernel image is decompressed, as a security feature that
1932 deters exploit attempts relying on knowledge of the location
1933 of kernel internals.
1935 Entropy is generated using the RDRAND instruction if it is
1936 supported. If RDTSC is supported, it is used as well. If
1937 neither RDRAND nor RDTSC are supported, then randomness is
1938 read from the i8254 timer.
1940 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1941 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1942 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1943 minimum of 2MiB, only 10 bits of entropy is theoretically
1944 possible. At best, due to page table layouts, 64-bit can use
1945 9 bits of entropy and 32-bit uses 8 bits.
1949 config RANDOMIZE_BASE_MAX_OFFSET
1950 hex "Maximum kASLR offset allowed" if EXPERT
1951 depends on RANDOMIZE_BASE
1952 range 0x0 0x20000000 if X86_32
1953 default "0x20000000" if X86_32
1954 range 0x0 0x40000000 if X86_64
1955 default "0x40000000" if X86_64
1957 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1958 memory is used to determine the maximal offset in bytes that will
1959 be applied to the kernel when kernel Address Space Layout
1960 Randomization (kASLR) is active. This must be a multiple of
1963 On 32-bit this is limited to 512MiB by page table layouts. The
1966 On 64-bit this is limited by how the kernel fixmap page table is
1967 positioned, so this cannot be larger than 1GiB currently. Without
1968 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1969 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1970 modules area will shrink to compensate, up to the current maximum
1971 1GiB to 1GiB split. The default is 1GiB.
1973 If unsure, leave at the default value.
1975 # Relocation on x86 needs some additional build support
1976 config X86_NEED_RELOCS
1978 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1980 config PHYSICAL_ALIGN
1981 hex "Alignment value to which kernel should be aligned"
1983 range 0x2000 0x1000000 if X86_32
1984 range 0x200000 0x1000000 if X86_64
1986 This value puts the alignment restrictions on physical address
1987 where kernel is loaded and run from. Kernel is compiled for an
1988 address which meets above alignment restriction.
1990 If bootloader loads the kernel at a non-aligned address and
1991 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1992 address aligned to above value and run from there.
1994 If bootloader loads the kernel at a non-aligned address and
1995 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1996 load address and decompress itself to the address it has been
1997 compiled for and run from there. The address for which kernel is
1998 compiled already meets above alignment restrictions. Hence the
1999 end result is that kernel runs from a physical address meeting
2000 above alignment restrictions.
2002 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2003 this value must be a multiple of 0x200000.
2005 Don't change this unless you know what you are doing.
2008 bool "Support for hot-pluggable CPUs"
2011 Say Y here to allow turning CPUs off and on. CPUs can be
2012 controlled through /sys/devices/system/cpu.
2013 ( Note: power management support will enable this option
2014 automatically on SMP systems. )
2015 Say N if you want to disable CPU hotplug.
2017 config BOOTPARAM_HOTPLUG_CPU0
2018 bool "Set default setting of cpu0_hotpluggable"
2020 depends on HOTPLUG_CPU
2022 Set whether default state of cpu0_hotpluggable is on or off.
2024 Say Y here to enable CPU0 hotplug by default. If this switch
2025 is turned on, there is no need to give cpu0_hotplug kernel
2026 parameter and the CPU0 hotplug feature is enabled by default.
2028 Please note: there are two known CPU0 dependencies if you want
2029 to enable the CPU0 hotplug feature either by this switch or by
2030 cpu0_hotplug kernel parameter.
2032 First, resume from hibernate or suspend always starts from CPU0.
2033 So hibernate and suspend are prevented if CPU0 is offline.
2035 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2036 offline if any interrupt can not migrate out of CPU0. There may
2037 be other CPU0 dependencies.
2039 Please make sure the dependencies are under your control before
2040 you enable this feature.
2042 Say N if you don't want to enable CPU0 hotplug feature by default.
2043 You still can enable the CPU0 hotplug feature at boot by kernel
2044 parameter cpu0_hotplug.
2046 config DEBUG_HOTPLUG_CPU0
2048 prompt "Debug CPU0 hotplug"
2049 depends on HOTPLUG_CPU
2051 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2052 soon as possible and boots up userspace with CPU0 offlined. User
2053 can online CPU0 back after boot time.
2055 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2056 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2057 compilation or giving cpu0_hotplug kernel parameter at boot.
2063 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2064 depends on X86_32 || IA32_EMULATION
2066 Certain buggy versions of glibc will crash if they are
2067 presented with a 32-bit vDSO that is not mapped at the address
2068 indicated in its segment table.
2070 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2071 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2072 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2073 the only released version with the bug, but OpenSUSE 9
2074 contains a buggy "glibc 2.3.2".
2076 The symptom of the bug is that everything crashes on startup, saying:
2077 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2079 Saying Y here changes the default value of the vdso32 boot
2080 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2081 This works around the glibc bug but hurts performance.
2083 If unsure, say N: if you are compiling your own kernel, you
2084 are unlikely to be using a buggy version of glibc.
2087 prompt "vsyscall table for legacy applications"
2089 default LEGACY_VSYSCALL_EMULATE
2091 Legacy user code that does not know how to find the vDSO expects
2092 to be able to issue three syscalls by calling fixed addresses in
2093 kernel space. Since this location is not randomized with ASLR,
2094 it can be used to assist security vulnerability exploitation.
2096 This setting can be changed at boot time via the kernel command
2097 line parameter vsyscall=[native|emulate|none].
2099 On a system with recent enough glibc (2.14 or newer) and no
2100 static binaries, you can say None without a performance penalty
2101 to improve security.
2103 If unsure, select "Emulate".
2105 config LEGACY_VSYSCALL_NATIVE
2108 Actual executable code is located in the fixed vsyscall
2109 address mapping, implementing time() efficiently. Since
2110 this makes the mapping executable, it can be used during
2111 security vulnerability exploitation (traditionally as
2112 ROP gadgets). This configuration is not recommended.
2114 config LEGACY_VSYSCALL_EMULATE
2117 The kernel traps and emulates calls into the fixed
2118 vsyscall address mapping. This makes the mapping
2119 non-executable, but it still contains known contents,
2120 which could be used in certain rare security vulnerability
2121 exploits. This configuration is recommended when userspace
2122 still uses the vsyscall area.
2124 config LEGACY_VSYSCALL_NONE
2127 There will be no vsyscall mapping at all. This will
2128 eliminate any risk of ASLR bypass due to the vsyscall
2129 fixed address mapping. Attempts to use the vsyscalls
2130 will be reported to dmesg, so that either old or
2131 malicious userspace programs can be identified.
2136 bool "Built-in kernel command line"
2138 Allow for specifying boot arguments to the kernel at
2139 build time. On some systems (e.g. embedded ones), it is
2140 necessary or convenient to provide some or all of the
2141 kernel boot arguments with the kernel itself (that is,
2142 to not rely on the boot loader to provide them.)
2144 To compile command line arguments into the kernel,
2145 set this option to 'Y', then fill in the
2146 boot arguments in CONFIG_CMDLINE.
2148 Systems with fully functional boot loaders (i.e. non-embedded)
2149 should leave this option set to 'N'.
2152 string "Built-in kernel command string"
2153 depends on CMDLINE_BOOL
2156 Enter arguments here that should be compiled into the kernel
2157 image and used at boot time. If the boot loader provides a
2158 command line at boot time, it is appended to this string to
2159 form the full kernel command line, when the system boots.
2161 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2162 change this behavior.
2164 In most cases, the command line (whether built-in or provided
2165 by the boot loader) should specify the device for the root
2168 config CMDLINE_OVERRIDE
2169 bool "Built-in command line overrides boot loader arguments"
2170 depends on CMDLINE_BOOL
2172 Set this option to 'Y' to have the kernel ignore the boot loader
2173 command line, and use ONLY the built-in command line.
2175 This is used to work around broken boot loaders. This should
2176 be set to 'N' under normal conditions.
2178 config MODIFY_LDT_SYSCALL
2179 bool "Enable the LDT (local descriptor table)" if EXPERT
2182 Linux can allow user programs to install a per-process x86
2183 Local Descriptor Table (LDT) using the modify_ldt(2) system
2184 call. This is required to run 16-bit or segmented code such as
2185 DOSEMU or some Wine programs. It is also used by some very old
2186 threading libraries.
2188 Enabling this feature adds a small amount of overhead to
2189 context switches and increases the low-level kernel attack
2190 surface. Disabling it removes the modify_ldt(2) system call.
2192 Saying 'N' here may make sense for embedded or server kernels.
2194 source "kernel/livepatch/Kconfig"
2198 config ARCH_ENABLE_MEMORY_HOTPLUG
2200 depends on X86_64 || (X86_32 && HIGHMEM)
2202 config ARCH_ENABLE_MEMORY_HOTREMOVE
2204 depends on MEMORY_HOTPLUG
2206 config USE_PERCPU_NUMA_NODE_ID
2210 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2212 depends on X86_64 || X86_PAE
2214 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2216 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2218 menu "Power management and ACPI options"
2220 config ARCH_HIBERNATION_HEADER
2222 depends on X86_64 && HIBERNATION
2224 source "kernel/power/Kconfig"
2226 source "drivers/acpi/Kconfig"
2228 source "drivers/sfi/Kconfig"
2235 tristate "APM (Advanced Power Management) BIOS support"
2236 depends on X86_32 && PM_SLEEP
2238 APM is a BIOS specification for saving power using several different
2239 techniques. This is mostly useful for battery powered laptops with
2240 APM compliant BIOSes. If you say Y here, the system time will be
2241 reset after a RESUME operation, the /proc/apm device will provide
2242 battery status information, and user-space programs will receive
2243 notification of APM "events" (e.g. battery status change).
2245 If you select "Y" here, you can disable actual use of the APM
2246 BIOS by passing the "apm=off" option to the kernel at boot time.
2248 Note that the APM support is almost completely disabled for
2249 machines with more than one CPU.
2251 In order to use APM, you will need supporting software. For location
2252 and more information, read <file:Documentation/power/apm-acpi.txt>
2253 and the Battery Powered Linux mini-HOWTO, available from
2254 <http://www.tldp.org/docs.html#howto>.
2256 This driver does not spin down disk drives (see the hdparm(8)
2257 manpage ("man 8 hdparm") for that), and it doesn't turn off
2258 VESA-compliant "green" monitors.
2260 This driver does not support the TI 4000M TravelMate and the ACER
2261 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2262 desktop machines also don't have compliant BIOSes, and this driver
2263 may cause those machines to panic during the boot phase.
2265 Generally, if you don't have a battery in your machine, there isn't
2266 much point in using this driver and you should say N. If you get
2267 random kernel OOPSes or reboots that don't seem to be related to
2268 anything, try disabling/enabling this option (or disabling/enabling
2271 Some other things you should try when experiencing seemingly random,
2274 1) make sure that you have enough swap space and that it is
2276 2) pass the "no-hlt" option to the kernel
2277 3) switch on floating point emulation in the kernel and pass
2278 the "no387" option to the kernel
2279 4) pass the "floppy=nodma" option to the kernel
2280 5) pass the "mem=4M" option to the kernel (thereby disabling
2281 all but the first 4 MB of RAM)
2282 6) make sure that the CPU is not over clocked.
2283 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2284 8) disable the cache from your BIOS settings
2285 9) install a fan for the video card or exchange video RAM
2286 10) install a better fan for the CPU
2287 11) exchange RAM chips
2288 12) exchange the motherboard.
2290 To compile this driver as a module, choose M here: the
2291 module will be called apm.
2295 config APM_IGNORE_USER_SUSPEND
2296 bool "Ignore USER SUSPEND"
2298 This option will ignore USER SUSPEND requests. On machines with a
2299 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2300 series notebooks, it is necessary to say Y because of a BIOS bug.
2302 config APM_DO_ENABLE
2303 bool "Enable PM at boot time"
2305 Enable APM features at boot time. From page 36 of the APM BIOS
2306 specification: "When disabled, the APM BIOS does not automatically
2307 power manage devices, enter the Standby State, enter the Suspend
2308 State, or take power saving steps in response to CPU Idle calls."
2309 This driver will make CPU Idle calls when Linux is idle (unless this
2310 feature is turned off -- see "Do CPU IDLE calls", below). This
2311 should always save battery power, but more complicated APM features
2312 will be dependent on your BIOS implementation. You may need to turn
2313 this option off if your computer hangs at boot time when using APM
2314 support, or if it beeps continuously instead of suspending. Turn
2315 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2316 T400CDT. This is off by default since most machines do fine without
2321 bool "Make CPU Idle calls when idle"
2323 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2324 On some machines, this can activate improved power savings, such as
2325 a slowed CPU clock rate, when the machine is idle. These idle calls
2326 are made after the idle loop has run for some length of time (e.g.,
2327 333 mS). On some machines, this will cause a hang at boot time or
2328 whenever the CPU becomes idle. (On machines with more than one CPU,
2329 this option does nothing.)
2331 config APM_DISPLAY_BLANK
2332 bool "Enable console blanking using APM"
2334 Enable console blanking using the APM. Some laptops can use this to
2335 turn off the LCD backlight when the screen blanker of the Linux
2336 virtual console blanks the screen. Note that this is only used by
2337 the virtual console screen blanker, and won't turn off the backlight
2338 when using the X Window system. This also doesn't have anything to
2339 do with your VESA-compliant power-saving monitor. Further, this
2340 option doesn't work for all laptops -- it might not turn off your
2341 backlight at all, or it might print a lot of errors to the console,
2342 especially if you are using gpm.
2344 config APM_ALLOW_INTS
2345 bool "Allow interrupts during APM BIOS calls"
2347 Normally we disable external interrupts while we are making calls to
2348 the APM BIOS as a measure to lessen the effects of a badly behaving
2349 BIOS implementation. The BIOS should reenable interrupts if it
2350 needs to. Unfortunately, some BIOSes do not -- especially those in
2351 many of the newer IBM Thinkpads. If you experience hangs when you
2352 suspend, try setting this to Y. Otherwise, say N.
2356 source "drivers/cpufreq/Kconfig"
2358 source "drivers/cpuidle/Kconfig"
2360 source "drivers/idle/Kconfig"
2365 menu "Bus options (PCI etc.)"
2371 Find out whether you have a PCI motherboard. PCI is the name of a
2372 bus system, i.e. the way the CPU talks to the other stuff inside
2373 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2374 VESA. If you have PCI, say Y, otherwise N.
2377 prompt "PCI access mode"
2378 depends on X86_32 && PCI
2381 On PCI systems, the BIOS can be used to detect the PCI devices and
2382 determine their configuration. However, some old PCI motherboards
2383 have BIOS bugs and may crash if this is done. Also, some embedded
2384 PCI-based systems don't have any BIOS at all. Linux can also try to
2385 detect the PCI hardware directly without using the BIOS.
2387 With this option, you can specify how Linux should detect the
2388 PCI devices. If you choose "BIOS", the BIOS will be used,
2389 if you choose "Direct", the BIOS won't be used, and if you
2390 choose "MMConfig", then PCI Express MMCONFIG will be used.
2391 If you choose "Any", the kernel will try MMCONFIG, then the
2392 direct access method and falls back to the BIOS if that doesn't
2393 work. If unsure, go with the default, which is "Any".
2398 config PCI_GOMMCONFIG
2415 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2417 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2420 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2424 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2428 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2432 depends on PCI && XEN
2440 bool "Support mmconfig PCI config space access"
2441 depends on X86_64 && PCI && ACPI
2443 config PCI_CNB20LE_QUIRK
2444 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2447 Read the PCI windows out of the CNB20LE host bridge. This allows
2448 PCI hotplug to work on systems with the CNB20LE chipset which do
2451 There's no public spec for this chipset, and this functionality
2452 is known to be incomplete.
2454 You should say N unless you know you need this.
2456 source "drivers/pci/Kconfig"
2458 # x86_64 have no ISA slots, but can have ISA-style DMA.
2460 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2463 Enables ISA-style DMA support for devices requiring such controllers.
2471 Find out whether you have ISA slots on your motherboard. ISA is the
2472 name of a bus system, i.e. the way the CPU talks to the other stuff
2473 inside your box. Other bus systems are PCI, EISA, MicroChannel
2474 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2475 newer boards don't support it. If you have ISA, say Y, otherwise N.
2481 The Extended Industry Standard Architecture (EISA) bus was
2482 developed as an open alternative to the IBM MicroChannel bus.
2484 The EISA bus provided some of the features of the IBM MicroChannel
2485 bus while maintaining backward compatibility with cards made for
2486 the older ISA bus. The EISA bus saw limited use between 1988 and
2487 1995 when it was made obsolete by the PCI bus.
2489 Say Y here if you are building a kernel for an EISA-based machine.
2493 source "drivers/eisa/Kconfig"
2496 tristate "NatSemi SCx200 support"
2498 This provides basic support for National Semiconductor's
2499 (now AMD's) Geode processors. The driver probes for the
2500 PCI-IDs of several on-chip devices, so its a good dependency
2501 for other scx200_* drivers.
2503 If compiled as a module, the driver is named scx200.
2505 config SCx200HR_TIMER
2506 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2510 This driver provides a clocksource built upon the on-chip
2511 27MHz high-resolution timer. Its also a workaround for
2512 NSC Geode SC-1100's buggy TSC, which loses time when the
2513 processor goes idle (as is done by the scheduler). The
2514 other workaround is idle=poll boot option.
2517 bool "One Laptop Per Child support"
2524 Add support for detecting the unique features of the OLPC
2528 bool "OLPC XO-1 Power Management"
2529 depends on OLPC && MFD_CS5535 && PM_SLEEP
2532 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2535 bool "OLPC XO-1 Real Time Clock"
2536 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2538 Add support for the XO-1 real time clock, which can be used as a
2539 programmable wakeup source.
2542 bool "OLPC XO-1 SCI extras"
2543 depends on OLPC && OLPC_XO1_PM
2549 Add support for SCI-based features of the OLPC XO-1 laptop:
2550 - EC-driven system wakeups
2554 - AC adapter status updates
2555 - Battery status updates
2557 config OLPC_XO15_SCI
2558 bool "OLPC XO-1.5 SCI extras"
2559 depends on OLPC && ACPI
2562 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2563 - EC-driven system wakeups
2564 - AC adapter status updates
2565 - Battery status updates
2568 bool "PCEngines ALIX System Support (LED setup)"
2571 This option enables system support for the PCEngines ALIX.
2572 At present this just sets up LEDs for GPIO control on
2573 ALIX2/3/6 boards. However, other system specific setup should
2576 Note: You must still enable the drivers for GPIO and LED support
2577 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2579 Note: You have to set alix.force=1 for boards with Award BIOS.
2582 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2585 This option enables system support for the Soekris Engineering net5501.
2588 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2592 This option enables system support for the Traverse Technologies GEOS.
2595 bool "Technologic Systems TS-5500 platform support"
2597 select CHECK_SIGNATURE
2601 This option enables system support for the Technologic Systems TS-5500.
2607 depends on CPU_SUP_AMD && PCI
2609 source "drivers/pcmcia/Kconfig"
2612 tristate "RapidIO support"
2616 If enabled this option will include drivers and the core
2617 infrastructure code to support RapidIO interconnect devices.
2619 source "drivers/rapidio/Kconfig"
2622 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2624 Firmwares often provide initial graphics framebuffers so the BIOS,
2625 bootloader or kernel can show basic video-output during boot for
2626 user-guidance and debugging. Historically, x86 used the VESA BIOS
2627 Extensions and EFI-framebuffers for this, which are mostly limited
2629 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2630 framebuffers so the new generic system-framebuffer drivers can be
2631 used on x86. If the framebuffer is not compatible with the generic
2632 modes, it is adverticed as fallback platform framebuffer so legacy
2633 drivers like efifb, vesafb and uvesafb can pick it up.
2634 If this option is not selected, all system framebuffers are always
2635 marked as fallback platform framebuffers as usual.
2637 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2638 not be able to pick up generic system framebuffers if this option
2639 is selected. You are highly encouraged to enable simplefb as
2640 replacement if you select this option. simplefb can correctly deal
2641 with generic system framebuffers. But you should still keep vesafb
2642 and others enabled as fallback if a system framebuffer is
2643 incompatible with simplefb.
2650 menu "Executable file formats / Emulations"
2652 source "fs/Kconfig.binfmt"
2654 config IA32_EMULATION
2655 bool "IA32 Emulation"
2658 select COMPAT_BINFMT_ELF
2659 select ARCH_WANT_OLD_COMPAT_IPC
2661 Include code to run legacy 32-bit programs under a
2662 64-bit kernel. You should likely turn this on, unless you're
2663 100% sure that you don't have any 32-bit programs left.
2666 tristate "IA32 a.out support"
2667 depends on IA32_EMULATION
2669 Support old a.out binaries in the 32bit emulation.
2672 bool "x32 ABI for 64-bit mode"
2675 Include code to run binaries for the x32 native 32-bit ABI
2676 for 64-bit processors. An x32 process gets access to the
2677 full 64-bit register file and wide data path while leaving
2678 pointers at 32 bits for smaller memory footprint.
2680 You will need a recent binutils (2.22 or later) with
2681 elf32_x86_64 support enabled to compile a kernel with this
2686 depends on IA32_EMULATION || X86_X32
2689 config COMPAT_FOR_U64_ALIGNMENT
2692 config SYSVIPC_COMPAT
2704 config HAVE_ATOMIC_IOMAP
2708 config X86_DEV_DMA_OPS
2710 depends on X86_64 || STA2X11
2712 config X86_DMA_REMAP
2722 tristate "Volume Management Device Driver"
2725 Adds support for the Intel Volume Management Device (VMD). VMD is a
2726 secondary PCI host bridge that allows PCI Express root ports,
2727 and devices attached to them, to be removed from the default
2728 PCI domain and placed within the VMD domain. This provides
2729 more bus resources than are otherwise possible with a
2730 single domain. If you know your system provides one of these and
2731 has devices attached to it, say Y; if you are not sure, say N.
2733 source "net/Kconfig"
2735 source "drivers/Kconfig"
2737 source "drivers/firmware/Kconfig"
2741 source "arch/x86/Kconfig.debug"
2743 source "security/Kconfig"
2745 source "crypto/Kconfig"
2747 source "arch/x86/kvm/Kconfig"
2749 source "lib/Kconfig"