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_HARDENED_USERCOPY
84 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
85 select HAVE_ARCH_JUMP_LABEL
86 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
88 select HAVE_ARCH_KMEMCHECK
89 select HAVE_ARCH_MMAP_RND_BITS if MMU
90 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
91 select HAVE_ARCH_SECCOMP_FILTER
92 select HAVE_ARCH_SOFT_DIRTY if X86_64
93 select HAVE_ARCH_TRACEHOOK
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
95 select HAVE_ARCH_WITHIN_STACK_FRAMES
96 select HAVE_EBPF_JIT if X86_64
97 select HAVE_CC_STACKPROTECTOR
98 select HAVE_CMPXCHG_DOUBLE
99 select HAVE_CMPXCHG_LOCAL
100 select HAVE_CONTEXT_TRACKING if X86_64
101 select HAVE_COPY_THREAD_TLS
102 select HAVE_C_RECORDMCOUNT
103 select HAVE_DEBUG_KMEMLEAK
104 select HAVE_DEBUG_STACKOVERFLOW
105 select HAVE_DMA_API_DEBUG
106 select HAVE_DMA_CONTIGUOUS
107 select HAVE_DYNAMIC_FTRACE
108 select HAVE_DYNAMIC_FTRACE_WITH_REGS
109 select HAVE_EFFICIENT_UNALIGNED_ACCESS
110 select HAVE_EXIT_THREAD
111 select HAVE_FENTRY if X86_64
112 select HAVE_FTRACE_MCOUNT_RECORD
113 select HAVE_FUNCTION_GRAPH_FP_TEST
114 select HAVE_FUNCTION_GRAPH_TRACER
115 select HAVE_FUNCTION_TRACER
116 select HAVE_GENERIC_DMA_COHERENT if X86_32
117 select HAVE_HW_BREAKPOINT
119 select HAVE_IOREMAP_PROT
120 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
121 select HAVE_IRQ_TIME_ACCOUNTING
122 select HAVE_KERNEL_BZIP2
123 select HAVE_KERNEL_GZIP
124 select HAVE_KERNEL_LZ4
125 select HAVE_KERNEL_LZMA
126 select HAVE_KERNEL_LZO
127 select HAVE_KERNEL_XZ
129 select HAVE_KPROBES_ON_FTRACE
130 select HAVE_KRETPROBES
132 select HAVE_LIVEPATCH if X86_64
134 select HAVE_MEMBLOCK_NODE_MAP
135 select HAVE_MIXED_BREAKPOINTS_REGS
138 select HAVE_OPTPROBES
139 select HAVE_PCSPKR_PLATFORM
140 select HAVE_PERF_EVENTS
141 select HAVE_PERF_EVENTS_NMI
142 select HAVE_PERF_REGS
143 select HAVE_PERF_USER_STACK_DUMP
144 select HAVE_REGS_AND_STACK_ACCESS_API
145 select HAVE_SYSCALL_TRACEPOINTS
146 select HAVE_UID16 if X86_32 || IA32_EMULATION
147 select HAVE_UNSTABLE_SCHED_CLOCK
148 select HAVE_USER_RETURN_NOTIFIER
149 select IRQ_FORCED_THREADING
150 select MODULES_USE_ELF_RELA if X86_64
151 select MODULES_USE_ELF_REL if X86_32
152 select OLD_SIGACTION if X86_32
153 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
158 select SYSCTL_EXCEPTION_TRACE
159 select USER_STACKTRACE_SUPPORT
161 select X86_DEV_DMA_OPS if X86_64
162 select X86_FEATURE_NAMES if PROC_FS
163 select HAVE_STACK_VALIDATION if X86_64
164 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
165 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
167 config INSTRUCTION_DECODER
169 depends on KPROBES || PERF_EVENTS || UPROBES
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 source "arch/x86/events/Kconfig"
1051 config X86_LEGACY_VM86
1052 bool "Legacy VM86 support"
1056 This option allows user programs to put the CPU into V8086
1057 mode, which is an 80286-era approximation of 16-bit real mode.
1059 Some very old versions of X and/or vbetool require this option
1060 for user mode setting. Similarly, DOSEMU will use it if
1061 available to accelerate real mode DOS programs. However, any
1062 recent version of DOSEMU, X, or vbetool should be fully
1063 functional even without kernel VM86 support, as they will all
1064 fall back to software emulation. Nevertheless, if you are using
1065 a 16-bit DOS program where 16-bit performance matters, vm86
1066 mode might be faster than emulation and you might want to
1069 Note that any app that works on a 64-bit kernel is unlikely to
1070 need this option, as 64-bit kernels don't, and can't, support
1071 V8086 mode. This option is also unrelated to 16-bit protected
1072 mode and is not needed to run most 16-bit programs under Wine.
1074 Enabling this option increases the complexity of the kernel
1075 and slows down exception handling a tiny bit.
1077 If unsure, say N here.
1081 default X86_LEGACY_VM86
1084 bool "Enable support for 16-bit segments" if EXPERT
1086 depends on MODIFY_LDT_SYSCALL
1088 This option is required by programs like Wine to run 16-bit
1089 protected mode legacy code on x86 processors. Disabling
1090 this option saves about 300 bytes on i386, or around 6K text
1091 plus 16K runtime memory on x86-64,
1095 depends on X86_16BIT && X86_32
1099 depends on X86_16BIT && X86_64
1101 config X86_VSYSCALL_EMULATION
1102 bool "Enable vsyscall emulation" if EXPERT
1106 This enables emulation of the legacy vsyscall page. Disabling
1107 it is roughly equivalent to booting with vsyscall=none, except
1108 that it will also disable the helpful warning if a program
1109 tries to use a vsyscall. With this option set to N, offending
1110 programs will just segfault, citing addresses of the form
1113 This option is required by many programs built before 2013, and
1114 care should be used even with newer programs if set to N.
1116 Disabling this option saves about 7K of kernel size and
1117 possibly 4K of additional runtime pagetable memory.
1120 tristate "Toshiba Laptop support"
1123 This adds a driver to safely access the System Management Mode of
1124 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1125 not work on models with a Phoenix BIOS. The System Management Mode
1126 is used to set the BIOS and power saving options on Toshiba portables.
1128 For information on utilities to make use of this driver see the
1129 Toshiba Linux utilities web site at:
1130 <http://www.buzzard.org.uk/toshiba/>.
1132 Say Y if you intend to run this kernel on a Toshiba portable.
1136 tristate "Dell i8k legacy laptop support"
1138 select SENSORS_DELL_SMM
1140 This option enables legacy /proc/i8k userspace interface in hwmon
1141 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1142 temperature and allows controlling fan speeds of Dell laptops via
1143 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1144 it reports also power and hotkey status. For fan speed control is
1145 needed userspace package i8kutils.
1147 Say Y if you intend to run this kernel on old Dell laptops or want to
1148 use userspace package i8kutils.
1151 config X86_REBOOTFIXUPS
1152 bool "Enable X86 board specific fixups for reboot"
1155 This enables chipset and/or board specific fixups to be done
1156 in order to get reboot to work correctly. This is only needed on
1157 some combinations of hardware and BIOS. The symptom, for which
1158 this config is intended, is when reboot ends with a stalled/hung
1161 Currently, the only fixup is for the Geode machines using
1162 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1164 Say Y if you want to enable the fixup. Currently, it's safe to
1165 enable this option even if you don't need it.
1169 bool "CPU microcode loading support"
1171 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1174 If you say Y here, you will be able to update the microcode on
1175 Intel and AMD processors. The Intel support is for the IA32 family,
1176 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1177 AMD support is for families 0x10 and later. You will obviously need
1178 the actual microcode binary data itself which is not shipped with
1181 The preferred method to load microcode from a detached initrd is described
1182 in Documentation/x86/early-microcode.txt. For that you need to enable
1183 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1184 initrd for microcode blobs.
1186 In addition, you can build-in the microcode into the kernel. For that you
1187 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1188 to the CONFIG_EXTRA_FIRMWARE config option.
1190 config MICROCODE_INTEL
1191 bool "Intel microcode loading support"
1192 depends on MICROCODE
1196 This options enables microcode patch loading support for Intel
1199 For the current Intel microcode data package go to
1200 <https://downloadcenter.intel.com> and search for
1201 'Linux Processor Microcode Data File'.
1203 config MICROCODE_AMD
1204 bool "AMD microcode loading support"
1205 depends on MICROCODE
1208 If you select this option, microcode patch loading support for AMD
1209 processors will be enabled.
1211 config MICROCODE_OLD_INTERFACE
1213 depends on MICROCODE
1216 tristate "/dev/cpu/*/msr - Model-specific register support"
1218 This device gives privileged processes access to the x86
1219 Model-Specific Registers (MSRs). It is a character device with
1220 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1221 MSR accesses are directed to a specific CPU on multi-processor
1225 tristate "/dev/cpu/*/cpuid - CPU information support"
1227 This device gives processes access to the x86 CPUID instruction to
1228 be executed on a specific processor. It is a character device
1229 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1233 prompt "High Memory Support"
1240 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1241 However, the address space of 32-bit x86 processors is only 4
1242 Gigabytes large. That means that, if you have a large amount of
1243 physical memory, not all of it can be "permanently mapped" by the
1244 kernel. The physical memory that's not permanently mapped is called
1247 If you are compiling a kernel which will never run on a machine with
1248 more than 1 Gigabyte total physical RAM, answer "off" here (default
1249 choice and suitable for most users). This will result in a "3GB/1GB"
1250 split: 3GB are mapped so that each process sees a 3GB virtual memory
1251 space and the remaining part of the 4GB virtual memory space is used
1252 by the kernel to permanently map as much physical memory as
1255 If the machine has between 1 and 4 Gigabytes physical RAM, then
1258 If more than 4 Gigabytes is used then answer "64GB" here. This
1259 selection turns Intel PAE (Physical Address Extension) mode on.
1260 PAE implements 3-level paging on IA32 processors. PAE is fully
1261 supported by Linux, PAE mode is implemented on all recent Intel
1262 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1263 then the kernel will not boot on CPUs that don't support PAE!
1265 The actual amount of total physical memory will either be
1266 auto detected or can be forced by using a kernel command line option
1267 such as "mem=256M". (Try "man bootparam" or see the documentation of
1268 your boot loader (lilo or loadlin) about how to pass options to the
1269 kernel at boot time.)
1271 If unsure, say "off".
1276 Select this if you have a 32-bit processor and between 1 and 4
1277 gigabytes of physical RAM.
1284 Select this if you have a 32-bit processor and more than 4
1285 gigabytes of physical RAM.
1290 prompt "Memory split" if EXPERT
1294 Select the desired split between kernel and user memory.
1296 If the address range available to the kernel is less than the
1297 physical memory installed, the remaining memory will be available
1298 as "high memory". Accessing high memory is a little more costly
1299 than low memory, as it needs to be mapped into the kernel first.
1300 Note that increasing the kernel address space limits the range
1301 available to user programs, making the address space there
1302 tighter. Selecting anything other than the default 3G/1G split
1303 will also likely make your kernel incompatible with binary-only
1306 If you are not absolutely sure what you are doing, leave this
1310 bool "3G/1G user/kernel split"
1311 config VMSPLIT_3G_OPT
1313 bool "3G/1G user/kernel split (for full 1G low memory)"
1315 bool "2G/2G user/kernel split"
1316 config VMSPLIT_2G_OPT
1318 bool "2G/2G user/kernel split (for full 2G low memory)"
1320 bool "1G/3G user/kernel split"
1325 default 0xB0000000 if VMSPLIT_3G_OPT
1326 default 0x80000000 if VMSPLIT_2G
1327 default 0x78000000 if VMSPLIT_2G_OPT
1328 default 0x40000000 if VMSPLIT_1G
1334 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1337 bool "PAE (Physical Address Extension) Support"
1338 depends on X86_32 && !HIGHMEM4G
1341 PAE is required for NX support, and furthermore enables
1342 larger swapspace support for non-overcommit purposes. It
1343 has the cost of more pagetable lookup overhead, and also
1344 consumes more pagetable space per process.
1346 config ARCH_PHYS_ADDR_T_64BIT
1348 depends on X86_64 || X86_PAE
1350 config ARCH_DMA_ADDR_T_64BIT
1352 depends on X86_64 || HIGHMEM64G
1354 config X86_DIRECT_GBPAGES
1356 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1358 Certain kernel features effectively disable kernel
1359 linear 1 GB mappings (even if the CPU otherwise
1360 supports them), so don't confuse the user by printing
1361 that we have them enabled.
1363 # Common NUMA Features
1365 bool "Numa Memory Allocation and Scheduler Support"
1367 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1368 default y if X86_BIGSMP
1370 Enable NUMA (Non Uniform Memory Access) support.
1372 The kernel will try to allocate memory used by a CPU on the
1373 local memory controller of the CPU and add some more
1374 NUMA awareness to the kernel.
1376 For 64-bit this is recommended if the system is Intel Core i7
1377 (or later), AMD Opteron, or EM64T NUMA.
1379 For 32-bit this is only needed if you boot a 32-bit
1380 kernel on a 64-bit NUMA platform.
1382 Otherwise, you should say N.
1386 prompt "Old style AMD Opteron NUMA detection"
1387 depends on X86_64 && NUMA && PCI
1389 Enable AMD NUMA node topology detection. You should say Y here if
1390 you have a multi processor AMD system. This uses an old method to
1391 read the NUMA configuration directly from the builtin Northbridge
1392 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1393 which also takes priority if both are compiled in.
1395 config X86_64_ACPI_NUMA
1397 prompt "ACPI NUMA detection"
1398 depends on X86_64 && NUMA && ACPI && PCI
1401 Enable ACPI SRAT based node topology detection.
1403 # Some NUMA nodes have memory ranges that span
1404 # other nodes. Even though a pfn is valid and
1405 # between a node's start and end pfns, it may not
1406 # reside on that node. See memmap_init_zone()
1408 config NODES_SPAN_OTHER_NODES
1410 depends on X86_64_ACPI_NUMA
1413 bool "NUMA emulation"
1416 Enable NUMA emulation. A flat machine will be split
1417 into virtual nodes when booted with "numa=fake=N", where N is the
1418 number of nodes. This is only useful for debugging.
1421 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1423 default "10" if MAXSMP
1424 default "6" if X86_64
1426 depends on NEED_MULTIPLE_NODES
1428 Specify the maximum number of NUMA Nodes available on the target
1429 system. Increases memory reserved to accommodate various tables.
1431 config ARCH_HAVE_MEMORY_PRESENT
1433 depends on X86_32 && DISCONTIGMEM
1435 config NEED_NODE_MEMMAP_SIZE
1437 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1439 config ARCH_FLATMEM_ENABLE
1441 depends on X86_32 && !NUMA
1443 config ARCH_DISCONTIGMEM_ENABLE
1445 depends on NUMA && X86_32
1447 config ARCH_DISCONTIGMEM_DEFAULT
1449 depends on NUMA && X86_32
1451 config ARCH_SPARSEMEM_ENABLE
1453 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1454 select SPARSEMEM_STATIC if X86_32
1455 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1457 config ARCH_SPARSEMEM_DEFAULT
1461 config ARCH_SELECT_MEMORY_MODEL
1463 depends on ARCH_SPARSEMEM_ENABLE
1465 config ARCH_MEMORY_PROBE
1466 bool "Enable sysfs memory/probe interface"
1467 depends on X86_64 && MEMORY_HOTPLUG
1469 This option enables a sysfs memory/probe interface for testing.
1470 See Documentation/memory-hotplug.txt for more information.
1471 If you are unsure how to answer this question, answer N.
1473 config ARCH_PROC_KCORE_TEXT
1475 depends on X86_64 && PROC_KCORE
1477 config ILLEGAL_POINTER_VALUE
1480 default 0xdead000000000000 if X86_64
1484 config X86_PMEM_LEGACY_DEVICE
1487 config X86_PMEM_LEGACY
1488 tristate "Support non-standard NVDIMMs and ADR protected memory"
1489 depends on PHYS_ADDR_T_64BIT
1491 select X86_PMEM_LEGACY_DEVICE
1494 Treat memory marked using the non-standard e820 type of 12 as used
1495 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1496 The kernel will offer these regions to the 'pmem' driver so
1497 they can be used for persistent storage.
1502 bool "Allocate 3rd-level pagetables from highmem"
1505 The VM uses one page table entry for each page of physical memory.
1506 For systems with a lot of RAM, this can be wasteful of precious
1507 low memory. Setting this option will put user-space page table
1508 entries in high memory.
1510 config X86_CHECK_BIOS_CORRUPTION
1511 bool "Check for low memory corruption"
1513 Periodically check for memory corruption in low memory, which
1514 is suspected to be caused by BIOS. Even when enabled in the
1515 configuration, it is disabled at runtime. Enable it by
1516 setting "memory_corruption_check=1" on the kernel command
1517 line. By default it scans the low 64k of memory every 60
1518 seconds; see the memory_corruption_check_size and
1519 memory_corruption_check_period parameters in
1520 Documentation/kernel-parameters.txt to adjust this.
1522 When enabled with the default parameters, this option has
1523 almost no overhead, as it reserves a relatively small amount
1524 of memory and scans it infrequently. It both detects corruption
1525 and prevents it from affecting the running system.
1527 It is, however, intended as a diagnostic tool; if repeatable
1528 BIOS-originated corruption always affects the same memory,
1529 you can use memmap= to prevent the kernel from using that
1532 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1533 bool "Set the default setting of memory_corruption_check"
1534 depends on X86_CHECK_BIOS_CORRUPTION
1537 Set whether the default state of memory_corruption_check is
1540 config X86_RESERVE_LOW
1541 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1545 Specify the amount of low memory to reserve for the BIOS.
1547 The first page contains BIOS data structures that the kernel
1548 must not use, so that page must always be reserved.
1550 By default we reserve the first 64K of physical RAM, as a
1551 number of BIOSes are known to corrupt that memory range
1552 during events such as suspend/resume or monitor cable
1553 insertion, so it must not be used by the kernel.
1555 You can set this to 4 if you are absolutely sure that you
1556 trust the BIOS to get all its memory reservations and usages
1557 right. If you know your BIOS have problems beyond the
1558 default 64K area, you can set this to 640 to avoid using the
1559 entire low memory range.
1561 If you have doubts about the BIOS (e.g. suspend/resume does
1562 not work or there's kernel crashes after certain hardware
1563 hotplug events) then you might want to enable
1564 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1565 typical corruption patterns.
1567 Leave this to the default value of 64 if you are unsure.
1569 config MATH_EMULATION
1571 depends on MODIFY_LDT_SYSCALL
1572 prompt "Math emulation" if X86_32
1574 Linux can emulate a math coprocessor (used for floating point
1575 operations) if you don't have one. 486DX and Pentium processors have
1576 a math coprocessor built in, 486SX and 386 do not, unless you added
1577 a 487DX or 387, respectively. (The messages during boot time can
1578 give you some hints here ["man dmesg"].) Everyone needs either a
1579 coprocessor or this emulation.
1581 If you don't have a math coprocessor, you need to say Y here; if you
1582 say Y here even though you have a coprocessor, the coprocessor will
1583 be used nevertheless. (This behavior can be changed with the kernel
1584 command line option "no387", which comes handy if your coprocessor
1585 is broken. Try "man bootparam" or see the documentation of your boot
1586 loader (lilo or loadlin) about how to pass options to the kernel at
1587 boot time.) This means that it is a good idea to say Y here if you
1588 intend to use this kernel on different machines.
1590 More information about the internals of the Linux math coprocessor
1591 emulation can be found in <file:arch/x86/math-emu/README>.
1593 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1594 kernel, it won't hurt.
1598 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1600 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1601 the Memory Type Range Registers (MTRRs) may be used to control
1602 processor access to memory ranges. This is most useful if you have
1603 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1604 allows bus write transfers to be combined into a larger transfer
1605 before bursting over the PCI/AGP bus. This can increase performance
1606 of image write operations 2.5 times or more. Saying Y here creates a
1607 /proc/mtrr file which may be used to manipulate your processor's
1608 MTRRs. Typically the X server should use this.
1610 This code has a reasonably generic interface so that similar
1611 control registers on other processors can be easily supported
1614 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1615 Registers (ARRs) which provide a similar functionality to MTRRs. For
1616 these, the ARRs are used to emulate the MTRRs.
1617 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1618 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1619 write-combining. All of these processors are supported by this code
1620 and it makes sense to say Y here if you have one of them.
1622 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1623 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1624 can lead to all sorts of problems, so it's good to say Y here.
1626 You can safely say Y even if your machine doesn't have MTRRs, you'll
1627 just add about 9 KB to your kernel.
1629 See <file:Documentation/x86/mtrr.txt> for more information.
1631 config MTRR_SANITIZER
1633 prompt "MTRR cleanup support"
1636 Convert MTRR layout from continuous to discrete, so X drivers can
1637 add writeback entries.
1639 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1640 The largest mtrr entry size for a continuous block can be set with
1645 config MTRR_SANITIZER_ENABLE_DEFAULT
1646 int "MTRR cleanup enable value (0-1)"
1649 depends on MTRR_SANITIZER
1651 Enable mtrr cleanup default value
1653 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1654 int "MTRR cleanup spare reg num (0-7)"
1657 depends on MTRR_SANITIZER
1659 mtrr cleanup spare entries default, it can be changed via
1660 mtrr_spare_reg_nr=N on the kernel command line.
1664 prompt "x86 PAT support" if EXPERT
1667 Use PAT attributes to setup page level cache control.
1669 PATs are the modern equivalents of MTRRs and are much more
1670 flexible than MTRRs.
1672 Say N here if you see bootup problems (boot crash, boot hang,
1673 spontaneous reboots) or a non-working video driver.
1677 config ARCH_USES_PG_UNCACHED
1683 prompt "x86 architectural random number generator" if EXPERT
1685 Enable the x86 architectural RDRAND instruction
1686 (Intel Bull Mountain technology) to generate random numbers.
1687 If supported, this is a high bandwidth, cryptographically
1688 secure hardware random number generator.
1692 prompt "Supervisor Mode Access Prevention" if EXPERT
1694 Supervisor Mode Access Prevention (SMAP) is a security
1695 feature in newer Intel processors. There is a small
1696 performance cost if this enabled and turned on; there is
1697 also a small increase in the kernel size if this is enabled.
1701 config X86_INTEL_MPX
1702 prompt "Intel MPX (Memory Protection Extensions)"
1704 depends on CPU_SUP_INTEL
1706 MPX provides hardware features that can be used in
1707 conjunction with compiler-instrumented code to check
1708 memory references. It is designed to detect buffer
1709 overflow or underflow bugs.
1711 This option enables running applications which are
1712 instrumented or otherwise use MPX. It does not use MPX
1713 itself inside the kernel or to protect the kernel
1714 against bad memory references.
1716 Enabling this option will make the kernel larger:
1717 ~8k of kernel text and 36 bytes of data on a 64-bit
1718 defconfig. It adds a long to the 'mm_struct' which
1719 will increase the kernel memory overhead of each
1720 process and adds some branches to paths used during
1721 exec() and munmap().
1723 For details, see Documentation/x86/intel_mpx.txt
1727 config X86_INTEL_MEMORY_PROTECTION_KEYS
1728 prompt "Intel Memory Protection Keys"
1730 # Note: only available in 64-bit mode
1731 depends on CPU_SUP_INTEL && X86_64
1733 Memory Protection Keys provides a mechanism for enforcing
1734 page-based protections, but without requiring modification of the
1735 page tables when an application changes protection domains.
1737 For details, see Documentation/x86/protection-keys.txt
1742 bool "EFI runtime service support"
1745 select EFI_RUNTIME_WRAPPERS
1747 This enables the kernel to use EFI runtime services that are
1748 available (such as the EFI variable services).
1750 This option is only useful on systems that have EFI firmware.
1751 In addition, you should use the latest ELILO loader available
1752 at <http://elilo.sourceforge.net> in order to take advantage
1753 of EFI runtime services. However, even with this option, the
1754 resultant kernel should continue to boot on existing non-EFI
1758 bool "EFI stub support"
1759 depends on EFI && !X86_USE_3DNOW
1762 This kernel feature allows a bzImage to be loaded directly
1763 by EFI firmware without the use of a bootloader.
1765 See Documentation/efi-stub.txt for more information.
1768 bool "EFI mixed-mode support"
1769 depends on EFI_STUB && X86_64
1771 Enabling this feature allows a 64-bit kernel to be booted
1772 on a 32-bit firmware, provided that your CPU supports 64-bit
1775 Note that it is not possible to boot a mixed-mode enabled
1776 kernel via the EFI boot stub - a bootloader that supports
1777 the EFI handover protocol must be used.
1783 prompt "Enable seccomp to safely compute untrusted bytecode"
1785 This kernel feature is useful for number crunching applications
1786 that may need to compute untrusted bytecode during their
1787 execution. By using pipes or other transports made available to
1788 the process as file descriptors supporting the read/write
1789 syscalls, it's possible to isolate those applications in
1790 their own address space using seccomp. Once seccomp is
1791 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1792 and the task is only allowed to execute a few safe syscalls
1793 defined by each seccomp mode.
1795 If unsure, say Y. Only embedded should say N here.
1797 source kernel/Kconfig.hz
1800 bool "kexec system call"
1803 kexec is a system call that implements the ability to shutdown your
1804 current kernel, and to start another kernel. It is like a reboot
1805 but it is independent of the system firmware. And like a reboot
1806 you can start any kernel with it, not just Linux.
1808 The name comes from the similarity to the exec system call.
1810 It is an ongoing process to be certain the hardware in a machine
1811 is properly shutdown, so do not be surprised if this code does not
1812 initially work for you. As of this writing the exact hardware
1813 interface is strongly in flux, so no good recommendation can be
1817 bool "kexec file based system call"
1822 depends on CRYPTO_SHA256=y
1824 This is new version of kexec system call. This system call is
1825 file based and takes file descriptors as system call argument
1826 for kernel and initramfs as opposed to list of segments as
1827 accepted by previous system call.
1829 config KEXEC_VERIFY_SIG
1830 bool "Verify kernel signature during kexec_file_load() syscall"
1831 depends on KEXEC_FILE
1833 This option makes kernel signature verification mandatory for
1834 the kexec_file_load() syscall.
1836 In addition to that option, you need to enable signature
1837 verification for the corresponding kernel image type being
1838 loaded in order for this to work.
1840 config KEXEC_BZIMAGE_VERIFY_SIG
1841 bool "Enable bzImage signature verification support"
1842 depends on KEXEC_VERIFY_SIG
1843 depends on SIGNED_PE_FILE_VERIFICATION
1844 select SYSTEM_TRUSTED_KEYRING
1846 Enable bzImage signature verification support.
1849 bool "kernel crash dumps"
1850 depends on X86_64 || (X86_32 && HIGHMEM)
1852 Generate crash dump after being started by kexec.
1853 This should be normally only set in special crash dump kernels
1854 which are loaded in the main kernel with kexec-tools into
1855 a specially reserved region and then later executed after
1856 a crash by kdump/kexec. The crash dump kernel must be compiled
1857 to a memory address not used by the main kernel or BIOS using
1858 PHYSICAL_START, or it must be built as a relocatable image
1859 (CONFIG_RELOCATABLE=y).
1860 For more details see Documentation/kdump/kdump.txt
1864 depends on KEXEC && HIBERNATION
1866 Jump between original kernel and kexeced kernel and invoke
1867 code in physical address mode via KEXEC
1869 config PHYSICAL_START
1870 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1873 This gives the physical address where the kernel is loaded.
1875 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1876 bzImage will decompress itself to above physical address and
1877 run from there. Otherwise, bzImage will run from the address where
1878 it has been loaded by the boot loader and will ignore above physical
1881 In normal kdump cases one does not have to set/change this option
1882 as now bzImage can be compiled as a completely relocatable image
1883 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1884 address. This option is mainly useful for the folks who don't want
1885 to use a bzImage for capturing the crash dump and want to use a
1886 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1887 to be specifically compiled to run from a specific memory area
1888 (normally a reserved region) and this option comes handy.
1890 So if you are using bzImage for capturing the crash dump,
1891 leave the value here unchanged to 0x1000000 and set
1892 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1893 for capturing the crash dump change this value to start of
1894 the reserved region. In other words, it can be set based on
1895 the "X" value as specified in the "crashkernel=YM@XM"
1896 command line boot parameter passed to the panic-ed
1897 kernel. Please take a look at Documentation/kdump/kdump.txt
1898 for more details about crash dumps.
1900 Usage of bzImage for capturing the crash dump is recommended as
1901 one does not have to build two kernels. Same kernel can be used
1902 as production kernel and capture kernel. Above option should have
1903 gone away after relocatable bzImage support is introduced. But it
1904 is present because there are users out there who continue to use
1905 vmlinux for dump capture. This option should go away down the
1908 Don't change this unless you know what you are doing.
1911 bool "Build a relocatable kernel"
1914 This builds a kernel image that retains relocation information
1915 so it can be loaded someplace besides the default 1MB.
1916 The relocations tend to make the kernel binary about 10% larger,
1917 but are discarded at runtime.
1919 One use is for the kexec on panic case where the recovery kernel
1920 must live at a different physical address than the primary
1923 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1924 it has been loaded at and the compile time physical address
1925 (CONFIG_PHYSICAL_START) is used as the minimum location.
1927 config RANDOMIZE_BASE
1928 bool "Randomize the address of the kernel image (KASLR)"
1929 depends on RELOCATABLE
1932 In support of Kernel Address Space Layout Randomization (KASLR),
1933 this randomizes the physical address at which the kernel image
1934 is decompressed and the virtual address where the kernel
1935 image is mapped, as a security feature that deters exploit
1936 attempts relying on knowledge of the location of kernel
1939 The kernel physical and virtual address can be randomized
1940 from 16MB up to 1GB on 64-bit and 512MB on 32-bit. (Note that
1941 using RANDOMIZE_BASE reduces the memory space available to
1942 kernel modules from 1.5GB to 1GB.)
1944 Entropy is generated using the RDRAND instruction if it is
1945 supported. If RDTSC is supported, its value is mixed into
1946 the entropy pool as well. If neither RDRAND nor RDTSC are
1947 supported, then entropy is read from the i8254 timer.
1949 Since the kernel is built using 2GB addressing, and
1950 PHYSICAL_ALIGN must be at a minimum of 2MB, only 10 bits of
1951 entropy is theoretically possible. Currently, with the
1952 default value for PHYSICAL_ALIGN and due to page table
1953 layouts, 64-bit uses 9 bits of entropy and 32-bit uses 8 bits.
1955 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1956 time. To enable it, boot with "kaslr" on the kernel command
1957 line (which will also disable hibernation).
1961 # Relocation on x86 needs some additional build support
1962 config X86_NEED_RELOCS
1964 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1966 config PHYSICAL_ALIGN
1967 hex "Alignment value to which kernel should be aligned"
1969 range 0x2000 0x1000000 if X86_32
1970 range 0x200000 0x1000000 if X86_64
1972 This value puts the alignment restrictions on physical address
1973 where kernel is loaded and run from. Kernel is compiled for an
1974 address which meets above alignment restriction.
1976 If bootloader loads the kernel at a non-aligned address and
1977 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1978 address aligned to above value and run from there.
1980 If bootloader loads the kernel at a non-aligned address and
1981 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1982 load address and decompress itself to the address it has been
1983 compiled for and run from there. The address for which kernel is
1984 compiled already meets above alignment restrictions. Hence the
1985 end result is that kernel runs from a physical address meeting
1986 above alignment restrictions.
1988 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1989 this value must be a multiple of 0x200000.
1991 Don't change this unless you know what you are doing.
1994 bool "Support for hot-pluggable CPUs"
1997 Say Y here to allow turning CPUs off and on. CPUs can be
1998 controlled through /sys/devices/system/cpu.
1999 ( Note: power management support will enable this option
2000 automatically on SMP systems. )
2001 Say N if you want to disable CPU hotplug.
2003 config BOOTPARAM_HOTPLUG_CPU0
2004 bool "Set default setting of cpu0_hotpluggable"
2006 depends on HOTPLUG_CPU
2008 Set whether default state of cpu0_hotpluggable is on or off.
2010 Say Y here to enable CPU0 hotplug by default. If this switch
2011 is turned on, there is no need to give cpu0_hotplug kernel
2012 parameter and the CPU0 hotplug feature is enabled by default.
2014 Please note: there are two known CPU0 dependencies if you want
2015 to enable the CPU0 hotplug feature either by this switch or by
2016 cpu0_hotplug kernel parameter.
2018 First, resume from hibernate or suspend always starts from CPU0.
2019 So hibernate and suspend are prevented if CPU0 is offline.
2021 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2022 offline if any interrupt can not migrate out of CPU0. There may
2023 be other CPU0 dependencies.
2025 Please make sure the dependencies are under your control before
2026 you enable this feature.
2028 Say N if you don't want to enable CPU0 hotplug feature by default.
2029 You still can enable the CPU0 hotplug feature at boot by kernel
2030 parameter cpu0_hotplug.
2032 config DEBUG_HOTPLUG_CPU0
2034 prompt "Debug CPU0 hotplug"
2035 depends on HOTPLUG_CPU
2037 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2038 soon as possible and boots up userspace with CPU0 offlined. User
2039 can online CPU0 back after boot time.
2041 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2042 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2043 compilation or giving cpu0_hotplug kernel parameter at boot.
2049 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2050 depends on X86_32 || IA32_EMULATION
2052 Certain buggy versions of glibc will crash if they are
2053 presented with a 32-bit vDSO that is not mapped at the address
2054 indicated in its segment table.
2056 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2057 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2058 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2059 the only released version with the bug, but OpenSUSE 9
2060 contains a buggy "glibc 2.3.2".
2062 The symptom of the bug is that everything crashes on startup, saying:
2063 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2065 Saying Y here changes the default value of the vdso32 boot
2066 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2067 This works around the glibc bug but hurts performance.
2069 If unsure, say N: if you are compiling your own kernel, you
2070 are unlikely to be using a buggy version of glibc.
2073 prompt "vsyscall table for legacy applications"
2075 default LEGACY_VSYSCALL_EMULATE
2077 Legacy user code that does not know how to find the vDSO expects
2078 to be able to issue three syscalls by calling fixed addresses in
2079 kernel space. Since this location is not randomized with ASLR,
2080 it can be used to assist security vulnerability exploitation.
2082 This setting can be changed at boot time via the kernel command
2083 line parameter vsyscall=[native|emulate|none].
2085 On a system with recent enough glibc (2.14 or newer) and no
2086 static binaries, you can say None without a performance penalty
2087 to improve security.
2089 If unsure, select "Emulate".
2091 config LEGACY_VSYSCALL_NATIVE
2094 Actual executable code is located in the fixed vsyscall
2095 address mapping, implementing time() efficiently. Since
2096 this makes the mapping executable, it can be used during
2097 security vulnerability exploitation (traditionally as
2098 ROP gadgets). This configuration is not recommended.
2100 config LEGACY_VSYSCALL_EMULATE
2103 The kernel traps and emulates calls into the fixed
2104 vsyscall address mapping. This makes the mapping
2105 non-executable, but it still contains known contents,
2106 which could be used in certain rare security vulnerability
2107 exploits. This configuration is recommended when userspace
2108 still uses the vsyscall area.
2110 config LEGACY_VSYSCALL_NONE
2113 There will be no vsyscall mapping at all. This will
2114 eliminate any risk of ASLR bypass due to the vsyscall
2115 fixed address mapping. Attempts to use the vsyscalls
2116 will be reported to dmesg, so that either old or
2117 malicious userspace programs can be identified.
2122 bool "Built-in kernel command line"
2124 Allow for specifying boot arguments to the kernel at
2125 build time. On some systems (e.g. embedded ones), it is
2126 necessary or convenient to provide some or all of the
2127 kernel boot arguments with the kernel itself (that is,
2128 to not rely on the boot loader to provide them.)
2130 To compile command line arguments into the kernel,
2131 set this option to 'Y', then fill in the
2132 boot arguments in CONFIG_CMDLINE.
2134 Systems with fully functional boot loaders (i.e. non-embedded)
2135 should leave this option set to 'N'.
2138 string "Built-in kernel command string"
2139 depends on CMDLINE_BOOL
2142 Enter arguments here that should be compiled into the kernel
2143 image and used at boot time. If the boot loader provides a
2144 command line at boot time, it is appended to this string to
2145 form the full kernel command line, when the system boots.
2147 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2148 change this behavior.
2150 In most cases, the command line (whether built-in or provided
2151 by the boot loader) should specify the device for the root
2154 config CMDLINE_OVERRIDE
2155 bool "Built-in command line overrides boot loader arguments"
2156 depends on CMDLINE_BOOL
2158 Set this option to 'Y' to have the kernel ignore the boot loader
2159 command line, and use ONLY the built-in command line.
2161 This is used to work around broken boot loaders. This should
2162 be set to 'N' under normal conditions.
2164 config MODIFY_LDT_SYSCALL
2165 bool "Enable the LDT (local descriptor table)" if EXPERT
2168 Linux can allow user programs to install a per-process x86
2169 Local Descriptor Table (LDT) using the modify_ldt(2) system
2170 call. This is required to run 16-bit or segmented code such as
2171 DOSEMU or some Wine programs. It is also used by some very old
2172 threading libraries.
2174 Enabling this feature adds a small amount of overhead to
2175 context switches and increases the low-level kernel attack
2176 surface. Disabling it removes the modify_ldt(2) system call.
2178 Saying 'N' here may make sense for embedded or server kernels.
2180 source "kernel/livepatch/Kconfig"
2184 config ARCH_ENABLE_MEMORY_HOTPLUG
2186 depends on X86_64 || (X86_32 && HIGHMEM)
2188 config ARCH_ENABLE_MEMORY_HOTREMOVE
2190 depends on MEMORY_HOTPLUG
2192 config USE_PERCPU_NUMA_NODE_ID
2196 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2198 depends on X86_64 || X86_PAE
2200 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2202 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2204 menu "Power management and ACPI options"
2206 config ARCH_HIBERNATION_HEADER
2208 depends on X86_64 && HIBERNATION
2210 source "kernel/power/Kconfig"
2212 source "drivers/acpi/Kconfig"
2214 source "drivers/sfi/Kconfig"
2221 tristate "APM (Advanced Power Management) BIOS support"
2222 depends on X86_32 && PM_SLEEP
2224 APM is a BIOS specification for saving power using several different
2225 techniques. This is mostly useful for battery powered laptops with
2226 APM compliant BIOSes. If you say Y here, the system time will be
2227 reset after a RESUME operation, the /proc/apm device will provide
2228 battery status information, and user-space programs will receive
2229 notification of APM "events" (e.g. battery status change).
2231 If you select "Y" here, you can disable actual use of the APM
2232 BIOS by passing the "apm=off" option to the kernel at boot time.
2234 Note that the APM support is almost completely disabled for
2235 machines with more than one CPU.
2237 In order to use APM, you will need supporting software. For location
2238 and more information, read <file:Documentation/power/apm-acpi.txt>
2239 and the Battery Powered Linux mini-HOWTO, available from
2240 <http://www.tldp.org/docs.html#howto>.
2242 This driver does not spin down disk drives (see the hdparm(8)
2243 manpage ("man 8 hdparm") for that), and it doesn't turn off
2244 VESA-compliant "green" monitors.
2246 This driver does not support the TI 4000M TravelMate and the ACER
2247 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2248 desktop machines also don't have compliant BIOSes, and this driver
2249 may cause those machines to panic during the boot phase.
2251 Generally, if you don't have a battery in your machine, there isn't
2252 much point in using this driver and you should say N. If you get
2253 random kernel OOPSes or reboots that don't seem to be related to
2254 anything, try disabling/enabling this option (or disabling/enabling
2257 Some other things you should try when experiencing seemingly random,
2260 1) make sure that you have enough swap space and that it is
2262 2) pass the "no-hlt" option to the kernel
2263 3) switch on floating point emulation in the kernel and pass
2264 the "no387" option to the kernel
2265 4) pass the "floppy=nodma" option to the kernel
2266 5) pass the "mem=4M" option to the kernel (thereby disabling
2267 all but the first 4 MB of RAM)
2268 6) make sure that the CPU is not over clocked.
2269 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2270 8) disable the cache from your BIOS settings
2271 9) install a fan for the video card or exchange video RAM
2272 10) install a better fan for the CPU
2273 11) exchange RAM chips
2274 12) exchange the motherboard.
2276 To compile this driver as a module, choose M here: the
2277 module will be called apm.
2281 config APM_IGNORE_USER_SUSPEND
2282 bool "Ignore USER SUSPEND"
2284 This option will ignore USER SUSPEND requests. On machines with a
2285 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2286 series notebooks, it is necessary to say Y because of a BIOS bug.
2288 config APM_DO_ENABLE
2289 bool "Enable PM at boot time"
2291 Enable APM features at boot time. From page 36 of the APM BIOS
2292 specification: "When disabled, the APM BIOS does not automatically
2293 power manage devices, enter the Standby State, enter the Suspend
2294 State, or take power saving steps in response to CPU Idle calls."
2295 This driver will make CPU Idle calls when Linux is idle (unless this
2296 feature is turned off -- see "Do CPU IDLE calls", below). This
2297 should always save battery power, but more complicated APM features
2298 will be dependent on your BIOS implementation. You may need to turn
2299 this option off if your computer hangs at boot time when using APM
2300 support, or if it beeps continuously instead of suspending. Turn
2301 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2302 T400CDT. This is off by default since most machines do fine without
2307 bool "Make CPU Idle calls when idle"
2309 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2310 On some machines, this can activate improved power savings, such as
2311 a slowed CPU clock rate, when the machine is idle. These idle calls
2312 are made after the idle loop has run for some length of time (e.g.,
2313 333 mS). On some machines, this will cause a hang at boot time or
2314 whenever the CPU becomes idle. (On machines with more than one CPU,
2315 this option does nothing.)
2317 config APM_DISPLAY_BLANK
2318 bool "Enable console blanking using APM"
2320 Enable console blanking using the APM. Some laptops can use this to
2321 turn off the LCD backlight when the screen blanker of the Linux
2322 virtual console blanks the screen. Note that this is only used by
2323 the virtual console screen blanker, and won't turn off the backlight
2324 when using the X Window system. This also doesn't have anything to
2325 do with your VESA-compliant power-saving monitor. Further, this
2326 option doesn't work for all laptops -- it might not turn off your
2327 backlight at all, or it might print a lot of errors to the console,
2328 especially if you are using gpm.
2330 config APM_ALLOW_INTS
2331 bool "Allow interrupts during APM BIOS calls"
2333 Normally we disable external interrupts while we are making calls to
2334 the APM BIOS as a measure to lessen the effects of a badly behaving
2335 BIOS implementation. The BIOS should reenable interrupts if it
2336 needs to. Unfortunately, some BIOSes do not -- especially those in
2337 many of the newer IBM Thinkpads. If you experience hangs when you
2338 suspend, try setting this to Y. Otherwise, say N.
2342 source "drivers/cpufreq/Kconfig"
2344 source "drivers/cpuidle/Kconfig"
2346 source "drivers/idle/Kconfig"
2351 menu "Bus options (PCI etc.)"
2357 Find out whether you have a PCI motherboard. PCI is the name of a
2358 bus system, i.e. the way the CPU talks to the other stuff inside
2359 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2360 VESA. If you have PCI, say Y, otherwise N.
2363 prompt "PCI access mode"
2364 depends on X86_32 && PCI
2367 On PCI systems, the BIOS can be used to detect the PCI devices and
2368 determine their configuration. However, some old PCI motherboards
2369 have BIOS bugs and may crash if this is done. Also, some embedded
2370 PCI-based systems don't have any BIOS at all. Linux can also try to
2371 detect the PCI hardware directly without using the BIOS.
2373 With this option, you can specify how Linux should detect the
2374 PCI devices. If you choose "BIOS", the BIOS will be used,
2375 if you choose "Direct", the BIOS won't be used, and if you
2376 choose "MMConfig", then PCI Express MMCONFIG will be used.
2377 If you choose "Any", the kernel will try MMCONFIG, then the
2378 direct access method and falls back to the BIOS if that doesn't
2379 work. If unsure, go with the default, which is "Any".
2384 config PCI_GOMMCONFIG
2401 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2403 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2406 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2410 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2414 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2418 depends on PCI && XEN
2426 bool "Support mmconfig PCI config space access"
2427 depends on X86_64 && PCI && ACPI
2429 config PCI_CNB20LE_QUIRK
2430 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2433 Read the PCI windows out of the CNB20LE host bridge. This allows
2434 PCI hotplug to work on systems with the CNB20LE chipset which do
2437 There's no public spec for this chipset, and this functionality
2438 is known to be incomplete.
2440 You should say N unless you know you need this.
2442 source "drivers/pci/Kconfig"
2445 bool "ISA-style bus support on modern systems" if EXPERT
2448 Enables ISA-style drivers on modern systems. This is necessary to
2449 support PC/104 devices on X86_64 platforms.
2453 # x86_64 have no ISA slots, but can have ISA-style DMA.
2455 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2458 Enables ISA-style DMA support for devices requiring such controllers.
2466 Find out whether you have ISA slots on your motherboard. ISA is the
2467 name of a bus system, i.e. the way the CPU talks to the other stuff
2468 inside your box. Other bus systems are PCI, EISA, MicroChannel
2469 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2470 newer boards don't support it. If you have ISA, say Y, otherwise N.
2476 The Extended Industry Standard Architecture (EISA) bus was
2477 developed as an open alternative to the IBM MicroChannel bus.
2479 The EISA bus provided some of the features of the IBM MicroChannel
2480 bus while maintaining backward compatibility with cards made for
2481 the older ISA bus. The EISA bus saw limited use between 1988 and
2482 1995 when it was made obsolete by the PCI bus.
2484 Say Y here if you are building a kernel for an EISA-based machine.
2488 source "drivers/eisa/Kconfig"
2491 tristate "NatSemi SCx200 support"
2493 This provides basic support for National Semiconductor's
2494 (now AMD's) Geode processors. The driver probes for the
2495 PCI-IDs of several on-chip devices, so its a good dependency
2496 for other scx200_* drivers.
2498 If compiled as a module, the driver is named scx200.
2500 config SCx200HR_TIMER
2501 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2505 This driver provides a clocksource built upon the on-chip
2506 27MHz high-resolution timer. Its also a workaround for
2507 NSC Geode SC-1100's buggy TSC, which loses time when the
2508 processor goes idle (as is done by the scheduler). The
2509 other workaround is idle=poll boot option.
2512 bool "One Laptop Per Child support"
2519 Add support for detecting the unique features of the OLPC
2523 bool "OLPC XO-1 Power Management"
2524 depends on OLPC && MFD_CS5535 && PM_SLEEP
2527 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2530 bool "OLPC XO-1 Real Time Clock"
2531 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2533 Add support for the XO-1 real time clock, which can be used as a
2534 programmable wakeup source.
2537 bool "OLPC XO-1 SCI extras"
2538 depends on OLPC && OLPC_XO1_PM
2544 Add support for SCI-based features of the OLPC XO-1 laptop:
2545 - EC-driven system wakeups
2549 - AC adapter status updates
2550 - Battery status updates
2552 config OLPC_XO15_SCI
2553 bool "OLPC XO-1.5 SCI extras"
2554 depends on OLPC && ACPI
2557 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2558 - EC-driven system wakeups
2559 - AC adapter status updates
2560 - Battery status updates
2563 bool "PCEngines ALIX System Support (LED setup)"
2566 This option enables system support for the PCEngines ALIX.
2567 At present this just sets up LEDs for GPIO control on
2568 ALIX2/3/6 boards. However, other system specific setup should
2571 Note: You must still enable the drivers for GPIO and LED support
2572 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2574 Note: You have to set alix.force=1 for boards with Award BIOS.
2577 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2580 This option enables system support for the Soekris Engineering net5501.
2583 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2587 This option enables system support for the Traverse Technologies GEOS.
2590 bool "Technologic Systems TS-5500 platform support"
2592 select CHECK_SIGNATURE
2596 This option enables system support for the Technologic Systems TS-5500.
2602 depends on CPU_SUP_AMD && PCI
2604 source "drivers/pcmcia/Kconfig"
2607 tristate "RapidIO support"
2611 If enabled this option will include drivers and the core
2612 infrastructure code to support RapidIO interconnect devices.
2614 source "drivers/rapidio/Kconfig"
2617 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2619 Firmwares often provide initial graphics framebuffers so the BIOS,
2620 bootloader or kernel can show basic video-output during boot for
2621 user-guidance and debugging. Historically, x86 used the VESA BIOS
2622 Extensions and EFI-framebuffers for this, which are mostly limited
2624 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2625 framebuffers so the new generic system-framebuffer drivers can be
2626 used on x86. If the framebuffer is not compatible with the generic
2627 modes, it is adverticed as fallback platform framebuffer so legacy
2628 drivers like efifb, vesafb and uvesafb can pick it up.
2629 If this option is not selected, all system framebuffers are always
2630 marked as fallback platform framebuffers as usual.
2632 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2633 not be able to pick up generic system framebuffers if this option
2634 is selected. You are highly encouraged to enable simplefb as
2635 replacement if you select this option. simplefb can correctly deal
2636 with generic system framebuffers. But you should still keep vesafb
2637 and others enabled as fallback if a system framebuffer is
2638 incompatible with simplefb.
2645 menu "Executable file formats / Emulations"
2647 source "fs/Kconfig.binfmt"
2649 config IA32_EMULATION
2650 bool "IA32 Emulation"
2653 select COMPAT_BINFMT_ELF
2654 select ARCH_WANT_OLD_COMPAT_IPC
2656 Include code to run legacy 32-bit programs under a
2657 64-bit kernel. You should likely turn this on, unless you're
2658 100% sure that you don't have any 32-bit programs left.
2661 tristate "IA32 a.out support"
2662 depends on IA32_EMULATION
2664 Support old a.out binaries in the 32bit emulation.
2667 bool "x32 ABI for 64-bit mode"
2670 Include code to run binaries for the x32 native 32-bit ABI
2671 for 64-bit processors. An x32 process gets access to the
2672 full 64-bit register file and wide data path while leaving
2673 pointers at 32 bits for smaller memory footprint.
2675 You will need a recent binutils (2.22 or later) with
2676 elf32_x86_64 support enabled to compile a kernel with this
2681 depends on IA32_EMULATION || X86_X32
2684 config COMPAT_FOR_U64_ALIGNMENT
2687 config SYSVIPC_COMPAT
2699 config HAVE_ATOMIC_IOMAP
2703 config X86_DEV_DMA_OPS
2705 depends on X86_64 || STA2X11
2707 config X86_DMA_REMAP
2717 tristate "Volume Management Device Driver"
2720 Adds support for the Intel Volume Management Device (VMD). VMD is a
2721 secondary PCI host bridge that allows PCI Express root ports,
2722 and devices attached to them, to be removed from the default
2723 PCI domain and placed within the VMD domain. This provides
2724 more bus resources than are otherwise possible with a
2725 single domain. If you know your system provides one of these and
2726 has devices attached to it, say Y; if you are not sure, say N.
2728 source "net/Kconfig"
2730 source "drivers/Kconfig"
2732 source "drivers/firmware/Kconfig"
2736 source "arch/x86/Kconfig.debug"
2738 source "security/Kconfig"
2740 source "crypto/Kconfig"
2742 source "arch/x86/kvm/Kconfig"
2744 source "lib/Kconfig"
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