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
135 select HAVE_OPTPROBES
136 select HAVE_PCSPKR_PLATFORM
137 select HAVE_PERF_EVENTS
138 select HAVE_PERF_EVENTS_NMI
139 select HAVE_PERF_REGS
140 select HAVE_PERF_USER_STACK_DUMP
141 select HAVE_REGS_AND_STACK_ACCESS_API
142 select HAVE_SYSCALL_TRACEPOINTS
143 select HAVE_UID16 if X86_32 || IA32_EMULATION
144 select HAVE_UNSTABLE_SCHED_CLOCK
145 select HAVE_USER_RETURN_NOTIFIER
146 select IRQ_FORCED_THREADING
147 select MODULES_USE_ELF_RELA if X86_64
148 select MODULES_USE_ELF_REL if X86_32
149 select OLD_SIGACTION if X86_32
150 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
155 select SYSCTL_EXCEPTION_TRACE
156 select USER_STACKTRACE_SUPPORT
158 select X86_DEV_DMA_OPS if X86_64
159 select X86_FEATURE_NAMES if PROC_FS
160 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
161 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
162 select HAVE_STACK_VALIDATION if X86_64
164 config INSTRUCTION_DECODER
166 depends on KPROBES || PERF_EVENTS || UPROBES
168 config PERF_EVENTS_INTEL_UNCORE
170 depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
174 default "elf32-i386" if X86_32
175 default "elf64-x86-64" if X86_64
177 config ARCH_DEFCONFIG
179 default "arch/x86/configs/i386_defconfig" if X86_32
180 default "arch/x86/configs/x86_64_defconfig" if X86_64
182 config LOCKDEP_SUPPORT
185 config STACKTRACE_SUPPORT
191 config ARCH_MMAP_RND_BITS_MIN
195 config ARCH_MMAP_RND_BITS_MAX
199 config ARCH_MMAP_RND_COMPAT_BITS_MIN
202 config ARCH_MMAP_RND_COMPAT_BITS_MAX
208 config NEED_DMA_MAP_STATE
210 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
212 config NEED_SG_DMA_LENGTH
215 config GENERIC_ISA_DMA
217 depends on ISA_DMA_API
222 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
224 config GENERIC_BUG_RELATIVE_POINTERS
227 config GENERIC_HWEIGHT
230 config ARCH_MAY_HAVE_PC_FDC
232 depends on ISA_DMA_API
234 config RWSEM_XCHGADD_ALGORITHM
237 config GENERIC_CALIBRATE_DELAY
240 config ARCH_HAS_CPU_RELAX
243 config ARCH_HAS_CACHE_LINE_SIZE
246 config HAVE_SETUP_PER_CPU_AREA
249 config NEED_PER_CPU_EMBED_FIRST_CHUNK
252 config NEED_PER_CPU_PAGE_FIRST_CHUNK
255 config ARCH_HIBERNATION_POSSIBLE
258 config ARCH_SUSPEND_POSSIBLE
261 config ARCH_WANT_HUGE_PMD_SHARE
264 config ARCH_WANT_GENERAL_HUGETLB
273 config ARCH_SUPPORTS_OPTIMIZED_INLINING
276 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
279 config KASAN_SHADOW_OFFSET
282 default 0xdffffc0000000000
284 config HAVE_INTEL_TXT
286 depends on INTEL_IOMMU && ACPI
290 depends on X86_32 && SMP
294 depends on X86_64 && SMP
296 config X86_32_LAZY_GS
298 depends on X86_32 && !CC_STACKPROTECTOR
300 config ARCH_HWEIGHT_CFLAGS
302 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
303 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
305 config ARCH_SUPPORTS_UPROBES
308 config FIX_EARLYCON_MEM
314 config PGTABLE_LEVELS
320 source "init/Kconfig"
321 source "kernel/Kconfig.freezer"
323 menu "Processor type and features"
326 bool "DMA memory allocation support" if EXPERT
329 DMA memory allocation support allows devices with less than 32-bit
330 addressing to allocate within the first 16MB of address space.
331 Disable if no such devices will be used.
336 bool "Symmetric multi-processing support"
338 This enables support for systems with more than one CPU. If you have
339 a system with only one CPU, say N. If you have a system with more
342 If you say N here, the kernel will run on uni- and multiprocessor
343 machines, but will use only one CPU of a multiprocessor machine. If
344 you say Y here, the kernel will run on many, but not all,
345 uniprocessor machines. On a uniprocessor machine, the kernel
346 will run faster if you say N here.
348 Note that if you say Y here and choose architecture "586" or
349 "Pentium" under "Processor family", the kernel will not work on 486
350 architectures. Similarly, multiprocessor kernels for the "PPro"
351 architecture may not work on all Pentium based boards.
353 People using multiprocessor machines who say Y here should also say
354 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
355 Management" code will be disabled if you say Y here.
357 See also <file:Documentation/x86/i386/IO-APIC.txt>,
358 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
359 <http://www.tldp.org/docs.html#howto>.
361 If you don't know what to do here, say N.
363 config X86_FEATURE_NAMES
364 bool "Processor feature human-readable names" if EMBEDDED
367 This option compiles in a table of x86 feature bits and corresponding
368 names. This is required to support /proc/cpuinfo and a few kernel
369 messages. You can disable this to save space, at the expense of
370 making those few kernel messages show numeric feature bits instead.
374 config X86_FAST_FEATURE_TESTS
375 bool "Fast CPU feature tests" if EMBEDDED
378 Some fast-paths in the kernel depend on the capabilities of the CPU.
379 Say Y here for the kernel to patch in the appropriate code at runtime
380 based on the capabilities of the CPU. The infrastructure for patching
381 code at runtime takes up some additional space; space-constrained
382 embedded systems may wish to say N here to produce smaller, slightly
386 bool "Support x2apic"
387 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
389 This enables x2apic support on CPUs that have this feature.
391 This allows 32-bit apic IDs (so it can support very large systems),
392 and accesses the local apic via MSRs not via mmio.
394 If you don't know what to do here, say N.
397 bool "Enable MPS table" if ACPI || SFI
399 depends on X86_LOCAL_APIC
401 For old smp systems that do not have proper acpi support. Newer systems
402 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
405 bool "Support for big SMP systems with more than 8 CPUs"
406 depends on X86_32 && SMP
408 This option is needed for the systems that have more than 8 CPUs
412 depends on X86_GOLDFISH
415 config X86_EXTENDED_PLATFORM
416 bool "Support for extended (non-PC) x86 platforms"
419 If you disable this option then the kernel will only support
420 standard PC platforms. (which covers the vast majority of
423 If you enable this option then you'll be able to select support
424 for the following (non-PC) 32 bit x86 platforms:
425 Goldfish (Android emulator)
428 SGI 320/540 (Visual Workstation)
429 STA2X11-based (e.g. Northville)
430 Moorestown MID devices
432 If you have one of these systems, or if you want to build a
433 generic distribution kernel, say Y here - otherwise say N.
437 config X86_EXTENDED_PLATFORM
438 bool "Support for extended (non-PC) x86 platforms"
441 If you disable this option then the kernel will only support
442 standard PC platforms. (which covers the vast majority of
445 If you enable this option then you'll be able to select support
446 for the following (non-PC) 64 bit x86 platforms:
451 If you have one of these systems, or if you want to build a
452 generic distribution kernel, say Y here - otherwise say N.
454 # This is an alphabetically sorted list of 64 bit extended platforms
455 # Please maintain the alphabetic order if and when there are additions
457 bool "Numascale NumaChip"
459 depends on X86_EXTENDED_PLATFORM
462 depends on X86_X2APIC
463 depends on PCI_MMCONFIG
465 Adds support for Numascale NumaChip large-SMP systems. Needed to
466 enable more than ~168 cores.
467 If you don't have one of these, you should say N here.
471 select HYPERVISOR_GUEST
473 depends on X86_64 && PCI
474 depends on X86_EXTENDED_PLATFORM
477 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
478 supposed to run on these EM64T-based machines. Only choose this option
479 if you have one of these machines.
482 bool "SGI Ultraviolet"
484 depends on X86_EXTENDED_PLATFORM
487 depends on X86_X2APIC
490 This option is needed in order to support SGI Ultraviolet systems.
491 If you don't have one of these, you should say N here.
493 # Following is an alphabetically sorted list of 32 bit extended platforms
494 # Please maintain the alphabetic order if and when there are additions
497 bool "Goldfish (Virtual Platform)"
498 depends on X86_EXTENDED_PLATFORM
500 Enable support for the Goldfish virtual platform used primarily
501 for Android development. Unless you are building for the Android
502 Goldfish emulator say N here.
505 bool "CE4100 TV platform"
507 depends on PCI_GODIRECT
508 depends on X86_IO_APIC
510 depends on X86_EXTENDED_PLATFORM
511 select X86_REBOOTFIXUPS
513 select OF_EARLY_FLATTREE
515 Select for the Intel CE media processor (CE4100) SOC.
516 This option compiles in support for the CE4100 SOC for settop
517 boxes and media devices.
520 bool "Intel MID platform support"
521 depends on X86_EXTENDED_PLATFORM
522 depends on X86_PLATFORM_DEVICES
524 depends on X86_64 || (PCI_GOANY && X86_32)
525 depends on X86_IO_APIC
531 select MFD_INTEL_MSIC
533 Select to build a kernel capable of supporting Intel MID (Mobile
534 Internet Device) platform systems which do not have the PCI legacy
535 interfaces. If you are building for a PC class system say N here.
537 Intel MID platforms are based on an Intel processor and chipset which
538 consume less power than most of the x86 derivatives.
540 config X86_INTEL_QUARK
541 bool "Intel Quark platform support"
543 depends on X86_EXTENDED_PLATFORM
544 depends on X86_PLATFORM_DEVICES
548 depends on X86_IO_APIC
553 Select to include support for Quark X1000 SoC.
554 Say Y here if you have a Quark based system such as the Arduino
555 compatible Intel Galileo.
557 config X86_INTEL_LPSS
558 bool "Intel Low Power Subsystem Support"
559 depends on X86 && ACPI
564 Select to build support for Intel Low Power Subsystem such as
565 found on Intel Lynxpoint PCH. Selecting this option enables
566 things like clock tree (common clock framework) and pincontrol
567 which are needed by the LPSS peripheral drivers.
569 config X86_AMD_PLATFORM_DEVICE
570 bool "AMD ACPI2Platform devices support"
575 Select to interpret AMD specific ACPI device to platform device
576 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
577 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
578 implemented under PINCTRL subsystem.
581 tristate "Intel SoC IOSF Sideband support for SoC platforms"
584 This option enables sideband register access support for Intel SoC
585 platforms. On these platforms the IOSF sideband is used in lieu of
586 MSR's for some register accesses, mostly but not limited to thermal
587 and power. Drivers may query the availability of this device to
588 determine if they need the sideband in order to work on these
589 platforms. The sideband is available on the following SoC products.
590 This list is not meant to be exclusive.
595 You should say Y if you are running a kernel on one of these SoC's.
597 config IOSF_MBI_DEBUG
598 bool "Enable IOSF sideband access through debugfs"
599 depends on IOSF_MBI && DEBUG_FS
601 Select this option to expose the IOSF sideband access registers (MCR,
602 MDR, MCRX) through debugfs to write and read register information from
603 different units on the SoC. This is most useful for obtaining device
604 state information for debug and analysis. As this is a general access
605 mechanism, users of this option would have specific knowledge of the
606 device they want to access.
608 If you don't require the option or are in doubt, say N.
611 bool "RDC R-321x SoC"
613 depends on X86_EXTENDED_PLATFORM
615 select X86_REBOOTFIXUPS
617 This option is needed for RDC R-321x system-on-chip, also known
619 If you don't have one of these chips, you should say N here.
621 config X86_32_NON_STANDARD
622 bool "Support non-standard 32-bit SMP architectures"
623 depends on X86_32 && SMP
624 depends on X86_EXTENDED_PLATFORM
626 This option compiles in the bigsmp and STA2X11 default
627 subarchitectures. It is intended for a generic binary
628 kernel. If you select them all, kernel will probe it one by
629 one and will fallback to default.
631 # Alphabetically sorted list of Non standard 32 bit platforms
633 config X86_SUPPORTS_MEMORY_FAILURE
635 # MCE code calls memory_failure():
637 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
638 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
639 depends on X86_64 || !SPARSEMEM
640 select ARCH_SUPPORTS_MEMORY_FAILURE
643 bool "STA2X11 Companion Chip Support"
644 depends on X86_32_NON_STANDARD && PCI
645 select X86_DEV_DMA_OPS
649 select ARCH_REQUIRE_GPIOLIB
652 This adds support for boards based on the STA2X11 IO-Hub,
653 a.k.a. "ConneXt". The chip is used in place of the standard
654 PC chipset, so all "standard" peripherals are missing. If this
655 option is selected the kernel will still be able to boot on
656 standard PC machines.
659 tristate "Eurobraille/Iris poweroff module"
662 The Iris machines from EuroBraille do not have APM or ACPI support
663 to shut themselves down properly. A special I/O sequence is
664 needed to do so, which is what this module does at
667 This is only for Iris machines from EuroBraille.
671 config SCHED_OMIT_FRAME_POINTER
673 prompt "Single-depth WCHAN output"
676 Calculate simpler /proc/<PID>/wchan values. If this option
677 is disabled then wchan values will recurse back to the
678 caller function. This provides more accurate wchan values,
679 at the expense of slightly more scheduling overhead.
681 If in doubt, say "Y".
683 menuconfig HYPERVISOR_GUEST
684 bool "Linux guest support"
686 Say Y here to enable options for running Linux under various hyper-
687 visors. This option enables basic hypervisor detection and platform
690 If you say N, all options in this submenu will be skipped and
691 disabled, and Linux guest support won't be built in.
696 bool "Enable paravirtualization code"
698 This changes the kernel so it can modify itself when it is run
699 under a hypervisor, potentially improving performance significantly
700 over full virtualization. However, when run without a hypervisor
701 the kernel is theoretically slower and slightly larger.
703 config PARAVIRT_DEBUG
704 bool "paravirt-ops debugging"
705 depends on PARAVIRT && DEBUG_KERNEL
707 Enable to debug paravirt_ops internals. Specifically, BUG if
708 a paravirt_op is missing when it is called.
710 config PARAVIRT_SPINLOCKS
711 bool "Paravirtualization layer for spinlocks"
712 depends on PARAVIRT && SMP
713 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
715 Paravirtualized spinlocks allow a pvops backend to replace the
716 spinlock implementation with something virtualization-friendly
717 (for example, block the virtual CPU rather than spinning).
719 It has a minimal impact on native kernels and gives a nice performance
720 benefit on paravirtualized KVM / Xen kernels.
722 If you are unsure how to answer this question, answer Y.
724 config QUEUED_LOCK_STAT
725 bool "Paravirt queued spinlock statistics"
726 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
728 Enable the collection of statistical data on the slowpath
729 behavior of paravirtualized queued spinlocks and report
732 source "arch/x86/xen/Kconfig"
735 bool "KVM Guest support (including kvmclock)"
737 select PARAVIRT_CLOCK
740 This option enables various optimizations for running under the KVM
741 hypervisor. It includes a paravirtualized clock, so that instead
742 of relying on a PIT (or probably other) emulation by the
743 underlying device model, the host provides the guest with
744 timing infrastructure such as time of day, and system time
747 bool "Enable debug information for KVM Guests in debugfs"
748 depends on KVM_GUEST && DEBUG_FS
751 This option enables collection of various statistics for KVM guest.
752 Statistics are displayed in debugfs filesystem. Enabling this option
753 may incur significant overhead.
755 source "arch/x86/lguest/Kconfig"
757 config PARAVIRT_TIME_ACCOUNTING
758 bool "Paravirtual steal time accounting"
762 Select this option to enable fine granularity task steal time
763 accounting. Time spent executing other tasks in parallel with
764 the current vCPU is discounted from the vCPU power. To account for
765 that, there can be a small performance impact.
767 If in doubt, say N here.
769 config PARAVIRT_CLOCK
772 endif #HYPERVISOR_GUEST
777 source "arch/x86/Kconfig.cpu"
781 prompt "HPET Timer Support" if X86_32
783 Use the IA-PC HPET (High Precision Event Timer) to manage
784 time in preference to the PIT and RTC, if a HPET is
786 HPET is the next generation timer replacing legacy 8254s.
787 The HPET provides a stable time base on SMP
788 systems, unlike the TSC, but it is more expensive to access,
789 as it is off-chip. The interface used is documented
790 in the HPET spec, revision 1.
792 You can safely choose Y here. However, HPET will only be
793 activated if the platform and the BIOS support this feature.
794 Otherwise the 8254 will be used for timing services.
796 Choose N to continue using the legacy 8254 timer.
798 config HPET_EMULATE_RTC
800 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
803 def_bool y if X86_INTEL_MID
804 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
806 depends on X86_INTEL_MID && SFI
808 APB timer is the replacement for 8254, HPET on X86 MID platforms.
809 The APBT provides a stable time base on SMP
810 systems, unlike the TSC, but it is more expensive to access,
811 as it is off-chip. APB timers are always running regardless of CPU
812 C states, they are used as per CPU clockevent device when possible.
814 # Mark as expert because too many people got it wrong.
815 # The code disables itself when not needed.
818 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
819 bool "Enable DMI scanning" if EXPERT
821 Enabled scanning of DMI to identify machine quirks. Say Y
822 here unless you have verified that your setup is not
823 affected by entries in the DMI blacklist. Required by PNP
827 bool "Old AMD GART IOMMU support"
829 depends on X86_64 && PCI && AMD_NB
831 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
832 GART based hardware IOMMUs.
834 The GART supports full DMA access for devices with 32-bit access
835 limitations, on systems with more than 3 GB. This is usually needed
836 for USB, sound, many IDE/SATA chipsets and some other devices.
838 Newer systems typically have a modern AMD IOMMU, supported via
839 the CONFIG_AMD_IOMMU=y config option.
841 In normal configurations this driver is only active when needed:
842 there's more than 3 GB of memory and the system contains a
843 32-bit limited device.
848 bool "IBM Calgary IOMMU support"
850 depends on X86_64 && PCI
852 Support for hardware IOMMUs in IBM's xSeries x366 and x460
853 systems. Needed to run systems with more than 3GB of memory
854 properly with 32-bit PCI devices that do not support DAC
855 (Double Address Cycle). Calgary also supports bus level
856 isolation, where all DMAs pass through the IOMMU. This
857 prevents them from going anywhere except their intended
858 destination. This catches hard-to-find kernel bugs and
859 mis-behaving drivers and devices that do not use the DMA-API
860 properly to set up their DMA buffers. The IOMMU can be
861 turned off at boot time with the iommu=off parameter.
862 Normally the kernel will make the right choice by itself.
865 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
867 prompt "Should Calgary be enabled by default?"
868 depends on CALGARY_IOMMU
870 Should Calgary be enabled by default? if you choose 'y', Calgary
871 will be used (if it exists). If you choose 'n', Calgary will not be
872 used even if it exists. If you choose 'n' and would like to use
873 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
876 # need this always selected by IOMMU for the VIA workaround
880 Support for software bounce buffers used on x86-64 systems
881 which don't have a hardware IOMMU. Using this PCI devices
882 which can only access 32-bits of memory can be used on systems
883 with more than 3 GB of memory.
888 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
891 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
892 depends on X86_64 && SMP && DEBUG_KERNEL
893 select CPUMASK_OFFSTACK
895 Enable maximum number of CPUS and NUMA Nodes for this architecture.
899 int "Maximum number of CPUs" if SMP && !MAXSMP
900 range 2 8 if SMP && X86_32 && !X86_BIGSMP
901 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
902 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
904 default "8192" if MAXSMP
905 default "32" if SMP && X86_BIGSMP
906 default "8" if SMP && X86_32
909 This allows you to specify the maximum number of CPUs which this
910 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
911 supported value is 8192, otherwise the maximum value is 512. The
912 minimum value which makes sense is 2.
914 This is purely to save memory - each supported CPU adds
915 approximately eight kilobytes to the kernel image.
918 bool "SMT (Hyperthreading) scheduler support"
921 SMT scheduler support improves the CPU scheduler's decision making
922 when dealing with Intel Pentium 4 chips with HyperThreading at a
923 cost of slightly increased overhead in some places. If unsure say
928 prompt "Multi-core scheduler support"
931 Multi-core scheduler support improves the CPU scheduler's decision
932 making when dealing with multi-core CPU chips at a cost of slightly
933 increased overhead in some places. If unsure say N here.
935 source "kernel/Kconfig.preempt"
939 depends on !SMP && X86_LOCAL_APIC
942 bool "Local APIC support on uniprocessors" if !PCI_MSI
944 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
946 A local APIC (Advanced Programmable Interrupt Controller) is an
947 integrated interrupt controller in the CPU. If you have a single-CPU
948 system which has a processor with a local APIC, you can say Y here to
949 enable and use it. If you say Y here even though your machine doesn't
950 have a local APIC, then the kernel will still run with no slowdown at
951 all. The local APIC supports CPU-generated self-interrupts (timer,
952 performance counters), and the NMI watchdog which detects hard
956 bool "IO-APIC support on uniprocessors"
957 depends on X86_UP_APIC
959 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
960 SMP-capable replacement for PC-style interrupt controllers. Most
961 SMP systems and many recent uniprocessor systems have one.
963 If you have a single-CPU system with an IO-APIC, you can say Y here
964 to use it. If you say Y here even though your machine doesn't have
965 an IO-APIC, then the kernel will still run with no slowdown at all.
967 config X86_LOCAL_APIC
969 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
970 select IRQ_DOMAIN_HIERARCHY
971 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
975 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
977 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
978 bool "Reroute for broken boot IRQs"
979 depends on X86_IO_APIC
981 This option enables a workaround that fixes a source of
982 spurious interrupts. This is recommended when threaded
983 interrupt handling is used on systems where the generation of
984 superfluous "boot interrupts" cannot be disabled.
986 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
987 entry in the chipset's IO-APIC is masked (as, e.g. the RT
988 kernel does during interrupt handling). On chipsets where this
989 boot IRQ generation cannot be disabled, this workaround keeps
990 the original IRQ line masked so that only the equivalent "boot
991 IRQ" is delivered to the CPUs. The workaround also tells the
992 kernel to set up the IRQ handler on the boot IRQ line. In this
993 way only one interrupt is delivered to the kernel. Otherwise
994 the spurious second interrupt may cause the kernel to bring
995 down (vital) interrupt lines.
997 Only affects "broken" chipsets. Interrupt sharing may be
998 increased on these systems.
1001 bool "Machine Check / overheating reporting"
1002 select GENERIC_ALLOCATOR
1005 Machine Check support allows the processor to notify the
1006 kernel if it detects a problem (e.g. overheating, data corruption).
1007 The action the kernel takes depends on the severity of the problem,
1008 ranging from warning messages to halting the machine.
1010 config X86_MCE_INTEL
1012 prompt "Intel MCE features"
1013 depends on X86_MCE && X86_LOCAL_APIC
1015 Additional support for intel specific MCE features such as
1016 the thermal monitor.
1020 prompt "AMD MCE features"
1021 depends on X86_MCE && X86_LOCAL_APIC
1023 Additional support for AMD specific MCE features such as
1024 the DRAM Error Threshold.
1026 config X86_ANCIENT_MCE
1027 bool "Support for old Pentium 5 / WinChip machine checks"
1028 depends on X86_32 && X86_MCE
1030 Include support for machine check handling on old Pentium 5 or WinChip
1031 systems. These typically need to be enabled explicitly on the command
1034 config X86_MCE_THRESHOLD
1035 depends on X86_MCE_AMD || X86_MCE_INTEL
1038 config X86_MCE_INJECT
1040 tristate "Machine check injector support"
1042 Provide support for injecting machine checks for testing purposes.
1043 If you don't know what a machine check is and you don't do kernel
1044 QA it is safe to say n.
1046 config X86_THERMAL_VECTOR
1048 depends on X86_MCE_INTEL
1050 config X86_LEGACY_VM86
1051 bool "Legacy VM86 support"
1055 This option allows user programs to put the CPU into V8086
1056 mode, which is an 80286-era approximation of 16-bit real mode.
1058 Some very old versions of X and/or vbetool require this option
1059 for user mode setting. Similarly, DOSEMU will use it if
1060 available to accelerate real mode DOS programs. However, any
1061 recent version of DOSEMU, X, or vbetool should be fully
1062 functional even without kernel VM86 support, as they will all
1063 fall back to software emulation. Nevertheless, if you are using
1064 a 16-bit DOS program where 16-bit performance matters, vm86
1065 mode might be faster than emulation and you might want to
1068 Note that any app that works on a 64-bit kernel is unlikely to
1069 need this option, as 64-bit kernels don't, and can't, support
1070 V8086 mode. This option is also unrelated to 16-bit protected
1071 mode and is not needed to run most 16-bit programs under Wine.
1073 Enabling this option increases the complexity of the kernel
1074 and slows down exception handling a tiny bit.
1076 If unsure, say N here.
1080 default X86_LEGACY_VM86
1083 bool "Enable support for 16-bit segments" if EXPERT
1085 depends on MODIFY_LDT_SYSCALL
1087 This option is required by programs like Wine to run 16-bit
1088 protected mode legacy code on x86 processors. Disabling
1089 this option saves about 300 bytes on i386, or around 6K text
1090 plus 16K runtime memory on x86-64,
1094 depends on X86_16BIT && X86_32
1098 depends on X86_16BIT && X86_64
1100 config X86_VSYSCALL_EMULATION
1101 bool "Enable vsyscall emulation" if EXPERT
1105 This enables emulation of the legacy vsyscall page. Disabling
1106 it is roughly equivalent to booting with vsyscall=none, except
1107 that it will also disable the helpful warning if a program
1108 tries to use a vsyscall. With this option set to N, offending
1109 programs will just segfault, citing addresses of the form
1112 This option is required by many programs built before 2013, and
1113 care should be used even with newer programs if set to N.
1115 Disabling this option saves about 7K of kernel size and
1116 possibly 4K of additional runtime pagetable memory.
1119 tristate "Toshiba Laptop support"
1122 This adds a driver to safely access the System Management Mode of
1123 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1124 not work on models with a Phoenix BIOS. The System Management Mode
1125 is used to set the BIOS and power saving options on Toshiba portables.
1127 For information on utilities to make use of this driver see the
1128 Toshiba Linux utilities web site at:
1129 <http://www.buzzard.org.uk/toshiba/>.
1131 Say Y if you intend to run this kernel on a Toshiba portable.
1135 tristate "Dell i8k legacy laptop support"
1137 select SENSORS_DELL_SMM
1139 This option enables legacy /proc/i8k userspace interface in hwmon
1140 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1141 temperature and allows controlling fan speeds of Dell laptops via
1142 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1143 it reports also power and hotkey status. For fan speed control is
1144 needed userspace package i8kutils.
1146 Say Y if you intend to run this kernel on old Dell laptops or want to
1147 use userspace package i8kutils.
1150 config X86_REBOOTFIXUPS
1151 bool "Enable X86 board specific fixups for reboot"
1154 This enables chipset and/or board specific fixups to be done
1155 in order to get reboot to work correctly. This is only needed on
1156 some combinations of hardware and BIOS. The symptom, for which
1157 this config is intended, is when reboot ends with a stalled/hung
1160 Currently, the only fixup is for the Geode machines using
1161 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1163 Say Y if you want to enable the fixup. Currently, it's safe to
1164 enable this option even if you don't need it.
1168 bool "CPU microcode loading support"
1170 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1173 If you say Y here, you will be able to update the microcode on
1174 Intel and AMD processors. The Intel support is for the IA32 family,
1175 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1176 AMD support is for families 0x10 and later. You will obviously need
1177 the actual microcode binary data itself which is not shipped with
1180 The preferred method to load microcode from a detached initrd is described
1181 in Documentation/x86/early-microcode.txt. For that you need to enable
1182 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1183 initrd for microcode blobs.
1185 In addition, you can build-in the microcode into the kernel. For that you
1186 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1187 to the CONFIG_EXTRA_FIRMWARE config option.
1189 config MICROCODE_INTEL
1190 bool "Intel microcode loading support"
1191 depends on MICROCODE
1195 This options enables microcode patch loading support for Intel
1198 For the current Intel microcode data package go to
1199 <https://downloadcenter.intel.com> and search for
1200 'Linux Processor Microcode Data File'.
1202 config MICROCODE_AMD
1203 bool "AMD microcode loading support"
1204 depends on MICROCODE
1207 If you select this option, microcode patch loading support for AMD
1208 processors will be enabled.
1210 config MICROCODE_OLD_INTERFACE
1212 depends on MICROCODE
1215 tristate "/dev/cpu/*/msr - Model-specific register support"
1217 This device gives privileged processes access to the x86
1218 Model-Specific Registers (MSRs). It is a character device with
1219 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1220 MSR accesses are directed to a specific CPU on multi-processor
1224 tristate "/dev/cpu/*/cpuid - CPU information support"
1226 This device gives processes access to the x86 CPUID instruction to
1227 be executed on a specific processor. It is a character device
1228 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1232 prompt "High Memory Support"
1239 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1240 However, the address space of 32-bit x86 processors is only 4
1241 Gigabytes large. That means that, if you have a large amount of
1242 physical memory, not all of it can be "permanently mapped" by the
1243 kernel. The physical memory that's not permanently mapped is called
1246 If you are compiling a kernel which will never run on a machine with
1247 more than 1 Gigabyte total physical RAM, answer "off" here (default
1248 choice and suitable for most users). This will result in a "3GB/1GB"
1249 split: 3GB are mapped so that each process sees a 3GB virtual memory
1250 space and the remaining part of the 4GB virtual memory space is used
1251 by the kernel to permanently map as much physical memory as
1254 If the machine has between 1 and 4 Gigabytes physical RAM, then
1257 If more than 4 Gigabytes is used then answer "64GB" here. This
1258 selection turns Intel PAE (Physical Address Extension) mode on.
1259 PAE implements 3-level paging on IA32 processors. PAE is fully
1260 supported by Linux, PAE mode is implemented on all recent Intel
1261 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1262 then the kernel will not boot on CPUs that don't support PAE!
1264 The actual amount of total physical memory will either be
1265 auto detected or can be forced by using a kernel command line option
1266 such as "mem=256M". (Try "man bootparam" or see the documentation of
1267 your boot loader (lilo or loadlin) about how to pass options to the
1268 kernel at boot time.)
1270 If unsure, say "off".
1275 Select this if you have a 32-bit processor and between 1 and 4
1276 gigabytes of physical RAM.
1283 Select this if you have a 32-bit processor and more than 4
1284 gigabytes of physical RAM.
1289 prompt "Memory split" if EXPERT
1293 Select the desired split between kernel and user memory.
1295 If the address range available to the kernel is less than the
1296 physical memory installed, the remaining memory will be available
1297 as "high memory". Accessing high memory is a little more costly
1298 than low memory, as it needs to be mapped into the kernel first.
1299 Note that increasing the kernel address space limits the range
1300 available to user programs, making the address space there
1301 tighter. Selecting anything other than the default 3G/1G split
1302 will also likely make your kernel incompatible with binary-only
1305 If you are not absolutely sure what you are doing, leave this
1309 bool "3G/1G user/kernel split"
1310 config VMSPLIT_3G_OPT
1312 bool "3G/1G user/kernel split (for full 1G low memory)"
1314 bool "2G/2G user/kernel split"
1315 config VMSPLIT_2G_OPT
1317 bool "2G/2G user/kernel split (for full 2G low memory)"
1319 bool "1G/3G user/kernel split"
1324 default 0xB0000000 if VMSPLIT_3G_OPT
1325 default 0x80000000 if VMSPLIT_2G
1326 default 0x78000000 if VMSPLIT_2G_OPT
1327 default 0x40000000 if VMSPLIT_1G
1333 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1336 bool "PAE (Physical Address Extension) Support"
1337 depends on X86_32 && !HIGHMEM4G
1340 PAE is required for NX support, and furthermore enables
1341 larger swapspace support for non-overcommit purposes. It
1342 has the cost of more pagetable lookup overhead, and also
1343 consumes more pagetable space per process.
1345 config ARCH_PHYS_ADDR_T_64BIT
1347 depends on X86_64 || X86_PAE
1349 config ARCH_DMA_ADDR_T_64BIT
1351 depends on X86_64 || HIGHMEM64G
1353 config X86_DIRECT_GBPAGES
1355 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1357 Certain kernel features effectively disable kernel
1358 linear 1 GB mappings (even if the CPU otherwise
1359 supports them), so don't confuse the user by printing
1360 that we have them enabled.
1362 # Common NUMA Features
1364 bool "Numa Memory Allocation and Scheduler Support"
1366 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1367 default y if X86_BIGSMP
1369 Enable NUMA (Non Uniform Memory Access) support.
1371 The kernel will try to allocate memory used by a CPU on the
1372 local memory controller of the CPU and add some more
1373 NUMA awareness to the kernel.
1375 For 64-bit this is recommended if the system is Intel Core i7
1376 (or later), AMD Opteron, or EM64T NUMA.
1378 For 32-bit this is only needed if you boot a 32-bit
1379 kernel on a 64-bit NUMA platform.
1381 Otherwise, you should say N.
1385 prompt "Old style AMD Opteron NUMA detection"
1386 depends on X86_64 && NUMA && PCI
1388 Enable AMD NUMA node topology detection. You should say Y here if
1389 you have a multi processor AMD system. This uses an old method to
1390 read the NUMA configuration directly from the builtin Northbridge
1391 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1392 which also takes priority if both are compiled in.
1394 config X86_64_ACPI_NUMA
1396 prompt "ACPI NUMA detection"
1397 depends on X86_64 && NUMA && ACPI && PCI
1400 Enable ACPI SRAT based node topology detection.
1402 # Some NUMA nodes have memory ranges that span
1403 # other nodes. Even though a pfn is valid and
1404 # between a node's start and end pfns, it may not
1405 # reside on that node. See memmap_init_zone()
1407 config NODES_SPAN_OTHER_NODES
1409 depends on X86_64_ACPI_NUMA
1412 bool "NUMA emulation"
1415 Enable NUMA emulation. A flat machine will be split
1416 into virtual nodes when booted with "numa=fake=N", where N is the
1417 number of nodes. This is only useful for debugging.
1420 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1421 range 1 10 if !NR_ZONES_EXTENDED
1422 range 1 9 if NR_ZONES_EXTENDED
1423 default "10" if MAXSMP && !NR_ZONES_EXTENDED
1424 default "9" if MAXSMP && NR_ZONES_EXTENDED
1425 default "6" if X86_64
1427 depends on NEED_MULTIPLE_NODES
1429 Specify the maximum number of NUMA Nodes available on the target
1430 system. Increases memory reserved to accommodate various tables.
1432 config ARCH_HAVE_MEMORY_PRESENT
1434 depends on X86_32 && DISCONTIGMEM
1436 config NEED_NODE_MEMMAP_SIZE
1438 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1440 config ARCH_FLATMEM_ENABLE
1442 depends on X86_32 && !NUMA
1444 config ARCH_DISCONTIGMEM_ENABLE
1446 depends on NUMA && X86_32
1448 config ARCH_DISCONTIGMEM_DEFAULT
1450 depends on NUMA && X86_32
1452 config ARCH_SPARSEMEM_ENABLE
1454 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1455 select SPARSEMEM_STATIC if X86_32
1456 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1458 config ARCH_SPARSEMEM_DEFAULT
1462 config ARCH_SELECT_MEMORY_MODEL
1464 depends on ARCH_SPARSEMEM_ENABLE
1466 config ARCH_MEMORY_PROBE
1467 bool "Enable sysfs memory/probe interface"
1468 depends on X86_64 && MEMORY_HOTPLUG
1470 This option enables a sysfs memory/probe interface for testing.
1471 See Documentation/memory-hotplug.txt for more information.
1472 If you are unsure how to answer this question, answer N.
1474 config ARCH_PROC_KCORE_TEXT
1476 depends on X86_64 && PROC_KCORE
1478 config ILLEGAL_POINTER_VALUE
1481 default 0xdead000000000000 if X86_64
1485 config X86_PMEM_LEGACY_DEVICE
1488 config X86_PMEM_LEGACY
1489 tristate "Support non-standard NVDIMMs and ADR protected memory"
1490 depends on PHYS_ADDR_T_64BIT
1492 select X86_PMEM_LEGACY_DEVICE
1495 Treat memory marked using the non-standard e820 type of 12 as used
1496 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1497 The kernel will offer these regions to the 'pmem' driver so
1498 they can be used for persistent storage.
1503 bool "Allocate 3rd-level pagetables from highmem"
1506 The VM uses one page table entry for each page of physical memory.
1507 For systems with a lot of RAM, this can be wasteful of precious
1508 low memory. Setting this option will put user-space page table
1509 entries in high memory.
1511 config X86_CHECK_BIOS_CORRUPTION
1512 bool "Check for low memory corruption"
1514 Periodically check for memory corruption in low memory, which
1515 is suspected to be caused by BIOS. Even when enabled in the
1516 configuration, it is disabled at runtime. Enable it by
1517 setting "memory_corruption_check=1" on the kernel command
1518 line. By default it scans the low 64k of memory every 60
1519 seconds; see the memory_corruption_check_size and
1520 memory_corruption_check_period parameters in
1521 Documentation/kernel-parameters.txt to adjust this.
1523 When enabled with the default parameters, this option has
1524 almost no overhead, as it reserves a relatively small amount
1525 of memory and scans it infrequently. It both detects corruption
1526 and prevents it from affecting the running system.
1528 It is, however, intended as a diagnostic tool; if repeatable
1529 BIOS-originated corruption always affects the same memory,
1530 you can use memmap= to prevent the kernel from using that
1533 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1534 bool "Set the default setting of memory_corruption_check"
1535 depends on X86_CHECK_BIOS_CORRUPTION
1538 Set whether the default state of memory_corruption_check is
1541 config X86_RESERVE_LOW
1542 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1546 Specify the amount of low memory to reserve for the BIOS.
1548 The first page contains BIOS data structures that the kernel
1549 must not use, so that page must always be reserved.
1551 By default we reserve the first 64K of physical RAM, as a
1552 number of BIOSes are known to corrupt that memory range
1553 during events such as suspend/resume or monitor cable
1554 insertion, so it must not be used by the kernel.
1556 You can set this to 4 if you are absolutely sure that you
1557 trust the BIOS to get all its memory reservations and usages
1558 right. If you know your BIOS have problems beyond the
1559 default 64K area, you can set this to 640 to avoid using the
1560 entire low memory range.
1562 If you have doubts about the BIOS (e.g. suspend/resume does
1563 not work or there's kernel crashes after certain hardware
1564 hotplug events) then you might want to enable
1565 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1566 typical corruption patterns.
1568 Leave this to the default value of 64 if you are unsure.
1570 config MATH_EMULATION
1572 depends on MODIFY_LDT_SYSCALL
1573 prompt "Math emulation" if X86_32
1575 Linux can emulate a math coprocessor (used for floating point
1576 operations) if you don't have one. 486DX and Pentium processors have
1577 a math coprocessor built in, 486SX and 386 do not, unless you added
1578 a 487DX or 387, respectively. (The messages during boot time can
1579 give you some hints here ["man dmesg"].) Everyone needs either a
1580 coprocessor or this emulation.
1582 If you don't have a math coprocessor, you need to say Y here; if you
1583 say Y here even though you have a coprocessor, the coprocessor will
1584 be used nevertheless. (This behavior can be changed with the kernel
1585 command line option "no387", which comes handy if your coprocessor
1586 is broken. Try "man bootparam" or see the documentation of your boot
1587 loader (lilo or loadlin) about how to pass options to the kernel at
1588 boot time.) This means that it is a good idea to say Y here if you
1589 intend to use this kernel on different machines.
1591 More information about the internals of the Linux math coprocessor
1592 emulation can be found in <file:arch/x86/math-emu/README>.
1594 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1595 kernel, it won't hurt.
1599 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1601 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1602 the Memory Type Range Registers (MTRRs) may be used to control
1603 processor access to memory ranges. This is most useful if you have
1604 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1605 allows bus write transfers to be combined into a larger transfer
1606 before bursting over the PCI/AGP bus. This can increase performance
1607 of image write operations 2.5 times or more. Saying Y here creates a
1608 /proc/mtrr file which may be used to manipulate your processor's
1609 MTRRs. Typically the X server should use this.
1611 This code has a reasonably generic interface so that similar
1612 control registers on other processors can be easily supported
1615 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1616 Registers (ARRs) which provide a similar functionality to MTRRs. For
1617 these, the ARRs are used to emulate the MTRRs.
1618 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1619 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1620 write-combining. All of these processors are supported by this code
1621 and it makes sense to say Y here if you have one of them.
1623 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1624 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1625 can lead to all sorts of problems, so it's good to say Y here.
1627 You can safely say Y even if your machine doesn't have MTRRs, you'll
1628 just add about 9 KB to your kernel.
1630 See <file:Documentation/x86/mtrr.txt> for more information.
1632 config MTRR_SANITIZER
1634 prompt "MTRR cleanup support"
1637 Convert MTRR layout from continuous to discrete, so X drivers can
1638 add writeback entries.
1640 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1641 The largest mtrr entry size for a continuous block can be set with
1646 config MTRR_SANITIZER_ENABLE_DEFAULT
1647 int "MTRR cleanup enable value (0-1)"
1650 depends on MTRR_SANITIZER
1652 Enable mtrr cleanup default value
1654 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1655 int "MTRR cleanup spare reg num (0-7)"
1658 depends on MTRR_SANITIZER
1660 mtrr cleanup spare entries default, it can be changed via
1661 mtrr_spare_reg_nr=N on the kernel command line.
1665 prompt "x86 PAT support" if EXPERT
1668 Use PAT attributes to setup page level cache control.
1670 PATs are the modern equivalents of MTRRs and are much more
1671 flexible than MTRRs.
1673 Say N here if you see bootup problems (boot crash, boot hang,
1674 spontaneous reboots) or a non-working video driver.
1678 config ARCH_USES_PG_UNCACHED
1684 prompt "x86 architectural random number generator" if EXPERT
1686 Enable the x86 architectural RDRAND instruction
1687 (Intel Bull Mountain technology) to generate random numbers.
1688 If supported, this is a high bandwidth, cryptographically
1689 secure hardware random number generator.
1693 prompt "Supervisor Mode Access Prevention" if EXPERT
1695 Supervisor Mode Access Prevention (SMAP) is a security
1696 feature in newer Intel processors. There is a small
1697 performance cost if this enabled and turned on; there is
1698 also a small increase in the kernel size if this is enabled.
1702 config X86_INTEL_MPX
1703 prompt "Intel MPX (Memory Protection Extensions)"
1705 depends on CPU_SUP_INTEL
1707 MPX provides hardware features that can be used in
1708 conjunction with compiler-instrumented code to check
1709 memory references. It is designed to detect buffer
1710 overflow or underflow bugs.
1712 This option enables running applications which are
1713 instrumented or otherwise use MPX. It does not use MPX
1714 itself inside the kernel or to protect the kernel
1715 against bad memory references.
1717 Enabling this option will make the kernel larger:
1718 ~8k of kernel text and 36 bytes of data on a 64-bit
1719 defconfig. It adds a long to the 'mm_struct' which
1720 will increase the kernel memory overhead of each
1721 process and adds some branches to paths used during
1722 exec() and munmap().
1724 For details, see Documentation/x86/intel_mpx.txt
1728 config X86_INTEL_MEMORY_PROTECTION_KEYS
1729 prompt "Intel Memory Protection Keys"
1731 # Note: only available in 64-bit mode
1732 depends on CPU_SUP_INTEL && X86_64
1734 Memory Protection Keys provides a mechanism for enforcing
1735 page-based protections, but without requiring modification of the
1736 page tables when an application changes protection domains.
1738 For details, see Documentation/x86/protection-keys.txt
1743 bool "EFI runtime service support"
1746 select EFI_RUNTIME_WRAPPERS
1748 This enables the kernel to use EFI runtime services that are
1749 available (such as the EFI variable services).
1751 This option is only useful on systems that have EFI firmware.
1752 In addition, you should use the latest ELILO loader available
1753 at <http://elilo.sourceforge.net> in order to take advantage
1754 of EFI runtime services. However, even with this option, the
1755 resultant kernel should continue to boot on existing non-EFI
1759 bool "EFI stub support"
1760 depends on EFI && !X86_USE_3DNOW
1763 This kernel feature allows a bzImage to be loaded directly
1764 by EFI firmware without the use of a bootloader.
1766 See Documentation/efi-stub.txt for more information.
1769 bool "EFI mixed-mode support"
1770 depends on EFI_STUB && X86_64
1772 Enabling this feature allows a 64-bit kernel to be booted
1773 on a 32-bit firmware, provided that your CPU supports 64-bit
1776 Note that it is not possible to boot a mixed-mode enabled
1777 kernel via the EFI boot stub - a bootloader that supports
1778 the EFI handover protocol must be used.
1784 prompt "Enable seccomp to safely compute untrusted bytecode"
1786 This kernel feature is useful for number crunching applications
1787 that may need to compute untrusted bytecode during their
1788 execution. By using pipes or other transports made available to
1789 the process as file descriptors supporting the read/write
1790 syscalls, it's possible to isolate those applications in
1791 their own address space using seccomp. Once seccomp is
1792 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1793 and the task is only allowed to execute a few safe syscalls
1794 defined by each seccomp mode.
1796 If unsure, say Y. Only embedded should say N here.
1798 source kernel/Kconfig.hz
1801 bool "kexec system call"
1804 kexec is a system call that implements the ability to shutdown your
1805 current kernel, and to start another kernel. It is like a reboot
1806 but it is independent of the system firmware. And like a reboot
1807 you can start any kernel with it, not just Linux.
1809 The name comes from the similarity to the exec system call.
1811 It is an ongoing process to be certain the hardware in a machine
1812 is properly shutdown, so do not be surprised if this code does not
1813 initially work for you. As of this writing the exact hardware
1814 interface is strongly in flux, so no good recommendation can be
1818 bool "kexec file based system call"
1823 depends on CRYPTO_SHA256=y
1825 This is new version of kexec system call. This system call is
1826 file based and takes file descriptors as system call argument
1827 for kernel and initramfs as opposed to list of segments as
1828 accepted by previous system call.
1830 config KEXEC_VERIFY_SIG
1831 bool "Verify kernel signature during kexec_file_load() syscall"
1832 depends on KEXEC_FILE
1834 This option makes kernel signature verification mandatory for
1835 the kexec_file_load() syscall.
1837 In addition to that option, you need to enable signature
1838 verification for the corresponding kernel image type being
1839 loaded in order for this to work.
1841 config KEXEC_BZIMAGE_VERIFY_SIG
1842 bool "Enable bzImage signature verification support"
1843 depends on KEXEC_VERIFY_SIG
1844 depends on SIGNED_PE_FILE_VERIFICATION
1845 select SYSTEM_TRUSTED_KEYRING
1847 Enable bzImage signature verification support.
1850 bool "kernel crash dumps"
1851 depends on X86_64 || (X86_32 && HIGHMEM)
1853 Generate crash dump after being started by kexec.
1854 This should be normally only set in special crash dump kernels
1855 which are loaded in the main kernel with kexec-tools into
1856 a specially reserved region and then later executed after
1857 a crash by kdump/kexec. The crash dump kernel must be compiled
1858 to a memory address not used by the main kernel or BIOS using
1859 PHYSICAL_START, or it must be built as a relocatable image
1860 (CONFIG_RELOCATABLE=y).
1861 For more details see Documentation/kdump/kdump.txt
1865 depends on KEXEC && HIBERNATION
1867 Jump between original kernel and kexeced kernel and invoke
1868 code in physical address mode via KEXEC
1870 config PHYSICAL_START
1871 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1874 This gives the physical address where the kernel is loaded.
1876 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1877 bzImage will decompress itself to above physical address and
1878 run from there. Otherwise, bzImage will run from the address where
1879 it has been loaded by the boot loader and will ignore above physical
1882 In normal kdump cases one does not have to set/change this option
1883 as now bzImage can be compiled as a completely relocatable image
1884 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1885 address. This option is mainly useful for the folks who don't want
1886 to use a bzImage for capturing the crash dump and want to use a
1887 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1888 to be specifically compiled to run from a specific memory area
1889 (normally a reserved region) and this option comes handy.
1891 So if you are using bzImage for capturing the crash dump,
1892 leave the value here unchanged to 0x1000000 and set
1893 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1894 for capturing the crash dump change this value to start of
1895 the reserved region. In other words, it can be set based on
1896 the "X" value as specified in the "crashkernel=YM@XM"
1897 command line boot parameter passed to the panic-ed
1898 kernel. Please take a look at Documentation/kdump/kdump.txt
1899 for more details about crash dumps.
1901 Usage of bzImage for capturing the crash dump is recommended as
1902 one does not have to build two kernels. Same kernel can be used
1903 as production kernel and capture kernel. Above option should have
1904 gone away after relocatable bzImage support is introduced. But it
1905 is present because there are users out there who continue to use
1906 vmlinux for dump capture. This option should go away down the
1909 Don't change this unless you know what you are doing.
1912 bool "Build a relocatable kernel"
1915 This builds a kernel image that retains relocation information
1916 so it can be loaded someplace besides the default 1MB.
1917 The relocations tend to make the kernel binary about 10% larger,
1918 but are discarded at runtime.
1920 One use is for the kexec on panic case where the recovery kernel
1921 must live at a different physical address than the primary
1924 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1925 it has been loaded at and the compile time physical address
1926 (CONFIG_PHYSICAL_START) is used as the minimum location.
1928 config RANDOMIZE_BASE
1929 bool "Randomize the address of the kernel image"
1930 depends on RELOCATABLE
1933 Randomizes the physical and virtual address at which the
1934 kernel image is decompressed, as a security feature that
1935 deters exploit attempts relying on knowledge of the location
1936 of kernel internals.
1938 Entropy is generated using the RDRAND instruction if it is
1939 supported. If RDTSC is supported, it is used as well. If
1940 neither RDRAND nor RDTSC are supported, then randomness is
1941 read from the i8254 timer.
1943 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1944 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1945 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1946 minimum of 2MiB, only 10 bits of entropy is theoretically
1947 possible. At best, due to page table layouts, 64-bit can use
1948 9 bits of entropy and 32-bit uses 8 bits.
1952 config RANDOMIZE_BASE_MAX_OFFSET
1953 hex "Maximum kASLR offset allowed" if EXPERT
1954 depends on RANDOMIZE_BASE
1955 range 0x0 0x20000000 if X86_32
1956 default "0x20000000" if X86_32
1957 range 0x0 0x40000000 if X86_64
1958 default "0x40000000" if X86_64
1960 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1961 memory is used to determine the maximal offset in bytes that will
1962 be applied to the kernel when kernel Address Space Layout
1963 Randomization (kASLR) is active. This must be a multiple of
1966 On 32-bit this is limited to 512MiB by page table layouts. The
1969 On 64-bit this is limited by how the kernel fixmap page table is
1970 positioned, so this cannot be larger than 1GiB currently. Without
1971 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1972 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1973 modules area will shrink to compensate, up to the current maximum
1974 1GiB to 1GiB split. The default is 1GiB.
1976 If unsure, leave at the default value.
1978 # Relocation on x86 needs some additional build support
1979 config X86_NEED_RELOCS
1981 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1983 config PHYSICAL_ALIGN
1984 hex "Alignment value to which kernel should be aligned"
1986 range 0x2000 0x1000000 if X86_32
1987 range 0x200000 0x1000000 if X86_64
1989 This value puts the alignment restrictions on physical address
1990 where kernel is loaded and run from. Kernel is compiled for an
1991 address which meets above alignment restriction.
1993 If bootloader loads the kernel at a non-aligned address and
1994 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1995 address aligned to above value and run from there.
1997 If bootloader loads the kernel at a non-aligned address and
1998 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1999 load address and decompress itself to the address it has been
2000 compiled for and run from there. The address for which kernel is
2001 compiled already meets above alignment restrictions. Hence the
2002 end result is that kernel runs from a physical address meeting
2003 above alignment restrictions.
2005 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2006 this value must be a multiple of 0x200000.
2008 Don't change this unless you know what you are doing.
2011 bool "Support for hot-pluggable CPUs"
2014 Say Y here to allow turning CPUs off and on. CPUs can be
2015 controlled through /sys/devices/system/cpu.
2016 ( Note: power management support will enable this option
2017 automatically on SMP systems. )
2018 Say N if you want to disable CPU hotplug.
2020 config BOOTPARAM_HOTPLUG_CPU0
2021 bool "Set default setting of cpu0_hotpluggable"
2023 depends on HOTPLUG_CPU
2025 Set whether default state of cpu0_hotpluggable is on or off.
2027 Say Y here to enable CPU0 hotplug by default. If this switch
2028 is turned on, there is no need to give cpu0_hotplug kernel
2029 parameter and the CPU0 hotplug feature is enabled by default.
2031 Please note: there are two known CPU0 dependencies if you want
2032 to enable the CPU0 hotplug feature either by this switch or by
2033 cpu0_hotplug kernel parameter.
2035 First, resume from hibernate or suspend always starts from CPU0.
2036 So hibernate and suspend are prevented if CPU0 is offline.
2038 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2039 offline if any interrupt can not migrate out of CPU0. There may
2040 be other CPU0 dependencies.
2042 Please make sure the dependencies are under your control before
2043 you enable this feature.
2045 Say N if you don't want to enable CPU0 hotplug feature by default.
2046 You still can enable the CPU0 hotplug feature at boot by kernel
2047 parameter cpu0_hotplug.
2049 config DEBUG_HOTPLUG_CPU0
2051 prompt "Debug CPU0 hotplug"
2052 depends on HOTPLUG_CPU
2054 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2055 soon as possible and boots up userspace with CPU0 offlined. User
2056 can online CPU0 back after boot time.
2058 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2059 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2060 compilation or giving cpu0_hotplug kernel parameter at boot.
2066 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2067 depends on X86_32 || IA32_EMULATION
2069 Certain buggy versions of glibc will crash if they are
2070 presented with a 32-bit vDSO that is not mapped at the address
2071 indicated in its segment table.
2073 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2074 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2075 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2076 the only released version with the bug, but OpenSUSE 9
2077 contains a buggy "glibc 2.3.2".
2079 The symptom of the bug is that everything crashes on startup, saying:
2080 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2082 Saying Y here changes the default value of the vdso32 boot
2083 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2084 This works around the glibc bug but hurts performance.
2086 If unsure, say N: if you are compiling your own kernel, you
2087 are unlikely to be using a buggy version of glibc.
2090 prompt "vsyscall table for legacy applications"
2092 default LEGACY_VSYSCALL_EMULATE
2094 Legacy user code that does not know how to find the vDSO expects
2095 to be able to issue three syscalls by calling fixed addresses in
2096 kernel space. Since this location is not randomized with ASLR,
2097 it can be used to assist security vulnerability exploitation.
2099 This setting can be changed at boot time via the kernel command
2100 line parameter vsyscall=[native|emulate|none].
2102 On a system with recent enough glibc (2.14 or newer) and no
2103 static binaries, you can say None without a performance penalty
2104 to improve security.
2106 If unsure, select "Emulate".
2108 config LEGACY_VSYSCALL_NATIVE
2111 Actual executable code is located in the fixed vsyscall
2112 address mapping, implementing time() efficiently. Since
2113 this makes the mapping executable, it can be used during
2114 security vulnerability exploitation (traditionally as
2115 ROP gadgets). This configuration is not recommended.
2117 config LEGACY_VSYSCALL_EMULATE
2120 The kernel traps and emulates calls into the fixed
2121 vsyscall address mapping. This makes the mapping
2122 non-executable, but it still contains known contents,
2123 which could be used in certain rare security vulnerability
2124 exploits. This configuration is recommended when userspace
2125 still uses the vsyscall area.
2127 config LEGACY_VSYSCALL_NONE
2130 There will be no vsyscall mapping at all. This will
2131 eliminate any risk of ASLR bypass due to the vsyscall
2132 fixed address mapping. Attempts to use the vsyscalls
2133 will be reported to dmesg, so that either old or
2134 malicious userspace programs can be identified.
2139 bool "Built-in kernel command line"
2141 Allow for specifying boot arguments to the kernel at
2142 build time. On some systems (e.g. embedded ones), it is
2143 necessary or convenient to provide some or all of the
2144 kernel boot arguments with the kernel itself (that is,
2145 to not rely on the boot loader to provide them.)
2147 To compile command line arguments into the kernel,
2148 set this option to 'Y', then fill in the
2149 boot arguments in CONFIG_CMDLINE.
2151 Systems with fully functional boot loaders (i.e. non-embedded)
2152 should leave this option set to 'N'.
2155 string "Built-in kernel command string"
2156 depends on CMDLINE_BOOL
2159 Enter arguments here that should be compiled into the kernel
2160 image and used at boot time. If the boot loader provides a
2161 command line at boot time, it is appended to this string to
2162 form the full kernel command line, when the system boots.
2164 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2165 change this behavior.
2167 In most cases, the command line (whether built-in or provided
2168 by the boot loader) should specify the device for the root
2171 config CMDLINE_OVERRIDE
2172 bool "Built-in command line overrides boot loader arguments"
2173 depends on CMDLINE_BOOL
2175 Set this option to 'Y' to have the kernel ignore the boot loader
2176 command line, and use ONLY the built-in command line.
2178 This is used to work around broken boot loaders. This should
2179 be set to 'N' under normal conditions.
2181 config MODIFY_LDT_SYSCALL
2182 bool "Enable the LDT (local descriptor table)" if EXPERT
2185 Linux can allow user programs to install a per-process x86
2186 Local Descriptor Table (LDT) using the modify_ldt(2) system
2187 call. This is required to run 16-bit or segmented code such as
2188 DOSEMU or some Wine programs. It is also used by some very old
2189 threading libraries.
2191 Enabling this feature adds a small amount of overhead to
2192 context switches and increases the low-level kernel attack
2193 surface. Disabling it removes the modify_ldt(2) system call.
2195 Saying 'N' here may make sense for embedded or server kernels.
2197 source "kernel/livepatch/Kconfig"
2201 config ARCH_ENABLE_MEMORY_HOTPLUG
2203 depends on X86_64 || (X86_32 && HIGHMEM)
2205 config ARCH_ENABLE_MEMORY_HOTREMOVE
2207 depends on MEMORY_HOTPLUG
2209 config USE_PERCPU_NUMA_NODE_ID
2213 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2215 depends on X86_64 || X86_PAE
2217 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2219 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2221 menu "Power management and ACPI options"
2223 config ARCH_HIBERNATION_HEADER
2225 depends on X86_64 && HIBERNATION
2227 source "kernel/power/Kconfig"
2229 source "drivers/acpi/Kconfig"
2231 source "drivers/sfi/Kconfig"
2238 tristate "APM (Advanced Power Management) BIOS support"
2239 depends on X86_32 && PM_SLEEP
2241 APM is a BIOS specification for saving power using several different
2242 techniques. This is mostly useful for battery powered laptops with
2243 APM compliant BIOSes. If you say Y here, the system time will be
2244 reset after a RESUME operation, the /proc/apm device will provide
2245 battery status information, and user-space programs will receive
2246 notification of APM "events" (e.g. battery status change).
2248 If you select "Y" here, you can disable actual use of the APM
2249 BIOS by passing the "apm=off" option to the kernel at boot time.
2251 Note that the APM support is almost completely disabled for
2252 machines with more than one CPU.
2254 In order to use APM, you will need supporting software. For location
2255 and more information, read <file:Documentation/power/apm-acpi.txt>
2256 and the Battery Powered Linux mini-HOWTO, available from
2257 <http://www.tldp.org/docs.html#howto>.
2259 This driver does not spin down disk drives (see the hdparm(8)
2260 manpage ("man 8 hdparm") for that), and it doesn't turn off
2261 VESA-compliant "green" monitors.
2263 This driver does not support the TI 4000M TravelMate and the ACER
2264 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2265 desktop machines also don't have compliant BIOSes, and this driver
2266 may cause those machines to panic during the boot phase.
2268 Generally, if you don't have a battery in your machine, there isn't
2269 much point in using this driver and you should say N. If you get
2270 random kernel OOPSes or reboots that don't seem to be related to
2271 anything, try disabling/enabling this option (or disabling/enabling
2274 Some other things you should try when experiencing seemingly random,
2277 1) make sure that you have enough swap space and that it is
2279 2) pass the "no-hlt" option to the kernel
2280 3) switch on floating point emulation in the kernel and pass
2281 the "no387" option to the kernel
2282 4) pass the "floppy=nodma" option to the kernel
2283 5) pass the "mem=4M" option to the kernel (thereby disabling
2284 all but the first 4 MB of RAM)
2285 6) make sure that the CPU is not over clocked.
2286 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2287 8) disable the cache from your BIOS settings
2288 9) install a fan for the video card or exchange video RAM
2289 10) install a better fan for the CPU
2290 11) exchange RAM chips
2291 12) exchange the motherboard.
2293 To compile this driver as a module, choose M here: the
2294 module will be called apm.
2298 config APM_IGNORE_USER_SUSPEND
2299 bool "Ignore USER SUSPEND"
2301 This option will ignore USER SUSPEND requests. On machines with a
2302 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2303 series notebooks, it is necessary to say Y because of a BIOS bug.
2305 config APM_DO_ENABLE
2306 bool "Enable PM at boot time"
2308 Enable APM features at boot time. From page 36 of the APM BIOS
2309 specification: "When disabled, the APM BIOS does not automatically
2310 power manage devices, enter the Standby State, enter the Suspend
2311 State, or take power saving steps in response to CPU Idle calls."
2312 This driver will make CPU Idle calls when Linux is idle (unless this
2313 feature is turned off -- see "Do CPU IDLE calls", below). This
2314 should always save battery power, but more complicated APM features
2315 will be dependent on your BIOS implementation. You may need to turn
2316 this option off if your computer hangs at boot time when using APM
2317 support, or if it beeps continuously instead of suspending. Turn
2318 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2319 T400CDT. This is off by default since most machines do fine without
2324 bool "Make CPU Idle calls when idle"
2326 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2327 On some machines, this can activate improved power savings, such as
2328 a slowed CPU clock rate, when the machine is idle. These idle calls
2329 are made after the idle loop has run for some length of time (e.g.,
2330 333 mS). On some machines, this will cause a hang at boot time or
2331 whenever the CPU becomes idle. (On machines with more than one CPU,
2332 this option does nothing.)
2334 config APM_DISPLAY_BLANK
2335 bool "Enable console blanking using APM"
2337 Enable console blanking using the APM. Some laptops can use this to
2338 turn off the LCD backlight when the screen blanker of the Linux
2339 virtual console blanks the screen. Note that this is only used by
2340 the virtual console screen blanker, and won't turn off the backlight
2341 when using the X Window system. This also doesn't have anything to
2342 do with your VESA-compliant power-saving monitor. Further, this
2343 option doesn't work for all laptops -- it might not turn off your
2344 backlight at all, or it might print a lot of errors to the console,
2345 especially if you are using gpm.
2347 config APM_ALLOW_INTS
2348 bool "Allow interrupts during APM BIOS calls"
2350 Normally we disable external interrupts while we are making calls to
2351 the APM BIOS as a measure to lessen the effects of a badly behaving
2352 BIOS implementation. The BIOS should reenable interrupts if it
2353 needs to. Unfortunately, some BIOSes do not -- especially those in
2354 many of the newer IBM Thinkpads. If you experience hangs when you
2355 suspend, try setting this to Y. Otherwise, say N.
2359 source "drivers/cpufreq/Kconfig"
2361 source "drivers/cpuidle/Kconfig"
2363 source "drivers/idle/Kconfig"
2368 menu "Bus options (PCI etc.)"
2374 Find out whether you have a PCI motherboard. PCI is the name of a
2375 bus system, i.e. the way the CPU talks to the other stuff inside
2376 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2377 VESA. If you have PCI, say Y, otherwise N.
2380 prompt "PCI access mode"
2381 depends on X86_32 && PCI
2384 On PCI systems, the BIOS can be used to detect the PCI devices and
2385 determine their configuration. However, some old PCI motherboards
2386 have BIOS bugs and may crash if this is done. Also, some embedded
2387 PCI-based systems don't have any BIOS at all. Linux can also try to
2388 detect the PCI hardware directly without using the BIOS.
2390 With this option, you can specify how Linux should detect the
2391 PCI devices. If you choose "BIOS", the BIOS will be used,
2392 if you choose "Direct", the BIOS won't be used, and if you
2393 choose "MMConfig", then PCI Express MMCONFIG will be used.
2394 If you choose "Any", the kernel will try MMCONFIG, then the
2395 direct access method and falls back to the BIOS if that doesn't
2396 work. If unsure, go with the default, which is "Any".
2401 config PCI_GOMMCONFIG
2418 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2420 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2423 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2427 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2431 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2435 depends on PCI && XEN
2443 bool "Support mmconfig PCI config space access"
2444 depends on X86_64 && PCI && ACPI
2446 config PCI_CNB20LE_QUIRK
2447 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2450 Read the PCI windows out of the CNB20LE host bridge. This allows
2451 PCI hotplug to work on systems with the CNB20LE chipset which do
2454 There's no public spec for this chipset, and this functionality
2455 is known to be incomplete.
2457 You should say N unless you know you need this.
2459 source "drivers/pci/pcie/Kconfig"
2461 source "drivers/pci/Kconfig"
2463 # x86_64 have no ISA slots, but can have ISA-style DMA.
2465 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2468 Enables ISA-style DMA support for devices requiring such controllers.
2476 Find out whether you have ISA slots on your motherboard. ISA is the
2477 name of a bus system, i.e. the way the CPU talks to the other stuff
2478 inside your box. Other bus systems are PCI, EISA, MicroChannel
2479 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2480 newer boards don't support it. If you have ISA, say Y, otherwise N.
2486 The Extended Industry Standard Architecture (EISA) bus was
2487 developed as an open alternative to the IBM MicroChannel bus.
2489 The EISA bus provided some of the features of the IBM MicroChannel
2490 bus while maintaining backward compatibility with cards made for
2491 the older ISA bus. The EISA bus saw limited use between 1988 and
2492 1995 when it was made obsolete by the PCI bus.
2494 Say Y here if you are building a kernel for an EISA-based machine.
2498 source "drivers/eisa/Kconfig"
2501 tristate "NatSemi SCx200 support"
2503 This provides basic support for National Semiconductor's
2504 (now AMD's) Geode processors. The driver probes for the
2505 PCI-IDs of several on-chip devices, so its a good dependency
2506 for other scx200_* drivers.
2508 If compiled as a module, the driver is named scx200.
2510 config SCx200HR_TIMER
2511 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2515 This driver provides a clocksource built upon the on-chip
2516 27MHz high-resolution timer. Its also a workaround for
2517 NSC Geode SC-1100's buggy TSC, which loses time when the
2518 processor goes idle (as is done by the scheduler). The
2519 other workaround is idle=poll boot option.
2522 bool "One Laptop Per Child support"
2529 Add support for detecting the unique features of the OLPC
2533 bool "OLPC XO-1 Power Management"
2534 depends on OLPC && MFD_CS5535 && PM_SLEEP
2537 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2540 bool "OLPC XO-1 Real Time Clock"
2541 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2543 Add support for the XO-1 real time clock, which can be used as a
2544 programmable wakeup source.
2547 bool "OLPC XO-1 SCI extras"
2548 depends on OLPC && OLPC_XO1_PM
2554 Add support for SCI-based features of the OLPC XO-1 laptop:
2555 - EC-driven system wakeups
2559 - AC adapter status updates
2560 - Battery status updates
2562 config OLPC_XO15_SCI
2563 bool "OLPC XO-1.5 SCI extras"
2564 depends on OLPC && ACPI
2567 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2568 - EC-driven system wakeups
2569 - AC adapter status updates
2570 - Battery status updates
2573 bool "PCEngines ALIX System Support (LED setup)"
2576 This option enables system support for the PCEngines ALIX.
2577 At present this just sets up LEDs for GPIO control on
2578 ALIX2/3/6 boards. However, other system specific setup should
2581 Note: You must still enable the drivers for GPIO and LED support
2582 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2584 Note: You have to set alix.force=1 for boards with Award BIOS.
2587 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2590 This option enables system support for the Soekris Engineering net5501.
2593 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2597 This option enables system support for the Traverse Technologies GEOS.
2600 bool "Technologic Systems TS-5500 platform support"
2602 select CHECK_SIGNATURE
2606 This option enables system support for the Technologic Systems TS-5500.
2612 depends on CPU_SUP_AMD && PCI
2614 source "drivers/pcmcia/Kconfig"
2616 source "drivers/pci/hotplug/Kconfig"
2619 tristate "RapidIO support"
2623 If enabled this option will include drivers and the core
2624 infrastructure code to support RapidIO interconnect devices.
2626 source "drivers/rapidio/Kconfig"
2629 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2631 Firmwares often provide initial graphics framebuffers so the BIOS,
2632 bootloader or kernel can show basic video-output during boot for
2633 user-guidance and debugging. Historically, x86 used the VESA BIOS
2634 Extensions and EFI-framebuffers for this, which are mostly limited
2636 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2637 framebuffers so the new generic system-framebuffer drivers can be
2638 used on x86. If the framebuffer is not compatible with the generic
2639 modes, it is adverticed as fallback platform framebuffer so legacy
2640 drivers like efifb, vesafb and uvesafb can pick it up.
2641 If this option is not selected, all system framebuffers are always
2642 marked as fallback platform framebuffers as usual.
2644 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2645 not be able to pick up generic system framebuffers if this option
2646 is selected. You are highly encouraged to enable simplefb as
2647 replacement if you select this option. simplefb can correctly deal
2648 with generic system framebuffers. But you should still keep vesafb
2649 and others enabled as fallback if a system framebuffer is
2650 incompatible with simplefb.
2657 menu "Executable file formats / Emulations"
2659 source "fs/Kconfig.binfmt"
2661 config IA32_EMULATION
2662 bool "IA32 Emulation"
2665 select COMPAT_BINFMT_ELF
2666 select ARCH_WANT_OLD_COMPAT_IPC
2668 Include code to run legacy 32-bit programs under a
2669 64-bit kernel. You should likely turn this on, unless you're
2670 100% sure that you don't have any 32-bit programs left.
2673 tristate "IA32 a.out support"
2674 depends on IA32_EMULATION
2676 Support old a.out binaries in the 32bit emulation.
2679 bool "x32 ABI for 64-bit mode"
2682 Include code to run binaries for the x32 native 32-bit ABI
2683 for 64-bit processors. An x32 process gets access to the
2684 full 64-bit register file and wide data path while leaving
2685 pointers at 32 bits for smaller memory footprint.
2687 You will need a recent binutils (2.22 or later) with
2688 elf32_x86_64 support enabled to compile a kernel with this
2693 depends on IA32_EMULATION || X86_X32
2696 config COMPAT_FOR_U64_ALIGNMENT
2699 config SYSVIPC_COMPAT
2711 config HAVE_ATOMIC_IOMAP
2715 config X86_DEV_DMA_OPS
2717 depends on X86_64 || STA2X11
2719 config X86_DMA_REMAP
2729 tristate "Volume Management Device Driver"
2732 Adds support for the Intel Volume Management Device (VMD). VMD is a
2733 secondary PCI host bridge that allows PCI Express root ports,
2734 and devices attached to them, to be removed from the default
2735 PCI domain and placed within the VMD domain. This provides
2736 more bus resources than are otherwise possible with a
2737 single domain. If you know your system provides one of these and
2738 has devices attached to it, say Y; if you are not sure, say N.
2740 source "net/Kconfig"
2742 source "drivers/Kconfig"
2744 source "drivers/firmware/Kconfig"
2748 source "arch/x86/Kconfig.debug"
2750 source "security/Kconfig"
2752 source "crypto/Kconfig"
2754 source "arch/x86/kvm/Kconfig"
2756 source "lib/Kconfig"