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_ACPI_TABLE_UPGRADE if ACPI
26 select ARCH_HAS_DEVMEM_IS_ALLOWED
27 select ARCH_HAS_ELF_RANDOMIZE
28 select ARCH_HAS_FAST_MULTIPLIER
29 select ARCH_HAS_GCOV_PROFILE_ALL
30 select ARCH_HAS_GIGANTIC_PAGE if X86_64
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 BUILDTIME_EXTABLE_SORT
54 select CLKSRC_I8253 if X86_32
55 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
56 select CLOCKSOURCE_WATCHDOG
57 select CLONE_BACKWARDS if X86_32
58 select COMPAT_OLD_SIGACTION if IA32_EMULATION
59 select DCACHE_WORD_ACCESS
60 select EDAC_ATOMIC_SCRUB
62 select GENERIC_CLOCKEVENTS
63 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
64 select GENERIC_CLOCKEVENTS_MIN_ADJUST
65 select GENERIC_CMOS_UPDATE
66 select GENERIC_CPU_AUTOPROBE
67 select GENERIC_EARLY_IOREMAP
68 select GENERIC_FIND_FIRST_BIT
70 select GENERIC_IRQ_PROBE
71 select GENERIC_IRQ_SHOW
72 select GENERIC_PENDING_IRQ if SMP
73 select GENERIC_SMP_IDLE_THREAD
74 select GENERIC_STRNCPY_FROM_USER
75 select GENERIC_STRNLEN_USER
76 select GENERIC_TIME_VSYSCALL
77 select HAVE_ACPI_APEI if ACPI
78 select HAVE_ACPI_APEI_NMI if ACPI
79 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
80 select HAVE_AOUT if X86_32
81 select HAVE_ARCH_AUDITSYSCALL
82 select HAVE_ARCH_HARDENED_USERCOPY
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_ARCH_WITHIN_STACK_FRAMES
95 select HAVE_EBPF_JIT if X86_64
96 select HAVE_ARCH_VMAP_STACK 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_TRACER
114 select HAVE_FUNCTION_TRACER
115 select HAVE_GCC_PLUGINS
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
156 select RTC_MC146818_LIB
159 select SYSCTL_EXCEPTION_TRACE
160 select THREAD_INFO_IN_TASK
161 select USER_STACKTRACE_SUPPORT
163 select X86_DEV_DMA_OPS if X86_64
164 select X86_FEATURE_NAMES if PROC_FS
165 select HAVE_STACK_VALIDATION if X86_64
166 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
167 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
169 config INSTRUCTION_DECODER
171 depends on KPROBES || PERF_EVENTS || UPROBES
175 default "elf32-i386" if X86_32
176 default "elf64-x86-64" if X86_64
178 config ARCH_DEFCONFIG
180 default "arch/x86/configs/i386_defconfig" if X86_32
181 default "arch/x86/configs/x86_64_defconfig" if X86_64
183 config LOCKDEP_SUPPORT
186 config STACKTRACE_SUPPORT
192 config ARCH_MMAP_RND_BITS_MIN
196 config ARCH_MMAP_RND_BITS_MAX
200 config ARCH_MMAP_RND_COMPAT_BITS_MIN
203 config ARCH_MMAP_RND_COMPAT_BITS_MAX
209 config NEED_DMA_MAP_STATE
211 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
213 config NEED_SG_DMA_LENGTH
216 config GENERIC_ISA_DMA
218 depends on ISA_DMA_API
223 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
225 config GENERIC_BUG_RELATIVE_POINTERS
228 config GENERIC_HWEIGHT
231 config ARCH_MAY_HAVE_PC_FDC
233 depends on ISA_DMA_API
235 config RWSEM_XCHGADD_ALGORITHM
238 config GENERIC_CALIBRATE_DELAY
241 config ARCH_HAS_CPU_RELAX
244 config ARCH_HAS_CACHE_LINE_SIZE
247 config HAVE_SETUP_PER_CPU_AREA
250 config NEED_PER_CPU_EMBED_FIRST_CHUNK
253 config NEED_PER_CPU_PAGE_FIRST_CHUNK
256 config ARCH_HIBERNATION_POSSIBLE
259 config ARCH_SUSPEND_POSSIBLE
262 config ARCH_WANT_HUGE_PMD_SHARE
265 config ARCH_WANT_GENERAL_HUGETLB
274 config ARCH_SUPPORTS_OPTIMIZED_INLINING
277 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
280 config KASAN_SHADOW_OFFSET
283 default 0xdffffc0000000000
285 config HAVE_INTEL_TXT
287 depends on INTEL_IOMMU && ACPI
291 depends on X86_32 && SMP
295 depends on X86_64 && SMP
297 config X86_32_LAZY_GS
299 depends on X86_32 && !CC_STACKPROTECTOR
301 config ARCH_SUPPORTS_UPROBES
304 config FIX_EARLYCON_MEM
310 config PGTABLE_LEVELS
316 source "init/Kconfig"
317 source "kernel/Kconfig.freezer"
319 menu "Processor type and features"
322 bool "DMA memory allocation support" if EXPERT
325 DMA memory allocation support allows devices with less than 32-bit
326 addressing to allocate within the first 16MB of address space.
327 Disable if no such devices will be used.
332 bool "Symmetric multi-processing support"
334 This enables support for systems with more than one CPU. If you have
335 a system with only one CPU, say N. If you have a system with more
338 If you say N here, the kernel will run on uni- and multiprocessor
339 machines, but will use only one CPU of a multiprocessor machine. If
340 you say Y here, the kernel will run on many, but not all,
341 uniprocessor machines. On a uniprocessor machine, the kernel
342 will run faster if you say N here.
344 Note that if you say Y here and choose architecture "586" or
345 "Pentium" under "Processor family", the kernel will not work on 486
346 architectures. Similarly, multiprocessor kernels for the "PPro"
347 architecture may not work on all Pentium based boards.
349 People using multiprocessor machines who say Y here should also say
350 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
351 Management" code will be disabled if you say Y here.
353 See also <file:Documentation/x86/i386/IO-APIC.txt>,
354 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
355 <http://www.tldp.org/docs.html#howto>.
357 If you don't know what to do here, say N.
359 config X86_FEATURE_NAMES
360 bool "Processor feature human-readable names" if EMBEDDED
363 This option compiles in a table of x86 feature bits and corresponding
364 names. This is required to support /proc/cpuinfo and a few kernel
365 messages. You can disable this to save space, at the expense of
366 making those few kernel messages show numeric feature bits instead.
370 config X86_FAST_FEATURE_TESTS
371 bool "Fast CPU feature tests" if EMBEDDED
374 Some fast-paths in the kernel depend on the capabilities of the CPU.
375 Say Y here for the kernel to patch in the appropriate code at runtime
376 based on the capabilities of the CPU. The infrastructure for patching
377 code at runtime takes up some additional space; space-constrained
378 embedded systems may wish to say N here to produce smaller, slightly
382 bool "Support x2apic"
383 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
385 This enables x2apic support on CPUs that have this feature.
387 This allows 32-bit apic IDs (so it can support very large systems),
388 and accesses the local apic via MSRs not via mmio.
390 If you don't know what to do here, say N.
393 bool "Enable MPS table" if ACPI || SFI
395 depends on X86_LOCAL_APIC
397 For old smp systems that do not have proper acpi support. Newer systems
398 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
401 bool "Support for big SMP systems with more than 8 CPUs"
402 depends on X86_32 && SMP
404 This option is needed for the systems that have more than 8 CPUs
408 depends on X86_GOLDFISH
411 config X86_EXTENDED_PLATFORM
412 bool "Support for extended (non-PC) x86 platforms"
415 If you disable this option then the kernel will only support
416 standard PC platforms. (which covers the vast majority of
419 If you enable this option then you'll be able to select support
420 for the following (non-PC) 32 bit x86 platforms:
421 Goldfish (Android emulator)
424 SGI 320/540 (Visual Workstation)
425 STA2X11-based (e.g. Northville)
426 Moorestown MID devices
428 If you have one of these systems, or if you want to build a
429 generic distribution kernel, say Y here - otherwise say N.
433 config X86_EXTENDED_PLATFORM
434 bool "Support for extended (non-PC) x86 platforms"
437 If you disable this option then the kernel will only support
438 standard PC platforms. (which covers the vast majority of
441 If you enable this option then you'll be able to select support
442 for the following (non-PC) 64 bit x86 platforms:
447 If you have one of these systems, or if you want to build a
448 generic distribution kernel, say Y here - otherwise say N.
450 # This is an alphabetically sorted list of 64 bit extended platforms
451 # Please maintain the alphabetic order if and when there are additions
453 bool "Numascale NumaChip"
455 depends on X86_EXTENDED_PLATFORM
458 depends on X86_X2APIC
459 depends on PCI_MMCONFIG
461 Adds support for Numascale NumaChip large-SMP systems. Needed to
462 enable more than ~168 cores.
463 If you don't have one of these, you should say N here.
467 select HYPERVISOR_GUEST
469 depends on X86_64 && PCI
470 depends on X86_EXTENDED_PLATFORM
473 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
474 supposed to run on these EM64T-based machines. Only choose this option
475 if you have one of these machines.
478 bool "SGI Ultraviolet"
480 depends on X86_EXTENDED_PLATFORM
483 depends on X86_X2APIC
486 This option is needed in order to support SGI Ultraviolet systems.
487 If you don't have one of these, you should say N here.
489 # Following is an alphabetically sorted list of 32 bit extended platforms
490 # Please maintain the alphabetic order if and when there are additions
493 bool "Goldfish (Virtual Platform)"
494 depends on X86_EXTENDED_PLATFORM
496 Enable support for the Goldfish virtual platform used primarily
497 for Android development. Unless you are building for the Android
498 Goldfish emulator say N here.
501 bool "CE4100 TV platform"
503 depends on PCI_GODIRECT
504 depends on X86_IO_APIC
506 depends on X86_EXTENDED_PLATFORM
507 select X86_REBOOTFIXUPS
509 select OF_EARLY_FLATTREE
511 Select for the Intel CE media processor (CE4100) SOC.
512 This option compiles in support for the CE4100 SOC for settop
513 boxes and media devices.
516 bool "Intel MID platform support"
517 depends on X86_EXTENDED_PLATFORM
518 depends on X86_PLATFORM_DEVICES
520 depends on X86_64 || (PCI_GOANY && X86_32)
521 depends on X86_IO_APIC
527 select MFD_INTEL_MSIC
529 Select to build a kernel capable of supporting Intel MID (Mobile
530 Internet Device) platform systems which do not have the PCI legacy
531 interfaces. If you are building for a PC class system say N here.
533 Intel MID platforms are based on an Intel processor and chipset which
534 consume less power than most of the x86 derivatives.
536 config X86_INTEL_QUARK
537 bool "Intel Quark platform support"
539 depends on X86_EXTENDED_PLATFORM
540 depends on X86_PLATFORM_DEVICES
544 depends on X86_IO_APIC
549 Select to include support for Quark X1000 SoC.
550 Say Y here if you have a Quark based system such as the Arduino
551 compatible Intel Galileo.
554 tristate "Mellanox Technologies platform support"
556 depends on X86_EXTENDED_PLATFORM
558 This option enables system support for the Mellanox Technologies
561 Say Y here if you are building a kernel for Mellanox system.
565 config X86_INTEL_LPSS
566 bool "Intel Low Power Subsystem Support"
567 depends on X86 && ACPI
572 Select to build support for Intel Low Power Subsystem such as
573 found on Intel Lynxpoint PCH. Selecting this option enables
574 things like clock tree (common clock framework) and pincontrol
575 which are needed by the LPSS peripheral drivers.
577 config X86_AMD_PLATFORM_DEVICE
578 bool "AMD ACPI2Platform devices support"
583 Select to interpret AMD specific ACPI device to platform device
584 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
585 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
586 implemented under PINCTRL subsystem.
589 tristate "Intel SoC IOSF Sideband support for SoC platforms"
592 This option enables sideband register access support for Intel SoC
593 platforms. On these platforms the IOSF sideband is used in lieu of
594 MSR's for some register accesses, mostly but not limited to thermal
595 and power. Drivers may query the availability of this device to
596 determine if they need the sideband in order to work on these
597 platforms. The sideband is available on the following SoC products.
598 This list is not meant to be exclusive.
603 You should say Y if you are running a kernel on one of these SoC's.
605 config IOSF_MBI_DEBUG
606 bool "Enable IOSF sideband access through debugfs"
607 depends on IOSF_MBI && DEBUG_FS
609 Select this option to expose the IOSF sideband access registers (MCR,
610 MDR, MCRX) through debugfs to write and read register information from
611 different units on the SoC. This is most useful for obtaining device
612 state information for debug and analysis. As this is a general access
613 mechanism, users of this option would have specific knowledge of the
614 device they want to access.
616 If you don't require the option or are in doubt, say N.
619 bool "RDC R-321x SoC"
621 depends on X86_EXTENDED_PLATFORM
623 select X86_REBOOTFIXUPS
625 This option is needed for RDC R-321x system-on-chip, also known
627 If you don't have one of these chips, you should say N here.
629 config X86_32_NON_STANDARD
630 bool "Support non-standard 32-bit SMP architectures"
631 depends on X86_32 && SMP
632 depends on X86_EXTENDED_PLATFORM
634 This option compiles in the bigsmp and STA2X11 default
635 subarchitectures. It is intended for a generic binary
636 kernel. If you select them all, kernel will probe it one by
637 one and will fallback to default.
639 # Alphabetically sorted list of Non standard 32 bit platforms
641 config X86_SUPPORTS_MEMORY_FAILURE
643 # MCE code calls memory_failure():
645 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
646 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
647 depends on X86_64 || !SPARSEMEM
648 select ARCH_SUPPORTS_MEMORY_FAILURE
651 bool "STA2X11 Companion Chip Support"
652 depends on X86_32_NON_STANDARD && PCI
653 select X86_DEV_DMA_OPS
660 This adds support for boards based on the STA2X11 IO-Hub,
661 a.k.a. "ConneXt". The chip is used in place of the standard
662 PC chipset, so all "standard" peripherals are missing. If this
663 option is selected the kernel will still be able to boot on
664 standard PC machines.
667 tristate "Eurobraille/Iris poweroff module"
670 The Iris machines from EuroBraille do not have APM or ACPI support
671 to shut themselves down properly. A special I/O sequence is
672 needed to do so, which is what this module does at
675 This is only for Iris machines from EuroBraille.
679 config SCHED_OMIT_FRAME_POINTER
681 prompt "Single-depth WCHAN output"
684 Calculate simpler /proc/<PID>/wchan values. If this option
685 is disabled then wchan values will recurse back to the
686 caller function. This provides more accurate wchan values,
687 at the expense of slightly more scheduling overhead.
689 If in doubt, say "Y".
691 menuconfig HYPERVISOR_GUEST
692 bool "Linux guest support"
694 Say Y here to enable options for running Linux under various hyper-
695 visors. This option enables basic hypervisor detection and platform
698 If you say N, all options in this submenu will be skipped and
699 disabled, and Linux guest support won't be built in.
704 bool "Enable paravirtualization code"
706 This changes the kernel so it can modify itself when it is run
707 under a hypervisor, potentially improving performance significantly
708 over full virtualization. However, when run without a hypervisor
709 the kernel is theoretically slower and slightly larger.
711 config PARAVIRT_DEBUG
712 bool "paravirt-ops debugging"
713 depends on PARAVIRT && DEBUG_KERNEL
715 Enable to debug paravirt_ops internals. Specifically, BUG if
716 a paravirt_op is missing when it is called.
718 config PARAVIRT_SPINLOCKS
719 bool "Paravirtualization layer for spinlocks"
720 depends on PARAVIRT && SMP
722 Paravirtualized spinlocks allow a pvops backend to replace the
723 spinlock implementation with something virtualization-friendly
724 (for example, block the virtual CPU rather than spinning).
726 It has a minimal impact on native kernels and gives a nice performance
727 benefit on paravirtualized KVM / Xen kernels.
729 If you are unsure how to answer this question, answer Y.
731 config QUEUED_LOCK_STAT
732 bool "Paravirt queued spinlock statistics"
733 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
735 Enable the collection of statistical data on the slowpath
736 behavior of paravirtualized queued spinlocks and report
739 source "arch/x86/xen/Kconfig"
742 bool "KVM Guest support (including kvmclock)"
744 select PARAVIRT_CLOCK
747 This option enables various optimizations for running under the KVM
748 hypervisor. It includes a paravirtualized clock, so that instead
749 of relying on a PIT (or probably other) emulation by the
750 underlying device model, the host provides the guest with
751 timing infrastructure such as time of day, and system time
754 bool "Enable debug information for KVM Guests in debugfs"
755 depends on KVM_GUEST && DEBUG_FS
758 This option enables collection of various statistics for KVM guest.
759 Statistics are displayed in debugfs filesystem. Enabling this option
760 may incur significant overhead.
762 source "arch/x86/lguest/Kconfig"
764 config PARAVIRT_TIME_ACCOUNTING
765 bool "Paravirtual steal time accounting"
769 Select this option to enable fine granularity task steal time
770 accounting. Time spent executing other tasks in parallel with
771 the current vCPU is discounted from the vCPU power. To account for
772 that, there can be a small performance impact.
774 If in doubt, say N here.
776 config PARAVIRT_CLOCK
779 endif #HYPERVISOR_GUEST
784 source "arch/x86/Kconfig.cpu"
788 prompt "HPET Timer Support" if X86_32
790 Use the IA-PC HPET (High Precision Event Timer) to manage
791 time in preference to the PIT and RTC, if a HPET is
793 HPET is the next generation timer replacing legacy 8254s.
794 The HPET provides a stable time base on SMP
795 systems, unlike the TSC, but it is more expensive to access,
796 as it is off-chip. The interface used is documented
797 in the HPET spec, revision 1.
799 You can safely choose Y here. However, HPET will only be
800 activated if the platform and the BIOS support this feature.
801 Otherwise the 8254 will be used for timing services.
803 Choose N to continue using the legacy 8254 timer.
805 config HPET_EMULATE_RTC
807 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
810 def_bool y if X86_INTEL_MID
811 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
813 depends on X86_INTEL_MID && SFI
815 APB timer is the replacement for 8254, HPET on X86 MID platforms.
816 The APBT provides a stable time base on SMP
817 systems, unlike the TSC, but it is more expensive to access,
818 as it is off-chip. APB timers are always running regardless of CPU
819 C states, they are used as per CPU clockevent device when possible.
821 # Mark as expert because too many people got it wrong.
822 # The code disables itself when not needed.
825 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
826 bool "Enable DMI scanning" if EXPERT
828 Enabled scanning of DMI to identify machine quirks. Say Y
829 here unless you have verified that your setup is not
830 affected by entries in the DMI blacklist. Required by PNP
834 bool "Old AMD GART IOMMU support"
836 depends on X86_64 && PCI && AMD_NB
838 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
839 GART based hardware IOMMUs.
841 The GART supports full DMA access for devices with 32-bit access
842 limitations, on systems with more than 3 GB. This is usually needed
843 for USB, sound, many IDE/SATA chipsets and some other devices.
845 Newer systems typically have a modern AMD IOMMU, supported via
846 the CONFIG_AMD_IOMMU=y config option.
848 In normal configurations this driver is only active when needed:
849 there's more than 3 GB of memory and the system contains a
850 32-bit limited device.
855 bool "IBM Calgary IOMMU support"
857 depends on X86_64 && PCI
859 Support for hardware IOMMUs in IBM's xSeries x366 and x460
860 systems. Needed to run systems with more than 3GB of memory
861 properly with 32-bit PCI devices that do not support DAC
862 (Double Address Cycle). Calgary also supports bus level
863 isolation, where all DMAs pass through the IOMMU. This
864 prevents them from going anywhere except their intended
865 destination. This catches hard-to-find kernel bugs and
866 mis-behaving drivers and devices that do not use the DMA-API
867 properly to set up their DMA buffers. The IOMMU can be
868 turned off at boot time with the iommu=off parameter.
869 Normally the kernel will make the right choice by itself.
872 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
874 prompt "Should Calgary be enabled by default?"
875 depends on CALGARY_IOMMU
877 Should Calgary be enabled by default? if you choose 'y', Calgary
878 will be used (if it exists). If you choose 'n', Calgary will not be
879 used even if it exists. If you choose 'n' and would like to use
880 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
883 # need this always selected by IOMMU for the VIA workaround
887 Support for software bounce buffers used on x86-64 systems
888 which don't have a hardware IOMMU. Using this PCI devices
889 which can only access 32-bits of memory can be used on systems
890 with more than 3 GB of memory.
895 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
898 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
899 depends on X86_64 && SMP && DEBUG_KERNEL
900 select CPUMASK_OFFSTACK
902 Enable maximum number of CPUS and NUMA Nodes for this architecture.
906 int "Maximum number of CPUs" if SMP && !MAXSMP
907 range 2 8 if SMP && X86_32 && !X86_BIGSMP
908 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
909 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
911 default "8192" if MAXSMP
912 default "32" if SMP && X86_BIGSMP
913 default "8" if SMP && X86_32
916 This allows you to specify the maximum number of CPUs which this
917 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
918 supported value is 8192, otherwise the maximum value is 512. The
919 minimum value which makes sense is 2.
921 This is purely to save memory - each supported CPU adds
922 approximately eight kilobytes to the kernel image.
925 bool "SMT (Hyperthreading) scheduler support"
928 SMT scheduler support improves the CPU scheduler's decision making
929 when dealing with Intel Pentium 4 chips with HyperThreading at a
930 cost of slightly increased overhead in some places. If unsure say
935 prompt "Multi-core scheduler support"
938 Multi-core scheduler support improves the CPU scheduler's decision
939 making when dealing with multi-core CPU chips at a cost of slightly
940 increased overhead in some places. If unsure say N here.
943 bool "CPU core priorities scheduler support"
944 depends on SCHED_MC && CPU_SUP_INTEL
945 select X86_INTEL_PSTATE
949 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
950 core ordering determined at manufacturing time, which allows
951 certain cores to reach higher turbo frequencies (when running
952 single threaded workloads) than others.
954 Enabling this kernel feature teaches the scheduler about
955 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
956 scheduler's CPU selection logic accordingly, so that higher
957 overall system performance can be achieved.
959 This feature will have no effect on CPUs without this feature.
961 If unsure say Y here.
963 source "kernel/Kconfig.preempt"
967 depends on !SMP && X86_LOCAL_APIC
970 bool "Local APIC support on uniprocessors" if !PCI_MSI
972 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
974 A local APIC (Advanced Programmable Interrupt Controller) is an
975 integrated interrupt controller in the CPU. If you have a single-CPU
976 system which has a processor with a local APIC, you can say Y here to
977 enable and use it. If you say Y here even though your machine doesn't
978 have a local APIC, then the kernel will still run with no slowdown at
979 all. The local APIC supports CPU-generated self-interrupts (timer,
980 performance counters), and the NMI watchdog which detects hard
984 bool "IO-APIC support on uniprocessors"
985 depends on X86_UP_APIC
987 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
988 SMP-capable replacement for PC-style interrupt controllers. Most
989 SMP systems and many recent uniprocessor systems have one.
991 If you have a single-CPU system with an IO-APIC, you can say Y here
992 to use it. If you say Y here even though your machine doesn't have
993 an IO-APIC, then the kernel will still run with no slowdown at all.
995 config X86_LOCAL_APIC
997 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
998 select IRQ_DOMAIN_HIERARCHY
999 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1003 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1005 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1006 bool "Reroute for broken boot IRQs"
1007 depends on X86_IO_APIC
1009 This option enables a workaround that fixes a source of
1010 spurious interrupts. This is recommended when threaded
1011 interrupt handling is used on systems where the generation of
1012 superfluous "boot interrupts" cannot be disabled.
1014 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1015 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1016 kernel does during interrupt handling). On chipsets where this
1017 boot IRQ generation cannot be disabled, this workaround keeps
1018 the original IRQ line masked so that only the equivalent "boot
1019 IRQ" is delivered to the CPUs. The workaround also tells the
1020 kernel to set up the IRQ handler on the boot IRQ line. In this
1021 way only one interrupt is delivered to the kernel. Otherwise
1022 the spurious second interrupt may cause the kernel to bring
1023 down (vital) interrupt lines.
1025 Only affects "broken" chipsets. Interrupt sharing may be
1026 increased on these systems.
1029 bool "Machine Check / overheating reporting"
1030 select GENERIC_ALLOCATOR
1033 Machine Check support allows the processor to notify the
1034 kernel if it detects a problem (e.g. overheating, data corruption).
1035 The action the kernel takes depends on the severity of the problem,
1036 ranging from warning messages to halting the machine.
1038 config X86_MCE_INTEL
1040 prompt "Intel MCE features"
1041 depends on X86_MCE && X86_LOCAL_APIC
1043 Additional support for intel specific MCE features such as
1044 the thermal monitor.
1048 prompt "AMD MCE features"
1049 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1051 Additional support for AMD specific MCE features such as
1052 the DRAM Error Threshold.
1054 config X86_ANCIENT_MCE
1055 bool "Support for old Pentium 5 / WinChip machine checks"
1056 depends on X86_32 && X86_MCE
1058 Include support for machine check handling on old Pentium 5 or WinChip
1059 systems. These typically need to be enabled explicitly on the command
1062 config X86_MCE_THRESHOLD
1063 depends on X86_MCE_AMD || X86_MCE_INTEL
1066 config X86_MCE_INJECT
1068 tristate "Machine check injector support"
1070 Provide support for injecting machine checks for testing purposes.
1071 If you don't know what a machine check is and you don't do kernel
1072 QA it is safe to say n.
1074 config X86_THERMAL_VECTOR
1076 depends on X86_MCE_INTEL
1078 source "arch/x86/events/Kconfig"
1080 config X86_LEGACY_VM86
1081 bool "Legacy VM86 support"
1085 This option allows user programs to put the CPU into V8086
1086 mode, which is an 80286-era approximation of 16-bit real mode.
1088 Some very old versions of X and/or vbetool require this option
1089 for user mode setting. Similarly, DOSEMU will use it if
1090 available to accelerate real mode DOS programs. However, any
1091 recent version of DOSEMU, X, or vbetool should be fully
1092 functional even without kernel VM86 support, as they will all
1093 fall back to software emulation. Nevertheless, if you are using
1094 a 16-bit DOS program where 16-bit performance matters, vm86
1095 mode might be faster than emulation and you might want to
1098 Note that any app that works on a 64-bit kernel is unlikely to
1099 need this option, as 64-bit kernels don't, and can't, support
1100 V8086 mode. This option is also unrelated to 16-bit protected
1101 mode and is not needed to run most 16-bit programs under Wine.
1103 Enabling this option increases the complexity of the kernel
1104 and slows down exception handling a tiny bit.
1106 If unsure, say N here.
1110 default X86_LEGACY_VM86
1113 bool "Enable support for 16-bit segments" if EXPERT
1115 depends on MODIFY_LDT_SYSCALL
1117 This option is required by programs like Wine to run 16-bit
1118 protected mode legacy code on x86 processors. Disabling
1119 this option saves about 300 bytes on i386, or around 6K text
1120 plus 16K runtime memory on x86-64,
1124 depends on X86_16BIT && X86_32
1128 depends on X86_16BIT && X86_64
1130 config X86_VSYSCALL_EMULATION
1131 bool "Enable vsyscall emulation" if EXPERT
1135 This enables emulation of the legacy vsyscall page. Disabling
1136 it is roughly equivalent to booting with vsyscall=none, except
1137 that it will also disable the helpful warning if a program
1138 tries to use a vsyscall. With this option set to N, offending
1139 programs will just segfault, citing addresses of the form
1142 This option is required by many programs built before 2013, and
1143 care should be used even with newer programs if set to N.
1145 Disabling this option saves about 7K of kernel size and
1146 possibly 4K of additional runtime pagetable memory.
1149 tristate "Toshiba Laptop support"
1152 This adds a driver to safely access the System Management Mode of
1153 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1154 not work on models with a Phoenix BIOS. The System Management Mode
1155 is used to set the BIOS and power saving options on Toshiba portables.
1157 For information on utilities to make use of this driver see the
1158 Toshiba Linux utilities web site at:
1159 <http://www.buzzard.org.uk/toshiba/>.
1161 Say Y if you intend to run this kernel on a Toshiba portable.
1165 tristate "Dell i8k legacy laptop support"
1167 select SENSORS_DELL_SMM
1169 This option enables legacy /proc/i8k userspace interface in hwmon
1170 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1171 temperature and allows controlling fan speeds of Dell laptops via
1172 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1173 it reports also power and hotkey status. For fan speed control is
1174 needed userspace package i8kutils.
1176 Say Y if you intend to run this kernel on old Dell laptops or want to
1177 use userspace package i8kutils.
1180 config X86_REBOOTFIXUPS
1181 bool "Enable X86 board specific fixups for reboot"
1184 This enables chipset and/or board specific fixups to be done
1185 in order to get reboot to work correctly. This is only needed on
1186 some combinations of hardware and BIOS. The symptom, for which
1187 this config is intended, is when reboot ends with a stalled/hung
1190 Currently, the only fixup is for the Geode machines using
1191 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1193 Say Y if you want to enable the fixup. Currently, it's safe to
1194 enable this option even if you don't need it.
1198 bool "CPU microcode loading support"
1200 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1203 If you say Y here, you will be able to update the microcode on
1204 Intel and AMD processors. The Intel support is for the IA32 family,
1205 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1206 AMD support is for families 0x10 and later. You will obviously need
1207 the actual microcode binary data itself which is not shipped with
1210 The preferred method to load microcode from a detached initrd is described
1211 in Documentation/x86/early-microcode.txt. For that you need to enable
1212 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1213 initrd for microcode blobs.
1215 In addition, you can build-in the microcode into the kernel. For that you
1216 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1217 to the CONFIG_EXTRA_FIRMWARE config option.
1219 config MICROCODE_INTEL
1220 bool "Intel microcode loading support"
1221 depends on MICROCODE
1225 This options enables microcode patch loading support for Intel
1228 For the current Intel microcode data package go to
1229 <https://downloadcenter.intel.com> and search for
1230 'Linux Processor Microcode Data File'.
1232 config MICROCODE_AMD
1233 bool "AMD microcode loading support"
1234 depends on MICROCODE
1237 If you select this option, microcode patch loading support for AMD
1238 processors will be enabled.
1240 config MICROCODE_OLD_INTERFACE
1242 depends on MICROCODE
1245 tristate "/dev/cpu/*/msr - Model-specific register support"
1247 This device gives privileged processes access to the x86
1248 Model-Specific Registers (MSRs). It is a character device with
1249 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1250 MSR accesses are directed to a specific CPU on multi-processor
1254 tristate "/dev/cpu/*/cpuid - CPU information support"
1256 This device gives processes access to the x86 CPUID instruction to
1257 be executed on a specific processor. It is a character device
1258 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1262 prompt "High Memory Support"
1269 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1270 However, the address space of 32-bit x86 processors is only 4
1271 Gigabytes large. That means that, if you have a large amount of
1272 physical memory, not all of it can be "permanently mapped" by the
1273 kernel. The physical memory that's not permanently mapped is called
1276 If you are compiling a kernel which will never run on a machine with
1277 more than 1 Gigabyte total physical RAM, answer "off" here (default
1278 choice and suitable for most users). This will result in a "3GB/1GB"
1279 split: 3GB are mapped so that each process sees a 3GB virtual memory
1280 space and the remaining part of the 4GB virtual memory space is used
1281 by the kernel to permanently map as much physical memory as
1284 If the machine has between 1 and 4 Gigabytes physical RAM, then
1287 If more than 4 Gigabytes is used then answer "64GB" here. This
1288 selection turns Intel PAE (Physical Address Extension) mode on.
1289 PAE implements 3-level paging on IA32 processors. PAE is fully
1290 supported by Linux, PAE mode is implemented on all recent Intel
1291 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1292 then the kernel will not boot on CPUs that don't support PAE!
1294 The actual amount of total physical memory will either be
1295 auto detected or can be forced by using a kernel command line option
1296 such as "mem=256M". (Try "man bootparam" or see the documentation of
1297 your boot loader (lilo or loadlin) about how to pass options to the
1298 kernel at boot time.)
1300 If unsure, say "off".
1305 Select this if you have a 32-bit processor and between 1 and 4
1306 gigabytes of physical RAM.
1313 Select this if you have a 32-bit processor and more than 4
1314 gigabytes of physical RAM.
1319 prompt "Memory split" if EXPERT
1323 Select the desired split between kernel and user memory.
1325 If the address range available to the kernel is less than the
1326 physical memory installed, the remaining memory will be available
1327 as "high memory". Accessing high memory is a little more costly
1328 than low memory, as it needs to be mapped into the kernel first.
1329 Note that increasing the kernel address space limits the range
1330 available to user programs, making the address space there
1331 tighter. Selecting anything other than the default 3G/1G split
1332 will also likely make your kernel incompatible with binary-only
1335 If you are not absolutely sure what you are doing, leave this
1339 bool "3G/1G user/kernel split"
1340 config VMSPLIT_3G_OPT
1342 bool "3G/1G user/kernel split (for full 1G low memory)"
1344 bool "2G/2G user/kernel split"
1345 config VMSPLIT_2G_OPT
1347 bool "2G/2G user/kernel split (for full 2G low memory)"
1349 bool "1G/3G user/kernel split"
1354 default 0xB0000000 if VMSPLIT_3G_OPT
1355 default 0x80000000 if VMSPLIT_2G
1356 default 0x78000000 if VMSPLIT_2G_OPT
1357 default 0x40000000 if VMSPLIT_1G
1363 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1366 bool "PAE (Physical Address Extension) Support"
1367 depends on X86_32 && !HIGHMEM4G
1370 PAE is required for NX support, and furthermore enables
1371 larger swapspace support for non-overcommit purposes. It
1372 has the cost of more pagetable lookup overhead, and also
1373 consumes more pagetable space per process.
1375 config ARCH_PHYS_ADDR_T_64BIT
1377 depends on X86_64 || X86_PAE
1379 config ARCH_DMA_ADDR_T_64BIT
1381 depends on X86_64 || HIGHMEM64G
1383 config X86_DIRECT_GBPAGES
1385 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1387 Certain kernel features effectively disable kernel
1388 linear 1 GB mappings (even if the CPU otherwise
1389 supports them), so don't confuse the user by printing
1390 that we have them enabled.
1392 # Common NUMA Features
1394 bool "Numa Memory Allocation and Scheduler Support"
1396 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1397 default y if X86_BIGSMP
1399 Enable NUMA (Non Uniform Memory Access) support.
1401 The kernel will try to allocate memory used by a CPU on the
1402 local memory controller of the CPU and add some more
1403 NUMA awareness to the kernel.
1405 For 64-bit this is recommended if the system is Intel Core i7
1406 (or later), AMD Opteron, or EM64T NUMA.
1408 For 32-bit this is only needed if you boot a 32-bit
1409 kernel on a 64-bit NUMA platform.
1411 Otherwise, you should say N.
1415 prompt "Old style AMD Opteron NUMA detection"
1416 depends on X86_64 && NUMA && PCI
1418 Enable AMD NUMA node topology detection. You should say Y here if
1419 you have a multi processor AMD system. This uses an old method to
1420 read the NUMA configuration directly from the builtin Northbridge
1421 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1422 which also takes priority if both are compiled in.
1424 config X86_64_ACPI_NUMA
1426 prompt "ACPI NUMA detection"
1427 depends on X86_64 && NUMA && ACPI && PCI
1430 Enable ACPI SRAT based node topology detection.
1432 # Some NUMA nodes have memory ranges that span
1433 # other nodes. Even though a pfn is valid and
1434 # between a node's start and end pfns, it may not
1435 # reside on that node. See memmap_init_zone()
1437 config NODES_SPAN_OTHER_NODES
1439 depends on X86_64_ACPI_NUMA
1442 bool "NUMA emulation"
1445 Enable NUMA emulation. A flat machine will be split
1446 into virtual nodes when booted with "numa=fake=N", where N is the
1447 number of nodes. This is only useful for debugging.
1450 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1452 default "10" if MAXSMP
1453 default "6" if X86_64
1455 depends on NEED_MULTIPLE_NODES
1457 Specify the maximum number of NUMA Nodes available on the target
1458 system. Increases memory reserved to accommodate various tables.
1460 config ARCH_HAVE_MEMORY_PRESENT
1462 depends on X86_32 && DISCONTIGMEM
1464 config NEED_NODE_MEMMAP_SIZE
1466 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1468 config ARCH_FLATMEM_ENABLE
1470 depends on X86_32 && !NUMA
1472 config ARCH_DISCONTIGMEM_ENABLE
1474 depends on NUMA && X86_32
1476 config ARCH_DISCONTIGMEM_DEFAULT
1478 depends on NUMA && X86_32
1480 config ARCH_SPARSEMEM_ENABLE
1482 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1483 select SPARSEMEM_STATIC if X86_32
1484 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1486 config ARCH_SPARSEMEM_DEFAULT
1490 config ARCH_SELECT_MEMORY_MODEL
1492 depends on ARCH_SPARSEMEM_ENABLE
1494 config ARCH_MEMORY_PROBE
1495 bool "Enable sysfs memory/probe interface"
1496 depends on X86_64 && MEMORY_HOTPLUG
1498 This option enables a sysfs memory/probe interface for testing.
1499 See Documentation/memory-hotplug.txt for more information.
1500 If you are unsure how to answer this question, answer N.
1502 config ARCH_PROC_KCORE_TEXT
1504 depends on X86_64 && PROC_KCORE
1506 config ILLEGAL_POINTER_VALUE
1509 default 0xdead000000000000 if X86_64
1513 config X86_PMEM_LEGACY_DEVICE
1516 config X86_PMEM_LEGACY
1517 tristate "Support non-standard NVDIMMs and ADR protected memory"
1518 depends on PHYS_ADDR_T_64BIT
1520 select X86_PMEM_LEGACY_DEVICE
1523 Treat memory marked using the non-standard e820 type of 12 as used
1524 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1525 The kernel will offer these regions to the 'pmem' driver so
1526 they can be used for persistent storage.
1531 bool "Allocate 3rd-level pagetables from highmem"
1534 The VM uses one page table entry for each page of physical memory.
1535 For systems with a lot of RAM, this can be wasteful of precious
1536 low memory. Setting this option will put user-space page table
1537 entries in high memory.
1539 config X86_CHECK_BIOS_CORRUPTION
1540 bool "Check for low memory corruption"
1542 Periodically check for memory corruption in low memory, which
1543 is suspected to be caused by BIOS. Even when enabled in the
1544 configuration, it is disabled at runtime. Enable it by
1545 setting "memory_corruption_check=1" on the kernel command
1546 line. By default it scans the low 64k of memory every 60
1547 seconds; see the memory_corruption_check_size and
1548 memory_corruption_check_period parameters in
1549 Documentation/kernel-parameters.txt to adjust this.
1551 When enabled with the default parameters, this option has
1552 almost no overhead, as it reserves a relatively small amount
1553 of memory and scans it infrequently. It both detects corruption
1554 and prevents it from affecting the running system.
1556 It is, however, intended as a diagnostic tool; if repeatable
1557 BIOS-originated corruption always affects the same memory,
1558 you can use memmap= to prevent the kernel from using that
1561 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1562 bool "Set the default setting of memory_corruption_check"
1563 depends on X86_CHECK_BIOS_CORRUPTION
1566 Set whether the default state of memory_corruption_check is
1569 config X86_RESERVE_LOW
1570 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1574 Specify the amount of low memory to reserve for the BIOS.
1576 The first page contains BIOS data structures that the kernel
1577 must not use, so that page must always be reserved.
1579 By default we reserve the first 64K of physical RAM, as a
1580 number of BIOSes are known to corrupt that memory range
1581 during events such as suspend/resume or monitor cable
1582 insertion, so it must not be used by the kernel.
1584 You can set this to 4 if you are absolutely sure that you
1585 trust the BIOS to get all its memory reservations and usages
1586 right. If you know your BIOS have problems beyond the
1587 default 64K area, you can set this to 640 to avoid using the
1588 entire low memory range.
1590 If you have doubts about the BIOS (e.g. suspend/resume does
1591 not work or there's kernel crashes after certain hardware
1592 hotplug events) then you might want to enable
1593 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1594 typical corruption patterns.
1596 Leave this to the default value of 64 if you are unsure.
1598 config MATH_EMULATION
1600 depends on MODIFY_LDT_SYSCALL
1601 prompt "Math emulation" if X86_32
1603 Linux can emulate a math coprocessor (used for floating point
1604 operations) if you don't have one. 486DX and Pentium processors have
1605 a math coprocessor built in, 486SX and 386 do not, unless you added
1606 a 487DX or 387, respectively. (The messages during boot time can
1607 give you some hints here ["man dmesg"].) Everyone needs either a
1608 coprocessor or this emulation.
1610 If you don't have a math coprocessor, you need to say Y here; if you
1611 say Y here even though you have a coprocessor, the coprocessor will
1612 be used nevertheless. (This behavior can be changed with the kernel
1613 command line option "no387", which comes handy if your coprocessor
1614 is broken. Try "man bootparam" or see the documentation of your boot
1615 loader (lilo or loadlin) about how to pass options to the kernel at
1616 boot time.) This means that it is a good idea to say Y here if you
1617 intend to use this kernel on different machines.
1619 More information about the internals of the Linux math coprocessor
1620 emulation can be found in <file:arch/x86/math-emu/README>.
1622 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1623 kernel, it won't hurt.
1627 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1629 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1630 the Memory Type Range Registers (MTRRs) may be used to control
1631 processor access to memory ranges. This is most useful if you have
1632 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1633 allows bus write transfers to be combined into a larger transfer
1634 before bursting over the PCI/AGP bus. This can increase performance
1635 of image write operations 2.5 times or more. Saying Y here creates a
1636 /proc/mtrr file which may be used to manipulate your processor's
1637 MTRRs. Typically the X server should use this.
1639 This code has a reasonably generic interface so that similar
1640 control registers on other processors can be easily supported
1643 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1644 Registers (ARRs) which provide a similar functionality to MTRRs. For
1645 these, the ARRs are used to emulate the MTRRs.
1646 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1647 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1648 write-combining. All of these processors are supported by this code
1649 and it makes sense to say Y here if you have one of them.
1651 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1652 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1653 can lead to all sorts of problems, so it's good to say Y here.
1655 You can safely say Y even if your machine doesn't have MTRRs, you'll
1656 just add about 9 KB to your kernel.
1658 See <file:Documentation/x86/mtrr.txt> for more information.
1660 config MTRR_SANITIZER
1662 prompt "MTRR cleanup support"
1665 Convert MTRR layout from continuous to discrete, so X drivers can
1666 add writeback entries.
1668 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1669 The largest mtrr entry size for a continuous block can be set with
1674 config MTRR_SANITIZER_ENABLE_DEFAULT
1675 int "MTRR cleanup enable value (0-1)"
1678 depends on MTRR_SANITIZER
1680 Enable mtrr cleanup default value
1682 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1683 int "MTRR cleanup spare reg num (0-7)"
1686 depends on MTRR_SANITIZER
1688 mtrr cleanup spare entries default, it can be changed via
1689 mtrr_spare_reg_nr=N on the kernel command line.
1693 prompt "x86 PAT support" if EXPERT
1696 Use PAT attributes to setup page level cache control.
1698 PATs are the modern equivalents of MTRRs and are much more
1699 flexible than MTRRs.
1701 Say N here if you see bootup problems (boot crash, boot hang,
1702 spontaneous reboots) or a non-working video driver.
1706 config ARCH_USES_PG_UNCACHED
1712 prompt "x86 architectural random number generator" if EXPERT
1714 Enable the x86 architectural RDRAND instruction
1715 (Intel Bull Mountain technology) to generate random numbers.
1716 If supported, this is a high bandwidth, cryptographically
1717 secure hardware random number generator.
1721 prompt "Supervisor Mode Access Prevention" if EXPERT
1723 Supervisor Mode Access Prevention (SMAP) is a security
1724 feature in newer Intel processors. There is a small
1725 performance cost if this enabled and turned on; there is
1726 also a small increase in the kernel size if this is enabled.
1730 config X86_INTEL_MPX
1731 prompt "Intel MPX (Memory Protection Extensions)"
1733 depends on CPU_SUP_INTEL
1735 MPX provides hardware features that can be used in
1736 conjunction with compiler-instrumented code to check
1737 memory references. It is designed to detect buffer
1738 overflow or underflow bugs.
1740 This option enables running applications which are
1741 instrumented or otherwise use MPX. It does not use MPX
1742 itself inside the kernel or to protect the kernel
1743 against bad memory references.
1745 Enabling this option will make the kernel larger:
1746 ~8k of kernel text and 36 bytes of data on a 64-bit
1747 defconfig. It adds a long to the 'mm_struct' which
1748 will increase the kernel memory overhead of each
1749 process and adds some branches to paths used during
1750 exec() and munmap().
1752 For details, see Documentation/x86/intel_mpx.txt
1756 config X86_INTEL_MEMORY_PROTECTION_KEYS
1757 prompt "Intel Memory Protection Keys"
1759 # Note: only available in 64-bit mode
1760 depends on CPU_SUP_INTEL && X86_64
1762 Memory Protection Keys provides a mechanism for enforcing
1763 page-based protections, but without requiring modification of the
1764 page tables when an application changes protection domains.
1766 For details, see Documentation/x86/protection-keys.txt
1771 bool "EFI runtime service support"
1774 select EFI_RUNTIME_WRAPPERS
1776 This enables the kernel to use EFI runtime services that are
1777 available (such as the EFI variable services).
1779 This option is only useful on systems that have EFI firmware.
1780 In addition, you should use the latest ELILO loader available
1781 at <http://elilo.sourceforge.net> in order to take advantage
1782 of EFI runtime services. However, even with this option, the
1783 resultant kernel should continue to boot on existing non-EFI
1787 bool "EFI stub support"
1788 depends on EFI && !X86_USE_3DNOW
1791 This kernel feature allows a bzImage to be loaded directly
1792 by EFI firmware without the use of a bootloader.
1794 See Documentation/efi-stub.txt for more information.
1797 bool "EFI mixed-mode support"
1798 depends on EFI_STUB && X86_64
1800 Enabling this feature allows a 64-bit kernel to be booted
1801 on a 32-bit firmware, provided that your CPU supports 64-bit
1804 Note that it is not possible to boot a mixed-mode enabled
1805 kernel via the EFI boot stub - a bootloader that supports
1806 the EFI handover protocol must be used.
1812 prompt "Enable seccomp to safely compute untrusted bytecode"
1814 This kernel feature is useful for number crunching applications
1815 that may need to compute untrusted bytecode during their
1816 execution. By using pipes or other transports made available to
1817 the process as file descriptors supporting the read/write
1818 syscalls, it's possible to isolate those applications in
1819 their own address space using seccomp. Once seccomp is
1820 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1821 and the task is only allowed to execute a few safe syscalls
1822 defined by each seccomp mode.
1824 If unsure, say Y. Only embedded should say N here.
1826 source kernel/Kconfig.hz
1829 bool "kexec system call"
1832 kexec is a system call that implements the ability to shutdown your
1833 current kernel, and to start another kernel. It is like a reboot
1834 but it is independent of the system firmware. And like a reboot
1835 you can start any kernel with it, not just Linux.
1837 The name comes from the similarity to the exec system call.
1839 It is an ongoing process to be certain the hardware in a machine
1840 is properly shutdown, so do not be surprised if this code does not
1841 initially work for you. As of this writing the exact hardware
1842 interface is strongly in flux, so no good recommendation can be
1846 bool "kexec file based system call"
1851 depends on CRYPTO_SHA256=y
1853 This is new version of kexec system call. This system call is
1854 file based and takes file descriptors as system call argument
1855 for kernel and initramfs as opposed to list of segments as
1856 accepted by previous system call.
1858 config KEXEC_VERIFY_SIG
1859 bool "Verify kernel signature during kexec_file_load() syscall"
1860 depends on KEXEC_FILE
1862 This option makes kernel signature verification mandatory for
1863 the kexec_file_load() syscall.
1865 In addition to that option, you need to enable signature
1866 verification for the corresponding kernel image type being
1867 loaded in order for this to work.
1869 config KEXEC_BZIMAGE_VERIFY_SIG
1870 bool "Enable bzImage signature verification support"
1871 depends on KEXEC_VERIFY_SIG
1872 depends on SIGNED_PE_FILE_VERIFICATION
1873 select SYSTEM_TRUSTED_KEYRING
1875 Enable bzImage signature verification support.
1878 bool "kernel crash dumps"
1879 depends on X86_64 || (X86_32 && HIGHMEM)
1881 Generate crash dump after being started by kexec.
1882 This should be normally only set in special crash dump kernels
1883 which are loaded in the main kernel with kexec-tools into
1884 a specially reserved region and then later executed after
1885 a crash by kdump/kexec. The crash dump kernel must be compiled
1886 to a memory address not used by the main kernel or BIOS using
1887 PHYSICAL_START, or it must be built as a relocatable image
1888 (CONFIG_RELOCATABLE=y).
1889 For more details see Documentation/kdump/kdump.txt
1893 depends on KEXEC && HIBERNATION
1895 Jump between original kernel and kexeced kernel and invoke
1896 code in physical address mode via KEXEC
1898 config PHYSICAL_START
1899 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1902 This gives the physical address where the kernel is loaded.
1904 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1905 bzImage will decompress itself to above physical address and
1906 run from there. Otherwise, bzImage will run from the address where
1907 it has been loaded by the boot loader and will ignore above physical
1910 In normal kdump cases one does not have to set/change this option
1911 as now bzImage can be compiled as a completely relocatable image
1912 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1913 address. This option is mainly useful for the folks who don't want
1914 to use a bzImage for capturing the crash dump and want to use a
1915 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1916 to be specifically compiled to run from a specific memory area
1917 (normally a reserved region) and this option comes handy.
1919 So if you are using bzImage for capturing the crash dump,
1920 leave the value here unchanged to 0x1000000 and set
1921 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1922 for capturing the crash dump change this value to start of
1923 the reserved region. In other words, it can be set based on
1924 the "X" value as specified in the "crashkernel=YM@XM"
1925 command line boot parameter passed to the panic-ed
1926 kernel. Please take a look at Documentation/kdump/kdump.txt
1927 for more details about crash dumps.
1929 Usage of bzImage for capturing the crash dump is recommended as
1930 one does not have to build two kernels. Same kernel can be used
1931 as production kernel and capture kernel. Above option should have
1932 gone away after relocatable bzImage support is introduced. But it
1933 is present because there are users out there who continue to use
1934 vmlinux for dump capture. This option should go away down the
1937 Don't change this unless you know what you are doing.
1940 bool "Build a relocatable kernel"
1943 This builds a kernel image that retains relocation information
1944 so it can be loaded someplace besides the default 1MB.
1945 The relocations tend to make the kernel binary about 10% larger,
1946 but are discarded at runtime.
1948 One use is for the kexec on panic case where the recovery kernel
1949 must live at a different physical address than the primary
1952 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1953 it has been loaded at and the compile time physical address
1954 (CONFIG_PHYSICAL_START) is used as the minimum location.
1956 config RANDOMIZE_BASE
1957 bool "Randomize the address of the kernel image (KASLR)"
1958 depends on RELOCATABLE
1961 In support of Kernel Address Space Layout Randomization (KASLR),
1962 this randomizes the physical address at which the kernel image
1963 is decompressed and the virtual address where the kernel
1964 image is mapped, as a security feature that deters exploit
1965 attempts relying on knowledge of the location of kernel
1968 On 64-bit, the kernel physical and virtual addresses are
1969 randomized separately. The physical address will be anywhere
1970 between 16MB and the top of physical memory (up to 64TB). The
1971 virtual address will be randomized from 16MB up to 1GB (9 bits
1972 of entropy). Note that this also reduces the memory space
1973 available to kernel modules from 1.5GB to 1GB.
1975 On 32-bit, the kernel physical and virtual addresses are
1976 randomized together. They will be randomized from 16MB up to
1977 512MB (8 bits of entropy).
1979 Entropy is generated using the RDRAND instruction if it is
1980 supported. If RDTSC is supported, its value is mixed into
1981 the entropy pool as well. If neither RDRAND nor RDTSC are
1982 supported, then entropy is read from the i8254 timer. The
1983 usable entropy is limited by the kernel being built using
1984 2GB addressing, and that PHYSICAL_ALIGN must be at a
1985 minimum of 2MB. As a result, only 10 bits of entropy are
1986 theoretically possible, but the implementations are further
1987 limited due to memory layouts.
1989 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1990 time. To enable it, boot with "kaslr" on the kernel command
1991 line (which will also disable hibernation).
1995 # Relocation on x86 needs some additional build support
1996 config X86_NEED_RELOCS
1998 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2000 config PHYSICAL_ALIGN
2001 hex "Alignment value to which kernel should be aligned"
2003 range 0x2000 0x1000000 if X86_32
2004 range 0x200000 0x1000000 if X86_64
2006 This value puts the alignment restrictions on physical address
2007 where kernel is loaded and run from. Kernel is compiled for an
2008 address which meets above alignment restriction.
2010 If bootloader loads the kernel at a non-aligned address and
2011 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2012 address aligned to above value and run from there.
2014 If bootloader loads the kernel at a non-aligned address and
2015 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2016 load address and decompress itself to the address it has been
2017 compiled for and run from there. The address for which kernel is
2018 compiled already meets above alignment restrictions. Hence the
2019 end result is that kernel runs from a physical address meeting
2020 above alignment restrictions.
2022 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2023 this value must be a multiple of 0x200000.
2025 Don't change this unless you know what you are doing.
2027 config RANDOMIZE_MEMORY
2028 bool "Randomize the kernel memory sections"
2030 depends on RANDOMIZE_BASE
2031 default RANDOMIZE_BASE
2033 Randomizes the base virtual address of kernel memory sections
2034 (physical memory mapping, vmalloc & vmemmap). This security feature
2035 makes exploits relying on predictable memory locations less reliable.
2037 The order of allocations remains unchanged. Entropy is generated in
2038 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2039 configuration have in average 30,000 different possible virtual
2040 addresses for each memory section.
2044 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2045 hex "Physical memory mapping padding" if EXPERT
2046 depends on RANDOMIZE_MEMORY
2047 default "0xa" if MEMORY_HOTPLUG
2049 range 0x1 0x40 if MEMORY_HOTPLUG
2052 Define the padding in terabytes added to the existing physical
2053 memory size during kernel memory randomization. It is useful
2054 for memory hotplug support but reduces the entropy available for
2055 address randomization.
2057 If unsure, leave at the default value.
2060 bool "Support for hot-pluggable CPUs"
2063 Say Y here to allow turning CPUs off and on. CPUs can be
2064 controlled through /sys/devices/system/cpu.
2065 ( Note: power management support will enable this option
2066 automatically on SMP systems. )
2067 Say N if you want to disable CPU hotplug.
2069 config BOOTPARAM_HOTPLUG_CPU0
2070 bool "Set default setting of cpu0_hotpluggable"
2072 depends on HOTPLUG_CPU
2074 Set whether default state of cpu0_hotpluggable is on or off.
2076 Say Y here to enable CPU0 hotplug by default. If this switch
2077 is turned on, there is no need to give cpu0_hotplug kernel
2078 parameter and the CPU0 hotplug feature is enabled by default.
2080 Please note: there are two known CPU0 dependencies if you want
2081 to enable the CPU0 hotplug feature either by this switch or by
2082 cpu0_hotplug kernel parameter.
2084 First, resume from hibernate or suspend always starts from CPU0.
2085 So hibernate and suspend are prevented if CPU0 is offline.
2087 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2088 offline if any interrupt can not migrate out of CPU0. There may
2089 be other CPU0 dependencies.
2091 Please make sure the dependencies are under your control before
2092 you enable this feature.
2094 Say N if you don't want to enable CPU0 hotplug feature by default.
2095 You still can enable the CPU0 hotplug feature at boot by kernel
2096 parameter cpu0_hotplug.
2098 config DEBUG_HOTPLUG_CPU0
2100 prompt "Debug CPU0 hotplug"
2101 depends on HOTPLUG_CPU
2103 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2104 soon as possible and boots up userspace with CPU0 offlined. User
2105 can online CPU0 back after boot time.
2107 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2108 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2109 compilation or giving cpu0_hotplug kernel parameter at boot.
2115 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2116 depends on X86_32 || IA32_EMULATION
2118 Certain buggy versions of glibc will crash if they are
2119 presented with a 32-bit vDSO that is not mapped at the address
2120 indicated in its segment table.
2122 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2123 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2124 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2125 the only released version with the bug, but OpenSUSE 9
2126 contains a buggy "glibc 2.3.2".
2128 The symptom of the bug is that everything crashes on startup, saying:
2129 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2131 Saying Y here changes the default value of the vdso32 boot
2132 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2133 This works around the glibc bug but hurts performance.
2135 If unsure, say N: if you are compiling your own kernel, you
2136 are unlikely to be using a buggy version of glibc.
2139 prompt "vsyscall table for legacy applications"
2141 default LEGACY_VSYSCALL_EMULATE
2143 Legacy user code that does not know how to find the vDSO expects
2144 to be able to issue three syscalls by calling fixed addresses in
2145 kernel space. Since this location is not randomized with ASLR,
2146 it can be used to assist security vulnerability exploitation.
2148 This setting can be changed at boot time via the kernel command
2149 line parameter vsyscall=[native|emulate|none].
2151 On a system with recent enough glibc (2.14 or newer) and no
2152 static binaries, you can say None without a performance penalty
2153 to improve security.
2155 If unsure, select "Emulate".
2157 config LEGACY_VSYSCALL_NATIVE
2160 Actual executable code is located in the fixed vsyscall
2161 address mapping, implementing time() efficiently. Since
2162 this makes the mapping executable, it can be used during
2163 security vulnerability exploitation (traditionally as
2164 ROP gadgets). This configuration is not recommended.
2166 config LEGACY_VSYSCALL_EMULATE
2169 The kernel traps and emulates calls into the fixed
2170 vsyscall address mapping. This makes the mapping
2171 non-executable, but it still contains known contents,
2172 which could be used in certain rare security vulnerability
2173 exploits. This configuration is recommended when userspace
2174 still uses the vsyscall area.
2176 config LEGACY_VSYSCALL_NONE
2179 There will be no vsyscall mapping at all. This will
2180 eliminate any risk of ASLR bypass due to the vsyscall
2181 fixed address mapping. Attempts to use the vsyscalls
2182 will be reported to dmesg, so that either old or
2183 malicious userspace programs can be identified.
2188 bool "Built-in kernel command line"
2190 Allow for specifying boot arguments to the kernel at
2191 build time. On some systems (e.g. embedded ones), it is
2192 necessary or convenient to provide some or all of the
2193 kernel boot arguments with the kernel itself (that is,
2194 to not rely on the boot loader to provide them.)
2196 To compile command line arguments into the kernel,
2197 set this option to 'Y', then fill in the
2198 boot arguments in CONFIG_CMDLINE.
2200 Systems with fully functional boot loaders (i.e. non-embedded)
2201 should leave this option set to 'N'.
2204 string "Built-in kernel command string"
2205 depends on CMDLINE_BOOL
2208 Enter arguments here that should be compiled into the kernel
2209 image and used at boot time. If the boot loader provides a
2210 command line at boot time, it is appended to this string to
2211 form the full kernel command line, when the system boots.
2213 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2214 change this behavior.
2216 In most cases, the command line (whether built-in or provided
2217 by the boot loader) should specify the device for the root
2220 config CMDLINE_OVERRIDE
2221 bool "Built-in command line overrides boot loader arguments"
2222 depends on CMDLINE_BOOL
2224 Set this option to 'Y' to have the kernel ignore the boot loader
2225 command line, and use ONLY the built-in command line.
2227 This is used to work around broken boot loaders. This should
2228 be set to 'N' under normal conditions.
2230 config MODIFY_LDT_SYSCALL
2231 bool "Enable the LDT (local descriptor table)" if EXPERT
2234 Linux can allow user programs to install a per-process x86
2235 Local Descriptor Table (LDT) using the modify_ldt(2) system
2236 call. This is required to run 16-bit or segmented code such as
2237 DOSEMU or some Wine programs. It is also used by some very old
2238 threading libraries.
2240 Enabling this feature adds a small amount of overhead to
2241 context switches and increases the low-level kernel attack
2242 surface. Disabling it removes the modify_ldt(2) system call.
2244 Saying 'N' here may make sense for embedded or server kernels.
2246 source "kernel/livepatch/Kconfig"
2250 config ARCH_ENABLE_MEMORY_HOTPLUG
2252 depends on X86_64 || (X86_32 && HIGHMEM)
2254 config ARCH_ENABLE_MEMORY_HOTREMOVE
2256 depends on MEMORY_HOTPLUG
2258 config USE_PERCPU_NUMA_NODE_ID
2262 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2264 depends on X86_64 || X86_PAE
2266 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2268 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2270 menu "Power management and ACPI options"
2272 config ARCH_HIBERNATION_HEADER
2274 depends on X86_64 && HIBERNATION
2276 source "kernel/power/Kconfig"
2278 source "drivers/acpi/Kconfig"
2280 source "drivers/sfi/Kconfig"
2287 tristate "APM (Advanced Power Management) BIOS support"
2288 depends on X86_32 && PM_SLEEP
2290 APM is a BIOS specification for saving power using several different
2291 techniques. This is mostly useful for battery powered laptops with
2292 APM compliant BIOSes. If you say Y here, the system time will be
2293 reset after a RESUME operation, the /proc/apm device will provide
2294 battery status information, and user-space programs will receive
2295 notification of APM "events" (e.g. battery status change).
2297 If you select "Y" here, you can disable actual use of the APM
2298 BIOS by passing the "apm=off" option to the kernel at boot time.
2300 Note that the APM support is almost completely disabled for
2301 machines with more than one CPU.
2303 In order to use APM, you will need supporting software. For location
2304 and more information, read <file:Documentation/power/apm-acpi.txt>
2305 and the Battery Powered Linux mini-HOWTO, available from
2306 <http://www.tldp.org/docs.html#howto>.
2308 This driver does not spin down disk drives (see the hdparm(8)
2309 manpage ("man 8 hdparm") for that), and it doesn't turn off
2310 VESA-compliant "green" monitors.
2312 This driver does not support the TI 4000M TravelMate and the ACER
2313 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2314 desktop machines also don't have compliant BIOSes, and this driver
2315 may cause those machines to panic during the boot phase.
2317 Generally, if you don't have a battery in your machine, there isn't
2318 much point in using this driver and you should say N. If you get
2319 random kernel OOPSes or reboots that don't seem to be related to
2320 anything, try disabling/enabling this option (or disabling/enabling
2323 Some other things you should try when experiencing seemingly random,
2326 1) make sure that you have enough swap space and that it is
2328 2) pass the "no-hlt" option to the kernel
2329 3) switch on floating point emulation in the kernel and pass
2330 the "no387" option to the kernel
2331 4) pass the "floppy=nodma" option to the kernel
2332 5) pass the "mem=4M" option to the kernel (thereby disabling
2333 all but the first 4 MB of RAM)
2334 6) make sure that the CPU is not over clocked.
2335 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2336 8) disable the cache from your BIOS settings
2337 9) install a fan for the video card or exchange video RAM
2338 10) install a better fan for the CPU
2339 11) exchange RAM chips
2340 12) exchange the motherboard.
2342 To compile this driver as a module, choose M here: the
2343 module will be called apm.
2347 config APM_IGNORE_USER_SUSPEND
2348 bool "Ignore USER SUSPEND"
2350 This option will ignore USER SUSPEND requests. On machines with a
2351 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2352 series notebooks, it is necessary to say Y because of a BIOS bug.
2354 config APM_DO_ENABLE
2355 bool "Enable PM at boot time"
2357 Enable APM features at boot time. From page 36 of the APM BIOS
2358 specification: "When disabled, the APM BIOS does not automatically
2359 power manage devices, enter the Standby State, enter the Suspend
2360 State, or take power saving steps in response to CPU Idle calls."
2361 This driver will make CPU Idle calls when Linux is idle (unless this
2362 feature is turned off -- see "Do CPU IDLE calls", below). This
2363 should always save battery power, but more complicated APM features
2364 will be dependent on your BIOS implementation. You may need to turn
2365 this option off if your computer hangs at boot time when using APM
2366 support, or if it beeps continuously instead of suspending. Turn
2367 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2368 T400CDT. This is off by default since most machines do fine without
2373 bool "Make CPU Idle calls when idle"
2375 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2376 On some machines, this can activate improved power savings, such as
2377 a slowed CPU clock rate, when the machine is idle. These idle calls
2378 are made after the idle loop has run for some length of time (e.g.,
2379 333 mS). On some machines, this will cause a hang at boot time or
2380 whenever the CPU becomes idle. (On machines with more than one CPU,
2381 this option does nothing.)
2383 config APM_DISPLAY_BLANK
2384 bool "Enable console blanking using APM"
2386 Enable console blanking using the APM. Some laptops can use this to
2387 turn off the LCD backlight when the screen blanker of the Linux
2388 virtual console blanks the screen. Note that this is only used by
2389 the virtual console screen blanker, and won't turn off the backlight
2390 when using the X Window system. This also doesn't have anything to
2391 do with your VESA-compliant power-saving monitor. Further, this
2392 option doesn't work for all laptops -- it might not turn off your
2393 backlight at all, or it might print a lot of errors to the console,
2394 especially if you are using gpm.
2396 config APM_ALLOW_INTS
2397 bool "Allow interrupts during APM BIOS calls"
2399 Normally we disable external interrupts while we are making calls to
2400 the APM BIOS as a measure to lessen the effects of a badly behaving
2401 BIOS implementation. The BIOS should reenable interrupts if it
2402 needs to. Unfortunately, some BIOSes do not -- especially those in
2403 many of the newer IBM Thinkpads. If you experience hangs when you
2404 suspend, try setting this to Y. Otherwise, say N.
2408 source "drivers/cpufreq/Kconfig"
2410 source "drivers/cpuidle/Kconfig"
2412 source "drivers/idle/Kconfig"
2417 menu "Bus options (PCI etc.)"
2423 Find out whether you have a PCI motherboard. PCI is the name of a
2424 bus system, i.e. the way the CPU talks to the other stuff inside
2425 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2426 VESA. If you have PCI, say Y, otherwise N.
2429 prompt "PCI access mode"
2430 depends on X86_32 && PCI
2433 On PCI systems, the BIOS can be used to detect the PCI devices and
2434 determine their configuration. However, some old PCI motherboards
2435 have BIOS bugs and may crash if this is done. Also, some embedded
2436 PCI-based systems don't have any BIOS at all. Linux can also try to
2437 detect the PCI hardware directly without using the BIOS.
2439 With this option, you can specify how Linux should detect the
2440 PCI devices. If you choose "BIOS", the BIOS will be used,
2441 if you choose "Direct", the BIOS won't be used, and if you
2442 choose "MMConfig", then PCI Express MMCONFIG will be used.
2443 If you choose "Any", the kernel will try MMCONFIG, then the
2444 direct access method and falls back to the BIOS if that doesn't
2445 work. If unsure, go with the default, which is "Any".
2450 config PCI_GOMMCONFIG
2467 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2469 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2472 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2476 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2480 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2484 depends on PCI && XEN
2492 bool "Support mmconfig PCI config space access"
2493 depends on X86_64 && PCI && ACPI
2495 config PCI_CNB20LE_QUIRK
2496 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2499 Read the PCI windows out of the CNB20LE host bridge. This allows
2500 PCI hotplug to work on systems with the CNB20LE chipset which do
2503 There's no public spec for this chipset, and this functionality
2504 is known to be incomplete.
2506 You should say N unless you know you need this.
2508 source "drivers/pci/Kconfig"
2511 bool "ISA-style bus support on modern systems" if EXPERT
2514 Enables ISA-style drivers on modern systems. This is necessary to
2515 support PC/104 devices on X86_64 platforms.
2519 # x86_64 have no ISA slots, but can have ISA-style DMA.
2521 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2524 Enables ISA-style DMA support for devices requiring such controllers.
2532 Find out whether you have ISA slots on your motherboard. ISA is the
2533 name of a bus system, i.e. the way the CPU talks to the other stuff
2534 inside your box. Other bus systems are PCI, EISA, MicroChannel
2535 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2536 newer boards don't support it. If you have ISA, say Y, otherwise N.
2542 The Extended Industry Standard Architecture (EISA) bus was
2543 developed as an open alternative to the IBM MicroChannel bus.
2545 The EISA bus provided some of the features of the IBM MicroChannel
2546 bus while maintaining backward compatibility with cards made for
2547 the older ISA bus. The EISA bus saw limited use between 1988 and
2548 1995 when it was made obsolete by the PCI bus.
2550 Say Y here if you are building a kernel for an EISA-based machine.
2554 source "drivers/eisa/Kconfig"
2557 tristate "NatSemi SCx200 support"
2559 This provides basic support for National Semiconductor's
2560 (now AMD's) Geode processors. The driver probes for the
2561 PCI-IDs of several on-chip devices, so its a good dependency
2562 for other scx200_* drivers.
2564 If compiled as a module, the driver is named scx200.
2566 config SCx200HR_TIMER
2567 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2571 This driver provides a clocksource built upon the on-chip
2572 27MHz high-resolution timer. Its also a workaround for
2573 NSC Geode SC-1100's buggy TSC, which loses time when the
2574 processor goes idle (as is done by the scheduler). The
2575 other workaround is idle=poll boot option.
2578 bool "One Laptop Per Child support"
2585 Add support for detecting the unique features of the OLPC
2589 bool "OLPC XO-1 Power Management"
2590 depends on OLPC && MFD_CS5535 && PM_SLEEP
2593 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2596 bool "OLPC XO-1 Real Time Clock"
2597 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2599 Add support for the XO-1 real time clock, which can be used as a
2600 programmable wakeup source.
2603 bool "OLPC XO-1 SCI extras"
2604 depends on OLPC && OLPC_XO1_PM
2610 Add support for SCI-based features of the OLPC XO-1 laptop:
2611 - EC-driven system wakeups
2615 - AC adapter status updates
2616 - Battery status updates
2618 config OLPC_XO15_SCI
2619 bool "OLPC XO-1.5 SCI extras"
2620 depends on OLPC && ACPI
2623 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2624 - EC-driven system wakeups
2625 - AC adapter status updates
2626 - Battery status updates
2629 bool "PCEngines ALIX System Support (LED setup)"
2632 This option enables system support for the PCEngines ALIX.
2633 At present this just sets up LEDs for GPIO control on
2634 ALIX2/3/6 boards. However, other system specific setup should
2637 Note: You must still enable the drivers for GPIO and LED support
2638 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2640 Note: You have to set alix.force=1 for boards with Award BIOS.
2643 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2646 This option enables system support for the Soekris Engineering net5501.
2649 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2653 This option enables system support for the Traverse Technologies GEOS.
2656 bool "Technologic Systems TS-5500 platform support"
2658 select CHECK_SIGNATURE
2662 This option enables system support for the Technologic Systems TS-5500.
2668 depends on CPU_SUP_AMD && PCI
2670 source "drivers/pcmcia/Kconfig"
2673 tristate "RapidIO support"
2677 If enabled this option will include drivers and the core
2678 infrastructure code to support RapidIO interconnect devices.
2680 source "drivers/rapidio/Kconfig"
2683 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2685 Firmwares often provide initial graphics framebuffers so the BIOS,
2686 bootloader or kernel can show basic video-output during boot for
2687 user-guidance and debugging. Historically, x86 used the VESA BIOS
2688 Extensions and EFI-framebuffers for this, which are mostly limited
2690 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2691 framebuffers so the new generic system-framebuffer drivers can be
2692 used on x86. If the framebuffer is not compatible with the generic
2693 modes, it is adverticed as fallback platform framebuffer so legacy
2694 drivers like efifb, vesafb and uvesafb can pick it up.
2695 If this option is not selected, all system framebuffers are always
2696 marked as fallback platform framebuffers as usual.
2698 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2699 not be able to pick up generic system framebuffers if this option
2700 is selected. You are highly encouraged to enable simplefb as
2701 replacement if you select this option. simplefb can correctly deal
2702 with generic system framebuffers. But you should still keep vesafb
2703 and others enabled as fallback if a system framebuffer is
2704 incompatible with simplefb.
2711 menu "Executable file formats / Emulations"
2713 source "fs/Kconfig.binfmt"
2715 config IA32_EMULATION
2716 bool "IA32 Emulation"
2719 select COMPAT_BINFMT_ELF
2720 select ARCH_WANT_OLD_COMPAT_IPC
2722 Include code to run legacy 32-bit programs under a
2723 64-bit kernel. You should likely turn this on, unless you're
2724 100% sure that you don't have any 32-bit programs left.
2727 tristate "IA32 a.out support"
2728 depends on IA32_EMULATION
2730 Support old a.out binaries in the 32bit emulation.
2733 bool "x32 ABI for 64-bit mode"
2736 Include code to run binaries for the x32 native 32-bit ABI
2737 for 64-bit processors. An x32 process gets access to the
2738 full 64-bit register file and wide data path while leaving
2739 pointers at 32 bits for smaller memory footprint.
2741 You will need a recent binutils (2.22 or later) with
2742 elf32_x86_64 support enabled to compile a kernel with this
2747 depends on IA32_EMULATION || X86_X32
2750 config COMPAT_FOR_U64_ALIGNMENT
2753 config SYSVIPC_COMPAT
2765 config HAVE_ATOMIC_IOMAP
2769 config X86_DEV_DMA_OPS
2771 depends on X86_64 || STA2X11
2773 config X86_DMA_REMAP
2781 source "net/Kconfig"
2783 source "drivers/Kconfig"
2785 source "drivers/firmware/Kconfig"
2789 source "arch/x86/Kconfig.debug"
2791 source "security/Kconfig"
2793 source "crypto/Kconfig"
2795 source "arch/x86/kvm/Kconfig"
2797 source "lib/Kconfig"
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