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
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_CPU_VULNERABILITIES
68 select GENERIC_EARLY_IOREMAP
69 select GENERIC_FIND_FIRST_BIT
71 select GENERIC_IRQ_PROBE
72 select GENERIC_IRQ_SHOW
73 select GENERIC_PENDING_IRQ if SMP
74 select GENERIC_SMP_IDLE_THREAD
75 select GENERIC_STRNCPY_FROM_USER
76 select GENERIC_STRNLEN_USER
77 select GENERIC_TIME_VSYSCALL
78 select HAVE_ACPI_APEI if ACPI
79 select HAVE_ACPI_APEI_NMI if ACPI
80 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
81 select HAVE_AOUT if X86_32
82 select HAVE_ARCH_AUDITSYSCALL
83 select HAVE_ARCH_HARDENED_USERCOPY
84 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
85 select HAVE_ARCH_JUMP_LABEL
86 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
88 select HAVE_ARCH_KMEMCHECK
89 select HAVE_ARCH_MMAP_RND_BITS if MMU
90 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
91 select HAVE_ARCH_SECCOMP_FILTER
92 select HAVE_ARCH_SOFT_DIRTY if X86_64
93 select HAVE_ARCH_TRACEHOOK
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
95 select HAVE_ARCH_WITHIN_STACK_FRAMES
96 select HAVE_EBPF_JIT if X86_64
97 select HAVE_ARCH_VMAP_STACK if X86_64
98 select HAVE_CC_STACKPROTECTOR
99 select HAVE_CMPXCHG_DOUBLE
100 select HAVE_CMPXCHG_LOCAL
101 select HAVE_CONTEXT_TRACKING if X86_64
102 select HAVE_COPY_THREAD_TLS
103 select HAVE_C_RECORDMCOUNT
104 select HAVE_DEBUG_KMEMLEAK
105 select HAVE_DEBUG_STACKOVERFLOW
106 select HAVE_DMA_API_DEBUG
107 select HAVE_DMA_CONTIGUOUS
108 select HAVE_DYNAMIC_FTRACE
109 select HAVE_DYNAMIC_FTRACE_WITH_REGS
110 select HAVE_EFFICIENT_UNALIGNED_ACCESS
111 select HAVE_EXIT_THREAD
112 select HAVE_FENTRY if X86_64
113 select HAVE_FTRACE_MCOUNT_RECORD
114 select HAVE_FUNCTION_GRAPH_TRACER
115 select HAVE_FUNCTION_TRACER
116 select HAVE_GCC_PLUGINS
117 select HAVE_GENERIC_DMA_COHERENT if X86_32
118 select HAVE_HW_BREAKPOINT
120 select HAVE_IOREMAP_PROT
121 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
122 select HAVE_IRQ_TIME_ACCOUNTING
123 select HAVE_KERNEL_BZIP2
124 select HAVE_KERNEL_GZIP
125 select HAVE_KERNEL_LZ4
126 select HAVE_KERNEL_LZMA
127 select HAVE_KERNEL_LZO
128 select HAVE_KERNEL_XZ
130 select HAVE_KPROBES_ON_FTRACE
131 select HAVE_KRETPROBES
133 select HAVE_LIVEPATCH if X86_64
135 select HAVE_MEMBLOCK_NODE_MAP
136 select HAVE_MIXED_BREAKPOINTS_REGS
139 select HAVE_OPTPROBES
140 select HAVE_PCSPKR_PLATFORM
141 select HAVE_PERF_EVENTS
142 select HAVE_PERF_EVENTS_NMI
143 select HAVE_PERF_REGS
144 select HAVE_PERF_USER_STACK_DUMP
145 select HAVE_REGS_AND_STACK_ACCESS_API
146 select HAVE_SYSCALL_TRACEPOINTS
147 select HAVE_UID16 if X86_32 || IA32_EMULATION
148 select HAVE_UNSTABLE_SCHED_CLOCK
149 select HAVE_USER_RETURN_NOTIFIER
150 select IRQ_FORCED_THREADING
151 select MODULES_USE_ELF_RELA if X86_64
152 select MODULES_USE_ELF_REL if X86_32
153 select OLD_SIGACTION if X86_32
154 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
157 select RTC_MC146818_LIB
160 select SYSCTL_EXCEPTION_TRACE
161 select THREAD_INFO_IN_TASK
162 select USER_STACKTRACE_SUPPORT
164 select X86_DEV_DMA_OPS if X86_64
165 select X86_FEATURE_NAMES if PROC_FS
166 select HAVE_STACK_VALIDATION if X86_64
167 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
168 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
170 config INSTRUCTION_DECODER
172 depends on KPROBES || PERF_EVENTS || UPROBES
176 default "elf32-i386" if X86_32
177 default "elf64-x86-64" if X86_64
179 config ARCH_DEFCONFIG
181 default "arch/x86/configs/i386_defconfig" if X86_32
182 default "arch/x86/configs/x86_64_defconfig" if X86_64
184 config LOCKDEP_SUPPORT
187 config STACKTRACE_SUPPORT
193 config ARCH_MMAP_RND_BITS_MIN
197 config ARCH_MMAP_RND_BITS_MAX
201 config ARCH_MMAP_RND_COMPAT_BITS_MIN
204 config ARCH_MMAP_RND_COMPAT_BITS_MAX
210 config NEED_DMA_MAP_STATE
212 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
214 config NEED_SG_DMA_LENGTH
217 config GENERIC_ISA_DMA
219 depends on ISA_DMA_API
224 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
226 config GENERIC_BUG_RELATIVE_POINTERS
229 config GENERIC_HWEIGHT
232 config ARCH_MAY_HAVE_PC_FDC
234 depends on ISA_DMA_API
236 config RWSEM_XCHGADD_ALGORITHM
239 config GENERIC_CALIBRATE_DELAY
242 config ARCH_HAS_CPU_RELAX
245 config ARCH_HAS_CACHE_LINE_SIZE
248 config HAVE_SETUP_PER_CPU_AREA
251 config NEED_PER_CPU_EMBED_FIRST_CHUNK
254 config NEED_PER_CPU_PAGE_FIRST_CHUNK
257 config ARCH_HIBERNATION_POSSIBLE
260 config ARCH_SUSPEND_POSSIBLE
263 config ARCH_WANT_HUGE_PMD_SHARE
266 config ARCH_WANT_GENERAL_HUGETLB
275 config ARCH_SUPPORTS_OPTIMIZED_INLINING
278 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
281 config KASAN_SHADOW_OFFSET
284 default 0xdffffc0000000000
286 config HAVE_INTEL_TXT
288 depends on INTEL_IOMMU && ACPI
292 depends on X86_32 && SMP
296 depends on X86_64 && SMP
298 config X86_32_LAZY_GS
300 depends on X86_32 && !CC_STACKPROTECTOR
302 config ARCH_SUPPORTS_UPROBES
305 config FIX_EARLYCON_MEM
311 config PGTABLE_LEVELS
317 source "init/Kconfig"
318 source "kernel/Kconfig.freezer"
320 menu "Processor type and features"
323 bool "DMA memory allocation support" if EXPERT
326 DMA memory allocation support allows devices with less than 32-bit
327 addressing to allocate within the first 16MB of address space.
328 Disable if no such devices will be used.
333 bool "Symmetric multi-processing support"
335 This enables support for systems with more than one CPU. If you have
336 a system with only one CPU, say N. If you have a system with more
339 If you say N here, the kernel will run on uni- and multiprocessor
340 machines, but will use only one CPU of a multiprocessor machine. If
341 you say Y here, the kernel will run on many, but not all,
342 uniprocessor machines. On a uniprocessor machine, the kernel
343 will run faster if you say N here.
345 Note that if you say Y here and choose architecture "586" or
346 "Pentium" under "Processor family", the kernel will not work on 486
347 architectures. Similarly, multiprocessor kernels for the "PPro"
348 architecture may not work on all Pentium based boards.
350 People using multiprocessor machines who say Y here should also say
351 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
352 Management" code will be disabled if you say Y here.
354 See also <file:Documentation/x86/i386/IO-APIC.txt>,
355 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
356 <http://www.tldp.org/docs.html#howto>.
358 If you don't know what to do here, say N.
360 config X86_FEATURE_NAMES
361 bool "Processor feature human-readable names" if EMBEDDED
364 This option compiles in a table of x86 feature bits and corresponding
365 names. This is required to support /proc/cpuinfo and a few kernel
366 messages. You can disable this to save space, at the expense of
367 making those few kernel messages show numeric feature bits instead.
371 config X86_FAST_FEATURE_TESTS
372 bool "Fast CPU feature tests" if EMBEDDED
375 Some fast-paths in the kernel depend on the capabilities of the CPU.
376 Say Y here for the kernel to patch in the appropriate code at runtime
377 based on the capabilities of the CPU. The infrastructure for patching
378 code at runtime takes up some additional space; space-constrained
379 embedded systems may wish to say N here to produce smaller, slightly
383 bool "Support x2apic"
384 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
386 This enables x2apic support on CPUs that have this feature.
388 This allows 32-bit apic IDs (so it can support very large systems),
389 and accesses the local apic via MSRs not via mmio.
391 If you don't know what to do here, say N.
394 bool "Enable MPS table" if ACPI || SFI
396 depends on X86_LOCAL_APIC
398 For old smp systems that do not have proper acpi support. Newer systems
399 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
402 bool "Support for big SMP systems with more than 8 CPUs"
403 depends on X86_32 && SMP
405 This option is needed for the systems that have more than 8 CPUs
409 depends on X86_GOLDFISH
412 bool "Avoid speculative indirect branches in kernel"
415 Compile kernel with the retpoline compiler options to guard against
416 kernel-to-user data leaks by avoiding speculative indirect
417 branches. Requires a compiler with -mindirect-branch=thunk-extern
418 support for full protection. The kernel may run slower.
420 Without compiler support, at least indirect branches in assembler
421 code are eliminated. Since this includes the syscall entry path,
422 it is not entirely pointless.
425 config X86_EXTENDED_PLATFORM
426 bool "Support for extended (non-PC) x86 platforms"
429 If you disable this option then the kernel will only support
430 standard PC platforms. (which covers the vast majority of
433 If you enable this option then you'll be able to select support
434 for the following (non-PC) 32 bit x86 platforms:
435 Goldfish (Android emulator)
438 SGI 320/540 (Visual Workstation)
439 STA2X11-based (e.g. Northville)
440 Moorestown MID devices
442 If you have one of these systems, or if you want to build a
443 generic distribution kernel, say Y here - otherwise say N.
447 config X86_EXTENDED_PLATFORM
448 bool "Support for extended (non-PC) x86 platforms"
451 If you disable this option then the kernel will only support
452 standard PC platforms. (which covers the vast majority of
455 If you enable this option then you'll be able to select support
456 for the following (non-PC) 64 bit x86 platforms:
461 If you have one of these systems, or if you want to build a
462 generic distribution kernel, say Y here - otherwise say N.
464 # This is an alphabetically sorted list of 64 bit extended platforms
465 # Please maintain the alphabetic order if and when there are additions
467 bool "Numascale NumaChip"
469 depends on X86_EXTENDED_PLATFORM
472 depends on X86_X2APIC
473 depends on PCI_MMCONFIG
475 Adds support for Numascale NumaChip large-SMP systems. Needed to
476 enable more than ~168 cores.
477 If you don't have one of these, you should say N here.
481 select HYPERVISOR_GUEST
483 depends on X86_64 && PCI
484 depends on X86_EXTENDED_PLATFORM
487 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
488 supposed to run on these EM64T-based machines. Only choose this option
489 if you have one of these machines.
492 bool "SGI Ultraviolet"
494 depends on X86_EXTENDED_PLATFORM
497 depends on X86_X2APIC
500 This option is needed in order to support SGI Ultraviolet systems.
501 If you don't have one of these, you should say N here.
503 # Following is an alphabetically sorted list of 32 bit extended platforms
504 # Please maintain the alphabetic order if and when there are additions
507 bool "Goldfish (Virtual Platform)"
508 depends on X86_EXTENDED_PLATFORM
510 Enable support for the Goldfish virtual platform used primarily
511 for Android development. Unless you are building for the Android
512 Goldfish emulator say N here.
515 bool "CE4100 TV platform"
517 depends on PCI_GODIRECT
518 depends on X86_IO_APIC
520 depends on X86_EXTENDED_PLATFORM
521 select X86_REBOOTFIXUPS
523 select OF_EARLY_FLATTREE
525 Select for the Intel CE media processor (CE4100) SOC.
526 This option compiles in support for the CE4100 SOC for settop
527 boxes and media devices.
530 bool "Intel MID platform support"
531 depends on X86_EXTENDED_PLATFORM
532 depends on X86_PLATFORM_DEVICES
534 depends on X86_64 || (PCI_GOANY && X86_32)
535 depends on X86_IO_APIC
541 select MFD_INTEL_MSIC
543 Select to build a kernel capable of supporting Intel MID (Mobile
544 Internet Device) platform systems which do not have the PCI legacy
545 interfaces. If you are building for a PC class system say N here.
547 Intel MID platforms are based on an Intel processor and chipset which
548 consume less power than most of the x86 derivatives.
550 config X86_INTEL_QUARK
551 bool "Intel Quark platform support"
553 depends on X86_EXTENDED_PLATFORM
554 depends on X86_PLATFORM_DEVICES
558 depends on X86_IO_APIC
563 Select to include support for Quark X1000 SoC.
564 Say Y here if you have a Quark based system such as the Arduino
565 compatible Intel Galileo.
568 tristate "Mellanox Technologies platform support"
570 depends on X86_EXTENDED_PLATFORM
572 This option enables system support for the Mellanox Technologies
575 Say Y here if you are building a kernel for Mellanox system.
579 config X86_INTEL_LPSS
580 bool "Intel Low Power Subsystem Support"
581 depends on X86 && ACPI
586 Select to build support for Intel Low Power Subsystem such as
587 found on Intel Lynxpoint PCH. Selecting this option enables
588 things like clock tree (common clock framework) and pincontrol
589 which are needed by the LPSS peripheral drivers.
591 config X86_AMD_PLATFORM_DEVICE
592 bool "AMD ACPI2Platform devices support"
597 Select to interpret AMD specific ACPI device to platform device
598 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
599 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
600 implemented under PINCTRL subsystem.
603 tristate "Intel SoC IOSF Sideband support for SoC platforms"
606 This option enables sideband register access support for Intel SoC
607 platforms. On these platforms the IOSF sideband is used in lieu of
608 MSR's for some register accesses, mostly but not limited to thermal
609 and power. Drivers may query the availability of this device to
610 determine if they need the sideband in order to work on these
611 platforms. The sideband is available on the following SoC products.
612 This list is not meant to be exclusive.
617 You should say Y if you are running a kernel on one of these SoC's.
619 config IOSF_MBI_DEBUG
620 bool "Enable IOSF sideband access through debugfs"
621 depends on IOSF_MBI && DEBUG_FS
623 Select this option to expose the IOSF sideband access registers (MCR,
624 MDR, MCRX) through debugfs to write and read register information from
625 different units on the SoC. This is most useful for obtaining device
626 state information for debug and analysis. As this is a general access
627 mechanism, users of this option would have specific knowledge of the
628 device they want to access.
630 If you don't require the option or are in doubt, say N.
633 bool "RDC R-321x SoC"
635 depends on X86_EXTENDED_PLATFORM
637 select X86_REBOOTFIXUPS
639 This option is needed for RDC R-321x system-on-chip, also known
641 If you don't have one of these chips, you should say N here.
643 config X86_32_NON_STANDARD
644 bool "Support non-standard 32-bit SMP architectures"
645 depends on X86_32 && SMP
646 depends on X86_EXTENDED_PLATFORM
648 This option compiles in the bigsmp and STA2X11 default
649 subarchitectures. It is intended for a generic binary
650 kernel. If you select them all, kernel will probe it one by
651 one and will fallback to default.
653 # Alphabetically sorted list of Non standard 32 bit platforms
655 config X86_SUPPORTS_MEMORY_FAILURE
657 # MCE code calls memory_failure():
659 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
660 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
661 depends on X86_64 || !SPARSEMEM
662 select ARCH_SUPPORTS_MEMORY_FAILURE
665 bool "STA2X11 Companion Chip Support"
666 depends on X86_32_NON_STANDARD && PCI
667 select X86_DEV_DMA_OPS
674 This adds support for boards based on the STA2X11 IO-Hub,
675 a.k.a. "ConneXt". The chip is used in place of the standard
676 PC chipset, so all "standard" peripherals are missing. If this
677 option is selected the kernel will still be able to boot on
678 standard PC machines.
681 tristate "Eurobraille/Iris poweroff module"
684 The Iris machines from EuroBraille do not have APM or ACPI support
685 to shut themselves down properly. A special I/O sequence is
686 needed to do so, which is what this module does at
689 This is only for Iris machines from EuroBraille.
693 config SCHED_OMIT_FRAME_POINTER
695 prompt "Single-depth WCHAN output"
698 Calculate simpler /proc/<PID>/wchan values. If this option
699 is disabled then wchan values will recurse back to the
700 caller function. This provides more accurate wchan values,
701 at the expense of slightly more scheduling overhead.
703 If in doubt, say "Y".
705 menuconfig HYPERVISOR_GUEST
706 bool "Linux guest support"
708 Say Y here to enable options for running Linux under various hyper-
709 visors. This option enables basic hypervisor detection and platform
712 If you say N, all options in this submenu will be skipped and
713 disabled, and Linux guest support won't be built in.
718 bool "Enable paravirtualization code"
720 This changes the kernel so it can modify itself when it is run
721 under a hypervisor, potentially improving performance significantly
722 over full virtualization. However, when run without a hypervisor
723 the kernel is theoretically slower and slightly larger.
725 config PARAVIRT_DEBUG
726 bool "paravirt-ops debugging"
727 depends on PARAVIRT && DEBUG_KERNEL
729 Enable to debug paravirt_ops internals. Specifically, BUG if
730 a paravirt_op is missing when it is called.
732 config PARAVIRT_SPINLOCKS
733 bool "Paravirtualization layer for spinlocks"
734 depends on PARAVIRT && SMP
736 Paravirtualized spinlocks allow a pvops backend to replace the
737 spinlock implementation with something virtualization-friendly
738 (for example, block the virtual CPU rather than spinning).
740 It has a minimal impact on native kernels and gives a nice performance
741 benefit on paravirtualized KVM / Xen kernels.
743 If you are unsure how to answer this question, answer Y.
745 config QUEUED_LOCK_STAT
746 bool "Paravirt queued spinlock statistics"
747 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
749 Enable the collection of statistical data on the slowpath
750 behavior of paravirtualized queued spinlocks and report
753 source "arch/x86/xen/Kconfig"
756 bool "KVM Guest support (including kvmclock)"
758 select PARAVIRT_CLOCK
761 This option enables various optimizations for running under the KVM
762 hypervisor. It includes a paravirtualized clock, so that instead
763 of relying on a PIT (or probably other) emulation by the
764 underlying device model, the host provides the guest with
765 timing infrastructure such as time of day, and system time
768 bool "Enable debug information for KVM Guests in debugfs"
769 depends on KVM_GUEST && DEBUG_FS
772 This option enables collection of various statistics for KVM guest.
773 Statistics are displayed in debugfs filesystem. Enabling this option
774 may incur significant overhead.
776 source "arch/x86/lguest/Kconfig"
778 config PARAVIRT_TIME_ACCOUNTING
779 bool "Paravirtual steal time accounting"
783 Select this option to enable fine granularity task steal time
784 accounting. Time spent executing other tasks in parallel with
785 the current vCPU is discounted from the vCPU power. To account for
786 that, there can be a small performance impact.
788 If in doubt, say N here.
790 config PARAVIRT_CLOCK
793 endif #HYPERVISOR_GUEST
798 source "arch/x86/Kconfig.cpu"
802 prompt "HPET Timer Support" if X86_32
804 Use the IA-PC HPET (High Precision Event Timer) to manage
805 time in preference to the PIT and RTC, if a HPET is
807 HPET is the next generation timer replacing legacy 8254s.
808 The HPET provides a stable time base on SMP
809 systems, unlike the TSC, but it is more expensive to access,
810 as it is off-chip. The interface used is documented
811 in the HPET spec, revision 1.
813 You can safely choose Y here. However, HPET will only be
814 activated if the platform and the BIOS support this feature.
815 Otherwise the 8254 will be used for timing services.
817 Choose N to continue using the legacy 8254 timer.
819 config HPET_EMULATE_RTC
821 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
824 def_bool y if X86_INTEL_MID
825 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
827 depends on X86_INTEL_MID && SFI
829 APB timer is the replacement for 8254, HPET on X86 MID platforms.
830 The APBT provides a stable time base on SMP
831 systems, unlike the TSC, but it is more expensive to access,
832 as it is off-chip. APB timers are always running regardless of CPU
833 C states, they are used as per CPU clockevent device when possible.
835 # Mark as expert because too many people got it wrong.
836 # The code disables itself when not needed.
839 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
840 bool "Enable DMI scanning" if EXPERT
842 Enabled scanning of DMI to identify machine quirks. Say Y
843 here unless you have verified that your setup is not
844 affected by entries in the DMI blacklist. Required by PNP
848 bool "Old AMD GART IOMMU support"
850 depends on X86_64 && PCI && AMD_NB
852 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
853 GART based hardware IOMMUs.
855 The GART supports full DMA access for devices with 32-bit access
856 limitations, on systems with more than 3 GB. This is usually needed
857 for USB, sound, many IDE/SATA chipsets and some other devices.
859 Newer systems typically have a modern AMD IOMMU, supported via
860 the CONFIG_AMD_IOMMU=y config option.
862 In normal configurations this driver is only active when needed:
863 there's more than 3 GB of memory and the system contains a
864 32-bit limited device.
869 bool "IBM Calgary IOMMU support"
871 depends on X86_64 && PCI
873 Support for hardware IOMMUs in IBM's xSeries x366 and x460
874 systems. Needed to run systems with more than 3GB of memory
875 properly with 32-bit PCI devices that do not support DAC
876 (Double Address Cycle). Calgary also supports bus level
877 isolation, where all DMAs pass through the IOMMU. This
878 prevents them from going anywhere except their intended
879 destination. This catches hard-to-find kernel bugs and
880 mis-behaving drivers and devices that do not use the DMA-API
881 properly to set up their DMA buffers. The IOMMU can be
882 turned off at boot time with the iommu=off parameter.
883 Normally the kernel will make the right choice by itself.
886 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
888 prompt "Should Calgary be enabled by default?"
889 depends on CALGARY_IOMMU
891 Should Calgary be enabled by default? if you choose 'y', Calgary
892 will be used (if it exists). If you choose 'n', Calgary will not be
893 used even if it exists. If you choose 'n' and would like to use
894 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
897 # need this always selected by IOMMU for the VIA workaround
901 Support for software bounce buffers used on x86-64 systems
902 which don't have a hardware IOMMU. Using this PCI devices
903 which can only access 32-bits of memory can be used on systems
904 with more than 3 GB of memory.
909 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
912 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
913 depends on X86_64 && SMP && DEBUG_KERNEL
914 select CPUMASK_OFFSTACK
916 Enable maximum number of CPUS and NUMA Nodes for this architecture.
920 int "Maximum number of CPUs" if SMP && !MAXSMP
921 range 2 8 if SMP && X86_32 && !X86_BIGSMP
922 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
923 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
925 default "8192" if MAXSMP
926 default "32" if SMP && X86_BIGSMP
927 default "8" if SMP && X86_32
930 This allows you to specify the maximum number of CPUs which this
931 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
932 supported value is 8192, otherwise the maximum value is 512. The
933 minimum value which makes sense is 2.
935 This is purely to save memory - each supported CPU adds
936 approximately eight kilobytes to the kernel image.
939 bool "SMT (Hyperthreading) scheduler support"
942 SMT scheduler support improves the CPU scheduler's decision making
943 when dealing with Intel Pentium 4 chips with HyperThreading at a
944 cost of slightly increased overhead in some places. If unsure say
949 prompt "Multi-core scheduler support"
952 Multi-core scheduler support improves the CPU scheduler's decision
953 making when dealing with multi-core CPU chips at a cost of slightly
954 increased overhead in some places. If unsure say N here.
956 source "kernel/Kconfig.preempt"
960 depends on !SMP && X86_LOCAL_APIC
963 bool "Local APIC support on uniprocessors" if !PCI_MSI
965 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
967 A local APIC (Advanced Programmable Interrupt Controller) is an
968 integrated interrupt controller in the CPU. If you have a single-CPU
969 system which has a processor with a local APIC, you can say Y here to
970 enable and use it. If you say Y here even though your machine doesn't
971 have a local APIC, then the kernel will still run with no slowdown at
972 all. The local APIC supports CPU-generated self-interrupts (timer,
973 performance counters), and the NMI watchdog which detects hard
977 bool "IO-APIC support on uniprocessors"
978 depends on X86_UP_APIC
980 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
981 SMP-capable replacement for PC-style interrupt controllers. Most
982 SMP systems and many recent uniprocessor systems have one.
984 If you have a single-CPU system with an IO-APIC, you can say Y here
985 to use it. If you say Y here even though your machine doesn't have
986 an IO-APIC, then the kernel will still run with no slowdown at all.
988 config X86_LOCAL_APIC
990 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
991 select IRQ_DOMAIN_HIERARCHY
992 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
996 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
998 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
999 bool "Reroute for broken boot IRQs"
1000 depends on X86_IO_APIC
1002 This option enables a workaround that fixes a source of
1003 spurious interrupts. This is recommended when threaded
1004 interrupt handling is used on systems where the generation of
1005 superfluous "boot interrupts" cannot be disabled.
1007 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1008 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1009 kernel does during interrupt handling). On chipsets where this
1010 boot IRQ generation cannot be disabled, this workaround keeps
1011 the original IRQ line masked so that only the equivalent "boot
1012 IRQ" is delivered to the CPUs. The workaround also tells the
1013 kernel to set up the IRQ handler on the boot IRQ line. In this
1014 way only one interrupt is delivered to the kernel. Otherwise
1015 the spurious second interrupt may cause the kernel to bring
1016 down (vital) interrupt lines.
1018 Only affects "broken" chipsets. Interrupt sharing may be
1019 increased on these systems.
1022 bool "Machine Check / overheating reporting"
1023 select GENERIC_ALLOCATOR
1026 Machine Check support allows the processor to notify the
1027 kernel if it detects a problem (e.g. overheating, data corruption).
1028 The action the kernel takes depends on the severity of the problem,
1029 ranging from warning messages to halting the machine.
1031 config X86_MCE_INTEL
1033 prompt "Intel MCE features"
1034 depends on X86_MCE && X86_LOCAL_APIC
1036 Additional support for intel specific MCE features such as
1037 the thermal monitor.
1041 prompt "AMD MCE features"
1042 depends on X86_MCE && X86_LOCAL_APIC
1044 Additional support for AMD specific MCE features such as
1045 the DRAM Error Threshold.
1047 config X86_ANCIENT_MCE
1048 bool "Support for old Pentium 5 / WinChip machine checks"
1049 depends on X86_32 && X86_MCE
1051 Include support for machine check handling on old Pentium 5 or WinChip
1052 systems. These typically need to be enabled explicitly on the command
1055 config X86_MCE_THRESHOLD
1056 depends on X86_MCE_AMD || X86_MCE_INTEL
1059 config X86_MCE_INJECT
1060 depends on X86_MCE && X86_LOCAL_APIC
1061 tristate "Machine check injector support"
1063 Provide support for injecting machine checks for testing purposes.
1064 If you don't know what a machine check is and you don't do kernel
1065 QA it is safe to say n.
1067 config X86_THERMAL_VECTOR
1069 depends on X86_MCE_INTEL
1071 source "arch/x86/events/Kconfig"
1073 config X86_LEGACY_VM86
1074 bool "Legacy VM86 support"
1078 This option allows user programs to put the CPU into V8086
1079 mode, which is an 80286-era approximation of 16-bit real mode.
1081 Some very old versions of X and/or vbetool require this option
1082 for user mode setting. Similarly, DOSEMU will use it if
1083 available to accelerate real mode DOS programs. However, any
1084 recent version of DOSEMU, X, or vbetool should be fully
1085 functional even without kernel VM86 support, as they will all
1086 fall back to software emulation. Nevertheless, if you are using
1087 a 16-bit DOS program where 16-bit performance matters, vm86
1088 mode might be faster than emulation and you might want to
1091 Note that any app that works on a 64-bit kernel is unlikely to
1092 need this option, as 64-bit kernels don't, and can't, support
1093 V8086 mode. This option is also unrelated to 16-bit protected
1094 mode and is not needed to run most 16-bit programs under Wine.
1096 Enabling this option increases the complexity of the kernel
1097 and slows down exception handling a tiny bit.
1099 If unsure, say N here.
1103 default X86_LEGACY_VM86
1106 bool "Enable support for 16-bit segments" if EXPERT
1108 depends on MODIFY_LDT_SYSCALL
1110 This option is required by programs like Wine to run 16-bit
1111 protected mode legacy code on x86 processors. Disabling
1112 this option saves about 300 bytes on i386, or around 6K text
1113 plus 16K runtime memory on x86-64,
1117 depends on X86_16BIT && X86_32
1121 depends on X86_16BIT && X86_64
1123 config X86_VSYSCALL_EMULATION
1124 bool "Enable vsyscall emulation" if EXPERT
1128 This enables emulation of the legacy vsyscall page. Disabling
1129 it is roughly equivalent to booting with vsyscall=none, except
1130 that it will also disable the helpful warning if a program
1131 tries to use a vsyscall. With this option set to N, offending
1132 programs will just segfault, citing addresses of the form
1135 This option is required by many programs built before 2013, and
1136 care should be used even with newer programs if set to N.
1138 Disabling this option saves about 7K of kernel size and
1139 possibly 4K of additional runtime pagetable memory.
1142 tristate "Toshiba Laptop support"
1145 This adds a driver to safely access the System Management Mode of
1146 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1147 not work on models with a Phoenix BIOS. The System Management Mode
1148 is used to set the BIOS and power saving options on Toshiba portables.
1150 For information on utilities to make use of this driver see the
1151 Toshiba Linux utilities web site at:
1152 <http://www.buzzard.org.uk/toshiba/>.
1154 Say Y if you intend to run this kernel on a Toshiba portable.
1158 tristate "Dell i8k legacy laptop support"
1160 select SENSORS_DELL_SMM
1162 This option enables legacy /proc/i8k userspace interface in hwmon
1163 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1164 temperature and allows controlling fan speeds of Dell laptops via
1165 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1166 it reports also power and hotkey status. For fan speed control is
1167 needed userspace package i8kutils.
1169 Say Y if you intend to run this kernel on old Dell laptops or want to
1170 use userspace package i8kutils.
1173 config X86_REBOOTFIXUPS
1174 bool "Enable X86 board specific fixups for reboot"
1177 This enables chipset and/or board specific fixups to be done
1178 in order to get reboot to work correctly. This is only needed on
1179 some combinations of hardware and BIOS. The symptom, for which
1180 this config is intended, is when reboot ends with a stalled/hung
1183 Currently, the only fixup is for the Geode machines using
1184 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1186 Say Y if you want to enable the fixup. Currently, it's safe to
1187 enable this option even if you don't need it.
1191 bool "CPU microcode loading support"
1193 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1196 If you say Y here, you will be able to update the microcode on
1197 Intel and AMD processors. The Intel support is for the IA32 family,
1198 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1199 AMD support is for families 0x10 and later. You will obviously need
1200 the actual microcode binary data itself which is not shipped with
1203 The preferred method to load microcode from a detached initrd is described
1204 in Documentation/x86/early-microcode.txt. For that you need to enable
1205 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1206 initrd for microcode blobs.
1208 In addition, you can build-in the microcode into the kernel. For that you
1209 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1210 to the CONFIG_EXTRA_FIRMWARE config option.
1212 config MICROCODE_INTEL
1213 bool "Intel microcode loading support"
1214 depends on MICROCODE
1218 This options enables microcode patch loading support for Intel
1221 For the current Intel microcode data package go to
1222 <https://downloadcenter.intel.com> and search for
1223 'Linux Processor Microcode Data File'.
1225 config MICROCODE_AMD
1226 bool "AMD microcode loading support"
1227 depends on MICROCODE
1230 If you select this option, microcode patch loading support for AMD
1231 processors will be enabled.
1233 config MICROCODE_OLD_INTERFACE
1235 depends on MICROCODE
1238 tristate "/dev/cpu/*/msr - Model-specific register support"
1240 This device gives privileged processes access to the x86
1241 Model-Specific Registers (MSRs). It is a character device with
1242 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1243 MSR accesses are directed to a specific CPU on multi-processor
1247 tristate "/dev/cpu/*/cpuid - CPU information support"
1249 This device gives processes access to the x86 CPUID instruction to
1250 be executed on a specific processor. It is a character device
1251 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1255 prompt "High Memory Support"
1262 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1263 However, the address space of 32-bit x86 processors is only 4
1264 Gigabytes large. That means that, if you have a large amount of
1265 physical memory, not all of it can be "permanently mapped" by the
1266 kernel. The physical memory that's not permanently mapped is called
1269 If you are compiling a kernel which will never run on a machine with
1270 more than 1 Gigabyte total physical RAM, answer "off" here (default
1271 choice and suitable for most users). This will result in a "3GB/1GB"
1272 split: 3GB are mapped so that each process sees a 3GB virtual memory
1273 space and the remaining part of the 4GB virtual memory space is used
1274 by the kernel to permanently map as much physical memory as
1277 If the machine has between 1 and 4 Gigabytes physical RAM, then
1280 If more than 4 Gigabytes is used then answer "64GB" here. This
1281 selection turns Intel PAE (Physical Address Extension) mode on.
1282 PAE implements 3-level paging on IA32 processors. PAE is fully
1283 supported by Linux, PAE mode is implemented on all recent Intel
1284 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1285 then the kernel will not boot on CPUs that don't support PAE!
1287 The actual amount of total physical memory will either be
1288 auto detected or can be forced by using a kernel command line option
1289 such as "mem=256M". (Try "man bootparam" or see the documentation of
1290 your boot loader (lilo or loadlin) about how to pass options to the
1291 kernel at boot time.)
1293 If unsure, say "off".
1298 Select this if you have a 32-bit processor and between 1 and 4
1299 gigabytes of physical RAM.
1306 Select this if you have a 32-bit processor and more than 4
1307 gigabytes of physical RAM.
1312 prompt "Memory split" if EXPERT
1316 Select the desired split between kernel and user memory.
1318 If the address range available to the kernel is less than the
1319 physical memory installed, the remaining memory will be available
1320 as "high memory". Accessing high memory is a little more costly
1321 than low memory, as it needs to be mapped into the kernel first.
1322 Note that increasing the kernel address space limits the range
1323 available to user programs, making the address space there
1324 tighter. Selecting anything other than the default 3G/1G split
1325 will also likely make your kernel incompatible with binary-only
1328 If you are not absolutely sure what you are doing, leave this
1332 bool "3G/1G user/kernel split"
1333 config VMSPLIT_3G_OPT
1335 bool "3G/1G user/kernel split (for full 1G low memory)"
1337 bool "2G/2G user/kernel split"
1338 config VMSPLIT_2G_OPT
1340 bool "2G/2G user/kernel split (for full 2G low memory)"
1342 bool "1G/3G user/kernel split"
1347 default 0xB0000000 if VMSPLIT_3G_OPT
1348 default 0x80000000 if VMSPLIT_2G
1349 default 0x78000000 if VMSPLIT_2G_OPT
1350 default 0x40000000 if VMSPLIT_1G
1356 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1359 bool "PAE (Physical Address Extension) Support"
1360 depends on X86_32 && !HIGHMEM4G
1363 PAE is required for NX support, and furthermore enables
1364 larger swapspace support for non-overcommit purposes. It
1365 has the cost of more pagetable lookup overhead, and also
1366 consumes more pagetable space per process.
1368 config ARCH_PHYS_ADDR_T_64BIT
1370 depends on X86_64 || X86_PAE
1372 config ARCH_DMA_ADDR_T_64BIT
1374 depends on X86_64 || HIGHMEM64G
1376 config X86_DIRECT_GBPAGES
1378 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1380 Certain kernel features effectively disable kernel
1381 linear 1 GB mappings (even if the CPU otherwise
1382 supports them), so don't confuse the user by printing
1383 that we have them enabled.
1385 # Common NUMA Features
1387 bool "Numa Memory Allocation and Scheduler Support"
1389 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1390 default y if X86_BIGSMP
1392 Enable NUMA (Non Uniform Memory Access) support.
1394 The kernel will try to allocate memory used by a CPU on the
1395 local memory controller of the CPU and add some more
1396 NUMA awareness to the kernel.
1398 For 64-bit this is recommended if the system is Intel Core i7
1399 (or later), AMD Opteron, or EM64T NUMA.
1401 For 32-bit this is only needed if you boot a 32-bit
1402 kernel on a 64-bit NUMA platform.
1404 Otherwise, you should say N.
1408 prompt "Old style AMD Opteron NUMA detection"
1409 depends on X86_64 && NUMA && PCI
1411 Enable AMD NUMA node topology detection. You should say Y here if
1412 you have a multi processor AMD system. This uses an old method to
1413 read the NUMA configuration directly from the builtin Northbridge
1414 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1415 which also takes priority if both are compiled in.
1417 config X86_64_ACPI_NUMA
1419 prompt "ACPI NUMA detection"
1420 depends on X86_64 && NUMA && ACPI && PCI
1423 Enable ACPI SRAT based node topology detection.
1425 # Some NUMA nodes have memory ranges that span
1426 # other nodes. Even though a pfn is valid and
1427 # between a node's start and end pfns, it may not
1428 # reside on that node. See memmap_init_zone()
1430 config NODES_SPAN_OTHER_NODES
1432 depends on X86_64_ACPI_NUMA
1435 bool "NUMA emulation"
1438 Enable NUMA emulation. A flat machine will be split
1439 into virtual nodes when booted with "numa=fake=N", where N is the
1440 number of nodes. This is only useful for debugging.
1443 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1445 default "10" if MAXSMP
1446 default "6" if X86_64
1448 depends on NEED_MULTIPLE_NODES
1450 Specify the maximum number of NUMA Nodes available on the target
1451 system. Increases memory reserved to accommodate various tables.
1453 config ARCH_HAVE_MEMORY_PRESENT
1455 depends on X86_32 && DISCONTIGMEM
1457 config NEED_NODE_MEMMAP_SIZE
1459 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1461 config ARCH_FLATMEM_ENABLE
1463 depends on X86_32 && !NUMA
1465 config ARCH_DISCONTIGMEM_ENABLE
1467 depends on NUMA && X86_32
1469 config ARCH_DISCONTIGMEM_DEFAULT
1471 depends on NUMA && X86_32
1473 config ARCH_SPARSEMEM_ENABLE
1475 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1476 select SPARSEMEM_STATIC if X86_32
1477 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1479 config ARCH_SPARSEMEM_DEFAULT
1483 config ARCH_SELECT_MEMORY_MODEL
1485 depends on ARCH_SPARSEMEM_ENABLE
1487 config ARCH_MEMORY_PROBE
1488 bool "Enable sysfs memory/probe interface"
1489 depends on X86_64 && MEMORY_HOTPLUG
1491 This option enables a sysfs memory/probe interface for testing.
1492 See Documentation/memory-hotplug.txt for more information.
1493 If you are unsure how to answer this question, answer N.
1495 config ARCH_PROC_KCORE_TEXT
1497 depends on X86_64 && PROC_KCORE
1499 config ILLEGAL_POINTER_VALUE
1502 default 0xdead000000000000 if X86_64
1506 config X86_PMEM_LEGACY_DEVICE
1509 config X86_PMEM_LEGACY
1510 tristate "Support non-standard NVDIMMs and ADR protected memory"
1511 depends on PHYS_ADDR_T_64BIT
1513 select X86_PMEM_LEGACY_DEVICE
1516 Treat memory marked using the non-standard e820 type of 12 as used
1517 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1518 The kernel will offer these regions to the 'pmem' driver so
1519 they can be used for persistent storage.
1524 bool "Allocate 3rd-level pagetables from highmem"
1527 The VM uses one page table entry for each page of physical memory.
1528 For systems with a lot of RAM, this can be wasteful of precious
1529 low memory. Setting this option will put user-space page table
1530 entries in high memory.
1532 config X86_CHECK_BIOS_CORRUPTION
1533 bool "Check for low memory corruption"
1535 Periodically check for memory corruption in low memory, which
1536 is suspected to be caused by BIOS. Even when enabled in the
1537 configuration, it is disabled at runtime. Enable it by
1538 setting "memory_corruption_check=1" on the kernel command
1539 line. By default it scans the low 64k of memory every 60
1540 seconds; see the memory_corruption_check_size and
1541 memory_corruption_check_period parameters in
1542 Documentation/kernel-parameters.txt to adjust this.
1544 When enabled with the default parameters, this option has
1545 almost no overhead, as it reserves a relatively small amount
1546 of memory and scans it infrequently. It both detects corruption
1547 and prevents it from affecting the running system.
1549 It is, however, intended as a diagnostic tool; if repeatable
1550 BIOS-originated corruption always affects the same memory,
1551 you can use memmap= to prevent the kernel from using that
1554 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1555 bool "Set the default setting of memory_corruption_check"
1556 depends on X86_CHECK_BIOS_CORRUPTION
1559 Set whether the default state of memory_corruption_check is
1562 config X86_RESERVE_LOW
1563 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1567 Specify the amount of low memory to reserve for the BIOS.
1569 The first page contains BIOS data structures that the kernel
1570 must not use, so that page must always be reserved.
1572 By default we reserve the first 64K of physical RAM, as a
1573 number of BIOSes are known to corrupt that memory range
1574 during events such as suspend/resume or monitor cable
1575 insertion, so it must not be used by the kernel.
1577 You can set this to 4 if you are absolutely sure that you
1578 trust the BIOS to get all its memory reservations and usages
1579 right. If you know your BIOS have problems beyond the
1580 default 64K area, you can set this to 640 to avoid using the
1581 entire low memory range.
1583 If you have doubts about the BIOS (e.g. suspend/resume does
1584 not work or there's kernel crashes after certain hardware
1585 hotplug events) then you might want to enable
1586 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1587 typical corruption patterns.
1589 Leave this to the default value of 64 if you are unsure.
1591 config MATH_EMULATION
1593 depends on MODIFY_LDT_SYSCALL
1594 prompt "Math emulation" if X86_32
1596 Linux can emulate a math coprocessor (used for floating point
1597 operations) if you don't have one. 486DX and Pentium processors have
1598 a math coprocessor built in, 486SX and 386 do not, unless you added
1599 a 487DX or 387, respectively. (The messages during boot time can
1600 give you some hints here ["man dmesg"].) Everyone needs either a
1601 coprocessor or this emulation.
1603 If you don't have a math coprocessor, you need to say Y here; if you
1604 say Y here even though you have a coprocessor, the coprocessor will
1605 be used nevertheless. (This behavior can be changed with the kernel
1606 command line option "no387", which comes handy if your coprocessor
1607 is broken. Try "man bootparam" or see the documentation of your boot
1608 loader (lilo or loadlin) about how to pass options to the kernel at
1609 boot time.) This means that it is a good idea to say Y here if you
1610 intend to use this kernel on different machines.
1612 More information about the internals of the Linux math coprocessor
1613 emulation can be found in <file:arch/x86/math-emu/README>.
1615 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1616 kernel, it won't hurt.
1620 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1622 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1623 the Memory Type Range Registers (MTRRs) may be used to control
1624 processor access to memory ranges. This is most useful if you have
1625 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1626 allows bus write transfers to be combined into a larger transfer
1627 before bursting over the PCI/AGP bus. This can increase performance
1628 of image write operations 2.5 times or more. Saying Y here creates a
1629 /proc/mtrr file which may be used to manipulate your processor's
1630 MTRRs. Typically the X server should use this.
1632 This code has a reasonably generic interface so that similar
1633 control registers on other processors can be easily supported
1636 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1637 Registers (ARRs) which provide a similar functionality to MTRRs. For
1638 these, the ARRs are used to emulate the MTRRs.
1639 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1640 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1641 write-combining. All of these processors are supported by this code
1642 and it makes sense to say Y here if you have one of them.
1644 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1645 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1646 can lead to all sorts of problems, so it's good to say Y here.
1648 You can safely say Y even if your machine doesn't have MTRRs, you'll
1649 just add about 9 KB to your kernel.
1651 See <file:Documentation/x86/mtrr.txt> for more information.
1653 config MTRR_SANITIZER
1655 prompt "MTRR cleanup support"
1658 Convert MTRR layout from continuous to discrete, so X drivers can
1659 add writeback entries.
1661 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1662 The largest mtrr entry size for a continuous block can be set with
1667 config MTRR_SANITIZER_ENABLE_DEFAULT
1668 int "MTRR cleanup enable value (0-1)"
1671 depends on MTRR_SANITIZER
1673 Enable mtrr cleanup default value
1675 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1676 int "MTRR cleanup spare reg num (0-7)"
1679 depends on MTRR_SANITIZER
1681 mtrr cleanup spare entries default, it can be changed via
1682 mtrr_spare_reg_nr=N on the kernel command line.
1686 prompt "x86 PAT support" if EXPERT
1689 Use PAT attributes to setup page level cache control.
1691 PATs are the modern equivalents of MTRRs and are much more
1692 flexible than MTRRs.
1694 Say N here if you see bootup problems (boot crash, boot hang,
1695 spontaneous reboots) or a non-working video driver.
1699 config ARCH_USES_PG_UNCACHED
1705 prompt "x86 architectural random number generator" if EXPERT
1707 Enable the x86 architectural RDRAND instruction
1708 (Intel Bull Mountain technology) to generate random numbers.
1709 If supported, this is a high bandwidth, cryptographically
1710 secure hardware random number generator.
1714 prompt "Supervisor Mode Access Prevention" if EXPERT
1716 Supervisor Mode Access Prevention (SMAP) is a security
1717 feature in newer Intel processors. There is a small
1718 performance cost if this enabled and turned on; there is
1719 also a small increase in the kernel size if this is enabled.
1723 config X86_INTEL_MPX
1724 prompt "Intel MPX (Memory Protection Extensions)"
1726 depends on CPU_SUP_INTEL
1728 MPX provides hardware features that can be used in
1729 conjunction with compiler-instrumented code to check
1730 memory references. It is designed to detect buffer
1731 overflow or underflow bugs.
1733 This option enables running applications which are
1734 instrumented or otherwise use MPX. It does not use MPX
1735 itself inside the kernel or to protect the kernel
1736 against bad memory references.
1738 Enabling this option will make the kernel larger:
1739 ~8k of kernel text and 36 bytes of data on a 64-bit
1740 defconfig. It adds a long to the 'mm_struct' which
1741 will increase the kernel memory overhead of each
1742 process and adds some branches to paths used during
1743 exec() and munmap().
1745 For details, see Documentation/x86/intel_mpx.txt
1749 config X86_INTEL_MEMORY_PROTECTION_KEYS
1750 prompt "Intel Memory Protection Keys"
1752 # Note: only available in 64-bit mode
1753 depends on CPU_SUP_INTEL && X86_64
1755 Memory Protection Keys provides a mechanism for enforcing
1756 page-based protections, but without requiring modification of the
1757 page tables when an application changes protection domains.
1759 For details, see Documentation/x86/protection-keys.txt
1764 bool "EFI runtime service support"
1767 select EFI_RUNTIME_WRAPPERS
1769 This enables the kernel to use EFI runtime services that are
1770 available (such as the EFI variable services).
1772 This option is only useful on systems that have EFI firmware.
1773 In addition, you should use the latest ELILO loader available
1774 at <http://elilo.sourceforge.net> in order to take advantage
1775 of EFI runtime services. However, even with this option, the
1776 resultant kernel should continue to boot on existing non-EFI
1780 bool "EFI stub support"
1781 depends on EFI && !X86_USE_3DNOW
1784 This kernel feature allows a bzImage to be loaded directly
1785 by EFI firmware without the use of a bootloader.
1787 See Documentation/efi-stub.txt for more information.
1790 bool "EFI mixed-mode support"
1791 depends on EFI_STUB && X86_64
1793 Enabling this feature allows a 64-bit kernel to be booted
1794 on a 32-bit firmware, provided that your CPU supports 64-bit
1797 Note that it is not possible to boot a mixed-mode enabled
1798 kernel via the EFI boot stub - a bootloader that supports
1799 the EFI handover protocol must be used.
1805 prompt "Enable seccomp to safely compute untrusted bytecode"
1807 This kernel feature is useful for number crunching applications
1808 that may need to compute untrusted bytecode during their
1809 execution. By using pipes or other transports made available to
1810 the process as file descriptors supporting the read/write
1811 syscalls, it's possible to isolate those applications in
1812 their own address space using seccomp. Once seccomp is
1813 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1814 and the task is only allowed to execute a few safe syscalls
1815 defined by each seccomp mode.
1817 If unsure, say Y. Only embedded should say N here.
1819 source kernel/Kconfig.hz
1822 bool "kexec system call"
1825 kexec is a system call that implements the ability to shutdown your
1826 current kernel, and to start another kernel. It is like a reboot
1827 but it is independent of the system firmware. And like a reboot
1828 you can start any kernel with it, not just Linux.
1830 The name comes from the similarity to the exec system call.
1832 It is an ongoing process to be certain the hardware in a machine
1833 is properly shutdown, so do not be surprised if this code does not
1834 initially work for you. As of this writing the exact hardware
1835 interface is strongly in flux, so no good recommendation can be
1839 bool "kexec file based system call"
1844 depends on CRYPTO_SHA256=y
1846 This is new version of kexec system call. This system call is
1847 file based and takes file descriptors as system call argument
1848 for kernel and initramfs as opposed to list of segments as
1849 accepted by previous system call.
1851 config KEXEC_VERIFY_SIG
1852 bool "Verify kernel signature during kexec_file_load() syscall"
1853 depends on KEXEC_FILE
1855 This option makes kernel signature verification mandatory for
1856 the kexec_file_load() syscall.
1858 In addition to that option, you need to enable signature
1859 verification for the corresponding kernel image type being
1860 loaded in order for this to work.
1862 config KEXEC_BZIMAGE_VERIFY_SIG
1863 bool "Enable bzImage signature verification support"
1864 depends on KEXEC_VERIFY_SIG
1865 depends on SIGNED_PE_FILE_VERIFICATION
1866 select SYSTEM_TRUSTED_KEYRING
1868 Enable bzImage signature verification support.
1871 bool "kernel crash dumps"
1872 depends on X86_64 || (X86_32 && HIGHMEM)
1874 Generate crash dump after being started by kexec.
1875 This should be normally only set in special crash dump kernels
1876 which are loaded in the main kernel with kexec-tools into
1877 a specially reserved region and then later executed after
1878 a crash by kdump/kexec. The crash dump kernel must be compiled
1879 to a memory address not used by the main kernel or BIOS using
1880 PHYSICAL_START, or it must be built as a relocatable image
1881 (CONFIG_RELOCATABLE=y).
1882 For more details see Documentation/kdump/kdump.txt
1886 depends on KEXEC && HIBERNATION
1888 Jump between original kernel and kexeced kernel and invoke
1889 code in physical address mode via KEXEC
1891 config PHYSICAL_START
1892 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1895 This gives the physical address where the kernel is loaded.
1897 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1898 bzImage will decompress itself to above physical address and
1899 run from there. Otherwise, bzImage will run from the address where
1900 it has been loaded by the boot loader and will ignore above physical
1903 In normal kdump cases one does not have to set/change this option
1904 as now bzImage can be compiled as a completely relocatable image
1905 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1906 address. This option is mainly useful for the folks who don't want
1907 to use a bzImage for capturing the crash dump and want to use a
1908 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1909 to be specifically compiled to run from a specific memory area
1910 (normally a reserved region) and this option comes handy.
1912 So if you are using bzImage for capturing the crash dump,
1913 leave the value here unchanged to 0x1000000 and set
1914 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1915 for capturing the crash dump change this value to start of
1916 the reserved region. In other words, it can be set based on
1917 the "X" value as specified in the "crashkernel=YM@XM"
1918 command line boot parameter passed to the panic-ed
1919 kernel. Please take a look at Documentation/kdump/kdump.txt
1920 for more details about crash dumps.
1922 Usage of bzImage for capturing the crash dump is recommended as
1923 one does not have to build two kernels. Same kernel can be used
1924 as production kernel and capture kernel. Above option should have
1925 gone away after relocatable bzImage support is introduced. But it
1926 is present because there are users out there who continue to use
1927 vmlinux for dump capture. This option should go away down the
1930 Don't change this unless you know what you are doing.
1933 bool "Build a relocatable kernel"
1936 This builds a kernel image that retains relocation information
1937 so it can be loaded someplace besides the default 1MB.
1938 The relocations tend to make the kernel binary about 10% larger,
1939 but are discarded at runtime.
1941 One use is for the kexec on panic case where the recovery kernel
1942 must live at a different physical address than the primary
1945 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1946 it has been loaded at and the compile time physical address
1947 (CONFIG_PHYSICAL_START) is used as the minimum location.
1949 config RANDOMIZE_BASE
1950 bool "Randomize the address of the kernel image (KASLR)"
1951 depends on RELOCATABLE
1954 In support of Kernel Address Space Layout Randomization (KASLR),
1955 this randomizes the physical address at which the kernel image
1956 is decompressed and the virtual address where the kernel
1957 image is mapped, as a security feature that deters exploit
1958 attempts relying on knowledge of the location of kernel
1961 On 64-bit, the kernel physical and virtual addresses are
1962 randomized separately. The physical address will be anywhere
1963 between 16MB and the top of physical memory (up to 64TB). The
1964 virtual address will be randomized from 16MB up to 1GB (9 bits
1965 of entropy). Note that this also reduces the memory space
1966 available to kernel modules from 1.5GB to 1GB.
1968 On 32-bit, the kernel physical and virtual addresses are
1969 randomized together. They will be randomized from 16MB up to
1970 512MB (8 bits of entropy).
1972 Entropy is generated using the RDRAND instruction if it is
1973 supported. If RDTSC is supported, its value is mixed into
1974 the entropy pool as well. If neither RDRAND nor RDTSC are
1975 supported, then entropy is read from the i8254 timer. The
1976 usable entropy is limited by the kernel being built using
1977 2GB addressing, and that PHYSICAL_ALIGN must be at a
1978 minimum of 2MB. As a result, only 10 bits of entropy are
1979 theoretically possible, but the implementations are further
1980 limited due to memory layouts.
1982 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1983 time. To enable it, boot with "kaslr" on the kernel command
1984 line (which will also disable hibernation).
1988 # Relocation on x86 needs some additional build support
1989 config X86_NEED_RELOCS
1991 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1993 config PHYSICAL_ALIGN
1994 hex "Alignment value to which kernel should be aligned"
1996 range 0x2000 0x1000000 if X86_32
1997 range 0x200000 0x1000000 if X86_64
1999 This value puts the alignment restrictions on physical address
2000 where kernel is loaded and run from. Kernel is compiled for an
2001 address which meets above alignment restriction.
2003 If bootloader loads the kernel at a non-aligned address and
2004 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2005 address aligned to above value and run from there.
2007 If bootloader loads the kernel at a non-aligned address and
2008 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2009 load address and decompress itself to the address it has been
2010 compiled for and run from there. The address for which kernel is
2011 compiled already meets above alignment restrictions. Hence the
2012 end result is that kernel runs from a physical address meeting
2013 above alignment restrictions.
2015 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2016 this value must be a multiple of 0x200000.
2018 Don't change this unless you know what you are doing.
2020 config RANDOMIZE_MEMORY
2021 bool "Randomize the kernel memory sections"
2023 depends on RANDOMIZE_BASE
2024 default RANDOMIZE_BASE
2026 Randomizes the base virtual address of kernel memory sections
2027 (physical memory mapping, vmalloc & vmemmap). This security feature
2028 makes exploits relying on predictable memory locations less reliable.
2030 The order of allocations remains unchanged. Entropy is generated in
2031 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2032 configuration have in average 30,000 different possible virtual
2033 addresses for each memory section.
2037 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2038 hex "Physical memory mapping padding" if EXPERT
2039 depends on RANDOMIZE_MEMORY
2040 default "0xa" if MEMORY_HOTPLUG
2042 range 0x1 0x40 if MEMORY_HOTPLUG
2045 Define the padding in terabytes added to the existing physical
2046 memory size during kernel memory randomization. It is useful
2047 for memory hotplug support but reduces the entropy available for
2048 address randomization.
2050 If unsure, leave at the default value.
2053 bool "Support for hot-pluggable CPUs"
2056 Say Y here to allow turning CPUs off and on. CPUs can be
2057 controlled through /sys/devices/system/cpu.
2058 ( Note: power management support will enable this option
2059 automatically on SMP systems. )
2060 Say N if you want to disable CPU hotplug.
2062 config BOOTPARAM_HOTPLUG_CPU0
2063 bool "Set default setting of cpu0_hotpluggable"
2065 depends on HOTPLUG_CPU
2067 Set whether default state of cpu0_hotpluggable is on or off.
2069 Say Y here to enable CPU0 hotplug by default. If this switch
2070 is turned on, there is no need to give cpu0_hotplug kernel
2071 parameter and the CPU0 hotplug feature is enabled by default.
2073 Please note: there are two known CPU0 dependencies if you want
2074 to enable the CPU0 hotplug feature either by this switch or by
2075 cpu0_hotplug kernel parameter.
2077 First, resume from hibernate or suspend always starts from CPU0.
2078 So hibernate and suspend are prevented if CPU0 is offline.
2080 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2081 offline if any interrupt can not migrate out of CPU0. There may
2082 be other CPU0 dependencies.
2084 Please make sure the dependencies are under your control before
2085 you enable this feature.
2087 Say N if you don't want to enable CPU0 hotplug feature by default.
2088 You still can enable the CPU0 hotplug feature at boot by kernel
2089 parameter cpu0_hotplug.
2091 config DEBUG_HOTPLUG_CPU0
2093 prompt "Debug CPU0 hotplug"
2094 depends on HOTPLUG_CPU
2096 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2097 soon as possible and boots up userspace with CPU0 offlined. User
2098 can online CPU0 back after boot time.
2100 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2101 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2102 compilation or giving cpu0_hotplug kernel parameter at boot.
2108 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2109 depends on X86_32 || IA32_EMULATION
2111 Certain buggy versions of glibc will crash if they are
2112 presented with a 32-bit vDSO that is not mapped at the address
2113 indicated in its segment table.
2115 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2116 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2117 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2118 the only released version with the bug, but OpenSUSE 9
2119 contains a buggy "glibc 2.3.2".
2121 The symptom of the bug is that everything crashes on startup, saying:
2122 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2124 Saying Y here changes the default value of the vdso32 boot
2125 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2126 This works around the glibc bug but hurts performance.
2128 If unsure, say N: if you are compiling your own kernel, you
2129 are unlikely to be using a buggy version of glibc.
2132 prompt "vsyscall table for legacy applications"
2134 default LEGACY_VSYSCALL_EMULATE
2136 Legacy user code that does not know how to find the vDSO expects
2137 to be able to issue three syscalls by calling fixed addresses in
2138 kernel space. Since this location is not randomized with ASLR,
2139 it can be used to assist security vulnerability exploitation.
2141 This setting can be changed at boot time via the kernel command
2142 line parameter vsyscall=[native|emulate|none].
2144 On a system with recent enough glibc (2.14 or newer) and no
2145 static binaries, you can say None without a performance penalty
2146 to improve security.
2148 If unsure, select "Emulate".
2150 config LEGACY_VSYSCALL_NATIVE
2153 Actual executable code is located in the fixed vsyscall
2154 address mapping, implementing time() efficiently. Since
2155 this makes the mapping executable, it can be used during
2156 security vulnerability exploitation (traditionally as
2157 ROP gadgets). This configuration is not recommended.
2159 config LEGACY_VSYSCALL_EMULATE
2162 The kernel traps and emulates calls into the fixed
2163 vsyscall address mapping. This makes the mapping
2164 non-executable, but it still contains known contents,
2165 which could be used in certain rare security vulnerability
2166 exploits. This configuration is recommended when userspace
2167 still uses the vsyscall area.
2169 config LEGACY_VSYSCALL_NONE
2172 There will be no vsyscall mapping at all. This will
2173 eliminate any risk of ASLR bypass due to the vsyscall
2174 fixed address mapping. Attempts to use the vsyscalls
2175 will be reported to dmesg, so that either old or
2176 malicious userspace programs can be identified.
2181 bool "Built-in kernel command line"
2183 Allow for specifying boot arguments to the kernel at
2184 build time. On some systems (e.g. embedded ones), it is
2185 necessary or convenient to provide some or all of the
2186 kernel boot arguments with the kernel itself (that is,
2187 to not rely on the boot loader to provide them.)
2189 To compile command line arguments into the kernel,
2190 set this option to 'Y', then fill in the
2191 boot arguments in CONFIG_CMDLINE.
2193 Systems with fully functional boot loaders (i.e. non-embedded)
2194 should leave this option set to 'N'.
2197 string "Built-in kernel command string"
2198 depends on CMDLINE_BOOL
2201 Enter arguments here that should be compiled into the kernel
2202 image and used at boot time. If the boot loader provides a
2203 command line at boot time, it is appended to this string to
2204 form the full kernel command line, when the system boots.
2206 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2207 change this behavior.
2209 In most cases, the command line (whether built-in or provided
2210 by the boot loader) should specify the device for the root
2213 config CMDLINE_OVERRIDE
2214 bool "Built-in command line overrides boot loader arguments"
2215 depends on CMDLINE_BOOL
2217 Set this option to 'Y' to have the kernel ignore the boot loader
2218 command line, and use ONLY the built-in command line.
2220 This is used to work around broken boot loaders. This should
2221 be set to 'N' under normal conditions.
2223 config MODIFY_LDT_SYSCALL
2224 bool "Enable the LDT (local descriptor table)" if EXPERT
2227 Linux can allow user programs to install a per-process x86
2228 Local Descriptor Table (LDT) using the modify_ldt(2) system
2229 call. This is required to run 16-bit or segmented code such as
2230 DOSEMU or some Wine programs. It is also used by some very old
2231 threading libraries.
2233 Enabling this feature adds a small amount of overhead to
2234 context switches and increases the low-level kernel attack
2235 surface. Disabling it removes the modify_ldt(2) system call.
2237 Saying 'N' here may make sense for embedded or server kernels.
2239 source "kernel/livepatch/Kconfig"
2243 config ARCH_ENABLE_MEMORY_HOTPLUG
2245 depends on X86_64 || (X86_32 && HIGHMEM)
2247 config ARCH_ENABLE_MEMORY_HOTREMOVE
2249 depends on MEMORY_HOTPLUG
2251 config USE_PERCPU_NUMA_NODE_ID
2255 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2257 depends on X86_64 || X86_PAE
2259 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2261 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2263 menu "Power management and ACPI options"
2265 config ARCH_HIBERNATION_HEADER
2267 depends on X86_64 && HIBERNATION
2269 source "kernel/power/Kconfig"
2271 source "drivers/acpi/Kconfig"
2273 source "drivers/sfi/Kconfig"
2280 tristate "APM (Advanced Power Management) BIOS support"
2281 depends on X86_32 && PM_SLEEP
2283 APM is a BIOS specification for saving power using several different
2284 techniques. This is mostly useful for battery powered laptops with
2285 APM compliant BIOSes. If you say Y here, the system time will be
2286 reset after a RESUME operation, the /proc/apm device will provide
2287 battery status information, and user-space programs will receive
2288 notification of APM "events" (e.g. battery status change).
2290 If you select "Y" here, you can disable actual use of the APM
2291 BIOS by passing the "apm=off" option to the kernel at boot time.
2293 Note that the APM support is almost completely disabled for
2294 machines with more than one CPU.
2296 In order to use APM, you will need supporting software. For location
2297 and more information, read <file:Documentation/power/apm-acpi.txt>
2298 and the Battery Powered Linux mini-HOWTO, available from
2299 <http://www.tldp.org/docs.html#howto>.
2301 This driver does not spin down disk drives (see the hdparm(8)
2302 manpage ("man 8 hdparm") for that), and it doesn't turn off
2303 VESA-compliant "green" monitors.
2305 This driver does not support the TI 4000M TravelMate and the ACER
2306 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2307 desktop machines also don't have compliant BIOSes, and this driver
2308 may cause those machines to panic during the boot phase.
2310 Generally, if you don't have a battery in your machine, there isn't
2311 much point in using this driver and you should say N. If you get
2312 random kernel OOPSes or reboots that don't seem to be related to
2313 anything, try disabling/enabling this option (or disabling/enabling
2316 Some other things you should try when experiencing seemingly random,
2319 1) make sure that you have enough swap space and that it is
2321 2) pass the "no-hlt" option to the kernel
2322 3) switch on floating point emulation in the kernel and pass
2323 the "no387" option to the kernel
2324 4) pass the "floppy=nodma" option to the kernel
2325 5) pass the "mem=4M" option to the kernel (thereby disabling
2326 all but the first 4 MB of RAM)
2327 6) make sure that the CPU is not over clocked.
2328 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2329 8) disable the cache from your BIOS settings
2330 9) install a fan for the video card or exchange video RAM
2331 10) install a better fan for the CPU
2332 11) exchange RAM chips
2333 12) exchange the motherboard.
2335 To compile this driver as a module, choose M here: the
2336 module will be called apm.
2340 config APM_IGNORE_USER_SUSPEND
2341 bool "Ignore USER SUSPEND"
2343 This option will ignore USER SUSPEND requests. On machines with a
2344 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2345 series notebooks, it is necessary to say Y because of a BIOS bug.
2347 config APM_DO_ENABLE
2348 bool "Enable PM at boot time"
2350 Enable APM features at boot time. From page 36 of the APM BIOS
2351 specification: "When disabled, the APM BIOS does not automatically
2352 power manage devices, enter the Standby State, enter the Suspend
2353 State, or take power saving steps in response to CPU Idle calls."
2354 This driver will make CPU Idle calls when Linux is idle (unless this
2355 feature is turned off -- see "Do CPU IDLE calls", below). This
2356 should always save battery power, but more complicated APM features
2357 will be dependent on your BIOS implementation. You may need to turn
2358 this option off if your computer hangs at boot time when using APM
2359 support, or if it beeps continuously instead of suspending. Turn
2360 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2361 T400CDT. This is off by default since most machines do fine without
2366 bool "Make CPU Idle calls when idle"
2368 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2369 On some machines, this can activate improved power savings, such as
2370 a slowed CPU clock rate, when the machine is idle. These idle calls
2371 are made after the idle loop has run for some length of time (e.g.,
2372 333 mS). On some machines, this will cause a hang at boot time or
2373 whenever the CPU becomes idle. (On machines with more than one CPU,
2374 this option does nothing.)
2376 config APM_DISPLAY_BLANK
2377 bool "Enable console blanking using APM"
2379 Enable console blanking using the APM. Some laptops can use this to
2380 turn off the LCD backlight when the screen blanker of the Linux
2381 virtual console blanks the screen. Note that this is only used by
2382 the virtual console screen blanker, and won't turn off the backlight
2383 when using the X Window system. This also doesn't have anything to
2384 do with your VESA-compliant power-saving monitor. Further, this
2385 option doesn't work for all laptops -- it might not turn off your
2386 backlight at all, or it might print a lot of errors to the console,
2387 especially if you are using gpm.
2389 config APM_ALLOW_INTS
2390 bool "Allow interrupts during APM BIOS calls"
2392 Normally we disable external interrupts while we are making calls to
2393 the APM BIOS as a measure to lessen the effects of a badly behaving
2394 BIOS implementation. The BIOS should reenable interrupts if it
2395 needs to. Unfortunately, some BIOSes do not -- especially those in
2396 many of the newer IBM Thinkpads. If you experience hangs when you
2397 suspend, try setting this to Y. Otherwise, say N.
2401 source "drivers/cpufreq/Kconfig"
2403 source "drivers/cpuidle/Kconfig"
2405 source "drivers/idle/Kconfig"
2410 menu "Bus options (PCI etc.)"
2416 Find out whether you have a PCI motherboard. PCI is the name of a
2417 bus system, i.e. the way the CPU talks to the other stuff inside
2418 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2419 VESA. If you have PCI, say Y, otherwise N.
2422 prompt "PCI access mode"
2423 depends on X86_32 && PCI
2426 On PCI systems, the BIOS can be used to detect the PCI devices and
2427 determine their configuration. However, some old PCI motherboards
2428 have BIOS bugs and may crash if this is done. Also, some embedded
2429 PCI-based systems don't have any BIOS at all. Linux can also try to
2430 detect the PCI hardware directly without using the BIOS.
2432 With this option, you can specify how Linux should detect the
2433 PCI devices. If you choose "BIOS", the BIOS will be used,
2434 if you choose "Direct", the BIOS won't be used, and if you
2435 choose "MMConfig", then PCI Express MMCONFIG will be used.
2436 If you choose "Any", the kernel will try MMCONFIG, then the
2437 direct access method and falls back to the BIOS if that doesn't
2438 work. If unsure, go with the default, which is "Any".
2443 config PCI_GOMMCONFIG
2460 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2462 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2465 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2469 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2473 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2477 depends on PCI && XEN
2485 bool "Support mmconfig PCI config space access"
2486 depends on X86_64 && PCI && ACPI
2488 config PCI_CNB20LE_QUIRK
2489 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2492 Read the PCI windows out of the CNB20LE host bridge. This allows
2493 PCI hotplug to work on systems with the CNB20LE chipset which do
2496 There's no public spec for this chipset, and this functionality
2497 is known to be incomplete.
2499 You should say N unless you know you need this.
2501 source "drivers/pci/Kconfig"
2504 bool "ISA-style bus support on modern systems" if EXPERT
2507 Enables ISA-style drivers on modern systems. This is necessary to
2508 support PC/104 devices on X86_64 platforms.
2512 # x86_64 have no ISA slots, but can have ISA-style DMA.
2514 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2517 Enables ISA-style DMA support for devices requiring such controllers.
2525 Find out whether you have ISA slots on your motherboard. ISA is the
2526 name of a bus system, i.e. the way the CPU talks to the other stuff
2527 inside your box. Other bus systems are PCI, EISA, MicroChannel
2528 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2529 newer boards don't support it. If you have ISA, say Y, otherwise N.
2535 The Extended Industry Standard Architecture (EISA) bus was
2536 developed as an open alternative to the IBM MicroChannel bus.
2538 The EISA bus provided some of the features of the IBM MicroChannel
2539 bus while maintaining backward compatibility with cards made for
2540 the older ISA bus. The EISA bus saw limited use between 1988 and
2541 1995 when it was made obsolete by the PCI bus.
2543 Say Y here if you are building a kernel for an EISA-based machine.
2547 source "drivers/eisa/Kconfig"
2550 tristate "NatSemi SCx200 support"
2552 This provides basic support for National Semiconductor's
2553 (now AMD's) Geode processors. The driver probes for the
2554 PCI-IDs of several on-chip devices, so its a good dependency
2555 for other scx200_* drivers.
2557 If compiled as a module, the driver is named scx200.
2559 config SCx200HR_TIMER
2560 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2564 This driver provides a clocksource built upon the on-chip
2565 27MHz high-resolution timer. Its also a workaround for
2566 NSC Geode SC-1100's buggy TSC, which loses time when the
2567 processor goes idle (as is done by the scheduler). The
2568 other workaround is idle=poll boot option.
2571 bool "One Laptop Per Child support"
2578 Add support for detecting the unique features of the OLPC
2582 bool "OLPC XO-1 Power Management"
2583 depends on OLPC && MFD_CS5535 && PM_SLEEP
2586 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2589 bool "OLPC XO-1 Real Time Clock"
2590 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2592 Add support for the XO-1 real time clock, which can be used as a
2593 programmable wakeup source.
2596 bool "OLPC XO-1 SCI extras"
2597 depends on OLPC && OLPC_XO1_PM
2603 Add support for SCI-based features of the OLPC XO-1 laptop:
2604 - EC-driven system wakeups
2608 - AC adapter status updates
2609 - Battery status updates
2611 config OLPC_XO15_SCI
2612 bool "OLPC XO-1.5 SCI extras"
2613 depends on OLPC && ACPI
2616 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2617 - EC-driven system wakeups
2618 - AC adapter status updates
2619 - Battery status updates
2622 bool "PCEngines ALIX System Support (LED setup)"
2625 This option enables system support for the PCEngines ALIX.
2626 At present this just sets up LEDs for GPIO control on
2627 ALIX2/3/6 boards. However, other system specific setup should
2630 Note: You must still enable the drivers for GPIO and LED support
2631 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2633 Note: You have to set alix.force=1 for boards with Award BIOS.
2636 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2639 This option enables system support for the Soekris Engineering net5501.
2642 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2646 This option enables system support for the Traverse Technologies GEOS.
2649 bool "Technologic Systems TS-5500 platform support"
2651 select CHECK_SIGNATURE
2655 This option enables system support for the Technologic Systems TS-5500.
2661 depends on CPU_SUP_AMD && PCI
2663 source "drivers/pcmcia/Kconfig"
2666 tristate "RapidIO support"
2670 If enabled this option will include drivers and the core
2671 infrastructure code to support RapidIO interconnect devices.
2673 source "drivers/rapidio/Kconfig"
2676 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2678 Firmwares often provide initial graphics framebuffers so the BIOS,
2679 bootloader or kernel can show basic video-output during boot for
2680 user-guidance and debugging. Historically, x86 used the VESA BIOS
2681 Extensions and EFI-framebuffers for this, which are mostly limited
2683 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2684 framebuffers so the new generic system-framebuffer drivers can be
2685 used on x86. If the framebuffer is not compatible with the generic
2686 modes, it is adverticed as fallback platform framebuffer so legacy
2687 drivers like efifb, vesafb and uvesafb can pick it up.
2688 If this option is not selected, all system framebuffers are always
2689 marked as fallback platform framebuffers as usual.
2691 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2692 not be able to pick up generic system framebuffers if this option
2693 is selected. You are highly encouraged to enable simplefb as
2694 replacement if you select this option. simplefb can correctly deal
2695 with generic system framebuffers. But you should still keep vesafb
2696 and others enabled as fallback if a system framebuffer is
2697 incompatible with simplefb.
2704 menu "Executable file formats / Emulations"
2706 source "fs/Kconfig.binfmt"
2708 config IA32_EMULATION
2709 bool "IA32 Emulation"
2712 select COMPAT_BINFMT_ELF
2713 select ARCH_WANT_OLD_COMPAT_IPC
2715 Include code to run legacy 32-bit programs under a
2716 64-bit kernel. You should likely turn this on, unless you're
2717 100% sure that you don't have any 32-bit programs left.
2720 tristate "IA32 a.out support"
2721 depends on IA32_EMULATION
2723 Support old a.out binaries in the 32bit emulation.
2726 bool "x32 ABI for 64-bit mode"
2729 Include code to run binaries for the x32 native 32-bit ABI
2730 for 64-bit processors. An x32 process gets access to the
2731 full 64-bit register file and wide data path while leaving
2732 pointers at 32 bits for smaller memory footprint.
2734 You will need a recent binutils (2.22 or later) with
2735 elf32_x86_64 support enabled to compile a kernel with this
2740 depends on IA32_EMULATION || X86_X32
2743 config COMPAT_FOR_U64_ALIGNMENT
2746 config SYSVIPC_COMPAT
2754 config HAVE_ATOMIC_IOMAP
2758 config X86_DEV_DMA_OPS
2760 depends on X86_64 || STA2X11
2762 config X86_DMA_REMAP
2766 source "net/Kconfig"
2768 source "drivers/Kconfig"
2770 source "drivers/firmware/Kconfig"
2774 source "arch/x86/Kconfig.debug"
2776 source "security/Kconfig"
2778 source "crypto/Kconfig"
2780 source "arch/x86/kvm/Kconfig"
2782 source "lib/Kconfig"