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
12 # Options that are inherently 32-bit kernel only:
13 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLONE_BACKWARDS
17 select HAVE_GENERIC_DMA_COHERENT
18 select MODULES_USE_ELF_REL
24 # Options that are inherently 64-bit kernel only:
25 select ARCH_HAS_GIGANTIC_PAGE
26 select ARCH_SUPPORTS_INT128
27 select ARCH_USE_CMPXCHG_LOCKREF
28 select HAVE_ARCH_SOFT_DIRTY
29 select MODULES_USE_ELF_RELA
30 select X86_DEV_DMA_OPS
35 # ( Note that options that are marked 'if X86_64' could in principle be
36 # ported to 32-bit as well. )
41 # Note: keep this list sorted alphabetically
43 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
44 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
46 select ARCH_CLOCKSOURCE_DATA
47 select ARCH_DISCARD_MEMBLOCK
48 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
49 select ARCH_HAS_DEVMEM_IS_ALLOWED
50 select ARCH_HAS_ELF_RANDOMIZE
51 select ARCH_HAS_FAST_MULTIPLIER
52 select ARCH_HAS_GCOV_PROFILE_ALL
53 select ARCH_HAS_KCOV if X86_64
54 select ARCH_HAS_MMIO_FLUSH
55 select ARCH_HAS_PMEM_API if X86_64
56 select ARCH_HAS_SG_CHAIN
57 select ARCH_HAS_UBSAN_SANITIZE_ALL
58 select ARCH_HAVE_NMI_SAFE_CMPXCHG
59 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
60 select ARCH_MIGHT_HAVE_PC_PARPORT
61 select ARCH_MIGHT_HAVE_PC_SERIO
62 select ARCH_SUPPORTS_ATOMIC_RMW
63 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
64 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
65 select ARCH_USE_BUILTIN_BSWAP
66 select ARCH_USE_QUEUED_RWLOCKS
67 select ARCH_USE_QUEUED_SPINLOCKS
68 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
69 select ARCH_WANT_FRAME_POINTERS
70 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
71 select BUILDTIME_EXTABLE_SORT
73 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
74 select CLOCKSOURCE_WATCHDOG
75 select DCACHE_WORD_ACCESS
76 select EDAC_ATOMIC_SCRUB
78 select GENERIC_CLOCKEVENTS
79 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
80 select GENERIC_CLOCKEVENTS_MIN_ADJUST
81 select GENERIC_CMOS_UPDATE
82 select GENERIC_CPU_AUTOPROBE
83 select GENERIC_EARLY_IOREMAP
84 select GENERIC_FIND_FIRST_BIT
86 select GENERIC_IRQ_PROBE
87 select GENERIC_IRQ_SHOW
88 select GENERIC_PENDING_IRQ if SMP
89 select GENERIC_SMP_IDLE_THREAD
90 select GENERIC_STRNCPY_FROM_USER
91 select GENERIC_STRNLEN_USER
92 select GENERIC_TIME_VSYSCALL
93 select HAVE_ACPI_APEI if ACPI
94 select HAVE_ACPI_APEI_NMI if ACPI
95 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
96 select HAVE_ARCH_AUDITSYSCALL
97 select HAVE_ARCH_HARDENED_USERCOPY
98 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
99 select HAVE_ARCH_JUMP_LABEL
100 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
101 select HAVE_ARCH_KGDB
102 select HAVE_ARCH_KMEMCHECK
103 select HAVE_ARCH_MMAP_RND_BITS if MMU
104 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
105 select HAVE_ARCH_SECCOMP_FILTER
106 select HAVE_ARCH_TRACEHOOK
107 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
108 select HAVE_ARCH_VMAP_STACK if X86_64
109 select HAVE_ARCH_WITHIN_STACK_FRAMES
110 select HAVE_CC_STACKPROTECTOR
111 select HAVE_CMPXCHG_DOUBLE
112 select HAVE_CMPXCHG_LOCAL
113 select HAVE_CONTEXT_TRACKING if X86_64
114 select HAVE_COPY_THREAD_TLS
115 select HAVE_C_RECORDMCOUNT
116 select HAVE_DEBUG_KMEMLEAK
117 select HAVE_DEBUG_STACKOVERFLOW
118 select HAVE_DMA_API_DEBUG
119 select HAVE_DMA_CONTIGUOUS
120 select HAVE_DYNAMIC_FTRACE
121 select HAVE_DYNAMIC_FTRACE_WITH_REGS
122 select HAVE_EBPF_JIT if X86_64
123 select HAVE_EFFICIENT_UNALIGNED_ACCESS
124 select HAVE_EXIT_THREAD
125 select HAVE_FENTRY if X86_64
126 select HAVE_FTRACE_MCOUNT_RECORD
127 select HAVE_FUNCTION_GRAPH_TRACER
128 select HAVE_FUNCTION_TRACER
129 select HAVE_GCC_PLUGINS
130 select HAVE_HW_BREAKPOINT
132 select HAVE_IOREMAP_PROT
133 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
134 select HAVE_IRQ_TIME_ACCOUNTING
135 select HAVE_KERNEL_BZIP2
136 select HAVE_KERNEL_GZIP
137 select HAVE_KERNEL_LZ4
138 select HAVE_KERNEL_LZMA
139 select HAVE_KERNEL_LZO
140 select HAVE_KERNEL_XZ
142 select HAVE_KPROBES_ON_FTRACE
143 select HAVE_KRETPROBES
145 select HAVE_LIVEPATCH if X86_64
147 select HAVE_MEMBLOCK_NODE_MAP
148 select HAVE_MIXED_BREAKPOINTS_REGS
151 select HAVE_OPTPROBES
152 select HAVE_PCSPKR_PLATFORM
153 select HAVE_PERF_EVENTS
154 select HAVE_PERF_EVENTS_NMI
155 select HAVE_PERF_REGS
156 select HAVE_PERF_USER_STACK_DUMP
157 select HAVE_REGS_AND_STACK_ACCESS_API
158 select HAVE_STACK_VALIDATION if X86_64
159 select HAVE_SYSCALL_TRACEPOINTS
160 select HAVE_UNSTABLE_SCHED_CLOCK
161 select HAVE_USER_RETURN_NOTIFIER
162 select IRQ_FORCED_THREADING
165 select RTC_MC146818_LIB
168 select SYSCTL_EXCEPTION_TRACE
169 select THREAD_INFO_IN_TASK
170 select USER_STACKTRACE_SUPPORT
172 select X86_FEATURE_NAMES if PROC_FS
174 config INSTRUCTION_DECODER
176 depends on KPROBES || PERF_EVENTS || UPROBES
180 default "elf32-i386" if X86_32
181 default "elf64-x86-64" if X86_64
183 config ARCH_DEFCONFIG
185 default "arch/x86/configs/i386_defconfig" if X86_32
186 default "arch/x86/configs/x86_64_defconfig" if X86_64
188 config LOCKDEP_SUPPORT
191 config STACKTRACE_SUPPORT
197 config ARCH_MMAP_RND_BITS_MIN
201 config ARCH_MMAP_RND_BITS_MAX
205 config ARCH_MMAP_RND_COMPAT_BITS_MIN
208 config ARCH_MMAP_RND_COMPAT_BITS_MAX
214 config NEED_DMA_MAP_STATE
216 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
218 config NEED_SG_DMA_LENGTH
221 config GENERIC_ISA_DMA
223 depends on ISA_DMA_API
228 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
230 config GENERIC_BUG_RELATIVE_POINTERS
233 config GENERIC_HWEIGHT
236 config ARCH_MAY_HAVE_PC_FDC
238 depends on ISA_DMA_API
240 config RWSEM_XCHGADD_ALGORITHM
243 config GENERIC_CALIBRATE_DELAY
246 config ARCH_HAS_CPU_RELAX
249 config ARCH_HAS_CACHE_LINE_SIZE
252 config HAVE_SETUP_PER_CPU_AREA
255 config NEED_PER_CPU_EMBED_FIRST_CHUNK
258 config NEED_PER_CPU_PAGE_FIRST_CHUNK
261 config ARCH_HIBERNATION_POSSIBLE
264 config ARCH_SUSPEND_POSSIBLE
267 config ARCH_WANT_HUGE_PMD_SHARE
270 config ARCH_WANT_GENERAL_HUGETLB
279 config ARCH_SUPPORTS_OPTIMIZED_INLINING
282 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
285 config KASAN_SHADOW_OFFSET
288 default 0xdffffc0000000000
290 config HAVE_INTEL_TXT
292 depends on INTEL_IOMMU && ACPI
296 depends on X86_32 && SMP
300 depends on X86_64 && SMP
302 config X86_32_LAZY_GS
304 depends on X86_32 && !CC_STACKPROTECTOR
306 config ARCH_SUPPORTS_UPROBES
309 config FIX_EARLYCON_MEM
315 config PGTABLE_LEVELS
321 source "init/Kconfig"
322 source "kernel/Kconfig.freezer"
324 menu "Processor type and features"
327 bool "DMA memory allocation support" if EXPERT
330 DMA memory allocation support allows devices with less than 32-bit
331 addressing to allocate within the first 16MB of address space.
332 Disable if no such devices will be used.
337 bool "Symmetric multi-processing support"
339 This enables support for systems with more than one CPU. If you have
340 a system with only one CPU, say N. If you have a system with more
343 If you say N here, the kernel will run on uni- and multiprocessor
344 machines, but will use only one CPU of a multiprocessor machine. If
345 you say Y here, the kernel will run on many, but not all,
346 uniprocessor machines. On a uniprocessor machine, the kernel
347 will run faster if you say N here.
349 Note that if you say Y here and choose architecture "586" or
350 "Pentium" under "Processor family", the kernel will not work on 486
351 architectures. Similarly, multiprocessor kernels for the "PPro"
352 architecture may not work on all Pentium based boards.
354 People using multiprocessor machines who say Y here should also say
355 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
356 Management" code will be disabled if you say Y here.
358 See also <file:Documentation/x86/i386/IO-APIC.txt>,
359 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
360 <http://www.tldp.org/docs.html#howto>.
362 If you don't know what to do here, say N.
364 config X86_FEATURE_NAMES
365 bool "Processor feature human-readable names" if EMBEDDED
368 This option compiles in a table of x86 feature bits and corresponding
369 names. This is required to support /proc/cpuinfo and a few kernel
370 messages. You can disable this to save space, at the expense of
371 making those few kernel messages show numeric feature bits instead.
375 config X86_FAST_FEATURE_TESTS
376 bool "Fast CPU feature tests" if EMBEDDED
379 Some fast-paths in the kernel depend on the capabilities of the CPU.
380 Say Y here for the kernel to patch in the appropriate code at runtime
381 based on the capabilities of the CPU. The infrastructure for patching
382 code at runtime takes up some additional space; space-constrained
383 embedded systems may wish to say N here to produce smaller, slightly
387 bool "Support x2apic"
388 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
390 This enables x2apic support on CPUs that have this feature.
392 This allows 32-bit apic IDs (so it can support very large systems),
393 and accesses the local apic via MSRs not via mmio.
395 If you don't know what to do here, say N.
398 bool "Enable MPS table" if ACPI || SFI
400 depends on X86_LOCAL_APIC
402 For old smp systems that do not have proper acpi support. Newer systems
403 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
406 bool "Support for big SMP systems with more than 8 CPUs"
407 depends on X86_32 && SMP
409 This option is needed for the systems that have more than 8 CPUs
413 depends on X86_GOLDFISH
416 bool "Intel Resource Director Technology Allocation support"
418 depends on X86 && CPU_SUP_INTEL
421 Select to enable resource allocation which is a sub-feature of
422 Intel Resource Director Technology(RDT). More information about
423 RDT can be found in the Intel x86 Architecture Software
429 config X86_EXTENDED_PLATFORM
430 bool "Support for extended (non-PC) x86 platforms"
433 If you disable this option then the kernel will only support
434 standard PC platforms. (which covers the vast majority of
437 If you enable this option then you'll be able to select support
438 for the following (non-PC) 32 bit x86 platforms:
439 Goldfish (Android emulator)
442 SGI 320/540 (Visual Workstation)
443 STA2X11-based (e.g. Northville)
444 Moorestown MID devices
446 If you have one of these systems, or if you want to build a
447 generic distribution kernel, say Y here - otherwise say N.
451 config X86_EXTENDED_PLATFORM
452 bool "Support for extended (non-PC) x86 platforms"
455 If you disable this option then the kernel will only support
456 standard PC platforms. (which covers the vast majority of
459 If you enable this option then you'll be able to select support
460 for the following (non-PC) 64 bit x86 platforms:
465 If you have one of these systems, or if you want to build a
466 generic distribution kernel, say Y here - otherwise say N.
468 # This is an alphabetically sorted list of 64 bit extended platforms
469 # Please maintain the alphabetic order if and when there are additions
471 bool "Numascale NumaChip"
473 depends on X86_EXTENDED_PLATFORM
476 depends on X86_X2APIC
477 depends on PCI_MMCONFIG
479 Adds support for Numascale NumaChip large-SMP systems. Needed to
480 enable more than ~168 cores.
481 If you don't have one of these, you should say N here.
485 select HYPERVISOR_GUEST
487 depends on X86_64 && PCI
488 depends on X86_EXTENDED_PLATFORM
491 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
492 supposed to run on these EM64T-based machines. Only choose this option
493 if you have one of these machines.
496 bool "SGI Ultraviolet"
498 depends on X86_EXTENDED_PLATFORM
501 depends on X86_X2APIC
504 This option is needed in order to support SGI Ultraviolet systems.
505 If you don't have one of these, you should say N here.
507 # Following is an alphabetically sorted list of 32 bit extended platforms
508 # Please maintain the alphabetic order if and when there are additions
511 bool "Goldfish (Virtual Platform)"
512 depends on X86_EXTENDED_PLATFORM
514 Enable support for the Goldfish virtual platform used primarily
515 for Android development. Unless you are building for the Android
516 Goldfish emulator say N here.
519 bool "CE4100 TV platform"
521 depends on PCI_GODIRECT
522 depends on X86_IO_APIC
524 depends on X86_EXTENDED_PLATFORM
525 select X86_REBOOTFIXUPS
527 select OF_EARLY_FLATTREE
529 Select for the Intel CE media processor (CE4100) SOC.
530 This option compiles in support for the CE4100 SOC for settop
531 boxes and media devices.
534 bool "Intel MID platform support"
535 depends on X86_EXTENDED_PLATFORM
536 depends on X86_PLATFORM_DEVICES
538 depends on X86_64 || (PCI_GOANY && X86_32)
539 depends on X86_IO_APIC
545 select MFD_INTEL_MSIC
547 Select to build a kernel capable of supporting Intel MID (Mobile
548 Internet Device) platform systems which do not have the PCI legacy
549 interfaces. If you are building for a PC class system say N here.
551 Intel MID platforms are based on an Intel processor and chipset which
552 consume less power than most of the x86 derivatives.
554 config X86_INTEL_QUARK
555 bool "Intel Quark platform support"
557 depends on X86_EXTENDED_PLATFORM
558 depends on X86_PLATFORM_DEVICES
562 depends on X86_IO_APIC
567 Select to include support for Quark X1000 SoC.
568 Say Y here if you have a Quark based system such as the Arduino
569 compatible Intel Galileo.
571 config X86_INTEL_LPSS
572 bool "Intel Low Power Subsystem Support"
573 depends on X86 && ACPI
578 Select to build support for Intel Low Power Subsystem such as
579 found on Intel Lynxpoint PCH. Selecting this option enables
580 things like clock tree (common clock framework) and pincontrol
581 which are needed by the LPSS peripheral drivers.
583 config X86_AMD_PLATFORM_DEVICE
584 bool "AMD ACPI2Platform devices support"
589 Select to interpret AMD specific ACPI device to platform device
590 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
591 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
592 implemented under PINCTRL subsystem.
595 tristate "Intel SoC IOSF Sideband support for SoC platforms"
598 This option enables sideband register access support for Intel SoC
599 platforms. On these platforms the IOSF sideband is used in lieu of
600 MSR's for some register accesses, mostly but not limited to thermal
601 and power. Drivers may query the availability of this device to
602 determine if they need the sideband in order to work on these
603 platforms. The sideband is available on the following SoC products.
604 This list is not meant to be exclusive.
609 You should say Y if you are running a kernel on one of these SoC's.
611 config IOSF_MBI_DEBUG
612 bool "Enable IOSF sideband access through debugfs"
613 depends on IOSF_MBI && DEBUG_FS
615 Select this option to expose the IOSF sideband access registers (MCR,
616 MDR, MCRX) through debugfs to write and read register information from
617 different units on the SoC. This is most useful for obtaining device
618 state information for debug and analysis. As this is a general access
619 mechanism, users of this option would have specific knowledge of the
620 device they want to access.
622 If you don't require the option or are in doubt, say N.
625 bool "RDC R-321x SoC"
627 depends on X86_EXTENDED_PLATFORM
629 select X86_REBOOTFIXUPS
631 This option is needed for RDC R-321x system-on-chip, also known
633 If you don't have one of these chips, you should say N here.
635 config X86_32_NON_STANDARD
636 bool "Support non-standard 32-bit SMP architectures"
637 depends on X86_32 && SMP
638 depends on X86_EXTENDED_PLATFORM
640 This option compiles in the bigsmp and STA2X11 default
641 subarchitectures. It is intended for a generic binary
642 kernel. If you select them all, kernel will probe it one by
643 one and will fallback to default.
645 # Alphabetically sorted list of Non standard 32 bit platforms
647 config X86_SUPPORTS_MEMORY_FAILURE
649 # MCE code calls memory_failure():
651 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
652 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
653 depends on X86_64 || !SPARSEMEM
654 select ARCH_SUPPORTS_MEMORY_FAILURE
657 bool "STA2X11 Companion Chip Support"
658 depends on X86_32_NON_STANDARD && PCI
659 select X86_DEV_DMA_OPS
666 This adds support for boards based on the STA2X11 IO-Hub,
667 a.k.a. "ConneXt". The chip is used in place of the standard
668 PC chipset, so all "standard" peripherals are missing. If this
669 option is selected the kernel will still be able to boot on
670 standard PC machines.
673 tristate "Eurobraille/Iris poweroff module"
676 The Iris machines from EuroBraille do not have APM or ACPI support
677 to shut themselves down properly. A special I/O sequence is
678 needed to do so, which is what this module does at
681 This is only for Iris machines from EuroBraille.
685 config SCHED_OMIT_FRAME_POINTER
687 prompt "Single-depth WCHAN output"
690 Calculate simpler /proc/<PID>/wchan values. If this option
691 is disabled then wchan values will recurse back to the
692 caller function. This provides more accurate wchan values,
693 at the expense of slightly more scheduling overhead.
695 If in doubt, say "Y".
697 menuconfig HYPERVISOR_GUEST
698 bool "Linux guest support"
700 Say Y here to enable options for running Linux under various hyper-
701 visors. This option enables basic hypervisor detection and platform
704 If you say N, all options in this submenu will be skipped and
705 disabled, and Linux guest support won't be built in.
710 bool "Enable paravirtualization code"
712 This changes the kernel so it can modify itself when it is run
713 under a hypervisor, potentially improving performance significantly
714 over full virtualization. However, when run without a hypervisor
715 the kernel is theoretically slower and slightly larger.
717 config PARAVIRT_DEBUG
718 bool "paravirt-ops debugging"
719 depends on PARAVIRT && DEBUG_KERNEL
721 Enable to debug paravirt_ops internals. Specifically, BUG if
722 a paravirt_op is missing when it is called.
724 config PARAVIRT_SPINLOCKS
725 bool "Paravirtualization layer for spinlocks"
726 depends on PARAVIRT && SMP
728 Paravirtualized spinlocks allow a pvops backend to replace the
729 spinlock implementation with something virtualization-friendly
730 (for example, block the virtual CPU rather than spinning).
732 It has a minimal impact on native kernels and gives a nice performance
733 benefit on paravirtualized KVM / Xen kernels.
735 If you are unsure how to answer this question, answer Y.
737 config QUEUED_LOCK_STAT
738 bool "Paravirt queued spinlock statistics"
739 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
741 Enable the collection of statistical data on the slowpath
742 behavior of paravirtualized queued spinlocks and report
745 source "arch/x86/xen/Kconfig"
748 bool "KVM Guest support (including kvmclock)"
750 select PARAVIRT_CLOCK
753 This option enables various optimizations for running under the KVM
754 hypervisor. It includes a paravirtualized clock, so that instead
755 of relying on a PIT (or probably other) emulation by the
756 underlying device model, the host provides the guest with
757 timing infrastructure such as time of day, and system time
760 bool "Enable debug information for KVM Guests in debugfs"
761 depends on KVM_GUEST && DEBUG_FS
764 This option enables collection of various statistics for KVM guest.
765 Statistics are displayed in debugfs filesystem. Enabling this option
766 may incur significant overhead.
768 source "arch/x86/lguest/Kconfig"
770 config PARAVIRT_TIME_ACCOUNTING
771 bool "Paravirtual steal time accounting"
775 Select this option to enable fine granularity task steal time
776 accounting. Time spent executing other tasks in parallel with
777 the current vCPU is discounted from the vCPU power. To account for
778 that, there can be a small performance impact.
780 If in doubt, say N here.
782 config PARAVIRT_CLOCK
785 endif #HYPERVISOR_GUEST
790 source "arch/x86/Kconfig.cpu"
794 prompt "HPET Timer Support" if X86_32
796 Use the IA-PC HPET (High Precision Event Timer) to manage
797 time in preference to the PIT and RTC, if a HPET is
799 HPET is the next generation timer replacing legacy 8254s.
800 The HPET provides a stable time base on SMP
801 systems, unlike the TSC, but it is more expensive to access,
802 as it is off-chip. The interface used is documented
803 in the HPET spec, revision 1.
805 You can safely choose Y here. However, HPET will only be
806 activated if the platform and the BIOS support this feature.
807 Otherwise the 8254 will be used for timing services.
809 Choose N to continue using the legacy 8254 timer.
811 config HPET_EMULATE_RTC
813 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
816 def_bool y if X86_INTEL_MID
817 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
819 depends on X86_INTEL_MID && SFI
821 APB timer is the replacement for 8254, HPET on X86 MID platforms.
822 The APBT provides a stable time base on SMP
823 systems, unlike the TSC, but it is more expensive to access,
824 as it is off-chip. APB timers are always running regardless of CPU
825 C states, they are used as per CPU clockevent device when possible.
827 # Mark as expert because too many people got it wrong.
828 # The code disables itself when not needed.
831 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
832 bool "Enable DMI scanning" if EXPERT
834 Enabled scanning of DMI to identify machine quirks. Say Y
835 here unless you have verified that your setup is not
836 affected by entries in the DMI blacklist. Required by PNP
840 bool "Old AMD GART IOMMU support"
842 depends on X86_64 && PCI && AMD_NB
844 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
845 GART based hardware IOMMUs.
847 The GART supports full DMA access for devices with 32-bit access
848 limitations, on systems with more than 3 GB. This is usually needed
849 for USB, sound, many IDE/SATA chipsets and some other devices.
851 Newer systems typically have a modern AMD IOMMU, supported via
852 the CONFIG_AMD_IOMMU=y config option.
854 In normal configurations this driver is only active when needed:
855 there's more than 3 GB of memory and the system contains a
856 32-bit limited device.
861 bool "IBM Calgary IOMMU support"
863 depends on X86_64 && PCI
865 Support for hardware IOMMUs in IBM's xSeries x366 and x460
866 systems. Needed to run systems with more than 3GB of memory
867 properly with 32-bit PCI devices that do not support DAC
868 (Double Address Cycle). Calgary also supports bus level
869 isolation, where all DMAs pass through the IOMMU. This
870 prevents them from going anywhere except their intended
871 destination. This catches hard-to-find kernel bugs and
872 mis-behaving drivers and devices that do not use the DMA-API
873 properly to set up their DMA buffers. The IOMMU can be
874 turned off at boot time with the iommu=off parameter.
875 Normally the kernel will make the right choice by itself.
878 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
880 prompt "Should Calgary be enabled by default?"
881 depends on CALGARY_IOMMU
883 Should Calgary be enabled by default? if you choose 'y', Calgary
884 will be used (if it exists). If you choose 'n', Calgary will not be
885 used even if it exists. If you choose 'n' and would like to use
886 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
889 # need this always selected by IOMMU for the VIA workaround
893 Support for software bounce buffers used on x86-64 systems
894 which don't have a hardware IOMMU. Using this PCI devices
895 which can only access 32-bits of memory can be used on systems
896 with more than 3 GB of memory.
901 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
904 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
905 depends on X86_64 && SMP && DEBUG_KERNEL
906 select CPUMASK_OFFSTACK
908 Enable maximum number of CPUS and NUMA Nodes for this architecture.
912 int "Maximum number of CPUs" if SMP && !MAXSMP
913 range 2 8 if SMP && X86_32 && !X86_BIGSMP
914 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
915 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
917 default "8192" if MAXSMP
918 default "32" if SMP && X86_BIGSMP
919 default "8" if SMP && X86_32
922 This allows you to specify the maximum number of CPUs which this
923 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
924 supported value is 8192, otherwise the maximum value is 512. The
925 minimum value which makes sense is 2.
927 This is purely to save memory - each supported CPU adds
928 approximately eight kilobytes to the kernel image.
931 bool "SMT (Hyperthreading) scheduler support"
934 SMT scheduler support improves the CPU scheduler's decision making
935 when dealing with Intel Pentium 4 chips with HyperThreading at a
936 cost of slightly increased overhead in some places. If unsure say
941 prompt "Multi-core scheduler support"
944 Multi-core scheduler support improves the CPU scheduler's decision
945 making when dealing with multi-core CPU chips at a cost of slightly
946 increased overhead in some places. If unsure say N here.
949 bool "CPU core priorities scheduler support"
950 depends on SCHED_MC && CPU_SUP_INTEL
951 select X86_INTEL_PSTATE
955 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
956 core ordering determined at manufacturing time, which allows
957 certain cores to reach higher turbo frequencies (when running
958 single threaded workloads) than others.
960 Enabling this kernel feature teaches the scheduler about
961 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
962 scheduler's CPU selection logic accordingly, so that higher
963 overall system performance can be achieved.
965 This feature will have no effect on CPUs without this feature.
967 If unsure say Y here.
969 source "kernel/Kconfig.preempt"
973 depends on !SMP && X86_LOCAL_APIC
976 bool "Local APIC support on uniprocessors" if !PCI_MSI
978 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
980 A local APIC (Advanced Programmable Interrupt Controller) is an
981 integrated interrupt controller in the CPU. If you have a single-CPU
982 system which has a processor with a local APIC, you can say Y here to
983 enable and use it. If you say Y here even though your machine doesn't
984 have a local APIC, then the kernel will still run with no slowdown at
985 all. The local APIC supports CPU-generated self-interrupts (timer,
986 performance counters), and the NMI watchdog which detects hard
990 bool "IO-APIC support on uniprocessors"
991 depends on X86_UP_APIC
993 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
994 SMP-capable replacement for PC-style interrupt controllers. Most
995 SMP systems and many recent uniprocessor systems have one.
997 If you have a single-CPU system with an IO-APIC, you can say Y here
998 to use it. If you say Y here even though your machine doesn't have
999 an IO-APIC, then the kernel will still run with no slowdown at all.
1001 config X86_LOCAL_APIC
1003 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1004 select IRQ_DOMAIN_HIERARCHY
1005 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1009 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1011 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1012 bool "Reroute for broken boot IRQs"
1013 depends on X86_IO_APIC
1015 This option enables a workaround that fixes a source of
1016 spurious interrupts. This is recommended when threaded
1017 interrupt handling is used on systems where the generation of
1018 superfluous "boot interrupts" cannot be disabled.
1020 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1021 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1022 kernel does during interrupt handling). On chipsets where this
1023 boot IRQ generation cannot be disabled, this workaround keeps
1024 the original IRQ line masked so that only the equivalent "boot
1025 IRQ" is delivered to the CPUs. The workaround also tells the
1026 kernel to set up the IRQ handler on the boot IRQ line. In this
1027 way only one interrupt is delivered to the kernel. Otherwise
1028 the spurious second interrupt may cause the kernel to bring
1029 down (vital) interrupt lines.
1031 Only affects "broken" chipsets. Interrupt sharing may be
1032 increased on these systems.
1035 bool "Machine Check / overheating reporting"
1036 select GENERIC_ALLOCATOR
1039 Machine Check support allows the processor to notify the
1040 kernel if it detects a problem (e.g. overheating, data corruption).
1041 The action the kernel takes depends on the severity of the problem,
1042 ranging from warning messages to halting the machine.
1044 config X86_MCE_INTEL
1046 prompt "Intel MCE features"
1047 depends on X86_MCE && X86_LOCAL_APIC
1049 Additional support for intel specific MCE features such as
1050 the thermal monitor.
1054 prompt "AMD MCE features"
1055 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1057 Additional support for AMD specific MCE features such as
1058 the DRAM Error Threshold.
1060 config X86_ANCIENT_MCE
1061 bool "Support for old Pentium 5 / WinChip machine checks"
1062 depends on X86_32 && X86_MCE
1064 Include support for machine check handling on old Pentium 5 or WinChip
1065 systems. These typically need to be enabled explicitly on the command
1068 config X86_MCE_THRESHOLD
1069 depends on X86_MCE_AMD || X86_MCE_INTEL
1072 config X86_MCE_INJECT
1074 tristate "Machine check injector support"
1076 Provide support for injecting machine checks for testing purposes.
1077 If you don't know what a machine check is and you don't do kernel
1078 QA it is safe to say n.
1080 config X86_THERMAL_VECTOR
1082 depends on X86_MCE_INTEL
1084 source "arch/x86/events/Kconfig"
1086 config X86_LEGACY_VM86
1087 bool "Legacy VM86 support"
1091 This option allows user programs to put the CPU into V8086
1092 mode, which is an 80286-era approximation of 16-bit real mode.
1094 Some very old versions of X and/or vbetool require this option
1095 for user mode setting. Similarly, DOSEMU will use it if
1096 available to accelerate real mode DOS programs. However, any
1097 recent version of DOSEMU, X, or vbetool should be fully
1098 functional even without kernel VM86 support, as they will all
1099 fall back to software emulation. Nevertheless, if you are using
1100 a 16-bit DOS program where 16-bit performance matters, vm86
1101 mode might be faster than emulation and you might want to
1104 Note that any app that works on a 64-bit kernel is unlikely to
1105 need this option, as 64-bit kernels don't, and can't, support
1106 V8086 mode. This option is also unrelated to 16-bit protected
1107 mode and is not needed to run most 16-bit programs under Wine.
1109 Enabling this option increases the complexity of the kernel
1110 and slows down exception handling a tiny bit.
1112 If unsure, say N here.
1116 default X86_LEGACY_VM86
1119 bool "Enable support for 16-bit segments" if EXPERT
1121 depends on MODIFY_LDT_SYSCALL
1123 This option is required by programs like Wine to run 16-bit
1124 protected mode legacy code on x86 processors. Disabling
1125 this option saves about 300 bytes on i386, or around 6K text
1126 plus 16K runtime memory on x86-64,
1130 depends on X86_16BIT && X86_32
1134 depends on X86_16BIT && X86_64
1136 config X86_VSYSCALL_EMULATION
1137 bool "Enable vsyscall emulation" if EXPERT
1141 This enables emulation of the legacy vsyscall page. Disabling
1142 it is roughly equivalent to booting with vsyscall=none, except
1143 that it will also disable the helpful warning if a program
1144 tries to use a vsyscall. With this option set to N, offending
1145 programs will just segfault, citing addresses of the form
1148 This option is required by many programs built before 2013, and
1149 care should be used even with newer programs if set to N.
1151 Disabling this option saves about 7K of kernel size and
1152 possibly 4K of additional runtime pagetable memory.
1155 tristate "Toshiba Laptop support"
1158 This adds a driver to safely access the System Management Mode of
1159 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1160 not work on models with a Phoenix BIOS. The System Management Mode
1161 is used to set the BIOS and power saving options on Toshiba portables.
1163 For information on utilities to make use of this driver see the
1164 Toshiba Linux utilities web site at:
1165 <http://www.buzzard.org.uk/toshiba/>.
1167 Say Y if you intend to run this kernel on a Toshiba portable.
1171 tristate "Dell i8k legacy laptop support"
1173 select SENSORS_DELL_SMM
1175 This option enables legacy /proc/i8k userspace interface in hwmon
1176 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1177 temperature and allows controlling fan speeds of Dell laptops via
1178 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1179 it reports also power and hotkey status. For fan speed control is
1180 needed userspace package i8kutils.
1182 Say Y if you intend to run this kernel on old Dell laptops or want to
1183 use userspace package i8kutils.
1186 config X86_REBOOTFIXUPS
1187 bool "Enable X86 board specific fixups for reboot"
1190 This enables chipset and/or board specific fixups to be done
1191 in order to get reboot to work correctly. This is only needed on
1192 some combinations of hardware and BIOS. The symptom, for which
1193 this config is intended, is when reboot ends with a stalled/hung
1196 Currently, the only fixup is for the Geode machines using
1197 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1199 Say Y if you want to enable the fixup. Currently, it's safe to
1200 enable this option even if you don't need it.
1204 bool "CPU microcode loading support"
1206 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1209 If you say Y here, you will be able to update the microcode on
1210 Intel and AMD processors. The Intel support is for the IA32 family,
1211 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1212 AMD support is for families 0x10 and later. You will obviously need
1213 the actual microcode binary data itself which is not shipped with
1216 The preferred method to load microcode from a detached initrd is described
1217 in Documentation/x86/early-microcode.txt. For that you need to enable
1218 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1219 initrd for microcode blobs.
1221 In addition, you can build-in the microcode into the kernel. For that you
1222 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1223 to the CONFIG_EXTRA_FIRMWARE config option.
1225 config MICROCODE_INTEL
1226 bool "Intel microcode loading support"
1227 depends on MICROCODE
1231 This options enables microcode patch loading support for Intel
1234 For the current Intel microcode data package go to
1235 <https://downloadcenter.intel.com> and search for
1236 'Linux Processor Microcode Data File'.
1238 config MICROCODE_AMD
1239 bool "AMD microcode loading support"
1240 depends on MICROCODE
1243 If you select this option, microcode patch loading support for AMD
1244 processors will be enabled.
1246 config MICROCODE_OLD_INTERFACE
1248 depends on MICROCODE
1251 tristate "/dev/cpu/*/msr - Model-specific register support"
1253 This device gives privileged processes access to the x86
1254 Model-Specific Registers (MSRs). It is a character device with
1255 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1256 MSR accesses are directed to a specific CPU on multi-processor
1260 tristate "/dev/cpu/*/cpuid - CPU information support"
1262 This device gives processes access to the x86 CPUID instruction to
1263 be executed on a specific processor. It is a character device
1264 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1268 prompt "High Memory Support"
1275 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1276 However, the address space of 32-bit x86 processors is only 4
1277 Gigabytes large. That means that, if you have a large amount of
1278 physical memory, not all of it can be "permanently mapped" by the
1279 kernel. The physical memory that's not permanently mapped is called
1282 If you are compiling a kernel which will never run on a machine with
1283 more than 1 Gigabyte total physical RAM, answer "off" here (default
1284 choice and suitable for most users). This will result in a "3GB/1GB"
1285 split: 3GB are mapped so that each process sees a 3GB virtual memory
1286 space and the remaining part of the 4GB virtual memory space is used
1287 by the kernel to permanently map as much physical memory as
1290 If the machine has between 1 and 4 Gigabytes physical RAM, then
1293 If more than 4 Gigabytes is used then answer "64GB" here. This
1294 selection turns Intel PAE (Physical Address Extension) mode on.
1295 PAE implements 3-level paging on IA32 processors. PAE is fully
1296 supported by Linux, PAE mode is implemented on all recent Intel
1297 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1298 then the kernel will not boot on CPUs that don't support PAE!
1300 The actual amount of total physical memory will either be
1301 auto detected or can be forced by using a kernel command line option
1302 such as "mem=256M". (Try "man bootparam" or see the documentation of
1303 your boot loader (lilo or loadlin) about how to pass options to the
1304 kernel at boot time.)
1306 If unsure, say "off".
1311 Select this if you have a 32-bit processor and between 1 and 4
1312 gigabytes of physical RAM.
1319 Select this if you have a 32-bit processor and more than 4
1320 gigabytes of physical RAM.
1325 prompt "Memory split" if EXPERT
1329 Select the desired split between kernel and user memory.
1331 If the address range available to the kernel is less than the
1332 physical memory installed, the remaining memory will be available
1333 as "high memory". Accessing high memory is a little more costly
1334 than low memory, as it needs to be mapped into the kernel first.
1335 Note that increasing the kernel address space limits the range
1336 available to user programs, making the address space there
1337 tighter. Selecting anything other than the default 3G/1G split
1338 will also likely make your kernel incompatible with binary-only
1341 If you are not absolutely sure what you are doing, leave this
1345 bool "3G/1G user/kernel split"
1346 config VMSPLIT_3G_OPT
1348 bool "3G/1G user/kernel split (for full 1G low memory)"
1350 bool "2G/2G user/kernel split"
1351 config VMSPLIT_2G_OPT
1353 bool "2G/2G user/kernel split (for full 2G low memory)"
1355 bool "1G/3G user/kernel split"
1360 default 0xB0000000 if VMSPLIT_3G_OPT
1361 default 0x80000000 if VMSPLIT_2G
1362 default 0x78000000 if VMSPLIT_2G_OPT
1363 default 0x40000000 if VMSPLIT_1G
1369 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1372 bool "PAE (Physical Address Extension) Support"
1373 depends on X86_32 && !HIGHMEM4G
1376 PAE is required for NX support, and furthermore enables
1377 larger swapspace support for non-overcommit purposes. It
1378 has the cost of more pagetable lookup overhead, and also
1379 consumes more pagetable space per process.
1381 config ARCH_PHYS_ADDR_T_64BIT
1383 depends on X86_64 || X86_PAE
1385 config ARCH_DMA_ADDR_T_64BIT
1387 depends on X86_64 || HIGHMEM64G
1389 config X86_DIRECT_GBPAGES
1391 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1393 Certain kernel features effectively disable kernel
1394 linear 1 GB mappings (even if the CPU otherwise
1395 supports them), so don't confuse the user by printing
1396 that we have them enabled.
1398 # Common NUMA Features
1400 bool "Numa Memory Allocation and Scheduler Support"
1402 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1403 default y if X86_BIGSMP
1405 Enable NUMA (Non Uniform Memory Access) support.
1407 The kernel will try to allocate memory used by a CPU on the
1408 local memory controller of the CPU and add some more
1409 NUMA awareness to the kernel.
1411 For 64-bit this is recommended if the system is Intel Core i7
1412 (or later), AMD Opteron, or EM64T NUMA.
1414 For 32-bit this is only needed if you boot a 32-bit
1415 kernel on a 64-bit NUMA platform.
1417 Otherwise, you should say N.
1421 prompt "Old style AMD Opteron NUMA detection"
1422 depends on X86_64 && NUMA && PCI
1424 Enable AMD NUMA node topology detection. You should say Y here if
1425 you have a multi processor AMD system. This uses an old method to
1426 read the NUMA configuration directly from the builtin Northbridge
1427 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1428 which also takes priority if both are compiled in.
1430 config X86_64_ACPI_NUMA
1432 prompt "ACPI NUMA detection"
1433 depends on X86_64 && NUMA && ACPI && PCI
1436 Enable ACPI SRAT based node topology detection.
1438 # Some NUMA nodes have memory ranges that span
1439 # other nodes. Even though a pfn is valid and
1440 # between a node's start and end pfns, it may not
1441 # reside on that node. See memmap_init_zone()
1443 config NODES_SPAN_OTHER_NODES
1445 depends on X86_64_ACPI_NUMA
1448 bool "NUMA emulation"
1451 Enable NUMA emulation. A flat machine will be split
1452 into virtual nodes when booted with "numa=fake=N", where N is the
1453 number of nodes. This is only useful for debugging.
1456 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1458 default "10" if MAXSMP
1459 default "6" if X86_64
1461 depends on NEED_MULTIPLE_NODES
1463 Specify the maximum number of NUMA Nodes available on the target
1464 system. Increases memory reserved to accommodate various tables.
1466 config ARCH_HAVE_MEMORY_PRESENT
1468 depends on X86_32 && DISCONTIGMEM
1470 config NEED_NODE_MEMMAP_SIZE
1472 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1474 config ARCH_FLATMEM_ENABLE
1476 depends on X86_32 && !NUMA
1478 config ARCH_DISCONTIGMEM_ENABLE
1480 depends on NUMA && X86_32
1482 config ARCH_DISCONTIGMEM_DEFAULT
1484 depends on NUMA && X86_32
1486 config ARCH_SPARSEMEM_ENABLE
1488 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1489 select SPARSEMEM_STATIC if X86_32
1490 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1492 config ARCH_SPARSEMEM_DEFAULT
1496 config ARCH_SELECT_MEMORY_MODEL
1498 depends on ARCH_SPARSEMEM_ENABLE
1500 config ARCH_MEMORY_PROBE
1501 bool "Enable sysfs memory/probe interface"
1502 depends on X86_64 && MEMORY_HOTPLUG
1504 This option enables a sysfs memory/probe interface for testing.
1505 See Documentation/memory-hotplug.txt for more information.
1506 If you are unsure how to answer this question, answer N.
1508 config ARCH_PROC_KCORE_TEXT
1510 depends on X86_64 && PROC_KCORE
1512 config ILLEGAL_POINTER_VALUE
1515 default 0xdead000000000000 if X86_64
1519 config X86_PMEM_LEGACY_DEVICE
1522 config X86_PMEM_LEGACY
1523 tristate "Support non-standard NVDIMMs and ADR protected memory"
1524 depends on PHYS_ADDR_T_64BIT
1526 select X86_PMEM_LEGACY_DEVICE
1529 Treat memory marked using the non-standard e820 type of 12 as used
1530 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1531 The kernel will offer these regions to the 'pmem' driver so
1532 they can be used for persistent storage.
1537 bool "Allocate 3rd-level pagetables from highmem"
1540 The VM uses one page table entry for each page of physical memory.
1541 For systems with a lot of RAM, this can be wasteful of precious
1542 low memory. Setting this option will put user-space page table
1543 entries in high memory.
1545 config X86_CHECK_BIOS_CORRUPTION
1546 bool "Check for low memory corruption"
1548 Periodically check for memory corruption in low memory, which
1549 is suspected to be caused by BIOS. Even when enabled in the
1550 configuration, it is disabled at runtime. Enable it by
1551 setting "memory_corruption_check=1" on the kernel command
1552 line. By default it scans the low 64k of memory every 60
1553 seconds; see the memory_corruption_check_size and
1554 memory_corruption_check_period parameters in
1555 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1557 When enabled with the default parameters, this option has
1558 almost no overhead, as it reserves a relatively small amount
1559 of memory and scans it infrequently. It both detects corruption
1560 and prevents it from affecting the running system.
1562 It is, however, intended as a diagnostic tool; if repeatable
1563 BIOS-originated corruption always affects the same memory,
1564 you can use memmap= to prevent the kernel from using that
1567 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1568 bool "Set the default setting of memory_corruption_check"
1569 depends on X86_CHECK_BIOS_CORRUPTION
1572 Set whether the default state of memory_corruption_check is
1575 config X86_RESERVE_LOW
1576 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1580 Specify the amount of low memory to reserve for the BIOS.
1582 The first page contains BIOS data structures that the kernel
1583 must not use, so that page must always be reserved.
1585 By default we reserve the first 64K of physical RAM, as a
1586 number of BIOSes are known to corrupt that memory range
1587 during events such as suspend/resume or monitor cable
1588 insertion, so it must not be used by the kernel.
1590 You can set this to 4 if you are absolutely sure that you
1591 trust the BIOS to get all its memory reservations and usages
1592 right. If you know your BIOS have problems beyond the
1593 default 64K area, you can set this to 640 to avoid using the
1594 entire low memory range.
1596 If you have doubts about the BIOS (e.g. suspend/resume does
1597 not work or there's kernel crashes after certain hardware
1598 hotplug events) then you might want to enable
1599 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1600 typical corruption patterns.
1602 Leave this to the default value of 64 if you are unsure.
1604 config MATH_EMULATION
1606 depends on MODIFY_LDT_SYSCALL
1607 prompt "Math emulation" if X86_32
1609 Linux can emulate a math coprocessor (used for floating point
1610 operations) if you don't have one. 486DX and Pentium processors have
1611 a math coprocessor built in, 486SX and 386 do not, unless you added
1612 a 487DX or 387, respectively. (The messages during boot time can
1613 give you some hints here ["man dmesg"].) Everyone needs either a
1614 coprocessor or this emulation.
1616 If you don't have a math coprocessor, you need to say Y here; if you
1617 say Y here even though you have a coprocessor, the coprocessor will
1618 be used nevertheless. (This behavior can be changed with the kernel
1619 command line option "no387", which comes handy if your coprocessor
1620 is broken. Try "man bootparam" or see the documentation of your boot
1621 loader (lilo or loadlin) about how to pass options to the kernel at
1622 boot time.) This means that it is a good idea to say Y here if you
1623 intend to use this kernel on different machines.
1625 More information about the internals of the Linux math coprocessor
1626 emulation can be found in <file:arch/x86/math-emu/README>.
1628 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1629 kernel, it won't hurt.
1633 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1635 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1636 the Memory Type Range Registers (MTRRs) may be used to control
1637 processor access to memory ranges. This is most useful if you have
1638 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1639 allows bus write transfers to be combined into a larger transfer
1640 before bursting over the PCI/AGP bus. This can increase performance
1641 of image write operations 2.5 times or more. Saying Y here creates a
1642 /proc/mtrr file which may be used to manipulate your processor's
1643 MTRRs. Typically the X server should use this.
1645 This code has a reasonably generic interface so that similar
1646 control registers on other processors can be easily supported
1649 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1650 Registers (ARRs) which provide a similar functionality to MTRRs. For
1651 these, the ARRs are used to emulate the MTRRs.
1652 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1653 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1654 write-combining. All of these processors are supported by this code
1655 and it makes sense to say Y here if you have one of them.
1657 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1658 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1659 can lead to all sorts of problems, so it's good to say Y here.
1661 You can safely say Y even if your machine doesn't have MTRRs, you'll
1662 just add about 9 KB to your kernel.
1664 See <file:Documentation/x86/mtrr.txt> for more information.
1666 config MTRR_SANITIZER
1668 prompt "MTRR cleanup support"
1671 Convert MTRR layout from continuous to discrete, so X drivers can
1672 add writeback entries.
1674 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1675 The largest mtrr entry size for a continuous block can be set with
1680 config MTRR_SANITIZER_ENABLE_DEFAULT
1681 int "MTRR cleanup enable value (0-1)"
1684 depends on MTRR_SANITIZER
1686 Enable mtrr cleanup default value
1688 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1689 int "MTRR cleanup spare reg num (0-7)"
1692 depends on MTRR_SANITIZER
1694 mtrr cleanup spare entries default, it can be changed via
1695 mtrr_spare_reg_nr=N on the kernel command line.
1699 prompt "x86 PAT support" if EXPERT
1702 Use PAT attributes to setup page level cache control.
1704 PATs are the modern equivalents of MTRRs and are much more
1705 flexible than MTRRs.
1707 Say N here if you see bootup problems (boot crash, boot hang,
1708 spontaneous reboots) or a non-working video driver.
1712 config ARCH_USES_PG_UNCACHED
1718 prompt "x86 architectural random number generator" if EXPERT
1720 Enable the x86 architectural RDRAND instruction
1721 (Intel Bull Mountain technology) to generate random numbers.
1722 If supported, this is a high bandwidth, cryptographically
1723 secure hardware random number generator.
1727 prompt "Supervisor Mode Access Prevention" if EXPERT
1729 Supervisor Mode Access Prevention (SMAP) is a security
1730 feature in newer Intel processors. There is a small
1731 performance cost if this enabled and turned on; there is
1732 also a small increase in the kernel size if this is enabled.
1736 config X86_INTEL_MPX
1737 prompt "Intel MPX (Memory Protection Extensions)"
1739 depends on CPU_SUP_INTEL
1741 MPX provides hardware features that can be used in
1742 conjunction with compiler-instrumented code to check
1743 memory references. It is designed to detect buffer
1744 overflow or underflow bugs.
1746 This option enables running applications which are
1747 instrumented or otherwise use MPX. It does not use MPX
1748 itself inside the kernel or to protect the kernel
1749 against bad memory references.
1751 Enabling this option will make the kernel larger:
1752 ~8k of kernel text and 36 bytes of data on a 64-bit
1753 defconfig. It adds a long to the 'mm_struct' which
1754 will increase the kernel memory overhead of each
1755 process and adds some branches to paths used during
1756 exec() and munmap().
1758 For details, see Documentation/x86/intel_mpx.txt
1762 config X86_INTEL_MEMORY_PROTECTION_KEYS
1763 prompt "Intel Memory Protection Keys"
1765 # Note: only available in 64-bit mode
1766 depends on CPU_SUP_INTEL && X86_64
1767 select ARCH_USES_HIGH_VMA_FLAGS
1768 select ARCH_HAS_PKEYS
1770 Memory Protection Keys provides a mechanism for enforcing
1771 page-based protections, but without requiring modification of the
1772 page tables when an application changes protection domains.
1774 For details, see Documentation/x86/protection-keys.txt
1779 bool "EFI runtime service support"
1782 select EFI_RUNTIME_WRAPPERS
1784 This enables the kernel to use EFI runtime services that are
1785 available (such as the EFI variable services).
1787 This option is only useful on systems that have EFI firmware.
1788 In addition, you should use the latest ELILO loader available
1789 at <http://elilo.sourceforge.net> in order to take advantage
1790 of EFI runtime services. However, even with this option, the
1791 resultant kernel should continue to boot on existing non-EFI
1795 bool "EFI stub support"
1796 depends on EFI && !X86_USE_3DNOW
1799 This kernel feature allows a bzImage to be loaded directly
1800 by EFI firmware without the use of a bootloader.
1802 See Documentation/efi-stub.txt for more information.
1805 bool "EFI mixed-mode support"
1806 depends on EFI_STUB && X86_64
1808 Enabling this feature allows a 64-bit kernel to be booted
1809 on a 32-bit firmware, provided that your CPU supports 64-bit
1812 Note that it is not possible to boot a mixed-mode enabled
1813 kernel via the EFI boot stub - a bootloader that supports
1814 the EFI handover protocol must be used.
1820 prompt "Enable seccomp to safely compute untrusted bytecode"
1822 This kernel feature is useful for number crunching applications
1823 that may need to compute untrusted bytecode during their
1824 execution. By using pipes or other transports made available to
1825 the process as file descriptors supporting the read/write
1826 syscalls, it's possible to isolate those applications in
1827 their own address space using seccomp. Once seccomp is
1828 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1829 and the task is only allowed to execute a few safe syscalls
1830 defined by each seccomp mode.
1832 If unsure, say Y. Only embedded should say N here.
1834 source kernel/Kconfig.hz
1837 bool "kexec system call"
1840 kexec is a system call that implements the ability to shutdown your
1841 current kernel, and to start another kernel. It is like a reboot
1842 but it is independent of the system firmware. And like a reboot
1843 you can start any kernel with it, not just Linux.
1845 The name comes from the similarity to the exec system call.
1847 It is an ongoing process to be certain the hardware in a machine
1848 is properly shutdown, so do not be surprised if this code does not
1849 initially work for you. As of this writing the exact hardware
1850 interface is strongly in flux, so no good recommendation can be
1854 bool "kexec file based system call"
1859 depends on CRYPTO_SHA256=y
1861 This is new version of kexec system call. This system call is
1862 file based and takes file descriptors as system call argument
1863 for kernel and initramfs as opposed to list of segments as
1864 accepted by previous system call.
1866 config KEXEC_VERIFY_SIG
1867 bool "Verify kernel signature during kexec_file_load() syscall"
1868 depends on KEXEC_FILE
1870 This option makes kernel signature verification mandatory for
1871 the kexec_file_load() syscall.
1873 In addition to that option, you need to enable signature
1874 verification for the corresponding kernel image type being
1875 loaded in order for this to work.
1877 config KEXEC_BZIMAGE_VERIFY_SIG
1878 bool "Enable bzImage signature verification support"
1879 depends on KEXEC_VERIFY_SIG
1880 depends on SIGNED_PE_FILE_VERIFICATION
1881 select SYSTEM_TRUSTED_KEYRING
1883 Enable bzImage signature verification support.
1886 bool "kernel crash dumps"
1887 depends on X86_64 || (X86_32 && HIGHMEM)
1889 Generate crash dump after being started by kexec.
1890 This should be normally only set in special crash dump kernels
1891 which are loaded in the main kernel with kexec-tools into
1892 a specially reserved region and then later executed after
1893 a crash by kdump/kexec. The crash dump kernel must be compiled
1894 to a memory address not used by the main kernel or BIOS using
1895 PHYSICAL_START, or it must be built as a relocatable image
1896 (CONFIG_RELOCATABLE=y).
1897 For more details see Documentation/kdump/kdump.txt
1901 depends on KEXEC && HIBERNATION
1903 Jump between original kernel and kexeced kernel and invoke
1904 code in physical address mode via KEXEC
1906 config PHYSICAL_START
1907 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1910 This gives the physical address where the kernel is loaded.
1912 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1913 bzImage will decompress itself to above physical address and
1914 run from there. Otherwise, bzImage will run from the address where
1915 it has been loaded by the boot loader and will ignore above physical
1918 In normal kdump cases one does not have to set/change this option
1919 as now bzImage can be compiled as a completely relocatable image
1920 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1921 address. This option is mainly useful for the folks who don't want
1922 to use a bzImage for capturing the crash dump and want to use a
1923 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1924 to be specifically compiled to run from a specific memory area
1925 (normally a reserved region) and this option comes handy.
1927 So if you are using bzImage for capturing the crash dump,
1928 leave the value here unchanged to 0x1000000 and set
1929 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1930 for capturing the crash dump change this value to start of
1931 the reserved region. In other words, it can be set based on
1932 the "X" value as specified in the "crashkernel=YM@XM"
1933 command line boot parameter passed to the panic-ed
1934 kernel. Please take a look at Documentation/kdump/kdump.txt
1935 for more details about crash dumps.
1937 Usage of bzImage for capturing the crash dump is recommended as
1938 one does not have to build two kernels. Same kernel can be used
1939 as production kernel and capture kernel. Above option should have
1940 gone away after relocatable bzImage support is introduced. But it
1941 is present because there are users out there who continue to use
1942 vmlinux for dump capture. This option should go away down the
1945 Don't change this unless you know what you are doing.
1948 bool "Build a relocatable kernel"
1951 This builds a kernel image that retains relocation information
1952 so it can be loaded someplace besides the default 1MB.
1953 The relocations tend to make the kernel binary about 10% larger,
1954 but are discarded at runtime.
1956 One use is for the kexec on panic case where the recovery kernel
1957 must live at a different physical address than the primary
1960 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1961 it has been loaded at and the compile time physical address
1962 (CONFIG_PHYSICAL_START) is used as the minimum location.
1964 config RANDOMIZE_BASE
1965 bool "Randomize the address of the kernel image (KASLR)"
1966 depends on RELOCATABLE
1969 In support of Kernel Address Space Layout Randomization (KASLR),
1970 this randomizes the physical address at which the kernel image
1971 is decompressed and the virtual address where the kernel
1972 image is mapped, as a security feature that deters exploit
1973 attempts relying on knowledge of the location of kernel
1976 On 64-bit, the kernel physical and virtual addresses are
1977 randomized separately. The physical address will be anywhere
1978 between 16MB and the top of physical memory (up to 64TB). The
1979 virtual address will be randomized from 16MB up to 1GB (9 bits
1980 of entropy). Note that this also reduces the memory space
1981 available to kernel modules from 1.5GB to 1GB.
1983 On 32-bit, the kernel physical and virtual addresses are
1984 randomized together. They will be randomized from 16MB up to
1985 512MB (8 bits of entropy).
1987 Entropy is generated using the RDRAND instruction if it is
1988 supported. If RDTSC is supported, its value is mixed into
1989 the entropy pool as well. If neither RDRAND nor RDTSC are
1990 supported, then entropy is read from the i8254 timer. The
1991 usable entropy is limited by the kernel being built using
1992 2GB addressing, and that PHYSICAL_ALIGN must be at a
1993 minimum of 2MB. As a result, only 10 bits of entropy are
1994 theoretically possible, but the implementations are further
1995 limited due to memory layouts.
1997 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1998 time. To enable it, boot with "kaslr" on the kernel command
1999 line (which will also disable hibernation).
2003 # Relocation on x86 needs some additional build support
2004 config X86_NEED_RELOCS
2006 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2008 config PHYSICAL_ALIGN
2009 hex "Alignment value to which kernel should be aligned"
2011 range 0x2000 0x1000000 if X86_32
2012 range 0x200000 0x1000000 if X86_64
2014 This value puts the alignment restrictions on physical address
2015 where kernel is loaded and run from. Kernel is compiled for an
2016 address which meets above alignment restriction.
2018 If bootloader loads the kernel at a non-aligned address and
2019 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2020 address aligned to above value and run from there.
2022 If bootloader loads the kernel at a non-aligned address and
2023 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2024 load address and decompress itself to the address it has been
2025 compiled for and run from there. The address for which kernel is
2026 compiled already meets above alignment restrictions. Hence the
2027 end result is that kernel runs from a physical address meeting
2028 above alignment restrictions.
2030 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2031 this value must be a multiple of 0x200000.
2033 Don't change this unless you know what you are doing.
2035 config RANDOMIZE_MEMORY
2036 bool "Randomize the kernel memory sections"
2038 depends on RANDOMIZE_BASE
2039 default RANDOMIZE_BASE
2041 Randomizes the base virtual address of kernel memory sections
2042 (physical memory mapping, vmalloc & vmemmap). This security feature
2043 makes exploits relying on predictable memory locations less reliable.
2045 The order of allocations remains unchanged. Entropy is generated in
2046 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2047 configuration have in average 30,000 different possible virtual
2048 addresses for each memory section.
2052 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2053 hex "Physical memory mapping padding" if EXPERT
2054 depends on RANDOMIZE_MEMORY
2055 default "0xa" if MEMORY_HOTPLUG
2057 range 0x1 0x40 if MEMORY_HOTPLUG
2060 Define the padding in terabytes added to the existing physical
2061 memory size during kernel memory randomization. It is useful
2062 for memory hotplug support but reduces the entropy available for
2063 address randomization.
2065 If unsure, leave at the default value.
2068 bool "Support for hot-pluggable CPUs"
2071 Say Y here to allow turning CPUs off and on. CPUs can be
2072 controlled through /sys/devices/system/cpu.
2073 ( Note: power management support will enable this option
2074 automatically on SMP systems. )
2075 Say N if you want to disable CPU hotplug.
2077 config BOOTPARAM_HOTPLUG_CPU0
2078 bool "Set default setting of cpu0_hotpluggable"
2080 depends on HOTPLUG_CPU
2082 Set whether default state of cpu0_hotpluggable is on or off.
2084 Say Y here to enable CPU0 hotplug by default. If this switch
2085 is turned on, there is no need to give cpu0_hotplug kernel
2086 parameter and the CPU0 hotplug feature is enabled by default.
2088 Please note: there are two known CPU0 dependencies if you want
2089 to enable the CPU0 hotplug feature either by this switch or by
2090 cpu0_hotplug kernel parameter.
2092 First, resume from hibernate or suspend always starts from CPU0.
2093 So hibernate and suspend are prevented if CPU0 is offline.
2095 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2096 offline if any interrupt can not migrate out of CPU0. There may
2097 be other CPU0 dependencies.
2099 Please make sure the dependencies are under your control before
2100 you enable this feature.
2102 Say N if you don't want to enable CPU0 hotplug feature by default.
2103 You still can enable the CPU0 hotplug feature at boot by kernel
2104 parameter cpu0_hotplug.
2106 config DEBUG_HOTPLUG_CPU0
2108 prompt "Debug CPU0 hotplug"
2109 depends on HOTPLUG_CPU
2111 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2112 soon as possible and boots up userspace with CPU0 offlined. User
2113 can online CPU0 back after boot time.
2115 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2116 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2117 compilation or giving cpu0_hotplug kernel parameter at boot.
2123 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2124 depends on COMPAT_32
2126 Certain buggy versions of glibc will crash if they are
2127 presented with a 32-bit vDSO that is not mapped at the address
2128 indicated in its segment table.
2130 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2131 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2132 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2133 the only released version with the bug, but OpenSUSE 9
2134 contains a buggy "glibc 2.3.2".
2136 The symptom of the bug is that everything crashes on startup, saying:
2137 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2139 Saying Y here changes the default value of the vdso32 boot
2140 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2141 This works around the glibc bug but hurts performance.
2143 If unsure, say N: if you are compiling your own kernel, you
2144 are unlikely to be using a buggy version of glibc.
2147 prompt "vsyscall table for legacy applications"
2149 default LEGACY_VSYSCALL_EMULATE
2151 Legacy user code that does not know how to find the vDSO expects
2152 to be able to issue three syscalls by calling fixed addresses in
2153 kernel space. Since this location is not randomized with ASLR,
2154 it can be used to assist security vulnerability exploitation.
2156 This setting can be changed at boot time via the kernel command
2157 line parameter vsyscall=[native|emulate|none].
2159 On a system with recent enough glibc (2.14 or newer) and no
2160 static binaries, you can say None without a performance penalty
2161 to improve security.
2163 If unsure, select "Emulate".
2165 config LEGACY_VSYSCALL_NATIVE
2168 Actual executable code is located in the fixed vsyscall
2169 address mapping, implementing time() efficiently. Since
2170 this makes the mapping executable, it can be used during
2171 security vulnerability exploitation (traditionally as
2172 ROP gadgets). This configuration is not recommended.
2174 config LEGACY_VSYSCALL_EMULATE
2177 The kernel traps and emulates calls into the fixed
2178 vsyscall address mapping. This makes the mapping
2179 non-executable, but it still contains known contents,
2180 which could be used in certain rare security vulnerability
2181 exploits. This configuration is recommended when userspace
2182 still uses the vsyscall area.
2184 config LEGACY_VSYSCALL_NONE
2187 There will be no vsyscall mapping at all. This will
2188 eliminate any risk of ASLR bypass due to the vsyscall
2189 fixed address mapping. Attempts to use the vsyscalls
2190 will be reported to dmesg, so that either old or
2191 malicious userspace programs can be identified.
2196 bool "Built-in kernel command line"
2198 Allow for specifying boot arguments to the kernel at
2199 build time. On some systems (e.g. embedded ones), it is
2200 necessary or convenient to provide some or all of the
2201 kernel boot arguments with the kernel itself (that is,
2202 to not rely on the boot loader to provide them.)
2204 To compile command line arguments into the kernel,
2205 set this option to 'Y', then fill in the
2206 boot arguments in CONFIG_CMDLINE.
2208 Systems with fully functional boot loaders (i.e. non-embedded)
2209 should leave this option set to 'N'.
2212 string "Built-in kernel command string"
2213 depends on CMDLINE_BOOL
2216 Enter arguments here that should be compiled into the kernel
2217 image and used at boot time. If the boot loader provides a
2218 command line at boot time, it is appended to this string to
2219 form the full kernel command line, when the system boots.
2221 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2222 change this behavior.
2224 In most cases, the command line (whether built-in or provided
2225 by the boot loader) should specify the device for the root
2228 config CMDLINE_OVERRIDE
2229 bool "Built-in command line overrides boot loader arguments"
2230 depends on CMDLINE_BOOL
2232 Set this option to 'Y' to have the kernel ignore the boot loader
2233 command line, and use ONLY the built-in command line.
2235 This is used to work around broken boot loaders. This should
2236 be set to 'N' under normal conditions.
2238 config MODIFY_LDT_SYSCALL
2239 bool "Enable the LDT (local descriptor table)" if EXPERT
2242 Linux can allow user programs to install a per-process x86
2243 Local Descriptor Table (LDT) using the modify_ldt(2) system
2244 call. This is required to run 16-bit or segmented code such as
2245 DOSEMU or some Wine programs. It is also used by some very old
2246 threading libraries.
2248 Enabling this feature adds a small amount of overhead to
2249 context switches and increases the low-level kernel attack
2250 surface. Disabling it removes the modify_ldt(2) system call.
2252 Saying 'N' here may make sense for embedded or server kernels.
2254 source "kernel/livepatch/Kconfig"
2258 config ARCH_ENABLE_MEMORY_HOTPLUG
2260 depends on X86_64 || (X86_32 && HIGHMEM)
2262 config ARCH_ENABLE_MEMORY_HOTREMOVE
2264 depends on MEMORY_HOTPLUG
2266 config USE_PERCPU_NUMA_NODE_ID
2270 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2272 depends on X86_64 || X86_PAE
2274 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2276 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2278 menu "Power management and ACPI options"
2280 config ARCH_HIBERNATION_HEADER
2282 depends on X86_64 && HIBERNATION
2284 source "kernel/power/Kconfig"
2286 source "drivers/acpi/Kconfig"
2288 source "drivers/sfi/Kconfig"
2295 tristate "APM (Advanced Power Management) BIOS support"
2296 depends on X86_32 && PM_SLEEP
2298 APM is a BIOS specification for saving power using several different
2299 techniques. This is mostly useful for battery powered laptops with
2300 APM compliant BIOSes. If you say Y here, the system time will be
2301 reset after a RESUME operation, the /proc/apm device will provide
2302 battery status information, and user-space programs will receive
2303 notification of APM "events" (e.g. battery status change).
2305 If you select "Y" here, you can disable actual use of the APM
2306 BIOS by passing the "apm=off" option to the kernel at boot time.
2308 Note that the APM support is almost completely disabled for
2309 machines with more than one CPU.
2311 In order to use APM, you will need supporting software. For location
2312 and more information, read <file:Documentation/power/apm-acpi.txt>
2313 and the Battery Powered Linux mini-HOWTO, available from
2314 <http://www.tldp.org/docs.html#howto>.
2316 This driver does not spin down disk drives (see the hdparm(8)
2317 manpage ("man 8 hdparm") for that), and it doesn't turn off
2318 VESA-compliant "green" monitors.
2320 This driver does not support the TI 4000M TravelMate and the ACER
2321 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2322 desktop machines also don't have compliant BIOSes, and this driver
2323 may cause those machines to panic during the boot phase.
2325 Generally, if you don't have a battery in your machine, there isn't
2326 much point in using this driver and you should say N. If you get
2327 random kernel OOPSes or reboots that don't seem to be related to
2328 anything, try disabling/enabling this option (or disabling/enabling
2331 Some other things you should try when experiencing seemingly random,
2334 1) make sure that you have enough swap space and that it is
2336 2) pass the "no-hlt" option to the kernel
2337 3) switch on floating point emulation in the kernel and pass
2338 the "no387" option to the kernel
2339 4) pass the "floppy=nodma" option to the kernel
2340 5) pass the "mem=4M" option to the kernel (thereby disabling
2341 all but the first 4 MB of RAM)
2342 6) make sure that the CPU is not over clocked.
2343 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2344 8) disable the cache from your BIOS settings
2345 9) install a fan for the video card or exchange video RAM
2346 10) install a better fan for the CPU
2347 11) exchange RAM chips
2348 12) exchange the motherboard.
2350 To compile this driver as a module, choose M here: the
2351 module will be called apm.
2355 config APM_IGNORE_USER_SUSPEND
2356 bool "Ignore USER SUSPEND"
2358 This option will ignore USER SUSPEND requests. On machines with a
2359 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2360 series notebooks, it is necessary to say Y because of a BIOS bug.
2362 config APM_DO_ENABLE
2363 bool "Enable PM at boot time"
2365 Enable APM features at boot time. From page 36 of the APM BIOS
2366 specification: "When disabled, the APM BIOS does not automatically
2367 power manage devices, enter the Standby State, enter the Suspend
2368 State, or take power saving steps in response to CPU Idle calls."
2369 This driver will make CPU Idle calls when Linux is idle (unless this
2370 feature is turned off -- see "Do CPU IDLE calls", below). This
2371 should always save battery power, but more complicated APM features
2372 will be dependent on your BIOS implementation. You may need to turn
2373 this option off if your computer hangs at boot time when using APM
2374 support, or if it beeps continuously instead of suspending. Turn
2375 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2376 T400CDT. This is off by default since most machines do fine without
2381 bool "Make CPU Idle calls when idle"
2383 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2384 On some machines, this can activate improved power savings, such as
2385 a slowed CPU clock rate, when the machine is idle. These idle calls
2386 are made after the idle loop has run for some length of time (e.g.,
2387 333 mS). On some machines, this will cause a hang at boot time or
2388 whenever the CPU becomes idle. (On machines with more than one CPU,
2389 this option does nothing.)
2391 config APM_DISPLAY_BLANK
2392 bool "Enable console blanking using APM"
2394 Enable console blanking using the APM. Some laptops can use this to
2395 turn off the LCD backlight when the screen blanker of the Linux
2396 virtual console blanks the screen. Note that this is only used by
2397 the virtual console screen blanker, and won't turn off the backlight
2398 when using the X Window system. This also doesn't have anything to
2399 do with your VESA-compliant power-saving monitor. Further, this
2400 option doesn't work for all laptops -- it might not turn off your
2401 backlight at all, or it might print a lot of errors to the console,
2402 especially if you are using gpm.
2404 config APM_ALLOW_INTS
2405 bool "Allow interrupts during APM BIOS calls"
2407 Normally we disable external interrupts while we are making calls to
2408 the APM BIOS as a measure to lessen the effects of a badly behaving
2409 BIOS implementation. The BIOS should reenable interrupts if it
2410 needs to. Unfortunately, some BIOSes do not -- especially those in
2411 many of the newer IBM Thinkpads. If you experience hangs when you
2412 suspend, try setting this to Y. Otherwise, say N.
2416 source "drivers/cpufreq/Kconfig"
2418 source "drivers/cpuidle/Kconfig"
2420 source "drivers/idle/Kconfig"
2425 menu "Bus options (PCI etc.)"
2431 Find out whether you have a PCI motherboard. PCI is the name of a
2432 bus system, i.e. the way the CPU talks to the other stuff inside
2433 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2434 VESA. If you have PCI, say Y, otherwise N.
2437 prompt "PCI access mode"
2438 depends on X86_32 && PCI
2441 On PCI systems, the BIOS can be used to detect the PCI devices and
2442 determine their configuration. However, some old PCI motherboards
2443 have BIOS bugs and may crash if this is done. Also, some embedded
2444 PCI-based systems don't have any BIOS at all. Linux can also try to
2445 detect the PCI hardware directly without using the BIOS.
2447 With this option, you can specify how Linux should detect the
2448 PCI devices. If you choose "BIOS", the BIOS will be used,
2449 if you choose "Direct", the BIOS won't be used, and if you
2450 choose "MMConfig", then PCI Express MMCONFIG will be used.
2451 If you choose "Any", the kernel will try MMCONFIG, then the
2452 direct access method and falls back to the BIOS if that doesn't
2453 work. If unsure, go with the default, which is "Any".
2458 config PCI_GOMMCONFIG
2475 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2477 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2480 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2484 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2488 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2492 depends on PCI && XEN
2500 bool "Support mmconfig PCI config space access"
2501 depends on X86_64 && PCI && ACPI
2503 config PCI_CNB20LE_QUIRK
2504 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2507 Read the PCI windows out of the CNB20LE host bridge. This allows
2508 PCI hotplug to work on systems with the CNB20LE chipset which do
2511 There's no public spec for this chipset, and this functionality
2512 is known to be incomplete.
2514 You should say N unless you know you need this.
2516 source "drivers/pci/Kconfig"
2519 bool "ISA-style bus support on modern systems" if EXPERT
2522 Enables ISA-style drivers on modern systems. This is necessary to
2523 support PC/104 devices on X86_64 platforms.
2527 # x86_64 have no ISA slots, but can have ISA-style DMA.
2529 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2532 Enables ISA-style DMA support for devices requiring such controllers.
2540 Find out whether you have ISA slots on your motherboard. ISA is the
2541 name of a bus system, i.e. the way the CPU talks to the other stuff
2542 inside your box. Other bus systems are PCI, EISA, MicroChannel
2543 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2544 newer boards don't support it. If you have ISA, say Y, otherwise N.
2550 The Extended Industry Standard Architecture (EISA) bus was
2551 developed as an open alternative to the IBM MicroChannel bus.
2553 The EISA bus provided some of the features of the IBM MicroChannel
2554 bus while maintaining backward compatibility with cards made for
2555 the older ISA bus. The EISA bus saw limited use between 1988 and
2556 1995 when it was made obsolete by the PCI bus.
2558 Say Y here if you are building a kernel for an EISA-based machine.
2562 source "drivers/eisa/Kconfig"
2565 tristate "NatSemi SCx200 support"
2567 This provides basic support for National Semiconductor's
2568 (now AMD's) Geode processors. The driver probes for the
2569 PCI-IDs of several on-chip devices, so its a good dependency
2570 for other scx200_* drivers.
2572 If compiled as a module, the driver is named scx200.
2574 config SCx200HR_TIMER
2575 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2579 This driver provides a clocksource built upon the on-chip
2580 27MHz high-resolution timer. Its also a workaround for
2581 NSC Geode SC-1100's buggy TSC, which loses time when the
2582 processor goes idle (as is done by the scheduler). The
2583 other workaround is idle=poll boot option.
2586 bool "One Laptop Per Child support"
2593 Add support for detecting the unique features of the OLPC
2597 bool "OLPC XO-1 Power Management"
2598 depends on OLPC && MFD_CS5535 && PM_SLEEP
2601 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2604 bool "OLPC XO-1 Real Time Clock"
2605 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2607 Add support for the XO-1 real time clock, which can be used as a
2608 programmable wakeup source.
2611 bool "OLPC XO-1 SCI extras"
2612 depends on OLPC && OLPC_XO1_PM
2618 Add support for SCI-based features of the OLPC XO-1 laptop:
2619 - EC-driven system wakeups
2623 - AC adapter status updates
2624 - Battery status updates
2626 config OLPC_XO15_SCI
2627 bool "OLPC XO-1.5 SCI extras"
2628 depends on OLPC && ACPI
2631 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2632 - EC-driven system wakeups
2633 - AC adapter status updates
2634 - Battery status updates
2637 bool "PCEngines ALIX System Support (LED setup)"
2640 This option enables system support for the PCEngines ALIX.
2641 At present this just sets up LEDs for GPIO control on
2642 ALIX2/3/6 boards. However, other system specific setup should
2645 Note: You must still enable the drivers for GPIO and LED support
2646 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2648 Note: You have to set alix.force=1 for boards with Award BIOS.
2651 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2654 This option enables system support for the Soekris Engineering net5501.
2657 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2661 This option enables system support for the Traverse Technologies GEOS.
2664 bool "Technologic Systems TS-5500 platform support"
2666 select CHECK_SIGNATURE
2670 This option enables system support for the Technologic Systems TS-5500.
2676 depends on CPU_SUP_AMD && PCI
2678 source "drivers/pcmcia/Kconfig"
2681 tristate "RapidIO support"
2685 If enabled this option will include drivers and the core
2686 infrastructure code to support RapidIO interconnect devices.
2688 source "drivers/rapidio/Kconfig"
2691 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2693 Firmwares often provide initial graphics framebuffers so the BIOS,
2694 bootloader or kernel can show basic video-output during boot for
2695 user-guidance and debugging. Historically, x86 used the VESA BIOS
2696 Extensions and EFI-framebuffers for this, which are mostly limited
2698 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2699 framebuffers so the new generic system-framebuffer drivers can be
2700 used on x86. If the framebuffer is not compatible with the generic
2701 modes, it is adverticed as fallback platform framebuffer so legacy
2702 drivers like efifb, vesafb and uvesafb can pick it up.
2703 If this option is not selected, all system framebuffers are always
2704 marked as fallback platform framebuffers as usual.
2706 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2707 not be able to pick up generic system framebuffers if this option
2708 is selected. You are highly encouraged to enable simplefb as
2709 replacement if you select this option. simplefb can correctly deal
2710 with generic system framebuffers. But you should still keep vesafb
2711 and others enabled as fallback if a system framebuffer is
2712 incompatible with simplefb.
2719 menu "Executable file formats / Emulations"
2721 source "fs/Kconfig.binfmt"
2723 config IA32_EMULATION
2724 bool "IA32 Emulation"
2726 select ARCH_WANT_OLD_COMPAT_IPC
2728 select COMPAT_BINFMT_ELF
2729 select COMPAT_OLD_SIGACTION
2731 Include code to run legacy 32-bit programs under a
2732 64-bit kernel. You should likely turn this on, unless you're
2733 100% sure that you don't have any 32-bit programs left.
2736 tristate "IA32 a.out support"
2737 depends on IA32_EMULATION
2739 Support old a.out binaries in the 32bit emulation.
2742 bool "x32 ABI for 64-bit mode"
2745 Include code to run binaries for the x32 native 32-bit ABI
2746 for 64-bit processors. An x32 process gets access to the
2747 full 64-bit register file and wide data path while leaving
2748 pointers at 32 bits for smaller memory footprint.
2750 You will need a recent binutils (2.22 or later) with
2751 elf32_x86_64 support enabled to compile a kernel with this
2756 depends on IA32_EMULATION || X86_32
2758 select OLD_SIGSUSPEND3
2762 depends on IA32_EMULATION || X86_X32
2765 config COMPAT_FOR_U64_ALIGNMENT
2768 config SYSVIPC_COMPAT
2780 config HAVE_ATOMIC_IOMAP
2784 config X86_DEV_DMA_OPS
2786 depends on X86_64 || STA2X11
2788 config X86_DMA_REMAP
2796 source "net/Kconfig"
2798 source "drivers/Kconfig"
2800 source "drivers/firmware/Kconfig"
2804 source "arch/x86/Kconfig.debug"
2806 source "security/Kconfig"
2808 source "crypto/Kconfig"
2810 source "arch/x86/kvm/Kconfig"
2812 source "lib/Kconfig"