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_DEBUG_VIRTUAL
50 select ARCH_HAS_DEVMEM_IS_ALLOWED
51 select ARCH_HAS_ELF_RANDOMIZE
52 select ARCH_HAS_FAST_MULTIPLIER
53 select ARCH_HAS_GCOV_PROFILE_ALL
54 select ARCH_HAS_KCOV if X86_64
55 select ARCH_HAS_MMIO_FLUSH
56 select ARCH_HAS_PMEM_API if X86_64
57 select ARCH_HAS_SET_MEMORY
58 select ARCH_HAS_SG_CHAIN
59 select ARCH_HAS_STRICT_KERNEL_RWX
60 select ARCH_HAS_STRICT_MODULE_RWX
61 select ARCH_HAS_UBSAN_SANITIZE_ALL
62 select ARCH_HAVE_NMI_SAFE_CMPXCHG
63 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
64 select ARCH_MIGHT_HAVE_PC_PARPORT
65 select ARCH_MIGHT_HAVE_PC_SERIO
66 select ARCH_SUPPORTS_ATOMIC_RMW
67 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
68 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
69 select ARCH_USE_BUILTIN_BSWAP
70 select ARCH_USE_QUEUED_RWLOCKS
71 select ARCH_USE_QUEUED_SPINLOCKS
72 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
73 select ARCH_WANT_FRAME_POINTERS
74 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
75 select BUILDTIME_EXTABLE_SORT
77 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
78 select CLOCKSOURCE_WATCHDOG
79 select DCACHE_WORD_ACCESS
80 select EDAC_ATOMIC_SCRUB
82 select GENERIC_CLOCKEVENTS
83 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
84 select GENERIC_CLOCKEVENTS_MIN_ADJUST
85 select GENERIC_CMOS_UPDATE
86 select GENERIC_CPU_AUTOPROBE
87 select GENERIC_EARLY_IOREMAP
88 select GENERIC_FIND_FIRST_BIT
90 select GENERIC_IRQ_PROBE
91 select GENERIC_IRQ_SHOW
92 select GENERIC_PENDING_IRQ if SMP
93 select GENERIC_SMP_IDLE_THREAD
94 select GENERIC_STRNCPY_FROM_USER
95 select GENERIC_STRNLEN_USER
96 select GENERIC_TIME_VSYSCALL
97 select HAVE_ACPI_APEI if ACPI
98 select HAVE_ACPI_APEI_NMI if ACPI
99 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
100 select HAVE_ARCH_AUDITSYSCALL
101 select HAVE_ARCH_HARDENED_USERCOPY
102 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
103 select HAVE_ARCH_JUMP_LABEL
104 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
105 select HAVE_ARCH_KGDB
106 select HAVE_ARCH_KMEMCHECK
107 select HAVE_ARCH_MMAP_RND_BITS if MMU
108 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
109 select HAVE_ARCH_SECCOMP_FILTER
110 select HAVE_ARCH_TRACEHOOK
111 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
112 select HAVE_ARCH_VMAP_STACK if X86_64
113 select HAVE_ARCH_WITHIN_STACK_FRAMES
114 select HAVE_CC_STACKPROTECTOR
115 select HAVE_CMPXCHG_DOUBLE
116 select HAVE_CMPXCHG_LOCAL
117 select HAVE_CONTEXT_TRACKING if X86_64
118 select HAVE_COPY_THREAD_TLS
119 select HAVE_C_RECORDMCOUNT
120 select HAVE_DEBUG_KMEMLEAK
121 select HAVE_DEBUG_STACKOVERFLOW
122 select HAVE_DMA_API_DEBUG
123 select HAVE_DMA_CONTIGUOUS
124 select HAVE_DYNAMIC_FTRACE
125 select HAVE_DYNAMIC_FTRACE_WITH_REGS
126 select HAVE_EBPF_JIT if X86_64
127 select HAVE_EFFICIENT_UNALIGNED_ACCESS
128 select HAVE_EXIT_THREAD
129 select HAVE_FENTRY if X86_64
130 select HAVE_FTRACE_MCOUNT_RECORD
131 select HAVE_FUNCTION_GRAPH_TRACER
132 select HAVE_FUNCTION_TRACER
133 select HAVE_GCC_PLUGINS
134 select HAVE_HW_BREAKPOINT
136 select HAVE_IOREMAP_PROT
137 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
138 select HAVE_IRQ_TIME_ACCOUNTING
139 select HAVE_KERNEL_BZIP2
140 select HAVE_KERNEL_GZIP
141 select HAVE_KERNEL_LZ4
142 select HAVE_KERNEL_LZMA
143 select HAVE_KERNEL_LZO
144 select HAVE_KERNEL_XZ
146 select HAVE_KPROBES_ON_FTRACE
147 select HAVE_KRETPROBES
149 select HAVE_LIVEPATCH if X86_64
151 select HAVE_MEMBLOCK_NODE_MAP
152 select HAVE_MIXED_BREAKPOINTS_REGS
155 select HAVE_OPTPROBES
156 select HAVE_PCSPKR_PLATFORM
157 select HAVE_PERF_EVENTS
158 select HAVE_PERF_EVENTS_NMI
159 select HAVE_PERF_REGS
160 select HAVE_PERF_USER_STACK_DUMP
161 select HAVE_REGS_AND_STACK_ACCESS_API
162 select HAVE_STACK_VALIDATION if X86_64
163 select HAVE_SYSCALL_TRACEPOINTS
164 select HAVE_UNSTABLE_SCHED_CLOCK
165 select HAVE_USER_RETURN_NOTIFIER
166 select IRQ_FORCED_THREADING
169 select RTC_MC146818_LIB
172 select SYSCTL_EXCEPTION_TRACE
173 select THREAD_INFO_IN_TASK
174 select USER_STACKTRACE_SUPPORT
176 select X86_FEATURE_NAMES if PROC_FS
178 config INSTRUCTION_DECODER
180 depends on KPROBES || PERF_EVENTS || UPROBES
184 default "elf32-i386" if X86_32
185 default "elf64-x86-64" if X86_64
187 config ARCH_DEFCONFIG
189 default "arch/x86/configs/i386_defconfig" if X86_32
190 default "arch/x86/configs/x86_64_defconfig" if X86_64
192 config LOCKDEP_SUPPORT
195 config STACKTRACE_SUPPORT
201 config ARCH_MMAP_RND_BITS_MIN
205 config ARCH_MMAP_RND_BITS_MAX
209 config ARCH_MMAP_RND_COMPAT_BITS_MIN
212 config ARCH_MMAP_RND_COMPAT_BITS_MAX
218 config NEED_DMA_MAP_STATE
220 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
222 config NEED_SG_DMA_LENGTH
225 config GENERIC_ISA_DMA
227 depends on ISA_DMA_API
232 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
234 config GENERIC_BUG_RELATIVE_POINTERS
237 config GENERIC_HWEIGHT
240 config ARCH_MAY_HAVE_PC_FDC
242 depends on ISA_DMA_API
244 config RWSEM_XCHGADD_ALGORITHM
247 config GENERIC_CALIBRATE_DELAY
250 config ARCH_HAS_CPU_RELAX
253 config ARCH_HAS_CACHE_LINE_SIZE
256 config HAVE_SETUP_PER_CPU_AREA
259 config NEED_PER_CPU_EMBED_FIRST_CHUNK
262 config NEED_PER_CPU_PAGE_FIRST_CHUNK
265 config ARCH_HIBERNATION_POSSIBLE
268 config ARCH_SUSPEND_POSSIBLE
271 config ARCH_WANT_HUGE_PMD_SHARE
274 config ARCH_WANT_GENERAL_HUGETLB
283 config ARCH_SUPPORTS_OPTIMIZED_INLINING
286 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
289 config KASAN_SHADOW_OFFSET
292 default 0xdffffc0000000000
294 config HAVE_INTEL_TXT
296 depends on INTEL_IOMMU && ACPI
300 depends on X86_32 && SMP
304 depends on X86_64 && SMP
306 config X86_32_LAZY_GS
308 depends on X86_32 && !CC_STACKPROTECTOR
310 config ARCH_SUPPORTS_UPROBES
313 config FIX_EARLYCON_MEM
316 config PGTABLE_LEVELS
322 source "init/Kconfig"
323 source "kernel/Kconfig.freezer"
325 menu "Processor type and features"
328 bool "DMA memory allocation support" if EXPERT
331 DMA memory allocation support allows devices with less than 32-bit
332 addressing to allocate within the first 16MB of address space.
333 Disable if no such devices will be used.
338 bool "Symmetric multi-processing support"
340 This enables support for systems with more than one CPU. If you have
341 a system with only one CPU, say N. If you have a system with more
344 If you say N here, the kernel will run on uni- and multiprocessor
345 machines, but will use only one CPU of a multiprocessor machine. If
346 you say Y here, the kernel will run on many, but not all,
347 uniprocessor machines. On a uniprocessor machine, the kernel
348 will run faster if you say N here.
350 Note that if you say Y here and choose architecture "586" or
351 "Pentium" under "Processor family", the kernel will not work on 486
352 architectures. Similarly, multiprocessor kernels for the "PPro"
353 architecture may not work on all Pentium based boards.
355 People using multiprocessor machines who say Y here should also say
356 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
357 Management" code will be disabled if you say Y here.
359 See also <file:Documentation/x86/i386/IO-APIC.txt>,
360 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
361 <http://www.tldp.org/docs.html#howto>.
363 If you don't know what to do here, say N.
365 config X86_FEATURE_NAMES
366 bool "Processor feature human-readable names" if EMBEDDED
369 This option compiles in a table of x86 feature bits and corresponding
370 names. This is required to support /proc/cpuinfo and a few kernel
371 messages. You can disable this to save space, at the expense of
372 making those few kernel messages show numeric feature bits instead.
376 config X86_FAST_FEATURE_TESTS
377 bool "Fast CPU feature tests" if EMBEDDED
380 Some fast-paths in the kernel depend on the capabilities of the CPU.
381 Say Y here for the kernel to patch in the appropriate code at runtime
382 based on the capabilities of the CPU. The infrastructure for patching
383 code at runtime takes up some additional space; space-constrained
384 embedded systems may wish to say N here to produce smaller, slightly
388 bool "Support x2apic"
389 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
391 This enables x2apic support on CPUs that have this feature.
393 This allows 32-bit apic IDs (so it can support very large systems),
394 and accesses the local apic via MSRs not via mmio.
396 If you don't know what to do here, say N.
399 bool "Enable MPS table" if ACPI || SFI
401 depends on X86_LOCAL_APIC
403 For old smp systems that do not have proper acpi support. Newer systems
404 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
407 bool "Support for big SMP systems with more than 8 CPUs"
408 depends on X86_32 && SMP
410 This option is needed for the systems that have more than 8 CPUs
414 depends on X86_GOLDFISH
417 bool "Intel Resource Director Technology Allocation support"
419 depends on X86 && CPU_SUP_INTEL
422 Select to enable resource allocation which is a sub-feature of
423 Intel Resource Director Technology(RDT). More information about
424 RDT can be found in the Intel x86 Architecture Software
430 config X86_EXTENDED_PLATFORM
431 bool "Support for extended (non-PC) x86 platforms"
434 If you disable this option then the kernel will only support
435 standard PC platforms. (which covers the vast majority of
438 If you enable this option then you'll be able to select support
439 for the following (non-PC) 32 bit x86 platforms:
440 Goldfish (Android emulator)
443 SGI 320/540 (Visual Workstation)
444 STA2X11-based (e.g. Northville)
445 Moorestown MID devices
447 If you have one of these systems, or if you want to build a
448 generic distribution kernel, say Y here - otherwise say N.
452 config X86_EXTENDED_PLATFORM
453 bool "Support for extended (non-PC) x86 platforms"
456 If you disable this option then the kernel will only support
457 standard PC platforms. (which covers the vast majority of
460 If you enable this option then you'll be able to select support
461 for the following (non-PC) 64 bit x86 platforms:
466 If you have one of these systems, or if you want to build a
467 generic distribution kernel, say Y here - otherwise say N.
469 # This is an alphabetically sorted list of 64 bit extended platforms
470 # Please maintain the alphabetic order if and when there are additions
472 bool "Numascale NumaChip"
474 depends on X86_EXTENDED_PLATFORM
477 depends on X86_X2APIC
478 depends on PCI_MMCONFIG
480 Adds support for Numascale NumaChip large-SMP systems. Needed to
481 enable more than ~168 cores.
482 If you don't have one of these, you should say N here.
486 select HYPERVISOR_GUEST
488 depends on X86_64 && PCI
489 depends on X86_EXTENDED_PLATFORM
492 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
493 supposed to run on these EM64T-based machines. Only choose this option
494 if you have one of these machines.
497 bool "SGI Ultraviolet"
499 depends on X86_EXTENDED_PLATFORM
502 depends on X86_X2APIC
505 This option is needed in order to support SGI Ultraviolet systems.
506 If you don't have one of these, you should say N here.
508 # Following is an alphabetically sorted list of 32 bit extended platforms
509 # Please maintain the alphabetic order if and when there are additions
512 bool "Goldfish (Virtual Platform)"
513 depends on X86_EXTENDED_PLATFORM
515 Enable support for the Goldfish virtual platform used primarily
516 for Android development. Unless you are building for the Android
517 Goldfish emulator say N here.
520 bool "CE4100 TV platform"
522 depends on PCI_GODIRECT
523 depends on X86_IO_APIC
525 depends on X86_EXTENDED_PLATFORM
526 select X86_REBOOTFIXUPS
528 select OF_EARLY_FLATTREE
530 Select for the Intel CE media processor (CE4100) SOC.
531 This option compiles in support for the CE4100 SOC for settop
532 boxes and media devices.
535 bool "Intel MID platform support"
536 depends on X86_EXTENDED_PLATFORM
537 depends on X86_PLATFORM_DEVICES
539 depends on X86_64 || (PCI_GOANY && X86_32)
540 depends on X86_IO_APIC
546 select MFD_INTEL_MSIC
548 Select to build a kernel capable of supporting Intel MID (Mobile
549 Internet Device) platform systems which do not have the PCI legacy
550 interfaces. If you are building for a PC class system say N here.
552 Intel MID platforms are based on an Intel processor and chipset which
553 consume less power than most of the x86 derivatives.
555 config X86_INTEL_QUARK
556 bool "Intel Quark platform support"
558 depends on X86_EXTENDED_PLATFORM
559 depends on X86_PLATFORM_DEVICES
563 depends on X86_IO_APIC
568 Select to include support for Quark X1000 SoC.
569 Say Y here if you have a Quark based system such as the Arduino
570 compatible Intel Galileo.
572 config X86_INTEL_LPSS
573 bool "Intel Low Power Subsystem Support"
574 depends on X86 && ACPI
579 Select to build support for Intel Low Power Subsystem such as
580 found on Intel Lynxpoint PCH. Selecting this option enables
581 things like clock tree (common clock framework) and pincontrol
582 which are needed by the LPSS peripheral drivers.
584 config X86_AMD_PLATFORM_DEVICE
585 bool "AMD ACPI2Platform devices support"
590 Select to interpret AMD specific ACPI device to platform device
591 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
592 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
593 implemented under PINCTRL subsystem.
596 tristate "Intel SoC IOSF Sideband support for SoC platforms"
599 This option enables sideband register access support for Intel SoC
600 platforms. On these platforms the IOSF sideband is used in lieu of
601 MSR's for some register accesses, mostly but not limited to thermal
602 and power. Drivers may query the availability of this device to
603 determine if they need the sideband in order to work on these
604 platforms. The sideband is available on the following SoC products.
605 This list is not meant to be exclusive.
610 You should say Y if you are running a kernel on one of these SoC's.
612 config IOSF_MBI_DEBUG
613 bool "Enable IOSF sideband access through debugfs"
614 depends on IOSF_MBI && DEBUG_FS
616 Select this option to expose the IOSF sideband access registers (MCR,
617 MDR, MCRX) through debugfs to write and read register information from
618 different units on the SoC. This is most useful for obtaining device
619 state information for debug and analysis. As this is a general access
620 mechanism, users of this option would have specific knowledge of the
621 device they want to access.
623 If you don't require the option or are in doubt, say N.
626 bool "RDC R-321x SoC"
628 depends on X86_EXTENDED_PLATFORM
630 select X86_REBOOTFIXUPS
632 This option is needed for RDC R-321x system-on-chip, also known
634 If you don't have one of these chips, you should say N here.
636 config X86_32_NON_STANDARD
637 bool "Support non-standard 32-bit SMP architectures"
638 depends on X86_32 && SMP
639 depends on X86_EXTENDED_PLATFORM
641 This option compiles in the bigsmp and STA2X11 default
642 subarchitectures. It is intended for a generic binary
643 kernel. If you select them all, kernel will probe it one by
644 one and will fallback to default.
646 # Alphabetically sorted list of Non standard 32 bit platforms
648 config X86_SUPPORTS_MEMORY_FAILURE
650 # MCE code calls memory_failure():
652 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
653 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
654 depends on X86_64 || !SPARSEMEM
655 select ARCH_SUPPORTS_MEMORY_FAILURE
658 bool "STA2X11 Companion Chip Support"
659 depends on X86_32_NON_STANDARD && PCI
660 select X86_DEV_DMA_OPS
667 This adds support for boards based on the STA2X11 IO-Hub,
668 a.k.a. "ConneXt". The chip is used in place of the standard
669 PC chipset, so all "standard" peripherals are missing. If this
670 option is selected the kernel will still be able to boot on
671 standard PC machines.
674 tristate "Eurobraille/Iris poweroff module"
677 The Iris machines from EuroBraille do not have APM or ACPI support
678 to shut themselves down properly. A special I/O sequence is
679 needed to do so, which is what this module does at
682 This is only for Iris machines from EuroBraille.
686 config SCHED_OMIT_FRAME_POINTER
688 prompt "Single-depth WCHAN output"
691 Calculate simpler /proc/<PID>/wchan values. If this option
692 is disabled then wchan values will recurse back to the
693 caller function. This provides more accurate wchan values,
694 at the expense of slightly more scheduling overhead.
696 If in doubt, say "Y".
698 menuconfig HYPERVISOR_GUEST
699 bool "Linux guest support"
701 Say Y here to enable options for running Linux under various hyper-
702 visors. This option enables basic hypervisor detection and platform
705 If you say N, all options in this submenu will be skipped and
706 disabled, and Linux guest support won't be built in.
711 bool "Enable paravirtualization code"
713 This changes the kernel so it can modify itself when it is run
714 under a hypervisor, potentially improving performance significantly
715 over full virtualization. However, when run without a hypervisor
716 the kernel is theoretically slower and slightly larger.
718 config PARAVIRT_DEBUG
719 bool "paravirt-ops debugging"
720 depends on PARAVIRT && DEBUG_KERNEL
722 Enable to debug paravirt_ops internals. Specifically, BUG if
723 a paravirt_op is missing when it is called.
725 config PARAVIRT_SPINLOCKS
726 bool "Paravirtualization layer for spinlocks"
727 depends on PARAVIRT && SMP
729 Paravirtualized spinlocks allow a pvops backend to replace the
730 spinlock implementation with something virtualization-friendly
731 (for example, block the virtual CPU rather than spinning).
733 It has a minimal impact on native kernels and gives a nice performance
734 benefit on paravirtualized KVM / Xen kernels.
736 If you are unsure how to answer this question, answer Y.
738 config QUEUED_LOCK_STAT
739 bool "Paravirt queued spinlock statistics"
740 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
742 Enable the collection of statistical data on the slowpath
743 behavior of paravirtualized queued spinlocks and report
746 source "arch/x86/xen/Kconfig"
749 bool "KVM Guest support (including kvmclock)"
751 select PARAVIRT_CLOCK
754 This option enables various optimizations for running under the KVM
755 hypervisor. It includes a paravirtualized clock, so that instead
756 of relying on a PIT (or probably other) emulation by the
757 underlying device model, the host provides the guest with
758 timing infrastructure such as time of day, and system time
761 bool "Enable debug information for KVM Guests in debugfs"
762 depends on KVM_GUEST && DEBUG_FS
765 This option enables collection of various statistics for KVM guest.
766 Statistics are displayed in debugfs filesystem. Enabling this option
767 may incur significant overhead.
769 source "arch/x86/lguest/Kconfig"
771 config PARAVIRT_TIME_ACCOUNTING
772 bool "Paravirtual steal time accounting"
776 Select this option to enable fine granularity task steal time
777 accounting. Time spent executing other tasks in parallel with
778 the current vCPU is discounted from the vCPU power. To account for
779 that, there can be a small performance impact.
781 If in doubt, say N here.
783 config PARAVIRT_CLOCK
786 endif #HYPERVISOR_GUEST
791 source "arch/x86/Kconfig.cpu"
795 prompt "HPET Timer Support" if X86_32
797 Use the IA-PC HPET (High Precision Event Timer) to manage
798 time in preference to the PIT and RTC, if a HPET is
800 HPET is the next generation timer replacing legacy 8254s.
801 The HPET provides a stable time base on SMP
802 systems, unlike the TSC, but it is more expensive to access,
803 as it is off-chip. The interface used is documented
804 in the HPET spec, revision 1.
806 You can safely choose Y here. However, HPET will only be
807 activated if the platform and the BIOS support this feature.
808 Otherwise the 8254 will be used for timing services.
810 Choose N to continue using the legacy 8254 timer.
812 config HPET_EMULATE_RTC
814 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
817 def_bool y if X86_INTEL_MID
818 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
820 depends on X86_INTEL_MID && SFI
822 APB timer is the replacement for 8254, HPET on X86 MID platforms.
823 The APBT provides a stable time base on SMP
824 systems, unlike the TSC, but it is more expensive to access,
825 as it is off-chip. APB timers are always running regardless of CPU
826 C states, they are used as per CPU clockevent device when possible.
828 # Mark as expert because too many people got it wrong.
829 # The code disables itself when not needed.
832 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
833 bool "Enable DMI scanning" if EXPERT
835 Enabled scanning of DMI to identify machine quirks. Say Y
836 here unless you have verified that your setup is not
837 affected by entries in the DMI blacklist. Required by PNP
841 bool "Old AMD GART IOMMU support"
843 depends on X86_64 && PCI && AMD_NB
845 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
846 GART based hardware IOMMUs.
848 The GART supports full DMA access for devices with 32-bit access
849 limitations, on systems with more than 3 GB. This is usually needed
850 for USB, sound, many IDE/SATA chipsets and some other devices.
852 Newer systems typically have a modern AMD IOMMU, supported via
853 the CONFIG_AMD_IOMMU=y config option.
855 In normal configurations this driver is only active when needed:
856 there's more than 3 GB of memory and the system contains a
857 32-bit limited device.
862 bool "IBM Calgary IOMMU support"
864 depends on X86_64 && PCI
866 Support for hardware IOMMUs in IBM's xSeries x366 and x460
867 systems. Needed to run systems with more than 3GB of memory
868 properly with 32-bit PCI devices that do not support DAC
869 (Double Address Cycle). Calgary also supports bus level
870 isolation, where all DMAs pass through the IOMMU. This
871 prevents them from going anywhere except their intended
872 destination. This catches hard-to-find kernel bugs and
873 mis-behaving drivers and devices that do not use the DMA-API
874 properly to set up their DMA buffers. The IOMMU can be
875 turned off at boot time with the iommu=off parameter.
876 Normally the kernel will make the right choice by itself.
879 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
881 prompt "Should Calgary be enabled by default?"
882 depends on CALGARY_IOMMU
884 Should Calgary be enabled by default? if you choose 'y', Calgary
885 will be used (if it exists). If you choose 'n', Calgary will not be
886 used even if it exists. If you choose 'n' and would like to use
887 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
890 # need this always selected by IOMMU for the VIA workaround
894 Support for software bounce buffers used on x86-64 systems
895 which don't have a hardware IOMMU. Using this PCI devices
896 which can only access 32-bits of memory can be used on systems
897 with more than 3 GB of memory.
902 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
905 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
906 depends on X86_64 && SMP && DEBUG_KERNEL
907 select CPUMASK_OFFSTACK
909 Enable maximum number of CPUS and NUMA Nodes for this architecture.
913 int "Maximum number of CPUs" if SMP && !MAXSMP
914 range 2 8 if SMP && X86_32 && !X86_BIGSMP
915 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
916 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
918 default "8192" if MAXSMP
919 default "32" if SMP && X86_BIGSMP
920 default "8" if SMP && X86_32
923 This allows you to specify the maximum number of CPUs which this
924 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
925 supported value is 8192, otherwise the maximum value is 512. The
926 minimum value which makes sense is 2.
928 This is purely to save memory - each supported CPU adds
929 approximately eight kilobytes to the kernel image.
932 bool "SMT (Hyperthreading) scheduler support"
935 SMT scheduler support improves the CPU scheduler's decision making
936 when dealing with Intel Pentium 4 chips with HyperThreading at a
937 cost of slightly increased overhead in some places. If unsure say
942 prompt "Multi-core scheduler support"
945 Multi-core scheduler support improves the CPU scheduler's decision
946 making when dealing with multi-core CPU chips at a cost of slightly
947 increased overhead in some places. If unsure say N here.
950 bool "CPU core priorities scheduler support"
951 depends on SCHED_MC && CPU_SUP_INTEL
952 select X86_INTEL_PSTATE
956 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
957 core ordering determined at manufacturing time, which allows
958 certain cores to reach higher turbo frequencies (when running
959 single threaded workloads) than others.
961 Enabling this kernel feature teaches the scheduler about
962 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
963 scheduler's CPU selection logic accordingly, so that higher
964 overall system performance can be achieved.
966 This feature will have no effect on CPUs without this feature.
968 If unsure say Y here.
970 source "kernel/Kconfig.preempt"
974 depends on !SMP && X86_LOCAL_APIC
977 bool "Local APIC support on uniprocessors" if !PCI_MSI
979 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
981 A local APIC (Advanced Programmable Interrupt Controller) is an
982 integrated interrupt controller in the CPU. If you have a single-CPU
983 system which has a processor with a local APIC, you can say Y here to
984 enable and use it. If you say Y here even though your machine doesn't
985 have a local APIC, then the kernel will still run with no slowdown at
986 all. The local APIC supports CPU-generated self-interrupts (timer,
987 performance counters), and the NMI watchdog which detects hard
991 bool "IO-APIC support on uniprocessors"
992 depends on X86_UP_APIC
994 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
995 SMP-capable replacement for PC-style interrupt controllers. Most
996 SMP systems and many recent uniprocessor systems have one.
998 If you have a single-CPU system with an IO-APIC, you can say Y here
999 to use it. If you say Y here even though your machine doesn't have
1000 an IO-APIC, then the kernel will still run with no slowdown at all.
1002 config X86_LOCAL_APIC
1004 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1005 select IRQ_DOMAIN_HIERARCHY
1006 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1010 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1012 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1013 bool "Reroute for broken boot IRQs"
1014 depends on X86_IO_APIC
1016 This option enables a workaround that fixes a source of
1017 spurious interrupts. This is recommended when threaded
1018 interrupt handling is used on systems where the generation of
1019 superfluous "boot interrupts" cannot be disabled.
1021 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1022 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1023 kernel does during interrupt handling). On chipsets where this
1024 boot IRQ generation cannot be disabled, this workaround keeps
1025 the original IRQ line masked so that only the equivalent "boot
1026 IRQ" is delivered to the CPUs. The workaround also tells the
1027 kernel to set up the IRQ handler on the boot IRQ line. In this
1028 way only one interrupt is delivered to the kernel. Otherwise
1029 the spurious second interrupt may cause the kernel to bring
1030 down (vital) interrupt lines.
1032 Only affects "broken" chipsets. Interrupt sharing may be
1033 increased on these systems.
1036 bool "Machine Check / overheating reporting"
1037 select GENERIC_ALLOCATOR
1040 Machine Check support allows the processor to notify the
1041 kernel if it detects a problem (e.g. overheating, data corruption).
1042 The action the kernel takes depends on the severity of the problem,
1043 ranging from warning messages to halting the machine.
1045 config X86_MCE_INTEL
1047 prompt "Intel MCE features"
1048 depends on X86_MCE && X86_LOCAL_APIC
1050 Additional support for intel specific MCE features such as
1051 the thermal monitor.
1055 prompt "AMD MCE features"
1056 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1058 Additional support for AMD specific MCE features such as
1059 the DRAM Error Threshold.
1061 config X86_ANCIENT_MCE
1062 bool "Support for old Pentium 5 / WinChip machine checks"
1063 depends on X86_32 && X86_MCE
1065 Include support for machine check handling on old Pentium 5 or WinChip
1066 systems. These typically need to be enabled explicitly on the command
1069 config X86_MCE_THRESHOLD
1070 depends on X86_MCE_AMD || X86_MCE_INTEL
1073 config X86_MCE_INJECT
1074 depends on X86_MCE && X86_LOCAL_APIC
1075 tristate "Machine check injector support"
1077 Provide support for injecting machine checks for testing purposes.
1078 If you don't know what a machine check is and you don't do kernel
1079 QA it is safe to say n.
1081 config X86_THERMAL_VECTOR
1083 depends on X86_MCE_INTEL
1085 source "arch/x86/events/Kconfig"
1087 config X86_LEGACY_VM86
1088 bool "Legacy VM86 support"
1092 This option allows user programs to put the CPU into V8086
1093 mode, which is an 80286-era approximation of 16-bit real mode.
1095 Some very old versions of X and/or vbetool require this option
1096 for user mode setting. Similarly, DOSEMU will use it if
1097 available to accelerate real mode DOS programs. However, any
1098 recent version of DOSEMU, X, or vbetool should be fully
1099 functional even without kernel VM86 support, as they will all
1100 fall back to software emulation. Nevertheless, if you are using
1101 a 16-bit DOS program where 16-bit performance matters, vm86
1102 mode might be faster than emulation and you might want to
1105 Note that any app that works on a 64-bit kernel is unlikely to
1106 need this option, as 64-bit kernels don't, and can't, support
1107 V8086 mode. This option is also unrelated to 16-bit protected
1108 mode and is not needed to run most 16-bit programs under Wine.
1110 Enabling this option increases the complexity of the kernel
1111 and slows down exception handling a tiny bit.
1113 If unsure, say N here.
1117 default X86_LEGACY_VM86
1120 bool "Enable support for 16-bit segments" if EXPERT
1122 depends on MODIFY_LDT_SYSCALL
1124 This option is required by programs like Wine to run 16-bit
1125 protected mode legacy code on x86 processors. Disabling
1126 this option saves about 300 bytes on i386, or around 6K text
1127 plus 16K runtime memory on x86-64,
1131 depends on X86_16BIT && X86_32
1135 depends on X86_16BIT && X86_64
1137 config X86_VSYSCALL_EMULATION
1138 bool "Enable vsyscall emulation" if EXPERT
1142 This enables emulation of the legacy vsyscall page. Disabling
1143 it is roughly equivalent to booting with vsyscall=none, except
1144 that it will also disable the helpful warning if a program
1145 tries to use a vsyscall. With this option set to N, offending
1146 programs will just segfault, citing addresses of the form
1149 This option is required by many programs built before 2013, and
1150 care should be used even with newer programs if set to N.
1152 Disabling this option saves about 7K of kernel size and
1153 possibly 4K of additional runtime pagetable memory.
1156 tristate "Toshiba Laptop support"
1159 This adds a driver to safely access the System Management Mode of
1160 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1161 not work on models with a Phoenix BIOS. The System Management Mode
1162 is used to set the BIOS and power saving options on Toshiba portables.
1164 For information on utilities to make use of this driver see the
1165 Toshiba Linux utilities web site at:
1166 <http://www.buzzard.org.uk/toshiba/>.
1168 Say Y if you intend to run this kernel on a Toshiba portable.
1172 tristate "Dell i8k legacy laptop support"
1174 select SENSORS_DELL_SMM
1176 This option enables legacy /proc/i8k userspace interface in hwmon
1177 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1178 temperature and allows controlling fan speeds of Dell laptops via
1179 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1180 it reports also power and hotkey status. For fan speed control is
1181 needed userspace package i8kutils.
1183 Say Y if you intend to run this kernel on old Dell laptops or want to
1184 use userspace package i8kutils.
1187 config X86_REBOOTFIXUPS
1188 bool "Enable X86 board specific fixups for reboot"
1191 This enables chipset and/or board specific fixups to be done
1192 in order to get reboot to work correctly. This is only needed on
1193 some combinations of hardware and BIOS. The symptom, for which
1194 this config is intended, is when reboot ends with a stalled/hung
1197 Currently, the only fixup is for the Geode machines using
1198 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1200 Say Y if you want to enable the fixup. Currently, it's safe to
1201 enable this option even if you don't need it.
1205 bool "CPU microcode loading support"
1207 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1210 If you say Y here, you will be able to update the microcode on
1211 Intel and AMD processors. The Intel support is for the IA32 family,
1212 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1213 AMD support is for families 0x10 and later. You will obviously need
1214 the actual microcode binary data itself which is not shipped with
1217 The preferred method to load microcode from a detached initrd is described
1218 in Documentation/x86/early-microcode.txt. For that you need to enable
1219 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1220 initrd for microcode blobs.
1222 In addition, you can build-in the microcode into the kernel. For that you
1223 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1224 to the CONFIG_EXTRA_FIRMWARE config option.
1226 config MICROCODE_INTEL
1227 bool "Intel microcode loading support"
1228 depends on MICROCODE
1232 This options enables microcode patch loading support for Intel
1235 For the current Intel microcode data package go to
1236 <https://downloadcenter.intel.com> and search for
1237 'Linux Processor Microcode Data File'.
1239 config MICROCODE_AMD
1240 bool "AMD microcode loading support"
1241 depends on MICROCODE
1244 If you select this option, microcode patch loading support for AMD
1245 processors will be enabled.
1247 config MICROCODE_OLD_INTERFACE
1249 depends on MICROCODE
1252 tristate "/dev/cpu/*/msr - Model-specific register support"
1254 This device gives privileged processes access to the x86
1255 Model-Specific Registers (MSRs). It is a character device with
1256 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1257 MSR accesses are directed to a specific CPU on multi-processor
1261 tristate "/dev/cpu/*/cpuid - CPU information support"
1263 This device gives processes access to the x86 CPUID instruction to
1264 be executed on a specific processor. It is a character device
1265 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1269 prompt "High Memory Support"
1276 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1277 However, the address space of 32-bit x86 processors is only 4
1278 Gigabytes large. That means that, if you have a large amount of
1279 physical memory, not all of it can be "permanently mapped" by the
1280 kernel. The physical memory that's not permanently mapped is called
1283 If you are compiling a kernel which will never run on a machine with
1284 more than 1 Gigabyte total physical RAM, answer "off" here (default
1285 choice and suitable for most users). This will result in a "3GB/1GB"
1286 split: 3GB are mapped so that each process sees a 3GB virtual memory
1287 space and the remaining part of the 4GB virtual memory space is used
1288 by the kernel to permanently map as much physical memory as
1291 If the machine has between 1 and 4 Gigabytes physical RAM, then
1294 If more than 4 Gigabytes is used then answer "64GB" here. This
1295 selection turns Intel PAE (Physical Address Extension) mode on.
1296 PAE implements 3-level paging on IA32 processors. PAE is fully
1297 supported by Linux, PAE mode is implemented on all recent Intel
1298 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1299 then the kernel will not boot on CPUs that don't support PAE!
1301 The actual amount of total physical memory will either be
1302 auto detected or can be forced by using a kernel command line option
1303 such as "mem=256M". (Try "man bootparam" or see the documentation of
1304 your boot loader (lilo or loadlin) about how to pass options to the
1305 kernel at boot time.)
1307 If unsure, say "off".
1312 Select this if you have a 32-bit processor and between 1 and 4
1313 gigabytes of physical RAM.
1320 Select this if you have a 32-bit processor and more than 4
1321 gigabytes of physical RAM.
1326 prompt "Memory split" if EXPERT
1330 Select the desired split between kernel and user memory.
1332 If the address range available to the kernel is less than the
1333 physical memory installed, the remaining memory will be available
1334 as "high memory". Accessing high memory is a little more costly
1335 than low memory, as it needs to be mapped into the kernel first.
1336 Note that increasing the kernel address space limits the range
1337 available to user programs, making the address space there
1338 tighter. Selecting anything other than the default 3G/1G split
1339 will also likely make your kernel incompatible with binary-only
1342 If you are not absolutely sure what you are doing, leave this
1346 bool "3G/1G user/kernel split"
1347 config VMSPLIT_3G_OPT
1349 bool "3G/1G user/kernel split (for full 1G low memory)"
1351 bool "2G/2G user/kernel split"
1352 config VMSPLIT_2G_OPT
1354 bool "2G/2G user/kernel split (for full 2G low memory)"
1356 bool "1G/3G user/kernel split"
1361 default 0xB0000000 if VMSPLIT_3G_OPT
1362 default 0x80000000 if VMSPLIT_2G
1363 default 0x78000000 if VMSPLIT_2G_OPT
1364 default 0x40000000 if VMSPLIT_1G
1370 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1373 bool "PAE (Physical Address Extension) Support"
1374 depends on X86_32 && !HIGHMEM4G
1377 PAE is required for NX support, and furthermore enables
1378 larger swapspace support for non-overcommit purposes. It
1379 has the cost of more pagetable lookup overhead, and also
1380 consumes more pagetable space per process.
1382 config ARCH_PHYS_ADDR_T_64BIT
1384 depends on X86_64 || X86_PAE
1386 config ARCH_DMA_ADDR_T_64BIT
1388 depends on X86_64 || HIGHMEM64G
1390 config X86_DIRECT_GBPAGES
1392 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1394 Certain kernel features effectively disable kernel
1395 linear 1 GB mappings (even if the CPU otherwise
1396 supports them), so don't confuse the user by printing
1397 that we have them enabled.
1399 # Common NUMA Features
1401 bool "Numa Memory Allocation and Scheduler Support"
1403 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1404 default y if X86_BIGSMP
1406 Enable NUMA (Non Uniform Memory Access) support.
1408 The kernel will try to allocate memory used by a CPU on the
1409 local memory controller of the CPU and add some more
1410 NUMA awareness to the kernel.
1412 For 64-bit this is recommended if the system is Intel Core i7
1413 (or later), AMD Opteron, or EM64T NUMA.
1415 For 32-bit this is only needed if you boot a 32-bit
1416 kernel on a 64-bit NUMA platform.
1418 Otherwise, you should say N.
1422 prompt "Old style AMD Opteron NUMA detection"
1423 depends on X86_64 && NUMA && PCI
1425 Enable AMD NUMA node topology detection. You should say Y here if
1426 you have a multi processor AMD system. This uses an old method to
1427 read the NUMA configuration directly from the builtin Northbridge
1428 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1429 which also takes priority if both are compiled in.
1431 config X86_64_ACPI_NUMA
1433 prompt "ACPI NUMA detection"
1434 depends on X86_64 && NUMA && ACPI && PCI
1437 Enable ACPI SRAT based node topology detection.
1439 # Some NUMA nodes have memory ranges that span
1440 # other nodes. Even though a pfn is valid and
1441 # between a node's start and end pfns, it may not
1442 # reside on that node. See memmap_init_zone()
1444 config NODES_SPAN_OTHER_NODES
1446 depends on X86_64_ACPI_NUMA
1449 bool "NUMA emulation"
1452 Enable NUMA emulation. A flat machine will be split
1453 into virtual nodes when booted with "numa=fake=N", where N is the
1454 number of nodes. This is only useful for debugging.
1457 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1459 default "10" if MAXSMP
1460 default "6" if X86_64
1462 depends on NEED_MULTIPLE_NODES
1464 Specify the maximum number of NUMA Nodes available on the target
1465 system. Increases memory reserved to accommodate various tables.
1467 config ARCH_HAVE_MEMORY_PRESENT
1469 depends on X86_32 && DISCONTIGMEM
1471 config NEED_NODE_MEMMAP_SIZE
1473 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1475 config ARCH_FLATMEM_ENABLE
1477 depends on X86_32 && !NUMA
1479 config ARCH_DISCONTIGMEM_ENABLE
1481 depends on NUMA && X86_32
1483 config ARCH_DISCONTIGMEM_DEFAULT
1485 depends on NUMA && X86_32
1487 config ARCH_SPARSEMEM_ENABLE
1489 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1490 select SPARSEMEM_STATIC if X86_32
1491 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1493 config ARCH_SPARSEMEM_DEFAULT
1497 config ARCH_SELECT_MEMORY_MODEL
1499 depends on ARCH_SPARSEMEM_ENABLE
1501 config ARCH_MEMORY_PROBE
1502 bool "Enable sysfs memory/probe interface"
1503 depends on X86_64 && MEMORY_HOTPLUG
1505 This option enables a sysfs memory/probe interface for testing.
1506 See Documentation/memory-hotplug.txt for more information.
1507 If you are unsure how to answer this question, answer N.
1509 config ARCH_PROC_KCORE_TEXT
1511 depends on X86_64 && PROC_KCORE
1513 config ILLEGAL_POINTER_VALUE
1516 default 0xdead000000000000 if X86_64
1520 config X86_PMEM_LEGACY_DEVICE
1523 config X86_PMEM_LEGACY
1524 tristate "Support non-standard NVDIMMs and ADR protected memory"
1525 depends on PHYS_ADDR_T_64BIT
1527 select X86_PMEM_LEGACY_DEVICE
1530 Treat memory marked using the non-standard e820 type of 12 as used
1531 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1532 The kernel will offer these regions to the 'pmem' driver so
1533 they can be used for persistent storage.
1538 bool "Allocate 3rd-level pagetables from highmem"
1541 The VM uses one page table entry for each page of physical memory.
1542 For systems with a lot of RAM, this can be wasteful of precious
1543 low memory. Setting this option will put user-space page table
1544 entries in high memory.
1546 config X86_CHECK_BIOS_CORRUPTION
1547 bool "Check for low memory corruption"
1549 Periodically check for memory corruption in low memory, which
1550 is suspected to be caused by BIOS. Even when enabled in the
1551 configuration, it is disabled at runtime. Enable it by
1552 setting "memory_corruption_check=1" on the kernel command
1553 line. By default it scans the low 64k of memory every 60
1554 seconds; see the memory_corruption_check_size and
1555 memory_corruption_check_period parameters in
1556 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1558 When enabled with the default parameters, this option has
1559 almost no overhead, as it reserves a relatively small amount
1560 of memory and scans it infrequently. It both detects corruption
1561 and prevents it from affecting the running system.
1563 It is, however, intended as a diagnostic tool; if repeatable
1564 BIOS-originated corruption always affects the same memory,
1565 you can use memmap= to prevent the kernel from using that
1568 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1569 bool "Set the default setting of memory_corruption_check"
1570 depends on X86_CHECK_BIOS_CORRUPTION
1573 Set whether the default state of memory_corruption_check is
1576 config X86_RESERVE_LOW
1577 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1581 Specify the amount of low memory to reserve for the BIOS.
1583 The first page contains BIOS data structures that the kernel
1584 must not use, so that page must always be reserved.
1586 By default we reserve the first 64K of physical RAM, as a
1587 number of BIOSes are known to corrupt that memory range
1588 during events such as suspend/resume or monitor cable
1589 insertion, so it must not be used by the kernel.
1591 You can set this to 4 if you are absolutely sure that you
1592 trust the BIOS to get all its memory reservations and usages
1593 right. If you know your BIOS have problems beyond the
1594 default 64K area, you can set this to 640 to avoid using the
1595 entire low memory range.
1597 If you have doubts about the BIOS (e.g. suspend/resume does
1598 not work or there's kernel crashes after certain hardware
1599 hotplug events) then you might want to enable
1600 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1601 typical corruption patterns.
1603 Leave this to the default value of 64 if you are unsure.
1605 config MATH_EMULATION
1607 depends on MODIFY_LDT_SYSCALL
1608 prompt "Math emulation" if X86_32
1610 Linux can emulate a math coprocessor (used for floating point
1611 operations) if you don't have one. 486DX and Pentium processors have
1612 a math coprocessor built in, 486SX and 386 do not, unless you added
1613 a 487DX or 387, respectively. (The messages during boot time can
1614 give you some hints here ["man dmesg"].) Everyone needs either a
1615 coprocessor or this emulation.
1617 If you don't have a math coprocessor, you need to say Y here; if you
1618 say Y here even though you have a coprocessor, the coprocessor will
1619 be used nevertheless. (This behavior can be changed with the kernel
1620 command line option "no387", which comes handy if your coprocessor
1621 is broken. Try "man bootparam" or see the documentation of your boot
1622 loader (lilo or loadlin) about how to pass options to the kernel at
1623 boot time.) This means that it is a good idea to say Y here if you
1624 intend to use this kernel on different machines.
1626 More information about the internals of the Linux math coprocessor
1627 emulation can be found in <file:arch/x86/math-emu/README>.
1629 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1630 kernel, it won't hurt.
1634 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1636 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1637 the Memory Type Range Registers (MTRRs) may be used to control
1638 processor access to memory ranges. This is most useful if you have
1639 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1640 allows bus write transfers to be combined into a larger transfer
1641 before bursting over the PCI/AGP bus. This can increase performance
1642 of image write operations 2.5 times or more. Saying Y here creates a
1643 /proc/mtrr file which may be used to manipulate your processor's
1644 MTRRs. Typically the X server should use this.
1646 This code has a reasonably generic interface so that similar
1647 control registers on other processors can be easily supported
1650 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1651 Registers (ARRs) which provide a similar functionality to MTRRs. For
1652 these, the ARRs are used to emulate the MTRRs.
1653 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1654 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1655 write-combining. All of these processors are supported by this code
1656 and it makes sense to say Y here if you have one of them.
1658 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1659 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1660 can lead to all sorts of problems, so it's good to say Y here.
1662 You can safely say Y even if your machine doesn't have MTRRs, you'll
1663 just add about 9 KB to your kernel.
1665 See <file:Documentation/x86/mtrr.txt> for more information.
1667 config MTRR_SANITIZER
1669 prompt "MTRR cleanup support"
1672 Convert MTRR layout from continuous to discrete, so X drivers can
1673 add writeback entries.
1675 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1676 The largest mtrr entry size for a continuous block can be set with
1681 config MTRR_SANITIZER_ENABLE_DEFAULT
1682 int "MTRR cleanup enable value (0-1)"
1685 depends on MTRR_SANITIZER
1687 Enable mtrr cleanup default value
1689 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1690 int "MTRR cleanup spare reg num (0-7)"
1693 depends on MTRR_SANITIZER
1695 mtrr cleanup spare entries default, it can be changed via
1696 mtrr_spare_reg_nr=N on the kernel command line.
1700 prompt "x86 PAT support" if EXPERT
1703 Use PAT attributes to setup page level cache control.
1705 PATs are the modern equivalents of MTRRs and are much more
1706 flexible than MTRRs.
1708 Say N here if you see bootup problems (boot crash, boot hang,
1709 spontaneous reboots) or a non-working video driver.
1713 config ARCH_USES_PG_UNCACHED
1719 prompt "x86 architectural random number generator" if EXPERT
1721 Enable the x86 architectural RDRAND instruction
1722 (Intel Bull Mountain technology) to generate random numbers.
1723 If supported, this is a high bandwidth, cryptographically
1724 secure hardware random number generator.
1728 prompt "Supervisor Mode Access Prevention" if EXPERT
1730 Supervisor Mode Access Prevention (SMAP) is a security
1731 feature in newer Intel processors. There is a small
1732 performance cost if this enabled and turned on; there is
1733 also a small increase in the kernel size if this is enabled.
1737 config X86_INTEL_MPX
1738 prompt "Intel MPX (Memory Protection Extensions)"
1740 depends on CPU_SUP_INTEL
1742 MPX provides hardware features that can be used in
1743 conjunction with compiler-instrumented code to check
1744 memory references. It is designed to detect buffer
1745 overflow or underflow bugs.
1747 This option enables running applications which are
1748 instrumented or otherwise use MPX. It does not use MPX
1749 itself inside the kernel or to protect the kernel
1750 against bad memory references.
1752 Enabling this option will make the kernel larger:
1753 ~8k of kernel text and 36 bytes of data on a 64-bit
1754 defconfig. It adds a long to the 'mm_struct' which
1755 will increase the kernel memory overhead of each
1756 process and adds some branches to paths used during
1757 exec() and munmap().
1759 For details, see Documentation/x86/intel_mpx.txt
1763 config X86_INTEL_MEMORY_PROTECTION_KEYS
1764 prompt "Intel Memory Protection Keys"
1766 # Note: only available in 64-bit mode
1767 depends on CPU_SUP_INTEL && X86_64
1768 select ARCH_USES_HIGH_VMA_FLAGS
1769 select ARCH_HAS_PKEYS
1771 Memory Protection Keys provides a mechanism for enforcing
1772 page-based protections, but without requiring modification of the
1773 page tables when an application changes protection domains.
1775 For details, see Documentation/x86/protection-keys.txt
1780 bool "EFI runtime service support"
1783 select EFI_RUNTIME_WRAPPERS
1785 This enables the kernel to use EFI runtime services that are
1786 available (such as the EFI variable services).
1788 This option is only useful on systems that have EFI firmware.
1789 In addition, you should use the latest ELILO loader available
1790 at <http://elilo.sourceforge.net> in order to take advantage
1791 of EFI runtime services. However, even with this option, the
1792 resultant kernel should continue to boot on existing non-EFI
1796 bool "EFI stub support"
1797 depends on EFI && !X86_USE_3DNOW
1800 This kernel feature allows a bzImage to be loaded directly
1801 by EFI firmware without the use of a bootloader.
1803 See Documentation/efi-stub.txt for more information.
1806 bool "EFI mixed-mode support"
1807 depends on EFI_STUB && X86_64
1809 Enabling this feature allows a 64-bit kernel to be booted
1810 on a 32-bit firmware, provided that your CPU supports 64-bit
1813 Note that it is not possible to boot a mixed-mode enabled
1814 kernel via the EFI boot stub - a bootloader that supports
1815 the EFI handover protocol must be used.
1821 prompt "Enable seccomp to safely compute untrusted bytecode"
1823 This kernel feature is useful for number crunching applications
1824 that may need to compute untrusted bytecode during their
1825 execution. By using pipes or other transports made available to
1826 the process as file descriptors supporting the read/write
1827 syscalls, it's possible to isolate those applications in
1828 their own address space using seccomp. Once seccomp is
1829 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1830 and the task is only allowed to execute a few safe syscalls
1831 defined by each seccomp mode.
1833 If unsure, say Y. Only embedded should say N here.
1835 source kernel/Kconfig.hz
1838 bool "kexec system call"
1841 kexec is a system call that implements the ability to shutdown your
1842 current kernel, and to start another kernel. It is like a reboot
1843 but it is independent of the system firmware. And like a reboot
1844 you can start any kernel with it, not just Linux.
1846 The name comes from the similarity to the exec system call.
1848 It is an ongoing process to be certain the hardware in a machine
1849 is properly shutdown, so do not be surprised if this code does not
1850 initially work for you. As of this writing the exact hardware
1851 interface is strongly in flux, so no good recommendation can be
1855 bool "kexec file based system call"
1860 depends on CRYPTO_SHA256=y
1862 This is new version of kexec system call. This system call is
1863 file based and takes file descriptors as system call argument
1864 for kernel and initramfs as opposed to list of segments as
1865 accepted by previous system call.
1867 config KEXEC_VERIFY_SIG
1868 bool "Verify kernel signature during kexec_file_load() syscall"
1869 depends on KEXEC_FILE
1871 This option makes kernel signature verification mandatory for
1872 the kexec_file_load() syscall.
1874 In addition to that option, you need to enable signature
1875 verification for the corresponding kernel image type being
1876 loaded in order for this to work.
1878 config KEXEC_BZIMAGE_VERIFY_SIG
1879 bool "Enable bzImage signature verification support"
1880 depends on KEXEC_VERIFY_SIG
1881 depends on SIGNED_PE_FILE_VERIFICATION
1882 select SYSTEM_TRUSTED_KEYRING
1884 Enable bzImage signature verification support.
1887 bool "kernel crash dumps"
1888 depends on X86_64 || (X86_32 && HIGHMEM)
1890 Generate crash dump after being started by kexec.
1891 This should be normally only set in special crash dump kernels
1892 which are loaded in the main kernel with kexec-tools into
1893 a specially reserved region and then later executed after
1894 a crash by kdump/kexec. The crash dump kernel must be compiled
1895 to a memory address not used by the main kernel or BIOS using
1896 PHYSICAL_START, or it must be built as a relocatable image
1897 (CONFIG_RELOCATABLE=y).
1898 For more details see Documentation/kdump/kdump.txt
1902 depends on KEXEC && HIBERNATION
1904 Jump between original kernel and kexeced kernel and invoke
1905 code in physical address mode via KEXEC
1907 config PHYSICAL_START
1908 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1911 This gives the physical address where the kernel is loaded.
1913 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1914 bzImage will decompress itself to above physical address and
1915 run from there. Otherwise, bzImage will run from the address where
1916 it has been loaded by the boot loader and will ignore above physical
1919 In normal kdump cases one does not have to set/change this option
1920 as now bzImage can be compiled as a completely relocatable image
1921 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1922 address. This option is mainly useful for the folks who don't want
1923 to use a bzImage for capturing the crash dump and want to use a
1924 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1925 to be specifically compiled to run from a specific memory area
1926 (normally a reserved region) and this option comes handy.
1928 So if you are using bzImage for capturing the crash dump,
1929 leave the value here unchanged to 0x1000000 and set
1930 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1931 for capturing the crash dump change this value to start of
1932 the reserved region. In other words, it can be set based on
1933 the "X" value as specified in the "crashkernel=YM@XM"
1934 command line boot parameter passed to the panic-ed
1935 kernel. Please take a look at Documentation/kdump/kdump.txt
1936 for more details about crash dumps.
1938 Usage of bzImage for capturing the crash dump is recommended as
1939 one does not have to build two kernels. Same kernel can be used
1940 as production kernel and capture kernel. Above option should have
1941 gone away after relocatable bzImage support is introduced. But it
1942 is present because there are users out there who continue to use
1943 vmlinux for dump capture. This option should go away down the
1946 Don't change this unless you know what you are doing.
1949 bool "Build a relocatable kernel"
1952 This builds a kernel image that retains relocation information
1953 so it can be loaded someplace besides the default 1MB.
1954 The relocations tend to make the kernel binary about 10% larger,
1955 but are discarded at runtime.
1957 One use is for the kexec on panic case where the recovery kernel
1958 must live at a different physical address than the primary
1961 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1962 it has been loaded at and the compile time physical address
1963 (CONFIG_PHYSICAL_START) is used as the minimum location.
1965 config RANDOMIZE_BASE
1966 bool "Randomize the address of the kernel image (KASLR)"
1967 depends on RELOCATABLE
1970 In support of Kernel Address Space Layout Randomization (KASLR),
1971 this randomizes the physical address at which the kernel image
1972 is decompressed and the virtual address where the kernel
1973 image is mapped, as a security feature that deters exploit
1974 attempts relying on knowledge of the location of kernel
1977 On 64-bit, the kernel physical and virtual addresses are
1978 randomized separately. The physical address will be anywhere
1979 between 16MB and the top of physical memory (up to 64TB). The
1980 virtual address will be randomized from 16MB up to 1GB (9 bits
1981 of entropy). Note that this also reduces the memory space
1982 available to kernel modules from 1.5GB to 1GB.
1984 On 32-bit, the kernel physical and virtual addresses are
1985 randomized together. They will be randomized from 16MB up to
1986 512MB (8 bits of entropy).
1988 Entropy is generated using the RDRAND instruction if it is
1989 supported. If RDTSC is supported, its value is mixed into
1990 the entropy pool as well. If neither RDRAND nor RDTSC are
1991 supported, then entropy is read from the i8254 timer. The
1992 usable entropy is limited by the kernel being built using
1993 2GB addressing, and that PHYSICAL_ALIGN must be at a
1994 minimum of 2MB. As a result, only 10 bits of entropy are
1995 theoretically possible, but the implementations are further
1996 limited due to memory layouts.
2000 # Relocation on x86 needs some additional build support
2001 config X86_NEED_RELOCS
2003 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2005 config PHYSICAL_ALIGN
2006 hex "Alignment value to which kernel should be aligned"
2008 range 0x2000 0x1000000 if X86_32
2009 range 0x200000 0x1000000 if X86_64
2011 This value puts the alignment restrictions on physical address
2012 where kernel is loaded and run from. Kernel is compiled for an
2013 address which meets above alignment restriction.
2015 If bootloader loads the kernel at a non-aligned address and
2016 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2017 address aligned to above value and run from there.
2019 If bootloader loads the kernel at a non-aligned address and
2020 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2021 load address and decompress itself to the address it has been
2022 compiled for and run from there. The address for which kernel is
2023 compiled already meets above alignment restrictions. Hence the
2024 end result is that kernel runs from a physical address meeting
2025 above alignment restrictions.
2027 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2028 this value must be a multiple of 0x200000.
2030 Don't change this unless you know what you are doing.
2032 config RANDOMIZE_MEMORY
2033 bool "Randomize the kernel memory sections"
2035 depends on RANDOMIZE_BASE
2036 default RANDOMIZE_BASE
2038 Randomizes the base virtual address of kernel memory sections
2039 (physical memory mapping, vmalloc & vmemmap). This security feature
2040 makes exploits relying on predictable memory locations less reliable.
2042 The order of allocations remains unchanged. Entropy is generated in
2043 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2044 configuration have in average 30,000 different possible virtual
2045 addresses for each memory section.
2049 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2050 hex "Physical memory mapping padding" if EXPERT
2051 depends on RANDOMIZE_MEMORY
2052 default "0xa" if MEMORY_HOTPLUG
2054 range 0x1 0x40 if MEMORY_HOTPLUG
2057 Define the padding in terabytes added to the existing physical
2058 memory size during kernel memory randomization. It is useful
2059 for memory hotplug support but reduces the entropy available for
2060 address randomization.
2062 If unsure, leave at the default value.
2065 bool "Support for hot-pluggable CPUs"
2068 Say Y here to allow turning CPUs off and on. CPUs can be
2069 controlled through /sys/devices/system/cpu.
2070 ( Note: power management support will enable this option
2071 automatically on SMP systems. )
2072 Say N if you want to disable CPU hotplug.
2074 config BOOTPARAM_HOTPLUG_CPU0
2075 bool "Set default setting of cpu0_hotpluggable"
2077 depends on HOTPLUG_CPU
2079 Set whether default state of cpu0_hotpluggable is on or off.
2081 Say Y here to enable CPU0 hotplug by default. If this switch
2082 is turned on, there is no need to give cpu0_hotplug kernel
2083 parameter and the CPU0 hotplug feature is enabled by default.
2085 Please note: there are two known CPU0 dependencies if you want
2086 to enable the CPU0 hotplug feature either by this switch or by
2087 cpu0_hotplug kernel parameter.
2089 First, resume from hibernate or suspend always starts from CPU0.
2090 So hibernate and suspend are prevented if CPU0 is offline.
2092 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2093 offline if any interrupt can not migrate out of CPU0. There may
2094 be other CPU0 dependencies.
2096 Please make sure the dependencies are under your control before
2097 you enable this feature.
2099 Say N if you don't want to enable CPU0 hotplug feature by default.
2100 You still can enable the CPU0 hotplug feature at boot by kernel
2101 parameter cpu0_hotplug.
2103 config DEBUG_HOTPLUG_CPU0
2105 prompt "Debug CPU0 hotplug"
2106 depends on HOTPLUG_CPU
2108 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2109 soon as possible and boots up userspace with CPU0 offlined. User
2110 can online CPU0 back after boot time.
2112 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2113 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2114 compilation or giving cpu0_hotplug kernel parameter at boot.
2120 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2121 depends on COMPAT_32
2123 Certain buggy versions of glibc will crash if they are
2124 presented with a 32-bit vDSO that is not mapped at the address
2125 indicated in its segment table.
2127 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2128 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2129 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2130 the only released version with the bug, but OpenSUSE 9
2131 contains a buggy "glibc 2.3.2".
2133 The symptom of the bug is that everything crashes on startup, saying:
2134 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2136 Saying Y here changes the default value of the vdso32 boot
2137 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2138 This works around the glibc bug but hurts performance.
2140 If unsure, say N: if you are compiling your own kernel, you
2141 are unlikely to be using a buggy version of glibc.
2144 prompt "vsyscall table for legacy applications"
2146 default LEGACY_VSYSCALL_EMULATE
2148 Legacy user code that does not know how to find the vDSO expects
2149 to be able to issue three syscalls by calling fixed addresses in
2150 kernel space. Since this location is not randomized with ASLR,
2151 it can be used to assist security vulnerability exploitation.
2153 This setting can be changed at boot time via the kernel command
2154 line parameter vsyscall=[native|emulate|none].
2156 On a system with recent enough glibc (2.14 or newer) and no
2157 static binaries, you can say None without a performance penalty
2158 to improve security.
2160 If unsure, select "Emulate".
2162 config LEGACY_VSYSCALL_NATIVE
2165 Actual executable code is located in the fixed vsyscall
2166 address mapping, implementing time() efficiently. Since
2167 this makes the mapping executable, it can be used during
2168 security vulnerability exploitation (traditionally as
2169 ROP gadgets). This configuration is not recommended.
2171 config LEGACY_VSYSCALL_EMULATE
2174 The kernel traps and emulates calls into the fixed
2175 vsyscall address mapping. This makes the mapping
2176 non-executable, but it still contains known contents,
2177 which could be used in certain rare security vulnerability
2178 exploits. This configuration is recommended when userspace
2179 still uses the vsyscall area.
2181 config LEGACY_VSYSCALL_NONE
2184 There will be no vsyscall mapping at all. This will
2185 eliminate any risk of ASLR bypass due to the vsyscall
2186 fixed address mapping. Attempts to use the vsyscalls
2187 will be reported to dmesg, so that either old or
2188 malicious userspace programs can be identified.
2193 bool "Built-in kernel command line"
2195 Allow for specifying boot arguments to the kernel at
2196 build time. On some systems (e.g. embedded ones), it is
2197 necessary or convenient to provide some or all of the
2198 kernel boot arguments with the kernel itself (that is,
2199 to not rely on the boot loader to provide them.)
2201 To compile command line arguments into the kernel,
2202 set this option to 'Y', then fill in the
2203 boot arguments in CONFIG_CMDLINE.
2205 Systems with fully functional boot loaders (i.e. non-embedded)
2206 should leave this option set to 'N'.
2209 string "Built-in kernel command string"
2210 depends on CMDLINE_BOOL
2213 Enter arguments here that should be compiled into the kernel
2214 image and used at boot time. If the boot loader provides a
2215 command line at boot time, it is appended to this string to
2216 form the full kernel command line, when the system boots.
2218 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2219 change this behavior.
2221 In most cases, the command line (whether built-in or provided
2222 by the boot loader) should specify the device for the root
2225 config CMDLINE_OVERRIDE
2226 bool "Built-in command line overrides boot loader arguments"
2227 depends on CMDLINE_BOOL
2229 Set this option to 'Y' to have the kernel ignore the boot loader
2230 command line, and use ONLY the built-in command line.
2232 This is used to work around broken boot loaders. This should
2233 be set to 'N' under normal conditions.
2235 config MODIFY_LDT_SYSCALL
2236 bool "Enable the LDT (local descriptor table)" if EXPERT
2239 Linux can allow user programs to install a per-process x86
2240 Local Descriptor Table (LDT) using the modify_ldt(2) system
2241 call. This is required to run 16-bit or segmented code such as
2242 DOSEMU or some Wine programs. It is also used by some very old
2243 threading libraries.
2245 Enabling this feature adds a small amount of overhead to
2246 context switches and increases the low-level kernel attack
2247 surface. Disabling it removes the modify_ldt(2) system call.
2249 Saying 'N' here may make sense for embedded or server kernels.
2251 source "kernel/livepatch/Kconfig"
2255 config ARCH_ENABLE_MEMORY_HOTPLUG
2257 depends on X86_64 || (X86_32 && HIGHMEM)
2259 config ARCH_ENABLE_MEMORY_HOTREMOVE
2261 depends on MEMORY_HOTPLUG
2263 config USE_PERCPU_NUMA_NODE_ID
2267 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2269 depends on X86_64 || X86_PAE
2271 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2273 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2275 menu "Power management and ACPI options"
2277 config ARCH_HIBERNATION_HEADER
2279 depends on X86_64 && HIBERNATION
2281 source "kernel/power/Kconfig"
2283 source "drivers/acpi/Kconfig"
2285 source "drivers/sfi/Kconfig"
2292 tristate "APM (Advanced Power Management) BIOS support"
2293 depends on X86_32 && PM_SLEEP
2295 APM is a BIOS specification for saving power using several different
2296 techniques. This is mostly useful for battery powered laptops with
2297 APM compliant BIOSes. If you say Y here, the system time will be
2298 reset after a RESUME operation, the /proc/apm device will provide
2299 battery status information, and user-space programs will receive
2300 notification of APM "events" (e.g. battery status change).
2302 If you select "Y" here, you can disable actual use of the APM
2303 BIOS by passing the "apm=off" option to the kernel at boot time.
2305 Note that the APM support is almost completely disabled for
2306 machines with more than one CPU.
2308 In order to use APM, you will need supporting software. For location
2309 and more information, read <file:Documentation/power/apm-acpi.txt>
2310 and the Battery Powered Linux mini-HOWTO, available from
2311 <http://www.tldp.org/docs.html#howto>.
2313 This driver does not spin down disk drives (see the hdparm(8)
2314 manpage ("man 8 hdparm") for that), and it doesn't turn off
2315 VESA-compliant "green" monitors.
2317 This driver does not support the TI 4000M TravelMate and the ACER
2318 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2319 desktop machines also don't have compliant BIOSes, and this driver
2320 may cause those machines to panic during the boot phase.
2322 Generally, if you don't have a battery in your machine, there isn't
2323 much point in using this driver and you should say N. If you get
2324 random kernel OOPSes or reboots that don't seem to be related to
2325 anything, try disabling/enabling this option (or disabling/enabling
2328 Some other things you should try when experiencing seemingly random,
2331 1) make sure that you have enough swap space and that it is
2333 2) pass the "no-hlt" option to the kernel
2334 3) switch on floating point emulation in the kernel and pass
2335 the "no387" option to the kernel
2336 4) pass the "floppy=nodma" option to the kernel
2337 5) pass the "mem=4M" option to the kernel (thereby disabling
2338 all but the first 4 MB of RAM)
2339 6) make sure that the CPU is not over clocked.
2340 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2341 8) disable the cache from your BIOS settings
2342 9) install a fan for the video card or exchange video RAM
2343 10) install a better fan for the CPU
2344 11) exchange RAM chips
2345 12) exchange the motherboard.
2347 To compile this driver as a module, choose M here: the
2348 module will be called apm.
2352 config APM_IGNORE_USER_SUSPEND
2353 bool "Ignore USER SUSPEND"
2355 This option will ignore USER SUSPEND requests. On machines with a
2356 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2357 series notebooks, it is necessary to say Y because of a BIOS bug.
2359 config APM_DO_ENABLE
2360 bool "Enable PM at boot time"
2362 Enable APM features at boot time. From page 36 of the APM BIOS
2363 specification: "When disabled, the APM BIOS does not automatically
2364 power manage devices, enter the Standby State, enter the Suspend
2365 State, or take power saving steps in response to CPU Idle calls."
2366 This driver will make CPU Idle calls when Linux is idle (unless this
2367 feature is turned off -- see "Do CPU IDLE calls", below). This
2368 should always save battery power, but more complicated APM features
2369 will be dependent on your BIOS implementation. You may need to turn
2370 this option off if your computer hangs at boot time when using APM
2371 support, or if it beeps continuously instead of suspending. Turn
2372 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2373 T400CDT. This is off by default since most machines do fine without
2378 bool "Make CPU Idle calls when idle"
2380 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2381 On some machines, this can activate improved power savings, such as
2382 a slowed CPU clock rate, when the machine is idle. These idle calls
2383 are made after the idle loop has run for some length of time (e.g.,
2384 333 mS). On some machines, this will cause a hang at boot time or
2385 whenever the CPU becomes idle. (On machines with more than one CPU,
2386 this option does nothing.)
2388 config APM_DISPLAY_BLANK
2389 bool "Enable console blanking using APM"
2391 Enable console blanking using the APM. Some laptops can use this to
2392 turn off the LCD backlight when the screen blanker of the Linux
2393 virtual console blanks the screen. Note that this is only used by
2394 the virtual console screen blanker, and won't turn off the backlight
2395 when using the X Window system. This also doesn't have anything to
2396 do with your VESA-compliant power-saving monitor. Further, this
2397 option doesn't work for all laptops -- it might not turn off your
2398 backlight at all, or it might print a lot of errors to the console,
2399 especially if you are using gpm.
2401 config APM_ALLOW_INTS
2402 bool "Allow interrupts during APM BIOS calls"
2404 Normally we disable external interrupts while we are making calls to
2405 the APM BIOS as a measure to lessen the effects of a badly behaving
2406 BIOS implementation. The BIOS should reenable interrupts if it
2407 needs to. Unfortunately, some BIOSes do not -- especially those in
2408 many of the newer IBM Thinkpads. If you experience hangs when you
2409 suspend, try setting this to Y. Otherwise, say N.
2413 source "drivers/cpufreq/Kconfig"
2415 source "drivers/cpuidle/Kconfig"
2417 source "drivers/idle/Kconfig"
2422 menu "Bus options (PCI etc.)"
2428 Find out whether you have a PCI motherboard. PCI is the name of a
2429 bus system, i.e. the way the CPU talks to the other stuff inside
2430 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2431 VESA. If you have PCI, say Y, otherwise N.
2434 prompt "PCI access mode"
2435 depends on X86_32 && PCI
2438 On PCI systems, the BIOS can be used to detect the PCI devices and
2439 determine their configuration. However, some old PCI motherboards
2440 have BIOS bugs and may crash if this is done. Also, some embedded
2441 PCI-based systems don't have any BIOS at all. Linux can also try to
2442 detect the PCI hardware directly without using the BIOS.
2444 With this option, you can specify how Linux should detect the
2445 PCI devices. If you choose "BIOS", the BIOS will be used,
2446 if you choose "Direct", the BIOS won't be used, and if you
2447 choose "MMConfig", then PCI Express MMCONFIG will be used.
2448 If you choose "Any", the kernel will try MMCONFIG, then the
2449 direct access method and falls back to the BIOS if that doesn't
2450 work. If unsure, go with the default, which is "Any".
2455 config PCI_GOMMCONFIG
2472 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2474 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2477 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2481 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2485 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2489 depends on PCI && XEN
2497 bool "Support mmconfig PCI config space access"
2498 depends on X86_64 && PCI && ACPI
2500 config PCI_CNB20LE_QUIRK
2501 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2504 Read the PCI windows out of the CNB20LE host bridge. This allows
2505 PCI hotplug to work on systems with the CNB20LE chipset which do
2508 There's no public spec for this chipset, and this functionality
2509 is known to be incomplete.
2511 You should say N unless you know you need this.
2513 source "drivers/pci/Kconfig"
2516 bool "ISA-style bus support on modern systems" if EXPERT
2519 Enables ISA-style drivers on modern systems. This is necessary to
2520 support PC/104 devices on X86_64 platforms.
2524 # x86_64 have no ISA slots, but can have ISA-style DMA.
2526 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2529 Enables ISA-style DMA support for devices requiring such controllers.
2537 Find out whether you have ISA slots on your motherboard. ISA is the
2538 name of a bus system, i.e. the way the CPU talks to the other stuff
2539 inside your box. Other bus systems are PCI, EISA, MicroChannel
2540 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2541 newer boards don't support it. If you have ISA, say Y, otherwise N.
2547 The Extended Industry Standard Architecture (EISA) bus was
2548 developed as an open alternative to the IBM MicroChannel bus.
2550 The EISA bus provided some of the features of the IBM MicroChannel
2551 bus while maintaining backward compatibility with cards made for
2552 the older ISA bus. The EISA bus saw limited use between 1988 and
2553 1995 when it was made obsolete by the PCI bus.
2555 Say Y here if you are building a kernel for an EISA-based machine.
2559 source "drivers/eisa/Kconfig"
2562 tristate "NatSemi SCx200 support"
2564 This provides basic support for National Semiconductor's
2565 (now AMD's) Geode processors. The driver probes for the
2566 PCI-IDs of several on-chip devices, so its a good dependency
2567 for other scx200_* drivers.
2569 If compiled as a module, the driver is named scx200.
2571 config SCx200HR_TIMER
2572 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2576 This driver provides a clocksource built upon the on-chip
2577 27MHz high-resolution timer. Its also a workaround for
2578 NSC Geode SC-1100's buggy TSC, which loses time when the
2579 processor goes idle (as is done by the scheduler). The
2580 other workaround is idle=poll boot option.
2583 bool "One Laptop Per Child support"
2590 Add support for detecting the unique features of the OLPC
2594 bool "OLPC XO-1 Power Management"
2595 depends on OLPC && MFD_CS5535 && PM_SLEEP
2598 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2601 bool "OLPC XO-1 Real Time Clock"
2602 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2604 Add support for the XO-1 real time clock, which can be used as a
2605 programmable wakeup source.
2608 bool "OLPC XO-1 SCI extras"
2609 depends on OLPC && OLPC_XO1_PM
2615 Add support for SCI-based features of the OLPC XO-1 laptop:
2616 - EC-driven system wakeups
2620 - AC adapter status updates
2621 - Battery status updates
2623 config OLPC_XO15_SCI
2624 bool "OLPC XO-1.5 SCI extras"
2625 depends on OLPC && ACPI
2628 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2629 - EC-driven system wakeups
2630 - AC adapter status updates
2631 - Battery status updates
2634 bool "PCEngines ALIX System Support (LED setup)"
2637 This option enables system support for the PCEngines ALIX.
2638 At present this just sets up LEDs for GPIO control on
2639 ALIX2/3/6 boards. However, other system specific setup should
2642 Note: You must still enable the drivers for GPIO and LED support
2643 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2645 Note: You have to set alix.force=1 for boards with Award BIOS.
2648 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2651 This option enables system support for the Soekris Engineering net5501.
2654 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2658 This option enables system support for the Traverse Technologies GEOS.
2661 bool "Technologic Systems TS-5500 platform support"
2663 select CHECK_SIGNATURE
2667 This option enables system support for the Technologic Systems TS-5500.
2673 depends on CPU_SUP_AMD && PCI
2675 source "drivers/pcmcia/Kconfig"
2678 tristate "RapidIO support"
2682 If enabled this option will include drivers and the core
2683 infrastructure code to support RapidIO interconnect devices.
2685 source "drivers/rapidio/Kconfig"
2688 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2690 Firmwares often provide initial graphics framebuffers so the BIOS,
2691 bootloader or kernel can show basic video-output during boot for
2692 user-guidance and debugging. Historically, x86 used the VESA BIOS
2693 Extensions and EFI-framebuffers for this, which are mostly limited
2695 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2696 framebuffers so the new generic system-framebuffer drivers can be
2697 used on x86. If the framebuffer is not compatible with the generic
2698 modes, it is adverticed as fallback platform framebuffer so legacy
2699 drivers like efifb, vesafb and uvesafb can pick it up.
2700 If this option is not selected, all system framebuffers are always
2701 marked as fallback platform framebuffers as usual.
2703 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2704 not be able to pick up generic system framebuffers if this option
2705 is selected. You are highly encouraged to enable simplefb as
2706 replacement if you select this option. simplefb can correctly deal
2707 with generic system framebuffers. But you should still keep vesafb
2708 and others enabled as fallback if a system framebuffer is
2709 incompatible with simplefb.
2716 menu "Executable file formats / Emulations"
2718 source "fs/Kconfig.binfmt"
2720 config IA32_EMULATION
2721 bool "IA32 Emulation"
2723 select ARCH_WANT_OLD_COMPAT_IPC
2725 select COMPAT_BINFMT_ELF
2726 select COMPAT_OLD_SIGACTION
2728 Include code to run legacy 32-bit programs under a
2729 64-bit kernel. You should likely turn this on, unless you're
2730 100% sure that you don't have any 32-bit programs left.
2733 tristate "IA32 a.out support"
2734 depends on IA32_EMULATION
2736 Support old a.out binaries in the 32bit emulation.
2739 bool "x32 ABI for 64-bit mode"
2742 Include code to run binaries for the x32 native 32-bit ABI
2743 for 64-bit processors. An x32 process gets access to the
2744 full 64-bit register file and wide data path while leaving
2745 pointers at 32 bits for smaller memory footprint.
2747 You will need a recent binutils (2.22 or later) with
2748 elf32_x86_64 support enabled to compile a kernel with this
2753 depends on IA32_EMULATION || X86_32
2755 select OLD_SIGSUSPEND3
2759 depends on IA32_EMULATION || X86_X32
2762 config COMPAT_FOR_U64_ALIGNMENT
2765 config SYSVIPC_COMPAT
2777 config HAVE_ATOMIC_IOMAP
2781 config X86_DEV_DMA_OPS
2783 depends on X86_64 || STA2X11
2785 config X86_DMA_REMAP
2793 source "net/Kconfig"
2795 source "drivers/Kconfig"
2797 source "drivers/firmware/Kconfig"
2801 source "arch/x86/Kconfig.debug"
2803 source "security/Kconfig"
2805 source "crypto/Kconfig"
2807 source "arch/x86/kvm/Kconfig"
2809 source "lib/Kconfig"