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_COMPAT_MMAP_BASES if MMU && COMPAT
110 select HAVE_ARCH_SECCOMP_FILTER
111 select HAVE_ARCH_TRACEHOOK
112 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
113 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
114 select HAVE_ARCH_VMAP_STACK if X86_64
115 select HAVE_ARCH_WITHIN_STACK_FRAMES
116 select HAVE_CC_STACKPROTECTOR
117 select HAVE_CMPXCHG_DOUBLE
118 select HAVE_CMPXCHG_LOCAL
119 select HAVE_CONTEXT_TRACKING if X86_64
120 select HAVE_COPY_THREAD_TLS
121 select HAVE_C_RECORDMCOUNT
122 select HAVE_DEBUG_KMEMLEAK
123 select HAVE_DEBUG_STACKOVERFLOW
124 select HAVE_DMA_API_DEBUG
125 select HAVE_DMA_CONTIGUOUS
126 select HAVE_DYNAMIC_FTRACE
127 select HAVE_DYNAMIC_FTRACE_WITH_REGS
128 select HAVE_EBPF_JIT if X86_64
129 select HAVE_EFFICIENT_UNALIGNED_ACCESS
130 select HAVE_EXIT_THREAD
131 select HAVE_FENTRY if X86_64
132 select HAVE_FTRACE_MCOUNT_RECORD
133 select HAVE_FUNCTION_GRAPH_TRACER
134 select HAVE_FUNCTION_TRACER
135 select HAVE_GCC_PLUGINS
136 select HAVE_HW_BREAKPOINT
138 select HAVE_IOREMAP_PROT
139 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
140 select HAVE_IRQ_TIME_ACCOUNTING
141 select HAVE_KERNEL_BZIP2
142 select HAVE_KERNEL_GZIP
143 select HAVE_KERNEL_LZ4
144 select HAVE_KERNEL_LZMA
145 select HAVE_KERNEL_LZO
146 select HAVE_KERNEL_XZ
148 select HAVE_KPROBES_ON_FTRACE
149 select HAVE_KRETPROBES
151 select HAVE_LIVEPATCH if X86_64
153 select HAVE_MEMBLOCK_NODE_MAP
154 select HAVE_MIXED_BREAKPOINTS_REGS
157 select HAVE_OPTPROBES
158 select HAVE_PCSPKR_PLATFORM
159 select HAVE_PERF_EVENTS
160 select HAVE_PERF_EVENTS_NMI
161 select HAVE_PERF_REGS
162 select HAVE_PERF_USER_STACK_DUMP
163 select HAVE_REGS_AND_STACK_ACCESS_API
164 select HAVE_STACK_VALIDATION if X86_64
165 select HAVE_SYSCALL_TRACEPOINTS
166 select HAVE_UNSTABLE_SCHED_CLOCK
167 select HAVE_USER_RETURN_NOTIFIER
168 select IRQ_FORCED_THREADING
171 select RTC_MC146818_LIB
174 select SYSCTL_EXCEPTION_TRACE
175 select THREAD_INFO_IN_TASK
176 select USER_STACKTRACE_SUPPORT
178 select X86_FEATURE_NAMES if PROC_FS
180 config INSTRUCTION_DECODER
182 depends on KPROBES || PERF_EVENTS || UPROBES
186 default "elf32-i386" if X86_32
187 default "elf64-x86-64" if X86_64
189 config ARCH_DEFCONFIG
191 default "arch/x86/configs/i386_defconfig" if X86_32
192 default "arch/x86/configs/x86_64_defconfig" if X86_64
194 config LOCKDEP_SUPPORT
197 config STACKTRACE_SUPPORT
203 config ARCH_MMAP_RND_BITS_MIN
207 config ARCH_MMAP_RND_BITS_MAX
211 config ARCH_MMAP_RND_COMPAT_BITS_MIN
214 config ARCH_MMAP_RND_COMPAT_BITS_MAX
220 config NEED_DMA_MAP_STATE
222 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
224 config NEED_SG_DMA_LENGTH
227 config GENERIC_ISA_DMA
229 depends on ISA_DMA_API
234 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
236 config GENERIC_BUG_RELATIVE_POINTERS
239 config GENERIC_HWEIGHT
242 config ARCH_MAY_HAVE_PC_FDC
244 depends on ISA_DMA_API
246 config RWSEM_XCHGADD_ALGORITHM
249 config GENERIC_CALIBRATE_DELAY
252 config ARCH_HAS_CPU_RELAX
255 config ARCH_HAS_CACHE_LINE_SIZE
258 config HAVE_SETUP_PER_CPU_AREA
261 config NEED_PER_CPU_EMBED_FIRST_CHUNK
264 config NEED_PER_CPU_PAGE_FIRST_CHUNK
267 config ARCH_HIBERNATION_POSSIBLE
270 config ARCH_SUSPEND_POSSIBLE
273 config ARCH_WANT_HUGE_PMD_SHARE
276 config ARCH_WANT_GENERAL_HUGETLB
285 config ARCH_SUPPORTS_OPTIMIZED_INLINING
288 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
291 config KASAN_SHADOW_OFFSET
294 default 0xdff8000000000000 if X86_5LEVEL
295 default 0xdffffc0000000000
297 config HAVE_INTEL_TXT
299 depends on INTEL_IOMMU && ACPI
303 depends on X86_32 && SMP
307 depends on X86_64 && SMP
309 config X86_32_LAZY_GS
311 depends on X86_32 && !CC_STACKPROTECTOR
313 config ARCH_SUPPORTS_UPROBES
316 config FIX_EARLYCON_MEM
319 config PGTABLE_LEVELS
325 source "init/Kconfig"
326 source "kernel/Kconfig.freezer"
328 menu "Processor type and features"
331 bool "DMA memory allocation support" if EXPERT
334 DMA memory allocation support allows devices with less than 32-bit
335 addressing to allocate within the first 16MB of address space.
336 Disable if no such devices will be used.
341 bool "Symmetric multi-processing support"
343 This enables support for systems with more than one CPU. If you have
344 a system with only one CPU, say N. If you have a system with more
347 If you say N here, the kernel will run on uni- and multiprocessor
348 machines, but will use only one CPU of a multiprocessor machine. If
349 you say Y here, the kernel will run on many, but not all,
350 uniprocessor machines. On a uniprocessor machine, the kernel
351 will run faster if you say N here.
353 Note that if you say Y here and choose architecture "586" or
354 "Pentium" under "Processor family", the kernel will not work on 486
355 architectures. Similarly, multiprocessor kernels for the "PPro"
356 architecture may not work on all Pentium based boards.
358 People using multiprocessor machines who say Y here should also say
359 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
360 Management" code will be disabled if you say Y here.
362 See also <file:Documentation/x86/i386/IO-APIC.txt>,
363 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
364 <http://www.tldp.org/docs.html#howto>.
366 If you don't know what to do here, say N.
368 config X86_FEATURE_NAMES
369 bool "Processor feature human-readable names" if EMBEDDED
372 This option compiles in a table of x86 feature bits and corresponding
373 names. This is required to support /proc/cpuinfo and a few kernel
374 messages. You can disable this to save space, at the expense of
375 making those few kernel messages show numeric feature bits instead.
379 config X86_FAST_FEATURE_TESTS
380 bool "Fast CPU feature tests" if EMBEDDED
383 Some fast-paths in the kernel depend on the capabilities of the CPU.
384 Say Y here for the kernel to patch in the appropriate code at runtime
385 based on the capabilities of the CPU. The infrastructure for patching
386 code at runtime takes up some additional space; space-constrained
387 embedded systems may wish to say N here to produce smaller, slightly
391 bool "Support x2apic"
392 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
394 This enables x2apic support on CPUs that have this feature.
396 This allows 32-bit apic IDs (so it can support very large systems),
397 and accesses the local apic via MSRs not via mmio.
399 If you don't know what to do here, say N.
402 bool "Enable MPS table" if ACPI || SFI
404 depends on X86_LOCAL_APIC
406 For old smp systems that do not have proper acpi support. Newer systems
407 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
410 bool "Support for big SMP systems with more than 8 CPUs"
411 depends on X86_32 && SMP
413 This option is needed for the systems that have more than 8 CPUs
417 depends on X86_GOLDFISH
420 bool "Intel Resource Director Technology Allocation support"
422 depends on X86 && CPU_SUP_INTEL
425 Select to enable resource allocation which is a sub-feature of
426 Intel Resource Director Technology(RDT). More information about
427 RDT can be found in the Intel x86 Architecture Software
433 config X86_EXTENDED_PLATFORM
434 bool "Support for extended (non-PC) x86 platforms"
437 If you disable this option then the kernel will only support
438 standard PC platforms. (which covers the vast majority of
441 If you enable this option then you'll be able to select support
442 for the following (non-PC) 32 bit x86 platforms:
443 Goldfish (Android emulator)
446 SGI 320/540 (Visual Workstation)
447 STA2X11-based (e.g. Northville)
448 Moorestown MID devices
450 If you have one of these systems, or if you want to build a
451 generic distribution kernel, say Y here - otherwise say N.
455 config X86_EXTENDED_PLATFORM
456 bool "Support for extended (non-PC) x86 platforms"
459 If you disable this option then the kernel will only support
460 standard PC platforms. (which covers the vast majority of
463 If you enable this option then you'll be able to select support
464 for the following (non-PC) 64 bit x86 platforms:
469 If you have one of these systems, or if you want to build a
470 generic distribution kernel, say Y here - otherwise say N.
472 # This is an alphabetically sorted list of 64 bit extended platforms
473 # Please maintain the alphabetic order if and when there are additions
475 bool "Numascale NumaChip"
477 depends on X86_EXTENDED_PLATFORM
480 depends on X86_X2APIC
481 depends on PCI_MMCONFIG
483 Adds support for Numascale NumaChip large-SMP systems. Needed to
484 enable more than ~168 cores.
485 If you don't have one of these, you should say N here.
489 select HYPERVISOR_GUEST
491 depends on X86_64 && PCI
492 depends on X86_EXTENDED_PLATFORM
495 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
496 supposed to run on these EM64T-based machines. Only choose this option
497 if you have one of these machines.
500 bool "SGI Ultraviolet"
502 depends on X86_EXTENDED_PLATFORM
505 depends on X86_X2APIC
508 This option is needed in order to support SGI Ultraviolet systems.
509 If you don't have one of these, you should say N here.
511 # Following is an alphabetically sorted list of 32 bit extended platforms
512 # Please maintain the alphabetic order if and when there are additions
515 bool "Goldfish (Virtual Platform)"
516 depends on X86_EXTENDED_PLATFORM
518 Enable support for the Goldfish virtual platform used primarily
519 for Android development. Unless you are building for the Android
520 Goldfish emulator say N here.
523 bool "CE4100 TV platform"
525 depends on PCI_GODIRECT
526 depends on X86_IO_APIC
528 depends on X86_EXTENDED_PLATFORM
529 select X86_REBOOTFIXUPS
531 select OF_EARLY_FLATTREE
533 Select for the Intel CE media processor (CE4100) SOC.
534 This option compiles in support for the CE4100 SOC for settop
535 boxes and media devices.
538 bool "Intel MID platform support"
539 depends on X86_EXTENDED_PLATFORM
540 depends on X86_PLATFORM_DEVICES
542 depends on X86_64 || (PCI_GOANY && X86_32)
543 depends on X86_IO_APIC
549 select MFD_INTEL_MSIC
551 Select to build a kernel capable of supporting Intel MID (Mobile
552 Internet Device) platform systems which do not have the PCI legacy
553 interfaces. If you are building for a PC class system say N here.
555 Intel MID platforms are based on an Intel processor and chipset which
556 consume less power than most of the x86 derivatives.
558 config X86_INTEL_QUARK
559 bool "Intel Quark platform support"
561 depends on X86_EXTENDED_PLATFORM
562 depends on X86_PLATFORM_DEVICES
566 depends on X86_IO_APIC
571 Select to include support for Quark X1000 SoC.
572 Say Y here if you have a Quark based system such as the Arduino
573 compatible Intel Galileo.
575 config X86_INTEL_LPSS
576 bool "Intel Low Power Subsystem Support"
577 depends on X86 && ACPI
582 Select to build support for Intel Low Power Subsystem such as
583 found on Intel Lynxpoint PCH. Selecting this option enables
584 things like clock tree (common clock framework) and pincontrol
585 which are needed by the LPSS peripheral drivers.
587 config X86_AMD_PLATFORM_DEVICE
588 bool "AMD ACPI2Platform devices support"
593 Select to interpret AMD specific ACPI device to platform device
594 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
595 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
596 implemented under PINCTRL subsystem.
599 tristate "Intel SoC IOSF Sideband support for SoC platforms"
602 This option enables sideband register access support for Intel SoC
603 platforms. On these platforms the IOSF sideband is used in lieu of
604 MSR's for some register accesses, mostly but not limited to thermal
605 and power. Drivers may query the availability of this device to
606 determine if they need the sideband in order to work on these
607 platforms. The sideband is available on the following SoC products.
608 This list is not meant to be exclusive.
613 You should say Y if you are running a kernel on one of these SoC's.
615 config IOSF_MBI_DEBUG
616 bool "Enable IOSF sideband access through debugfs"
617 depends on IOSF_MBI && DEBUG_FS
619 Select this option to expose the IOSF sideband access registers (MCR,
620 MDR, MCRX) through debugfs to write and read register information from
621 different units on the SoC. This is most useful for obtaining device
622 state information for debug and analysis. As this is a general access
623 mechanism, users of this option would have specific knowledge of the
624 device they want to access.
626 If you don't require the option or are in doubt, say N.
629 bool "RDC R-321x SoC"
631 depends on X86_EXTENDED_PLATFORM
633 select X86_REBOOTFIXUPS
635 This option is needed for RDC R-321x system-on-chip, also known
637 If you don't have one of these chips, you should say N here.
639 config X86_32_NON_STANDARD
640 bool "Support non-standard 32-bit SMP architectures"
641 depends on X86_32 && SMP
642 depends on X86_EXTENDED_PLATFORM
644 This option compiles in the bigsmp and STA2X11 default
645 subarchitectures. It is intended for a generic binary
646 kernel. If you select them all, kernel will probe it one by
647 one and will fallback to default.
649 # Alphabetically sorted list of Non standard 32 bit platforms
651 config X86_SUPPORTS_MEMORY_FAILURE
653 # MCE code calls memory_failure():
655 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
656 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
657 depends on X86_64 || !SPARSEMEM
658 select ARCH_SUPPORTS_MEMORY_FAILURE
661 bool "STA2X11 Companion Chip Support"
662 depends on X86_32_NON_STANDARD && PCI
663 select X86_DEV_DMA_OPS
670 This adds support for boards based on the STA2X11 IO-Hub,
671 a.k.a. "ConneXt". The chip is used in place of the standard
672 PC chipset, so all "standard" peripherals are missing. If this
673 option is selected the kernel will still be able to boot on
674 standard PC machines.
677 tristate "Eurobraille/Iris poweroff module"
680 The Iris machines from EuroBraille do not have APM or ACPI support
681 to shut themselves down properly. A special I/O sequence is
682 needed to do so, which is what this module does at
685 This is only for Iris machines from EuroBraille.
689 config SCHED_OMIT_FRAME_POINTER
691 prompt "Single-depth WCHAN output"
694 Calculate simpler /proc/<PID>/wchan values. If this option
695 is disabled then wchan values will recurse back to the
696 caller function. This provides more accurate wchan values,
697 at the expense of slightly more scheduling overhead.
699 If in doubt, say "Y".
701 menuconfig HYPERVISOR_GUEST
702 bool "Linux guest support"
704 Say Y here to enable options for running Linux under various hyper-
705 visors. This option enables basic hypervisor detection and platform
708 If you say N, all options in this submenu will be skipped and
709 disabled, and Linux guest support won't be built in.
714 bool "Enable paravirtualization code"
716 This changes the kernel so it can modify itself when it is run
717 under a hypervisor, potentially improving performance significantly
718 over full virtualization. However, when run without a hypervisor
719 the kernel is theoretically slower and slightly larger.
721 config PARAVIRT_DEBUG
722 bool "paravirt-ops debugging"
723 depends on PARAVIRT && DEBUG_KERNEL
725 Enable to debug paravirt_ops internals. Specifically, BUG if
726 a paravirt_op is missing when it is called.
728 config PARAVIRT_SPINLOCKS
729 bool "Paravirtualization layer for spinlocks"
730 depends on PARAVIRT && SMP
732 Paravirtualized spinlocks allow a pvops backend to replace the
733 spinlock implementation with something virtualization-friendly
734 (for example, block the virtual CPU rather than spinning).
736 It has a minimal impact on native kernels and gives a nice performance
737 benefit on paravirtualized KVM / Xen kernels.
739 If you are unsure how to answer this question, answer Y.
741 config QUEUED_LOCK_STAT
742 bool "Paravirt queued spinlock statistics"
743 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
745 Enable the collection of statistical data on the slowpath
746 behavior of paravirtualized queued spinlocks and report
749 source "arch/x86/xen/Kconfig"
752 bool "KVM Guest support (including kvmclock)"
754 select PARAVIRT_CLOCK
757 This option enables various optimizations for running under the KVM
758 hypervisor. It includes a paravirtualized clock, so that instead
759 of relying on a PIT (or probably other) emulation by the
760 underlying device model, the host provides the guest with
761 timing infrastructure such as time of day, and system time
764 bool "Enable debug information for KVM Guests in debugfs"
765 depends on KVM_GUEST && DEBUG_FS
768 This option enables collection of various statistics for KVM guest.
769 Statistics are displayed in debugfs filesystem. Enabling this option
770 may incur significant overhead.
772 source "arch/x86/lguest/Kconfig"
774 config PARAVIRT_TIME_ACCOUNTING
775 bool "Paravirtual steal time accounting"
779 Select this option to enable fine granularity task steal time
780 accounting. Time spent executing other tasks in parallel with
781 the current vCPU is discounted from the vCPU power. To account for
782 that, there can be a small performance impact.
784 If in doubt, say N here.
786 config PARAVIRT_CLOCK
789 endif #HYPERVISOR_GUEST
794 source "arch/x86/Kconfig.cpu"
798 prompt "HPET Timer Support" if X86_32
800 Use the IA-PC HPET (High Precision Event Timer) to manage
801 time in preference to the PIT and RTC, if a HPET is
803 HPET is the next generation timer replacing legacy 8254s.
804 The HPET provides a stable time base on SMP
805 systems, unlike the TSC, but it is more expensive to access,
806 as it is off-chip. The interface used is documented
807 in the HPET spec, revision 1.
809 You can safely choose Y here. However, HPET will only be
810 activated if the platform and the BIOS support this feature.
811 Otherwise the 8254 will be used for timing services.
813 Choose N to continue using the legacy 8254 timer.
815 config HPET_EMULATE_RTC
817 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
820 def_bool y if X86_INTEL_MID
821 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
823 depends on X86_INTEL_MID && SFI
825 APB timer is the replacement for 8254, HPET on X86 MID platforms.
826 The APBT provides a stable time base on SMP
827 systems, unlike the TSC, but it is more expensive to access,
828 as it is off-chip. APB timers are always running regardless of CPU
829 C states, they are used as per CPU clockevent device when possible.
831 # Mark as expert because too many people got it wrong.
832 # The code disables itself when not needed.
835 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
836 bool "Enable DMI scanning" if EXPERT
838 Enabled scanning of DMI to identify machine quirks. Say Y
839 here unless you have verified that your setup is not
840 affected by entries in the DMI blacklist. Required by PNP
844 bool "Old AMD GART IOMMU support"
846 depends on X86_64 && PCI && AMD_NB
848 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
849 GART based hardware IOMMUs.
851 The GART supports full DMA access for devices with 32-bit access
852 limitations, on systems with more than 3 GB. This is usually needed
853 for USB, sound, many IDE/SATA chipsets and some other devices.
855 Newer systems typically have a modern AMD IOMMU, supported via
856 the CONFIG_AMD_IOMMU=y config option.
858 In normal configurations this driver is only active when needed:
859 there's more than 3 GB of memory and the system contains a
860 32-bit limited device.
865 bool "IBM Calgary IOMMU support"
867 depends on X86_64 && PCI
869 Support for hardware IOMMUs in IBM's xSeries x366 and x460
870 systems. Needed to run systems with more than 3GB of memory
871 properly with 32-bit PCI devices that do not support DAC
872 (Double Address Cycle). Calgary also supports bus level
873 isolation, where all DMAs pass through the IOMMU. This
874 prevents them from going anywhere except their intended
875 destination. This catches hard-to-find kernel bugs and
876 mis-behaving drivers and devices that do not use the DMA-API
877 properly to set up their DMA buffers. The IOMMU can be
878 turned off at boot time with the iommu=off parameter.
879 Normally the kernel will make the right choice by itself.
882 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
884 prompt "Should Calgary be enabled by default?"
885 depends on CALGARY_IOMMU
887 Should Calgary be enabled by default? if you choose 'y', Calgary
888 will be used (if it exists). If you choose 'n', Calgary will not be
889 used even if it exists. If you choose 'n' and would like to use
890 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
893 # need this always selected by IOMMU for the VIA workaround
897 Support for software bounce buffers used on x86-64 systems
898 which don't have a hardware IOMMU. Using this PCI devices
899 which can only access 32-bits of memory can be used on systems
900 with more than 3 GB of memory.
905 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
908 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
909 depends on X86_64 && SMP && DEBUG_KERNEL
910 select CPUMASK_OFFSTACK
912 Enable maximum number of CPUS and NUMA Nodes for this architecture.
916 int "Maximum number of CPUs" if SMP && !MAXSMP
917 range 2 8 if SMP && X86_32 && !X86_BIGSMP
918 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
919 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
921 default "8192" if MAXSMP
922 default "32" if SMP && X86_BIGSMP
923 default "8" if SMP && X86_32
926 This allows you to specify the maximum number of CPUs which this
927 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
928 supported value is 8192, otherwise the maximum value is 512. The
929 minimum value which makes sense is 2.
931 This is purely to save memory - each supported CPU adds
932 approximately eight kilobytes to the kernel image.
935 bool "SMT (Hyperthreading) scheduler support"
938 SMT scheduler support improves the CPU scheduler's decision making
939 when dealing with Intel Pentium 4 chips with HyperThreading at a
940 cost of slightly increased overhead in some places. If unsure say
945 prompt "Multi-core scheduler support"
948 Multi-core scheduler support improves the CPU scheduler's decision
949 making when dealing with multi-core CPU chips at a cost of slightly
950 increased overhead in some places. If unsure say N here.
953 bool "CPU core priorities scheduler support"
954 depends on SCHED_MC && CPU_SUP_INTEL
955 select X86_INTEL_PSTATE
959 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
960 core ordering determined at manufacturing time, which allows
961 certain cores to reach higher turbo frequencies (when running
962 single threaded workloads) than others.
964 Enabling this kernel feature teaches the scheduler about
965 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
966 scheduler's CPU selection logic accordingly, so that higher
967 overall system performance can be achieved.
969 This feature will have no effect on CPUs without this feature.
971 If unsure say Y here.
973 source "kernel/Kconfig.preempt"
977 depends on !SMP && X86_LOCAL_APIC
980 bool "Local APIC support on uniprocessors" if !PCI_MSI
982 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
984 A local APIC (Advanced Programmable Interrupt Controller) is an
985 integrated interrupt controller in the CPU. If you have a single-CPU
986 system which has a processor with a local APIC, you can say Y here to
987 enable and use it. If you say Y here even though your machine doesn't
988 have a local APIC, then the kernel will still run with no slowdown at
989 all. The local APIC supports CPU-generated self-interrupts (timer,
990 performance counters), and the NMI watchdog which detects hard
994 bool "IO-APIC support on uniprocessors"
995 depends on X86_UP_APIC
997 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
998 SMP-capable replacement for PC-style interrupt controllers. Most
999 SMP systems and many recent uniprocessor systems have one.
1001 If you have a single-CPU system with an IO-APIC, you can say Y here
1002 to use it. If you say Y here even though your machine doesn't have
1003 an IO-APIC, then the kernel will still run with no slowdown at all.
1005 config X86_LOCAL_APIC
1007 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1008 select IRQ_DOMAIN_HIERARCHY
1009 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1013 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1015 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1016 bool "Reroute for broken boot IRQs"
1017 depends on X86_IO_APIC
1019 This option enables a workaround that fixes a source of
1020 spurious interrupts. This is recommended when threaded
1021 interrupt handling is used on systems where the generation of
1022 superfluous "boot interrupts" cannot be disabled.
1024 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1025 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1026 kernel does during interrupt handling). On chipsets where this
1027 boot IRQ generation cannot be disabled, this workaround keeps
1028 the original IRQ line masked so that only the equivalent "boot
1029 IRQ" is delivered to the CPUs. The workaround also tells the
1030 kernel to set up the IRQ handler on the boot IRQ line. In this
1031 way only one interrupt is delivered to the kernel. Otherwise
1032 the spurious second interrupt may cause the kernel to bring
1033 down (vital) interrupt lines.
1035 Only affects "broken" chipsets. Interrupt sharing may be
1036 increased on these systems.
1039 bool "Machine Check / overheating reporting"
1040 select GENERIC_ALLOCATOR
1043 Machine Check support allows the processor to notify the
1044 kernel if it detects a problem (e.g. overheating, data corruption).
1045 The action the kernel takes depends on the severity of the problem,
1046 ranging from warning messages to halting the machine.
1048 config X86_MCE_INTEL
1050 prompt "Intel MCE features"
1051 depends on X86_MCE && X86_LOCAL_APIC
1053 Additional support for intel specific MCE features such as
1054 the thermal monitor.
1058 prompt "AMD MCE features"
1059 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1061 Additional support for AMD specific MCE features such as
1062 the DRAM Error Threshold.
1064 config X86_ANCIENT_MCE
1065 bool "Support for old Pentium 5 / WinChip machine checks"
1066 depends on X86_32 && X86_MCE
1068 Include support for machine check handling on old Pentium 5 or WinChip
1069 systems. These typically need to be enabled explicitly on the command
1072 config X86_MCE_THRESHOLD
1073 depends on X86_MCE_AMD || X86_MCE_INTEL
1076 config X86_MCE_INJECT
1077 depends on X86_MCE && X86_LOCAL_APIC
1078 tristate "Machine check injector support"
1080 Provide support for injecting machine checks for testing purposes.
1081 If you don't know what a machine check is and you don't do kernel
1082 QA it is safe to say n.
1084 config X86_THERMAL_VECTOR
1086 depends on X86_MCE_INTEL
1088 source "arch/x86/events/Kconfig"
1090 config X86_LEGACY_VM86
1091 bool "Legacy VM86 support"
1095 This option allows user programs to put the CPU into V8086
1096 mode, which is an 80286-era approximation of 16-bit real mode.
1098 Some very old versions of X and/or vbetool require this option
1099 for user mode setting. Similarly, DOSEMU will use it if
1100 available to accelerate real mode DOS programs. However, any
1101 recent version of DOSEMU, X, or vbetool should be fully
1102 functional even without kernel VM86 support, as they will all
1103 fall back to software emulation. Nevertheless, if you are using
1104 a 16-bit DOS program where 16-bit performance matters, vm86
1105 mode might be faster than emulation and you might want to
1108 Note that any app that works on a 64-bit kernel is unlikely to
1109 need this option, as 64-bit kernels don't, and can't, support
1110 V8086 mode. This option is also unrelated to 16-bit protected
1111 mode and is not needed to run most 16-bit programs under Wine.
1113 Enabling this option increases the complexity of the kernel
1114 and slows down exception handling a tiny bit.
1116 If unsure, say N here.
1120 default X86_LEGACY_VM86
1123 bool "Enable support for 16-bit segments" if EXPERT
1125 depends on MODIFY_LDT_SYSCALL
1127 This option is required by programs like Wine to run 16-bit
1128 protected mode legacy code on x86 processors. Disabling
1129 this option saves about 300 bytes on i386, or around 6K text
1130 plus 16K runtime memory on x86-64,
1134 depends on X86_16BIT && X86_32
1138 depends on X86_16BIT && X86_64
1140 config X86_VSYSCALL_EMULATION
1141 bool "Enable vsyscall emulation" if EXPERT
1145 This enables emulation of the legacy vsyscall page. Disabling
1146 it is roughly equivalent to booting with vsyscall=none, except
1147 that it will also disable the helpful warning if a program
1148 tries to use a vsyscall. With this option set to N, offending
1149 programs will just segfault, citing addresses of the form
1152 This option is required by many programs built before 2013, and
1153 care should be used even with newer programs if set to N.
1155 Disabling this option saves about 7K of kernel size and
1156 possibly 4K of additional runtime pagetable memory.
1159 tristate "Toshiba Laptop support"
1162 This adds a driver to safely access the System Management Mode of
1163 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1164 not work on models with a Phoenix BIOS. The System Management Mode
1165 is used to set the BIOS and power saving options on Toshiba portables.
1167 For information on utilities to make use of this driver see the
1168 Toshiba Linux utilities web site at:
1169 <http://www.buzzard.org.uk/toshiba/>.
1171 Say Y if you intend to run this kernel on a Toshiba portable.
1175 tristate "Dell i8k legacy laptop support"
1177 select SENSORS_DELL_SMM
1179 This option enables legacy /proc/i8k userspace interface in hwmon
1180 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1181 temperature and allows controlling fan speeds of Dell laptops via
1182 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1183 it reports also power and hotkey status. For fan speed control is
1184 needed userspace package i8kutils.
1186 Say Y if you intend to run this kernel on old Dell laptops or want to
1187 use userspace package i8kutils.
1190 config X86_REBOOTFIXUPS
1191 bool "Enable X86 board specific fixups for reboot"
1194 This enables chipset and/or board specific fixups to be done
1195 in order to get reboot to work correctly. This is only needed on
1196 some combinations of hardware and BIOS. The symptom, for which
1197 this config is intended, is when reboot ends with a stalled/hung
1200 Currently, the only fixup is for the Geode machines using
1201 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1203 Say Y if you want to enable the fixup. Currently, it's safe to
1204 enable this option even if you don't need it.
1208 bool "CPU microcode loading support"
1210 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1213 If you say Y here, you will be able to update the microcode on
1214 Intel and AMD processors. The Intel support is for the IA32 family,
1215 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1216 AMD support is for families 0x10 and later. You will obviously need
1217 the actual microcode binary data itself which is not shipped with
1220 The preferred method to load microcode from a detached initrd is described
1221 in Documentation/x86/early-microcode.txt. For that you need to enable
1222 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1223 initrd for microcode blobs.
1225 In addition, you can build-in the microcode into the kernel. For that you
1226 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1227 to the CONFIG_EXTRA_FIRMWARE config option.
1229 config MICROCODE_INTEL
1230 bool "Intel microcode loading support"
1231 depends on MICROCODE
1235 This options enables microcode patch loading support for Intel
1238 For the current Intel microcode data package go to
1239 <https://downloadcenter.intel.com> and search for
1240 'Linux Processor Microcode Data File'.
1242 config MICROCODE_AMD
1243 bool "AMD microcode loading support"
1244 depends on MICROCODE
1247 If you select this option, microcode patch loading support for AMD
1248 processors will be enabled.
1250 config MICROCODE_OLD_INTERFACE
1252 depends on MICROCODE
1255 tristate "/dev/cpu/*/msr - Model-specific register support"
1257 This device gives privileged processes access to the x86
1258 Model-Specific Registers (MSRs). It is a character device with
1259 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1260 MSR accesses are directed to a specific CPU on multi-processor
1264 tristate "/dev/cpu/*/cpuid - CPU information support"
1266 This device gives processes access to the x86 CPUID instruction to
1267 be executed on a specific processor. It is a character device
1268 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1272 prompt "High Memory Support"
1279 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1280 However, the address space of 32-bit x86 processors is only 4
1281 Gigabytes large. That means that, if you have a large amount of
1282 physical memory, not all of it can be "permanently mapped" by the
1283 kernel. The physical memory that's not permanently mapped is called
1286 If you are compiling a kernel which will never run on a machine with
1287 more than 1 Gigabyte total physical RAM, answer "off" here (default
1288 choice and suitable for most users). This will result in a "3GB/1GB"
1289 split: 3GB are mapped so that each process sees a 3GB virtual memory
1290 space and the remaining part of the 4GB virtual memory space is used
1291 by the kernel to permanently map as much physical memory as
1294 If the machine has between 1 and 4 Gigabytes physical RAM, then
1297 If more than 4 Gigabytes is used then answer "64GB" here. This
1298 selection turns Intel PAE (Physical Address Extension) mode on.
1299 PAE implements 3-level paging on IA32 processors. PAE is fully
1300 supported by Linux, PAE mode is implemented on all recent Intel
1301 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1302 then the kernel will not boot on CPUs that don't support PAE!
1304 The actual amount of total physical memory will either be
1305 auto detected or can be forced by using a kernel command line option
1306 such as "mem=256M". (Try "man bootparam" or see the documentation of
1307 your boot loader (lilo or loadlin) about how to pass options to the
1308 kernel at boot time.)
1310 If unsure, say "off".
1315 Select this if you have a 32-bit processor and between 1 and 4
1316 gigabytes of physical RAM.
1323 Select this if you have a 32-bit processor and more than 4
1324 gigabytes of physical RAM.
1329 prompt "Memory split" if EXPERT
1333 Select the desired split between kernel and user memory.
1335 If the address range available to the kernel is less than the
1336 physical memory installed, the remaining memory will be available
1337 as "high memory". Accessing high memory is a little more costly
1338 than low memory, as it needs to be mapped into the kernel first.
1339 Note that increasing the kernel address space limits the range
1340 available to user programs, making the address space there
1341 tighter. Selecting anything other than the default 3G/1G split
1342 will also likely make your kernel incompatible with binary-only
1345 If you are not absolutely sure what you are doing, leave this
1349 bool "3G/1G user/kernel split"
1350 config VMSPLIT_3G_OPT
1352 bool "3G/1G user/kernel split (for full 1G low memory)"
1354 bool "2G/2G user/kernel split"
1355 config VMSPLIT_2G_OPT
1357 bool "2G/2G user/kernel split (for full 2G low memory)"
1359 bool "1G/3G user/kernel split"
1364 default 0xB0000000 if VMSPLIT_3G_OPT
1365 default 0x80000000 if VMSPLIT_2G
1366 default 0x78000000 if VMSPLIT_2G_OPT
1367 default 0x40000000 if VMSPLIT_1G
1373 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1376 bool "PAE (Physical Address Extension) Support"
1377 depends on X86_32 && !HIGHMEM4G
1380 PAE is required for NX support, and furthermore enables
1381 larger swapspace support for non-overcommit purposes. It
1382 has the cost of more pagetable lookup overhead, and also
1383 consumes more pagetable space per process.
1385 config ARCH_PHYS_ADDR_T_64BIT
1387 depends on X86_64 || X86_PAE
1389 config ARCH_DMA_ADDR_T_64BIT
1391 depends on X86_64 || HIGHMEM64G
1393 config X86_DIRECT_GBPAGES
1395 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1397 Certain kernel features effectively disable kernel
1398 linear 1 GB mappings (even if the CPU otherwise
1399 supports them), so don't confuse the user by printing
1400 that we have them enabled.
1402 # Common NUMA Features
1404 bool "Numa Memory Allocation and Scheduler Support"
1406 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1407 default y if X86_BIGSMP
1409 Enable NUMA (Non Uniform Memory Access) support.
1411 The kernel will try to allocate memory used by a CPU on the
1412 local memory controller of the CPU and add some more
1413 NUMA awareness to the kernel.
1415 For 64-bit this is recommended if the system is Intel Core i7
1416 (or later), AMD Opteron, or EM64T NUMA.
1418 For 32-bit this is only needed if you boot a 32-bit
1419 kernel on a 64-bit NUMA platform.
1421 Otherwise, you should say N.
1425 prompt "Old style AMD Opteron NUMA detection"
1426 depends on X86_64 && NUMA && PCI
1428 Enable AMD NUMA node topology detection. You should say Y here if
1429 you have a multi processor AMD system. This uses an old method to
1430 read the NUMA configuration directly from the builtin Northbridge
1431 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1432 which also takes priority if both are compiled in.
1434 config X86_64_ACPI_NUMA
1436 prompt "ACPI NUMA detection"
1437 depends on X86_64 && NUMA && ACPI && PCI
1440 Enable ACPI SRAT based node topology detection.
1442 # Some NUMA nodes have memory ranges that span
1443 # other nodes. Even though a pfn is valid and
1444 # between a node's start and end pfns, it may not
1445 # reside on that node. See memmap_init_zone()
1447 config NODES_SPAN_OTHER_NODES
1449 depends on X86_64_ACPI_NUMA
1452 bool "NUMA emulation"
1455 Enable NUMA emulation. A flat machine will be split
1456 into virtual nodes when booted with "numa=fake=N", where N is the
1457 number of nodes. This is only useful for debugging.
1460 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1462 default "10" if MAXSMP
1463 default "6" if X86_64
1465 depends on NEED_MULTIPLE_NODES
1467 Specify the maximum number of NUMA Nodes available on the target
1468 system. Increases memory reserved to accommodate various tables.
1470 config ARCH_HAVE_MEMORY_PRESENT
1472 depends on X86_32 && DISCONTIGMEM
1474 config NEED_NODE_MEMMAP_SIZE
1476 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1478 config ARCH_FLATMEM_ENABLE
1480 depends on X86_32 && !NUMA
1482 config ARCH_DISCONTIGMEM_ENABLE
1484 depends on NUMA && X86_32
1486 config ARCH_DISCONTIGMEM_DEFAULT
1488 depends on NUMA && X86_32
1490 config ARCH_SPARSEMEM_ENABLE
1492 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1493 select SPARSEMEM_STATIC if X86_32
1494 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1496 config ARCH_SPARSEMEM_DEFAULT
1500 config ARCH_SELECT_MEMORY_MODEL
1502 depends on ARCH_SPARSEMEM_ENABLE
1504 config ARCH_MEMORY_PROBE
1505 bool "Enable sysfs memory/probe interface"
1506 depends on X86_64 && MEMORY_HOTPLUG
1508 This option enables a sysfs memory/probe interface for testing.
1509 See Documentation/memory-hotplug.txt for more information.
1510 If you are unsure how to answer this question, answer N.
1512 config ARCH_PROC_KCORE_TEXT
1514 depends on X86_64 && PROC_KCORE
1516 config ILLEGAL_POINTER_VALUE
1519 default 0xdead000000000000 if X86_64
1523 config X86_PMEM_LEGACY_DEVICE
1526 config X86_PMEM_LEGACY
1527 tristate "Support non-standard NVDIMMs and ADR protected memory"
1528 depends on PHYS_ADDR_T_64BIT
1530 select X86_PMEM_LEGACY_DEVICE
1533 Treat memory marked using the non-standard e820 type of 12 as used
1534 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1535 The kernel will offer these regions to the 'pmem' driver so
1536 they can be used for persistent storage.
1541 bool "Allocate 3rd-level pagetables from highmem"
1544 The VM uses one page table entry for each page of physical memory.
1545 For systems with a lot of RAM, this can be wasteful of precious
1546 low memory. Setting this option will put user-space page table
1547 entries in high memory.
1549 config X86_CHECK_BIOS_CORRUPTION
1550 bool "Check for low memory corruption"
1552 Periodically check for memory corruption in low memory, which
1553 is suspected to be caused by BIOS. Even when enabled in the
1554 configuration, it is disabled at runtime. Enable it by
1555 setting "memory_corruption_check=1" on the kernel command
1556 line. By default it scans the low 64k of memory every 60
1557 seconds; see the memory_corruption_check_size and
1558 memory_corruption_check_period parameters in
1559 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1561 When enabled with the default parameters, this option has
1562 almost no overhead, as it reserves a relatively small amount
1563 of memory and scans it infrequently. It both detects corruption
1564 and prevents it from affecting the running system.
1566 It is, however, intended as a diagnostic tool; if repeatable
1567 BIOS-originated corruption always affects the same memory,
1568 you can use memmap= to prevent the kernel from using that
1571 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1572 bool "Set the default setting of memory_corruption_check"
1573 depends on X86_CHECK_BIOS_CORRUPTION
1576 Set whether the default state of memory_corruption_check is
1579 config X86_RESERVE_LOW
1580 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1584 Specify the amount of low memory to reserve for the BIOS.
1586 The first page contains BIOS data structures that the kernel
1587 must not use, so that page must always be reserved.
1589 By default we reserve the first 64K of physical RAM, as a
1590 number of BIOSes are known to corrupt that memory range
1591 during events such as suspend/resume or monitor cable
1592 insertion, so it must not be used by the kernel.
1594 You can set this to 4 if you are absolutely sure that you
1595 trust the BIOS to get all its memory reservations and usages
1596 right. If you know your BIOS have problems beyond the
1597 default 64K area, you can set this to 640 to avoid using the
1598 entire low memory range.
1600 If you have doubts about the BIOS (e.g. suspend/resume does
1601 not work or there's kernel crashes after certain hardware
1602 hotplug events) then you might want to enable
1603 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1604 typical corruption patterns.
1606 Leave this to the default value of 64 if you are unsure.
1608 config MATH_EMULATION
1610 depends on MODIFY_LDT_SYSCALL
1611 prompt "Math emulation" if X86_32
1613 Linux can emulate a math coprocessor (used for floating point
1614 operations) if you don't have one. 486DX and Pentium processors have
1615 a math coprocessor built in, 486SX and 386 do not, unless you added
1616 a 487DX or 387, respectively. (The messages during boot time can
1617 give you some hints here ["man dmesg"].) Everyone needs either a
1618 coprocessor or this emulation.
1620 If you don't have a math coprocessor, you need to say Y here; if you
1621 say Y here even though you have a coprocessor, the coprocessor will
1622 be used nevertheless. (This behavior can be changed with the kernel
1623 command line option "no387", which comes handy if your coprocessor
1624 is broken. Try "man bootparam" or see the documentation of your boot
1625 loader (lilo or loadlin) about how to pass options to the kernel at
1626 boot time.) This means that it is a good idea to say Y here if you
1627 intend to use this kernel on different machines.
1629 More information about the internals of the Linux math coprocessor
1630 emulation can be found in <file:arch/x86/math-emu/README>.
1632 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1633 kernel, it won't hurt.
1637 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1639 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1640 the Memory Type Range Registers (MTRRs) may be used to control
1641 processor access to memory ranges. This is most useful if you have
1642 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1643 allows bus write transfers to be combined into a larger transfer
1644 before bursting over the PCI/AGP bus. This can increase performance
1645 of image write operations 2.5 times or more. Saying Y here creates a
1646 /proc/mtrr file which may be used to manipulate your processor's
1647 MTRRs. Typically the X server should use this.
1649 This code has a reasonably generic interface so that similar
1650 control registers on other processors can be easily supported
1653 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1654 Registers (ARRs) which provide a similar functionality to MTRRs. For
1655 these, the ARRs are used to emulate the MTRRs.
1656 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1657 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1658 write-combining. All of these processors are supported by this code
1659 and it makes sense to say Y here if you have one of them.
1661 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1662 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1663 can lead to all sorts of problems, so it's good to say Y here.
1665 You can safely say Y even if your machine doesn't have MTRRs, you'll
1666 just add about 9 KB to your kernel.
1668 See <file:Documentation/x86/mtrr.txt> for more information.
1670 config MTRR_SANITIZER
1672 prompt "MTRR cleanup support"
1675 Convert MTRR layout from continuous to discrete, so X drivers can
1676 add writeback entries.
1678 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1679 The largest mtrr entry size for a continuous block can be set with
1684 config MTRR_SANITIZER_ENABLE_DEFAULT
1685 int "MTRR cleanup enable value (0-1)"
1688 depends on MTRR_SANITIZER
1690 Enable mtrr cleanup default value
1692 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1693 int "MTRR cleanup spare reg num (0-7)"
1696 depends on MTRR_SANITIZER
1698 mtrr cleanup spare entries default, it can be changed via
1699 mtrr_spare_reg_nr=N on the kernel command line.
1703 prompt "x86 PAT support" if EXPERT
1706 Use PAT attributes to setup page level cache control.
1708 PATs are the modern equivalents of MTRRs and are much more
1709 flexible than MTRRs.
1711 Say N here if you see bootup problems (boot crash, boot hang,
1712 spontaneous reboots) or a non-working video driver.
1716 config ARCH_USES_PG_UNCACHED
1722 prompt "x86 architectural random number generator" if EXPERT
1724 Enable the x86 architectural RDRAND instruction
1725 (Intel Bull Mountain technology) to generate random numbers.
1726 If supported, this is a high bandwidth, cryptographically
1727 secure hardware random number generator.
1731 prompt "Supervisor Mode Access Prevention" if EXPERT
1733 Supervisor Mode Access Prevention (SMAP) is a security
1734 feature in newer Intel processors. There is a small
1735 performance cost if this enabled and turned on; there is
1736 also a small increase in the kernel size if this is enabled.
1740 config X86_INTEL_MPX
1741 prompt "Intel MPX (Memory Protection Extensions)"
1743 depends on CPU_SUP_INTEL
1745 MPX provides hardware features that can be used in
1746 conjunction with compiler-instrumented code to check
1747 memory references. It is designed to detect buffer
1748 overflow or underflow bugs.
1750 This option enables running applications which are
1751 instrumented or otherwise use MPX. It does not use MPX
1752 itself inside the kernel or to protect the kernel
1753 against bad memory references.
1755 Enabling this option will make the kernel larger:
1756 ~8k of kernel text and 36 bytes of data on a 64-bit
1757 defconfig. It adds a long to the 'mm_struct' which
1758 will increase the kernel memory overhead of each
1759 process and adds some branches to paths used during
1760 exec() and munmap().
1762 For details, see Documentation/x86/intel_mpx.txt
1766 config X86_INTEL_MEMORY_PROTECTION_KEYS
1767 prompt "Intel Memory Protection Keys"
1769 # Note: only available in 64-bit mode
1770 depends on CPU_SUP_INTEL && X86_64
1771 select ARCH_USES_HIGH_VMA_FLAGS
1772 select ARCH_HAS_PKEYS
1774 Memory Protection Keys provides a mechanism for enforcing
1775 page-based protections, but without requiring modification of the
1776 page tables when an application changes protection domains.
1778 For details, see Documentation/x86/protection-keys.txt
1783 bool "EFI runtime service support"
1786 select EFI_RUNTIME_WRAPPERS
1788 This enables the kernel to use EFI runtime services that are
1789 available (such as the EFI variable services).
1791 This option is only useful on systems that have EFI firmware.
1792 In addition, you should use the latest ELILO loader available
1793 at <http://elilo.sourceforge.net> in order to take advantage
1794 of EFI runtime services. However, even with this option, the
1795 resultant kernel should continue to boot on existing non-EFI
1799 bool "EFI stub support"
1800 depends on EFI && !X86_USE_3DNOW
1803 This kernel feature allows a bzImage to be loaded directly
1804 by EFI firmware without the use of a bootloader.
1806 See Documentation/efi-stub.txt for more information.
1809 bool "EFI mixed-mode support"
1810 depends on EFI_STUB && X86_64
1812 Enabling this feature allows a 64-bit kernel to be booted
1813 on a 32-bit firmware, provided that your CPU supports 64-bit
1816 Note that it is not possible to boot a mixed-mode enabled
1817 kernel via the EFI boot stub - a bootloader that supports
1818 the EFI handover protocol must be used.
1824 prompt "Enable seccomp to safely compute untrusted bytecode"
1826 This kernel feature is useful for number crunching applications
1827 that may need to compute untrusted bytecode during their
1828 execution. By using pipes or other transports made available to
1829 the process as file descriptors supporting the read/write
1830 syscalls, it's possible to isolate those applications in
1831 their own address space using seccomp. Once seccomp is
1832 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1833 and the task is only allowed to execute a few safe syscalls
1834 defined by each seccomp mode.
1836 If unsure, say Y. Only embedded should say N here.
1838 source kernel/Kconfig.hz
1841 bool "kexec system call"
1844 kexec is a system call that implements the ability to shutdown your
1845 current kernel, and to start another kernel. It is like a reboot
1846 but it is independent of the system firmware. And like a reboot
1847 you can start any kernel with it, not just Linux.
1849 The name comes from the similarity to the exec system call.
1851 It is an ongoing process to be certain the hardware in a machine
1852 is properly shutdown, so do not be surprised if this code does not
1853 initially work for you. As of this writing the exact hardware
1854 interface is strongly in flux, so no good recommendation can be
1858 bool "kexec file based system call"
1863 depends on CRYPTO_SHA256=y
1865 This is new version of kexec system call. This system call is
1866 file based and takes file descriptors as system call argument
1867 for kernel and initramfs as opposed to list of segments as
1868 accepted by previous system call.
1870 config KEXEC_VERIFY_SIG
1871 bool "Verify kernel signature during kexec_file_load() syscall"
1872 depends on KEXEC_FILE
1874 This option makes kernel signature verification mandatory for
1875 the kexec_file_load() syscall.
1877 In addition to that option, you need to enable signature
1878 verification for the corresponding kernel image type being
1879 loaded in order for this to work.
1881 config KEXEC_BZIMAGE_VERIFY_SIG
1882 bool "Enable bzImage signature verification support"
1883 depends on KEXEC_VERIFY_SIG
1884 depends on SIGNED_PE_FILE_VERIFICATION
1885 select SYSTEM_TRUSTED_KEYRING
1887 Enable bzImage signature verification support.
1890 bool "kernel crash dumps"
1891 depends on X86_64 || (X86_32 && HIGHMEM)
1893 Generate crash dump after being started by kexec.
1894 This should be normally only set in special crash dump kernels
1895 which are loaded in the main kernel with kexec-tools into
1896 a specially reserved region and then later executed after
1897 a crash by kdump/kexec. The crash dump kernel must be compiled
1898 to a memory address not used by the main kernel or BIOS using
1899 PHYSICAL_START, or it must be built as a relocatable image
1900 (CONFIG_RELOCATABLE=y).
1901 For more details see Documentation/kdump/kdump.txt
1905 depends on KEXEC && HIBERNATION
1907 Jump between original kernel and kexeced kernel and invoke
1908 code in physical address mode via KEXEC
1910 config PHYSICAL_START
1911 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1914 This gives the physical address where the kernel is loaded.
1916 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1917 bzImage will decompress itself to above physical address and
1918 run from there. Otherwise, bzImage will run from the address where
1919 it has been loaded by the boot loader and will ignore above physical
1922 In normal kdump cases one does not have to set/change this option
1923 as now bzImage can be compiled as a completely relocatable image
1924 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1925 address. This option is mainly useful for the folks who don't want
1926 to use a bzImage for capturing the crash dump and want to use a
1927 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1928 to be specifically compiled to run from a specific memory area
1929 (normally a reserved region) and this option comes handy.
1931 So if you are using bzImage for capturing the crash dump,
1932 leave the value here unchanged to 0x1000000 and set
1933 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1934 for capturing the crash dump change this value to start of
1935 the reserved region. In other words, it can be set based on
1936 the "X" value as specified in the "crashkernel=YM@XM"
1937 command line boot parameter passed to the panic-ed
1938 kernel. Please take a look at Documentation/kdump/kdump.txt
1939 for more details about crash dumps.
1941 Usage of bzImage for capturing the crash dump is recommended as
1942 one does not have to build two kernels. Same kernel can be used
1943 as production kernel and capture kernel. Above option should have
1944 gone away after relocatable bzImage support is introduced. But it
1945 is present because there are users out there who continue to use
1946 vmlinux for dump capture. This option should go away down the
1949 Don't change this unless you know what you are doing.
1952 bool "Build a relocatable kernel"
1955 This builds a kernel image that retains relocation information
1956 so it can be loaded someplace besides the default 1MB.
1957 The relocations tend to make the kernel binary about 10% larger,
1958 but are discarded at runtime.
1960 One use is for the kexec on panic case where the recovery kernel
1961 must live at a different physical address than the primary
1964 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1965 it has been loaded at and the compile time physical address
1966 (CONFIG_PHYSICAL_START) is used as the minimum location.
1968 config RANDOMIZE_BASE
1969 bool "Randomize the address of the kernel image (KASLR)"
1970 depends on RELOCATABLE
1973 In support of Kernel Address Space Layout Randomization (KASLR),
1974 this randomizes the physical address at which the kernel image
1975 is decompressed and the virtual address where the kernel
1976 image is mapped, as a security feature that deters exploit
1977 attempts relying on knowledge of the location of kernel
1980 On 64-bit, the kernel physical and virtual addresses are
1981 randomized separately. The physical address will be anywhere
1982 between 16MB and the top of physical memory (up to 64TB). The
1983 virtual address will be randomized from 16MB up to 1GB (9 bits
1984 of entropy). Note that this also reduces the memory space
1985 available to kernel modules from 1.5GB to 1GB.
1987 On 32-bit, the kernel physical and virtual addresses are
1988 randomized together. They will be randomized from 16MB up to
1989 512MB (8 bits of entropy).
1991 Entropy is generated using the RDRAND instruction if it is
1992 supported. If RDTSC is supported, its value is mixed into
1993 the entropy pool as well. If neither RDRAND nor RDTSC are
1994 supported, then entropy is read from the i8254 timer. The
1995 usable entropy is limited by the kernel being built using
1996 2GB addressing, and that PHYSICAL_ALIGN must be at a
1997 minimum of 2MB. As a result, only 10 bits of entropy are
1998 theoretically possible, but the implementations are further
1999 limited due to memory layouts.
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
2792 config HAVE_GENERIC_GUP
2795 source "net/Kconfig"
2797 source "drivers/Kconfig"
2799 source "drivers/firmware/Kconfig"
2803 source "arch/x86/Kconfig.debug"
2805 source "security/Kconfig"
2807 source "crypto/Kconfig"
2809 source "arch/x86/kvm/Kconfig"
2811 source "lib/Kconfig"