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 if (MEMORY_ISOLATION && COMPACTION) || CMA
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_UACCESS_FLUSHCACHE if X86_64
58 select ARCH_HAS_SET_MEMORY
59 select ARCH_HAS_SG_CHAIN
60 select ARCH_HAS_STRICT_KERNEL_RWX
61 select ARCH_HAS_STRICT_MODULE_RWX
62 select ARCH_HAS_UBSAN_SANITIZE_ALL
63 select ARCH_HAS_ZONE_DEVICE if X86_64
64 select ARCH_HAVE_NMI_SAFE_CMPXCHG
65 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
66 select ARCH_MIGHT_HAVE_PC_PARPORT
67 select ARCH_MIGHT_HAVE_PC_SERIO
68 select ARCH_SUPPORTS_ATOMIC_RMW
69 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
70 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
71 select ARCH_USE_BUILTIN_BSWAP
72 select ARCH_USE_QUEUED_RWLOCKS
73 select ARCH_USE_QUEUED_SPINLOCKS
74 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
75 select ARCH_WANT_FRAME_POINTERS
76 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
77 select ARCH_WANTS_THP_SWAP if X86_64
78 select BUILDTIME_EXTABLE_SORT
80 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
81 select CLOCKSOURCE_WATCHDOG
82 select DCACHE_WORD_ACCESS
83 select EDAC_ATOMIC_SCRUB
85 select GENERIC_CLOCKEVENTS
86 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
87 select GENERIC_CLOCKEVENTS_MIN_ADJUST
88 select GENERIC_CMOS_UPDATE
89 select GENERIC_CPU_AUTOPROBE
90 select GENERIC_EARLY_IOREMAP
91 select GENERIC_FIND_FIRST_BIT
93 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
94 select GENERIC_IRQ_MIGRATION if SMP
95 select GENERIC_IRQ_PROBE
96 select GENERIC_IRQ_SHOW
97 select GENERIC_PENDING_IRQ if SMP
98 select GENERIC_SMP_IDLE_THREAD
99 select GENERIC_STRNCPY_FROM_USER
100 select GENERIC_STRNLEN_USER
101 select GENERIC_TIME_VSYSCALL
102 select HAVE_ACPI_APEI if ACPI
103 select HAVE_ACPI_APEI_NMI if ACPI
104 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
105 select HAVE_ARCH_AUDITSYSCALL
106 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
107 select HAVE_ARCH_JUMP_LABEL
108 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
109 select HAVE_ARCH_KGDB
110 select HAVE_ARCH_KMEMCHECK
111 select HAVE_ARCH_MMAP_RND_BITS if MMU
112 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
113 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
114 select HAVE_ARCH_SECCOMP_FILTER
115 select HAVE_ARCH_TRACEHOOK
116 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
117 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
118 select HAVE_ARCH_VMAP_STACK if X86_64
119 select HAVE_ARCH_WITHIN_STACK_FRAMES
120 select HAVE_CC_STACKPROTECTOR
121 select HAVE_CMPXCHG_DOUBLE
122 select HAVE_CMPXCHG_LOCAL
123 select HAVE_CONTEXT_TRACKING if X86_64
124 select HAVE_COPY_THREAD_TLS
125 select HAVE_C_RECORDMCOUNT
126 select HAVE_DEBUG_KMEMLEAK
127 select HAVE_DEBUG_STACKOVERFLOW
128 select HAVE_DMA_API_DEBUG
129 select HAVE_DMA_CONTIGUOUS
130 select HAVE_DYNAMIC_FTRACE
131 select HAVE_DYNAMIC_FTRACE_WITH_REGS
132 select HAVE_EBPF_JIT if X86_64
133 select HAVE_EFFICIENT_UNALIGNED_ACCESS
134 select HAVE_EXIT_THREAD
135 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
136 select HAVE_FTRACE_MCOUNT_RECORD
137 select HAVE_FUNCTION_GRAPH_TRACER
138 select HAVE_FUNCTION_TRACER
139 select HAVE_GCC_PLUGINS
140 select HAVE_HW_BREAKPOINT
142 select HAVE_IOREMAP_PROT
143 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
144 select HAVE_IRQ_TIME_ACCOUNTING
145 select HAVE_KERNEL_BZIP2
146 select HAVE_KERNEL_GZIP
147 select HAVE_KERNEL_LZ4
148 select HAVE_KERNEL_LZMA
149 select HAVE_KERNEL_LZO
150 select HAVE_KERNEL_XZ
152 select HAVE_KPROBES_ON_FTRACE
153 select HAVE_KRETPROBES
155 select HAVE_LIVEPATCH if X86_64
157 select HAVE_MEMBLOCK_NODE_MAP
158 select HAVE_MIXED_BREAKPOINTS_REGS
161 select HAVE_OPTPROBES
162 select HAVE_PCSPKR_PLATFORM
163 select HAVE_PERF_EVENTS
164 select HAVE_PERF_EVENTS_NMI
165 select HAVE_PERF_REGS
166 select HAVE_PERF_USER_STACK_DUMP
167 select HAVE_REGS_AND_STACK_ACCESS_API
168 select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER && STACK_VALIDATION
169 select HAVE_STACK_VALIDATION if X86_64
170 select HAVE_SYSCALL_TRACEPOINTS
171 select HAVE_UNSTABLE_SCHED_CLOCK
172 select HAVE_USER_RETURN_NOTIFIER
173 select IRQ_FORCED_THREADING
174 select PCI_LOCKLESS_CONFIG
177 select RTC_MC146818_LIB
180 select SYSCTL_EXCEPTION_TRACE
181 select THREAD_INFO_IN_TASK
182 select USER_STACKTRACE_SUPPORT
184 select X86_FEATURE_NAMES if PROC_FS
186 config INSTRUCTION_DECODER
188 depends on KPROBES || PERF_EVENTS || UPROBES
192 default "elf32-i386" if X86_32
193 default "elf64-x86-64" if X86_64
195 config ARCH_DEFCONFIG
197 default "arch/x86/configs/i386_defconfig" if X86_32
198 default "arch/x86/configs/x86_64_defconfig" if X86_64
200 config LOCKDEP_SUPPORT
203 config STACKTRACE_SUPPORT
209 config ARCH_MMAP_RND_BITS_MIN
213 config ARCH_MMAP_RND_BITS_MAX
217 config ARCH_MMAP_RND_COMPAT_BITS_MIN
220 config ARCH_MMAP_RND_COMPAT_BITS_MAX
226 config NEED_DMA_MAP_STATE
228 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
230 config NEED_SG_DMA_LENGTH
233 config GENERIC_ISA_DMA
235 depends on ISA_DMA_API
240 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
242 config GENERIC_BUG_RELATIVE_POINTERS
245 config GENERIC_HWEIGHT
248 config ARCH_MAY_HAVE_PC_FDC
250 depends on ISA_DMA_API
252 config RWSEM_XCHGADD_ALGORITHM
255 config GENERIC_CALIBRATE_DELAY
258 config ARCH_HAS_CPU_RELAX
261 config ARCH_HAS_CACHE_LINE_SIZE
264 config HAVE_SETUP_PER_CPU_AREA
267 config NEED_PER_CPU_EMBED_FIRST_CHUNK
270 config NEED_PER_CPU_PAGE_FIRST_CHUNK
273 config ARCH_HIBERNATION_POSSIBLE
276 config ARCH_SUSPEND_POSSIBLE
279 config ARCH_WANT_HUGE_PMD_SHARE
282 config ARCH_WANT_GENERAL_HUGETLB
291 config ARCH_SUPPORTS_OPTIMIZED_INLINING
294 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
297 config KASAN_SHADOW_OFFSET
300 default 0xdff8000000000000 if X86_5LEVEL
301 default 0xdffffc0000000000
303 config HAVE_INTEL_TXT
305 depends on INTEL_IOMMU && ACPI
309 depends on X86_32 && SMP
313 depends on X86_64 && SMP
315 config X86_32_LAZY_GS
317 depends on X86_32 && !CC_STACKPROTECTOR
319 config ARCH_SUPPORTS_UPROBES
322 config FIX_EARLYCON_MEM
325 config PGTABLE_LEVELS
331 source "init/Kconfig"
332 source "kernel/Kconfig.freezer"
334 menu "Processor type and features"
337 bool "DMA memory allocation support" if EXPERT
340 DMA memory allocation support allows devices with less than 32-bit
341 addressing to allocate within the first 16MB of address space.
342 Disable if no such devices will be used.
347 bool "Symmetric multi-processing support"
349 This enables support for systems with more than one CPU. If you have
350 a system with only one CPU, say N. If you have a system with more
353 If you say N here, the kernel will run on uni- and multiprocessor
354 machines, but will use only one CPU of a multiprocessor machine. If
355 you say Y here, the kernel will run on many, but not all,
356 uniprocessor machines. On a uniprocessor machine, the kernel
357 will run faster if you say N here.
359 Note that if you say Y here and choose architecture "586" or
360 "Pentium" under "Processor family", the kernel will not work on 486
361 architectures. Similarly, multiprocessor kernels for the "PPro"
362 architecture may not work on all Pentium based boards.
364 People using multiprocessor machines who say Y here should also say
365 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
366 Management" code will be disabled if you say Y here.
368 See also <file:Documentation/x86/i386/IO-APIC.txt>,
369 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
370 <http://www.tldp.org/docs.html#howto>.
372 If you don't know what to do here, say N.
374 config X86_FEATURE_NAMES
375 bool "Processor feature human-readable names" if EMBEDDED
378 This option compiles in a table of x86 feature bits and corresponding
379 names. This is required to support /proc/cpuinfo and a few kernel
380 messages. You can disable this to save space, at the expense of
381 making those few kernel messages show numeric feature bits instead.
385 config X86_FAST_FEATURE_TESTS
386 bool "Fast CPU feature tests" if EMBEDDED
389 Some fast-paths in the kernel depend on the capabilities of the CPU.
390 Say Y here for the kernel to patch in the appropriate code at runtime
391 based on the capabilities of the CPU. The infrastructure for patching
392 code at runtime takes up some additional space; space-constrained
393 embedded systems may wish to say N here to produce smaller, slightly
397 bool "Support x2apic"
398 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
400 This enables x2apic support on CPUs that have this feature.
402 This allows 32-bit apic IDs (so it can support very large systems),
403 and accesses the local apic via MSRs not via mmio.
405 If you don't know what to do here, say N.
408 bool "Enable MPS table" if ACPI || SFI
410 depends on X86_LOCAL_APIC
412 For old smp systems that do not have proper acpi support. Newer systems
413 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
416 bool "Support for big SMP systems with more than 8 CPUs"
417 depends on X86_32 && SMP
419 This option is needed for the systems that have more than 8 CPUs
423 depends on X86_GOLDFISH
426 bool "Intel Resource Director Technology Allocation support"
428 depends on X86 && CPU_SUP_INTEL
431 Select to enable resource allocation which is a sub-feature of
432 Intel Resource Director Technology(RDT). More information about
433 RDT can be found in the Intel x86 Architecture Software
439 config X86_EXTENDED_PLATFORM
440 bool "Support for extended (non-PC) x86 platforms"
443 If you disable this option then the kernel will only support
444 standard PC platforms. (which covers the vast majority of
447 If you enable this option then you'll be able to select support
448 for the following (non-PC) 32 bit x86 platforms:
449 Goldfish (Android emulator)
452 SGI 320/540 (Visual Workstation)
453 STA2X11-based (e.g. Northville)
454 Moorestown MID devices
456 If you have one of these systems, or if you want to build a
457 generic distribution kernel, say Y here - otherwise say N.
461 config X86_EXTENDED_PLATFORM
462 bool "Support for extended (non-PC) x86 platforms"
465 If you disable this option then the kernel will only support
466 standard PC platforms. (which covers the vast majority of
469 If you enable this option then you'll be able to select support
470 for the following (non-PC) 64 bit x86 platforms:
475 If you have one of these systems, or if you want to build a
476 generic distribution kernel, say Y here - otherwise say N.
478 # This is an alphabetically sorted list of 64 bit extended platforms
479 # Please maintain the alphabetic order if and when there are additions
481 bool "Numascale NumaChip"
483 depends on X86_EXTENDED_PLATFORM
486 depends on X86_X2APIC
487 depends on PCI_MMCONFIG
489 Adds support for Numascale NumaChip large-SMP systems. Needed to
490 enable more than ~168 cores.
491 If you don't have one of these, you should say N here.
495 select HYPERVISOR_GUEST
497 depends on X86_64 && PCI
498 depends on X86_EXTENDED_PLATFORM
501 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
502 supposed to run on these EM64T-based machines. Only choose this option
503 if you have one of these machines.
506 bool "SGI Ultraviolet"
508 depends on X86_EXTENDED_PLATFORM
511 depends on X86_X2APIC
514 This option is needed in order to support SGI Ultraviolet systems.
515 If you don't have one of these, you should say N here.
517 # Following is an alphabetically sorted list of 32 bit extended platforms
518 # Please maintain the alphabetic order if and when there are additions
521 bool "Goldfish (Virtual Platform)"
522 depends on X86_EXTENDED_PLATFORM
524 Enable support for the Goldfish virtual platform used primarily
525 for Android development. Unless you are building for the Android
526 Goldfish emulator say N here.
529 bool "CE4100 TV platform"
531 depends on PCI_GODIRECT
532 depends on X86_IO_APIC
534 depends on X86_EXTENDED_PLATFORM
535 select X86_REBOOTFIXUPS
537 select OF_EARLY_FLATTREE
539 Select for the Intel CE media processor (CE4100) SOC.
540 This option compiles in support for the CE4100 SOC for settop
541 boxes and media devices.
544 bool "Intel MID platform support"
545 depends on X86_EXTENDED_PLATFORM
546 depends on X86_PLATFORM_DEVICES
548 depends on X86_64 || (PCI_GOANY && X86_32)
549 depends on X86_IO_APIC
555 select MFD_INTEL_MSIC
557 Select to build a kernel capable of supporting Intel MID (Mobile
558 Internet Device) platform systems which do not have the PCI legacy
559 interfaces. If you are building for a PC class system say N here.
561 Intel MID platforms are based on an Intel processor and chipset which
562 consume less power than most of the x86 derivatives.
564 config X86_INTEL_QUARK
565 bool "Intel Quark platform support"
567 depends on X86_EXTENDED_PLATFORM
568 depends on X86_PLATFORM_DEVICES
572 depends on X86_IO_APIC
577 Select to include support for Quark X1000 SoC.
578 Say Y here if you have a Quark based system such as the Arduino
579 compatible Intel Galileo.
581 config X86_INTEL_LPSS
582 bool "Intel Low Power Subsystem Support"
583 depends on X86 && ACPI
588 Select to build support for Intel Low Power Subsystem such as
589 found on Intel Lynxpoint PCH. Selecting this option enables
590 things like clock tree (common clock framework) and pincontrol
591 which are needed by the LPSS peripheral drivers.
593 config X86_AMD_PLATFORM_DEVICE
594 bool "AMD ACPI2Platform devices support"
599 Select to interpret AMD specific ACPI device to platform device
600 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
601 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
602 implemented under PINCTRL subsystem.
605 tristate "Intel SoC IOSF Sideband support for SoC platforms"
608 This option enables sideband register access support for Intel SoC
609 platforms. On these platforms the IOSF sideband is used in lieu of
610 MSR's for some register accesses, mostly but not limited to thermal
611 and power. Drivers may query the availability of this device to
612 determine if they need the sideband in order to work on these
613 platforms. The sideband is available on the following SoC products.
614 This list is not meant to be exclusive.
619 You should say Y if you are running a kernel on one of these SoC's.
621 config IOSF_MBI_DEBUG
622 bool "Enable IOSF sideband access through debugfs"
623 depends on IOSF_MBI && DEBUG_FS
625 Select this option to expose the IOSF sideband access registers (MCR,
626 MDR, MCRX) through debugfs to write and read register information from
627 different units on the SoC. This is most useful for obtaining device
628 state information for debug and analysis. As this is a general access
629 mechanism, users of this option would have specific knowledge of the
630 device they want to access.
632 If you don't require the option or are in doubt, say N.
635 bool "RDC R-321x SoC"
637 depends on X86_EXTENDED_PLATFORM
639 select X86_REBOOTFIXUPS
641 This option is needed for RDC R-321x system-on-chip, also known
643 If you don't have one of these chips, you should say N here.
645 config X86_32_NON_STANDARD
646 bool "Support non-standard 32-bit SMP architectures"
647 depends on X86_32 && SMP
648 depends on X86_EXTENDED_PLATFORM
650 This option compiles in the bigsmp and STA2X11 default
651 subarchitectures. It is intended for a generic binary
652 kernel. If you select them all, kernel will probe it one by
653 one and will fallback to default.
655 # Alphabetically sorted list of Non standard 32 bit platforms
657 config X86_SUPPORTS_MEMORY_FAILURE
659 # MCE code calls memory_failure():
661 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
662 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
663 depends on X86_64 || !SPARSEMEM
664 select ARCH_SUPPORTS_MEMORY_FAILURE
667 bool "STA2X11 Companion Chip Support"
668 depends on X86_32_NON_STANDARD && PCI
669 select X86_DEV_DMA_OPS
676 This adds support for boards based on the STA2X11 IO-Hub,
677 a.k.a. "ConneXt". The chip is used in place of the standard
678 PC chipset, so all "standard" peripherals are missing. If this
679 option is selected the kernel will still be able to boot on
680 standard PC machines.
683 tristate "Eurobraille/Iris poweroff module"
686 The Iris machines from EuroBraille do not have APM or ACPI support
687 to shut themselves down properly. A special I/O sequence is
688 needed to do so, which is what this module does at
691 This is only for Iris machines from EuroBraille.
695 config SCHED_OMIT_FRAME_POINTER
697 prompt "Single-depth WCHAN output"
700 Calculate simpler /proc/<PID>/wchan values. If this option
701 is disabled then wchan values will recurse back to the
702 caller function. This provides more accurate wchan values,
703 at the expense of slightly more scheduling overhead.
705 If in doubt, say "Y".
707 menuconfig HYPERVISOR_GUEST
708 bool "Linux guest support"
710 Say Y here to enable options for running Linux under various hyper-
711 visors. This option enables basic hypervisor detection and platform
714 If you say N, all options in this submenu will be skipped and
715 disabled, and Linux guest support won't be built in.
720 bool "Enable paravirtualization code"
722 This changes the kernel so it can modify itself when it is run
723 under a hypervisor, potentially improving performance significantly
724 over full virtualization. However, when run without a hypervisor
725 the kernel is theoretically slower and slightly larger.
727 config PARAVIRT_DEBUG
728 bool "paravirt-ops debugging"
729 depends on PARAVIRT && DEBUG_KERNEL
731 Enable to debug paravirt_ops internals. Specifically, BUG if
732 a paravirt_op is missing when it is called.
734 config PARAVIRT_SPINLOCKS
735 bool "Paravirtualization layer for spinlocks"
736 depends on PARAVIRT && SMP
738 Paravirtualized spinlocks allow a pvops backend to replace the
739 spinlock implementation with something virtualization-friendly
740 (for example, block the virtual CPU rather than spinning).
742 It has a minimal impact on native kernels and gives a nice performance
743 benefit on paravirtualized KVM / Xen kernels.
745 If you are unsure how to answer this question, answer Y.
747 config QUEUED_LOCK_STAT
748 bool "Paravirt queued spinlock statistics"
749 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
751 Enable the collection of statistical data on the slowpath
752 behavior of paravirtualized queued spinlocks and report
755 source "arch/x86/xen/Kconfig"
758 bool "KVM Guest support (including kvmclock)"
760 select PARAVIRT_CLOCK
763 This option enables various optimizations for running under the KVM
764 hypervisor. It includes a paravirtualized clock, so that instead
765 of relying on a PIT (or probably other) emulation by the
766 underlying device model, the host provides the guest with
767 timing infrastructure such as time of day, and system time
770 bool "Enable debug information for KVM Guests in debugfs"
771 depends on KVM_GUEST && DEBUG_FS
774 This option enables collection of various statistics for KVM guest.
775 Statistics are displayed in debugfs filesystem. Enabling this option
776 may incur significant overhead.
778 source "arch/x86/lguest/Kconfig"
780 config PARAVIRT_TIME_ACCOUNTING
781 bool "Paravirtual steal time accounting"
785 Select this option to enable fine granularity task steal time
786 accounting. Time spent executing other tasks in parallel with
787 the current vCPU is discounted from the vCPU power. To account for
788 that, there can be a small performance impact.
790 If in doubt, say N here.
792 config PARAVIRT_CLOCK
795 endif #HYPERVISOR_GUEST
800 source "arch/x86/Kconfig.cpu"
804 prompt "HPET Timer Support" if X86_32
806 Use the IA-PC HPET (High Precision Event Timer) to manage
807 time in preference to the PIT and RTC, if a HPET is
809 HPET is the next generation timer replacing legacy 8254s.
810 The HPET provides a stable time base on SMP
811 systems, unlike the TSC, but it is more expensive to access,
812 as it is off-chip. The interface used is documented
813 in the HPET spec, revision 1.
815 You can safely choose Y here. However, HPET will only be
816 activated if the platform and the BIOS support this feature.
817 Otherwise the 8254 will be used for timing services.
819 Choose N to continue using the legacy 8254 timer.
821 config HPET_EMULATE_RTC
823 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
826 def_bool y if X86_INTEL_MID
827 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
829 depends on X86_INTEL_MID && SFI
831 APB timer is the replacement for 8254, HPET on X86 MID platforms.
832 The APBT provides a stable time base on SMP
833 systems, unlike the TSC, but it is more expensive to access,
834 as it is off-chip. APB timers are always running regardless of CPU
835 C states, they are used as per CPU clockevent device when possible.
837 # Mark as expert because too many people got it wrong.
838 # The code disables itself when not needed.
841 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
842 bool "Enable DMI scanning" if EXPERT
844 Enabled scanning of DMI to identify machine quirks. Say Y
845 here unless you have verified that your setup is not
846 affected by entries in the DMI blacklist. Required by PNP
850 bool "Old AMD GART IOMMU support"
852 depends on X86_64 && PCI && AMD_NB
854 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
855 GART based hardware IOMMUs.
857 The GART supports full DMA access for devices with 32-bit access
858 limitations, on systems with more than 3 GB. This is usually needed
859 for USB, sound, many IDE/SATA chipsets and some other devices.
861 Newer systems typically have a modern AMD IOMMU, supported via
862 the CONFIG_AMD_IOMMU=y config option.
864 In normal configurations this driver is only active when needed:
865 there's more than 3 GB of memory and the system contains a
866 32-bit limited device.
871 bool "IBM Calgary IOMMU support"
873 depends on X86_64 && PCI
875 Support for hardware IOMMUs in IBM's xSeries x366 and x460
876 systems. Needed to run systems with more than 3GB of memory
877 properly with 32-bit PCI devices that do not support DAC
878 (Double Address Cycle). Calgary also supports bus level
879 isolation, where all DMAs pass through the IOMMU. This
880 prevents them from going anywhere except their intended
881 destination. This catches hard-to-find kernel bugs and
882 mis-behaving drivers and devices that do not use the DMA-API
883 properly to set up their DMA buffers. The IOMMU can be
884 turned off at boot time with the iommu=off parameter.
885 Normally the kernel will make the right choice by itself.
888 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
890 prompt "Should Calgary be enabled by default?"
891 depends on CALGARY_IOMMU
893 Should Calgary be enabled by default? if you choose 'y', Calgary
894 will be used (if it exists). If you choose 'n', Calgary will not be
895 used even if it exists. If you choose 'n' and would like to use
896 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
899 # need this always selected by IOMMU for the VIA workaround
903 Support for software bounce buffers used on x86-64 systems
904 which don't have a hardware IOMMU. Using this PCI devices
905 which can only access 32-bits of memory can be used on systems
906 with more than 3 GB of memory.
911 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
914 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
915 depends on X86_64 && SMP && DEBUG_KERNEL
916 select CPUMASK_OFFSTACK
918 Enable maximum number of CPUS and NUMA Nodes for this architecture.
922 int "Maximum number of CPUs" if SMP && !MAXSMP
923 range 2 8 if SMP && X86_32 && !X86_BIGSMP
924 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
925 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
927 default "8192" if MAXSMP
928 default "32" if SMP && X86_BIGSMP
929 default "8" if SMP && X86_32
932 This allows you to specify the maximum number of CPUs which this
933 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
934 supported value is 8192, otherwise the maximum value is 512. The
935 minimum value which makes sense is 2.
937 This is purely to save memory - each supported CPU adds
938 approximately eight kilobytes to the kernel image.
941 bool "SMT (Hyperthreading) scheduler support"
944 SMT scheduler support improves the CPU scheduler's decision making
945 when dealing with Intel Pentium 4 chips with HyperThreading at a
946 cost of slightly increased overhead in some places. If unsure say
951 prompt "Multi-core scheduler support"
954 Multi-core scheduler support improves the CPU scheduler's decision
955 making when dealing with multi-core CPU chips at a cost of slightly
956 increased overhead in some places. If unsure say N here.
959 bool "CPU core priorities scheduler support"
960 depends on SCHED_MC && CPU_SUP_INTEL
961 select X86_INTEL_PSTATE
965 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
966 core ordering determined at manufacturing time, which allows
967 certain cores to reach higher turbo frequencies (when running
968 single threaded workloads) than others.
970 Enabling this kernel feature teaches the scheduler about
971 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
972 scheduler's CPU selection logic accordingly, so that higher
973 overall system performance can be achieved.
975 This feature will have no effect on CPUs without this feature.
977 If unsure say Y here.
979 source "kernel/Kconfig.preempt"
983 depends on !SMP && X86_LOCAL_APIC
986 bool "Local APIC support on uniprocessors" if !PCI_MSI
988 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
990 A local APIC (Advanced Programmable Interrupt Controller) is an
991 integrated interrupt controller in the CPU. If you have a single-CPU
992 system which has a processor with a local APIC, you can say Y here to
993 enable and use it. If you say Y here even though your machine doesn't
994 have a local APIC, then the kernel will still run with no slowdown at
995 all. The local APIC supports CPU-generated self-interrupts (timer,
996 performance counters), and the NMI watchdog which detects hard
1000 bool "IO-APIC support on uniprocessors"
1001 depends on X86_UP_APIC
1003 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1004 SMP-capable replacement for PC-style interrupt controllers. Most
1005 SMP systems and many recent uniprocessor systems have one.
1007 If you have a single-CPU system with an IO-APIC, you can say Y here
1008 to use it. If you say Y here even though your machine doesn't have
1009 an IO-APIC, then the kernel will still run with no slowdown at all.
1011 config X86_LOCAL_APIC
1013 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1014 select IRQ_DOMAIN_HIERARCHY
1015 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1019 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1021 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1022 bool "Reroute for broken boot IRQs"
1023 depends on X86_IO_APIC
1025 This option enables a workaround that fixes a source of
1026 spurious interrupts. This is recommended when threaded
1027 interrupt handling is used on systems where the generation of
1028 superfluous "boot interrupts" cannot be disabled.
1030 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1031 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1032 kernel does during interrupt handling). On chipsets where this
1033 boot IRQ generation cannot be disabled, this workaround keeps
1034 the original IRQ line masked so that only the equivalent "boot
1035 IRQ" is delivered to the CPUs. The workaround also tells the
1036 kernel to set up the IRQ handler on the boot IRQ line. In this
1037 way only one interrupt is delivered to the kernel. Otherwise
1038 the spurious second interrupt may cause the kernel to bring
1039 down (vital) interrupt lines.
1041 Only affects "broken" chipsets. Interrupt sharing may be
1042 increased on these systems.
1045 bool "Machine Check / overheating reporting"
1046 select GENERIC_ALLOCATOR
1049 Machine Check support allows the processor to notify the
1050 kernel if it detects a problem (e.g. overheating, data corruption).
1051 The action the kernel takes depends on the severity of the problem,
1052 ranging from warning messages to halting the machine.
1054 config X86_MCELOG_LEGACY
1055 bool "Support for deprecated /dev/mcelog character device"
1058 Enable support for /dev/mcelog which is needed by the old mcelog
1059 userspace logging daemon. Consider switching to the new generation
1062 config X86_MCE_INTEL
1064 prompt "Intel MCE features"
1065 depends on X86_MCE && X86_LOCAL_APIC
1067 Additional support for intel specific MCE features such as
1068 the thermal monitor.
1072 prompt "AMD MCE features"
1073 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1075 Additional support for AMD specific MCE features such as
1076 the DRAM Error Threshold.
1078 config X86_ANCIENT_MCE
1079 bool "Support for old Pentium 5 / WinChip machine checks"
1080 depends on X86_32 && X86_MCE
1082 Include support for machine check handling on old Pentium 5 or WinChip
1083 systems. These typically need to be enabled explicitly on the command
1086 config X86_MCE_THRESHOLD
1087 depends on X86_MCE_AMD || X86_MCE_INTEL
1090 config X86_MCE_INJECT
1091 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1092 tristate "Machine check injector support"
1094 Provide support for injecting machine checks for testing purposes.
1095 If you don't know what a machine check is and you don't do kernel
1096 QA it is safe to say n.
1098 config X86_THERMAL_VECTOR
1100 depends on X86_MCE_INTEL
1102 source "arch/x86/events/Kconfig"
1104 config X86_LEGACY_VM86
1105 bool "Legacy VM86 support"
1109 This option allows user programs to put the CPU into V8086
1110 mode, which is an 80286-era approximation of 16-bit real mode.
1112 Some very old versions of X and/or vbetool require this option
1113 for user mode setting. Similarly, DOSEMU will use it if
1114 available to accelerate real mode DOS programs. However, any
1115 recent version of DOSEMU, X, or vbetool should be fully
1116 functional even without kernel VM86 support, as they will all
1117 fall back to software emulation. Nevertheless, if you are using
1118 a 16-bit DOS program where 16-bit performance matters, vm86
1119 mode might be faster than emulation and you might want to
1122 Note that any app that works on a 64-bit kernel is unlikely to
1123 need this option, as 64-bit kernels don't, and can't, support
1124 V8086 mode. This option is also unrelated to 16-bit protected
1125 mode and is not needed to run most 16-bit programs under Wine.
1127 Enabling this option increases the complexity of the kernel
1128 and slows down exception handling a tiny bit.
1130 If unsure, say N here.
1134 default X86_LEGACY_VM86
1137 bool "Enable support for 16-bit segments" if EXPERT
1139 depends on MODIFY_LDT_SYSCALL
1141 This option is required by programs like Wine to run 16-bit
1142 protected mode legacy code on x86 processors. Disabling
1143 this option saves about 300 bytes on i386, or around 6K text
1144 plus 16K runtime memory on x86-64,
1148 depends on X86_16BIT && X86_32
1152 depends on X86_16BIT && X86_64
1154 config X86_VSYSCALL_EMULATION
1155 bool "Enable vsyscall emulation" if EXPERT
1159 This enables emulation of the legacy vsyscall page. Disabling
1160 it is roughly equivalent to booting with vsyscall=none, except
1161 that it will also disable the helpful warning if a program
1162 tries to use a vsyscall. With this option set to N, offending
1163 programs will just segfault, citing addresses of the form
1166 This option is required by many programs built before 2013, and
1167 care should be used even with newer programs if set to N.
1169 Disabling this option saves about 7K of kernel size and
1170 possibly 4K of additional runtime pagetable memory.
1173 tristate "Toshiba Laptop support"
1176 This adds a driver to safely access the System Management Mode of
1177 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1178 not work on models with a Phoenix BIOS. The System Management Mode
1179 is used to set the BIOS and power saving options on Toshiba portables.
1181 For information on utilities to make use of this driver see the
1182 Toshiba Linux utilities web site at:
1183 <http://www.buzzard.org.uk/toshiba/>.
1185 Say Y if you intend to run this kernel on a Toshiba portable.
1189 tristate "Dell i8k legacy laptop support"
1191 select SENSORS_DELL_SMM
1193 This option enables legacy /proc/i8k userspace interface in hwmon
1194 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1195 temperature and allows controlling fan speeds of Dell laptops via
1196 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1197 it reports also power and hotkey status. For fan speed control is
1198 needed userspace package i8kutils.
1200 Say Y if you intend to run this kernel on old Dell laptops or want to
1201 use userspace package i8kutils.
1204 config X86_REBOOTFIXUPS
1205 bool "Enable X86 board specific fixups for reboot"
1208 This enables chipset and/or board specific fixups to be done
1209 in order to get reboot to work correctly. This is only needed on
1210 some combinations of hardware and BIOS. The symptom, for which
1211 this config is intended, is when reboot ends with a stalled/hung
1214 Currently, the only fixup is for the Geode machines using
1215 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1217 Say Y if you want to enable the fixup. Currently, it's safe to
1218 enable this option even if you don't need it.
1222 bool "CPU microcode loading support"
1224 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1227 If you say Y here, you will be able to update the microcode on
1228 Intel and AMD processors. The Intel support is for the IA32 family,
1229 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1230 AMD support is for families 0x10 and later. You will obviously need
1231 the actual microcode binary data itself which is not shipped with
1234 The preferred method to load microcode from a detached initrd is described
1235 in Documentation/x86/early-microcode.txt. For that you need to enable
1236 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1237 initrd for microcode blobs.
1239 In addition, you can build-in the microcode into the kernel. For that you
1240 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1241 to the CONFIG_EXTRA_FIRMWARE config option.
1243 config MICROCODE_INTEL
1244 bool "Intel microcode loading support"
1245 depends on MICROCODE
1249 This options enables microcode patch loading support for Intel
1252 For the current Intel microcode data package go to
1253 <https://downloadcenter.intel.com> and search for
1254 'Linux Processor Microcode Data File'.
1256 config MICROCODE_AMD
1257 bool "AMD microcode loading support"
1258 depends on MICROCODE
1261 If you select this option, microcode patch loading support for AMD
1262 processors will be enabled.
1264 config MICROCODE_OLD_INTERFACE
1266 depends on MICROCODE
1269 tristate "/dev/cpu/*/msr - Model-specific register support"
1271 This device gives privileged processes access to the x86
1272 Model-Specific Registers (MSRs). It is a character device with
1273 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1274 MSR accesses are directed to a specific CPU on multi-processor
1278 tristate "/dev/cpu/*/cpuid - CPU information support"
1280 This device gives processes access to the x86 CPUID instruction to
1281 be executed on a specific processor. It is a character device
1282 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1286 prompt "High Memory Support"
1293 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1294 However, the address space of 32-bit x86 processors is only 4
1295 Gigabytes large. That means that, if you have a large amount of
1296 physical memory, not all of it can be "permanently mapped" by the
1297 kernel. The physical memory that's not permanently mapped is called
1300 If you are compiling a kernel which will never run on a machine with
1301 more than 1 Gigabyte total physical RAM, answer "off" here (default
1302 choice and suitable for most users). This will result in a "3GB/1GB"
1303 split: 3GB are mapped so that each process sees a 3GB virtual memory
1304 space and the remaining part of the 4GB virtual memory space is used
1305 by the kernel to permanently map as much physical memory as
1308 If the machine has between 1 and 4 Gigabytes physical RAM, then
1311 If more than 4 Gigabytes is used then answer "64GB" here. This
1312 selection turns Intel PAE (Physical Address Extension) mode on.
1313 PAE implements 3-level paging on IA32 processors. PAE is fully
1314 supported by Linux, PAE mode is implemented on all recent Intel
1315 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1316 then the kernel will not boot on CPUs that don't support PAE!
1318 The actual amount of total physical memory will either be
1319 auto detected or can be forced by using a kernel command line option
1320 such as "mem=256M". (Try "man bootparam" or see the documentation of
1321 your boot loader (lilo or loadlin) about how to pass options to the
1322 kernel at boot time.)
1324 If unsure, say "off".
1329 Select this if you have a 32-bit processor and between 1 and 4
1330 gigabytes of physical RAM.
1337 Select this if you have a 32-bit processor and more than 4
1338 gigabytes of physical RAM.
1343 prompt "Memory split" if EXPERT
1347 Select the desired split between kernel and user memory.
1349 If the address range available to the kernel is less than the
1350 physical memory installed, the remaining memory will be available
1351 as "high memory". Accessing high memory is a little more costly
1352 than low memory, as it needs to be mapped into the kernel first.
1353 Note that increasing the kernel address space limits the range
1354 available to user programs, making the address space there
1355 tighter. Selecting anything other than the default 3G/1G split
1356 will also likely make your kernel incompatible with binary-only
1359 If you are not absolutely sure what you are doing, leave this
1363 bool "3G/1G user/kernel split"
1364 config VMSPLIT_3G_OPT
1366 bool "3G/1G user/kernel split (for full 1G low memory)"
1368 bool "2G/2G user/kernel split"
1369 config VMSPLIT_2G_OPT
1371 bool "2G/2G user/kernel split (for full 2G low memory)"
1373 bool "1G/3G user/kernel split"
1378 default 0xB0000000 if VMSPLIT_3G_OPT
1379 default 0x80000000 if VMSPLIT_2G
1380 default 0x78000000 if VMSPLIT_2G_OPT
1381 default 0x40000000 if VMSPLIT_1G
1387 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1390 bool "PAE (Physical Address Extension) Support"
1391 depends on X86_32 && !HIGHMEM4G
1394 PAE is required for NX support, and furthermore enables
1395 larger swapspace support for non-overcommit purposes. It
1396 has the cost of more pagetable lookup overhead, and also
1397 consumes more pagetable space per process.
1399 config ARCH_PHYS_ADDR_T_64BIT
1401 depends on X86_64 || X86_PAE
1403 config ARCH_DMA_ADDR_T_64BIT
1405 depends on X86_64 || HIGHMEM64G
1407 config X86_DIRECT_GBPAGES
1409 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1411 Certain kernel features effectively disable kernel
1412 linear 1 GB mappings (even if the CPU otherwise
1413 supports them), so don't confuse the user by printing
1414 that we have them enabled.
1416 # Common NUMA Features
1418 bool "Numa Memory Allocation and Scheduler Support"
1420 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1421 default y if X86_BIGSMP
1423 Enable NUMA (Non Uniform Memory Access) support.
1425 The kernel will try to allocate memory used by a CPU on the
1426 local memory controller of the CPU and add some more
1427 NUMA awareness to the kernel.
1429 For 64-bit this is recommended if the system is Intel Core i7
1430 (or later), AMD Opteron, or EM64T NUMA.
1432 For 32-bit this is only needed if you boot a 32-bit
1433 kernel on a 64-bit NUMA platform.
1435 Otherwise, you should say N.
1439 prompt "Old style AMD Opteron NUMA detection"
1440 depends on X86_64 && NUMA && PCI
1442 Enable AMD NUMA node topology detection. You should say Y here if
1443 you have a multi processor AMD system. This uses an old method to
1444 read the NUMA configuration directly from the builtin Northbridge
1445 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1446 which also takes priority if both are compiled in.
1448 config X86_64_ACPI_NUMA
1450 prompt "ACPI NUMA detection"
1451 depends on X86_64 && NUMA && ACPI && PCI
1454 Enable ACPI SRAT based node topology detection.
1456 # Some NUMA nodes have memory ranges that span
1457 # other nodes. Even though a pfn is valid and
1458 # between a node's start and end pfns, it may not
1459 # reside on that node. See memmap_init_zone()
1461 config NODES_SPAN_OTHER_NODES
1463 depends on X86_64_ACPI_NUMA
1466 bool "NUMA emulation"
1469 Enable NUMA emulation. A flat machine will be split
1470 into virtual nodes when booted with "numa=fake=N", where N is the
1471 number of nodes. This is only useful for debugging.
1474 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1476 default "10" if MAXSMP
1477 default "6" if X86_64
1479 depends on NEED_MULTIPLE_NODES
1481 Specify the maximum number of NUMA Nodes available on the target
1482 system. Increases memory reserved to accommodate various tables.
1484 config ARCH_HAVE_MEMORY_PRESENT
1486 depends on X86_32 && DISCONTIGMEM
1488 config NEED_NODE_MEMMAP_SIZE
1490 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1492 config ARCH_FLATMEM_ENABLE
1494 depends on X86_32 && !NUMA
1496 config ARCH_DISCONTIGMEM_ENABLE
1498 depends on NUMA && X86_32
1500 config ARCH_DISCONTIGMEM_DEFAULT
1502 depends on NUMA && X86_32
1504 config ARCH_SPARSEMEM_ENABLE
1506 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1507 select SPARSEMEM_STATIC if X86_32
1508 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1510 config ARCH_SPARSEMEM_DEFAULT
1514 config ARCH_SELECT_MEMORY_MODEL
1516 depends on ARCH_SPARSEMEM_ENABLE
1518 config ARCH_MEMORY_PROBE
1519 bool "Enable sysfs memory/probe interface"
1520 depends on X86_64 && MEMORY_HOTPLUG
1522 This option enables a sysfs memory/probe interface for testing.
1523 See Documentation/memory-hotplug.txt for more information.
1524 If you are unsure how to answer this question, answer N.
1526 config ARCH_PROC_KCORE_TEXT
1528 depends on X86_64 && PROC_KCORE
1530 config ILLEGAL_POINTER_VALUE
1533 default 0xdead000000000000 if X86_64
1537 config X86_PMEM_LEGACY_DEVICE
1540 config X86_PMEM_LEGACY
1541 tristate "Support non-standard NVDIMMs and ADR protected memory"
1542 depends on PHYS_ADDR_T_64BIT
1544 select X86_PMEM_LEGACY_DEVICE
1547 Treat memory marked using the non-standard e820 type of 12 as used
1548 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1549 The kernel will offer these regions to the 'pmem' driver so
1550 they can be used for persistent storage.
1555 bool "Allocate 3rd-level pagetables from highmem"
1558 The VM uses one page table entry for each page of physical memory.
1559 For systems with a lot of RAM, this can be wasteful of precious
1560 low memory. Setting this option will put user-space page table
1561 entries in high memory.
1563 config X86_CHECK_BIOS_CORRUPTION
1564 bool "Check for low memory corruption"
1566 Periodically check for memory corruption in low memory, which
1567 is suspected to be caused by BIOS. Even when enabled in the
1568 configuration, it is disabled at runtime. Enable it by
1569 setting "memory_corruption_check=1" on the kernel command
1570 line. By default it scans the low 64k of memory every 60
1571 seconds; see the memory_corruption_check_size and
1572 memory_corruption_check_period parameters in
1573 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1575 When enabled with the default parameters, this option has
1576 almost no overhead, as it reserves a relatively small amount
1577 of memory and scans it infrequently. It both detects corruption
1578 and prevents it from affecting the running system.
1580 It is, however, intended as a diagnostic tool; if repeatable
1581 BIOS-originated corruption always affects the same memory,
1582 you can use memmap= to prevent the kernel from using that
1585 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1586 bool "Set the default setting of memory_corruption_check"
1587 depends on X86_CHECK_BIOS_CORRUPTION
1590 Set whether the default state of memory_corruption_check is
1593 config X86_RESERVE_LOW
1594 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1598 Specify the amount of low memory to reserve for the BIOS.
1600 The first page contains BIOS data structures that the kernel
1601 must not use, so that page must always be reserved.
1603 By default we reserve the first 64K of physical RAM, as a
1604 number of BIOSes are known to corrupt that memory range
1605 during events such as suspend/resume or monitor cable
1606 insertion, so it must not be used by the kernel.
1608 You can set this to 4 if you are absolutely sure that you
1609 trust the BIOS to get all its memory reservations and usages
1610 right. If you know your BIOS have problems beyond the
1611 default 64K area, you can set this to 640 to avoid using the
1612 entire low memory range.
1614 If you have doubts about the BIOS (e.g. suspend/resume does
1615 not work or there's kernel crashes after certain hardware
1616 hotplug events) then you might want to enable
1617 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1618 typical corruption patterns.
1620 Leave this to the default value of 64 if you are unsure.
1622 config MATH_EMULATION
1624 depends on MODIFY_LDT_SYSCALL
1625 prompt "Math emulation" if X86_32
1627 Linux can emulate a math coprocessor (used for floating point
1628 operations) if you don't have one. 486DX and Pentium processors have
1629 a math coprocessor built in, 486SX and 386 do not, unless you added
1630 a 487DX or 387, respectively. (The messages during boot time can
1631 give you some hints here ["man dmesg"].) Everyone needs either a
1632 coprocessor or this emulation.
1634 If you don't have a math coprocessor, you need to say Y here; if you
1635 say Y here even though you have a coprocessor, the coprocessor will
1636 be used nevertheless. (This behavior can be changed with the kernel
1637 command line option "no387", which comes handy if your coprocessor
1638 is broken. Try "man bootparam" or see the documentation of your boot
1639 loader (lilo or loadlin) about how to pass options to the kernel at
1640 boot time.) This means that it is a good idea to say Y here if you
1641 intend to use this kernel on different machines.
1643 More information about the internals of the Linux math coprocessor
1644 emulation can be found in <file:arch/x86/math-emu/README>.
1646 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1647 kernel, it won't hurt.
1651 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1653 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1654 the Memory Type Range Registers (MTRRs) may be used to control
1655 processor access to memory ranges. This is most useful if you have
1656 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1657 allows bus write transfers to be combined into a larger transfer
1658 before bursting over the PCI/AGP bus. This can increase performance
1659 of image write operations 2.5 times or more. Saying Y here creates a
1660 /proc/mtrr file which may be used to manipulate your processor's
1661 MTRRs. Typically the X server should use this.
1663 This code has a reasonably generic interface so that similar
1664 control registers on other processors can be easily supported
1667 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1668 Registers (ARRs) which provide a similar functionality to MTRRs. For
1669 these, the ARRs are used to emulate the MTRRs.
1670 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1671 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1672 write-combining. All of these processors are supported by this code
1673 and it makes sense to say Y here if you have one of them.
1675 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1676 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1677 can lead to all sorts of problems, so it's good to say Y here.
1679 You can safely say Y even if your machine doesn't have MTRRs, you'll
1680 just add about 9 KB to your kernel.
1682 See <file:Documentation/x86/mtrr.txt> for more information.
1684 config MTRR_SANITIZER
1686 prompt "MTRR cleanup support"
1689 Convert MTRR layout from continuous to discrete, so X drivers can
1690 add writeback entries.
1692 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1693 The largest mtrr entry size for a continuous block can be set with
1698 config MTRR_SANITIZER_ENABLE_DEFAULT
1699 int "MTRR cleanup enable value (0-1)"
1702 depends on MTRR_SANITIZER
1704 Enable mtrr cleanup default value
1706 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1707 int "MTRR cleanup spare reg num (0-7)"
1710 depends on MTRR_SANITIZER
1712 mtrr cleanup spare entries default, it can be changed via
1713 mtrr_spare_reg_nr=N on the kernel command line.
1717 prompt "x86 PAT support" if EXPERT
1720 Use PAT attributes to setup page level cache control.
1722 PATs are the modern equivalents of MTRRs and are much more
1723 flexible than MTRRs.
1725 Say N here if you see bootup problems (boot crash, boot hang,
1726 spontaneous reboots) or a non-working video driver.
1730 config ARCH_USES_PG_UNCACHED
1736 prompt "x86 architectural random number generator" if EXPERT
1738 Enable the x86 architectural RDRAND instruction
1739 (Intel Bull Mountain technology) to generate random numbers.
1740 If supported, this is a high bandwidth, cryptographically
1741 secure hardware random number generator.
1745 prompt "Supervisor Mode Access Prevention" if EXPERT
1747 Supervisor Mode Access Prevention (SMAP) is a security
1748 feature in newer Intel processors. There is a small
1749 performance cost if this enabled and turned on; there is
1750 also a small increase in the kernel size if this is enabled.
1754 config X86_INTEL_MPX
1755 prompt "Intel MPX (Memory Protection Extensions)"
1757 depends on CPU_SUP_INTEL
1759 MPX provides hardware features that can be used in
1760 conjunction with compiler-instrumented code to check
1761 memory references. It is designed to detect buffer
1762 overflow or underflow bugs.
1764 This option enables running applications which are
1765 instrumented or otherwise use MPX. It does not use MPX
1766 itself inside the kernel or to protect the kernel
1767 against bad memory references.
1769 Enabling this option will make the kernel larger:
1770 ~8k of kernel text and 36 bytes of data on a 64-bit
1771 defconfig. It adds a long to the 'mm_struct' which
1772 will increase the kernel memory overhead of each
1773 process and adds some branches to paths used during
1774 exec() and munmap().
1776 For details, see Documentation/x86/intel_mpx.txt
1780 config X86_INTEL_MEMORY_PROTECTION_KEYS
1781 prompt "Intel Memory Protection Keys"
1783 # Note: only available in 64-bit mode
1784 depends on CPU_SUP_INTEL && X86_64
1785 select ARCH_USES_HIGH_VMA_FLAGS
1786 select ARCH_HAS_PKEYS
1788 Memory Protection Keys provides a mechanism for enforcing
1789 page-based protections, but without requiring modification of the
1790 page tables when an application changes protection domains.
1792 For details, see Documentation/x86/protection-keys.txt
1797 bool "EFI runtime service support"
1800 select EFI_RUNTIME_WRAPPERS
1802 This enables the kernel to use EFI runtime services that are
1803 available (such as the EFI variable services).
1805 This option is only useful on systems that have EFI firmware.
1806 In addition, you should use the latest ELILO loader available
1807 at <http://elilo.sourceforge.net> in order to take advantage
1808 of EFI runtime services. However, even with this option, the
1809 resultant kernel should continue to boot on existing non-EFI
1813 bool "EFI stub support"
1814 depends on EFI && !X86_USE_3DNOW
1817 This kernel feature allows a bzImage to be loaded directly
1818 by EFI firmware without the use of a bootloader.
1820 See Documentation/efi-stub.txt for more information.
1823 bool "EFI mixed-mode support"
1824 depends on EFI_STUB && X86_64
1826 Enabling this feature allows a 64-bit kernel to be booted
1827 on a 32-bit firmware, provided that your CPU supports 64-bit
1830 Note that it is not possible to boot a mixed-mode enabled
1831 kernel via the EFI boot stub - a bootloader that supports
1832 the EFI handover protocol must be used.
1838 prompt "Enable seccomp to safely compute untrusted bytecode"
1840 This kernel feature is useful for number crunching applications
1841 that may need to compute untrusted bytecode during their
1842 execution. By using pipes or other transports made available to
1843 the process as file descriptors supporting the read/write
1844 syscalls, it's possible to isolate those applications in
1845 their own address space using seccomp. Once seccomp is
1846 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1847 and the task is only allowed to execute a few safe syscalls
1848 defined by each seccomp mode.
1850 If unsure, say Y. Only embedded should say N here.
1852 source kernel/Kconfig.hz
1855 bool "kexec system call"
1858 kexec is a system call that implements the ability to shutdown your
1859 current kernel, and to start another kernel. It is like a reboot
1860 but it is independent of the system firmware. And like a reboot
1861 you can start any kernel with it, not just Linux.
1863 The name comes from the similarity to the exec system call.
1865 It is an ongoing process to be certain the hardware in a machine
1866 is properly shutdown, so do not be surprised if this code does not
1867 initially work for you. As of this writing the exact hardware
1868 interface is strongly in flux, so no good recommendation can be
1872 bool "kexec file based system call"
1877 depends on CRYPTO_SHA256=y
1879 This is new version of kexec system call. This system call is
1880 file based and takes file descriptors as system call argument
1881 for kernel and initramfs as opposed to list of segments as
1882 accepted by previous system call.
1884 config KEXEC_VERIFY_SIG
1885 bool "Verify kernel signature during kexec_file_load() syscall"
1886 depends on KEXEC_FILE
1888 This option makes kernel signature verification mandatory for
1889 the kexec_file_load() syscall.
1891 In addition to that option, you need to enable signature
1892 verification for the corresponding kernel image type being
1893 loaded in order for this to work.
1895 config KEXEC_BZIMAGE_VERIFY_SIG
1896 bool "Enable bzImage signature verification support"
1897 depends on KEXEC_VERIFY_SIG
1898 depends on SIGNED_PE_FILE_VERIFICATION
1899 select SYSTEM_TRUSTED_KEYRING
1901 Enable bzImage signature verification support.
1904 bool "kernel crash dumps"
1905 depends on X86_64 || (X86_32 && HIGHMEM)
1907 Generate crash dump after being started by kexec.
1908 This should be normally only set in special crash dump kernels
1909 which are loaded in the main kernel with kexec-tools into
1910 a specially reserved region and then later executed after
1911 a crash by kdump/kexec. The crash dump kernel must be compiled
1912 to a memory address not used by the main kernel or BIOS using
1913 PHYSICAL_START, or it must be built as a relocatable image
1914 (CONFIG_RELOCATABLE=y).
1915 For more details see Documentation/kdump/kdump.txt
1919 depends on KEXEC && HIBERNATION
1921 Jump between original kernel and kexeced kernel and invoke
1922 code in physical address mode via KEXEC
1924 config PHYSICAL_START
1925 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1928 This gives the physical address where the kernel is loaded.
1930 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1931 bzImage will decompress itself to above physical address and
1932 run from there. Otherwise, bzImage will run from the address where
1933 it has been loaded by the boot loader and will ignore above physical
1936 In normal kdump cases one does not have to set/change this option
1937 as now bzImage can be compiled as a completely relocatable image
1938 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1939 address. This option is mainly useful for the folks who don't want
1940 to use a bzImage for capturing the crash dump and want to use a
1941 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1942 to be specifically compiled to run from a specific memory area
1943 (normally a reserved region) and this option comes handy.
1945 So if you are using bzImage for capturing the crash dump,
1946 leave the value here unchanged to 0x1000000 and set
1947 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1948 for capturing the crash dump change this value to start of
1949 the reserved region. In other words, it can be set based on
1950 the "X" value as specified in the "crashkernel=YM@XM"
1951 command line boot parameter passed to the panic-ed
1952 kernel. Please take a look at Documentation/kdump/kdump.txt
1953 for more details about crash dumps.
1955 Usage of bzImage for capturing the crash dump is recommended as
1956 one does not have to build two kernels. Same kernel can be used
1957 as production kernel and capture kernel. Above option should have
1958 gone away after relocatable bzImage support is introduced. But it
1959 is present because there are users out there who continue to use
1960 vmlinux for dump capture. This option should go away down the
1963 Don't change this unless you know what you are doing.
1966 bool "Build a relocatable kernel"
1969 This builds a kernel image that retains relocation information
1970 so it can be loaded someplace besides the default 1MB.
1971 The relocations tend to make the kernel binary about 10% larger,
1972 but are discarded at runtime.
1974 One use is for the kexec on panic case where the recovery kernel
1975 must live at a different physical address than the primary
1978 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1979 it has been loaded at and the compile time physical address
1980 (CONFIG_PHYSICAL_START) is used as the minimum location.
1982 config RANDOMIZE_BASE
1983 bool "Randomize the address of the kernel image (KASLR)"
1984 depends on RELOCATABLE
1987 In support of Kernel Address Space Layout Randomization (KASLR),
1988 this randomizes the physical address at which the kernel image
1989 is decompressed and the virtual address where the kernel
1990 image is mapped, as a security feature that deters exploit
1991 attempts relying on knowledge of the location of kernel
1994 On 64-bit, the kernel physical and virtual addresses are
1995 randomized separately. The physical address will be anywhere
1996 between 16MB and the top of physical memory (up to 64TB). The
1997 virtual address will be randomized from 16MB up to 1GB (9 bits
1998 of entropy). Note that this also reduces the memory space
1999 available to kernel modules from 1.5GB to 1GB.
2001 On 32-bit, the kernel physical and virtual addresses are
2002 randomized together. They will be randomized from 16MB up to
2003 512MB (8 bits of entropy).
2005 Entropy is generated using the RDRAND instruction if it is
2006 supported. If RDTSC is supported, its value is mixed into
2007 the entropy pool as well. If neither RDRAND nor RDTSC are
2008 supported, then entropy is read from the i8254 timer. The
2009 usable entropy is limited by the kernel being built using
2010 2GB addressing, and that PHYSICAL_ALIGN must be at a
2011 minimum of 2MB. As a result, only 10 bits of entropy are
2012 theoretically possible, but the implementations are further
2013 limited due to memory layouts.
2017 # Relocation on x86 needs some additional build support
2018 config X86_NEED_RELOCS
2020 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2022 config PHYSICAL_ALIGN
2023 hex "Alignment value to which kernel should be aligned"
2025 range 0x2000 0x1000000 if X86_32
2026 range 0x200000 0x1000000 if X86_64
2028 This value puts the alignment restrictions on physical address
2029 where kernel is loaded and run from. Kernel is compiled for an
2030 address which meets above alignment restriction.
2032 If bootloader loads the kernel at a non-aligned address and
2033 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2034 address aligned to above value and run from there.
2036 If bootloader loads the kernel at a non-aligned address and
2037 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2038 load address and decompress itself to the address it has been
2039 compiled for and run from there. The address for which kernel is
2040 compiled already meets above alignment restrictions. Hence the
2041 end result is that kernel runs from a physical address meeting
2042 above alignment restrictions.
2044 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2045 this value must be a multiple of 0x200000.
2047 Don't change this unless you know what you are doing.
2049 config RANDOMIZE_MEMORY
2050 bool "Randomize the kernel memory sections"
2052 depends on RANDOMIZE_BASE
2053 default RANDOMIZE_BASE
2055 Randomizes the base virtual address of kernel memory sections
2056 (physical memory mapping, vmalloc & vmemmap). This security feature
2057 makes exploits relying on predictable memory locations less reliable.
2059 The order of allocations remains unchanged. Entropy is generated in
2060 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2061 configuration have in average 30,000 different possible virtual
2062 addresses for each memory section.
2066 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2067 hex "Physical memory mapping padding" if EXPERT
2068 depends on RANDOMIZE_MEMORY
2069 default "0xa" if MEMORY_HOTPLUG
2071 range 0x1 0x40 if MEMORY_HOTPLUG
2074 Define the padding in terabytes added to the existing physical
2075 memory size during kernel memory randomization. It is useful
2076 for memory hotplug support but reduces the entropy available for
2077 address randomization.
2079 If unsure, leave at the default value.
2082 bool "Support for hot-pluggable CPUs"
2085 Say Y here to allow turning CPUs off and on. CPUs can be
2086 controlled through /sys/devices/system/cpu.
2087 ( Note: power management support will enable this option
2088 automatically on SMP systems. )
2089 Say N if you want to disable CPU hotplug.
2091 config BOOTPARAM_HOTPLUG_CPU0
2092 bool "Set default setting of cpu0_hotpluggable"
2094 depends on HOTPLUG_CPU
2096 Set whether default state of cpu0_hotpluggable is on or off.
2098 Say Y here to enable CPU0 hotplug by default. If this switch
2099 is turned on, there is no need to give cpu0_hotplug kernel
2100 parameter and the CPU0 hotplug feature is enabled by default.
2102 Please note: there are two known CPU0 dependencies if you want
2103 to enable the CPU0 hotplug feature either by this switch or by
2104 cpu0_hotplug kernel parameter.
2106 First, resume from hibernate or suspend always starts from CPU0.
2107 So hibernate and suspend are prevented if CPU0 is offline.
2109 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2110 offline if any interrupt can not migrate out of CPU0. There may
2111 be other CPU0 dependencies.
2113 Please make sure the dependencies are under your control before
2114 you enable this feature.
2116 Say N if you don't want to enable CPU0 hotplug feature by default.
2117 You still can enable the CPU0 hotplug feature at boot by kernel
2118 parameter cpu0_hotplug.
2120 config DEBUG_HOTPLUG_CPU0
2122 prompt "Debug CPU0 hotplug"
2123 depends on HOTPLUG_CPU
2125 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2126 soon as possible and boots up userspace with CPU0 offlined. User
2127 can online CPU0 back after boot time.
2129 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2130 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2131 compilation or giving cpu0_hotplug kernel parameter at boot.
2137 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2138 depends on COMPAT_32
2140 Certain buggy versions of glibc will crash if they are
2141 presented with a 32-bit vDSO that is not mapped at the address
2142 indicated in its segment table.
2144 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2145 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2146 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2147 the only released version with the bug, but OpenSUSE 9
2148 contains a buggy "glibc 2.3.2".
2150 The symptom of the bug is that everything crashes on startup, saying:
2151 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2153 Saying Y here changes the default value of the vdso32 boot
2154 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2155 This works around the glibc bug but hurts performance.
2157 If unsure, say N: if you are compiling your own kernel, you
2158 are unlikely to be using a buggy version of glibc.
2161 prompt "vsyscall table for legacy applications"
2163 default LEGACY_VSYSCALL_EMULATE
2165 Legacy user code that does not know how to find the vDSO expects
2166 to be able to issue three syscalls by calling fixed addresses in
2167 kernel space. Since this location is not randomized with ASLR,
2168 it can be used to assist security vulnerability exploitation.
2170 This setting can be changed at boot time via the kernel command
2171 line parameter vsyscall=[native|emulate|none].
2173 On a system with recent enough glibc (2.14 or newer) and no
2174 static binaries, you can say None without a performance penalty
2175 to improve security.
2177 If unsure, select "Emulate".
2179 config LEGACY_VSYSCALL_NATIVE
2182 Actual executable code is located in the fixed vsyscall
2183 address mapping, implementing time() efficiently. Since
2184 this makes the mapping executable, it can be used during
2185 security vulnerability exploitation (traditionally as
2186 ROP gadgets). This configuration is not recommended.
2188 config LEGACY_VSYSCALL_EMULATE
2191 The kernel traps and emulates calls into the fixed
2192 vsyscall address mapping. This makes the mapping
2193 non-executable, but it still contains known contents,
2194 which could be used in certain rare security vulnerability
2195 exploits. This configuration is recommended when userspace
2196 still uses the vsyscall area.
2198 config LEGACY_VSYSCALL_NONE
2201 There will be no vsyscall mapping at all. This will
2202 eliminate any risk of ASLR bypass due to the vsyscall
2203 fixed address mapping. Attempts to use the vsyscalls
2204 will be reported to dmesg, so that either old or
2205 malicious userspace programs can be identified.
2210 bool "Built-in kernel command line"
2212 Allow for specifying boot arguments to the kernel at
2213 build time. On some systems (e.g. embedded ones), it is
2214 necessary or convenient to provide some or all of the
2215 kernel boot arguments with the kernel itself (that is,
2216 to not rely on the boot loader to provide them.)
2218 To compile command line arguments into the kernel,
2219 set this option to 'Y', then fill in the
2220 boot arguments in CONFIG_CMDLINE.
2222 Systems with fully functional boot loaders (i.e. non-embedded)
2223 should leave this option set to 'N'.
2226 string "Built-in kernel command string"
2227 depends on CMDLINE_BOOL
2230 Enter arguments here that should be compiled into the kernel
2231 image and used at boot time. If the boot loader provides a
2232 command line at boot time, it is appended to this string to
2233 form the full kernel command line, when the system boots.
2235 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2236 change this behavior.
2238 In most cases, the command line (whether built-in or provided
2239 by the boot loader) should specify the device for the root
2242 config CMDLINE_OVERRIDE
2243 bool "Built-in command line overrides boot loader arguments"
2244 depends on CMDLINE_BOOL
2246 Set this option to 'Y' to have the kernel ignore the boot loader
2247 command line, and use ONLY the built-in command line.
2249 This is used to work around broken boot loaders. This should
2250 be set to 'N' under normal conditions.
2252 config MODIFY_LDT_SYSCALL
2253 bool "Enable the LDT (local descriptor table)" if EXPERT
2256 Linux can allow user programs to install a per-process x86
2257 Local Descriptor Table (LDT) using the modify_ldt(2) system
2258 call. This is required to run 16-bit or segmented code such as
2259 DOSEMU or some Wine programs. It is also used by some very old
2260 threading libraries.
2262 Enabling this feature adds a small amount of overhead to
2263 context switches and increases the low-level kernel attack
2264 surface. Disabling it removes the modify_ldt(2) system call.
2266 Saying 'N' here may make sense for embedded or server kernels.
2268 source "kernel/livepatch/Kconfig"
2272 config ARCH_ENABLE_MEMORY_HOTPLUG
2274 depends on X86_64 || (X86_32 && HIGHMEM)
2276 config ARCH_ENABLE_MEMORY_HOTREMOVE
2278 depends on MEMORY_HOTPLUG
2280 config USE_PERCPU_NUMA_NODE_ID
2284 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2286 depends on X86_64 || X86_PAE
2288 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2290 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2292 menu "Power management and ACPI options"
2294 config ARCH_HIBERNATION_HEADER
2296 depends on X86_64 && HIBERNATION
2298 source "kernel/power/Kconfig"
2300 source "drivers/acpi/Kconfig"
2302 source "drivers/sfi/Kconfig"
2309 tristate "APM (Advanced Power Management) BIOS support"
2310 depends on X86_32 && PM_SLEEP
2312 APM is a BIOS specification for saving power using several different
2313 techniques. This is mostly useful for battery powered laptops with
2314 APM compliant BIOSes. If you say Y here, the system time will be
2315 reset after a RESUME operation, the /proc/apm device will provide
2316 battery status information, and user-space programs will receive
2317 notification of APM "events" (e.g. battery status change).
2319 If you select "Y" here, you can disable actual use of the APM
2320 BIOS by passing the "apm=off" option to the kernel at boot time.
2322 Note that the APM support is almost completely disabled for
2323 machines with more than one CPU.
2325 In order to use APM, you will need supporting software. For location
2326 and more information, read <file:Documentation/power/apm-acpi.txt>
2327 and the Battery Powered Linux mini-HOWTO, available from
2328 <http://www.tldp.org/docs.html#howto>.
2330 This driver does not spin down disk drives (see the hdparm(8)
2331 manpage ("man 8 hdparm") for that), and it doesn't turn off
2332 VESA-compliant "green" monitors.
2334 This driver does not support the TI 4000M TravelMate and the ACER
2335 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2336 desktop machines also don't have compliant BIOSes, and this driver
2337 may cause those machines to panic during the boot phase.
2339 Generally, if you don't have a battery in your machine, there isn't
2340 much point in using this driver and you should say N. If you get
2341 random kernel OOPSes or reboots that don't seem to be related to
2342 anything, try disabling/enabling this option (or disabling/enabling
2345 Some other things you should try when experiencing seemingly random,
2348 1) make sure that you have enough swap space and that it is
2350 2) pass the "no-hlt" option to the kernel
2351 3) switch on floating point emulation in the kernel and pass
2352 the "no387" option to the kernel
2353 4) pass the "floppy=nodma" option to the kernel
2354 5) pass the "mem=4M" option to the kernel (thereby disabling
2355 all but the first 4 MB of RAM)
2356 6) make sure that the CPU is not over clocked.
2357 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2358 8) disable the cache from your BIOS settings
2359 9) install a fan for the video card or exchange video RAM
2360 10) install a better fan for the CPU
2361 11) exchange RAM chips
2362 12) exchange the motherboard.
2364 To compile this driver as a module, choose M here: the
2365 module will be called apm.
2369 config APM_IGNORE_USER_SUSPEND
2370 bool "Ignore USER SUSPEND"
2372 This option will ignore USER SUSPEND requests. On machines with a
2373 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2374 series notebooks, it is necessary to say Y because of a BIOS bug.
2376 config APM_DO_ENABLE
2377 bool "Enable PM at boot time"
2379 Enable APM features at boot time. From page 36 of the APM BIOS
2380 specification: "When disabled, the APM BIOS does not automatically
2381 power manage devices, enter the Standby State, enter the Suspend
2382 State, or take power saving steps in response to CPU Idle calls."
2383 This driver will make CPU Idle calls when Linux is idle (unless this
2384 feature is turned off -- see "Do CPU IDLE calls", below). This
2385 should always save battery power, but more complicated APM features
2386 will be dependent on your BIOS implementation. You may need to turn
2387 this option off if your computer hangs at boot time when using APM
2388 support, or if it beeps continuously instead of suspending. Turn
2389 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2390 T400CDT. This is off by default since most machines do fine without
2395 bool "Make CPU Idle calls when idle"
2397 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2398 On some machines, this can activate improved power savings, such as
2399 a slowed CPU clock rate, when the machine is idle. These idle calls
2400 are made after the idle loop has run for some length of time (e.g.,
2401 333 mS). On some machines, this will cause a hang at boot time or
2402 whenever the CPU becomes idle. (On machines with more than one CPU,
2403 this option does nothing.)
2405 config APM_DISPLAY_BLANK
2406 bool "Enable console blanking using APM"
2408 Enable console blanking using the APM. Some laptops can use this to
2409 turn off the LCD backlight when the screen blanker of the Linux
2410 virtual console blanks the screen. Note that this is only used by
2411 the virtual console screen blanker, and won't turn off the backlight
2412 when using the X Window system. This also doesn't have anything to
2413 do with your VESA-compliant power-saving monitor. Further, this
2414 option doesn't work for all laptops -- it might not turn off your
2415 backlight at all, or it might print a lot of errors to the console,
2416 especially if you are using gpm.
2418 config APM_ALLOW_INTS
2419 bool "Allow interrupts during APM BIOS calls"
2421 Normally we disable external interrupts while we are making calls to
2422 the APM BIOS as a measure to lessen the effects of a badly behaving
2423 BIOS implementation. The BIOS should reenable interrupts if it
2424 needs to. Unfortunately, some BIOSes do not -- especially those in
2425 many of the newer IBM Thinkpads. If you experience hangs when you
2426 suspend, try setting this to Y. Otherwise, say N.
2430 source "drivers/cpufreq/Kconfig"
2432 source "drivers/cpuidle/Kconfig"
2434 source "drivers/idle/Kconfig"
2439 menu "Bus options (PCI etc.)"
2445 Find out whether you have a PCI motherboard. PCI is the name of a
2446 bus system, i.e. the way the CPU talks to the other stuff inside
2447 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2448 VESA. If you have PCI, say Y, otherwise N.
2451 prompt "PCI access mode"
2452 depends on X86_32 && PCI
2455 On PCI systems, the BIOS can be used to detect the PCI devices and
2456 determine their configuration. However, some old PCI motherboards
2457 have BIOS bugs and may crash if this is done. Also, some embedded
2458 PCI-based systems don't have any BIOS at all. Linux can also try to
2459 detect the PCI hardware directly without using the BIOS.
2461 With this option, you can specify how Linux should detect the
2462 PCI devices. If you choose "BIOS", the BIOS will be used,
2463 if you choose "Direct", the BIOS won't be used, and if you
2464 choose "MMConfig", then PCI Express MMCONFIG will be used.
2465 If you choose "Any", the kernel will try MMCONFIG, then the
2466 direct access method and falls back to the BIOS if that doesn't
2467 work. If unsure, go with the default, which is "Any".
2472 config PCI_GOMMCONFIG
2489 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2491 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2494 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2498 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2502 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2506 depends on PCI && XEN
2514 bool "Support mmconfig PCI config space access"
2515 depends on X86_64 && PCI && ACPI
2517 config PCI_CNB20LE_QUIRK
2518 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2521 Read the PCI windows out of the CNB20LE host bridge. This allows
2522 PCI hotplug to work on systems with the CNB20LE chipset which do
2525 There's no public spec for this chipset, and this functionality
2526 is known to be incomplete.
2528 You should say N unless you know you need this.
2530 source "drivers/pci/Kconfig"
2533 bool "ISA-style bus support on modern systems" if EXPERT
2536 Enables ISA-style drivers on modern systems. This is necessary to
2537 support PC/104 devices on X86_64 platforms.
2541 # x86_64 have no ISA slots, but can have ISA-style DMA.
2543 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2546 Enables ISA-style DMA support for devices requiring such controllers.
2554 Find out whether you have ISA slots on your motherboard. ISA is the
2555 name of a bus system, i.e. the way the CPU talks to the other stuff
2556 inside your box. Other bus systems are PCI, EISA, MicroChannel
2557 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2558 newer boards don't support it. If you have ISA, say Y, otherwise N.
2564 The Extended Industry Standard Architecture (EISA) bus was
2565 developed as an open alternative to the IBM MicroChannel bus.
2567 The EISA bus provided some of the features of the IBM MicroChannel
2568 bus while maintaining backward compatibility with cards made for
2569 the older ISA bus. The EISA bus saw limited use between 1988 and
2570 1995 when it was made obsolete by the PCI bus.
2572 Say Y here if you are building a kernel for an EISA-based machine.
2576 source "drivers/eisa/Kconfig"
2579 tristate "NatSemi SCx200 support"
2581 This provides basic support for National Semiconductor's
2582 (now AMD's) Geode processors. The driver probes for the
2583 PCI-IDs of several on-chip devices, so its a good dependency
2584 for other scx200_* drivers.
2586 If compiled as a module, the driver is named scx200.
2588 config SCx200HR_TIMER
2589 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2593 This driver provides a clocksource built upon the on-chip
2594 27MHz high-resolution timer. Its also a workaround for
2595 NSC Geode SC-1100's buggy TSC, which loses time when the
2596 processor goes idle (as is done by the scheduler). The
2597 other workaround is idle=poll boot option.
2600 bool "One Laptop Per Child support"
2607 Add support for detecting the unique features of the OLPC
2611 bool "OLPC XO-1 Power Management"
2612 depends on OLPC && MFD_CS5535 && PM_SLEEP
2615 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2618 bool "OLPC XO-1 Real Time Clock"
2619 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2621 Add support for the XO-1 real time clock, which can be used as a
2622 programmable wakeup source.
2625 bool "OLPC XO-1 SCI extras"
2626 depends on OLPC && OLPC_XO1_PM
2632 Add support for SCI-based features of the OLPC XO-1 laptop:
2633 - EC-driven system wakeups
2637 - AC adapter status updates
2638 - Battery status updates
2640 config OLPC_XO15_SCI
2641 bool "OLPC XO-1.5 SCI extras"
2642 depends on OLPC && ACPI
2645 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2646 - EC-driven system wakeups
2647 - AC adapter status updates
2648 - Battery status updates
2651 bool "PCEngines ALIX System Support (LED setup)"
2654 This option enables system support for the PCEngines ALIX.
2655 At present this just sets up LEDs for GPIO control on
2656 ALIX2/3/6 boards. However, other system specific setup should
2659 Note: You must still enable the drivers for GPIO and LED support
2660 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2662 Note: You have to set alix.force=1 for boards with Award BIOS.
2665 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2668 This option enables system support for the Soekris Engineering net5501.
2671 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2675 This option enables system support for the Traverse Technologies GEOS.
2678 bool "Technologic Systems TS-5500 platform support"
2680 select CHECK_SIGNATURE
2684 This option enables system support for the Technologic Systems TS-5500.
2690 depends on CPU_SUP_AMD && PCI
2692 source "drivers/pcmcia/Kconfig"
2695 tristate "RapidIO support"
2699 If enabled this option will include drivers and the core
2700 infrastructure code to support RapidIO interconnect devices.
2702 source "drivers/rapidio/Kconfig"
2705 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2707 Firmwares often provide initial graphics framebuffers so the BIOS,
2708 bootloader or kernel can show basic video-output during boot for
2709 user-guidance and debugging. Historically, x86 used the VESA BIOS
2710 Extensions and EFI-framebuffers for this, which are mostly limited
2712 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2713 framebuffers so the new generic system-framebuffer drivers can be
2714 used on x86. If the framebuffer is not compatible with the generic
2715 modes, it is adverticed as fallback platform framebuffer so legacy
2716 drivers like efifb, vesafb and uvesafb can pick it up.
2717 If this option is not selected, all system framebuffers are always
2718 marked as fallback platform framebuffers as usual.
2720 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2721 not be able to pick up generic system framebuffers if this option
2722 is selected. You are highly encouraged to enable simplefb as
2723 replacement if you select this option. simplefb can correctly deal
2724 with generic system framebuffers. But you should still keep vesafb
2725 and others enabled as fallback if a system framebuffer is
2726 incompatible with simplefb.
2733 menu "Executable file formats / Emulations"
2735 source "fs/Kconfig.binfmt"
2737 config IA32_EMULATION
2738 bool "IA32 Emulation"
2740 select ARCH_WANT_OLD_COMPAT_IPC
2742 select COMPAT_BINFMT_ELF
2743 select COMPAT_OLD_SIGACTION
2745 Include code to run legacy 32-bit programs under a
2746 64-bit kernel. You should likely turn this on, unless you're
2747 100% sure that you don't have any 32-bit programs left.
2750 tristate "IA32 a.out support"
2751 depends on IA32_EMULATION
2753 Support old a.out binaries in the 32bit emulation.
2756 bool "x32 ABI for 64-bit mode"
2759 Include code to run binaries for the x32 native 32-bit ABI
2760 for 64-bit processors. An x32 process gets access to the
2761 full 64-bit register file and wide data path while leaving
2762 pointers at 32 bits for smaller memory footprint.
2764 You will need a recent binutils (2.22 or later) with
2765 elf32_x86_64 support enabled to compile a kernel with this
2770 depends on IA32_EMULATION || X86_32
2772 select OLD_SIGSUSPEND3
2776 depends on IA32_EMULATION || X86_X32
2779 config COMPAT_FOR_U64_ALIGNMENT
2782 config SYSVIPC_COMPAT
2790 config HAVE_ATOMIC_IOMAP
2794 config X86_DEV_DMA_OPS
2796 depends on X86_64 || STA2X11
2798 config X86_DMA_REMAP
2802 config HAVE_GENERIC_GUP
2805 source "net/Kconfig"
2807 source "drivers/Kconfig"
2809 source "drivers/firmware/Kconfig"
2813 source "arch/x86/Kconfig.debug"
2815 source "security/Kconfig"
2817 source "crypto/Kconfig"
2819 source "arch/x86/kvm/Kconfig"
2821 source "lib/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob