3 bool "64-bit kernel" if ARCH = "x86"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
20 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
21 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
23 select ARCH_CLOCKSOURCE_DATA
24 select ARCH_DISCARD_MEMBLOCK
25 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
26 select ARCH_HAS_DEVMEM_IS_ALLOWED
27 select ARCH_HAS_ELF_RANDOMIZE
28 select ARCH_HAS_FAST_MULTIPLIER
29 select ARCH_HAS_GCOV_PROFILE_ALL
30 select ARCH_HAS_GIGANTIC_PAGE if X86_64
31 select ARCH_HAS_KCOV if X86_64
32 select ARCH_HAS_PMEM_API if X86_64
33 select ARCH_HAS_MMIO_FLUSH
34 select ARCH_HAS_SG_CHAIN
35 select ARCH_HAS_UBSAN_SANITIZE_ALL
36 select ARCH_HAVE_NMI_SAFE_CMPXCHG
37 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
38 select ARCH_MIGHT_HAVE_PC_PARPORT
39 select ARCH_MIGHT_HAVE_PC_SERIO
40 select ARCH_SUPPORTS_ATOMIC_RMW
41 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
42 select ARCH_SUPPORTS_INT128 if X86_64
43 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
44 select ARCH_USE_BUILTIN_BSWAP
45 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
46 select ARCH_USE_QUEUED_RWLOCKS
47 select ARCH_USE_QUEUED_SPINLOCKS
48 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
49 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
50 select ARCH_WANT_FRAME_POINTERS
51 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
52 select BUILDTIME_EXTABLE_SORT
54 select CLKSRC_I8253 if X86_32
55 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
56 select CLOCKSOURCE_WATCHDOG
57 select CLONE_BACKWARDS if X86_32
58 select COMPAT_OLD_SIGACTION if IA32_EMULATION
59 select DCACHE_WORD_ACCESS
60 select EDAC_ATOMIC_SCRUB
62 select GENERIC_CLOCKEVENTS
63 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
64 select GENERIC_CLOCKEVENTS_MIN_ADJUST
65 select GENERIC_CMOS_UPDATE
66 select GENERIC_CPU_AUTOPROBE
67 select GENERIC_CPU_VULNERABILITIES
68 select GENERIC_EARLY_IOREMAP
69 select GENERIC_FIND_FIRST_BIT
71 select GENERIC_IRQ_PROBE
72 select GENERIC_IRQ_SHOW
73 select GENERIC_PENDING_IRQ if SMP
74 select GENERIC_SMP_IDLE_THREAD
75 select GENERIC_STRNCPY_FROM_USER
76 select GENERIC_STRNLEN_USER
77 select GENERIC_TIME_VSYSCALL
78 select HAVE_ACPI_APEI if ACPI
79 select HAVE_ACPI_APEI_NMI if ACPI
80 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
81 select HAVE_AOUT if X86_32
82 select HAVE_ARCH_AUDITSYSCALL
83 select HAVE_ARCH_HARDENED_USERCOPY
84 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
85 select HAVE_ARCH_JUMP_LABEL
86 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
88 select HAVE_ARCH_KMEMCHECK
89 select HAVE_ARCH_MMAP_RND_BITS if MMU
90 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
91 select HAVE_ARCH_SECCOMP_FILTER
92 select HAVE_ARCH_SOFT_DIRTY if X86_64
93 select HAVE_ARCH_TRACEHOOK
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
95 select HAVE_ARCH_WITHIN_STACK_FRAMES
96 select HAVE_EBPF_JIT if X86_64
97 select HAVE_ARCH_VMAP_STACK if X86_64
98 select HAVE_CC_STACKPROTECTOR
99 select HAVE_CMPXCHG_DOUBLE
100 select HAVE_CMPXCHG_LOCAL
101 select HAVE_CONTEXT_TRACKING if X86_64
102 select HAVE_COPY_THREAD_TLS
103 select HAVE_C_RECORDMCOUNT
104 select HAVE_DEBUG_KMEMLEAK
105 select HAVE_DEBUG_STACKOVERFLOW
106 select HAVE_DMA_API_DEBUG
107 select HAVE_DMA_CONTIGUOUS
108 select HAVE_DYNAMIC_FTRACE
109 select HAVE_DYNAMIC_FTRACE_WITH_REGS
110 select HAVE_EFFICIENT_UNALIGNED_ACCESS
111 select HAVE_EXIT_THREAD
112 select HAVE_FENTRY if X86_64
113 select HAVE_FTRACE_MCOUNT_RECORD
114 select HAVE_FUNCTION_GRAPH_TRACER
115 select HAVE_FUNCTION_TRACER
116 select HAVE_GCC_PLUGINS
117 select HAVE_GENERIC_DMA_COHERENT if X86_32
118 select HAVE_HW_BREAKPOINT
120 select HAVE_IOREMAP_PROT
121 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
122 select HAVE_IRQ_TIME_ACCOUNTING
123 select HAVE_KERNEL_BZIP2
124 select HAVE_KERNEL_GZIP
125 select HAVE_KERNEL_LZ4
126 select HAVE_KERNEL_LZMA
127 select HAVE_KERNEL_LZO
128 select HAVE_KERNEL_XZ
130 select HAVE_KPROBES_ON_FTRACE
131 select HAVE_KRETPROBES
133 select HAVE_LIVEPATCH if X86_64
135 select HAVE_MEMBLOCK_NODE_MAP
136 select HAVE_MIXED_BREAKPOINTS_REGS
139 select HAVE_OPTPROBES
140 select HAVE_PCSPKR_PLATFORM
141 select HAVE_PERF_EVENTS
142 select HAVE_PERF_EVENTS_NMI
143 select HAVE_PERF_REGS
144 select HAVE_PERF_USER_STACK_DUMP
145 select HAVE_REGS_AND_STACK_ACCESS_API
146 select HAVE_SYSCALL_TRACEPOINTS
147 select HAVE_UID16 if X86_32 || IA32_EMULATION
148 select HAVE_UNSTABLE_SCHED_CLOCK
149 select HAVE_USER_RETURN_NOTIFIER
150 select HOTPLUG_SMT if SMP
151 select IRQ_FORCED_THREADING
152 select MODULES_USE_ELF_RELA if X86_64
153 select MODULES_USE_ELF_REL if X86_32
154 select OLD_SIGACTION if X86_32
155 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
158 select RTC_MC146818_LIB
161 select SYSCTL_EXCEPTION_TRACE
162 select THREAD_INFO_IN_TASK
163 select USER_STACKTRACE_SUPPORT
165 select X86_DEV_DMA_OPS if X86_64
166 select X86_FEATURE_NAMES if PROC_FS
167 select HAVE_STACK_VALIDATION if X86_64
168 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
169 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
171 config INSTRUCTION_DECODER
173 depends on KPROBES || PERF_EVENTS || UPROBES
177 default "elf32-i386" if X86_32
178 default "elf64-x86-64" if X86_64
180 config ARCH_DEFCONFIG
182 default "arch/x86/configs/i386_defconfig" if X86_32
183 default "arch/x86/configs/x86_64_defconfig" if X86_64
185 config LOCKDEP_SUPPORT
188 config STACKTRACE_SUPPORT
194 config ARCH_MMAP_RND_BITS_MIN
198 config ARCH_MMAP_RND_BITS_MAX
202 config ARCH_MMAP_RND_COMPAT_BITS_MIN
205 config ARCH_MMAP_RND_COMPAT_BITS_MAX
211 config NEED_DMA_MAP_STATE
213 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
215 config NEED_SG_DMA_LENGTH
218 config GENERIC_ISA_DMA
220 depends on ISA_DMA_API
225 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
227 config GENERIC_BUG_RELATIVE_POINTERS
230 config GENERIC_HWEIGHT
233 config ARCH_MAY_HAVE_PC_FDC
235 depends on ISA_DMA_API
237 config RWSEM_XCHGADD_ALGORITHM
240 config GENERIC_CALIBRATE_DELAY
243 config ARCH_HAS_CPU_RELAX
246 config ARCH_HAS_CACHE_LINE_SIZE
249 config HAVE_SETUP_PER_CPU_AREA
252 config NEED_PER_CPU_EMBED_FIRST_CHUNK
255 config NEED_PER_CPU_PAGE_FIRST_CHUNK
258 config ARCH_HIBERNATION_POSSIBLE
261 config ARCH_SUSPEND_POSSIBLE
264 config ARCH_WANT_HUGE_PMD_SHARE
267 config ARCH_WANT_GENERAL_HUGETLB
276 config ARCH_SUPPORTS_OPTIMIZED_INLINING
279 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
282 config KASAN_SHADOW_OFFSET
285 default 0xdffffc0000000000
287 config HAVE_INTEL_TXT
289 depends on INTEL_IOMMU && ACPI
293 depends on X86_32 && SMP
297 depends on X86_64 && SMP
299 config X86_32_LAZY_GS
301 depends on X86_32 && !CC_STACKPROTECTOR
303 config ARCH_SUPPORTS_UPROBES
306 config FIX_EARLYCON_MEM
312 config PGTABLE_LEVELS
318 source "init/Kconfig"
319 source "kernel/Kconfig.freezer"
321 menu "Processor type and features"
324 bool "DMA memory allocation support" if EXPERT
327 DMA memory allocation support allows devices with less than 32-bit
328 addressing to allocate within the first 16MB of address space.
329 Disable if no such devices will be used.
334 bool "Symmetric multi-processing support"
336 This enables support for systems with more than one CPU. If you have
337 a system with only one CPU, say N. If you have a system with more
340 If you say N here, the kernel will run on uni- and multiprocessor
341 machines, but will use only one CPU of a multiprocessor machine. If
342 you say Y here, the kernel will run on many, but not all,
343 uniprocessor machines. On a uniprocessor machine, the kernel
344 will run faster if you say N here.
346 Note that if you say Y here and choose architecture "586" or
347 "Pentium" under "Processor family", the kernel will not work on 486
348 architectures. Similarly, multiprocessor kernels for the "PPro"
349 architecture may not work on all Pentium based boards.
351 People using multiprocessor machines who say Y here should also say
352 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
353 Management" code will be disabled if you say Y here.
355 See also <file:Documentation/x86/i386/IO-APIC.txt>,
356 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
357 <http://www.tldp.org/docs.html#howto>.
359 If you don't know what to do here, say N.
361 config X86_FEATURE_NAMES
362 bool "Processor feature human-readable names" if EMBEDDED
365 This option compiles in a table of x86 feature bits and corresponding
366 names. This is required to support /proc/cpuinfo and a few kernel
367 messages. You can disable this to save space, at the expense of
368 making those few kernel messages show numeric feature bits instead.
372 config X86_FAST_FEATURE_TESTS
373 bool "Fast CPU feature tests" if EMBEDDED
376 Some fast-paths in the kernel depend on the capabilities of the CPU.
377 Say Y here for the kernel to patch in the appropriate code at runtime
378 based on the capabilities of the CPU. The infrastructure for patching
379 code at runtime takes up some additional space; space-constrained
380 embedded systems may wish to say N here to produce smaller, slightly
384 bool "Support x2apic"
385 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
387 This enables x2apic support on CPUs that have this feature.
389 This allows 32-bit apic IDs (so it can support very large systems),
390 and accesses the local apic via MSRs not via mmio.
392 If you don't know what to do here, say N.
395 bool "Enable MPS table" if ACPI || SFI
397 depends on X86_LOCAL_APIC
399 For old smp systems that do not have proper acpi support. Newer systems
400 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
403 bool "Support for big SMP systems with more than 8 CPUs"
404 depends on X86_32 && SMP
406 This option is needed for the systems that have more than 8 CPUs
410 depends on X86_GOLDFISH
413 bool "Avoid speculative indirect branches in kernel"
416 Compile kernel with the retpoline compiler options to guard against
417 kernel-to-user data leaks by avoiding speculative indirect
418 branches. Requires a compiler with -mindirect-branch=thunk-extern
419 support for full protection. The kernel may run slower.
422 config X86_EXTENDED_PLATFORM
423 bool "Support for extended (non-PC) x86 platforms"
426 If you disable this option then the kernel will only support
427 standard PC platforms. (which covers the vast majority of
430 If you enable this option then you'll be able to select support
431 for the following (non-PC) 32 bit x86 platforms:
432 Goldfish (Android emulator)
435 SGI 320/540 (Visual Workstation)
436 STA2X11-based (e.g. Northville)
437 Moorestown MID devices
439 If you have one of these systems, or if you want to build a
440 generic distribution kernel, say Y here - otherwise say N.
444 config X86_EXTENDED_PLATFORM
445 bool "Support for extended (non-PC) x86 platforms"
448 If you disable this option then the kernel will only support
449 standard PC platforms. (which covers the vast majority of
452 If you enable this option then you'll be able to select support
453 for the following (non-PC) 64 bit x86 platforms:
458 If you have one of these systems, or if you want to build a
459 generic distribution kernel, say Y here - otherwise say N.
461 # This is an alphabetically sorted list of 64 bit extended platforms
462 # Please maintain the alphabetic order if and when there are additions
464 bool "Numascale NumaChip"
466 depends on X86_EXTENDED_PLATFORM
469 depends on X86_X2APIC
470 depends on PCI_MMCONFIG
472 Adds support for Numascale NumaChip large-SMP systems. Needed to
473 enable more than ~168 cores.
474 If you don't have one of these, you should say N here.
478 select HYPERVISOR_GUEST
480 depends on X86_64 && PCI
481 depends on X86_EXTENDED_PLATFORM
484 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
485 supposed to run on these EM64T-based machines. Only choose this option
486 if you have one of these machines.
489 bool "SGI Ultraviolet"
491 depends on X86_EXTENDED_PLATFORM
494 depends on KEXEC_CORE
495 depends on X86_X2APIC
498 This option is needed in order to support SGI Ultraviolet systems.
499 If you don't have one of these, you should say N here.
501 # Following is an alphabetically sorted list of 32 bit extended platforms
502 # Please maintain the alphabetic order if and when there are additions
505 bool "Goldfish (Virtual Platform)"
506 depends on X86_EXTENDED_PLATFORM
508 Enable support for the Goldfish virtual platform used primarily
509 for Android development. Unless you are building for the Android
510 Goldfish emulator say N here.
513 bool "CE4100 TV platform"
515 depends on PCI_GODIRECT
516 depends on X86_IO_APIC
518 depends on X86_EXTENDED_PLATFORM
519 select X86_REBOOTFIXUPS
521 select OF_EARLY_FLATTREE
523 Select for the Intel CE media processor (CE4100) SOC.
524 This option compiles in support for the CE4100 SOC for settop
525 boxes and media devices.
528 bool "Intel MID platform support"
529 depends on X86_EXTENDED_PLATFORM
530 depends on X86_PLATFORM_DEVICES
532 depends on X86_64 || (PCI_GOANY && X86_32)
533 depends on X86_IO_APIC
539 select MFD_INTEL_MSIC
541 Select to build a kernel capable of supporting Intel MID (Mobile
542 Internet Device) platform systems which do not have the PCI legacy
543 interfaces. If you are building for a PC class system say N here.
545 Intel MID platforms are based on an Intel processor and chipset which
546 consume less power than most of the x86 derivatives.
548 config X86_INTEL_QUARK
549 bool "Intel Quark platform support"
551 depends on X86_EXTENDED_PLATFORM
552 depends on X86_PLATFORM_DEVICES
556 depends on X86_IO_APIC
561 Select to include support for Quark X1000 SoC.
562 Say Y here if you have a Quark based system such as the Arduino
563 compatible Intel Galileo.
566 tristate "Mellanox Technologies platform support"
568 depends on X86_EXTENDED_PLATFORM
570 This option enables system support for the Mellanox Technologies
573 Say Y here if you are building a kernel for Mellanox system.
577 config X86_INTEL_LPSS
578 bool "Intel Low Power Subsystem Support"
579 depends on X86 && ACPI
584 Select to build support for Intel Low Power Subsystem such as
585 found on Intel Lynxpoint PCH. Selecting this option enables
586 things like clock tree (common clock framework) and pincontrol
587 which are needed by the LPSS peripheral drivers.
589 config X86_AMD_PLATFORM_DEVICE
590 bool "AMD ACPI2Platform devices support"
595 Select to interpret AMD specific ACPI device to platform device
596 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
597 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
598 implemented under PINCTRL subsystem.
601 tristate "Intel SoC IOSF Sideband support for SoC platforms"
604 This option enables sideband register access support for Intel SoC
605 platforms. On these platforms the IOSF sideband is used in lieu of
606 MSR's for some register accesses, mostly but not limited to thermal
607 and power. Drivers may query the availability of this device to
608 determine if they need the sideband in order to work on these
609 platforms. The sideband is available on the following SoC products.
610 This list is not meant to be exclusive.
615 You should say Y if you are running a kernel on one of these SoC's.
617 config IOSF_MBI_DEBUG
618 bool "Enable IOSF sideband access through debugfs"
619 depends on IOSF_MBI && DEBUG_FS
621 Select this option to expose the IOSF sideband access registers (MCR,
622 MDR, MCRX) through debugfs to write and read register information from
623 different units on the SoC. This is most useful for obtaining device
624 state information for debug and analysis. As this is a general access
625 mechanism, users of this option would have specific knowledge of the
626 device they want to access.
628 If you don't require the option or are in doubt, say N.
631 bool "RDC R-321x SoC"
633 depends on X86_EXTENDED_PLATFORM
635 select X86_REBOOTFIXUPS
637 This option is needed for RDC R-321x system-on-chip, also known
639 If you don't have one of these chips, you should say N here.
641 config X86_32_NON_STANDARD
642 bool "Support non-standard 32-bit SMP architectures"
643 depends on X86_32 && SMP
644 depends on X86_EXTENDED_PLATFORM
646 This option compiles in the bigsmp and STA2X11 default
647 subarchitectures. It is intended for a generic binary
648 kernel. If you select them all, kernel will probe it one by
649 one and will fallback to default.
651 # Alphabetically sorted list of Non standard 32 bit platforms
653 config X86_SUPPORTS_MEMORY_FAILURE
655 # MCE code calls memory_failure():
657 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
658 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
659 depends on X86_64 || !SPARSEMEM
660 select ARCH_SUPPORTS_MEMORY_FAILURE
663 bool "STA2X11 Companion Chip Support"
664 depends on X86_32_NON_STANDARD && PCI
665 select X86_DEV_DMA_OPS
672 This adds support for boards based on the STA2X11 IO-Hub,
673 a.k.a. "ConneXt". The chip is used in place of the standard
674 PC chipset, so all "standard" peripherals are missing. If this
675 option is selected the kernel will still be able to boot on
676 standard PC machines.
679 tristate "Eurobraille/Iris poweroff module"
682 The Iris machines from EuroBraille do not have APM or ACPI support
683 to shut themselves down properly. A special I/O sequence is
684 needed to do so, which is what this module does at
687 This is only for Iris machines from EuroBraille.
691 config SCHED_OMIT_FRAME_POINTER
693 prompt "Single-depth WCHAN output"
696 Calculate simpler /proc/<PID>/wchan values. If this option
697 is disabled then wchan values will recurse back to the
698 caller function. This provides more accurate wchan values,
699 at the expense of slightly more scheduling overhead.
701 If in doubt, say "Y".
703 menuconfig HYPERVISOR_GUEST
704 bool "Linux guest support"
706 Say Y here to enable options for running Linux under various hyper-
707 visors. This option enables basic hypervisor detection and platform
710 If you say N, all options in this submenu will be skipped and
711 disabled, and Linux guest support won't be built in.
716 bool "Enable paravirtualization code"
718 This changes the kernel so it can modify itself when it is run
719 under a hypervisor, potentially improving performance significantly
720 over full virtualization. However, when run without a hypervisor
721 the kernel is theoretically slower and slightly larger.
723 config PARAVIRT_DEBUG
724 bool "paravirt-ops debugging"
725 depends on PARAVIRT && DEBUG_KERNEL
727 Enable to debug paravirt_ops internals. Specifically, BUG if
728 a paravirt_op is missing when it is called.
730 config PARAVIRT_SPINLOCKS
731 bool "Paravirtualization layer for spinlocks"
732 depends on PARAVIRT && SMP
734 Paravirtualized spinlocks allow a pvops backend to replace the
735 spinlock implementation with something virtualization-friendly
736 (for example, block the virtual CPU rather than spinning).
738 It has a minimal impact on native kernels and gives a nice performance
739 benefit on paravirtualized KVM / Xen kernels.
741 If you are unsure how to answer this question, answer Y.
743 config QUEUED_LOCK_STAT
744 bool "Paravirt queued spinlock statistics"
745 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
747 Enable the collection of statistical data on the slowpath
748 behavior of paravirtualized queued spinlocks and report
751 source "arch/x86/xen/Kconfig"
754 bool "KVM Guest support (including kvmclock)"
756 select PARAVIRT_CLOCK
759 This option enables various optimizations for running under the KVM
760 hypervisor. It includes a paravirtualized clock, so that instead
761 of relying on a PIT (or probably other) emulation by the
762 underlying device model, the host provides the guest with
763 timing infrastructure such as time of day, and system time
766 bool "Enable debug information for KVM Guests in debugfs"
767 depends on KVM_GUEST && DEBUG_FS
770 This option enables collection of various statistics for KVM guest.
771 Statistics are displayed in debugfs filesystem. Enabling this option
772 may incur significant overhead.
774 source "arch/x86/lguest/Kconfig"
776 config PARAVIRT_TIME_ACCOUNTING
777 bool "Paravirtual steal time accounting"
781 Select this option to enable fine granularity task steal time
782 accounting. Time spent executing other tasks in parallel with
783 the current vCPU is discounted from the vCPU power. To account for
784 that, there can be a small performance impact.
786 If in doubt, say N here.
788 config PARAVIRT_CLOCK
791 endif #HYPERVISOR_GUEST
796 source "arch/x86/Kconfig.cpu"
800 prompt "HPET Timer Support" if X86_32
802 Use the IA-PC HPET (High Precision Event Timer) to manage
803 time in preference to the PIT and RTC, if a HPET is
805 HPET is the next generation timer replacing legacy 8254s.
806 The HPET provides a stable time base on SMP
807 systems, unlike the TSC, but it is more expensive to access,
808 as it is off-chip. The interface used is documented
809 in the HPET spec, revision 1.
811 You can safely choose Y here. However, HPET will only be
812 activated if the platform and the BIOS support this feature.
813 Otherwise the 8254 will be used for timing services.
815 Choose N to continue using the legacy 8254 timer.
817 config HPET_EMULATE_RTC
819 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
822 def_bool y if X86_INTEL_MID
823 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
825 depends on X86_INTEL_MID && SFI
827 APB timer is the replacement for 8254, HPET on X86 MID platforms.
828 The APBT provides a stable time base on SMP
829 systems, unlike the TSC, but it is more expensive to access,
830 as it is off-chip. APB timers are always running regardless of CPU
831 C states, they are used as per CPU clockevent device when possible.
833 # Mark as expert because too many people got it wrong.
834 # The code disables itself when not needed.
837 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
838 bool "Enable DMI scanning" if EXPERT
840 Enabled scanning of DMI to identify machine quirks. Say Y
841 here unless you have verified that your setup is not
842 affected by entries in the DMI blacklist. Required by PNP
846 bool "Old AMD GART IOMMU support"
848 depends on X86_64 && PCI && AMD_NB
850 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
851 GART based hardware IOMMUs.
853 The GART supports full DMA access for devices with 32-bit access
854 limitations, on systems with more than 3 GB. This is usually needed
855 for USB, sound, many IDE/SATA chipsets and some other devices.
857 Newer systems typically have a modern AMD IOMMU, supported via
858 the CONFIG_AMD_IOMMU=y config option.
860 In normal configurations this driver is only active when needed:
861 there's more than 3 GB of memory and the system contains a
862 32-bit limited device.
867 bool "IBM Calgary IOMMU support"
869 depends on X86_64 && PCI
871 Support for hardware IOMMUs in IBM's xSeries x366 and x460
872 systems. Needed to run systems with more than 3GB of memory
873 properly with 32-bit PCI devices that do not support DAC
874 (Double Address Cycle). Calgary also supports bus level
875 isolation, where all DMAs pass through the IOMMU. This
876 prevents them from going anywhere except their intended
877 destination. This catches hard-to-find kernel bugs and
878 mis-behaving drivers and devices that do not use the DMA-API
879 properly to set up their DMA buffers. The IOMMU can be
880 turned off at boot time with the iommu=off parameter.
881 Normally the kernel will make the right choice by itself.
884 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
886 prompt "Should Calgary be enabled by default?"
887 depends on CALGARY_IOMMU
889 Should Calgary be enabled by default? if you choose 'y', Calgary
890 will be used (if it exists). If you choose 'n', Calgary will not be
891 used even if it exists. If you choose 'n' and would like to use
892 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
895 # need this always selected by IOMMU for the VIA workaround
899 Support for software bounce buffers used on x86-64 systems
900 which don't have a hardware IOMMU. Using this PCI devices
901 which can only access 32-bits of memory can be used on systems
902 with more than 3 GB of memory.
907 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
910 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
911 depends on X86_64 && SMP && DEBUG_KERNEL
912 select CPUMASK_OFFSTACK
914 Enable maximum number of CPUS and NUMA Nodes for this architecture.
918 int "Maximum number of CPUs" if SMP && !MAXSMP
919 range 2 8 if SMP && X86_32 && !X86_BIGSMP
920 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
921 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
923 default "8192" if MAXSMP
924 default "32" if SMP && X86_BIGSMP
925 default "8" if SMP && X86_32
928 This allows you to specify the maximum number of CPUs which this
929 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
930 supported value is 8192, otherwise the maximum value is 512. The
931 minimum value which makes sense is 2.
933 This is purely to save memory - each supported CPU adds
934 approximately eight kilobytes to the kernel image.
941 prompt "Multi-core scheduler support"
944 Multi-core scheduler support improves the CPU scheduler's decision
945 making when dealing with multi-core CPU chips at a cost of slightly
946 increased overhead in some places. If unsure say N here.
948 source "kernel/Kconfig.preempt"
952 depends on !SMP && X86_LOCAL_APIC
955 bool "Local APIC support on uniprocessors" if !PCI_MSI
957 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
959 A local APIC (Advanced Programmable Interrupt Controller) is an
960 integrated interrupt controller in the CPU. If you have a single-CPU
961 system which has a processor with a local APIC, you can say Y here to
962 enable and use it. If you say Y here even though your machine doesn't
963 have a local APIC, then the kernel will still run with no slowdown at
964 all. The local APIC supports CPU-generated self-interrupts (timer,
965 performance counters), and the NMI watchdog which detects hard
969 bool "IO-APIC support on uniprocessors"
970 depends on X86_UP_APIC
972 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
973 SMP-capable replacement for PC-style interrupt controllers. Most
974 SMP systems and many recent uniprocessor systems have one.
976 If you have a single-CPU system with an IO-APIC, you can say Y here
977 to use it. If you say Y here even though your machine doesn't have
978 an IO-APIC, then the kernel will still run with no slowdown at all.
980 config X86_LOCAL_APIC
982 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
983 select IRQ_DOMAIN_HIERARCHY
984 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
988 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
990 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
991 bool "Reroute for broken boot IRQs"
992 depends on X86_IO_APIC
994 This option enables a workaround that fixes a source of
995 spurious interrupts. This is recommended when threaded
996 interrupt handling is used on systems where the generation of
997 superfluous "boot interrupts" cannot be disabled.
999 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1000 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1001 kernel does during interrupt handling). On chipsets where this
1002 boot IRQ generation cannot be disabled, this workaround keeps
1003 the original IRQ line masked so that only the equivalent "boot
1004 IRQ" is delivered to the CPUs. The workaround also tells the
1005 kernel to set up the IRQ handler on the boot IRQ line. In this
1006 way only one interrupt is delivered to the kernel. Otherwise
1007 the spurious second interrupt may cause the kernel to bring
1008 down (vital) interrupt lines.
1010 Only affects "broken" chipsets. Interrupt sharing may be
1011 increased on these systems.
1014 bool "Machine Check / overheating reporting"
1015 select GENERIC_ALLOCATOR
1018 Machine Check support allows the processor to notify the
1019 kernel if it detects a problem (e.g. overheating, data corruption).
1020 The action the kernel takes depends on the severity of the problem,
1021 ranging from warning messages to halting the machine.
1023 config X86_MCE_INTEL
1025 prompt "Intel MCE features"
1026 depends on X86_MCE && X86_LOCAL_APIC
1028 Additional support for intel specific MCE features such as
1029 the thermal monitor.
1033 prompt "AMD MCE features"
1034 depends on X86_MCE && X86_LOCAL_APIC
1036 Additional support for AMD specific MCE features such as
1037 the DRAM Error Threshold.
1039 config X86_ANCIENT_MCE
1040 bool "Support for old Pentium 5 / WinChip machine checks"
1041 depends on X86_32 && X86_MCE
1043 Include support for machine check handling on old Pentium 5 or WinChip
1044 systems. These typically need to be enabled explicitly on the command
1047 config X86_MCE_THRESHOLD
1048 depends on X86_MCE_AMD || X86_MCE_INTEL
1051 config X86_MCE_INJECT
1052 depends on X86_MCE && X86_LOCAL_APIC
1053 tristate "Machine check injector support"
1055 Provide support for injecting machine checks for testing purposes.
1056 If you don't know what a machine check is and you don't do kernel
1057 QA it is safe to say n.
1059 config X86_THERMAL_VECTOR
1061 depends on X86_MCE_INTEL
1063 source "arch/x86/events/Kconfig"
1065 config X86_LEGACY_VM86
1066 bool "Legacy VM86 support"
1070 This option allows user programs to put the CPU into V8086
1071 mode, which is an 80286-era approximation of 16-bit real mode.
1073 Some very old versions of X and/or vbetool require this option
1074 for user mode setting. Similarly, DOSEMU will use it if
1075 available to accelerate real mode DOS programs. However, any
1076 recent version of DOSEMU, X, or vbetool should be fully
1077 functional even without kernel VM86 support, as they will all
1078 fall back to software emulation. Nevertheless, if you are using
1079 a 16-bit DOS program where 16-bit performance matters, vm86
1080 mode might be faster than emulation and you might want to
1083 Note that any app that works on a 64-bit kernel is unlikely to
1084 need this option, as 64-bit kernels don't, and can't, support
1085 V8086 mode. This option is also unrelated to 16-bit protected
1086 mode and is not needed to run most 16-bit programs under Wine.
1088 Enabling this option increases the complexity of the kernel
1089 and slows down exception handling a tiny bit.
1091 If unsure, say N here.
1095 default X86_LEGACY_VM86
1098 bool "Enable support for 16-bit segments" if EXPERT
1100 depends on MODIFY_LDT_SYSCALL
1102 This option is required by programs like Wine to run 16-bit
1103 protected mode legacy code on x86 processors. Disabling
1104 this option saves about 300 bytes on i386, or around 6K text
1105 plus 16K runtime memory on x86-64,
1109 depends on X86_16BIT && X86_32
1113 depends on X86_16BIT && X86_64
1115 config X86_VSYSCALL_EMULATION
1116 bool "Enable vsyscall emulation" if EXPERT
1120 This enables emulation of the legacy vsyscall page. Disabling
1121 it is roughly equivalent to booting with vsyscall=none, except
1122 that it will also disable the helpful warning if a program
1123 tries to use a vsyscall. With this option set to N, offending
1124 programs will just segfault, citing addresses of the form
1127 This option is required by many programs built before 2013, and
1128 care should be used even with newer programs if set to N.
1130 Disabling this option saves about 7K of kernel size and
1131 possibly 4K of additional runtime pagetable memory.
1134 tristate "Toshiba Laptop support"
1137 This adds a driver to safely access the System Management Mode of
1138 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1139 not work on models with a Phoenix BIOS. The System Management Mode
1140 is used to set the BIOS and power saving options on Toshiba portables.
1142 For information on utilities to make use of this driver see the
1143 Toshiba Linux utilities web site at:
1144 <http://www.buzzard.org.uk/toshiba/>.
1146 Say Y if you intend to run this kernel on a Toshiba portable.
1150 tristate "Dell i8k legacy laptop support"
1152 select SENSORS_DELL_SMM
1154 This option enables legacy /proc/i8k userspace interface in hwmon
1155 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1156 temperature and allows controlling fan speeds of Dell laptops via
1157 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1158 it reports also power and hotkey status. For fan speed control is
1159 needed userspace package i8kutils.
1161 Say Y if you intend to run this kernel on old Dell laptops or want to
1162 use userspace package i8kutils.
1165 config X86_REBOOTFIXUPS
1166 bool "Enable X86 board specific fixups for reboot"
1169 This enables chipset and/or board specific fixups to be done
1170 in order to get reboot to work correctly. This is only needed on
1171 some combinations of hardware and BIOS. The symptom, for which
1172 this config is intended, is when reboot ends with a stalled/hung
1175 Currently, the only fixup is for the Geode machines using
1176 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1178 Say Y if you want to enable the fixup. Currently, it's safe to
1179 enable this option even if you don't need it.
1183 bool "CPU microcode loading support"
1185 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1188 If you say Y here, you will be able to update the microcode on
1189 Intel and AMD processors. The Intel support is for the IA32 family,
1190 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1191 AMD support is for families 0x10 and later. You will obviously need
1192 the actual microcode binary data itself which is not shipped with
1195 The preferred method to load microcode from a detached initrd is described
1196 in Documentation/x86/early-microcode.txt. For that you need to enable
1197 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1198 initrd for microcode blobs.
1200 In addition, you can build-in the microcode into the kernel. For that you
1201 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1202 to the CONFIG_EXTRA_FIRMWARE config option.
1204 config MICROCODE_INTEL
1205 bool "Intel microcode loading support"
1206 depends on MICROCODE
1210 This options enables microcode patch loading support for Intel
1213 For the current Intel microcode data package go to
1214 <https://downloadcenter.intel.com> and search for
1215 'Linux Processor Microcode Data File'.
1217 config MICROCODE_AMD
1218 bool "AMD microcode loading support"
1219 depends on MICROCODE
1222 If you select this option, microcode patch loading support for AMD
1223 processors will be enabled.
1225 config MICROCODE_OLD_INTERFACE
1227 depends on MICROCODE
1230 tristate "/dev/cpu/*/msr - Model-specific register support"
1232 This device gives privileged processes access to the x86
1233 Model-Specific Registers (MSRs). It is a character device with
1234 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1235 MSR accesses are directed to a specific CPU on multi-processor
1239 tristate "/dev/cpu/*/cpuid - CPU information support"
1241 This device gives processes access to the x86 CPUID instruction to
1242 be executed on a specific processor. It is a character device
1243 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1247 prompt "High Memory Support"
1254 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1255 However, the address space of 32-bit x86 processors is only 4
1256 Gigabytes large. That means that, if you have a large amount of
1257 physical memory, not all of it can be "permanently mapped" by the
1258 kernel. The physical memory that's not permanently mapped is called
1261 If you are compiling a kernel which will never run on a machine with
1262 more than 1 Gigabyte total physical RAM, answer "off" here (default
1263 choice and suitable for most users). This will result in a "3GB/1GB"
1264 split: 3GB are mapped so that each process sees a 3GB virtual memory
1265 space and the remaining part of the 4GB virtual memory space is used
1266 by the kernel to permanently map as much physical memory as
1269 If the machine has between 1 and 4 Gigabytes physical RAM, then
1272 If more than 4 Gigabytes is used then answer "64GB" here. This
1273 selection turns Intel PAE (Physical Address Extension) mode on.
1274 PAE implements 3-level paging on IA32 processors. PAE is fully
1275 supported by Linux, PAE mode is implemented on all recent Intel
1276 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1277 then the kernel will not boot on CPUs that don't support PAE!
1279 The actual amount of total physical memory will either be
1280 auto detected or can be forced by using a kernel command line option
1281 such as "mem=256M". (Try "man bootparam" or see the documentation of
1282 your boot loader (lilo or loadlin) about how to pass options to the
1283 kernel at boot time.)
1285 If unsure, say "off".
1290 Select this if you have a 32-bit processor and between 1 and 4
1291 gigabytes of physical RAM.
1298 Select this if you have a 32-bit processor and more than 4
1299 gigabytes of physical RAM.
1304 prompt "Memory split" if EXPERT
1308 Select the desired split between kernel and user memory.
1310 If the address range available to the kernel is less than the
1311 physical memory installed, the remaining memory will be available
1312 as "high memory". Accessing high memory is a little more costly
1313 than low memory, as it needs to be mapped into the kernel first.
1314 Note that increasing the kernel address space limits the range
1315 available to user programs, making the address space there
1316 tighter. Selecting anything other than the default 3G/1G split
1317 will also likely make your kernel incompatible with binary-only
1320 If you are not absolutely sure what you are doing, leave this
1324 bool "3G/1G user/kernel split"
1325 config VMSPLIT_3G_OPT
1327 bool "3G/1G user/kernel split (for full 1G low memory)"
1329 bool "2G/2G user/kernel split"
1330 config VMSPLIT_2G_OPT
1332 bool "2G/2G user/kernel split (for full 2G low memory)"
1334 bool "1G/3G user/kernel split"
1339 default 0xB0000000 if VMSPLIT_3G_OPT
1340 default 0x80000000 if VMSPLIT_2G
1341 default 0x78000000 if VMSPLIT_2G_OPT
1342 default 0x40000000 if VMSPLIT_1G
1348 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1351 bool "PAE (Physical Address Extension) Support"
1352 depends on X86_32 && !HIGHMEM4G
1355 PAE is required for NX support, and furthermore enables
1356 larger swapspace support for non-overcommit purposes. It
1357 has the cost of more pagetable lookup overhead, and also
1358 consumes more pagetable space per process.
1360 config ARCH_PHYS_ADDR_T_64BIT
1362 depends on X86_64 || X86_PAE
1364 config ARCH_DMA_ADDR_T_64BIT
1366 depends on X86_64 || HIGHMEM64G
1368 config X86_DIRECT_GBPAGES
1370 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1372 Certain kernel features effectively disable kernel
1373 linear 1 GB mappings (even if the CPU otherwise
1374 supports them), so don't confuse the user by printing
1375 that we have them enabled.
1377 # Common NUMA Features
1379 bool "Numa Memory Allocation and Scheduler Support"
1381 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1382 default y if X86_BIGSMP
1384 Enable NUMA (Non Uniform Memory Access) support.
1386 The kernel will try to allocate memory used by a CPU on the
1387 local memory controller of the CPU and add some more
1388 NUMA awareness to the kernel.
1390 For 64-bit this is recommended if the system is Intel Core i7
1391 (or later), AMD Opteron, or EM64T NUMA.
1393 For 32-bit this is only needed if you boot a 32-bit
1394 kernel on a 64-bit NUMA platform.
1396 Otherwise, you should say N.
1400 prompt "Old style AMD Opteron NUMA detection"
1401 depends on X86_64 && NUMA && PCI
1403 Enable AMD NUMA node topology detection. You should say Y here if
1404 you have a multi processor AMD system. This uses an old method to
1405 read the NUMA configuration directly from the builtin Northbridge
1406 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1407 which also takes priority if both are compiled in.
1409 config X86_64_ACPI_NUMA
1411 prompt "ACPI NUMA detection"
1412 depends on X86_64 && NUMA && ACPI && PCI
1415 Enable ACPI SRAT based node topology detection.
1417 # Some NUMA nodes have memory ranges that span
1418 # other nodes. Even though a pfn is valid and
1419 # between a node's start and end pfns, it may not
1420 # reside on that node. See memmap_init_zone()
1422 config NODES_SPAN_OTHER_NODES
1424 depends on X86_64_ACPI_NUMA
1427 bool "NUMA emulation"
1430 Enable NUMA emulation. A flat machine will be split
1431 into virtual nodes when booted with "numa=fake=N", where N is the
1432 number of nodes. This is only useful for debugging.
1435 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1437 default "10" if MAXSMP
1438 default "6" if X86_64
1440 depends on NEED_MULTIPLE_NODES
1442 Specify the maximum number of NUMA Nodes available on the target
1443 system. Increases memory reserved to accommodate various tables.
1445 config ARCH_HAVE_MEMORY_PRESENT
1447 depends on X86_32 && DISCONTIGMEM
1449 config NEED_NODE_MEMMAP_SIZE
1451 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1453 config ARCH_FLATMEM_ENABLE
1455 depends on X86_32 && !NUMA
1457 config ARCH_DISCONTIGMEM_ENABLE
1459 depends on NUMA && X86_32
1461 config ARCH_DISCONTIGMEM_DEFAULT
1463 depends on NUMA && X86_32
1465 config ARCH_SPARSEMEM_ENABLE
1467 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1468 select SPARSEMEM_STATIC if X86_32
1469 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1471 config ARCH_SPARSEMEM_DEFAULT
1475 config ARCH_SELECT_MEMORY_MODEL
1477 depends on ARCH_SPARSEMEM_ENABLE
1479 config ARCH_MEMORY_PROBE
1480 bool "Enable sysfs memory/probe interface"
1481 depends on X86_64 && MEMORY_HOTPLUG
1483 This option enables a sysfs memory/probe interface for testing.
1484 See Documentation/memory-hotplug.txt for more information.
1485 If you are unsure how to answer this question, answer N.
1487 config ARCH_PROC_KCORE_TEXT
1489 depends on X86_64 && PROC_KCORE
1491 config ILLEGAL_POINTER_VALUE
1494 default 0xdead000000000000 if X86_64
1498 config X86_PMEM_LEGACY_DEVICE
1501 config X86_PMEM_LEGACY
1502 tristate "Support non-standard NVDIMMs and ADR protected memory"
1503 depends on PHYS_ADDR_T_64BIT
1505 select X86_PMEM_LEGACY_DEVICE
1508 Treat memory marked using the non-standard e820 type of 12 as used
1509 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1510 The kernel will offer these regions to the 'pmem' driver so
1511 they can be used for persistent storage.
1516 bool "Allocate 3rd-level pagetables from highmem"
1519 The VM uses one page table entry for each page of physical memory.
1520 For systems with a lot of RAM, this can be wasteful of precious
1521 low memory. Setting this option will put user-space page table
1522 entries in high memory.
1524 config X86_CHECK_BIOS_CORRUPTION
1525 bool "Check for low memory corruption"
1527 Periodically check for memory corruption in low memory, which
1528 is suspected to be caused by BIOS. Even when enabled in the
1529 configuration, it is disabled at runtime. Enable it by
1530 setting "memory_corruption_check=1" on the kernel command
1531 line. By default it scans the low 64k of memory every 60
1532 seconds; see the memory_corruption_check_size and
1533 memory_corruption_check_period parameters in
1534 Documentation/kernel-parameters.txt to adjust this.
1536 When enabled with the default parameters, this option has
1537 almost no overhead, as it reserves a relatively small amount
1538 of memory and scans it infrequently. It both detects corruption
1539 and prevents it from affecting the running system.
1541 It is, however, intended as a diagnostic tool; if repeatable
1542 BIOS-originated corruption always affects the same memory,
1543 you can use memmap= to prevent the kernel from using that
1546 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1547 bool "Set the default setting of memory_corruption_check"
1548 depends on X86_CHECK_BIOS_CORRUPTION
1551 Set whether the default state of memory_corruption_check is
1554 config X86_RESERVE_LOW
1555 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1559 Specify the amount of low memory to reserve for the BIOS.
1561 The first page contains BIOS data structures that the kernel
1562 must not use, so that page must always be reserved.
1564 By default we reserve the first 64K of physical RAM, as a
1565 number of BIOSes are known to corrupt that memory range
1566 during events such as suspend/resume or monitor cable
1567 insertion, so it must not be used by the kernel.
1569 You can set this to 4 if you are absolutely sure that you
1570 trust the BIOS to get all its memory reservations and usages
1571 right. If you know your BIOS have problems beyond the
1572 default 64K area, you can set this to 640 to avoid using the
1573 entire low memory range.
1575 If you have doubts about the BIOS (e.g. suspend/resume does
1576 not work or there's kernel crashes after certain hardware
1577 hotplug events) then you might want to enable
1578 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1579 typical corruption patterns.
1581 Leave this to the default value of 64 if you are unsure.
1583 config MATH_EMULATION
1585 depends on MODIFY_LDT_SYSCALL
1586 prompt "Math emulation" if X86_32
1588 Linux can emulate a math coprocessor (used for floating point
1589 operations) if you don't have one. 486DX and Pentium processors have
1590 a math coprocessor built in, 486SX and 386 do not, unless you added
1591 a 487DX or 387, respectively. (The messages during boot time can
1592 give you some hints here ["man dmesg"].) Everyone needs either a
1593 coprocessor or this emulation.
1595 If you don't have a math coprocessor, you need to say Y here; if you
1596 say Y here even though you have a coprocessor, the coprocessor will
1597 be used nevertheless. (This behavior can be changed with the kernel
1598 command line option "no387", which comes handy if your coprocessor
1599 is broken. Try "man bootparam" or see the documentation of your boot
1600 loader (lilo or loadlin) about how to pass options to the kernel at
1601 boot time.) This means that it is a good idea to say Y here if you
1602 intend to use this kernel on different machines.
1604 More information about the internals of the Linux math coprocessor
1605 emulation can be found in <file:arch/x86/math-emu/README>.
1607 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1608 kernel, it won't hurt.
1612 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1614 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1615 the Memory Type Range Registers (MTRRs) may be used to control
1616 processor access to memory ranges. This is most useful if you have
1617 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1618 allows bus write transfers to be combined into a larger transfer
1619 before bursting over the PCI/AGP bus. This can increase performance
1620 of image write operations 2.5 times or more. Saying Y here creates a
1621 /proc/mtrr file which may be used to manipulate your processor's
1622 MTRRs. Typically the X server should use this.
1624 This code has a reasonably generic interface so that similar
1625 control registers on other processors can be easily supported
1628 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1629 Registers (ARRs) which provide a similar functionality to MTRRs. For
1630 these, the ARRs are used to emulate the MTRRs.
1631 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1632 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1633 write-combining. All of these processors are supported by this code
1634 and it makes sense to say Y here if you have one of them.
1636 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1637 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1638 can lead to all sorts of problems, so it's good to say Y here.
1640 You can safely say Y even if your machine doesn't have MTRRs, you'll
1641 just add about 9 KB to your kernel.
1643 See <file:Documentation/x86/mtrr.txt> for more information.
1645 config MTRR_SANITIZER
1647 prompt "MTRR cleanup support"
1650 Convert MTRR layout from continuous to discrete, so X drivers can
1651 add writeback entries.
1653 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1654 The largest mtrr entry size for a continuous block can be set with
1659 config MTRR_SANITIZER_ENABLE_DEFAULT
1660 int "MTRR cleanup enable value (0-1)"
1663 depends on MTRR_SANITIZER
1665 Enable mtrr cleanup default value
1667 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1668 int "MTRR cleanup spare reg num (0-7)"
1671 depends on MTRR_SANITIZER
1673 mtrr cleanup spare entries default, it can be changed via
1674 mtrr_spare_reg_nr=N on the kernel command line.
1678 prompt "x86 PAT support" if EXPERT
1681 Use PAT attributes to setup page level cache control.
1683 PATs are the modern equivalents of MTRRs and are much more
1684 flexible than MTRRs.
1686 Say N here if you see bootup problems (boot crash, boot hang,
1687 spontaneous reboots) or a non-working video driver.
1691 config ARCH_USES_PG_UNCACHED
1697 prompt "x86 architectural random number generator" if EXPERT
1699 Enable the x86 architectural RDRAND instruction
1700 (Intel Bull Mountain technology) to generate random numbers.
1701 If supported, this is a high bandwidth, cryptographically
1702 secure hardware random number generator.
1706 prompt "Supervisor Mode Access Prevention" if EXPERT
1708 Supervisor Mode Access Prevention (SMAP) is a security
1709 feature in newer Intel processors. There is a small
1710 performance cost if this enabled and turned on; there is
1711 also a small increase in the kernel size if this is enabled.
1715 config X86_INTEL_MPX
1716 prompt "Intel MPX (Memory Protection Extensions)"
1718 depends on CPU_SUP_INTEL
1720 MPX provides hardware features that can be used in
1721 conjunction with compiler-instrumented code to check
1722 memory references. It is designed to detect buffer
1723 overflow or underflow bugs.
1725 This option enables running applications which are
1726 instrumented or otherwise use MPX. It does not use MPX
1727 itself inside the kernel or to protect the kernel
1728 against bad memory references.
1730 Enabling this option will make the kernel larger:
1731 ~8k of kernel text and 36 bytes of data on a 64-bit
1732 defconfig. It adds a long to the 'mm_struct' which
1733 will increase the kernel memory overhead of each
1734 process and adds some branches to paths used during
1735 exec() and munmap().
1737 For details, see Documentation/x86/intel_mpx.txt
1741 config X86_INTEL_MEMORY_PROTECTION_KEYS
1742 prompt "Intel Memory Protection Keys"
1744 # Note: only available in 64-bit mode
1745 depends on CPU_SUP_INTEL && X86_64
1747 Memory Protection Keys provides a mechanism for enforcing
1748 page-based protections, but without requiring modification of the
1749 page tables when an application changes protection domains.
1751 For details, see Documentation/x86/protection-keys.txt
1756 prompt "TSX enable mode"
1757 depends on CPU_SUP_INTEL
1758 default X86_INTEL_TSX_MODE_OFF
1760 Intel's TSX (Transactional Synchronization Extensions) feature
1761 allows to optimize locking protocols through lock elision which
1762 can lead to a noticeable performance boost.
1764 On the other hand it has been shown that TSX can be exploited
1765 to form side channel attacks (e.g. TAA) and chances are there
1766 will be more of those attacks discovered in the future.
1768 Therefore TSX is not enabled by default (aka tsx=off). An admin
1769 might override this decision by tsx=on the command line parameter.
1770 Even with TSX enabled, the kernel will attempt to enable the best
1771 possible TAA mitigation setting depending on the microcode available
1772 for the particular machine.
1774 This option allows to set the default tsx mode between tsx=on, =off
1775 and =auto. See Documentation/kernel-parameters.txt for more
1778 Say off if not sure, auto if TSX is in use but it should be used on safe
1779 platforms or on if TSX is in use and the security aspect of tsx is not
1782 config X86_INTEL_TSX_MODE_OFF
1785 TSX is disabled if possible - equals to tsx=off command line parameter.
1787 config X86_INTEL_TSX_MODE_ON
1790 TSX is always enabled on TSX capable HW - equals the tsx=on command
1793 config X86_INTEL_TSX_MODE_AUTO
1796 TSX is enabled on TSX capable HW that is believed to be safe against
1797 side channel attacks- equals the tsx=auto command line parameter.
1801 bool "EFI runtime service support"
1804 select EFI_RUNTIME_WRAPPERS
1806 This enables the kernel to use EFI runtime services that are
1807 available (such as the EFI variable services).
1809 This option is only useful on systems that have EFI firmware.
1810 In addition, you should use the latest ELILO loader available
1811 at <http://elilo.sourceforge.net> in order to take advantage
1812 of EFI runtime services. However, even with this option, the
1813 resultant kernel should continue to boot on existing non-EFI
1817 bool "EFI stub support"
1818 depends on EFI && !X86_USE_3DNOW
1821 This kernel feature allows a bzImage to be loaded directly
1822 by EFI firmware without the use of a bootloader.
1824 See Documentation/efi-stub.txt for more information.
1827 bool "EFI mixed-mode support"
1828 depends on EFI_STUB && X86_64
1830 Enabling this feature allows a 64-bit kernel to be booted
1831 on a 32-bit firmware, provided that your CPU supports 64-bit
1834 Note that it is not possible to boot a mixed-mode enabled
1835 kernel via the EFI boot stub - a bootloader that supports
1836 the EFI handover protocol must be used.
1842 prompt "Enable seccomp to safely compute untrusted bytecode"
1844 This kernel feature is useful for number crunching applications
1845 that may need to compute untrusted bytecode during their
1846 execution. By using pipes or other transports made available to
1847 the process as file descriptors supporting the read/write
1848 syscalls, it's possible to isolate those applications in
1849 their own address space using seccomp. Once seccomp is
1850 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1851 and the task is only allowed to execute a few safe syscalls
1852 defined by each seccomp mode.
1854 If unsure, say Y. Only embedded should say N here.
1856 source kernel/Kconfig.hz
1859 bool "kexec system call"
1862 kexec is a system call that implements the ability to shutdown your
1863 current kernel, and to start another kernel. It is like a reboot
1864 but it is independent of the system firmware. And like a reboot
1865 you can start any kernel with it, not just Linux.
1867 The name comes from the similarity to the exec system call.
1869 It is an ongoing process to be certain the hardware in a machine
1870 is properly shutdown, so do not be surprised if this code does not
1871 initially work for you. As of this writing the exact hardware
1872 interface is strongly in flux, so no good recommendation can be
1876 bool "kexec file based system call"
1881 depends on CRYPTO_SHA256=y
1883 This is new version of kexec system call. This system call is
1884 file based and takes file descriptors as system call argument
1885 for kernel and initramfs as opposed to list of segments as
1886 accepted by previous system call.
1888 config KEXEC_VERIFY_SIG
1889 bool "Verify kernel signature during kexec_file_load() syscall"
1890 depends on KEXEC_FILE
1892 This option makes kernel signature verification mandatory for
1893 the kexec_file_load() syscall.
1895 In addition to that option, you need to enable signature
1896 verification for the corresponding kernel image type being
1897 loaded in order for this to work.
1899 config KEXEC_BZIMAGE_VERIFY_SIG
1900 bool "Enable bzImage signature verification support"
1901 depends on KEXEC_VERIFY_SIG
1902 depends on SIGNED_PE_FILE_VERIFICATION
1903 select SYSTEM_TRUSTED_KEYRING
1905 Enable bzImage signature verification support.
1908 bool "kernel crash dumps"
1909 depends on X86_64 || (X86_32 && HIGHMEM)
1911 Generate crash dump after being started by kexec.
1912 This should be normally only set in special crash dump kernels
1913 which are loaded in the main kernel with kexec-tools into
1914 a specially reserved region and then later executed after
1915 a crash by kdump/kexec. The crash dump kernel must be compiled
1916 to a memory address not used by the main kernel or BIOS using
1917 PHYSICAL_START, or it must be built as a relocatable image
1918 (CONFIG_RELOCATABLE=y).
1919 For more details see Documentation/kdump/kdump.txt
1923 depends on KEXEC && HIBERNATION
1925 Jump between original kernel and kexeced kernel and invoke
1926 code in physical address mode via KEXEC
1928 config PHYSICAL_START
1929 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1932 This gives the physical address where the kernel is loaded.
1934 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1935 bzImage will decompress itself to above physical address and
1936 run from there. Otherwise, bzImage will run from the address where
1937 it has been loaded by the boot loader and will ignore above physical
1940 In normal kdump cases one does not have to set/change this option
1941 as now bzImage can be compiled as a completely relocatable image
1942 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1943 address. This option is mainly useful for the folks who don't want
1944 to use a bzImage for capturing the crash dump and want to use a
1945 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1946 to be specifically compiled to run from a specific memory area
1947 (normally a reserved region) and this option comes handy.
1949 So if you are using bzImage for capturing the crash dump,
1950 leave the value here unchanged to 0x1000000 and set
1951 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1952 for capturing the crash dump change this value to start of
1953 the reserved region. In other words, it can be set based on
1954 the "X" value as specified in the "crashkernel=YM@XM"
1955 command line boot parameter passed to the panic-ed
1956 kernel. Please take a look at Documentation/kdump/kdump.txt
1957 for more details about crash dumps.
1959 Usage of bzImage for capturing the crash dump is recommended as
1960 one does not have to build two kernels. Same kernel can be used
1961 as production kernel and capture kernel. Above option should have
1962 gone away after relocatable bzImage support is introduced. But it
1963 is present because there are users out there who continue to use
1964 vmlinux for dump capture. This option should go away down the
1967 Don't change this unless you know what you are doing.
1970 bool "Build a relocatable kernel"
1973 This builds a kernel image that retains relocation information
1974 so it can be loaded someplace besides the default 1MB.
1975 The relocations tend to make the kernel binary about 10% larger,
1976 but are discarded at runtime.
1978 One use is for the kexec on panic case where the recovery kernel
1979 must live at a different physical address than the primary
1982 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1983 it has been loaded at and the compile time physical address
1984 (CONFIG_PHYSICAL_START) is used as the minimum location.
1986 config RANDOMIZE_BASE
1987 bool "Randomize the address of the kernel image (KASLR)"
1988 depends on RELOCATABLE
1991 In support of Kernel Address Space Layout Randomization (KASLR),
1992 this randomizes the physical address at which the kernel image
1993 is decompressed and the virtual address where the kernel
1994 image is mapped, as a security feature that deters exploit
1995 attempts relying on knowledge of the location of kernel
1998 On 64-bit, the kernel physical and virtual addresses are
1999 randomized separately. The physical address will be anywhere
2000 between 16MB and the top of physical memory (up to 64TB). The
2001 virtual address will be randomized from 16MB up to 1GB (9 bits
2002 of entropy). Note that this also reduces the memory space
2003 available to kernel modules from 1.5GB to 1GB.
2005 On 32-bit, the kernel physical and virtual addresses are
2006 randomized together. They will be randomized from 16MB up to
2007 512MB (8 bits of entropy).
2009 Entropy is generated using the RDRAND instruction if it is
2010 supported. If RDTSC is supported, its value is mixed into
2011 the entropy pool as well. If neither RDRAND nor RDTSC are
2012 supported, then entropy is read from the i8254 timer. The
2013 usable entropy is limited by the kernel being built using
2014 2GB addressing, and that PHYSICAL_ALIGN must be at a
2015 minimum of 2MB. As a result, only 10 bits of entropy are
2016 theoretically possible, but the implementations are further
2017 limited due to memory layouts.
2019 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
2020 time. To enable it, boot with "kaslr" on the kernel command
2021 line (which will also disable hibernation).
2025 # Relocation on x86 needs some additional build support
2026 config X86_NEED_RELOCS
2028 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2030 config PHYSICAL_ALIGN
2031 hex "Alignment value to which kernel should be aligned"
2033 range 0x2000 0x1000000 if X86_32
2034 range 0x200000 0x1000000 if X86_64
2036 This value puts the alignment restrictions on physical address
2037 where kernel is loaded and run from. Kernel is compiled for an
2038 address which meets above alignment restriction.
2040 If bootloader loads the kernel at a non-aligned address and
2041 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2042 address aligned to above value and run from there.
2044 If bootloader loads the kernel at a non-aligned address and
2045 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2046 load address and decompress itself to the address it has been
2047 compiled for and run from there. The address for which kernel is
2048 compiled already meets above alignment restrictions. Hence the
2049 end result is that kernel runs from a physical address meeting
2050 above alignment restrictions.
2052 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2053 this value must be a multiple of 0x200000.
2055 Don't change this unless you know what you are doing.
2057 config RANDOMIZE_MEMORY
2058 bool "Randomize the kernel memory sections"
2060 depends on RANDOMIZE_BASE
2061 default RANDOMIZE_BASE
2063 Randomizes the base virtual address of kernel memory sections
2064 (physical memory mapping, vmalloc & vmemmap). This security feature
2065 makes exploits relying on predictable memory locations less reliable.
2067 The order of allocations remains unchanged. Entropy is generated in
2068 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2069 configuration have in average 30,000 different possible virtual
2070 addresses for each memory section.
2074 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2075 hex "Physical memory mapping padding" if EXPERT
2076 depends on RANDOMIZE_MEMORY
2077 default "0xa" if MEMORY_HOTPLUG
2079 range 0x1 0x40 if MEMORY_HOTPLUG
2082 Define the padding in terabytes added to the existing physical
2083 memory size during kernel memory randomization. It is useful
2084 for memory hotplug support but reduces the entropy available for
2085 address randomization.
2087 If unsure, leave at the default value.
2093 config BOOTPARAM_HOTPLUG_CPU0
2094 bool "Set default setting of cpu0_hotpluggable"
2096 depends on HOTPLUG_CPU
2098 Set whether default state of cpu0_hotpluggable is on or off.
2100 Say Y here to enable CPU0 hotplug by default. If this switch
2101 is turned on, there is no need to give cpu0_hotplug kernel
2102 parameter and the CPU0 hotplug feature is enabled by default.
2104 Please note: there are two known CPU0 dependencies if you want
2105 to enable the CPU0 hotplug feature either by this switch or by
2106 cpu0_hotplug kernel parameter.
2108 First, resume from hibernate or suspend always starts from CPU0.
2109 So hibernate and suspend are prevented if CPU0 is offline.
2111 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2112 offline if any interrupt can not migrate out of CPU0. There may
2113 be other CPU0 dependencies.
2115 Please make sure the dependencies are under your control before
2116 you enable this feature.
2118 Say N if you don't want to enable CPU0 hotplug feature by default.
2119 You still can enable the CPU0 hotplug feature at boot by kernel
2120 parameter cpu0_hotplug.
2122 config DEBUG_HOTPLUG_CPU0
2124 prompt "Debug CPU0 hotplug"
2125 depends on HOTPLUG_CPU
2127 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2128 soon as possible and boots up userspace with CPU0 offlined. User
2129 can online CPU0 back after boot time.
2131 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2132 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2133 compilation or giving cpu0_hotplug kernel parameter at boot.
2139 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2140 depends on X86_32 || IA32_EMULATION
2142 Certain buggy versions of glibc will crash if they are
2143 presented with a 32-bit vDSO that is not mapped at the address
2144 indicated in its segment table.
2146 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2147 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2148 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2149 the only released version with the bug, but OpenSUSE 9
2150 contains a buggy "glibc 2.3.2".
2152 The symptom of the bug is that everything crashes on startup, saying:
2153 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2155 Saying Y here changes the default value of the vdso32 boot
2156 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2157 This works around the glibc bug but hurts performance.
2159 If unsure, say N: if you are compiling your own kernel, you
2160 are unlikely to be using a buggy version of glibc.
2163 prompt "vsyscall table for legacy applications"
2165 default LEGACY_VSYSCALL_EMULATE
2167 Legacy user code that does not know how to find the vDSO expects
2168 to be able to issue three syscalls by calling fixed addresses in
2169 kernel space. Since this location is not randomized with ASLR,
2170 it can be used to assist security vulnerability exploitation.
2172 This setting can be changed at boot time via the kernel command
2173 line parameter vsyscall=[native|emulate|none].
2175 On a system with recent enough glibc (2.14 or newer) and no
2176 static binaries, you can say None without a performance penalty
2177 to improve security.
2179 If unsure, select "Emulate".
2181 config LEGACY_VSYSCALL_NATIVE
2184 Actual executable code is located in the fixed vsyscall
2185 address mapping, implementing time() efficiently. Since
2186 this makes the mapping executable, it can be used during
2187 security vulnerability exploitation (traditionally as
2188 ROP gadgets). This configuration is not recommended.
2190 config LEGACY_VSYSCALL_EMULATE
2193 The kernel traps and emulates calls into the fixed
2194 vsyscall address mapping. This makes the mapping
2195 non-executable, but it still contains known contents,
2196 which could be used in certain rare security vulnerability
2197 exploits. This configuration is recommended when userspace
2198 still uses the vsyscall area.
2200 config LEGACY_VSYSCALL_NONE
2203 There will be no vsyscall mapping at all. This will
2204 eliminate any risk of ASLR bypass due to the vsyscall
2205 fixed address mapping. Attempts to use the vsyscalls
2206 will be reported to dmesg, so that either old or
2207 malicious userspace programs can be identified.
2212 bool "Built-in kernel command line"
2214 Allow for specifying boot arguments to the kernel at
2215 build time. On some systems (e.g. embedded ones), it is
2216 necessary or convenient to provide some or all of the
2217 kernel boot arguments with the kernel itself (that is,
2218 to not rely on the boot loader to provide them.)
2220 To compile command line arguments into the kernel,
2221 set this option to 'Y', then fill in the
2222 boot arguments in CONFIG_CMDLINE.
2224 Systems with fully functional boot loaders (i.e. non-embedded)
2225 should leave this option set to 'N'.
2228 string "Built-in kernel command string"
2229 depends on CMDLINE_BOOL
2232 Enter arguments here that should be compiled into the kernel
2233 image and used at boot time. If the boot loader provides a
2234 command line at boot time, it is appended to this string to
2235 form the full kernel command line, when the system boots.
2237 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2238 change this behavior.
2240 In most cases, the command line (whether built-in or provided
2241 by the boot loader) should specify the device for the root
2244 config CMDLINE_OVERRIDE
2245 bool "Built-in command line overrides boot loader arguments"
2246 depends on CMDLINE_BOOL
2248 Set this option to 'Y' to have the kernel ignore the boot loader
2249 command line, and use ONLY the built-in command line.
2251 This is used to work around broken boot loaders. This should
2252 be set to 'N' under normal conditions.
2254 config MODIFY_LDT_SYSCALL
2255 bool "Enable the LDT (local descriptor table)" if EXPERT
2258 Linux can allow user programs to install a per-process x86
2259 Local Descriptor Table (LDT) using the modify_ldt(2) system
2260 call. This is required to run 16-bit or segmented code such as
2261 DOSEMU or some Wine programs. It is also used by some very old
2262 threading libraries.
2264 Enabling this feature adds a small amount of overhead to
2265 context switches and increases the low-level kernel attack
2266 surface. Disabling it removes the modify_ldt(2) system call.
2268 Saying 'N' here may make sense for embedded or server kernels.
2270 source "kernel/livepatch/Kconfig"
2274 config ARCH_ENABLE_MEMORY_HOTPLUG
2276 depends on X86_64 || (X86_32 && HIGHMEM)
2278 config ARCH_ENABLE_MEMORY_HOTREMOVE
2280 depends on MEMORY_HOTPLUG
2282 config USE_PERCPU_NUMA_NODE_ID
2286 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2288 depends on X86_64 || X86_PAE
2290 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2292 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2294 menu "Power management and ACPI options"
2296 config ARCH_HIBERNATION_HEADER
2298 depends on X86_64 && HIBERNATION
2300 source "kernel/power/Kconfig"
2302 source "drivers/acpi/Kconfig"
2304 source "drivers/sfi/Kconfig"
2311 tristate "APM (Advanced Power Management) BIOS support"
2312 depends on X86_32 && PM_SLEEP
2314 APM is a BIOS specification for saving power using several different
2315 techniques. This is mostly useful for battery powered laptops with
2316 APM compliant BIOSes. If you say Y here, the system time will be
2317 reset after a RESUME operation, the /proc/apm device will provide
2318 battery status information, and user-space programs will receive
2319 notification of APM "events" (e.g. battery status change).
2321 If you select "Y" here, you can disable actual use of the APM
2322 BIOS by passing the "apm=off" option to the kernel at boot time.
2324 Note that the APM support is almost completely disabled for
2325 machines with more than one CPU.
2327 In order to use APM, you will need supporting software. For location
2328 and more information, read <file:Documentation/power/apm-acpi.txt>
2329 and the Battery Powered Linux mini-HOWTO, available from
2330 <http://www.tldp.org/docs.html#howto>.
2332 This driver does not spin down disk drives (see the hdparm(8)
2333 manpage ("man 8 hdparm") for that), and it doesn't turn off
2334 VESA-compliant "green" monitors.
2336 This driver does not support the TI 4000M TravelMate and the ACER
2337 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2338 desktop machines also don't have compliant BIOSes, and this driver
2339 may cause those machines to panic during the boot phase.
2341 Generally, if you don't have a battery in your machine, there isn't
2342 much point in using this driver and you should say N. If you get
2343 random kernel OOPSes or reboots that don't seem to be related to
2344 anything, try disabling/enabling this option (or disabling/enabling
2347 Some other things you should try when experiencing seemingly random,
2350 1) make sure that you have enough swap space and that it is
2352 2) pass the "no-hlt" option to the kernel
2353 3) switch on floating point emulation in the kernel and pass
2354 the "no387" option to the kernel
2355 4) pass the "floppy=nodma" option to the kernel
2356 5) pass the "mem=4M" option to the kernel (thereby disabling
2357 all but the first 4 MB of RAM)
2358 6) make sure that the CPU is not over clocked.
2359 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2360 8) disable the cache from your BIOS settings
2361 9) install a fan for the video card or exchange video RAM
2362 10) install a better fan for the CPU
2363 11) exchange RAM chips
2364 12) exchange the motherboard.
2366 To compile this driver as a module, choose M here: the
2367 module will be called apm.
2371 config APM_IGNORE_USER_SUSPEND
2372 bool "Ignore USER SUSPEND"
2374 This option will ignore USER SUSPEND requests. On machines with a
2375 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2376 series notebooks, it is necessary to say Y because of a BIOS bug.
2378 config APM_DO_ENABLE
2379 bool "Enable PM at boot time"
2381 Enable APM features at boot time. From page 36 of the APM BIOS
2382 specification: "When disabled, the APM BIOS does not automatically
2383 power manage devices, enter the Standby State, enter the Suspend
2384 State, or take power saving steps in response to CPU Idle calls."
2385 This driver will make CPU Idle calls when Linux is idle (unless this
2386 feature is turned off -- see "Do CPU IDLE calls", below). This
2387 should always save battery power, but more complicated APM features
2388 will be dependent on your BIOS implementation. You may need to turn
2389 this option off if your computer hangs at boot time when using APM
2390 support, or if it beeps continuously instead of suspending. Turn
2391 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2392 T400CDT. This is off by default since most machines do fine without
2397 bool "Make CPU Idle calls when idle"
2399 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2400 On some machines, this can activate improved power savings, such as
2401 a slowed CPU clock rate, when the machine is idle. These idle calls
2402 are made after the idle loop has run for some length of time (e.g.,
2403 333 mS). On some machines, this will cause a hang at boot time or
2404 whenever the CPU becomes idle. (On machines with more than one CPU,
2405 this option does nothing.)
2407 config APM_DISPLAY_BLANK
2408 bool "Enable console blanking using APM"
2410 Enable console blanking using the APM. Some laptops can use this to
2411 turn off the LCD backlight when the screen blanker of the Linux
2412 virtual console blanks the screen. Note that this is only used by
2413 the virtual console screen blanker, and won't turn off the backlight
2414 when using the X Window system. This also doesn't have anything to
2415 do with your VESA-compliant power-saving monitor. Further, this
2416 option doesn't work for all laptops -- it might not turn off your
2417 backlight at all, or it might print a lot of errors to the console,
2418 especially if you are using gpm.
2420 config APM_ALLOW_INTS
2421 bool "Allow interrupts during APM BIOS calls"
2423 Normally we disable external interrupts while we are making calls to
2424 the APM BIOS as a measure to lessen the effects of a badly behaving
2425 BIOS implementation. The BIOS should reenable interrupts if it
2426 needs to. Unfortunately, some BIOSes do not -- especially those in
2427 many of the newer IBM Thinkpads. If you experience hangs when you
2428 suspend, try setting this to Y. Otherwise, say N.
2432 source "drivers/cpufreq/Kconfig"
2434 source "drivers/cpuidle/Kconfig"
2436 source "drivers/idle/Kconfig"
2441 menu "Bus options (PCI etc.)"
2447 Find out whether you have a PCI motherboard. PCI is the name of a
2448 bus system, i.e. the way the CPU talks to the other stuff inside
2449 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2450 VESA. If you have PCI, say Y, otherwise N.
2453 prompt "PCI access mode"
2454 depends on X86_32 && PCI
2457 On PCI systems, the BIOS can be used to detect the PCI devices and
2458 determine their configuration. However, some old PCI motherboards
2459 have BIOS bugs and may crash if this is done. Also, some embedded
2460 PCI-based systems don't have any BIOS at all. Linux can also try to
2461 detect the PCI hardware directly without using the BIOS.
2463 With this option, you can specify how Linux should detect the
2464 PCI devices. If you choose "BIOS", the BIOS will be used,
2465 if you choose "Direct", the BIOS won't be used, and if you
2466 choose "MMConfig", then PCI Express MMCONFIG will be used.
2467 If you choose "Any", the kernel will try MMCONFIG, then the
2468 direct access method and falls back to the BIOS if that doesn't
2469 work. If unsure, go with the default, which is "Any".
2474 config PCI_GOMMCONFIG
2491 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2493 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2496 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2500 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2504 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2508 depends on PCI && XEN
2516 bool "Support mmconfig PCI config space access"
2517 depends on X86_64 && PCI && ACPI
2519 config PCI_CNB20LE_QUIRK
2520 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2523 Read the PCI windows out of the CNB20LE host bridge. This allows
2524 PCI hotplug to work on systems with the CNB20LE chipset which do
2527 There's no public spec for this chipset, and this functionality
2528 is known to be incomplete.
2530 You should say N unless you know you need this.
2532 source "drivers/pci/Kconfig"
2535 bool "ISA-style bus support on modern systems" if EXPERT
2538 Enables ISA-style drivers on modern systems. This is necessary to
2539 support PC/104 devices on X86_64 platforms.
2543 # x86_64 have no ISA slots, but can have ISA-style DMA.
2545 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2548 Enables ISA-style DMA support for devices requiring such controllers.
2556 Find out whether you have ISA slots on your motherboard. ISA is the
2557 name of a bus system, i.e. the way the CPU talks to the other stuff
2558 inside your box. Other bus systems are PCI, EISA, MicroChannel
2559 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2560 newer boards don't support it. If you have ISA, say Y, otherwise N.
2566 The Extended Industry Standard Architecture (EISA) bus was
2567 developed as an open alternative to the IBM MicroChannel bus.
2569 The EISA bus provided some of the features of the IBM MicroChannel
2570 bus while maintaining backward compatibility with cards made for
2571 the older ISA bus. The EISA bus saw limited use between 1988 and
2572 1995 when it was made obsolete by the PCI bus.
2574 Say Y here if you are building a kernel for an EISA-based machine.
2578 source "drivers/eisa/Kconfig"
2581 tristate "NatSemi SCx200 support"
2583 This provides basic support for National Semiconductor's
2584 (now AMD's) Geode processors. The driver probes for the
2585 PCI-IDs of several on-chip devices, so its a good dependency
2586 for other scx200_* drivers.
2588 If compiled as a module, the driver is named scx200.
2590 config SCx200HR_TIMER
2591 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2595 This driver provides a clocksource built upon the on-chip
2596 27MHz high-resolution timer. Its also a workaround for
2597 NSC Geode SC-1100's buggy TSC, which loses time when the
2598 processor goes idle (as is done by the scheduler). The
2599 other workaround is idle=poll boot option.
2602 bool "One Laptop Per Child support"
2609 Add support for detecting the unique features of the OLPC
2613 bool "OLPC XO-1 Power Management"
2614 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2616 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2619 bool "OLPC XO-1 Real Time Clock"
2620 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2622 Add support for the XO-1 real time clock, which can be used as a
2623 programmable wakeup source.
2626 bool "OLPC XO-1 SCI extras"
2627 depends on OLPC && OLPC_XO1_PM
2633 Add support for SCI-based features of the OLPC XO-1 laptop:
2634 - EC-driven system wakeups
2638 - AC adapter status updates
2639 - Battery status updates
2641 config OLPC_XO15_SCI
2642 bool "OLPC XO-1.5 SCI extras"
2643 depends on OLPC && ACPI
2646 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2647 - EC-driven system wakeups
2648 - AC adapter status updates
2649 - Battery status updates
2652 bool "PCEngines ALIX System Support (LED setup)"
2655 This option enables system support for the PCEngines ALIX.
2656 At present this just sets up LEDs for GPIO control on
2657 ALIX2/3/6 boards. However, other system specific setup should
2660 Note: You must still enable the drivers for GPIO and LED support
2661 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2663 Note: You have to set alix.force=1 for boards with Award BIOS.
2666 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2669 This option enables system support for the Soekris Engineering net5501.
2672 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2676 This option enables system support for the Traverse Technologies GEOS.
2679 bool "Technologic Systems TS-5500 platform support"
2681 select CHECK_SIGNATURE
2685 This option enables system support for the Technologic Systems TS-5500.
2691 depends on CPU_SUP_AMD && PCI
2693 source "drivers/pcmcia/Kconfig"
2696 tristate "RapidIO support"
2700 If enabled this option will include drivers and the core
2701 infrastructure code to support RapidIO interconnect devices.
2703 source "drivers/rapidio/Kconfig"
2706 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2708 Firmwares often provide initial graphics framebuffers so the BIOS,
2709 bootloader or kernel can show basic video-output during boot for
2710 user-guidance and debugging. Historically, x86 used the VESA BIOS
2711 Extensions and EFI-framebuffers for this, which are mostly limited
2713 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2714 framebuffers so the new generic system-framebuffer drivers can be
2715 used on x86. If the framebuffer is not compatible with the generic
2716 modes, it is adverticed as fallback platform framebuffer so legacy
2717 drivers like efifb, vesafb and uvesafb can pick it up.
2718 If this option is not selected, all system framebuffers are always
2719 marked as fallback platform framebuffers as usual.
2721 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2722 not be able to pick up generic system framebuffers if this option
2723 is selected. You are highly encouraged to enable simplefb as
2724 replacement if you select this option. simplefb can correctly deal
2725 with generic system framebuffers. But you should still keep vesafb
2726 and others enabled as fallback if a system framebuffer is
2727 incompatible with simplefb.
2734 menu "Executable file formats / Emulations"
2736 source "fs/Kconfig.binfmt"
2738 config IA32_EMULATION
2739 bool "IA32 Emulation"
2742 select COMPAT_BINFMT_ELF
2743 select ARCH_WANT_OLD_COMPAT_IPC
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_X32
2773 config COMPAT_FOR_U64_ALIGNMENT
2776 config SYSVIPC_COMPAT
2784 config HAVE_ATOMIC_IOMAP
2788 config X86_DEV_DMA_OPS
2790 depends on X86_64 || STA2X11
2792 config X86_DMA_REMAP
2800 source "net/Kconfig"
2802 source "drivers/Kconfig"
2804 source "drivers/firmware/Kconfig"
2808 source "arch/x86/Kconfig.debug"
2810 source "security/Kconfig"
2812 source "crypto/Kconfig"
2814 source "arch/x86/kvm/Kconfig"
2816 source "lib/Kconfig"