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.
421 Without compiler support, at least indirect branches in assembler
422 code are eliminated. Since this includes the syscall entry path,
423 it is not entirely pointless.
426 config X86_EXTENDED_PLATFORM
427 bool "Support for extended (non-PC) x86 platforms"
430 If you disable this option then the kernel will only support
431 standard PC platforms. (which covers the vast majority of
434 If you enable this option then you'll be able to select support
435 for the following (non-PC) 32 bit x86 platforms:
436 Goldfish (Android emulator)
439 SGI 320/540 (Visual Workstation)
440 STA2X11-based (e.g. Northville)
441 Moorestown MID devices
443 If you have one of these systems, or if you want to build a
444 generic distribution kernel, say Y here - otherwise say N.
448 config X86_EXTENDED_PLATFORM
449 bool "Support for extended (non-PC) x86 platforms"
452 If you disable this option then the kernel will only support
453 standard PC platforms. (which covers the vast majority of
456 If you enable this option then you'll be able to select support
457 for the following (non-PC) 64 bit x86 platforms:
462 If you have one of these systems, or if you want to build a
463 generic distribution kernel, say Y here - otherwise say N.
465 # This is an alphabetically sorted list of 64 bit extended platforms
466 # Please maintain the alphabetic order if and when there are additions
468 bool "Numascale NumaChip"
470 depends on X86_EXTENDED_PLATFORM
473 depends on X86_X2APIC
474 depends on PCI_MMCONFIG
476 Adds support for Numascale NumaChip large-SMP systems. Needed to
477 enable more than ~168 cores.
478 If you don't have one of these, you should say N here.
482 select HYPERVISOR_GUEST
484 depends on X86_64 && PCI
485 depends on X86_EXTENDED_PLATFORM
488 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
489 supposed to run on these EM64T-based machines. Only choose this option
490 if you have one of these machines.
493 bool "SGI Ultraviolet"
495 depends on X86_EXTENDED_PLATFORM
498 depends on KEXEC_CORE
499 depends on X86_X2APIC
502 This option is needed in order to support SGI Ultraviolet systems.
503 If you don't have one of these, you should say N here.
505 # Following is an alphabetically sorted list of 32 bit extended platforms
506 # Please maintain the alphabetic order if and when there are additions
509 bool "Goldfish (Virtual Platform)"
510 depends on X86_EXTENDED_PLATFORM
512 Enable support for the Goldfish virtual platform used primarily
513 for Android development. Unless you are building for the Android
514 Goldfish emulator say N here.
517 bool "CE4100 TV platform"
519 depends on PCI_GODIRECT
520 depends on X86_IO_APIC
522 depends on X86_EXTENDED_PLATFORM
523 select X86_REBOOTFIXUPS
525 select OF_EARLY_FLATTREE
527 Select for the Intel CE media processor (CE4100) SOC.
528 This option compiles in support for the CE4100 SOC for settop
529 boxes and media devices.
532 bool "Intel MID platform support"
533 depends on X86_EXTENDED_PLATFORM
534 depends on X86_PLATFORM_DEVICES
536 depends on X86_64 || (PCI_GOANY && X86_32)
537 depends on X86_IO_APIC
543 select MFD_INTEL_MSIC
545 Select to build a kernel capable of supporting Intel MID (Mobile
546 Internet Device) platform systems which do not have the PCI legacy
547 interfaces. If you are building for a PC class system say N here.
549 Intel MID platforms are based on an Intel processor and chipset which
550 consume less power than most of the x86 derivatives.
552 config X86_INTEL_QUARK
553 bool "Intel Quark platform support"
555 depends on X86_EXTENDED_PLATFORM
556 depends on X86_PLATFORM_DEVICES
560 depends on X86_IO_APIC
565 Select to include support for Quark X1000 SoC.
566 Say Y here if you have a Quark based system such as the Arduino
567 compatible Intel Galileo.
570 tristate "Mellanox Technologies platform support"
572 depends on X86_EXTENDED_PLATFORM
574 This option enables system support for the Mellanox Technologies
577 Say Y here if you are building a kernel for Mellanox system.
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.
945 prompt "Multi-core scheduler support"
948 Multi-core scheduler support improves the CPU scheduler's decision
949 making when dealing with multi-core CPU chips at a cost of slightly
950 increased overhead in some places. If unsure say N here.
952 source "kernel/Kconfig.preempt"
956 depends on !SMP && X86_LOCAL_APIC
959 bool "Local APIC support on uniprocessors" if !PCI_MSI
961 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
963 A local APIC (Advanced Programmable Interrupt Controller) is an
964 integrated interrupt controller in the CPU. If you have a single-CPU
965 system which has a processor with a local APIC, you can say Y here to
966 enable and use it. If you say Y here even though your machine doesn't
967 have a local APIC, then the kernel will still run with no slowdown at
968 all. The local APIC supports CPU-generated self-interrupts (timer,
969 performance counters), and the NMI watchdog which detects hard
973 bool "IO-APIC support on uniprocessors"
974 depends on X86_UP_APIC
976 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
977 SMP-capable replacement for PC-style interrupt controllers. Most
978 SMP systems and many recent uniprocessor systems have one.
980 If you have a single-CPU system with an IO-APIC, you can say Y here
981 to use it. If you say Y here even though your machine doesn't have
982 an IO-APIC, then the kernel will still run with no slowdown at all.
984 config X86_LOCAL_APIC
986 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
987 select IRQ_DOMAIN_HIERARCHY
988 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
992 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
994 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
995 bool "Reroute for broken boot IRQs"
996 depends on X86_IO_APIC
998 This option enables a workaround that fixes a source of
999 spurious interrupts. This is recommended when threaded
1000 interrupt handling is used on systems where the generation of
1001 superfluous "boot interrupts" cannot be disabled.
1003 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1004 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1005 kernel does during interrupt handling). On chipsets where this
1006 boot IRQ generation cannot be disabled, this workaround keeps
1007 the original IRQ line masked so that only the equivalent "boot
1008 IRQ" is delivered to the CPUs. The workaround also tells the
1009 kernel to set up the IRQ handler on the boot IRQ line. In this
1010 way only one interrupt is delivered to the kernel. Otherwise
1011 the spurious second interrupt may cause the kernel to bring
1012 down (vital) interrupt lines.
1014 Only affects "broken" chipsets. Interrupt sharing may be
1015 increased on these systems.
1018 bool "Machine Check / overheating reporting"
1019 select GENERIC_ALLOCATOR
1022 Machine Check support allows the processor to notify the
1023 kernel if it detects a problem (e.g. overheating, data corruption).
1024 The action the kernel takes depends on the severity of the problem,
1025 ranging from warning messages to halting the machine.
1027 config X86_MCE_INTEL
1029 prompt "Intel MCE features"
1030 depends on X86_MCE && X86_LOCAL_APIC
1032 Additional support for intel specific MCE features such as
1033 the thermal monitor.
1037 prompt "AMD MCE features"
1038 depends on X86_MCE && X86_LOCAL_APIC
1040 Additional support for AMD specific MCE features such as
1041 the DRAM Error Threshold.
1043 config X86_ANCIENT_MCE
1044 bool "Support for old Pentium 5 / WinChip machine checks"
1045 depends on X86_32 && X86_MCE
1047 Include support for machine check handling on old Pentium 5 or WinChip
1048 systems. These typically need to be enabled explicitly on the command
1051 config X86_MCE_THRESHOLD
1052 depends on X86_MCE_AMD || X86_MCE_INTEL
1055 config X86_MCE_INJECT
1056 depends on X86_MCE && X86_LOCAL_APIC
1057 tristate "Machine check injector support"
1059 Provide support for injecting machine checks for testing purposes.
1060 If you don't know what a machine check is and you don't do kernel
1061 QA it is safe to say n.
1063 config X86_THERMAL_VECTOR
1065 depends on X86_MCE_INTEL
1067 source "arch/x86/events/Kconfig"
1069 config X86_LEGACY_VM86
1070 bool "Legacy VM86 support"
1074 This option allows user programs to put the CPU into V8086
1075 mode, which is an 80286-era approximation of 16-bit real mode.
1077 Some very old versions of X and/or vbetool require this option
1078 for user mode setting. Similarly, DOSEMU will use it if
1079 available to accelerate real mode DOS programs. However, any
1080 recent version of DOSEMU, X, or vbetool should be fully
1081 functional even without kernel VM86 support, as they will all
1082 fall back to software emulation. Nevertheless, if you are using
1083 a 16-bit DOS program where 16-bit performance matters, vm86
1084 mode might be faster than emulation and you might want to
1087 Note that any app that works on a 64-bit kernel is unlikely to
1088 need this option, as 64-bit kernels don't, and can't, support
1089 V8086 mode. This option is also unrelated to 16-bit protected
1090 mode and is not needed to run most 16-bit programs under Wine.
1092 Enabling this option increases the complexity of the kernel
1093 and slows down exception handling a tiny bit.
1095 If unsure, say N here.
1099 default X86_LEGACY_VM86
1102 bool "Enable support for 16-bit segments" if EXPERT
1104 depends on MODIFY_LDT_SYSCALL
1106 This option is required by programs like Wine to run 16-bit
1107 protected mode legacy code on x86 processors. Disabling
1108 this option saves about 300 bytes on i386, or around 6K text
1109 plus 16K runtime memory on x86-64,
1113 depends on X86_16BIT && X86_32
1117 depends on X86_16BIT && X86_64
1119 config X86_VSYSCALL_EMULATION
1120 bool "Enable vsyscall emulation" if EXPERT
1124 This enables emulation of the legacy vsyscall page. Disabling
1125 it is roughly equivalent to booting with vsyscall=none, except
1126 that it will also disable the helpful warning if a program
1127 tries to use a vsyscall. With this option set to N, offending
1128 programs will just segfault, citing addresses of the form
1131 This option is required by many programs built before 2013, and
1132 care should be used even with newer programs if set to N.
1134 Disabling this option saves about 7K of kernel size and
1135 possibly 4K of additional runtime pagetable memory.
1138 tristate "Toshiba Laptop support"
1141 This adds a driver to safely access the System Management Mode of
1142 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1143 not work on models with a Phoenix BIOS. The System Management Mode
1144 is used to set the BIOS and power saving options on Toshiba portables.
1146 For information on utilities to make use of this driver see the
1147 Toshiba Linux utilities web site at:
1148 <http://www.buzzard.org.uk/toshiba/>.
1150 Say Y if you intend to run this kernel on a Toshiba portable.
1154 tristate "Dell i8k legacy laptop support"
1156 select SENSORS_DELL_SMM
1158 This option enables legacy /proc/i8k userspace interface in hwmon
1159 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1160 temperature and allows controlling fan speeds of Dell laptops via
1161 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1162 it reports also power and hotkey status. For fan speed control is
1163 needed userspace package i8kutils.
1165 Say Y if you intend to run this kernel on old Dell laptops or want to
1166 use userspace package i8kutils.
1169 config X86_REBOOTFIXUPS
1170 bool "Enable X86 board specific fixups for reboot"
1173 This enables chipset and/or board specific fixups to be done
1174 in order to get reboot to work correctly. This is only needed on
1175 some combinations of hardware and BIOS. The symptom, for which
1176 this config is intended, is when reboot ends with a stalled/hung
1179 Currently, the only fixup is for the Geode machines using
1180 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1182 Say Y if you want to enable the fixup. Currently, it's safe to
1183 enable this option even if you don't need it.
1187 bool "CPU microcode loading support"
1189 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1192 If you say Y here, you will be able to update the microcode on
1193 Intel and AMD processors. The Intel support is for the IA32 family,
1194 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1195 AMD support is for families 0x10 and later. You will obviously need
1196 the actual microcode binary data itself which is not shipped with
1199 The preferred method to load microcode from a detached initrd is described
1200 in Documentation/x86/early-microcode.txt. For that you need to enable
1201 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1202 initrd for microcode blobs.
1204 In addition, you can build-in the microcode into the kernel. For that you
1205 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1206 to the CONFIG_EXTRA_FIRMWARE config option.
1208 config MICROCODE_INTEL
1209 bool "Intel microcode loading support"
1210 depends on MICROCODE
1214 This options enables microcode patch loading support for Intel
1217 For the current Intel microcode data package go to
1218 <https://downloadcenter.intel.com> and search for
1219 'Linux Processor Microcode Data File'.
1221 config MICROCODE_AMD
1222 bool "AMD microcode loading support"
1223 depends on MICROCODE
1226 If you select this option, microcode patch loading support for AMD
1227 processors will be enabled.
1229 config MICROCODE_OLD_INTERFACE
1231 depends on MICROCODE
1234 tristate "/dev/cpu/*/msr - Model-specific register support"
1236 This device gives privileged processes access to the x86
1237 Model-Specific Registers (MSRs). It is a character device with
1238 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1239 MSR accesses are directed to a specific CPU on multi-processor
1243 tristate "/dev/cpu/*/cpuid - CPU information support"
1245 This device gives processes access to the x86 CPUID instruction to
1246 be executed on a specific processor. It is a character device
1247 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1251 prompt "High Memory Support"
1258 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1259 However, the address space of 32-bit x86 processors is only 4
1260 Gigabytes large. That means that, if you have a large amount of
1261 physical memory, not all of it can be "permanently mapped" by the
1262 kernel. The physical memory that's not permanently mapped is called
1265 If you are compiling a kernel which will never run on a machine with
1266 more than 1 Gigabyte total physical RAM, answer "off" here (default
1267 choice and suitable for most users). This will result in a "3GB/1GB"
1268 split: 3GB are mapped so that each process sees a 3GB virtual memory
1269 space and the remaining part of the 4GB virtual memory space is used
1270 by the kernel to permanently map as much physical memory as
1273 If the machine has between 1 and 4 Gigabytes physical RAM, then
1276 If more than 4 Gigabytes is used then answer "64GB" here. This
1277 selection turns Intel PAE (Physical Address Extension) mode on.
1278 PAE implements 3-level paging on IA32 processors. PAE is fully
1279 supported by Linux, PAE mode is implemented on all recent Intel
1280 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1281 then the kernel will not boot on CPUs that don't support PAE!
1283 The actual amount of total physical memory will either be
1284 auto detected or can be forced by using a kernel command line option
1285 such as "mem=256M". (Try "man bootparam" or see the documentation of
1286 your boot loader (lilo or loadlin) about how to pass options to the
1287 kernel at boot time.)
1289 If unsure, say "off".
1294 Select this if you have a 32-bit processor and between 1 and 4
1295 gigabytes of physical RAM.
1302 Select this if you have a 32-bit processor and more than 4
1303 gigabytes of physical RAM.
1308 prompt "Memory split" if EXPERT
1312 Select the desired split between kernel and user memory.
1314 If the address range available to the kernel is less than the
1315 physical memory installed, the remaining memory will be available
1316 as "high memory". Accessing high memory is a little more costly
1317 than low memory, as it needs to be mapped into the kernel first.
1318 Note that increasing the kernel address space limits the range
1319 available to user programs, making the address space there
1320 tighter. Selecting anything other than the default 3G/1G split
1321 will also likely make your kernel incompatible with binary-only
1324 If you are not absolutely sure what you are doing, leave this
1328 bool "3G/1G user/kernel split"
1329 config VMSPLIT_3G_OPT
1331 bool "3G/1G user/kernel split (for full 1G low memory)"
1333 bool "2G/2G user/kernel split"
1334 config VMSPLIT_2G_OPT
1336 bool "2G/2G user/kernel split (for full 2G low memory)"
1338 bool "1G/3G user/kernel split"
1343 default 0xB0000000 if VMSPLIT_3G_OPT
1344 default 0x80000000 if VMSPLIT_2G
1345 default 0x78000000 if VMSPLIT_2G_OPT
1346 default 0x40000000 if VMSPLIT_1G
1352 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1355 bool "PAE (Physical Address Extension) Support"
1356 depends on X86_32 && !HIGHMEM4G
1359 PAE is required for NX support, and furthermore enables
1360 larger swapspace support for non-overcommit purposes. It
1361 has the cost of more pagetable lookup overhead, and also
1362 consumes more pagetable space per process.
1364 config ARCH_PHYS_ADDR_T_64BIT
1366 depends on X86_64 || X86_PAE
1368 config ARCH_DMA_ADDR_T_64BIT
1370 depends on X86_64 || HIGHMEM64G
1372 config X86_DIRECT_GBPAGES
1374 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1376 Certain kernel features effectively disable kernel
1377 linear 1 GB mappings (even if the CPU otherwise
1378 supports them), so don't confuse the user by printing
1379 that we have them enabled.
1381 # Common NUMA Features
1383 bool "Numa Memory Allocation and Scheduler Support"
1385 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1386 default y if X86_BIGSMP
1388 Enable NUMA (Non Uniform Memory Access) support.
1390 The kernel will try to allocate memory used by a CPU on the
1391 local memory controller of the CPU and add some more
1392 NUMA awareness to the kernel.
1394 For 64-bit this is recommended if the system is Intel Core i7
1395 (or later), AMD Opteron, or EM64T NUMA.
1397 For 32-bit this is only needed if you boot a 32-bit
1398 kernel on a 64-bit NUMA platform.
1400 Otherwise, you should say N.
1404 prompt "Old style AMD Opteron NUMA detection"
1405 depends on X86_64 && NUMA && PCI
1407 Enable AMD NUMA node topology detection. You should say Y here if
1408 you have a multi processor AMD system. This uses an old method to
1409 read the NUMA configuration directly from the builtin Northbridge
1410 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1411 which also takes priority if both are compiled in.
1413 config X86_64_ACPI_NUMA
1415 prompt "ACPI NUMA detection"
1416 depends on X86_64 && NUMA && ACPI && PCI
1419 Enable ACPI SRAT based node topology detection.
1421 # Some NUMA nodes have memory ranges that span
1422 # other nodes. Even though a pfn is valid and
1423 # between a node's start and end pfns, it may not
1424 # reside on that node. See memmap_init_zone()
1426 config NODES_SPAN_OTHER_NODES
1428 depends on X86_64_ACPI_NUMA
1431 bool "NUMA emulation"
1434 Enable NUMA emulation. A flat machine will be split
1435 into virtual nodes when booted with "numa=fake=N", where N is the
1436 number of nodes. This is only useful for debugging.
1439 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1441 default "10" if MAXSMP
1442 default "6" if X86_64
1444 depends on NEED_MULTIPLE_NODES
1446 Specify the maximum number of NUMA Nodes available on the target
1447 system. Increases memory reserved to accommodate various tables.
1449 config ARCH_HAVE_MEMORY_PRESENT
1451 depends on X86_32 && DISCONTIGMEM
1453 config NEED_NODE_MEMMAP_SIZE
1455 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1457 config ARCH_FLATMEM_ENABLE
1459 depends on X86_32 && !NUMA
1461 config ARCH_DISCONTIGMEM_ENABLE
1463 depends on NUMA && X86_32
1465 config ARCH_DISCONTIGMEM_DEFAULT
1467 depends on NUMA && X86_32
1469 config ARCH_SPARSEMEM_ENABLE
1471 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1472 select SPARSEMEM_STATIC if X86_32
1473 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1475 config ARCH_SPARSEMEM_DEFAULT
1479 config ARCH_SELECT_MEMORY_MODEL
1481 depends on ARCH_SPARSEMEM_ENABLE
1483 config ARCH_MEMORY_PROBE
1484 bool "Enable sysfs memory/probe interface"
1485 depends on X86_64 && MEMORY_HOTPLUG
1487 This option enables a sysfs memory/probe interface for testing.
1488 See Documentation/memory-hotplug.txt for more information.
1489 If you are unsure how to answer this question, answer N.
1491 config ARCH_PROC_KCORE_TEXT
1493 depends on X86_64 && PROC_KCORE
1495 config ILLEGAL_POINTER_VALUE
1498 default 0xdead000000000000 if X86_64
1502 config X86_PMEM_LEGACY_DEVICE
1505 config X86_PMEM_LEGACY
1506 tristate "Support non-standard NVDIMMs and ADR protected memory"
1507 depends on PHYS_ADDR_T_64BIT
1509 select X86_PMEM_LEGACY_DEVICE
1512 Treat memory marked using the non-standard e820 type of 12 as used
1513 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1514 The kernel will offer these regions to the 'pmem' driver so
1515 they can be used for persistent storage.
1520 bool "Allocate 3rd-level pagetables from highmem"
1523 The VM uses one page table entry for each page of physical memory.
1524 For systems with a lot of RAM, this can be wasteful of precious
1525 low memory. Setting this option will put user-space page table
1526 entries in high memory.
1528 config X86_CHECK_BIOS_CORRUPTION
1529 bool "Check for low memory corruption"
1531 Periodically check for memory corruption in low memory, which
1532 is suspected to be caused by BIOS. Even when enabled in the
1533 configuration, it is disabled at runtime. Enable it by
1534 setting "memory_corruption_check=1" on the kernel command
1535 line. By default it scans the low 64k of memory every 60
1536 seconds; see the memory_corruption_check_size and
1537 memory_corruption_check_period parameters in
1538 Documentation/kernel-parameters.txt to adjust this.
1540 When enabled with the default parameters, this option has
1541 almost no overhead, as it reserves a relatively small amount
1542 of memory and scans it infrequently. It both detects corruption
1543 and prevents it from affecting the running system.
1545 It is, however, intended as a diagnostic tool; if repeatable
1546 BIOS-originated corruption always affects the same memory,
1547 you can use memmap= to prevent the kernel from using that
1550 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1551 bool "Set the default setting of memory_corruption_check"
1552 depends on X86_CHECK_BIOS_CORRUPTION
1555 Set whether the default state of memory_corruption_check is
1558 config X86_RESERVE_LOW
1559 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1563 Specify the amount of low memory to reserve for the BIOS.
1565 The first page contains BIOS data structures that the kernel
1566 must not use, so that page must always be reserved.
1568 By default we reserve the first 64K of physical RAM, as a
1569 number of BIOSes are known to corrupt that memory range
1570 during events such as suspend/resume or monitor cable
1571 insertion, so it must not be used by the kernel.
1573 You can set this to 4 if you are absolutely sure that you
1574 trust the BIOS to get all its memory reservations and usages
1575 right. If you know your BIOS have problems beyond the
1576 default 64K area, you can set this to 640 to avoid using the
1577 entire low memory range.
1579 If you have doubts about the BIOS (e.g. suspend/resume does
1580 not work or there's kernel crashes after certain hardware
1581 hotplug events) then you might want to enable
1582 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1583 typical corruption patterns.
1585 Leave this to the default value of 64 if you are unsure.
1587 config MATH_EMULATION
1589 depends on MODIFY_LDT_SYSCALL
1590 prompt "Math emulation" if X86_32
1592 Linux can emulate a math coprocessor (used for floating point
1593 operations) if you don't have one. 486DX and Pentium processors have
1594 a math coprocessor built in, 486SX and 386 do not, unless you added
1595 a 487DX or 387, respectively. (The messages during boot time can
1596 give you some hints here ["man dmesg"].) Everyone needs either a
1597 coprocessor or this emulation.
1599 If you don't have a math coprocessor, you need to say Y here; if you
1600 say Y here even though you have a coprocessor, the coprocessor will
1601 be used nevertheless. (This behavior can be changed with the kernel
1602 command line option "no387", which comes handy if your coprocessor
1603 is broken. Try "man bootparam" or see the documentation of your boot
1604 loader (lilo or loadlin) about how to pass options to the kernel at
1605 boot time.) This means that it is a good idea to say Y here if you
1606 intend to use this kernel on different machines.
1608 More information about the internals of the Linux math coprocessor
1609 emulation can be found in <file:arch/x86/math-emu/README>.
1611 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1612 kernel, it won't hurt.
1616 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1618 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1619 the Memory Type Range Registers (MTRRs) may be used to control
1620 processor access to memory ranges. This is most useful if you have
1621 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1622 allows bus write transfers to be combined into a larger transfer
1623 before bursting over the PCI/AGP bus. This can increase performance
1624 of image write operations 2.5 times or more. Saying Y here creates a
1625 /proc/mtrr file which may be used to manipulate your processor's
1626 MTRRs. Typically the X server should use this.
1628 This code has a reasonably generic interface so that similar
1629 control registers on other processors can be easily supported
1632 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1633 Registers (ARRs) which provide a similar functionality to MTRRs. For
1634 these, the ARRs are used to emulate the MTRRs.
1635 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1636 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1637 write-combining. All of these processors are supported by this code
1638 and it makes sense to say Y here if you have one of them.
1640 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1641 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1642 can lead to all sorts of problems, so it's good to say Y here.
1644 You can safely say Y even if your machine doesn't have MTRRs, you'll
1645 just add about 9 KB to your kernel.
1647 See <file:Documentation/x86/mtrr.txt> for more information.
1649 config MTRR_SANITIZER
1651 prompt "MTRR cleanup support"
1654 Convert MTRR layout from continuous to discrete, so X drivers can
1655 add writeback entries.
1657 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1658 The largest mtrr entry size for a continuous block can be set with
1663 config MTRR_SANITIZER_ENABLE_DEFAULT
1664 int "MTRR cleanup enable value (0-1)"
1667 depends on MTRR_SANITIZER
1669 Enable mtrr cleanup default value
1671 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1672 int "MTRR cleanup spare reg num (0-7)"
1675 depends on MTRR_SANITIZER
1677 mtrr cleanup spare entries default, it can be changed via
1678 mtrr_spare_reg_nr=N on the kernel command line.
1682 prompt "x86 PAT support" if EXPERT
1685 Use PAT attributes to setup page level cache control.
1687 PATs are the modern equivalents of MTRRs and are much more
1688 flexible than MTRRs.
1690 Say N here if you see bootup problems (boot crash, boot hang,
1691 spontaneous reboots) or a non-working video driver.
1695 config ARCH_USES_PG_UNCACHED
1701 prompt "x86 architectural random number generator" if EXPERT
1703 Enable the x86 architectural RDRAND instruction
1704 (Intel Bull Mountain technology) to generate random numbers.
1705 If supported, this is a high bandwidth, cryptographically
1706 secure hardware random number generator.
1710 prompt "Supervisor Mode Access Prevention" if EXPERT
1712 Supervisor Mode Access Prevention (SMAP) is a security
1713 feature in newer Intel processors. There is a small
1714 performance cost if this enabled and turned on; there is
1715 also a small increase in the kernel size if this is enabled.
1719 config X86_INTEL_MPX
1720 prompt "Intel MPX (Memory Protection Extensions)"
1722 depends on CPU_SUP_INTEL
1724 MPX provides hardware features that can be used in
1725 conjunction with compiler-instrumented code to check
1726 memory references. It is designed to detect buffer
1727 overflow or underflow bugs.
1729 This option enables running applications which are
1730 instrumented or otherwise use MPX. It does not use MPX
1731 itself inside the kernel or to protect the kernel
1732 against bad memory references.
1734 Enabling this option will make the kernel larger:
1735 ~8k of kernel text and 36 bytes of data on a 64-bit
1736 defconfig. It adds a long to the 'mm_struct' which
1737 will increase the kernel memory overhead of each
1738 process and adds some branches to paths used during
1739 exec() and munmap().
1741 For details, see Documentation/x86/intel_mpx.txt
1745 config X86_INTEL_MEMORY_PROTECTION_KEYS
1746 prompt "Intel Memory Protection Keys"
1748 # Note: only available in 64-bit mode
1749 depends on CPU_SUP_INTEL && X86_64
1751 Memory Protection Keys provides a mechanism for enforcing
1752 page-based protections, but without requiring modification of the
1753 page tables when an application changes protection domains.
1755 For details, see Documentation/x86/protection-keys.txt
1760 prompt "TSX enable mode"
1761 depends on CPU_SUP_INTEL
1762 default X86_INTEL_TSX_MODE_OFF
1764 Intel's TSX (Transactional Synchronization Extensions) feature
1765 allows to optimize locking protocols through lock elision which
1766 can lead to a noticeable performance boost.
1768 On the other hand it has been shown that TSX can be exploited
1769 to form side channel attacks (e.g. TAA) and chances are there
1770 will be more of those attacks discovered in the future.
1772 Therefore TSX is not enabled by default (aka tsx=off). An admin
1773 might override this decision by tsx=on the command line parameter.
1774 Even with TSX enabled, the kernel will attempt to enable the best
1775 possible TAA mitigation setting depending on the microcode available
1776 for the particular machine.
1778 This option allows to set the default tsx mode between tsx=on, =off
1779 and =auto. See Documentation/kernel-parameters.txt for more
1782 Say off if not sure, auto if TSX is in use but it should be used on safe
1783 platforms or on if TSX is in use and the security aspect of tsx is not
1786 config X86_INTEL_TSX_MODE_OFF
1789 TSX is disabled if possible - equals to tsx=off command line parameter.
1791 config X86_INTEL_TSX_MODE_ON
1794 TSX is always enabled on TSX capable HW - equals the tsx=on command
1797 config X86_INTEL_TSX_MODE_AUTO
1800 TSX is enabled on TSX capable HW that is believed to be safe against
1801 side channel attacks- equals the tsx=auto command line parameter.
1805 bool "EFI runtime service support"
1808 select EFI_RUNTIME_WRAPPERS
1810 This enables the kernel to use EFI runtime services that are
1811 available (such as the EFI variable services).
1813 This option is only useful on systems that have EFI firmware.
1814 In addition, you should use the latest ELILO loader available
1815 at <http://elilo.sourceforge.net> in order to take advantage
1816 of EFI runtime services. However, even with this option, the
1817 resultant kernel should continue to boot on existing non-EFI
1821 bool "EFI stub support"
1822 depends on EFI && !X86_USE_3DNOW
1825 This kernel feature allows a bzImage to be loaded directly
1826 by EFI firmware without the use of a bootloader.
1828 See Documentation/efi-stub.txt for more information.
1831 bool "EFI mixed-mode support"
1832 depends on EFI_STUB && X86_64
1834 Enabling this feature allows a 64-bit kernel to be booted
1835 on a 32-bit firmware, provided that your CPU supports 64-bit
1838 Note that it is not possible to boot a mixed-mode enabled
1839 kernel via the EFI boot stub - a bootloader that supports
1840 the EFI handover protocol must be used.
1846 prompt "Enable seccomp to safely compute untrusted bytecode"
1848 This kernel feature is useful for number crunching applications
1849 that may need to compute untrusted bytecode during their
1850 execution. By using pipes or other transports made available to
1851 the process as file descriptors supporting the read/write
1852 syscalls, it's possible to isolate those applications in
1853 their own address space using seccomp. Once seccomp is
1854 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1855 and the task is only allowed to execute a few safe syscalls
1856 defined by each seccomp mode.
1858 If unsure, say Y. Only embedded should say N here.
1860 source kernel/Kconfig.hz
1863 bool "kexec system call"
1866 kexec is a system call that implements the ability to shutdown your
1867 current kernel, and to start another kernel. It is like a reboot
1868 but it is independent of the system firmware. And like a reboot
1869 you can start any kernel with it, not just Linux.
1871 The name comes from the similarity to the exec system call.
1873 It is an ongoing process to be certain the hardware in a machine
1874 is properly shutdown, so do not be surprised if this code does not
1875 initially work for you. As of this writing the exact hardware
1876 interface is strongly in flux, so no good recommendation can be
1880 bool "kexec file based system call"
1885 depends on CRYPTO_SHA256=y
1887 This is new version of kexec system call. This system call is
1888 file based and takes file descriptors as system call argument
1889 for kernel and initramfs as opposed to list of segments as
1890 accepted by previous system call.
1892 config KEXEC_VERIFY_SIG
1893 bool "Verify kernel signature during kexec_file_load() syscall"
1894 depends on KEXEC_FILE
1896 This option makes kernel signature verification mandatory for
1897 the kexec_file_load() syscall.
1899 In addition to that option, you need to enable signature
1900 verification for the corresponding kernel image type being
1901 loaded in order for this to work.
1903 config KEXEC_BZIMAGE_VERIFY_SIG
1904 bool "Enable bzImage signature verification support"
1905 depends on KEXEC_VERIFY_SIG
1906 depends on SIGNED_PE_FILE_VERIFICATION
1907 select SYSTEM_TRUSTED_KEYRING
1909 Enable bzImage signature verification support.
1912 bool "kernel crash dumps"
1913 depends on X86_64 || (X86_32 && HIGHMEM)
1915 Generate crash dump after being started by kexec.
1916 This should be normally only set in special crash dump kernels
1917 which are loaded in the main kernel with kexec-tools into
1918 a specially reserved region and then later executed after
1919 a crash by kdump/kexec. The crash dump kernel must be compiled
1920 to a memory address not used by the main kernel or BIOS using
1921 PHYSICAL_START, or it must be built as a relocatable image
1922 (CONFIG_RELOCATABLE=y).
1923 For more details see Documentation/kdump/kdump.txt
1927 depends on KEXEC && HIBERNATION
1929 Jump between original kernel and kexeced kernel and invoke
1930 code in physical address mode via KEXEC
1932 config PHYSICAL_START
1933 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1936 This gives the physical address where the kernel is loaded.
1938 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1939 bzImage will decompress itself to above physical address and
1940 run from there. Otherwise, bzImage will run from the address where
1941 it has been loaded by the boot loader and will ignore above physical
1944 In normal kdump cases one does not have to set/change this option
1945 as now bzImage can be compiled as a completely relocatable image
1946 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1947 address. This option is mainly useful for the folks who don't want
1948 to use a bzImage for capturing the crash dump and want to use a
1949 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1950 to be specifically compiled to run from a specific memory area
1951 (normally a reserved region) and this option comes handy.
1953 So if you are using bzImage for capturing the crash dump,
1954 leave the value here unchanged to 0x1000000 and set
1955 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1956 for capturing the crash dump change this value to start of
1957 the reserved region. In other words, it can be set based on
1958 the "X" value as specified in the "crashkernel=YM@XM"
1959 command line boot parameter passed to the panic-ed
1960 kernel. Please take a look at Documentation/kdump/kdump.txt
1961 for more details about crash dumps.
1963 Usage of bzImage for capturing the crash dump is recommended as
1964 one does not have to build two kernels. Same kernel can be used
1965 as production kernel and capture kernel. Above option should have
1966 gone away after relocatable bzImage support is introduced. But it
1967 is present because there are users out there who continue to use
1968 vmlinux for dump capture. This option should go away down the
1971 Don't change this unless you know what you are doing.
1974 bool "Build a relocatable kernel"
1977 This builds a kernel image that retains relocation information
1978 so it can be loaded someplace besides the default 1MB.
1979 The relocations tend to make the kernel binary about 10% larger,
1980 but are discarded at runtime.
1982 One use is for the kexec on panic case where the recovery kernel
1983 must live at a different physical address than the primary
1986 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1987 it has been loaded at and the compile time physical address
1988 (CONFIG_PHYSICAL_START) is used as the minimum location.
1990 config RANDOMIZE_BASE
1991 bool "Randomize the address of the kernel image (KASLR)"
1992 depends on RELOCATABLE
1995 In support of Kernel Address Space Layout Randomization (KASLR),
1996 this randomizes the physical address at which the kernel image
1997 is decompressed and the virtual address where the kernel
1998 image is mapped, as a security feature that deters exploit
1999 attempts relying on knowledge of the location of kernel
2002 On 64-bit, the kernel physical and virtual addresses are
2003 randomized separately. The physical address will be anywhere
2004 between 16MB and the top of physical memory (up to 64TB). The
2005 virtual address will be randomized from 16MB up to 1GB (9 bits
2006 of entropy). Note that this also reduces the memory space
2007 available to kernel modules from 1.5GB to 1GB.
2009 On 32-bit, the kernel physical and virtual addresses are
2010 randomized together. They will be randomized from 16MB up to
2011 512MB (8 bits of entropy).
2013 Entropy is generated using the RDRAND instruction if it is
2014 supported. If RDTSC is supported, its value is mixed into
2015 the entropy pool as well. If neither RDRAND nor RDTSC are
2016 supported, then entropy is read from the i8254 timer. The
2017 usable entropy is limited by the kernel being built using
2018 2GB addressing, and that PHYSICAL_ALIGN must be at a
2019 minimum of 2MB. As a result, only 10 bits of entropy are
2020 theoretically possible, but the implementations are further
2021 limited due to memory layouts.
2023 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
2024 time. To enable it, boot with "kaslr" on the kernel command
2025 line (which will also disable hibernation).
2029 # Relocation on x86 needs some additional build support
2030 config X86_NEED_RELOCS
2032 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2034 config PHYSICAL_ALIGN
2035 hex "Alignment value to which kernel should be aligned"
2037 range 0x2000 0x1000000 if X86_32
2038 range 0x200000 0x1000000 if X86_64
2040 This value puts the alignment restrictions on physical address
2041 where kernel is loaded and run from. Kernel is compiled for an
2042 address which meets above alignment restriction.
2044 If bootloader loads the kernel at a non-aligned address and
2045 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2046 address aligned to above value and run from there.
2048 If bootloader loads the kernel at a non-aligned address and
2049 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2050 load address and decompress itself to the address it has been
2051 compiled for and run from there. The address for which kernel is
2052 compiled already meets above alignment restrictions. Hence the
2053 end result is that kernel runs from a physical address meeting
2054 above alignment restrictions.
2056 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2057 this value must be a multiple of 0x200000.
2059 Don't change this unless you know what you are doing.
2061 config RANDOMIZE_MEMORY
2062 bool "Randomize the kernel memory sections"
2064 depends on RANDOMIZE_BASE
2065 default RANDOMIZE_BASE
2067 Randomizes the base virtual address of kernel memory sections
2068 (physical memory mapping, vmalloc & vmemmap). This security feature
2069 makes exploits relying on predictable memory locations less reliable.
2071 The order of allocations remains unchanged. Entropy is generated in
2072 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2073 configuration have in average 30,000 different possible virtual
2074 addresses for each memory section.
2078 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2079 hex "Physical memory mapping padding" if EXPERT
2080 depends on RANDOMIZE_MEMORY
2081 default "0xa" if MEMORY_HOTPLUG
2083 range 0x1 0x40 if MEMORY_HOTPLUG
2086 Define the padding in terabytes added to the existing physical
2087 memory size during kernel memory randomization. It is useful
2088 for memory hotplug support but reduces the entropy available for
2089 address randomization.
2091 If unsure, leave at the default value.
2097 config BOOTPARAM_HOTPLUG_CPU0
2098 bool "Set default setting of cpu0_hotpluggable"
2100 depends on HOTPLUG_CPU
2102 Set whether default state of cpu0_hotpluggable is on or off.
2104 Say Y here to enable CPU0 hotplug by default. If this switch
2105 is turned on, there is no need to give cpu0_hotplug kernel
2106 parameter and the CPU0 hotplug feature is enabled by default.
2108 Please note: there are two known CPU0 dependencies if you want
2109 to enable the CPU0 hotplug feature either by this switch or by
2110 cpu0_hotplug kernel parameter.
2112 First, resume from hibernate or suspend always starts from CPU0.
2113 So hibernate and suspend are prevented if CPU0 is offline.
2115 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2116 offline if any interrupt can not migrate out of CPU0. There may
2117 be other CPU0 dependencies.
2119 Please make sure the dependencies are under your control before
2120 you enable this feature.
2122 Say N if you don't want to enable CPU0 hotplug feature by default.
2123 You still can enable the CPU0 hotplug feature at boot by kernel
2124 parameter cpu0_hotplug.
2126 config DEBUG_HOTPLUG_CPU0
2128 prompt "Debug CPU0 hotplug"
2129 depends on HOTPLUG_CPU
2131 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2132 soon as possible and boots up userspace with CPU0 offlined. User
2133 can online CPU0 back after boot time.
2135 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2136 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2137 compilation or giving cpu0_hotplug kernel parameter at boot.
2143 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2144 depends on X86_32 || IA32_EMULATION
2146 Certain buggy versions of glibc will crash if they are
2147 presented with a 32-bit vDSO that is not mapped at the address
2148 indicated in its segment table.
2150 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2151 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2152 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2153 the only released version with the bug, but OpenSUSE 9
2154 contains a buggy "glibc 2.3.2".
2156 The symptom of the bug is that everything crashes on startup, saying:
2157 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2159 Saying Y here changes the default value of the vdso32 boot
2160 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2161 This works around the glibc bug but hurts performance.
2163 If unsure, say N: if you are compiling your own kernel, you
2164 are unlikely to be using a buggy version of glibc.
2167 prompt "vsyscall table for legacy applications"
2169 default LEGACY_VSYSCALL_EMULATE
2171 Legacy user code that does not know how to find the vDSO expects
2172 to be able to issue three syscalls by calling fixed addresses in
2173 kernel space. Since this location is not randomized with ASLR,
2174 it can be used to assist security vulnerability exploitation.
2176 This setting can be changed at boot time via the kernel command
2177 line parameter vsyscall=[native|emulate|none].
2179 On a system with recent enough glibc (2.14 or newer) and no
2180 static binaries, you can say None without a performance penalty
2181 to improve security.
2183 If unsure, select "Emulate".
2185 config LEGACY_VSYSCALL_NATIVE
2188 Actual executable code is located in the fixed vsyscall
2189 address mapping, implementing time() efficiently. Since
2190 this makes the mapping executable, it can be used during
2191 security vulnerability exploitation (traditionally as
2192 ROP gadgets). This configuration is not recommended.
2194 config LEGACY_VSYSCALL_EMULATE
2197 The kernel traps and emulates calls into the fixed
2198 vsyscall address mapping. This makes the mapping
2199 non-executable, but it still contains known contents,
2200 which could be used in certain rare security vulnerability
2201 exploits. This configuration is recommended when userspace
2202 still uses the vsyscall area.
2204 config LEGACY_VSYSCALL_NONE
2207 There will be no vsyscall mapping at all. This will
2208 eliminate any risk of ASLR bypass due to the vsyscall
2209 fixed address mapping. Attempts to use the vsyscalls
2210 will be reported to dmesg, so that either old or
2211 malicious userspace programs can be identified.
2216 bool "Built-in kernel command line"
2218 Allow for specifying boot arguments to the kernel at
2219 build time. On some systems (e.g. embedded ones), it is
2220 necessary or convenient to provide some or all of the
2221 kernel boot arguments with the kernel itself (that is,
2222 to not rely on the boot loader to provide them.)
2224 To compile command line arguments into the kernel,
2225 set this option to 'Y', then fill in the
2226 boot arguments in CONFIG_CMDLINE.
2228 Systems with fully functional boot loaders (i.e. non-embedded)
2229 should leave this option set to 'N'.
2232 string "Built-in kernel command string"
2233 depends on CMDLINE_BOOL
2236 Enter arguments here that should be compiled into the kernel
2237 image and used at boot time. If the boot loader provides a
2238 command line at boot time, it is appended to this string to
2239 form the full kernel command line, when the system boots.
2241 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2242 change this behavior.
2244 In most cases, the command line (whether built-in or provided
2245 by the boot loader) should specify the device for the root
2248 config CMDLINE_OVERRIDE
2249 bool "Built-in command line overrides boot loader arguments"
2250 depends on CMDLINE_BOOL
2252 Set this option to 'Y' to have the kernel ignore the boot loader
2253 command line, and use ONLY the built-in command line.
2255 This is used to work around broken boot loaders. This should
2256 be set to 'N' under normal conditions.
2258 config MODIFY_LDT_SYSCALL
2259 bool "Enable the LDT (local descriptor table)" if EXPERT
2262 Linux can allow user programs to install a per-process x86
2263 Local Descriptor Table (LDT) using the modify_ldt(2) system
2264 call. This is required to run 16-bit or segmented code such as
2265 DOSEMU or some Wine programs. It is also used by some very old
2266 threading libraries.
2268 Enabling this feature adds a small amount of overhead to
2269 context switches and increases the low-level kernel attack
2270 surface. Disabling it removes the modify_ldt(2) system call.
2272 Saying 'N' here may make sense for embedded or server kernels.
2274 source "kernel/livepatch/Kconfig"
2278 config ARCH_ENABLE_MEMORY_HOTPLUG
2280 depends on X86_64 || (X86_32 && HIGHMEM)
2282 config ARCH_ENABLE_MEMORY_HOTREMOVE
2284 depends on MEMORY_HOTPLUG
2286 config USE_PERCPU_NUMA_NODE_ID
2290 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2292 depends on X86_64 || X86_PAE
2294 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2296 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2298 menu "Power management and ACPI options"
2300 config ARCH_HIBERNATION_HEADER
2302 depends on X86_64 && HIBERNATION
2304 source "kernel/power/Kconfig"
2306 source "drivers/acpi/Kconfig"
2308 source "drivers/sfi/Kconfig"
2315 tristate "APM (Advanced Power Management) BIOS support"
2316 depends on X86_32 && PM_SLEEP
2318 APM is a BIOS specification for saving power using several different
2319 techniques. This is mostly useful for battery powered laptops with
2320 APM compliant BIOSes. If you say Y here, the system time will be
2321 reset after a RESUME operation, the /proc/apm device will provide
2322 battery status information, and user-space programs will receive
2323 notification of APM "events" (e.g. battery status change).
2325 If you select "Y" here, you can disable actual use of the APM
2326 BIOS by passing the "apm=off" option to the kernel at boot time.
2328 Note that the APM support is almost completely disabled for
2329 machines with more than one CPU.
2331 In order to use APM, you will need supporting software. For location
2332 and more information, read <file:Documentation/power/apm-acpi.txt>
2333 and the Battery Powered Linux mini-HOWTO, available from
2334 <http://www.tldp.org/docs.html#howto>.
2336 This driver does not spin down disk drives (see the hdparm(8)
2337 manpage ("man 8 hdparm") for that), and it doesn't turn off
2338 VESA-compliant "green" monitors.
2340 This driver does not support the TI 4000M TravelMate and the ACER
2341 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2342 desktop machines also don't have compliant BIOSes, and this driver
2343 may cause those machines to panic during the boot phase.
2345 Generally, if you don't have a battery in your machine, there isn't
2346 much point in using this driver and you should say N. If you get
2347 random kernel OOPSes or reboots that don't seem to be related to
2348 anything, try disabling/enabling this option (or disabling/enabling
2351 Some other things you should try when experiencing seemingly random,
2354 1) make sure that you have enough swap space and that it is
2356 2) pass the "no-hlt" option to the kernel
2357 3) switch on floating point emulation in the kernel and pass
2358 the "no387" option to the kernel
2359 4) pass the "floppy=nodma" option to the kernel
2360 5) pass the "mem=4M" option to the kernel (thereby disabling
2361 all but the first 4 MB of RAM)
2362 6) make sure that the CPU is not over clocked.
2363 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2364 8) disable the cache from your BIOS settings
2365 9) install a fan for the video card or exchange video RAM
2366 10) install a better fan for the CPU
2367 11) exchange RAM chips
2368 12) exchange the motherboard.
2370 To compile this driver as a module, choose M here: the
2371 module will be called apm.
2375 config APM_IGNORE_USER_SUSPEND
2376 bool "Ignore USER SUSPEND"
2378 This option will ignore USER SUSPEND requests. On machines with a
2379 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2380 series notebooks, it is necessary to say Y because of a BIOS bug.
2382 config APM_DO_ENABLE
2383 bool "Enable PM at boot time"
2385 Enable APM features at boot time. From page 36 of the APM BIOS
2386 specification: "When disabled, the APM BIOS does not automatically
2387 power manage devices, enter the Standby State, enter the Suspend
2388 State, or take power saving steps in response to CPU Idle calls."
2389 This driver will make CPU Idle calls when Linux is idle (unless this
2390 feature is turned off -- see "Do CPU IDLE calls", below). This
2391 should always save battery power, but more complicated APM features
2392 will be dependent on your BIOS implementation. You may need to turn
2393 this option off if your computer hangs at boot time when using APM
2394 support, or if it beeps continuously instead of suspending. Turn
2395 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2396 T400CDT. This is off by default since most machines do fine without
2401 bool "Make CPU Idle calls when idle"
2403 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2404 On some machines, this can activate improved power savings, such as
2405 a slowed CPU clock rate, when the machine is idle. These idle calls
2406 are made after the idle loop has run for some length of time (e.g.,
2407 333 mS). On some machines, this will cause a hang at boot time or
2408 whenever the CPU becomes idle. (On machines with more than one CPU,
2409 this option does nothing.)
2411 config APM_DISPLAY_BLANK
2412 bool "Enable console blanking using APM"
2414 Enable console blanking using the APM. Some laptops can use this to
2415 turn off the LCD backlight when the screen blanker of the Linux
2416 virtual console blanks the screen. Note that this is only used by
2417 the virtual console screen blanker, and won't turn off the backlight
2418 when using the X Window system. This also doesn't have anything to
2419 do with your VESA-compliant power-saving monitor. Further, this
2420 option doesn't work for all laptops -- it might not turn off your
2421 backlight at all, or it might print a lot of errors to the console,
2422 especially if you are using gpm.
2424 config APM_ALLOW_INTS
2425 bool "Allow interrupts during APM BIOS calls"
2427 Normally we disable external interrupts while we are making calls to
2428 the APM BIOS as a measure to lessen the effects of a badly behaving
2429 BIOS implementation. The BIOS should reenable interrupts if it
2430 needs to. Unfortunately, some BIOSes do not -- especially those in
2431 many of the newer IBM Thinkpads. If you experience hangs when you
2432 suspend, try setting this to Y. Otherwise, say N.
2436 source "drivers/cpufreq/Kconfig"
2438 source "drivers/cpuidle/Kconfig"
2440 source "drivers/idle/Kconfig"
2445 menu "Bus options (PCI etc.)"
2451 Find out whether you have a PCI motherboard. PCI is the name of a
2452 bus system, i.e. the way the CPU talks to the other stuff inside
2453 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2454 VESA. If you have PCI, say Y, otherwise N.
2457 prompt "PCI access mode"
2458 depends on X86_32 && PCI
2461 On PCI systems, the BIOS can be used to detect the PCI devices and
2462 determine their configuration. However, some old PCI motherboards
2463 have BIOS bugs and may crash if this is done. Also, some embedded
2464 PCI-based systems don't have any BIOS at all. Linux can also try to
2465 detect the PCI hardware directly without using the BIOS.
2467 With this option, you can specify how Linux should detect the
2468 PCI devices. If you choose "BIOS", the BIOS will be used,
2469 if you choose "Direct", the BIOS won't be used, and if you
2470 choose "MMConfig", then PCI Express MMCONFIG will be used.
2471 If you choose "Any", the kernel will try MMCONFIG, then the
2472 direct access method and falls back to the BIOS if that doesn't
2473 work. If unsure, go with the default, which is "Any".
2478 config PCI_GOMMCONFIG
2495 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2497 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2500 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2504 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2508 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2512 depends on PCI && XEN
2520 bool "Support mmconfig PCI config space access"
2521 depends on X86_64 && PCI && ACPI
2523 config PCI_CNB20LE_QUIRK
2524 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2527 Read the PCI windows out of the CNB20LE host bridge. This allows
2528 PCI hotplug to work on systems with the CNB20LE chipset which do
2531 There's no public spec for this chipset, and this functionality
2532 is known to be incomplete.
2534 You should say N unless you know you need this.
2536 source "drivers/pci/Kconfig"
2539 bool "ISA-style bus support on modern systems" if EXPERT
2542 Enables ISA-style drivers on modern systems. This is necessary to
2543 support PC/104 devices on X86_64 platforms.
2547 # x86_64 have no ISA slots, but can have ISA-style DMA.
2549 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2552 Enables ISA-style DMA support for devices requiring such controllers.
2560 Find out whether you have ISA slots on your motherboard. ISA is the
2561 name of a bus system, i.e. the way the CPU talks to the other stuff
2562 inside your box. Other bus systems are PCI, EISA, MicroChannel
2563 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2564 newer boards don't support it. If you have ISA, say Y, otherwise N.
2570 The Extended Industry Standard Architecture (EISA) bus was
2571 developed as an open alternative to the IBM MicroChannel bus.
2573 The EISA bus provided some of the features of the IBM MicroChannel
2574 bus while maintaining backward compatibility with cards made for
2575 the older ISA bus. The EISA bus saw limited use between 1988 and
2576 1995 when it was made obsolete by the PCI bus.
2578 Say Y here if you are building a kernel for an EISA-based machine.
2582 source "drivers/eisa/Kconfig"
2585 tristate "NatSemi SCx200 support"
2587 This provides basic support for National Semiconductor's
2588 (now AMD's) Geode processors. The driver probes for the
2589 PCI-IDs of several on-chip devices, so its a good dependency
2590 for other scx200_* drivers.
2592 If compiled as a module, the driver is named scx200.
2594 config SCx200HR_TIMER
2595 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2599 This driver provides a clocksource built upon the on-chip
2600 27MHz high-resolution timer. Its also a workaround for
2601 NSC Geode SC-1100's buggy TSC, which loses time when the
2602 processor goes idle (as is done by the scheduler). The
2603 other workaround is idle=poll boot option.
2606 bool "One Laptop Per Child support"
2613 Add support for detecting the unique features of the OLPC
2617 bool "OLPC XO-1 Power Management"
2618 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2620 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2623 bool "OLPC XO-1 Real Time Clock"
2624 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2626 Add support for the XO-1 real time clock, which can be used as a
2627 programmable wakeup source.
2630 bool "OLPC XO-1 SCI extras"
2631 depends on OLPC && OLPC_XO1_PM
2637 Add support for SCI-based features of the OLPC XO-1 laptop:
2638 - EC-driven system wakeups
2642 - AC adapter status updates
2643 - Battery status updates
2645 config OLPC_XO15_SCI
2646 bool "OLPC XO-1.5 SCI extras"
2647 depends on OLPC && ACPI
2650 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2651 - EC-driven system wakeups
2652 - AC adapter status updates
2653 - Battery status updates
2656 bool "PCEngines ALIX System Support (LED setup)"
2659 This option enables system support for the PCEngines ALIX.
2660 At present this just sets up LEDs for GPIO control on
2661 ALIX2/3/6 boards. However, other system specific setup should
2664 Note: You must still enable the drivers for GPIO and LED support
2665 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2667 Note: You have to set alix.force=1 for boards with Award BIOS.
2670 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2673 This option enables system support for the Soekris Engineering net5501.
2676 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2680 This option enables system support for the Traverse Technologies GEOS.
2683 bool "Technologic Systems TS-5500 platform support"
2685 select CHECK_SIGNATURE
2689 This option enables system support for the Technologic Systems TS-5500.
2695 depends on CPU_SUP_AMD && PCI
2697 source "drivers/pcmcia/Kconfig"
2700 tristate "RapidIO support"
2704 If enabled this option will include drivers and the core
2705 infrastructure code to support RapidIO interconnect devices.
2707 source "drivers/rapidio/Kconfig"
2710 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2712 Firmwares often provide initial graphics framebuffers so the BIOS,
2713 bootloader or kernel can show basic video-output during boot for
2714 user-guidance and debugging. Historically, x86 used the VESA BIOS
2715 Extensions and EFI-framebuffers for this, which are mostly limited
2717 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2718 framebuffers so the new generic system-framebuffer drivers can be
2719 used on x86. If the framebuffer is not compatible with the generic
2720 modes, it is adverticed as fallback platform framebuffer so legacy
2721 drivers like efifb, vesafb and uvesafb can pick it up.
2722 If this option is not selected, all system framebuffers are always
2723 marked as fallback platform framebuffers as usual.
2725 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2726 not be able to pick up generic system framebuffers if this option
2727 is selected. You are highly encouraged to enable simplefb as
2728 replacement if you select this option. simplefb can correctly deal
2729 with generic system framebuffers. But you should still keep vesafb
2730 and others enabled as fallback if a system framebuffer is
2731 incompatible with simplefb.
2738 menu "Executable file formats / Emulations"
2740 source "fs/Kconfig.binfmt"
2742 config IA32_EMULATION
2743 bool "IA32 Emulation"
2746 select COMPAT_BINFMT_ELF
2747 select ARCH_WANT_OLD_COMPAT_IPC
2749 Include code to run legacy 32-bit programs under a
2750 64-bit kernel. You should likely turn this on, unless you're
2751 100% sure that you don't have any 32-bit programs left.
2754 tristate "IA32 a.out support"
2755 depends on IA32_EMULATION
2757 Support old a.out binaries in the 32bit emulation.
2760 bool "x32 ABI for 64-bit mode"
2763 Include code to run binaries for the x32 native 32-bit ABI
2764 for 64-bit processors. An x32 process gets access to the
2765 full 64-bit register file and wide data path while leaving
2766 pointers at 32 bits for smaller memory footprint.
2768 You will need a recent binutils (2.22 or later) with
2769 elf32_x86_64 support enabled to compile a kernel with this
2774 depends on IA32_EMULATION || X86_X32
2777 config COMPAT_FOR_U64_ALIGNMENT
2780 config SYSVIPC_COMPAT
2788 config HAVE_ATOMIC_IOMAP
2792 config X86_DEV_DMA_OPS
2794 depends on X86_64 || STA2X11
2796 config X86_DMA_REMAP
2804 source "net/Kconfig"
2806 source "drivers/Kconfig"
2808 source "drivers/firmware/Kconfig"
2812 source "arch/x86/Kconfig.debug"
2814 source "security/Kconfig"
2816 source "crypto/Kconfig"
2818 source "arch/x86/kvm/Kconfig"
2820 source "lib/Kconfig"
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