3 bool "64-bit kernel" if ARCH = "x86"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
12 # Options that are inherently 32-bit kernel only:
13 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLONE_BACKWARDS
17 select HAVE_GENERIC_DMA_COHERENT
18 select MODULES_USE_ELF_REL
24 # Options that are inherently 64-bit kernel only:
25 select ARCH_HAS_GIGANTIC_PAGE
26 select ARCH_SUPPORTS_INT128
27 select ARCH_USE_CMPXCHG_LOCKREF
28 select HAVE_ARCH_SOFT_DIRTY
29 select MODULES_USE_ELF_RELA
30 select X86_DEV_DMA_OPS
35 # ( Note that options that are marked 'if X86_64' could in principle be
36 # ported to 32-bit as well. )
41 # Note: keep this list sorted alphabetically
43 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
44 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
46 select ARCH_CLOCKSOURCE_DATA
47 select ARCH_DISCARD_MEMBLOCK
48 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
49 select ARCH_HAS_DEBUG_VIRTUAL
50 select ARCH_HAS_DEVMEM_IS_ALLOWED
51 select ARCH_HAS_ELF_RANDOMIZE
52 select ARCH_HAS_FAST_MULTIPLIER
53 select ARCH_HAS_GCOV_PROFILE_ALL
54 select ARCH_HAS_KCOV if X86_64
55 select ARCH_HAS_MMIO_FLUSH
56 select ARCH_HAS_PMEM_API if X86_64
57 select ARCH_HAS_SET_MEMORY
58 select ARCH_HAS_SG_CHAIN
59 select ARCH_HAS_STRICT_KERNEL_RWX
60 select ARCH_HAS_STRICT_MODULE_RWX
61 select ARCH_HAS_UBSAN_SANITIZE_ALL
62 select ARCH_HAVE_NMI_SAFE_CMPXCHG
63 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
64 select ARCH_MIGHT_HAVE_PC_PARPORT
65 select ARCH_MIGHT_HAVE_PC_SERIO
66 select ARCH_SUPPORTS_ATOMIC_RMW
67 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
68 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
69 select ARCH_USE_BUILTIN_BSWAP
70 select ARCH_USE_QUEUED_RWLOCKS
71 select ARCH_USE_QUEUED_SPINLOCKS
72 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
73 select ARCH_WANT_FRAME_POINTERS
74 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
75 select BUILDTIME_EXTABLE_SORT
77 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
78 select CLOCKSOURCE_WATCHDOG
79 select DCACHE_WORD_ACCESS
80 select EDAC_ATOMIC_SCRUB
82 select GENERIC_CLOCKEVENTS
83 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
84 select GENERIC_CLOCKEVENTS_MIN_ADJUST
85 select GENERIC_CMOS_UPDATE
86 select GENERIC_CPU_AUTOPROBE
87 select GENERIC_EARLY_IOREMAP
88 select GENERIC_FIND_FIRST_BIT
90 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
91 select GENERIC_IRQ_MIGRATION if SMP
92 select GENERIC_IRQ_PROBE
93 select GENERIC_IRQ_SHOW
94 select GENERIC_PENDING_IRQ if SMP
95 select GENERIC_SMP_IDLE_THREAD
96 select GENERIC_STRNCPY_FROM_USER
97 select GENERIC_STRNLEN_USER
98 select GENERIC_TIME_VSYSCALL
99 select HAVE_ACPI_APEI if ACPI
100 select HAVE_ACPI_APEI_NMI if ACPI
101 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
102 select HAVE_ARCH_AUDITSYSCALL
103 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
104 select HAVE_ARCH_JUMP_LABEL
105 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
106 select HAVE_ARCH_KGDB
107 select HAVE_ARCH_KMEMCHECK
108 select HAVE_ARCH_MMAP_RND_BITS if MMU
109 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
110 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
111 select HAVE_ARCH_SECCOMP_FILTER
112 select HAVE_ARCH_TRACEHOOK
113 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
114 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
115 select HAVE_ARCH_VMAP_STACK if X86_64
116 select HAVE_ARCH_WITHIN_STACK_FRAMES
117 select HAVE_CC_STACKPROTECTOR
118 select HAVE_CMPXCHG_DOUBLE
119 select HAVE_CMPXCHG_LOCAL
120 select HAVE_CONTEXT_TRACKING if X86_64
121 select HAVE_COPY_THREAD_TLS
122 select HAVE_C_RECORDMCOUNT
123 select HAVE_DEBUG_KMEMLEAK
124 select HAVE_DEBUG_STACKOVERFLOW
125 select HAVE_DMA_API_DEBUG
126 select HAVE_DMA_CONTIGUOUS
127 select HAVE_DYNAMIC_FTRACE
128 select HAVE_DYNAMIC_FTRACE_WITH_REGS
129 select HAVE_EBPF_JIT if X86_64
130 select HAVE_EFFICIENT_UNALIGNED_ACCESS
131 select HAVE_EXIT_THREAD
132 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
133 select HAVE_FTRACE_MCOUNT_RECORD
134 select HAVE_FUNCTION_GRAPH_TRACER
135 select HAVE_FUNCTION_TRACER
136 select HAVE_GCC_PLUGINS
137 select HAVE_HW_BREAKPOINT
139 select HAVE_IOREMAP_PROT
140 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
141 select HAVE_IRQ_TIME_ACCOUNTING
142 select HAVE_KERNEL_BZIP2
143 select HAVE_KERNEL_GZIP
144 select HAVE_KERNEL_LZ4
145 select HAVE_KERNEL_LZMA
146 select HAVE_KERNEL_LZO
147 select HAVE_KERNEL_XZ
149 select HAVE_KPROBES_ON_FTRACE
150 select HAVE_KRETPROBES
152 select HAVE_LIVEPATCH if X86_64
154 select HAVE_MEMBLOCK_NODE_MAP
155 select HAVE_MIXED_BREAKPOINTS_REGS
158 select HAVE_OPTPROBES
159 select HAVE_PCSPKR_PLATFORM
160 select HAVE_PERF_EVENTS
161 select HAVE_PERF_EVENTS_NMI
162 select HAVE_PERF_REGS
163 select HAVE_PERF_USER_STACK_DUMP
164 select HAVE_REGS_AND_STACK_ACCESS_API
165 select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER && STACK_VALIDATION
166 select HAVE_STACK_VALIDATION if X86_64
167 select HAVE_SYSCALL_TRACEPOINTS
168 select HAVE_UNSTABLE_SCHED_CLOCK
169 select HAVE_USER_RETURN_NOTIFIER
170 select IRQ_FORCED_THREADING
171 select PCI_LOCKLESS_CONFIG
174 select RTC_MC146818_LIB
177 select SYSCTL_EXCEPTION_TRACE
178 select THREAD_INFO_IN_TASK
179 select USER_STACKTRACE_SUPPORT
181 select X86_FEATURE_NAMES if PROC_FS
183 config INSTRUCTION_DECODER
185 depends on KPROBES || PERF_EVENTS || UPROBES
189 default "elf32-i386" if X86_32
190 default "elf64-x86-64" if X86_64
192 config ARCH_DEFCONFIG
194 default "arch/x86/configs/i386_defconfig" if X86_32
195 default "arch/x86/configs/x86_64_defconfig" if X86_64
197 config LOCKDEP_SUPPORT
200 config STACKTRACE_SUPPORT
206 config ARCH_MMAP_RND_BITS_MIN
210 config ARCH_MMAP_RND_BITS_MAX
214 config ARCH_MMAP_RND_COMPAT_BITS_MIN
217 config ARCH_MMAP_RND_COMPAT_BITS_MAX
223 config NEED_DMA_MAP_STATE
225 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
227 config NEED_SG_DMA_LENGTH
230 config GENERIC_ISA_DMA
232 depends on ISA_DMA_API
237 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
239 config GENERIC_BUG_RELATIVE_POINTERS
242 config GENERIC_HWEIGHT
245 config ARCH_MAY_HAVE_PC_FDC
247 depends on ISA_DMA_API
249 config RWSEM_XCHGADD_ALGORITHM
252 config GENERIC_CALIBRATE_DELAY
255 config ARCH_HAS_CPU_RELAX
258 config ARCH_HAS_CACHE_LINE_SIZE
261 config HAVE_SETUP_PER_CPU_AREA
264 config NEED_PER_CPU_EMBED_FIRST_CHUNK
267 config NEED_PER_CPU_PAGE_FIRST_CHUNK
270 config ARCH_HIBERNATION_POSSIBLE
273 config ARCH_SUSPEND_POSSIBLE
276 config ARCH_WANT_HUGE_PMD_SHARE
279 config ARCH_WANT_GENERAL_HUGETLB
288 config ARCH_SUPPORTS_OPTIMIZED_INLINING
291 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
294 config KASAN_SHADOW_OFFSET
297 default 0xdff8000000000000 if X86_5LEVEL
298 default 0xdffffc0000000000
300 config HAVE_INTEL_TXT
302 depends on INTEL_IOMMU && ACPI
306 depends on X86_32 && SMP
310 depends on X86_64 && SMP
312 config X86_32_LAZY_GS
314 depends on X86_32 && !CC_STACKPROTECTOR
316 config ARCH_SUPPORTS_UPROBES
319 config FIX_EARLYCON_MEM
322 config PGTABLE_LEVELS
328 source "init/Kconfig"
329 source "kernel/Kconfig.freezer"
331 menu "Processor type and features"
334 bool "DMA memory allocation support" if EXPERT
337 DMA memory allocation support allows devices with less than 32-bit
338 addressing to allocate within the first 16MB of address space.
339 Disable if no such devices will be used.
344 bool "Symmetric multi-processing support"
346 This enables support for systems with more than one CPU. If you have
347 a system with only one CPU, say N. If you have a system with more
350 If you say N here, the kernel will run on uni- and multiprocessor
351 machines, but will use only one CPU of a multiprocessor machine. If
352 you say Y here, the kernel will run on many, but not all,
353 uniprocessor machines. On a uniprocessor machine, the kernel
354 will run faster if you say N here.
356 Note that if you say Y here and choose architecture "586" or
357 "Pentium" under "Processor family", the kernel will not work on 486
358 architectures. Similarly, multiprocessor kernels for the "PPro"
359 architecture may not work on all Pentium based boards.
361 People using multiprocessor machines who say Y here should also say
362 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
363 Management" code will be disabled if you say Y here.
365 See also <file:Documentation/x86/i386/IO-APIC.txt>,
366 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
367 <http://www.tldp.org/docs.html#howto>.
369 If you don't know what to do here, say N.
371 config X86_FEATURE_NAMES
372 bool "Processor feature human-readable names" if EMBEDDED
375 This option compiles in a table of x86 feature bits and corresponding
376 names. This is required to support /proc/cpuinfo and a few kernel
377 messages. You can disable this to save space, at the expense of
378 making those few kernel messages show numeric feature bits instead.
382 config X86_FAST_FEATURE_TESTS
383 bool "Fast CPU feature tests" if EMBEDDED
386 Some fast-paths in the kernel depend on the capabilities of the CPU.
387 Say Y here for the kernel to patch in the appropriate code at runtime
388 based on the capabilities of the CPU. The infrastructure for patching
389 code at runtime takes up some additional space; space-constrained
390 embedded systems may wish to say N here to produce smaller, slightly
394 bool "Support x2apic"
395 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
397 This enables x2apic support on CPUs that have this feature.
399 This allows 32-bit apic IDs (so it can support very large systems),
400 and accesses the local apic via MSRs not via mmio.
402 If you don't know what to do here, say N.
405 bool "Enable MPS table" if ACPI || SFI
407 depends on X86_LOCAL_APIC
409 For old smp systems that do not have proper acpi support. Newer systems
410 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
413 bool "Support for big SMP systems with more than 8 CPUs"
414 depends on X86_32 && SMP
416 This option is needed for the systems that have more than 8 CPUs
420 depends on X86_GOLDFISH
423 bool "Intel Resource Director Technology Allocation support"
425 depends on X86 && CPU_SUP_INTEL
428 Select to enable resource allocation which is a sub-feature of
429 Intel Resource Director Technology(RDT). More information about
430 RDT can be found in the Intel x86 Architecture Software
436 config X86_EXTENDED_PLATFORM
437 bool "Support for extended (non-PC) x86 platforms"
440 If you disable this option then the kernel will only support
441 standard PC platforms. (which covers the vast majority of
444 If you enable this option then you'll be able to select support
445 for the following (non-PC) 32 bit x86 platforms:
446 Goldfish (Android emulator)
449 SGI 320/540 (Visual Workstation)
450 STA2X11-based (e.g. Northville)
451 Moorestown MID devices
453 If you have one of these systems, or if you want to build a
454 generic distribution kernel, say Y here - otherwise say N.
458 config X86_EXTENDED_PLATFORM
459 bool "Support for extended (non-PC) x86 platforms"
462 If you disable this option then the kernel will only support
463 standard PC platforms. (which covers the vast majority of
466 If you enable this option then you'll be able to select support
467 for the following (non-PC) 64 bit x86 platforms:
472 If you have one of these systems, or if you want to build a
473 generic distribution kernel, say Y here - otherwise say N.
475 # This is an alphabetically sorted list of 64 bit extended platforms
476 # Please maintain the alphabetic order if and when there are additions
478 bool "Numascale NumaChip"
480 depends on X86_EXTENDED_PLATFORM
483 depends on X86_X2APIC
484 depends on PCI_MMCONFIG
486 Adds support for Numascale NumaChip large-SMP systems. Needed to
487 enable more than ~168 cores.
488 If you don't have one of these, you should say N here.
492 select HYPERVISOR_GUEST
494 depends on X86_64 && PCI
495 depends on X86_EXTENDED_PLATFORM
498 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
499 supposed to run on these EM64T-based machines. Only choose this option
500 if you have one of these machines.
503 bool "SGI Ultraviolet"
505 depends on X86_EXTENDED_PLATFORM
508 depends on X86_X2APIC
511 This option is needed in order to support SGI Ultraviolet systems.
512 If you don't have one of these, you should say N here.
514 # Following is an alphabetically sorted list of 32 bit extended platforms
515 # Please maintain the alphabetic order if and when there are additions
518 bool "Goldfish (Virtual Platform)"
519 depends on X86_EXTENDED_PLATFORM
521 Enable support for the Goldfish virtual platform used primarily
522 for Android development. Unless you are building for the Android
523 Goldfish emulator say N here.
526 bool "CE4100 TV platform"
528 depends on PCI_GODIRECT
529 depends on X86_IO_APIC
531 depends on X86_EXTENDED_PLATFORM
532 select X86_REBOOTFIXUPS
534 select OF_EARLY_FLATTREE
536 Select for the Intel CE media processor (CE4100) SOC.
537 This option compiles in support for the CE4100 SOC for settop
538 boxes and media devices.
541 bool "Intel MID platform support"
542 depends on X86_EXTENDED_PLATFORM
543 depends on X86_PLATFORM_DEVICES
545 depends on X86_64 || (PCI_GOANY && X86_32)
546 depends on X86_IO_APIC
552 select MFD_INTEL_MSIC
554 Select to build a kernel capable of supporting Intel MID (Mobile
555 Internet Device) platform systems which do not have the PCI legacy
556 interfaces. If you are building for a PC class system say N here.
558 Intel MID platforms are based on an Intel processor and chipset which
559 consume less power than most of the x86 derivatives.
561 config X86_INTEL_QUARK
562 bool "Intel Quark platform support"
564 depends on X86_EXTENDED_PLATFORM
565 depends on X86_PLATFORM_DEVICES
569 depends on X86_IO_APIC
574 Select to include support for Quark X1000 SoC.
575 Say Y here if you have a Quark based system such as the Arduino
576 compatible Intel Galileo.
578 config X86_INTEL_LPSS
579 bool "Intel Low Power Subsystem Support"
580 depends on X86 && ACPI
585 Select to build support for Intel Low Power Subsystem such as
586 found on Intel Lynxpoint PCH. Selecting this option enables
587 things like clock tree (common clock framework) and pincontrol
588 which are needed by the LPSS peripheral drivers.
590 config X86_AMD_PLATFORM_DEVICE
591 bool "AMD ACPI2Platform devices support"
596 Select to interpret AMD specific ACPI device to platform device
597 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
598 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
599 implemented under PINCTRL subsystem.
602 tristate "Intel SoC IOSF Sideband support for SoC platforms"
605 This option enables sideband register access support for Intel SoC
606 platforms. On these platforms the IOSF sideband is used in lieu of
607 MSR's for some register accesses, mostly but not limited to thermal
608 and power. Drivers may query the availability of this device to
609 determine if they need the sideband in order to work on these
610 platforms. The sideband is available on the following SoC products.
611 This list is not meant to be exclusive.
616 You should say Y if you are running a kernel on one of these SoC's.
618 config IOSF_MBI_DEBUG
619 bool "Enable IOSF sideband access through debugfs"
620 depends on IOSF_MBI && DEBUG_FS
622 Select this option to expose the IOSF sideband access registers (MCR,
623 MDR, MCRX) through debugfs to write and read register information from
624 different units on the SoC. This is most useful for obtaining device
625 state information for debug and analysis. As this is a general access
626 mechanism, users of this option would have specific knowledge of the
627 device they want to access.
629 If you don't require the option or are in doubt, say N.
632 bool "RDC R-321x SoC"
634 depends on X86_EXTENDED_PLATFORM
636 select X86_REBOOTFIXUPS
638 This option is needed for RDC R-321x system-on-chip, also known
640 If you don't have one of these chips, you should say N here.
642 config X86_32_NON_STANDARD
643 bool "Support non-standard 32-bit SMP architectures"
644 depends on X86_32 && SMP
645 depends on X86_EXTENDED_PLATFORM
647 This option compiles in the bigsmp and STA2X11 default
648 subarchitectures. It is intended for a generic binary
649 kernel. If you select them all, kernel will probe it one by
650 one and will fallback to default.
652 # Alphabetically sorted list of Non standard 32 bit platforms
654 config X86_SUPPORTS_MEMORY_FAILURE
656 # MCE code calls memory_failure():
658 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
659 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
660 depends on X86_64 || !SPARSEMEM
661 select ARCH_SUPPORTS_MEMORY_FAILURE
664 bool "STA2X11 Companion Chip Support"
665 depends on X86_32_NON_STANDARD && PCI
666 select X86_DEV_DMA_OPS
673 This adds support for boards based on the STA2X11 IO-Hub,
674 a.k.a. "ConneXt". The chip is used in place of the standard
675 PC chipset, so all "standard" peripherals are missing. If this
676 option is selected the kernel will still be able to boot on
677 standard PC machines.
680 tristate "Eurobraille/Iris poweroff module"
683 The Iris machines from EuroBraille do not have APM or ACPI support
684 to shut themselves down properly. A special I/O sequence is
685 needed to do so, which is what this module does at
688 This is only for Iris machines from EuroBraille.
692 config SCHED_OMIT_FRAME_POINTER
694 prompt "Single-depth WCHAN output"
697 Calculate simpler /proc/<PID>/wchan values. If this option
698 is disabled then wchan values will recurse back to the
699 caller function. This provides more accurate wchan values,
700 at the expense of slightly more scheduling overhead.
702 If in doubt, say "Y".
704 menuconfig HYPERVISOR_GUEST
705 bool "Linux guest support"
707 Say Y here to enable options for running Linux under various hyper-
708 visors. This option enables basic hypervisor detection and platform
711 If you say N, all options in this submenu will be skipped and
712 disabled, and Linux guest support won't be built in.
717 bool "Enable paravirtualization code"
719 This changes the kernel so it can modify itself when it is run
720 under a hypervisor, potentially improving performance significantly
721 over full virtualization. However, when run without a hypervisor
722 the kernel is theoretically slower and slightly larger.
724 config PARAVIRT_DEBUG
725 bool "paravirt-ops debugging"
726 depends on PARAVIRT && DEBUG_KERNEL
728 Enable to debug paravirt_ops internals. Specifically, BUG if
729 a paravirt_op is missing when it is called.
731 config PARAVIRT_SPINLOCKS
732 bool "Paravirtualization layer for spinlocks"
733 depends on PARAVIRT && SMP
735 Paravirtualized spinlocks allow a pvops backend to replace the
736 spinlock implementation with something virtualization-friendly
737 (for example, block the virtual CPU rather than spinning).
739 It has a minimal impact on native kernels and gives a nice performance
740 benefit on paravirtualized KVM / Xen kernels.
742 If you are unsure how to answer this question, answer Y.
744 config QUEUED_LOCK_STAT
745 bool "Paravirt queued spinlock statistics"
746 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
748 Enable the collection of statistical data on the slowpath
749 behavior of paravirtualized queued spinlocks and report
752 source "arch/x86/xen/Kconfig"
755 bool "KVM Guest support (including kvmclock)"
757 select PARAVIRT_CLOCK
760 This option enables various optimizations for running under the KVM
761 hypervisor. It includes a paravirtualized clock, so that instead
762 of relying on a PIT (or probably other) emulation by the
763 underlying device model, the host provides the guest with
764 timing infrastructure such as time of day, and system time
767 bool "Enable debug information for KVM Guests in debugfs"
768 depends on KVM_GUEST && DEBUG_FS
771 This option enables collection of various statistics for KVM guest.
772 Statistics are displayed in debugfs filesystem. Enabling this option
773 may incur significant overhead.
775 source "arch/x86/lguest/Kconfig"
777 config PARAVIRT_TIME_ACCOUNTING
778 bool "Paravirtual steal time accounting"
782 Select this option to enable fine granularity task steal time
783 accounting. Time spent executing other tasks in parallel with
784 the current vCPU is discounted from the vCPU power. To account for
785 that, there can be a small performance impact.
787 If in doubt, say N here.
789 config PARAVIRT_CLOCK
792 endif #HYPERVISOR_GUEST
797 source "arch/x86/Kconfig.cpu"
801 prompt "HPET Timer Support" if X86_32
803 Use the IA-PC HPET (High Precision Event Timer) to manage
804 time in preference to the PIT and RTC, if a HPET is
806 HPET is the next generation timer replacing legacy 8254s.
807 The HPET provides a stable time base on SMP
808 systems, unlike the TSC, but it is more expensive to access,
809 as it is off-chip. The interface used is documented
810 in the HPET spec, revision 1.
812 You can safely choose Y here. However, HPET will only be
813 activated if the platform and the BIOS support this feature.
814 Otherwise the 8254 will be used for timing services.
816 Choose N to continue using the legacy 8254 timer.
818 config HPET_EMULATE_RTC
820 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
823 def_bool y if X86_INTEL_MID
824 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
826 depends on X86_INTEL_MID && SFI
828 APB timer is the replacement for 8254, HPET on X86 MID platforms.
829 The APBT provides a stable time base on SMP
830 systems, unlike the TSC, but it is more expensive to access,
831 as it is off-chip. APB timers are always running regardless of CPU
832 C states, they are used as per CPU clockevent device when possible.
834 # Mark as expert because too many people got it wrong.
835 # The code disables itself when not needed.
838 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
839 bool "Enable DMI scanning" if EXPERT
841 Enabled scanning of DMI to identify machine quirks. Say Y
842 here unless you have verified that your setup is not
843 affected by entries in the DMI blacklist. Required by PNP
847 bool "Old AMD GART IOMMU support"
849 depends on X86_64 && PCI && AMD_NB
851 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
852 GART based hardware IOMMUs.
854 The GART supports full DMA access for devices with 32-bit access
855 limitations, on systems with more than 3 GB. This is usually needed
856 for USB, sound, many IDE/SATA chipsets and some other devices.
858 Newer systems typically have a modern AMD IOMMU, supported via
859 the CONFIG_AMD_IOMMU=y config option.
861 In normal configurations this driver is only active when needed:
862 there's more than 3 GB of memory and the system contains a
863 32-bit limited device.
868 bool "IBM Calgary IOMMU support"
870 depends on X86_64 && PCI
872 Support for hardware IOMMUs in IBM's xSeries x366 and x460
873 systems. Needed to run systems with more than 3GB of memory
874 properly with 32-bit PCI devices that do not support DAC
875 (Double Address Cycle). Calgary also supports bus level
876 isolation, where all DMAs pass through the IOMMU. This
877 prevents them from going anywhere except their intended
878 destination. This catches hard-to-find kernel bugs and
879 mis-behaving drivers and devices that do not use the DMA-API
880 properly to set up their DMA buffers. The IOMMU can be
881 turned off at boot time with the iommu=off parameter.
882 Normally the kernel will make the right choice by itself.
885 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
887 prompt "Should Calgary be enabled by default?"
888 depends on CALGARY_IOMMU
890 Should Calgary be enabled by default? if you choose 'y', Calgary
891 will be used (if it exists). If you choose 'n', Calgary will not be
892 used even if it exists. If you choose 'n' and would like to use
893 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
896 # need this always selected by IOMMU for the VIA workaround
900 Support for software bounce buffers used on x86-64 systems
901 which don't have a hardware IOMMU. Using this PCI devices
902 which can only access 32-bits of memory can be used on systems
903 with more than 3 GB of memory.
908 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
911 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
912 depends on X86_64 && SMP && DEBUG_KERNEL
913 select CPUMASK_OFFSTACK
915 Enable maximum number of CPUS and NUMA Nodes for this architecture.
919 int "Maximum number of CPUs" if SMP && !MAXSMP
920 range 2 8 if SMP && X86_32 && !X86_BIGSMP
921 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
922 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
924 default "8192" if MAXSMP
925 default "32" if SMP && X86_BIGSMP
926 default "8" if SMP && X86_32
929 This allows you to specify the maximum number of CPUs which this
930 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
931 supported value is 8192, otherwise the maximum value is 512. The
932 minimum value which makes sense is 2.
934 This is purely to save memory - each supported CPU adds
935 approximately eight kilobytes to the kernel image.
938 bool "SMT (Hyperthreading) scheduler support"
941 SMT scheduler support improves the CPU scheduler's decision making
942 when dealing with Intel Pentium 4 chips with HyperThreading at a
943 cost of slightly increased overhead in some places. If unsure say
948 prompt "Multi-core scheduler support"
951 Multi-core scheduler support improves the CPU scheduler's decision
952 making when dealing with multi-core CPU chips at a cost of slightly
953 increased overhead in some places. If unsure say N here.
956 bool "CPU core priorities scheduler support"
957 depends on SCHED_MC && CPU_SUP_INTEL
958 select X86_INTEL_PSTATE
962 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
963 core ordering determined at manufacturing time, which allows
964 certain cores to reach higher turbo frequencies (when running
965 single threaded workloads) than others.
967 Enabling this kernel feature teaches the scheduler about
968 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
969 scheduler's CPU selection logic accordingly, so that higher
970 overall system performance can be achieved.
972 This feature will have no effect on CPUs without this feature.
974 If unsure say Y here.
976 source "kernel/Kconfig.preempt"
980 depends on !SMP && X86_LOCAL_APIC
983 bool "Local APIC support on uniprocessors" if !PCI_MSI
985 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
987 A local APIC (Advanced Programmable Interrupt Controller) is an
988 integrated interrupt controller in the CPU. If you have a single-CPU
989 system which has a processor with a local APIC, you can say Y here to
990 enable and use it. If you say Y here even though your machine doesn't
991 have a local APIC, then the kernel will still run with no slowdown at
992 all. The local APIC supports CPU-generated self-interrupts (timer,
993 performance counters), and the NMI watchdog which detects hard
997 bool "IO-APIC support on uniprocessors"
998 depends on X86_UP_APIC
1000 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1001 SMP-capable replacement for PC-style interrupt controllers. Most
1002 SMP systems and many recent uniprocessor systems have one.
1004 If you have a single-CPU system with an IO-APIC, you can say Y here
1005 to use it. If you say Y here even though your machine doesn't have
1006 an IO-APIC, then the kernel will still run with no slowdown at all.
1008 config X86_LOCAL_APIC
1010 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1011 select IRQ_DOMAIN_HIERARCHY
1012 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1016 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1018 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1019 bool "Reroute for broken boot IRQs"
1020 depends on X86_IO_APIC
1022 This option enables a workaround that fixes a source of
1023 spurious interrupts. This is recommended when threaded
1024 interrupt handling is used on systems where the generation of
1025 superfluous "boot interrupts" cannot be disabled.
1027 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1028 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1029 kernel does during interrupt handling). On chipsets where this
1030 boot IRQ generation cannot be disabled, this workaround keeps
1031 the original IRQ line masked so that only the equivalent "boot
1032 IRQ" is delivered to the CPUs. The workaround also tells the
1033 kernel to set up the IRQ handler on the boot IRQ line. In this
1034 way only one interrupt is delivered to the kernel. Otherwise
1035 the spurious second interrupt may cause the kernel to bring
1036 down (vital) interrupt lines.
1038 Only affects "broken" chipsets. Interrupt sharing may be
1039 increased on these systems.
1042 bool "Machine Check / overheating reporting"
1043 select GENERIC_ALLOCATOR
1046 Machine Check support allows the processor to notify the
1047 kernel if it detects a problem (e.g. overheating, data corruption).
1048 The action the kernel takes depends on the severity of the problem,
1049 ranging from warning messages to halting the machine.
1051 config X86_MCELOG_LEGACY
1052 bool "Support for deprecated /dev/mcelog character device"
1055 Enable support for /dev/mcelog which is needed by the old mcelog
1056 userspace logging daemon. Consider switching to the new generation
1059 config X86_MCE_INTEL
1061 prompt "Intel MCE features"
1062 depends on X86_MCE && X86_LOCAL_APIC
1064 Additional support for intel specific MCE features such as
1065 the thermal monitor.
1069 prompt "AMD MCE features"
1070 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1072 Additional support for AMD specific MCE features such as
1073 the DRAM Error Threshold.
1075 config X86_ANCIENT_MCE
1076 bool "Support for old Pentium 5 / WinChip machine checks"
1077 depends on X86_32 && X86_MCE
1079 Include support for machine check handling on old Pentium 5 or WinChip
1080 systems. These typically need to be enabled explicitly on the command
1083 config X86_MCE_THRESHOLD
1084 depends on X86_MCE_AMD || X86_MCE_INTEL
1087 config X86_MCE_INJECT
1088 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1089 tristate "Machine check injector support"
1091 Provide support for injecting machine checks for testing purposes.
1092 If you don't know what a machine check is and you don't do kernel
1093 QA it is safe to say n.
1095 config X86_THERMAL_VECTOR
1097 depends on X86_MCE_INTEL
1099 source "arch/x86/events/Kconfig"
1101 config X86_LEGACY_VM86
1102 bool "Legacy VM86 support"
1106 This option allows user programs to put the CPU into V8086
1107 mode, which is an 80286-era approximation of 16-bit real mode.
1109 Some very old versions of X and/or vbetool require this option
1110 for user mode setting. Similarly, DOSEMU will use it if
1111 available to accelerate real mode DOS programs. However, any
1112 recent version of DOSEMU, X, or vbetool should be fully
1113 functional even without kernel VM86 support, as they will all
1114 fall back to software emulation. Nevertheless, if you are using
1115 a 16-bit DOS program where 16-bit performance matters, vm86
1116 mode might be faster than emulation and you might want to
1119 Note that any app that works on a 64-bit kernel is unlikely to
1120 need this option, as 64-bit kernels don't, and can't, support
1121 V8086 mode. This option is also unrelated to 16-bit protected
1122 mode and is not needed to run most 16-bit programs under Wine.
1124 Enabling this option increases the complexity of the kernel
1125 and slows down exception handling a tiny bit.
1127 If unsure, say N here.
1131 default X86_LEGACY_VM86
1134 bool "Enable support for 16-bit segments" if EXPERT
1136 depends on MODIFY_LDT_SYSCALL
1138 This option is required by programs like Wine to run 16-bit
1139 protected mode legacy code on x86 processors. Disabling
1140 this option saves about 300 bytes on i386, or around 6K text
1141 plus 16K runtime memory on x86-64,
1145 depends on X86_16BIT && X86_32
1149 depends on X86_16BIT && X86_64
1151 config X86_VSYSCALL_EMULATION
1152 bool "Enable vsyscall emulation" if EXPERT
1156 This enables emulation of the legacy vsyscall page. Disabling
1157 it is roughly equivalent to booting with vsyscall=none, except
1158 that it will also disable the helpful warning if a program
1159 tries to use a vsyscall. With this option set to N, offending
1160 programs will just segfault, citing addresses of the form
1163 This option is required by many programs built before 2013, and
1164 care should be used even with newer programs if set to N.
1166 Disabling this option saves about 7K of kernel size and
1167 possibly 4K of additional runtime pagetable memory.
1170 tristate "Toshiba Laptop support"
1173 This adds a driver to safely access the System Management Mode of
1174 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1175 not work on models with a Phoenix BIOS. The System Management Mode
1176 is used to set the BIOS and power saving options on Toshiba portables.
1178 For information on utilities to make use of this driver see the
1179 Toshiba Linux utilities web site at:
1180 <http://www.buzzard.org.uk/toshiba/>.
1182 Say Y if you intend to run this kernel on a Toshiba portable.
1186 tristate "Dell i8k legacy laptop support"
1188 select SENSORS_DELL_SMM
1190 This option enables legacy /proc/i8k userspace interface in hwmon
1191 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1192 temperature and allows controlling fan speeds of Dell laptops via
1193 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1194 it reports also power and hotkey status. For fan speed control is
1195 needed userspace package i8kutils.
1197 Say Y if you intend to run this kernel on old Dell laptops or want to
1198 use userspace package i8kutils.
1201 config X86_REBOOTFIXUPS
1202 bool "Enable X86 board specific fixups for reboot"
1205 This enables chipset and/or board specific fixups to be done
1206 in order to get reboot to work correctly. This is only needed on
1207 some combinations of hardware and BIOS. The symptom, for which
1208 this config is intended, is when reboot ends with a stalled/hung
1211 Currently, the only fixup is for the Geode machines using
1212 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1214 Say Y if you want to enable the fixup. Currently, it's safe to
1215 enable this option even if you don't need it.
1219 bool "CPU microcode loading support"
1221 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1224 If you say Y here, you will be able to update the microcode on
1225 Intel and AMD processors. The Intel support is for the IA32 family,
1226 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1227 AMD support is for families 0x10 and later. You will obviously need
1228 the actual microcode binary data itself which is not shipped with
1231 The preferred method to load microcode from a detached initrd is described
1232 in Documentation/x86/early-microcode.txt. For that you need to enable
1233 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1234 initrd for microcode blobs.
1236 In addition, you can build-in the microcode into the kernel. For that you
1237 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1238 to the CONFIG_EXTRA_FIRMWARE config option.
1240 config MICROCODE_INTEL
1241 bool "Intel microcode loading support"
1242 depends on MICROCODE
1246 This options enables microcode patch loading support for Intel
1249 For the current Intel microcode data package go to
1250 <https://downloadcenter.intel.com> and search for
1251 'Linux Processor Microcode Data File'.
1253 config MICROCODE_AMD
1254 bool "AMD microcode loading support"
1255 depends on MICROCODE
1258 If you select this option, microcode patch loading support for AMD
1259 processors will be enabled.
1261 config MICROCODE_OLD_INTERFACE
1263 depends on MICROCODE
1266 tristate "/dev/cpu/*/msr - Model-specific register support"
1268 This device gives privileged processes access to the x86
1269 Model-Specific Registers (MSRs). It is a character device with
1270 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1271 MSR accesses are directed to a specific CPU on multi-processor
1275 tristate "/dev/cpu/*/cpuid - CPU information support"
1277 This device gives processes access to the x86 CPUID instruction to
1278 be executed on a specific processor. It is a character device
1279 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1283 prompt "High Memory Support"
1290 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1291 However, the address space of 32-bit x86 processors is only 4
1292 Gigabytes large. That means that, if you have a large amount of
1293 physical memory, not all of it can be "permanently mapped" by the
1294 kernel. The physical memory that's not permanently mapped is called
1297 If you are compiling a kernel which will never run on a machine with
1298 more than 1 Gigabyte total physical RAM, answer "off" here (default
1299 choice and suitable for most users). This will result in a "3GB/1GB"
1300 split: 3GB are mapped so that each process sees a 3GB virtual memory
1301 space and the remaining part of the 4GB virtual memory space is used
1302 by the kernel to permanently map as much physical memory as
1305 If the machine has between 1 and 4 Gigabytes physical RAM, then
1308 If more than 4 Gigabytes is used then answer "64GB" here. This
1309 selection turns Intel PAE (Physical Address Extension) mode on.
1310 PAE implements 3-level paging on IA32 processors. PAE is fully
1311 supported by Linux, PAE mode is implemented on all recent Intel
1312 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1313 then the kernel will not boot on CPUs that don't support PAE!
1315 The actual amount of total physical memory will either be
1316 auto detected or can be forced by using a kernel command line option
1317 such as "mem=256M". (Try "man bootparam" or see the documentation of
1318 your boot loader (lilo or loadlin) about how to pass options to the
1319 kernel at boot time.)
1321 If unsure, say "off".
1326 Select this if you have a 32-bit processor and between 1 and 4
1327 gigabytes of physical RAM.
1334 Select this if you have a 32-bit processor and more than 4
1335 gigabytes of physical RAM.
1340 prompt "Memory split" if EXPERT
1344 Select the desired split between kernel and user memory.
1346 If the address range available to the kernel is less than the
1347 physical memory installed, the remaining memory will be available
1348 as "high memory". Accessing high memory is a little more costly
1349 than low memory, as it needs to be mapped into the kernel first.
1350 Note that increasing the kernel address space limits the range
1351 available to user programs, making the address space there
1352 tighter. Selecting anything other than the default 3G/1G split
1353 will also likely make your kernel incompatible with binary-only
1356 If you are not absolutely sure what you are doing, leave this
1360 bool "3G/1G user/kernel split"
1361 config VMSPLIT_3G_OPT
1363 bool "3G/1G user/kernel split (for full 1G low memory)"
1365 bool "2G/2G user/kernel split"
1366 config VMSPLIT_2G_OPT
1368 bool "2G/2G user/kernel split (for full 2G low memory)"
1370 bool "1G/3G user/kernel split"
1375 default 0xB0000000 if VMSPLIT_3G_OPT
1376 default 0x80000000 if VMSPLIT_2G
1377 default 0x78000000 if VMSPLIT_2G_OPT
1378 default 0x40000000 if VMSPLIT_1G
1384 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1387 bool "PAE (Physical Address Extension) Support"
1388 depends on X86_32 && !HIGHMEM4G
1391 PAE is required for NX support, and furthermore enables
1392 larger swapspace support for non-overcommit purposes. It
1393 has the cost of more pagetable lookup overhead, and also
1394 consumes more pagetable space per process.
1396 config ARCH_PHYS_ADDR_T_64BIT
1398 depends on X86_64 || X86_PAE
1400 config ARCH_DMA_ADDR_T_64BIT
1402 depends on X86_64 || HIGHMEM64G
1404 config X86_DIRECT_GBPAGES
1406 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1408 Certain kernel features effectively disable kernel
1409 linear 1 GB mappings (even if the CPU otherwise
1410 supports them), so don't confuse the user by printing
1411 that we have them enabled.
1413 # Common NUMA Features
1415 bool "Numa Memory Allocation and Scheduler Support"
1417 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1418 default y if X86_BIGSMP
1420 Enable NUMA (Non Uniform Memory Access) support.
1422 The kernel will try to allocate memory used by a CPU on the
1423 local memory controller of the CPU and add some more
1424 NUMA awareness to the kernel.
1426 For 64-bit this is recommended if the system is Intel Core i7
1427 (or later), AMD Opteron, or EM64T NUMA.
1429 For 32-bit this is only needed if you boot a 32-bit
1430 kernel on a 64-bit NUMA platform.
1432 Otherwise, you should say N.
1436 prompt "Old style AMD Opteron NUMA detection"
1437 depends on X86_64 && NUMA && PCI
1439 Enable AMD NUMA node topology detection. You should say Y here if
1440 you have a multi processor AMD system. This uses an old method to
1441 read the NUMA configuration directly from the builtin Northbridge
1442 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1443 which also takes priority if both are compiled in.
1445 config X86_64_ACPI_NUMA
1447 prompt "ACPI NUMA detection"
1448 depends on X86_64 && NUMA && ACPI && PCI
1451 Enable ACPI SRAT based node topology detection.
1453 # Some NUMA nodes have memory ranges that span
1454 # other nodes. Even though a pfn is valid and
1455 # between a node's start and end pfns, it may not
1456 # reside on that node. See memmap_init_zone()
1458 config NODES_SPAN_OTHER_NODES
1460 depends on X86_64_ACPI_NUMA
1463 bool "NUMA emulation"
1466 Enable NUMA emulation. A flat machine will be split
1467 into virtual nodes when booted with "numa=fake=N", where N is the
1468 number of nodes. This is only useful for debugging.
1471 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1473 default "10" if MAXSMP
1474 default "6" if X86_64
1476 depends on NEED_MULTIPLE_NODES
1478 Specify the maximum number of NUMA Nodes available on the target
1479 system. Increases memory reserved to accommodate various tables.
1481 config ARCH_HAVE_MEMORY_PRESENT
1483 depends on X86_32 && DISCONTIGMEM
1485 config NEED_NODE_MEMMAP_SIZE
1487 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1489 config ARCH_FLATMEM_ENABLE
1491 depends on X86_32 && !NUMA
1493 config ARCH_DISCONTIGMEM_ENABLE
1495 depends on NUMA && X86_32
1497 config ARCH_DISCONTIGMEM_DEFAULT
1499 depends on NUMA && X86_32
1501 config ARCH_SPARSEMEM_ENABLE
1503 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1504 select SPARSEMEM_STATIC if X86_32
1505 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1507 config ARCH_SPARSEMEM_DEFAULT
1511 config ARCH_SELECT_MEMORY_MODEL
1513 depends on ARCH_SPARSEMEM_ENABLE
1515 config ARCH_MEMORY_PROBE
1516 bool "Enable sysfs memory/probe interface"
1517 depends on X86_64 && MEMORY_HOTPLUG
1519 This option enables a sysfs memory/probe interface for testing.
1520 See Documentation/memory-hotplug.txt for more information.
1521 If you are unsure how to answer this question, answer N.
1523 config ARCH_PROC_KCORE_TEXT
1525 depends on X86_64 && PROC_KCORE
1527 config ILLEGAL_POINTER_VALUE
1530 default 0xdead000000000000 if X86_64
1534 config X86_PMEM_LEGACY_DEVICE
1537 config X86_PMEM_LEGACY
1538 tristate "Support non-standard NVDIMMs and ADR protected memory"
1539 depends on PHYS_ADDR_T_64BIT
1541 select X86_PMEM_LEGACY_DEVICE
1544 Treat memory marked using the non-standard e820 type of 12 as used
1545 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1546 The kernel will offer these regions to the 'pmem' driver so
1547 they can be used for persistent storage.
1552 bool "Allocate 3rd-level pagetables from highmem"
1555 The VM uses one page table entry for each page of physical memory.
1556 For systems with a lot of RAM, this can be wasteful of precious
1557 low memory. Setting this option will put user-space page table
1558 entries in high memory.
1560 config X86_CHECK_BIOS_CORRUPTION
1561 bool "Check for low memory corruption"
1563 Periodically check for memory corruption in low memory, which
1564 is suspected to be caused by BIOS. Even when enabled in the
1565 configuration, it is disabled at runtime. Enable it by
1566 setting "memory_corruption_check=1" on the kernel command
1567 line. By default it scans the low 64k of memory every 60
1568 seconds; see the memory_corruption_check_size and
1569 memory_corruption_check_period parameters in
1570 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1572 When enabled with the default parameters, this option has
1573 almost no overhead, as it reserves a relatively small amount
1574 of memory and scans it infrequently. It both detects corruption
1575 and prevents it from affecting the running system.
1577 It is, however, intended as a diagnostic tool; if repeatable
1578 BIOS-originated corruption always affects the same memory,
1579 you can use memmap= to prevent the kernel from using that
1582 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1583 bool "Set the default setting of memory_corruption_check"
1584 depends on X86_CHECK_BIOS_CORRUPTION
1587 Set whether the default state of memory_corruption_check is
1590 config X86_RESERVE_LOW
1591 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1595 Specify the amount of low memory to reserve for the BIOS.
1597 The first page contains BIOS data structures that the kernel
1598 must not use, so that page must always be reserved.
1600 By default we reserve the first 64K of physical RAM, as a
1601 number of BIOSes are known to corrupt that memory range
1602 during events such as suspend/resume or monitor cable
1603 insertion, so it must not be used by the kernel.
1605 You can set this to 4 if you are absolutely sure that you
1606 trust the BIOS to get all its memory reservations and usages
1607 right. If you know your BIOS have problems beyond the
1608 default 64K area, you can set this to 640 to avoid using the
1609 entire low memory range.
1611 If you have doubts about the BIOS (e.g. suspend/resume does
1612 not work or there's kernel crashes after certain hardware
1613 hotplug events) then you might want to enable
1614 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1615 typical corruption patterns.
1617 Leave this to the default value of 64 if you are unsure.
1619 config MATH_EMULATION
1621 depends on MODIFY_LDT_SYSCALL
1622 prompt "Math emulation" if X86_32
1624 Linux can emulate a math coprocessor (used for floating point
1625 operations) if you don't have one. 486DX and Pentium processors have
1626 a math coprocessor built in, 486SX and 386 do not, unless you added
1627 a 487DX or 387, respectively. (The messages during boot time can
1628 give you some hints here ["man dmesg"].) Everyone needs either a
1629 coprocessor or this emulation.
1631 If you don't have a math coprocessor, you need to say Y here; if you
1632 say Y here even though you have a coprocessor, the coprocessor will
1633 be used nevertheless. (This behavior can be changed with the kernel
1634 command line option "no387", which comes handy if your coprocessor
1635 is broken. Try "man bootparam" or see the documentation of your boot
1636 loader (lilo or loadlin) about how to pass options to the kernel at
1637 boot time.) This means that it is a good idea to say Y here if you
1638 intend to use this kernel on different machines.
1640 More information about the internals of the Linux math coprocessor
1641 emulation can be found in <file:arch/x86/math-emu/README>.
1643 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1644 kernel, it won't hurt.
1648 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1650 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1651 the Memory Type Range Registers (MTRRs) may be used to control
1652 processor access to memory ranges. This is most useful if you have
1653 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1654 allows bus write transfers to be combined into a larger transfer
1655 before bursting over the PCI/AGP bus. This can increase performance
1656 of image write operations 2.5 times or more. Saying Y here creates a
1657 /proc/mtrr file which may be used to manipulate your processor's
1658 MTRRs. Typically the X server should use this.
1660 This code has a reasonably generic interface so that similar
1661 control registers on other processors can be easily supported
1664 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1665 Registers (ARRs) which provide a similar functionality to MTRRs. For
1666 these, the ARRs are used to emulate the MTRRs.
1667 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1668 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1669 write-combining. All of these processors are supported by this code
1670 and it makes sense to say Y here if you have one of them.
1672 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1673 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1674 can lead to all sorts of problems, so it's good to say Y here.
1676 You can safely say Y even if your machine doesn't have MTRRs, you'll
1677 just add about 9 KB to your kernel.
1679 See <file:Documentation/x86/mtrr.txt> for more information.
1681 config MTRR_SANITIZER
1683 prompt "MTRR cleanup support"
1686 Convert MTRR layout from continuous to discrete, so X drivers can
1687 add writeback entries.
1689 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1690 The largest mtrr entry size for a continuous block can be set with
1695 config MTRR_SANITIZER_ENABLE_DEFAULT
1696 int "MTRR cleanup enable value (0-1)"
1699 depends on MTRR_SANITIZER
1701 Enable mtrr cleanup default value
1703 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1704 int "MTRR cleanup spare reg num (0-7)"
1707 depends on MTRR_SANITIZER
1709 mtrr cleanup spare entries default, it can be changed via
1710 mtrr_spare_reg_nr=N on the kernel command line.
1714 prompt "x86 PAT support" if EXPERT
1717 Use PAT attributes to setup page level cache control.
1719 PATs are the modern equivalents of MTRRs and are much more
1720 flexible than MTRRs.
1722 Say N here if you see bootup problems (boot crash, boot hang,
1723 spontaneous reboots) or a non-working video driver.
1727 config ARCH_USES_PG_UNCACHED
1733 prompt "x86 architectural random number generator" if EXPERT
1735 Enable the x86 architectural RDRAND instruction
1736 (Intel Bull Mountain technology) to generate random numbers.
1737 If supported, this is a high bandwidth, cryptographically
1738 secure hardware random number generator.
1742 prompt "Supervisor Mode Access Prevention" if EXPERT
1744 Supervisor Mode Access Prevention (SMAP) is a security
1745 feature in newer Intel processors. There is a small
1746 performance cost if this enabled and turned on; there is
1747 also a small increase in the kernel size if this is enabled.
1751 config X86_INTEL_MPX
1752 prompt "Intel MPX (Memory Protection Extensions)"
1754 depends on CPU_SUP_INTEL
1756 MPX provides hardware features that can be used in
1757 conjunction with compiler-instrumented code to check
1758 memory references. It is designed to detect buffer
1759 overflow or underflow bugs.
1761 This option enables running applications which are
1762 instrumented or otherwise use MPX. It does not use MPX
1763 itself inside the kernel or to protect the kernel
1764 against bad memory references.
1766 Enabling this option will make the kernel larger:
1767 ~8k of kernel text and 36 bytes of data on a 64-bit
1768 defconfig. It adds a long to the 'mm_struct' which
1769 will increase the kernel memory overhead of each
1770 process and adds some branches to paths used during
1771 exec() and munmap().
1773 For details, see Documentation/x86/intel_mpx.txt
1777 config X86_INTEL_MEMORY_PROTECTION_KEYS
1778 prompt "Intel Memory Protection Keys"
1780 # Note: only available in 64-bit mode
1781 depends on CPU_SUP_INTEL && X86_64
1782 select ARCH_USES_HIGH_VMA_FLAGS
1783 select ARCH_HAS_PKEYS
1785 Memory Protection Keys provides a mechanism for enforcing
1786 page-based protections, but without requiring modification of the
1787 page tables when an application changes protection domains.
1789 For details, see Documentation/x86/protection-keys.txt
1794 bool "EFI runtime service support"
1797 select EFI_RUNTIME_WRAPPERS
1799 This enables the kernel to use EFI runtime services that are
1800 available (such as the EFI variable services).
1802 This option is only useful on systems that have EFI firmware.
1803 In addition, you should use the latest ELILO loader available
1804 at <http://elilo.sourceforge.net> in order to take advantage
1805 of EFI runtime services. However, even with this option, the
1806 resultant kernel should continue to boot on existing non-EFI
1810 bool "EFI stub support"
1811 depends on EFI && !X86_USE_3DNOW
1814 This kernel feature allows a bzImage to be loaded directly
1815 by EFI firmware without the use of a bootloader.
1817 See Documentation/efi-stub.txt for more information.
1820 bool "EFI mixed-mode support"
1821 depends on EFI_STUB && X86_64
1823 Enabling this feature allows a 64-bit kernel to be booted
1824 on a 32-bit firmware, provided that your CPU supports 64-bit
1827 Note that it is not possible to boot a mixed-mode enabled
1828 kernel via the EFI boot stub - a bootloader that supports
1829 the EFI handover protocol must be used.
1835 prompt "Enable seccomp to safely compute untrusted bytecode"
1837 This kernel feature is useful for number crunching applications
1838 that may need to compute untrusted bytecode during their
1839 execution. By using pipes or other transports made available to
1840 the process as file descriptors supporting the read/write
1841 syscalls, it's possible to isolate those applications in
1842 their own address space using seccomp. Once seccomp is
1843 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1844 and the task is only allowed to execute a few safe syscalls
1845 defined by each seccomp mode.
1847 If unsure, say Y. Only embedded should say N here.
1849 source kernel/Kconfig.hz
1852 bool "kexec system call"
1855 kexec is a system call that implements the ability to shutdown your
1856 current kernel, and to start another kernel. It is like a reboot
1857 but it is independent of the system firmware. And like a reboot
1858 you can start any kernel with it, not just Linux.
1860 The name comes from the similarity to the exec system call.
1862 It is an ongoing process to be certain the hardware in a machine
1863 is properly shutdown, so do not be surprised if this code does not
1864 initially work for you. As of this writing the exact hardware
1865 interface is strongly in flux, so no good recommendation can be
1869 bool "kexec file based system call"
1874 depends on CRYPTO_SHA256=y
1876 This is new version of kexec system call. This system call is
1877 file based and takes file descriptors as system call argument
1878 for kernel and initramfs as opposed to list of segments as
1879 accepted by previous system call.
1881 config KEXEC_VERIFY_SIG
1882 bool "Verify kernel signature during kexec_file_load() syscall"
1883 depends on KEXEC_FILE
1885 This option makes kernel signature verification mandatory for
1886 the kexec_file_load() syscall.
1888 In addition to that option, you need to enable signature
1889 verification for the corresponding kernel image type being
1890 loaded in order for this to work.
1892 config KEXEC_BZIMAGE_VERIFY_SIG
1893 bool "Enable bzImage signature verification support"
1894 depends on KEXEC_VERIFY_SIG
1895 depends on SIGNED_PE_FILE_VERIFICATION
1896 select SYSTEM_TRUSTED_KEYRING
1898 Enable bzImage signature verification support.
1901 bool "kernel crash dumps"
1902 depends on X86_64 || (X86_32 && HIGHMEM)
1904 Generate crash dump after being started by kexec.
1905 This should be normally only set in special crash dump kernels
1906 which are loaded in the main kernel with kexec-tools into
1907 a specially reserved region and then later executed after
1908 a crash by kdump/kexec. The crash dump kernel must be compiled
1909 to a memory address not used by the main kernel or BIOS using
1910 PHYSICAL_START, or it must be built as a relocatable image
1911 (CONFIG_RELOCATABLE=y).
1912 For more details see Documentation/kdump/kdump.txt
1916 depends on KEXEC && HIBERNATION
1918 Jump between original kernel and kexeced kernel and invoke
1919 code in physical address mode via KEXEC
1921 config PHYSICAL_START
1922 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1925 This gives the physical address where the kernel is loaded.
1927 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1928 bzImage will decompress itself to above physical address and
1929 run from there. Otherwise, bzImage will run from the address where
1930 it has been loaded by the boot loader and will ignore above physical
1933 In normal kdump cases one does not have to set/change this option
1934 as now bzImage can be compiled as a completely relocatable image
1935 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1936 address. This option is mainly useful for the folks who don't want
1937 to use a bzImage for capturing the crash dump and want to use a
1938 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1939 to be specifically compiled to run from a specific memory area
1940 (normally a reserved region) and this option comes handy.
1942 So if you are using bzImage for capturing the crash dump,
1943 leave the value here unchanged to 0x1000000 and set
1944 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1945 for capturing the crash dump change this value to start of
1946 the reserved region. In other words, it can be set based on
1947 the "X" value as specified in the "crashkernel=YM@XM"
1948 command line boot parameter passed to the panic-ed
1949 kernel. Please take a look at Documentation/kdump/kdump.txt
1950 for more details about crash dumps.
1952 Usage of bzImage for capturing the crash dump is recommended as
1953 one does not have to build two kernels. Same kernel can be used
1954 as production kernel and capture kernel. Above option should have
1955 gone away after relocatable bzImage support is introduced. But it
1956 is present because there are users out there who continue to use
1957 vmlinux for dump capture. This option should go away down the
1960 Don't change this unless you know what you are doing.
1963 bool "Build a relocatable kernel"
1966 This builds a kernel image that retains relocation information
1967 so it can be loaded someplace besides the default 1MB.
1968 The relocations tend to make the kernel binary about 10% larger,
1969 but are discarded at runtime.
1971 One use is for the kexec on panic case where the recovery kernel
1972 must live at a different physical address than the primary
1975 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1976 it has been loaded at and the compile time physical address
1977 (CONFIG_PHYSICAL_START) is used as the minimum location.
1979 config RANDOMIZE_BASE
1980 bool "Randomize the address of the kernel image (KASLR)"
1981 depends on RELOCATABLE
1984 In support of Kernel Address Space Layout Randomization (KASLR),
1985 this randomizes the physical address at which the kernel image
1986 is decompressed and the virtual address where the kernel
1987 image is mapped, as a security feature that deters exploit
1988 attempts relying on knowledge of the location of kernel
1991 On 64-bit, the kernel physical and virtual addresses are
1992 randomized separately. The physical address will be anywhere
1993 between 16MB and the top of physical memory (up to 64TB). The
1994 virtual address will be randomized from 16MB up to 1GB (9 bits
1995 of entropy). Note that this also reduces the memory space
1996 available to kernel modules from 1.5GB to 1GB.
1998 On 32-bit, the kernel physical and virtual addresses are
1999 randomized together. They will be randomized from 16MB up to
2000 512MB (8 bits of entropy).
2002 Entropy is generated using the RDRAND instruction if it is
2003 supported. If RDTSC is supported, its value is mixed into
2004 the entropy pool as well. If neither RDRAND nor RDTSC are
2005 supported, then entropy is read from the i8254 timer. The
2006 usable entropy is limited by the kernel being built using
2007 2GB addressing, and that PHYSICAL_ALIGN must be at a
2008 minimum of 2MB. As a result, only 10 bits of entropy are
2009 theoretically possible, but the implementations are further
2010 limited due to memory layouts.
2014 # Relocation on x86 needs some additional build support
2015 config X86_NEED_RELOCS
2017 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2019 config PHYSICAL_ALIGN
2020 hex "Alignment value to which kernel should be aligned"
2022 range 0x2000 0x1000000 if X86_32
2023 range 0x200000 0x1000000 if X86_64
2025 This value puts the alignment restrictions on physical address
2026 where kernel is loaded and run from. Kernel is compiled for an
2027 address which meets above alignment restriction.
2029 If bootloader loads the kernel at a non-aligned address and
2030 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2031 address aligned to above value and run from there.
2033 If bootloader loads the kernel at a non-aligned address and
2034 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2035 load address and decompress itself to the address it has been
2036 compiled for and run from there. The address for which kernel is
2037 compiled already meets above alignment restrictions. Hence the
2038 end result is that kernel runs from a physical address meeting
2039 above alignment restrictions.
2041 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2042 this value must be a multiple of 0x200000.
2044 Don't change this unless you know what you are doing.
2046 config RANDOMIZE_MEMORY
2047 bool "Randomize the kernel memory sections"
2049 depends on RANDOMIZE_BASE
2050 default RANDOMIZE_BASE
2052 Randomizes the base virtual address of kernel memory sections
2053 (physical memory mapping, vmalloc & vmemmap). This security feature
2054 makes exploits relying on predictable memory locations less reliable.
2056 The order of allocations remains unchanged. Entropy is generated in
2057 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2058 configuration have in average 30,000 different possible virtual
2059 addresses for each memory section.
2063 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2064 hex "Physical memory mapping padding" if EXPERT
2065 depends on RANDOMIZE_MEMORY
2066 default "0xa" if MEMORY_HOTPLUG
2068 range 0x1 0x40 if MEMORY_HOTPLUG
2071 Define the padding in terabytes added to the existing physical
2072 memory size during kernel memory randomization. It is useful
2073 for memory hotplug support but reduces the entropy available for
2074 address randomization.
2076 If unsure, leave at the default value.
2079 bool "Support for hot-pluggable CPUs"
2082 Say Y here to allow turning CPUs off and on. CPUs can be
2083 controlled through /sys/devices/system/cpu.
2084 ( Note: power management support will enable this option
2085 automatically on SMP systems. )
2086 Say N if you want to disable CPU hotplug.
2088 config BOOTPARAM_HOTPLUG_CPU0
2089 bool "Set default setting of cpu0_hotpluggable"
2091 depends on HOTPLUG_CPU
2093 Set whether default state of cpu0_hotpluggable is on or off.
2095 Say Y here to enable CPU0 hotplug by default. If this switch
2096 is turned on, there is no need to give cpu0_hotplug kernel
2097 parameter and the CPU0 hotplug feature is enabled by default.
2099 Please note: there are two known CPU0 dependencies if you want
2100 to enable the CPU0 hotplug feature either by this switch or by
2101 cpu0_hotplug kernel parameter.
2103 First, resume from hibernate or suspend always starts from CPU0.
2104 So hibernate and suspend are prevented if CPU0 is offline.
2106 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2107 offline if any interrupt can not migrate out of CPU0. There may
2108 be other CPU0 dependencies.
2110 Please make sure the dependencies are under your control before
2111 you enable this feature.
2113 Say N if you don't want to enable CPU0 hotplug feature by default.
2114 You still can enable the CPU0 hotplug feature at boot by kernel
2115 parameter cpu0_hotplug.
2117 config DEBUG_HOTPLUG_CPU0
2119 prompt "Debug CPU0 hotplug"
2120 depends on HOTPLUG_CPU
2122 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2123 soon as possible and boots up userspace with CPU0 offlined. User
2124 can online CPU0 back after boot time.
2126 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2127 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2128 compilation or giving cpu0_hotplug kernel parameter at boot.
2134 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2135 depends on COMPAT_32
2137 Certain buggy versions of glibc will crash if they are
2138 presented with a 32-bit vDSO that is not mapped at the address
2139 indicated in its segment table.
2141 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2142 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2143 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2144 the only released version with the bug, but OpenSUSE 9
2145 contains a buggy "glibc 2.3.2".
2147 The symptom of the bug is that everything crashes on startup, saying:
2148 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2150 Saying Y here changes the default value of the vdso32 boot
2151 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2152 This works around the glibc bug but hurts performance.
2154 If unsure, say N: if you are compiling your own kernel, you
2155 are unlikely to be using a buggy version of glibc.
2158 prompt "vsyscall table for legacy applications"
2160 default LEGACY_VSYSCALL_EMULATE
2162 Legacy user code that does not know how to find the vDSO expects
2163 to be able to issue three syscalls by calling fixed addresses in
2164 kernel space. Since this location is not randomized with ASLR,
2165 it can be used to assist security vulnerability exploitation.
2167 This setting can be changed at boot time via the kernel command
2168 line parameter vsyscall=[native|emulate|none].
2170 On a system with recent enough glibc (2.14 or newer) and no
2171 static binaries, you can say None without a performance penalty
2172 to improve security.
2174 If unsure, select "Emulate".
2176 config LEGACY_VSYSCALL_NATIVE
2179 Actual executable code is located in the fixed vsyscall
2180 address mapping, implementing time() efficiently. Since
2181 this makes the mapping executable, it can be used during
2182 security vulnerability exploitation (traditionally as
2183 ROP gadgets). This configuration is not recommended.
2185 config LEGACY_VSYSCALL_EMULATE
2188 The kernel traps and emulates calls into the fixed
2189 vsyscall address mapping. This makes the mapping
2190 non-executable, but it still contains known contents,
2191 which could be used in certain rare security vulnerability
2192 exploits. This configuration is recommended when userspace
2193 still uses the vsyscall area.
2195 config LEGACY_VSYSCALL_NONE
2198 There will be no vsyscall mapping at all. This will
2199 eliminate any risk of ASLR bypass due to the vsyscall
2200 fixed address mapping. Attempts to use the vsyscalls
2201 will be reported to dmesg, so that either old or
2202 malicious userspace programs can be identified.
2207 bool "Built-in kernel command line"
2209 Allow for specifying boot arguments to the kernel at
2210 build time. On some systems (e.g. embedded ones), it is
2211 necessary or convenient to provide some or all of the
2212 kernel boot arguments with the kernel itself (that is,
2213 to not rely on the boot loader to provide them.)
2215 To compile command line arguments into the kernel,
2216 set this option to 'Y', then fill in the
2217 boot arguments in CONFIG_CMDLINE.
2219 Systems with fully functional boot loaders (i.e. non-embedded)
2220 should leave this option set to 'N'.
2223 string "Built-in kernel command string"
2224 depends on CMDLINE_BOOL
2227 Enter arguments here that should be compiled into the kernel
2228 image and used at boot time. If the boot loader provides a
2229 command line at boot time, it is appended to this string to
2230 form the full kernel command line, when the system boots.
2232 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2233 change this behavior.
2235 In most cases, the command line (whether built-in or provided
2236 by the boot loader) should specify the device for the root
2239 config CMDLINE_OVERRIDE
2240 bool "Built-in command line overrides boot loader arguments"
2241 depends on CMDLINE_BOOL
2243 Set this option to 'Y' to have the kernel ignore the boot loader
2244 command line, and use ONLY the built-in command line.
2246 This is used to work around broken boot loaders. This should
2247 be set to 'N' under normal conditions.
2249 config MODIFY_LDT_SYSCALL
2250 bool "Enable the LDT (local descriptor table)" if EXPERT
2253 Linux can allow user programs to install a per-process x86
2254 Local Descriptor Table (LDT) using the modify_ldt(2) system
2255 call. This is required to run 16-bit or segmented code such as
2256 DOSEMU or some Wine programs. It is also used by some very old
2257 threading libraries.
2259 Enabling this feature adds a small amount of overhead to
2260 context switches and increases the low-level kernel attack
2261 surface. Disabling it removes the modify_ldt(2) system call.
2263 Saying 'N' here may make sense for embedded or server kernels.
2265 source "kernel/livepatch/Kconfig"
2269 config ARCH_ENABLE_MEMORY_HOTPLUG
2271 depends on X86_64 || (X86_32 && HIGHMEM)
2273 config ARCH_ENABLE_MEMORY_HOTREMOVE
2275 depends on MEMORY_HOTPLUG
2277 config USE_PERCPU_NUMA_NODE_ID
2281 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2283 depends on X86_64 || X86_PAE
2285 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2287 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2289 menu "Power management and ACPI options"
2291 config ARCH_HIBERNATION_HEADER
2293 depends on X86_64 && HIBERNATION
2295 source "kernel/power/Kconfig"
2297 source "drivers/acpi/Kconfig"
2299 source "drivers/sfi/Kconfig"
2306 tristate "APM (Advanced Power Management) BIOS support"
2307 depends on X86_32 && PM_SLEEP
2309 APM is a BIOS specification for saving power using several different
2310 techniques. This is mostly useful for battery powered laptops with
2311 APM compliant BIOSes. If you say Y here, the system time will be
2312 reset after a RESUME operation, the /proc/apm device will provide
2313 battery status information, and user-space programs will receive
2314 notification of APM "events" (e.g. battery status change).
2316 If you select "Y" here, you can disable actual use of the APM
2317 BIOS by passing the "apm=off" option to the kernel at boot time.
2319 Note that the APM support is almost completely disabled for
2320 machines with more than one CPU.
2322 In order to use APM, you will need supporting software. For location
2323 and more information, read <file:Documentation/power/apm-acpi.txt>
2324 and the Battery Powered Linux mini-HOWTO, available from
2325 <http://www.tldp.org/docs.html#howto>.
2327 This driver does not spin down disk drives (see the hdparm(8)
2328 manpage ("man 8 hdparm") for that), and it doesn't turn off
2329 VESA-compliant "green" monitors.
2331 This driver does not support the TI 4000M TravelMate and the ACER
2332 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2333 desktop machines also don't have compliant BIOSes, and this driver
2334 may cause those machines to panic during the boot phase.
2336 Generally, if you don't have a battery in your machine, there isn't
2337 much point in using this driver and you should say N. If you get
2338 random kernel OOPSes or reboots that don't seem to be related to
2339 anything, try disabling/enabling this option (or disabling/enabling
2342 Some other things you should try when experiencing seemingly random,
2345 1) make sure that you have enough swap space and that it is
2347 2) pass the "no-hlt" option to the kernel
2348 3) switch on floating point emulation in the kernel and pass
2349 the "no387" option to the kernel
2350 4) pass the "floppy=nodma" option to the kernel
2351 5) pass the "mem=4M" option to the kernel (thereby disabling
2352 all but the first 4 MB of RAM)
2353 6) make sure that the CPU is not over clocked.
2354 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2355 8) disable the cache from your BIOS settings
2356 9) install a fan for the video card or exchange video RAM
2357 10) install a better fan for the CPU
2358 11) exchange RAM chips
2359 12) exchange the motherboard.
2361 To compile this driver as a module, choose M here: the
2362 module will be called apm.
2366 config APM_IGNORE_USER_SUSPEND
2367 bool "Ignore USER SUSPEND"
2369 This option will ignore USER SUSPEND requests. On machines with a
2370 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2371 series notebooks, it is necessary to say Y because of a BIOS bug.
2373 config APM_DO_ENABLE
2374 bool "Enable PM at boot time"
2376 Enable APM features at boot time. From page 36 of the APM BIOS
2377 specification: "When disabled, the APM BIOS does not automatically
2378 power manage devices, enter the Standby State, enter the Suspend
2379 State, or take power saving steps in response to CPU Idle calls."
2380 This driver will make CPU Idle calls when Linux is idle (unless this
2381 feature is turned off -- see "Do CPU IDLE calls", below). This
2382 should always save battery power, but more complicated APM features
2383 will be dependent on your BIOS implementation. You may need to turn
2384 this option off if your computer hangs at boot time when using APM
2385 support, or if it beeps continuously instead of suspending. Turn
2386 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2387 T400CDT. This is off by default since most machines do fine without
2392 bool "Make CPU Idle calls when idle"
2394 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2395 On some machines, this can activate improved power savings, such as
2396 a slowed CPU clock rate, when the machine is idle. These idle calls
2397 are made after the idle loop has run for some length of time (e.g.,
2398 333 mS). On some machines, this will cause a hang at boot time or
2399 whenever the CPU becomes idle. (On machines with more than one CPU,
2400 this option does nothing.)
2402 config APM_DISPLAY_BLANK
2403 bool "Enable console blanking using APM"
2405 Enable console blanking using the APM. Some laptops can use this to
2406 turn off the LCD backlight when the screen blanker of the Linux
2407 virtual console blanks the screen. Note that this is only used by
2408 the virtual console screen blanker, and won't turn off the backlight
2409 when using the X Window system. This also doesn't have anything to
2410 do with your VESA-compliant power-saving monitor. Further, this
2411 option doesn't work for all laptops -- it might not turn off your
2412 backlight at all, or it might print a lot of errors to the console,
2413 especially if you are using gpm.
2415 config APM_ALLOW_INTS
2416 bool "Allow interrupts during APM BIOS calls"
2418 Normally we disable external interrupts while we are making calls to
2419 the APM BIOS as a measure to lessen the effects of a badly behaving
2420 BIOS implementation. The BIOS should reenable interrupts if it
2421 needs to. Unfortunately, some BIOSes do not -- especially those in
2422 many of the newer IBM Thinkpads. If you experience hangs when you
2423 suspend, try setting this to Y. Otherwise, say N.
2427 source "drivers/cpufreq/Kconfig"
2429 source "drivers/cpuidle/Kconfig"
2431 source "drivers/idle/Kconfig"
2436 menu "Bus options (PCI etc.)"
2442 Find out whether you have a PCI motherboard. PCI is the name of a
2443 bus system, i.e. the way the CPU talks to the other stuff inside
2444 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2445 VESA. If you have PCI, say Y, otherwise N.
2448 prompt "PCI access mode"
2449 depends on X86_32 && PCI
2452 On PCI systems, the BIOS can be used to detect the PCI devices and
2453 determine their configuration. However, some old PCI motherboards
2454 have BIOS bugs and may crash if this is done. Also, some embedded
2455 PCI-based systems don't have any BIOS at all. Linux can also try to
2456 detect the PCI hardware directly without using the BIOS.
2458 With this option, you can specify how Linux should detect the
2459 PCI devices. If you choose "BIOS", the BIOS will be used,
2460 if you choose "Direct", the BIOS won't be used, and if you
2461 choose "MMConfig", then PCI Express MMCONFIG will be used.
2462 If you choose "Any", the kernel will try MMCONFIG, then the
2463 direct access method and falls back to the BIOS if that doesn't
2464 work. If unsure, go with the default, which is "Any".
2469 config PCI_GOMMCONFIG
2486 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2488 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2491 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2495 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2499 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2503 depends on PCI && XEN
2511 bool "Support mmconfig PCI config space access"
2512 depends on X86_64 && PCI && ACPI
2514 config PCI_CNB20LE_QUIRK
2515 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2518 Read the PCI windows out of the CNB20LE host bridge. This allows
2519 PCI hotplug to work on systems with the CNB20LE chipset which do
2522 There's no public spec for this chipset, and this functionality
2523 is known to be incomplete.
2525 You should say N unless you know you need this.
2527 source "drivers/pci/Kconfig"
2530 bool "ISA-style bus support on modern systems" if EXPERT
2533 Enables ISA-style drivers on modern systems. This is necessary to
2534 support PC/104 devices on X86_64 platforms.
2538 # x86_64 have no ISA slots, but can have ISA-style DMA.
2540 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2543 Enables ISA-style DMA support for devices requiring such controllers.
2551 Find out whether you have ISA slots on your motherboard. ISA is the
2552 name of a bus system, i.e. the way the CPU talks to the other stuff
2553 inside your box. Other bus systems are PCI, EISA, MicroChannel
2554 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2555 newer boards don't support it. If you have ISA, say Y, otherwise N.
2561 The Extended Industry Standard Architecture (EISA) bus was
2562 developed as an open alternative to the IBM MicroChannel bus.
2564 The EISA bus provided some of the features of the IBM MicroChannel
2565 bus while maintaining backward compatibility with cards made for
2566 the older ISA bus. The EISA bus saw limited use between 1988 and
2567 1995 when it was made obsolete by the PCI bus.
2569 Say Y here if you are building a kernel for an EISA-based machine.
2573 source "drivers/eisa/Kconfig"
2576 tristate "NatSemi SCx200 support"
2578 This provides basic support for National Semiconductor's
2579 (now AMD's) Geode processors. The driver probes for the
2580 PCI-IDs of several on-chip devices, so its a good dependency
2581 for other scx200_* drivers.
2583 If compiled as a module, the driver is named scx200.
2585 config SCx200HR_TIMER
2586 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2590 This driver provides a clocksource built upon the on-chip
2591 27MHz high-resolution timer. Its also a workaround for
2592 NSC Geode SC-1100's buggy TSC, which loses time when the
2593 processor goes idle (as is done by the scheduler). The
2594 other workaround is idle=poll boot option.
2597 bool "One Laptop Per Child support"
2604 Add support for detecting the unique features of the OLPC
2608 bool "OLPC XO-1 Power Management"
2609 depends on OLPC && MFD_CS5535 && PM_SLEEP
2612 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2615 bool "OLPC XO-1 Real Time Clock"
2616 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2618 Add support for the XO-1 real time clock, which can be used as a
2619 programmable wakeup source.
2622 bool "OLPC XO-1 SCI extras"
2623 depends on OLPC && OLPC_XO1_PM
2629 Add support for SCI-based features of the OLPC XO-1 laptop:
2630 - EC-driven system wakeups
2634 - AC adapter status updates
2635 - Battery status updates
2637 config OLPC_XO15_SCI
2638 bool "OLPC XO-1.5 SCI extras"
2639 depends on OLPC && ACPI
2642 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2643 - EC-driven system wakeups
2644 - AC adapter status updates
2645 - Battery status updates
2648 bool "PCEngines ALIX System Support (LED setup)"
2651 This option enables system support for the PCEngines ALIX.
2652 At present this just sets up LEDs for GPIO control on
2653 ALIX2/3/6 boards. However, other system specific setup should
2656 Note: You must still enable the drivers for GPIO and LED support
2657 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2659 Note: You have to set alix.force=1 for boards with Award BIOS.
2662 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2665 This option enables system support for the Soekris Engineering net5501.
2668 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2672 This option enables system support for the Traverse Technologies GEOS.
2675 bool "Technologic Systems TS-5500 platform support"
2677 select CHECK_SIGNATURE
2681 This option enables system support for the Technologic Systems TS-5500.
2687 depends on CPU_SUP_AMD && PCI
2689 source "drivers/pcmcia/Kconfig"
2692 tristate "RapidIO support"
2696 If enabled this option will include drivers and the core
2697 infrastructure code to support RapidIO interconnect devices.
2699 source "drivers/rapidio/Kconfig"
2702 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2704 Firmwares often provide initial graphics framebuffers so the BIOS,
2705 bootloader or kernel can show basic video-output during boot for
2706 user-guidance and debugging. Historically, x86 used the VESA BIOS
2707 Extensions and EFI-framebuffers for this, which are mostly limited
2709 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2710 framebuffers so the new generic system-framebuffer drivers can be
2711 used on x86. If the framebuffer is not compatible with the generic
2712 modes, it is adverticed as fallback platform framebuffer so legacy
2713 drivers like efifb, vesafb and uvesafb can pick it up.
2714 If this option is not selected, all system framebuffers are always
2715 marked as fallback platform framebuffers as usual.
2717 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2718 not be able to pick up generic system framebuffers if this option
2719 is selected. You are highly encouraged to enable simplefb as
2720 replacement if you select this option. simplefb can correctly deal
2721 with generic system framebuffers. But you should still keep vesafb
2722 and others enabled as fallback if a system framebuffer is
2723 incompatible with simplefb.
2730 menu "Executable file formats / Emulations"
2732 source "fs/Kconfig.binfmt"
2734 config IA32_EMULATION
2735 bool "IA32 Emulation"
2737 select ARCH_WANT_OLD_COMPAT_IPC
2739 select COMPAT_BINFMT_ELF
2740 select COMPAT_OLD_SIGACTION
2742 Include code to run legacy 32-bit programs under a
2743 64-bit kernel. You should likely turn this on, unless you're
2744 100% sure that you don't have any 32-bit programs left.
2747 tristate "IA32 a.out support"
2748 depends on IA32_EMULATION
2750 Support old a.out binaries in the 32bit emulation.
2753 bool "x32 ABI for 64-bit mode"
2756 Include code to run binaries for the x32 native 32-bit ABI
2757 for 64-bit processors. An x32 process gets access to the
2758 full 64-bit register file and wide data path while leaving
2759 pointers at 32 bits for smaller memory footprint.
2761 You will need a recent binutils (2.22 or later) with
2762 elf32_x86_64 support enabled to compile a kernel with this
2767 depends on IA32_EMULATION || X86_32
2769 select OLD_SIGSUSPEND3
2773 depends on IA32_EMULATION || X86_X32
2776 config COMPAT_FOR_U64_ALIGNMENT
2779 config SYSVIPC_COMPAT
2787 config HAVE_ATOMIC_IOMAP
2791 config X86_DEV_DMA_OPS
2793 depends on X86_64 || STA2X11
2795 config X86_DMA_REMAP
2799 config HAVE_GENERIC_GUP
2802 source "net/Kconfig"
2804 source "drivers/Kconfig"
2806 source "drivers/firmware/Kconfig"
2810 source "arch/x86/Kconfig.debug"
2812 source "security/Kconfig"
2814 source "crypto/Kconfig"
2816 source "arch/x86/kvm/Kconfig"
2818 source "lib/Kconfig"
projects / linux-2.6-block.git / blob