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_DEVMEM_IS_ALLOWED
50 select ARCH_HAS_ELF_RANDOMIZE
51 select ARCH_HAS_FAST_MULTIPLIER
52 select ARCH_HAS_GCOV_PROFILE_ALL
53 select ARCH_HAS_KCOV if X86_64
54 select ARCH_HAS_MMIO_FLUSH
55 select ARCH_HAS_PMEM_API if X86_64
56 select ARCH_HAS_SG_CHAIN
57 select ARCH_HAS_UBSAN_SANITIZE_ALL
58 select ARCH_HAVE_NMI_SAFE_CMPXCHG
59 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
60 select ARCH_MIGHT_HAVE_PC_PARPORT
61 select ARCH_MIGHT_HAVE_PC_SERIO
62 select ARCH_SUPPORTS_ATOMIC_RMW
63 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
64 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
65 select ARCH_USE_BUILTIN_BSWAP
66 select ARCH_USE_QUEUED_RWLOCKS
67 select ARCH_USE_QUEUED_SPINLOCKS
68 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
69 select ARCH_WANT_FRAME_POINTERS
70 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
71 select BUILDTIME_EXTABLE_SORT
73 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
74 select CLOCKSOURCE_WATCHDOG
75 select DCACHE_WORD_ACCESS
76 select EDAC_ATOMIC_SCRUB
78 select GENERIC_CLOCKEVENTS
79 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
80 select GENERIC_CLOCKEVENTS_MIN_ADJUST
81 select GENERIC_CMOS_UPDATE
82 select GENERIC_CPU_AUTOPROBE
83 select GENERIC_EARLY_IOREMAP
84 select GENERIC_FIND_FIRST_BIT
86 select GENERIC_IRQ_PROBE
87 select GENERIC_IRQ_SHOW
88 select GENERIC_PENDING_IRQ if SMP
89 select GENERIC_SMP_IDLE_THREAD
90 select GENERIC_STRNCPY_FROM_USER
91 select GENERIC_STRNLEN_USER
92 select GENERIC_TIME_VSYSCALL
93 select HAVE_ACPI_APEI if ACPI
94 select HAVE_ACPI_APEI_NMI if ACPI
95 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
96 select HAVE_ARCH_AUDITSYSCALL
97 select HAVE_ARCH_HARDENED_USERCOPY
98 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
99 select HAVE_ARCH_JUMP_LABEL
100 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
101 select HAVE_ARCH_KGDB
102 select HAVE_ARCH_KMEMCHECK
103 select HAVE_ARCH_MMAP_RND_BITS if MMU
104 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
105 select HAVE_ARCH_SECCOMP_FILTER
106 select HAVE_ARCH_TRACEHOOK
107 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
108 select HAVE_ARCH_VMAP_STACK if X86_64
109 select HAVE_ARCH_WITHIN_STACK_FRAMES
110 select HAVE_CC_STACKPROTECTOR
111 select HAVE_CMPXCHG_DOUBLE
112 select HAVE_CMPXCHG_LOCAL
113 select HAVE_CONTEXT_TRACKING if X86_64
114 select HAVE_COPY_THREAD_TLS
115 select HAVE_C_RECORDMCOUNT
116 select HAVE_DEBUG_KMEMLEAK
117 select HAVE_DEBUG_STACKOVERFLOW
118 select HAVE_DMA_API_DEBUG
119 select HAVE_DMA_CONTIGUOUS
120 select HAVE_DYNAMIC_FTRACE
121 select HAVE_DYNAMIC_FTRACE_WITH_REGS
122 select HAVE_EBPF_JIT if X86_64
123 select HAVE_EFFICIENT_UNALIGNED_ACCESS
124 select HAVE_EXIT_THREAD
125 select HAVE_FENTRY if X86_64
126 select HAVE_FTRACE_MCOUNT_RECORD
127 select HAVE_FUNCTION_GRAPH_TRACER
128 select HAVE_FUNCTION_TRACER
129 select HAVE_GCC_PLUGINS
130 select HAVE_HW_BREAKPOINT
132 select HAVE_IOREMAP_PROT
133 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
134 select HAVE_IRQ_TIME_ACCOUNTING
135 select HAVE_KERNEL_BZIP2
136 select HAVE_KERNEL_GZIP
137 select HAVE_KERNEL_LZ4
138 select HAVE_KERNEL_LZMA
139 select HAVE_KERNEL_LZO
140 select HAVE_KERNEL_XZ
142 select HAVE_KPROBES_ON_FTRACE
143 select HAVE_KRETPROBES
145 select HAVE_LIVEPATCH if X86_64
147 select HAVE_MEMBLOCK_NODE_MAP
148 select HAVE_MIXED_BREAKPOINTS_REGS
151 select HAVE_OPTPROBES
152 select HAVE_PCSPKR_PLATFORM
153 select HAVE_PERF_EVENTS
154 select HAVE_PERF_EVENTS_NMI
155 select HAVE_PERF_REGS
156 select HAVE_PERF_USER_STACK_DUMP
157 select HAVE_REGS_AND_STACK_ACCESS_API
158 select HAVE_STACK_VALIDATION if X86_64
159 select HAVE_SYSCALL_TRACEPOINTS
160 select HAVE_UNSTABLE_SCHED_CLOCK
161 select HAVE_USER_RETURN_NOTIFIER
162 select IRQ_FORCED_THREADING
165 select RTC_MC146818_LIB
168 select SYSCTL_EXCEPTION_TRACE
169 select THREAD_INFO_IN_TASK
170 select USER_STACKTRACE_SUPPORT
172 select X86_FEATURE_NAMES if PROC_FS
174 config INSTRUCTION_DECODER
176 depends on KPROBES || PERF_EVENTS || UPROBES
180 default "elf32-i386" if X86_32
181 default "elf64-x86-64" if X86_64
183 config ARCH_DEFCONFIG
185 default "arch/x86/configs/i386_defconfig" if X86_32
186 default "arch/x86/configs/x86_64_defconfig" if X86_64
188 config LOCKDEP_SUPPORT
191 config STACKTRACE_SUPPORT
197 config ARCH_MMAP_RND_BITS_MIN
201 config ARCH_MMAP_RND_BITS_MAX
205 config ARCH_MMAP_RND_COMPAT_BITS_MIN
208 config ARCH_MMAP_RND_COMPAT_BITS_MAX
214 config NEED_DMA_MAP_STATE
216 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
218 config NEED_SG_DMA_LENGTH
221 config GENERIC_ISA_DMA
223 depends on ISA_DMA_API
228 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
230 config GENERIC_BUG_RELATIVE_POINTERS
233 config GENERIC_HWEIGHT
236 config ARCH_MAY_HAVE_PC_FDC
238 depends on ISA_DMA_API
240 config RWSEM_XCHGADD_ALGORITHM
243 config GENERIC_CALIBRATE_DELAY
246 config ARCH_HAS_CPU_RELAX
249 config ARCH_HAS_CACHE_LINE_SIZE
252 config HAVE_SETUP_PER_CPU_AREA
255 config NEED_PER_CPU_EMBED_FIRST_CHUNK
258 config NEED_PER_CPU_PAGE_FIRST_CHUNK
261 config ARCH_HIBERNATION_POSSIBLE
264 config ARCH_SUSPEND_POSSIBLE
267 config ARCH_WANT_HUGE_PMD_SHARE
270 config ARCH_WANT_GENERAL_HUGETLB
279 config ARCH_SUPPORTS_OPTIMIZED_INLINING
282 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
285 config KASAN_SHADOW_OFFSET
288 default 0xdffffc0000000000
290 config HAVE_INTEL_TXT
292 depends on INTEL_IOMMU && ACPI
296 depends on X86_32 && SMP
300 depends on X86_64 && SMP
302 config X86_32_LAZY_GS
304 depends on X86_32 && !CC_STACKPROTECTOR
306 config ARCH_SUPPORTS_UPROBES
309 config FIX_EARLYCON_MEM
315 config PGTABLE_LEVELS
321 source "init/Kconfig"
322 source "kernel/Kconfig.freezer"
324 menu "Processor type and features"
327 bool "DMA memory allocation support" if EXPERT
330 DMA memory allocation support allows devices with less than 32-bit
331 addressing to allocate within the first 16MB of address space.
332 Disable if no such devices will be used.
337 bool "Symmetric multi-processing support"
339 This enables support for systems with more than one CPU. If you have
340 a system with only one CPU, say N. If you have a system with more
343 If you say N here, the kernel will run on uni- and multiprocessor
344 machines, but will use only one CPU of a multiprocessor machine. If
345 you say Y here, the kernel will run on many, but not all,
346 uniprocessor machines. On a uniprocessor machine, the kernel
347 will run faster if you say N here.
349 Note that if you say Y here and choose architecture "586" or
350 "Pentium" under "Processor family", the kernel will not work on 486
351 architectures. Similarly, multiprocessor kernels for the "PPro"
352 architecture may not work on all Pentium based boards.
354 People using multiprocessor machines who say Y here should also say
355 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
356 Management" code will be disabled if you say Y here.
358 See also <file:Documentation/x86/i386/IO-APIC.txt>,
359 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
360 <http://www.tldp.org/docs.html#howto>.
362 If you don't know what to do here, say N.
364 config X86_FEATURE_NAMES
365 bool "Processor feature human-readable names" if EMBEDDED
368 This option compiles in a table of x86 feature bits and corresponding
369 names. This is required to support /proc/cpuinfo and a few kernel
370 messages. You can disable this to save space, at the expense of
371 making those few kernel messages show numeric feature bits instead.
375 config X86_FAST_FEATURE_TESTS
376 bool "Fast CPU feature tests" if EMBEDDED
379 Some fast-paths in the kernel depend on the capabilities of the CPU.
380 Say Y here for the kernel to patch in the appropriate code at runtime
381 based on the capabilities of the CPU. The infrastructure for patching
382 code at runtime takes up some additional space; space-constrained
383 embedded systems may wish to say N here to produce smaller, slightly
387 bool "Support x2apic"
388 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
390 This enables x2apic support on CPUs that have this feature.
392 This allows 32-bit apic IDs (so it can support very large systems),
393 and accesses the local apic via MSRs not via mmio.
395 If you don't know what to do here, say N.
398 bool "Enable MPS table" if ACPI || SFI
400 depends on X86_LOCAL_APIC
402 For old smp systems that do not have proper acpi support. Newer systems
403 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
406 bool "Support for big SMP systems with more than 8 CPUs"
407 depends on X86_32 && SMP
409 This option is needed for the systems that have more than 8 CPUs
413 depends on X86_GOLDFISH
416 config X86_EXTENDED_PLATFORM
417 bool "Support for extended (non-PC) x86 platforms"
420 If you disable this option then the kernel will only support
421 standard PC platforms. (which covers the vast majority of
424 If you enable this option then you'll be able to select support
425 for the following (non-PC) 32 bit x86 platforms:
426 Goldfish (Android emulator)
429 SGI 320/540 (Visual Workstation)
430 STA2X11-based (e.g. Northville)
431 Moorestown MID devices
433 If you have one of these systems, or if you want to build a
434 generic distribution kernel, say Y here - otherwise say N.
438 config X86_EXTENDED_PLATFORM
439 bool "Support for extended (non-PC) x86 platforms"
442 If you disable this option then the kernel will only support
443 standard PC platforms. (which covers the vast majority of
446 If you enable this option then you'll be able to select support
447 for the following (non-PC) 64 bit x86 platforms:
452 If you have one of these systems, or if you want to build a
453 generic distribution kernel, say Y here - otherwise say N.
455 # This is an alphabetically sorted list of 64 bit extended platforms
456 # Please maintain the alphabetic order if and when there are additions
458 bool "Numascale NumaChip"
460 depends on X86_EXTENDED_PLATFORM
463 depends on X86_X2APIC
464 depends on PCI_MMCONFIG
466 Adds support for Numascale NumaChip large-SMP systems. Needed to
467 enable more than ~168 cores.
468 If you don't have one of these, you should say N here.
472 select HYPERVISOR_GUEST
474 depends on X86_64 && PCI
475 depends on X86_EXTENDED_PLATFORM
478 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
479 supposed to run on these EM64T-based machines. Only choose this option
480 if you have one of these machines.
483 bool "SGI Ultraviolet"
485 depends on X86_EXTENDED_PLATFORM
488 depends on X86_X2APIC
491 This option is needed in order to support SGI Ultraviolet systems.
492 If you don't have one of these, you should say N here.
494 # Following is an alphabetically sorted list of 32 bit extended platforms
495 # Please maintain the alphabetic order if and when there are additions
498 bool "Goldfish (Virtual Platform)"
499 depends on X86_EXTENDED_PLATFORM
501 Enable support for the Goldfish virtual platform used primarily
502 for Android development. Unless you are building for the Android
503 Goldfish emulator say N here.
506 bool "CE4100 TV platform"
508 depends on PCI_GODIRECT
509 depends on X86_IO_APIC
511 depends on X86_EXTENDED_PLATFORM
512 select X86_REBOOTFIXUPS
514 select OF_EARLY_FLATTREE
516 Select for the Intel CE media processor (CE4100) SOC.
517 This option compiles in support for the CE4100 SOC for settop
518 boxes and media devices.
521 bool "Intel MID platform support"
522 depends on X86_EXTENDED_PLATFORM
523 depends on X86_PLATFORM_DEVICES
525 depends on X86_64 || (PCI_GOANY && X86_32)
526 depends on X86_IO_APIC
532 select MFD_INTEL_MSIC
534 Select to build a kernel capable of supporting Intel MID (Mobile
535 Internet Device) platform systems which do not have the PCI legacy
536 interfaces. If you are building for a PC class system say N here.
538 Intel MID platforms are based on an Intel processor and chipset which
539 consume less power than most of the x86 derivatives.
541 config X86_INTEL_QUARK
542 bool "Intel Quark platform support"
544 depends on X86_EXTENDED_PLATFORM
545 depends on X86_PLATFORM_DEVICES
549 depends on X86_IO_APIC
554 Select to include support for Quark X1000 SoC.
555 Say Y here if you have a Quark based system such as the Arduino
556 compatible Intel Galileo.
558 config X86_INTEL_LPSS
559 bool "Intel Low Power Subsystem Support"
560 depends on X86 && ACPI
565 Select to build support for Intel Low Power Subsystem such as
566 found on Intel Lynxpoint PCH. Selecting this option enables
567 things like clock tree (common clock framework) and pincontrol
568 which are needed by the LPSS peripheral drivers.
570 config X86_AMD_PLATFORM_DEVICE
571 bool "AMD ACPI2Platform devices support"
576 Select to interpret AMD specific ACPI device to platform device
577 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
578 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
579 implemented under PINCTRL subsystem.
582 tristate "Intel SoC IOSF Sideband support for SoC platforms"
585 This option enables sideband register access support for Intel SoC
586 platforms. On these platforms the IOSF sideband is used in lieu of
587 MSR's for some register accesses, mostly but not limited to thermal
588 and power. Drivers may query the availability of this device to
589 determine if they need the sideband in order to work on these
590 platforms. The sideband is available on the following SoC products.
591 This list is not meant to be exclusive.
596 You should say Y if you are running a kernel on one of these SoC's.
598 config IOSF_MBI_DEBUG
599 bool "Enable IOSF sideband access through debugfs"
600 depends on IOSF_MBI && DEBUG_FS
602 Select this option to expose the IOSF sideband access registers (MCR,
603 MDR, MCRX) through debugfs to write and read register information from
604 different units on the SoC. This is most useful for obtaining device
605 state information for debug and analysis. As this is a general access
606 mechanism, users of this option would have specific knowledge of the
607 device they want to access.
609 If you don't require the option or are in doubt, say N.
612 bool "RDC R-321x SoC"
614 depends on X86_EXTENDED_PLATFORM
616 select X86_REBOOTFIXUPS
618 This option is needed for RDC R-321x system-on-chip, also known
620 If you don't have one of these chips, you should say N here.
622 config X86_32_NON_STANDARD
623 bool "Support non-standard 32-bit SMP architectures"
624 depends on X86_32 && SMP
625 depends on X86_EXTENDED_PLATFORM
627 This option compiles in the bigsmp and STA2X11 default
628 subarchitectures. It is intended for a generic binary
629 kernel. If you select them all, kernel will probe it one by
630 one and will fallback to default.
632 # Alphabetically sorted list of Non standard 32 bit platforms
634 config X86_SUPPORTS_MEMORY_FAILURE
636 # MCE code calls memory_failure():
638 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
639 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
640 depends on X86_64 || !SPARSEMEM
641 select ARCH_SUPPORTS_MEMORY_FAILURE
644 bool "STA2X11 Companion Chip Support"
645 depends on X86_32_NON_STANDARD && PCI
646 select X86_DEV_DMA_OPS
653 This adds support for boards based on the STA2X11 IO-Hub,
654 a.k.a. "ConneXt". The chip is used in place of the standard
655 PC chipset, so all "standard" peripherals are missing. If this
656 option is selected the kernel will still be able to boot on
657 standard PC machines.
660 tristate "Eurobraille/Iris poweroff module"
663 The Iris machines from EuroBraille do not have APM or ACPI support
664 to shut themselves down properly. A special I/O sequence is
665 needed to do so, which is what this module does at
668 This is only for Iris machines from EuroBraille.
672 config SCHED_OMIT_FRAME_POINTER
674 prompt "Single-depth WCHAN output"
677 Calculate simpler /proc/<PID>/wchan values. If this option
678 is disabled then wchan values will recurse back to the
679 caller function. This provides more accurate wchan values,
680 at the expense of slightly more scheduling overhead.
682 If in doubt, say "Y".
684 menuconfig HYPERVISOR_GUEST
685 bool "Linux guest support"
687 Say Y here to enable options for running Linux under various hyper-
688 visors. This option enables basic hypervisor detection and platform
691 If you say N, all options in this submenu will be skipped and
692 disabled, and Linux guest support won't be built in.
697 bool "Enable paravirtualization code"
699 This changes the kernel so it can modify itself when it is run
700 under a hypervisor, potentially improving performance significantly
701 over full virtualization. However, when run without a hypervisor
702 the kernel is theoretically slower and slightly larger.
704 config PARAVIRT_DEBUG
705 bool "paravirt-ops debugging"
706 depends on PARAVIRT && DEBUG_KERNEL
708 Enable to debug paravirt_ops internals. Specifically, BUG if
709 a paravirt_op is missing when it is called.
711 config PARAVIRT_SPINLOCKS
712 bool "Paravirtualization layer for spinlocks"
713 depends on PARAVIRT && SMP
715 Paravirtualized spinlocks allow a pvops backend to replace the
716 spinlock implementation with something virtualization-friendly
717 (for example, block the virtual CPU rather than spinning).
719 It has a minimal impact on native kernels and gives a nice performance
720 benefit on paravirtualized KVM / Xen kernels.
722 If you are unsure how to answer this question, answer Y.
724 config QUEUED_LOCK_STAT
725 bool "Paravirt queued spinlock statistics"
726 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
728 Enable the collection of statistical data on the slowpath
729 behavior of paravirtualized queued spinlocks and report
732 source "arch/x86/xen/Kconfig"
735 bool "KVM Guest support (including kvmclock)"
737 select PARAVIRT_CLOCK
740 This option enables various optimizations for running under the KVM
741 hypervisor. It includes a paravirtualized clock, so that instead
742 of relying on a PIT (or probably other) emulation by the
743 underlying device model, the host provides the guest with
744 timing infrastructure such as time of day, and system time
747 bool "Enable debug information for KVM Guests in debugfs"
748 depends on KVM_GUEST && DEBUG_FS
751 This option enables collection of various statistics for KVM guest.
752 Statistics are displayed in debugfs filesystem. Enabling this option
753 may incur significant overhead.
755 source "arch/x86/lguest/Kconfig"
757 config PARAVIRT_TIME_ACCOUNTING
758 bool "Paravirtual steal time accounting"
762 Select this option to enable fine granularity task steal time
763 accounting. Time spent executing other tasks in parallel with
764 the current vCPU is discounted from the vCPU power. To account for
765 that, there can be a small performance impact.
767 If in doubt, say N here.
769 config PARAVIRT_CLOCK
772 endif #HYPERVISOR_GUEST
777 source "arch/x86/Kconfig.cpu"
781 prompt "HPET Timer Support" if X86_32
783 Use the IA-PC HPET (High Precision Event Timer) to manage
784 time in preference to the PIT and RTC, if a HPET is
786 HPET is the next generation timer replacing legacy 8254s.
787 The HPET provides a stable time base on SMP
788 systems, unlike the TSC, but it is more expensive to access,
789 as it is off-chip. The interface used is documented
790 in the HPET spec, revision 1.
792 You can safely choose Y here. However, HPET will only be
793 activated if the platform and the BIOS support this feature.
794 Otherwise the 8254 will be used for timing services.
796 Choose N to continue using the legacy 8254 timer.
798 config HPET_EMULATE_RTC
800 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
803 def_bool y if X86_INTEL_MID
804 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
806 depends on X86_INTEL_MID && SFI
808 APB timer is the replacement for 8254, HPET on X86 MID platforms.
809 The APBT provides a stable time base on SMP
810 systems, unlike the TSC, but it is more expensive to access,
811 as it is off-chip. APB timers are always running regardless of CPU
812 C states, they are used as per CPU clockevent device when possible.
814 # Mark as expert because too many people got it wrong.
815 # The code disables itself when not needed.
818 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
819 bool "Enable DMI scanning" if EXPERT
821 Enabled scanning of DMI to identify machine quirks. Say Y
822 here unless you have verified that your setup is not
823 affected by entries in the DMI blacklist. Required by PNP
827 bool "Old AMD GART IOMMU support"
829 depends on X86_64 && PCI && AMD_NB
831 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
832 GART based hardware IOMMUs.
834 The GART supports full DMA access for devices with 32-bit access
835 limitations, on systems with more than 3 GB. This is usually needed
836 for USB, sound, many IDE/SATA chipsets and some other devices.
838 Newer systems typically have a modern AMD IOMMU, supported via
839 the CONFIG_AMD_IOMMU=y config option.
841 In normal configurations this driver is only active when needed:
842 there's more than 3 GB of memory and the system contains a
843 32-bit limited device.
848 bool "IBM Calgary IOMMU support"
850 depends on X86_64 && PCI
852 Support for hardware IOMMUs in IBM's xSeries x366 and x460
853 systems. Needed to run systems with more than 3GB of memory
854 properly with 32-bit PCI devices that do not support DAC
855 (Double Address Cycle). Calgary also supports bus level
856 isolation, where all DMAs pass through the IOMMU. This
857 prevents them from going anywhere except their intended
858 destination. This catches hard-to-find kernel bugs and
859 mis-behaving drivers and devices that do not use the DMA-API
860 properly to set up their DMA buffers. The IOMMU can be
861 turned off at boot time with the iommu=off parameter.
862 Normally the kernel will make the right choice by itself.
865 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
867 prompt "Should Calgary be enabled by default?"
868 depends on CALGARY_IOMMU
870 Should Calgary be enabled by default? if you choose 'y', Calgary
871 will be used (if it exists). If you choose 'n', Calgary will not be
872 used even if it exists. If you choose 'n' and would like to use
873 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
876 # need this always selected by IOMMU for the VIA workaround
880 Support for software bounce buffers used on x86-64 systems
881 which don't have a hardware IOMMU. Using this PCI devices
882 which can only access 32-bits of memory can be used on systems
883 with more than 3 GB of memory.
888 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
891 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
892 depends on X86_64 && SMP && DEBUG_KERNEL
893 select CPUMASK_OFFSTACK
895 Enable maximum number of CPUS and NUMA Nodes for this architecture.
899 int "Maximum number of CPUs" if SMP && !MAXSMP
900 range 2 8 if SMP && X86_32 && !X86_BIGSMP
901 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
902 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
904 default "8192" if MAXSMP
905 default "32" if SMP && X86_BIGSMP
906 default "8" if SMP && X86_32
909 This allows you to specify the maximum number of CPUs which this
910 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
911 supported value is 8192, otherwise the maximum value is 512. The
912 minimum value which makes sense is 2.
914 This is purely to save memory - each supported CPU adds
915 approximately eight kilobytes to the kernel image.
918 bool "SMT (Hyperthreading) scheduler support"
921 SMT scheduler support improves the CPU scheduler's decision making
922 when dealing with Intel Pentium 4 chips with HyperThreading at a
923 cost of slightly increased overhead in some places. If unsure say
928 prompt "Multi-core scheduler support"
931 Multi-core scheduler support improves the CPU scheduler's decision
932 making when dealing with multi-core CPU chips at a cost of slightly
933 increased overhead in some places. If unsure say N here.
936 bool "CPU core priorities scheduler support"
937 depends on SCHED_MC && CPU_SUP_INTEL
938 select X86_INTEL_PSTATE
942 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
943 core ordering determined at manufacturing time, which allows
944 certain cores to reach higher turbo frequencies (when running
945 single threaded workloads) than others.
947 Enabling this kernel feature teaches the scheduler about
948 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
949 scheduler's CPU selection logic accordingly, so that higher
950 overall system performance can be achieved.
952 This feature will have no effect on CPUs without this feature.
954 If unsure say Y here.
956 source "kernel/Kconfig.preempt"
960 depends on !SMP && X86_LOCAL_APIC
963 bool "Local APIC support on uniprocessors" if !PCI_MSI
965 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
967 A local APIC (Advanced Programmable Interrupt Controller) is an
968 integrated interrupt controller in the CPU. If you have a single-CPU
969 system which has a processor with a local APIC, you can say Y here to
970 enable and use it. If you say Y here even though your machine doesn't
971 have a local APIC, then the kernel will still run with no slowdown at
972 all. The local APIC supports CPU-generated self-interrupts (timer,
973 performance counters), and the NMI watchdog which detects hard
977 bool "IO-APIC support on uniprocessors"
978 depends on X86_UP_APIC
980 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
981 SMP-capable replacement for PC-style interrupt controllers. Most
982 SMP systems and many recent uniprocessor systems have one.
984 If you have a single-CPU system with an IO-APIC, you can say Y here
985 to use it. If you say Y here even though your machine doesn't have
986 an IO-APIC, then the kernel will still run with no slowdown at all.
988 config X86_LOCAL_APIC
990 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
991 select IRQ_DOMAIN_HIERARCHY
992 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
996 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
998 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
999 bool "Reroute for broken boot IRQs"
1000 depends on X86_IO_APIC
1002 This option enables a workaround that fixes a source of
1003 spurious interrupts. This is recommended when threaded
1004 interrupt handling is used on systems where the generation of
1005 superfluous "boot interrupts" cannot be disabled.
1007 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1008 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1009 kernel does during interrupt handling). On chipsets where this
1010 boot IRQ generation cannot be disabled, this workaround keeps
1011 the original IRQ line masked so that only the equivalent "boot
1012 IRQ" is delivered to the CPUs. The workaround also tells the
1013 kernel to set up the IRQ handler on the boot IRQ line. In this
1014 way only one interrupt is delivered to the kernel. Otherwise
1015 the spurious second interrupt may cause the kernel to bring
1016 down (vital) interrupt lines.
1018 Only affects "broken" chipsets. Interrupt sharing may be
1019 increased on these systems.
1022 bool "Machine Check / overheating reporting"
1023 select GENERIC_ALLOCATOR
1026 Machine Check support allows the processor to notify the
1027 kernel if it detects a problem (e.g. overheating, data corruption).
1028 The action the kernel takes depends on the severity of the problem,
1029 ranging from warning messages to halting the machine.
1031 config X86_MCE_INTEL
1033 prompt "Intel MCE features"
1034 depends on X86_MCE && X86_LOCAL_APIC
1036 Additional support for intel specific MCE features such as
1037 the thermal monitor.
1041 prompt "AMD MCE features"
1042 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1044 Additional support for AMD specific MCE features such as
1045 the DRAM Error Threshold.
1047 config X86_ANCIENT_MCE
1048 bool "Support for old Pentium 5 / WinChip machine checks"
1049 depends on X86_32 && X86_MCE
1051 Include support for machine check handling on old Pentium 5 or WinChip
1052 systems. These typically need to be enabled explicitly on the command
1055 config X86_MCE_THRESHOLD
1056 depends on X86_MCE_AMD || X86_MCE_INTEL
1059 config X86_MCE_INJECT
1061 tristate "Machine check injector support"
1063 Provide support for injecting machine checks for testing purposes.
1064 If you don't know what a machine check is and you don't do kernel
1065 QA it is safe to say n.
1067 config X86_THERMAL_VECTOR
1069 depends on X86_MCE_INTEL
1071 source "arch/x86/events/Kconfig"
1073 config X86_LEGACY_VM86
1074 bool "Legacy VM86 support"
1078 This option allows user programs to put the CPU into V8086
1079 mode, which is an 80286-era approximation of 16-bit real mode.
1081 Some very old versions of X and/or vbetool require this option
1082 for user mode setting. Similarly, DOSEMU will use it if
1083 available to accelerate real mode DOS programs. However, any
1084 recent version of DOSEMU, X, or vbetool should be fully
1085 functional even without kernel VM86 support, as they will all
1086 fall back to software emulation. Nevertheless, if you are using
1087 a 16-bit DOS program where 16-bit performance matters, vm86
1088 mode might be faster than emulation and you might want to
1091 Note that any app that works on a 64-bit kernel is unlikely to
1092 need this option, as 64-bit kernels don't, and can't, support
1093 V8086 mode. This option is also unrelated to 16-bit protected
1094 mode and is not needed to run most 16-bit programs under Wine.
1096 Enabling this option increases the complexity of the kernel
1097 and slows down exception handling a tiny bit.
1099 If unsure, say N here.
1103 default X86_LEGACY_VM86
1106 bool "Enable support for 16-bit segments" if EXPERT
1108 depends on MODIFY_LDT_SYSCALL
1110 This option is required by programs like Wine to run 16-bit
1111 protected mode legacy code on x86 processors. Disabling
1112 this option saves about 300 bytes on i386, or around 6K text
1113 plus 16K runtime memory on x86-64,
1117 depends on X86_16BIT && X86_32
1121 depends on X86_16BIT && X86_64
1123 config X86_VSYSCALL_EMULATION
1124 bool "Enable vsyscall emulation" if EXPERT
1128 This enables emulation of the legacy vsyscall page. Disabling
1129 it is roughly equivalent to booting with vsyscall=none, except
1130 that it will also disable the helpful warning if a program
1131 tries to use a vsyscall. With this option set to N, offending
1132 programs will just segfault, citing addresses of the form
1135 This option is required by many programs built before 2013, and
1136 care should be used even with newer programs if set to N.
1138 Disabling this option saves about 7K of kernel size and
1139 possibly 4K of additional runtime pagetable memory.
1142 tristate "Toshiba Laptop support"
1145 This adds a driver to safely access the System Management Mode of
1146 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1147 not work on models with a Phoenix BIOS. The System Management Mode
1148 is used to set the BIOS and power saving options on Toshiba portables.
1150 For information on utilities to make use of this driver see the
1151 Toshiba Linux utilities web site at:
1152 <http://www.buzzard.org.uk/toshiba/>.
1154 Say Y if you intend to run this kernel on a Toshiba portable.
1158 tristate "Dell i8k legacy laptop support"
1160 select SENSORS_DELL_SMM
1162 This option enables legacy /proc/i8k userspace interface in hwmon
1163 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1164 temperature and allows controlling fan speeds of Dell laptops via
1165 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1166 it reports also power and hotkey status. For fan speed control is
1167 needed userspace package i8kutils.
1169 Say Y if you intend to run this kernel on old Dell laptops or want to
1170 use userspace package i8kutils.
1173 config X86_REBOOTFIXUPS
1174 bool "Enable X86 board specific fixups for reboot"
1177 This enables chipset and/or board specific fixups to be done
1178 in order to get reboot to work correctly. This is only needed on
1179 some combinations of hardware and BIOS. The symptom, for which
1180 this config is intended, is when reboot ends with a stalled/hung
1183 Currently, the only fixup is for the Geode machines using
1184 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1186 Say Y if you want to enable the fixup. Currently, it's safe to
1187 enable this option even if you don't need it.
1191 bool "CPU microcode loading support"
1193 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1196 If you say Y here, you will be able to update the microcode on
1197 Intel and AMD processors. The Intel support is for the IA32 family,
1198 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1199 AMD support is for families 0x10 and later. You will obviously need
1200 the actual microcode binary data itself which is not shipped with
1203 The preferred method to load microcode from a detached initrd is described
1204 in Documentation/x86/early-microcode.txt. For that you need to enable
1205 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1206 initrd for microcode blobs.
1208 In addition, you can build-in the microcode into the kernel. For that you
1209 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1210 to the CONFIG_EXTRA_FIRMWARE config option.
1212 config MICROCODE_INTEL
1213 bool "Intel microcode loading support"
1214 depends on MICROCODE
1218 This options enables microcode patch loading support for Intel
1221 For the current Intel microcode data package go to
1222 <https://downloadcenter.intel.com> and search for
1223 'Linux Processor Microcode Data File'.
1225 config MICROCODE_AMD
1226 bool "AMD microcode loading support"
1227 depends on MICROCODE
1230 If you select this option, microcode patch loading support for AMD
1231 processors will be enabled.
1233 config MICROCODE_OLD_INTERFACE
1235 depends on MICROCODE
1238 tristate "/dev/cpu/*/msr - Model-specific register support"
1240 This device gives privileged processes access to the x86
1241 Model-Specific Registers (MSRs). It is a character device with
1242 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1243 MSR accesses are directed to a specific CPU on multi-processor
1247 tristate "/dev/cpu/*/cpuid - CPU information support"
1249 This device gives processes access to the x86 CPUID instruction to
1250 be executed on a specific processor. It is a character device
1251 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1255 prompt "High Memory Support"
1262 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1263 However, the address space of 32-bit x86 processors is only 4
1264 Gigabytes large. That means that, if you have a large amount of
1265 physical memory, not all of it can be "permanently mapped" by the
1266 kernel. The physical memory that's not permanently mapped is called
1269 If you are compiling a kernel which will never run on a machine with
1270 more than 1 Gigabyte total physical RAM, answer "off" here (default
1271 choice and suitable for most users). This will result in a "3GB/1GB"
1272 split: 3GB are mapped so that each process sees a 3GB virtual memory
1273 space and the remaining part of the 4GB virtual memory space is used
1274 by the kernel to permanently map as much physical memory as
1277 If the machine has between 1 and 4 Gigabytes physical RAM, then
1280 If more than 4 Gigabytes is used then answer "64GB" here. This
1281 selection turns Intel PAE (Physical Address Extension) mode on.
1282 PAE implements 3-level paging on IA32 processors. PAE is fully
1283 supported by Linux, PAE mode is implemented on all recent Intel
1284 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1285 then the kernel will not boot on CPUs that don't support PAE!
1287 The actual amount of total physical memory will either be
1288 auto detected or can be forced by using a kernel command line option
1289 such as "mem=256M". (Try "man bootparam" or see the documentation of
1290 your boot loader (lilo or loadlin) about how to pass options to the
1291 kernel at boot time.)
1293 If unsure, say "off".
1298 Select this if you have a 32-bit processor and between 1 and 4
1299 gigabytes of physical RAM.
1306 Select this if you have a 32-bit processor and more than 4
1307 gigabytes of physical RAM.
1312 prompt "Memory split" if EXPERT
1316 Select the desired split between kernel and user memory.
1318 If the address range available to the kernel is less than the
1319 physical memory installed, the remaining memory will be available
1320 as "high memory". Accessing high memory is a little more costly
1321 than low memory, as it needs to be mapped into the kernel first.
1322 Note that increasing the kernel address space limits the range
1323 available to user programs, making the address space there
1324 tighter. Selecting anything other than the default 3G/1G split
1325 will also likely make your kernel incompatible with binary-only
1328 If you are not absolutely sure what you are doing, leave this
1332 bool "3G/1G user/kernel split"
1333 config VMSPLIT_3G_OPT
1335 bool "3G/1G user/kernel split (for full 1G low memory)"
1337 bool "2G/2G user/kernel split"
1338 config VMSPLIT_2G_OPT
1340 bool "2G/2G user/kernel split (for full 2G low memory)"
1342 bool "1G/3G user/kernel split"
1347 default 0xB0000000 if VMSPLIT_3G_OPT
1348 default 0x80000000 if VMSPLIT_2G
1349 default 0x78000000 if VMSPLIT_2G_OPT
1350 default 0x40000000 if VMSPLIT_1G
1356 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1359 bool "PAE (Physical Address Extension) Support"
1360 depends on X86_32 && !HIGHMEM4G
1363 PAE is required for NX support, and furthermore enables
1364 larger swapspace support for non-overcommit purposes. It
1365 has the cost of more pagetable lookup overhead, and also
1366 consumes more pagetable space per process.
1368 config ARCH_PHYS_ADDR_T_64BIT
1370 depends on X86_64 || X86_PAE
1372 config ARCH_DMA_ADDR_T_64BIT
1374 depends on X86_64 || HIGHMEM64G
1376 config X86_DIRECT_GBPAGES
1378 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1380 Certain kernel features effectively disable kernel
1381 linear 1 GB mappings (even if the CPU otherwise
1382 supports them), so don't confuse the user by printing
1383 that we have them enabled.
1385 # Common NUMA Features
1387 bool "Numa Memory Allocation and Scheduler Support"
1389 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1390 default y if X86_BIGSMP
1392 Enable NUMA (Non Uniform Memory Access) support.
1394 The kernel will try to allocate memory used by a CPU on the
1395 local memory controller of the CPU and add some more
1396 NUMA awareness to the kernel.
1398 For 64-bit this is recommended if the system is Intel Core i7
1399 (or later), AMD Opteron, or EM64T NUMA.
1401 For 32-bit this is only needed if you boot a 32-bit
1402 kernel on a 64-bit NUMA platform.
1404 Otherwise, you should say N.
1408 prompt "Old style AMD Opteron NUMA detection"
1409 depends on X86_64 && NUMA && PCI
1411 Enable AMD NUMA node topology detection. You should say Y here if
1412 you have a multi processor AMD system. This uses an old method to
1413 read the NUMA configuration directly from the builtin Northbridge
1414 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1415 which also takes priority if both are compiled in.
1417 config X86_64_ACPI_NUMA
1419 prompt "ACPI NUMA detection"
1420 depends on X86_64 && NUMA && ACPI && PCI
1423 Enable ACPI SRAT based node topology detection.
1425 # Some NUMA nodes have memory ranges that span
1426 # other nodes. Even though a pfn is valid and
1427 # between a node's start and end pfns, it may not
1428 # reside on that node. See memmap_init_zone()
1430 config NODES_SPAN_OTHER_NODES
1432 depends on X86_64_ACPI_NUMA
1435 bool "NUMA emulation"
1438 Enable NUMA emulation. A flat machine will be split
1439 into virtual nodes when booted with "numa=fake=N", where N is the
1440 number of nodes. This is only useful for debugging.
1443 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1445 default "10" if MAXSMP
1446 default "6" if X86_64
1448 depends on NEED_MULTIPLE_NODES
1450 Specify the maximum number of NUMA Nodes available on the target
1451 system. Increases memory reserved to accommodate various tables.
1453 config ARCH_HAVE_MEMORY_PRESENT
1455 depends on X86_32 && DISCONTIGMEM
1457 config NEED_NODE_MEMMAP_SIZE
1459 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1461 config ARCH_FLATMEM_ENABLE
1463 depends on X86_32 && !NUMA
1465 config ARCH_DISCONTIGMEM_ENABLE
1467 depends on NUMA && X86_32
1469 config ARCH_DISCONTIGMEM_DEFAULT
1471 depends on NUMA && X86_32
1473 config ARCH_SPARSEMEM_ENABLE
1475 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1476 select SPARSEMEM_STATIC if X86_32
1477 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1479 config ARCH_SPARSEMEM_DEFAULT
1483 config ARCH_SELECT_MEMORY_MODEL
1485 depends on ARCH_SPARSEMEM_ENABLE
1487 config ARCH_MEMORY_PROBE
1488 bool "Enable sysfs memory/probe interface"
1489 depends on X86_64 && MEMORY_HOTPLUG
1491 This option enables a sysfs memory/probe interface for testing.
1492 See Documentation/memory-hotplug.txt for more information.
1493 If you are unsure how to answer this question, answer N.
1495 config ARCH_PROC_KCORE_TEXT
1497 depends on X86_64 && PROC_KCORE
1499 config ILLEGAL_POINTER_VALUE
1502 default 0xdead000000000000 if X86_64
1506 config X86_PMEM_LEGACY_DEVICE
1509 config X86_PMEM_LEGACY
1510 tristate "Support non-standard NVDIMMs and ADR protected memory"
1511 depends on PHYS_ADDR_T_64BIT
1513 select X86_PMEM_LEGACY_DEVICE
1516 Treat memory marked using the non-standard e820 type of 12 as used
1517 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1518 The kernel will offer these regions to the 'pmem' driver so
1519 they can be used for persistent storage.
1524 bool "Allocate 3rd-level pagetables from highmem"
1527 The VM uses one page table entry for each page of physical memory.
1528 For systems with a lot of RAM, this can be wasteful of precious
1529 low memory. Setting this option will put user-space page table
1530 entries in high memory.
1532 config X86_CHECK_BIOS_CORRUPTION
1533 bool "Check for low memory corruption"
1535 Periodically check for memory corruption in low memory, which
1536 is suspected to be caused by BIOS. Even when enabled in the
1537 configuration, it is disabled at runtime. Enable it by
1538 setting "memory_corruption_check=1" on the kernel command
1539 line. By default it scans the low 64k of memory every 60
1540 seconds; see the memory_corruption_check_size and
1541 memory_corruption_check_period parameters in
1542 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1544 When enabled with the default parameters, this option has
1545 almost no overhead, as it reserves a relatively small amount
1546 of memory and scans it infrequently. It both detects corruption
1547 and prevents it from affecting the running system.
1549 It is, however, intended as a diagnostic tool; if repeatable
1550 BIOS-originated corruption always affects the same memory,
1551 you can use memmap= to prevent the kernel from using that
1554 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1555 bool "Set the default setting of memory_corruption_check"
1556 depends on X86_CHECK_BIOS_CORRUPTION
1559 Set whether the default state of memory_corruption_check is
1562 config X86_RESERVE_LOW
1563 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1567 Specify the amount of low memory to reserve for the BIOS.
1569 The first page contains BIOS data structures that the kernel
1570 must not use, so that page must always be reserved.
1572 By default we reserve the first 64K of physical RAM, as a
1573 number of BIOSes are known to corrupt that memory range
1574 during events such as suspend/resume or monitor cable
1575 insertion, so it must not be used by the kernel.
1577 You can set this to 4 if you are absolutely sure that you
1578 trust the BIOS to get all its memory reservations and usages
1579 right. If you know your BIOS have problems beyond the
1580 default 64K area, you can set this to 640 to avoid using the
1581 entire low memory range.
1583 If you have doubts about the BIOS (e.g. suspend/resume does
1584 not work or there's kernel crashes after certain hardware
1585 hotplug events) then you might want to enable
1586 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1587 typical corruption patterns.
1589 Leave this to the default value of 64 if you are unsure.
1591 config MATH_EMULATION
1593 depends on MODIFY_LDT_SYSCALL
1594 prompt "Math emulation" if X86_32
1596 Linux can emulate a math coprocessor (used for floating point
1597 operations) if you don't have one. 486DX and Pentium processors have
1598 a math coprocessor built in, 486SX and 386 do not, unless you added
1599 a 487DX or 387, respectively. (The messages during boot time can
1600 give you some hints here ["man dmesg"].) Everyone needs either a
1601 coprocessor or this emulation.
1603 If you don't have a math coprocessor, you need to say Y here; if you
1604 say Y here even though you have a coprocessor, the coprocessor will
1605 be used nevertheless. (This behavior can be changed with the kernel
1606 command line option "no387", which comes handy if your coprocessor
1607 is broken. Try "man bootparam" or see the documentation of your boot
1608 loader (lilo or loadlin) about how to pass options to the kernel at
1609 boot time.) This means that it is a good idea to say Y here if you
1610 intend to use this kernel on different machines.
1612 More information about the internals of the Linux math coprocessor
1613 emulation can be found in <file:arch/x86/math-emu/README>.
1615 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1616 kernel, it won't hurt.
1620 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1622 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1623 the Memory Type Range Registers (MTRRs) may be used to control
1624 processor access to memory ranges. This is most useful if you have
1625 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1626 allows bus write transfers to be combined into a larger transfer
1627 before bursting over the PCI/AGP bus. This can increase performance
1628 of image write operations 2.5 times or more. Saying Y here creates a
1629 /proc/mtrr file which may be used to manipulate your processor's
1630 MTRRs. Typically the X server should use this.
1632 This code has a reasonably generic interface so that similar
1633 control registers on other processors can be easily supported
1636 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1637 Registers (ARRs) which provide a similar functionality to MTRRs. For
1638 these, the ARRs are used to emulate the MTRRs.
1639 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1640 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1641 write-combining. All of these processors are supported by this code
1642 and it makes sense to say Y here if you have one of them.
1644 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1645 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1646 can lead to all sorts of problems, so it's good to say Y here.
1648 You can safely say Y even if your machine doesn't have MTRRs, you'll
1649 just add about 9 KB to your kernel.
1651 See <file:Documentation/x86/mtrr.txt> for more information.
1653 config MTRR_SANITIZER
1655 prompt "MTRR cleanup support"
1658 Convert MTRR layout from continuous to discrete, so X drivers can
1659 add writeback entries.
1661 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1662 The largest mtrr entry size for a continuous block can be set with
1667 config MTRR_SANITIZER_ENABLE_DEFAULT
1668 int "MTRR cleanup enable value (0-1)"
1671 depends on MTRR_SANITIZER
1673 Enable mtrr cleanup default value
1675 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1676 int "MTRR cleanup spare reg num (0-7)"
1679 depends on MTRR_SANITIZER
1681 mtrr cleanup spare entries default, it can be changed via
1682 mtrr_spare_reg_nr=N on the kernel command line.
1686 prompt "x86 PAT support" if EXPERT
1689 Use PAT attributes to setup page level cache control.
1691 PATs are the modern equivalents of MTRRs and are much more
1692 flexible than MTRRs.
1694 Say N here if you see bootup problems (boot crash, boot hang,
1695 spontaneous reboots) or a non-working video driver.
1699 config ARCH_USES_PG_UNCACHED
1705 prompt "x86 architectural random number generator" if EXPERT
1707 Enable the x86 architectural RDRAND instruction
1708 (Intel Bull Mountain technology) to generate random numbers.
1709 If supported, this is a high bandwidth, cryptographically
1710 secure hardware random number generator.
1714 prompt "Supervisor Mode Access Prevention" if EXPERT
1716 Supervisor Mode Access Prevention (SMAP) is a security
1717 feature in newer Intel processors. There is a small
1718 performance cost if this enabled and turned on; there is
1719 also a small increase in the kernel size if this is enabled.
1723 config X86_INTEL_MPX
1724 prompt "Intel MPX (Memory Protection Extensions)"
1726 depends on CPU_SUP_INTEL
1728 MPX provides hardware features that can be used in
1729 conjunction with compiler-instrumented code to check
1730 memory references. It is designed to detect buffer
1731 overflow or underflow bugs.
1733 This option enables running applications which are
1734 instrumented or otherwise use MPX. It does not use MPX
1735 itself inside the kernel or to protect the kernel
1736 against bad memory references.
1738 Enabling this option will make the kernel larger:
1739 ~8k of kernel text and 36 bytes of data on a 64-bit
1740 defconfig. It adds a long to the 'mm_struct' which
1741 will increase the kernel memory overhead of each
1742 process and adds some branches to paths used during
1743 exec() and munmap().
1745 For details, see Documentation/x86/intel_mpx.txt
1749 config X86_INTEL_MEMORY_PROTECTION_KEYS
1750 prompt "Intel Memory Protection Keys"
1752 # Note: only available in 64-bit mode
1753 depends on CPU_SUP_INTEL && X86_64
1754 select ARCH_USES_HIGH_VMA_FLAGS
1755 select ARCH_HAS_PKEYS
1757 Memory Protection Keys provides a mechanism for enforcing
1758 page-based protections, but without requiring modification of the
1759 page tables when an application changes protection domains.
1761 For details, see Documentation/x86/protection-keys.txt
1766 bool "EFI runtime service support"
1769 select EFI_RUNTIME_WRAPPERS
1771 This enables the kernel to use EFI runtime services that are
1772 available (such as the EFI variable services).
1774 This option is only useful on systems that have EFI firmware.
1775 In addition, you should use the latest ELILO loader available
1776 at <http://elilo.sourceforge.net> in order to take advantage
1777 of EFI runtime services. However, even with this option, the
1778 resultant kernel should continue to boot on existing non-EFI
1782 bool "EFI stub support"
1783 depends on EFI && !X86_USE_3DNOW
1786 This kernel feature allows a bzImage to be loaded directly
1787 by EFI firmware without the use of a bootloader.
1789 See Documentation/efi-stub.txt for more information.
1792 bool "EFI mixed-mode support"
1793 depends on EFI_STUB && X86_64
1795 Enabling this feature allows a 64-bit kernel to be booted
1796 on a 32-bit firmware, provided that your CPU supports 64-bit
1799 Note that it is not possible to boot a mixed-mode enabled
1800 kernel via the EFI boot stub - a bootloader that supports
1801 the EFI handover protocol must be used.
1807 prompt "Enable seccomp to safely compute untrusted bytecode"
1809 This kernel feature is useful for number crunching applications
1810 that may need to compute untrusted bytecode during their
1811 execution. By using pipes or other transports made available to
1812 the process as file descriptors supporting the read/write
1813 syscalls, it's possible to isolate those applications in
1814 their own address space using seccomp. Once seccomp is
1815 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1816 and the task is only allowed to execute a few safe syscalls
1817 defined by each seccomp mode.
1819 If unsure, say Y. Only embedded should say N here.
1821 source kernel/Kconfig.hz
1824 bool "kexec system call"
1827 kexec is a system call that implements the ability to shutdown your
1828 current kernel, and to start another kernel. It is like a reboot
1829 but it is independent of the system firmware. And like a reboot
1830 you can start any kernel with it, not just Linux.
1832 The name comes from the similarity to the exec system call.
1834 It is an ongoing process to be certain the hardware in a machine
1835 is properly shutdown, so do not be surprised if this code does not
1836 initially work for you. As of this writing the exact hardware
1837 interface is strongly in flux, so no good recommendation can be
1841 bool "kexec file based system call"
1846 depends on CRYPTO_SHA256=y
1848 This is new version of kexec system call. This system call is
1849 file based and takes file descriptors as system call argument
1850 for kernel and initramfs as opposed to list of segments as
1851 accepted by previous system call.
1853 config KEXEC_VERIFY_SIG
1854 bool "Verify kernel signature during kexec_file_load() syscall"
1855 depends on KEXEC_FILE
1857 This option makes kernel signature verification mandatory for
1858 the kexec_file_load() syscall.
1860 In addition to that option, you need to enable signature
1861 verification for the corresponding kernel image type being
1862 loaded in order for this to work.
1864 config KEXEC_BZIMAGE_VERIFY_SIG
1865 bool "Enable bzImage signature verification support"
1866 depends on KEXEC_VERIFY_SIG
1867 depends on SIGNED_PE_FILE_VERIFICATION
1868 select SYSTEM_TRUSTED_KEYRING
1870 Enable bzImage signature verification support.
1873 bool "kernel crash dumps"
1874 depends on X86_64 || (X86_32 && HIGHMEM)
1876 Generate crash dump after being started by kexec.
1877 This should be normally only set in special crash dump kernels
1878 which are loaded in the main kernel with kexec-tools into
1879 a specially reserved region and then later executed after
1880 a crash by kdump/kexec. The crash dump kernel must be compiled
1881 to a memory address not used by the main kernel or BIOS using
1882 PHYSICAL_START, or it must be built as a relocatable image
1883 (CONFIG_RELOCATABLE=y).
1884 For more details see Documentation/kdump/kdump.txt
1888 depends on KEXEC && HIBERNATION
1890 Jump between original kernel and kexeced kernel and invoke
1891 code in physical address mode via KEXEC
1893 config PHYSICAL_START
1894 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1897 This gives the physical address where the kernel is loaded.
1899 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1900 bzImage will decompress itself to above physical address and
1901 run from there. Otherwise, bzImage will run from the address where
1902 it has been loaded by the boot loader and will ignore above physical
1905 In normal kdump cases one does not have to set/change this option
1906 as now bzImage can be compiled as a completely relocatable image
1907 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1908 address. This option is mainly useful for the folks who don't want
1909 to use a bzImage for capturing the crash dump and want to use a
1910 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1911 to be specifically compiled to run from a specific memory area
1912 (normally a reserved region) and this option comes handy.
1914 So if you are using bzImage for capturing the crash dump,
1915 leave the value here unchanged to 0x1000000 and set
1916 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1917 for capturing the crash dump change this value to start of
1918 the reserved region. In other words, it can be set based on
1919 the "X" value as specified in the "crashkernel=YM@XM"
1920 command line boot parameter passed to the panic-ed
1921 kernel. Please take a look at Documentation/kdump/kdump.txt
1922 for more details about crash dumps.
1924 Usage of bzImage for capturing the crash dump is recommended as
1925 one does not have to build two kernels. Same kernel can be used
1926 as production kernel and capture kernel. Above option should have
1927 gone away after relocatable bzImage support is introduced. But it
1928 is present because there are users out there who continue to use
1929 vmlinux for dump capture. This option should go away down the
1932 Don't change this unless you know what you are doing.
1935 bool "Build a relocatable kernel"
1938 This builds a kernel image that retains relocation information
1939 so it can be loaded someplace besides the default 1MB.
1940 The relocations tend to make the kernel binary about 10% larger,
1941 but are discarded at runtime.
1943 One use is for the kexec on panic case where the recovery kernel
1944 must live at a different physical address than the primary
1947 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1948 it has been loaded at and the compile time physical address
1949 (CONFIG_PHYSICAL_START) is used as the minimum location.
1951 config RANDOMIZE_BASE
1952 bool "Randomize the address of the kernel image (KASLR)"
1953 depends on RELOCATABLE
1956 In support of Kernel Address Space Layout Randomization (KASLR),
1957 this randomizes the physical address at which the kernel image
1958 is decompressed and the virtual address where the kernel
1959 image is mapped, as a security feature that deters exploit
1960 attempts relying on knowledge of the location of kernel
1963 On 64-bit, the kernel physical and virtual addresses are
1964 randomized separately. The physical address will be anywhere
1965 between 16MB and the top of physical memory (up to 64TB). The
1966 virtual address will be randomized from 16MB up to 1GB (9 bits
1967 of entropy). Note that this also reduces the memory space
1968 available to kernel modules from 1.5GB to 1GB.
1970 On 32-bit, the kernel physical and virtual addresses are
1971 randomized together. They will be randomized from 16MB up to
1972 512MB (8 bits of entropy).
1974 Entropy is generated using the RDRAND instruction if it is
1975 supported. If RDTSC is supported, its value is mixed into
1976 the entropy pool as well. If neither RDRAND nor RDTSC are
1977 supported, then entropy is read from the i8254 timer. The
1978 usable entropy is limited by the kernel being built using
1979 2GB addressing, and that PHYSICAL_ALIGN must be at a
1980 minimum of 2MB. As a result, only 10 bits of entropy are
1981 theoretically possible, but the implementations are further
1982 limited due to memory layouts.
1984 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1985 time. To enable it, boot with "kaslr" on the kernel command
1986 line (which will also disable hibernation).
1990 # Relocation on x86 needs some additional build support
1991 config X86_NEED_RELOCS
1993 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1995 config PHYSICAL_ALIGN
1996 hex "Alignment value to which kernel should be aligned"
1998 range 0x2000 0x1000000 if X86_32
1999 range 0x200000 0x1000000 if X86_64
2001 This value puts the alignment restrictions on physical address
2002 where kernel is loaded and run from. Kernel is compiled for an
2003 address which meets above alignment restriction.
2005 If bootloader loads the kernel at a non-aligned address and
2006 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2007 address aligned to above value and run from there.
2009 If bootloader loads the kernel at a non-aligned address and
2010 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2011 load address and decompress itself to the address it has been
2012 compiled for and run from there. The address for which kernel is
2013 compiled already meets above alignment restrictions. Hence the
2014 end result is that kernel runs from a physical address meeting
2015 above alignment restrictions.
2017 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2018 this value must be a multiple of 0x200000.
2020 Don't change this unless you know what you are doing.
2022 config RANDOMIZE_MEMORY
2023 bool "Randomize the kernel memory sections"
2025 depends on RANDOMIZE_BASE
2026 default RANDOMIZE_BASE
2028 Randomizes the base virtual address of kernel memory sections
2029 (physical memory mapping, vmalloc & vmemmap). This security feature
2030 makes exploits relying on predictable memory locations less reliable.
2032 The order of allocations remains unchanged. Entropy is generated in
2033 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2034 configuration have in average 30,000 different possible virtual
2035 addresses for each memory section.
2039 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2040 hex "Physical memory mapping padding" if EXPERT
2041 depends on RANDOMIZE_MEMORY
2042 default "0xa" if MEMORY_HOTPLUG
2044 range 0x1 0x40 if MEMORY_HOTPLUG
2047 Define the padding in terabytes added to the existing physical
2048 memory size during kernel memory randomization. It is useful
2049 for memory hotplug support but reduces the entropy available for
2050 address randomization.
2052 If unsure, leave at the default value.
2055 bool "Support for hot-pluggable CPUs"
2058 Say Y here to allow turning CPUs off and on. CPUs can be
2059 controlled through /sys/devices/system/cpu.
2060 ( Note: power management support will enable this option
2061 automatically on SMP systems. )
2062 Say N if you want to disable CPU hotplug.
2064 config BOOTPARAM_HOTPLUG_CPU0
2065 bool "Set default setting of cpu0_hotpluggable"
2067 depends on HOTPLUG_CPU
2069 Set whether default state of cpu0_hotpluggable is on or off.
2071 Say Y here to enable CPU0 hotplug by default. If this switch
2072 is turned on, there is no need to give cpu0_hotplug kernel
2073 parameter and the CPU0 hotplug feature is enabled by default.
2075 Please note: there are two known CPU0 dependencies if you want
2076 to enable the CPU0 hotplug feature either by this switch or by
2077 cpu0_hotplug kernel parameter.
2079 First, resume from hibernate or suspend always starts from CPU0.
2080 So hibernate and suspend are prevented if CPU0 is offline.
2082 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2083 offline if any interrupt can not migrate out of CPU0. There may
2084 be other CPU0 dependencies.
2086 Please make sure the dependencies are under your control before
2087 you enable this feature.
2089 Say N if you don't want to enable CPU0 hotplug feature by default.
2090 You still can enable the CPU0 hotplug feature at boot by kernel
2091 parameter cpu0_hotplug.
2093 config DEBUG_HOTPLUG_CPU0
2095 prompt "Debug CPU0 hotplug"
2096 depends on HOTPLUG_CPU
2098 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2099 soon as possible and boots up userspace with CPU0 offlined. User
2100 can online CPU0 back after boot time.
2102 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2103 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2104 compilation or giving cpu0_hotplug kernel parameter at boot.
2110 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2111 depends on COMPAT_32
2113 Certain buggy versions of glibc will crash if they are
2114 presented with a 32-bit vDSO that is not mapped at the address
2115 indicated in its segment table.
2117 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2118 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2119 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2120 the only released version with the bug, but OpenSUSE 9
2121 contains a buggy "glibc 2.3.2".
2123 The symptom of the bug is that everything crashes on startup, saying:
2124 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2126 Saying Y here changes the default value of the vdso32 boot
2127 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2128 This works around the glibc bug but hurts performance.
2130 If unsure, say N: if you are compiling your own kernel, you
2131 are unlikely to be using a buggy version of glibc.
2134 prompt "vsyscall table for legacy applications"
2136 default LEGACY_VSYSCALL_EMULATE
2138 Legacy user code that does not know how to find the vDSO expects
2139 to be able to issue three syscalls by calling fixed addresses in
2140 kernel space. Since this location is not randomized with ASLR,
2141 it can be used to assist security vulnerability exploitation.
2143 This setting can be changed at boot time via the kernel command
2144 line parameter vsyscall=[native|emulate|none].
2146 On a system with recent enough glibc (2.14 or newer) and no
2147 static binaries, you can say None without a performance penalty
2148 to improve security.
2150 If unsure, select "Emulate".
2152 config LEGACY_VSYSCALL_NATIVE
2155 Actual executable code is located in the fixed vsyscall
2156 address mapping, implementing time() efficiently. Since
2157 this makes the mapping executable, it can be used during
2158 security vulnerability exploitation (traditionally as
2159 ROP gadgets). This configuration is not recommended.
2161 config LEGACY_VSYSCALL_EMULATE
2164 The kernel traps and emulates calls into the fixed
2165 vsyscall address mapping. This makes the mapping
2166 non-executable, but it still contains known contents,
2167 which could be used in certain rare security vulnerability
2168 exploits. This configuration is recommended when userspace
2169 still uses the vsyscall area.
2171 config LEGACY_VSYSCALL_NONE
2174 There will be no vsyscall mapping at all. This will
2175 eliminate any risk of ASLR bypass due to the vsyscall
2176 fixed address mapping. Attempts to use the vsyscalls
2177 will be reported to dmesg, so that either old or
2178 malicious userspace programs can be identified.
2183 bool "Built-in kernel command line"
2185 Allow for specifying boot arguments to the kernel at
2186 build time. On some systems (e.g. embedded ones), it is
2187 necessary or convenient to provide some or all of the
2188 kernel boot arguments with the kernel itself (that is,
2189 to not rely on the boot loader to provide them.)
2191 To compile command line arguments into the kernel,
2192 set this option to 'Y', then fill in the
2193 boot arguments in CONFIG_CMDLINE.
2195 Systems with fully functional boot loaders (i.e. non-embedded)
2196 should leave this option set to 'N'.
2199 string "Built-in kernel command string"
2200 depends on CMDLINE_BOOL
2203 Enter arguments here that should be compiled into the kernel
2204 image and used at boot time. If the boot loader provides a
2205 command line at boot time, it is appended to this string to
2206 form the full kernel command line, when the system boots.
2208 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2209 change this behavior.
2211 In most cases, the command line (whether built-in or provided
2212 by the boot loader) should specify the device for the root
2215 config CMDLINE_OVERRIDE
2216 bool "Built-in command line overrides boot loader arguments"
2217 depends on CMDLINE_BOOL
2219 Set this option to 'Y' to have the kernel ignore the boot loader
2220 command line, and use ONLY the built-in command line.
2222 This is used to work around broken boot loaders. This should
2223 be set to 'N' under normal conditions.
2225 config MODIFY_LDT_SYSCALL
2226 bool "Enable the LDT (local descriptor table)" if EXPERT
2229 Linux can allow user programs to install a per-process x86
2230 Local Descriptor Table (LDT) using the modify_ldt(2) system
2231 call. This is required to run 16-bit or segmented code such as
2232 DOSEMU or some Wine programs. It is also used by some very old
2233 threading libraries.
2235 Enabling this feature adds a small amount of overhead to
2236 context switches and increases the low-level kernel attack
2237 surface. Disabling it removes the modify_ldt(2) system call.
2239 Saying 'N' here may make sense for embedded or server kernels.
2241 source "kernel/livepatch/Kconfig"
2245 config ARCH_ENABLE_MEMORY_HOTPLUG
2247 depends on X86_64 || (X86_32 && HIGHMEM)
2249 config ARCH_ENABLE_MEMORY_HOTREMOVE
2251 depends on MEMORY_HOTPLUG
2253 config USE_PERCPU_NUMA_NODE_ID
2257 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2259 depends on X86_64 || X86_PAE
2261 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2263 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2265 menu "Power management and ACPI options"
2267 config ARCH_HIBERNATION_HEADER
2269 depends on X86_64 && HIBERNATION
2271 source "kernel/power/Kconfig"
2273 source "drivers/acpi/Kconfig"
2275 source "drivers/sfi/Kconfig"
2282 tristate "APM (Advanced Power Management) BIOS support"
2283 depends on X86_32 && PM_SLEEP
2285 APM is a BIOS specification for saving power using several different
2286 techniques. This is mostly useful for battery powered laptops with
2287 APM compliant BIOSes. If you say Y here, the system time will be
2288 reset after a RESUME operation, the /proc/apm device will provide
2289 battery status information, and user-space programs will receive
2290 notification of APM "events" (e.g. battery status change).
2292 If you select "Y" here, you can disable actual use of the APM
2293 BIOS by passing the "apm=off" option to the kernel at boot time.
2295 Note that the APM support is almost completely disabled for
2296 machines with more than one CPU.
2298 In order to use APM, you will need supporting software. For location
2299 and more information, read <file:Documentation/power/apm-acpi.txt>
2300 and the Battery Powered Linux mini-HOWTO, available from
2301 <http://www.tldp.org/docs.html#howto>.
2303 This driver does not spin down disk drives (see the hdparm(8)
2304 manpage ("man 8 hdparm") for that), and it doesn't turn off
2305 VESA-compliant "green" monitors.
2307 This driver does not support the TI 4000M TravelMate and the ACER
2308 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2309 desktop machines also don't have compliant BIOSes, and this driver
2310 may cause those machines to panic during the boot phase.
2312 Generally, if you don't have a battery in your machine, there isn't
2313 much point in using this driver and you should say N. If you get
2314 random kernel OOPSes or reboots that don't seem to be related to
2315 anything, try disabling/enabling this option (or disabling/enabling
2318 Some other things you should try when experiencing seemingly random,
2321 1) make sure that you have enough swap space and that it is
2323 2) pass the "no-hlt" option to the kernel
2324 3) switch on floating point emulation in the kernel and pass
2325 the "no387" option to the kernel
2326 4) pass the "floppy=nodma" option to the kernel
2327 5) pass the "mem=4M" option to the kernel (thereby disabling
2328 all but the first 4 MB of RAM)
2329 6) make sure that the CPU is not over clocked.
2330 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2331 8) disable the cache from your BIOS settings
2332 9) install a fan for the video card or exchange video RAM
2333 10) install a better fan for the CPU
2334 11) exchange RAM chips
2335 12) exchange the motherboard.
2337 To compile this driver as a module, choose M here: the
2338 module will be called apm.
2342 config APM_IGNORE_USER_SUSPEND
2343 bool "Ignore USER SUSPEND"
2345 This option will ignore USER SUSPEND requests. On machines with a
2346 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2347 series notebooks, it is necessary to say Y because of a BIOS bug.
2349 config APM_DO_ENABLE
2350 bool "Enable PM at boot time"
2352 Enable APM features at boot time. From page 36 of the APM BIOS
2353 specification: "When disabled, the APM BIOS does not automatically
2354 power manage devices, enter the Standby State, enter the Suspend
2355 State, or take power saving steps in response to CPU Idle calls."
2356 This driver will make CPU Idle calls when Linux is idle (unless this
2357 feature is turned off -- see "Do CPU IDLE calls", below). This
2358 should always save battery power, but more complicated APM features
2359 will be dependent on your BIOS implementation. You may need to turn
2360 this option off if your computer hangs at boot time when using APM
2361 support, or if it beeps continuously instead of suspending. Turn
2362 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2363 T400CDT. This is off by default since most machines do fine without
2368 bool "Make CPU Idle calls when idle"
2370 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2371 On some machines, this can activate improved power savings, such as
2372 a slowed CPU clock rate, when the machine is idle. These idle calls
2373 are made after the idle loop has run for some length of time (e.g.,
2374 333 mS). On some machines, this will cause a hang at boot time or
2375 whenever the CPU becomes idle. (On machines with more than one CPU,
2376 this option does nothing.)
2378 config APM_DISPLAY_BLANK
2379 bool "Enable console blanking using APM"
2381 Enable console blanking using the APM. Some laptops can use this to
2382 turn off the LCD backlight when the screen blanker of the Linux
2383 virtual console blanks the screen. Note that this is only used by
2384 the virtual console screen blanker, and won't turn off the backlight
2385 when using the X Window system. This also doesn't have anything to
2386 do with your VESA-compliant power-saving monitor. Further, this
2387 option doesn't work for all laptops -- it might not turn off your
2388 backlight at all, or it might print a lot of errors to the console,
2389 especially if you are using gpm.
2391 config APM_ALLOW_INTS
2392 bool "Allow interrupts during APM BIOS calls"
2394 Normally we disable external interrupts while we are making calls to
2395 the APM BIOS as a measure to lessen the effects of a badly behaving
2396 BIOS implementation. The BIOS should reenable interrupts if it
2397 needs to. Unfortunately, some BIOSes do not -- especially those in
2398 many of the newer IBM Thinkpads. If you experience hangs when you
2399 suspend, try setting this to Y. Otherwise, say N.
2403 source "drivers/cpufreq/Kconfig"
2405 source "drivers/cpuidle/Kconfig"
2407 source "drivers/idle/Kconfig"
2412 menu "Bus options (PCI etc.)"
2418 Find out whether you have a PCI motherboard. PCI is the name of a
2419 bus system, i.e. the way the CPU talks to the other stuff inside
2420 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2421 VESA. If you have PCI, say Y, otherwise N.
2424 prompt "PCI access mode"
2425 depends on X86_32 && PCI
2428 On PCI systems, the BIOS can be used to detect the PCI devices and
2429 determine their configuration. However, some old PCI motherboards
2430 have BIOS bugs and may crash if this is done. Also, some embedded
2431 PCI-based systems don't have any BIOS at all. Linux can also try to
2432 detect the PCI hardware directly without using the BIOS.
2434 With this option, you can specify how Linux should detect the
2435 PCI devices. If you choose "BIOS", the BIOS will be used,
2436 if you choose "Direct", the BIOS won't be used, and if you
2437 choose "MMConfig", then PCI Express MMCONFIG will be used.
2438 If you choose "Any", the kernel will try MMCONFIG, then the
2439 direct access method and falls back to the BIOS if that doesn't
2440 work. If unsure, go with the default, which is "Any".
2445 config PCI_GOMMCONFIG
2462 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2464 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2467 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2471 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2475 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2479 depends on PCI && XEN
2487 bool "Support mmconfig PCI config space access"
2488 depends on X86_64 && PCI && ACPI
2490 config PCI_CNB20LE_QUIRK
2491 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2494 Read the PCI windows out of the CNB20LE host bridge. This allows
2495 PCI hotplug to work on systems with the CNB20LE chipset which do
2498 There's no public spec for this chipset, and this functionality
2499 is known to be incomplete.
2501 You should say N unless you know you need this.
2503 source "drivers/pci/Kconfig"
2506 bool "ISA-style bus support on modern systems" if EXPERT
2509 Enables ISA-style drivers on modern systems. This is necessary to
2510 support PC/104 devices on X86_64 platforms.
2514 # x86_64 have no ISA slots, but can have ISA-style DMA.
2516 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2519 Enables ISA-style DMA support for devices requiring such controllers.
2527 Find out whether you have ISA slots on your motherboard. ISA is the
2528 name of a bus system, i.e. the way the CPU talks to the other stuff
2529 inside your box. Other bus systems are PCI, EISA, MicroChannel
2530 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2531 newer boards don't support it. If you have ISA, say Y, otherwise N.
2537 The Extended Industry Standard Architecture (EISA) bus was
2538 developed as an open alternative to the IBM MicroChannel bus.
2540 The EISA bus provided some of the features of the IBM MicroChannel
2541 bus while maintaining backward compatibility with cards made for
2542 the older ISA bus. The EISA bus saw limited use between 1988 and
2543 1995 when it was made obsolete by the PCI bus.
2545 Say Y here if you are building a kernel for an EISA-based machine.
2549 source "drivers/eisa/Kconfig"
2552 tristate "NatSemi SCx200 support"
2554 This provides basic support for National Semiconductor's
2555 (now AMD's) Geode processors. The driver probes for the
2556 PCI-IDs of several on-chip devices, so its a good dependency
2557 for other scx200_* drivers.
2559 If compiled as a module, the driver is named scx200.
2561 config SCx200HR_TIMER
2562 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2566 This driver provides a clocksource built upon the on-chip
2567 27MHz high-resolution timer. Its also a workaround for
2568 NSC Geode SC-1100's buggy TSC, which loses time when the
2569 processor goes idle (as is done by the scheduler). The
2570 other workaround is idle=poll boot option.
2573 bool "One Laptop Per Child support"
2580 Add support for detecting the unique features of the OLPC
2584 bool "OLPC XO-1 Power Management"
2585 depends on OLPC && MFD_CS5535 && PM_SLEEP
2588 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2591 bool "OLPC XO-1 Real Time Clock"
2592 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2594 Add support for the XO-1 real time clock, which can be used as a
2595 programmable wakeup source.
2598 bool "OLPC XO-1 SCI extras"
2599 depends on OLPC && OLPC_XO1_PM
2605 Add support for SCI-based features of the OLPC XO-1 laptop:
2606 - EC-driven system wakeups
2610 - AC adapter status updates
2611 - Battery status updates
2613 config OLPC_XO15_SCI
2614 bool "OLPC XO-1.5 SCI extras"
2615 depends on OLPC && ACPI
2618 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2619 - EC-driven system wakeups
2620 - AC adapter status updates
2621 - Battery status updates
2624 bool "PCEngines ALIX System Support (LED setup)"
2627 This option enables system support for the PCEngines ALIX.
2628 At present this just sets up LEDs for GPIO control on
2629 ALIX2/3/6 boards. However, other system specific setup should
2632 Note: You must still enable the drivers for GPIO and LED support
2633 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2635 Note: You have to set alix.force=1 for boards with Award BIOS.
2638 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2641 This option enables system support for the Soekris Engineering net5501.
2644 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2648 This option enables system support for the Traverse Technologies GEOS.
2651 bool "Technologic Systems TS-5500 platform support"
2653 select CHECK_SIGNATURE
2657 This option enables system support for the Technologic Systems TS-5500.
2663 depends on CPU_SUP_AMD && PCI
2665 source "drivers/pcmcia/Kconfig"
2668 tristate "RapidIO support"
2672 If enabled this option will include drivers and the core
2673 infrastructure code to support RapidIO interconnect devices.
2675 source "drivers/rapidio/Kconfig"
2678 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2680 Firmwares often provide initial graphics framebuffers so the BIOS,
2681 bootloader or kernel can show basic video-output during boot for
2682 user-guidance and debugging. Historically, x86 used the VESA BIOS
2683 Extensions and EFI-framebuffers for this, which are mostly limited
2685 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2686 framebuffers so the new generic system-framebuffer drivers can be
2687 used on x86. If the framebuffer is not compatible with the generic
2688 modes, it is adverticed as fallback platform framebuffer so legacy
2689 drivers like efifb, vesafb and uvesafb can pick it up.
2690 If this option is not selected, all system framebuffers are always
2691 marked as fallback platform framebuffers as usual.
2693 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2694 not be able to pick up generic system framebuffers if this option
2695 is selected. You are highly encouraged to enable simplefb as
2696 replacement if you select this option. simplefb can correctly deal
2697 with generic system framebuffers. But you should still keep vesafb
2698 and others enabled as fallback if a system framebuffer is
2699 incompatible with simplefb.
2706 menu "Executable file formats / Emulations"
2708 source "fs/Kconfig.binfmt"
2710 config IA32_EMULATION
2711 bool "IA32 Emulation"
2713 select ARCH_WANT_OLD_COMPAT_IPC
2715 select COMPAT_BINFMT_ELF
2716 select COMPAT_OLD_SIGACTION
2718 Include code to run legacy 32-bit programs under a
2719 64-bit kernel. You should likely turn this on, unless you're
2720 100% sure that you don't have any 32-bit programs left.
2723 tristate "IA32 a.out support"
2724 depends on IA32_EMULATION
2726 Support old a.out binaries in the 32bit emulation.
2729 bool "x32 ABI for 64-bit mode"
2732 Include code to run binaries for the x32 native 32-bit ABI
2733 for 64-bit processors. An x32 process gets access to the
2734 full 64-bit register file and wide data path while leaving
2735 pointers at 32 bits for smaller memory footprint.
2737 You will need a recent binutils (2.22 or later) with
2738 elf32_x86_64 support enabled to compile a kernel with this
2743 depends on IA32_EMULATION || X86_32
2745 select OLD_SIGSUSPEND3
2749 depends on IA32_EMULATION || X86_X32
2752 config COMPAT_FOR_U64_ALIGNMENT
2755 config SYSVIPC_COMPAT
2767 config HAVE_ATOMIC_IOMAP
2771 config X86_DEV_DMA_OPS
2773 depends on X86_64 || STA2X11
2775 config X86_DMA_REMAP
2783 source "net/Kconfig"
2785 source "drivers/Kconfig"
2787 source "drivers/firmware/Kconfig"
2791 source "arch/x86/Kconfig.debug"
2793 source "security/Kconfig"
2795 source "crypto/Kconfig"
2797 source "arch/x86/kvm/Kconfig"
2799 source "lib/Kconfig"