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_STRICT_KERNEL_RWX
58 select ARCH_HAS_STRICT_MODULE_RWX
59 select ARCH_HAS_UBSAN_SANITIZE_ALL
60 select ARCH_HAVE_NMI_SAFE_CMPXCHG
61 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
62 select ARCH_MIGHT_HAVE_PC_PARPORT
63 select ARCH_MIGHT_HAVE_PC_SERIO
64 select ARCH_SUPPORTS_ATOMIC_RMW
65 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
66 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
67 select ARCH_USE_BUILTIN_BSWAP
68 select ARCH_USE_QUEUED_RWLOCKS
69 select ARCH_USE_QUEUED_SPINLOCKS
70 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
71 select ARCH_WANT_FRAME_POINTERS
72 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
73 select BUILDTIME_EXTABLE_SORT
75 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
76 select CLOCKSOURCE_WATCHDOG
77 select DCACHE_WORD_ACCESS
78 select EDAC_ATOMIC_SCRUB
80 select GENERIC_CLOCKEVENTS
81 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
82 select GENERIC_CLOCKEVENTS_MIN_ADJUST
83 select GENERIC_CMOS_UPDATE
84 select GENERIC_CPU_AUTOPROBE
85 select GENERIC_EARLY_IOREMAP
86 select GENERIC_FIND_FIRST_BIT
88 select GENERIC_IRQ_PROBE
89 select GENERIC_IRQ_SHOW
90 select GENERIC_PENDING_IRQ if SMP
91 select GENERIC_SMP_IDLE_THREAD
92 select GENERIC_STRNCPY_FROM_USER
93 select GENERIC_STRNLEN_USER
94 select GENERIC_TIME_VSYSCALL
95 select HAVE_ACPI_APEI if ACPI
96 select HAVE_ACPI_APEI_NMI if ACPI
97 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
98 select HAVE_ARCH_AUDITSYSCALL
99 select HAVE_ARCH_HARDENED_USERCOPY
100 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
101 select HAVE_ARCH_JUMP_LABEL
102 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
103 select HAVE_ARCH_KGDB
104 select HAVE_ARCH_KMEMCHECK
105 select HAVE_ARCH_MMAP_RND_BITS if MMU
106 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
107 select HAVE_ARCH_SECCOMP_FILTER
108 select HAVE_ARCH_TRACEHOOK
109 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
110 select HAVE_ARCH_VMAP_STACK if X86_64
111 select HAVE_ARCH_WITHIN_STACK_FRAMES
112 select HAVE_CC_STACKPROTECTOR
113 select HAVE_CMPXCHG_DOUBLE
114 select HAVE_CMPXCHG_LOCAL
115 select HAVE_CONTEXT_TRACKING if X86_64
116 select HAVE_COPY_THREAD_TLS
117 select HAVE_C_RECORDMCOUNT
118 select HAVE_DEBUG_KMEMLEAK
119 select HAVE_DEBUG_STACKOVERFLOW
120 select HAVE_DMA_API_DEBUG
121 select HAVE_DMA_CONTIGUOUS
122 select HAVE_DYNAMIC_FTRACE
123 select HAVE_DYNAMIC_FTRACE_WITH_REGS
124 select HAVE_EBPF_JIT if X86_64
125 select HAVE_EFFICIENT_UNALIGNED_ACCESS
126 select HAVE_EXIT_THREAD
127 select HAVE_FENTRY if X86_64
128 select HAVE_FTRACE_MCOUNT_RECORD
129 select HAVE_FUNCTION_GRAPH_TRACER
130 select HAVE_FUNCTION_TRACER
131 select HAVE_GCC_PLUGINS
132 select HAVE_HW_BREAKPOINT
134 select HAVE_IOREMAP_PROT
135 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
136 select HAVE_IRQ_TIME_ACCOUNTING
137 select HAVE_KERNEL_BZIP2
138 select HAVE_KERNEL_GZIP
139 select HAVE_KERNEL_LZ4
140 select HAVE_KERNEL_LZMA
141 select HAVE_KERNEL_LZO
142 select HAVE_KERNEL_XZ
144 select HAVE_KPROBES_ON_FTRACE
145 select HAVE_KRETPROBES
147 select HAVE_LIVEPATCH if X86_64
149 select HAVE_MEMBLOCK_NODE_MAP
150 select HAVE_MIXED_BREAKPOINTS_REGS
153 select HAVE_OPTPROBES
154 select HAVE_PCSPKR_PLATFORM
155 select HAVE_PERF_EVENTS
156 select HAVE_PERF_EVENTS_NMI
157 select HAVE_PERF_REGS
158 select HAVE_PERF_USER_STACK_DUMP
159 select HAVE_REGS_AND_STACK_ACCESS_API
160 select HAVE_STACK_VALIDATION if X86_64
161 select HAVE_SYSCALL_TRACEPOINTS
162 select HAVE_UNSTABLE_SCHED_CLOCK
163 select HAVE_USER_RETURN_NOTIFIER
164 select IRQ_FORCED_THREADING
167 select RTC_MC146818_LIB
170 select SYSCTL_EXCEPTION_TRACE
171 select THREAD_INFO_IN_TASK
172 select USER_STACKTRACE_SUPPORT
174 select X86_FEATURE_NAMES if PROC_FS
176 config INSTRUCTION_DECODER
178 depends on KPROBES || PERF_EVENTS || UPROBES
182 default "elf32-i386" if X86_32
183 default "elf64-x86-64" if X86_64
185 config ARCH_DEFCONFIG
187 default "arch/x86/configs/i386_defconfig" if X86_32
188 default "arch/x86/configs/x86_64_defconfig" if X86_64
190 config LOCKDEP_SUPPORT
193 config STACKTRACE_SUPPORT
199 config ARCH_MMAP_RND_BITS_MIN
203 config ARCH_MMAP_RND_BITS_MAX
207 config ARCH_MMAP_RND_COMPAT_BITS_MIN
210 config ARCH_MMAP_RND_COMPAT_BITS_MAX
216 config NEED_DMA_MAP_STATE
218 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
220 config NEED_SG_DMA_LENGTH
223 config GENERIC_ISA_DMA
225 depends on ISA_DMA_API
230 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
232 config GENERIC_BUG_RELATIVE_POINTERS
235 config GENERIC_HWEIGHT
238 config ARCH_MAY_HAVE_PC_FDC
240 depends on ISA_DMA_API
242 config RWSEM_XCHGADD_ALGORITHM
245 config GENERIC_CALIBRATE_DELAY
248 config ARCH_HAS_CPU_RELAX
251 config ARCH_HAS_CACHE_LINE_SIZE
254 config HAVE_SETUP_PER_CPU_AREA
257 config NEED_PER_CPU_EMBED_FIRST_CHUNK
260 config NEED_PER_CPU_PAGE_FIRST_CHUNK
263 config ARCH_HIBERNATION_POSSIBLE
266 config ARCH_SUSPEND_POSSIBLE
269 config ARCH_WANT_HUGE_PMD_SHARE
272 config ARCH_WANT_GENERAL_HUGETLB
281 config ARCH_SUPPORTS_OPTIMIZED_INLINING
284 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
287 config KASAN_SHADOW_OFFSET
290 default 0xdffffc0000000000
292 config HAVE_INTEL_TXT
294 depends on INTEL_IOMMU && ACPI
298 depends on X86_32 && SMP
302 depends on X86_64 && SMP
304 config X86_32_LAZY_GS
306 depends on X86_32 && !CC_STACKPROTECTOR
308 config ARCH_SUPPORTS_UPROBES
311 config FIX_EARLYCON_MEM
314 config PGTABLE_LEVELS
320 source "init/Kconfig"
321 source "kernel/Kconfig.freezer"
323 menu "Processor type and features"
326 bool "DMA memory allocation support" if EXPERT
329 DMA memory allocation support allows devices with less than 32-bit
330 addressing to allocate within the first 16MB of address space.
331 Disable if no such devices will be used.
336 bool "Symmetric multi-processing support"
338 This enables support for systems with more than one CPU. If you have
339 a system with only one CPU, say N. If you have a system with more
342 If you say N here, the kernel will run on uni- and multiprocessor
343 machines, but will use only one CPU of a multiprocessor machine. If
344 you say Y here, the kernel will run on many, but not all,
345 uniprocessor machines. On a uniprocessor machine, the kernel
346 will run faster if you say N here.
348 Note that if you say Y here and choose architecture "586" or
349 "Pentium" under "Processor family", the kernel will not work on 486
350 architectures. Similarly, multiprocessor kernels for the "PPro"
351 architecture may not work on all Pentium based boards.
353 People using multiprocessor machines who say Y here should also say
354 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
355 Management" code will be disabled if you say Y here.
357 See also <file:Documentation/x86/i386/IO-APIC.txt>,
358 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
359 <http://www.tldp.org/docs.html#howto>.
361 If you don't know what to do here, say N.
363 config X86_FEATURE_NAMES
364 bool "Processor feature human-readable names" if EMBEDDED
367 This option compiles in a table of x86 feature bits and corresponding
368 names. This is required to support /proc/cpuinfo and a few kernel
369 messages. You can disable this to save space, at the expense of
370 making those few kernel messages show numeric feature bits instead.
374 config X86_FAST_FEATURE_TESTS
375 bool "Fast CPU feature tests" if EMBEDDED
378 Some fast-paths in the kernel depend on the capabilities of the CPU.
379 Say Y here for the kernel to patch in the appropriate code at runtime
380 based on the capabilities of the CPU. The infrastructure for patching
381 code at runtime takes up some additional space; space-constrained
382 embedded systems may wish to say N here to produce smaller, slightly
386 bool "Support x2apic"
387 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
389 This enables x2apic support on CPUs that have this feature.
391 This allows 32-bit apic IDs (so it can support very large systems),
392 and accesses the local apic via MSRs not via mmio.
394 If you don't know what to do here, say N.
397 bool "Enable MPS table" if ACPI || SFI
399 depends on X86_LOCAL_APIC
401 For old smp systems that do not have proper acpi support. Newer systems
402 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
405 bool "Support for big SMP systems with more than 8 CPUs"
406 depends on X86_32 && SMP
408 This option is needed for the systems that have more than 8 CPUs
412 depends on X86_GOLDFISH
415 bool "Intel Resource Director Technology Allocation support"
417 depends on X86 && CPU_SUP_INTEL
420 Select to enable resource allocation which is a sub-feature of
421 Intel Resource Director Technology(RDT). More information about
422 RDT can be found in the Intel x86 Architecture Software
428 config X86_EXTENDED_PLATFORM
429 bool "Support for extended (non-PC) x86 platforms"
432 If you disable this option then the kernel will only support
433 standard PC platforms. (which covers the vast majority of
436 If you enable this option then you'll be able to select support
437 for the following (non-PC) 32 bit x86 platforms:
438 Goldfish (Android emulator)
441 SGI 320/540 (Visual Workstation)
442 STA2X11-based (e.g. Northville)
443 Moorestown MID devices
445 If you have one of these systems, or if you want to build a
446 generic distribution kernel, say Y here - otherwise say N.
450 config X86_EXTENDED_PLATFORM
451 bool "Support for extended (non-PC) x86 platforms"
454 If you disable this option then the kernel will only support
455 standard PC platforms. (which covers the vast majority of
458 If you enable this option then you'll be able to select support
459 for the following (non-PC) 64 bit x86 platforms:
464 If you have one of these systems, or if you want to build a
465 generic distribution kernel, say Y here - otherwise say N.
467 # This is an alphabetically sorted list of 64 bit extended platforms
468 # Please maintain the alphabetic order if and when there are additions
470 bool "Numascale NumaChip"
472 depends on X86_EXTENDED_PLATFORM
475 depends on X86_X2APIC
476 depends on PCI_MMCONFIG
478 Adds support for Numascale NumaChip large-SMP systems. Needed to
479 enable more than ~168 cores.
480 If you don't have one of these, you should say N here.
484 select HYPERVISOR_GUEST
486 depends on X86_64 && PCI
487 depends on X86_EXTENDED_PLATFORM
490 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
491 supposed to run on these EM64T-based machines. Only choose this option
492 if you have one of these machines.
495 bool "SGI Ultraviolet"
497 depends on X86_EXTENDED_PLATFORM
500 depends on X86_X2APIC
503 This option is needed in order to support SGI Ultraviolet systems.
504 If you don't have one of these, you should say N here.
506 # Following is an alphabetically sorted list of 32 bit extended platforms
507 # Please maintain the alphabetic order if and when there are additions
510 bool "Goldfish (Virtual Platform)"
511 depends on X86_EXTENDED_PLATFORM
513 Enable support for the Goldfish virtual platform used primarily
514 for Android development. Unless you are building for the Android
515 Goldfish emulator say N here.
518 bool "CE4100 TV platform"
520 depends on PCI_GODIRECT
521 depends on X86_IO_APIC
523 depends on X86_EXTENDED_PLATFORM
524 select X86_REBOOTFIXUPS
526 select OF_EARLY_FLATTREE
528 Select for the Intel CE media processor (CE4100) SOC.
529 This option compiles in support for the CE4100 SOC for settop
530 boxes and media devices.
533 bool "Intel MID platform support"
534 depends on X86_EXTENDED_PLATFORM
535 depends on X86_PLATFORM_DEVICES
537 depends on X86_64 || (PCI_GOANY && X86_32)
538 depends on X86_IO_APIC
544 select MFD_INTEL_MSIC
546 Select to build a kernel capable of supporting Intel MID (Mobile
547 Internet Device) platform systems which do not have the PCI legacy
548 interfaces. If you are building for a PC class system say N here.
550 Intel MID platforms are based on an Intel processor and chipset which
551 consume less power than most of the x86 derivatives.
553 config X86_INTEL_QUARK
554 bool "Intel Quark platform support"
556 depends on X86_EXTENDED_PLATFORM
557 depends on X86_PLATFORM_DEVICES
561 depends on X86_IO_APIC
566 Select to include support for Quark X1000 SoC.
567 Say Y here if you have a Quark based system such as the Arduino
568 compatible Intel Galileo.
570 config X86_INTEL_LPSS
571 bool "Intel Low Power Subsystem Support"
572 depends on X86 && ACPI
577 Select to build support for Intel Low Power Subsystem such as
578 found on Intel Lynxpoint PCH. Selecting this option enables
579 things like clock tree (common clock framework) and pincontrol
580 which are needed by the LPSS peripheral drivers.
582 config X86_AMD_PLATFORM_DEVICE
583 bool "AMD ACPI2Platform devices support"
588 Select to interpret AMD specific ACPI device to platform device
589 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
590 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
591 implemented under PINCTRL subsystem.
594 tristate "Intel SoC IOSF Sideband support for SoC platforms"
597 This option enables sideband register access support for Intel SoC
598 platforms. On these platforms the IOSF sideband is used in lieu of
599 MSR's for some register accesses, mostly but not limited to thermal
600 and power. Drivers may query the availability of this device to
601 determine if they need the sideband in order to work on these
602 platforms. The sideband is available on the following SoC products.
603 This list is not meant to be exclusive.
608 You should say Y if you are running a kernel on one of these SoC's.
610 config IOSF_MBI_DEBUG
611 bool "Enable IOSF sideband access through debugfs"
612 depends on IOSF_MBI && DEBUG_FS
614 Select this option to expose the IOSF sideband access registers (MCR,
615 MDR, MCRX) through debugfs to write and read register information from
616 different units on the SoC. This is most useful for obtaining device
617 state information for debug and analysis. As this is a general access
618 mechanism, users of this option would have specific knowledge of the
619 device they want to access.
621 If you don't require the option or are in doubt, say N.
624 bool "RDC R-321x SoC"
626 depends on X86_EXTENDED_PLATFORM
628 select X86_REBOOTFIXUPS
630 This option is needed for RDC R-321x system-on-chip, also known
632 If you don't have one of these chips, you should say N here.
634 config X86_32_NON_STANDARD
635 bool "Support non-standard 32-bit SMP architectures"
636 depends on X86_32 && SMP
637 depends on X86_EXTENDED_PLATFORM
639 This option compiles in the bigsmp and STA2X11 default
640 subarchitectures. It is intended for a generic binary
641 kernel. If you select them all, kernel will probe it one by
642 one and will fallback to default.
644 # Alphabetically sorted list of Non standard 32 bit platforms
646 config X86_SUPPORTS_MEMORY_FAILURE
648 # MCE code calls memory_failure():
650 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
651 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
652 depends on X86_64 || !SPARSEMEM
653 select ARCH_SUPPORTS_MEMORY_FAILURE
656 bool "STA2X11 Companion Chip Support"
657 depends on X86_32_NON_STANDARD && PCI
658 select X86_DEV_DMA_OPS
665 This adds support for boards based on the STA2X11 IO-Hub,
666 a.k.a. "ConneXt". The chip is used in place of the standard
667 PC chipset, so all "standard" peripherals are missing. If this
668 option is selected the kernel will still be able to boot on
669 standard PC machines.
672 tristate "Eurobraille/Iris poweroff module"
675 The Iris machines from EuroBraille do not have APM or ACPI support
676 to shut themselves down properly. A special I/O sequence is
677 needed to do so, which is what this module does at
680 This is only for Iris machines from EuroBraille.
684 config SCHED_OMIT_FRAME_POINTER
686 prompt "Single-depth WCHAN output"
689 Calculate simpler /proc/<PID>/wchan values. If this option
690 is disabled then wchan values will recurse back to the
691 caller function. This provides more accurate wchan values,
692 at the expense of slightly more scheduling overhead.
694 If in doubt, say "Y".
696 menuconfig HYPERVISOR_GUEST
697 bool "Linux guest support"
699 Say Y here to enable options for running Linux under various hyper-
700 visors. This option enables basic hypervisor detection and platform
703 If you say N, all options in this submenu will be skipped and
704 disabled, and Linux guest support won't be built in.
709 bool "Enable paravirtualization code"
711 This changes the kernel so it can modify itself when it is run
712 under a hypervisor, potentially improving performance significantly
713 over full virtualization. However, when run without a hypervisor
714 the kernel is theoretically slower and slightly larger.
716 config PARAVIRT_DEBUG
717 bool "paravirt-ops debugging"
718 depends on PARAVIRT && DEBUG_KERNEL
720 Enable to debug paravirt_ops internals. Specifically, BUG if
721 a paravirt_op is missing when it is called.
723 config PARAVIRT_SPINLOCKS
724 bool "Paravirtualization layer for spinlocks"
725 depends on PARAVIRT && SMP
727 Paravirtualized spinlocks allow a pvops backend to replace the
728 spinlock implementation with something virtualization-friendly
729 (for example, block the virtual CPU rather than spinning).
731 It has a minimal impact on native kernels and gives a nice performance
732 benefit on paravirtualized KVM / Xen kernels.
734 If you are unsure how to answer this question, answer Y.
736 config QUEUED_LOCK_STAT
737 bool "Paravirt queued spinlock statistics"
738 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
740 Enable the collection of statistical data on the slowpath
741 behavior of paravirtualized queued spinlocks and report
744 source "arch/x86/xen/Kconfig"
747 bool "KVM Guest support (including kvmclock)"
749 select PARAVIRT_CLOCK
752 This option enables various optimizations for running under the KVM
753 hypervisor. It includes a paravirtualized clock, so that instead
754 of relying on a PIT (or probably other) emulation by the
755 underlying device model, the host provides the guest with
756 timing infrastructure such as time of day, and system time
759 bool "Enable debug information for KVM Guests in debugfs"
760 depends on KVM_GUEST && DEBUG_FS
763 This option enables collection of various statistics for KVM guest.
764 Statistics are displayed in debugfs filesystem. Enabling this option
765 may incur significant overhead.
767 source "arch/x86/lguest/Kconfig"
769 config PARAVIRT_TIME_ACCOUNTING
770 bool "Paravirtual steal time accounting"
774 Select this option to enable fine granularity task steal time
775 accounting. Time spent executing other tasks in parallel with
776 the current vCPU is discounted from the vCPU power. To account for
777 that, there can be a small performance impact.
779 If in doubt, say N here.
781 config PARAVIRT_CLOCK
784 endif #HYPERVISOR_GUEST
789 source "arch/x86/Kconfig.cpu"
793 prompt "HPET Timer Support" if X86_32
795 Use the IA-PC HPET (High Precision Event Timer) to manage
796 time in preference to the PIT and RTC, if a HPET is
798 HPET is the next generation timer replacing legacy 8254s.
799 The HPET provides a stable time base on SMP
800 systems, unlike the TSC, but it is more expensive to access,
801 as it is off-chip. The interface used is documented
802 in the HPET spec, revision 1.
804 You can safely choose Y here. However, HPET will only be
805 activated if the platform and the BIOS support this feature.
806 Otherwise the 8254 will be used for timing services.
808 Choose N to continue using the legacy 8254 timer.
810 config HPET_EMULATE_RTC
812 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
815 def_bool y if X86_INTEL_MID
816 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
818 depends on X86_INTEL_MID && SFI
820 APB timer is the replacement for 8254, HPET on X86 MID platforms.
821 The APBT provides a stable time base on SMP
822 systems, unlike the TSC, but it is more expensive to access,
823 as it is off-chip. APB timers are always running regardless of CPU
824 C states, they are used as per CPU clockevent device when possible.
826 # Mark as expert because too many people got it wrong.
827 # The code disables itself when not needed.
830 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
831 bool "Enable DMI scanning" if EXPERT
833 Enabled scanning of DMI to identify machine quirks. Say Y
834 here unless you have verified that your setup is not
835 affected by entries in the DMI blacklist. Required by PNP
839 bool "Old AMD GART IOMMU support"
841 depends on X86_64 && PCI && AMD_NB
843 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
844 GART based hardware IOMMUs.
846 The GART supports full DMA access for devices with 32-bit access
847 limitations, on systems with more than 3 GB. This is usually needed
848 for USB, sound, many IDE/SATA chipsets and some other devices.
850 Newer systems typically have a modern AMD IOMMU, supported via
851 the CONFIG_AMD_IOMMU=y config option.
853 In normal configurations this driver is only active when needed:
854 there's more than 3 GB of memory and the system contains a
855 32-bit limited device.
860 bool "IBM Calgary IOMMU support"
862 depends on X86_64 && PCI
864 Support for hardware IOMMUs in IBM's xSeries x366 and x460
865 systems. Needed to run systems with more than 3GB of memory
866 properly with 32-bit PCI devices that do not support DAC
867 (Double Address Cycle). Calgary also supports bus level
868 isolation, where all DMAs pass through the IOMMU. This
869 prevents them from going anywhere except their intended
870 destination. This catches hard-to-find kernel bugs and
871 mis-behaving drivers and devices that do not use the DMA-API
872 properly to set up their DMA buffers. The IOMMU can be
873 turned off at boot time with the iommu=off parameter.
874 Normally the kernel will make the right choice by itself.
877 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
879 prompt "Should Calgary be enabled by default?"
880 depends on CALGARY_IOMMU
882 Should Calgary be enabled by default? if you choose 'y', Calgary
883 will be used (if it exists). If you choose 'n', Calgary will not be
884 used even if it exists. If you choose 'n' and would like to use
885 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
888 # need this always selected by IOMMU for the VIA workaround
892 Support for software bounce buffers used on x86-64 systems
893 which don't have a hardware IOMMU. Using this PCI devices
894 which can only access 32-bits of memory can be used on systems
895 with more than 3 GB of memory.
900 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
903 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
904 depends on X86_64 && SMP && DEBUG_KERNEL
905 select CPUMASK_OFFSTACK
907 Enable maximum number of CPUS and NUMA Nodes for this architecture.
911 int "Maximum number of CPUs" if SMP && !MAXSMP
912 range 2 8 if SMP && X86_32 && !X86_BIGSMP
913 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
914 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
916 default "8192" if MAXSMP
917 default "32" if SMP && X86_BIGSMP
918 default "8" if SMP && X86_32
921 This allows you to specify the maximum number of CPUs which this
922 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
923 supported value is 8192, otherwise the maximum value is 512. The
924 minimum value which makes sense is 2.
926 This is purely to save memory - each supported CPU adds
927 approximately eight kilobytes to the kernel image.
930 bool "SMT (Hyperthreading) scheduler support"
933 SMT scheduler support improves the CPU scheduler's decision making
934 when dealing with Intel Pentium 4 chips with HyperThreading at a
935 cost of slightly increased overhead in some places. If unsure say
940 prompt "Multi-core scheduler support"
943 Multi-core scheduler support improves the CPU scheduler's decision
944 making when dealing with multi-core CPU chips at a cost of slightly
945 increased overhead in some places. If unsure say N here.
948 bool "CPU core priorities scheduler support"
949 depends on SCHED_MC && CPU_SUP_INTEL
950 select X86_INTEL_PSTATE
954 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
955 core ordering determined at manufacturing time, which allows
956 certain cores to reach higher turbo frequencies (when running
957 single threaded workloads) than others.
959 Enabling this kernel feature teaches the scheduler about
960 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
961 scheduler's CPU selection logic accordingly, so that higher
962 overall system performance can be achieved.
964 This feature will have no effect on CPUs without this feature.
966 If unsure say Y here.
968 source "kernel/Kconfig.preempt"
972 depends on !SMP && X86_LOCAL_APIC
975 bool "Local APIC support on uniprocessors" if !PCI_MSI
977 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
979 A local APIC (Advanced Programmable Interrupt Controller) is an
980 integrated interrupt controller in the CPU. If you have a single-CPU
981 system which has a processor with a local APIC, you can say Y here to
982 enable and use it. If you say Y here even though your machine doesn't
983 have a local APIC, then the kernel will still run with no slowdown at
984 all. The local APIC supports CPU-generated self-interrupts (timer,
985 performance counters), and the NMI watchdog which detects hard
989 bool "IO-APIC support on uniprocessors"
990 depends on X86_UP_APIC
992 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
993 SMP-capable replacement for PC-style interrupt controllers. Most
994 SMP systems and many recent uniprocessor systems have one.
996 If you have a single-CPU system with an IO-APIC, you can say Y here
997 to use it. If you say Y here even though your machine doesn't have
998 an IO-APIC, then the kernel will still run with no slowdown at all.
1000 config X86_LOCAL_APIC
1002 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1003 select IRQ_DOMAIN_HIERARCHY
1004 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1008 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1010 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1011 bool "Reroute for broken boot IRQs"
1012 depends on X86_IO_APIC
1014 This option enables a workaround that fixes a source of
1015 spurious interrupts. This is recommended when threaded
1016 interrupt handling is used on systems where the generation of
1017 superfluous "boot interrupts" cannot be disabled.
1019 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1020 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1021 kernel does during interrupt handling). On chipsets where this
1022 boot IRQ generation cannot be disabled, this workaround keeps
1023 the original IRQ line masked so that only the equivalent "boot
1024 IRQ" is delivered to the CPUs. The workaround also tells the
1025 kernel to set up the IRQ handler on the boot IRQ line. In this
1026 way only one interrupt is delivered to the kernel. Otherwise
1027 the spurious second interrupt may cause the kernel to bring
1028 down (vital) interrupt lines.
1030 Only affects "broken" chipsets. Interrupt sharing may be
1031 increased on these systems.
1034 bool "Machine Check / overheating reporting"
1035 select GENERIC_ALLOCATOR
1038 Machine Check support allows the processor to notify the
1039 kernel if it detects a problem (e.g. overheating, data corruption).
1040 The action the kernel takes depends on the severity of the problem,
1041 ranging from warning messages to halting the machine.
1043 config X86_MCE_INTEL
1045 prompt "Intel MCE features"
1046 depends on X86_MCE && X86_LOCAL_APIC
1048 Additional support for intel specific MCE features such as
1049 the thermal monitor.
1053 prompt "AMD MCE features"
1054 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1056 Additional support for AMD specific MCE features such as
1057 the DRAM Error Threshold.
1059 config X86_ANCIENT_MCE
1060 bool "Support for old Pentium 5 / WinChip machine checks"
1061 depends on X86_32 && X86_MCE
1063 Include support for machine check handling on old Pentium 5 or WinChip
1064 systems. These typically need to be enabled explicitly on the command
1067 config X86_MCE_THRESHOLD
1068 depends on X86_MCE_AMD || X86_MCE_INTEL
1071 config X86_MCE_INJECT
1073 tristate "Machine check injector support"
1075 Provide support for injecting machine checks for testing purposes.
1076 If you don't know what a machine check is and you don't do kernel
1077 QA it is safe to say n.
1079 config X86_THERMAL_VECTOR
1081 depends on X86_MCE_INTEL
1083 source "arch/x86/events/Kconfig"
1085 config X86_LEGACY_VM86
1086 bool "Legacy VM86 support"
1090 This option allows user programs to put the CPU into V8086
1091 mode, which is an 80286-era approximation of 16-bit real mode.
1093 Some very old versions of X and/or vbetool require this option
1094 for user mode setting. Similarly, DOSEMU will use it if
1095 available to accelerate real mode DOS programs. However, any
1096 recent version of DOSEMU, X, or vbetool should be fully
1097 functional even without kernel VM86 support, as they will all
1098 fall back to software emulation. Nevertheless, if you are using
1099 a 16-bit DOS program where 16-bit performance matters, vm86
1100 mode might be faster than emulation and you might want to
1103 Note that any app that works on a 64-bit kernel is unlikely to
1104 need this option, as 64-bit kernels don't, and can't, support
1105 V8086 mode. This option is also unrelated to 16-bit protected
1106 mode and is not needed to run most 16-bit programs under Wine.
1108 Enabling this option increases the complexity of the kernel
1109 and slows down exception handling a tiny bit.
1111 If unsure, say N here.
1115 default X86_LEGACY_VM86
1118 bool "Enable support for 16-bit segments" if EXPERT
1120 depends on MODIFY_LDT_SYSCALL
1122 This option is required by programs like Wine to run 16-bit
1123 protected mode legacy code on x86 processors. Disabling
1124 this option saves about 300 bytes on i386, or around 6K text
1125 plus 16K runtime memory on x86-64,
1129 depends on X86_16BIT && X86_32
1133 depends on X86_16BIT && X86_64
1135 config X86_VSYSCALL_EMULATION
1136 bool "Enable vsyscall emulation" if EXPERT
1140 This enables emulation of the legacy vsyscall page. Disabling
1141 it is roughly equivalent to booting with vsyscall=none, except
1142 that it will also disable the helpful warning if a program
1143 tries to use a vsyscall. With this option set to N, offending
1144 programs will just segfault, citing addresses of the form
1147 This option is required by many programs built before 2013, and
1148 care should be used even with newer programs if set to N.
1150 Disabling this option saves about 7K of kernel size and
1151 possibly 4K of additional runtime pagetable memory.
1154 tristate "Toshiba Laptop support"
1157 This adds a driver to safely access the System Management Mode of
1158 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1159 not work on models with a Phoenix BIOS. The System Management Mode
1160 is used to set the BIOS and power saving options on Toshiba portables.
1162 For information on utilities to make use of this driver see the
1163 Toshiba Linux utilities web site at:
1164 <http://www.buzzard.org.uk/toshiba/>.
1166 Say Y if you intend to run this kernel on a Toshiba portable.
1170 tristate "Dell i8k legacy laptop support"
1172 select SENSORS_DELL_SMM
1174 This option enables legacy /proc/i8k userspace interface in hwmon
1175 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1176 temperature and allows controlling fan speeds of Dell laptops via
1177 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1178 it reports also power and hotkey status. For fan speed control is
1179 needed userspace package i8kutils.
1181 Say Y if you intend to run this kernel on old Dell laptops or want to
1182 use userspace package i8kutils.
1185 config X86_REBOOTFIXUPS
1186 bool "Enable X86 board specific fixups for reboot"
1189 This enables chipset and/or board specific fixups to be done
1190 in order to get reboot to work correctly. This is only needed on
1191 some combinations of hardware and BIOS. The symptom, for which
1192 this config is intended, is when reboot ends with a stalled/hung
1195 Currently, the only fixup is for the Geode machines using
1196 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1198 Say Y if you want to enable the fixup. Currently, it's safe to
1199 enable this option even if you don't need it.
1203 bool "CPU microcode loading support"
1205 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1208 If you say Y here, you will be able to update the microcode on
1209 Intel and AMD processors. The Intel support is for the IA32 family,
1210 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1211 AMD support is for families 0x10 and later. You will obviously need
1212 the actual microcode binary data itself which is not shipped with
1215 The preferred method to load microcode from a detached initrd is described
1216 in Documentation/x86/early-microcode.txt. For that you need to enable
1217 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1218 initrd for microcode blobs.
1220 In addition, you can build-in the microcode into the kernel. For that you
1221 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1222 to the CONFIG_EXTRA_FIRMWARE config option.
1224 config MICROCODE_INTEL
1225 bool "Intel microcode loading support"
1226 depends on MICROCODE
1230 This options enables microcode patch loading support for Intel
1233 For the current Intel microcode data package go to
1234 <https://downloadcenter.intel.com> and search for
1235 'Linux Processor Microcode Data File'.
1237 config MICROCODE_AMD
1238 bool "AMD microcode loading support"
1239 depends on MICROCODE
1242 If you select this option, microcode patch loading support for AMD
1243 processors will be enabled.
1245 config MICROCODE_OLD_INTERFACE
1247 depends on MICROCODE
1250 tristate "/dev/cpu/*/msr - Model-specific register support"
1252 This device gives privileged processes access to the x86
1253 Model-Specific Registers (MSRs). It is a character device with
1254 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1255 MSR accesses are directed to a specific CPU on multi-processor
1259 tristate "/dev/cpu/*/cpuid - CPU information support"
1261 This device gives processes access to the x86 CPUID instruction to
1262 be executed on a specific processor. It is a character device
1263 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1267 prompt "High Memory Support"
1274 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1275 However, the address space of 32-bit x86 processors is only 4
1276 Gigabytes large. That means that, if you have a large amount of
1277 physical memory, not all of it can be "permanently mapped" by the
1278 kernel. The physical memory that's not permanently mapped is called
1281 If you are compiling a kernel which will never run on a machine with
1282 more than 1 Gigabyte total physical RAM, answer "off" here (default
1283 choice and suitable for most users). This will result in a "3GB/1GB"
1284 split: 3GB are mapped so that each process sees a 3GB virtual memory
1285 space and the remaining part of the 4GB virtual memory space is used
1286 by the kernel to permanently map as much physical memory as
1289 If the machine has between 1 and 4 Gigabytes physical RAM, then
1292 If more than 4 Gigabytes is used then answer "64GB" here. This
1293 selection turns Intel PAE (Physical Address Extension) mode on.
1294 PAE implements 3-level paging on IA32 processors. PAE is fully
1295 supported by Linux, PAE mode is implemented on all recent Intel
1296 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1297 then the kernel will not boot on CPUs that don't support PAE!
1299 The actual amount of total physical memory will either be
1300 auto detected or can be forced by using a kernel command line option
1301 such as "mem=256M". (Try "man bootparam" or see the documentation of
1302 your boot loader (lilo or loadlin) about how to pass options to the
1303 kernel at boot time.)
1305 If unsure, say "off".
1310 Select this if you have a 32-bit processor and between 1 and 4
1311 gigabytes of physical RAM.
1318 Select this if you have a 32-bit processor and more than 4
1319 gigabytes of physical RAM.
1324 prompt "Memory split" if EXPERT
1328 Select the desired split between kernel and user memory.
1330 If the address range available to the kernel is less than the
1331 physical memory installed, the remaining memory will be available
1332 as "high memory". Accessing high memory is a little more costly
1333 than low memory, as it needs to be mapped into the kernel first.
1334 Note that increasing the kernel address space limits the range
1335 available to user programs, making the address space there
1336 tighter. Selecting anything other than the default 3G/1G split
1337 will also likely make your kernel incompatible with binary-only
1340 If you are not absolutely sure what you are doing, leave this
1344 bool "3G/1G user/kernel split"
1345 config VMSPLIT_3G_OPT
1347 bool "3G/1G user/kernel split (for full 1G low memory)"
1349 bool "2G/2G user/kernel split"
1350 config VMSPLIT_2G_OPT
1352 bool "2G/2G user/kernel split (for full 2G low memory)"
1354 bool "1G/3G user/kernel split"
1359 default 0xB0000000 if VMSPLIT_3G_OPT
1360 default 0x80000000 if VMSPLIT_2G
1361 default 0x78000000 if VMSPLIT_2G_OPT
1362 default 0x40000000 if VMSPLIT_1G
1368 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1371 bool "PAE (Physical Address Extension) Support"
1372 depends on X86_32 && !HIGHMEM4G
1375 PAE is required for NX support, and furthermore enables
1376 larger swapspace support for non-overcommit purposes. It
1377 has the cost of more pagetable lookup overhead, and also
1378 consumes more pagetable space per process.
1380 config ARCH_PHYS_ADDR_T_64BIT
1382 depends on X86_64 || X86_PAE
1384 config ARCH_DMA_ADDR_T_64BIT
1386 depends on X86_64 || HIGHMEM64G
1388 config X86_DIRECT_GBPAGES
1390 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1392 Certain kernel features effectively disable kernel
1393 linear 1 GB mappings (even if the CPU otherwise
1394 supports them), so don't confuse the user by printing
1395 that we have them enabled.
1397 # Common NUMA Features
1399 bool "Numa Memory Allocation and Scheduler Support"
1401 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1402 default y if X86_BIGSMP
1404 Enable NUMA (Non Uniform Memory Access) support.
1406 The kernel will try to allocate memory used by a CPU on the
1407 local memory controller of the CPU and add some more
1408 NUMA awareness to the kernel.
1410 For 64-bit this is recommended if the system is Intel Core i7
1411 (or later), AMD Opteron, or EM64T NUMA.
1413 For 32-bit this is only needed if you boot a 32-bit
1414 kernel on a 64-bit NUMA platform.
1416 Otherwise, you should say N.
1420 prompt "Old style AMD Opteron NUMA detection"
1421 depends on X86_64 && NUMA && PCI
1423 Enable AMD NUMA node topology detection. You should say Y here if
1424 you have a multi processor AMD system. This uses an old method to
1425 read the NUMA configuration directly from the builtin Northbridge
1426 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1427 which also takes priority if both are compiled in.
1429 config X86_64_ACPI_NUMA
1431 prompt "ACPI NUMA detection"
1432 depends on X86_64 && NUMA && ACPI && PCI
1435 Enable ACPI SRAT based node topology detection.
1437 # Some NUMA nodes have memory ranges that span
1438 # other nodes. Even though a pfn is valid and
1439 # between a node's start and end pfns, it may not
1440 # reside on that node. See memmap_init_zone()
1442 config NODES_SPAN_OTHER_NODES
1444 depends on X86_64_ACPI_NUMA
1447 bool "NUMA emulation"
1450 Enable NUMA emulation. A flat machine will be split
1451 into virtual nodes when booted with "numa=fake=N", where N is the
1452 number of nodes. This is only useful for debugging.
1455 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1457 default "10" if MAXSMP
1458 default "6" if X86_64
1460 depends on NEED_MULTIPLE_NODES
1462 Specify the maximum number of NUMA Nodes available on the target
1463 system. Increases memory reserved to accommodate various tables.
1465 config ARCH_HAVE_MEMORY_PRESENT
1467 depends on X86_32 && DISCONTIGMEM
1469 config NEED_NODE_MEMMAP_SIZE
1471 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1473 config ARCH_FLATMEM_ENABLE
1475 depends on X86_32 && !NUMA
1477 config ARCH_DISCONTIGMEM_ENABLE
1479 depends on NUMA && X86_32
1481 config ARCH_DISCONTIGMEM_DEFAULT
1483 depends on NUMA && X86_32
1485 config ARCH_SPARSEMEM_ENABLE
1487 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1488 select SPARSEMEM_STATIC if X86_32
1489 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1491 config ARCH_SPARSEMEM_DEFAULT
1495 config ARCH_SELECT_MEMORY_MODEL
1497 depends on ARCH_SPARSEMEM_ENABLE
1499 config ARCH_MEMORY_PROBE
1500 bool "Enable sysfs memory/probe interface"
1501 depends on X86_64 && MEMORY_HOTPLUG
1503 This option enables a sysfs memory/probe interface for testing.
1504 See Documentation/memory-hotplug.txt for more information.
1505 If you are unsure how to answer this question, answer N.
1507 config ARCH_PROC_KCORE_TEXT
1509 depends on X86_64 && PROC_KCORE
1511 config ILLEGAL_POINTER_VALUE
1514 default 0xdead000000000000 if X86_64
1518 config X86_PMEM_LEGACY_DEVICE
1521 config X86_PMEM_LEGACY
1522 tristate "Support non-standard NVDIMMs and ADR protected memory"
1523 depends on PHYS_ADDR_T_64BIT
1525 select X86_PMEM_LEGACY_DEVICE
1528 Treat memory marked using the non-standard e820 type of 12 as used
1529 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1530 The kernel will offer these regions to the 'pmem' driver so
1531 they can be used for persistent storage.
1536 bool "Allocate 3rd-level pagetables from highmem"
1539 The VM uses one page table entry for each page of physical memory.
1540 For systems with a lot of RAM, this can be wasteful of precious
1541 low memory. Setting this option will put user-space page table
1542 entries in high memory.
1544 config X86_CHECK_BIOS_CORRUPTION
1545 bool "Check for low memory corruption"
1547 Periodically check for memory corruption in low memory, which
1548 is suspected to be caused by BIOS. Even when enabled in the
1549 configuration, it is disabled at runtime. Enable it by
1550 setting "memory_corruption_check=1" on the kernel command
1551 line. By default it scans the low 64k of memory every 60
1552 seconds; see the memory_corruption_check_size and
1553 memory_corruption_check_period parameters in
1554 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1556 When enabled with the default parameters, this option has
1557 almost no overhead, as it reserves a relatively small amount
1558 of memory and scans it infrequently. It both detects corruption
1559 and prevents it from affecting the running system.
1561 It is, however, intended as a diagnostic tool; if repeatable
1562 BIOS-originated corruption always affects the same memory,
1563 you can use memmap= to prevent the kernel from using that
1566 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1567 bool "Set the default setting of memory_corruption_check"
1568 depends on X86_CHECK_BIOS_CORRUPTION
1571 Set whether the default state of memory_corruption_check is
1574 config X86_RESERVE_LOW
1575 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1579 Specify the amount of low memory to reserve for the BIOS.
1581 The first page contains BIOS data structures that the kernel
1582 must not use, so that page must always be reserved.
1584 By default we reserve the first 64K of physical RAM, as a
1585 number of BIOSes are known to corrupt that memory range
1586 during events such as suspend/resume or monitor cable
1587 insertion, so it must not be used by the kernel.
1589 You can set this to 4 if you are absolutely sure that you
1590 trust the BIOS to get all its memory reservations and usages
1591 right. If you know your BIOS have problems beyond the
1592 default 64K area, you can set this to 640 to avoid using the
1593 entire low memory range.
1595 If you have doubts about the BIOS (e.g. suspend/resume does
1596 not work or there's kernel crashes after certain hardware
1597 hotplug events) then you might want to enable
1598 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1599 typical corruption patterns.
1601 Leave this to the default value of 64 if you are unsure.
1603 config MATH_EMULATION
1605 depends on MODIFY_LDT_SYSCALL
1606 prompt "Math emulation" if X86_32
1608 Linux can emulate a math coprocessor (used for floating point
1609 operations) if you don't have one. 486DX and Pentium processors have
1610 a math coprocessor built in, 486SX and 386 do not, unless you added
1611 a 487DX or 387, respectively. (The messages during boot time can
1612 give you some hints here ["man dmesg"].) Everyone needs either a
1613 coprocessor or this emulation.
1615 If you don't have a math coprocessor, you need to say Y here; if you
1616 say Y here even though you have a coprocessor, the coprocessor will
1617 be used nevertheless. (This behavior can be changed with the kernel
1618 command line option "no387", which comes handy if your coprocessor
1619 is broken. Try "man bootparam" or see the documentation of your boot
1620 loader (lilo or loadlin) about how to pass options to the kernel at
1621 boot time.) This means that it is a good idea to say Y here if you
1622 intend to use this kernel on different machines.
1624 More information about the internals of the Linux math coprocessor
1625 emulation can be found in <file:arch/x86/math-emu/README>.
1627 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1628 kernel, it won't hurt.
1632 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1634 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1635 the Memory Type Range Registers (MTRRs) may be used to control
1636 processor access to memory ranges. This is most useful if you have
1637 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1638 allows bus write transfers to be combined into a larger transfer
1639 before bursting over the PCI/AGP bus. This can increase performance
1640 of image write operations 2.5 times or more. Saying Y here creates a
1641 /proc/mtrr file which may be used to manipulate your processor's
1642 MTRRs. Typically the X server should use this.
1644 This code has a reasonably generic interface so that similar
1645 control registers on other processors can be easily supported
1648 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1649 Registers (ARRs) which provide a similar functionality to MTRRs. For
1650 these, the ARRs are used to emulate the MTRRs.
1651 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1652 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1653 write-combining. All of these processors are supported by this code
1654 and it makes sense to say Y here if you have one of them.
1656 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1657 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1658 can lead to all sorts of problems, so it's good to say Y here.
1660 You can safely say Y even if your machine doesn't have MTRRs, you'll
1661 just add about 9 KB to your kernel.
1663 See <file:Documentation/x86/mtrr.txt> for more information.
1665 config MTRR_SANITIZER
1667 prompt "MTRR cleanup support"
1670 Convert MTRR layout from continuous to discrete, so X drivers can
1671 add writeback entries.
1673 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1674 The largest mtrr entry size for a continuous block can be set with
1679 config MTRR_SANITIZER_ENABLE_DEFAULT
1680 int "MTRR cleanup enable value (0-1)"
1683 depends on MTRR_SANITIZER
1685 Enable mtrr cleanup default value
1687 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1688 int "MTRR cleanup spare reg num (0-7)"
1691 depends on MTRR_SANITIZER
1693 mtrr cleanup spare entries default, it can be changed via
1694 mtrr_spare_reg_nr=N on the kernel command line.
1698 prompt "x86 PAT support" if EXPERT
1701 Use PAT attributes to setup page level cache control.
1703 PATs are the modern equivalents of MTRRs and are much more
1704 flexible than MTRRs.
1706 Say N here if you see bootup problems (boot crash, boot hang,
1707 spontaneous reboots) or a non-working video driver.
1711 config ARCH_USES_PG_UNCACHED
1717 prompt "x86 architectural random number generator" if EXPERT
1719 Enable the x86 architectural RDRAND instruction
1720 (Intel Bull Mountain technology) to generate random numbers.
1721 If supported, this is a high bandwidth, cryptographically
1722 secure hardware random number generator.
1726 prompt "Supervisor Mode Access Prevention" if EXPERT
1728 Supervisor Mode Access Prevention (SMAP) is a security
1729 feature in newer Intel processors. There is a small
1730 performance cost if this enabled and turned on; there is
1731 also a small increase in the kernel size if this is enabled.
1735 config X86_INTEL_MPX
1736 prompt "Intel MPX (Memory Protection Extensions)"
1738 depends on CPU_SUP_INTEL
1740 MPX provides hardware features that can be used in
1741 conjunction with compiler-instrumented code to check
1742 memory references. It is designed to detect buffer
1743 overflow or underflow bugs.
1745 This option enables running applications which are
1746 instrumented or otherwise use MPX. It does not use MPX
1747 itself inside the kernel or to protect the kernel
1748 against bad memory references.
1750 Enabling this option will make the kernel larger:
1751 ~8k of kernel text and 36 bytes of data on a 64-bit
1752 defconfig. It adds a long to the 'mm_struct' which
1753 will increase the kernel memory overhead of each
1754 process and adds some branches to paths used during
1755 exec() and munmap().
1757 For details, see Documentation/x86/intel_mpx.txt
1761 config X86_INTEL_MEMORY_PROTECTION_KEYS
1762 prompt "Intel Memory Protection Keys"
1764 # Note: only available in 64-bit mode
1765 depends on CPU_SUP_INTEL && X86_64
1766 select ARCH_USES_HIGH_VMA_FLAGS
1767 select ARCH_HAS_PKEYS
1769 Memory Protection Keys provides a mechanism for enforcing
1770 page-based protections, but without requiring modification of the
1771 page tables when an application changes protection domains.
1773 For details, see Documentation/x86/protection-keys.txt
1778 bool "EFI runtime service support"
1781 select EFI_RUNTIME_WRAPPERS
1783 This enables the kernel to use EFI runtime services that are
1784 available (such as the EFI variable services).
1786 This option is only useful on systems that have EFI firmware.
1787 In addition, you should use the latest ELILO loader available
1788 at <http://elilo.sourceforge.net> in order to take advantage
1789 of EFI runtime services. However, even with this option, the
1790 resultant kernel should continue to boot on existing non-EFI
1794 bool "EFI stub support"
1795 depends on EFI && !X86_USE_3DNOW
1798 This kernel feature allows a bzImage to be loaded directly
1799 by EFI firmware without the use of a bootloader.
1801 See Documentation/efi-stub.txt for more information.
1804 bool "EFI mixed-mode support"
1805 depends on EFI_STUB && X86_64
1807 Enabling this feature allows a 64-bit kernel to be booted
1808 on a 32-bit firmware, provided that your CPU supports 64-bit
1811 Note that it is not possible to boot a mixed-mode enabled
1812 kernel via the EFI boot stub - a bootloader that supports
1813 the EFI handover protocol must be used.
1819 prompt "Enable seccomp to safely compute untrusted bytecode"
1821 This kernel feature is useful for number crunching applications
1822 that may need to compute untrusted bytecode during their
1823 execution. By using pipes or other transports made available to
1824 the process as file descriptors supporting the read/write
1825 syscalls, it's possible to isolate those applications in
1826 their own address space using seccomp. Once seccomp is
1827 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1828 and the task is only allowed to execute a few safe syscalls
1829 defined by each seccomp mode.
1831 If unsure, say Y. Only embedded should say N here.
1833 source kernel/Kconfig.hz
1836 bool "kexec system call"
1839 kexec is a system call that implements the ability to shutdown your
1840 current kernel, and to start another kernel. It is like a reboot
1841 but it is independent of the system firmware. And like a reboot
1842 you can start any kernel with it, not just Linux.
1844 The name comes from the similarity to the exec system call.
1846 It is an ongoing process to be certain the hardware in a machine
1847 is properly shutdown, so do not be surprised if this code does not
1848 initially work for you. As of this writing the exact hardware
1849 interface is strongly in flux, so no good recommendation can be
1853 bool "kexec file based system call"
1858 depends on CRYPTO_SHA256=y
1860 This is new version of kexec system call. This system call is
1861 file based and takes file descriptors as system call argument
1862 for kernel and initramfs as opposed to list of segments as
1863 accepted by previous system call.
1865 config KEXEC_VERIFY_SIG
1866 bool "Verify kernel signature during kexec_file_load() syscall"
1867 depends on KEXEC_FILE
1869 This option makes kernel signature verification mandatory for
1870 the kexec_file_load() syscall.
1872 In addition to that option, you need to enable signature
1873 verification for the corresponding kernel image type being
1874 loaded in order for this to work.
1876 config KEXEC_BZIMAGE_VERIFY_SIG
1877 bool "Enable bzImage signature verification support"
1878 depends on KEXEC_VERIFY_SIG
1879 depends on SIGNED_PE_FILE_VERIFICATION
1880 select SYSTEM_TRUSTED_KEYRING
1882 Enable bzImage signature verification support.
1885 bool "kernel crash dumps"
1886 depends on X86_64 || (X86_32 && HIGHMEM)
1888 Generate crash dump after being started by kexec.
1889 This should be normally only set in special crash dump kernels
1890 which are loaded in the main kernel with kexec-tools into
1891 a specially reserved region and then later executed after
1892 a crash by kdump/kexec. The crash dump kernel must be compiled
1893 to a memory address not used by the main kernel or BIOS using
1894 PHYSICAL_START, or it must be built as a relocatable image
1895 (CONFIG_RELOCATABLE=y).
1896 For more details see Documentation/kdump/kdump.txt
1900 depends on KEXEC && HIBERNATION
1902 Jump between original kernel and kexeced kernel and invoke
1903 code in physical address mode via KEXEC
1905 config PHYSICAL_START
1906 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1909 This gives the physical address where the kernel is loaded.
1911 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1912 bzImage will decompress itself to above physical address and
1913 run from there. Otherwise, bzImage will run from the address where
1914 it has been loaded by the boot loader and will ignore above physical
1917 In normal kdump cases one does not have to set/change this option
1918 as now bzImage can be compiled as a completely relocatable image
1919 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1920 address. This option is mainly useful for the folks who don't want
1921 to use a bzImage for capturing the crash dump and want to use a
1922 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1923 to be specifically compiled to run from a specific memory area
1924 (normally a reserved region) and this option comes handy.
1926 So if you are using bzImage for capturing the crash dump,
1927 leave the value here unchanged to 0x1000000 and set
1928 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1929 for capturing the crash dump change this value to start of
1930 the reserved region. In other words, it can be set based on
1931 the "X" value as specified in the "crashkernel=YM@XM"
1932 command line boot parameter passed to the panic-ed
1933 kernel. Please take a look at Documentation/kdump/kdump.txt
1934 for more details about crash dumps.
1936 Usage of bzImage for capturing the crash dump is recommended as
1937 one does not have to build two kernels. Same kernel can be used
1938 as production kernel and capture kernel. Above option should have
1939 gone away after relocatable bzImage support is introduced. But it
1940 is present because there are users out there who continue to use
1941 vmlinux for dump capture. This option should go away down the
1944 Don't change this unless you know what you are doing.
1947 bool "Build a relocatable kernel"
1950 This builds a kernel image that retains relocation information
1951 so it can be loaded someplace besides the default 1MB.
1952 The relocations tend to make the kernel binary about 10% larger,
1953 but are discarded at runtime.
1955 One use is for the kexec on panic case where the recovery kernel
1956 must live at a different physical address than the primary
1959 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1960 it has been loaded at and the compile time physical address
1961 (CONFIG_PHYSICAL_START) is used as the minimum location.
1963 config RANDOMIZE_BASE
1964 bool "Randomize the address of the kernel image (KASLR)"
1965 depends on RELOCATABLE
1968 In support of Kernel Address Space Layout Randomization (KASLR),
1969 this randomizes the physical address at which the kernel image
1970 is decompressed and the virtual address where the kernel
1971 image is mapped, as a security feature that deters exploit
1972 attempts relying on knowledge of the location of kernel
1975 On 64-bit, the kernel physical and virtual addresses are
1976 randomized separately. The physical address will be anywhere
1977 between 16MB and the top of physical memory (up to 64TB). The
1978 virtual address will be randomized from 16MB up to 1GB (9 bits
1979 of entropy). Note that this also reduces the memory space
1980 available to kernel modules from 1.5GB to 1GB.
1982 On 32-bit, the kernel physical and virtual addresses are
1983 randomized together. They will be randomized from 16MB up to
1984 512MB (8 bits of entropy).
1986 Entropy is generated using the RDRAND instruction if it is
1987 supported. If RDTSC is supported, its value is mixed into
1988 the entropy pool as well. If neither RDRAND nor RDTSC are
1989 supported, then entropy is read from the i8254 timer. The
1990 usable entropy is limited by the kernel being built using
1991 2GB addressing, and that PHYSICAL_ALIGN must be at a
1992 minimum of 2MB. As a result, only 10 bits of entropy are
1993 theoretically possible, but the implementations are further
1994 limited due to memory layouts.
1996 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1997 time. To enable it, boot with "kaslr" on the kernel command
1998 line (which will also disable hibernation).
2002 # Relocation on x86 needs some additional build support
2003 config X86_NEED_RELOCS
2005 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2007 config PHYSICAL_ALIGN
2008 hex "Alignment value to which kernel should be aligned"
2010 range 0x2000 0x1000000 if X86_32
2011 range 0x200000 0x1000000 if X86_64
2013 This value puts the alignment restrictions on physical address
2014 where kernel is loaded and run from. Kernel is compiled for an
2015 address which meets above alignment restriction.
2017 If bootloader loads the kernel at a non-aligned address and
2018 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2019 address aligned to above value and run from there.
2021 If bootloader loads the kernel at a non-aligned address and
2022 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2023 load address and decompress itself to the address it has been
2024 compiled for and run from there. The address for which kernel is
2025 compiled already meets above alignment restrictions. Hence the
2026 end result is that kernel runs from a physical address meeting
2027 above alignment restrictions.
2029 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2030 this value must be a multiple of 0x200000.
2032 Don't change this unless you know what you are doing.
2034 config RANDOMIZE_MEMORY
2035 bool "Randomize the kernel memory sections"
2037 depends on RANDOMIZE_BASE
2038 default RANDOMIZE_BASE
2040 Randomizes the base virtual address of kernel memory sections
2041 (physical memory mapping, vmalloc & vmemmap). This security feature
2042 makes exploits relying on predictable memory locations less reliable.
2044 The order of allocations remains unchanged. Entropy is generated in
2045 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2046 configuration have in average 30,000 different possible virtual
2047 addresses for each memory section.
2051 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2052 hex "Physical memory mapping padding" if EXPERT
2053 depends on RANDOMIZE_MEMORY
2054 default "0xa" if MEMORY_HOTPLUG
2056 range 0x1 0x40 if MEMORY_HOTPLUG
2059 Define the padding in terabytes added to the existing physical
2060 memory size during kernel memory randomization. It is useful
2061 for memory hotplug support but reduces the entropy available for
2062 address randomization.
2064 If unsure, leave at the default value.
2067 bool "Support for hot-pluggable CPUs"
2070 Say Y here to allow turning CPUs off and on. CPUs can be
2071 controlled through /sys/devices/system/cpu.
2072 ( Note: power management support will enable this option
2073 automatically on SMP systems. )
2074 Say N if you want to disable CPU hotplug.
2076 config BOOTPARAM_HOTPLUG_CPU0
2077 bool "Set default setting of cpu0_hotpluggable"
2079 depends on HOTPLUG_CPU
2081 Set whether default state of cpu0_hotpluggable is on or off.
2083 Say Y here to enable CPU0 hotplug by default. If this switch
2084 is turned on, there is no need to give cpu0_hotplug kernel
2085 parameter and the CPU0 hotplug feature is enabled by default.
2087 Please note: there are two known CPU0 dependencies if you want
2088 to enable the CPU0 hotplug feature either by this switch or by
2089 cpu0_hotplug kernel parameter.
2091 First, resume from hibernate or suspend always starts from CPU0.
2092 So hibernate and suspend are prevented if CPU0 is offline.
2094 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2095 offline if any interrupt can not migrate out of CPU0. There may
2096 be other CPU0 dependencies.
2098 Please make sure the dependencies are under your control before
2099 you enable this feature.
2101 Say N if you don't want to enable CPU0 hotplug feature by default.
2102 You still can enable the CPU0 hotplug feature at boot by kernel
2103 parameter cpu0_hotplug.
2105 config DEBUG_HOTPLUG_CPU0
2107 prompt "Debug CPU0 hotplug"
2108 depends on HOTPLUG_CPU
2110 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2111 soon as possible and boots up userspace with CPU0 offlined. User
2112 can online CPU0 back after boot time.
2114 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2115 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2116 compilation or giving cpu0_hotplug kernel parameter at boot.
2122 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2123 depends on COMPAT_32
2125 Certain buggy versions of glibc will crash if they are
2126 presented with a 32-bit vDSO that is not mapped at the address
2127 indicated in its segment table.
2129 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2130 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2131 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2132 the only released version with the bug, but OpenSUSE 9
2133 contains a buggy "glibc 2.3.2".
2135 The symptom of the bug is that everything crashes on startup, saying:
2136 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2138 Saying Y here changes the default value of the vdso32 boot
2139 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2140 This works around the glibc bug but hurts performance.
2142 If unsure, say N: if you are compiling your own kernel, you
2143 are unlikely to be using a buggy version of glibc.
2146 prompt "vsyscall table for legacy applications"
2148 default LEGACY_VSYSCALL_EMULATE
2150 Legacy user code that does not know how to find the vDSO expects
2151 to be able to issue three syscalls by calling fixed addresses in
2152 kernel space. Since this location is not randomized with ASLR,
2153 it can be used to assist security vulnerability exploitation.
2155 This setting can be changed at boot time via the kernel command
2156 line parameter vsyscall=[native|emulate|none].
2158 On a system with recent enough glibc (2.14 or newer) and no
2159 static binaries, you can say None without a performance penalty
2160 to improve security.
2162 If unsure, select "Emulate".
2164 config LEGACY_VSYSCALL_NATIVE
2167 Actual executable code is located in the fixed vsyscall
2168 address mapping, implementing time() efficiently. Since
2169 this makes the mapping executable, it can be used during
2170 security vulnerability exploitation (traditionally as
2171 ROP gadgets). This configuration is not recommended.
2173 config LEGACY_VSYSCALL_EMULATE
2176 The kernel traps and emulates calls into the fixed
2177 vsyscall address mapping. This makes the mapping
2178 non-executable, but it still contains known contents,
2179 which could be used in certain rare security vulnerability
2180 exploits. This configuration is recommended when userspace
2181 still uses the vsyscall area.
2183 config LEGACY_VSYSCALL_NONE
2186 There will be no vsyscall mapping at all. This will
2187 eliminate any risk of ASLR bypass due to the vsyscall
2188 fixed address mapping. Attempts to use the vsyscalls
2189 will be reported to dmesg, so that either old or
2190 malicious userspace programs can be identified.
2195 bool "Built-in kernel command line"
2197 Allow for specifying boot arguments to the kernel at
2198 build time. On some systems (e.g. embedded ones), it is
2199 necessary or convenient to provide some or all of the
2200 kernel boot arguments with the kernel itself (that is,
2201 to not rely on the boot loader to provide them.)
2203 To compile command line arguments into the kernel,
2204 set this option to 'Y', then fill in the
2205 boot arguments in CONFIG_CMDLINE.
2207 Systems with fully functional boot loaders (i.e. non-embedded)
2208 should leave this option set to 'N'.
2211 string "Built-in kernel command string"
2212 depends on CMDLINE_BOOL
2215 Enter arguments here that should be compiled into the kernel
2216 image and used at boot time. If the boot loader provides a
2217 command line at boot time, it is appended to this string to
2218 form the full kernel command line, when the system boots.
2220 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2221 change this behavior.
2223 In most cases, the command line (whether built-in or provided
2224 by the boot loader) should specify the device for the root
2227 config CMDLINE_OVERRIDE
2228 bool "Built-in command line overrides boot loader arguments"
2229 depends on CMDLINE_BOOL
2231 Set this option to 'Y' to have the kernel ignore the boot loader
2232 command line, and use ONLY the built-in command line.
2234 This is used to work around broken boot loaders. This should
2235 be set to 'N' under normal conditions.
2237 config MODIFY_LDT_SYSCALL
2238 bool "Enable the LDT (local descriptor table)" if EXPERT
2241 Linux can allow user programs to install a per-process x86
2242 Local Descriptor Table (LDT) using the modify_ldt(2) system
2243 call. This is required to run 16-bit or segmented code such as
2244 DOSEMU or some Wine programs. It is also used by some very old
2245 threading libraries.
2247 Enabling this feature adds a small amount of overhead to
2248 context switches and increases the low-level kernel attack
2249 surface. Disabling it removes the modify_ldt(2) system call.
2251 Saying 'N' here may make sense for embedded or server kernels.
2253 source "kernel/livepatch/Kconfig"
2257 config ARCH_ENABLE_MEMORY_HOTPLUG
2259 depends on X86_64 || (X86_32 && HIGHMEM)
2261 config ARCH_ENABLE_MEMORY_HOTREMOVE
2263 depends on MEMORY_HOTPLUG
2265 config USE_PERCPU_NUMA_NODE_ID
2269 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2271 depends on X86_64 || X86_PAE
2273 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2275 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2277 menu "Power management and ACPI options"
2279 config ARCH_HIBERNATION_HEADER
2281 depends on X86_64 && HIBERNATION
2283 source "kernel/power/Kconfig"
2285 source "drivers/acpi/Kconfig"
2287 source "drivers/sfi/Kconfig"
2294 tristate "APM (Advanced Power Management) BIOS support"
2295 depends on X86_32 && PM_SLEEP
2297 APM is a BIOS specification for saving power using several different
2298 techniques. This is mostly useful for battery powered laptops with
2299 APM compliant BIOSes. If you say Y here, the system time will be
2300 reset after a RESUME operation, the /proc/apm device will provide
2301 battery status information, and user-space programs will receive
2302 notification of APM "events" (e.g. battery status change).
2304 If you select "Y" here, you can disable actual use of the APM
2305 BIOS by passing the "apm=off" option to the kernel at boot time.
2307 Note that the APM support is almost completely disabled for
2308 machines with more than one CPU.
2310 In order to use APM, you will need supporting software. For location
2311 and more information, read <file:Documentation/power/apm-acpi.txt>
2312 and the Battery Powered Linux mini-HOWTO, available from
2313 <http://www.tldp.org/docs.html#howto>.
2315 This driver does not spin down disk drives (see the hdparm(8)
2316 manpage ("man 8 hdparm") for that), and it doesn't turn off
2317 VESA-compliant "green" monitors.
2319 This driver does not support the TI 4000M TravelMate and the ACER
2320 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2321 desktop machines also don't have compliant BIOSes, and this driver
2322 may cause those machines to panic during the boot phase.
2324 Generally, if you don't have a battery in your machine, there isn't
2325 much point in using this driver and you should say N. If you get
2326 random kernel OOPSes or reboots that don't seem to be related to
2327 anything, try disabling/enabling this option (or disabling/enabling
2330 Some other things you should try when experiencing seemingly random,
2333 1) make sure that you have enough swap space and that it is
2335 2) pass the "no-hlt" option to the kernel
2336 3) switch on floating point emulation in the kernel and pass
2337 the "no387" option to the kernel
2338 4) pass the "floppy=nodma" option to the kernel
2339 5) pass the "mem=4M" option to the kernel (thereby disabling
2340 all but the first 4 MB of RAM)
2341 6) make sure that the CPU is not over clocked.
2342 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2343 8) disable the cache from your BIOS settings
2344 9) install a fan for the video card or exchange video RAM
2345 10) install a better fan for the CPU
2346 11) exchange RAM chips
2347 12) exchange the motherboard.
2349 To compile this driver as a module, choose M here: the
2350 module will be called apm.
2354 config APM_IGNORE_USER_SUSPEND
2355 bool "Ignore USER SUSPEND"
2357 This option will ignore USER SUSPEND requests. On machines with a
2358 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2359 series notebooks, it is necessary to say Y because of a BIOS bug.
2361 config APM_DO_ENABLE
2362 bool "Enable PM at boot time"
2364 Enable APM features at boot time. From page 36 of the APM BIOS
2365 specification: "When disabled, the APM BIOS does not automatically
2366 power manage devices, enter the Standby State, enter the Suspend
2367 State, or take power saving steps in response to CPU Idle calls."
2368 This driver will make CPU Idle calls when Linux is idle (unless this
2369 feature is turned off -- see "Do CPU IDLE calls", below). This
2370 should always save battery power, but more complicated APM features
2371 will be dependent on your BIOS implementation. You may need to turn
2372 this option off if your computer hangs at boot time when using APM
2373 support, or if it beeps continuously instead of suspending. Turn
2374 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2375 T400CDT. This is off by default since most machines do fine without
2380 bool "Make CPU Idle calls when idle"
2382 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2383 On some machines, this can activate improved power savings, such as
2384 a slowed CPU clock rate, when the machine is idle. These idle calls
2385 are made after the idle loop has run for some length of time (e.g.,
2386 333 mS). On some machines, this will cause a hang at boot time or
2387 whenever the CPU becomes idle. (On machines with more than one CPU,
2388 this option does nothing.)
2390 config APM_DISPLAY_BLANK
2391 bool "Enable console blanking using APM"
2393 Enable console blanking using the APM. Some laptops can use this to
2394 turn off the LCD backlight when the screen blanker of the Linux
2395 virtual console blanks the screen. Note that this is only used by
2396 the virtual console screen blanker, and won't turn off the backlight
2397 when using the X Window system. This also doesn't have anything to
2398 do with your VESA-compliant power-saving monitor. Further, this
2399 option doesn't work for all laptops -- it might not turn off your
2400 backlight at all, or it might print a lot of errors to the console,
2401 especially if you are using gpm.
2403 config APM_ALLOW_INTS
2404 bool "Allow interrupts during APM BIOS calls"
2406 Normally we disable external interrupts while we are making calls to
2407 the APM BIOS as a measure to lessen the effects of a badly behaving
2408 BIOS implementation. The BIOS should reenable interrupts if it
2409 needs to. Unfortunately, some BIOSes do not -- especially those in
2410 many of the newer IBM Thinkpads. If you experience hangs when you
2411 suspend, try setting this to Y. Otherwise, say N.
2415 source "drivers/cpufreq/Kconfig"
2417 source "drivers/cpuidle/Kconfig"
2419 source "drivers/idle/Kconfig"
2424 menu "Bus options (PCI etc.)"
2430 Find out whether you have a PCI motherboard. PCI is the name of a
2431 bus system, i.e. the way the CPU talks to the other stuff inside
2432 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2433 VESA. If you have PCI, say Y, otherwise N.
2436 prompt "PCI access mode"
2437 depends on X86_32 && PCI
2440 On PCI systems, the BIOS can be used to detect the PCI devices and
2441 determine their configuration. However, some old PCI motherboards
2442 have BIOS bugs and may crash if this is done. Also, some embedded
2443 PCI-based systems don't have any BIOS at all. Linux can also try to
2444 detect the PCI hardware directly without using the BIOS.
2446 With this option, you can specify how Linux should detect the
2447 PCI devices. If you choose "BIOS", the BIOS will be used,
2448 if you choose "Direct", the BIOS won't be used, and if you
2449 choose "MMConfig", then PCI Express MMCONFIG will be used.
2450 If you choose "Any", the kernel will try MMCONFIG, then the
2451 direct access method and falls back to the BIOS if that doesn't
2452 work. If unsure, go with the default, which is "Any".
2457 config PCI_GOMMCONFIG
2474 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2476 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2479 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2483 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2487 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2491 depends on PCI && XEN
2499 bool "Support mmconfig PCI config space access"
2500 depends on X86_64 && PCI && ACPI
2502 config PCI_CNB20LE_QUIRK
2503 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2506 Read the PCI windows out of the CNB20LE host bridge. This allows
2507 PCI hotplug to work on systems with the CNB20LE chipset which do
2510 There's no public spec for this chipset, and this functionality
2511 is known to be incomplete.
2513 You should say N unless you know you need this.
2515 source "drivers/pci/Kconfig"
2518 bool "ISA-style bus support on modern systems" if EXPERT
2521 Enables ISA-style drivers on modern systems. This is necessary to
2522 support PC/104 devices on X86_64 platforms.
2526 # x86_64 have no ISA slots, but can have ISA-style DMA.
2528 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2531 Enables ISA-style DMA support for devices requiring such controllers.
2539 Find out whether you have ISA slots on your motherboard. ISA is the
2540 name of a bus system, i.e. the way the CPU talks to the other stuff
2541 inside your box. Other bus systems are PCI, EISA, MicroChannel
2542 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2543 newer boards don't support it. If you have ISA, say Y, otherwise N.
2549 The Extended Industry Standard Architecture (EISA) bus was
2550 developed as an open alternative to the IBM MicroChannel bus.
2552 The EISA bus provided some of the features of the IBM MicroChannel
2553 bus while maintaining backward compatibility with cards made for
2554 the older ISA bus. The EISA bus saw limited use between 1988 and
2555 1995 when it was made obsolete by the PCI bus.
2557 Say Y here if you are building a kernel for an EISA-based machine.
2561 source "drivers/eisa/Kconfig"
2564 tristate "NatSemi SCx200 support"
2566 This provides basic support for National Semiconductor's
2567 (now AMD's) Geode processors. The driver probes for the
2568 PCI-IDs of several on-chip devices, so its a good dependency
2569 for other scx200_* drivers.
2571 If compiled as a module, the driver is named scx200.
2573 config SCx200HR_TIMER
2574 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2578 This driver provides a clocksource built upon the on-chip
2579 27MHz high-resolution timer. Its also a workaround for
2580 NSC Geode SC-1100's buggy TSC, which loses time when the
2581 processor goes idle (as is done by the scheduler). The
2582 other workaround is idle=poll boot option.
2585 bool "One Laptop Per Child support"
2592 Add support for detecting the unique features of the OLPC
2596 bool "OLPC XO-1 Power Management"
2597 depends on OLPC && MFD_CS5535 && PM_SLEEP
2600 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2603 bool "OLPC XO-1 Real Time Clock"
2604 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2606 Add support for the XO-1 real time clock, which can be used as a
2607 programmable wakeup source.
2610 bool "OLPC XO-1 SCI extras"
2611 depends on OLPC && OLPC_XO1_PM
2617 Add support for SCI-based features of the OLPC XO-1 laptop:
2618 - EC-driven system wakeups
2622 - AC adapter status updates
2623 - Battery status updates
2625 config OLPC_XO15_SCI
2626 bool "OLPC XO-1.5 SCI extras"
2627 depends on OLPC && ACPI
2630 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2631 - EC-driven system wakeups
2632 - AC adapter status updates
2633 - Battery status updates
2636 bool "PCEngines ALIX System Support (LED setup)"
2639 This option enables system support for the PCEngines ALIX.
2640 At present this just sets up LEDs for GPIO control on
2641 ALIX2/3/6 boards. However, other system specific setup should
2644 Note: You must still enable the drivers for GPIO and LED support
2645 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2647 Note: You have to set alix.force=1 for boards with Award BIOS.
2650 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2653 This option enables system support for the Soekris Engineering net5501.
2656 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2660 This option enables system support for the Traverse Technologies GEOS.
2663 bool "Technologic Systems TS-5500 platform support"
2665 select CHECK_SIGNATURE
2669 This option enables system support for the Technologic Systems TS-5500.
2675 depends on CPU_SUP_AMD && PCI
2677 source "drivers/pcmcia/Kconfig"
2680 tristate "RapidIO support"
2684 If enabled this option will include drivers and the core
2685 infrastructure code to support RapidIO interconnect devices.
2687 source "drivers/rapidio/Kconfig"
2690 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2692 Firmwares often provide initial graphics framebuffers so the BIOS,
2693 bootloader or kernel can show basic video-output during boot for
2694 user-guidance and debugging. Historically, x86 used the VESA BIOS
2695 Extensions and EFI-framebuffers for this, which are mostly limited
2697 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2698 framebuffers so the new generic system-framebuffer drivers can be
2699 used on x86. If the framebuffer is not compatible with the generic
2700 modes, it is adverticed as fallback platform framebuffer so legacy
2701 drivers like efifb, vesafb and uvesafb can pick it up.
2702 If this option is not selected, all system framebuffers are always
2703 marked as fallback platform framebuffers as usual.
2705 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2706 not be able to pick up generic system framebuffers if this option
2707 is selected. You are highly encouraged to enable simplefb as
2708 replacement if you select this option. simplefb can correctly deal
2709 with generic system framebuffers. But you should still keep vesafb
2710 and others enabled as fallback if a system framebuffer is
2711 incompatible with simplefb.
2718 menu "Executable file formats / Emulations"
2720 source "fs/Kconfig.binfmt"
2722 config IA32_EMULATION
2723 bool "IA32 Emulation"
2725 select ARCH_WANT_OLD_COMPAT_IPC
2727 select COMPAT_BINFMT_ELF
2728 select COMPAT_OLD_SIGACTION
2730 Include code to run legacy 32-bit programs under a
2731 64-bit kernel. You should likely turn this on, unless you're
2732 100% sure that you don't have any 32-bit programs left.
2735 tristate "IA32 a.out support"
2736 depends on IA32_EMULATION
2738 Support old a.out binaries in the 32bit emulation.
2741 bool "x32 ABI for 64-bit mode"
2744 Include code to run binaries for the x32 native 32-bit ABI
2745 for 64-bit processors. An x32 process gets access to the
2746 full 64-bit register file and wide data path while leaving
2747 pointers at 32 bits for smaller memory footprint.
2749 You will need a recent binutils (2.22 or later) with
2750 elf32_x86_64 support enabled to compile a kernel with this
2755 depends on IA32_EMULATION || X86_32
2757 select OLD_SIGSUSPEND3
2761 depends on IA32_EMULATION || X86_X32
2764 config COMPAT_FOR_U64_ALIGNMENT
2767 config SYSVIPC_COMPAT
2779 config HAVE_ATOMIC_IOMAP
2783 config X86_DEV_DMA_OPS
2785 depends on X86_64 || STA2X11
2787 config X86_DMA_REMAP
2795 source "net/Kconfig"
2797 source "drivers/Kconfig"
2799 source "drivers/firmware/Kconfig"
2803 source "arch/x86/Kconfig.debug"
2805 source "security/Kconfig"
2807 source "crypto/Kconfig"
2809 source "arch/x86/kvm/Kconfig"
2811 source "lib/Kconfig"