3 bool "64-bit kernel" if ARCH = "x86"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
12 # Options that are inherently 32-bit kernel only:
13 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLONE_BACKWARDS
17 select HAVE_GENERIC_DMA_COHERENT
18 select MODULES_USE_ELF_REL
24 # Options that are inherently 64-bit kernel only:
25 select ARCH_HAS_GIGANTIC_PAGE
26 select ARCH_SUPPORTS_INT128
27 select ARCH_USE_CMPXCHG_LOCKREF
28 select HAVE_ARCH_SOFT_DIRTY
29 select MODULES_USE_ELF_RELA
30 select X86_DEV_DMA_OPS
35 # ( Note that options that are marked 'if X86_64' could in principle be
36 # ported to 32-bit as well. )
41 # Note: keep this list sorted alphabetically
43 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
44 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
46 select ARCH_CLOCKSOURCE_DATA
47 select ARCH_DISCARD_MEMBLOCK
48 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
49 select ARCH_HAS_DEBUG_VIRTUAL
50 select ARCH_HAS_DEVMEM_IS_ALLOWED
51 select ARCH_HAS_ELF_RANDOMIZE
52 select ARCH_HAS_FAST_MULTIPLIER
53 select ARCH_HAS_GCOV_PROFILE_ALL
54 select ARCH_HAS_KCOV if X86_64
55 select ARCH_HAS_MMIO_FLUSH
56 select ARCH_HAS_PMEM_API if X86_64
57 select ARCH_HAS_SET_MEMORY
58 select ARCH_HAS_SG_CHAIN
59 select ARCH_HAS_STRICT_KERNEL_RWX
60 select ARCH_HAS_STRICT_MODULE_RWX
61 select ARCH_HAS_UBSAN_SANITIZE_ALL
62 select ARCH_HAVE_NMI_SAFE_CMPXCHG
63 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
64 select ARCH_MIGHT_HAVE_PC_PARPORT
65 select ARCH_MIGHT_HAVE_PC_SERIO
66 select ARCH_SUPPORTS_ATOMIC_RMW
67 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
68 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
69 select ARCH_USE_BUILTIN_BSWAP
70 select ARCH_USE_QUEUED_RWLOCKS
71 select ARCH_USE_QUEUED_SPINLOCKS
72 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
73 select ARCH_WANT_FRAME_POINTERS
74 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
75 select BUILDTIME_EXTABLE_SORT
77 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
78 select CLOCKSOURCE_WATCHDOG
79 select DCACHE_WORD_ACCESS
80 select EDAC_ATOMIC_SCRUB
82 select GENERIC_CLOCKEVENTS
83 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
84 select GENERIC_CLOCKEVENTS_MIN_ADJUST
85 select GENERIC_CMOS_UPDATE
86 select GENERIC_CPU_AUTOPROBE
87 select GENERIC_EARLY_IOREMAP
88 select GENERIC_FIND_FIRST_BIT
90 select GENERIC_IRQ_PROBE
91 select GENERIC_IRQ_SHOW
92 select GENERIC_PENDING_IRQ if SMP
93 select GENERIC_SMP_IDLE_THREAD
94 select GENERIC_STRNCPY_FROM_USER
95 select GENERIC_STRNLEN_USER
96 select GENERIC_TIME_VSYSCALL
97 select HAVE_ACPI_APEI if ACPI
98 select HAVE_ACPI_APEI_NMI if ACPI
99 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
100 select HAVE_ARCH_AUDITSYSCALL
101 select HAVE_ARCH_HARDENED_USERCOPY
102 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
103 select HAVE_ARCH_JUMP_LABEL
104 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
105 select HAVE_ARCH_KGDB
106 select HAVE_ARCH_KMEMCHECK
107 select HAVE_ARCH_MMAP_RND_BITS if MMU
108 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
109 select HAVE_ARCH_SECCOMP_FILTER
110 select HAVE_ARCH_TRACEHOOK
111 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
112 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
113 select HAVE_ARCH_VMAP_STACK if X86_64
114 select HAVE_ARCH_WITHIN_STACK_FRAMES
115 select HAVE_CC_STACKPROTECTOR
116 select HAVE_CMPXCHG_DOUBLE
117 select HAVE_CMPXCHG_LOCAL
118 select HAVE_CONTEXT_TRACKING if X86_64
119 select HAVE_COPY_THREAD_TLS
120 select HAVE_C_RECORDMCOUNT
121 select HAVE_DEBUG_KMEMLEAK
122 select HAVE_DEBUG_STACKOVERFLOW
123 select HAVE_DMA_API_DEBUG
124 select HAVE_DMA_CONTIGUOUS
125 select HAVE_DYNAMIC_FTRACE
126 select HAVE_DYNAMIC_FTRACE_WITH_REGS
127 select HAVE_EBPF_JIT if X86_64
128 select HAVE_EFFICIENT_UNALIGNED_ACCESS
129 select HAVE_EXIT_THREAD
130 select HAVE_FENTRY if X86_64
131 select HAVE_FTRACE_MCOUNT_RECORD
132 select HAVE_FUNCTION_GRAPH_TRACER
133 select HAVE_FUNCTION_TRACER
134 select HAVE_GCC_PLUGINS
135 select HAVE_HW_BREAKPOINT
137 select HAVE_IOREMAP_PROT
138 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
139 select HAVE_IRQ_TIME_ACCOUNTING
140 select HAVE_KERNEL_BZIP2
141 select HAVE_KERNEL_GZIP
142 select HAVE_KERNEL_LZ4
143 select HAVE_KERNEL_LZMA
144 select HAVE_KERNEL_LZO
145 select HAVE_KERNEL_XZ
147 select HAVE_KPROBES_ON_FTRACE
148 select HAVE_KRETPROBES
150 select HAVE_LIVEPATCH if X86_64
152 select HAVE_MEMBLOCK_NODE_MAP
153 select HAVE_MIXED_BREAKPOINTS_REGS
156 select HAVE_OPTPROBES
157 select HAVE_PCSPKR_PLATFORM
158 select HAVE_PERF_EVENTS
159 select HAVE_PERF_EVENTS_NMI
160 select HAVE_PERF_REGS
161 select HAVE_PERF_USER_STACK_DUMP
162 select HAVE_REGS_AND_STACK_ACCESS_API
163 select HAVE_STACK_VALIDATION if X86_64
164 select HAVE_SYSCALL_TRACEPOINTS
165 select HAVE_UNSTABLE_SCHED_CLOCK
166 select HAVE_USER_RETURN_NOTIFIER
167 select IRQ_FORCED_THREADING
170 select RTC_MC146818_LIB
173 select SYSCTL_EXCEPTION_TRACE
174 select THREAD_INFO_IN_TASK
175 select USER_STACKTRACE_SUPPORT
177 select X86_FEATURE_NAMES if PROC_FS
179 config INSTRUCTION_DECODER
181 depends on KPROBES || PERF_EVENTS || UPROBES
185 default "elf32-i386" if X86_32
186 default "elf64-x86-64" if X86_64
188 config ARCH_DEFCONFIG
190 default "arch/x86/configs/i386_defconfig" if X86_32
191 default "arch/x86/configs/x86_64_defconfig" if X86_64
193 config LOCKDEP_SUPPORT
196 config STACKTRACE_SUPPORT
202 config ARCH_MMAP_RND_BITS_MIN
206 config ARCH_MMAP_RND_BITS_MAX
210 config ARCH_MMAP_RND_COMPAT_BITS_MIN
213 config ARCH_MMAP_RND_COMPAT_BITS_MAX
219 config NEED_DMA_MAP_STATE
221 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
223 config NEED_SG_DMA_LENGTH
226 config GENERIC_ISA_DMA
228 depends on ISA_DMA_API
233 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
235 config GENERIC_BUG_RELATIVE_POINTERS
238 config GENERIC_HWEIGHT
241 config ARCH_MAY_HAVE_PC_FDC
243 depends on ISA_DMA_API
245 config RWSEM_XCHGADD_ALGORITHM
248 config GENERIC_CALIBRATE_DELAY
251 config ARCH_HAS_CPU_RELAX
254 config ARCH_HAS_CACHE_LINE_SIZE
257 config HAVE_SETUP_PER_CPU_AREA
260 config NEED_PER_CPU_EMBED_FIRST_CHUNK
263 config NEED_PER_CPU_PAGE_FIRST_CHUNK
266 config ARCH_HIBERNATION_POSSIBLE
269 config ARCH_SUSPEND_POSSIBLE
272 config ARCH_WANT_HUGE_PMD_SHARE
275 config ARCH_WANT_GENERAL_HUGETLB
284 config ARCH_SUPPORTS_OPTIMIZED_INLINING
287 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
290 config KASAN_SHADOW_OFFSET
293 default 0xdffffc0000000000
295 config HAVE_INTEL_TXT
297 depends on INTEL_IOMMU && ACPI
301 depends on X86_32 && SMP
305 depends on X86_64 && SMP
307 config X86_32_LAZY_GS
309 depends on X86_32 && !CC_STACKPROTECTOR
311 config ARCH_SUPPORTS_UPROBES
314 config FIX_EARLYCON_MEM
317 config PGTABLE_LEVELS
323 source "init/Kconfig"
324 source "kernel/Kconfig.freezer"
326 menu "Processor type and features"
329 bool "DMA memory allocation support" if EXPERT
332 DMA memory allocation support allows devices with less than 32-bit
333 addressing to allocate within the first 16MB of address space.
334 Disable if no such devices will be used.
339 bool "Symmetric multi-processing support"
341 This enables support for systems with more than one CPU. If you have
342 a system with only one CPU, say N. If you have a system with more
345 If you say N here, the kernel will run on uni- and multiprocessor
346 machines, but will use only one CPU of a multiprocessor machine. If
347 you say Y here, the kernel will run on many, but not all,
348 uniprocessor machines. On a uniprocessor machine, the kernel
349 will run faster if you say N here.
351 Note that if you say Y here and choose architecture "586" or
352 "Pentium" under "Processor family", the kernel will not work on 486
353 architectures. Similarly, multiprocessor kernels for the "PPro"
354 architecture may not work on all Pentium based boards.
356 People using multiprocessor machines who say Y here should also say
357 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
358 Management" code will be disabled if you say Y here.
360 See also <file:Documentation/x86/i386/IO-APIC.txt>,
361 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
362 <http://www.tldp.org/docs.html#howto>.
364 If you don't know what to do here, say N.
366 config X86_FEATURE_NAMES
367 bool "Processor feature human-readable names" if EMBEDDED
370 This option compiles in a table of x86 feature bits and corresponding
371 names. This is required to support /proc/cpuinfo and a few kernel
372 messages. You can disable this to save space, at the expense of
373 making those few kernel messages show numeric feature bits instead.
377 config X86_FAST_FEATURE_TESTS
378 bool "Fast CPU feature tests" if EMBEDDED
381 Some fast-paths in the kernel depend on the capabilities of the CPU.
382 Say Y here for the kernel to patch in the appropriate code at runtime
383 based on the capabilities of the CPU. The infrastructure for patching
384 code at runtime takes up some additional space; space-constrained
385 embedded systems may wish to say N here to produce smaller, slightly
389 bool "Support x2apic"
390 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
392 This enables x2apic support on CPUs that have this feature.
394 This allows 32-bit apic IDs (so it can support very large systems),
395 and accesses the local apic via MSRs not via mmio.
397 If you don't know what to do here, say N.
400 bool "Enable MPS table" if ACPI || SFI
402 depends on X86_LOCAL_APIC
404 For old smp systems that do not have proper acpi support. Newer systems
405 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
408 bool "Support for big SMP systems with more than 8 CPUs"
409 depends on X86_32 && SMP
411 This option is needed for the systems that have more than 8 CPUs
415 depends on X86_GOLDFISH
418 bool "Intel Resource Director Technology Allocation support"
420 depends on X86 && CPU_SUP_INTEL
423 Select to enable resource allocation which is a sub-feature of
424 Intel Resource Director Technology(RDT). More information about
425 RDT can be found in the Intel x86 Architecture Software
431 config X86_EXTENDED_PLATFORM
432 bool "Support for extended (non-PC) x86 platforms"
435 If you disable this option then the kernel will only support
436 standard PC platforms. (which covers the vast majority of
439 If you enable this option then you'll be able to select support
440 for the following (non-PC) 32 bit x86 platforms:
441 Goldfish (Android emulator)
444 SGI 320/540 (Visual Workstation)
445 STA2X11-based (e.g. Northville)
446 Moorestown MID devices
448 If you have one of these systems, or if you want to build a
449 generic distribution kernel, say Y here - otherwise say N.
453 config X86_EXTENDED_PLATFORM
454 bool "Support for extended (non-PC) x86 platforms"
457 If you disable this option then the kernel will only support
458 standard PC platforms. (which covers the vast majority of
461 If you enable this option then you'll be able to select support
462 for the following (non-PC) 64 bit x86 platforms:
467 If you have one of these systems, or if you want to build a
468 generic distribution kernel, say Y here - otherwise say N.
470 # This is an alphabetically sorted list of 64 bit extended platforms
471 # Please maintain the alphabetic order if and when there are additions
473 bool "Numascale NumaChip"
475 depends on X86_EXTENDED_PLATFORM
478 depends on X86_X2APIC
479 depends on PCI_MMCONFIG
481 Adds support for Numascale NumaChip large-SMP systems. Needed to
482 enable more than ~168 cores.
483 If you don't have one of these, you should say N here.
487 select HYPERVISOR_GUEST
489 depends on X86_64 && PCI
490 depends on X86_EXTENDED_PLATFORM
493 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
494 supposed to run on these EM64T-based machines. Only choose this option
495 if you have one of these machines.
498 bool "SGI Ultraviolet"
500 depends on X86_EXTENDED_PLATFORM
503 depends on X86_X2APIC
506 This option is needed in order to support SGI Ultraviolet systems.
507 If you don't have one of these, you should say N here.
509 # Following is an alphabetically sorted list of 32 bit extended platforms
510 # Please maintain the alphabetic order if and when there are additions
513 bool "Goldfish (Virtual Platform)"
514 depends on X86_EXTENDED_PLATFORM
516 Enable support for the Goldfish virtual platform used primarily
517 for Android development. Unless you are building for the Android
518 Goldfish emulator say N here.
521 bool "CE4100 TV platform"
523 depends on PCI_GODIRECT
524 depends on X86_IO_APIC
526 depends on X86_EXTENDED_PLATFORM
527 select X86_REBOOTFIXUPS
529 select OF_EARLY_FLATTREE
531 Select for the Intel CE media processor (CE4100) SOC.
532 This option compiles in support for the CE4100 SOC for settop
533 boxes and media devices.
536 bool "Intel MID platform support"
537 depends on X86_EXTENDED_PLATFORM
538 depends on X86_PLATFORM_DEVICES
540 depends on X86_64 || (PCI_GOANY && X86_32)
541 depends on X86_IO_APIC
547 select MFD_INTEL_MSIC
549 Select to build a kernel capable of supporting Intel MID (Mobile
550 Internet Device) platform systems which do not have the PCI legacy
551 interfaces. If you are building for a PC class system say N here.
553 Intel MID platforms are based on an Intel processor and chipset which
554 consume less power than most of the x86 derivatives.
556 config X86_INTEL_QUARK
557 bool "Intel Quark platform support"
559 depends on X86_EXTENDED_PLATFORM
560 depends on X86_PLATFORM_DEVICES
564 depends on X86_IO_APIC
569 Select to include support for Quark X1000 SoC.
570 Say Y here if you have a Quark based system such as the Arduino
571 compatible Intel Galileo.
573 config X86_INTEL_LPSS
574 bool "Intel Low Power Subsystem Support"
575 depends on X86 && ACPI
580 Select to build support for Intel Low Power Subsystem such as
581 found on Intel Lynxpoint PCH. Selecting this option enables
582 things like clock tree (common clock framework) and pincontrol
583 which are needed by the LPSS peripheral drivers.
585 config X86_AMD_PLATFORM_DEVICE
586 bool "AMD ACPI2Platform devices support"
591 Select to interpret AMD specific ACPI device to platform device
592 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
593 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
594 implemented under PINCTRL subsystem.
597 tristate "Intel SoC IOSF Sideband support for SoC platforms"
600 This option enables sideband register access support for Intel SoC
601 platforms. On these platforms the IOSF sideband is used in lieu of
602 MSR's for some register accesses, mostly but not limited to thermal
603 and power. Drivers may query the availability of this device to
604 determine if they need the sideband in order to work on these
605 platforms. The sideband is available on the following SoC products.
606 This list is not meant to be exclusive.
611 You should say Y if you are running a kernel on one of these SoC's.
613 config IOSF_MBI_DEBUG
614 bool "Enable IOSF sideband access through debugfs"
615 depends on IOSF_MBI && DEBUG_FS
617 Select this option to expose the IOSF sideband access registers (MCR,
618 MDR, MCRX) through debugfs to write and read register information from
619 different units on the SoC. This is most useful for obtaining device
620 state information for debug and analysis. As this is a general access
621 mechanism, users of this option would have specific knowledge of the
622 device they want to access.
624 If you don't require the option or are in doubt, say N.
627 bool "RDC R-321x SoC"
629 depends on X86_EXTENDED_PLATFORM
631 select X86_REBOOTFIXUPS
633 This option is needed for RDC R-321x system-on-chip, also known
635 If you don't have one of these chips, you should say N here.
637 config X86_32_NON_STANDARD
638 bool "Support non-standard 32-bit SMP architectures"
639 depends on X86_32 && SMP
640 depends on X86_EXTENDED_PLATFORM
642 This option compiles in the bigsmp and STA2X11 default
643 subarchitectures. It is intended for a generic binary
644 kernel. If you select them all, kernel will probe it one by
645 one and will fallback to default.
647 # Alphabetically sorted list of Non standard 32 bit platforms
649 config X86_SUPPORTS_MEMORY_FAILURE
651 # MCE code calls memory_failure():
653 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
654 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
655 depends on X86_64 || !SPARSEMEM
656 select ARCH_SUPPORTS_MEMORY_FAILURE
659 bool "STA2X11 Companion Chip Support"
660 depends on X86_32_NON_STANDARD && PCI
661 select X86_DEV_DMA_OPS
668 This adds support for boards based on the STA2X11 IO-Hub,
669 a.k.a. "ConneXt". The chip is used in place of the standard
670 PC chipset, so all "standard" peripherals are missing. If this
671 option is selected the kernel will still be able to boot on
672 standard PC machines.
675 tristate "Eurobraille/Iris poweroff module"
678 The Iris machines from EuroBraille do not have APM or ACPI support
679 to shut themselves down properly. A special I/O sequence is
680 needed to do so, which is what this module does at
683 This is only for Iris machines from EuroBraille.
687 config SCHED_OMIT_FRAME_POINTER
689 prompt "Single-depth WCHAN output"
692 Calculate simpler /proc/<PID>/wchan values. If this option
693 is disabled then wchan values will recurse back to the
694 caller function. This provides more accurate wchan values,
695 at the expense of slightly more scheduling overhead.
697 If in doubt, say "Y".
699 menuconfig HYPERVISOR_GUEST
700 bool "Linux guest support"
702 Say Y here to enable options for running Linux under various hyper-
703 visors. This option enables basic hypervisor detection and platform
706 If you say N, all options in this submenu will be skipped and
707 disabled, and Linux guest support won't be built in.
712 bool "Enable paravirtualization code"
714 This changes the kernel so it can modify itself when it is run
715 under a hypervisor, potentially improving performance significantly
716 over full virtualization. However, when run without a hypervisor
717 the kernel is theoretically slower and slightly larger.
719 config PARAVIRT_DEBUG
720 bool "paravirt-ops debugging"
721 depends on PARAVIRT && DEBUG_KERNEL
723 Enable to debug paravirt_ops internals. Specifically, BUG if
724 a paravirt_op is missing when it is called.
726 config PARAVIRT_SPINLOCKS
727 bool "Paravirtualization layer for spinlocks"
728 depends on PARAVIRT && SMP
730 Paravirtualized spinlocks allow a pvops backend to replace the
731 spinlock implementation with something virtualization-friendly
732 (for example, block the virtual CPU rather than spinning).
734 It has a minimal impact on native kernels and gives a nice performance
735 benefit on paravirtualized KVM / Xen kernels.
737 If you are unsure how to answer this question, answer Y.
739 config QUEUED_LOCK_STAT
740 bool "Paravirt queued spinlock statistics"
741 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
743 Enable the collection of statistical data on the slowpath
744 behavior of paravirtualized queued spinlocks and report
747 source "arch/x86/xen/Kconfig"
750 bool "KVM Guest support (including kvmclock)"
752 select PARAVIRT_CLOCK
755 This option enables various optimizations for running under the KVM
756 hypervisor. It includes a paravirtualized clock, so that instead
757 of relying on a PIT (or probably other) emulation by the
758 underlying device model, the host provides the guest with
759 timing infrastructure such as time of day, and system time
762 bool "Enable debug information for KVM Guests in debugfs"
763 depends on KVM_GUEST && DEBUG_FS
766 This option enables collection of various statistics for KVM guest.
767 Statistics are displayed in debugfs filesystem. Enabling this option
768 may incur significant overhead.
770 source "arch/x86/lguest/Kconfig"
772 config PARAVIRT_TIME_ACCOUNTING
773 bool "Paravirtual steal time accounting"
777 Select this option to enable fine granularity task steal time
778 accounting. Time spent executing other tasks in parallel with
779 the current vCPU is discounted from the vCPU power. To account for
780 that, there can be a small performance impact.
782 If in doubt, say N here.
784 config PARAVIRT_CLOCK
787 endif #HYPERVISOR_GUEST
792 source "arch/x86/Kconfig.cpu"
796 prompt "HPET Timer Support" if X86_32
798 Use the IA-PC HPET (High Precision Event Timer) to manage
799 time in preference to the PIT and RTC, if a HPET is
801 HPET is the next generation timer replacing legacy 8254s.
802 The HPET provides a stable time base on SMP
803 systems, unlike the TSC, but it is more expensive to access,
804 as it is off-chip. The interface used is documented
805 in the HPET spec, revision 1.
807 You can safely choose Y here. However, HPET will only be
808 activated if the platform and the BIOS support this feature.
809 Otherwise the 8254 will be used for timing services.
811 Choose N to continue using the legacy 8254 timer.
813 config HPET_EMULATE_RTC
815 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
818 def_bool y if X86_INTEL_MID
819 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
821 depends on X86_INTEL_MID && SFI
823 APB timer is the replacement for 8254, HPET on X86 MID platforms.
824 The APBT provides a stable time base on SMP
825 systems, unlike the TSC, but it is more expensive to access,
826 as it is off-chip. APB timers are always running regardless of CPU
827 C states, they are used as per CPU clockevent device when possible.
829 # Mark as expert because too many people got it wrong.
830 # The code disables itself when not needed.
833 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
834 bool "Enable DMI scanning" if EXPERT
836 Enabled scanning of DMI to identify machine quirks. Say Y
837 here unless you have verified that your setup is not
838 affected by entries in the DMI blacklist. Required by PNP
842 bool "Old AMD GART IOMMU support"
844 depends on X86_64 && PCI && AMD_NB
846 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
847 GART based hardware IOMMUs.
849 The GART supports full DMA access for devices with 32-bit access
850 limitations, on systems with more than 3 GB. This is usually needed
851 for USB, sound, many IDE/SATA chipsets and some other devices.
853 Newer systems typically have a modern AMD IOMMU, supported via
854 the CONFIG_AMD_IOMMU=y config option.
856 In normal configurations this driver is only active when needed:
857 there's more than 3 GB of memory and the system contains a
858 32-bit limited device.
863 bool "IBM Calgary IOMMU support"
865 depends on X86_64 && PCI
867 Support for hardware IOMMUs in IBM's xSeries x366 and x460
868 systems. Needed to run systems with more than 3GB of memory
869 properly with 32-bit PCI devices that do not support DAC
870 (Double Address Cycle). Calgary also supports bus level
871 isolation, where all DMAs pass through the IOMMU. This
872 prevents them from going anywhere except their intended
873 destination. This catches hard-to-find kernel bugs and
874 mis-behaving drivers and devices that do not use the DMA-API
875 properly to set up their DMA buffers. The IOMMU can be
876 turned off at boot time with the iommu=off parameter.
877 Normally the kernel will make the right choice by itself.
880 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
882 prompt "Should Calgary be enabled by default?"
883 depends on CALGARY_IOMMU
885 Should Calgary be enabled by default? if you choose 'y', Calgary
886 will be used (if it exists). If you choose 'n', Calgary will not be
887 used even if it exists. If you choose 'n' and would like to use
888 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
891 # need this always selected by IOMMU for the VIA workaround
895 Support for software bounce buffers used on x86-64 systems
896 which don't have a hardware IOMMU. Using this PCI devices
897 which can only access 32-bits of memory can be used on systems
898 with more than 3 GB of memory.
903 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
906 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
907 depends on X86_64 && SMP && DEBUG_KERNEL
908 select CPUMASK_OFFSTACK
910 Enable maximum number of CPUS and NUMA Nodes for this architecture.
914 int "Maximum number of CPUs" if SMP && !MAXSMP
915 range 2 8 if SMP && X86_32 && !X86_BIGSMP
916 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
917 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
919 default "8192" if MAXSMP
920 default "32" if SMP && X86_BIGSMP
921 default "8" if SMP && X86_32
924 This allows you to specify the maximum number of CPUs which this
925 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
926 supported value is 8192, otherwise the maximum value is 512. The
927 minimum value which makes sense is 2.
929 This is purely to save memory - each supported CPU adds
930 approximately eight kilobytes to the kernel image.
933 bool "SMT (Hyperthreading) scheduler support"
936 SMT scheduler support improves the CPU scheduler's decision making
937 when dealing with Intel Pentium 4 chips with HyperThreading at a
938 cost of slightly increased overhead in some places. If unsure say
943 prompt "Multi-core scheduler support"
946 Multi-core scheduler support improves the CPU scheduler's decision
947 making when dealing with multi-core CPU chips at a cost of slightly
948 increased overhead in some places. If unsure say N here.
951 bool "CPU core priorities scheduler support"
952 depends on SCHED_MC && CPU_SUP_INTEL
953 select X86_INTEL_PSTATE
957 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
958 core ordering determined at manufacturing time, which allows
959 certain cores to reach higher turbo frequencies (when running
960 single threaded workloads) than others.
962 Enabling this kernel feature teaches the scheduler about
963 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
964 scheduler's CPU selection logic accordingly, so that higher
965 overall system performance can be achieved.
967 This feature will have no effect on CPUs without this feature.
969 If unsure say Y here.
971 source "kernel/Kconfig.preempt"
975 depends on !SMP && X86_LOCAL_APIC
978 bool "Local APIC support on uniprocessors" if !PCI_MSI
980 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
982 A local APIC (Advanced Programmable Interrupt Controller) is an
983 integrated interrupt controller in the CPU. If you have a single-CPU
984 system which has a processor with a local APIC, you can say Y here to
985 enable and use it. If you say Y here even though your machine doesn't
986 have a local APIC, then the kernel will still run with no slowdown at
987 all. The local APIC supports CPU-generated self-interrupts (timer,
988 performance counters), and the NMI watchdog which detects hard
992 bool "IO-APIC support on uniprocessors"
993 depends on X86_UP_APIC
995 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
996 SMP-capable replacement for PC-style interrupt controllers. Most
997 SMP systems and many recent uniprocessor systems have one.
999 If you have a single-CPU system with an IO-APIC, you can say Y here
1000 to use it. If you say Y here even though your machine doesn't have
1001 an IO-APIC, then the kernel will still run with no slowdown at all.
1003 config X86_LOCAL_APIC
1005 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1006 select IRQ_DOMAIN_HIERARCHY
1007 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1011 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1013 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1014 bool "Reroute for broken boot IRQs"
1015 depends on X86_IO_APIC
1017 This option enables a workaround that fixes a source of
1018 spurious interrupts. This is recommended when threaded
1019 interrupt handling is used on systems where the generation of
1020 superfluous "boot interrupts" cannot be disabled.
1022 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1023 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1024 kernel does during interrupt handling). On chipsets where this
1025 boot IRQ generation cannot be disabled, this workaround keeps
1026 the original IRQ line masked so that only the equivalent "boot
1027 IRQ" is delivered to the CPUs. The workaround also tells the
1028 kernel to set up the IRQ handler on the boot IRQ line. In this
1029 way only one interrupt is delivered to the kernel. Otherwise
1030 the spurious second interrupt may cause the kernel to bring
1031 down (vital) interrupt lines.
1033 Only affects "broken" chipsets. Interrupt sharing may be
1034 increased on these systems.
1037 bool "Machine Check / overheating reporting"
1038 select GENERIC_ALLOCATOR
1041 Machine Check support allows the processor to notify the
1042 kernel if it detects a problem (e.g. overheating, data corruption).
1043 The action the kernel takes depends on the severity of the problem,
1044 ranging from warning messages to halting the machine.
1046 config X86_MCE_INTEL
1048 prompt "Intel MCE features"
1049 depends on X86_MCE && X86_LOCAL_APIC
1051 Additional support for intel specific MCE features such as
1052 the thermal monitor.
1056 prompt "AMD MCE features"
1057 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1059 Additional support for AMD specific MCE features such as
1060 the DRAM Error Threshold.
1062 config X86_ANCIENT_MCE
1063 bool "Support for old Pentium 5 / WinChip machine checks"
1064 depends on X86_32 && X86_MCE
1066 Include support for machine check handling on old Pentium 5 or WinChip
1067 systems. These typically need to be enabled explicitly on the command
1070 config X86_MCE_THRESHOLD
1071 depends on X86_MCE_AMD || X86_MCE_INTEL
1074 config X86_MCE_INJECT
1075 depends on X86_MCE && X86_LOCAL_APIC
1076 tristate "Machine check injector support"
1078 Provide support for injecting machine checks for testing purposes.
1079 If you don't know what a machine check is and you don't do kernel
1080 QA it is safe to say n.
1082 config X86_THERMAL_VECTOR
1084 depends on X86_MCE_INTEL
1086 source "arch/x86/events/Kconfig"
1088 config X86_LEGACY_VM86
1089 bool "Legacy VM86 support"
1093 This option allows user programs to put the CPU into V8086
1094 mode, which is an 80286-era approximation of 16-bit real mode.
1096 Some very old versions of X and/or vbetool require this option
1097 for user mode setting. Similarly, DOSEMU will use it if
1098 available to accelerate real mode DOS programs. However, any
1099 recent version of DOSEMU, X, or vbetool should be fully
1100 functional even without kernel VM86 support, as they will all
1101 fall back to software emulation. Nevertheless, if you are using
1102 a 16-bit DOS program where 16-bit performance matters, vm86
1103 mode might be faster than emulation and you might want to
1106 Note that any app that works on a 64-bit kernel is unlikely to
1107 need this option, as 64-bit kernels don't, and can't, support
1108 V8086 mode. This option is also unrelated to 16-bit protected
1109 mode and is not needed to run most 16-bit programs under Wine.
1111 Enabling this option increases the complexity of the kernel
1112 and slows down exception handling a tiny bit.
1114 If unsure, say N here.
1118 default X86_LEGACY_VM86
1121 bool "Enable support for 16-bit segments" if EXPERT
1123 depends on MODIFY_LDT_SYSCALL
1125 This option is required by programs like Wine to run 16-bit
1126 protected mode legacy code on x86 processors. Disabling
1127 this option saves about 300 bytes on i386, or around 6K text
1128 plus 16K runtime memory on x86-64,
1132 depends on X86_16BIT && X86_32
1136 depends on X86_16BIT && X86_64
1138 config X86_VSYSCALL_EMULATION
1139 bool "Enable vsyscall emulation" if EXPERT
1143 This enables emulation of the legacy vsyscall page. Disabling
1144 it is roughly equivalent to booting with vsyscall=none, except
1145 that it will also disable the helpful warning if a program
1146 tries to use a vsyscall. With this option set to N, offending
1147 programs will just segfault, citing addresses of the form
1150 This option is required by many programs built before 2013, and
1151 care should be used even with newer programs if set to N.
1153 Disabling this option saves about 7K of kernel size and
1154 possibly 4K of additional runtime pagetable memory.
1157 tristate "Toshiba Laptop support"
1160 This adds a driver to safely access the System Management Mode of
1161 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1162 not work on models with a Phoenix BIOS. The System Management Mode
1163 is used to set the BIOS and power saving options on Toshiba portables.
1165 For information on utilities to make use of this driver see the
1166 Toshiba Linux utilities web site at:
1167 <http://www.buzzard.org.uk/toshiba/>.
1169 Say Y if you intend to run this kernel on a Toshiba portable.
1173 tristate "Dell i8k legacy laptop support"
1175 select SENSORS_DELL_SMM
1177 This option enables legacy /proc/i8k userspace interface in hwmon
1178 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1179 temperature and allows controlling fan speeds of Dell laptops via
1180 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1181 it reports also power and hotkey status. For fan speed control is
1182 needed userspace package i8kutils.
1184 Say Y if you intend to run this kernel on old Dell laptops or want to
1185 use userspace package i8kutils.
1188 config X86_REBOOTFIXUPS
1189 bool "Enable X86 board specific fixups for reboot"
1192 This enables chipset and/or board specific fixups to be done
1193 in order to get reboot to work correctly. This is only needed on
1194 some combinations of hardware and BIOS. The symptom, for which
1195 this config is intended, is when reboot ends with a stalled/hung
1198 Currently, the only fixup is for the Geode machines using
1199 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1201 Say Y if you want to enable the fixup. Currently, it's safe to
1202 enable this option even if you don't need it.
1206 bool "CPU microcode loading support"
1208 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1211 If you say Y here, you will be able to update the microcode on
1212 Intel and AMD processors. The Intel support is for the IA32 family,
1213 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1214 AMD support is for families 0x10 and later. You will obviously need
1215 the actual microcode binary data itself which is not shipped with
1218 The preferred method to load microcode from a detached initrd is described
1219 in Documentation/x86/early-microcode.txt. For that you need to enable
1220 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1221 initrd for microcode blobs.
1223 In addition, you can build-in the microcode into the kernel. For that you
1224 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1225 to the CONFIG_EXTRA_FIRMWARE config option.
1227 config MICROCODE_INTEL
1228 bool "Intel microcode loading support"
1229 depends on MICROCODE
1233 This options enables microcode patch loading support for Intel
1236 For the current Intel microcode data package go to
1237 <https://downloadcenter.intel.com> and search for
1238 'Linux Processor Microcode Data File'.
1240 config MICROCODE_AMD
1241 bool "AMD microcode loading support"
1242 depends on MICROCODE
1245 If you select this option, microcode patch loading support for AMD
1246 processors will be enabled.
1248 config MICROCODE_OLD_INTERFACE
1250 depends on MICROCODE
1253 tristate "/dev/cpu/*/msr - Model-specific register support"
1255 This device gives privileged processes access to the x86
1256 Model-Specific Registers (MSRs). It is a character device with
1257 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1258 MSR accesses are directed to a specific CPU on multi-processor
1262 tristate "/dev/cpu/*/cpuid - CPU information support"
1264 This device gives processes access to the x86 CPUID instruction to
1265 be executed on a specific processor. It is a character device
1266 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1270 prompt "High Memory Support"
1277 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1278 However, the address space of 32-bit x86 processors is only 4
1279 Gigabytes large. That means that, if you have a large amount of
1280 physical memory, not all of it can be "permanently mapped" by the
1281 kernel. The physical memory that's not permanently mapped is called
1284 If you are compiling a kernel which will never run on a machine with
1285 more than 1 Gigabyte total physical RAM, answer "off" here (default
1286 choice and suitable for most users). This will result in a "3GB/1GB"
1287 split: 3GB are mapped so that each process sees a 3GB virtual memory
1288 space and the remaining part of the 4GB virtual memory space is used
1289 by the kernel to permanently map as much physical memory as
1292 If the machine has between 1 and 4 Gigabytes physical RAM, then
1295 If more than 4 Gigabytes is used then answer "64GB" here. This
1296 selection turns Intel PAE (Physical Address Extension) mode on.
1297 PAE implements 3-level paging on IA32 processors. PAE is fully
1298 supported by Linux, PAE mode is implemented on all recent Intel
1299 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1300 then the kernel will not boot on CPUs that don't support PAE!
1302 The actual amount of total physical memory will either be
1303 auto detected or can be forced by using a kernel command line option
1304 such as "mem=256M". (Try "man bootparam" or see the documentation of
1305 your boot loader (lilo or loadlin) about how to pass options to the
1306 kernel at boot time.)
1308 If unsure, say "off".
1313 Select this if you have a 32-bit processor and between 1 and 4
1314 gigabytes of physical RAM.
1321 Select this if you have a 32-bit processor and more than 4
1322 gigabytes of physical RAM.
1327 prompt "Memory split" if EXPERT
1331 Select the desired split between kernel and user memory.
1333 If the address range available to the kernel is less than the
1334 physical memory installed, the remaining memory will be available
1335 as "high memory". Accessing high memory is a little more costly
1336 than low memory, as it needs to be mapped into the kernel first.
1337 Note that increasing the kernel address space limits the range
1338 available to user programs, making the address space there
1339 tighter. Selecting anything other than the default 3G/1G split
1340 will also likely make your kernel incompatible with binary-only
1343 If you are not absolutely sure what you are doing, leave this
1347 bool "3G/1G user/kernel split"
1348 config VMSPLIT_3G_OPT
1350 bool "3G/1G user/kernel split (for full 1G low memory)"
1352 bool "2G/2G user/kernel split"
1353 config VMSPLIT_2G_OPT
1355 bool "2G/2G user/kernel split (for full 2G low memory)"
1357 bool "1G/3G user/kernel split"
1362 default 0xB0000000 if VMSPLIT_3G_OPT
1363 default 0x80000000 if VMSPLIT_2G
1364 default 0x78000000 if VMSPLIT_2G_OPT
1365 default 0x40000000 if VMSPLIT_1G
1371 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1374 bool "PAE (Physical Address Extension) Support"
1375 depends on X86_32 && !HIGHMEM4G
1378 PAE is required for NX support, and furthermore enables
1379 larger swapspace support for non-overcommit purposes. It
1380 has the cost of more pagetable lookup overhead, and also
1381 consumes more pagetable space per process.
1383 config ARCH_PHYS_ADDR_T_64BIT
1385 depends on X86_64 || X86_PAE
1387 config ARCH_DMA_ADDR_T_64BIT
1389 depends on X86_64 || HIGHMEM64G
1391 config X86_DIRECT_GBPAGES
1393 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1395 Certain kernel features effectively disable kernel
1396 linear 1 GB mappings (even if the CPU otherwise
1397 supports them), so don't confuse the user by printing
1398 that we have them enabled.
1400 # Common NUMA Features
1402 bool "Numa Memory Allocation and Scheduler Support"
1404 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1405 default y if X86_BIGSMP
1407 Enable NUMA (Non Uniform Memory Access) support.
1409 The kernel will try to allocate memory used by a CPU on the
1410 local memory controller of the CPU and add some more
1411 NUMA awareness to the kernel.
1413 For 64-bit this is recommended if the system is Intel Core i7
1414 (or later), AMD Opteron, or EM64T NUMA.
1416 For 32-bit this is only needed if you boot a 32-bit
1417 kernel on a 64-bit NUMA platform.
1419 Otherwise, you should say N.
1423 prompt "Old style AMD Opteron NUMA detection"
1424 depends on X86_64 && NUMA && PCI
1426 Enable AMD NUMA node topology detection. You should say Y here if
1427 you have a multi processor AMD system. This uses an old method to
1428 read the NUMA configuration directly from the builtin Northbridge
1429 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1430 which also takes priority if both are compiled in.
1432 config X86_64_ACPI_NUMA
1434 prompt "ACPI NUMA detection"
1435 depends on X86_64 && NUMA && ACPI && PCI
1438 Enable ACPI SRAT based node topology detection.
1440 # Some NUMA nodes have memory ranges that span
1441 # other nodes. Even though a pfn is valid and
1442 # between a node's start and end pfns, it may not
1443 # reside on that node. See memmap_init_zone()
1445 config NODES_SPAN_OTHER_NODES
1447 depends on X86_64_ACPI_NUMA
1450 bool "NUMA emulation"
1453 Enable NUMA emulation. A flat machine will be split
1454 into virtual nodes when booted with "numa=fake=N", where N is the
1455 number of nodes. This is only useful for debugging.
1458 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1460 default "10" if MAXSMP
1461 default "6" if X86_64
1463 depends on NEED_MULTIPLE_NODES
1465 Specify the maximum number of NUMA Nodes available on the target
1466 system. Increases memory reserved to accommodate various tables.
1468 config ARCH_HAVE_MEMORY_PRESENT
1470 depends on X86_32 && DISCONTIGMEM
1472 config NEED_NODE_MEMMAP_SIZE
1474 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1476 config ARCH_FLATMEM_ENABLE
1478 depends on X86_32 && !NUMA
1480 config ARCH_DISCONTIGMEM_ENABLE
1482 depends on NUMA && X86_32
1484 config ARCH_DISCONTIGMEM_DEFAULT
1486 depends on NUMA && X86_32
1488 config ARCH_SPARSEMEM_ENABLE
1490 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1491 select SPARSEMEM_STATIC if X86_32
1492 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1494 config ARCH_SPARSEMEM_DEFAULT
1498 config ARCH_SELECT_MEMORY_MODEL
1500 depends on ARCH_SPARSEMEM_ENABLE
1502 config ARCH_MEMORY_PROBE
1503 bool "Enable sysfs memory/probe interface"
1504 depends on X86_64 && MEMORY_HOTPLUG
1506 This option enables a sysfs memory/probe interface for testing.
1507 See Documentation/memory-hotplug.txt for more information.
1508 If you are unsure how to answer this question, answer N.
1510 config ARCH_PROC_KCORE_TEXT
1512 depends on X86_64 && PROC_KCORE
1514 config ILLEGAL_POINTER_VALUE
1517 default 0xdead000000000000 if X86_64
1521 config X86_PMEM_LEGACY_DEVICE
1524 config X86_PMEM_LEGACY
1525 tristate "Support non-standard NVDIMMs and ADR protected memory"
1526 depends on PHYS_ADDR_T_64BIT
1528 select X86_PMEM_LEGACY_DEVICE
1531 Treat memory marked using the non-standard e820 type of 12 as used
1532 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1533 The kernel will offer these regions to the 'pmem' driver so
1534 they can be used for persistent storage.
1539 bool "Allocate 3rd-level pagetables from highmem"
1542 The VM uses one page table entry for each page of physical memory.
1543 For systems with a lot of RAM, this can be wasteful of precious
1544 low memory. Setting this option will put user-space page table
1545 entries in high memory.
1547 config X86_CHECK_BIOS_CORRUPTION
1548 bool "Check for low memory corruption"
1550 Periodically check for memory corruption in low memory, which
1551 is suspected to be caused by BIOS. Even when enabled in the
1552 configuration, it is disabled at runtime. Enable it by
1553 setting "memory_corruption_check=1" on the kernel command
1554 line. By default it scans the low 64k of memory every 60
1555 seconds; see the memory_corruption_check_size and
1556 memory_corruption_check_period parameters in
1557 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1559 When enabled with the default parameters, this option has
1560 almost no overhead, as it reserves a relatively small amount
1561 of memory and scans it infrequently. It both detects corruption
1562 and prevents it from affecting the running system.
1564 It is, however, intended as a diagnostic tool; if repeatable
1565 BIOS-originated corruption always affects the same memory,
1566 you can use memmap= to prevent the kernel from using that
1569 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1570 bool "Set the default setting of memory_corruption_check"
1571 depends on X86_CHECK_BIOS_CORRUPTION
1574 Set whether the default state of memory_corruption_check is
1577 config X86_RESERVE_LOW
1578 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1582 Specify the amount of low memory to reserve for the BIOS.
1584 The first page contains BIOS data structures that the kernel
1585 must not use, so that page must always be reserved.
1587 By default we reserve the first 64K of physical RAM, as a
1588 number of BIOSes are known to corrupt that memory range
1589 during events such as suspend/resume or monitor cable
1590 insertion, so it must not be used by the kernel.
1592 You can set this to 4 if you are absolutely sure that you
1593 trust the BIOS to get all its memory reservations and usages
1594 right. If you know your BIOS have problems beyond the
1595 default 64K area, you can set this to 640 to avoid using the
1596 entire low memory range.
1598 If you have doubts about the BIOS (e.g. suspend/resume does
1599 not work or there's kernel crashes after certain hardware
1600 hotplug events) then you might want to enable
1601 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1602 typical corruption patterns.
1604 Leave this to the default value of 64 if you are unsure.
1606 config MATH_EMULATION
1608 depends on MODIFY_LDT_SYSCALL
1609 prompt "Math emulation" if X86_32
1611 Linux can emulate a math coprocessor (used for floating point
1612 operations) if you don't have one. 486DX and Pentium processors have
1613 a math coprocessor built in, 486SX and 386 do not, unless you added
1614 a 487DX or 387, respectively. (The messages during boot time can
1615 give you some hints here ["man dmesg"].) Everyone needs either a
1616 coprocessor or this emulation.
1618 If you don't have a math coprocessor, you need to say Y here; if you
1619 say Y here even though you have a coprocessor, the coprocessor will
1620 be used nevertheless. (This behavior can be changed with the kernel
1621 command line option "no387", which comes handy if your coprocessor
1622 is broken. Try "man bootparam" or see the documentation of your boot
1623 loader (lilo or loadlin) about how to pass options to the kernel at
1624 boot time.) This means that it is a good idea to say Y here if you
1625 intend to use this kernel on different machines.
1627 More information about the internals of the Linux math coprocessor
1628 emulation can be found in <file:arch/x86/math-emu/README>.
1630 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1631 kernel, it won't hurt.
1635 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1637 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1638 the Memory Type Range Registers (MTRRs) may be used to control
1639 processor access to memory ranges. This is most useful if you have
1640 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1641 allows bus write transfers to be combined into a larger transfer
1642 before bursting over the PCI/AGP bus. This can increase performance
1643 of image write operations 2.5 times or more. Saying Y here creates a
1644 /proc/mtrr file which may be used to manipulate your processor's
1645 MTRRs. Typically the X server should use this.
1647 This code has a reasonably generic interface so that similar
1648 control registers on other processors can be easily supported
1651 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1652 Registers (ARRs) which provide a similar functionality to MTRRs. For
1653 these, the ARRs are used to emulate the MTRRs.
1654 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1655 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1656 write-combining. All of these processors are supported by this code
1657 and it makes sense to say Y here if you have one of them.
1659 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1660 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1661 can lead to all sorts of problems, so it's good to say Y here.
1663 You can safely say Y even if your machine doesn't have MTRRs, you'll
1664 just add about 9 KB to your kernel.
1666 See <file:Documentation/x86/mtrr.txt> for more information.
1668 config MTRR_SANITIZER
1670 prompt "MTRR cleanup support"
1673 Convert MTRR layout from continuous to discrete, so X drivers can
1674 add writeback entries.
1676 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1677 The largest mtrr entry size for a continuous block can be set with
1682 config MTRR_SANITIZER_ENABLE_DEFAULT
1683 int "MTRR cleanup enable value (0-1)"
1686 depends on MTRR_SANITIZER
1688 Enable mtrr cleanup default value
1690 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1691 int "MTRR cleanup spare reg num (0-7)"
1694 depends on MTRR_SANITIZER
1696 mtrr cleanup spare entries default, it can be changed via
1697 mtrr_spare_reg_nr=N on the kernel command line.
1701 prompt "x86 PAT support" if EXPERT
1704 Use PAT attributes to setup page level cache control.
1706 PATs are the modern equivalents of MTRRs and are much more
1707 flexible than MTRRs.
1709 Say N here if you see bootup problems (boot crash, boot hang,
1710 spontaneous reboots) or a non-working video driver.
1714 config ARCH_USES_PG_UNCACHED
1720 prompt "x86 architectural random number generator" if EXPERT
1722 Enable the x86 architectural RDRAND instruction
1723 (Intel Bull Mountain technology) to generate random numbers.
1724 If supported, this is a high bandwidth, cryptographically
1725 secure hardware random number generator.
1729 prompt "Supervisor Mode Access Prevention" if EXPERT
1731 Supervisor Mode Access Prevention (SMAP) is a security
1732 feature in newer Intel processors. There is a small
1733 performance cost if this enabled and turned on; there is
1734 also a small increase in the kernel size if this is enabled.
1738 config X86_INTEL_MPX
1739 prompt "Intel MPX (Memory Protection Extensions)"
1741 depends on CPU_SUP_INTEL
1743 MPX provides hardware features that can be used in
1744 conjunction with compiler-instrumented code to check
1745 memory references. It is designed to detect buffer
1746 overflow or underflow bugs.
1748 This option enables running applications which are
1749 instrumented or otherwise use MPX. It does not use MPX
1750 itself inside the kernel or to protect the kernel
1751 against bad memory references.
1753 Enabling this option will make the kernel larger:
1754 ~8k of kernel text and 36 bytes of data on a 64-bit
1755 defconfig. It adds a long to the 'mm_struct' which
1756 will increase the kernel memory overhead of each
1757 process and adds some branches to paths used during
1758 exec() and munmap().
1760 For details, see Documentation/x86/intel_mpx.txt
1764 config X86_INTEL_MEMORY_PROTECTION_KEYS
1765 prompt "Intel Memory Protection Keys"
1767 # Note: only available in 64-bit mode
1768 depends on CPU_SUP_INTEL && X86_64
1769 select ARCH_USES_HIGH_VMA_FLAGS
1770 select ARCH_HAS_PKEYS
1772 Memory Protection Keys provides a mechanism for enforcing
1773 page-based protections, but without requiring modification of the
1774 page tables when an application changes protection domains.
1776 For details, see Documentation/x86/protection-keys.txt
1781 bool "EFI runtime service support"
1784 select EFI_RUNTIME_WRAPPERS
1786 This enables the kernel to use EFI runtime services that are
1787 available (such as the EFI variable services).
1789 This option is only useful on systems that have EFI firmware.
1790 In addition, you should use the latest ELILO loader available
1791 at <http://elilo.sourceforge.net> in order to take advantage
1792 of EFI runtime services. However, even with this option, the
1793 resultant kernel should continue to boot on existing non-EFI
1797 bool "EFI stub support"
1798 depends on EFI && !X86_USE_3DNOW
1801 This kernel feature allows a bzImage to be loaded directly
1802 by EFI firmware without the use of a bootloader.
1804 See Documentation/efi-stub.txt for more information.
1807 bool "EFI mixed-mode support"
1808 depends on EFI_STUB && X86_64
1810 Enabling this feature allows a 64-bit kernel to be booted
1811 on a 32-bit firmware, provided that your CPU supports 64-bit
1814 Note that it is not possible to boot a mixed-mode enabled
1815 kernel via the EFI boot stub - a bootloader that supports
1816 the EFI handover protocol must be used.
1822 prompt "Enable seccomp to safely compute untrusted bytecode"
1824 This kernel feature is useful for number crunching applications
1825 that may need to compute untrusted bytecode during their
1826 execution. By using pipes or other transports made available to
1827 the process as file descriptors supporting the read/write
1828 syscalls, it's possible to isolate those applications in
1829 their own address space using seccomp. Once seccomp is
1830 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1831 and the task is only allowed to execute a few safe syscalls
1832 defined by each seccomp mode.
1834 If unsure, say Y. Only embedded should say N here.
1836 source kernel/Kconfig.hz
1839 bool "kexec system call"
1842 kexec is a system call that implements the ability to shutdown your
1843 current kernel, and to start another kernel. It is like a reboot
1844 but it is independent of the system firmware. And like a reboot
1845 you can start any kernel with it, not just Linux.
1847 The name comes from the similarity to the exec system call.
1849 It is an ongoing process to be certain the hardware in a machine
1850 is properly shutdown, so do not be surprised if this code does not
1851 initially work for you. As of this writing the exact hardware
1852 interface is strongly in flux, so no good recommendation can be
1856 bool "kexec file based system call"
1861 depends on CRYPTO_SHA256=y
1863 This is new version of kexec system call. This system call is
1864 file based and takes file descriptors as system call argument
1865 for kernel and initramfs as opposed to list of segments as
1866 accepted by previous system call.
1868 config KEXEC_VERIFY_SIG
1869 bool "Verify kernel signature during kexec_file_load() syscall"
1870 depends on KEXEC_FILE
1872 This option makes kernel signature verification mandatory for
1873 the kexec_file_load() syscall.
1875 In addition to that option, you need to enable signature
1876 verification for the corresponding kernel image type being
1877 loaded in order for this to work.
1879 config KEXEC_BZIMAGE_VERIFY_SIG
1880 bool "Enable bzImage signature verification support"
1881 depends on KEXEC_VERIFY_SIG
1882 depends on SIGNED_PE_FILE_VERIFICATION
1883 select SYSTEM_TRUSTED_KEYRING
1885 Enable bzImage signature verification support.
1888 bool "kernel crash dumps"
1889 depends on X86_64 || (X86_32 && HIGHMEM)
1891 Generate crash dump after being started by kexec.
1892 This should be normally only set in special crash dump kernels
1893 which are loaded in the main kernel with kexec-tools into
1894 a specially reserved region and then later executed after
1895 a crash by kdump/kexec. The crash dump kernel must be compiled
1896 to a memory address not used by the main kernel or BIOS using
1897 PHYSICAL_START, or it must be built as a relocatable image
1898 (CONFIG_RELOCATABLE=y).
1899 For more details see Documentation/kdump/kdump.txt
1903 depends on KEXEC && HIBERNATION
1905 Jump between original kernel and kexeced kernel and invoke
1906 code in physical address mode via KEXEC
1908 config PHYSICAL_START
1909 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1912 This gives the physical address where the kernel is loaded.
1914 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1915 bzImage will decompress itself to above physical address and
1916 run from there. Otherwise, bzImage will run from the address where
1917 it has been loaded by the boot loader and will ignore above physical
1920 In normal kdump cases one does not have to set/change this option
1921 as now bzImage can be compiled as a completely relocatable image
1922 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1923 address. This option is mainly useful for the folks who don't want
1924 to use a bzImage for capturing the crash dump and want to use a
1925 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1926 to be specifically compiled to run from a specific memory area
1927 (normally a reserved region) and this option comes handy.
1929 So if you are using bzImage for capturing the crash dump,
1930 leave the value here unchanged to 0x1000000 and set
1931 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1932 for capturing the crash dump change this value to start of
1933 the reserved region. In other words, it can be set based on
1934 the "X" value as specified in the "crashkernel=YM@XM"
1935 command line boot parameter passed to the panic-ed
1936 kernel. Please take a look at Documentation/kdump/kdump.txt
1937 for more details about crash dumps.
1939 Usage of bzImage for capturing the crash dump is recommended as
1940 one does not have to build two kernels. Same kernel can be used
1941 as production kernel and capture kernel. Above option should have
1942 gone away after relocatable bzImage support is introduced. But it
1943 is present because there are users out there who continue to use
1944 vmlinux for dump capture. This option should go away down the
1947 Don't change this unless you know what you are doing.
1950 bool "Build a relocatable kernel"
1953 This builds a kernel image that retains relocation information
1954 so it can be loaded someplace besides the default 1MB.
1955 The relocations tend to make the kernel binary about 10% larger,
1956 but are discarded at runtime.
1958 One use is for the kexec on panic case where the recovery kernel
1959 must live at a different physical address than the primary
1962 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1963 it has been loaded at and the compile time physical address
1964 (CONFIG_PHYSICAL_START) is used as the minimum location.
1966 config RANDOMIZE_BASE
1967 bool "Randomize the address of the kernel image (KASLR)"
1968 depends on RELOCATABLE
1971 In support of Kernel Address Space Layout Randomization (KASLR),
1972 this randomizes the physical address at which the kernel image
1973 is decompressed and the virtual address where the kernel
1974 image is mapped, as a security feature that deters exploit
1975 attempts relying on knowledge of the location of kernel
1978 On 64-bit, the kernel physical and virtual addresses are
1979 randomized separately. The physical address will be anywhere
1980 between 16MB and the top of physical memory (up to 64TB). The
1981 virtual address will be randomized from 16MB up to 1GB (9 bits
1982 of entropy). Note that this also reduces the memory space
1983 available to kernel modules from 1.5GB to 1GB.
1985 On 32-bit, the kernel physical and virtual addresses are
1986 randomized together. They will be randomized from 16MB up to
1987 512MB (8 bits of entropy).
1989 Entropy is generated using the RDRAND instruction if it is
1990 supported. If RDTSC is supported, its value is mixed into
1991 the entropy pool as well. If neither RDRAND nor RDTSC are
1992 supported, then entropy is read from the i8254 timer. The
1993 usable entropy is limited by the kernel being built using
1994 2GB addressing, and that PHYSICAL_ALIGN must be at a
1995 minimum of 2MB. As a result, only 10 bits of entropy are
1996 theoretically possible, but the implementations are further
1997 limited due to memory layouts.
2001 # Relocation on x86 needs some additional build support
2002 config X86_NEED_RELOCS
2004 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2006 config PHYSICAL_ALIGN
2007 hex "Alignment value to which kernel should be aligned"
2009 range 0x2000 0x1000000 if X86_32
2010 range 0x200000 0x1000000 if X86_64
2012 This value puts the alignment restrictions on physical address
2013 where kernel is loaded and run from. Kernel is compiled for an
2014 address which meets above alignment restriction.
2016 If bootloader loads the kernel at a non-aligned address and
2017 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2018 address aligned to above value and run from there.
2020 If bootloader loads the kernel at a non-aligned address and
2021 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2022 load address and decompress itself to the address it has been
2023 compiled for and run from there. The address for which kernel is
2024 compiled already meets above alignment restrictions. Hence the
2025 end result is that kernel runs from a physical address meeting
2026 above alignment restrictions.
2028 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2029 this value must be a multiple of 0x200000.
2031 Don't change this unless you know what you are doing.
2033 config RANDOMIZE_MEMORY
2034 bool "Randomize the kernel memory sections"
2036 depends on RANDOMIZE_BASE
2037 default RANDOMIZE_BASE
2039 Randomizes the base virtual address of kernel memory sections
2040 (physical memory mapping, vmalloc & vmemmap). This security feature
2041 makes exploits relying on predictable memory locations less reliable.
2043 The order of allocations remains unchanged. Entropy is generated in
2044 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2045 configuration have in average 30,000 different possible virtual
2046 addresses for each memory section.
2050 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2051 hex "Physical memory mapping padding" if EXPERT
2052 depends on RANDOMIZE_MEMORY
2053 default "0xa" if MEMORY_HOTPLUG
2055 range 0x1 0x40 if MEMORY_HOTPLUG
2058 Define the padding in terabytes added to the existing physical
2059 memory size during kernel memory randomization. It is useful
2060 for memory hotplug support but reduces the entropy available for
2061 address randomization.
2063 If unsure, leave at the default value.
2066 bool "Support for hot-pluggable CPUs"
2069 Say Y here to allow turning CPUs off and on. CPUs can be
2070 controlled through /sys/devices/system/cpu.
2071 ( Note: power management support will enable this option
2072 automatically on SMP systems. )
2073 Say N if you want to disable CPU hotplug.
2075 config BOOTPARAM_HOTPLUG_CPU0
2076 bool "Set default setting of cpu0_hotpluggable"
2078 depends on HOTPLUG_CPU
2080 Set whether default state of cpu0_hotpluggable is on or off.
2082 Say Y here to enable CPU0 hotplug by default. If this switch
2083 is turned on, there is no need to give cpu0_hotplug kernel
2084 parameter and the CPU0 hotplug feature is enabled by default.
2086 Please note: there are two known CPU0 dependencies if you want
2087 to enable the CPU0 hotplug feature either by this switch or by
2088 cpu0_hotplug kernel parameter.
2090 First, resume from hibernate or suspend always starts from CPU0.
2091 So hibernate and suspend are prevented if CPU0 is offline.
2093 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2094 offline if any interrupt can not migrate out of CPU0. There may
2095 be other CPU0 dependencies.
2097 Please make sure the dependencies are under your control before
2098 you enable this feature.
2100 Say N if you don't want to enable CPU0 hotplug feature by default.
2101 You still can enable the CPU0 hotplug feature at boot by kernel
2102 parameter cpu0_hotplug.
2104 config DEBUG_HOTPLUG_CPU0
2106 prompt "Debug CPU0 hotplug"
2107 depends on HOTPLUG_CPU
2109 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2110 soon as possible and boots up userspace with CPU0 offlined. User
2111 can online CPU0 back after boot time.
2113 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2114 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2115 compilation or giving cpu0_hotplug kernel parameter at boot.
2121 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2122 depends on COMPAT_32
2124 Certain buggy versions of glibc will crash if they are
2125 presented with a 32-bit vDSO that is not mapped at the address
2126 indicated in its segment table.
2128 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2129 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2130 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2131 the only released version with the bug, but OpenSUSE 9
2132 contains a buggy "glibc 2.3.2".
2134 The symptom of the bug is that everything crashes on startup, saying:
2135 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2137 Saying Y here changes the default value of the vdso32 boot
2138 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2139 This works around the glibc bug but hurts performance.
2141 If unsure, say N: if you are compiling your own kernel, you
2142 are unlikely to be using a buggy version of glibc.
2145 prompt "vsyscall table for legacy applications"
2147 default LEGACY_VSYSCALL_EMULATE
2149 Legacy user code that does not know how to find the vDSO expects
2150 to be able to issue three syscalls by calling fixed addresses in
2151 kernel space. Since this location is not randomized with ASLR,
2152 it can be used to assist security vulnerability exploitation.
2154 This setting can be changed at boot time via the kernel command
2155 line parameter vsyscall=[native|emulate|none].
2157 On a system with recent enough glibc (2.14 or newer) and no
2158 static binaries, you can say None without a performance penalty
2159 to improve security.
2161 If unsure, select "Emulate".
2163 config LEGACY_VSYSCALL_NATIVE
2166 Actual executable code is located in the fixed vsyscall
2167 address mapping, implementing time() efficiently. Since
2168 this makes the mapping executable, it can be used during
2169 security vulnerability exploitation (traditionally as
2170 ROP gadgets). This configuration is not recommended.
2172 config LEGACY_VSYSCALL_EMULATE
2175 The kernel traps and emulates calls into the fixed
2176 vsyscall address mapping. This makes the mapping
2177 non-executable, but it still contains known contents,
2178 which could be used in certain rare security vulnerability
2179 exploits. This configuration is recommended when userspace
2180 still uses the vsyscall area.
2182 config LEGACY_VSYSCALL_NONE
2185 There will be no vsyscall mapping at all. This will
2186 eliminate any risk of ASLR bypass due to the vsyscall
2187 fixed address mapping. Attempts to use the vsyscalls
2188 will be reported to dmesg, so that either old or
2189 malicious userspace programs can be identified.
2194 bool "Built-in kernel command line"
2196 Allow for specifying boot arguments to the kernel at
2197 build time. On some systems (e.g. embedded ones), it is
2198 necessary or convenient to provide some or all of the
2199 kernel boot arguments with the kernel itself (that is,
2200 to not rely on the boot loader to provide them.)
2202 To compile command line arguments into the kernel,
2203 set this option to 'Y', then fill in the
2204 boot arguments in CONFIG_CMDLINE.
2206 Systems with fully functional boot loaders (i.e. non-embedded)
2207 should leave this option set to 'N'.
2210 string "Built-in kernel command string"
2211 depends on CMDLINE_BOOL
2214 Enter arguments here that should be compiled into the kernel
2215 image and used at boot time. If the boot loader provides a
2216 command line at boot time, it is appended to this string to
2217 form the full kernel command line, when the system boots.
2219 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2220 change this behavior.
2222 In most cases, the command line (whether built-in or provided
2223 by the boot loader) should specify the device for the root
2226 config CMDLINE_OVERRIDE
2227 bool "Built-in command line overrides boot loader arguments"
2228 depends on CMDLINE_BOOL
2230 Set this option to 'Y' to have the kernel ignore the boot loader
2231 command line, and use ONLY the built-in command line.
2233 This is used to work around broken boot loaders. This should
2234 be set to 'N' under normal conditions.
2236 config MODIFY_LDT_SYSCALL
2237 bool "Enable the LDT (local descriptor table)" if EXPERT
2240 Linux can allow user programs to install a per-process x86
2241 Local Descriptor Table (LDT) using the modify_ldt(2) system
2242 call. This is required to run 16-bit or segmented code such as
2243 DOSEMU or some Wine programs. It is also used by some very old
2244 threading libraries.
2246 Enabling this feature adds a small amount of overhead to
2247 context switches and increases the low-level kernel attack
2248 surface. Disabling it removes the modify_ldt(2) system call.
2250 Saying 'N' here may make sense for embedded or server kernels.
2252 source "kernel/livepatch/Kconfig"
2256 config ARCH_ENABLE_MEMORY_HOTPLUG
2258 depends on X86_64 || (X86_32 && HIGHMEM)
2260 config ARCH_ENABLE_MEMORY_HOTREMOVE
2262 depends on MEMORY_HOTPLUG
2264 config USE_PERCPU_NUMA_NODE_ID
2268 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2270 depends on X86_64 || X86_PAE
2272 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2274 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2276 menu "Power management and ACPI options"
2278 config ARCH_HIBERNATION_HEADER
2280 depends on X86_64 && HIBERNATION
2282 source "kernel/power/Kconfig"
2284 source "drivers/acpi/Kconfig"
2286 source "drivers/sfi/Kconfig"
2293 tristate "APM (Advanced Power Management) BIOS support"
2294 depends on X86_32 && PM_SLEEP
2296 APM is a BIOS specification for saving power using several different
2297 techniques. This is mostly useful for battery powered laptops with
2298 APM compliant BIOSes. If you say Y here, the system time will be
2299 reset after a RESUME operation, the /proc/apm device will provide
2300 battery status information, and user-space programs will receive
2301 notification of APM "events" (e.g. battery status change).
2303 If you select "Y" here, you can disable actual use of the APM
2304 BIOS by passing the "apm=off" option to the kernel at boot time.
2306 Note that the APM support is almost completely disabled for
2307 machines with more than one CPU.
2309 In order to use APM, you will need supporting software. For location
2310 and more information, read <file:Documentation/power/apm-acpi.txt>
2311 and the Battery Powered Linux mini-HOWTO, available from
2312 <http://www.tldp.org/docs.html#howto>.
2314 This driver does not spin down disk drives (see the hdparm(8)
2315 manpage ("man 8 hdparm") for that), and it doesn't turn off
2316 VESA-compliant "green" monitors.
2318 This driver does not support the TI 4000M TravelMate and the ACER
2319 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2320 desktop machines also don't have compliant BIOSes, and this driver
2321 may cause those machines to panic during the boot phase.
2323 Generally, if you don't have a battery in your machine, there isn't
2324 much point in using this driver and you should say N. If you get
2325 random kernel OOPSes or reboots that don't seem to be related to
2326 anything, try disabling/enabling this option (or disabling/enabling
2329 Some other things you should try when experiencing seemingly random,
2332 1) make sure that you have enough swap space and that it is
2334 2) pass the "no-hlt" option to the kernel
2335 3) switch on floating point emulation in the kernel and pass
2336 the "no387" option to the kernel
2337 4) pass the "floppy=nodma" option to the kernel
2338 5) pass the "mem=4M" option to the kernel (thereby disabling
2339 all but the first 4 MB of RAM)
2340 6) make sure that the CPU is not over clocked.
2341 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2342 8) disable the cache from your BIOS settings
2343 9) install a fan for the video card or exchange video RAM
2344 10) install a better fan for the CPU
2345 11) exchange RAM chips
2346 12) exchange the motherboard.
2348 To compile this driver as a module, choose M here: the
2349 module will be called apm.
2353 config APM_IGNORE_USER_SUSPEND
2354 bool "Ignore USER SUSPEND"
2356 This option will ignore USER SUSPEND requests. On machines with a
2357 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2358 series notebooks, it is necessary to say Y because of a BIOS bug.
2360 config APM_DO_ENABLE
2361 bool "Enable PM at boot time"
2363 Enable APM features at boot time. From page 36 of the APM BIOS
2364 specification: "When disabled, the APM BIOS does not automatically
2365 power manage devices, enter the Standby State, enter the Suspend
2366 State, or take power saving steps in response to CPU Idle calls."
2367 This driver will make CPU Idle calls when Linux is idle (unless this
2368 feature is turned off -- see "Do CPU IDLE calls", below). This
2369 should always save battery power, but more complicated APM features
2370 will be dependent on your BIOS implementation. You may need to turn
2371 this option off if your computer hangs at boot time when using APM
2372 support, or if it beeps continuously instead of suspending. Turn
2373 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2374 T400CDT. This is off by default since most machines do fine without
2379 bool "Make CPU Idle calls when idle"
2381 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2382 On some machines, this can activate improved power savings, such as
2383 a slowed CPU clock rate, when the machine is idle. These idle calls
2384 are made after the idle loop has run for some length of time (e.g.,
2385 333 mS). On some machines, this will cause a hang at boot time or
2386 whenever the CPU becomes idle. (On machines with more than one CPU,
2387 this option does nothing.)
2389 config APM_DISPLAY_BLANK
2390 bool "Enable console blanking using APM"
2392 Enable console blanking using the APM. Some laptops can use this to
2393 turn off the LCD backlight when the screen blanker of the Linux
2394 virtual console blanks the screen. Note that this is only used by
2395 the virtual console screen blanker, and won't turn off the backlight
2396 when using the X Window system. This also doesn't have anything to
2397 do with your VESA-compliant power-saving monitor. Further, this
2398 option doesn't work for all laptops -- it might not turn off your
2399 backlight at all, or it might print a lot of errors to the console,
2400 especially if you are using gpm.
2402 config APM_ALLOW_INTS
2403 bool "Allow interrupts during APM BIOS calls"
2405 Normally we disable external interrupts while we are making calls to
2406 the APM BIOS as a measure to lessen the effects of a badly behaving
2407 BIOS implementation. The BIOS should reenable interrupts if it
2408 needs to. Unfortunately, some BIOSes do not -- especially those in
2409 many of the newer IBM Thinkpads. If you experience hangs when you
2410 suspend, try setting this to Y. Otherwise, say N.
2414 source "drivers/cpufreq/Kconfig"
2416 source "drivers/cpuidle/Kconfig"
2418 source "drivers/idle/Kconfig"
2423 menu "Bus options (PCI etc.)"
2429 Find out whether you have a PCI motherboard. PCI is the name of a
2430 bus system, i.e. the way the CPU talks to the other stuff inside
2431 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2432 VESA. If you have PCI, say Y, otherwise N.
2435 prompt "PCI access mode"
2436 depends on X86_32 && PCI
2439 On PCI systems, the BIOS can be used to detect the PCI devices and
2440 determine their configuration. However, some old PCI motherboards
2441 have BIOS bugs and may crash if this is done. Also, some embedded
2442 PCI-based systems don't have any BIOS at all. Linux can also try to
2443 detect the PCI hardware directly without using the BIOS.
2445 With this option, you can specify how Linux should detect the
2446 PCI devices. If you choose "BIOS", the BIOS will be used,
2447 if you choose "Direct", the BIOS won't be used, and if you
2448 choose "MMConfig", then PCI Express MMCONFIG will be used.
2449 If you choose "Any", the kernel will try MMCONFIG, then the
2450 direct access method and falls back to the BIOS if that doesn't
2451 work. If unsure, go with the default, which is "Any".
2456 config PCI_GOMMCONFIG
2473 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2475 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2478 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2482 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2486 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2490 depends on PCI && XEN
2498 bool "Support mmconfig PCI config space access"
2499 depends on X86_64 && PCI && ACPI
2501 config PCI_CNB20LE_QUIRK
2502 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2505 Read the PCI windows out of the CNB20LE host bridge. This allows
2506 PCI hotplug to work on systems with the CNB20LE chipset which do
2509 There's no public spec for this chipset, and this functionality
2510 is known to be incomplete.
2512 You should say N unless you know you need this.
2514 source "drivers/pci/Kconfig"
2517 bool "ISA-style bus support on modern systems" if EXPERT
2520 Enables ISA-style drivers on modern systems. This is necessary to
2521 support PC/104 devices on X86_64 platforms.
2525 # x86_64 have no ISA slots, but can have ISA-style DMA.
2527 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2530 Enables ISA-style DMA support for devices requiring such controllers.
2538 Find out whether you have ISA slots on your motherboard. ISA is the
2539 name of a bus system, i.e. the way the CPU talks to the other stuff
2540 inside your box. Other bus systems are PCI, EISA, MicroChannel
2541 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2542 newer boards don't support it. If you have ISA, say Y, otherwise N.
2548 The Extended Industry Standard Architecture (EISA) bus was
2549 developed as an open alternative to the IBM MicroChannel bus.
2551 The EISA bus provided some of the features of the IBM MicroChannel
2552 bus while maintaining backward compatibility with cards made for
2553 the older ISA bus. The EISA bus saw limited use between 1988 and
2554 1995 when it was made obsolete by the PCI bus.
2556 Say Y here if you are building a kernel for an EISA-based machine.
2560 source "drivers/eisa/Kconfig"
2563 tristate "NatSemi SCx200 support"
2565 This provides basic support for National Semiconductor's
2566 (now AMD's) Geode processors. The driver probes for the
2567 PCI-IDs of several on-chip devices, so its a good dependency
2568 for other scx200_* drivers.
2570 If compiled as a module, the driver is named scx200.
2572 config SCx200HR_TIMER
2573 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2577 This driver provides a clocksource built upon the on-chip
2578 27MHz high-resolution timer. Its also a workaround for
2579 NSC Geode SC-1100's buggy TSC, which loses time when the
2580 processor goes idle (as is done by the scheduler). The
2581 other workaround is idle=poll boot option.
2584 bool "One Laptop Per Child support"
2591 Add support for detecting the unique features of the OLPC
2595 bool "OLPC XO-1 Power Management"
2596 depends on OLPC && MFD_CS5535 && PM_SLEEP
2599 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2602 bool "OLPC XO-1 Real Time Clock"
2603 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2605 Add support for the XO-1 real time clock, which can be used as a
2606 programmable wakeup source.
2609 bool "OLPC XO-1 SCI extras"
2610 depends on OLPC && OLPC_XO1_PM
2616 Add support for SCI-based features of the OLPC XO-1 laptop:
2617 - EC-driven system wakeups
2621 - AC adapter status updates
2622 - Battery status updates
2624 config OLPC_XO15_SCI
2625 bool "OLPC XO-1.5 SCI extras"
2626 depends on OLPC && ACPI
2629 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2630 - EC-driven system wakeups
2631 - AC adapter status updates
2632 - Battery status updates
2635 bool "PCEngines ALIX System Support (LED setup)"
2638 This option enables system support for the PCEngines ALIX.
2639 At present this just sets up LEDs for GPIO control on
2640 ALIX2/3/6 boards. However, other system specific setup should
2643 Note: You must still enable the drivers for GPIO and LED support
2644 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2646 Note: You have to set alix.force=1 for boards with Award BIOS.
2649 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2652 This option enables system support for the Soekris Engineering net5501.
2655 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2659 This option enables system support for the Traverse Technologies GEOS.
2662 bool "Technologic Systems TS-5500 platform support"
2664 select CHECK_SIGNATURE
2668 This option enables system support for the Technologic Systems TS-5500.
2674 depends on CPU_SUP_AMD && PCI
2676 source "drivers/pcmcia/Kconfig"
2679 tristate "RapidIO support"
2683 If enabled this option will include drivers and the core
2684 infrastructure code to support RapidIO interconnect devices.
2686 source "drivers/rapidio/Kconfig"
2689 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2691 Firmwares often provide initial graphics framebuffers so the BIOS,
2692 bootloader or kernel can show basic video-output during boot for
2693 user-guidance and debugging. Historically, x86 used the VESA BIOS
2694 Extensions and EFI-framebuffers for this, which are mostly limited
2696 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2697 framebuffers so the new generic system-framebuffer drivers can be
2698 used on x86. If the framebuffer is not compatible with the generic
2699 modes, it is adverticed as fallback platform framebuffer so legacy
2700 drivers like efifb, vesafb and uvesafb can pick it up.
2701 If this option is not selected, all system framebuffers are always
2702 marked as fallback platform framebuffers as usual.
2704 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2705 not be able to pick up generic system framebuffers if this option
2706 is selected. You are highly encouraged to enable simplefb as
2707 replacement if you select this option. simplefb can correctly deal
2708 with generic system framebuffers. But you should still keep vesafb
2709 and others enabled as fallback if a system framebuffer is
2710 incompatible with simplefb.
2717 menu "Executable file formats / Emulations"
2719 source "fs/Kconfig.binfmt"
2721 config IA32_EMULATION
2722 bool "IA32 Emulation"
2724 select ARCH_WANT_OLD_COMPAT_IPC
2726 select COMPAT_BINFMT_ELF
2727 select COMPAT_OLD_SIGACTION
2729 Include code to run legacy 32-bit programs under a
2730 64-bit kernel. You should likely turn this on, unless you're
2731 100% sure that you don't have any 32-bit programs left.
2734 tristate "IA32 a.out support"
2735 depends on IA32_EMULATION
2737 Support old a.out binaries in the 32bit emulation.
2740 bool "x32 ABI for 64-bit mode"
2743 Include code to run binaries for the x32 native 32-bit ABI
2744 for 64-bit processors. An x32 process gets access to the
2745 full 64-bit register file and wide data path while leaving
2746 pointers at 32 bits for smaller memory footprint.
2748 You will need a recent binutils (2.22 or later) with
2749 elf32_x86_64 support enabled to compile a kernel with this
2754 depends on IA32_EMULATION || X86_32
2756 select OLD_SIGSUSPEND3
2760 depends on IA32_EMULATION || X86_X32
2763 config COMPAT_FOR_U64_ALIGNMENT
2766 config SYSVIPC_COMPAT
2778 config HAVE_ATOMIC_IOMAP
2782 config X86_DEV_DMA_OPS
2784 depends on X86_64 || STA2X11
2786 config X86_DMA_REMAP
2790 source "net/Kconfig"
2792 source "drivers/Kconfig"
2794 source "drivers/firmware/Kconfig"
2798 source "arch/x86/Kconfig.debug"
2800 source "security/Kconfig"
2802 source "crypto/Kconfig"
2804 source "arch/x86/kvm/Kconfig"
2806 source "lib/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob