3 bool "64-bit kernel" if ARCH = "x86"
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
20 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
21 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
23 select ARCH_CLOCKSOURCE_DATA
24 select ARCH_DISCARD_MEMBLOCK
25 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
26 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
27 select ARCH_HAS_DEVMEM_IS_ALLOWED
28 select ARCH_HAS_ELF_RANDOMIZE
29 select ARCH_HAS_FAST_MULTIPLIER
30 select ARCH_HAS_GCOV_PROFILE_ALL
31 select ARCH_HAS_PMEM_API if X86_64
32 select ARCH_HAS_MMIO_FLUSH
33 select ARCH_HAS_SG_CHAIN
34 select ARCH_HAS_UBSAN_SANITIZE_ALL
35 select ARCH_HAVE_NMI_SAFE_CMPXCHG
36 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
37 select ARCH_MIGHT_HAVE_PC_PARPORT
38 select ARCH_MIGHT_HAVE_PC_SERIO
39 select ARCH_SUPPORTS_ATOMIC_RMW
40 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
41 select ARCH_SUPPORTS_INT128 if X86_64
42 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
43 select ARCH_USE_BUILTIN_BSWAP
44 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
45 select ARCH_USE_QUEUED_RWLOCKS
46 select ARCH_USE_QUEUED_SPINLOCKS
47 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
48 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
49 select ARCH_WANT_FRAME_POINTERS
50 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
51 select ARCH_WANT_OPTIONAL_GPIOLIB
52 select BUILDTIME_EXTABLE_SORT
54 select CLKSRC_I8253 if X86_32
55 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
56 select CLOCKSOURCE_WATCHDOG
57 select CLONE_BACKWARDS if X86_32
58 select COMPAT_OLD_SIGACTION if IA32_EMULATION
59 select DCACHE_WORD_ACCESS
60 select EDAC_ATOMIC_SCRUB
62 select GENERIC_CLOCKEVENTS
63 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
64 select GENERIC_CLOCKEVENTS_MIN_ADJUST
65 select GENERIC_CMOS_UPDATE
66 select GENERIC_CPU_AUTOPROBE
67 select GENERIC_EARLY_IOREMAP
68 select GENERIC_FIND_FIRST_BIT
70 select GENERIC_IRQ_PROBE
71 select GENERIC_IRQ_SHOW
72 select GENERIC_PENDING_IRQ if SMP
73 select GENERIC_SMP_IDLE_THREAD
74 select GENERIC_STRNCPY_FROM_USER
75 select GENERIC_STRNLEN_USER
76 select GENERIC_TIME_VSYSCALL
77 select HAVE_ACPI_APEI if ACPI
78 select HAVE_ACPI_APEI_NMI if ACPI
79 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
80 select HAVE_AOUT if X86_32
81 select HAVE_ARCH_AUDITSYSCALL
82 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
83 select HAVE_ARCH_JUMP_LABEL
84 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
86 select HAVE_ARCH_KMEMCHECK
87 select HAVE_ARCH_MMAP_RND_BITS if MMU
88 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
89 select HAVE_ARCH_SECCOMP_FILTER
90 select HAVE_ARCH_SOFT_DIRTY if X86_64
91 select HAVE_ARCH_TRACEHOOK
92 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
93 select HAVE_BPF_JIT if X86_64
94 select HAVE_CC_STACKPROTECTOR
95 select HAVE_CMPXCHG_DOUBLE
96 select HAVE_CMPXCHG_LOCAL
97 select HAVE_CONTEXT_TRACKING if X86_64
98 select HAVE_COPY_THREAD_TLS
99 select HAVE_C_RECORDMCOUNT
100 select HAVE_DEBUG_KMEMLEAK
101 select HAVE_DEBUG_STACKOVERFLOW
102 select HAVE_DMA_API_DEBUG
103 select HAVE_DMA_CONTIGUOUS
104 select HAVE_DYNAMIC_FTRACE
105 select HAVE_DYNAMIC_FTRACE_WITH_REGS
106 select HAVE_EFFICIENT_UNALIGNED_ACCESS
107 select HAVE_FENTRY if X86_64
108 select HAVE_FTRACE_MCOUNT_RECORD
109 select HAVE_FUNCTION_GRAPH_FP_TEST
110 select HAVE_FUNCTION_GRAPH_TRACER
111 select HAVE_FUNCTION_TRACER
112 select HAVE_GENERIC_DMA_COHERENT if X86_32
113 select HAVE_HW_BREAKPOINT
115 select HAVE_IOREMAP_PROT
116 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
117 select HAVE_IRQ_TIME_ACCOUNTING
118 select HAVE_KERNEL_BZIP2
119 select HAVE_KERNEL_GZIP
120 select HAVE_KERNEL_LZ4
121 select HAVE_KERNEL_LZMA
122 select HAVE_KERNEL_LZO
123 select HAVE_KERNEL_XZ
125 select HAVE_KPROBES_ON_FTRACE
126 select HAVE_KRETPROBES
128 select HAVE_LIVEPATCH if X86_64
130 select HAVE_MEMBLOCK_NODE_MAP
131 select HAVE_MIXED_BREAKPOINTS_REGS
133 select HAVE_OPTPROBES
134 select HAVE_PCSPKR_PLATFORM
135 select HAVE_PERF_EVENTS
136 select HAVE_PERF_EVENTS_NMI
137 select HAVE_PERF_REGS
138 select HAVE_PERF_USER_STACK_DUMP
139 select HAVE_REGS_AND_STACK_ACCESS_API
140 select HAVE_SYSCALL_TRACEPOINTS
141 select HAVE_UID16 if X86_32 || IA32_EMULATION
142 select HAVE_UNSTABLE_SCHED_CLOCK
143 select HAVE_USER_RETURN_NOTIFIER
144 select IRQ_FORCED_THREADING
145 select MODULES_USE_ELF_RELA if X86_64
146 select MODULES_USE_ELF_REL if X86_32
147 select OLD_SIGACTION if X86_32
148 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
153 select SYSCTL_EXCEPTION_TRACE
154 select USER_STACKTRACE_SUPPORT
156 select X86_DEV_DMA_OPS if X86_64
157 select X86_FEATURE_NAMES if PROC_FS
158 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
160 config INSTRUCTION_DECODER
162 depends on KPROBES || PERF_EVENTS || UPROBES
164 config PERF_EVENTS_INTEL_UNCORE
166 depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
170 default "elf32-i386" if X86_32
171 default "elf64-x86-64" if X86_64
173 config ARCH_DEFCONFIG
175 default "arch/x86/configs/i386_defconfig" if X86_32
176 default "arch/x86/configs/x86_64_defconfig" if X86_64
178 config LOCKDEP_SUPPORT
181 config STACKTRACE_SUPPORT
187 config ARCH_MMAP_RND_BITS_MIN
191 config ARCH_MMAP_RND_BITS_MAX
195 config ARCH_MMAP_RND_COMPAT_BITS_MIN
198 config ARCH_MMAP_RND_COMPAT_BITS_MAX
204 config NEED_DMA_MAP_STATE
206 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
208 config NEED_SG_DMA_LENGTH
211 config GENERIC_ISA_DMA
213 depends on ISA_DMA_API
218 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
220 config GENERIC_BUG_RELATIVE_POINTERS
223 config GENERIC_HWEIGHT
226 config ARCH_MAY_HAVE_PC_FDC
228 depends on ISA_DMA_API
230 config RWSEM_XCHGADD_ALGORITHM
233 config GENERIC_CALIBRATE_DELAY
236 config ARCH_HAS_CPU_RELAX
239 config ARCH_HAS_CACHE_LINE_SIZE
242 config HAVE_SETUP_PER_CPU_AREA
245 config NEED_PER_CPU_EMBED_FIRST_CHUNK
248 config NEED_PER_CPU_PAGE_FIRST_CHUNK
251 config ARCH_HIBERNATION_POSSIBLE
254 config ARCH_SUSPEND_POSSIBLE
257 config ARCH_WANT_HUGE_PMD_SHARE
260 config ARCH_WANT_GENERAL_HUGETLB
269 config ARCH_SUPPORTS_OPTIMIZED_INLINING
272 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
275 config KASAN_SHADOW_OFFSET
278 default 0xdffffc0000000000
280 config HAVE_INTEL_TXT
282 depends on INTEL_IOMMU && ACPI
286 depends on X86_32 && SMP
290 depends on X86_64 && SMP
292 config X86_32_LAZY_GS
294 depends on X86_32 && !CC_STACKPROTECTOR
296 config ARCH_HWEIGHT_CFLAGS
298 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
299 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
301 config ARCH_SUPPORTS_UPROBES
304 config FIX_EARLYCON_MEM
307 config PGTABLE_LEVELS
313 source "init/Kconfig"
314 source "kernel/Kconfig.freezer"
316 menu "Processor type and features"
319 bool "DMA memory allocation support" if EXPERT
322 DMA memory allocation support allows devices with less than 32-bit
323 addressing to allocate within the first 16MB of address space.
324 Disable if no such devices will be used.
329 bool "Symmetric multi-processing support"
331 This enables support for systems with more than one CPU. If you have
332 a system with only one CPU, say N. If you have a system with more
335 If you say N here, the kernel will run on uni- and multiprocessor
336 machines, but will use only one CPU of a multiprocessor machine. If
337 you say Y here, the kernel will run on many, but not all,
338 uniprocessor machines. On a uniprocessor machine, the kernel
339 will run faster if you say N here.
341 Note that if you say Y here and choose architecture "586" or
342 "Pentium" under "Processor family", the kernel will not work on 486
343 architectures. Similarly, multiprocessor kernels for the "PPro"
344 architecture may not work on all Pentium based boards.
346 People using multiprocessor machines who say Y here should also say
347 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
348 Management" code will be disabled if you say Y here.
350 See also <file:Documentation/x86/i386/IO-APIC.txt>,
351 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
352 <http://www.tldp.org/docs.html#howto>.
354 If you don't know what to do here, say N.
356 config X86_FEATURE_NAMES
357 bool "Processor feature human-readable names" if EMBEDDED
360 This option compiles in a table of x86 feature bits and corresponding
361 names. This is required to support /proc/cpuinfo and a few kernel
362 messages. You can disable this to save space, at the expense of
363 making those few kernel messages show numeric feature bits instead.
367 config X86_FAST_FEATURE_TESTS
368 bool "Fast CPU feature tests" if EMBEDDED
371 Some fast-paths in the kernel depend on the capabilities of the CPU.
372 Say Y here for the kernel to patch in the appropriate code at runtime
373 based on the capabilities of the CPU. The infrastructure for patching
374 code at runtime takes up some additional space; space-constrained
375 embedded systems may wish to say N here to produce smaller, slightly
379 bool "Support x2apic"
380 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
382 This enables x2apic support on CPUs that have this feature.
384 This allows 32-bit apic IDs (so it can support very large systems),
385 and accesses the local apic via MSRs not via mmio.
387 If you don't know what to do here, say N.
390 bool "Enable MPS table" if ACPI || SFI
392 depends on X86_LOCAL_APIC
394 For old smp systems that do not have proper acpi support. Newer systems
395 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
398 bool "Support for big SMP systems with more than 8 CPUs"
399 depends on X86_32 && SMP
401 This option is needed for the systems that have more than 8 CPUs
405 depends on X86_GOLDFISH
408 config X86_EXTENDED_PLATFORM
409 bool "Support for extended (non-PC) x86 platforms"
412 If you disable this option then the kernel will only support
413 standard PC platforms. (which covers the vast majority of
416 If you enable this option then you'll be able to select support
417 for the following (non-PC) 32 bit x86 platforms:
418 Goldfish (Android emulator)
421 SGI 320/540 (Visual Workstation)
422 STA2X11-based (e.g. Northville)
423 Moorestown MID devices
425 If you have one of these systems, or if you want to build a
426 generic distribution kernel, say Y here - otherwise say N.
430 config X86_EXTENDED_PLATFORM
431 bool "Support for extended (non-PC) x86 platforms"
434 If you disable this option then the kernel will only support
435 standard PC platforms. (which covers the vast majority of
438 If you enable this option then you'll be able to select support
439 for the following (non-PC) 64 bit x86 platforms:
444 If you have one of these systems, or if you want to build a
445 generic distribution kernel, say Y here - otherwise say N.
447 # This is an alphabetically sorted list of 64 bit extended platforms
448 # Please maintain the alphabetic order if and when there are additions
450 bool "Numascale NumaChip"
452 depends on X86_EXTENDED_PLATFORM
455 depends on X86_X2APIC
456 depends on PCI_MMCONFIG
458 Adds support for Numascale NumaChip large-SMP systems. Needed to
459 enable more than ~168 cores.
460 If you don't have one of these, you should say N here.
464 select HYPERVISOR_GUEST
466 depends on X86_64 && PCI
467 depends on X86_EXTENDED_PLATFORM
470 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
471 supposed to run on these EM64T-based machines. Only choose this option
472 if you have one of these machines.
475 bool "SGI Ultraviolet"
477 depends on X86_EXTENDED_PLATFORM
480 depends on X86_X2APIC
483 This option is needed in order to support SGI Ultraviolet systems.
484 If you don't have one of these, you should say N here.
486 # Following is an alphabetically sorted list of 32 bit extended platforms
487 # Please maintain the alphabetic order if and when there are additions
490 bool "Goldfish (Virtual Platform)"
491 depends on X86_EXTENDED_PLATFORM
493 Enable support for the Goldfish virtual platform used primarily
494 for Android development. Unless you are building for the Android
495 Goldfish emulator say N here.
498 bool "CE4100 TV platform"
500 depends on PCI_GODIRECT
501 depends on X86_IO_APIC
503 depends on X86_EXTENDED_PLATFORM
504 select X86_REBOOTFIXUPS
506 select OF_EARLY_FLATTREE
508 Select for the Intel CE media processor (CE4100) SOC.
509 This option compiles in support for the CE4100 SOC for settop
510 boxes and media devices.
513 bool "Intel MID platform support"
514 depends on X86_EXTENDED_PLATFORM
515 depends on X86_PLATFORM_DEVICES
517 depends on X86_64 || (PCI_GOANY && X86_32)
518 depends on X86_IO_APIC
524 select MFD_INTEL_MSIC
526 Select to build a kernel capable of supporting Intel MID (Mobile
527 Internet Device) platform systems which do not have the PCI legacy
528 interfaces. If you are building for a PC class system say N here.
530 Intel MID platforms are based on an Intel processor and chipset which
531 consume less power than most of the x86 derivatives.
533 config X86_INTEL_QUARK
534 bool "Intel Quark platform support"
536 depends on X86_EXTENDED_PLATFORM
537 depends on X86_PLATFORM_DEVICES
541 depends on X86_IO_APIC
546 Select to include support for Quark X1000 SoC.
547 Say Y here if you have a Quark based system such as the Arduino
548 compatible Intel Galileo.
550 config X86_INTEL_LPSS
551 bool "Intel Low Power Subsystem Support"
552 depends on X86 && ACPI
557 Select to build support for Intel Low Power Subsystem such as
558 found on Intel Lynxpoint PCH. Selecting this option enables
559 things like clock tree (common clock framework) and pincontrol
560 which are needed by the LPSS peripheral drivers.
562 config X86_AMD_PLATFORM_DEVICE
563 bool "AMD ACPI2Platform devices support"
568 Select to interpret AMD specific ACPI device to platform device
569 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
570 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
571 implemented under PINCTRL subsystem.
574 tristate "Intel SoC IOSF Sideband support for SoC platforms"
577 This option enables sideband register access support for Intel SoC
578 platforms. On these platforms the IOSF sideband is used in lieu of
579 MSR's for some register accesses, mostly but not limited to thermal
580 and power. Drivers may query the availability of this device to
581 determine if they need the sideband in order to work on these
582 platforms. The sideband is available on the following SoC products.
583 This list is not meant to be exclusive.
588 You should say Y if you are running a kernel on one of these SoC's.
590 config IOSF_MBI_DEBUG
591 bool "Enable IOSF sideband access through debugfs"
592 depends on IOSF_MBI && DEBUG_FS
594 Select this option to expose the IOSF sideband access registers (MCR,
595 MDR, MCRX) through debugfs to write and read register information from
596 different units on the SoC. This is most useful for obtaining device
597 state information for debug and analysis. As this is a general access
598 mechanism, users of this option would have specific knowledge of the
599 device they want to access.
601 If you don't require the option or are in doubt, say N.
604 bool "RDC R-321x SoC"
606 depends on X86_EXTENDED_PLATFORM
608 select X86_REBOOTFIXUPS
610 This option is needed for RDC R-321x system-on-chip, also known
612 If you don't have one of these chips, you should say N here.
614 config X86_32_NON_STANDARD
615 bool "Support non-standard 32-bit SMP architectures"
616 depends on X86_32 && SMP
617 depends on X86_EXTENDED_PLATFORM
619 This option compiles in the bigsmp and STA2X11 default
620 subarchitectures. It is intended for a generic binary
621 kernel. If you select them all, kernel will probe it one by
622 one and will fallback to default.
624 # Alphabetically sorted list of Non standard 32 bit platforms
626 config X86_SUPPORTS_MEMORY_FAILURE
628 # MCE code calls memory_failure():
630 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
631 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
632 depends on X86_64 || !SPARSEMEM
633 select ARCH_SUPPORTS_MEMORY_FAILURE
636 bool "STA2X11 Companion Chip Support"
637 depends on X86_32_NON_STANDARD && PCI
638 select X86_DEV_DMA_OPS
642 select ARCH_REQUIRE_GPIOLIB
645 This adds support for boards based on the STA2X11 IO-Hub,
646 a.k.a. "ConneXt". The chip is used in place of the standard
647 PC chipset, so all "standard" peripherals are missing. If this
648 option is selected the kernel will still be able to boot on
649 standard PC machines.
652 tristate "Eurobraille/Iris poweroff module"
655 The Iris machines from EuroBraille do not have APM or ACPI support
656 to shut themselves down properly. A special I/O sequence is
657 needed to do so, which is what this module does at
660 This is only for Iris machines from EuroBraille.
664 config SCHED_OMIT_FRAME_POINTER
666 prompt "Single-depth WCHAN output"
669 Calculate simpler /proc/<PID>/wchan values. If this option
670 is disabled then wchan values will recurse back to the
671 caller function. This provides more accurate wchan values,
672 at the expense of slightly more scheduling overhead.
674 If in doubt, say "Y".
676 menuconfig HYPERVISOR_GUEST
677 bool "Linux guest support"
679 Say Y here to enable options for running Linux under various hyper-
680 visors. This option enables basic hypervisor detection and platform
683 If you say N, all options in this submenu will be skipped and
684 disabled, and Linux guest support won't be built in.
689 bool "Enable paravirtualization code"
691 This changes the kernel so it can modify itself when it is run
692 under a hypervisor, potentially improving performance significantly
693 over full virtualization. However, when run without a hypervisor
694 the kernel is theoretically slower and slightly larger.
696 config PARAVIRT_DEBUG
697 bool "paravirt-ops debugging"
698 depends on PARAVIRT && DEBUG_KERNEL
700 Enable to debug paravirt_ops internals. Specifically, BUG if
701 a paravirt_op is missing when it is called.
703 config PARAVIRT_SPINLOCKS
704 bool "Paravirtualization layer for spinlocks"
705 depends on PARAVIRT && SMP
706 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
708 Paravirtualized spinlocks allow a pvops backend to replace the
709 spinlock implementation with something virtualization-friendly
710 (for example, block the virtual CPU rather than spinning).
712 It has a minimal impact on native kernels and gives a nice performance
713 benefit on paravirtualized KVM / Xen kernels.
715 If you are unsure how to answer this question, answer Y.
717 config QUEUED_LOCK_STAT
718 bool "Paravirt queued spinlock statistics"
719 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
721 Enable the collection of statistical data on the slowpath
722 behavior of paravirtualized queued spinlocks and report
725 source "arch/x86/xen/Kconfig"
728 bool "KVM Guest support (including kvmclock)"
730 select PARAVIRT_CLOCK
733 This option enables various optimizations for running under the KVM
734 hypervisor. It includes a paravirtualized clock, so that instead
735 of relying on a PIT (or probably other) emulation by the
736 underlying device model, the host provides the guest with
737 timing infrastructure such as time of day, and system time
740 bool "Enable debug information for KVM Guests in debugfs"
741 depends on KVM_GUEST && DEBUG_FS
744 This option enables collection of various statistics for KVM guest.
745 Statistics are displayed in debugfs filesystem. Enabling this option
746 may incur significant overhead.
748 source "arch/x86/lguest/Kconfig"
750 config PARAVIRT_TIME_ACCOUNTING
751 bool "Paravirtual steal time accounting"
755 Select this option to enable fine granularity task steal time
756 accounting. Time spent executing other tasks in parallel with
757 the current vCPU is discounted from the vCPU power. To account for
758 that, there can be a small performance impact.
760 If in doubt, say N here.
762 config PARAVIRT_CLOCK
765 endif #HYPERVISOR_GUEST
770 source "arch/x86/Kconfig.cpu"
774 prompt "HPET Timer Support" if X86_32
776 Use the IA-PC HPET (High Precision Event Timer) to manage
777 time in preference to the PIT and RTC, if a HPET is
779 HPET is the next generation timer replacing legacy 8254s.
780 The HPET provides a stable time base on SMP
781 systems, unlike the TSC, but it is more expensive to access,
782 as it is off-chip. You can find the HPET spec at
783 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
785 You can safely choose Y here. However, HPET will only be
786 activated if the platform and the BIOS support this feature.
787 Otherwise the 8254 will be used for timing services.
789 Choose N to continue using the legacy 8254 timer.
791 config HPET_EMULATE_RTC
793 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
796 def_bool y if X86_INTEL_MID
797 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
799 depends on X86_INTEL_MID && SFI
801 APB timer is the replacement for 8254, HPET on X86 MID platforms.
802 The APBT 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. APB timers are always running regardless of CPU
805 C states, they are used as per CPU clockevent device when possible.
807 # Mark as expert because too many people got it wrong.
808 # The code disables itself when not needed.
811 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
812 bool "Enable DMI scanning" if EXPERT
814 Enabled scanning of DMI to identify machine quirks. Say Y
815 here unless you have verified that your setup is not
816 affected by entries in the DMI blacklist. Required by PNP
820 bool "Old AMD GART IOMMU support"
822 depends on X86_64 && PCI && AMD_NB
824 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
825 GART based hardware IOMMUs.
827 The GART supports full DMA access for devices with 32-bit access
828 limitations, on systems with more than 3 GB. This is usually needed
829 for USB, sound, many IDE/SATA chipsets and some other devices.
831 Newer systems typically have a modern AMD IOMMU, supported via
832 the CONFIG_AMD_IOMMU=y config option.
834 In normal configurations this driver is only active when needed:
835 there's more than 3 GB of memory and the system contains a
836 32-bit limited device.
841 bool "IBM Calgary IOMMU support"
843 depends on X86_64 && PCI
845 Support for hardware IOMMUs in IBM's xSeries x366 and x460
846 systems. Needed to run systems with more than 3GB of memory
847 properly with 32-bit PCI devices that do not support DAC
848 (Double Address Cycle). Calgary also supports bus level
849 isolation, where all DMAs pass through the IOMMU. This
850 prevents them from going anywhere except their intended
851 destination. This catches hard-to-find kernel bugs and
852 mis-behaving drivers and devices that do not use the DMA-API
853 properly to set up their DMA buffers. The IOMMU can be
854 turned off at boot time with the iommu=off parameter.
855 Normally the kernel will make the right choice by itself.
858 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
860 prompt "Should Calgary be enabled by default?"
861 depends on CALGARY_IOMMU
863 Should Calgary be enabled by default? if you choose 'y', Calgary
864 will be used (if it exists). If you choose 'n', Calgary will not be
865 used even if it exists. If you choose 'n' and would like to use
866 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
869 # need this always selected by IOMMU for the VIA workaround
873 Support for software bounce buffers used on x86-64 systems
874 which don't have a hardware IOMMU. Using this PCI devices
875 which can only access 32-bits of memory can be used on systems
876 with more than 3 GB of memory.
881 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
884 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
885 depends on X86_64 && SMP && DEBUG_KERNEL
886 select CPUMASK_OFFSTACK
888 Enable maximum number of CPUS and NUMA Nodes for this architecture.
892 int "Maximum number of CPUs" if SMP && !MAXSMP
893 range 2 8 if SMP && X86_32 && !X86_BIGSMP
894 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
895 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
897 default "8192" if MAXSMP
898 default "32" if SMP && X86_BIGSMP
899 default "8" if SMP && X86_32
902 This allows you to specify the maximum number of CPUs which this
903 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
904 supported value is 8192, otherwise the maximum value is 512. The
905 minimum value which makes sense is 2.
907 This is purely to save memory - each supported CPU adds
908 approximately eight kilobytes to the kernel image.
911 bool "SMT (Hyperthreading) scheduler support"
914 SMT scheduler support improves the CPU scheduler's decision making
915 when dealing with Intel Pentium 4 chips with HyperThreading at a
916 cost of slightly increased overhead in some places. If unsure say
921 prompt "Multi-core scheduler support"
924 Multi-core scheduler support improves the CPU scheduler's decision
925 making when dealing with multi-core CPU chips at a cost of slightly
926 increased overhead in some places. If unsure say N here.
928 source "kernel/Kconfig.preempt"
932 depends on !SMP && X86_LOCAL_APIC
935 bool "Local APIC support on uniprocessors" if !PCI_MSI
937 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
939 A local APIC (Advanced Programmable Interrupt Controller) is an
940 integrated interrupt controller in the CPU. If you have a single-CPU
941 system which has a processor with a local APIC, you can say Y here to
942 enable and use it. If you say Y here even though your machine doesn't
943 have a local APIC, then the kernel will still run with no slowdown at
944 all. The local APIC supports CPU-generated self-interrupts (timer,
945 performance counters), and the NMI watchdog which detects hard
949 bool "IO-APIC support on uniprocessors"
950 depends on X86_UP_APIC
952 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
953 SMP-capable replacement for PC-style interrupt controllers. Most
954 SMP systems and many recent uniprocessor systems have one.
956 If you have a single-CPU system with an IO-APIC, you can say Y here
957 to use it. If you say Y here even though your machine doesn't have
958 an IO-APIC, then the kernel will still run with no slowdown at all.
960 config X86_LOCAL_APIC
962 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
963 select IRQ_DOMAIN_HIERARCHY
964 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
968 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
970 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
971 bool "Reroute for broken boot IRQs"
972 depends on X86_IO_APIC
974 This option enables a workaround that fixes a source of
975 spurious interrupts. This is recommended when threaded
976 interrupt handling is used on systems where the generation of
977 superfluous "boot interrupts" cannot be disabled.
979 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
980 entry in the chipset's IO-APIC is masked (as, e.g. the RT
981 kernel does during interrupt handling). On chipsets where this
982 boot IRQ generation cannot be disabled, this workaround keeps
983 the original IRQ line masked so that only the equivalent "boot
984 IRQ" is delivered to the CPUs. The workaround also tells the
985 kernel to set up the IRQ handler on the boot IRQ line. In this
986 way only one interrupt is delivered to the kernel. Otherwise
987 the spurious second interrupt may cause the kernel to bring
988 down (vital) interrupt lines.
990 Only affects "broken" chipsets. Interrupt sharing may be
991 increased on these systems.
994 bool "Machine Check / overheating reporting"
995 select GENERIC_ALLOCATOR
998 Machine Check support allows the processor to notify the
999 kernel if it detects a problem (e.g. overheating, data corruption).
1000 The action the kernel takes depends on the severity of the problem,
1001 ranging from warning messages to halting the machine.
1003 config X86_MCE_INTEL
1005 prompt "Intel MCE features"
1006 depends on X86_MCE && X86_LOCAL_APIC
1008 Additional support for intel specific MCE features such as
1009 the thermal monitor.
1013 prompt "AMD MCE features"
1014 depends on X86_MCE && X86_LOCAL_APIC
1016 Additional support for AMD specific MCE features such as
1017 the DRAM Error Threshold.
1019 config X86_ANCIENT_MCE
1020 bool "Support for old Pentium 5 / WinChip machine checks"
1021 depends on X86_32 && X86_MCE
1023 Include support for machine check handling on old Pentium 5 or WinChip
1024 systems. These typically need to be enabled explicitly on the command
1027 config X86_MCE_THRESHOLD
1028 depends on X86_MCE_AMD || X86_MCE_INTEL
1031 config X86_MCE_INJECT
1033 tristate "Machine check injector support"
1035 Provide support for injecting machine checks for testing purposes.
1036 If you don't know what a machine check is and you don't do kernel
1037 QA it is safe to say n.
1039 config X86_THERMAL_VECTOR
1041 depends on X86_MCE_INTEL
1043 config X86_LEGACY_VM86
1044 bool "Legacy VM86 support"
1048 This option allows user programs to put the CPU into V8086
1049 mode, which is an 80286-era approximation of 16-bit real mode.
1051 Some very old versions of X and/or vbetool require this option
1052 for user mode setting. Similarly, DOSEMU will use it if
1053 available to accelerate real mode DOS programs. However, any
1054 recent version of DOSEMU, X, or vbetool should be fully
1055 functional even without kernel VM86 support, as they will all
1056 fall back to software emulation. Nevertheless, if you are using
1057 a 16-bit DOS program where 16-bit performance matters, vm86
1058 mode might be faster than emulation and you might want to
1061 Note that any app that works on a 64-bit kernel is unlikely to
1062 need this option, as 64-bit kernels don't, and can't, support
1063 V8086 mode. This option is also unrelated to 16-bit protected
1064 mode and is not needed to run most 16-bit programs under Wine.
1066 Enabling this option increases the complexity of the kernel
1067 and slows down exception handling a tiny bit.
1069 If unsure, say N here.
1073 default X86_LEGACY_VM86
1076 bool "Enable support for 16-bit segments" if EXPERT
1078 depends on MODIFY_LDT_SYSCALL
1080 This option is required by programs like Wine to run 16-bit
1081 protected mode legacy code on x86 processors. Disabling
1082 this option saves about 300 bytes on i386, or around 6K text
1083 plus 16K runtime memory on x86-64,
1087 depends on X86_16BIT && X86_32
1091 depends on X86_16BIT && X86_64
1093 config X86_VSYSCALL_EMULATION
1094 bool "Enable vsyscall emulation" if EXPERT
1098 This enables emulation of the legacy vsyscall page. Disabling
1099 it is roughly equivalent to booting with vsyscall=none, except
1100 that it will also disable the helpful warning if a program
1101 tries to use a vsyscall. With this option set to N, offending
1102 programs will just segfault, citing addresses of the form
1105 This option is required by many programs built before 2013, and
1106 care should be used even with newer programs if set to N.
1108 Disabling this option saves about 7K of kernel size and
1109 possibly 4K of additional runtime pagetable memory.
1112 tristate "Toshiba Laptop support"
1115 This adds a driver to safely access the System Management Mode of
1116 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1117 not work on models with a Phoenix BIOS. The System Management Mode
1118 is used to set the BIOS and power saving options on Toshiba portables.
1120 For information on utilities to make use of this driver see the
1121 Toshiba Linux utilities web site at:
1122 <http://www.buzzard.org.uk/toshiba/>.
1124 Say Y if you intend to run this kernel on a Toshiba portable.
1128 tristate "Dell i8k legacy laptop support"
1130 select SENSORS_DELL_SMM
1132 This option enables legacy /proc/i8k userspace interface in hwmon
1133 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1134 temperature and allows controlling fan speeds of Dell laptops via
1135 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1136 it reports also power and hotkey status. For fan speed control is
1137 needed userspace package i8kutils.
1139 Say Y if you intend to run this kernel on old Dell laptops or want to
1140 use userspace package i8kutils.
1143 config X86_REBOOTFIXUPS
1144 bool "Enable X86 board specific fixups for reboot"
1147 This enables chipset and/or board specific fixups to be done
1148 in order to get reboot to work correctly. This is only needed on
1149 some combinations of hardware and BIOS. The symptom, for which
1150 this config is intended, is when reboot ends with a stalled/hung
1153 Currently, the only fixup is for the Geode machines using
1154 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1156 Say Y if you want to enable the fixup. Currently, it's safe to
1157 enable this option even if you don't need it.
1161 bool "CPU microcode loading support"
1163 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1164 depends on BLK_DEV_INITRD
1168 If you say Y here, you will be able to update the microcode on
1169 certain Intel and AMD processors. The Intel support is for the
1170 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1171 Xeon etc. The AMD support is for families 0x10 and later. You will
1172 obviously need the actual microcode binary data itself which is not
1173 shipped with the Linux kernel.
1175 This option selects the general module only, you need to select
1176 at least one vendor specific module as well.
1178 To compile this driver as a module, choose M here: the module
1179 will be called microcode.
1181 config MICROCODE_INTEL
1182 bool "Intel microcode loading support"
1183 depends on MICROCODE
1187 This options enables microcode patch loading support for Intel
1190 For the current Intel microcode data package go to
1191 <https://downloadcenter.intel.com> and search for
1192 'Linux Processor Microcode Data File'.
1194 config MICROCODE_AMD
1195 bool "AMD microcode loading support"
1196 depends on MICROCODE
1199 If you select this option, microcode patch loading support for AMD
1200 processors will be enabled.
1202 config MICROCODE_OLD_INTERFACE
1204 depends on MICROCODE
1207 tristate "/dev/cpu/*/msr - Model-specific register support"
1209 This device gives privileged processes access to the x86
1210 Model-Specific Registers (MSRs). It is a character device with
1211 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1212 MSR accesses are directed to a specific CPU on multi-processor
1216 tristate "/dev/cpu/*/cpuid - CPU information support"
1218 This device gives processes access to the x86 CPUID instruction to
1219 be executed on a specific processor. It is a character device
1220 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1224 prompt "High Memory Support"
1231 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1232 However, the address space of 32-bit x86 processors is only 4
1233 Gigabytes large. That means that, if you have a large amount of
1234 physical memory, not all of it can be "permanently mapped" by the
1235 kernel. The physical memory that's not permanently mapped is called
1238 If you are compiling a kernel which will never run on a machine with
1239 more than 1 Gigabyte total physical RAM, answer "off" here (default
1240 choice and suitable for most users). This will result in a "3GB/1GB"
1241 split: 3GB are mapped so that each process sees a 3GB virtual memory
1242 space and the remaining part of the 4GB virtual memory space is used
1243 by the kernel to permanently map as much physical memory as
1246 If the machine has between 1 and 4 Gigabytes physical RAM, then
1249 If more than 4 Gigabytes is used then answer "64GB" here. This
1250 selection turns Intel PAE (Physical Address Extension) mode on.
1251 PAE implements 3-level paging on IA32 processors. PAE is fully
1252 supported by Linux, PAE mode is implemented on all recent Intel
1253 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1254 then the kernel will not boot on CPUs that don't support PAE!
1256 The actual amount of total physical memory will either be
1257 auto detected or can be forced by using a kernel command line option
1258 such as "mem=256M". (Try "man bootparam" or see the documentation of
1259 your boot loader (lilo or loadlin) about how to pass options to the
1260 kernel at boot time.)
1262 If unsure, say "off".
1267 Select this if you have a 32-bit processor and between 1 and 4
1268 gigabytes of physical RAM.
1275 Select this if you have a 32-bit processor and more than 4
1276 gigabytes of physical RAM.
1281 prompt "Memory split" if EXPERT
1285 Select the desired split between kernel and user memory.
1287 If the address range available to the kernel is less than the
1288 physical memory installed, the remaining memory will be available
1289 as "high memory". Accessing high memory is a little more costly
1290 than low memory, as it needs to be mapped into the kernel first.
1291 Note that increasing the kernel address space limits the range
1292 available to user programs, making the address space there
1293 tighter. Selecting anything other than the default 3G/1G split
1294 will also likely make your kernel incompatible with binary-only
1297 If you are not absolutely sure what you are doing, leave this
1301 bool "3G/1G user/kernel split"
1302 config VMSPLIT_3G_OPT
1304 bool "3G/1G user/kernel split (for full 1G low memory)"
1306 bool "2G/2G user/kernel split"
1307 config VMSPLIT_2G_OPT
1309 bool "2G/2G user/kernel split (for full 2G low memory)"
1311 bool "1G/3G user/kernel split"
1316 default 0xB0000000 if VMSPLIT_3G_OPT
1317 default 0x80000000 if VMSPLIT_2G
1318 default 0x78000000 if VMSPLIT_2G_OPT
1319 default 0x40000000 if VMSPLIT_1G
1325 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1328 bool "PAE (Physical Address Extension) Support"
1329 depends on X86_32 && !HIGHMEM4G
1332 PAE is required for NX support, and furthermore enables
1333 larger swapspace support for non-overcommit purposes. It
1334 has the cost of more pagetable lookup overhead, and also
1335 consumes more pagetable space per process.
1337 config ARCH_PHYS_ADDR_T_64BIT
1339 depends on X86_64 || X86_PAE
1341 config ARCH_DMA_ADDR_T_64BIT
1343 depends on X86_64 || HIGHMEM64G
1345 config X86_DIRECT_GBPAGES
1347 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1349 Certain kernel features effectively disable kernel
1350 linear 1 GB mappings (even if the CPU otherwise
1351 supports them), so don't confuse the user by printing
1352 that we have them enabled.
1354 # Common NUMA Features
1356 bool "Numa Memory Allocation and Scheduler Support"
1358 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1359 default y if X86_BIGSMP
1361 Enable NUMA (Non Uniform Memory Access) support.
1363 The kernel will try to allocate memory used by a CPU on the
1364 local memory controller of the CPU and add some more
1365 NUMA awareness to the kernel.
1367 For 64-bit this is recommended if the system is Intel Core i7
1368 (or later), AMD Opteron, or EM64T NUMA.
1370 For 32-bit this is only needed if you boot a 32-bit
1371 kernel on a 64-bit NUMA platform.
1373 Otherwise, you should say N.
1377 prompt "Old style AMD Opteron NUMA detection"
1378 depends on X86_64 && NUMA && PCI
1380 Enable AMD NUMA node topology detection. You should say Y here if
1381 you have a multi processor AMD system. This uses an old method to
1382 read the NUMA configuration directly from the builtin Northbridge
1383 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1384 which also takes priority if both are compiled in.
1386 config X86_64_ACPI_NUMA
1388 prompt "ACPI NUMA detection"
1389 depends on X86_64 && NUMA && ACPI && PCI
1392 Enable ACPI SRAT based node topology detection.
1394 # Some NUMA nodes have memory ranges that span
1395 # other nodes. Even though a pfn is valid and
1396 # between a node's start and end pfns, it may not
1397 # reside on that node. See memmap_init_zone()
1399 config NODES_SPAN_OTHER_NODES
1401 depends on X86_64_ACPI_NUMA
1404 bool "NUMA emulation"
1407 Enable NUMA emulation. A flat machine will be split
1408 into virtual nodes when booted with "numa=fake=N", where N is the
1409 number of nodes. This is only useful for debugging.
1412 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1414 default "10" if MAXSMP
1415 default "6" if X86_64
1417 depends on NEED_MULTIPLE_NODES
1419 Specify the maximum number of NUMA Nodes available on the target
1420 system. Increases memory reserved to accommodate various tables.
1422 config ARCH_HAVE_MEMORY_PRESENT
1424 depends on X86_32 && DISCONTIGMEM
1426 config NEED_NODE_MEMMAP_SIZE
1428 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1430 config ARCH_FLATMEM_ENABLE
1432 depends on X86_32 && !NUMA
1434 config ARCH_DISCONTIGMEM_ENABLE
1436 depends on NUMA && X86_32
1438 config ARCH_DISCONTIGMEM_DEFAULT
1440 depends on NUMA && X86_32
1442 config ARCH_SPARSEMEM_ENABLE
1444 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1445 select SPARSEMEM_STATIC if X86_32
1446 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1448 config ARCH_SPARSEMEM_DEFAULT
1452 config ARCH_SELECT_MEMORY_MODEL
1454 depends on ARCH_SPARSEMEM_ENABLE
1456 config ARCH_MEMORY_PROBE
1457 bool "Enable sysfs memory/probe interface"
1458 depends on X86_64 && MEMORY_HOTPLUG
1460 This option enables a sysfs memory/probe interface for testing.
1461 See Documentation/memory-hotplug.txt for more information.
1462 If you are unsure how to answer this question, answer N.
1464 config ARCH_PROC_KCORE_TEXT
1466 depends on X86_64 && PROC_KCORE
1468 config ILLEGAL_POINTER_VALUE
1471 default 0xdead000000000000 if X86_64
1475 config X86_PMEM_LEGACY_DEVICE
1478 config X86_PMEM_LEGACY
1479 tristate "Support non-standard NVDIMMs and ADR protected memory"
1480 depends on PHYS_ADDR_T_64BIT
1482 select X86_PMEM_LEGACY_DEVICE
1485 Treat memory marked using the non-standard e820 type of 12 as used
1486 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1487 The kernel will offer these regions to the 'pmem' driver so
1488 they can be used for persistent storage.
1493 bool "Allocate 3rd-level pagetables from highmem"
1496 The VM uses one page table entry for each page of physical memory.
1497 For systems with a lot of RAM, this can be wasteful of precious
1498 low memory. Setting this option will put user-space page table
1499 entries in high memory.
1501 config X86_CHECK_BIOS_CORRUPTION
1502 bool "Check for low memory corruption"
1504 Periodically check for memory corruption in low memory, which
1505 is suspected to be caused by BIOS. Even when enabled in the
1506 configuration, it is disabled at runtime. Enable it by
1507 setting "memory_corruption_check=1" on the kernel command
1508 line. By default it scans the low 64k of memory every 60
1509 seconds; see the memory_corruption_check_size and
1510 memory_corruption_check_period parameters in
1511 Documentation/kernel-parameters.txt to adjust this.
1513 When enabled with the default parameters, this option has
1514 almost no overhead, as it reserves a relatively small amount
1515 of memory and scans it infrequently. It both detects corruption
1516 and prevents it from affecting the running system.
1518 It is, however, intended as a diagnostic tool; if repeatable
1519 BIOS-originated corruption always affects the same memory,
1520 you can use memmap= to prevent the kernel from using that
1523 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1524 bool "Set the default setting of memory_corruption_check"
1525 depends on X86_CHECK_BIOS_CORRUPTION
1528 Set whether the default state of memory_corruption_check is
1531 config X86_RESERVE_LOW
1532 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1536 Specify the amount of low memory to reserve for the BIOS.
1538 The first page contains BIOS data structures that the kernel
1539 must not use, so that page must always be reserved.
1541 By default we reserve the first 64K of physical RAM, as a
1542 number of BIOSes are known to corrupt that memory range
1543 during events such as suspend/resume or monitor cable
1544 insertion, so it must not be used by the kernel.
1546 You can set this to 4 if you are absolutely sure that you
1547 trust the BIOS to get all its memory reservations and usages
1548 right. If you know your BIOS have problems beyond the
1549 default 64K area, you can set this to 640 to avoid using the
1550 entire low memory range.
1552 If you have doubts about the BIOS (e.g. suspend/resume does
1553 not work or there's kernel crashes after certain hardware
1554 hotplug events) then you might want to enable
1555 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1556 typical corruption patterns.
1558 Leave this to the default value of 64 if you are unsure.
1560 config MATH_EMULATION
1562 depends on MODIFY_LDT_SYSCALL
1563 prompt "Math emulation" if X86_32
1565 Linux can emulate a math coprocessor (used for floating point
1566 operations) if you don't have one. 486DX and Pentium processors have
1567 a math coprocessor built in, 486SX and 386 do not, unless you added
1568 a 487DX or 387, respectively. (The messages during boot time can
1569 give you some hints here ["man dmesg"].) Everyone needs either a
1570 coprocessor or this emulation.
1572 If you don't have a math coprocessor, you need to say Y here; if you
1573 say Y here even though you have a coprocessor, the coprocessor will
1574 be used nevertheless. (This behavior can be changed with the kernel
1575 command line option "no387", which comes handy if your coprocessor
1576 is broken. Try "man bootparam" or see the documentation of your boot
1577 loader (lilo or loadlin) about how to pass options to the kernel at
1578 boot time.) This means that it is a good idea to say Y here if you
1579 intend to use this kernel on different machines.
1581 More information about the internals of the Linux math coprocessor
1582 emulation can be found in <file:arch/x86/math-emu/README>.
1584 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1585 kernel, it won't hurt.
1589 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1591 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1592 the Memory Type Range Registers (MTRRs) may be used to control
1593 processor access to memory ranges. This is most useful if you have
1594 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1595 allows bus write transfers to be combined into a larger transfer
1596 before bursting over the PCI/AGP bus. This can increase performance
1597 of image write operations 2.5 times or more. Saying Y here creates a
1598 /proc/mtrr file which may be used to manipulate your processor's
1599 MTRRs. Typically the X server should use this.
1601 This code has a reasonably generic interface so that similar
1602 control registers on other processors can be easily supported
1605 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1606 Registers (ARRs) which provide a similar functionality to MTRRs. For
1607 these, the ARRs are used to emulate the MTRRs.
1608 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1609 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1610 write-combining. All of these processors are supported by this code
1611 and it makes sense to say Y here if you have one of them.
1613 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1614 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1615 can lead to all sorts of problems, so it's good to say Y here.
1617 You can safely say Y even if your machine doesn't have MTRRs, you'll
1618 just add about 9 KB to your kernel.
1620 See <file:Documentation/x86/mtrr.txt> for more information.
1622 config MTRR_SANITIZER
1624 prompt "MTRR cleanup support"
1627 Convert MTRR layout from continuous to discrete, so X drivers can
1628 add writeback entries.
1630 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1631 The largest mtrr entry size for a continuous block can be set with
1636 config MTRR_SANITIZER_ENABLE_DEFAULT
1637 int "MTRR cleanup enable value (0-1)"
1640 depends on MTRR_SANITIZER
1642 Enable mtrr cleanup default value
1644 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1645 int "MTRR cleanup spare reg num (0-7)"
1648 depends on MTRR_SANITIZER
1650 mtrr cleanup spare entries default, it can be changed via
1651 mtrr_spare_reg_nr=N on the kernel command line.
1655 prompt "x86 PAT support" if EXPERT
1658 Use PAT attributes to setup page level cache control.
1660 PATs are the modern equivalents of MTRRs and are much more
1661 flexible than MTRRs.
1663 Say N here if you see bootup problems (boot crash, boot hang,
1664 spontaneous reboots) or a non-working video driver.
1668 config ARCH_USES_PG_UNCACHED
1674 prompt "x86 architectural random number generator" if EXPERT
1676 Enable the x86 architectural RDRAND instruction
1677 (Intel Bull Mountain technology) to generate random numbers.
1678 If supported, this is a high bandwidth, cryptographically
1679 secure hardware random number generator.
1683 prompt "Supervisor Mode Access Prevention" if EXPERT
1685 Supervisor Mode Access Prevention (SMAP) is a security
1686 feature in newer Intel processors. There is a small
1687 performance cost if this enabled and turned on; there is
1688 also a small increase in the kernel size if this is enabled.
1692 config X86_INTEL_MPX
1693 prompt "Intel MPX (Memory Protection Extensions)"
1695 depends on CPU_SUP_INTEL
1697 MPX provides hardware features that can be used in
1698 conjunction with compiler-instrumented code to check
1699 memory references. It is designed to detect buffer
1700 overflow or underflow bugs.
1702 This option enables running applications which are
1703 instrumented or otherwise use MPX. It does not use MPX
1704 itself inside the kernel or to protect the kernel
1705 against bad memory references.
1707 Enabling this option will make the kernel larger:
1708 ~8k of kernel text and 36 bytes of data on a 64-bit
1709 defconfig. It adds a long to the 'mm_struct' which
1710 will increase the kernel memory overhead of each
1711 process and adds some branches to paths used during
1712 exec() and munmap().
1714 For details, see Documentation/x86/intel_mpx.txt
1718 config X86_INTEL_MEMORY_PROTECTION_KEYS
1720 depends on CPU_SUP_INTEL && X86_64
1723 bool "EFI runtime service support"
1726 select EFI_RUNTIME_WRAPPERS
1728 This enables the kernel to use EFI runtime services that are
1729 available (such as the EFI variable services).
1731 This option is only useful on systems that have EFI firmware.
1732 In addition, you should use the latest ELILO loader available
1733 at <http://elilo.sourceforge.net> in order to take advantage
1734 of EFI runtime services. However, even with this option, the
1735 resultant kernel should continue to boot on existing non-EFI
1739 bool "EFI stub support"
1740 depends on EFI && !X86_USE_3DNOW
1743 This kernel feature allows a bzImage to be loaded directly
1744 by EFI firmware without the use of a bootloader.
1746 See Documentation/efi-stub.txt for more information.
1749 bool "EFI mixed-mode support"
1750 depends on EFI_STUB && X86_64
1752 Enabling this feature allows a 64-bit kernel to be booted
1753 on a 32-bit firmware, provided that your CPU supports 64-bit
1756 Note that it is not possible to boot a mixed-mode enabled
1757 kernel via the EFI boot stub - a bootloader that supports
1758 the EFI handover protocol must be used.
1764 prompt "Enable seccomp to safely compute untrusted bytecode"
1766 This kernel feature is useful for number crunching applications
1767 that may need to compute untrusted bytecode during their
1768 execution. By using pipes or other transports made available to
1769 the process as file descriptors supporting the read/write
1770 syscalls, it's possible to isolate those applications in
1771 their own address space using seccomp. Once seccomp is
1772 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1773 and the task is only allowed to execute a few safe syscalls
1774 defined by each seccomp mode.
1776 If unsure, say Y. Only embedded should say N here.
1778 source kernel/Kconfig.hz
1781 bool "kexec system call"
1784 kexec is a system call that implements the ability to shutdown your
1785 current kernel, and to start another kernel. It is like a reboot
1786 but it is independent of the system firmware. And like a reboot
1787 you can start any kernel with it, not just Linux.
1789 The name comes from the similarity to the exec system call.
1791 It is an ongoing process to be certain the hardware in a machine
1792 is properly shutdown, so do not be surprised if this code does not
1793 initially work for you. As of this writing the exact hardware
1794 interface is strongly in flux, so no good recommendation can be
1798 bool "kexec file based system call"
1803 depends on CRYPTO_SHA256=y
1805 This is new version of kexec system call. This system call is
1806 file based and takes file descriptors as system call argument
1807 for kernel and initramfs as opposed to list of segments as
1808 accepted by previous system call.
1810 config KEXEC_VERIFY_SIG
1811 bool "Verify kernel signature during kexec_file_load() syscall"
1812 depends on KEXEC_FILE
1814 This option makes kernel signature verification mandatory for
1815 the kexec_file_load() syscall.
1817 In addition to that option, you need to enable signature
1818 verification for the corresponding kernel image type being
1819 loaded in order for this to work.
1821 config KEXEC_BZIMAGE_VERIFY_SIG
1822 bool "Enable bzImage signature verification support"
1823 depends on KEXEC_VERIFY_SIG
1824 depends on SIGNED_PE_FILE_VERIFICATION
1825 select SYSTEM_TRUSTED_KEYRING
1827 Enable bzImage signature verification support.
1830 bool "kernel crash dumps"
1831 depends on X86_64 || (X86_32 && HIGHMEM)
1833 Generate crash dump after being started by kexec.
1834 This should be normally only set in special crash dump kernels
1835 which are loaded in the main kernel with kexec-tools into
1836 a specially reserved region and then later executed after
1837 a crash by kdump/kexec. The crash dump kernel must be compiled
1838 to a memory address not used by the main kernel or BIOS using
1839 PHYSICAL_START, or it must be built as a relocatable image
1840 (CONFIG_RELOCATABLE=y).
1841 For more details see Documentation/kdump/kdump.txt
1845 depends on KEXEC && HIBERNATION
1847 Jump between original kernel and kexeced kernel and invoke
1848 code in physical address mode via KEXEC
1850 config PHYSICAL_START
1851 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1854 This gives the physical address where the kernel is loaded.
1856 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1857 bzImage will decompress itself to above physical address and
1858 run from there. Otherwise, bzImage will run from the address where
1859 it has been loaded by the boot loader and will ignore above physical
1862 In normal kdump cases one does not have to set/change this option
1863 as now bzImage can be compiled as a completely relocatable image
1864 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1865 address. This option is mainly useful for the folks who don't want
1866 to use a bzImage for capturing the crash dump and want to use a
1867 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1868 to be specifically compiled to run from a specific memory area
1869 (normally a reserved region) and this option comes handy.
1871 So if you are using bzImage for capturing the crash dump,
1872 leave the value here unchanged to 0x1000000 and set
1873 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1874 for capturing the crash dump change this value to start of
1875 the reserved region. In other words, it can be set based on
1876 the "X" value as specified in the "crashkernel=YM@XM"
1877 command line boot parameter passed to the panic-ed
1878 kernel. Please take a look at Documentation/kdump/kdump.txt
1879 for more details about crash dumps.
1881 Usage of bzImage for capturing the crash dump is recommended as
1882 one does not have to build two kernels. Same kernel can be used
1883 as production kernel and capture kernel. Above option should have
1884 gone away after relocatable bzImage support is introduced. But it
1885 is present because there are users out there who continue to use
1886 vmlinux for dump capture. This option should go away down the
1889 Don't change this unless you know what you are doing.
1892 bool "Build a relocatable kernel"
1895 This builds a kernel image that retains relocation information
1896 so it can be loaded someplace besides the default 1MB.
1897 The relocations tend to make the kernel binary about 10% larger,
1898 but are discarded at runtime.
1900 One use is for the kexec on panic case where the recovery kernel
1901 must live at a different physical address than the primary
1904 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1905 it has been loaded at and the compile time physical address
1906 (CONFIG_PHYSICAL_START) is used as the minimum location.
1908 config RANDOMIZE_BASE
1909 bool "Randomize the address of the kernel image"
1910 depends on RELOCATABLE
1913 Randomizes the physical and virtual address at which the
1914 kernel image is decompressed, as a security feature that
1915 deters exploit attempts relying on knowledge of the location
1916 of kernel internals.
1918 Entropy is generated using the RDRAND instruction if it is
1919 supported. If RDTSC is supported, it is used as well. If
1920 neither RDRAND nor RDTSC are supported, then randomness is
1921 read from the i8254 timer.
1923 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1924 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1925 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1926 minimum of 2MiB, only 10 bits of entropy is theoretically
1927 possible. At best, due to page table layouts, 64-bit can use
1928 9 bits of entropy and 32-bit uses 8 bits.
1932 config RANDOMIZE_BASE_MAX_OFFSET
1933 hex "Maximum kASLR offset allowed" if EXPERT
1934 depends on RANDOMIZE_BASE
1935 range 0x0 0x20000000 if X86_32
1936 default "0x20000000" if X86_32
1937 range 0x0 0x40000000 if X86_64
1938 default "0x40000000" if X86_64
1940 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1941 memory is used to determine the maximal offset in bytes that will
1942 be applied to the kernel when kernel Address Space Layout
1943 Randomization (kASLR) is active. This must be a multiple of
1946 On 32-bit this is limited to 512MiB by page table layouts. The
1949 On 64-bit this is limited by how the kernel fixmap page table is
1950 positioned, so this cannot be larger than 1GiB currently. Without
1951 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1952 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1953 modules area will shrink to compensate, up to the current maximum
1954 1GiB to 1GiB split. The default is 1GiB.
1956 If unsure, leave at the default value.
1958 # Relocation on x86 needs some additional build support
1959 config X86_NEED_RELOCS
1961 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1963 config PHYSICAL_ALIGN
1964 hex "Alignment value to which kernel should be aligned"
1966 range 0x2000 0x1000000 if X86_32
1967 range 0x200000 0x1000000 if X86_64
1969 This value puts the alignment restrictions on physical address
1970 where kernel is loaded and run from. Kernel is compiled for an
1971 address which meets above alignment restriction.
1973 If bootloader loads the kernel at a non-aligned address and
1974 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1975 address aligned to above value and run from there.
1977 If bootloader loads the kernel at a non-aligned address and
1978 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1979 load address and decompress itself to the address it has been
1980 compiled for and run from there. The address for which kernel is
1981 compiled already meets above alignment restrictions. Hence the
1982 end result is that kernel runs from a physical address meeting
1983 above alignment restrictions.
1985 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1986 this value must be a multiple of 0x200000.
1988 Don't change this unless you know what you are doing.
1991 bool "Support for hot-pluggable CPUs"
1994 Say Y here to allow turning CPUs off and on. CPUs can be
1995 controlled through /sys/devices/system/cpu.
1996 ( Note: power management support will enable this option
1997 automatically on SMP systems. )
1998 Say N if you want to disable CPU hotplug.
2000 config BOOTPARAM_HOTPLUG_CPU0
2001 bool "Set default setting of cpu0_hotpluggable"
2003 depends on HOTPLUG_CPU
2005 Set whether default state of cpu0_hotpluggable is on or off.
2007 Say Y here to enable CPU0 hotplug by default. If this switch
2008 is turned on, there is no need to give cpu0_hotplug kernel
2009 parameter and the CPU0 hotplug feature is enabled by default.
2011 Please note: there are two known CPU0 dependencies if you want
2012 to enable the CPU0 hotplug feature either by this switch or by
2013 cpu0_hotplug kernel parameter.
2015 First, resume from hibernate or suspend always starts from CPU0.
2016 So hibernate and suspend are prevented if CPU0 is offline.
2018 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2019 offline if any interrupt can not migrate out of CPU0. There may
2020 be other CPU0 dependencies.
2022 Please make sure the dependencies are under your control before
2023 you enable this feature.
2025 Say N if you don't want to enable CPU0 hotplug feature by default.
2026 You still can enable the CPU0 hotplug feature at boot by kernel
2027 parameter cpu0_hotplug.
2029 config DEBUG_HOTPLUG_CPU0
2031 prompt "Debug CPU0 hotplug"
2032 depends on HOTPLUG_CPU
2034 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2035 soon as possible and boots up userspace with CPU0 offlined. User
2036 can online CPU0 back after boot time.
2038 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2039 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2040 compilation or giving cpu0_hotplug kernel parameter at boot.
2046 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2047 depends on X86_32 || IA32_EMULATION
2049 Certain buggy versions of glibc will crash if they are
2050 presented with a 32-bit vDSO that is not mapped at the address
2051 indicated in its segment table.
2053 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2054 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2055 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2056 the only released version with the bug, but OpenSUSE 9
2057 contains a buggy "glibc 2.3.2".
2059 The symptom of the bug is that everything crashes on startup, saying:
2060 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2062 Saying Y here changes the default value of the vdso32 boot
2063 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2064 This works around the glibc bug but hurts performance.
2066 If unsure, say N: if you are compiling your own kernel, you
2067 are unlikely to be using a buggy version of glibc.
2070 prompt "vsyscall table for legacy applications"
2072 default LEGACY_VSYSCALL_EMULATE
2074 Legacy user code that does not know how to find the vDSO expects
2075 to be able to issue three syscalls by calling fixed addresses in
2076 kernel space. Since this location is not randomized with ASLR,
2077 it can be used to assist security vulnerability exploitation.
2079 This setting can be changed at boot time via the kernel command
2080 line parameter vsyscall=[native|emulate|none].
2082 On a system with recent enough glibc (2.14 or newer) and no
2083 static binaries, you can say None without a performance penalty
2084 to improve security.
2086 If unsure, select "Emulate".
2088 config LEGACY_VSYSCALL_NATIVE
2091 Actual executable code is located in the fixed vsyscall
2092 address mapping, implementing time() efficiently. Since
2093 this makes the mapping executable, it can be used during
2094 security vulnerability exploitation (traditionally as
2095 ROP gadgets). This configuration is not recommended.
2097 config LEGACY_VSYSCALL_EMULATE
2100 The kernel traps and emulates calls into the fixed
2101 vsyscall address mapping. This makes the mapping
2102 non-executable, but it still contains known contents,
2103 which could be used in certain rare security vulnerability
2104 exploits. This configuration is recommended when userspace
2105 still uses the vsyscall area.
2107 config LEGACY_VSYSCALL_NONE
2110 There will be no vsyscall mapping at all. This will
2111 eliminate any risk of ASLR bypass due to the vsyscall
2112 fixed address mapping. Attempts to use the vsyscalls
2113 will be reported to dmesg, so that either old or
2114 malicious userspace programs can be identified.
2119 bool "Built-in kernel command line"
2121 Allow for specifying boot arguments to the kernel at
2122 build time. On some systems (e.g. embedded ones), it is
2123 necessary or convenient to provide some or all of the
2124 kernel boot arguments with the kernel itself (that is,
2125 to not rely on the boot loader to provide them.)
2127 To compile command line arguments into the kernel,
2128 set this option to 'Y', then fill in the
2129 boot arguments in CONFIG_CMDLINE.
2131 Systems with fully functional boot loaders (i.e. non-embedded)
2132 should leave this option set to 'N'.
2135 string "Built-in kernel command string"
2136 depends on CMDLINE_BOOL
2139 Enter arguments here that should be compiled into the kernel
2140 image and used at boot time. If the boot loader provides a
2141 command line at boot time, it is appended to this string to
2142 form the full kernel command line, when the system boots.
2144 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2145 change this behavior.
2147 In most cases, the command line (whether built-in or provided
2148 by the boot loader) should specify the device for the root
2151 config CMDLINE_OVERRIDE
2152 bool "Built-in command line overrides boot loader arguments"
2153 depends on CMDLINE_BOOL
2155 Set this option to 'Y' to have the kernel ignore the boot loader
2156 command line, and use ONLY the built-in command line.
2158 This is used to work around broken boot loaders. This should
2159 be set to 'N' under normal conditions.
2161 config MODIFY_LDT_SYSCALL
2162 bool "Enable the LDT (local descriptor table)" if EXPERT
2165 Linux can allow user programs to install a per-process x86
2166 Local Descriptor Table (LDT) using the modify_ldt(2) system
2167 call. This is required to run 16-bit or segmented code such as
2168 DOSEMU or some Wine programs. It is also used by some very old
2169 threading libraries.
2171 Enabling this feature adds a small amount of overhead to
2172 context switches and increases the low-level kernel attack
2173 surface. Disabling it removes the modify_ldt(2) system call.
2175 Saying 'N' here may make sense for embedded or server kernels.
2177 source "kernel/livepatch/Kconfig"
2181 config ARCH_ENABLE_MEMORY_HOTPLUG
2183 depends on X86_64 || (X86_32 && HIGHMEM)
2185 config ARCH_ENABLE_MEMORY_HOTREMOVE
2187 depends on MEMORY_HOTPLUG
2189 config USE_PERCPU_NUMA_NODE_ID
2193 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2195 depends on X86_64 || X86_PAE
2197 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2199 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2201 menu "Power management and ACPI options"
2203 config ARCH_HIBERNATION_HEADER
2205 depends on X86_64 && HIBERNATION
2207 source "kernel/power/Kconfig"
2209 source "drivers/acpi/Kconfig"
2211 source "drivers/sfi/Kconfig"
2218 tristate "APM (Advanced Power Management) BIOS support"
2219 depends on X86_32 && PM_SLEEP
2221 APM is a BIOS specification for saving power using several different
2222 techniques. This is mostly useful for battery powered laptops with
2223 APM compliant BIOSes. If you say Y here, the system time will be
2224 reset after a RESUME operation, the /proc/apm device will provide
2225 battery status information, and user-space programs will receive
2226 notification of APM "events" (e.g. battery status change).
2228 If you select "Y" here, you can disable actual use of the APM
2229 BIOS by passing the "apm=off" option to the kernel at boot time.
2231 Note that the APM support is almost completely disabled for
2232 machines with more than one CPU.
2234 In order to use APM, you will need supporting software. For location
2235 and more information, read <file:Documentation/power/apm-acpi.txt>
2236 and the Battery Powered Linux mini-HOWTO, available from
2237 <http://www.tldp.org/docs.html#howto>.
2239 This driver does not spin down disk drives (see the hdparm(8)
2240 manpage ("man 8 hdparm") for that), and it doesn't turn off
2241 VESA-compliant "green" monitors.
2243 This driver does not support the TI 4000M TravelMate and the ACER
2244 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2245 desktop machines also don't have compliant BIOSes, and this driver
2246 may cause those machines to panic during the boot phase.
2248 Generally, if you don't have a battery in your machine, there isn't
2249 much point in using this driver and you should say N. If you get
2250 random kernel OOPSes or reboots that don't seem to be related to
2251 anything, try disabling/enabling this option (or disabling/enabling
2254 Some other things you should try when experiencing seemingly random,
2257 1) make sure that you have enough swap space and that it is
2259 2) pass the "no-hlt" option to the kernel
2260 3) switch on floating point emulation in the kernel and pass
2261 the "no387" option to the kernel
2262 4) pass the "floppy=nodma" option to the kernel
2263 5) pass the "mem=4M" option to the kernel (thereby disabling
2264 all but the first 4 MB of RAM)
2265 6) make sure that the CPU is not over clocked.
2266 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2267 8) disable the cache from your BIOS settings
2268 9) install a fan for the video card or exchange video RAM
2269 10) install a better fan for the CPU
2270 11) exchange RAM chips
2271 12) exchange the motherboard.
2273 To compile this driver as a module, choose M here: the
2274 module will be called apm.
2278 config APM_IGNORE_USER_SUSPEND
2279 bool "Ignore USER SUSPEND"
2281 This option will ignore USER SUSPEND requests. On machines with a
2282 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2283 series notebooks, it is necessary to say Y because of a BIOS bug.
2285 config APM_DO_ENABLE
2286 bool "Enable PM at boot time"
2288 Enable APM features at boot time. From page 36 of the APM BIOS
2289 specification: "When disabled, the APM BIOS does not automatically
2290 power manage devices, enter the Standby State, enter the Suspend
2291 State, or take power saving steps in response to CPU Idle calls."
2292 This driver will make CPU Idle calls when Linux is idle (unless this
2293 feature is turned off -- see "Do CPU IDLE calls", below). This
2294 should always save battery power, but more complicated APM features
2295 will be dependent on your BIOS implementation. You may need to turn
2296 this option off if your computer hangs at boot time when using APM
2297 support, or if it beeps continuously instead of suspending. Turn
2298 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2299 T400CDT. This is off by default since most machines do fine without
2304 bool "Make CPU Idle calls when idle"
2306 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2307 On some machines, this can activate improved power savings, such as
2308 a slowed CPU clock rate, when the machine is idle. These idle calls
2309 are made after the idle loop has run for some length of time (e.g.,
2310 333 mS). On some machines, this will cause a hang at boot time or
2311 whenever the CPU becomes idle. (On machines with more than one CPU,
2312 this option does nothing.)
2314 config APM_DISPLAY_BLANK
2315 bool "Enable console blanking using APM"
2317 Enable console blanking using the APM. Some laptops can use this to
2318 turn off the LCD backlight when the screen blanker of the Linux
2319 virtual console blanks the screen. Note that this is only used by
2320 the virtual console screen blanker, and won't turn off the backlight
2321 when using the X Window system. This also doesn't have anything to
2322 do with your VESA-compliant power-saving monitor. Further, this
2323 option doesn't work for all laptops -- it might not turn off your
2324 backlight at all, or it might print a lot of errors to the console,
2325 especially if you are using gpm.
2327 config APM_ALLOW_INTS
2328 bool "Allow interrupts during APM BIOS calls"
2330 Normally we disable external interrupts while we are making calls to
2331 the APM BIOS as a measure to lessen the effects of a badly behaving
2332 BIOS implementation. The BIOS should reenable interrupts if it
2333 needs to. Unfortunately, some BIOSes do not -- especially those in
2334 many of the newer IBM Thinkpads. If you experience hangs when you
2335 suspend, try setting this to Y. Otherwise, say N.
2339 source "drivers/cpufreq/Kconfig"
2341 source "drivers/cpuidle/Kconfig"
2343 source "drivers/idle/Kconfig"
2348 menu "Bus options (PCI etc.)"
2354 Find out whether you have a PCI motherboard. PCI is the name of a
2355 bus system, i.e. the way the CPU talks to the other stuff inside
2356 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2357 VESA. If you have PCI, say Y, otherwise N.
2360 prompt "PCI access mode"
2361 depends on X86_32 && PCI
2364 On PCI systems, the BIOS can be used to detect the PCI devices and
2365 determine their configuration. However, some old PCI motherboards
2366 have BIOS bugs and may crash if this is done. Also, some embedded
2367 PCI-based systems don't have any BIOS at all. Linux can also try to
2368 detect the PCI hardware directly without using the BIOS.
2370 With this option, you can specify how Linux should detect the
2371 PCI devices. If you choose "BIOS", the BIOS will be used,
2372 if you choose "Direct", the BIOS won't be used, and if you
2373 choose "MMConfig", then PCI Express MMCONFIG will be used.
2374 If you choose "Any", the kernel will try MMCONFIG, then the
2375 direct access method and falls back to the BIOS if that doesn't
2376 work. If unsure, go with the default, which is "Any".
2381 config PCI_GOMMCONFIG
2398 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2400 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2403 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2407 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2411 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2415 depends on PCI && XEN
2423 bool "Support mmconfig PCI config space access"
2424 depends on X86_64 && PCI && ACPI
2426 config PCI_CNB20LE_QUIRK
2427 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2430 Read the PCI windows out of the CNB20LE host bridge. This allows
2431 PCI hotplug to work on systems with the CNB20LE chipset which do
2434 There's no public spec for this chipset, and this functionality
2435 is known to be incomplete.
2437 You should say N unless you know you need this.
2439 source "drivers/pci/pcie/Kconfig"
2441 source "drivers/pci/Kconfig"
2443 # x86_64 have no ISA slots, but can have ISA-style DMA.
2445 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2448 Enables ISA-style DMA support for devices requiring such controllers.
2456 Find out whether you have ISA slots on your motherboard. ISA is the
2457 name of a bus system, i.e. the way the CPU talks to the other stuff
2458 inside your box. Other bus systems are PCI, EISA, MicroChannel
2459 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2460 newer boards don't support it. If you have ISA, say Y, otherwise N.
2466 The Extended Industry Standard Architecture (EISA) bus was
2467 developed as an open alternative to the IBM MicroChannel bus.
2469 The EISA bus provided some of the features of the IBM MicroChannel
2470 bus while maintaining backward compatibility with cards made for
2471 the older ISA bus. The EISA bus saw limited use between 1988 and
2472 1995 when it was made obsolete by the PCI bus.
2474 Say Y here if you are building a kernel for an EISA-based machine.
2478 source "drivers/eisa/Kconfig"
2481 tristate "NatSemi SCx200 support"
2483 This provides basic support for National Semiconductor's
2484 (now AMD's) Geode processors. The driver probes for the
2485 PCI-IDs of several on-chip devices, so its a good dependency
2486 for other scx200_* drivers.
2488 If compiled as a module, the driver is named scx200.
2490 config SCx200HR_TIMER
2491 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2495 This driver provides a clocksource built upon the on-chip
2496 27MHz high-resolution timer. Its also a workaround for
2497 NSC Geode SC-1100's buggy TSC, which loses time when the
2498 processor goes idle (as is done by the scheduler). The
2499 other workaround is idle=poll boot option.
2502 bool "One Laptop Per Child support"
2509 Add support for detecting the unique features of the OLPC
2513 bool "OLPC XO-1 Power Management"
2514 depends on OLPC && MFD_CS5535 && PM_SLEEP
2517 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2520 bool "OLPC XO-1 Real Time Clock"
2521 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2523 Add support for the XO-1 real time clock, which can be used as a
2524 programmable wakeup source.
2527 bool "OLPC XO-1 SCI extras"
2528 depends on OLPC && OLPC_XO1_PM
2534 Add support for SCI-based features of the OLPC XO-1 laptop:
2535 - EC-driven system wakeups
2539 - AC adapter status updates
2540 - Battery status updates
2542 config OLPC_XO15_SCI
2543 bool "OLPC XO-1.5 SCI extras"
2544 depends on OLPC && ACPI
2547 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2548 - EC-driven system wakeups
2549 - AC adapter status updates
2550 - Battery status updates
2553 bool "PCEngines ALIX System Support (LED setup)"
2556 This option enables system support for the PCEngines ALIX.
2557 At present this just sets up LEDs for GPIO control on
2558 ALIX2/3/6 boards. However, other system specific setup should
2561 Note: You must still enable the drivers for GPIO and LED support
2562 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2564 Note: You have to set alix.force=1 for boards with Award BIOS.
2567 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2570 This option enables system support for the Soekris Engineering net5501.
2573 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2577 This option enables system support for the Traverse Technologies GEOS.
2580 bool "Technologic Systems TS-5500 platform support"
2582 select CHECK_SIGNATURE
2586 This option enables system support for the Technologic Systems TS-5500.
2592 depends on CPU_SUP_AMD && PCI
2594 source "drivers/pcmcia/Kconfig"
2596 source "drivers/pci/hotplug/Kconfig"
2599 tristate "RapidIO support"
2603 If enabled this option will include drivers and the core
2604 infrastructure code to support RapidIO interconnect devices.
2606 source "drivers/rapidio/Kconfig"
2609 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2611 Firmwares often provide initial graphics framebuffers so the BIOS,
2612 bootloader or kernel can show basic video-output during boot for
2613 user-guidance and debugging. Historically, x86 used the VESA BIOS
2614 Extensions and EFI-framebuffers for this, which are mostly limited
2616 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2617 framebuffers so the new generic system-framebuffer drivers can be
2618 used on x86. If the framebuffer is not compatible with the generic
2619 modes, it is adverticed as fallback platform framebuffer so legacy
2620 drivers like efifb, vesafb and uvesafb can pick it up.
2621 If this option is not selected, all system framebuffers are always
2622 marked as fallback platform framebuffers as usual.
2624 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2625 not be able to pick up generic system framebuffers if this option
2626 is selected. You are highly encouraged to enable simplefb as
2627 replacement if you select this option. simplefb can correctly deal
2628 with generic system framebuffers. But you should still keep vesafb
2629 and others enabled as fallback if a system framebuffer is
2630 incompatible with simplefb.
2637 menu "Executable file formats / Emulations"
2639 source "fs/Kconfig.binfmt"
2641 config IA32_EMULATION
2642 bool "IA32 Emulation"
2645 select COMPAT_BINFMT_ELF
2646 select ARCH_WANT_OLD_COMPAT_IPC
2648 Include code to run legacy 32-bit programs under a
2649 64-bit kernel. You should likely turn this on, unless you're
2650 100% sure that you don't have any 32-bit programs left.
2653 tristate "IA32 a.out support"
2654 depends on IA32_EMULATION
2656 Support old a.out binaries in the 32bit emulation.
2659 bool "x32 ABI for 64-bit mode"
2662 Include code to run binaries for the x32 native 32-bit ABI
2663 for 64-bit processors. An x32 process gets access to the
2664 full 64-bit register file and wide data path while leaving
2665 pointers at 32 bits for smaller memory footprint.
2667 You will need a recent binutils (2.22 or later) with
2668 elf32_x86_64 support enabled to compile a kernel with this
2673 depends on IA32_EMULATION || X86_X32
2676 config COMPAT_FOR_U64_ALIGNMENT
2679 config SYSVIPC_COMPAT
2691 config HAVE_ATOMIC_IOMAP
2695 config X86_DEV_DMA_OPS
2697 depends on X86_64 || STA2X11
2699 config X86_DMA_REMAP
2709 tristate "Volume Management Device Driver"
2712 Adds support for the Intel Volume Management Device (VMD). VMD is a
2713 secondary PCI host bridge that allows PCI Express root ports,
2714 and devices attached to them, to be removed from the default
2715 PCI domain and placed within the VMD domain. This provides
2716 more bus resources than are otherwise possible with a
2717 single domain. If you know your system provides one of these and
2718 has devices attached to it, say Y; if you are not sure, say N.
2720 source "net/Kconfig"
2722 source "drivers/Kconfig"
2724 source "drivers/firmware/Kconfig"
2728 source "arch/x86/Kconfig.debug"
2730 source "security/Kconfig"
2732 source "crypto/Kconfig"
2734 source "arch/x86/kvm/Kconfig"
2736 source "lib/Kconfig"
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