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_KCOV if X86_64
32 select ARCH_HAS_PMEM_API if X86_64
33 select ARCH_HAS_MMIO_FLUSH
34 select ARCH_HAS_SG_CHAIN
35 select ARCH_HAS_UBSAN_SANITIZE_ALL
36 select ARCH_HAVE_NMI_SAFE_CMPXCHG
37 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
38 select ARCH_MIGHT_HAVE_PC_PARPORT
39 select ARCH_MIGHT_HAVE_PC_SERIO
40 select ARCH_SUPPORTS_ATOMIC_RMW
41 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
42 select ARCH_SUPPORTS_INT128 if X86_64
43 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
44 select ARCH_USE_BUILTIN_BSWAP
45 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
46 select ARCH_USE_QUEUED_RWLOCKS
47 select ARCH_USE_QUEUED_SPINLOCKS
48 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
49 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
50 select ARCH_WANT_FRAME_POINTERS
51 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
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_EBPF_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_EXIT_THREAD
108 select HAVE_FENTRY if X86_64
109 select HAVE_FTRACE_MCOUNT_RECORD
110 select HAVE_FUNCTION_GRAPH_FP_TEST
111 select HAVE_FUNCTION_GRAPH_TRACER
112 select HAVE_FUNCTION_TRACER
113 select HAVE_GENERIC_DMA_COHERENT if X86_32
114 select HAVE_HW_BREAKPOINT
116 select HAVE_IOREMAP_PROT
117 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
118 select HAVE_IRQ_TIME_ACCOUNTING
119 select HAVE_KERNEL_BZIP2
120 select HAVE_KERNEL_GZIP
121 select HAVE_KERNEL_LZ4
122 select HAVE_KERNEL_LZMA
123 select HAVE_KERNEL_LZO
124 select HAVE_KERNEL_XZ
126 select HAVE_KPROBES_ON_FTRACE
127 select HAVE_KRETPROBES
129 select HAVE_LIVEPATCH if X86_64
131 select HAVE_MEMBLOCK_NODE_MAP
132 select HAVE_MIXED_BREAKPOINTS_REGS
135 select HAVE_OPTPROBES
136 select HAVE_PCSPKR_PLATFORM
137 select HAVE_PERF_EVENTS
138 select HAVE_PERF_EVENTS_NMI
139 select HAVE_PERF_REGS
140 select HAVE_PERF_USER_STACK_DUMP
141 select HAVE_REGS_AND_STACK_ACCESS_API
142 select HAVE_SYSCALL_TRACEPOINTS
143 select HAVE_UID16 if X86_32 || IA32_EMULATION
144 select HAVE_UNSTABLE_SCHED_CLOCK
145 select HAVE_USER_RETURN_NOTIFIER
146 select IRQ_FORCED_THREADING
147 select MODULES_USE_ELF_RELA if X86_64
148 select MODULES_USE_ELF_REL if X86_32
149 select OLD_SIGACTION if X86_32
150 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
155 select SYSCTL_EXCEPTION_TRACE
156 select USER_STACKTRACE_SUPPORT
158 select X86_DEV_DMA_OPS if X86_64
159 select X86_FEATURE_NAMES if PROC_FS
160 select HAVE_STACK_VALIDATION if X86_64
161 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
162 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
164 config INSTRUCTION_DECODER
166 depends on KPROBES || PERF_EVENTS || UPROBES
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_SUPPORTS_UPROBES
299 config FIX_EARLYCON_MEM
305 config PGTABLE_LEVELS
311 source "init/Kconfig"
312 source "kernel/Kconfig.freezer"
314 menu "Processor type and features"
317 bool "DMA memory allocation support" if EXPERT
320 DMA memory allocation support allows devices with less than 32-bit
321 addressing to allocate within the first 16MB of address space.
322 Disable if no such devices will be used.
327 bool "Symmetric multi-processing support"
329 This enables support for systems with more than one CPU. If you have
330 a system with only one CPU, say N. If you have a system with more
333 If you say N here, the kernel will run on uni- and multiprocessor
334 machines, but will use only one CPU of a multiprocessor machine. If
335 you say Y here, the kernel will run on many, but not all,
336 uniprocessor machines. On a uniprocessor machine, the kernel
337 will run faster if you say N here.
339 Note that if you say Y here and choose architecture "586" or
340 "Pentium" under "Processor family", the kernel will not work on 486
341 architectures. Similarly, multiprocessor kernels for the "PPro"
342 architecture may not work on all Pentium based boards.
344 People using multiprocessor machines who say Y here should also say
345 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
346 Management" code will be disabled if you say Y here.
348 See also <file:Documentation/x86/i386/IO-APIC.txt>,
349 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
350 <http://www.tldp.org/docs.html#howto>.
352 If you don't know what to do here, say N.
354 config X86_FEATURE_NAMES
355 bool "Processor feature human-readable names" if EMBEDDED
358 This option compiles in a table of x86 feature bits and corresponding
359 names. This is required to support /proc/cpuinfo and a few kernel
360 messages. You can disable this to save space, at the expense of
361 making those few kernel messages show numeric feature bits instead.
365 config X86_FAST_FEATURE_TESTS
366 bool "Fast CPU feature tests" if EMBEDDED
369 Some fast-paths in the kernel depend on the capabilities of the CPU.
370 Say Y here for the kernel to patch in the appropriate code at runtime
371 based on the capabilities of the CPU. The infrastructure for patching
372 code at runtime takes up some additional space; space-constrained
373 embedded systems may wish to say N here to produce smaller, slightly
377 bool "Support x2apic"
378 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
380 This enables x2apic support on CPUs that have this feature.
382 This allows 32-bit apic IDs (so it can support very large systems),
383 and accesses the local apic via MSRs not via mmio.
385 If you don't know what to do here, say N.
388 bool "Enable MPS table" if ACPI || SFI
390 depends on X86_LOCAL_APIC
392 For old smp systems that do not have proper acpi support. Newer systems
393 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
396 bool "Support for big SMP systems with more than 8 CPUs"
397 depends on X86_32 && SMP
399 This option is needed for the systems that have more than 8 CPUs
403 depends on X86_GOLDFISH
406 config X86_EXTENDED_PLATFORM
407 bool "Support for extended (non-PC) x86 platforms"
410 If you disable this option then the kernel will only support
411 standard PC platforms. (which covers the vast majority of
414 If you enable this option then you'll be able to select support
415 for the following (non-PC) 32 bit x86 platforms:
416 Goldfish (Android emulator)
419 SGI 320/540 (Visual Workstation)
420 STA2X11-based (e.g. Northville)
421 Moorestown MID devices
423 If you have one of these systems, or if you want to build a
424 generic distribution kernel, say Y here - otherwise say N.
428 config X86_EXTENDED_PLATFORM
429 bool "Support for extended (non-PC) x86 platforms"
432 If you disable this option then the kernel will only support
433 standard PC platforms. (which covers the vast majority of
436 If you enable this option then you'll be able to select support
437 for the following (non-PC) 64 bit x86 platforms:
442 If you have one of these systems, or if you want to build a
443 generic distribution kernel, say Y here - otherwise say N.
445 # This is an alphabetically sorted list of 64 bit extended platforms
446 # Please maintain the alphabetic order if and when there are additions
448 bool "Numascale NumaChip"
450 depends on X86_EXTENDED_PLATFORM
453 depends on X86_X2APIC
454 depends on PCI_MMCONFIG
456 Adds support for Numascale NumaChip large-SMP systems. Needed to
457 enable more than ~168 cores.
458 If you don't have one of these, you should say N here.
462 select HYPERVISOR_GUEST
464 depends on X86_64 && PCI
465 depends on X86_EXTENDED_PLATFORM
468 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
469 supposed to run on these EM64T-based machines. Only choose this option
470 if you have one of these machines.
473 bool "SGI Ultraviolet"
475 depends on X86_EXTENDED_PLATFORM
478 depends on X86_X2APIC
481 This option is needed in order to support SGI Ultraviolet systems.
482 If you don't have one of these, you should say N here.
484 # Following is an alphabetically sorted list of 32 bit extended platforms
485 # Please maintain the alphabetic order if and when there are additions
488 bool "Goldfish (Virtual Platform)"
489 depends on X86_EXTENDED_PLATFORM
491 Enable support for the Goldfish virtual platform used primarily
492 for Android development. Unless you are building for the Android
493 Goldfish emulator say N here.
496 bool "CE4100 TV platform"
498 depends on PCI_GODIRECT
499 depends on X86_IO_APIC
501 depends on X86_EXTENDED_PLATFORM
502 select X86_REBOOTFIXUPS
504 select OF_EARLY_FLATTREE
506 Select for the Intel CE media processor (CE4100) SOC.
507 This option compiles in support for the CE4100 SOC for settop
508 boxes and media devices.
511 bool "Intel MID platform support"
512 depends on X86_EXTENDED_PLATFORM
513 depends on X86_PLATFORM_DEVICES
515 depends on X86_64 || (PCI_GOANY && X86_32)
516 depends on X86_IO_APIC
522 select MFD_INTEL_MSIC
524 Select to build a kernel capable of supporting Intel MID (Mobile
525 Internet Device) platform systems which do not have the PCI legacy
526 interfaces. If you are building for a PC class system say N here.
528 Intel MID platforms are based on an Intel processor and chipset which
529 consume less power than most of the x86 derivatives.
531 config X86_INTEL_QUARK
532 bool "Intel Quark platform support"
534 depends on X86_EXTENDED_PLATFORM
535 depends on X86_PLATFORM_DEVICES
539 depends on X86_IO_APIC
544 Select to include support for Quark X1000 SoC.
545 Say Y here if you have a Quark based system such as the Arduino
546 compatible Intel Galileo.
548 config X86_INTEL_LPSS
549 bool "Intel Low Power Subsystem Support"
550 depends on X86 && ACPI
555 Select to build support for Intel Low Power Subsystem such as
556 found on Intel Lynxpoint PCH. Selecting this option enables
557 things like clock tree (common clock framework) and pincontrol
558 which are needed by the LPSS peripheral drivers.
560 config X86_AMD_PLATFORM_DEVICE
561 bool "AMD ACPI2Platform devices support"
566 Select to interpret AMD specific ACPI device to platform device
567 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
568 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
569 implemented under PINCTRL subsystem.
572 tristate "Intel SoC IOSF Sideband support for SoC platforms"
575 This option enables sideband register access support for Intel SoC
576 platforms. On these platforms the IOSF sideband is used in lieu of
577 MSR's for some register accesses, mostly but not limited to thermal
578 and power. Drivers may query the availability of this device to
579 determine if they need the sideband in order to work on these
580 platforms. The sideband is available on the following SoC products.
581 This list is not meant to be exclusive.
586 You should say Y if you are running a kernel on one of these SoC's.
588 config IOSF_MBI_DEBUG
589 bool "Enable IOSF sideband access through debugfs"
590 depends on IOSF_MBI && DEBUG_FS
592 Select this option to expose the IOSF sideband access registers (MCR,
593 MDR, MCRX) through debugfs to write and read register information from
594 different units on the SoC. This is most useful for obtaining device
595 state information for debug and analysis. As this is a general access
596 mechanism, users of this option would have specific knowledge of the
597 device they want to access.
599 If you don't require the option or are in doubt, say N.
602 bool "RDC R-321x SoC"
604 depends on X86_EXTENDED_PLATFORM
606 select X86_REBOOTFIXUPS
608 This option is needed for RDC R-321x system-on-chip, also known
610 If you don't have one of these chips, you should say N here.
612 config X86_32_NON_STANDARD
613 bool "Support non-standard 32-bit SMP architectures"
614 depends on X86_32 && SMP
615 depends on X86_EXTENDED_PLATFORM
617 This option compiles in the bigsmp and STA2X11 default
618 subarchitectures. It is intended for a generic binary
619 kernel. If you select them all, kernel will probe it one by
620 one and will fallback to default.
622 # Alphabetically sorted list of Non standard 32 bit platforms
624 config X86_SUPPORTS_MEMORY_FAILURE
626 # MCE code calls memory_failure():
628 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
629 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
630 depends on X86_64 || !SPARSEMEM
631 select ARCH_SUPPORTS_MEMORY_FAILURE
634 bool "STA2X11 Companion Chip Support"
635 depends on X86_32_NON_STANDARD && PCI
636 select X86_DEV_DMA_OPS
643 This adds support for boards based on the STA2X11 IO-Hub,
644 a.k.a. "ConneXt". The chip is used in place of the standard
645 PC chipset, so all "standard" peripherals are missing. If this
646 option is selected the kernel will still be able to boot on
647 standard PC machines.
650 tristate "Eurobraille/Iris poweroff module"
653 The Iris machines from EuroBraille do not have APM or ACPI support
654 to shut themselves down properly. A special I/O sequence is
655 needed to do so, which is what this module does at
658 This is only for Iris machines from EuroBraille.
662 config SCHED_OMIT_FRAME_POINTER
664 prompt "Single-depth WCHAN output"
667 Calculate simpler /proc/<PID>/wchan values. If this option
668 is disabled then wchan values will recurse back to the
669 caller function. This provides more accurate wchan values,
670 at the expense of slightly more scheduling overhead.
672 If in doubt, say "Y".
674 menuconfig HYPERVISOR_GUEST
675 bool "Linux guest support"
677 Say Y here to enable options for running Linux under various hyper-
678 visors. This option enables basic hypervisor detection and platform
681 If you say N, all options in this submenu will be skipped and
682 disabled, and Linux guest support won't be built in.
687 bool "Enable paravirtualization code"
689 This changes the kernel so it can modify itself when it is run
690 under a hypervisor, potentially improving performance significantly
691 over full virtualization. However, when run without a hypervisor
692 the kernel is theoretically slower and slightly larger.
694 config PARAVIRT_DEBUG
695 bool "paravirt-ops debugging"
696 depends on PARAVIRT && DEBUG_KERNEL
698 Enable to debug paravirt_ops internals. Specifically, BUG if
699 a paravirt_op is missing when it is called.
701 config PARAVIRT_SPINLOCKS
702 bool "Paravirtualization layer for spinlocks"
703 depends on PARAVIRT && SMP
704 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
706 Paravirtualized spinlocks allow a pvops backend to replace the
707 spinlock implementation with something virtualization-friendly
708 (for example, block the virtual CPU rather than spinning).
710 It has a minimal impact on native kernels and gives a nice performance
711 benefit on paravirtualized KVM / Xen kernels.
713 If you are unsure how to answer this question, answer Y.
715 config QUEUED_LOCK_STAT
716 bool "Paravirt queued spinlock statistics"
717 depends on PARAVIRT_SPINLOCKS && DEBUG_FS && QUEUED_SPINLOCKS
719 Enable the collection of statistical data on the slowpath
720 behavior of paravirtualized queued spinlocks and report
723 source "arch/x86/xen/Kconfig"
726 bool "KVM Guest support (including kvmclock)"
728 select PARAVIRT_CLOCK
731 This option enables various optimizations for running under the KVM
732 hypervisor. It includes a paravirtualized clock, so that instead
733 of relying on a PIT (or probably other) emulation by the
734 underlying device model, the host provides the guest with
735 timing infrastructure such as time of day, and system time
738 bool "Enable debug information for KVM Guests in debugfs"
739 depends on KVM_GUEST && DEBUG_FS
742 This option enables collection of various statistics for KVM guest.
743 Statistics are displayed in debugfs filesystem. Enabling this option
744 may incur significant overhead.
746 source "arch/x86/lguest/Kconfig"
748 config PARAVIRT_TIME_ACCOUNTING
749 bool "Paravirtual steal time accounting"
753 Select this option to enable fine granularity task steal time
754 accounting. Time spent executing other tasks in parallel with
755 the current vCPU is discounted from the vCPU power. To account for
756 that, there can be a small performance impact.
758 If in doubt, say N here.
760 config PARAVIRT_CLOCK
763 endif #HYPERVISOR_GUEST
768 source "arch/x86/Kconfig.cpu"
772 prompt "HPET Timer Support" if X86_32
774 Use the IA-PC HPET (High Precision Event Timer) to manage
775 time in preference to the PIT and RTC, if a HPET is
777 HPET is the next generation timer replacing legacy 8254s.
778 The HPET provides a stable time base on SMP
779 systems, unlike the TSC, but it is more expensive to access,
780 as it is off-chip. The interface used is documented
781 in the HPET spec, revision 1.
783 You can safely choose Y here. However, HPET will only be
784 activated if the platform and the BIOS support this feature.
785 Otherwise the 8254 will be used for timing services.
787 Choose N to continue using the legacy 8254 timer.
789 config HPET_EMULATE_RTC
791 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
794 def_bool y if X86_INTEL_MID
795 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
797 depends on X86_INTEL_MID && SFI
799 APB timer is the replacement for 8254, HPET on X86 MID platforms.
800 The APBT provides a stable time base on SMP
801 systems, unlike the TSC, but it is more expensive to access,
802 as it is off-chip. APB timers are always running regardless of CPU
803 C states, they are used as per CPU clockevent device when possible.
805 # Mark as expert because too many people got it wrong.
806 # The code disables itself when not needed.
809 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
810 bool "Enable DMI scanning" if EXPERT
812 Enabled scanning of DMI to identify machine quirks. Say Y
813 here unless you have verified that your setup is not
814 affected by entries in the DMI blacklist. Required by PNP
818 bool "Old AMD GART IOMMU support"
820 depends on X86_64 && PCI && AMD_NB
822 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
823 GART based hardware IOMMUs.
825 The GART supports full DMA access for devices with 32-bit access
826 limitations, on systems with more than 3 GB. This is usually needed
827 for USB, sound, many IDE/SATA chipsets and some other devices.
829 Newer systems typically have a modern AMD IOMMU, supported via
830 the CONFIG_AMD_IOMMU=y config option.
832 In normal configurations this driver is only active when needed:
833 there's more than 3 GB of memory and the system contains a
834 32-bit limited device.
839 bool "IBM Calgary IOMMU support"
841 depends on X86_64 && PCI
843 Support for hardware IOMMUs in IBM's xSeries x366 and x460
844 systems. Needed to run systems with more than 3GB of memory
845 properly with 32-bit PCI devices that do not support DAC
846 (Double Address Cycle). Calgary also supports bus level
847 isolation, where all DMAs pass through the IOMMU. This
848 prevents them from going anywhere except their intended
849 destination. This catches hard-to-find kernel bugs and
850 mis-behaving drivers and devices that do not use the DMA-API
851 properly to set up their DMA buffers. The IOMMU can be
852 turned off at boot time with the iommu=off parameter.
853 Normally the kernel will make the right choice by itself.
856 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
858 prompt "Should Calgary be enabled by default?"
859 depends on CALGARY_IOMMU
861 Should Calgary be enabled by default? if you choose 'y', Calgary
862 will be used (if it exists). If you choose 'n', Calgary will not be
863 used even if it exists. If you choose 'n' and would like to use
864 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
867 # need this always selected by IOMMU for the VIA workaround
871 Support for software bounce buffers used on x86-64 systems
872 which don't have a hardware IOMMU. Using this PCI devices
873 which can only access 32-bits of memory can be used on systems
874 with more than 3 GB of memory.
879 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
882 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
883 depends on X86_64 && SMP && DEBUG_KERNEL
884 select CPUMASK_OFFSTACK
886 Enable maximum number of CPUS and NUMA Nodes for this architecture.
890 int "Maximum number of CPUs" if SMP && !MAXSMP
891 range 2 8 if SMP && X86_32 && !X86_BIGSMP
892 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
893 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
895 default "8192" if MAXSMP
896 default "32" if SMP && X86_BIGSMP
897 default "8" if SMP && X86_32
900 This allows you to specify the maximum number of CPUs which this
901 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
902 supported value is 8192, otherwise the maximum value is 512. The
903 minimum value which makes sense is 2.
905 This is purely to save memory - each supported CPU adds
906 approximately eight kilobytes to the kernel image.
909 bool "SMT (Hyperthreading) scheduler support"
912 SMT scheduler support improves the CPU scheduler's decision making
913 when dealing with Intel Pentium 4 chips with HyperThreading at a
914 cost of slightly increased overhead in some places. If unsure say
919 prompt "Multi-core scheduler support"
922 Multi-core scheduler support improves the CPU scheduler's decision
923 making when dealing with multi-core CPU chips at a cost of slightly
924 increased overhead in some places. If unsure say N here.
926 source "kernel/Kconfig.preempt"
930 depends on !SMP && X86_LOCAL_APIC
933 bool "Local APIC support on uniprocessors" if !PCI_MSI
935 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
937 A local APIC (Advanced Programmable Interrupt Controller) is an
938 integrated interrupt controller in the CPU. If you have a single-CPU
939 system which has a processor with a local APIC, you can say Y here to
940 enable and use it. If you say Y here even though your machine doesn't
941 have a local APIC, then the kernel will still run with no slowdown at
942 all. The local APIC supports CPU-generated self-interrupts (timer,
943 performance counters), and the NMI watchdog which detects hard
947 bool "IO-APIC support on uniprocessors"
948 depends on X86_UP_APIC
950 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
951 SMP-capable replacement for PC-style interrupt controllers. Most
952 SMP systems and many recent uniprocessor systems have one.
954 If you have a single-CPU system with an IO-APIC, you can say Y here
955 to use it. If you say Y here even though your machine doesn't have
956 an IO-APIC, then the kernel will still run with no slowdown at all.
958 config X86_LOCAL_APIC
960 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
961 select IRQ_DOMAIN_HIERARCHY
962 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
966 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
968 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
969 bool "Reroute for broken boot IRQs"
970 depends on X86_IO_APIC
972 This option enables a workaround that fixes a source of
973 spurious interrupts. This is recommended when threaded
974 interrupt handling is used on systems where the generation of
975 superfluous "boot interrupts" cannot be disabled.
977 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
978 entry in the chipset's IO-APIC is masked (as, e.g. the RT
979 kernel does during interrupt handling). On chipsets where this
980 boot IRQ generation cannot be disabled, this workaround keeps
981 the original IRQ line masked so that only the equivalent "boot
982 IRQ" is delivered to the CPUs. The workaround also tells the
983 kernel to set up the IRQ handler on the boot IRQ line. In this
984 way only one interrupt is delivered to the kernel. Otherwise
985 the spurious second interrupt may cause the kernel to bring
986 down (vital) interrupt lines.
988 Only affects "broken" chipsets. Interrupt sharing may be
989 increased on these systems.
992 bool "Machine Check / overheating reporting"
993 select GENERIC_ALLOCATOR
996 Machine Check support allows the processor to notify the
997 kernel if it detects a problem (e.g. overheating, data corruption).
998 The action the kernel takes depends on the severity of the problem,
999 ranging from warning messages to halting the machine.
1001 config X86_MCE_INTEL
1003 prompt "Intel MCE features"
1004 depends on X86_MCE && X86_LOCAL_APIC
1006 Additional support for intel specific MCE features such as
1007 the thermal monitor.
1011 prompt "AMD MCE features"
1012 depends on X86_MCE && X86_LOCAL_APIC
1014 Additional support for AMD specific MCE features such as
1015 the DRAM Error Threshold.
1017 config X86_ANCIENT_MCE
1018 bool "Support for old Pentium 5 / WinChip machine checks"
1019 depends on X86_32 && X86_MCE
1021 Include support for machine check handling on old Pentium 5 or WinChip
1022 systems. These typically need to be enabled explicitly on the command
1025 config X86_MCE_THRESHOLD
1026 depends on X86_MCE_AMD || X86_MCE_INTEL
1029 config X86_MCE_INJECT
1031 tristate "Machine check injector support"
1033 Provide support for injecting machine checks for testing purposes.
1034 If you don't know what a machine check is and you don't do kernel
1035 QA it is safe to say n.
1037 config X86_THERMAL_VECTOR
1039 depends on X86_MCE_INTEL
1041 source "arch/x86/events/Kconfig"
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
1166 If you say Y here, you will be able to update the microcode on
1167 Intel and AMD processors. The Intel support is for the IA32 family,
1168 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1169 AMD support is for families 0x10 and later. You will obviously need
1170 the actual microcode binary data itself which is not shipped with
1173 The preferred method to load microcode from a detached initrd is described
1174 in Documentation/x86/early-microcode.txt. For that you need to enable
1175 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1176 initrd for microcode blobs.
1178 In addition, you can build-in the microcode into the kernel. For that you
1179 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1180 to the CONFIG_EXTRA_FIRMWARE config option.
1182 config MICROCODE_INTEL
1183 bool "Intel microcode loading support"
1184 depends on MICROCODE
1188 This options enables microcode patch loading support for Intel
1191 For the current Intel microcode data package go to
1192 <https://downloadcenter.intel.com> and search for
1193 'Linux Processor Microcode Data File'.
1195 config MICROCODE_AMD
1196 bool "AMD microcode loading support"
1197 depends on MICROCODE
1200 If you select this option, microcode patch loading support for AMD
1201 processors will be enabled.
1203 config MICROCODE_OLD_INTERFACE
1205 depends on MICROCODE
1208 tristate "/dev/cpu/*/msr - Model-specific register support"
1210 This device gives privileged processes access to the x86
1211 Model-Specific Registers (MSRs). It is a character device with
1212 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1213 MSR accesses are directed to a specific CPU on multi-processor
1217 tristate "/dev/cpu/*/cpuid - CPU information support"
1219 This device gives processes access to the x86 CPUID instruction to
1220 be executed on a specific processor. It is a character device
1221 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1225 prompt "High Memory Support"
1232 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1233 However, the address space of 32-bit x86 processors is only 4
1234 Gigabytes large. That means that, if you have a large amount of
1235 physical memory, not all of it can be "permanently mapped" by the
1236 kernel. The physical memory that's not permanently mapped is called
1239 If you are compiling a kernel which will never run on a machine with
1240 more than 1 Gigabyte total physical RAM, answer "off" here (default
1241 choice and suitable for most users). This will result in a "3GB/1GB"
1242 split: 3GB are mapped so that each process sees a 3GB virtual memory
1243 space and the remaining part of the 4GB virtual memory space is used
1244 by the kernel to permanently map as much physical memory as
1247 If the machine has between 1 and 4 Gigabytes physical RAM, then
1250 If more than 4 Gigabytes is used then answer "64GB" here. This
1251 selection turns Intel PAE (Physical Address Extension) mode on.
1252 PAE implements 3-level paging on IA32 processors. PAE is fully
1253 supported by Linux, PAE mode is implemented on all recent Intel
1254 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1255 then the kernel will not boot on CPUs that don't support PAE!
1257 The actual amount of total physical memory will either be
1258 auto detected or can be forced by using a kernel command line option
1259 such as "mem=256M". (Try "man bootparam" or see the documentation of
1260 your boot loader (lilo or loadlin) about how to pass options to the
1261 kernel at boot time.)
1263 If unsure, say "off".
1268 Select this if you have a 32-bit processor and between 1 and 4
1269 gigabytes of physical RAM.
1276 Select this if you have a 32-bit processor and more than 4
1277 gigabytes of physical RAM.
1282 prompt "Memory split" if EXPERT
1286 Select the desired split between kernel and user memory.
1288 If the address range available to the kernel is less than the
1289 physical memory installed, the remaining memory will be available
1290 as "high memory". Accessing high memory is a little more costly
1291 than low memory, as it needs to be mapped into the kernel first.
1292 Note that increasing the kernel address space limits the range
1293 available to user programs, making the address space there
1294 tighter. Selecting anything other than the default 3G/1G split
1295 will also likely make your kernel incompatible with binary-only
1298 If you are not absolutely sure what you are doing, leave this
1302 bool "3G/1G user/kernel split"
1303 config VMSPLIT_3G_OPT
1305 bool "3G/1G user/kernel split (for full 1G low memory)"
1307 bool "2G/2G user/kernel split"
1308 config VMSPLIT_2G_OPT
1310 bool "2G/2G user/kernel split (for full 2G low memory)"
1312 bool "1G/3G user/kernel split"
1317 default 0xB0000000 if VMSPLIT_3G_OPT
1318 default 0x80000000 if VMSPLIT_2G
1319 default 0x78000000 if VMSPLIT_2G_OPT
1320 default 0x40000000 if VMSPLIT_1G
1326 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1329 bool "PAE (Physical Address Extension) Support"
1330 depends on X86_32 && !HIGHMEM4G
1333 PAE is required for NX support, and furthermore enables
1334 larger swapspace support for non-overcommit purposes. It
1335 has the cost of more pagetable lookup overhead, and also
1336 consumes more pagetable space per process.
1338 config ARCH_PHYS_ADDR_T_64BIT
1340 depends on X86_64 || X86_PAE
1342 config ARCH_DMA_ADDR_T_64BIT
1344 depends on X86_64 || HIGHMEM64G
1346 config X86_DIRECT_GBPAGES
1348 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1350 Certain kernel features effectively disable kernel
1351 linear 1 GB mappings (even if the CPU otherwise
1352 supports them), so don't confuse the user by printing
1353 that we have them enabled.
1355 # Common NUMA Features
1357 bool "Numa Memory Allocation and Scheduler Support"
1359 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1360 default y if X86_BIGSMP
1362 Enable NUMA (Non Uniform Memory Access) support.
1364 The kernel will try to allocate memory used by a CPU on the
1365 local memory controller of the CPU and add some more
1366 NUMA awareness to the kernel.
1368 For 64-bit this is recommended if the system is Intel Core i7
1369 (or later), AMD Opteron, or EM64T NUMA.
1371 For 32-bit this is only needed if you boot a 32-bit
1372 kernel on a 64-bit NUMA platform.
1374 Otherwise, you should say N.
1378 prompt "Old style AMD Opteron NUMA detection"
1379 depends on X86_64 && NUMA && PCI
1381 Enable AMD NUMA node topology detection. You should say Y here if
1382 you have a multi processor AMD system. This uses an old method to
1383 read the NUMA configuration directly from the builtin Northbridge
1384 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1385 which also takes priority if both are compiled in.
1387 config X86_64_ACPI_NUMA
1389 prompt "ACPI NUMA detection"
1390 depends on X86_64 && NUMA && ACPI && PCI
1393 Enable ACPI SRAT based node topology detection.
1395 # Some NUMA nodes have memory ranges that span
1396 # other nodes. Even though a pfn is valid and
1397 # between a node's start and end pfns, it may not
1398 # reside on that node. See memmap_init_zone()
1400 config NODES_SPAN_OTHER_NODES
1402 depends on X86_64_ACPI_NUMA
1405 bool "NUMA emulation"
1408 Enable NUMA emulation. A flat machine will be split
1409 into virtual nodes when booted with "numa=fake=N", where N is the
1410 number of nodes. This is only useful for debugging.
1413 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1415 default "10" if MAXSMP
1416 default "6" if X86_64
1418 depends on NEED_MULTIPLE_NODES
1420 Specify the maximum number of NUMA Nodes available on the target
1421 system. Increases memory reserved to accommodate various tables.
1423 config ARCH_HAVE_MEMORY_PRESENT
1425 depends on X86_32 && DISCONTIGMEM
1427 config NEED_NODE_MEMMAP_SIZE
1429 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1431 config ARCH_FLATMEM_ENABLE
1433 depends on X86_32 && !NUMA
1435 config ARCH_DISCONTIGMEM_ENABLE
1437 depends on NUMA && X86_32
1439 config ARCH_DISCONTIGMEM_DEFAULT
1441 depends on NUMA && X86_32
1443 config ARCH_SPARSEMEM_ENABLE
1445 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1446 select SPARSEMEM_STATIC if X86_32
1447 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1449 config ARCH_SPARSEMEM_DEFAULT
1453 config ARCH_SELECT_MEMORY_MODEL
1455 depends on ARCH_SPARSEMEM_ENABLE
1457 config ARCH_MEMORY_PROBE
1458 bool "Enable sysfs memory/probe interface"
1459 depends on X86_64 && MEMORY_HOTPLUG
1461 This option enables a sysfs memory/probe interface for testing.
1462 See Documentation/memory-hotplug.txt for more information.
1463 If you are unsure how to answer this question, answer N.
1465 config ARCH_PROC_KCORE_TEXT
1467 depends on X86_64 && PROC_KCORE
1469 config ILLEGAL_POINTER_VALUE
1472 default 0xdead000000000000 if X86_64
1476 config X86_PMEM_LEGACY_DEVICE
1479 config X86_PMEM_LEGACY
1480 tristate "Support non-standard NVDIMMs and ADR protected memory"
1481 depends on PHYS_ADDR_T_64BIT
1483 select X86_PMEM_LEGACY_DEVICE
1486 Treat memory marked using the non-standard e820 type of 12 as used
1487 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1488 The kernel will offer these regions to the 'pmem' driver so
1489 they can be used for persistent storage.
1494 bool "Allocate 3rd-level pagetables from highmem"
1497 The VM uses one page table entry for each page of physical memory.
1498 For systems with a lot of RAM, this can be wasteful of precious
1499 low memory. Setting this option will put user-space page table
1500 entries in high memory.
1502 config X86_CHECK_BIOS_CORRUPTION
1503 bool "Check for low memory corruption"
1505 Periodically check for memory corruption in low memory, which
1506 is suspected to be caused by BIOS. Even when enabled in the
1507 configuration, it is disabled at runtime. Enable it by
1508 setting "memory_corruption_check=1" on the kernel command
1509 line. By default it scans the low 64k of memory every 60
1510 seconds; see the memory_corruption_check_size and
1511 memory_corruption_check_period parameters in
1512 Documentation/kernel-parameters.txt to adjust this.
1514 When enabled with the default parameters, this option has
1515 almost no overhead, as it reserves a relatively small amount
1516 of memory and scans it infrequently. It both detects corruption
1517 and prevents it from affecting the running system.
1519 It is, however, intended as a diagnostic tool; if repeatable
1520 BIOS-originated corruption always affects the same memory,
1521 you can use memmap= to prevent the kernel from using that
1524 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1525 bool "Set the default setting of memory_corruption_check"
1526 depends on X86_CHECK_BIOS_CORRUPTION
1529 Set whether the default state of memory_corruption_check is
1532 config X86_RESERVE_LOW
1533 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1537 Specify the amount of low memory to reserve for the BIOS.
1539 The first page contains BIOS data structures that the kernel
1540 must not use, so that page must always be reserved.
1542 By default we reserve the first 64K of physical RAM, as a
1543 number of BIOSes are known to corrupt that memory range
1544 during events such as suspend/resume or monitor cable
1545 insertion, so it must not be used by the kernel.
1547 You can set this to 4 if you are absolutely sure that you
1548 trust the BIOS to get all its memory reservations and usages
1549 right. If you know your BIOS have problems beyond the
1550 default 64K area, you can set this to 640 to avoid using the
1551 entire low memory range.
1553 If you have doubts about the BIOS (e.g. suspend/resume does
1554 not work or there's kernel crashes after certain hardware
1555 hotplug events) then you might want to enable
1556 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1557 typical corruption patterns.
1559 Leave this to the default value of 64 if you are unsure.
1561 config MATH_EMULATION
1563 depends on MODIFY_LDT_SYSCALL
1564 prompt "Math emulation" if X86_32
1566 Linux can emulate a math coprocessor (used for floating point
1567 operations) if you don't have one. 486DX and Pentium processors have
1568 a math coprocessor built in, 486SX and 386 do not, unless you added
1569 a 487DX or 387, respectively. (The messages during boot time can
1570 give you some hints here ["man dmesg"].) Everyone needs either a
1571 coprocessor or this emulation.
1573 If you don't have a math coprocessor, you need to say Y here; if you
1574 say Y here even though you have a coprocessor, the coprocessor will
1575 be used nevertheless. (This behavior can be changed with the kernel
1576 command line option "no387", which comes handy if your coprocessor
1577 is broken. Try "man bootparam" or see the documentation of your boot
1578 loader (lilo or loadlin) about how to pass options to the kernel at
1579 boot time.) This means that it is a good idea to say Y here if you
1580 intend to use this kernel on different machines.
1582 More information about the internals of the Linux math coprocessor
1583 emulation can be found in <file:arch/x86/math-emu/README>.
1585 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1586 kernel, it won't hurt.
1590 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1592 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1593 the Memory Type Range Registers (MTRRs) may be used to control
1594 processor access to memory ranges. This is most useful if you have
1595 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1596 allows bus write transfers to be combined into a larger transfer
1597 before bursting over the PCI/AGP bus. This can increase performance
1598 of image write operations 2.5 times or more. Saying Y here creates a
1599 /proc/mtrr file which may be used to manipulate your processor's
1600 MTRRs. Typically the X server should use this.
1602 This code has a reasonably generic interface so that similar
1603 control registers on other processors can be easily supported
1606 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1607 Registers (ARRs) which provide a similar functionality to MTRRs. For
1608 these, the ARRs are used to emulate the MTRRs.
1609 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1610 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1611 write-combining. All of these processors are supported by this code
1612 and it makes sense to say Y here if you have one of them.
1614 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1615 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1616 can lead to all sorts of problems, so it's good to say Y here.
1618 You can safely say Y even if your machine doesn't have MTRRs, you'll
1619 just add about 9 KB to your kernel.
1621 See <file:Documentation/x86/mtrr.txt> for more information.
1623 config MTRR_SANITIZER
1625 prompt "MTRR cleanup support"
1628 Convert MTRR layout from continuous to discrete, so X drivers can
1629 add writeback entries.
1631 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1632 The largest mtrr entry size for a continuous block can be set with
1637 config MTRR_SANITIZER_ENABLE_DEFAULT
1638 int "MTRR cleanup enable value (0-1)"
1641 depends on MTRR_SANITIZER
1643 Enable mtrr cleanup default value
1645 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1646 int "MTRR cleanup spare reg num (0-7)"
1649 depends on MTRR_SANITIZER
1651 mtrr cleanup spare entries default, it can be changed via
1652 mtrr_spare_reg_nr=N on the kernel command line.
1656 prompt "x86 PAT support" if EXPERT
1659 Use PAT attributes to setup page level cache control.
1661 PATs are the modern equivalents of MTRRs and are much more
1662 flexible than MTRRs.
1664 Say N here if you see bootup problems (boot crash, boot hang,
1665 spontaneous reboots) or a non-working video driver.
1669 config ARCH_USES_PG_UNCACHED
1675 prompt "x86 architectural random number generator" if EXPERT
1677 Enable the x86 architectural RDRAND instruction
1678 (Intel Bull Mountain technology) to generate random numbers.
1679 If supported, this is a high bandwidth, cryptographically
1680 secure hardware random number generator.
1684 prompt "Supervisor Mode Access Prevention" if EXPERT
1686 Supervisor Mode Access Prevention (SMAP) is a security
1687 feature in newer Intel processors. There is a small
1688 performance cost if this enabled and turned on; there is
1689 also a small increase in the kernel size if this is enabled.
1693 config X86_INTEL_MPX
1694 prompt "Intel MPX (Memory Protection Extensions)"
1696 depends on CPU_SUP_INTEL
1698 MPX provides hardware features that can be used in
1699 conjunction with compiler-instrumented code to check
1700 memory references. It is designed to detect buffer
1701 overflow or underflow bugs.
1703 This option enables running applications which are
1704 instrumented or otherwise use MPX. It does not use MPX
1705 itself inside the kernel or to protect the kernel
1706 against bad memory references.
1708 Enabling this option will make the kernel larger:
1709 ~8k of kernel text and 36 bytes of data on a 64-bit
1710 defconfig. It adds a long to the 'mm_struct' which
1711 will increase the kernel memory overhead of each
1712 process and adds some branches to paths used during
1713 exec() and munmap().
1715 For details, see Documentation/x86/intel_mpx.txt
1719 config X86_INTEL_MEMORY_PROTECTION_KEYS
1720 prompt "Intel Memory Protection Keys"
1722 # Note: only available in 64-bit mode
1723 depends on CPU_SUP_INTEL && X86_64
1725 Memory Protection Keys provides a mechanism for enforcing
1726 page-based protections, but without requiring modification of the
1727 page tables when an application changes protection domains.
1729 For details, see Documentation/x86/protection-keys.txt
1734 bool "EFI runtime service support"
1737 select EFI_RUNTIME_WRAPPERS
1739 This enables the kernel to use EFI runtime services that are
1740 available (such as the EFI variable services).
1742 This option is only useful on systems that have EFI firmware.
1743 In addition, you should use the latest ELILO loader available
1744 at <http://elilo.sourceforge.net> in order to take advantage
1745 of EFI runtime services. However, even with this option, the
1746 resultant kernel should continue to boot on existing non-EFI
1750 bool "EFI stub support"
1751 depends on EFI && !X86_USE_3DNOW
1754 This kernel feature allows a bzImage to be loaded directly
1755 by EFI firmware without the use of a bootloader.
1757 See Documentation/efi-stub.txt for more information.
1760 bool "EFI mixed-mode support"
1761 depends on EFI_STUB && X86_64
1763 Enabling this feature allows a 64-bit kernel to be booted
1764 on a 32-bit firmware, provided that your CPU supports 64-bit
1767 Note that it is not possible to boot a mixed-mode enabled
1768 kernel via the EFI boot stub - a bootloader that supports
1769 the EFI handover protocol must be used.
1775 prompt "Enable seccomp to safely compute untrusted bytecode"
1777 This kernel feature is useful for number crunching applications
1778 that may need to compute untrusted bytecode during their
1779 execution. By using pipes or other transports made available to
1780 the process as file descriptors supporting the read/write
1781 syscalls, it's possible to isolate those applications in
1782 their own address space using seccomp. Once seccomp is
1783 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1784 and the task is only allowed to execute a few safe syscalls
1785 defined by each seccomp mode.
1787 If unsure, say Y. Only embedded should say N here.
1789 source kernel/Kconfig.hz
1792 bool "kexec system call"
1795 kexec is a system call that implements the ability to shutdown your
1796 current kernel, and to start another kernel. It is like a reboot
1797 but it is independent of the system firmware. And like a reboot
1798 you can start any kernel with it, not just Linux.
1800 The name comes from the similarity to the exec system call.
1802 It is an ongoing process to be certain the hardware in a machine
1803 is properly shutdown, so do not be surprised if this code does not
1804 initially work for you. As of this writing the exact hardware
1805 interface is strongly in flux, so no good recommendation can be
1809 bool "kexec file based system call"
1814 depends on CRYPTO_SHA256=y
1816 This is new version of kexec system call. This system call is
1817 file based and takes file descriptors as system call argument
1818 for kernel and initramfs as opposed to list of segments as
1819 accepted by previous system call.
1821 config KEXEC_VERIFY_SIG
1822 bool "Verify kernel signature during kexec_file_load() syscall"
1823 depends on KEXEC_FILE
1825 This option makes kernel signature verification mandatory for
1826 the kexec_file_load() syscall.
1828 In addition to that option, you need to enable signature
1829 verification for the corresponding kernel image type being
1830 loaded in order for this to work.
1832 config KEXEC_BZIMAGE_VERIFY_SIG
1833 bool "Enable bzImage signature verification support"
1834 depends on KEXEC_VERIFY_SIG
1835 depends on SIGNED_PE_FILE_VERIFICATION
1836 select SYSTEM_TRUSTED_KEYRING
1838 Enable bzImage signature verification support.
1841 bool "kernel crash dumps"
1842 depends on X86_64 || (X86_32 && HIGHMEM)
1844 Generate crash dump after being started by kexec.
1845 This should be normally only set in special crash dump kernels
1846 which are loaded in the main kernel with kexec-tools into
1847 a specially reserved region and then later executed after
1848 a crash by kdump/kexec. The crash dump kernel must be compiled
1849 to a memory address not used by the main kernel or BIOS using
1850 PHYSICAL_START, or it must be built as a relocatable image
1851 (CONFIG_RELOCATABLE=y).
1852 For more details see Documentation/kdump/kdump.txt
1856 depends on KEXEC && HIBERNATION
1858 Jump between original kernel and kexeced kernel and invoke
1859 code in physical address mode via KEXEC
1861 config PHYSICAL_START
1862 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1865 This gives the physical address where the kernel is loaded.
1867 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1868 bzImage will decompress itself to above physical address and
1869 run from there. Otherwise, bzImage will run from the address where
1870 it has been loaded by the boot loader and will ignore above physical
1873 In normal kdump cases one does not have to set/change this option
1874 as now bzImage can be compiled as a completely relocatable image
1875 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1876 address. This option is mainly useful for the folks who don't want
1877 to use a bzImage for capturing the crash dump and want to use a
1878 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1879 to be specifically compiled to run from a specific memory area
1880 (normally a reserved region) and this option comes handy.
1882 So if you are using bzImage for capturing the crash dump,
1883 leave the value here unchanged to 0x1000000 and set
1884 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1885 for capturing the crash dump change this value to start of
1886 the reserved region. In other words, it can be set based on
1887 the "X" value as specified in the "crashkernel=YM@XM"
1888 command line boot parameter passed to the panic-ed
1889 kernel. Please take a look at Documentation/kdump/kdump.txt
1890 for more details about crash dumps.
1892 Usage of bzImage for capturing the crash dump is recommended as
1893 one does not have to build two kernels. Same kernel can be used
1894 as production kernel and capture kernel. Above option should have
1895 gone away after relocatable bzImage support is introduced. But it
1896 is present because there are users out there who continue to use
1897 vmlinux for dump capture. This option should go away down the
1900 Don't change this unless you know what you are doing.
1903 bool "Build a relocatable kernel"
1906 This builds a kernel image that retains relocation information
1907 so it can be loaded someplace besides the default 1MB.
1908 The relocations tend to make the kernel binary about 10% larger,
1909 but are discarded at runtime.
1911 One use is for the kexec on panic case where the recovery kernel
1912 must live at a different physical address than the primary
1915 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1916 it has been loaded at and the compile time physical address
1917 (CONFIG_PHYSICAL_START) is used as the minimum location.
1919 config RANDOMIZE_BASE
1920 bool "Randomize the address of the kernel image (KASLR)"
1921 depends on RELOCATABLE
1924 In support of Kernel Address Space Layout Randomization (KASLR),
1925 this randomizes the physical address at which the kernel image
1926 is decompressed and the virtual address where the kernel
1927 image is mapped, as a security feature that deters exploit
1928 attempts relying on knowledge of the location of kernel
1931 On 64-bit, the kernel physical and virtual addresses are
1932 randomized separately. The physical address will be anywhere
1933 between 16MB and the top of physical memory (up to 64TB). The
1934 virtual address will be randomized from 16MB up to 1GB (9 bits
1935 of entropy). Note that this also reduces the memory space
1936 available to kernel modules from 1.5GB to 1GB.
1938 On 32-bit, the kernel physical and virtual addresses are
1939 randomized together. They will be randomized from 16MB up to
1940 512MB (8 bits of entropy).
1942 Entropy is generated using the RDRAND instruction if it is
1943 supported. If RDTSC is supported, its value is mixed into
1944 the entropy pool as well. If neither RDRAND nor RDTSC are
1945 supported, then entropy is read from the i8254 timer. The
1946 usable entropy is limited by the kernel being built using
1947 2GB addressing, and that PHYSICAL_ALIGN must be at a
1948 minimum of 2MB. As a result, only 10 bits of entropy are
1949 theoretically possible, but the implementations are further
1950 limited due to memory layouts.
1952 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1953 time. To enable it, boot with "kaslr" on the kernel command
1954 line (which will also disable hibernation).
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.
1990 config RANDOMIZE_MEMORY
1991 bool "Randomize the kernel memory sections"
1993 depends on RANDOMIZE_BASE
1994 default RANDOMIZE_BASE
1996 Randomizes the base virtual address of kernel memory sections
1997 (physical memory mapping, vmalloc & vmemmap). This security feature
1998 makes exploits relying on predictable memory locations less reliable.
2000 The order of allocations remains unchanged. Entropy is generated in
2001 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2002 configuration have in average 30,000 different possible virtual
2003 addresses for each memory section.
2007 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2008 hex "Physical memory mapping padding" if EXPERT
2009 depends on RANDOMIZE_MEMORY
2010 default "0xa" if MEMORY_HOTPLUG
2012 range 0x1 0x40 if MEMORY_HOTPLUG
2015 Define the padding in terabytes added to the existing physical
2016 memory size during kernel memory randomization. It is useful
2017 for memory hotplug support but reduces the entropy available for
2018 address randomization.
2020 If unsure, leave at the default value.
2023 bool "Support for hot-pluggable CPUs"
2026 Say Y here to allow turning CPUs off and on. CPUs can be
2027 controlled through /sys/devices/system/cpu.
2028 ( Note: power management support will enable this option
2029 automatically on SMP systems. )
2030 Say N if you want to disable CPU hotplug.
2032 config BOOTPARAM_HOTPLUG_CPU0
2033 bool "Set default setting of cpu0_hotpluggable"
2035 depends on HOTPLUG_CPU
2037 Set whether default state of cpu0_hotpluggable is on or off.
2039 Say Y here to enable CPU0 hotplug by default. If this switch
2040 is turned on, there is no need to give cpu0_hotplug kernel
2041 parameter and the CPU0 hotplug feature is enabled by default.
2043 Please note: there are two known CPU0 dependencies if you want
2044 to enable the CPU0 hotplug feature either by this switch or by
2045 cpu0_hotplug kernel parameter.
2047 First, resume from hibernate or suspend always starts from CPU0.
2048 So hibernate and suspend are prevented if CPU0 is offline.
2050 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2051 offline if any interrupt can not migrate out of CPU0. There may
2052 be other CPU0 dependencies.
2054 Please make sure the dependencies are under your control before
2055 you enable this feature.
2057 Say N if you don't want to enable CPU0 hotplug feature by default.
2058 You still can enable the CPU0 hotplug feature at boot by kernel
2059 parameter cpu0_hotplug.
2061 config DEBUG_HOTPLUG_CPU0
2063 prompt "Debug CPU0 hotplug"
2064 depends on HOTPLUG_CPU
2066 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2067 soon as possible and boots up userspace with CPU0 offlined. User
2068 can online CPU0 back after boot time.
2070 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2071 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2072 compilation or giving cpu0_hotplug kernel parameter at boot.
2078 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2079 depends on X86_32 || IA32_EMULATION
2081 Certain buggy versions of glibc will crash if they are
2082 presented with a 32-bit vDSO that is not mapped at the address
2083 indicated in its segment table.
2085 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2086 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2087 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2088 the only released version with the bug, but OpenSUSE 9
2089 contains a buggy "glibc 2.3.2".
2091 The symptom of the bug is that everything crashes on startup, saying:
2092 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2094 Saying Y here changes the default value of the vdso32 boot
2095 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2096 This works around the glibc bug but hurts performance.
2098 If unsure, say N: if you are compiling your own kernel, you
2099 are unlikely to be using a buggy version of glibc.
2102 prompt "vsyscall table for legacy applications"
2104 default LEGACY_VSYSCALL_EMULATE
2106 Legacy user code that does not know how to find the vDSO expects
2107 to be able to issue three syscalls by calling fixed addresses in
2108 kernel space. Since this location is not randomized with ASLR,
2109 it can be used to assist security vulnerability exploitation.
2111 This setting can be changed at boot time via the kernel command
2112 line parameter vsyscall=[native|emulate|none].
2114 On a system with recent enough glibc (2.14 or newer) and no
2115 static binaries, you can say None without a performance penalty
2116 to improve security.
2118 If unsure, select "Emulate".
2120 config LEGACY_VSYSCALL_NATIVE
2123 Actual executable code is located in the fixed vsyscall
2124 address mapping, implementing time() efficiently. Since
2125 this makes the mapping executable, it can be used during
2126 security vulnerability exploitation (traditionally as
2127 ROP gadgets). This configuration is not recommended.
2129 config LEGACY_VSYSCALL_EMULATE
2132 The kernel traps and emulates calls into the fixed
2133 vsyscall address mapping. This makes the mapping
2134 non-executable, but it still contains known contents,
2135 which could be used in certain rare security vulnerability
2136 exploits. This configuration is recommended when userspace
2137 still uses the vsyscall area.
2139 config LEGACY_VSYSCALL_NONE
2142 There will be no vsyscall mapping at all. This will
2143 eliminate any risk of ASLR bypass due to the vsyscall
2144 fixed address mapping. Attempts to use the vsyscalls
2145 will be reported to dmesg, so that either old or
2146 malicious userspace programs can be identified.
2151 bool "Built-in kernel command line"
2153 Allow for specifying boot arguments to the kernel at
2154 build time. On some systems (e.g. embedded ones), it is
2155 necessary or convenient to provide some or all of the
2156 kernel boot arguments with the kernel itself (that is,
2157 to not rely on the boot loader to provide them.)
2159 To compile command line arguments into the kernel,
2160 set this option to 'Y', then fill in the
2161 boot arguments in CONFIG_CMDLINE.
2163 Systems with fully functional boot loaders (i.e. non-embedded)
2164 should leave this option set to 'N'.
2167 string "Built-in kernel command string"
2168 depends on CMDLINE_BOOL
2171 Enter arguments here that should be compiled into the kernel
2172 image and used at boot time. If the boot loader provides a
2173 command line at boot time, it is appended to this string to
2174 form the full kernel command line, when the system boots.
2176 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2177 change this behavior.
2179 In most cases, the command line (whether built-in or provided
2180 by the boot loader) should specify the device for the root
2183 config CMDLINE_OVERRIDE
2184 bool "Built-in command line overrides boot loader arguments"
2185 depends on CMDLINE_BOOL
2187 Set this option to 'Y' to have the kernel ignore the boot loader
2188 command line, and use ONLY the built-in command line.
2190 This is used to work around broken boot loaders. This should
2191 be set to 'N' under normal conditions.
2193 config MODIFY_LDT_SYSCALL
2194 bool "Enable the LDT (local descriptor table)" if EXPERT
2197 Linux can allow user programs to install a per-process x86
2198 Local Descriptor Table (LDT) using the modify_ldt(2) system
2199 call. This is required to run 16-bit or segmented code such as
2200 DOSEMU or some Wine programs. It is also used by some very old
2201 threading libraries.
2203 Enabling this feature adds a small amount of overhead to
2204 context switches and increases the low-level kernel attack
2205 surface. Disabling it removes the modify_ldt(2) system call.
2207 Saying 'N' here may make sense for embedded or server kernels.
2209 source "kernel/livepatch/Kconfig"
2213 config ARCH_ENABLE_MEMORY_HOTPLUG
2215 depends on X86_64 || (X86_32 && HIGHMEM)
2217 config ARCH_ENABLE_MEMORY_HOTREMOVE
2219 depends on MEMORY_HOTPLUG
2221 config USE_PERCPU_NUMA_NODE_ID
2225 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2227 depends on X86_64 || X86_PAE
2229 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2231 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2233 menu "Power management and ACPI options"
2235 config ARCH_HIBERNATION_HEADER
2237 depends on X86_64 && HIBERNATION
2239 source "kernel/power/Kconfig"
2241 source "drivers/acpi/Kconfig"
2243 source "drivers/sfi/Kconfig"
2250 tristate "APM (Advanced Power Management) BIOS support"
2251 depends on X86_32 && PM_SLEEP
2253 APM is a BIOS specification for saving power using several different
2254 techniques. This is mostly useful for battery powered laptops with
2255 APM compliant BIOSes. If you say Y here, the system time will be
2256 reset after a RESUME operation, the /proc/apm device will provide
2257 battery status information, and user-space programs will receive
2258 notification of APM "events" (e.g. battery status change).
2260 If you select "Y" here, you can disable actual use of the APM
2261 BIOS by passing the "apm=off" option to the kernel at boot time.
2263 Note that the APM support is almost completely disabled for
2264 machines with more than one CPU.
2266 In order to use APM, you will need supporting software. For location
2267 and more information, read <file:Documentation/power/apm-acpi.txt>
2268 and the Battery Powered Linux mini-HOWTO, available from
2269 <http://www.tldp.org/docs.html#howto>.
2271 This driver does not spin down disk drives (see the hdparm(8)
2272 manpage ("man 8 hdparm") for that), and it doesn't turn off
2273 VESA-compliant "green" monitors.
2275 This driver does not support the TI 4000M TravelMate and the ACER
2276 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2277 desktop machines also don't have compliant BIOSes, and this driver
2278 may cause those machines to panic during the boot phase.
2280 Generally, if you don't have a battery in your machine, there isn't
2281 much point in using this driver and you should say N. If you get
2282 random kernel OOPSes or reboots that don't seem to be related to
2283 anything, try disabling/enabling this option (or disabling/enabling
2286 Some other things you should try when experiencing seemingly random,
2289 1) make sure that you have enough swap space and that it is
2291 2) pass the "no-hlt" option to the kernel
2292 3) switch on floating point emulation in the kernel and pass
2293 the "no387" option to the kernel
2294 4) pass the "floppy=nodma" option to the kernel
2295 5) pass the "mem=4M" option to the kernel (thereby disabling
2296 all but the first 4 MB of RAM)
2297 6) make sure that the CPU is not over clocked.
2298 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2299 8) disable the cache from your BIOS settings
2300 9) install a fan for the video card or exchange video RAM
2301 10) install a better fan for the CPU
2302 11) exchange RAM chips
2303 12) exchange the motherboard.
2305 To compile this driver as a module, choose M here: the
2306 module will be called apm.
2310 config APM_IGNORE_USER_SUSPEND
2311 bool "Ignore USER SUSPEND"
2313 This option will ignore USER SUSPEND requests. On machines with a
2314 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2315 series notebooks, it is necessary to say Y because of a BIOS bug.
2317 config APM_DO_ENABLE
2318 bool "Enable PM at boot time"
2320 Enable APM features at boot time. From page 36 of the APM BIOS
2321 specification: "When disabled, the APM BIOS does not automatically
2322 power manage devices, enter the Standby State, enter the Suspend
2323 State, or take power saving steps in response to CPU Idle calls."
2324 This driver will make CPU Idle calls when Linux is idle (unless this
2325 feature is turned off -- see "Do CPU IDLE calls", below). This
2326 should always save battery power, but more complicated APM features
2327 will be dependent on your BIOS implementation. You may need to turn
2328 this option off if your computer hangs at boot time when using APM
2329 support, or if it beeps continuously instead of suspending. Turn
2330 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2331 T400CDT. This is off by default since most machines do fine without
2336 bool "Make CPU Idle calls when idle"
2338 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2339 On some machines, this can activate improved power savings, such as
2340 a slowed CPU clock rate, when the machine is idle. These idle calls
2341 are made after the idle loop has run for some length of time (e.g.,
2342 333 mS). On some machines, this will cause a hang at boot time or
2343 whenever the CPU becomes idle. (On machines with more than one CPU,
2344 this option does nothing.)
2346 config APM_DISPLAY_BLANK
2347 bool "Enable console blanking using APM"
2349 Enable console blanking using the APM. Some laptops can use this to
2350 turn off the LCD backlight when the screen blanker of the Linux
2351 virtual console blanks the screen. Note that this is only used by
2352 the virtual console screen blanker, and won't turn off the backlight
2353 when using the X Window system. This also doesn't have anything to
2354 do with your VESA-compliant power-saving monitor. Further, this
2355 option doesn't work for all laptops -- it might not turn off your
2356 backlight at all, or it might print a lot of errors to the console,
2357 especially if you are using gpm.
2359 config APM_ALLOW_INTS
2360 bool "Allow interrupts during APM BIOS calls"
2362 Normally we disable external interrupts while we are making calls to
2363 the APM BIOS as a measure to lessen the effects of a badly behaving
2364 BIOS implementation. The BIOS should reenable interrupts if it
2365 needs to. Unfortunately, some BIOSes do not -- especially those in
2366 many of the newer IBM Thinkpads. If you experience hangs when you
2367 suspend, try setting this to Y. Otherwise, say N.
2371 source "drivers/cpufreq/Kconfig"
2373 source "drivers/cpuidle/Kconfig"
2375 source "drivers/idle/Kconfig"
2380 menu "Bus options (PCI etc.)"
2386 Find out whether you have a PCI motherboard. PCI is the name of a
2387 bus system, i.e. the way the CPU talks to the other stuff inside
2388 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2389 VESA. If you have PCI, say Y, otherwise N.
2392 prompt "PCI access mode"
2393 depends on X86_32 && PCI
2396 On PCI systems, the BIOS can be used to detect the PCI devices and
2397 determine their configuration. However, some old PCI motherboards
2398 have BIOS bugs and may crash if this is done. Also, some embedded
2399 PCI-based systems don't have any BIOS at all. Linux can also try to
2400 detect the PCI hardware directly without using the BIOS.
2402 With this option, you can specify how Linux should detect the
2403 PCI devices. If you choose "BIOS", the BIOS will be used,
2404 if you choose "Direct", the BIOS won't be used, and if you
2405 choose "MMConfig", then PCI Express MMCONFIG will be used.
2406 If you choose "Any", the kernel will try MMCONFIG, then the
2407 direct access method and falls back to the BIOS if that doesn't
2408 work. If unsure, go with the default, which is "Any".
2413 config PCI_GOMMCONFIG
2430 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2432 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2435 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2439 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2443 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2447 depends on PCI && XEN
2455 bool "Support mmconfig PCI config space access"
2456 depends on X86_64 && PCI && ACPI
2458 config PCI_CNB20LE_QUIRK
2459 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2462 Read the PCI windows out of the CNB20LE host bridge. This allows
2463 PCI hotplug to work on systems with the CNB20LE chipset which do
2466 There's no public spec for this chipset, and this functionality
2467 is known to be incomplete.
2469 You should say N unless you know you need this.
2471 source "drivers/pci/Kconfig"
2474 bool "ISA-style bus support on modern systems" if EXPERT
2477 Enables ISA-style drivers on modern systems. This is necessary to
2478 support PC/104 devices on X86_64 platforms.
2482 # x86_64 have no ISA slots, but can have ISA-style DMA.
2484 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2487 Enables ISA-style DMA support for devices requiring such controllers.
2495 Find out whether you have ISA slots on your motherboard. ISA is the
2496 name of a bus system, i.e. the way the CPU talks to the other stuff
2497 inside your box. Other bus systems are PCI, EISA, MicroChannel
2498 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2499 newer boards don't support it. If you have ISA, say Y, otherwise N.
2505 The Extended Industry Standard Architecture (EISA) bus was
2506 developed as an open alternative to the IBM MicroChannel bus.
2508 The EISA bus provided some of the features of the IBM MicroChannel
2509 bus while maintaining backward compatibility with cards made for
2510 the older ISA bus. The EISA bus saw limited use between 1988 and
2511 1995 when it was made obsolete by the PCI bus.
2513 Say Y here if you are building a kernel for an EISA-based machine.
2517 source "drivers/eisa/Kconfig"
2520 tristate "NatSemi SCx200 support"
2522 This provides basic support for National Semiconductor's
2523 (now AMD's) Geode processors. The driver probes for the
2524 PCI-IDs of several on-chip devices, so its a good dependency
2525 for other scx200_* drivers.
2527 If compiled as a module, the driver is named scx200.
2529 config SCx200HR_TIMER
2530 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2534 This driver provides a clocksource built upon the on-chip
2535 27MHz high-resolution timer. Its also a workaround for
2536 NSC Geode SC-1100's buggy TSC, which loses time when the
2537 processor goes idle (as is done by the scheduler). The
2538 other workaround is idle=poll boot option.
2541 bool "One Laptop Per Child support"
2548 Add support for detecting the unique features of the OLPC
2552 bool "OLPC XO-1 Power Management"
2553 depends on OLPC && MFD_CS5535 && PM_SLEEP
2556 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2559 bool "OLPC XO-1 Real Time Clock"
2560 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2562 Add support for the XO-1 real time clock, which can be used as a
2563 programmable wakeup source.
2566 bool "OLPC XO-1 SCI extras"
2567 depends on OLPC && OLPC_XO1_PM
2573 Add support for SCI-based features of the OLPC XO-1 laptop:
2574 - EC-driven system wakeups
2578 - AC adapter status updates
2579 - Battery status updates
2581 config OLPC_XO15_SCI
2582 bool "OLPC XO-1.5 SCI extras"
2583 depends on OLPC && ACPI
2586 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2587 - EC-driven system wakeups
2588 - AC adapter status updates
2589 - Battery status updates
2592 bool "PCEngines ALIX System Support (LED setup)"
2595 This option enables system support for the PCEngines ALIX.
2596 At present this just sets up LEDs for GPIO control on
2597 ALIX2/3/6 boards. However, other system specific setup should
2600 Note: You must still enable the drivers for GPIO and LED support
2601 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2603 Note: You have to set alix.force=1 for boards with Award BIOS.
2606 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2609 This option enables system support for the Soekris Engineering net5501.
2612 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2616 This option enables system support for the Traverse Technologies GEOS.
2619 bool "Technologic Systems TS-5500 platform support"
2621 select CHECK_SIGNATURE
2625 This option enables system support for the Technologic Systems TS-5500.
2631 depends on CPU_SUP_AMD && PCI
2633 source "drivers/pcmcia/Kconfig"
2636 tristate "RapidIO support"
2640 If enabled this option will include drivers and the core
2641 infrastructure code to support RapidIO interconnect devices.
2643 source "drivers/rapidio/Kconfig"
2646 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2648 Firmwares often provide initial graphics framebuffers so the BIOS,
2649 bootloader or kernel can show basic video-output during boot for
2650 user-guidance and debugging. Historically, x86 used the VESA BIOS
2651 Extensions and EFI-framebuffers for this, which are mostly limited
2653 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2654 framebuffers so the new generic system-framebuffer drivers can be
2655 used on x86. If the framebuffer is not compatible with the generic
2656 modes, it is adverticed as fallback platform framebuffer so legacy
2657 drivers like efifb, vesafb and uvesafb can pick it up.
2658 If this option is not selected, all system framebuffers are always
2659 marked as fallback platform framebuffers as usual.
2661 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2662 not be able to pick up generic system framebuffers if this option
2663 is selected. You are highly encouraged to enable simplefb as
2664 replacement if you select this option. simplefb can correctly deal
2665 with generic system framebuffers. But you should still keep vesafb
2666 and others enabled as fallback if a system framebuffer is
2667 incompatible with simplefb.
2674 menu "Executable file formats / Emulations"
2676 source "fs/Kconfig.binfmt"
2678 config IA32_EMULATION
2679 bool "IA32 Emulation"
2682 select COMPAT_BINFMT_ELF
2683 select ARCH_WANT_OLD_COMPAT_IPC
2685 Include code to run legacy 32-bit programs under a
2686 64-bit kernel. You should likely turn this on, unless you're
2687 100% sure that you don't have any 32-bit programs left.
2690 tristate "IA32 a.out support"
2691 depends on IA32_EMULATION
2693 Support old a.out binaries in the 32bit emulation.
2696 bool "x32 ABI for 64-bit mode"
2699 Include code to run binaries for the x32 native 32-bit ABI
2700 for 64-bit processors. An x32 process gets access to the
2701 full 64-bit register file and wide data path while leaving
2702 pointers at 32 bits for smaller memory footprint.
2704 You will need a recent binutils (2.22 or later) with
2705 elf32_x86_64 support enabled to compile a kernel with this
2710 depends on IA32_EMULATION || X86_X32
2713 config COMPAT_FOR_U64_ALIGNMENT
2716 config SYSVIPC_COMPAT
2728 config HAVE_ATOMIC_IOMAP
2732 config X86_DEV_DMA_OPS
2734 depends on X86_64 || STA2X11
2736 config X86_DMA_REMAP
2746 tristate "Volume Management Device Driver"
2749 Adds support for the Intel Volume Management Device (VMD). VMD is a
2750 secondary PCI host bridge that allows PCI Express root ports,
2751 and devices attached to them, to be removed from the default
2752 PCI domain and placed within the VMD domain. This provides
2753 more bus resources than are otherwise possible with a
2754 single domain. If you know your system provides one of these and
2755 has devices attached to it, say Y; if you are not sure, say N.
2757 source "net/Kconfig"
2759 source "drivers/Kconfig"
2761 source "drivers/firmware/Kconfig"
2765 source "arch/x86/Kconfig.debug"
2767 source "security/Kconfig"
2769 source "crypto/Kconfig"
2771 source "arch/x86/kvm/Kconfig"
2773 source "lib/Kconfig"
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