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 HAVE_PREEMPT_LAZY
21 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
22 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
24 select ARCH_CLOCKSOURCE_DATA
25 select ARCH_DISCARD_MEMBLOCK
26 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
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_GIGANTIC_PAGE if X86_64
32 select ARCH_HAS_KCOV if X86_64
33 select ARCH_HAS_PMEM_API if X86_64
34 select ARCH_HAS_MMIO_FLUSH
35 select ARCH_HAS_SG_CHAIN
36 select ARCH_HAS_UBSAN_SANITIZE_ALL
37 select ARCH_HAVE_NMI_SAFE_CMPXCHG
38 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
39 select ARCH_MIGHT_HAVE_PC_PARPORT
40 select ARCH_MIGHT_HAVE_PC_SERIO
41 select ARCH_SUPPORTS_ATOMIC_RMW
42 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
43 select ARCH_SUPPORTS_INT128 if X86_64
44 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
45 select ARCH_USE_BUILTIN_BSWAP
46 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
47 select ARCH_USE_QUEUED_RWLOCKS
48 select ARCH_USE_QUEUED_SPINLOCKS
49 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
50 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
51 select ARCH_WANT_FRAME_POINTERS
52 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
53 select BUILDTIME_EXTABLE_SORT
55 select CLKSRC_I8253 if X86_32
56 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
57 select CLOCKSOURCE_WATCHDOG
58 select CLONE_BACKWARDS if X86_32
59 select COMPAT_OLD_SIGACTION if IA32_EMULATION
60 select DCACHE_WORD_ACCESS
61 select EDAC_ATOMIC_SCRUB
63 select GENERIC_CLOCKEVENTS
64 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
65 select GENERIC_CLOCKEVENTS_MIN_ADJUST
66 select GENERIC_CMOS_UPDATE
67 select GENERIC_CPU_AUTOPROBE
68 select GENERIC_EARLY_IOREMAP
69 select GENERIC_FIND_FIRST_BIT
71 select GENERIC_IRQ_PROBE
72 select GENERIC_IRQ_SHOW
73 select GENERIC_PENDING_IRQ if SMP
74 select GENERIC_SMP_IDLE_THREAD
75 select GENERIC_STRNCPY_FROM_USER
76 select GENERIC_STRNLEN_USER
77 select GENERIC_TIME_VSYSCALL
78 select HAVE_ACPI_APEI if ACPI
79 select HAVE_ACPI_APEI_NMI if ACPI
80 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
81 select HAVE_AOUT if X86_32
82 select HAVE_ARCH_AUDITSYSCALL
83 select HAVE_ARCH_HARDENED_USERCOPY
84 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
85 select HAVE_ARCH_JUMP_LABEL
86 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
88 select HAVE_ARCH_KMEMCHECK
89 select HAVE_ARCH_MMAP_RND_BITS if MMU
90 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
91 select HAVE_ARCH_SECCOMP_FILTER
92 select HAVE_ARCH_SOFT_DIRTY if X86_64
93 select HAVE_ARCH_TRACEHOOK
94 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
95 select HAVE_ARCH_WITHIN_STACK_FRAMES
96 select HAVE_EBPF_JIT if X86_64
97 select HAVE_ARCH_VMAP_STACK if X86_64
98 select HAVE_CC_STACKPROTECTOR
99 select HAVE_CMPXCHG_DOUBLE
100 select HAVE_CMPXCHG_LOCAL
101 select HAVE_CONTEXT_TRACKING if X86_64
102 select HAVE_COPY_THREAD_TLS
103 select HAVE_C_RECORDMCOUNT
104 select HAVE_DEBUG_KMEMLEAK
105 select HAVE_DEBUG_STACKOVERFLOW
106 select HAVE_DMA_API_DEBUG
107 select HAVE_DMA_CONTIGUOUS
108 select HAVE_DYNAMIC_FTRACE
109 select HAVE_DYNAMIC_FTRACE_WITH_REGS
110 select HAVE_EFFICIENT_UNALIGNED_ACCESS
111 select HAVE_EXIT_THREAD
112 select HAVE_FENTRY if X86_64
113 select HAVE_FTRACE_MCOUNT_RECORD
114 select HAVE_FUNCTION_GRAPH_TRACER
115 select HAVE_FUNCTION_TRACER
116 select HAVE_GCC_PLUGINS
117 select HAVE_GENERIC_DMA_COHERENT if X86_32
118 select HAVE_HW_BREAKPOINT
120 select HAVE_IOREMAP_PROT
121 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
122 select HAVE_IRQ_TIME_ACCOUNTING
123 select HAVE_KERNEL_BZIP2
124 select HAVE_KERNEL_GZIP
125 select HAVE_KERNEL_LZ4
126 select HAVE_KERNEL_LZMA
127 select HAVE_KERNEL_LZO
128 select HAVE_KERNEL_XZ
130 select HAVE_KPROBES_ON_FTRACE
131 select HAVE_KRETPROBES
133 select HAVE_LIVEPATCH if X86_64
135 select HAVE_MEMBLOCK_NODE_MAP
136 select HAVE_MIXED_BREAKPOINTS_REGS
139 select HAVE_OPTPROBES
140 select HAVE_PCSPKR_PLATFORM
141 select HAVE_PERF_EVENTS
142 select HAVE_PERF_EVENTS_NMI
143 select HAVE_PERF_REGS
144 select HAVE_PERF_USER_STACK_DUMP
145 select HAVE_REGS_AND_STACK_ACCESS_API
146 select HAVE_SYSCALL_TRACEPOINTS
147 select HAVE_UID16 if X86_32 || IA32_EMULATION
148 select HAVE_UNSTABLE_SCHED_CLOCK
149 select HAVE_USER_RETURN_NOTIFIER
150 select IRQ_FORCED_THREADING
151 select MODULES_USE_ELF_RELA if X86_64
152 select MODULES_USE_ELF_REL if X86_32
153 select OLD_SIGACTION if X86_32
154 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
157 select RTC_MC146818_LIB
160 select SYSCTL_EXCEPTION_TRACE
161 select THREAD_INFO_IN_TASK
162 select USER_STACKTRACE_SUPPORT
164 select X86_DEV_DMA_OPS if X86_64
165 select X86_FEATURE_NAMES if PROC_FS
166 select HAVE_STACK_VALIDATION if X86_64
167 select ARCH_USES_HIGH_VMA_FLAGS if X86_INTEL_MEMORY_PROTECTION_KEYS
168 select ARCH_HAS_PKEYS if X86_INTEL_MEMORY_PROTECTION_KEYS
170 config INSTRUCTION_DECODER
172 depends on KPROBES || PERF_EVENTS || UPROBES
176 default "elf32-i386" if X86_32
177 default "elf64-x86-64" if X86_64
179 config ARCH_DEFCONFIG
181 default "arch/x86/configs/i386_defconfig" if X86_32
182 default "arch/x86/configs/x86_64_defconfig" if X86_64
184 config LOCKDEP_SUPPORT
187 config STACKTRACE_SUPPORT
193 config ARCH_MMAP_RND_BITS_MIN
197 config ARCH_MMAP_RND_BITS_MAX
201 config ARCH_MMAP_RND_COMPAT_BITS_MIN
204 config ARCH_MMAP_RND_COMPAT_BITS_MAX
210 config NEED_DMA_MAP_STATE
212 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
214 config NEED_SG_DMA_LENGTH
217 config GENERIC_ISA_DMA
219 depends on ISA_DMA_API
224 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
226 config GENERIC_BUG_RELATIVE_POINTERS
229 config GENERIC_HWEIGHT
232 config ARCH_MAY_HAVE_PC_FDC
234 depends on ISA_DMA_API
236 config RWSEM_GENERIC_SPINLOCK
237 def_bool PREEMPT_RT_FULL
239 config RWSEM_XCHGADD_ALGORITHM
240 def_bool !RWSEM_GENERIC_SPINLOCK && !PREEMPT_RT_FULL
242 config GENERIC_CALIBRATE_DELAY
245 config ARCH_HAS_CPU_RELAX
248 config ARCH_HAS_CACHE_LINE_SIZE
251 config HAVE_SETUP_PER_CPU_AREA
254 config NEED_PER_CPU_EMBED_FIRST_CHUNK
257 config NEED_PER_CPU_PAGE_FIRST_CHUNK
260 config ARCH_HIBERNATION_POSSIBLE
263 config ARCH_SUSPEND_POSSIBLE
266 config ARCH_WANT_HUGE_PMD_SHARE
269 config ARCH_WANT_GENERAL_HUGETLB
278 config ARCH_SUPPORTS_OPTIMIZED_INLINING
281 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
284 config KASAN_SHADOW_OFFSET
287 default 0xdffffc0000000000
289 config HAVE_INTEL_TXT
291 depends on INTEL_IOMMU && ACPI
295 depends on X86_32 && SMP
299 depends on X86_64 && SMP
301 config X86_32_LAZY_GS
303 depends on X86_32 && !CC_STACKPROTECTOR
305 config ARCH_SUPPORTS_UPROBES
308 config FIX_EARLYCON_MEM
314 config PGTABLE_LEVELS
320 source "init/Kconfig"
321 source "kernel/Kconfig.freezer"
323 menu "Processor type and features"
326 bool "DMA memory allocation support" if EXPERT
329 DMA memory allocation support allows devices with less than 32-bit
330 addressing to allocate within the first 16MB of address space.
331 Disable if no such devices will be used.
336 bool "Symmetric multi-processing support"
338 This enables support for systems with more than one CPU. If you have
339 a system with only one CPU, say N. If you have a system with more
342 If you say N here, the kernel will run on uni- and multiprocessor
343 machines, but will use only one CPU of a multiprocessor machine. If
344 you say Y here, the kernel will run on many, but not all,
345 uniprocessor machines. On a uniprocessor machine, the kernel
346 will run faster if you say N here.
348 Note that if you say Y here and choose architecture "586" or
349 "Pentium" under "Processor family", the kernel will not work on 486
350 architectures. Similarly, multiprocessor kernels for the "PPro"
351 architecture may not work on all Pentium based boards.
353 People using multiprocessor machines who say Y here should also say
354 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
355 Management" code will be disabled if you say Y here.
357 See also <file:Documentation/x86/i386/IO-APIC.txt>,
358 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
359 <http://www.tldp.org/docs.html#howto>.
361 If you don't know what to do here, say N.
363 config X86_FEATURE_NAMES
364 bool "Processor feature human-readable names" if EMBEDDED
367 This option compiles in a table of x86 feature bits and corresponding
368 names. This is required to support /proc/cpuinfo and a few kernel
369 messages. You can disable this to save space, at the expense of
370 making those few kernel messages show numeric feature bits instead.
374 config X86_FAST_FEATURE_TESTS
375 bool "Fast CPU feature tests" if EMBEDDED
378 Some fast-paths in the kernel depend on the capabilities of the CPU.
379 Say Y here for the kernel to patch in the appropriate code at runtime
380 based on the capabilities of the CPU. The infrastructure for patching
381 code at runtime takes up some additional space; space-constrained
382 embedded systems may wish to say N here to produce smaller, slightly
386 bool "Support x2apic"
387 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
389 This enables x2apic support on CPUs that have this feature.
391 This allows 32-bit apic IDs (so it can support very large systems),
392 and accesses the local apic via MSRs not via mmio.
394 If you don't know what to do here, say N.
397 bool "Enable MPS table" if ACPI || SFI
399 depends on X86_LOCAL_APIC
401 For old smp systems that do not have proper acpi support. Newer systems
402 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
405 bool "Support for big SMP systems with more than 8 CPUs"
406 depends on X86_32 && SMP
408 This option is needed for the systems that have more than 8 CPUs
412 depends on X86_GOLDFISH
415 config X86_EXTENDED_PLATFORM
416 bool "Support for extended (non-PC) x86 platforms"
419 If you disable this option then the kernel will only support
420 standard PC platforms. (which covers the vast majority of
423 If you enable this option then you'll be able to select support
424 for the following (non-PC) 32 bit x86 platforms:
425 Goldfish (Android emulator)
428 SGI 320/540 (Visual Workstation)
429 STA2X11-based (e.g. Northville)
430 Moorestown MID devices
432 If you have one of these systems, or if you want to build a
433 generic distribution kernel, say Y here - otherwise say N.
437 config X86_EXTENDED_PLATFORM
438 bool "Support for extended (non-PC) x86 platforms"
441 If you disable this option then the kernel will only support
442 standard PC platforms. (which covers the vast majority of
445 If you enable this option then you'll be able to select support
446 for the following (non-PC) 64 bit x86 platforms:
451 If you have one of these systems, or if you want to build a
452 generic distribution kernel, say Y here - otherwise say N.
454 # This is an alphabetically sorted list of 64 bit extended platforms
455 # Please maintain the alphabetic order if and when there are additions
457 bool "Numascale NumaChip"
459 depends on X86_EXTENDED_PLATFORM
462 depends on X86_X2APIC
463 depends on PCI_MMCONFIG
465 Adds support for Numascale NumaChip large-SMP systems. Needed to
466 enable more than ~168 cores.
467 If you don't have one of these, you should say N here.
471 select HYPERVISOR_GUEST
473 depends on X86_64 && PCI
474 depends on X86_EXTENDED_PLATFORM
477 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
478 supposed to run on these EM64T-based machines. Only choose this option
479 if you have one of these machines.
482 bool "SGI Ultraviolet"
484 depends on X86_EXTENDED_PLATFORM
487 depends on X86_X2APIC
490 This option is needed in order to support SGI Ultraviolet systems.
491 If you don't have one of these, you should say N here.
493 # Following is an alphabetically sorted list of 32 bit extended platforms
494 # Please maintain the alphabetic order if and when there are additions
497 bool "Goldfish (Virtual Platform)"
498 depends on X86_EXTENDED_PLATFORM
500 Enable support for the Goldfish virtual platform used primarily
501 for Android development. Unless you are building for the Android
502 Goldfish emulator say N here.
505 bool "CE4100 TV platform"
507 depends on PCI_GODIRECT
508 depends on X86_IO_APIC
510 depends on X86_EXTENDED_PLATFORM
511 select X86_REBOOTFIXUPS
513 select OF_EARLY_FLATTREE
515 Select for the Intel CE media processor (CE4100) SOC.
516 This option compiles in support for the CE4100 SOC for settop
517 boxes and media devices.
520 bool "Intel MID platform support"
521 depends on X86_EXTENDED_PLATFORM
522 depends on X86_PLATFORM_DEVICES
524 depends on X86_64 || (PCI_GOANY && X86_32)
525 depends on X86_IO_APIC
531 select MFD_INTEL_MSIC
533 Select to build a kernel capable of supporting Intel MID (Mobile
534 Internet Device) platform systems which do not have the PCI legacy
535 interfaces. If you are building for a PC class system say N here.
537 Intel MID platforms are based on an Intel processor and chipset which
538 consume less power than most of the x86 derivatives.
540 config X86_INTEL_QUARK
541 bool "Intel Quark platform support"
543 depends on X86_EXTENDED_PLATFORM
544 depends on X86_PLATFORM_DEVICES
548 depends on X86_IO_APIC
553 Select to include support for Quark X1000 SoC.
554 Say Y here if you have a Quark based system such as the Arduino
555 compatible Intel Galileo.
558 tristate "Mellanox Technologies platform support"
560 depends on X86_EXTENDED_PLATFORM
562 This option enables system support for the Mellanox Technologies
565 Say Y here if you are building a kernel for Mellanox system.
569 config X86_INTEL_LPSS
570 bool "Intel Low Power Subsystem Support"
571 depends on X86 && ACPI
576 Select to build support for Intel Low Power Subsystem such as
577 found on Intel Lynxpoint PCH. Selecting this option enables
578 things like clock tree (common clock framework) and pincontrol
579 which are needed by the LPSS peripheral drivers.
581 config X86_AMD_PLATFORM_DEVICE
582 bool "AMD ACPI2Platform devices support"
587 Select to interpret AMD specific ACPI device to platform device
588 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
589 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
590 implemented under PINCTRL subsystem.
593 tristate "Intel SoC IOSF Sideband support for SoC platforms"
596 This option enables sideband register access support for Intel SoC
597 platforms. On these platforms the IOSF sideband is used in lieu of
598 MSR's for some register accesses, mostly but not limited to thermal
599 and power. Drivers may query the availability of this device to
600 determine if they need the sideband in order to work on these
601 platforms. The sideband is available on the following SoC products.
602 This list is not meant to be exclusive.
607 You should say Y if you are running a kernel on one of these SoC's.
609 config IOSF_MBI_DEBUG
610 bool "Enable IOSF sideband access through debugfs"
611 depends on IOSF_MBI && DEBUG_FS
613 Select this option to expose the IOSF sideband access registers (MCR,
614 MDR, MCRX) through debugfs to write and read register information from
615 different units on the SoC. This is most useful for obtaining device
616 state information for debug and analysis. As this is a general access
617 mechanism, users of this option would have specific knowledge of the
618 device they want to access.
620 If you don't require the option or are in doubt, say N.
623 bool "RDC R-321x SoC"
625 depends on X86_EXTENDED_PLATFORM
627 select X86_REBOOTFIXUPS
629 This option is needed for RDC R-321x system-on-chip, also known
631 If you don't have one of these chips, you should say N here.
633 config X86_32_NON_STANDARD
634 bool "Support non-standard 32-bit SMP architectures"
635 depends on X86_32 && SMP
636 depends on X86_EXTENDED_PLATFORM
638 This option compiles in the bigsmp and STA2X11 default
639 subarchitectures. It is intended for a generic binary
640 kernel. If you select them all, kernel will probe it one by
641 one and will fallback to default.
643 # Alphabetically sorted list of Non standard 32 bit platforms
645 config X86_SUPPORTS_MEMORY_FAILURE
647 # MCE code calls memory_failure():
649 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
650 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
651 depends on X86_64 || !SPARSEMEM
652 select ARCH_SUPPORTS_MEMORY_FAILURE
655 bool "STA2X11 Companion Chip Support"
656 depends on X86_32_NON_STANDARD && PCI
657 select X86_DEV_DMA_OPS
664 This adds support for boards based on the STA2X11 IO-Hub,
665 a.k.a. "ConneXt". The chip is used in place of the standard
666 PC chipset, so all "standard" peripherals are missing. If this
667 option is selected the kernel will still be able to boot on
668 standard PC machines.
671 tristate "Eurobraille/Iris poweroff module"
674 The Iris machines from EuroBraille do not have APM or ACPI support
675 to shut themselves down properly. A special I/O sequence is
676 needed to do so, which is what this module does at
679 This is only for Iris machines from EuroBraille.
683 config SCHED_OMIT_FRAME_POINTER
685 prompt "Single-depth WCHAN output"
688 Calculate simpler /proc/<PID>/wchan values. If this option
689 is disabled then wchan values will recurse back to the
690 caller function. This provides more accurate wchan values,
691 at the expense of slightly more scheduling overhead.
693 If in doubt, say "Y".
695 menuconfig HYPERVISOR_GUEST
696 bool "Linux guest support"
698 Say Y here to enable options for running Linux under various hyper-
699 visors. This option enables basic hypervisor detection and platform
702 If you say N, all options in this submenu will be skipped and
703 disabled, and Linux guest support won't be built in.
708 bool "Enable paravirtualization code"
710 This changes the kernel so it can modify itself when it is run
711 under a hypervisor, potentially improving performance significantly
712 over full virtualization. However, when run without a hypervisor
713 the kernel is theoretically slower and slightly larger.
715 config PARAVIRT_DEBUG
716 bool "paravirt-ops debugging"
717 depends on PARAVIRT && DEBUG_KERNEL
719 Enable to debug paravirt_ops internals. Specifically, BUG if
720 a paravirt_op is missing when it is called.
722 config PARAVIRT_SPINLOCKS
723 bool "Paravirtualization layer for spinlocks"
724 depends on PARAVIRT && SMP
726 Paravirtualized spinlocks allow a pvops backend to replace the
727 spinlock implementation with something virtualization-friendly
728 (for example, block the virtual CPU rather than spinning).
730 It has a minimal impact on native kernels and gives a nice performance
731 benefit on paravirtualized KVM / Xen kernels.
733 If you are unsure how to answer this question, answer Y.
735 config QUEUED_LOCK_STAT
736 bool "Paravirt queued spinlock statistics"
737 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
739 Enable the collection of statistical data on the slowpath
740 behavior of paravirtualized queued spinlocks and report
743 source "arch/x86/xen/Kconfig"
746 bool "KVM Guest support (including kvmclock)"
748 select PARAVIRT_CLOCK
751 This option enables various optimizations for running under the KVM
752 hypervisor. It includes a paravirtualized clock, so that instead
753 of relying on a PIT (or probably other) emulation by the
754 underlying device model, the host provides the guest with
755 timing infrastructure such as time of day, and system time
758 bool "Enable debug information for KVM Guests in debugfs"
759 depends on KVM_GUEST && DEBUG_FS
762 This option enables collection of various statistics for KVM guest.
763 Statistics are displayed in debugfs filesystem. Enabling this option
764 may incur significant overhead.
766 source "arch/x86/lguest/Kconfig"
768 config PARAVIRT_TIME_ACCOUNTING
769 bool "Paravirtual steal time accounting"
773 Select this option to enable fine granularity task steal time
774 accounting. Time spent executing other tasks in parallel with
775 the current vCPU is discounted from the vCPU power. To account for
776 that, there can be a small performance impact.
778 If in doubt, say N here.
780 config PARAVIRT_CLOCK
783 endif #HYPERVISOR_GUEST
788 source "arch/x86/Kconfig.cpu"
792 prompt "HPET Timer Support" if X86_32
794 Use the IA-PC HPET (High Precision Event Timer) to manage
795 time in preference to the PIT and RTC, if a HPET is
797 HPET is the next generation timer replacing legacy 8254s.
798 The HPET provides a stable time base on SMP
799 systems, unlike the TSC, but it is more expensive to access,
800 as it is off-chip. The interface used is documented
801 in the HPET spec, revision 1.
803 You can safely choose Y here. However, HPET will only be
804 activated if the platform and the BIOS support this feature.
805 Otherwise the 8254 will be used for timing services.
807 Choose N to continue using the legacy 8254 timer.
809 config HPET_EMULATE_RTC
811 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
814 def_bool y if X86_INTEL_MID
815 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
817 depends on X86_INTEL_MID && SFI
819 APB timer is the replacement for 8254, HPET on X86 MID platforms.
820 The APBT provides a stable time base on SMP
821 systems, unlike the TSC, but it is more expensive to access,
822 as it is off-chip. APB timers are always running regardless of CPU
823 C states, they are used as per CPU clockevent device when possible.
825 # Mark as expert because too many people got it wrong.
826 # The code disables itself when not needed.
829 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
830 bool "Enable DMI scanning" if EXPERT
832 Enabled scanning of DMI to identify machine quirks. Say Y
833 here unless you have verified that your setup is not
834 affected by entries in the DMI blacklist. Required by PNP
838 bool "Old AMD GART IOMMU support"
840 depends on X86_64 && PCI && AMD_NB
842 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
843 GART based hardware IOMMUs.
845 The GART supports full DMA access for devices with 32-bit access
846 limitations, on systems with more than 3 GB. This is usually needed
847 for USB, sound, many IDE/SATA chipsets and some other devices.
849 Newer systems typically have a modern AMD IOMMU, supported via
850 the CONFIG_AMD_IOMMU=y config option.
852 In normal configurations this driver is only active when needed:
853 there's more than 3 GB of memory and the system contains a
854 32-bit limited device.
859 bool "IBM Calgary IOMMU support"
861 depends on X86_64 && PCI
863 Support for hardware IOMMUs in IBM's xSeries x366 and x460
864 systems. Needed to run systems with more than 3GB of memory
865 properly with 32-bit PCI devices that do not support DAC
866 (Double Address Cycle). Calgary also supports bus level
867 isolation, where all DMAs pass through the IOMMU. This
868 prevents them from going anywhere except their intended
869 destination. This catches hard-to-find kernel bugs and
870 mis-behaving drivers and devices that do not use the DMA-API
871 properly to set up their DMA buffers. The IOMMU can be
872 turned off at boot time with the iommu=off parameter.
873 Normally the kernel will make the right choice by itself.
876 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
878 prompt "Should Calgary be enabled by default?"
879 depends on CALGARY_IOMMU
881 Should Calgary be enabled by default? if you choose 'y', Calgary
882 will be used (if it exists). If you choose 'n', Calgary will not be
883 used even if it exists. If you choose 'n' and would like to use
884 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
887 # need this always selected by IOMMU for the VIA workaround
891 Support for software bounce buffers used on x86-64 systems
892 which don't have a hardware IOMMU. Using this PCI devices
893 which can only access 32-bits of memory can be used on systems
894 with more than 3 GB of memory.
899 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
902 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
903 depends on X86_64 && SMP && DEBUG_KERNEL
904 select CPUMASK_OFFSTACK if !PREEMPT_RT_FULL
906 Enable maximum number of CPUS and NUMA Nodes for this architecture.
910 int "Maximum number of CPUs" if SMP && !MAXSMP
911 range 2 8 if SMP && X86_32 && !X86_BIGSMP
912 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
913 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
915 default "8192" if MAXSMP
916 default "32" if SMP && X86_BIGSMP
917 default "8" if SMP && X86_32
920 This allows you to specify the maximum number of CPUs which this
921 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
922 supported value is 8192, otherwise the maximum value is 512. The
923 minimum value which makes sense is 2.
925 This is purely to save memory - each supported CPU adds
926 approximately eight kilobytes to the kernel image.
929 bool "SMT (Hyperthreading) scheduler support"
932 SMT scheduler support improves the CPU scheduler's decision making
933 when dealing with Intel Pentium 4 chips with HyperThreading at a
934 cost of slightly increased overhead in some places. If unsure say
939 prompt "Multi-core scheduler support"
942 Multi-core scheduler support improves the CPU scheduler's decision
943 making when dealing with multi-core CPU chips at a cost of slightly
944 increased overhead in some places. If unsure say N here.
946 source "kernel/Kconfig.preempt"
950 depends on !SMP && X86_LOCAL_APIC
953 bool "Local APIC support on uniprocessors" if !PCI_MSI
955 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
957 A local APIC (Advanced Programmable Interrupt Controller) is an
958 integrated interrupt controller in the CPU. If you have a single-CPU
959 system which has a processor with a local APIC, you can say Y here to
960 enable and use it. If you say Y here even though your machine doesn't
961 have a local APIC, then the kernel will still run with no slowdown at
962 all. The local APIC supports CPU-generated self-interrupts (timer,
963 performance counters), and the NMI watchdog which detects hard
967 bool "IO-APIC support on uniprocessors"
968 depends on X86_UP_APIC
970 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
971 SMP-capable replacement for PC-style interrupt controllers. Most
972 SMP systems and many recent uniprocessor systems have one.
974 If you have a single-CPU system with an IO-APIC, you can say Y here
975 to use it. If you say Y here even though your machine doesn't have
976 an IO-APIC, then the kernel will still run with no slowdown at all.
978 config X86_LOCAL_APIC
980 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
981 select IRQ_DOMAIN_HIERARCHY
982 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
986 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
988 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
989 bool "Reroute for broken boot IRQs"
990 depends on X86_IO_APIC
992 This option enables a workaround that fixes a source of
993 spurious interrupts. This is recommended when threaded
994 interrupt handling is used on systems where the generation of
995 superfluous "boot interrupts" cannot be disabled.
997 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
998 entry in the chipset's IO-APIC is masked (as, e.g. the RT
999 kernel does during interrupt handling). On chipsets where this
1000 boot IRQ generation cannot be disabled, this workaround keeps
1001 the original IRQ line masked so that only the equivalent "boot
1002 IRQ" is delivered to the CPUs. The workaround also tells the
1003 kernel to set up the IRQ handler on the boot IRQ line. In this
1004 way only one interrupt is delivered to the kernel. Otherwise
1005 the spurious second interrupt may cause the kernel to bring
1006 down (vital) interrupt lines.
1008 Only affects "broken" chipsets. Interrupt sharing may be
1009 increased on these systems.
1012 bool "Machine Check / overheating reporting"
1013 select GENERIC_ALLOCATOR
1016 Machine Check support allows the processor to notify the
1017 kernel if it detects a problem (e.g. overheating, data corruption).
1018 The action the kernel takes depends on the severity of the problem,
1019 ranging from warning messages to halting the machine.
1021 config X86_MCE_INTEL
1023 prompt "Intel MCE features"
1024 depends on X86_MCE && X86_LOCAL_APIC
1026 Additional support for intel specific MCE features such as
1027 the thermal monitor.
1031 prompt "AMD MCE features"
1032 depends on X86_MCE && X86_LOCAL_APIC
1034 Additional support for AMD specific MCE features such as
1035 the DRAM Error Threshold.
1037 config X86_ANCIENT_MCE
1038 bool "Support for old Pentium 5 / WinChip machine checks"
1039 depends on X86_32 && X86_MCE
1041 Include support for machine check handling on old Pentium 5 or WinChip
1042 systems. These typically need to be enabled explicitly on the command
1045 config X86_MCE_THRESHOLD
1046 depends on X86_MCE_AMD || X86_MCE_INTEL
1049 config X86_MCE_INJECT
1051 tristate "Machine check injector support"
1053 Provide support for injecting machine checks for testing purposes.
1054 If you don't know what a machine check is and you don't do kernel
1055 QA it is safe to say n.
1057 config X86_THERMAL_VECTOR
1059 depends on X86_MCE_INTEL
1061 source "arch/x86/events/Kconfig"
1063 config X86_LEGACY_VM86
1064 bool "Legacy VM86 support"
1068 This option allows user programs to put the CPU into V8086
1069 mode, which is an 80286-era approximation of 16-bit real mode.
1071 Some very old versions of X and/or vbetool require this option
1072 for user mode setting. Similarly, DOSEMU will use it if
1073 available to accelerate real mode DOS programs. However, any
1074 recent version of DOSEMU, X, or vbetool should be fully
1075 functional even without kernel VM86 support, as they will all
1076 fall back to software emulation. Nevertheless, if you are using
1077 a 16-bit DOS program where 16-bit performance matters, vm86
1078 mode might be faster than emulation and you might want to
1081 Note that any app that works on a 64-bit kernel is unlikely to
1082 need this option, as 64-bit kernels don't, and can't, support
1083 V8086 mode. This option is also unrelated to 16-bit protected
1084 mode and is not needed to run most 16-bit programs under Wine.
1086 Enabling this option increases the complexity of the kernel
1087 and slows down exception handling a tiny bit.
1089 If unsure, say N here.
1093 default X86_LEGACY_VM86
1096 bool "Enable support for 16-bit segments" if EXPERT
1098 depends on MODIFY_LDT_SYSCALL
1100 This option is required by programs like Wine to run 16-bit
1101 protected mode legacy code on x86 processors. Disabling
1102 this option saves about 300 bytes on i386, or around 6K text
1103 plus 16K runtime memory on x86-64,
1107 depends on X86_16BIT && X86_32
1111 depends on X86_16BIT && X86_64
1113 config X86_VSYSCALL_EMULATION
1114 bool "Enable vsyscall emulation" if EXPERT
1118 This enables emulation of the legacy vsyscall page. Disabling
1119 it is roughly equivalent to booting with vsyscall=none, except
1120 that it will also disable the helpful warning if a program
1121 tries to use a vsyscall. With this option set to N, offending
1122 programs will just segfault, citing addresses of the form
1125 This option is required by many programs built before 2013, and
1126 care should be used even with newer programs if set to N.
1128 Disabling this option saves about 7K of kernel size and
1129 possibly 4K of additional runtime pagetable memory.
1132 tristate "Toshiba Laptop support"
1135 This adds a driver to safely access the System Management Mode of
1136 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1137 not work on models with a Phoenix BIOS. The System Management Mode
1138 is used to set the BIOS and power saving options on Toshiba portables.
1140 For information on utilities to make use of this driver see the
1141 Toshiba Linux utilities web site at:
1142 <http://www.buzzard.org.uk/toshiba/>.
1144 Say Y if you intend to run this kernel on a Toshiba portable.
1148 tristate "Dell i8k legacy laptop support"
1150 select SENSORS_DELL_SMM
1152 This option enables legacy /proc/i8k userspace interface in hwmon
1153 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1154 temperature and allows controlling fan speeds of Dell laptops via
1155 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1156 it reports also power and hotkey status. For fan speed control is
1157 needed userspace package i8kutils.
1159 Say Y if you intend to run this kernel on old Dell laptops or want to
1160 use userspace package i8kutils.
1163 config X86_REBOOTFIXUPS
1164 bool "Enable X86 board specific fixups for reboot"
1167 This enables chipset and/or board specific fixups to be done
1168 in order to get reboot to work correctly. This is only needed on
1169 some combinations of hardware and BIOS. The symptom, for which
1170 this config is intended, is when reboot ends with a stalled/hung
1173 Currently, the only fixup is for the Geode machines using
1174 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1176 Say Y if you want to enable the fixup. Currently, it's safe to
1177 enable this option even if you don't need it.
1181 bool "CPU microcode loading support"
1183 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1186 If you say Y here, you will be able to update the microcode on
1187 Intel and AMD processors. The Intel support is for the IA32 family,
1188 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1189 AMD support is for families 0x10 and later. You will obviously need
1190 the actual microcode binary data itself which is not shipped with
1193 The preferred method to load microcode from a detached initrd is described
1194 in Documentation/x86/early-microcode.txt. For that you need to enable
1195 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1196 initrd for microcode blobs.
1198 In addition, you can build-in the microcode into the kernel. For that you
1199 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1200 to the CONFIG_EXTRA_FIRMWARE config option.
1202 config MICROCODE_INTEL
1203 bool "Intel microcode loading support"
1204 depends on MICROCODE
1208 This options enables microcode patch loading support for Intel
1211 For the current Intel microcode data package go to
1212 <https://downloadcenter.intel.com> and search for
1213 'Linux Processor Microcode Data File'.
1215 config MICROCODE_AMD
1216 bool "AMD microcode loading support"
1217 depends on MICROCODE
1220 If you select this option, microcode patch loading support for AMD
1221 processors will be enabled.
1223 config MICROCODE_OLD_INTERFACE
1225 depends on MICROCODE
1228 tristate "/dev/cpu/*/msr - Model-specific register support"
1230 This device gives privileged processes access to the x86
1231 Model-Specific Registers (MSRs). It is a character device with
1232 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1233 MSR accesses are directed to a specific CPU on multi-processor
1237 tristate "/dev/cpu/*/cpuid - CPU information support"
1239 This device gives processes access to the x86 CPUID instruction to
1240 be executed on a specific processor. It is a character device
1241 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1245 prompt "High Memory Support"
1252 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1253 However, the address space of 32-bit x86 processors is only 4
1254 Gigabytes large. That means that, if you have a large amount of
1255 physical memory, not all of it can be "permanently mapped" by the
1256 kernel. The physical memory that's not permanently mapped is called
1259 If you are compiling a kernel which will never run on a machine with
1260 more than 1 Gigabyte total physical RAM, answer "off" here (default
1261 choice and suitable for most users). This will result in a "3GB/1GB"
1262 split: 3GB are mapped so that each process sees a 3GB virtual memory
1263 space and the remaining part of the 4GB virtual memory space is used
1264 by the kernel to permanently map as much physical memory as
1267 If the machine has between 1 and 4 Gigabytes physical RAM, then
1270 If more than 4 Gigabytes is used then answer "64GB" here. This
1271 selection turns Intel PAE (Physical Address Extension) mode on.
1272 PAE implements 3-level paging on IA32 processors. PAE is fully
1273 supported by Linux, PAE mode is implemented on all recent Intel
1274 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1275 then the kernel will not boot on CPUs that don't support PAE!
1277 The actual amount of total physical memory will either be
1278 auto detected or can be forced by using a kernel command line option
1279 such as "mem=256M". (Try "man bootparam" or see the documentation of
1280 your boot loader (lilo or loadlin) about how to pass options to the
1281 kernel at boot time.)
1283 If unsure, say "off".
1288 Select this if you have a 32-bit processor and between 1 and 4
1289 gigabytes of physical RAM.
1296 Select this if you have a 32-bit processor and more than 4
1297 gigabytes of physical RAM.
1302 prompt "Memory split" if EXPERT
1306 Select the desired split between kernel and user memory.
1308 If the address range available to the kernel is less than the
1309 physical memory installed, the remaining memory will be available
1310 as "high memory". Accessing high memory is a little more costly
1311 than low memory, as it needs to be mapped into the kernel first.
1312 Note that increasing the kernel address space limits the range
1313 available to user programs, making the address space there
1314 tighter. Selecting anything other than the default 3G/1G split
1315 will also likely make your kernel incompatible with binary-only
1318 If you are not absolutely sure what you are doing, leave this
1322 bool "3G/1G user/kernel split"
1323 config VMSPLIT_3G_OPT
1325 bool "3G/1G user/kernel split (for full 1G low memory)"
1327 bool "2G/2G user/kernel split"
1328 config VMSPLIT_2G_OPT
1330 bool "2G/2G user/kernel split (for full 2G low memory)"
1332 bool "1G/3G user/kernel split"
1337 default 0xB0000000 if VMSPLIT_3G_OPT
1338 default 0x80000000 if VMSPLIT_2G
1339 default 0x78000000 if VMSPLIT_2G_OPT
1340 default 0x40000000 if VMSPLIT_1G
1346 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1349 bool "PAE (Physical Address Extension) Support"
1350 depends on X86_32 && !HIGHMEM4G
1353 PAE is required for NX support, and furthermore enables
1354 larger swapspace support for non-overcommit purposes. It
1355 has the cost of more pagetable lookup overhead, and also
1356 consumes more pagetable space per process.
1358 config ARCH_PHYS_ADDR_T_64BIT
1360 depends on X86_64 || X86_PAE
1362 config ARCH_DMA_ADDR_T_64BIT
1364 depends on X86_64 || HIGHMEM64G
1366 config X86_DIRECT_GBPAGES
1368 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1370 Certain kernel features effectively disable kernel
1371 linear 1 GB mappings (even if the CPU otherwise
1372 supports them), so don't confuse the user by printing
1373 that we have them enabled.
1375 # Common NUMA Features
1377 bool "Numa Memory Allocation and Scheduler Support"
1379 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1380 default y if X86_BIGSMP
1382 Enable NUMA (Non Uniform Memory Access) support.
1384 The kernel will try to allocate memory used by a CPU on the
1385 local memory controller of the CPU and add some more
1386 NUMA awareness to the kernel.
1388 For 64-bit this is recommended if the system is Intel Core i7
1389 (or later), AMD Opteron, or EM64T NUMA.
1391 For 32-bit this is only needed if you boot a 32-bit
1392 kernel on a 64-bit NUMA platform.
1394 Otherwise, you should say N.
1398 prompt "Old style AMD Opteron NUMA detection"
1399 depends on X86_64 && NUMA && PCI
1401 Enable AMD NUMA node topology detection. You should say Y here if
1402 you have a multi processor AMD system. This uses an old method to
1403 read the NUMA configuration directly from the builtin Northbridge
1404 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1405 which also takes priority if both are compiled in.
1407 config X86_64_ACPI_NUMA
1409 prompt "ACPI NUMA detection"
1410 depends on X86_64 && NUMA && ACPI && PCI
1413 Enable ACPI SRAT based node topology detection.
1415 # Some NUMA nodes have memory ranges that span
1416 # other nodes. Even though a pfn is valid and
1417 # between a node's start and end pfns, it may not
1418 # reside on that node. See memmap_init_zone()
1420 config NODES_SPAN_OTHER_NODES
1422 depends on X86_64_ACPI_NUMA
1425 bool "NUMA emulation"
1428 Enable NUMA emulation. A flat machine will be split
1429 into virtual nodes when booted with "numa=fake=N", where N is the
1430 number of nodes. This is only useful for debugging.
1433 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1435 default "10" if MAXSMP
1436 default "6" if X86_64
1438 depends on NEED_MULTIPLE_NODES
1440 Specify the maximum number of NUMA Nodes available on the target
1441 system. Increases memory reserved to accommodate various tables.
1443 config ARCH_HAVE_MEMORY_PRESENT
1445 depends on X86_32 && DISCONTIGMEM
1447 config NEED_NODE_MEMMAP_SIZE
1449 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1451 config ARCH_FLATMEM_ENABLE
1453 depends on X86_32 && !NUMA
1455 config ARCH_DISCONTIGMEM_ENABLE
1457 depends on NUMA && X86_32
1459 config ARCH_DISCONTIGMEM_DEFAULT
1461 depends on NUMA && X86_32
1463 config ARCH_SPARSEMEM_ENABLE
1465 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1466 select SPARSEMEM_STATIC if X86_32
1467 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1469 config ARCH_SPARSEMEM_DEFAULT
1473 config ARCH_SELECT_MEMORY_MODEL
1475 depends on ARCH_SPARSEMEM_ENABLE
1477 config ARCH_MEMORY_PROBE
1478 bool "Enable sysfs memory/probe interface"
1479 depends on X86_64 && MEMORY_HOTPLUG
1481 This option enables a sysfs memory/probe interface for testing.
1482 See Documentation/memory-hotplug.txt for more information.
1483 If you are unsure how to answer this question, answer N.
1485 config ARCH_PROC_KCORE_TEXT
1487 depends on X86_64 && PROC_KCORE
1489 config ILLEGAL_POINTER_VALUE
1492 default 0xdead000000000000 if X86_64
1496 config X86_PMEM_LEGACY_DEVICE
1499 config X86_PMEM_LEGACY
1500 tristate "Support non-standard NVDIMMs and ADR protected memory"
1501 depends on PHYS_ADDR_T_64BIT
1503 select X86_PMEM_LEGACY_DEVICE
1506 Treat memory marked using the non-standard e820 type of 12 as used
1507 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1508 The kernel will offer these regions to the 'pmem' driver so
1509 they can be used for persistent storage.
1514 bool "Allocate 3rd-level pagetables from highmem"
1517 The VM uses one page table entry for each page of physical memory.
1518 For systems with a lot of RAM, this can be wasteful of precious
1519 low memory. Setting this option will put user-space page table
1520 entries in high memory.
1522 config X86_CHECK_BIOS_CORRUPTION
1523 bool "Check for low memory corruption"
1525 Periodically check for memory corruption in low memory, which
1526 is suspected to be caused by BIOS. Even when enabled in the
1527 configuration, it is disabled at runtime. Enable it by
1528 setting "memory_corruption_check=1" on the kernel command
1529 line. By default it scans the low 64k of memory every 60
1530 seconds; see the memory_corruption_check_size and
1531 memory_corruption_check_period parameters in
1532 Documentation/kernel-parameters.txt to adjust this.
1534 When enabled with the default parameters, this option has
1535 almost no overhead, as it reserves a relatively small amount
1536 of memory and scans it infrequently. It both detects corruption
1537 and prevents it from affecting the running system.
1539 It is, however, intended as a diagnostic tool; if repeatable
1540 BIOS-originated corruption always affects the same memory,
1541 you can use memmap= to prevent the kernel from using that
1544 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1545 bool "Set the default setting of memory_corruption_check"
1546 depends on X86_CHECK_BIOS_CORRUPTION
1549 Set whether the default state of memory_corruption_check is
1552 config X86_RESERVE_LOW
1553 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1557 Specify the amount of low memory to reserve for the BIOS.
1559 The first page contains BIOS data structures that the kernel
1560 must not use, so that page must always be reserved.
1562 By default we reserve the first 64K of physical RAM, as a
1563 number of BIOSes are known to corrupt that memory range
1564 during events such as suspend/resume or monitor cable
1565 insertion, so it must not be used by the kernel.
1567 You can set this to 4 if you are absolutely sure that you
1568 trust the BIOS to get all its memory reservations and usages
1569 right. If you know your BIOS have problems beyond the
1570 default 64K area, you can set this to 640 to avoid using the
1571 entire low memory range.
1573 If you have doubts about the BIOS (e.g. suspend/resume does
1574 not work or there's kernel crashes after certain hardware
1575 hotplug events) then you might want to enable
1576 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1577 typical corruption patterns.
1579 Leave this to the default value of 64 if you are unsure.
1581 config MATH_EMULATION
1583 depends on MODIFY_LDT_SYSCALL
1584 prompt "Math emulation" if X86_32
1586 Linux can emulate a math coprocessor (used for floating point
1587 operations) if you don't have one. 486DX and Pentium processors have
1588 a math coprocessor built in, 486SX and 386 do not, unless you added
1589 a 487DX or 387, respectively. (The messages during boot time can
1590 give you some hints here ["man dmesg"].) Everyone needs either a
1591 coprocessor or this emulation.
1593 If you don't have a math coprocessor, you need to say Y here; if you
1594 say Y here even though you have a coprocessor, the coprocessor will
1595 be used nevertheless. (This behavior can be changed with the kernel
1596 command line option "no387", which comes handy if your coprocessor
1597 is broken. Try "man bootparam" or see the documentation of your boot
1598 loader (lilo or loadlin) about how to pass options to the kernel at
1599 boot time.) This means that it is a good idea to say Y here if you
1600 intend to use this kernel on different machines.
1602 More information about the internals of the Linux math coprocessor
1603 emulation can be found in <file:arch/x86/math-emu/README>.
1605 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1606 kernel, it won't hurt.
1610 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1612 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1613 the Memory Type Range Registers (MTRRs) may be used to control
1614 processor access to memory ranges. This is most useful if you have
1615 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1616 allows bus write transfers to be combined into a larger transfer
1617 before bursting over the PCI/AGP bus. This can increase performance
1618 of image write operations 2.5 times or more. Saying Y here creates a
1619 /proc/mtrr file which may be used to manipulate your processor's
1620 MTRRs. Typically the X server should use this.
1622 This code has a reasonably generic interface so that similar
1623 control registers on other processors can be easily supported
1626 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1627 Registers (ARRs) which provide a similar functionality to MTRRs. For
1628 these, the ARRs are used to emulate the MTRRs.
1629 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1630 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1631 write-combining. All of these processors are supported by this code
1632 and it makes sense to say Y here if you have one of them.
1634 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1635 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1636 can lead to all sorts of problems, so it's good to say Y here.
1638 You can safely say Y even if your machine doesn't have MTRRs, you'll
1639 just add about 9 KB to your kernel.
1641 See <file:Documentation/x86/mtrr.txt> for more information.
1643 config MTRR_SANITIZER
1645 prompt "MTRR cleanup support"
1648 Convert MTRR layout from continuous to discrete, so X drivers can
1649 add writeback entries.
1651 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1652 The largest mtrr entry size for a continuous block can be set with
1657 config MTRR_SANITIZER_ENABLE_DEFAULT
1658 int "MTRR cleanup enable value (0-1)"
1661 depends on MTRR_SANITIZER
1663 Enable mtrr cleanup default value
1665 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1666 int "MTRR cleanup spare reg num (0-7)"
1669 depends on MTRR_SANITIZER
1671 mtrr cleanup spare entries default, it can be changed via
1672 mtrr_spare_reg_nr=N on the kernel command line.
1676 prompt "x86 PAT support" if EXPERT
1679 Use PAT attributes to setup page level cache control.
1681 PATs are the modern equivalents of MTRRs and are much more
1682 flexible than MTRRs.
1684 Say N here if you see bootup problems (boot crash, boot hang,
1685 spontaneous reboots) or a non-working video driver.
1689 config ARCH_USES_PG_UNCACHED
1695 prompt "x86 architectural random number generator" if EXPERT
1697 Enable the x86 architectural RDRAND instruction
1698 (Intel Bull Mountain technology) to generate random numbers.
1699 If supported, this is a high bandwidth, cryptographically
1700 secure hardware random number generator.
1704 prompt "Supervisor Mode Access Prevention" if EXPERT
1706 Supervisor Mode Access Prevention (SMAP) is a security
1707 feature in newer Intel processors. There is a small
1708 performance cost if this enabled and turned on; there is
1709 also a small increase in the kernel size if this is enabled.
1713 config X86_INTEL_MPX
1714 prompt "Intel MPX (Memory Protection Extensions)"
1716 depends on CPU_SUP_INTEL
1718 MPX provides hardware features that can be used in
1719 conjunction with compiler-instrumented code to check
1720 memory references. It is designed to detect buffer
1721 overflow or underflow bugs.
1723 This option enables running applications which are
1724 instrumented or otherwise use MPX. It does not use MPX
1725 itself inside the kernel or to protect the kernel
1726 against bad memory references.
1728 Enabling this option will make the kernel larger:
1729 ~8k of kernel text and 36 bytes of data on a 64-bit
1730 defconfig. It adds a long to the 'mm_struct' which
1731 will increase the kernel memory overhead of each
1732 process and adds some branches to paths used during
1733 exec() and munmap().
1735 For details, see Documentation/x86/intel_mpx.txt
1739 config X86_INTEL_MEMORY_PROTECTION_KEYS
1740 prompt "Intel Memory Protection Keys"
1742 # Note: only available in 64-bit mode
1743 depends on CPU_SUP_INTEL && X86_64
1745 Memory Protection Keys provides a mechanism for enforcing
1746 page-based protections, but without requiring modification of the
1747 page tables when an application changes protection domains.
1749 For details, see Documentation/x86/protection-keys.txt
1754 bool "EFI runtime service support"
1757 select EFI_RUNTIME_WRAPPERS
1759 This enables the kernel to use EFI runtime services that are
1760 available (such as the EFI variable services).
1762 This option is only useful on systems that have EFI firmware.
1763 In addition, you should use the latest ELILO loader available
1764 at <http://elilo.sourceforge.net> in order to take advantage
1765 of EFI runtime services. However, even with this option, the
1766 resultant kernel should continue to boot on existing non-EFI
1770 bool "EFI stub support"
1771 depends on EFI && !X86_USE_3DNOW
1774 This kernel feature allows a bzImage to be loaded directly
1775 by EFI firmware without the use of a bootloader.
1777 See Documentation/efi-stub.txt for more information.
1780 bool "EFI mixed-mode support"
1781 depends on EFI_STUB && X86_64
1783 Enabling this feature allows a 64-bit kernel to be booted
1784 on a 32-bit firmware, provided that your CPU supports 64-bit
1787 Note that it is not possible to boot a mixed-mode enabled
1788 kernel via the EFI boot stub - a bootloader that supports
1789 the EFI handover protocol must be used.
1795 prompt "Enable seccomp to safely compute untrusted bytecode"
1797 This kernel feature is useful for number crunching applications
1798 that may need to compute untrusted bytecode during their
1799 execution. By using pipes or other transports made available to
1800 the process as file descriptors supporting the read/write
1801 syscalls, it's possible to isolate those applications in
1802 their own address space using seccomp. Once seccomp is
1803 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1804 and the task is only allowed to execute a few safe syscalls
1805 defined by each seccomp mode.
1807 If unsure, say Y. Only embedded should say N here.
1809 source kernel/Kconfig.hz
1812 bool "kexec system call"
1815 kexec is a system call that implements the ability to shutdown your
1816 current kernel, and to start another kernel. It is like a reboot
1817 but it is independent of the system firmware. And like a reboot
1818 you can start any kernel with it, not just Linux.
1820 The name comes from the similarity to the exec system call.
1822 It is an ongoing process to be certain the hardware in a machine
1823 is properly shutdown, so do not be surprised if this code does not
1824 initially work for you. As of this writing the exact hardware
1825 interface is strongly in flux, so no good recommendation can be
1829 bool "kexec file based system call"
1834 depends on CRYPTO_SHA256=y
1836 This is new version of kexec system call. This system call is
1837 file based and takes file descriptors as system call argument
1838 for kernel and initramfs as opposed to list of segments as
1839 accepted by previous system call.
1841 config KEXEC_VERIFY_SIG
1842 bool "Verify kernel signature during kexec_file_load() syscall"
1843 depends on KEXEC_FILE
1845 This option makes kernel signature verification mandatory for
1846 the kexec_file_load() syscall.
1848 In addition to that option, you need to enable signature
1849 verification for the corresponding kernel image type being
1850 loaded in order for this to work.
1852 config KEXEC_BZIMAGE_VERIFY_SIG
1853 bool "Enable bzImage signature verification support"
1854 depends on KEXEC_VERIFY_SIG
1855 depends on SIGNED_PE_FILE_VERIFICATION
1856 select SYSTEM_TRUSTED_KEYRING
1858 Enable bzImage signature verification support.
1861 bool "kernel crash dumps"
1862 depends on X86_64 || (X86_32 && HIGHMEM)
1864 Generate crash dump after being started by kexec.
1865 This should be normally only set in special crash dump kernels
1866 which are loaded in the main kernel with kexec-tools into
1867 a specially reserved region and then later executed after
1868 a crash by kdump/kexec. The crash dump kernel must be compiled
1869 to a memory address not used by the main kernel or BIOS using
1870 PHYSICAL_START, or it must be built as a relocatable image
1871 (CONFIG_RELOCATABLE=y).
1872 For more details see Documentation/kdump/kdump.txt
1876 depends on KEXEC && HIBERNATION
1878 Jump between original kernel and kexeced kernel and invoke
1879 code in physical address mode via KEXEC
1881 config PHYSICAL_START
1882 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1885 This gives the physical address where the kernel is loaded.
1887 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1888 bzImage will decompress itself to above physical address and
1889 run from there. Otherwise, bzImage will run from the address where
1890 it has been loaded by the boot loader and will ignore above physical
1893 In normal kdump cases one does not have to set/change this option
1894 as now bzImage can be compiled as a completely relocatable image
1895 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1896 address. This option is mainly useful for the folks who don't want
1897 to use a bzImage for capturing the crash dump and want to use a
1898 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1899 to be specifically compiled to run from a specific memory area
1900 (normally a reserved region) and this option comes handy.
1902 So if you are using bzImage for capturing the crash dump,
1903 leave the value here unchanged to 0x1000000 and set
1904 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1905 for capturing the crash dump change this value to start of
1906 the reserved region. In other words, it can be set based on
1907 the "X" value as specified in the "crashkernel=YM@XM"
1908 command line boot parameter passed to the panic-ed
1909 kernel. Please take a look at Documentation/kdump/kdump.txt
1910 for more details about crash dumps.
1912 Usage of bzImage for capturing the crash dump is recommended as
1913 one does not have to build two kernels. Same kernel can be used
1914 as production kernel and capture kernel. Above option should have
1915 gone away after relocatable bzImage support is introduced. But it
1916 is present because there are users out there who continue to use
1917 vmlinux for dump capture. This option should go away down the
1920 Don't change this unless you know what you are doing.
1923 bool "Build a relocatable kernel"
1926 This builds a kernel image that retains relocation information
1927 so it can be loaded someplace besides the default 1MB.
1928 The relocations tend to make the kernel binary about 10% larger,
1929 but are discarded at runtime.
1931 One use is for the kexec on panic case where the recovery kernel
1932 must live at a different physical address than the primary
1935 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1936 it has been loaded at and the compile time physical address
1937 (CONFIG_PHYSICAL_START) is used as the minimum location.
1939 config RANDOMIZE_BASE
1940 bool "Randomize the address of the kernel image (KASLR)"
1941 depends on RELOCATABLE
1944 In support of Kernel Address Space Layout Randomization (KASLR),
1945 this randomizes the physical address at which the kernel image
1946 is decompressed and the virtual address where the kernel
1947 image is mapped, as a security feature that deters exploit
1948 attempts relying on knowledge of the location of kernel
1951 On 64-bit, the kernel physical and virtual addresses are
1952 randomized separately. The physical address will be anywhere
1953 between 16MB and the top of physical memory (up to 64TB). The
1954 virtual address will be randomized from 16MB up to 1GB (9 bits
1955 of entropy). Note that this also reduces the memory space
1956 available to kernel modules from 1.5GB to 1GB.
1958 On 32-bit, the kernel physical and virtual addresses are
1959 randomized together. They will be randomized from 16MB up to
1960 512MB (8 bits of entropy).
1962 Entropy is generated using the RDRAND instruction if it is
1963 supported. If RDTSC is supported, its value is mixed into
1964 the entropy pool as well. If neither RDRAND nor RDTSC are
1965 supported, then entropy is read from the i8254 timer. The
1966 usable entropy is limited by the kernel being built using
1967 2GB addressing, and that PHYSICAL_ALIGN must be at a
1968 minimum of 2MB. As a result, only 10 bits of entropy are
1969 theoretically possible, but the implementations are further
1970 limited due to memory layouts.
1972 If CONFIG_HIBERNATE is also enabled, KASLR is disabled at boot
1973 time. To enable it, boot with "kaslr" on the kernel command
1974 line (which will also disable hibernation).
1978 # Relocation on x86 needs some additional build support
1979 config X86_NEED_RELOCS
1981 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1983 config PHYSICAL_ALIGN
1984 hex "Alignment value to which kernel should be aligned"
1986 range 0x2000 0x1000000 if X86_32
1987 range 0x200000 0x1000000 if X86_64
1989 This value puts the alignment restrictions on physical address
1990 where kernel is loaded and run from. Kernel is compiled for an
1991 address which meets above alignment restriction.
1993 If bootloader loads the kernel at a non-aligned address and
1994 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1995 address aligned to above value and run from there.
1997 If bootloader loads the kernel at a non-aligned address and
1998 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1999 load address and decompress itself to the address it has been
2000 compiled for and run from there. The address for which kernel is
2001 compiled already meets above alignment restrictions. Hence the
2002 end result is that kernel runs from a physical address meeting
2003 above alignment restrictions.
2005 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2006 this value must be a multiple of 0x200000.
2008 Don't change this unless you know what you are doing.
2010 config RANDOMIZE_MEMORY
2011 bool "Randomize the kernel memory sections"
2013 depends on RANDOMIZE_BASE
2014 default RANDOMIZE_BASE
2016 Randomizes the base virtual address of kernel memory sections
2017 (physical memory mapping, vmalloc & vmemmap). This security feature
2018 makes exploits relying on predictable memory locations less reliable.
2020 The order of allocations remains unchanged. Entropy is generated in
2021 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2022 configuration have in average 30,000 different possible virtual
2023 addresses for each memory section.
2027 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2028 hex "Physical memory mapping padding" if EXPERT
2029 depends on RANDOMIZE_MEMORY
2030 default "0xa" if MEMORY_HOTPLUG
2032 range 0x1 0x40 if MEMORY_HOTPLUG
2035 Define the padding in terabytes added to the existing physical
2036 memory size during kernel memory randomization. It is useful
2037 for memory hotplug support but reduces the entropy available for
2038 address randomization.
2040 If unsure, leave at the default value.
2043 bool "Support for hot-pluggable CPUs"
2046 Say Y here to allow turning CPUs off and on. CPUs can be
2047 controlled through /sys/devices/system/cpu.
2048 ( Note: power management support will enable this option
2049 automatically on SMP systems. )
2050 Say N if you want to disable CPU hotplug.
2052 config BOOTPARAM_HOTPLUG_CPU0
2053 bool "Set default setting of cpu0_hotpluggable"
2055 depends on HOTPLUG_CPU
2057 Set whether default state of cpu0_hotpluggable is on or off.
2059 Say Y here to enable CPU0 hotplug by default. If this switch
2060 is turned on, there is no need to give cpu0_hotplug kernel
2061 parameter and the CPU0 hotplug feature is enabled by default.
2063 Please note: there are two known CPU0 dependencies if you want
2064 to enable the CPU0 hotplug feature either by this switch or by
2065 cpu0_hotplug kernel parameter.
2067 First, resume from hibernate or suspend always starts from CPU0.
2068 So hibernate and suspend are prevented if CPU0 is offline.
2070 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2071 offline if any interrupt can not migrate out of CPU0. There may
2072 be other CPU0 dependencies.
2074 Please make sure the dependencies are under your control before
2075 you enable this feature.
2077 Say N if you don't want to enable CPU0 hotplug feature by default.
2078 You still can enable the CPU0 hotplug feature at boot by kernel
2079 parameter cpu0_hotplug.
2081 config DEBUG_HOTPLUG_CPU0
2083 prompt "Debug CPU0 hotplug"
2084 depends on HOTPLUG_CPU
2086 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2087 soon as possible and boots up userspace with CPU0 offlined. User
2088 can online CPU0 back after boot time.
2090 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2091 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2092 compilation or giving cpu0_hotplug kernel parameter at boot.
2098 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2099 depends on X86_32 || IA32_EMULATION
2101 Certain buggy versions of glibc will crash if they are
2102 presented with a 32-bit vDSO that is not mapped at the address
2103 indicated in its segment table.
2105 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2106 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2107 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2108 the only released version with the bug, but OpenSUSE 9
2109 contains a buggy "glibc 2.3.2".
2111 The symptom of the bug is that everything crashes on startup, saying:
2112 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2114 Saying Y here changes the default value of the vdso32 boot
2115 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2116 This works around the glibc bug but hurts performance.
2118 If unsure, say N: if you are compiling your own kernel, you
2119 are unlikely to be using a buggy version of glibc.
2122 prompt "vsyscall table for legacy applications"
2124 default LEGACY_VSYSCALL_EMULATE
2126 Legacy user code that does not know how to find the vDSO expects
2127 to be able to issue three syscalls by calling fixed addresses in
2128 kernel space. Since this location is not randomized with ASLR,
2129 it can be used to assist security vulnerability exploitation.
2131 This setting can be changed at boot time via the kernel command
2132 line parameter vsyscall=[native|emulate|none].
2134 On a system with recent enough glibc (2.14 or newer) and no
2135 static binaries, you can say None without a performance penalty
2136 to improve security.
2138 If unsure, select "Emulate".
2140 config LEGACY_VSYSCALL_NATIVE
2143 Actual executable code is located in the fixed vsyscall
2144 address mapping, implementing time() efficiently. Since
2145 this makes the mapping executable, it can be used during
2146 security vulnerability exploitation (traditionally as
2147 ROP gadgets). This configuration is not recommended.
2149 config LEGACY_VSYSCALL_EMULATE
2152 The kernel traps and emulates calls into the fixed
2153 vsyscall address mapping. This makes the mapping
2154 non-executable, but it still contains known contents,
2155 which could be used in certain rare security vulnerability
2156 exploits. This configuration is recommended when userspace
2157 still uses the vsyscall area.
2159 config LEGACY_VSYSCALL_NONE
2162 There will be no vsyscall mapping at all. This will
2163 eliminate any risk of ASLR bypass due to the vsyscall
2164 fixed address mapping. Attempts to use the vsyscalls
2165 will be reported to dmesg, so that either old or
2166 malicious userspace programs can be identified.
2171 bool "Built-in kernel command line"
2173 Allow for specifying boot arguments to the kernel at
2174 build time. On some systems (e.g. embedded ones), it is
2175 necessary or convenient to provide some or all of the
2176 kernel boot arguments with the kernel itself (that is,
2177 to not rely on the boot loader to provide them.)
2179 To compile command line arguments into the kernel,
2180 set this option to 'Y', then fill in the
2181 boot arguments in CONFIG_CMDLINE.
2183 Systems with fully functional boot loaders (i.e. non-embedded)
2184 should leave this option set to 'N'.
2187 string "Built-in kernel command string"
2188 depends on CMDLINE_BOOL
2191 Enter arguments here that should be compiled into the kernel
2192 image and used at boot time. If the boot loader provides a
2193 command line at boot time, it is appended to this string to
2194 form the full kernel command line, when the system boots.
2196 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2197 change this behavior.
2199 In most cases, the command line (whether built-in or provided
2200 by the boot loader) should specify the device for the root
2203 config CMDLINE_OVERRIDE
2204 bool "Built-in command line overrides boot loader arguments"
2205 depends on CMDLINE_BOOL
2207 Set this option to 'Y' to have the kernel ignore the boot loader
2208 command line, and use ONLY the built-in command line.
2210 This is used to work around broken boot loaders. This should
2211 be set to 'N' under normal conditions.
2213 config MODIFY_LDT_SYSCALL
2214 bool "Enable the LDT (local descriptor table)" if EXPERT
2217 Linux can allow user programs to install a per-process x86
2218 Local Descriptor Table (LDT) using the modify_ldt(2) system
2219 call. This is required to run 16-bit or segmented code such as
2220 DOSEMU or some Wine programs. It is also used by some very old
2221 threading libraries.
2223 Enabling this feature adds a small amount of overhead to
2224 context switches and increases the low-level kernel attack
2225 surface. Disabling it removes the modify_ldt(2) system call.
2227 Saying 'N' here may make sense for embedded or server kernels.
2229 source "kernel/livepatch/Kconfig"
2233 config ARCH_ENABLE_MEMORY_HOTPLUG
2235 depends on X86_64 || (X86_32 && HIGHMEM)
2237 config ARCH_ENABLE_MEMORY_HOTREMOVE
2239 depends on MEMORY_HOTPLUG
2241 config USE_PERCPU_NUMA_NODE_ID
2245 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2247 depends on X86_64 || X86_PAE
2249 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2251 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2253 menu "Power management and ACPI options"
2255 config ARCH_HIBERNATION_HEADER
2257 depends on X86_64 && HIBERNATION
2259 source "kernel/power/Kconfig"
2261 source "drivers/acpi/Kconfig"
2263 source "drivers/sfi/Kconfig"
2270 tristate "APM (Advanced Power Management) BIOS support"
2271 depends on X86_32 && PM_SLEEP
2273 APM is a BIOS specification for saving power using several different
2274 techniques. This is mostly useful for battery powered laptops with
2275 APM compliant BIOSes. If you say Y here, the system time will be
2276 reset after a RESUME operation, the /proc/apm device will provide
2277 battery status information, and user-space programs will receive
2278 notification of APM "events" (e.g. battery status change).
2280 If you select "Y" here, you can disable actual use of the APM
2281 BIOS by passing the "apm=off" option to the kernel at boot time.
2283 Note that the APM support is almost completely disabled for
2284 machines with more than one CPU.
2286 In order to use APM, you will need supporting software. For location
2287 and more information, read <file:Documentation/power/apm-acpi.txt>
2288 and the Battery Powered Linux mini-HOWTO, available from
2289 <http://www.tldp.org/docs.html#howto>.
2291 This driver does not spin down disk drives (see the hdparm(8)
2292 manpage ("man 8 hdparm") for that), and it doesn't turn off
2293 VESA-compliant "green" monitors.
2295 This driver does not support the TI 4000M TravelMate and the ACER
2296 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2297 desktop machines also don't have compliant BIOSes, and this driver
2298 may cause those machines to panic during the boot phase.
2300 Generally, if you don't have a battery in your machine, there isn't
2301 much point in using this driver and you should say N. If you get
2302 random kernel OOPSes or reboots that don't seem to be related to
2303 anything, try disabling/enabling this option (or disabling/enabling
2306 Some other things you should try when experiencing seemingly random,
2309 1) make sure that you have enough swap space and that it is
2311 2) pass the "no-hlt" option to the kernel
2312 3) switch on floating point emulation in the kernel and pass
2313 the "no387" option to the kernel
2314 4) pass the "floppy=nodma" option to the kernel
2315 5) pass the "mem=4M" option to the kernel (thereby disabling
2316 all but the first 4 MB of RAM)
2317 6) make sure that the CPU is not over clocked.
2318 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2319 8) disable the cache from your BIOS settings
2320 9) install a fan for the video card or exchange video RAM
2321 10) install a better fan for the CPU
2322 11) exchange RAM chips
2323 12) exchange the motherboard.
2325 To compile this driver as a module, choose M here: the
2326 module will be called apm.
2330 config APM_IGNORE_USER_SUSPEND
2331 bool "Ignore USER SUSPEND"
2333 This option will ignore USER SUSPEND requests. On machines with a
2334 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2335 series notebooks, it is necessary to say Y because of a BIOS bug.
2337 config APM_DO_ENABLE
2338 bool "Enable PM at boot time"
2340 Enable APM features at boot time. From page 36 of the APM BIOS
2341 specification: "When disabled, the APM BIOS does not automatically
2342 power manage devices, enter the Standby State, enter the Suspend
2343 State, or take power saving steps in response to CPU Idle calls."
2344 This driver will make CPU Idle calls when Linux is idle (unless this
2345 feature is turned off -- see "Do CPU IDLE calls", below). This
2346 should always save battery power, but more complicated APM features
2347 will be dependent on your BIOS implementation. You may need to turn
2348 this option off if your computer hangs at boot time when using APM
2349 support, or if it beeps continuously instead of suspending. Turn
2350 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2351 T400CDT. This is off by default since most machines do fine without
2356 bool "Make CPU Idle calls when idle"
2358 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2359 On some machines, this can activate improved power savings, such as
2360 a slowed CPU clock rate, when the machine is idle. These idle calls
2361 are made after the idle loop has run for some length of time (e.g.,
2362 333 mS). On some machines, this will cause a hang at boot time or
2363 whenever the CPU becomes idle. (On machines with more than one CPU,
2364 this option does nothing.)
2366 config APM_DISPLAY_BLANK
2367 bool "Enable console blanking using APM"
2369 Enable console blanking using the APM. Some laptops can use this to
2370 turn off the LCD backlight when the screen blanker of the Linux
2371 virtual console blanks the screen. Note that this is only used by
2372 the virtual console screen blanker, and won't turn off the backlight
2373 when using the X Window system. This also doesn't have anything to
2374 do with your VESA-compliant power-saving monitor. Further, this
2375 option doesn't work for all laptops -- it might not turn off your
2376 backlight at all, or it might print a lot of errors to the console,
2377 especially if you are using gpm.
2379 config APM_ALLOW_INTS
2380 bool "Allow interrupts during APM BIOS calls"
2382 Normally we disable external interrupts while we are making calls to
2383 the APM BIOS as a measure to lessen the effects of a badly behaving
2384 BIOS implementation. The BIOS should reenable interrupts if it
2385 needs to. Unfortunately, some BIOSes do not -- especially those in
2386 many of the newer IBM Thinkpads. If you experience hangs when you
2387 suspend, try setting this to Y. Otherwise, say N.
2391 source "drivers/cpufreq/Kconfig"
2393 source "drivers/cpuidle/Kconfig"
2395 source "drivers/idle/Kconfig"
2400 menu "Bus options (PCI etc.)"
2406 Find out whether you have a PCI motherboard. PCI is the name of a
2407 bus system, i.e. the way the CPU talks to the other stuff inside
2408 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2409 VESA. If you have PCI, say Y, otherwise N.
2412 prompt "PCI access mode"
2413 depends on X86_32 && PCI
2416 On PCI systems, the BIOS can be used to detect the PCI devices and
2417 determine their configuration. However, some old PCI motherboards
2418 have BIOS bugs and may crash if this is done. Also, some embedded
2419 PCI-based systems don't have any BIOS at all. Linux can also try to
2420 detect the PCI hardware directly without using the BIOS.
2422 With this option, you can specify how Linux should detect the
2423 PCI devices. If you choose "BIOS", the BIOS will be used,
2424 if you choose "Direct", the BIOS won't be used, and if you
2425 choose "MMConfig", then PCI Express MMCONFIG will be used.
2426 If you choose "Any", the kernel will try MMCONFIG, then the
2427 direct access method and falls back to the BIOS if that doesn't
2428 work. If unsure, go with the default, which is "Any".
2433 config PCI_GOMMCONFIG
2450 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2452 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2455 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2459 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2463 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2467 depends on PCI && XEN
2475 bool "Support mmconfig PCI config space access"
2476 depends on X86_64 && PCI && ACPI
2478 config PCI_CNB20LE_QUIRK
2479 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2482 Read the PCI windows out of the CNB20LE host bridge. This allows
2483 PCI hotplug to work on systems with the CNB20LE chipset which do
2486 There's no public spec for this chipset, and this functionality
2487 is known to be incomplete.
2489 You should say N unless you know you need this.
2491 source "drivers/pci/Kconfig"
2494 bool "ISA-style bus support on modern systems" if EXPERT
2497 Enables ISA-style drivers on modern systems. This is necessary to
2498 support PC/104 devices on X86_64 platforms.
2502 # x86_64 have no ISA slots, but can have ISA-style DMA.
2504 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2507 Enables ISA-style DMA support for devices requiring such controllers.
2515 Find out whether you have ISA slots on your motherboard. ISA is the
2516 name of a bus system, i.e. the way the CPU talks to the other stuff
2517 inside your box. Other bus systems are PCI, EISA, MicroChannel
2518 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2519 newer boards don't support it. If you have ISA, say Y, otherwise N.
2525 The Extended Industry Standard Architecture (EISA) bus was
2526 developed as an open alternative to the IBM MicroChannel bus.
2528 The EISA bus provided some of the features of the IBM MicroChannel
2529 bus while maintaining backward compatibility with cards made for
2530 the older ISA bus. The EISA bus saw limited use between 1988 and
2531 1995 when it was made obsolete by the PCI bus.
2533 Say Y here if you are building a kernel for an EISA-based machine.
2537 source "drivers/eisa/Kconfig"
2540 tristate "NatSemi SCx200 support"
2542 This provides basic support for National Semiconductor's
2543 (now AMD's) Geode processors. The driver probes for the
2544 PCI-IDs of several on-chip devices, so its a good dependency
2545 for other scx200_* drivers.
2547 If compiled as a module, the driver is named scx200.
2549 config SCx200HR_TIMER
2550 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2554 This driver provides a clocksource built upon the on-chip
2555 27MHz high-resolution timer. Its also a workaround for
2556 NSC Geode SC-1100's buggy TSC, which loses time when the
2557 processor goes idle (as is done by the scheduler). The
2558 other workaround is idle=poll boot option.
2561 bool "One Laptop Per Child support"
2568 Add support for detecting the unique features of the OLPC
2572 bool "OLPC XO-1 Power Management"
2573 depends on OLPC && MFD_CS5535 && PM_SLEEP
2576 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2579 bool "OLPC XO-1 Real Time Clock"
2580 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2582 Add support for the XO-1 real time clock, which can be used as a
2583 programmable wakeup source.
2586 bool "OLPC XO-1 SCI extras"
2587 depends on OLPC && OLPC_XO1_PM
2593 Add support for SCI-based features of the OLPC XO-1 laptop:
2594 - EC-driven system wakeups
2598 - AC adapter status updates
2599 - Battery status updates
2601 config OLPC_XO15_SCI
2602 bool "OLPC XO-1.5 SCI extras"
2603 depends on OLPC && ACPI
2606 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2607 - EC-driven system wakeups
2608 - AC adapter status updates
2609 - Battery status updates
2612 bool "PCEngines ALIX System Support (LED setup)"
2615 This option enables system support for the PCEngines ALIX.
2616 At present this just sets up LEDs for GPIO control on
2617 ALIX2/3/6 boards. However, other system specific setup should
2620 Note: You must still enable the drivers for GPIO and LED support
2621 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2623 Note: You have to set alix.force=1 for boards with Award BIOS.
2626 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2629 This option enables system support for the Soekris Engineering net5501.
2632 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2636 This option enables system support for the Traverse Technologies GEOS.
2639 bool "Technologic Systems TS-5500 platform support"
2641 select CHECK_SIGNATURE
2645 This option enables system support for the Technologic Systems TS-5500.
2651 depends on CPU_SUP_AMD && PCI
2653 source "drivers/pcmcia/Kconfig"
2656 tristate "RapidIO support"
2660 If enabled this option will include drivers and the core
2661 infrastructure code to support RapidIO interconnect devices.
2663 source "drivers/rapidio/Kconfig"
2666 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2668 Firmwares often provide initial graphics framebuffers so the BIOS,
2669 bootloader or kernel can show basic video-output during boot for
2670 user-guidance and debugging. Historically, x86 used the VESA BIOS
2671 Extensions and EFI-framebuffers for this, which are mostly limited
2673 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2674 framebuffers so the new generic system-framebuffer drivers can be
2675 used on x86. If the framebuffer is not compatible with the generic
2676 modes, it is adverticed as fallback platform framebuffer so legacy
2677 drivers like efifb, vesafb and uvesafb can pick it up.
2678 If this option is not selected, all system framebuffers are always
2679 marked as fallback platform framebuffers as usual.
2681 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2682 not be able to pick up generic system framebuffers if this option
2683 is selected. You are highly encouraged to enable simplefb as
2684 replacement if you select this option. simplefb can correctly deal
2685 with generic system framebuffers. But you should still keep vesafb
2686 and others enabled as fallback if a system framebuffer is
2687 incompatible with simplefb.
2694 menu "Executable file formats / Emulations"
2696 source "fs/Kconfig.binfmt"
2698 config IA32_EMULATION
2699 bool "IA32 Emulation"
2702 select COMPAT_BINFMT_ELF
2703 select ARCH_WANT_OLD_COMPAT_IPC
2705 Include code to run legacy 32-bit programs under a
2706 64-bit kernel. You should likely turn this on, unless you're
2707 100% sure that you don't have any 32-bit programs left.
2710 tristate "IA32 a.out support"
2711 depends on IA32_EMULATION
2713 Support old a.out binaries in the 32bit emulation.
2716 bool "x32 ABI for 64-bit mode"
2719 Include code to run binaries for the x32 native 32-bit ABI
2720 for 64-bit processors. An x32 process gets access to the
2721 full 64-bit register file and wide data path while leaving
2722 pointers at 32 bits for smaller memory footprint.
2724 You will need a recent binutils (2.22 or later) with
2725 elf32_x86_64 support enabled to compile a kernel with this
2730 depends on IA32_EMULATION || X86_X32
2733 config COMPAT_FOR_U64_ALIGNMENT
2736 config SYSVIPC_COMPAT
2748 config HAVE_ATOMIC_IOMAP
2752 config X86_DEV_DMA_OPS
2754 depends on X86_64 || STA2X11
2756 config X86_DMA_REMAP
2764 source "net/Kconfig"
2766 source "drivers/Kconfig"
2768 source "drivers/firmware/Kconfig"
2772 source "arch/x86/Kconfig.debug"
2774 source "security/Kconfig"
2776 source "crypto/Kconfig"
2778 source "arch/x86/kvm/Kconfig"
2780 source "lib/Kconfig"