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_ATOMIC64_DEC_IF_POSITIVE
27 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
28 select ARCH_HAS_ELF_RANDOMIZE
29 select ARCH_HAS_FAST_MULTIPLIER
30 select ARCH_HAS_GCOV_PROFILE_ALL
31 select ARCH_HAS_PMEM_API if X86_64
32 select ARCH_HAS_MMIO_FLUSH
33 select ARCH_HAS_SG_CHAIN
34 select ARCH_HAVE_NMI_SAFE_CMPXCHG
35 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
36 select ARCH_MIGHT_HAVE_PC_PARPORT
37 select ARCH_MIGHT_HAVE_PC_SERIO
38 select ARCH_SUPPORTS_ATOMIC_RMW
39 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
40 select ARCH_SUPPORTS_INT128 if X86_64
41 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
42 select ARCH_USE_BUILTIN_BSWAP
43 select ARCH_USE_CMPXCHG_LOCKREF if X86_64
44 select ARCH_USE_QUEUED_RWLOCKS
45 select ARCH_USE_QUEUED_SPINLOCKS
46 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
47 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
48 select ARCH_WANT_FRAME_POINTERS
49 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
50 select ARCH_WANT_OPTIONAL_GPIOLIB
51 select BUILDTIME_EXTABLE_SORT
53 select CLKSRC_I8253 if X86_32
54 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
55 select CLOCKSOURCE_WATCHDOG
56 select CLONE_BACKWARDS if X86_32
57 select COMPAT_OLD_SIGACTION if IA32_EMULATION
58 select DCACHE_WORD_ACCESS
59 select EDAC_ATOMIC_SCRUB
61 select GENERIC_CLOCKEVENTS
62 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
63 select GENERIC_CLOCKEVENTS_MIN_ADJUST
64 select GENERIC_CMOS_UPDATE
65 select GENERIC_CPU_AUTOPROBE
66 select GENERIC_EARLY_IOREMAP
67 select GENERIC_FIND_FIRST_BIT
69 select GENERIC_IRQ_PROBE
70 select GENERIC_IRQ_SHOW
71 select GENERIC_PENDING_IRQ if SMP
72 select GENERIC_SMP_IDLE_THREAD
73 select GENERIC_STRNCPY_FROM_USER
74 select GENERIC_STRNLEN_USER
75 select GENERIC_TIME_VSYSCALL
76 select HAVE_ACPI_APEI if ACPI
77 select HAVE_ACPI_APEI_NMI if ACPI
78 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
79 select HAVE_AOUT if X86_32
80 select HAVE_ARCH_AUDITSYSCALL
81 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
82 select HAVE_ARCH_JUMP_LABEL
83 select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
85 select HAVE_ARCH_KMEMCHECK
86 select HAVE_ARCH_SECCOMP_FILTER
87 select HAVE_ARCH_SOFT_DIRTY if X86_64
88 select HAVE_ARCH_TRACEHOOK
89 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
90 select HAVE_BPF_JIT if X86_64
91 select HAVE_CC_STACKPROTECTOR
92 select HAVE_CMPXCHG_DOUBLE
93 select HAVE_CMPXCHG_LOCAL
94 select HAVE_CONTEXT_TRACKING if X86_64
95 select HAVE_COPY_THREAD_TLS
96 select HAVE_C_RECORDMCOUNT
97 select HAVE_DEBUG_KMEMLEAK
98 select HAVE_DEBUG_STACKOVERFLOW
99 select HAVE_DMA_API_DEBUG
100 select HAVE_DMA_ATTRS
101 select HAVE_DMA_CONTIGUOUS
102 select HAVE_DYNAMIC_FTRACE
103 select HAVE_DYNAMIC_FTRACE_WITH_REGS
104 select HAVE_EFFICIENT_UNALIGNED_ACCESS
105 select HAVE_FENTRY if X86_64
106 select HAVE_FTRACE_MCOUNT_RECORD
107 select HAVE_FUNCTION_GRAPH_FP_TEST
108 select HAVE_FUNCTION_GRAPH_TRACER
109 select HAVE_FUNCTION_TRACER
110 select HAVE_GENERIC_DMA_COHERENT if X86_32
111 select HAVE_HW_BREAKPOINT
113 select HAVE_IOREMAP_PROT
114 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
115 select HAVE_IRQ_TIME_ACCOUNTING
116 select HAVE_KERNEL_BZIP2
117 select HAVE_KERNEL_GZIP
118 select HAVE_KERNEL_LZ4
119 select HAVE_KERNEL_LZMA
120 select HAVE_KERNEL_LZO
121 select HAVE_KERNEL_XZ
123 select HAVE_KPROBES_ON_FTRACE
124 select HAVE_KRETPROBES
126 select HAVE_LIVEPATCH if X86_64
128 select HAVE_MEMBLOCK_NODE_MAP
129 select HAVE_MIXED_BREAKPOINTS_REGS
131 select HAVE_OPTPROBES
132 select HAVE_PCSPKR_PLATFORM
133 select HAVE_PERF_EVENTS
134 select HAVE_PERF_EVENTS_NMI
135 select HAVE_PERF_REGS
136 select HAVE_PERF_USER_STACK_DUMP
137 select HAVE_REGS_AND_STACK_ACCESS_API
138 select HAVE_SYSCALL_TRACEPOINTS
139 select HAVE_UID16 if X86_32 || IA32_EMULATION
140 select HAVE_UNSTABLE_SCHED_CLOCK
141 select HAVE_USER_RETURN_NOTIFIER
142 select IRQ_FORCED_THREADING
143 select MODULES_USE_ELF_RELA if X86_64
144 select MODULES_USE_ELF_REL if X86_32
145 select OLD_SIGACTION if X86_32
146 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
151 select SYSCTL_EXCEPTION_TRACE
152 select USER_STACKTRACE_SUPPORT
154 select X86_DEV_DMA_OPS if X86_64
155 select X86_FEATURE_NAMES if PROC_FS
157 config INSTRUCTION_DECODER
159 depends on KPROBES || PERF_EVENTS || UPROBES
161 config PERF_EVENTS_INTEL_UNCORE
163 depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
167 default "elf32-i386" if X86_32
168 default "elf64-x86-64" if X86_64
170 config ARCH_DEFCONFIG
172 default "arch/x86/configs/i386_defconfig" if X86_32
173 default "arch/x86/configs/x86_64_defconfig" if X86_64
175 config LOCKDEP_SUPPORT
178 config STACKTRACE_SUPPORT
181 config HAVE_LATENCYTOP_SUPPORT
190 config NEED_DMA_MAP_STATE
192 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
194 config NEED_SG_DMA_LENGTH
197 config GENERIC_ISA_DMA
199 depends on ISA_DMA_API
204 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
206 config GENERIC_BUG_RELATIVE_POINTERS
209 config GENERIC_HWEIGHT
212 config ARCH_MAY_HAVE_PC_FDC
214 depends on ISA_DMA_API
216 config RWSEM_GENERIC_SPINLOCK
217 def_bool PREEMPT_RT_FULL
219 config RWSEM_XCHGADD_ALGORITHM
220 def_bool !RWSEM_GENERIC_SPINLOCK && !PREEMPT_RT_FULL
222 config GENERIC_CALIBRATE_DELAY
225 config ARCH_HAS_CPU_RELAX
228 config ARCH_HAS_CACHE_LINE_SIZE
231 config HAVE_SETUP_PER_CPU_AREA
234 config NEED_PER_CPU_EMBED_FIRST_CHUNK
237 config NEED_PER_CPU_PAGE_FIRST_CHUNK
240 config ARCH_HIBERNATION_POSSIBLE
243 config ARCH_SUSPEND_POSSIBLE
246 config ARCH_WANT_HUGE_PMD_SHARE
249 config ARCH_WANT_GENERAL_HUGETLB
258 config ARCH_SUPPORTS_OPTIMIZED_INLINING
261 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
264 config KASAN_SHADOW_OFFSET
267 default 0xdffffc0000000000
269 config HAVE_INTEL_TXT
271 depends on INTEL_IOMMU && ACPI
275 depends on X86_32 && SMP
279 depends on X86_64 && SMP
281 config X86_32_LAZY_GS
283 depends on X86_32 && !CC_STACKPROTECTOR
285 config ARCH_HWEIGHT_CFLAGS
287 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
288 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
290 config ARCH_SUPPORTS_UPROBES
293 config FIX_EARLYCON_MEM
296 config PGTABLE_LEVELS
302 source "init/Kconfig"
303 source "kernel/Kconfig.freezer"
305 menu "Processor type and features"
308 bool "DMA memory allocation support" if EXPERT
311 DMA memory allocation support allows devices with less than 32-bit
312 addressing to allocate within the first 16MB of address space.
313 Disable if no such devices will be used.
318 bool "Symmetric multi-processing support"
320 This enables support for systems with more than one CPU. If you have
321 a system with only one CPU, say N. If you have a system with more
324 If you say N here, the kernel will run on uni- and multiprocessor
325 machines, but will use only one CPU of a multiprocessor machine. If
326 you say Y here, the kernel will run on many, but not all,
327 uniprocessor machines. On a uniprocessor machine, the kernel
328 will run faster if you say N here.
330 Note that if you say Y here and choose architecture "586" or
331 "Pentium" under "Processor family", the kernel will not work on 486
332 architectures. Similarly, multiprocessor kernels for the "PPro"
333 architecture may not work on all Pentium based boards.
335 People using multiprocessor machines who say Y here should also say
336 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
337 Management" code will be disabled if you say Y here.
339 See also <file:Documentation/x86/i386/IO-APIC.txt>,
340 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
341 <http://www.tldp.org/docs.html#howto>.
343 If you don't know what to do here, say N.
345 config X86_FEATURE_NAMES
346 bool "Processor feature human-readable names" if EMBEDDED
349 This option compiles in a table of x86 feature bits and corresponding
350 names. This is required to support /proc/cpuinfo and a few kernel
351 messages. You can disable this to save space, at the expense of
352 making those few kernel messages show numeric feature bits instead.
357 bool "Support x2apic"
358 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
360 This enables x2apic support on CPUs that have this feature.
362 This allows 32-bit apic IDs (so it can support very large systems),
363 and accesses the local apic via MSRs not via mmio.
365 If you don't know what to do here, say N.
368 bool "Enable MPS table" if ACPI || SFI
370 depends on X86_LOCAL_APIC
372 For old smp systems that do not have proper acpi support. Newer systems
373 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
376 bool "Support for big SMP systems with more than 8 CPUs"
377 depends on X86_32 && SMP
379 This option is needed for the systems that have more than 8 CPUs
383 depends on X86_GOLDFISH
386 config X86_EXTENDED_PLATFORM
387 bool "Support for extended (non-PC) x86 platforms"
390 If you disable this option then the kernel will only support
391 standard PC platforms. (which covers the vast majority of
394 If you enable this option then you'll be able to select support
395 for the following (non-PC) 32 bit x86 platforms:
396 Goldfish (Android emulator)
399 SGI 320/540 (Visual Workstation)
400 STA2X11-based (e.g. Northville)
401 Moorestown MID devices
403 If you have one of these systems, or if you want to build a
404 generic distribution kernel, say Y here - otherwise say N.
408 config X86_EXTENDED_PLATFORM
409 bool "Support for extended (non-PC) x86 platforms"
412 If you disable this option then the kernel will only support
413 standard PC platforms. (which covers the vast majority of
416 If you enable this option then you'll be able to select support
417 for the following (non-PC) 64 bit x86 platforms:
422 If you have one of these systems, or if you want to build a
423 generic distribution kernel, say Y here - otherwise say N.
425 # This is an alphabetically sorted list of 64 bit extended platforms
426 # Please maintain the alphabetic order if and when there are additions
428 bool "Numascale NumaChip"
430 depends on X86_EXTENDED_PLATFORM
433 depends on X86_X2APIC
434 depends on PCI_MMCONFIG
436 Adds support for Numascale NumaChip large-SMP systems. Needed to
437 enable more than ~168 cores.
438 If you don't have one of these, you should say N here.
442 select HYPERVISOR_GUEST
444 depends on X86_64 && PCI
445 depends on X86_EXTENDED_PLATFORM
448 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
449 supposed to run on these EM64T-based machines. Only choose this option
450 if you have one of these machines.
453 bool "SGI Ultraviolet"
455 depends on X86_EXTENDED_PLATFORM
457 depends on X86_X2APIC
460 This option is needed in order to support SGI Ultraviolet systems.
461 If you don't have one of these, you should say N here.
463 # Following is an alphabetically sorted list of 32 bit extended platforms
464 # Please maintain the alphabetic order if and when there are additions
467 bool "Goldfish (Virtual Platform)"
468 depends on X86_EXTENDED_PLATFORM
470 Enable support for the Goldfish virtual platform used primarily
471 for Android development. Unless you are building for the Android
472 Goldfish emulator say N here.
475 bool "CE4100 TV platform"
477 depends on PCI_GODIRECT
478 depends on X86_IO_APIC
480 depends on X86_EXTENDED_PLATFORM
481 select X86_REBOOTFIXUPS
483 select OF_EARLY_FLATTREE
485 Select for the Intel CE media processor (CE4100) SOC.
486 This option compiles in support for the CE4100 SOC for settop
487 boxes and media devices.
490 bool "Intel MID platform support"
492 depends on X86_EXTENDED_PLATFORM
493 depends on X86_PLATFORM_DEVICES
496 depends on X86_IO_APIC
502 select MFD_INTEL_MSIC
504 Select to build a kernel capable of supporting Intel MID (Mobile
505 Internet Device) platform systems which do not have the PCI legacy
506 interfaces. If you are building for a PC class system say N here.
508 Intel MID platforms are based on an Intel processor and chipset which
509 consume less power than most of the x86 derivatives.
511 config X86_INTEL_QUARK
512 bool "Intel Quark platform support"
514 depends on X86_EXTENDED_PLATFORM
515 depends on X86_PLATFORM_DEVICES
519 depends on X86_IO_APIC
524 Select to include support for Quark X1000 SoC.
525 Say Y here if you have a Quark based system such as the Arduino
526 compatible Intel Galileo.
528 config X86_INTEL_LPSS
529 bool "Intel Low Power Subsystem Support"
534 Select to build support for Intel Low Power Subsystem such as
535 found on Intel Lynxpoint PCH. Selecting this option enables
536 things like clock tree (common clock framework) and pincontrol
537 which are needed by the LPSS peripheral drivers.
539 config X86_AMD_PLATFORM_DEVICE
540 bool "AMD ACPI2Platform devices support"
545 Select to interpret AMD specific ACPI device to platform device
546 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
547 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
548 implemented under PINCTRL subsystem.
551 tristate "Intel SoC IOSF Sideband support for SoC platforms"
554 This option enables sideband register access support for Intel SoC
555 platforms. On these platforms the IOSF sideband is used in lieu of
556 MSR's for some register accesses, mostly but not limited to thermal
557 and power. Drivers may query the availability of this device to
558 determine if they need the sideband in order to work on these
559 platforms. The sideband is available on the following SoC products.
560 This list is not meant to be exclusive.
565 You should say Y if you are running a kernel on one of these SoC's.
567 config IOSF_MBI_DEBUG
568 bool "Enable IOSF sideband access through debugfs"
569 depends on IOSF_MBI && DEBUG_FS
571 Select this option to expose the IOSF sideband access registers (MCR,
572 MDR, MCRX) through debugfs to write and read register information from
573 different units on the SoC. This is most useful for obtaining device
574 state information for debug and analysis. As this is a general access
575 mechanism, users of this option would have specific knowledge of the
576 device they want to access.
578 If you don't require the option or are in doubt, say N.
581 bool "RDC R-321x SoC"
583 depends on X86_EXTENDED_PLATFORM
585 select X86_REBOOTFIXUPS
587 This option is needed for RDC R-321x system-on-chip, also known
589 If you don't have one of these chips, you should say N here.
591 config X86_32_NON_STANDARD
592 bool "Support non-standard 32-bit SMP architectures"
593 depends on X86_32 && SMP
594 depends on X86_EXTENDED_PLATFORM
596 This option compiles in the bigsmp and STA2X11 default
597 subarchitectures. It is intended for a generic binary
598 kernel. If you select them all, kernel will probe it one by
599 one and will fallback to default.
601 # Alphabetically sorted list of Non standard 32 bit platforms
603 config X86_SUPPORTS_MEMORY_FAILURE
605 # MCE code calls memory_failure():
607 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
608 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
609 depends on X86_64 || !SPARSEMEM
610 select ARCH_SUPPORTS_MEMORY_FAILURE
613 bool "STA2X11 Companion Chip Support"
614 depends on X86_32_NON_STANDARD && PCI
615 select X86_DEV_DMA_OPS
619 select ARCH_REQUIRE_GPIOLIB
622 This adds support for boards based on the STA2X11 IO-Hub,
623 a.k.a. "ConneXt". The chip is used in place of the standard
624 PC chipset, so all "standard" peripherals are missing. If this
625 option is selected the kernel will still be able to boot on
626 standard PC machines.
629 tristate "Eurobraille/Iris poweroff module"
632 The Iris machines from EuroBraille do not have APM or ACPI support
633 to shut themselves down properly. A special I/O sequence is
634 needed to do so, which is what this module does at
637 This is only for Iris machines from EuroBraille.
641 config SCHED_OMIT_FRAME_POINTER
643 prompt "Single-depth WCHAN output"
646 Calculate simpler /proc/<PID>/wchan values. If this option
647 is disabled then wchan values will recurse back to the
648 caller function. This provides more accurate wchan values,
649 at the expense of slightly more scheduling overhead.
651 If in doubt, say "Y".
653 menuconfig HYPERVISOR_GUEST
654 bool "Linux guest support"
656 Say Y here to enable options for running Linux under various hyper-
657 visors. This option enables basic hypervisor detection and platform
660 If you say N, all options in this submenu will be skipped and
661 disabled, and Linux guest support won't be built in.
666 bool "Enable paravirtualization code"
668 This changes the kernel so it can modify itself when it is run
669 under a hypervisor, potentially improving performance significantly
670 over full virtualization. However, when run without a hypervisor
671 the kernel is theoretically slower and slightly larger.
673 config PARAVIRT_DEBUG
674 bool "paravirt-ops debugging"
675 depends on PARAVIRT && DEBUG_KERNEL
677 Enable to debug paravirt_ops internals. Specifically, BUG if
678 a paravirt_op is missing when it is called.
680 config PARAVIRT_SPINLOCKS
681 bool "Paravirtualization layer for spinlocks"
682 depends on PARAVIRT && SMP
683 select UNINLINE_SPIN_UNLOCK if !QUEUED_SPINLOCKS
685 Paravirtualized spinlocks allow a pvops backend to replace the
686 spinlock implementation with something virtualization-friendly
687 (for example, block the virtual CPU rather than spinning).
689 It has a minimal impact on native kernels and gives a nice performance
690 benefit on paravirtualized KVM / Xen kernels.
692 If you are unsure how to answer this question, answer Y.
694 source "arch/x86/xen/Kconfig"
697 bool "KVM Guest support (including kvmclock)"
699 select PARAVIRT_CLOCK
702 This option enables various optimizations for running under the KVM
703 hypervisor. It includes a paravirtualized clock, so that instead
704 of relying on a PIT (or probably other) emulation by the
705 underlying device model, the host provides the guest with
706 timing infrastructure such as time of day, and system time
709 bool "Enable debug information for KVM Guests in debugfs"
710 depends on KVM_GUEST && DEBUG_FS
713 This option enables collection of various statistics for KVM guest.
714 Statistics are displayed in debugfs filesystem. Enabling this option
715 may incur significant overhead.
717 source "arch/x86/lguest/Kconfig"
719 config PARAVIRT_TIME_ACCOUNTING
720 bool "Paravirtual steal time accounting"
724 Select this option to enable fine granularity task steal time
725 accounting. Time spent executing other tasks in parallel with
726 the current vCPU is discounted from the vCPU power. To account for
727 that, there can be a small performance impact.
729 If in doubt, say N here.
731 config PARAVIRT_CLOCK
734 endif #HYPERVISOR_GUEST
739 source "arch/x86/Kconfig.cpu"
743 prompt "HPET Timer Support" if X86_32
745 Use the IA-PC HPET (High Precision Event Timer) to manage
746 time in preference to the PIT and RTC, if a HPET is
748 HPET is the next generation timer replacing legacy 8254s.
749 The HPET provides a stable time base on SMP
750 systems, unlike the TSC, but it is more expensive to access,
751 as it is off-chip. You can find the HPET spec at
752 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
754 You can safely choose Y here. However, HPET will only be
755 activated if the platform and the BIOS support this feature.
756 Otherwise the 8254 will be used for timing services.
758 Choose N to continue using the legacy 8254 timer.
760 config HPET_EMULATE_RTC
762 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
765 def_bool y if X86_INTEL_MID
766 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
768 depends on X86_INTEL_MID && SFI
770 APB timer is the replacement for 8254, HPET on X86 MID platforms.
771 The APBT provides a stable time base on SMP
772 systems, unlike the TSC, but it is more expensive to access,
773 as it is off-chip. APB timers are always running regardless of CPU
774 C states, they are used as per CPU clockevent device when possible.
776 # Mark as expert because too many people got it wrong.
777 # The code disables itself when not needed.
780 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
781 bool "Enable DMI scanning" if EXPERT
783 Enabled scanning of DMI to identify machine quirks. Say Y
784 here unless you have verified that your setup is not
785 affected by entries in the DMI blacklist. Required by PNP
789 bool "Old AMD GART IOMMU support"
791 depends on X86_64 && PCI && AMD_NB
793 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
794 GART based hardware IOMMUs.
796 The GART supports full DMA access for devices with 32-bit access
797 limitations, on systems with more than 3 GB. This is usually needed
798 for USB, sound, many IDE/SATA chipsets and some other devices.
800 Newer systems typically have a modern AMD IOMMU, supported via
801 the CONFIG_AMD_IOMMU=y config option.
803 In normal configurations this driver is only active when needed:
804 there's more than 3 GB of memory and the system contains a
805 32-bit limited device.
810 bool "IBM Calgary IOMMU support"
812 depends on X86_64 && PCI
814 Support for hardware IOMMUs in IBM's xSeries x366 and x460
815 systems. Needed to run systems with more than 3GB of memory
816 properly with 32-bit PCI devices that do not support DAC
817 (Double Address Cycle). Calgary also supports bus level
818 isolation, where all DMAs pass through the IOMMU. This
819 prevents them from going anywhere except their intended
820 destination. This catches hard-to-find kernel bugs and
821 mis-behaving drivers and devices that do not use the DMA-API
822 properly to set up their DMA buffers. The IOMMU can be
823 turned off at boot time with the iommu=off parameter.
824 Normally the kernel will make the right choice by itself.
827 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
829 prompt "Should Calgary be enabled by default?"
830 depends on CALGARY_IOMMU
832 Should Calgary be enabled by default? if you choose 'y', Calgary
833 will be used (if it exists). If you choose 'n', Calgary will not be
834 used even if it exists. If you choose 'n' and would like to use
835 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
838 # need this always selected by IOMMU for the VIA workaround
842 Support for software bounce buffers used on x86-64 systems
843 which don't have a hardware IOMMU. Using this PCI devices
844 which can only access 32-bits of memory can be used on systems
845 with more than 3 GB of memory.
850 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
853 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
854 depends on X86_64 && SMP && DEBUG_KERNEL
855 select CPUMASK_OFFSTACK if !PREEMPT_RT_FULL
857 Enable maximum number of CPUS and NUMA Nodes for this architecture.
861 int "Maximum number of CPUs" if SMP && !MAXSMP
862 range 2 8 if SMP && X86_32 && !X86_BIGSMP
863 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
864 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
866 default "8192" if MAXSMP
867 default "32" if SMP && X86_BIGSMP
868 default "8" if SMP && X86_32
871 This allows you to specify the maximum number of CPUs which this
872 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
873 supported value is 8192, otherwise the maximum value is 512. The
874 minimum value which makes sense is 2.
876 This is purely to save memory - each supported CPU adds
877 approximately eight kilobytes to the kernel image.
880 bool "SMT (Hyperthreading) scheduler support"
883 SMT scheduler support improves the CPU scheduler's decision making
884 when dealing with Intel Pentium 4 chips with HyperThreading at a
885 cost of slightly increased overhead in some places. If unsure say
890 prompt "Multi-core scheduler support"
893 Multi-core scheduler support improves the CPU scheduler's decision
894 making when dealing with multi-core CPU chips at a cost of slightly
895 increased overhead in some places. If unsure say N here.
897 source "kernel/Kconfig.preempt"
901 depends on !SMP && X86_LOCAL_APIC
904 bool "Local APIC support on uniprocessors" if !PCI_MSI
906 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
908 A local APIC (Advanced Programmable Interrupt Controller) is an
909 integrated interrupt controller in the CPU. If you have a single-CPU
910 system which has a processor with a local APIC, you can say Y here to
911 enable and use it. If you say Y here even though your machine doesn't
912 have a local APIC, then the kernel will still run with no slowdown at
913 all. The local APIC supports CPU-generated self-interrupts (timer,
914 performance counters), and the NMI watchdog which detects hard
918 bool "IO-APIC support on uniprocessors"
919 depends on X86_UP_APIC
921 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
922 SMP-capable replacement for PC-style interrupt controllers. Most
923 SMP systems and many recent uniprocessor systems have one.
925 If you have a single-CPU system with an IO-APIC, you can say Y here
926 to use it. If you say Y here even though your machine doesn't have
927 an IO-APIC, then the kernel will still run with no slowdown at all.
929 config X86_LOCAL_APIC
931 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
932 select IRQ_DOMAIN_HIERARCHY
933 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
937 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
939 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
940 bool "Reroute for broken boot IRQs"
941 depends on X86_IO_APIC
943 This option enables a workaround that fixes a source of
944 spurious interrupts. This is recommended when threaded
945 interrupt handling is used on systems where the generation of
946 superfluous "boot interrupts" cannot be disabled.
948 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
949 entry in the chipset's IO-APIC is masked (as, e.g. the RT
950 kernel does during interrupt handling). On chipsets where this
951 boot IRQ generation cannot be disabled, this workaround keeps
952 the original IRQ line masked so that only the equivalent "boot
953 IRQ" is delivered to the CPUs. The workaround also tells the
954 kernel to set up the IRQ handler on the boot IRQ line. In this
955 way only one interrupt is delivered to the kernel. Otherwise
956 the spurious second interrupt may cause the kernel to bring
957 down (vital) interrupt lines.
959 Only affects "broken" chipsets. Interrupt sharing may be
960 increased on these systems.
963 bool "Machine Check / overheating reporting"
964 select GENERIC_ALLOCATOR
967 Machine Check support allows the processor to notify the
968 kernel if it detects a problem (e.g. overheating, data corruption).
969 The action the kernel takes depends on the severity of the problem,
970 ranging from warning messages to halting the machine.
974 prompt "Intel MCE features"
975 depends on X86_MCE && X86_LOCAL_APIC
977 Additional support for intel specific MCE features such as
982 prompt "AMD MCE features"
983 depends on X86_MCE && X86_LOCAL_APIC
985 Additional support for AMD specific MCE features such as
986 the DRAM Error Threshold.
988 config X86_ANCIENT_MCE
989 bool "Support for old Pentium 5 / WinChip machine checks"
990 depends on X86_32 && X86_MCE
992 Include support for machine check handling on old Pentium 5 or WinChip
993 systems. These typically need to be enabled explicitly on the command
996 config X86_MCE_THRESHOLD
997 depends on X86_MCE_AMD || X86_MCE_INTEL
1000 config X86_MCE_INJECT
1002 tristate "Machine check injector support"
1004 Provide support for injecting machine checks for testing purposes.
1005 If you don't know what a machine check is and you don't do kernel
1006 QA it is safe to say n.
1008 config X86_THERMAL_VECTOR
1010 depends on X86_MCE_INTEL
1012 config X86_LEGACY_VM86
1013 bool "Legacy VM86 support"
1017 This option allows user programs to put the CPU into V8086
1018 mode, which is an 80286-era approximation of 16-bit real mode.
1020 Some very old versions of X and/or vbetool require this option
1021 for user mode setting. Similarly, DOSEMU will use it if
1022 available to accelerate real mode DOS programs. However, any
1023 recent version of DOSEMU, X, or vbetool should be fully
1024 functional even without kernel VM86 support, as they will all
1025 fall back to software emulation. Nevertheless, if you are using
1026 a 16-bit DOS program where 16-bit performance matters, vm86
1027 mode might be faster than emulation and you might want to
1030 Note that any app that works on a 64-bit kernel is unlikely to
1031 need this option, as 64-bit kernels don't, and can't, support
1032 V8086 mode. This option is also unrelated to 16-bit protected
1033 mode and is not needed to run most 16-bit programs under Wine.
1035 Enabling this option increases the complexity of the kernel
1036 and slows down exception handling a tiny bit.
1038 If unsure, say N here.
1042 default X86_LEGACY_VM86
1045 bool "Enable support for 16-bit segments" if EXPERT
1047 depends on MODIFY_LDT_SYSCALL
1049 This option is required by programs like Wine to run 16-bit
1050 protected mode legacy code on x86 processors. Disabling
1051 this option saves about 300 bytes on i386, or around 6K text
1052 plus 16K runtime memory on x86-64,
1056 depends on X86_16BIT && X86_32
1060 depends on X86_16BIT && X86_64
1062 config X86_VSYSCALL_EMULATION
1063 bool "Enable vsyscall emulation" if EXPERT
1067 This enables emulation of the legacy vsyscall page. Disabling
1068 it is roughly equivalent to booting with vsyscall=none, except
1069 that it will also disable the helpful warning if a program
1070 tries to use a vsyscall. With this option set to N, offending
1071 programs will just segfault, citing addresses of the form
1074 This option is required by many programs built before 2013, and
1075 care should be used even with newer programs if set to N.
1077 Disabling this option saves about 7K of kernel size and
1078 possibly 4K of additional runtime pagetable memory.
1081 tristate "Toshiba Laptop support"
1084 This adds a driver to safely access the System Management Mode of
1085 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1086 not work on models with a Phoenix BIOS. The System Management Mode
1087 is used to set the BIOS and power saving options on Toshiba portables.
1089 For information on utilities to make use of this driver see the
1090 Toshiba Linux utilities web site at:
1091 <http://www.buzzard.org.uk/toshiba/>.
1093 Say Y if you intend to run this kernel on a Toshiba portable.
1097 tristate "Dell i8k legacy laptop support"
1099 select SENSORS_DELL_SMM
1101 This option enables legacy /proc/i8k userspace interface in hwmon
1102 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1103 temperature and allows controlling fan speeds of Dell laptops via
1104 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1105 it reports also power and hotkey status. For fan speed control is
1106 needed userspace package i8kutils.
1108 Say Y if you intend to run this kernel on old Dell laptops or want to
1109 use userspace package i8kutils.
1112 config X86_REBOOTFIXUPS
1113 bool "Enable X86 board specific fixups for reboot"
1116 This enables chipset and/or board specific fixups to be done
1117 in order to get reboot to work correctly. This is only needed on
1118 some combinations of hardware and BIOS. The symptom, for which
1119 this config is intended, is when reboot ends with a stalled/hung
1122 Currently, the only fixup is for the Geode machines using
1123 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1125 Say Y if you want to enable the fixup. Currently, it's safe to
1126 enable this option even if you don't need it.
1130 bool "CPU microcode loading support"
1132 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1135 If you say Y here, you will be able to update the microcode on
1136 Intel and AMD processors. The Intel support is for the IA32 family,
1137 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1138 AMD support is for families 0x10 and later. You will obviously need
1139 the actual microcode binary data itself which is not shipped with
1142 The preferred method to load microcode from a detached initrd is described
1143 in Documentation/x86/early-microcode.txt. For that you need to enable
1144 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1145 initrd for microcode blobs.
1147 In addition, you can build-in the microcode into the kernel. For that you
1148 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1149 to the CONFIG_EXTRA_FIRMWARE config option.
1151 config MICROCODE_INTEL
1152 bool "Intel microcode loading support"
1153 depends on MICROCODE
1157 This options enables microcode patch loading support for Intel
1160 For the current Intel microcode data package go to
1161 <https://downloadcenter.intel.com> and search for
1162 'Linux Processor Microcode Data File'.
1164 config MICROCODE_AMD
1165 bool "AMD microcode loading support"
1166 depends on MICROCODE
1169 If you select this option, microcode patch loading support for AMD
1170 processors will be enabled.
1172 config MICROCODE_OLD_INTERFACE
1174 depends on MICROCODE
1177 tristate "/dev/cpu/*/msr - Model-specific register support"
1179 This device gives privileged processes access to the x86
1180 Model-Specific Registers (MSRs). It is a character device with
1181 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1182 MSR accesses are directed to a specific CPU on multi-processor
1186 tristate "/dev/cpu/*/cpuid - CPU information support"
1188 This device gives processes access to the x86 CPUID instruction to
1189 be executed on a specific processor. It is a character device
1190 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1194 prompt "High Memory Support"
1201 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1202 However, the address space of 32-bit x86 processors is only 4
1203 Gigabytes large. That means that, if you have a large amount of
1204 physical memory, not all of it can be "permanently mapped" by the
1205 kernel. The physical memory that's not permanently mapped is called
1208 If you are compiling a kernel which will never run on a machine with
1209 more than 1 Gigabyte total physical RAM, answer "off" here (default
1210 choice and suitable for most users). This will result in a "3GB/1GB"
1211 split: 3GB are mapped so that each process sees a 3GB virtual memory
1212 space and the remaining part of the 4GB virtual memory space is used
1213 by the kernel to permanently map as much physical memory as
1216 If the machine has between 1 and 4 Gigabytes physical RAM, then
1219 If more than 4 Gigabytes is used then answer "64GB" here. This
1220 selection turns Intel PAE (Physical Address Extension) mode on.
1221 PAE implements 3-level paging on IA32 processors. PAE is fully
1222 supported by Linux, PAE mode is implemented on all recent Intel
1223 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1224 then the kernel will not boot on CPUs that don't support PAE!
1226 The actual amount of total physical memory will either be
1227 auto detected or can be forced by using a kernel command line option
1228 such as "mem=256M". (Try "man bootparam" or see the documentation of
1229 your boot loader (lilo or loadlin) about how to pass options to the
1230 kernel at boot time.)
1232 If unsure, say "off".
1237 Select this if you have a 32-bit processor and between 1 and 4
1238 gigabytes of physical RAM.
1245 Select this if you have a 32-bit processor and more than 4
1246 gigabytes of physical RAM.
1251 prompt "Memory split" if EXPERT
1255 Select the desired split between kernel and user memory.
1257 If the address range available to the kernel is less than the
1258 physical memory installed, the remaining memory will be available
1259 as "high memory". Accessing high memory is a little more costly
1260 than low memory, as it needs to be mapped into the kernel first.
1261 Note that increasing the kernel address space limits the range
1262 available to user programs, making the address space there
1263 tighter. Selecting anything other than the default 3G/1G split
1264 will also likely make your kernel incompatible with binary-only
1267 If you are not absolutely sure what you are doing, leave this
1271 bool "3G/1G user/kernel split"
1272 config VMSPLIT_3G_OPT
1274 bool "3G/1G user/kernel split (for full 1G low memory)"
1276 bool "2G/2G user/kernel split"
1277 config VMSPLIT_2G_OPT
1279 bool "2G/2G user/kernel split (for full 2G low memory)"
1281 bool "1G/3G user/kernel split"
1286 default 0xB0000000 if VMSPLIT_3G_OPT
1287 default 0x80000000 if VMSPLIT_2G
1288 default 0x78000000 if VMSPLIT_2G_OPT
1289 default 0x40000000 if VMSPLIT_1G
1295 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1298 bool "PAE (Physical Address Extension) Support"
1299 depends on X86_32 && !HIGHMEM4G
1302 PAE is required for NX support, and furthermore enables
1303 larger swapspace support for non-overcommit purposes. It
1304 has the cost of more pagetable lookup overhead, and also
1305 consumes more pagetable space per process.
1307 config ARCH_PHYS_ADDR_T_64BIT
1309 depends on X86_64 || X86_PAE
1311 config ARCH_DMA_ADDR_T_64BIT
1313 depends on X86_64 || HIGHMEM64G
1315 config X86_DIRECT_GBPAGES
1317 depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
1319 Certain kernel features effectively disable kernel
1320 linear 1 GB mappings (even if the CPU otherwise
1321 supports them), so don't confuse the user by printing
1322 that we have them enabled.
1324 # Common NUMA Features
1326 bool "Numa Memory Allocation and Scheduler Support"
1328 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1329 default y if X86_BIGSMP
1331 Enable NUMA (Non Uniform Memory Access) support.
1333 The kernel will try to allocate memory used by a CPU on the
1334 local memory controller of the CPU and add some more
1335 NUMA awareness to the kernel.
1337 For 64-bit this is recommended if the system is Intel Core i7
1338 (or later), AMD Opteron, or EM64T NUMA.
1340 For 32-bit this is only needed if you boot a 32-bit
1341 kernel on a 64-bit NUMA platform.
1343 Otherwise, you should say N.
1347 prompt "Old style AMD Opteron NUMA detection"
1348 depends on X86_64 && NUMA && PCI
1350 Enable AMD NUMA node topology detection. You should say Y here if
1351 you have a multi processor AMD system. This uses an old method to
1352 read the NUMA configuration directly from the builtin Northbridge
1353 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1354 which also takes priority if both are compiled in.
1356 config X86_64_ACPI_NUMA
1358 prompt "ACPI NUMA detection"
1359 depends on X86_64 && NUMA && ACPI && PCI
1362 Enable ACPI SRAT based node topology detection.
1364 # Some NUMA nodes have memory ranges that span
1365 # other nodes. Even though a pfn is valid and
1366 # between a node's start and end pfns, it may not
1367 # reside on that node. See memmap_init_zone()
1369 config NODES_SPAN_OTHER_NODES
1371 depends on X86_64_ACPI_NUMA
1374 bool "NUMA emulation"
1377 Enable NUMA emulation. A flat machine will be split
1378 into virtual nodes when booted with "numa=fake=N", where N is the
1379 number of nodes. This is only useful for debugging.
1382 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1384 default "10" if MAXSMP
1385 default "6" if X86_64
1387 depends on NEED_MULTIPLE_NODES
1389 Specify the maximum number of NUMA Nodes available on the target
1390 system. Increases memory reserved to accommodate various tables.
1392 config ARCH_HAVE_MEMORY_PRESENT
1394 depends on X86_32 && DISCONTIGMEM
1396 config NEED_NODE_MEMMAP_SIZE
1398 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1400 config ARCH_FLATMEM_ENABLE
1402 depends on X86_32 && !NUMA
1404 config ARCH_DISCONTIGMEM_ENABLE
1406 depends on NUMA && X86_32
1408 config ARCH_DISCONTIGMEM_DEFAULT
1410 depends on NUMA && X86_32
1412 config ARCH_SPARSEMEM_ENABLE
1414 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1415 select SPARSEMEM_STATIC if X86_32
1416 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1418 config ARCH_SPARSEMEM_DEFAULT
1422 config ARCH_SELECT_MEMORY_MODEL
1424 depends on ARCH_SPARSEMEM_ENABLE
1426 config ARCH_MEMORY_PROBE
1427 bool "Enable sysfs memory/probe interface"
1428 depends on X86_64 && MEMORY_HOTPLUG
1430 This option enables a sysfs memory/probe interface for testing.
1431 See Documentation/memory-hotplug.txt for more information.
1432 If you are unsure how to answer this question, answer N.
1434 config ARCH_PROC_KCORE_TEXT
1436 depends on X86_64 && PROC_KCORE
1438 config ILLEGAL_POINTER_VALUE
1441 default 0xdead000000000000 if X86_64
1445 config X86_PMEM_LEGACY_DEVICE
1448 config X86_PMEM_LEGACY
1449 tristate "Support non-standard NVDIMMs and ADR protected memory"
1450 depends on PHYS_ADDR_T_64BIT
1452 select X86_PMEM_LEGACY_DEVICE
1455 Treat memory marked using the non-standard e820 type of 12 as used
1456 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1457 The kernel will offer these regions to the 'pmem' driver so
1458 they can be used for persistent storage.
1463 bool "Allocate 3rd-level pagetables from highmem"
1466 The VM uses one page table entry for each page of physical memory.
1467 For systems with a lot of RAM, this can be wasteful of precious
1468 low memory. Setting this option will put user-space page table
1469 entries in high memory.
1471 config X86_CHECK_BIOS_CORRUPTION
1472 bool "Check for low memory corruption"
1474 Periodically check for memory corruption in low memory, which
1475 is suspected to be caused by BIOS. Even when enabled in the
1476 configuration, it is disabled at runtime. Enable it by
1477 setting "memory_corruption_check=1" on the kernel command
1478 line. By default it scans the low 64k of memory every 60
1479 seconds; see the memory_corruption_check_size and
1480 memory_corruption_check_period parameters in
1481 Documentation/kernel-parameters.txt to adjust this.
1483 When enabled with the default parameters, this option has
1484 almost no overhead, as it reserves a relatively small amount
1485 of memory and scans it infrequently. It both detects corruption
1486 and prevents it from affecting the running system.
1488 It is, however, intended as a diagnostic tool; if repeatable
1489 BIOS-originated corruption always affects the same memory,
1490 you can use memmap= to prevent the kernel from using that
1493 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1494 bool "Set the default setting of memory_corruption_check"
1495 depends on X86_CHECK_BIOS_CORRUPTION
1498 Set whether the default state of memory_corruption_check is
1501 config X86_RESERVE_LOW
1502 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1506 Specify the amount of low memory to reserve for the BIOS.
1508 The first page contains BIOS data structures that the kernel
1509 must not use, so that page must always be reserved.
1511 By default we reserve the first 64K of physical RAM, as a
1512 number of BIOSes are known to corrupt that memory range
1513 during events such as suspend/resume or monitor cable
1514 insertion, so it must not be used by the kernel.
1516 You can set this to 4 if you are absolutely sure that you
1517 trust the BIOS to get all its memory reservations and usages
1518 right. If you know your BIOS have problems beyond the
1519 default 64K area, you can set this to 640 to avoid using the
1520 entire low memory range.
1522 If you have doubts about the BIOS (e.g. suspend/resume does
1523 not work or there's kernel crashes after certain hardware
1524 hotplug events) then you might want to enable
1525 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1526 typical corruption patterns.
1528 Leave this to the default value of 64 if you are unsure.
1530 config MATH_EMULATION
1532 depends on MODIFY_LDT_SYSCALL
1533 prompt "Math emulation" if X86_32
1535 Linux can emulate a math coprocessor (used for floating point
1536 operations) if you don't have one. 486DX and Pentium processors have
1537 a math coprocessor built in, 486SX and 386 do not, unless you added
1538 a 487DX or 387, respectively. (The messages during boot time can
1539 give you some hints here ["man dmesg"].) Everyone needs either a
1540 coprocessor or this emulation.
1542 If you don't have a math coprocessor, you need to say Y here; if you
1543 say Y here even though you have a coprocessor, the coprocessor will
1544 be used nevertheless. (This behavior can be changed with the kernel
1545 command line option "no387", which comes handy if your coprocessor
1546 is broken. Try "man bootparam" or see the documentation of your boot
1547 loader (lilo or loadlin) about how to pass options to the kernel at
1548 boot time.) This means that it is a good idea to say Y here if you
1549 intend to use this kernel on different machines.
1551 More information about the internals of the Linux math coprocessor
1552 emulation can be found in <file:arch/x86/math-emu/README>.
1554 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1555 kernel, it won't hurt.
1559 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1561 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1562 the Memory Type Range Registers (MTRRs) may be used to control
1563 processor access to memory ranges. This is most useful if you have
1564 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1565 allows bus write transfers to be combined into a larger transfer
1566 before bursting over the PCI/AGP bus. This can increase performance
1567 of image write operations 2.5 times or more. Saying Y here creates a
1568 /proc/mtrr file which may be used to manipulate your processor's
1569 MTRRs. Typically the X server should use this.
1571 This code has a reasonably generic interface so that similar
1572 control registers on other processors can be easily supported
1575 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1576 Registers (ARRs) which provide a similar functionality to MTRRs. For
1577 these, the ARRs are used to emulate the MTRRs.
1578 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1579 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1580 write-combining. All of these processors are supported by this code
1581 and it makes sense to say Y here if you have one of them.
1583 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1584 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1585 can lead to all sorts of problems, so it's good to say Y here.
1587 You can safely say Y even if your machine doesn't have MTRRs, you'll
1588 just add about 9 KB to your kernel.
1590 See <file:Documentation/x86/mtrr.txt> for more information.
1592 config MTRR_SANITIZER
1594 prompt "MTRR cleanup support"
1597 Convert MTRR layout from continuous to discrete, so X drivers can
1598 add writeback entries.
1600 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1601 The largest mtrr entry size for a continuous block can be set with
1606 config MTRR_SANITIZER_ENABLE_DEFAULT
1607 int "MTRR cleanup enable value (0-1)"
1610 depends on MTRR_SANITIZER
1612 Enable mtrr cleanup default value
1614 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1615 int "MTRR cleanup spare reg num (0-7)"
1618 depends on MTRR_SANITIZER
1620 mtrr cleanup spare entries default, it can be changed via
1621 mtrr_spare_reg_nr=N on the kernel command line.
1625 prompt "x86 PAT support" if EXPERT
1628 Use PAT attributes to setup page level cache control.
1630 PATs are the modern equivalents of MTRRs and are much more
1631 flexible than MTRRs.
1633 Say N here if you see bootup problems (boot crash, boot hang,
1634 spontaneous reboots) or a non-working video driver.
1638 config ARCH_USES_PG_UNCACHED
1644 prompt "x86 architectural random number generator" if EXPERT
1646 Enable the x86 architectural RDRAND instruction
1647 (Intel Bull Mountain technology) to generate random numbers.
1648 If supported, this is a high bandwidth, cryptographically
1649 secure hardware random number generator.
1653 prompt "Supervisor Mode Access Prevention" if EXPERT
1655 Supervisor Mode Access Prevention (SMAP) is a security
1656 feature in newer Intel processors. There is a small
1657 performance cost if this enabled and turned on; there is
1658 also a small increase in the kernel size if this is enabled.
1662 config X86_INTEL_MPX
1663 prompt "Intel MPX (Memory Protection Extensions)"
1665 depends on CPU_SUP_INTEL
1667 MPX provides hardware features that can be used in
1668 conjunction with compiler-instrumented code to check
1669 memory references. It is designed to detect buffer
1670 overflow or underflow bugs.
1672 This option enables running applications which are
1673 instrumented or otherwise use MPX. It does not use MPX
1674 itself inside the kernel or to protect the kernel
1675 against bad memory references.
1677 Enabling this option will make the kernel larger:
1678 ~8k of kernel text and 36 bytes of data on a 64-bit
1679 defconfig. It adds a long to the 'mm_struct' which
1680 will increase the kernel memory overhead of each
1681 process and adds some branches to paths used during
1682 exec() and munmap().
1684 For details, see Documentation/x86/intel_mpx.txt
1689 bool "EFI runtime service support"
1692 select EFI_RUNTIME_WRAPPERS
1694 This enables the kernel to use EFI runtime services that are
1695 available (such as the EFI variable services).
1697 This option is only useful on systems that have EFI firmware.
1698 In addition, you should use the latest ELILO loader available
1699 at <http://elilo.sourceforge.net> in order to take advantage
1700 of EFI runtime services. However, even with this option, the
1701 resultant kernel should continue to boot on existing non-EFI
1705 bool "EFI stub support"
1706 depends on EFI && !X86_USE_3DNOW
1709 This kernel feature allows a bzImage to be loaded directly
1710 by EFI firmware without the use of a bootloader.
1712 See Documentation/efi-stub.txt for more information.
1715 bool "EFI mixed-mode support"
1716 depends on EFI_STUB && X86_64
1718 Enabling this feature allows a 64-bit kernel to be booted
1719 on a 32-bit firmware, provided that your CPU supports 64-bit
1722 Note that it is not possible to boot a mixed-mode enabled
1723 kernel via the EFI boot stub - a bootloader that supports
1724 the EFI handover protocol must be used.
1730 prompt "Enable seccomp to safely compute untrusted bytecode"
1732 This kernel feature is useful for number crunching applications
1733 that may need to compute untrusted bytecode during their
1734 execution. By using pipes or other transports made available to
1735 the process as file descriptors supporting the read/write
1736 syscalls, it's possible to isolate those applications in
1737 their own address space using seccomp. Once seccomp is
1738 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1739 and the task is only allowed to execute a few safe syscalls
1740 defined by each seccomp mode.
1742 If unsure, say Y. Only embedded should say N here.
1744 source kernel/Kconfig.hz
1747 bool "kexec system call"
1750 kexec is a system call that implements the ability to shutdown your
1751 current kernel, and to start another kernel. It is like a reboot
1752 but it is independent of the system firmware. And like a reboot
1753 you can start any kernel with it, not just Linux.
1755 The name comes from the similarity to the exec system call.
1757 It is an ongoing process to be certain the hardware in a machine
1758 is properly shutdown, so do not be surprised if this code does not
1759 initially work for you. As of this writing the exact hardware
1760 interface is strongly in flux, so no good recommendation can be
1764 bool "kexec file based system call"
1769 depends on CRYPTO_SHA256=y
1771 This is new version of kexec system call. This system call is
1772 file based and takes file descriptors as system call argument
1773 for kernel and initramfs as opposed to list of segments as
1774 accepted by previous system call.
1776 config KEXEC_VERIFY_SIG
1777 bool "Verify kernel signature during kexec_file_load() syscall"
1778 depends on KEXEC_FILE
1780 This option makes kernel signature verification mandatory for
1781 the kexec_file_load() syscall.
1783 In addition to that option, you need to enable signature
1784 verification for the corresponding kernel image type being
1785 loaded in order for this to work.
1787 config KEXEC_BZIMAGE_VERIFY_SIG
1788 bool "Enable bzImage signature verification support"
1789 depends on KEXEC_VERIFY_SIG
1790 depends on SIGNED_PE_FILE_VERIFICATION
1791 select SYSTEM_TRUSTED_KEYRING
1793 Enable bzImage signature verification support.
1796 bool "kernel crash dumps"
1797 depends on X86_64 || (X86_32 && HIGHMEM)
1799 Generate crash dump after being started by kexec.
1800 This should be normally only set in special crash dump kernels
1801 which are loaded in the main kernel with kexec-tools into
1802 a specially reserved region and then later executed after
1803 a crash by kdump/kexec. The crash dump kernel must be compiled
1804 to a memory address not used by the main kernel or BIOS using
1805 PHYSICAL_START, or it must be built as a relocatable image
1806 (CONFIG_RELOCATABLE=y).
1807 For more details see Documentation/kdump/kdump.txt
1811 depends on KEXEC && HIBERNATION
1813 Jump between original kernel and kexeced kernel and invoke
1814 code in physical address mode via KEXEC
1816 config PHYSICAL_START
1817 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1820 This gives the physical address where the kernel is loaded.
1822 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1823 bzImage will decompress itself to above physical address and
1824 run from there. Otherwise, bzImage will run from the address where
1825 it has been loaded by the boot loader and will ignore above physical
1828 In normal kdump cases one does not have to set/change this option
1829 as now bzImage can be compiled as a completely relocatable image
1830 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1831 address. This option is mainly useful for the folks who don't want
1832 to use a bzImage for capturing the crash dump and want to use a
1833 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1834 to be specifically compiled to run from a specific memory area
1835 (normally a reserved region) and this option comes handy.
1837 So if you are using bzImage for capturing the crash dump,
1838 leave the value here unchanged to 0x1000000 and set
1839 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1840 for capturing the crash dump change this value to start of
1841 the reserved region. In other words, it can be set based on
1842 the "X" value as specified in the "crashkernel=YM@XM"
1843 command line boot parameter passed to the panic-ed
1844 kernel. Please take a look at Documentation/kdump/kdump.txt
1845 for more details about crash dumps.
1847 Usage of bzImage for capturing the crash dump is recommended as
1848 one does not have to build two kernels. Same kernel can be used
1849 as production kernel and capture kernel. Above option should have
1850 gone away after relocatable bzImage support is introduced. But it
1851 is present because there are users out there who continue to use
1852 vmlinux for dump capture. This option should go away down the
1855 Don't change this unless you know what you are doing.
1858 bool "Build a relocatable kernel"
1861 This builds a kernel image that retains relocation information
1862 so it can be loaded someplace besides the default 1MB.
1863 The relocations tend to make the kernel binary about 10% larger,
1864 but are discarded at runtime.
1866 One use is for the kexec on panic case where the recovery kernel
1867 must live at a different physical address than the primary
1870 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1871 it has been loaded at and the compile time physical address
1872 (CONFIG_PHYSICAL_START) is used as the minimum location.
1874 config RANDOMIZE_BASE
1875 bool "Randomize the address of the kernel image"
1876 depends on RELOCATABLE
1879 Randomizes the physical and virtual address at which the
1880 kernel image is decompressed, as a security feature that
1881 deters exploit attempts relying on knowledge of the location
1882 of kernel internals.
1884 Entropy is generated using the RDRAND instruction if it is
1885 supported. If RDTSC is supported, it is used as well. If
1886 neither RDRAND nor RDTSC are supported, then randomness is
1887 read from the i8254 timer.
1889 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1890 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1891 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1892 minimum of 2MiB, only 10 bits of entropy is theoretically
1893 possible. At best, due to page table layouts, 64-bit can use
1894 9 bits of entropy and 32-bit uses 8 bits.
1898 config RANDOMIZE_BASE_MAX_OFFSET
1899 hex "Maximum kASLR offset allowed" if EXPERT
1900 depends on RANDOMIZE_BASE
1901 range 0x0 0x20000000 if X86_32
1902 default "0x20000000" if X86_32
1903 range 0x0 0x40000000 if X86_64
1904 default "0x40000000" if X86_64
1906 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1907 memory is used to determine the maximal offset in bytes that will
1908 be applied to the kernel when kernel Address Space Layout
1909 Randomization (kASLR) is active. This must be a multiple of
1912 On 32-bit this is limited to 512MiB by page table layouts. The
1915 On 64-bit this is limited by how the kernel fixmap page table is
1916 positioned, so this cannot be larger than 1GiB currently. Without
1917 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1918 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1919 modules area will shrink to compensate, up to the current maximum
1920 1GiB to 1GiB split. The default is 1GiB.
1922 If unsure, leave at the default value.
1924 # Relocation on x86 needs some additional build support
1925 config X86_NEED_RELOCS
1927 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1929 config PHYSICAL_ALIGN
1930 hex "Alignment value to which kernel should be aligned"
1932 range 0x2000 0x1000000 if X86_32
1933 range 0x200000 0x1000000 if X86_64
1935 This value puts the alignment restrictions on physical address
1936 where kernel is loaded and run from. Kernel is compiled for an
1937 address which meets above alignment restriction.
1939 If bootloader loads the kernel at a non-aligned address and
1940 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1941 address aligned to above value and run from there.
1943 If bootloader loads the kernel at a non-aligned address and
1944 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1945 load address and decompress itself to the address it has been
1946 compiled for and run from there. The address for which kernel is
1947 compiled already meets above alignment restrictions. Hence the
1948 end result is that kernel runs from a physical address meeting
1949 above alignment restrictions.
1951 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1952 this value must be a multiple of 0x200000.
1954 Don't change this unless you know what you are doing.
1957 bool "Support for hot-pluggable CPUs"
1960 Say Y here to allow turning CPUs off and on. CPUs can be
1961 controlled through /sys/devices/system/cpu.
1962 ( Note: power management support will enable this option
1963 automatically on SMP systems. )
1964 Say N if you want to disable CPU hotplug.
1966 config BOOTPARAM_HOTPLUG_CPU0
1967 bool "Set default setting of cpu0_hotpluggable"
1969 depends on HOTPLUG_CPU
1971 Set whether default state of cpu0_hotpluggable is on or off.
1973 Say Y here to enable CPU0 hotplug by default. If this switch
1974 is turned on, there is no need to give cpu0_hotplug kernel
1975 parameter and the CPU0 hotplug feature is enabled by default.
1977 Please note: there are two known CPU0 dependencies if you want
1978 to enable the CPU0 hotplug feature either by this switch or by
1979 cpu0_hotplug kernel parameter.
1981 First, resume from hibernate or suspend always starts from CPU0.
1982 So hibernate and suspend are prevented if CPU0 is offline.
1984 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1985 offline if any interrupt can not migrate out of CPU0. There may
1986 be other CPU0 dependencies.
1988 Please make sure the dependencies are under your control before
1989 you enable this feature.
1991 Say N if you don't want to enable CPU0 hotplug feature by default.
1992 You still can enable the CPU0 hotplug feature at boot by kernel
1993 parameter cpu0_hotplug.
1995 config DEBUG_HOTPLUG_CPU0
1997 prompt "Debug CPU0 hotplug"
1998 depends on HOTPLUG_CPU
2000 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2001 soon as possible and boots up userspace with CPU0 offlined. User
2002 can online CPU0 back after boot time.
2004 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2005 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2006 compilation or giving cpu0_hotplug kernel parameter at boot.
2012 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2013 depends on X86_32 || IA32_EMULATION
2015 Certain buggy versions of glibc will crash if they are
2016 presented with a 32-bit vDSO that is not mapped at the address
2017 indicated in its segment table.
2019 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2020 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2021 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2022 the only released version with the bug, but OpenSUSE 9
2023 contains a buggy "glibc 2.3.2".
2025 The symptom of the bug is that everything crashes on startup, saying:
2026 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2028 Saying Y here changes the default value of the vdso32 boot
2029 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2030 This works around the glibc bug but hurts performance.
2032 If unsure, say N: if you are compiling your own kernel, you
2033 are unlikely to be using a buggy version of glibc.
2036 prompt "vsyscall table for legacy applications"
2038 default LEGACY_VSYSCALL_EMULATE
2040 Legacy user code that does not know how to find the vDSO expects
2041 to be able to issue three syscalls by calling fixed addresses in
2042 kernel space. Since this location is not randomized with ASLR,
2043 it can be used to assist security vulnerability exploitation.
2045 This setting can be changed at boot time via the kernel command
2046 line parameter vsyscall=[native|emulate|none].
2048 On a system with recent enough glibc (2.14 or newer) and no
2049 static binaries, you can say None without a performance penalty
2050 to improve security.
2052 If unsure, select "Emulate".
2054 config LEGACY_VSYSCALL_NATIVE
2057 Actual executable code is located in the fixed vsyscall
2058 address mapping, implementing time() efficiently. Since
2059 this makes the mapping executable, it can be used during
2060 security vulnerability exploitation (traditionally as
2061 ROP gadgets). This configuration is not recommended.
2063 config LEGACY_VSYSCALL_EMULATE
2066 The kernel traps and emulates calls into the fixed
2067 vsyscall address mapping. This makes the mapping
2068 non-executable, but it still contains known contents,
2069 which could be used in certain rare security vulnerability
2070 exploits. This configuration is recommended when userspace
2071 still uses the vsyscall area.
2073 config LEGACY_VSYSCALL_NONE
2076 There will be no vsyscall mapping at all. This will
2077 eliminate any risk of ASLR bypass due to the vsyscall
2078 fixed address mapping. Attempts to use the vsyscalls
2079 will be reported to dmesg, so that either old or
2080 malicious userspace programs can be identified.
2085 bool "Built-in kernel command line"
2087 Allow for specifying boot arguments to the kernel at
2088 build time. On some systems (e.g. embedded ones), it is
2089 necessary or convenient to provide some or all of the
2090 kernel boot arguments with the kernel itself (that is,
2091 to not rely on the boot loader to provide them.)
2093 To compile command line arguments into the kernel,
2094 set this option to 'Y', then fill in the
2095 boot arguments in CONFIG_CMDLINE.
2097 Systems with fully functional boot loaders (i.e. non-embedded)
2098 should leave this option set to 'N'.
2101 string "Built-in kernel command string"
2102 depends on CMDLINE_BOOL
2105 Enter arguments here that should be compiled into the kernel
2106 image and used at boot time. If the boot loader provides a
2107 command line at boot time, it is appended to this string to
2108 form the full kernel command line, when the system boots.
2110 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2111 change this behavior.
2113 In most cases, the command line (whether built-in or provided
2114 by the boot loader) should specify the device for the root
2117 config CMDLINE_OVERRIDE
2118 bool "Built-in command line overrides boot loader arguments"
2119 depends on CMDLINE_BOOL
2121 Set this option to 'Y' to have the kernel ignore the boot loader
2122 command line, and use ONLY the built-in command line.
2124 This is used to work around broken boot loaders. This should
2125 be set to 'N' under normal conditions.
2127 config MODIFY_LDT_SYSCALL
2128 bool "Enable the LDT (local descriptor table)" if EXPERT
2131 Linux can allow user programs to install a per-process x86
2132 Local Descriptor Table (LDT) using the modify_ldt(2) system
2133 call. This is required to run 16-bit or segmented code such as
2134 DOSEMU or some Wine programs. It is also used by some very old
2135 threading libraries.
2137 Enabling this feature adds a small amount of overhead to
2138 context switches and increases the low-level kernel attack
2139 surface. Disabling it removes the modify_ldt(2) system call.
2141 Saying 'N' here may make sense for embedded or server kernels.
2143 source "kernel/livepatch/Kconfig"
2147 config ARCH_ENABLE_MEMORY_HOTPLUG
2149 depends on X86_64 || (X86_32 && HIGHMEM)
2151 config ARCH_ENABLE_MEMORY_HOTREMOVE
2153 depends on MEMORY_HOTPLUG
2155 config USE_PERCPU_NUMA_NODE_ID
2159 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2161 depends on X86_64 || X86_PAE
2163 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2165 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2167 menu "Power management and ACPI options"
2169 config ARCH_HIBERNATION_HEADER
2171 depends on X86_64 && HIBERNATION
2173 source "kernel/power/Kconfig"
2175 source "drivers/acpi/Kconfig"
2177 source "drivers/sfi/Kconfig"
2184 tristate "APM (Advanced Power Management) BIOS support"
2185 depends on X86_32 && PM_SLEEP
2187 APM is a BIOS specification for saving power using several different
2188 techniques. This is mostly useful for battery powered laptops with
2189 APM compliant BIOSes. If you say Y here, the system time will be
2190 reset after a RESUME operation, the /proc/apm device will provide
2191 battery status information, and user-space programs will receive
2192 notification of APM "events" (e.g. battery status change).
2194 If you select "Y" here, you can disable actual use of the APM
2195 BIOS by passing the "apm=off" option to the kernel at boot time.
2197 Note that the APM support is almost completely disabled for
2198 machines with more than one CPU.
2200 In order to use APM, you will need supporting software. For location
2201 and more information, read <file:Documentation/power/apm-acpi.txt>
2202 and the Battery Powered Linux mini-HOWTO, available from
2203 <http://www.tldp.org/docs.html#howto>.
2205 This driver does not spin down disk drives (see the hdparm(8)
2206 manpage ("man 8 hdparm") for that), and it doesn't turn off
2207 VESA-compliant "green" monitors.
2209 This driver does not support the TI 4000M TravelMate and the ACER
2210 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2211 desktop machines also don't have compliant BIOSes, and this driver
2212 may cause those machines to panic during the boot phase.
2214 Generally, if you don't have a battery in your machine, there isn't
2215 much point in using this driver and you should say N. If you get
2216 random kernel OOPSes or reboots that don't seem to be related to
2217 anything, try disabling/enabling this option (or disabling/enabling
2220 Some other things you should try when experiencing seemingly random,
2223 1) make sure that you have enough swap space and that it is
2225 2) pass the "no-hlt" option to the kernel
2226 3) switch on floating point emulation in the kernel and pass
2227 the "no387" option to the kernel
2228 4) pass the "floppy=nodma" option to the kernel
2229 5) pass the "mem=4M" option to the kernel (thereby disabling
2230 all but the first 4 MB of RAM)
2231 6) make sure that the CPU is not over clocked.
2232 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2233 8) disable the cache from your BIOS settings
2234 9) install a fan for the video card or exchange video RAM
2235 10) install a better fan for the CPU
2236 11) exchange RAM chips
2237 12) exchange the motherboard.
2239 To compile this driver as a module, choose M here: the
2240 module will be called apm.
2244 config APM_IGNORE_USER_SUSPEND
2245 bool "Ignore USER SUSPEND"
2247 This option will ignore USER SUSPEND requests. On machines with a
2248 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2249 series notebooks, it is necessary to say Y because of a BIOS bug.
2251 config APM_DO_ENABLE
2252 bool "Enable PM at boot time"
2254 Enable APM features at boot time. From page 36 of the APM BIOS
2255 specification: "When disabled, the APM BIOS does not automatically
2256 power manage devices, enter the Standby State, enter the Suspend
2257 State, or take power saving steps in response to CPU Idle calls."
2258 This driver will make CPU Idle calls when Linux is idle (unless this
2259 feature is turned off -- see "Do CPU IDLE calls", below). This
2260 should always save battery power, but more complicated APM features
2261 will be dependent on your BIOS implementation. You may need to turn
2262 this option off if your computer hangs at boot time when using APM
2263 support, or if it beeps continuously instead of suspending. Turn
2264 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2265 T400CDT. This is off by default since most machines do fine without
2270 bool "Make CPU Idle calls when idle"
2272 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2273 On some machines, this can activate improved power savings, such as
2274 a slowed CPU clock rate, when the machine is idle. These idle calls
2275 are made after the idle loop has run for some length of time (e.g.,
2276 333 mS). On some machines, this will cause a hang at boot time or
2277 whenever the CPU becomes idle. (On machines with more than one CPU,
2278 this option does nothing.)
2280 config APM_DISPLAY_BLANK
2281 bool "Enable console blanking using APM"
2283 Enable console blanking using the APM. Some laptops can use this to
2284 turn off the LCD backlight when the screen blanker of the Linux
2285 virtual console blanks the screen. Note that this is only used by
2286 the virtual console screen blanker, and won't turn off the backlight
2287 when using the X Window system. This also doesn't have anything to
2288 do with your VESA-compliant power-saving monitor. Further, this
2289 option doesn't work for all laptops -- it might not turn off your
2290 backlight at all, or it might print a lot of errors to the console,
2291 especially if you are using gpm.
2293 config APM_ALLOW_INTS
2294 bool "Allow interrupts during APM BIOS calls"
2296 Normally we disable external interrupts while we are making calls to
2297 the APM BIOS as a measure to lessen the effects of a badly behaving
2298 BIOS implementation. The BIOS should reenable interrupts if it
2299 needs to. Unfortunately, some BIOSes do not -- especially those in
2300 many of the newer IBM Thinkpads. If you experience hangs when you
2301 suspend, try setting this to Y. Otherwise, say N.
2305 source "drivers/cpufreq/Kconfig"
2307 source "drivers/cpuidle/Kconfig"
2309 source "drivers/idle/Kconfig"
2314 menu "Bus options (PCI etc.)"
2320 Find out whether you have a PCI motherboard. PCI is the name of a
2321 bus system, i.e. the way the CPU talks to the other stuff inside
2322 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2323 VESA. If you have PCI, say Y, otherwise N.
2326 prompt "PCI access mode"
2327 depends on X86_32 && PCI
2330 On PCI systems, the BIOS can be used to detect the PCI devices and
2331 determine their configuration. However, some old PCI motherboards
2332 have BIOS bugs and may crash if this is done. Also, some embedded
2333 PCI-based systems don't have any BIOS at all. Linux can also try to
2334 detect the PCI hardware directly without using the BIOS.
2336 With this option, you can specify how Linux should detect the
2337 PCI devices. If you choose "BIOS", the BIOS will be used,
2338 if you choose "Direct", the BIOS won't be used, and if you
2339 choose "MMConfig", then PCI Express MMCONFIG will be used.
2340 If you choose "Any", the kernel will try MMCONFIG, then the
2341 direct access method and falls back to the BIOS if that doesn't
2342 work. If unsure, go with the default, which is "Any".
2347 config PCI_GOMMCONFIG
2364 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2366 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2369 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2373 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2377 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2381 depends on PCI && XEN
2389 bool "Support mmconfig PCI config space access"
2390 depends on X86_64 && PCI && ACPI
2392 config PCI_CNB20LE_QUIRK
2393 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2396 Read the PCI windows out of the CNB20LE host bridge. This allows
2397 PCI hotplug to work on systems with the CNB20LE chipset which do
2400 There's no public spec for this chipset, and this functionality
2401 is known to be incomplete.
2403 You should say N unless you know you need this.
2405 source "drivers/pci/pcie/Kconfig"
2407 source "drivers/pci/Kconfig"
2409 # x86_64 have no ISA slots, but can have ISA-style DMA.
2411 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2414 Enables ISA-style DMA support for devices requiring such controllers.
2422 Find out whether you have ISA slots on your motherboard. ISA is the
2423 name of a bus system, i.e. the way the CPU talks to the other stuff
2424 inside your box. Other bus systems are PCI, EISA, MicroChannel
2425 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2426 newer boards don't support it. If you have ISA, say Y, otherwise N.
2432 The Extended Industry Standard Architecture (EISA) bus was
2433 developed as an open alternative to the IBM MicroChannel bus.
2435 The EISA bus provided some of the features of the IBM MicroChannel
2436 bus while maintaining backward compatibility with cards made for
2437 the older ISA bus. The EISA bus saw limited use between 1988 and
2438 1995 when it was made obsolete by the PCI bus.
2440 Say Y here if you are building a kernel for an EISA-based machine.
2444 source "drivers/eisa/Kconfig"
2447 tristate "NatSemi SCx200 support"
2449 This provides basic support for National Semiconductor's
2450 (now AMD's) Geode processors. The driver probes for the
2451 PCI-IDs of several on-chip devices, so its a good dependency
2452 for other scx200_* drivers.
2454 If compiled as a module, the driver is named scx200.
2456 config SCx200HR_TIMER
2457 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2461 This driver provides a clocksource built upon the on-chip
2462 27MHz high-resolution timer. Its also a workaround for
2463 NSC Geode SC-1100's buggy TSC, which loses time when the
2464 processor goes idle (as is done by the scheduler). The
2465 other workaround is idle=poll boot option.
2468 bool "One Laptop Per Child support"
2475 Add support for detecting the unique features of the OLPC
2479 bool "OLPC XO-1 Power Management"
2480 depends on OLPC && MFD_CS5535 && PM_SLEEP
2483 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2486 bool "OLPC XO-1 Real Time Clock"
2487 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2489 Add support for the XO-1 real time clock, which can be used as a
2490 programmable wakeup source.
2493 bool "OLPC XO-1 SCI extras"
2494 depends on OLPC && OLPC_XO1_PM
2500 Add support for SCI-based features of the OLPC XO-1 laptop:
2501 - EC-driven system wakeups
2505 - AC adapter status updates
2506 - Battery status updates
2508 config OLPC_XO15_SCI
2509 bool "OLPC XO-1.5 SCI extras"
2510 depends on OLPC && ACPI
2513 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2514 - EC-driven system wakeups
2515 - AC adapter status updates
2516 - Battery status updates
2519 bool "PCEngines ALIX System Support (LED setup)"
2522 This option enables system support for the PCEngines ALIX.
2523 At present this just sets up LEDs for GPIO control on
2524 ALIX2/3/6 boards. However, other system specific setup should
2527 Note: You must still enable the drivers for GPIO and LED support
2528 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2530 Note: You have to set alix.force=1 for boards with Award BIOS.
2533 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2536 This option enables system support for the Soekris Engineering net5501.
2539 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2543 This option enables system support for the Traverse Technologies GEOS.
2546 bool "Technologic Systems TS-5500 platform support"
2548 select CHECK_SIGNATURE
2552 This option enables system support for the Technologic Systems TS-5500.
2558 depends on CPU_SUP_AMD && PCI
2560 source "drivers/pcmcia/Kconfig"
2562 source "drivers/pci/hotplug/Kconfig"
2565 tristate "RapidIO support"
2569 If enabled this option will include drivers and the core
2570 infrastructure code to support RapidIO interconnect devices.
2572 source "drivers/rapidio/Kconfig"
2575 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2577 Firmwares often provide initial graphics framebuffers so the BIOS,
2578 bootloader or kernel can show basic video-output during boot for
2579 user-guidance and debugging. Historically, x86 used the VESA BIOS
2580 Extensions and EFI-framebuffers for this, which are mostly limited
2582 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2583 framebuffers so the new generic system-framebuffer drivers can be
2584 used on x86. If the framebuffer is not compatible with the generic
2585 modes, it is adverticed as fallback platform framebuffer so legacy
2586 drivers like efifb, vesafb and uvesafb can pick it up.
2587 If this option is not selected, all system framebuffers are always
2588 marked as fallback platform framebuffers as usual.
2590 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2591 not be able to pick up generic system framebuffers if this option
2592 is selected. You are highly encouraged to enable simplefb as
2593 replacement if you select this option. simplefb can correctly deal
2594 with generic system framebuffers. But you should still keep vesafb
2595 and others enabled as fallback if a system framebuffer is
2596 incompatible with simplefb.
2603 menu "Executable file formats / Emulations"
2605 source "fs/Kconfig.binfmt"
2607 config IA32_EMULATION
2608 bool "IA32 Emulation"
2611 select COMPAT_BINFMT_ELF
2612 select ARCH_WANT_OLD_COMPAT_IPC
2614 Include code to run legacy 32-bit programs under a
2615 64-bit kernel. You should likely turn this on, unless you're
2616 100% sure that you don't have any 32-bit programs left.
2619 tristate "IA32 a.out support"
2620 depends on IA32_EMULATION
2622 Support old a.out binaries in the 32bit emulation.
2625 bool "x32 ABI for 64-bit mode"
2628 Include code to run binaries for the x32 native 32-bit ABI
2629 for 64-bit processors. An x32 process gets access to the
2630 full 64-bit register file and wide data path while leaving
2631 pointers at 32 bits for smaller memory footprint.
2633 You will need a recent binutils (2.22 or later) with
2634 elf32_x86_64 support enabled to compile a kernel with this
2639 depends on IA32_EMULATION || X86_X32
2642 config COMPAT_FOR_U64_ALIGNMENT
2645 config SYSVIPC_COMPAT
2657 config HAVE_ATOMIC_IOMAP
2661 config X86_DEV_DMA_OPS
2663 depends on X86_64 || STA2X11
2665 config X86_DMA_REMAP
2673 source "net/Kconfig"
2675 source "drivers/Kconfig"
2677 source "drivers/firmware/Kconfig"
2681 source "arch/x86/Kconfig.debug"
2683 source "security/Kconfig"
2685 source "crypto/Kconfig"
2687 source "arch/x86/kvm/Kconfig"
2689 source "lib/Kconfig"