1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if ARCH = "x86"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
18 select HAVE_GENERIC_DMA_COHERENT
19 select MODULES_USE_ELF_REL
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
27 select ARCH_SUPPORTS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select X86_DEV_DMA_OPS
32 select ARCH_HAS_SYSCALL_WRAPPER
37 # ( Note that options that are marked 'if X86_64' could in principle be
38 # ported to 32-bit as well. )
43 # Note: keep this list sorted alphabetically
45 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
46 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
48 select ARCH_CLOCKSOURCE_DATA
49 select ARCH_DISCARD_MEMBLOCK
50 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
51 select ARCH_HAS_DEBUG_VIRTUAL
52 select ARCH_HAS_DEVMEM_IS_ALLOWED
53 select ARCH_HAS_ELF_RANDOMIZE
54 select ARCH_HAS_FAST_MULTIPLIER
55 select ARCH_HAS_FILTER_PGPROT
56 select ARCH_HAS_FORTIFY_SOURCE
57 select ARCH_HAS_GCOV_PROFILE_ALL
58 select ARCH_HAS_KCOV if X86_64
59 select ARCH_HAS_MEMBARRIER_SYNC_CORE
60 select ARCH_HAS_PMEM_API if X86_64
61 select ARCH_HAS_REFCOUNT
62 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
63 select ARCH_HAS_SET_MEMORY
64 select ARCH_HAS_SG_CHAIN
65 select ARCH_HAS_STRICT_KERNEL_RWX
66 select ARCH_HAS_STRICT_MODULE_RWX
67 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
68 select ARCH_HAS_UBSAN_SANITIZE_ALL
69 select ARCH_HAS_ZONE_DEVICE if X86_64
70 select ARCH_HAVE_NMI_SAFE_CMPXCHG
71 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
72 select ARCH_MIGHT_HAVE_PC_PARPORT
73 select ARCH_MIGHT_HAVE_PC_SERIO
74 select ARCH_SUPPORTS_ATOMIC_RMW
75 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
76 select ARCH_USE_BUILTIN_BSWAP
77 select ARCH_USE_QUEUED_RWLOCKS
78 select ARCH_USE_QUEUED_SPINLOCKS
79 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
80 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
81 select ARCH_WANTS_THP_SWAP if X86_64
82 select BUILDTIME_EXTABLE_SORT
84 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
85 select CLOCKSOURCE_WATCHDOG
86 select DCACHE_WORD_ACCESS
88 select EDAC_ATOMIC_SCRUB
90 select GENERIC_CLOCKEVENTS
91 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
92 select GENERIC_CLOCKEVENTS_MIN_ADJUST
93 select GENERIC_CMOS_UPDATE
94 select GENERIC_CPU_AUTOPROBE
95 select GENERIC_CPU_VULNERABILITIES
96 select GENERIC_EARLY_IOREMAP
97 select GENERIC_FIND_FIRST_BIT
99 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
100 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
101 select GENERIC_IRQ_MIGRATION if SMP
102 select GENERIC_IRQ_PROBE
103 select GENERIC_IRQ_RESERVATION_MODE
104 select GENERIC_IRQ_SHOW
105 select GENERIC_PENDING_IRQ if SMP
106 select GENERIC_SMP_IDLE_THREAD
107 select GENERIC_STRNCPY_FROM_USER
108 select GENERIC_STRNLEN_USER
109 select GENERIC_TIME_VSYSCALL
110 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
111 select HAVE_ACPI_APEI if ACPI
112 select HAVE_ACPI_APEI_NMI if ACPI
113 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
114 select HAVE_ARCH_AUDITSYSCALL
115 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
116 select HAVE_ARCH_JUMP_LABEL
117 select HAVE_ARCH_KASAN if X86_64
118 select HAVE_ARCH_KGDB
119 select HAVE_ARCH_MMAP_RND_BITS if MMU
120 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
121 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
122 select HAVE_ARCH_SECCOMP_FILTER
123 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
124 select HAVE_ARCH_TRACEHOOK
125 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
126 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
127 select HAVE_ARCH_VMAP_STACK if X86_64
128 select HAVE_ARCH_WITHIN_STACK_FRAMES
129 select HAVE_CC_STACKPROTECTOR
130 select HAVE_CMPXCHG_DOUBLE
131 select HAVE_CMPXCHG_LOCAL
132 select HAVE_CONTEXT_TRACKING if X86_64
133 select HAVE_COPY_THREAD_TLS
134 select HAVE_C_RECORDMCOUNT
135 select HAVE_DEBUG_KMEMLEAK
136 select HAVE_DEBUG_STACKOVERFLOW
137 select HAVE_DMA_API_DEBUG
138 select HAVE_DMA_CONTIGUOUS
139 select HAVE_DYNAMIC_FTRACE
140 select HAVE_DYNAMIC_FTRACE_WITH_REGS
141 select HAVE_EBPF_JIT if X86_64
142 select HAVE_EFFICIENT_UNALIGNED_ACCESS
143 select HAVE_EXIT_THREAD
144 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
145 select HAVE_FTRACE_MCOUNT_RECORD
146 select HAVE_FUNCTION_GRAPH_TRACER
147 select HAVE_FUNCTION_TRACER
148 select HAVE_GCC_PLUGINS
149 select HAVE_HW_BREAKPOINT
151 select HAVE_IOREMAP_PROT
152 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
153 select HAVE_IRQ_TIME_ACCOUNTING
154 select HAVE_KERNEL_BZIP2
155 select HAVE_KERNEL_GZIP
156 select HAVE_KERNEL_LZ4
157 select HAVE_KERNEL_LZMA
158 select HAVE_KERNEL_LZO
159 select HAVE_KERNEL_XZ
161 select HAVE_KPROBES_ON_FTRACE
162 select HAVE_FUNCTION_ERROR_INJECTION
163 select HAVE_KRETPROBES
165 select HAVE_LIVEPATCH if X86_64
167 select HAVE_MEMBLOCK_NODE_MAP
168 select HAVE_MIXED_BREAKPOINTS_REGS
169 select HAVE_MOD_ARCH_SPECIFIC
172 select HAVE_OPTPROBES
173 select HAVE_PCSPKR_PLATFORM
174 select HAVE_PERF_EVENTS
175 select HAVE_PERF_EVENTS_NMI
176 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
177 select HAVE_PERF_REGS
178 select HAVE_PERF_USER_STACK_DUMP
179 select HAVE_RCU_TABLE_FREE
180 select HAVE_REGS_AND_STACK_ACCESS_API
181 select HAVE_RELIABLE_STACKTRACE if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
182 select HAVE_STACK_VALIDATION if X86_64
183 select HAVE_SYSCALL_TRACEPOINTS
184 select HAVE_UNSTABLE_SCHED_CLOCK
185 select HAVE_USER_RETURN_NOTIFIER
186 select IRQ_FORCED_THREADING
187 select PCI_LOCKLESS_CONFIG
190 select RTC_MC146818_LIB
193 select SYSCTL_EXCEPTION_TRACE
194 select THREAD_INFO_IN_TASK
195 select USER_STACKTRACE_SUPPORT
197 select X86_FEATURE_NAMES if PROC_FS
199 config INSTRUCTION_DECODER
201 depends on KPROBES || PERF_EVENTS || UPROBES
205 default "elf32-i386" if X86_32
206 default "elf64-x86-64" if X86_64
208 config ARCH_DEFCONFIG
210 default "arch/x86/configs/i386_defconfig" if X86_32
211 default "arch/x86/configs/x86_64_defconfig" if X86_64
213 config LOCKDEP_SUPPORT
216 config STACKTRACE_SUPPORT
222 config ARCH_MMAP_RND_BITS_MIN
226 config ARCH_MMAP_RND_BITS_MAX
230 config ARCH_MMAP_RND_COMPAT_BITS_MIN
233 config ARCH_MMAP_RND_COMPAT_BITS_MAX
239 config NEED_DMA_MAP_STATE
241 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
243 config NEED_SG_DMA_LENGTH
246 config GENERIC_ISA_DMA
248 depends on ISA_DMA_API
253 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
255 config GENERIC_BUG_RELATIVE_POINTERS
258 config GENERIC_HWEIGHT
261 config ARCH_MAY_HAVE_PC_FDC
263 depends on ISA_DMA_API
265 config RWSEM_XCHGADD_ALGORITHM
268 config GENERIC_CALIBRATE_DELAY
271 config ARCH_HAS_CPU_RELAX
274 config ARCH_HAS_CACHE_LINE_SIZE
277 config ARCH_HAS_FILTER_PGPROT
280 config HAVE_SETUP_PER_CPU_AREA
283 config NEED_PER_CPU_EMBED_FIRST_CHUNK
286 config NEED_PER_CPU_PAGE_FIRST_CHUNK
289 config ARCH_HIBERNATION_POSSIBLE
292 config ARCH_SUSPEND_POSSIBLE
295 config ARCH_WANT_HUGE_PMD_SHARE
298 config ARCH_WANT_GENERAL_HUGETLB
307 config ARCH_SUPPORTS_OPTIMIZED_INLINING
310 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
313 config KASAN_SHADOW_OFFSET
316 default 0xdffffc0000000000
318 config HAVE_INTEL_TXT
320 depends on INTEL_IOMMU && ACPI
324 depends on X86_32 && SMP
328 depends on X86_64 && SMP
330 config X86_32_LAZY_GS
332 depends on X86_32 && CC_STACKPROTECTOR_NONE
334 config ARCH_SUPPORTS_UPROBES
337 config FIX_EARLYCON_MEM
340 config PGTABLE_LEVELS
342 default 5 if X86_5LEVEL
347 source "init/Kconfig"
348 source "kernel/Kconfig.freezer"
350 menu "Processor type and features"
353 bool "DMA memory allocation support" if EXPERT
356 DMA memory allocation support allows devices with less than 32-bit
357 addressing to allocate within the first 16MB of address space.
358 Disable if no such devices will be used.
363 bool "Symmetric multi-processing support"
365 This enables support for systems with more than one CPU. If you have
366 a system with only one CPU, say N. If you have a system with more
369 If you say N here, the kernel will run on uni- and multiprocessor
370 machines, but will use only one CPU of a multiprocessor machine. If
371 you say Y here, the kernel will run on many, but not all,
372 uniprocessor machines. On a uniprocessor machine, the kernel
373 will run faster if you say N here.
375 Note that if you say Y here and choose architecture "586" or
376 "Pentium" under "Processor family", the kernel will not work on 486
377 architectures. Similarly, multiprocessor kernels for the "PPro"
378 architecture may not work on all Pentium based boards.
380 People using multiprocessor machines who say Y here should also say
381 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
382 Management" code will be disabled if you say Y here.
384 See also <file:Documentation/x86/i386/IO-APIC.txt>,
385 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
386 <http://www.tldp.org/docs.html#howto>.
388 If you don't know what to do here, say N.
390 config X86_FEATURE_NAMES
391 bool "Processor feature human-readable names" if EMBEDDED
394 This option compiles in a table of x86 feature bits and corresponding
395 names. This is required to support /proc/cpuinfo and a few kernel
396 messages. You can disable this to save space, at the expense of
397 making those few kernel messages show numeric feature bits instead.
402 bool "Support x2apic"
403 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
405 This enables x2apic support on CPUs that have this feature.
407 This allows 32-bit apic IDs (so it can support very large systems),
408 and accesses the local apic via MSRs not via mmio.
410 If you don't know what to do here, say N.
413 bool "Enable MPS table" if ACPI || SFI
415 depends on X86_LOCAL_APIC
417 For old smp systems that do not have proper acpi support. Newer systems
418 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
422 depends on X86_GOLDFISH
425 bool "Avoid speculative indirect branches in kernel"
427 select STACK_VALIDATION if HAVE_STACK_VALIDATION
429 Compile kernel with the retpoline compiler options to guard against
430 kernel-to-user data leaks by avoiding speculative indirect
431 branches. Requires a compiler with -mindirect-branch=thunk-extern
432 support for full protection. The kernel may run slower.
434 Without compiler support, at least indirect branches in assembler
435 code are eliminated. Since this includes the syscall entry path,
436 it is not entirely pointless.
439 bool "Intel Resource Director Technology support"
441 depends on X86 && CPU_SUP_INTEL
444 Select to enable resource allocation and monitoring which are
445 sub-features of Intel Resource Director Technology(RDT). More
446 information about RDT can be found in the Intel x86
447 Architecture Software Developer Manual.
453 bool "Support for big SMP systems with more than 8 CPUs"
456 This option is needed for the systems that have more than 8 CPUs
458 config X86_EXTENDED_PLATFORM
459 bool "Support for extended (non-PC) x86 platforms"
462 If you disable this option then the kernel will only support
463 standard PC platforms. (which covers the vast majority of
466 If you enable this option then you'll be able to select support
467 for the following (non-PC) 32 bit x86 platforms:
468 Goldfish (Android emulator)
471 SGI 320/540 (Visual Workstation)
472 STA2X11-based (e.g. Northville)
473 Moorestown MID devices
475 If you have one of these systems, or if you want to build a
476 generic distribution kernel, say Y here - otherwise say N.
480 config X86_EXTENDED_PLATFORM
481 bool "Support for extended (non-PC) x86 platforms"
484 If you disable this option then the kernel will only support
485 standard PC platforms. (which covers the vast majority of
488 If you enable this option then you'll be able to select support
489 for the following (non-PC) 64 bit x86 platforms:
494 If you have one of these systems, or if you want to build a
495 generic distribution kernel, say Y here - otherwise say N.
497 # This is an alphabetically sorted list of 64 bit extended platforms
498 # Please maintain the alphabetic order if and when there are additions
500 bool "Numascale NumaChip"
502 depends on X86_EXTENDED_PLATFORM
505 depends on X86_X2APIC
506 depends on PCI_MMCONFIG
508 Adds support for Numascale NumaChip large-SMP systems. Needed to
509 enable more than ~168 cores.
510 If you don't have one of these, you should say N here.
514 select HYPERVISOR_GUEST
516 depends on X86_64 && PCI
517 depends on X86_EXTENDED_PLATFORM
520 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
521 supposed to run on these EM64T-based machines. Only choose this option
522 if you have one of these machines.
525 bool "SGI Ultraviolet"
527 depends on X86_EXTENDED_PLATFORM
530 depends on X86_X2APIC
533 This option is needed in order to support SGI Ultraviolet systems.
534 If you don't have one of these, you should say N here.
536 # Following is an alphabetically sorted list of 32 bit extended platforms
537 # Please maintain the alphabetic order if and when there are additions
540 bool "Goldfish (Virtual Platform)"
541 depends on X86_EXTENDED_PLATFORM
543 Enable support for the Goldfish virtual platform used primarily
544 for Android development. Unless you are building for the Android
545 Goldfish emulator say N here.
548 bool "CE4100 TV platform"
550 depends on PCI_GODIRECT
551 depends on X86_IO_APIC
553 depends on X86_EXTENDED_PLATFORM
554 select X86_REBOOTFIXUPS
556 select OF_EARLY_FLATTREE
558 Select for the Intel CE media processor (CE4100) SOC.
559 This option compiles in support for the CE4100 SOC for settop
560 boxes and media devices.
563 bool "Intel MID platform support"
564 depends on X86_EXTENDED_PLATFORM
565 depends on X86_PLATFORM_DEVICES
567 depends on X86_64 || (PCI_GOANY && X86_32)
568 depends on X86_IO_APIC
574 select MFD_INTEL_MSIC
576 Select to build a kernel capable of supporting Intel MID (Mobile
577 Internet Device) platform systems which do not have the PCI legacy
578 interfaces. If you are building for a PC class system say N here.
580 Intel MID platforms are based on an Intel processor and chipset which
581 consume less power than most of the x86 derivatives.
583 config X86_INTEL_QUARK
584 bool "Intel Quark platform support"
586 depends on X86_EXTENDED_PLATFORM
587 depends on X86_PLATFORM_DEVICES
591 depends on X86_IO_APIC
596 Select to include support for Quark X1000 SoC.
597 Say Y here if you have a Quark based system such as the Arduino
598 compatible Intel Galileo.
600 config X86_INTEL_LPSS
601 bool "Intel Low Power Subsystem Support"
602 depends on X86 && ACPI
607 Select to build support for Intel Low Power Subsystem such as
608 found on Intel Lynxpoint PCH. Selecting this option enables
609 things like clock tree (common clock framework) and pincontrol
610 which are needed by the LPSS peripheral drivers.
612 config X86_AMD_PLATFORM_DEVICE
613 bool "AMD ACPI2Platform devices support"
618 Select to interpret AMD specific ACPI device to platform device
619 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
620 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
621 implemented under PINCTRL subsystem.
624 tristate "Intel SoC IOSF Sideband support for SoC platforms"
627 This option enables sideband register access support for Intel SoC
628 platforms. On these platforms the IOSF sideband is used in lieu of
629 MSR's for some register accesses, mostly but not limited to thermal
630 and power. Drivers may query the availability of this device to
631 determine if they need the sideband in order to work on these
632 platforms. The sideband is available on the following SoC products.
633 This list is not meant to be exclusive.
638 You should say Y if you are running a kernel on one of these SoC's.
640 config IOSF_MBI_DEBUG
641 bool "Enable IOSF sideband access through debugfs"
642 depends on IOSF_MBI && DEBUG_FS
644 Select this option to expose the IOSF sideband access registers (MCR,
645 MDR, MCRX) through debugfs to write and read register information from
646 different units on the SoC. This is most useful for obtaining device
647 state information for debug and analysis. As this is a general access
648 mechanism, users of this option would have specific knowledge of the
649 device they want to access.
651 If you don't require the option or are in doubt, say N.
654 bool "RDC R-321x SoC"
656 depends on X86_EXTENDED_PLATFORM
658 select X86_REBOOTFIXUPS
660 This option is needed for RDC R-321x system-on-chip, also known
662 If you don't have one of these chips, you should say N here.
664 config X86_32_NON_STANDARD
665 bool "Support non-standard 32-bit SMP architectures"
666 depends on X86_32 && SMP
667 depends on X86_EXTENDED_PLATFORM
669 This option compiles in the bigsmp and STA2X11 default
670 subarchitectures. It is intended for a generic binary
671 kernel. If you select them all, kernel will probe it one by
672 one and will fallback to default.
674 # Alphabetically sorted list of Non standard 32 bit platforms
676 config X86_SUPPORTS_MEMORY_FAILURE
678 # MCE code calls memory_failure():
680 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
681 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
682 depends on X86_64 || !SPARSEMEM
683 select ARCH_SUPPORTS_MEMORY_FAILURE
686 bool "STA2X11 Companion Chip Support"
687 depends on X86_32_NON_STANDARD && PCI
688 select ARCH_HAS_PHYS_TO_DMA
689 select X86_DEV_DMA_OPS
696 This adds support for boards based on the STA2X11 IO-Hub,
697 a.k.a. "ConneXt". The chip is used in place of the standard
698 PC chipset, so all "standard" peripherals are missing. If this
699 option is selected the kernel will still be able to boot on
700 standard PC machines.
703 tristate "Eurobraille/Iris poweroff module"
706 The Iris machines from EuroBraille do not have APM or ACPI support
707 to shut themselves down properly. A special I/O sequence is
708 needed to do so, which is what this module does at
711 This is only for Iris machines from EuroBraille.
715 config SCHED_OMIT_FRAME_POINTER
717 prompt "Single-depth WCHAN output"
720 Calculate simpler /proc/<PID>/wchan values. If this option
721 is disabled then wchan values will recurse back to the
722 caller function. This provides more accurate wchan values,
723 at the expense of slightly more scheduling overhead.
725 If in doubt, say "Y".
727 menuconfig HYPERVISOR_GUEST
728 bool "Linux guest support"
730 Say Y here to enable options for running Linux under various hyper-
731 visors. This option enables basic hypervisor detection and platform
734 If you say N, all options in this submenu will be skipped and
735 disabled, and Linux guest support won't be built in.
740 bool "Enable paravirtualization code"
742 This changes the kernel so it can modify itself when it is run
743 under a hypervisor, potentially improving performance significantly
744 over full virtualization. However, when run without a hypervisor
745 the kernel is theoretically slower and slightly larger.
747 config PARAVIRT_DEBUG
748 bool "paravirt-ops debugging"
749 depends on PARAVIRT && DEBUG_KERNEL
751 Enable to debug paravirt_ops internals. Specifically, BUG if
752 a paravirt_op is missing when it is called.
754 config PARAVIRT_SPINLOCKS
755 bool "Paravirtualization layer for spinlocks"
756 depends on PARAVIRT && SMP
758 Paravirtualized spinlocks allow a pvops backend to replace the
759 spinlock implementation with something virtualization-friendly
760 (for example, block the virtual CPU rather than spinning).
762 It has a minimal impact on native kernels and gives a nice performance
763 benefit on paravirtualized KVM / Xen kernels.
765 If you are unsure how to answer this question, answer Y.
767 config QUEUED_LOCK_STAT
768 bool "Paravirt queued spinlock statistics"
769 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
771 Enable the collection of statistical data on the slowpath
772 behavior of paravirtualized queued spinlocks and report
775 source "arch/x86/xen/Kconfig"
778 bool "KVM Guest support (including kvmclock)"
780 select PARAVIRT_CLOCK
783 This option enables various optimizations for running under the KVM
784 hypervisor. It includes a paravirtualized clock, so that instead
785 of relying on a PIT (or probably other) emulation by the
786 underlying device model, the host provides the guest with
787 timing infrastructure such as time of day, and system time
790 bool "Enable debug information for KVM Guests in debugfs"
791 depends on KVM_GUEST && DEBUG_FS
794 This option enables collection of various statistics for KVM guest.
795 Statistics are displayed in debugfs filesystem. Enabling this option
796 may incur significant overhead.
798 config PARAVIRT_TIME_ACCOUNTING
799 bool "Paravirtual steal time accounting"
803 Select this option to enable fine granularity task steal time
804 accounting. Time spent executing other tasks in parallel with
805 the current vCPU is discounted from the vCPU power. To account for
806 that, there can be a small performance impact.
808 If in doubt, say N here.
810 config PARAVIRT_CLOCK
813 config JAILHOUSE_GUEST
814 bool "Jailhouse non-root cell support"
815 depends on X86_64 && PCI
818 This option allows to run Linux as guest in a Jailhouse non-root
819 cell. You can leave this option disabled if you only want to start
820 Jailhouse and run Linux afterwards in the root cell.
822 endif #HYPERVISOR_GUEST
827 source "arch/x86/Kconfig.cpu"
831 prompt "HPET Timer Support" if X86_32
833 Use the IA-PC HPET (High Precision Event Timer) to manage
834 time in preference to the PIT and RTC, if a HPET is
836 HPET is the next generation timer replacing legacy 8254s.
837 The HPET provides a stable time base on SMP
838 systems, unlike the TSC, but it is more expensive to access,
839 as it is off-chip. The interface used is documented
840 in the HPET spec, revision 1.
842 You can safely choose Y here. However, HPET will only be
843 activated if the platform and the BIOS support this feature.
844 Otherwise the 8254 will be used for timing services.
846 Choose N to continue using the legacy 8254 timer.
848 config HPET_EMULATE_RTC
850 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
853 def_bool y if X86_INTEL_MID
854 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
856 depends on X86_INTEL_MID && SFI
858 APB timer is the replacement for 8254, HPET on X86 MID platforms.
859 The APBT provides a stable time base on SMP
860 systems, unlike the TSC, but it is more expensive to access,
861 as it is off-chip. APB timers are always running regardless of CPU
862 C states, they are used as per CPU clockevent device when possible.
864 # Mark as expert because too many people got it wrong.
865 # The code disables itself when not needed.
868 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
869 bool "Enable DMI scanning" if EXPERT
871 Enabled scanning of DMI to identify machine quirks. Say Y
872 here unless you have verified that your setup is not
873 affected by entries in the DMI blacklist. Required by PNP
877 bool "Old AMD GART IOMMU support"
879 depends on X86_64 && PCI && AMD_NB
881 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
882 GART based hardware IOMMUs.
884 The GART supports full DMA access for devices with 32-bit access
885 limitations, on systems with more than 3 GB. This is usually needed
886 for USB, sound, many IDE/SATA chipsets and some other devices.
888 Newer systems typically have a modern AMD IOMMU, supported via
889 the CONFIG_AMD_IOMMU=y config option.
891 In normal configurations this driver is only active when needed:
892 there's more than 3 GB of memory and the system contains a
893 32-bit limited device.
898 bool "IBM Calgary IOMMU support"
900 depends on X86_64 && PCI
902 Support for hardware IOMMUs in IBM's xSeries x366 and x460
903 systems. Needed to run systems with more than 3GB of memory
904 properly with 32-bit PCI devices that do not support DAC
905 (Double Address Cycle). Calgary also supports bus level
906 isolation, where all DMAs pass through the IOMMU. This
907 prevents them from going anywhere except their intended
908 destination. This catches hard-to-find kernel bugs and
909 mis-behaving drivers and devices that do not use the DMA-API
910 properly to set up their DMA buffers. The IOMMU can be
911 turned off at boot time with the iommu=off parameter.
912 Normally the kernel will make the right choice by itself.
915 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
917 prompt "Should Calgary be enabled by default?"
918 depends on CALGARY_IOMMU
920 Should Calgary be enabled by default? if you choose 'y', Calgary
921 will be used (if it exists). If you choose 'n', Calgary will not be
922 used even if it exists. If you choose 'n' and would like to use
923 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
926 # need this always selected by IOMMU for the VIA workaround
930 Support for software bounce buffers used on x86-64 systems
931 which don't have a hardware IOMMU. Using this PCI devices
932 which can only access 32-bits of memory can be used on systems
933 with more than 3 GB of memory.
938 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
941 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
942 depends on X86_64 && SMP && DEBUG_KERNEL
943 select CPUMASK_OFFSTACK
945 Enable maximum number of CPUS and NUMA Nodes for this architecture.
949 # The maximum number of CPUs supported:
951 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
952 # and which can be configured interactively in the
953 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
955 # The ranges are different on 32-bit and 64-bit kernels, depending on
956 # hardware capabilities and scalability features of the kernel.
958 # ( If MAXSMP is enabled we just use the highest possible value and disable
959 # interactive configuration. )
962 config NR_CPUS_RANGE_BEGIN
964 default NR_CPUS_RANGE_END if MAXSMP
968 config NR_CPUS_RANGE_END
971 default 64 if SMP && X86_BIGSMP
972 default 8 if SMP && !X86_BIGSMP
975 config NR_CPUS_RANGE_END
978 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
979 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
982 config NR_CPUS_DEFAULT
985 default 32 if X86_BIGSMP
989 config NR_CPUS_DEFAULT
992 default 8192 if MAXSMP
997 int "Maximum number of CPUs" if SMP && !MAXSMP
998 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
999 default NR_CPUS_DEFAULT
1001 This allows you to specify the maximum number of CPUs which this
1002 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1003 supported value is 8192, otherwise the maximum value is 512. The
1004 minimum value which makes sense is 2.
1006 This is purely to save memory: each supported CPU adds about 8KB
1007 to the kernel image.
1010 bool "SMT (Hyperthreading) scheduler support"
1013 SMT scheduler support improves the CPU scheduler's decision making
1014 when dealing with Intel Pentium 4 chips with HyperThreading at a
1015 cost of slightly increased overhead in some places. If unsure say
1020 prompt "Multi-core scheduler support"
1023 Multi-core scheduler support improves the CPU scheduler's decision
1024 making when dealing with multi-core CPU chips at a cost of slightly
1025 increased overhead in some places. If unsure say N here.
1027 config SCHED_MC_PRIO
1028 bool "CPU core priorities scheduler support"
1029 depends on SCHED_MC && CPU_SUP_INTEL
1030 select X86_INTEL_PSTATE
1034 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1035 core ordering determined at manufacturing time, which allows
1036 certain cores to reach higher turbo frequencies (when running
1037 single threaded workloads) than others.
1039 Enabling this kernel feature teaches the scheduler about
1040 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1041 scheduler's CPU selection logic accordingly, so that higher
1042 overall system performance can be achieved.
1044 This feature will have no effect on CPUs without this feature.
1046 If unsure say Y here.
1048 source "kernel/Kconfig.preempt"
1052 depends on !SMP && X86_LOCAL_APIC
1055 bool "Local APIC support on uniprocessors" if !PCI_MSI
1057 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1059 A local APIC (Advanced Programmable Interrupt Controller) is an
1060 integrated interrupt controller in the CPU. If you have a single-CPU
1061 system which has a processor with a local APIC, you can say Y here to
1062 enable and use it. If you say Y here even though your machine doesn't
1063 have a local APIC, then the kernel will still run with no slowdown at
1064 all. The local APIC supports CPU-generated self-interrupts (timer,
1065 performance counters), and the NMI watchdog which detects hard
1068 config X86_UP_IOAPIC
1069 bool "IO-APIC support on uniprocessors"
1070 depends on X86_UP_APIC
1072 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1073 SMP-capable replacement for PC-style interrupt controllers. Most
1074 SMP systems and many recent uniprocessor systems have one.
1076 If you have a single-CPU system with an IO-APIC, you can say Y here
1077 to use it. If you say Y here even though your machine doesn't have
1078 an IO-APIC, then the kernel will still run with no slowdown at all.
1080 config X86_LOCAL_APIC
1082 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1083 select IRQ_DOMAIN_HIERARCHY
1084 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1088 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1090 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1091 bool "Reroute for broken boot IRQs"
1092 depends on X86_IO_APIC
1094 This option enables a workaround that fixes a source of
1095 spurious interrupts. This is recommended when threaded
1096 interrupt handling is used on systems where the generation of
1097 superfluous "boot interrupts" cannot be disabled.
1099 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1100 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1101 kernel does during interrupt handling). On chipsets where this
1102 boot IRQ generation cannot be disabled, this workaround keeps
1103 the original IRQ line masked so that only the equivalent "boot
1104 IRQ" is delivered to the CPUs. The workaround also tells the
1105 kernel to set up the IRQ handler on the boot IRQ line. In this
1106 way only one interrupt is delivered to the kernel. Otherwise
1107 the spurious second interrupt may cause the kernel to bring
1108 down (vital) interrupt lines.
1110 Only affects "broken" chipsets. Interrupt sharing may be
1111 increased on these systems.
1114 bool "Machine Check / overheating reporting"
1115 select GENERIC_ALLOCATOR
1118 Machine Check support allows the processor to notify the
1119 kernel if it detects a problem (e.g. overheating, data corruption).
1120 The action the kernel takes depends on the severity of the problem,
1121 ranging from warning messages to halting the machine.
1123 config X86_MCELOG_LEGACY
1124 bool "Support for deprecated /dev/mcelog character device"
1127 Enable support for /dev/mcelog which is needed by the old mcelog
1128 userspace logging daemon. Consider switching to the new generation
1131 config X86_MCE_INTEL
1133 prompt "Intel MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC
1136 Additional support for intel specific MCE features such as
1137 the thermal monitor.
1141 prompt "AMD MCE features"
1142 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1144 Additional support for AMD specific MCE features such as
1145 the DRAM Error Threshold.
1147 config X86_ANCIENT_MCE
1148 bool "Support for old Pentium 5 / WinChip machine checks"
1149 depends on X86_32 && X86_MCE
1151 Include support for machine check handling on old Pentium 5 or WinChip
1152 systems. These typically need to be enabled explicitly on the command
1155 config X86_MCE_THRESHOLD
1156 depends on X86_MCE_AMD || X86_MCE_INTEL
1159 config X86_MCE_INJECT
1160 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1161 tristate "Machine check injector support"
1163 Provide support for injecting machine checks for testing purposes.
1164 If you don't know what a machine check is and you don't do kernel
1165 QA it is safe to say n.
1167 config X86_THERMAL_VECTOR
1169 depends on X86_MCE_INTEL
1171 source "arch/x86/events/Kconfig"
1173 config X86_LEGACY_VM86
1174 bool "Legacy VM86 support"
1178 This option allows user programs to put the CPU into V8086
1179 mode, which is an 80286-era approximation of 16-bit real mode.
1181 Some very old versions of X and/or vbetool require this option
1182 for user mode setting. Similarly, DOSEMU will use it if
1183 available to accelerate real mode DOS programs. However, any
1184 recent version of DOSEMU, X, or vbetool should be fully
1185 functional even without kernel VM86 support, as they will all
1186 fall back to software emulation. Nevertheless, if you are using
1187 a 16-bit DOS program where 16-bit performance matters, vm86
1188 mode might be faster than emulation and you might want to
1191 Note that any app that works on a 64-bit kernel is unlikely to
1192 need this option, as 64-bit kernels don't, and can't, support
1193 V8086 mode. This option is also unrelated to 16-bit protected
1194 mode and is not needed to run most 16-bit programs under Wine.
1196 Enabling this option increases the complexity of the kernel
1197 and slows down exception handling a tiny bit.
1199 If unsure, say N here.
1203 default X86_LEGACY_VM86
1206 bool "Enable support for 16-bit segments" if EXPERT
1208 depends on MODIFY_LDT_SYSCALL
1210 This option is required by programs like Wine to run 16-bit
1211 protected mode legacy code on x86 processors. Disabling
1212 this option saves about 300 bytes on i386, or around 6K text
1213 plus 16K runtime memory on x86-64,
1217 depends on X86_16BIT && X86_32
1221 depends on X86_16BIT && X86_64
1223 config X86_VSYSCALL_EMULATION
1224 bool "Enable vsyscall emulation" if EXPERT
1228 This enables emulation of the legacy vsyscall page. Disabling
1229 it is roughly equivalent to booting with vsyscall=none, except
1230 that it will also disable the helpful warning if a program
1231 tries to use a vsyscall. With this option set to N, offending
1232 programs will just segfault, citing addresses of the form
1235 This option is required by many programs built before 2013, and
1236 care should be used even with newer programs if set to N.
1238 Disabling this option saves about 7K of kernel size and
1239 possibly 4K of additional runtime pagetable memory.
1242 tristate "Toshiba Laptop support"
1245 This adds a driver to safely access the System Management Mode of
1246 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1247 not work on models with a Phoenix BIOS. The System Management Mode
1248 is used to set the BIOS and power saving options on Toshiba portables.
1250 For information on utilities to make use of this driver see the
1251 Toshiba Linux utilities web site at:
1252 <http://www.buzzard.org.uk/toshiba/>.
1254 Say Y if you intend to run this kernel on a Toshiba portable.
1258 tristate "Dell i8k legacy laptop support"
1260 select SENSORS_DELL_SMM
1262 This option enables legacy /proc/i8k userspace interface in hwmon
1263 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1264 temperature and allows controlling fan speeds of Dell laptops via
1265 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1266 it reports also power and hotkey status. For fan speed control is
1267 needed userspace package i8kutils.
1269 Say Y if you intend to run this kernel on old Dell laptops or want to
1270 use userspace package i8kutils.
1273 config X86_REBOOTFIXUPS
1274 bool "Enable X86 board specific fixups for reboot"
1277 This enables chipset and/or board specific fixups to be done
1278 in order to get reboot to work correctly. This is only needed on
1279 some combinations of hardware and BIOS. The symptom, for which
1280 this config is intended, is when reboot ends with a stalled/hung
1283 Currently, the only fixup is for the Geode machines using
1284 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1286 Say Y if you want to enable the fixup. Currently, it's safe to
1287 enable this option even if you don't need it.
1291 bool "CPU microcode loading support"
1293 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1296 If you say Y here, you will be able to update the microcode on
1297 Intel and AMD processors. The Intel support is for the IA32 family,
1298 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1299 AMD support is for families 0x10 and later. You will obviously need
1300 the actual microcode binary data itself which is not shipped with
1303 The preferred method to load microcode from a detached initrd is described
1304 in Documentation/x86/microcode.txt. For that you need to enable
1305 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1306 initrd for microcode blobs.
1308 In addition, you can build the microcode into the kernel. For that you
1309 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1312 config MICROCODE_INTEL
1313 bool "Intel microcode loading support"
1314 depends on MICROCODE
1318 This options enables microcode patch loading support for Intel
1321 For the current Intel microcode data package go to
1322 <https://downloadcenter.intel.com> and search for
1323 'Linux Processor Microcode Data File'.
1325 config MICROCODE_AMD
1326 bool "AMD microcode loading support"
1327 depends on MICROCODE
1330 If you select this option, microcode patch loading support for AMD
1331 processors will be enabled.
1333 config MICROCODE_OLD_INTERFACE
1335 depends on MICROCODE
1338 tristate "/dev/cpu/*/msr - Model-specific register support"
1340 This device gives privileged processes access to the x86
1341 Model-Specific Registers (MSRs). It is a character device with
1342 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1343 MSR accesses are directed to a specific CPU on multi-processor
1347 tristate "/dev/cpu/*/cpuid - CPU information support"
1349 This device gives processes access to the x86 CPUID instruction to
1350 be executed on a specific processor. It is a character device
1351 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1355 prompt "High Memory Support"
1362 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1363 However, the address space of 32-bit x86 processors is only 4
1364 Gigabytes large. That means that, if you have a large amount of
1365 physical memory, not all of it can be "permanently mapped" by the
1366 kernel. The physical memory that's not permanently mapped is called
1369 If you are compiling a kernel which will never run on a machine with
1370 more than 1 Gigabyte total physical RAM, answer "off" here (default
1371 choice and suitable for most users). This will result in a "3GB/1GB"
1372 split: 3GB are mapped so that each process sees a 3GB virtual memory
1373 space and the remaining part of the 4GB virtual memory space is used
1374 by the kernel to permanently map as much physical memory as
1377 If the machine has between 1 and 4 Gigabytes physical RAM, then
1380 If more than 4 Gigabytes is used then answer "64GB" here. This
1381 selection turns Intel PAE (Physical Address Extension) mode on.
1382 PAE implements 3-level paging on IA32 processors. PAE is fully
1383 supported by Linux, PAE mode is implemented on all recent Intel
1384 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1385 then the kernel will not boot on CPUs that don't support PAE!
1387 The actual amount of total physical memory will either be
1388 auto detected or can be forced by using a kernel command line option
1389 such as "mem=256M". (Try "man bootparam" or see the documentation of
1390 your boot loader (lilo or loadlin) about how to pass options to the
1391 kernel at boot time.)
1393 If unsure, say "off".
1398 Select this if you have a 32-bit processor and between 1 and 4
1399 gigabytes of physical RAM.
1403 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1406 Select this if you have a 32-bit processor and more than 4
1407 gigabytes of physical RAM.
1412 prompt "Memory split" if EXPERT
1416 Select the desired split between kernel and user memory.
1418 If the address range available to the kernel is less than the
1419 physical memory installed, the remaining memory will be available
1420 as "high memory". Accessing high memory is a little more costly
1421 than low memory, as it needs to be mapped into the kernel first.
1422 Note that increasing the kernel address space limits the range
1423 available to user programs, making the address space there
1424 tighter. Selecting anything other than the default 3G/1G split
1425 will also likely make your kernel incompatible with binary-only
1428 If you are not absolutely sure what you are doing, leave this
1432 bool "3G/1G user/kernel split"
1433 config VMSPLIT_3G_OPT
1435 bool "3G/1G user/kernel split (for full 1G low memory)"
1437 bool "2G/2G user/kernel split"
1438 config VMSPLIT_2G_OPT
1440 bool "2G/2G user/kernel split (for full 2G low memory)"
1442 bool "1G/3G user/kernel split"
1447 default 0xB0000000 if VMSPLIT_3G_OPT
1448 default 0x80000000 if VMSPLIT_2G
1449 default 0x78000000 if VMSPLIT_2G_OPT
1450 default 0x40000000 if VMSPLIT_1G
1456 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1459 bool "PAE (Physical Address Extension) Support"
1460 depends on X86_32 && !HIGHMEM4G
1463 PAE is required for NX support, and furthermore enables
1464 larger swapspace support for non-overcommit purposes. It
1465 has the cost of more pagetable lookup overhead, and also
1466 consumes more pagetable space per process.
1469 bool "Enable 5-level page tables support"
1470 select DYNAMIC_MEMORY_LAYOUT
1471 select SPARSEMEM_VMEMMAP
1474 5-level paging enables access to larger address space:
1475 upto 128 PiB of virtual address space and 4 PiB of
1476 physical address space.
1478 It will be supported by future Intel CPUs.
1480 A kernel with the option enabled can be booted on machines that
1481 support 4- or 5-level paging.
1483 See Documentation/x86/x86_64/5level-paging.txt for more
1488 config ARCH_PHYS_ADDR_T_64BIT
1490 depends on X86_64 || X86_PAE
1492 config ARCH_DMA_ADDR_T_64BIT
1494 depends on X86_64 || HIGHMEM64G
1496 config X86_DIRECT_GBPAGES
1498 depends on X86_64 && !DEBUG_PAGEALLOC
1500 Certain kernel features effectively disable kernel
1501 linear 1 GB mappings (even if the CPU otherwise
1502 supports them), so don't confuse the user by printing
1503 that we have them enabled.
1505 config ARCH_HAS_MEM_ENCRYPT
1508 config AMD_MEM_ENCRYPT
1509 bool "AMD Secure Memory Encryption (SME) support"
1510 depends on X86_64 && CPU_SUP_AMD
1512 Say yes to enable support for the encryption of system memory.
1513 This requires an AMD processor that supports Secure Memory
1516 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1517 bool "Activate AMD Secure Memory Encryption (SME) by default"
1519 depends on AMD_MEM_ENCRYPT
1521 Say yes to have system memory encrypted by default if running on
1522 an AMD processor that supports Secure Memory Encryption (SME).
1524 If set to Y, then the encryption of system memory can be
1525 deactivated with the mem_encrypt=off command line option.
1527 If set to N, then the encryption of system memory can be
1528 activated with the mem_encrypt=on command line option.
1530 config ARCH_USE_MEMREMAP_PROT
1532 depends on AMD_MEM_ENCRYPT
1534 # Common NUMA Features
1536 bool "Numa Memory Allocation and Scheduler Support"
1538 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1539 default y if X86_BIGSMP
1541 Enable NUMA (Non Uniform Memory Access) support.
1543 The kernel will try to allocate memory used by a CPU on the
1544 local memory controller of the CPU and add some more
1545 NUMA awareness to the kernel.
1547 For 64-bit this is recommended if the system is Intel Core i7
1548 (or later), AMD Opteron, or EM64T NUMA.
1550 For 32-bit this is only needed if you boot a 32-bit
1551 kernel on a 64-bit NUMA platform.
1553 Otherwise, you should say N.
1557 prompt "Old style AMD Opteron NUMA detection"
1558 depends on X86_64 && NUMA && PCI
1560 Enable AMD NUMA node topology detection. You should say Y here if
1561 you have a multi processor AMD system. This uses an old method to
1562 read the NUMA configuration directly from the builtin Northbridge
1563 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1564 which also takes priority if both are compiled in.
1566 config X86_64_ACPI_NUMA
1568 prompt "ACPI NUMA detection"
1569 depends on X86_64 && NUMA && ACPI && PCI
1572 Enable ACPI SRAT based node topology detection.
1574 # Some NUMA nodes have memory ranges that span
1575 # other nodes. Even though a pfn is valid and
1576 # between a node's start and end pfns, it may not
1577 # reside on that node. See memmap_init_zone()
1579 config NODES_SPAN_OTHER_NODES
1581 depends on X86_64_ACPI_NUMA
1584 bool "NUMA emulation"
1587 Enable NUMA emulation. A flat machine will be split
1588 into virtual nodes when booted with "numa=fake=N", where N is the
1589 number of nodes. This is only useful for debugging.
1592 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1594 default "10" if MAXSMP
1595 default "6" if X86_64
1597 depends on NEED_MULTIPLE_NODES
1599 Specify the maximum number of NUMA Nodes available on the target
1600 system. Increases memory reserved to accommodate various tables.
1602 config ARCH_HAVE_MEMORY_PRESENT
1604 depends on X86_32 && DISCONTIGMEM
1606 config ARCH_FLATMEM_ENABLE
1608 depends on X86_32 && !NUMA
1610 config ARCH_DISCONTIGMEM_ENABLE
1612 depends on NUMA && X86_32
1614 config ARCH_DISCONTIGMEM_DEFAULT
1616 depends on NUMA && X86_32
1618 config ARCH_SPARSEMEM_ENABLE
1620 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1621 select SPARSEMEM_STATIC if X86_32
1622 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1624 config ARCH_SPARSEMEM_DEFAULT
1628 config ARCH_SELECT_MEMORY_MODEL
1630 depends on ARCH_SPARSEMEM_ENABLE
1632 config ARCH_MEMORY_PROBE
1633 bool "Enable sysfs memory/probe interface"
1634 depends on X86_64 && MEMORY_HOTPLUG
1636 This option enables a sysfs memory/probe interface for testing.
1637 See Documentation/memory-hotplug.txt for more information.
1638 If you are unsure how to answer this question, answer N.
1640 config ARCH_PROC_KCORE_TEXT
1642 depends on X86_64 && PROC_KCORE
1644 config ILLEGAL_POINTER_VALUE
1647 default 0xdead000000000000 if X86_64
1651 config X86_PMEM_LEGACY_DEVICE
1654 config X86_PMEM_LEGACY
1655 tristate "Support non-standard NVDIMMs and ADR protected memory"
1656 depends on PHYS_ADDR_T_64BIT
1658 select X86_PMEM_LEGACY_DEVICE
1661 Treat memory marked using the non-standard e820 type of 12 as used
1662 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1663 The kernel will offer these regions to the 'pmem' driver so
1664 they can be used for persistent storage.
1669 bool "Allocate 3rd-level pagetables from highmem"
1672 The VM uses one page table entry for each page of physical memory.
1673 For systems with a lot of RAM, this can be wasteful of precious
1674 low memory. Setting this option will put user-space page table
1675 entries in high memory.
1677 config X86_CHECK_BIOS_CORRUPTION
1678 bool "Check for low memory corruption"
1680 Periodically check for memory corruption in low memory, which
1681 is suspected to be caused by BIOS. Even when enabled in the
1682 configuration, it is disabled at runtime. Enable it by
1683 setting "memory_corruption_check=1" on the kernel command
1684 line. By default it scans the low 64k of memory every 60
1685 seconds; see the memory_corruption_check_size and
1686 memory_corruption_check_period parameters in
1687 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1689 When enabled with the default parameters, this option has
1690 almost no overhead, as it reserves a relatively small amount
1691 of memory and scans it infrequently. It both detects corruption
1692 and prevents it from affecting the running system.
1694 It is, however, intended as a diagnostic tool; if repeatable
1695 BIOS-originated corruption always affects the same memory,
1696 you can use memmap= to prevent the kernel from using that
1699 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1700 bool "Set the default setting of memory_corruption_check"
1701 depends on X86_CHECK_BIOS_CORRUPTION
1704 Set whether the default state of memory_corruption_check is
1707 config X86_RESERVE_LOW
1708 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1712 Specify the amount of low memory to reserve for the BIOS.
1714 The first page contains BIOS data structures that the kernel
1715 must not use, so that page must always be reserved.
1717 By default we reserve the first 64K of physical RAM, as a
1718 number of BIOSes are known to corrupt that memory range
1719 during events such as suspend/resume or monitor cable
1720 insertion, so it must not be used by the kernel.
1722 You can set this to 4 if you are absolutely sure that you
1723 trust the BIOS to get all its memory reservations and usages
1724 right. If you know your BIOS have problems beyond the
1725 default 64K area, you can set this to 640 to avoid using the
1726 entire low memory range.
1728 If you have doubts about the BIOS (e.g. suspend/resume does
1729 not work or there's kernel crashes after certain hardware
1730 hotplug events) then you might want to enable
1731 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1732 typical corruption patterns.
1734 Leave this to the default value of 64 if you are unsure.
1736 config MATH_EMULATION
1738 depends on MODIFY_LDT_SYSCALL
1739 prompt "Math emulation" if X86_32
1741 Linux can emulate a math coprocessor (used for floating point
1742 operations) if you don't have one. 486DX and Pentium processors have
1743 a math coprocessor built in, 486SX and 386 do not, unless you added
1744 a 487DX or 387, respectively. (The messages during boot time can
1745 give you some hints here ["man dmesg"].) Everyone needs either a
1746 coprocessor or this emulation.
1748 If you don't have a math coprocessor, you need to say Y here; if you
1749 say Y here even though you have a coprocessor, the coprocessor will
1750 be used nevertheless. (This behavior can be changed with the kernel
1751 command line option "no387", which comes handy if your coprocessor
1752 is broken. Try "man bootparam" or see the documentation of your boot
1753 loader (lilo or loadlin) about how to pass options to the kernel at
1754 boot time.) This means that it is a good idea to say Y here if you
1755 intend to use this kernel on different machines.
1757 More information about the internals of the Linux math coprocessor
1758 emulation can be found in <file:arch/x86/math-emu/README>.
1760 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1761 kernel, it won't hurt.
1765 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1767 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1768 the Memory Type Range Registers (MTRRs) may be used to control
1769 processor access to memory ranges. This is most useful if you have
1770 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1771 allows bus write transfers to be combined into a larger transfer
1772 before bursting over the PCI/AGP bus. This can increase performance
1773 of image write operations 2.5 times or more. Saying Y here creates a
1774 /proc/mtrr file which may be used to manipulate your processor's
1775 MTRRs. Typically the X server should use this.
1777 This code has a reasonably generic interface so that similar
1778 control registers on other processors can be easily supported
1781 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1782 Registers (ARRs) which provide a similar functionality to MTRRs. For
1783 these, the ARRs are used to emulate the MTRRs.
1784 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1785 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1786 write-combining. All of these processors are supported by this code
1787 and it makes sense to say Y here if you have one of them.
1789 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1790 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1791 can lead to all sorts of problems, so it's good to say Y here.
1793 You can safely say Y even if your machine doesn't have MTRRs, you'll
1794 just add about 9 KB to your kernel.
1796 See <file:Documentation/x86/mtrr.txt> for more information.
1798 config MTRR_SANITIZER
1800 prompt "MTRR cleanup support"
1803 Convert MTRR layout from continuous to discrete, so X drivers can
1804 add writeback entries.
1806 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1807 The largest mtrr entry size for a continuous block can be set with
1812 config MTRR_SANITIZER_ENABLE_DEFAULT
1813 int "MTRR cleanup enable value (0-1)"
1816 depends on MTRR_SANITIZER
1818 Enable mtrr cleanup default value
1820 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1821 int "MTRR cleanup spare reg num (0-7)"
1824 depends on MTRR_SANITIZER
1826 mtrr cleanup spare entries default, it can be changed via
1827 mtrr_spare_reg_nr=N on the kernel command line.
1831 prompt "x86 PAT support" if EXPERT
1834 Use PAT attributes to setup page level cache control.
1836 PATs are the modern equivalents of MTRRs and are much more
1837 flexible than MTRRs.
1839 Say N here if you see bootup problems (boot crash, boot hang,
1840 spontaneous reboots) or a non-working video driver.
1844 config ARCH_USES_PG_UNCACHED
1850 prompt "x86 architectural random number generator" if EXPERT
1852 Enable the x86 architectural RDRAND instruction
1853 (Intel Bull Mountain technology) to generate random numbers.
1854 If supported, this is a high bandwidth, cryptographically
1855 secure hardware random number generator.
1859 prompt "Supervisor Mode Access Prevention" if EXPERT
1861 Supervisor Mode Access Prevention (SMAP) is a security
1862 feature in newer Intel processors. There is a small
1863 performance cost if this enabled and turned on; there is
1864 also a small increase in the kernel size if this is enabled.
1868 config X86_INTEL_UMIP
1870 depends on CPU_SUP_INTEL
1871 prompt "Intel User Mode Instruction Prevention" if EXPERT
1873 The User Mode Instruction Prevention (UMIP) is a security
1874 feature in newer Intel processors. If enabled, a general
1875 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1876 or STR instructions are executed in user mode. These instructions
1877 unnecessarily expose information about the hardware state.
1879 The vast majority of applications do not use these instructions.
1880 For the very few that do, software emulation is provided in
1881 specific cases in protected and virtual-8086 modes. Emulated
1884 config X86_INTEL_MPX
1885 prompt "Intel MPX (Memory Protection Extensions)"
1887 # Note: only available in 64-bit mode due to VMA flags shortage
1888 depends on CPU_SUP_INTEL && X86_64
1889 select ARCH_USES_HIGH_VMA_FLAGS
1891 MPX provides hardware features that can be used in
1892 conjunction with compiler-instrumented code to check
1893 memory references. It is designed to detect buffer
1894 overflow or underflow bugs.
1896 This option enables running applications which are
1897 instrumented or otherwise use MPX. It does not use MPX
1898 itself inside the kernel or to protect the kernel
1899 against bad memory references.
1901 Enabling this option will make the kernel larger:
1902 ~8k of kernel text and 36 bytes of data on a 64-bit
1903 defconfig. It adds a long to the 'mm_struct' which
1904 will increase the kernel memory overhead of each
1905 process and adds some branches to paths used during
1906 exec() and munmap().
1908 For details, see Documentation/x86/intel_mpx.txt
1912 config X86_INTEL_MEMORY_PROTECTION_KEYS
1913 prompt "Intel Memory Protection Keys"
1915 # Note: only available in 64-bit mode
1916 depends on CPU_SUP_INTEL && X86_64
1917 select ARCH_USES_HIGH_VMA_FLAGS
1918 select ARCH_HAS_PKEYS
1920 Memory Protection Keys provides a mechanism for enforcing
1921 page-based protections, but without requiring modification of the
1922 page tables when an application changes protection domains.
1924 For details, see Documentation/x86/protection-keys.txt
1929 bool "EFI runtime service support"
1932 select EFI_RUNTIME_WRAPPERS
1934 This enables the kernel to use EFI runtime services that are
1935 available (such as the EFI variable services).
1937 This option is only useful on systems that have EFI firmware.
1938 In addition, you should use the latest ELILO loader available
1939 at <http://elilo.sourceforge.net> in order to take advantage
1940 of EFI runtime services. However, even with this option, the
1941 resultant kernel should continue to boot on existing non-EFI
1945 bool "EFI stub support"
1946 depends on EFI && !X86_USE_3DNOW
1949 This kernel feature allows a bzImage to be loaded directly
1950 by EFI firmware without the use of a bootloader.
1952 See Documentation/efi-stub.txt for more information.
1955 bool "EFI mixed-mode support"
1956 depends on EFI_STUB && X86_64
1958 Enabling this feature allows a 64-bit kernel to be booted
1959 on a 32-bit firmware, provided that your CPU supports 64-bit
1962 Note that it is not possible to boot a mixed-mode enabled
1963 kernel via the EFI boot stub - a bootloader that supports
1964 the EFI handover protocol must be used.
1970 prompt "Enable seccomp to safely compute untrusted bytecode"
1972 This kernel feature is useful for number crunching applications
1973 that may need to compute untrusted bytecode during their
1974 execution. By using pipes or other transports made available to
1975 the process as file descriptors supporting the read/write
1976 syscalls, it's possible to isolate those applications in
1977 their own address space using seccomp. Once seccomp is
1978 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1979 and the task is only allowed to execute a few safe syscalls
1980 defined by each seccomp mode.
1982 If unsure, say Y. Only embedded should say N here.
1984 source kernel/Kconfig.hz
1987 bool "kexec system call"
1990 kexec is a system call that implements the ability to shutdown your
1991 current kernel, and to start another kernel. It is like a reboot
1992 but it is independent of the system firmware. And like a reboot
1993 you can start any kernel with it, not just Linux.
1995 The name comes from the similarity to the exec system call.
1997 It is an ongoing process to be certain the hardware in a machine
1998 is properly shutdown, so do not be surprised if this code does not
1999 initially work for you. As of this writing the exact hardware
2000 interface is strongly in flux, so no good recommendation can be
2004 bool "kexec file based system call"
2009 depends on CRYPTO_SHA256=y
2011 This is new version of kexec system call. This system call is
2012 file based and takes file descriptors as system call argument
2013 for kernel and initramfs as opposed to list of segments as
2014 accepted by previous system call.
2016 config ARCH_HAS_KEXEC_PURGATORY
2019 config KEXEC_VERIFY_SIG
2020 bool "Verify kernel signature during kexec_file_load() syscall"
2021 depends on KEXEC_FILE
2023 This option makes kernel signature verification mandatory for
2024 the kexec_file_load() syscall.
2026 In addition to that option, you need to enable signature
2027 verification for the corresponding kernel image type being
2028 loaded in order for this to work.
2030 config KEXEC_BZIMAGE_VERIFY_SIG
2031 bool "Enable bzImage signature verification support"
2032 depends on KEXEC_VERIFY_SIG
2033 depends on SIGNED_PE_FILE_VERIFICATION
2034 select SYSTEM_TRUSTED_KEYRING
2036 Enable bzImage signature verification support.
2039 bool "kernel crash dumps"
2040 depends on X86_64 || (X86_32 && HIGHMEM)
2042 Generate crash dump after being started by kexec.
2043 This should be normally only set in special crash dump kernels
2044 which are loaded in the main kernel with kexec-tools into
2045 a specially reserved region and then later executed after
2046 a crash by kdump/kexec. The crash dump kernel must be compiled
2047 to a memory address not used by the main kernel or BIOS using
2048 PHYSICAL_START, or it must be built as a relocatable image
2049 (CONFIG_RELOCATABLE=y).
2050 For more details see Documentation/kdump/kdump.txt
2054 depends on KEXEC && HIBERNATION
2056 Jump between original kernel and kexeced kernel and invoke
2057 code in physical address mode via KEXEC
2059 config PHYSICAL_START
2060 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2063 This gives the physical address where the kernel is loaded.
2065 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2066 bzImage will decompress itself to above physical address and
2067 run from there. Otherwise, bzImage will run from the address where
2068 it has been loaded by the boot loader and will ignore above physical
2071 In normal kdump cases one does not have to set/change this option
2072 as now bzImage can be compiled as a completely relocatable image
2073 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2074 address. This option is mainly useful for the folks who don't want
2075 to use a bzImage for capturing the crash dump and want to use a
2076 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2077 to be specifically compiled to run from a specific memory area
2078 (normally a reserved region) and this option comes handy.
2080 So if you are using bzImage for capturing the crash dump,
2081 leave the value here unchanged to 0x1000000 and set
2082 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2083 for capturing the crash dump change this value to start of
2084 the reserved region. In other words, it can be set based on
2085 the "X" value as specified in the "crashkernel=YM@XM"
2086 command line boot parameter passed to the panic-ed
2087 kernel. Please take a look at Documentation/kdump/kdump.txt
2088 for more details about crash dumps.
2090 Usage of bzImage for capturing the crash dump is recommended as
2091 one does not have to build two kernels. Same kernel can be used
2092 as production kernel and capture kernel. Above option should have
2093 gone away after relocatable bzImage support is introduced. But it
2094 is present because there are users out there who continue to use
2095 vmlinux for dump capture. This option should go away down the
2098 Don't change this unless you know what you are doing.
2101 bool "Build a relocatable kernel"
2104 This builds a kernel image that retains relocation information
2105 so it can be loaded someplace besides the default 1MB.
2106 The relocations tend to make the kernel binary about 10% larger,
2107 but are discarded at runtime.
2109 One use is for the kexec on panic case where the recovery kernel
2110 must live at a different physical address than the primary
2113 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2114 it has been loaded at and the compile time physical address
2115 (CONFIG_PHYSICAL_START) is used as the minimum location.
2117 config RANDOMIZE_BASE
2118 bool "Randomize the address of the kernel image (KASLR)"
2119 depends on RELOCATABLE
2122 In support of Kernel Address Space Layout Randomization (KASLR),
2123 this randomizes the physical address at which the kernel image
2124 is decompressed and the virtual address where the kernel
2125 image is mapped, as a security feature that deters exploit
2126 attempts relying on knowledge of the location of kernel
2129 On 64-bit, the kernel physical and virtual addresses are
2130 randomized separately. The physical address will be anywhere
2131 between 16MB and the top of physical memory (up to 64TB). The
2132 virtual address will be randomized from 16MB up to 1GB (9 bits
2133 of entropy). Note that this also reduces the memory space
2134 available to kernel modules from 1.5GB to 1GB.
2136 On 32-bit, the kernel physical and virtual addresses are
2137 randomized together. They will be randomized from 16MB up to
2138 512MB (8 bits of entropy).
2140 Entropy is generated using the RDRAND instruction if it is
2141 supported. If RDTSC is supported, its value is mixed into
2142 the entropy pool as well. If neither RDRAND nor RDTSC are
2143 supported, then entropy is read from the i8254 timer. The
2144 usable entropy is limited by the kernel being built using
2145 2GB addressing, and that PHYSICAL_ALIGN must be at a
2146 minimum of 2MB. As a result, only 10 bits of entropy are
2147 theoretically possible, but the implementations are further
2148 limited due to memory layouts.
2152 # Relocation on x86 needs some additional build support
2153 config X86_NEED_RELOCS
2155 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2157 config PHYSICAL_ALIGN
2158 hex "Alignment value to which kernel should be aligned"
2160 range 0x2000 0x1000000 if X86_32
2161 range 0x200000 0x1000000 if X86_64
2163 This value puts the alignment restrictions on physical address
2164 where kernel is loaded and run from. Kernel is compiled for an
2165 address which meets above alignment restriction.
2167 If bootloader loads the kernel at a non-aligned address and
2168 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2169 address aligned to above value and run from there.
2171 If bootloader loads the kernel at a non-aligned address and
2172 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2173 load address and decompress itself to the address it has been
2174 compiled for and run from there. The address for which kernel is
2175 compiled already meets above alignment restrictions. Hence the
2176 end result is that kernel runs from a physical address meeting
2177 above alignment restrictions.
2179 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2180 this value must be a multiple of 0x200000.
2182 Don't change this unless you know what you are doing.
2184 config DYNAMIC_MEMORY_LAYOUT
2187 This option makes base addresses of vmalloc and vmemmap as well as
2188 __PAGE_OFFSET movable during boot.
2190 config RANDOMIZE_MEMORY
2191 bool "Randomize the kernel memory sections"
2193 depends on RANDOMIZE_BASE
2194 select DYNAMIC_MEMORY_LAYOUT
2195 default RANDOMIZE_BASE
2197 Randomizes the base virtual address of kernel memory sections
2198 (physical memory mapping, vmalloc & vmemmap). This security feature
2199 makes exploits relying on predictable memory locations less reliable.
2201 The order of allocations remains unchanged. Entropy is generated in
2202 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2203 configuration have in average 30,000 different possible virtual
2204 addresses for each memory section.
2208 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2209 hex "Physical memory mapping padding" if EXPERT
2210 depends on RANDOMIZE_MEMORY
2211 default "0xa" if MEMORY_HOTPLUG
2213 range 0x1 0x40 if MEMORY_HOTPLUG
2216 Define the padding in terabytes added to the existing physical
2217 memory size during kernel memory randomization. It is useful
2218 for memory hotplug support but reduces the entropy available for
2219 address randomization.
2221 If unsure, leave at the default value.
2224 bool "Support for hot-pluggable CPUs"
2227 Say Y here to allow turning CPUs off and on. CPUs can be
2228 controlled through /sys/devices/system/cpu.
2229 ( Note: power management support will enable this option
2230 automatically on SMP systems. )
2231 Say N if you want to disable CPU hotplug.
2233 config BOOTPARAM_HOTPLUG_CPU0
2234 bool "Set default setting of cpu0_hotpluggable"
2236 depends on HOTPLUG_CPU
2238 Set whether default state of cpu0_hotpluggable is on or off.
2240 Say Y here to enable CPU0 hotplug by default. If this switch
2241 is turned on, there is no need to give cpu0_hotplug kernel
2242 parameter and the CPU0 hotplug feature is enabled by default.
2244 Please note: there are two known CPU0 dependencies if you want
2245 to enable the CPU0 hotplug feature either by this switch or by
2246 cpu0_hotplug kernel parameter.
2248 First, resume from hibernate or suspend always starts from CPU0.
2249 So hibernate and suspend are prevented if CPU0 is offline.
2251 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2252 offline if any interrupt can not migrate out of CPU0. There may
2253 be other CPU0 dependencies.
2255 Please make sure the dependencies are under your control before
2256 you enable this feature.
2258 Say N if you don't want to enable CPU0 hotplug feature by default.
2259 You still can enable the CPU0 hotplug feature at boot by kernel
2260 parameter cpu0_hotplug.
2262 config DEBUG_HOTPLUG_CPU0
2264 prompt "Debug CPU0 hotplug"
2265 depends on HOTPLUG_CPU
2267 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2268 soon as possible and boots up userspace with CPU0 offlined. User
2269 can online CPU0 back after boot time.
2271 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2272 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2273 compilation or giving cpu0_hotplug kernel parameter at boot.
2279 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2280 depends on COMPAT_32
2282 Certain buggy versions of glibc will crash if they are
2283 presented with a 32-bit vDSO that is not mapped at the address
2284 indicated in its segment table.
2286 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2287 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2288 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2289 the only released version with the bug, but OpenSUSE 9
2290 contains a buggy "glibc 2.3.2".
2292 The symptom of the bug is that everything crashes on startup, saying:
2293 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2295 Saying Y here changes the default value of the vdso32 boot
2296 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2297 This works around the glibc bug but hurts performance.
2299 If unsure, say N: if you are compiling your own kernel, you
2300 are unlikely to be using a buggy version of glibc.
2303 prompt "vsyscall table for legacy applications"
2305 default LEGACY_VSYSCALL_EMULATE
2307 Legacy user code that does not know how to find the vDSO expects
2308 to be able to issue three syscalls by calling fixed addresses in
2309 kernel space. Since this location is not randomized with ASLR,
2310 it can be used to assist security vulnerability exploitation.
2312 This setting can be changed at boot time via the kernel command
2313 line parameter vsyscall=[emulate|none].
2315 On a system with recent enough glibc (2.14 or newer) and no
2316 static binaries, you can say None without a performance penalty
2317 to improve security.
2319 If unsure, select "Emulate".
2321 config LEGACY_VSYSCALL_EMULATE
2324 The kernel traps and emulates calls into the fixed
2325 vsyscall address mapping. This makes the mapping
2326 non-executable, but it still contains known contents,
2327 which could be used in certain rare security vulnerability
2328 exploits. This configuration is recommended when userspace
2329 still uses the vsyscall area.
2331 config LEGACY_VSYSCALL_NONE
2334 There will be no vsyscall mapping at all. This will
2335 eliminate any risk of ASLR bypass due to the vsyscall
2336 fixed address mapping. Attempts to use the vsyscalls
2337 will be reported to dmesg, so that either old or
2338 malicious userspace programs can be identified.
2343 bool "Built-in kernel command line"
2345 Allow for specifying boot arguments to the kernel at
2346 build time. On some systems (e.g. embedded ones), it is
2347 necessary or convenient to provide some or all of the
2348 kernel boot arguments with the kernel itself (that is,
2349 to not rely on the boot loader to provide them.)
2351 To compile command line arguments into the kernel,
2352 set this option to 'Y', then fill in the
2353 boot arguments in CONFIG_CMDLINE.
2355 Systems with fully functional boot loaders (i.e. non-embedded)
2356 should leave this option set to 'N'.
2359 string "Built-in kernel command string"
2360 depends on CMDLINE_BOOL
2363 Enter arguments here that should be compiled into the kernel
2364 image and used at boot time. If the boot loader provides a
2365 command line at boot time, it is appended to this string to
2366 form the full kernel command line, when the system boots.
2368 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2369 change this behavior.
2371 In most cases, the command line (whether built-in or provided
2372 by the boot loader) should specify the device for the root
2375 config CMDLINE_OVERRIDE
2376 bool "Built-in command line overrides boot loader arguments"
2377 depends on CMDLINE_BOOL
2379 Set this option to 'Y' to have the kernel ignore the boot loader
2380 command line, and use ONLY the built-in command line.
2382 This is used to work around broken boot loaders. This should
2383 be set to 'N' under normal conditions.
2385 config MODIFY_LDT_SYSCALL
2386 bool "Enable the LDT (local descriptor table)" if EXPERT
2389 Linux can allow user programs to install a per-process x86
2390 Local Descriptor Table (LDT) using the modify_ldt(2) system
2391 call. This is required to run 16-bit or segmented code such as
2392 DOSEMU or some Wine programs. It is also used by some very old
2393 threading libraries.
2395 Enabling this feature adds a small amount of overhead to
2396 context switches and increases the low-level kernel attack
2397 surface. Disabling it removes the modify_ldt(2) system call.
2399 Saying 'N' here may make sense for embedded or server kernels.
2401 source "kernel/livepatch/Kconfig"
2405 config ARCH_HAS_ADD_PAGES
2407 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2409 config ARCH_ENABLE_MEMORY_HOTPLUG
2411 depends on X86_64 || (X86_32 && HIGHMEM)
2413 config ARCH_ENABLE_MEMORY_HOTREMOVE
2415 depends on MEMORY_HOTPLUG
2417 config USE_PERCPU_NUMA_NODE_ID
2421 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2423 depends on X86_64 || X86_PAE
2425 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2427 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2429 config ARCH_ENABLE_THP_MIGRATION
2431 depends on X86_64 && TRANSPARENT_HUGEPAGE
2433 menu "Power management and ACPI options"
2435 config ARCH_HIBERNATION_HEADER
2437 depends on X86_64 && HIBERNATION
2439 source "kernel/power/Kconfig"
2441 source "drivers/acpi/Kconfig"
2443 source "drivers/sfi/Kconfig"
2450 tristate "APM (Advanced Power Management) BIOS support"
2451 depends on X86_32 && PM_SLEEP
2453 APM is a BIOS specification for saving power using several different
2454 techniques. This is mostly useful for battery powered laptops with
2455 APM compliant BIOSes. If you say Y here, the system time will be
2456 reset after a RESUME operation, the /proc/apm device will provide
2457 battery status information, and user-space programs will receive
2458 notification of APM "events" (e.g. battery status change).
2460 If you select "Y" here, you can disable actual use of the APM
2461 BIOS by passing the "apm=off" option to the kernel at boot time.
2463 Note that the APM support is almost completely disabled for
2464 machines with more than one CPU.
2466 In order to use APM, you will need supporting software. For location
2467 and more information, read <file:Documentation/power/apm-acpi.txt>
2468 and the Battery Powered Linux mini-HOWTO, available from
2469 <http://www.tldp.org/docs.html#howto>.
2471 This driver does not spin down disk drives (see the hdparm(8)
2472 manpage ("man 8 hdparm") for that), and it doesn't turn off
2473 VESA-compliant "green" monitors.
2475 This driver does not support the TI 4000M TravelMate and the ACER
2476 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2477 desktop machines also don't have compliant BIOSes, and this driver
2478 may cause those machines to panic during the boot phase.
2480 Generally, if you don't have a battery in your machine, there isn't
2481 much point in using this driver and you should say N. If you get
2482 random kernel OOPSes or reboots that don't seem to be related to
2483 anything, try disabling/enabling this option (or disabling/enabling
2486 Some other things you should try when experiencing seemingly random,
2489 1) make sure that you have enough swap space and that it is
2491 2) pass the "no-hlt" option to the kernel
2492 3) switch on floating point emulation in the kernel and pass
2493 the "no387" option to the kernel
2494 4) pass the "floppy=nodma" option to the kernel
2495 5) pass the "mem=4M" option to the kernel (thereby disabling
2496 all but the first 4 MB of RAM)
2497 6) make sure that the CPU is not over clocked.
2498 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2499 8) disable the cache from your BIOS settings
2500 9) install a fan for the video card or exchange video RAM
2501 10) install a better fan for the CPU
2502 11) exchange RAM chips
2503 12) exchange the motherboard.
2505 To compile this driver as a module, choose M here: the
2506 module will be called apm.
2510 config APM_IGNORE_USER_SUSPEND
2511 bool "Ignore USER SUSPEND"
2513 This option will ignore USER SUSPEND requests. On machines with a
2514 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2515 series notebooks, it is necessary to say Y because of a BIOS bug.
2517 config APM_DO_ENABLE
2518 bool "Enable PM at boot time"
2520 Enable APM features at boot time. From page 36 of the APM BIOS
2521 specification: "When disabled, the APM BIOS does not automatically
2522 power manage devices, enter the Standby State, enter the Suspend
2523 State, or take power saving steps in response to CPU Idle calls."
2524 This driver will make CPU Idle calls when Linux is idle (unless this
2525 feature is turned off -- see "Do CPU IDLE calls", below). This
2526 should always save battery power, but more complicated APM features
2527 will be dependent on your BIOS implementation. You may need to turn
2528 this option off if your computer hangs at boot time when using APM
2529 support, or if it beeps continuously instead of suspending. Turn
2530 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2531 T400CDT. This is off by default since most machines do fine without
2536 bool "Make CPU Idle calls when idle"
2538 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2539 On some machines, this can activate improved power savings, such as
2540 a slowed CPU clock rate, when the machine is idle. These idle calls
2541 are made after the idle loop has run for some length of time (e.g.,
2542 333 mS). On some machines, this will cause a hang at boot time or
2543 whenever the CPU becomes idle. (On machines with more than one CPU,
2544 this option does nothing.)
2546 config APM_DISPLAY_BLANK
2547 bool "Enable console blanking using APM"
2549 Enable console blanking using the APM. Some laptops can use this to
2550 turn off the LCD backlight when the screen blanker of the Linux
2551 virtual console blanks the screen. Note that this is only used by
2552 the virtual console screen blanker, and won't turn off the backlight
2553 when using the X Window system. This also doesn't have anything to
2554 do with your VESA-compliant power-saving monitor. Further, this
2555 option doesn't work for all laptops -- it might not turn off your
2556 backlight at all, or it might print a lot of errors to the console,
2557 especially if you are using gpm.
2559 config APM_ALLOW_INTS
2560 bool "Allow interrupts during APM BIOS calls"
2562 Normally we disable external interrupts while we are making calls to
2563 the APM BIOS as a measure to lessen the effects of a badly behaving
2564 BIOS implementation. The BIOS should reenable interrupts if it
2565 needs to. Unfortunately, some BIOSes do not -- especially those in
2566 many of the newer IBM Thinkpads. If you experience hangs when you
2567 suspend, try setting this to Y. Otherwise, say N.
2571 source "drivers/cpufreq/Kconfig"
2573 source "drivers/cpuidle/Kconfig"
2575 source "drivers/idle/Kconfig"
2580 menu "Bus options (PCI etc.)"
2586 Find out whether you have a PCI motherboard. PCI is the name of a
2587 bus system, i.e. the way the CPU talks to the other stuff inside
2588 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2589 VESA. If you have PCI, say Y, otherwise N.
2592 prompt "PCI access mode"
2593 depends on X86_32 && PCI
2596 On PCI systems, the BIOS can be used to detect the PCI devices and
2597 determine their configuration. However, some old PCI motherboards
2598 have BIOS bugs and may crash if this is done. Also, some embedded
2599 PCI-based systems don't have any BIOS at all. Linux can also try to
2600 detect the PCI hardware directly without using the BIOS.
2602 With this option, you can specify how Linux should detect the
2603 PCI devices. If you choose "BIOS", the BIOS will be used,
2604 if you choose "Direct", the BIOS won't be used, and if you
2605 choose "MMConfig", then PCI Express MMCONFIG will be used.
2606 If you choose "Any", the kernel will try MMCONFIG, then the
2607 direct access method and falls back to the BIOS if that doesn't
2608 work. If unsure, go with the default, which is "Any".
2613 config PCI_GOMMCONFIG
2630 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2632 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2635 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2638 bool "Support mmconfig PCI config space access" if X86_64
2640 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2641 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2645 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2649 depends on PCI && XEN
2656 config MMCONF_FAM10H
2658 depends on X86_64 && PCI_MMCONFIG && ACPI
2660 config PCI_CNB20LE_QUIRK
2661 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2664 Read the PCI windows out of the CNB20LE host bridge. This allows
2665 PCI hotplug to work on systems with the CNB20LE chipset which do
2668 There's no public spec for this chipset, and this functionality
2669 is known to be incomplete.
2671 You should say N unless you know you need this.
2673 source "drivers/pci/Kconfig"
2676 bool "ISA bus support on modern systems" if EXPERT
2678 Expose ISA bus device drivers and options available for selection and
2679 configuration. Enable this option if your target machine has an ISA
2680 bus. ISA is an older system, displaced by PCI and newer bus
2681 architectures -- if your target machine is modern, it probably does
2682 not have an ISA bus.
2686 # x86_64 have no ISA slots, but can have ISA-style DMA.
2688 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2691 Enables ISA-style DMA support for devices requiring such controllers.
2699 Find out whether you have ISA slots on your motherboard. ISA is the
2700 name of a bus system, i.e. the way the CPU talks to the other stuff
2701 inside your box. Other bus systems are PCI, EISA, MicroChannel
2702 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2703 newer boards don't support it. If you have ISA, say Y, otherwise N.
2709 The Extended Industry Standard Architecture (EISA) bus was
2710 developed as an open alternative to the IBM MicroChannel bus.
2712 The EISA bus provided some of the features of the IBM MicroChannel
2713 bus while maintaining backward compatibility with cards made for
2714 the older ISA bus. The EISA bus saw limited use between 1988 and
2715 1995 when it was made obsolete by the PCI bus.
2717 Say Y here if you are building a kernel for an EISA-based machine.
2721 source "drivers/eisa/Kconfig"
2724 tristate "NatSemi SCx200 support"
2726 This provides basic support for National Semiconductor's
2727 (now AMD's) Geode processors. The driver probes for the
2728 PCI-IDs of several on-chip devices, so its a good dependency
2729 for other scx200_* drivers.
2731 If compiled as a module, the driver is named scx200.
2733 config SCx200HR_TIMER
2734 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2738 This driver provides a clocksource built upon the on-chip
2739 27MHz high-resolution timer. Its also a workaround for
2740 NSC Geode SC-1100's buggy TSC, which loses time when the
2741 processor goes idle (as is done by the scheduler). The
2742 other workaround is idle=poll boot option.
2745 bool "One Laptop Per Child support"
2752 Add support for detecting the unique features of the OLPC
2756 bool "OLPC XO-1 Power Management"
2757 depends on OLPC && MFD_CS5535 && PM_SLEEP
2760 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2763 bool "OLPC XO-1 Real Time Clock"
2764 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2766 Add support for the XO-1 real time clock, which can be used as a
2767 programmable wakeup source.
2770 bool "OLPC XO-1 SCI extras"
2771 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2775 Add support for SCI-based features of the OLPC XO-1 laptop:
2776 - EC-driven system wakeups
2780 - AC adapter status updates
2781 - Battery status updates
2783 config OLPC_XO15_SCI
2784 bool "OLPC XO-1.5 SCI extras"
2785 depends on OLPC && ACPI
2788 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2789 - EC-driven system wakeups
2790 - AC adapter status updates
2791 - Battery status updates
2794 bool "PCEngines ALIX System Support (LED setup)"
2797 This option enables system support for the PCEngines ALIX.
2798 At present this just sets up LEDs for GPIO control on
2799 ALIX2/3/6 boards. However, other system specific setup should
2802 Note: You must still enable the drivers for GPIO and LED support
2803 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2805 Note: You have to set alix.force=1 for boards with Award BIOS.
2808 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2811 This option enables system support for the Soekris Engineering net5501.
2814 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2818 This option enables system support for the Traverse Technologies GEOS.
2821 bool "Technologic Systems TS-5500 platform support"
2823 select CHECK_SIGNATURE
2827 This option enables system support for the Technologic Systems TS-5500.
2833 depends on CPU_SUP_AMD && PCI
2835 source "drivers/pcmcia/Kconfig"
2838 tristate "RapidIO support"
2842 If enabled this option will include drivers and the core
2843 infrastructure code to support RapidIO interconnect devices.
2845 source "drivers/rapidio/Kconfig"
2848 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2850 Firmwares often provide initial graphics framebuffers so the BIOS,
2851 bootloader or kernel can show basic video-output during boot for
2852 user-guidance and debugging. Historically, x86 used the VESA BIOS
2853 Extensions and EFI-framebuffers for this, which are mostly limited
2855 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2856 framebuffers so the new generic system-framebuffer drivers can be
2857 used on x86. If the framebuffer is not compatible with the generic
2858 modes, it is adverticed as fallback platform framebuffer so legacy
2859 drivers like efifb, vesafb and uvesafb can pick it up.
2860 If this option is not selected, all system framebuffers are always
2861 marked as fallback platform framebuffers as usual.
2863 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2864 not be able to pick up generic system framebuffers if this option
2865 is selected. You are highly encouraged to enable simplefb as
2866 replacement if you select this option. simplefb can correctly deal
2867 with generic system framebuffers. But you should still keep vesafb
2868 and others enabled as fallback if a system framebuffer is
2869 incompatible with simplefb.
2876 menu "Executable file formats / Emulations"
2878 source "fs/Kconfig.binfmt"
2880 config IA32_EMULATION
2881 bool "IA32 Emulation"
2883 select ARCH_WANT_OLD_COMPAT_IPC
2885 select COMPAT_BINFMT_ELF
2886 select COMPAT_OLD_SIGACTION
2888 Include code to run legacy 32-bit programs under a
2889 64-bit kernel. You should likely turn this on, unless you're
2890 100% sure that you don't have any 32-bit programs left.
2893 tristate "IA32 a.out support"
2894 depends on IA32_EMULATION
2896 Support old a.out binaries in the 32bit emulation.
2899 bool "x32 ABI for 64-bit mode"
2902 Include code to run binaries for the x32 native 32-bit ABI
2903 for 64-bit processors. An x32 process gets access to the
2904 full 64-bit register file and wide data path while leaving
2905 pointers at 32 bits for smaller memory footprint.
2907 You will need a recent binutils (2.22 or later) with
2908 elf32_x86_64 support enabled to compile a kernel with this
2913 depends on IA32_EMULATION || X86_32
2915 select OLD_SIGSUSPEND3
2919 depends on IA32_EMULATION || X86_X32
2922 config COMPAT_FOR_U64_ALIGNMENT
2925 config SYSVIPC_COMPAT
2933 config HAVE_ATOMIC_IOMAP
2937 config X86_DEV_DMA_OPS
2939 depends on X86_64 || STA2X11
2941 config X86_DMA_REMAP
2945 config HAVE_GENERIC_GUP
2948 source "net/Kconfig"
2950 source "drivers/Kconfig"
2952 source "drivers/firmware/Kconfig"
2956 source "arch/x86/Kconfig.debug"
2958 source "security/Kconfig"
2960 source "crypto/Kconfig"
2962 source "arch/x86/kvm/Kconfig"
2964 source "lib/Kconfig"