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_FORTIFY_SOURCE
56 select ARCH_HAS_GCOV_PROFILE_ALL
57 select ARCH_HAS_KCOV if X86_64
58 select ARCH_HAS_MEMBARRIER_SYNC_CORE
59 select ARCH_HAS_PMEM_API if X86_64
60 select ARCH_HAS_REFCOUNT
61 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
62 select ARCH_HAS_SET_MEMORY
63 select ARCH_HAS_SG_CHAIN
64 select ARCH_HAS_STRICT_KERNEL_RWX
65 select ARCH_HAS_STRICT_MODULE_RWX
66 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
67 select ARCH_HAS_UBSAN_SANITIZE_ALL
68 select ARCH_HAS_ZONE_DEVICE if X86_64
69 select ARCH_HAVE_NMI_SAFE_CMPXCHG
70 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
71 select ARCH_MIGHT_HAVE_PC_PARPORT
72 select ARCH_MIGHT_HAVE_PC_SERIO
73 select ARCH_SUPPORTS_ATOMIC_RMW
74 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
75 select ARCH_USE_BUILTIN_BSWAP
76 select ARCH_USE_QUEUED_RWLOCKS
77 select ARCH_USE_QUEUED_SPINLOCKS
78 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
79 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
80 select ARCH_WANTS_THP_SWAP if X86_64
81 select BUILDTIME_EXTABLE_SORT
83 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
84 select CLOCKSOURCE_WATCHDOG
85 select DCACHE_WORD_ACCESS
87 select EDAC_ATOMIC_SCRUB
89 select GENERIC_CLOCKEVENTS
90 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
91 select GENERIC_CLOCKEVENTS_MIN_ADJUST
92 select GENERIC_CMOS_UPDATE
93 select GENERIC_CPU_AUTOPROBE
94 select GENERIC_CPU_VULNERABILITIES
95 select GENERIC_EARLY_IOREMAP
96 select GENERIC_FIND_FIRST_BIT
98 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
99 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
100 select GENERIC_IRQ_MIGRATION if SMP
101 select GENERIC_IRQ_PROBE
102 select GENERIC_IRQ_RESERVATION_MODE
103 select GENERIC_IRQ_SHOW
104 select GENERIC_PENDING_IRQ if SMP
105 select GENERIC_SMP_IDLE_THREAD
106 select GENERIC_STRNCPY_FROM_USER
107 select GENERIC_STRNLEN_USER
108 select GENERIC_TIME_VSYSCALL
109 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
110 select HAVE_ACPI_APEI if ACPI
111 select HAVE_ACPI_APEI_NMI if ACPI
112 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
113 select HAVE_ARCH_AUDITSYSCALL
114 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
115 select HAVE_ARCH_JUMP_LABEL
116 select HAVE_ARCH_KASAN if X86_64
117 select HAVE_ARCH_KGDB
118 select HAVE_ARCH_MMAP_RND_BITS if MMU
119 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
120 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
121 select HAVE_ARCH_SECCOMP_FILTER
122 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
123 select HAVE_ARCH_TRACEHOOK
124 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
125 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
126 select HAVE_ARCH_VMAP_STACK if X86_64
127 select HAVE_ARCH_WITHIN_STACK_FRAMES
128 select HAVE_CC_STACKPROTECTOR
129 select HAVE_CMPXCHG_DOUBLE
130 select HAVE_CMPXCHG_LOCAL
131 select HAVE_CONTEXT_TRACKING if X86_64
132 select HAVE_COPY_THREAD_TLS
133 select HAVE_C_RECORDMCOUNT
134 select HAVE_DEBUG_KMEMLEAK
135 select HAVE_DEBUG_STACKOVERFLOW
136 select HAVE_DMA_API_DEBUG
137 select HAVE_DMA_CONTIGUOUS
138 select HAVE_DYNAMIC_FTRACE
139 select HAVE_DYNAMIC_FTRACE_WITH_REGS
140 select HAVE_EBPF_JIT if X86_64
141 select HAVE_EFFICIENT_UNALIGNED_ACCESS
142 select HAVE_EXIT_THREAD
143 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
144 select HAVE_FTRACE_MCOUNT_RECORD
145 select HAVE_FUNCTION_GRAPH_TRACER
146 select HAVE_FUNCTION_TRACER
147 select HAVE_GCC_PLUGINS
148 select HAVE_HW_BREAKPOINT
150 select HAVE_IOREMAP_PROT
151 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
152 select HAVE_IRQ_TIME_ACCOUNTING
153 select HAVE_KERNEL_BZIP2
154 select HAVE_KERNEL_GZIP
155 select HAVE_KERNEL_LZ4
156 select HAVE_KERNEL_LZMA
157 select HAVE_KERNEL_LZO
158 select HAVE_KERNEL_XZ
160 select HAVE_KPROBES_ON_FTRACE
161 select HAVE_FUNCTION_ERROR_INJECTION
162 select HAVE_KRETPROBES
164 select HAVE_LIVEPATCH if X86_64
166 select HAVE_MEMBLOCK_NODE_MAP
167 select HAVE_MIXED_BREAKPOINTS_REGS
168 select HAVE_MOD_ARCH_SPECIFIC
171 select HAVE_OPTPROBES
172 select HAVE_PCSPKR_PLATFORM
173 select HAVE_PERF_EVENTS
174 select HAVE_PERF_EVENTS_NMI
175 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
176 select HAVE_PERF_REGS
177 select HAVE_PERF_USER_STACK_DUMP
178 select HAVE_RCU_TABLE_FREE
179 select HAVE_REGS_AND_STACK_ACCESS_API
180 select HAVE_RELIABLE_STACKTRACE if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
181 select HAVE_STACK_VALIDATION if X86_64
182 select HAVE_SYSCALL_TRACEPOINTS
183 select HAVE_UNSTABLE_SCHED_CLOCK
184 select HAVE_USER_RETURN_NOTIFIER
185 select IRQ_FORCED_THREADING
186 select PCI_LOCKLESS_CONFIG
189 select RTC_MC146818_LIB
192 select SYSCTL_EXCEPTION_TRACE
193 select THREAD_INFO_IN_TASK
194 select USER_STACKTRACE_SUPPORT
196 select X86_FEATURE_NAMES if PROC_FS
198 config INSTRUCTION_DECODER
200 depends on KPROBES || PERF_EVENTS || UPROBES
204 default "elf32-i386" if X86_32
205 default "elf64-x86-64" if X86_64
207 config ARCH_DEFCONFIG
209 default "arch/x86/configs/i386_defconfig" if X86_32
210 default "arch/x86/configs/x86_64_defconfig" if X86_64
212 config LOCKDEP_SUPPORT
215 config STACKTRACE_SUPPORT
221 config ARCH_MMAP_RND_BITS_MIN
225 config ARCH_MMAP_RND_BITS_MAX
229 config ARCH_MMAP_RND_COMPAT_BITS_MIN
232 config ARCH_MMAP_RND_COMPAT_BITS_MAX
238 config NEED_DMA_MAP_STATE
240 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
242 config NEED_SG_DMA_LENGTH
245 config GENERIC_ISA_DMA
247 depends on ISA_DMA_API
252 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
254 config GENERIC_BUG_RELATIVE_POINTERS
257 config GENERIC_HWEIGHT
260 config ARCH_MAY_HAVE_PC_FDC
262 depends on ISA_DMA_API
264 config RWSEM_XCHGADD_ALGORITHM
267 config GENERIC_CALIBRATE_DELAY
270 config ARCH_HAS_CPU_RELAX
273 config ARCH_HAS_CACHE_LINE_SIZE
276 config HAVE_SETUP_PER_CPU_AREA
279 config NEED_PER_CPU_EMBED_FIRST_CHUNK
282 config NEED_PER_CPU_PAGE_FIRST_CHUNK
285 config ARCH_HIBERNATION_POSSIBLE
288 config ARCH_SUSPEND_POSSIBLE
291 config ARCH_WANT_HUGE_PMD_SHARE
294 config ARCH_WANT_GENERAL_HUGETLB
303 config ARCH_SUPPORTS_OPTIMIZED_INLINING
306 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
309 config KASAN_SHADOW_OFFSET
312 default 0xdffffc0000000000
314 config HAVE_INTEL_TXT
316 depends on INTEL_IOMMU && ACPI
320 depends on X86_32 && SMP
324 depends on X86_64 && SMP
326 config X86_32_LAZY_GS
328 depends on X86_32 && CC_STACKPROTECTOR_NONE
330 config ARCH_SUPPORTS_UPROBES
333 config FIX_EARLYCON_MEM
336 config PGTABLE_LEVELS
338 default 5 if X86_5LEVEL
343 source "init/Kconfig"
344 source "kernel/Kconfig.freezer"
346 menu "Processor type and features"
349 bool "DMA memory allocation support" if EXPERT
352 DMA memory allocation support allows devices with less than 32-bit
353 addressing to allocate within the first 16MB of address space.
354 Disable if no such devices will be used.
359 bool "Symmetric multi-processing support"
361 This enables support for systems with more than one CPU. If you have
362 a system with only one CPU, say N. If you have a system with more
365 If you say N here, the kernel will run on uni- and multiprocessor
366 machines, but will use only one CPU of a multiprocessor machine. If
367 you say Y here, the kernel will run on many, but not all,
368 uniprocessor machines. On a uniprocessor machine, the kernel
369 will run faster if you say N here.
371 Note that if you say Y here and choose architecture "586" or
372 "Pentium" under "Processor family", the kernel will not work on 486
373 architectures. Similarly, multiprocessor kernels for the "PPro"
374 architecture may not work on all Pentium based boards.
376 People using multiprocessor machines who say Y here should also say
377 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
378 Management" code will be disabled if you say Y here.
380 See also <file:Documentation/x86/i386/IO-APIC.txt>,
381 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
382 <http://www.tldp.org/docs.html#howto>.
384 If you don't know what to do here, say N.
386 config X86_FEATURE_NAMES
387 bool "Processor feature human-readable names" if EMBEDDED
390 This option compiles in a table of x86 feature bits and corresponding
391 names. This is required to support /proc/cpuinfo and a few kernel
392 messages. You can disable this to save space, at the expense of
393 making those few kernel messages show numeric feature bits instead.
398 bool "Support x2apic"
399 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
401 This enables x2apic support on CPUs that have this feature.
403 This allows 32-bit apic IDs (so it can support very large systems),
404 and accesses the local apic via MSRs not via mmio.
406 If you don't know what to do here, say N.
409 bool "Enable MPS table" if ACPI || SFI
411 depends on X86_LOCAL_APIC
413 For old smp systems that do not have proper acpi support. Newer systems
414 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
418 depends on X86_GOLDFISH
421 bool "Avoid speculative indirect branches in kernel"
423 select STACK_VALIDATION if HAVE_STACK_VALIDATION
425 Compile kernel with the retpoline compiler options to guard against
426 kernel-to-user data leaks by avoiding speculative indirect
427 branches. Requires a compiler with -mindirect-branch=thunk-extern
428 support for full protection. The kernel may run slower.
430 Without compiler support, at least indirect branches in assembler
431 code are eliminated. Since this includes the syscall entry path,
432 it is not entirely pointless.
435 bool "Intel Resource Director Technology support"
437 depends on X86 && CPU_SUP_INTEL
440 Select to enable resource allocation and monitoring which are
441 sub-features of Intel Resource Director Technology(RDT). More
442 information about RDT can be found in the Intel x86
443 Architecture Software Developer Manual.
449 bool "Support for big SMP systems with more than 8 CPUs"
452 This option is needed for the systems that have more than 8 CPUs
454 config X86_EXTENDED_PLATFORM
455 bool "Support for extended (non-PC) x86 platforms"
458 If you disable this option then the kernel will only support
459 standard PC platforms. (which covers the vast majority of
462 If you enable this option then you'll be able to select support
463 for the following (non-PC) 32 bit x86 platforms:
464 Goldfish (Android emulator)
467 SGI 320/540 (Visual Workstation)
468 STA2X11-based (e.g. Northville)
469 Moorestown MID devices
471 If you have one of these systems, or if you want to build a
472 generic distribution kernel, say Y here - otherwise say N.
476 config X86_EXTENDED_PLATFORM
477 bool "Support for extended (non-PC) x86 platforms"
480 If you disable this option then the kernel will only support
481 standard PC platforms. (which covers the vast majority of
484 If you enable this option then you'll be able to select support
485 for the following (non-PC) 64 bit x86 platforms:
490 If you have one of these systems, or if you want to build a
491 generic distribution kernel, say Y here - otherwise say N.
493 # This is an alphabetically sorted list of 64 bit extended platforms
494 # Please maintain the alphabetic order if and when there are additions
496 bool "Numascale NumaChip"
498 depends on X86_EXTENDED_PLATFORM
501 depends on X86_X2APIC
502 depends on PCI_MMCONFIG
504 Adds support for Numascale NumaChip large-SMP systems. Needed to
505 enable more than ~168 cores.
506 If you don't have one of these, you should say N here.
510 select HYPERVISOR_GUEST
512 depends on X86_64 && PCI
513 depends on X86_EXTENDED_PLATFORM
516 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
517 supposed to run on these EM64T-based machines. Only choose this option
518 if you have one of these machines.
521 bool "SGI Ultraviolet"
523 depends on X86_EXTENDED_PLATFORM
526 depends on X86_X2APIC
529 This option is needed in order to support SGI Ultraviolet systems.
530 If you don't have one of these, you should say N here.
532 # Following is an alphabetically sorted list of 32 bit extended platforms
533 # Please maintain the alphabetic order if and when there are additions
536 bool "Goldfish (Virtual Platform)"
537 depends on X86_EXTENDED_PLATFORM
539 Enable support for the Goldfish virtual platform used primarily
540 for Android development. Unless you are building for the Android
541 Goldfish emulator say N here.
544 bool "CE4100 TV platform"
546 depends on PCI_GODIRECT
547 depends on X86_IO_APIC
549 depends on X86_EXTENDED_PLATFORM
550 select X86_REBOOTFIXUPS
552 select OF_EARLY_FLATTREE
554 Select for the Intel CE media processor (CE4100) SOC.
555 This option compiles in support for the CE4100 SOC for settop
556 boxes and media devices.
559 bool "Intel MID platform support"
560 depends on X86_EXTENDED_PLATFORM
561 depends on X86_PLATFORM_DEVICES
563 depends on X86_64 || (PCI_GOANY && X86_32)
564 depends on X86_IO_APIC
570 select MFD_INTEL_MSIC
572 Select to build a kernel capable of supporting Intel MID (Mobile
573 Internet Device) platform systems which do not have the PCI legacy
574 interfaces. If you are building for a PC class system say N here.
576 Intel MID platforms are based on an Intel processor and chipset which
577 consume less power than most of the x86 derivatives.
579 config X86_INTEL_QUARK
580 bool "Intel Quark platform support"
582 depends on X86_EXTENDED_PLATFORM
583 depends on X86_PLATFORM_DEVICES
587 depends on X86_IO_APIC
592 Select to include support for Quark X1000 SoC.
593 Say Y here if you have a Quark based system such as the Arduino
594 compatible Intel Galileo.
596 config X86_INTEL_LPSS
597 bool "Intel Low Power Subsystem Support"
598 depends on X86 && ACPI
603 Select to build support for Intel Low Power Subsystem such as
604 found on Intel Lynxpoint PCH. Selecting this option enables
605 things like clock tree (common clock framework) and pincontrol
606 which are needed by the LPSS peripheral drivers.
608 config X86_AMD_PLATFORM_DEVICE
609 bool "AMD ACPI2Platform devices support"
614 Select to interpret AMD specific ACPI device to platform device
615 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
616 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
617 implemented under PINCTRL subsystem.
620 tristate "Intel SoC IOSF Sideband support for SoC platforms"
623 This option enables sideband register access support for Intel SoC
624 platforms. On these platforms the IOSF sideband is used in lieu of
625 MSR's for some register accesses, mostly but not limited to thermal
626 and power. Drivers may query the availability of this device to
627 determine if they need the sideband in order to work on these
628 platforms. The sideband is available on the following SoC products.
629 This list is not meant to be exclusive.
634 You should say Y if you are running a kernel on one of these SoC's.
636 config IOSF_MBI_DEBUG
637 bool "Enable IOSF sideband access through debugfs"
638 depends on IOSF_MBI && DEBUG_FS
640 Select this option to expose the IOSF sideband access registers (MCR,
641 MDR, MCRX) through debugfs to write and read register information from
642 different units on the SoC. This is most useful for obtaining device
643 state information for debug and analysis. As this is a general access
644 mechanism, users of this option would have specific knowledge of the
645 device they want to access.
647 If you don't require the option or are in doubt, say N.
650 bool "RDC R-321x SoC"
652 depends on X86_EXTENDED_PLATFORM
654 select X86_REBOOTFIXUPS
656 This option is needed for RDC R-321x system-on-chip, also known
658 If you don't have one of these chips, you should say N here.
660 config X86_32_NON_STANDARD
661 bool "Support non-standard 32-bit SMP architectures"
662 depends on X86_32 && SMP
663 depends on X86_EXTENDED_PLATFORM
665 This option compiles in the bigsmp and STA2X11 default
666 subarchitectures. It is intended for a generic binary
667 kernel. If you select them all, kernel will probe it one by
668 one and will fallback to default.
670 # Alphabetically sorted list of Non standard 32 bit platforms
672 config X86_SUPPORTS_MEMORY_FAILURE
674 # MCE code calls memory_failure():
676 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
677 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
678 depends on X86_64 || !SPARSEMEM
679 select ARCH_SUPPORTS_MEMORY_FAILURE
682 bool "STA2X11 Companion Chip Support"
683 depends on X86_32_NON_STANDARD && PCI
684 select ARCH_HAS_PHYS_TO_DMA
685 select X86_DEV_DMA_OPS
692 This adds support for boards based on the STA2X11 IO-Hub,
693 a.k.a. "ConneXt". The chip is used in place of the standard
694 PC chipset, so all "standard" peripherals are missing. If this
695 option is selected the kernel will still be able to boot on
696 standard PC machines.
699 tristate "Eurobraille/Iris poweroff module"
702 The Iris machines from EuroBraille do not have APM or ACPI support
703 to shut themselves down properly. A special I/O sequence is
704 needed to do so, which is what this module does at
707 This is only for Iris machines from EuroBraille.
711 config SCHED_OMIT_FRAME_POINTER
713 prompt "Single-depth WCHAN output"
716 Calculate simpler /proc/<PID>/wchan values. If this option
717 is disabled then wchan values will recurse back to the
718 caller function. This provides more accurate wchan values,
719 at the expense of slightly more scheduling overhead.
721 If in doubt, say "Y".
723 menuconfig HYPERVISOR_GUEST
724 bool "Linux guest support"
726 Say Y here to enable options for running Linux under various hyper-
727 visors. This option enables basic hypervisor detection and platform
730 If you say N, all options in this submenu will be skipped and
731 disabled, and Linux guest support won't be built in.
736 bool "Enable paravirtualization code"
738 This changes the kernel so it can modify itself when it is run
739 under a hypervisor, potentially improving performance significantly
740 over full virtualization. However, when run without a hypervisor
741 the kernel is theoretically slower and slightly larger.
743 config PARAVIRT_DEBUG
744 bool "paravirt-ops debugging"
745 depends on PARAVIRT && DEBUG_KERNEL
747 Enable to debug paravirt_ops internals. Specifically, BUG if
748 a paravirt_op is missing when it is called.
750 config PARAVIRT_SPINLOCKS
751 bool "Paravirtualization layer for spinlocks"
752 depends on PARAVIRT && SMP
754 Paravirtualized spinlocks allow a pvops backend to replace the
755 spinlock implementation with something virtualization-friendly
756 (for example, block the virtual CPU rather than spinning).
758 It has a minimal impact on native kernels and gives a nice performance
759 benefit on paravirtualized KVM / Xen kernels.
761 If you are unsure how to answer this question, answer Y.
763 config QUEUED_LOCK_STAT
764 bool "Paravirt queued spinlock statistics"
765 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
767 Enable the collection of statistical data on the slowpath
768 behavior of paravirtualized queued spinlocks and report
771 source "arch/x86/xen/Kconfig"
774 bool "KVM Guest support (including kvmclock)"
776 select PARAVIRT_CLOCK
779 This option enables various optimizations for running under the KVM
780 hypervisor. It includes a paravirtualized clock, so that instead
781 of relying on a PIT (or probably other) emulation by the
782 underlying device model, the host provides the guest with
783 timing infrastructure such as time of day, and system time
786 bool "Enable debug information for KVM Guests in debugfs"
787 depends on KVM_GUEST && DEBUG_FS
790 This option enables collection of various statistics for KVM guest.
791 Statistics are displayed in debugfs filesystem. Enabling this option
792 may incur significant overhead.
794 config PARAVIRT_TIME_ACCOUNTING
795 bool "Paravirtual steal time accounting"
799 Select this option to enable fine granularity task steal time
800 accounting. Time spent executing other tasks in parallel with
801 the current vCPU is discounted from the vCPU power. To account for
802 that, there can be a small performance impact.
804 If in doubt, say N here.
806 config PARAVIRT_CLOCK
809 config JAILHOUSE_GUEST
810 bool "Jailhouse non-root cell support"
811 depends on X86_64 && PCI
814 This option allows to run Linux as guest in a Jailhouse non-root
815 cell. You can leave this option disabled if you only want to start
816 Jailhouse and run Linux afterwards in the root cell.
818 endif #HYPERVISOR_GUEST
823 source "arch/x86/Kconfig.cpu"
827 prompt "HPET Timer Support" if X86_32
829 Use the IA-PC HPET (High Precision Event Timer) to manage
830 time in preference to the PIT and RTC, if a HPET is
832 HPET is the next generation timer replacing legacy 8254s.
833 The HPET provides a stable time base on SMP
834 systems, unlike the TSC, but it is more expensive to access,
835 as it is off-chip. The interface used is documented
836 in the HPET spec, revision 1.
838 You can safely choose Y here. However, HPET will only be
839 activated if the platform and the BIOS support this feature.
840 Otherwise the 8254 will be used for timing services.
842 Choose N to continue using the legacy 8254 timer.
844 config HPET_EMULATE_RTC
846 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
849 def_bool y if X86_INTEL_MID
850 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
852 depends on X86_INTEL_MID && SFI
854 APB timer is the replacement for 8254, HPET on X86 MID platforms.
855 The APBT provides a stable time base on SMP
856 systems, unlike the TSC, but it is more expensive to access,
857 as it is off-chip. APB timers are always running regardless of CPU
858 C states, they are used as per CPU clockevent device when possible.
860 # Mark as expert because too many people got it wrong.
861 # The code disables itself when not needed.
864 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
865 bool "Enable DMI scanning" if EXPERT
867 Enabled scanning of DMI to identify machine quirks. Say Y
868 here unless you have verified that your setup is not
869 affected by entries in the DMI blacklist. Required by PNP
873 bool "Old AMD GART IOMMU support"
875 depends on X86_64 && PCI && AMD_NB
877 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
878 GART based hardware IOMMUs.
880 The GART supports full DMA access for devices with 32-bit access
881 limitations, on systems with more than 3 GB. This is usually needed
882 for USB, sound, many IDE/SATA chipsets and some other devices.
884 Newer systems typically have a modern AMD IOMMU, supported via
885 the CONFIG_AMD_IOMMU=y config option.
887 In normal configurations this driver is only active when needed:
888 there's more than 3 GB of memory and the system contains a
889 32-bit limited device.
894 bool "IBM Calgary IOMMU support"
896 depends on X86_64 && PCI
898 Support for hardware IOMMUs in IBM's xSeries x366 and x460
899 systems. Needed to run systems with more than 3GB of memory
900 properly with 32-bit PCI devices that do not support DAC
901 (Double Address Cycle). Calgary also supports bus level
902 isolation, where all DMAs pass through the IOMMU. This
903 prevents them from going anywhere except their intended
904 destination. This catches hard-to-find kernel bugs and
905 mis-behaving drivers and devices that do not use the DMA-API
906 properly to set up their DMA buffers. The IOMMU can be
907 turned off at boot time with the iommu=off parameter.
908 Normally the kernel will make the right choice by itself.
911 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
913 prompt "Should Calgary be enabled by default?"
914 depends on CALGARY_IOMMU
916 Should Calgary be enabled by default? if you choose 'y', Calgary
917 will be used (if it exists). If you choose 'n', Calgary will not be
918 used even if it exists. If you choose 'n' and would like to use
919 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
922 # need this always selected by IOMMU for the VIA workaround
926 Support for software bounce buffers used on x86-64 systems
927 which don't have a hardware IOMMU. Using this PCI devices
928 which can only access 32-bits of memory can be used on systems
929 with more than 3 GB of memory.
934 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
937 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
938 depends on X86_64 && SMP && DEBUG_KERNEL
939 select CPUMASK_OFFSTACK
941 Enable maximum number of CPUS and NUMA Nodes for this architecture.
945 # The maximum number of CPUs supported:
947 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
948 # and which can be configured interactively in the
949 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
951 # The ranges are different on 32-bit and 64-bit kernels, depending on
952 # hardware capabilities and scalability features of the kernel.
954 # ( If MAXSMP is enabled we just use the highest possible value and disable
955 # interactive configuration. )
958 config NR_CPUS_RANGE_BEGIN
960 default NR_CPUS_RANGE_END if MAXSMP
964 config NR_CPUS_RANGE_END
967 default 64 if SMP && X86_BIGSMP
968 default 8 if SMP && !X86_BIGSMP
971 config NR_CPUS_RANGE_END
974 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
975 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
978 config NR_CPUS_DEFAULT
981 default 32 if X86_BIGSMP
985 config NR_CPUS_DEFAULT
988 default 8192 if MAXSMP
993 int "Maximum number of CPUs" if SMP && !MAXSMP
994 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
995 default NR_CPUS_DEFAULT
997 This allows you to specify the maximum number of CPUs which this
998 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
999 supported value is 8192, otherwise the maximum value is 512. The
1000 minimum value which makes sense is 2.
1002 This is purely to save memory: each supported CPU adds about 8KB
1003 to the kernel image.
1006 bool "SMT (Hyperthreading) scheduler support"
1009 SMT scheduler support improves the CPU scheduler's decision making
1010 when dealing with Intel Pentium 4 chips with HyperThreading at a
1011 cost of slightly increased overhead in some places. If unsure say
1016 prompt "Multi-core scheduler support"
1019 Multi-core scheduler support improves the CPU scheduler's decision
1020 making when dealing with multi-core CPU chips at a cost of slightly
1021 increased overhead in some places. If unsure say N here.
1023 config SCHED_MC_PRIO
1024 bool "CPU core priorities scheduler support"
1025 depends on SCHED_MC && CPU_SUP_INTEL
1026 select X86_INTEL_PSTATE
1030 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1031 core ordering determined at manufacturing time, which allows
1032 certain cores to reach higher turbo frequencies (when running
1033 single threaded workloads) than others.
1035 Enabling this kernel feature teaches the scheduler about
1036 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1037 scheduler's CPU selection logic accordingly, so that higher
1038 overall system performance can be achieved.
1040 This feature will have no effect on CPUs without this feature.
1042 If unsure say Y here.
1044 source "kernel/Kconfig.preempt"
1048 depends on !SMP && X86_LOCAL_APIC
1051 bool "Local APIC support on uniprocessors" if !PCI_MSI
1053 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1055 A local APIC (Advanced Programmable Interrupt Controller) is an
1056 integrated interrupt controller in the CPU. If you have a single-CPU
1057 system which has a processor with a local APIC, you can say Y here to
1058 enable and use it. If you say Y here even though your machine doesn't
1059 have a local APIC, then the kernel will still run with no slowdown at
1060 all. The local APIC supports CPU-generated self-interrupts (timer,
1061 performance counters), and the NMI watchdog which detects hard
1064 config X86_UP_IOAPIC
1065 bool "IO-APIC support on uniprocessors"
1066 depends on X86_UP_APIC
1068 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1069 SMP-capable replacement for PC-style interrupt controllers. Most
1070 SMP systems and many recent uniprocessor systems have one.
1072 If you have a single-CPU system with an IO-APIC, you can say Y here
1073 to use it. If you say Y here even though your machine doesn't have
1074 an IO-APIC, then the kernel will still run with no slowdown at all.
1076 config X86_LOCAL_APIC
1078 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1079 select IRQ_DOMAIN_HIERARCHY
1080 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1084 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1086 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1087 bool "Reroute for broken boot IRQs"
1088 depends on X86_IO_APIC
1090 This option enables a workaround that fixes a source of
1091 spurious interrupts. This is recommended when threaded
1092 interrupt handling is used on systems where the generation of
1093 superfluous "boot interrupts" cannot be disabled.
1095 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1096 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1097 kernel does during interrupt handling). On chipsets where this
1098 boot IRQ generation cannot be disabled, this workaround keeps
1099 the original IRQ line masked so that only the equivalent "boot
1100 IRQ" is delivered to the CPUs. The workaround also tells the
1101 kernel to set up the IRQ handler on the boot IRQ line. In this
1102 way only one interrupt is delivered to the kernel. Otherwise
1103 the spurious second interrupt may cause the kernel to bring
1104 down (vital) interrupt lines.
1106 Only affects "broken" chipsets. Interrupt sharing may be
1107 increased on these systems.
1110 bool "Machine Check / overheating reporting"
1111 select GENERIC_ALLOCATOR
1114 Machine Check support allows the processor to notify the
1115 kernel if it detects a problem (e.g. overheating, data corruption).
1116 The action the kernel takes depends on the severity of the problem,
1117 ranging from warning messages to halting the machine.
1119 config X86_MCELOG_LEGACY
1120 bool "Support for deprecated /dev/mcelog character device"
1123 Enable support for /dev/mcelog which is needed by the old mcelog
1124 userspace logging daemon. Consider switching to the new generation
1127 config X86_MCE_INTEL
1129 prompt "Intel MCE features"
1130 depends on X86_MCE && X86_LOCAL_APIC
1132 Additional support for intel specific MCE features such as
1133 the thermal monitor.
1137 prompt "AMD MCE features"
1138 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1140 Additional support for AMD specific MCE features such as
1141 the DRAM Error Threshold.
1143 config X86_ANCIENT_MCE
1144 bool "Support for old Pentium 5 / WinChip machine checks"
1145 depends on X86_32 && X86_MCE
1147 Include support for machine check handling on old Pentium 5 or WinChip
1148 systems. These typically need to be enabled explicitly on the command
1151 config X86_MCE_THRESHOLD
1152 depends on X86_MCE_AMD || X86_MCE_INTEL
1155 config X86_MCE_INJECT
1156 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1157 tristate "Machine check injector support"
1159 Provide support for injecting machine checks for testing purposes.
1160 If you don't know what a machine check is and you don't do kernel
1161 QA it is safe to say n.
1163 config X86_THERMAL_VECTOR
1165 depends on X86_MCE_INTEL
1167 source "arch/x86/events/Kconfig"
1169 config X86_LEGACY_VM86
1170 bool "Legacy VM86 support"
1174 This option allows user programs to put the CPU into V8086
1175 mode, which is an 80286-era approximation of 16-bit real mode.
1177 Some very old versions of X and/or vbetool require this option
1178 for user mode setting. Similarly, DOSEMU will use it if
1179 available to accelerate real mode DOS programs. However, any
1180 recent version of DOSEMU, X, or vbetool should be fully
1181 functional even without kernel VM86 support, as they will all
1182 fall back to software emulation. Nevertheless, if you are using
1183 a 16-bit DOS program where 16-bit performance matters, vm86
1184 mode might be faster than emulation and you might want to
1187 Note that any app that works on a 64-bit kernel is unlikely to
1188 need this option, as 64-bit kernels don't, and can't, support
1189 V8086 mode. This option is also unrelated to 16-bit protected
1190 mode and is not needed to run most 16-bit programs under Wine.
1192 Enabling this option increases the complexity of the kernel
1193 and slows down exception handling a tiny bit.
1195 If unsure, say N here.
1199 default X86_LEGACY_VM86
1202 bool "Enable support for 16-bit segments" if EXPERT
1204 depends on MODIFY_LDT_SYSCALL
1206 This option is required by programs like Wine to run 16-bit
1207 protected mode legacy code on x86 processors. Disabling
1208 this option saves about 300 bytes on i386, or around 6K text
1209 plus 16K runtime memory on x86-64,
1213 depends on X86_16BIT && X86_32
1217 depends on X86_16BIT && X86_64
1219 config X86_VSYSCALL_EMULATION
1220 bool "Enable vsyscall emulation" if EXPERT
1224 This enables emulation of the legacy vsyscall page. Disabling
1225 it is roughly equivalent to booting with vsyscall=none, except
1226 that it will also disable the helpful warning if a program
1227 tries to use a vsyscall. With this option set to N, offending
1228 programs will just segfault, citing addresses of the form
1231 This option is required by many programs built before 2013, and
1232 care should be used even with newer programs if set to N.
1234 Disabling this option saves about 7K of kernel size and
1235 possibly 4K of additional runtime pagetable memory.
1238 tristate "Toshiba Laptop support"
1241 This adds a driver to safely access the System Management Mode of
1242 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1243 not work on models with a Phoenix BIOS. The System Management Mode
1244 is used to set the BIOS and power saving options on Toshiba portables.
1246 For information on utilities to make use of this driver see the
1247 Toshiba Linux utilities web site at:
1248 <http://www.buzzard.org.uk/toshiba/>.
1250 Say Y if you intend to run this kernel on a Toshiba portable.
1254 tristate "Dell i8k legacy laptop support"
1256 select SENSORS_DELL_SMM
1258 This option enables legacy /proc/i8k userspace interface in hwmon
1259 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1260 temperature and allows controlling fan speeds of Dell laptops via
1261 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1262 it reports also power and hotkey status. For fan speed control is
1263 needed userspace package i8kutils.
1265 Say Y if you intend to run this kernel on old Dell laptops or want to
1266 use userspace package i8kutils.
1269 config X86_REBOOTFIXUPS
1270 bool "Enable X86 board specific fixups for reboot"
1273 This enables chipset and/or board specific fixups to be done
1274 in order to get reboot to work correctly. This is only needed on
1275 some combinations of hardware and BIOS. The symptom, for which
1276 this config is intended, is when reboot ends with a stalled/hung
1279 Currently, the only fixup is for the Geode machines using
1280 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1282 Say Y if you want to enable the fixup. Currently, it's safe to
1283 enable this option even if you don't need it.
1287 bool "CPU microcode loading support"
1289 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1292 If you say Y here, you will be able to update the microcode on
1293 Intel and AMD processors. The Intel support is for the IA32 family,
1294 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1295 AMD support is for families 0x10 and later. You will obviously need
1296 the actual microcode binary data itself which is not shipped with
1299 The preferred method to load microcode from a detached initrd is described
1300 in Documentation/x86/microcode.txt. For that you need to enable
1301 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1302 initrd for microcode blobs.
1304 In addition, you can build the microcode into the kernel. For that you
1305 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1308 config MICROCODE_INTEL
1309 bool "Intel microcode loading support"
1310 depends on MICROCODE
1314 This options enables microcode patch loading support for Intel
1317 For the current Intel microcode data package go to
1318 <https://downloadcenter.intel.com> and search for
1319 'Linux Processor Microcode Data File'.
1321 config MICROCODE_AMD
1322 bool "AMD microcode loading support"
1323 depends on MICROCODE
1326 If you select this option, microcode patch loading support for AMD
1327 processors will be enabled.
1329 config MICROCODE_OLD_INTERFACE
1331 depends on MICROCODE
1334 tristate "/dev/cpu/*/msr - Model-specific register support"
1336 This device gives privileged processes access to the x86
1337 Model-Specific Registers (MSRs). It is a character device with
1338 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1339 MSR accesses are directed to a specific CPU on multi-processor
1343 tristate "/dev/cpu/*/cpuid - CPU information support"
1345 This device gives processes access to the x86 CPUID instruction to
1346 be executed on a specific processor. It is a character device
1347 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1351 prompt "High Memory Support"
1358 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1359 However, the address space of 32-bit x86 processors is only 4
1360 Gigabytes large. That means that, if you have a large amount of
1361 physical memory, not all of it can be "permanently mapped" by the
1362 kernel. The physical memory that's not permanently mapped is called
1365 If you are compiling a kernel which will never run on a machine with
1366 more than 1 Gigabyte total physical RAM, answer "off" here (default
1367 choice and suitable for most users). This will result in a "3GB/1GB"
1368 split: 3GB are mapped so that each process sees a 3GB virtual memory
1369 space and the remaining part of the 4GB virtual memory space is used
1370 by the kernel to permanently map as much physical memory as
1373 If the machine has between 1 and 4 Gigabytes physical RAM, then
1376 If more than 4 Gigabytes is used then answer "64GB" here. This
1377 selection turns Intel PAE (Physical Address Extension) mode on.
1378 PAE implements 3-level paging on IA32 processors. PAE is fully
1379 supported by Linux, PAE mode is implemented on all recent Intel
1380 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1381 then the kernel will not boot on CPUs that don't support PAE!
1383 The actual amount of total physical memory will either be
1384 auto detected or can be forced by using a kernel command line option
1385 such as "mem=256M". (Try "man bootparam" or see the documentation of
1386 your boot loader (lilo or loadlin) about how to pass options to the
1387 kernel at boot time.)
1389 If unsure, say "off".
1394 Select this if you have a 32-bit processor and between 1 and 4
1395 gigabytes of physical RAM.
1399 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1402 Select this if you have a 32-bit processor and more than 4
1403 gigabytes of physical RAM.
1408 prompt "Memory split" if EXPERT
1412 Select the desired split between kernel and user memory.
1414 If the address range available to the kernel is less than the
1415 physical memory installed, the remaining memory will be available
1416 as "high memory". Accessing high memory is a little more costly
1417 than low memory, as it needs to be mapped into the kernel first.
1418 Note that increasing the kernel address space limits the range
1419 available to user programs, making the address space there
1420 tighter. Selecting anything other than the default 3G/1G split
1421 will also likely make your kernel incompatible with binary-only
1424 If you are not absolutely sure what you are doing, leave this
1428 bool "3G/1G user/kernel split"
1429 config VMSPLIT_3G_OPT
1431 bool "3G/1G user/kernel split (for full 1G low memory)"
1433 bool "2G/2G user/kernel split"
1434 config VMSPLIT_2G_OPT
1436 bool "2G/2G user/kernel split (for full 2G low memory)"
1438 bool "1G/3G user/kernel split"
1443 default 0xB0000000 if VMSPLIT_3G_OPT
1444 default 0x80000000 if VMSPLIT_2G
1445 default 0x78000000 if VMSPLIT_2G_OPT
1446 default 0x40000000 if VMSPLIT_1G
1452 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1455 bool "PAE (Physical Address Extension) Support"
1456 depends on X86_32 && !HIGHMEM4G
1459 PAE is required for NX support, and furthermore enables
1460 larger swapspace support for non-overcommit purposes. It
1461 has the cost of more pagetable lookup overhead, and also
1462 consumes more pagetable space per process.
1465 bool "Enable 5-level page tables support"
1466 select DYNAMIC_MEMORY_LAYOUT
1467 select SPARSEMEM_VMEMMAP
1470 5-level paging enables access to larger address space:
1471 upto 128 PiB of virtual address space and 4 PiB of
1472 physical address space.
1474 It will be supported by future Intel CPUs.
1476 A kernel with the option enabled can be booted on machines that
1477 support 4- or 5-level paging.
1479 See Documentation/x86/x86_64/5level-paging.txt for more
1484 config ARCH_PHYS_ADDR_T_64BIT
1486 depends on X86_64 || X86_PAE
1488 config ARCH_DMA_ADDR_T_64BIT
1490 depends on X86_64 || HIGHMEM64G
1492 config X86_DIRECT_GBPAGES
1494 depends on X86_64 && !DEBUG_PAGEALLOC
1496 Certain kernel features effectively disable kernel
1497 linear 1 GB mappings (even if the CPU otherwise
1498 supports them), so don't confuse the user by printing
1499 that we have them enabled.
1501 config ARCH_HAS_MEM_ENCRYPT
1504 config AMD_MEM_ENCRYPT
1505 bool "AMD Secure Memory Encryption (SME) support"
1506 depends on X86_64 && CPU_SUP_AMD
1508 Say yes to enable support for the encryption of system memory.
1509 This requires an AMD processor that supports Secure Memory
1512 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1513 bool "Activate AMD Secure Memory Encryption (SME) by default"
1515 depends on AMD_MEM_ENCRYPT
1517 Say yes to have system memory encrypted by default if running on
1518 an AMD processor that supports Secure Memory Encryption (SME).
1520 If set to Y, then the encryption of system memory can be
1521 deactivated with the mem_encrypt=off command line option.
1523 If set to N, then the encryption of system memory can be
1524 activated with the mem_encrypt=on command line option.
1526 config ARCH_USE_MEMREMAP_PROT
1528 depends on AMD_MEM_ENCRYPT
1530 # Common NUMA Features
1532 bool "Numa Memory Allocation and Scheduler Support"
1534 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1535 default y if X86_BIGSMP
1537 Enable NUMA (Non Uniform Memory Access) support.
1539 The kernel will try to allocate memory used by a CPU on the
1540 local memory controller of the CPU and add some more
1541 NUMA awareness to the kernel.
1543 For 64-bit this is recommended if the system is Intel Core i7
1544 (or later), AMD Opteron, or EM64T NUMA.
1546 For 32-bit this is only needed if you boot a 32-bit
1547 kernel on a 64-bit NUMA platform.
1549 Otherwise, you should say N.
1553 prompt "Old style AMD Opteron NUMA detection"
1554 depends on X86_64 && NUMA && PCI
1556 Enable AMD NUMA node topology detection. You should say Y here if
1557 you have a multi processor AMD system. This uses an old method to
1558 read the NUMA configuration directly from the builtin Northbridge
1559 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1560 which also takes priority if both are compiled in.
1562 config X86_64_ACPI_NUMA
1564 prompt "ACPI NUMA detection"
1565 depends on X86_64 && NUMA && ACPI && PCI
1568 Enable ACPI SRAT based node topology detection.
1570 # Some NUMA nodes have memory ranges that span
1571 # other nodes. Even though a pfn is valid and
1572 # between a node's start and end pfns, it may not
1573 # reside on that node. See memmap_init_zone()
1575 config NODES_SPAN_OTHER_NODES
1577 depends on X86_64_ACPI_NUMA
1580 bool "NUMA emulation"
1583 Enable NUMA emulation. A flat machine will be split
1584 into virtual nodes when booted with "numa=fake=N", where N is the
1585 number of nodes. This is only useful for debugging.
1588 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1590 default "10" if MAXSMP
1591 default "6" if X86_64
1593 depends on NEED_MULTIPLE_NODES
1595 Specify the maximum number of NUMA Nodes available on the target
1596 system. Increases memory reserved to accommodate various tables.
1598 config ARCH_HAVE_MEMORY_PRESENT
1600 depends on X86_32 && DISCONTIGMEM
1602 config ARCH_FLATMEM_ENABLE
1604 depends on X86_32 && !NUMA
1606 config ARCH_DISCONTIGMEM_ENABLE
1608 depends on NUMA && X86_32
1610 config ARCH_DISCONTIGMEM_DEFAULT
1612 depends on NUMA && X86_32
1614 config ARCH_SPARSEMEM_ENABLE
1616 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1617 select SPARSEMEM_STATIC if X86_32
1618 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1620 config ARCH_SPARSEMEM_DEFAULT
1624 config ARCH_SELECT_MEMORY_MODEL
1626 depends on ARCH_SPARSEMEM_ENABLE
1628 config ARCH_MEMORY_PROBE
1629 bool "Enable sysfs memory/probe interface"
1630 depends on X86_64 && MEMORY_HOTPLUG
1632 This option enables a sysfs memory/probe interface for testing.
1633 See Documentation/memory-hotplug.txt for more information.
1634 If you are unsure how to answer this question, answer N.
1636 config ARCH_PROC_KCORE_TEXT
1638 depends on X86_64 && PROC_KCORE
1640 config ILLEGAL_POINTER_VALUE
1643 default 0xdead000000000000 if X86_64
1647 config X86_PMEM_LEGACY_DEVICE
1650 config X86_PMEM_LEGACY
1651 tristate "Support non-standard NVDIMMs and ADR protected memory"
1652 depends on PHYS_ADDR_T_64BIT
1654 select X86_PMEM_LEGACY_DEVICE
1657 Treat memory marked using the non-standard e820 type of 12 as used
1658 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1659 The kernel will offer these regions to the 'pmem' driver so
1660 they can be used for persistent storage.
1665 bool "Allocate 3rd-level pagetables from highmem"
1668 The VM uses one page table entry for each page of physical memory.
1669 For systems with a lot of RAM, this can be wasteful of precious
1670 low memory. Setting this option will put user-space page table
1671 entries in high memory.
1673 config X86_CHECK_BIOS_CORRUPTION
1674 bool "Check for low memory corruption"
1676 Periodically check for memory corruption in low memory, which
1677 is suspected to be caused by BIOS. Even when enabled in the
1678 configuration, it is disabled at runtime. Enable it by
1679 setting "memory_corruption_check=1" on the kernel command
1680 line. By default it scans the low 64k of memory every 60
1681 seconds; see the memory_corruption_check_size and
1682 memory_corruption_check_period parameters in
1683 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685 When enabled with the default parameters, this option has
1686 almost no overhead, as it reserves a relatively small amount
1687 of memory and scans it infrequently. It both detects corruption
1688 and prevents it from affecting the running system.
1690 It is, however, intended as a diagnostic tool; if repeatable
1691 BIOS-originated corruption always affects the same memory,
1692 you can use memmap= to prevent the kernel from using that
1695 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1696 bool "Set the default setting of memory_corruption_check"
1697 depends on X86_CHECK_BIOS_CORRUPTION
1700 Set whether the default state of memory_corruption_check is
1703 config X86_RESERVE_LOW
1704 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1708 Specify the amount of low memory to reserve for the BIOS.
1710 The first page contains BIOS data structures that the kernel
1711 must not use, so that page must always be reserved.
1713 By default we reserve the first 64K of physical RAM, as a
1714 number of BIOSes are known to corrupt that memory range
1715 during events such as suspend/resume or monitor cable
1716 insertion, so it must not be used by the kernel.
1718 You can set this to 4 if you are absolutely sure that you
1719 trust the BIOS to get all its memory reservations and usages
1720 right. If you know your BIOS have problems beyond the
1721 default 64K area, you can set this to 640 to avoid using the
1722 entire low memory range.
1724 If you have doubts about the BIOS (e.g. suspend/resume does
1725 not work or there's kernel crashes after certain hardware
1726 hotplug events) then you might want to enable
1727 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1728 typical corruption patterns.
1730 Leave this to the default value of 64 if you are unsure.
1732 config MATH_EMULATION
1734 depends on MODIFY_LDT_SYSCALL
1735 prompt "Math emulation" if X86_32
1737 Linux can emulate a math coprocessor (used for floating point
1738 operations) if you don't have one. 486DX and Pentium processors have
1739 a math coprocessor built in, 486SX and 386 do not, unless you added
1740 a 487DX or 387, respectively. (The messages during boot time can
1741 give you some hints here ["man dmesg"].) Everyone needs either a
1742 coprocessor or this emulation.
1744 If you don't have a math coprocessor, you need to say Y here; if you
1745 say Y here even though you have a coprocessor, the coprocessor will
1746 be used nevertheless. (This behavior can be changed with the kernel
1747 command line option "no387", which comes handy if your coprocessor
1748 is broken. Try "man bootparam" or see the documentation of your boot
1749 loader (lilo or loadlin) about how to pass options to the kernel at
1750 boot time.) This means that it is a good idea to say Y here if you
1751 intend to use this kernel on different machines.
1753 More information about the internals of the Linux math coprocessor
1754 emulation can be found in <file:arch/x86/math-emu/README>.
1756 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1757 kernel, it won't hurt.
1761 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1763 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1764 the Memory Type Range Registers (MTRRs) may be used to control
1765 processor access to memory ranges. This is most useful if you have
1766 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1767 allows bus write transfers to be combined into a larger transfer
1768 before bursting over the PCI/AGP bus. This can increase performance
1769 of image write operations 2.5 times or more. Saying Y here creates a
1770 /proc/mtrr file which may be used to manipulate your processor's
1771 MTRRs. Typically the X server should use this.
1773 This code has a reasonably generic interface so that similar
1774 control registers on other processors can be easily supported
1777 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1778 Registers (ARRs) which provide a similar functionality to MTRRs. For
1779 these, the ARRs are used to emulate the MTRRs.
1780 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1781 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1782 write-combining. All of these processors are supported by this code
1783 and it makes sense to say Y here if you have one of them.
1785 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1786 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1787 can lead to all sorts of problems, so it's good to say Y here.
1789 You can safely say Y even if your machine doesn't have MTRRs, you'll
1790 just add about 9 KB to your kernel.
1792 See <file:Documentation/x86/mtrr.txt> for more information.
1794 config MTRR_SANITIZER
1796 prompt "MTRR cleanup support"
1799 Convert MTRR layout from continuous to discrete, so X drivers can
1800 add writeback entries.
1802 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1803 The largest mtrr entry size for a continuous block can be set with
1808 config MTRR_SANITIZER_ENABLE_DEFAULT
1809 int "MTRR cleanup enable value (0-1)"
1812 depends on MTRR_SANITIZER
1814 Enable mtrr cleanup default value
1816 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1817 int "MTRR cleanup spare reg num (0-7)"
1820 depends on MTRR_SANITIZER
1822 mtrr cleanup spare entries default, it can be changed via
1823 mtrr_spare_reg_nr=N on the kernel command line.
1827 prompt "x86 PAT support" if EXPERT
1830 Use PAT attributes to setup page level cache control.
1832 PATs are the modern equivalents of MTRRs and are much more
1833 flexible than MTRRs.
1835 Say N here if you see bootup problems (boot crash, boot hang,
1836 spontaneous reboots) or a non-working video driver.
1840 config ARCH_USES_PG_UNCACHED
1846 prompt "x86 architectural random number generator" if EXPERT
1848 Enable the x86 architectural RDRAND instruction
1849 (Intel Bull Mountain technology) to generate random numbers.
1850 If supported, this is a high bandwidth, cryptographically
1851 secure hardware random number generator.
1855 prompt "Supervisor Mode Access Prevention" if EXPERT
1857 Supervisor Mode Access Prevention (SMAP) is a security
1858 feature in newer Intel processors. There is a small
1859 performance cost if this enabled and turned on; there is
1860 also a small increase in the kernel size if this is enabled.
1864 config X86_INTEL_UMIP
1866 depends on CPU_SUP_INTEL
1867 prompt "Intel User Mode Instruction Prevention" if EXPERT
1869 The User Mode Instruction Prevention (UMIP) is a security
1870 feature in newer Intel processors. If enabled, a general
1871 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1872 or STR instructions are executed in user mode. These instructions
1873 unnecessarily expose information about the hardware state.
1875 The vast majority of applications do not use these instructions.
1876 For the very few that do, software emulation is provided in
1877 specific cases in protected and virtual-8086 modes. Emulated
1880 config X86_INTEL_MPX
1881 prompt "Intel MPX (Memory Protection Extensions)"
1883 # Note: only available in 64-bit mode due to VMA flags shortage
1884 depends on CPU_SUP_INTEL && X86_64
1885 select ARCH_USES_HIGH_VMA_FLAGS
1887 MPX provides hardware features that can be used in
1888 conjunction with compiler-instrumented code to check
1889 memory references. It is designed to detect buffer
1890 overflow or underflow bugs.
1892 This option enables running applications which are
1893 instrumented or otherwise use MPX. It does not use MPX
1894 itself inside the kernel or to protect the kernel
1895 against bad memory references.
1897 Enabling this option will make the kernel larger:
1898 ~8k of kernel text and 36 bytes of data on a 64-bit
1899 defconfig. It adds a long to the 'mm_struct' which
1900 will increase the kernel memory overhead of each
1901 process and adds some branches to paths used during
1902 exec() and munmap().
1904 For details, see Documentation/x86/intel_mpx.txt
1908 config X86_INTEL_MEMORY_PROTECTION_KEYS
1909 prompt "Intel Memory Protection Keys"
1911 # Note: only available in 64-bit mode
1912 depends on CPU_SUP_INTEL && X86_64
1913 select ARCH_USES_HIGH_VMA_FLAGS
1914 select ARCH_HAS_PKEYS
1916 Memory Protection Keys provides a mechanism for enforcing
1917 page-based protections, but without requiring modification of the
1918 page tables when an application changes protection domains.
1920 For details, see Documentation/x86/protection-keys.txt
1925 bool "EFI runtime service support"
1928 select EFI_RUNTIME_WRAPPERS
1930 This enables the kernel to use EFI runtime services that are
1931 available (such as the EFI variable services).
1933 This option is only useful on systems that have EFI firmware.
1934 In addition, you should use the latest ELILO loader available
1935 at <http://elilo.sourceforge.net> in order to take advantage
1936 of EFI runtime services. However, even with this option, the
1937 resultant kernel should continue to boot on existing non-EFI
1941 bool "EFI stub support"
1942 depends on EFI && !X86_USE_3DNOW
1945 This kernel feature allows a bzImage to be loaded directly
1946 by EFI firmware without the use of a bootloader.
1948 See Documentation/efi-stub.txt for more information.
1951 bool "EFI mixed-mode support"
1952 depends on EFI_STUB && X86_64
1954 Enabling this feature allows a 64-bit kernel to be booted
1955 on a 32-bit firmware, provided that your CPU supports 64-bit
1958 Note that it is not possible to boot a mixed-mode enabled
1959 kernel via the EFI boot stub - a bootloader that supports
1960 the EFI handover protocol must be used.
1966 prompt "Enable seccomp to safely compute untrusted bytecode"
1968 This kernel feature is useful for number crunching applications
1969 that may need to compute untrusted bytecode during their
1970 execution. By using pipes or other transports made available to
1971 the process as file descriptors supporting the read/write
1972 syscalls, it's possible to isolate those applications in
1973 their own address space using seccomp. Once seccomp is
1974 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1975 and the task is only allowed to execute a few safe syscalls
1976 defined by each seccomp mode.
1978 If unsure, say Y. Only embedded should say N here.
1980 source kernel/Kconfig.hz
1983 bool "kexec system call"
1986 kexec is a system call that implements the ability to shutdown your
1987 current kernel, and to start another kernel. It is like a reboot
1988 but it is independent of the system firmware. And like a reboot
1989 you can start any kernel with it, not just Linux.
1991 The name comes from the similarity to the exec system call.
1993 It is an ongoing process to be certain the hardware in a machine
1994 is properly shutdown, so do not be surprised if this code does not
1995 initially work for you. As of this writing the exact hardware
1996 interface is strongly in flux, so no good recommendation can be
2000 bool "kexec file based system call"
2005 depends on CRYPTO_SHA256=y
2007 This is new version of kexec system call. This system call is
2008 file based and takes file descriptors as system call argument
2009 for kernel and initramfs as opposed to list of segments as
2010 accepted by previous system call.
2012 config ARCH_HAS_KEXEC_PURGATORY
2015 config KEXEC_VERIFY_SIG
2016 bool "Verify kernel signature during kexec_file_load() syscall"
2017 depends on KEXEC_FILE
2019 This option makes kernel signature verification mandatory for
2020 the kexec_file_load() syscall.
2022 In addition to that option, you need to enable signature
2023 verification for the corresponding kernel image type being
2024 loaded in order for this to work.
2026 config KEXEC_BZIMAGE_VERIFY_SIG
2027 bool "Enable bzImage signature verification support"
2028 depends on KEXEC_VERIFY_SIG
2029 depends on SIGNED_PE_FILE_VERIFICATION
2030 select SYSTEM_TRUSTED_KEYRING
2032 Enable bzImage signature verification support.
2035 bool "kernel crash dumps"
2036 depends on X86_64 || (X86_32 && HIGHMEM)
2038 Generate crash dump after being started by kexec.
2039 This should be normally only set in special crash dump kernels
2040 which are loaded in the main kernel with kexec-tools into
2041 a specially reserved region and then later executed after
2042 a crash by kdump/kexec. The crash dump kernel must be compiled
2043 to a memory address not used by the main kernel or BIOS using
2044 PHYSICAL_START, or it must be built as a relocatable image
2045 (CONFIG_RELOCATABLE=y).
2046 For more details see Documentation/kdump/kdump.txt
2050 depends on KEXEC && HIBERNATION
2052 Jump between original kernel and kexeced kernel and invoke
2053 code in physical address mode via KEXEC
2055 config PHYSICAL_START
2056 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2059 This gives the physical address where the kernel is loaded.
2061 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2062 bzImage will decompress itself to above physical address and
2063 run from there. Otherwise, bzImage will run from the address where
2064 it has been loaded by the boot loader and will ignore above physical
2067 In normal kdump cases one does not have to set/change this option
2068 as now bzImage can be compiled as a completely relocatable image
2069 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2070 address. This option is mainly useful for the folks who don't want
2071 to use a bzImage for capturing the crash dump and want to use a
2072 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2073 to be specifically compiled to run from a specific memory area
2074 (normally a reserved region) and this option comes handy.
2076 So if you are using bzImage for capturing the crash dump,
2077 leave the value here unchanged to 0x1000000 and set
2078 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2079 for capturing the crash dump change this value to start of
2080 the reserved region. In other words, it can be set based on
2081 the "X" value as specified in the "crashkernel=YM@XM"
2082 command line boot parameter passed to the panic-ed
2083 kernel. Please take a look at Documentation/kdump/kdump.txt
2084 for more details about crash dumps.
2086 Usage of bzImage for capturing the crash dump is recommended as
2087 one does not have to build two kernels. Same kernel can be used
2088 as production kernel and capture kernel. Above option should have
2089 gone away after relocatable bzImage support is introduced. But it
2090 is present because there are users out there who continue to use
2091 vmlinux for dump capture. This option should go away down the
2094 Don't change this unless you know what you are doing.
2097 bool "Build a relocatable kernel"
2100 This builds a kernel image that retains relocation information
2101 so it can be loaded someplace besides the default 1MB.
2102 The relocations tend to make the kernel binary about 10% larger,
2103 but are discarded at runtime.
2105 One use is for the kexec on panic case where the recovery kernel
2106 must live at a different physical address than the primary
2109 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2110 it has been loaded at and the compile time physical address
2111 (CONFIG_PHYSICAL_START) is used as the minimum location.
2113 config RANDOMIZE_BASE
2114 bool "Randomize the address of the kernel image (KASLR)"
2115 depends on RELOCATABLE
2118 In support of Kernel Address Space Layout Randomization (KASLR),
2119 this randomizes the physical address at which the kernel image
2120 is decompressed and the virtual address where the kernel
2121 image is mapped, as a security feature that deters exploit
2122 attempts relying on knowledge of the location of kernel
2125 On 64-bit, the kernel physical and virtual addresses are
2126 randomized separately. The physical address will be anywhere
2127 between 16MB and the top of physical memory (up to 64TB). The
2128 virtual address will be randomized from 16MB up to 1GB (9 bits
2129 of entropy). Note that this also reduces the memory space
2130 available to kernel modules from 1.5GB to 1GB.
2132 On 32-bit, the kernel physical and virtual addresses are
2133 randomized together. They will be randomized from 16MB up to
2134 512MB (8 bits of entropy).
2136 Entropy is generated using the RDRAND instruction if it is
2137 supported. If RDTSC is supported, its value is mixed into
2138 the entropy pool as well. If neither RDRAND nor RDTSC are
2139 supported, then entropy is read from the i8254 timer. The
2140 usable entropy is limited by the kernel being built using
2141 2GB addressing, and that PHYSICAL_ALIGN must be at a
2142 minimum of 2MB. As a result, only 10 bits of entropy are
2143 theoretically possible, but the implementations are further
2144 limited due to memory layouts.
2148 # Relocation on x86 needs some additional build support
2149 config X86_NEED_RELOCS
2151 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2153 config PHYSICAL_ALIGN
2154 hex "Alignment value to which kernel should be aligned"
2156 range 0x2000 0x1000000 if X86_32
2157 range 0x200000 0x1000000 if X86_64
2159 This value puts the alignment restrictions on physical address
2160 where kernel is loaded and run from. Kernel is compiled for an
2161 address which meets above alignment restriction.
2163 If bootloader loads the kernel at a non-aligned address and
2164 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2165 address aligned to above value and run from there.
2167 If bootloader loads the kernel at a non-aligned address and
2168 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2169 load address and decompress itself to the address it has been
2170 compiled for and run from there. The address for which kernel is
2171 compiled already meets above alignment restrictions. Hence the
2172 end result is that kernel runs from a physical address meeting
2173 above alignment restrictions.
2175 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2176 this value must be a multiple of 0x200000.
2178 Don't change this unless you know what you are doing.
2180 config DYNAMIC_MEMORY_LAYOUT
2183 This option makes base addresses of vmalloc and vmemmap as well as
2184 __PAGE_OFFSET movable during boot.
2186 config RANDOMIZE_MEMORY
2187 bool "Randomize the kernel memory sections"
2189 depends on RANDOMIZE_BASE
2190 select DYNAMIC_MEMORY_LAYOUT
2191 default RANDOMIZE_BASE
2193 Randomizes the base virtual address of kernel memory sections
2194 (physical memory mapping, vmalloc & vmemmap). This security feature
2195 makes exploits relying on predictable memory locations less reliable.
2197 The order of allocations remains unchanged. Entropy is generated in
2198 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2199 configuration have in average 30,000 different possible virtual
2200 addresses for each memory section.
2204 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2205 hex "Physical memory mapping padding" if EXPERT
2206 depends on RANDOMIZE_MEMORY
2207 default "0xa" if MEMORY_HOTPLUG
2209 range 0x1 0x40 if MEMORY_HOTPLUG
2212 Define the padding in terabytes added to the existing physical
2213 memory size during kernel memory randomization. It is useful
2214 for memory hotplug support but reduces the entropy available for
2215 address randomization.
2217 If unsure, leave at the default value.
2220 bool "Support for hot-pluggable CPUs"
2223 Say Y here to allow turning CPUs off and on. CPUs can be
2224 controlled through /sys/devices/system/cpu.
2225 ( Note: power management support will enable this option
2226 automatically on SMP systems. )
2227 Say N if you want to disable CPU hotplug.
2229 config BOOTPARAM_HOTPLUG_CPU0
2230 bool "Set default setting of cpu0_hotpluggable"
2232 depends on HOTPLUG_CPU
2234 Set whether default state of cpu0_hotpluggable is on or off.
2236 Say Y here to enable CPU0 hotplug by default. If this switch
2237 is turned on, there is no need to give cpu0_hotplug kernel
2238 parameter and the CPU0 hotplug feature is enabled by default.
2240 Please note: there are two known CPU0 dependencies if you want
2241 to enable the CPU0 hotplug feature either by this switch or by
2242 cpu0_hotplug kernel parameter.
2244 First, resume from hibernate or suspend always starts from CPU0.
2245 So hibernate and suspend are prevented if CPU0 is offline.
2247 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2248 offline if any interrupt can not migrate out of CPU0. There may
2249 be other CPU0 dependencies.
2251 Please make sure the dependencies are under your control before
2252 you enable this feature.
2254 Say N if you don't want to enable CPU0 hotplug feature by default.
2255 You still can enable the CPU0 hotplug feature at boot by kernel
2256 parameter cpu0_hotplug.
2258 config DEBUG_HOTPLUG_CPU0
2260 prompt "Debug CPU0 hotplug"
2261 depends on HOTPLUG_CPU
2263 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2264 soon as possible and boots up userspace with CPU0 offlined. User
2265 can online CPU0 back after boot time.
2267 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2268 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2269 compilation or giving cpu0_hotplug kernel parameter at boot.
2275 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2276 depends on COMPAT_32
2278 Certain buggy versions of glibc will crash if they are
2279 presented with a 32-bit vDSO that is not mapped at the address
2280 indicated in its segment table.
2282 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2283 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2284 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2285 the only released version with the bug, but OpenSUSE 9
2286 contains a buggy "glibc 2.3.2".
2288 The symptom of the bug is that everything crashes on startup, saying:
2289 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2291 Saying Y here changes the default value of the vdso32 boot
2292 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2293 This works around the glibc bug but hurts performance.
2295 If unsure, say N: if you are compiling your own kernel, you
2296 are unlikely to be using a buggy version of glibc.
2299 prompt "vsyscall table for legacy applications"
2301 default LEGACY_VSYSCALL_EMULATE
2303 Legacy user code that does not know how to find the vDSO expects
2304 to be able to issue three syscalls by calling fixed addresses in
2305 kernel space. Since this location is not randomized with ASLR,
2306 it can be used to assist security vulnerability exploitation.
2308 This setting can be changed at boot time via the kernel command
2309 line parameter vsyscall=[emulate|none].
2311 On a system with recent enough glibc (2.14 or newer) and no
2312 static binaries, you can say None without a performance penalty
2313 to improve security.
2315 If unsure, select "Emulate".
2317 config LEGACY_VSYSCALL_EMULATE
2320 The kernel traps and emulates calls into the fixed
2321 vsyscall address mapping. This makes the mapping
2322 non-executable, but it still contains known contents,
2323 which could be used in certain rare security vulnerability
2324 exploits. This configuration is recommended when userspace
2325 still uses the vsyscall area.
2327 config LEGACY_VSYSCALL_NONE
2330 There will be no vsyscall mapping at all. This will
2331 eliminate any risk of ASLR bypass due to the vsyscall
2332 fixed address mapping. Attempts to use the vsyscalls
2333 will be reported to dmesg, so that either old or
2334 malicious userspace programs can be identified.
2339 bool "Built-in kernel command line"
2341 Allow for specifying boot arguments to the kernel at
2342 build time. On some systems (e.g. embedded ones), it is
2343 necessary or convenient to provide some or all of the
2344 kernel boot arguments with the kernel itself (that is,
2345 to not rely on the boot loader to provide them.)
2347 To compile command line arguments into the kernel,
2348 set this option to 'Y', then fill in the
2349 boot arguments in CONFIG_CMDLINE.
2351 Systems with fully functional boot loaders (i.e. non-embedded)
2352 should leave this option set to 'N'.
2355 string "Built-in kernel command string"
2356 depends on CMDLINE_BOOL
2359 Enter arguments here that should be compiled into the kernel
2360 image and used at boot time. If the boot loader provides a
2361 command line at boot time, it is appended to this string to
2362 form the full kernel command line, when the system boots.
2364 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2365 change this behavior.
2367 In most cases, the command line (whether built-in or provided
2368 by the boot loader) should specify the device for the root
2371 config CMDLINE_OVERRIDE
2372 bool "Built-in command line overrides boot loader arguments"
2373 depends on CMDLINE_BOOL
2375 Set this option to 'Y' to have the kernel ignore the boot loader
2376 command line, and use ONLY the built-in command line.
2378 This is used to work around broken boot loaders. This should
2379 be set to 'N' under normal conditions.
2381 config MODIFY_LDT_SYSCALL
2382 bool "Enable the LDT (local descriptor table)" if EXPERT
2385 Linux can allow user programs to install a per-process x86
2386 Local Descriptor Table (LDT) using the modify_ldt(2) system
2387 call. This is required to run 16-bit or segmented code such as
2388 DOSEMU or some Wine programs. It is also used by some very old
2389 threading libraries.
2391 Enabling this feature adds a small amount of overhead to
2392 context switches and increases the low-level kernel attack
2393 surface. Disabling it removes the modify_ldt(2) system call.
2395 Saying 'N' here may make sense for embedded or server kernels.
2397 source "kernel/livepatch/Kconfig"
2401 config ARCH_HAS_ADD_PAGES
2403 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2405 config ARCH_ENABLE_MEMORY_HOTPLUG
2407 depends on X86_64 || (X86_32 && HIGHMEM)
2409 config ARCH_ENABLE_MEMORY_HOTREMOVE
2411 depends on MEMORY_HOTPLUG
2413 config USE_PERCPU_NUMA_NODE_ID
2417 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2419 depends on X86_64 || X86_PAE
2421 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2423 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2425 config ARCH_ENABLE_THP_MIGRATION
2427 depends on X86_64 && TRANSPARENT_HUGEPAGE
2429 menu "Power management and ACPI options"
2431 config ARCH_HIBERNATION_HEADER
2433 depends on X86_64 && HIBERNATION
2435 source "kernel/power/Kconfig"
2437 source "drivers/acpi/Kconfig"
2439 source "drivers/sfi/Kconfig"
2446 tristate "APM (Advanced Power Management) BIOS support"
2447 depends on X86_32 && PM_SLEEP
2449 APM is a BIOS specification for saving power using several different
2450 techniques. This is mostly useful for battery powered laptops with
2451 APM compliant BIOSes. If you say Y here, the system time will be
2452 reset after a RESUME operation, the /proc/apm device will provide
2453 battery status information, and user-space programs will receive
2454 notification of APM "events" (e.g. battery status change).
2456 If you select "Y" here, you can disable actual use of the APM
2457 BIOS by passing the "apm=off" option to the kernel at boot time.
2459 Note that the APM support is almost completely disabled for
2460 machines with more than one CPU.
2462 In order to use APM, you will need supporting software. For location
2463 and more information, read <file:Documentation/power/apm-acpi.txt>
2464 and the Battery Powered Linux mini-HOWTO, available from
2465 <http://www.tldp.org/docs.html#howto>.
2467 This driver does not spin down disk drives (see the hdparm(8)
2468 manpage ("man 8 hdparm") for that), and it doesn't turn off
2469 VESA-compliant "green" monitors.
2471 This driver does not support the TI 4000M TravelMate and the ACER
2472 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2473 desktop machines also don't have compliant BIOSes, and this driver
2474 may cause those machines to panic during the boot phase.
2476 Generally, if you don't have a battery in your machine, there isn't
2477 much point in using this driver and you should say N. If you get
2478 random kernel OOPSes or reboots that don't seem to be related to
2479 anything, try disabling/enabling this option (or disabling/enabling
2482 Some other things you should try when experiencing seemingly random,
2485 1) make sure that you have enough swap space and that it is
2487 2) pass the "no-hlt" option to the kernel
2488 3) switch on floating point emulation in the kernel and pass
2489 the "no387" option to the kernel
2490 4) pass the "floppy=nodma" option to the kernel
2491 5) pass the "mem=4M" option to the kernel (thereby disabling
2492 all but the first 4 MB of RAM)
2493 6) make sure that the CPU is not over clocked.
2494 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2495 8) disable the cache from your BIOS settings
2496 9) install a fan for the video card or exchange video RAM
2497 10) install a better fan for the CPU
2498 11) exchange RAM chips
2499 12) exchange the motherboard.
2501 To compile this driver as a module, choose M here: the
2502 module will be called apm.
2506 config APM_IGNORE_USER_SUSPEND
2507 bool "Ignore USER SUSPEND"
2509 This option will ignore USER SUSPEND requests. On machines with a
2510 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2511 series notebooks, it is necessary to say Y because of a BIOS bug.
2513 config APM_DO_ENABLE
2514 bool "Enable PM at boot time"
2516 Enable APM features at boot time. From page 36 of the APM BIOS
2517 specification: "When disabled, the APM BIOS does not automatically
2518 power manage devices, enter the Standby State, enter the Suspend
2519 State, or take power saving steps in response to CPU Idle calls."
2520 This driver will make CPU Idle calls when Linux is idle (unless this
2521 feature is turned off -- see "Do CPU IDLE calls", below). This
2522 should always save battery power, but more complicated APM features
2523 will be dependent on your BIOS implementation. You may need to turn
2524 this option off if your computer hangs at boot time when using APM
2525 support, or if it beeps continuously instead of suspending. Turn
2526 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2527 T400CDT. This is off by default since most machines do fine without
2532 bool "Make CPU Idle calls when idle"
2534 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2535 On some machines, this can activate improved power savings, such as
2536 a slowed CPU clock rate, when the machine is idle. These idle calls
2537 are made after the idle loop has run for some length of time (e.g.,
2538 333 mS). On some machines, this will cause a hang at boot time or
2539 whenever the CPU becomes idle. (On machines with more than one CPU,
2540 this option does nothing.)
2542 config APM_DISPLAY_BLANK
2543 bool "Enable console blanking using APM"
2545 Enable console blanking using the APM. Some laptops can use this to
2546 turn off the LCD backlight when the screen blanker of the Linux
2547 virtual console blanks the screen. Note that this is only used by
2548 the virtual console screen blanker, and won't turn off the backlight
2549 when using the X Window system. This also doesn't have anything to
2550 do with your VESA-compliant power-saving monitor. Further, this
2551 option doesn't work for all laptops -- it might not turn off your
2552 backlight at all, or it might print a lot of errors to the console,
2553 especially if you are using gpm.
2555 config APM_ALLOW_INTS
2556 bool "Allow interrupts during APM BIOS calls"
2558 Normally we disable external interrupts while we are making calls to
2559 the APM BIOS as a measure to lessen the effects of a badly behaving
2560 BIOS implementation. The BIOS should reenable interrupts if it
2561 needs to. Unfortunately, some BIOSes do not -- especially those in
2562 many of the newer IBM Thinkpads. If you experience hangs when you
2563 suspend, try setting this to Y. Otherwise, say N.
2567 source "drivers/cpufreq/Kconfig"
2569 source "drivers/cpuidle/Kconfig"
2571 source "drivers/idle/Kconfig"
2576 menu "Bus options (PCI etc.)"
2582 Find out whether you have a PCI motherboard. PCI is the name of a
2583 bus system, i.e. the way the CPU talks to the other stuff inside
2584 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2585 VESA. If you have PCI, say Y, otherwise N.
2588 prompt "PCI access mode"
2589 depends on X86_32 && PCI
2592 On PCI systems, the BIOS can be used to detect the PCI devices and
2593 determine their configuration. However, some old PCI motherboards
2594 have BIOS bugs and may crash if this is done. Also, some embedded
2595 PCI-based systems don't have any BIOS at all. Linux can also try to
2596 detect the PCI hardware directly without using the BIOS.
2598 With this option, you can specify how Linux should detect the
2599 PCI devices. If you choose "BIOS", the BIOS will be used,
2600 if you choose "Direct", the BIOS won't be used, and if you
2601 choose "MMConfig", then PCI Express MMCONFIG will be used.
2602 If you choose "Any", the kernel will try MMCONFIG, then the
2603 direct access method and falls back to the BIOS if that doesn't
2604 work. If unsure, go with the default, which is "Any".
2609 config PCI_GOMMCONFIG
2626 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2628 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2631 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2634 bool "Support mmconfig PCI config space access" if X86_64
2636 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2637 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2641 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2645 depends on PCI && XEN
2652 config MMCONF_FAM10H
2654 depends on X86_64 && PCI_MMCONFIG && ACPI
2656 config PCI_CNB20LE_QUIRK
2657 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2660 Read the PCI windows out of the CNB20LE host bridge. This allows
2661 PCI hotplug to work on systems with the CNB20LE chipset which do
2664 There's no public spec for this chipset, and this functionality
2665 is known to be incomplete.
2667 You should say N unless you know you need this.
2669 source "drivers/pci/Kconfig"
2672 bool "ISA bus support on modern systems" if EXPERT
2674 Expose ISA bus device drivers and options available for selection and
2675 configuration. Enable this option if your target machine has an ISA
2676 bus. ISA is an older system, displaced by PCI and newer bus
2677 architectures -- if your target machine is modern, it probably does
2678 not have an ISA bus.
2682 # x86_64 have no ISA slots, but can have ISA-style DMA.
2684 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2687 Enables ISA-style DMA support for devices requiring such controllers.
2695 Find out whether you have ISA slots on your motherboard. ISA is the
2696 name of a bus system, i.e. the way the CPU talks to the other stuff
2697 inside your box. Other bus systems are PCI, EISA, MicroChannel
2698 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2699 newer boards don't support it. If you have ISA, say Y, otherwise N.
2705 The Extended Industry Standard Architecture (EISA) bus was
2706 developed as an open alternative to the IBM MicroChannel bus.
2708 The EISA bus provided some of the features of the IBM MicroChannel
2709 bus while maintaining backward compatibility with cards made for
2710 the older ISA bus. The EISA bus saw limited use between 1988 and
2711 1995 when it was made obsolete by the PCI bus.
2713 Say Y here if you are building a kernel for an EISA-based machine.
2717 source "drivers/eisa/Kconfig"
2720 tristate "NatSemi SCx200 support"
2722 This provides basic support for National Semiconductor's
2723 (now AMD's) Geode processors. The driver probes for the
2724 PCI-IDs of several on-chip devices, so its a good dependency
2725 for other scx200_* drivers.
2727 If compiled as a module, the driver is named scx200.
2729 config SCx200HR_TIMER
2730 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2734 This driver provides a clocksource built upon the on-chip
2735 27MHz high-resolution timer. Its also a workaround for
2736 NSC Geode SC-1100's buggy TSC, which loses time when the
2737 processor goes idle (as is done by the scheduler). The
2738 other workaround is idle=poll boot option.
2741 bool "One Laptop Per Child support"
2748 Add support for detecting the unique features of the OLPC
2752 bool "OLPC XO-1 Power Management"
2753 depends on OLPC && MFD_CS5535 && PM_SLEEP
2756 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2759 bool "OLPC XO-1 Real Time Clock"
2760 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2762 Add support for the XO-1 real time clock, which can be used as a
2763 programmable wakeup source.
2766 bool "OLPC XO-1 SCI extras"
2767 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2771 Add support for SCI-based features of the OLPC XO-1 laptop:
2772 - EC-driven system wakeups
2776 - AC adapter status updates
2777 - Battery status updates
2779 config OLPC_XO15_SCI
2780 bool "OLPC XO-1.5 SCI extras"
2781 depends on OLPC && ACPI
2784 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2785 - EC-driven system wakeups
2786 - AC adapter status updates
2787 - Battery status updates
2790 bool "PCEngines ALIX System Support (LED setup)"
2793 This option enables system support for the PCEngines ALIX.
2794 At present this just sets up LEDs for GPIO control on
2795 ALIX2/3/6 boards. However, other system specific setup should
2798 Note: You must still enable the drivers for GPIO and LED support
2799 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2801 Note: You have to set alix.force=1 for boards with Award BIOS.
2804 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2807 This option enables system support for the Soekris Engineering net5501.
2810 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2814 This option enables system support for the Traverse Technologies GEOS.
2817 bool "Technologic Systems TS-5500 platform support"
2819 select CHECK_SIGNATURE
2823 This option enables system support for the Technologic Systems TS-5500.
2829 depends on CPU_SUP_AMD && PCI
2831 source "drivers/pcmcia/Kconfig"
2834 tristate "RapidIO support"
2838 If enabled this option will include drivers and the core
2839 infrastructure code to support RapidIO interconnect devices.
2841 source "drivers/rapidio/Kconfig"
2844 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2846 Firmwares often provide initial graphics framebuffers so the BIOS,
2847 bootloader or kernel can show basic video-output during boot for
2848 user-guidance and debugging. Historically, x86 used the VESA BIOS
2849 Extensions and EFI-framebuffers for this, which are mostly limited
2851 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2852 framebuffers so the new generic system-framebuffer drivers can be
2853 used on x86. If the framebuffer is not compatible with the generic
2854 modes, it is adverticed as fallback platform framebuffer so legacy
2855 drivers like efifb, vesafb and uvesafb can pick it up.
2856 If this option is not selected, all system framebuffers are always
2857 marked as fallback platform framebuffers as usual.
2859 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2860 not be able to pick up generic system framebuffers if this option
2861 is selected. You are highly encouraged to enable simplefb as
2862 replacement if you select this option. simplefb can correctly deal
2863 with generic system framebuffers. But you should still keep vesafb
2864 and others enabled as fallback if a system framebuffer is
2865 incompatible with simplefb.
2872 menu "Executable file formats / Emulations"
2874 source "fs/Kconfig.binfmt"
2876 config IA32_EMULATION
2877 bool "IA32 Emulation"
2879 select ARCH_WANT_OLD_COMPAT_IPC
2881 select COMPAT_BINFMT_ELF
2882 select COMPAT_OLD_SIGACTION
2884 Include code to run legacy 32-bit programs under a
2885 64-bit kernel. You should likely turn this on, unless you're
2886 100% sure that you don't have any 32-bit programs left.
2889 tristate "IA32 a.out support"
2890 depends on IA32_EMULATION
2892 Support old a.out binaries in the 32bit emulation.
2895 bool "x32 ABI for 64-bit mode"
2898 Include code to run binaries for the x32 native 32-bit ABI
2899 for 64-bit processors. An x32 process gets access to the
2900 full 64-bit register file and wide data path while leaving
2901 pointers at 32 bits for smaller memory footprint.
2903 You will need a recent binutils (2.22 or later) with
2904 elf32_x86_64 support enabled to compile a kernel with this
2909 depends on IA32_EMULATION || X86_32
2911 select OLD_SIGSUSPEND3
2915 depends on IA32_EMULATION || X86_X32
2918 config COMPAT_FOR_U64_ALIGNMENT
2921 config SYSVIPC_COMPAT
2929 config HAVE_ATOMIC_IOMAP
2933 config X86_DEV_DMA_OPS
2935 depends on X86_64 || STA2X11
2937 config X86_DMA_REMAP
2941 config HAVE_GENERIC_GUP
2944 source "net/Kconfig"
2946 source "drivers/Kconfig"
2948 source "drivers/firmware/Kconfig"
2952 source "arch/x86/Kconfig.debug"
2954 source "security/Kconfig"
2956 source "crypto/Kconfig"
2958 source "arch/x86/kvm/Kconfig"
2960 source "lib/Kconfig"