1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
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 NEED_DMA_MAP_STATE
33 select X86_DEV_DMA_OPS
34 select ARCH_HAS_SYSCALL_WRAPPER
39 # ( Note that options that are marked 'if X86_64' could in principle be
40 # ported to 32-bit as well. )
45 # Note: keep this list sorted alphabetically
47 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
48 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
50 select ARCH_CLOCKSOURCE_DATA
51 select ARCH_DISCARD_MEMBLOCK
52 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
53 select ARCH_HAS_DEBUG_VIRTUAL
54 select ARCH_HAS_DEVMEM_IS_ALLOWED
55 select ARCH_HAS_ELF_RANDOMIZE
56 select ARCH_HAS_FAST_MULTIPLIER
57 select ARCH_HAS_FILTER_PGPROT
58 select ARCH_HAS_FORTIFY_SOURCE
59 select ARCH_HAS_GCOV_PROFILE_ALL
60 select ARCH_HAS_KCOV if X86_64
61 select ARCH_HAS_MEMBARRIER_SYNC_CORE
62 select ARCH_HAS_PMEM_API if X86_64
63 select ARCH_HAS_PTE_SPECIAL
64 select ARCH_HAS_REFCOUNT
65 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
66 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
67 select ARCH_HAS_SET_MEMORY
68 select ARCH_HAS_SG_CHAIN
69 select ARCH_HAS_STRICT_KERNEL_RWX
70 select ARCH_HAS_STRICT_MODULE_RWX
71 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
72 select ARCH_HAS_UBSAN_SANITIZE_ALL
73 select ARCH_HAS_ZONE_DEVICE if X86_64
74 select ARCH_HAVE_NMI_SAFE_CMPXCHG
75 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
76 select ARCH_MIGHT_HAVE_PC_PARPORT
77 select ARCH_MIGHT_HAVE_PC_SERIO
78 select ARCH_SUPPORTS_ACPI
79 select ARCH_SUPPORTS_ATOMIC_RMW
80 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
81 select ARCH_USE_BUILTIN_BSWAP
82 select ARCH_USE_QUEUED_RWLOCKS
83 select ARCH_USE_QUEUED_SPINLOCKS
84 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
85 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
86 select ARCH_WANTS_THP_SWAP if X86_64
87 select BUILDTIME_EXTABLE_SORT
89 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
90 select CLOCKSOURCE_WATCHDOG
91 select DCACHE_WORD_ACCESS
93 select EDAC_ATOMIC_SCRUB
95 select GENERIC_CLOCKEVENTS
96 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
97 select GENERIC_CLOCKEVENTS_MIN_ADJUST
98 select GENERIC_CMOS_UPDATE
99 select GENERIC_CPU_AUTOPROBE
100 select GENERIC_CPU_VULNERABILITIES
101 select GENERIC_EARLY_IOREMAP
102 select GENERIC_FIND_FIRST_BIT
104 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
105 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
106 select GENERIC_IRQ_MIGRATION if SMP
107 select GENERIC_IRQ_PROBE
108 select GENERIC_IRQ_RESERVATION_MODE
109 select GENERIC_IRQ_SHOW
110 select GENERIC_PENDING_IRQ if SMP
111 select GENERIC_SMP_IDLE_THREAD
112 select GENERIC_STRNCPY_FROM_USER
113 select GENERIC_STRNLEN_USER
114 select GENERIC_TIME_VSYSCALL
115 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
116 select HAVE_ACPI_APEI if ACPI
117 select HAVE_ACPI_APEI_NMI if ACPI
118 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
119 select HAVE_ARCH_AUDITSYSCALL
120 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
121 select HAVE_ARCH_JUMP_LABEL
122 select HAVE_ARCH_KASAN if X86_64
123 select HAVE_ARCH_KGDB
124 select HAVE_ARCH_MMAP_RND_BITS if MMU
125 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
126 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
127 select HAVE_ARCH_PREL32_RELOCATIONS
128 select HAVE_ARCH_SECCOMP_FILTER
129 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
130 select HAVE_ARCH_TRACEHOOK
131 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
132 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
133 select HAVE_ARCH_VMAP_STACK if X86_64
134 select HAVE_ARCH_WITHIN_STACK_FRAMES
135 select HAVE_CMPXCHG_DOUBLE
136 select HAVE_CMPXCHG_LOCAL
137 select HAVE_CONTEXT_TRACKING if X86_64
138 select HAVE_COPY_THREAD_TLS
139 select HAVE_C_RECORDMCOUNT
140 select HAVE_DEBUG_KMEMLEAK
141 select HAVE_DEBUG_STACKOVERFLOW
142 select HAVE_DMA_CONTIGUOUS
143 select HAVE_DYNAMIC_FTRACE
144 select HAVE_DYNAMIC_FTRACE_WITH_REGS
146 select HAVE_EFFICIENT_UNALIGNED_ACCESS
147 select HAVE_EXIT_THREAD
148 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
149 select HAVE_FTRACE_MCOUNT_RECORD
150 select HAVE_FUNCTION_GRAPH_TRACER
151 select HAVE_FUNCTION_TRACER
152 select HAVE_GCC_PLUGINS
153 select HAVE_HW_BREAKPOINT
155 select HAVE_IOREMAP_PROT
156 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
157 select HAVE_IRQ_TIME_ACCOUNTING
158 select HAVE_KERNEL_BZIP2
159 select HAVE_KERNEL_GZIP
160 select HAVE_KERNEL_LZ4
161 select HAVE_KERNEL_LZMA
162 select HAVE_KERNEL_LZO
163 select HAVE_KERNEL_XZ
165 select HAVE_KPROBES_ON_FTRACE
166 select HAVE_FUNCTION_ERROR_INJECTION
167 select HAVE_KRETPROBES
169 select HAVE_LIVEPATCH if X86_64
171 select HAVE_MEMBLOCK_NODE_MAP
172 select HAVE_MIXED_BREAKPOINTS_REGS
173 select HAVE_MOD_ARCH_SPECIFIC
176 select HAVE_OPTPROBES
177 select HAVE_PCSPKR_PLATFORM
178 select HAVE_PERF_EVENTS
179 select HAVE_PERF_EVENTS_NMI
180 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
181 select HAVE_PERF_REGS
182 select HAVE_PERF_USER_STACK_DUMP
183 select HAVE_RCU_TABLE_FREE if PARAVIRT
184 select HAVE_RCU_TABLE_INVALIDATE if HAVE_RCU_TABLE_FREE
185 select HAVE_REGS_AND_STACK_ACCESS_API
186 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
187 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
188 select HAVE_STACK_VALIDATION if X86_64
190 select HAVE_SYSCALL_TRACEPOINTS
191 select HAVE_UNSTABLE_SCHED_CLOCK
192 select HAVE_USER_RETURN_NOTIFIER
193 select HOTPLUG_SMT if SMP
194 select IRQ_FORCED_THREADING
195 select NEED_SG_DMA_LENGTH
196 select PCI_LOCKLESS_CONFIG
199 select RTC_MC146818_LIB
202 select SYSCTL_EXCEPTION_TRACE
203 select THREAD_INFO_IN_TASK
204 select USER_STACKTRACE_SUPPORT
206 select X86_FEATURE_NAMES if PROC_FS
208 config INSTRUCTION_DECODER
210 depends on KPROBES || PERF_EVENTS || UPROBES
214 default "elf32-i386" if X86_32
215 default "elf64-x86-64" if X86_64
217 config ARCH_DEFCONFIG
219 default "arch/x86/configs/i386_defconfig" if X86_32
220 default "arch/x86/configs/x86_64_defconfig" if X86_64
222 config LOCKDEP_SUPPORT
225 config STACKTRACE_SUPPORT
231 config ARCH_MMAP_RND_BITS_MIN
235 config ARCH_MMAP_RND_BITS_MAX
239 config ARCH_MMAP_RND_COMPAT_BITS_MIN
242 config ARCH_MMAP_RND_COMPAT_BITS_MAX
248 config GENERIC_ISA_DMA
250 depends on ISA_DMA_API
255 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
257 config GENERIC_BUG_RELATIVE_POINTERS
260 config GENERIC_HWEIGHT
263 config ARCH_MAY_HAVE_PC_FDC
265 depends on ISA_DMA_API
267 config RWSEM_XCHGADD_ALGORITHM
270 config GENERIC_CALIBRATE_DELAY
273 config ARCH_HAS_CPU_RELAX
276 config ARCH_HAS_CACHE_LINE_SIZE
279 config ARCH_HAS_FILTER_PGPROT
282 config HAVE_SETUP_PER_CPU_AREA
285 config NEED_PER_CPU_EMBED_FIRST_CHUNK
288 config NEED_PER_CPU_PAGE_FIRST_CHUNK
291 config ARCH_HIBERNATION_POSSIBLE
294 config ARCH_SUSPEND_POSSIBLE
297 config ARCH_WANT_HUGE_PMD_SHARE
300 config ARCH_WANT_GENERAL_HUGETLB
309 config ARCH_SUPPORTS_OPTIMIZED_INLINING
312 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
315 config KASAN_SHADOW_OFFSET
318 default 0xdffffc0000000000
320 config HAVE_INTEL_TXT
322 depends on INTEL_IOMMU && ACPI
326 depends on X86_32 && SMP
330 depends on X86_64 && SMP
332 config X86_32_LAZY_GS
334 depends on X86_32 && !STACKPROTECTOR
336 config ARCH_SUPPORTS_UPROBES
339 config FIX_EARLYCON_MEM
342 config DYNAMIC_PHYSICAL_MASK
345 config PGTABLE_LEVELS
347 default 5 if X86_5LEVEL
352 config CC_HAS_SANE_STACKPROTECTOR
354 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
355 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
357 We have to make sure stack protector is unconditionally disabled if
358 the compiler produces broken code.
360 menu "Processor type and features"
363 bool "DMA memory allocation support" if EXPERT
366 DMA memory allocation support allows devices with less than 32-bit
367 addressing to allocate within the first 16MB of address space.
368 Disable if no such devices will be used.
373 bool "Symmetric multi-processing support"
375 This enables support for systems with more than one CPU. If you have
376 a system with only one CPU, say N. If you have a system with more
379 If you say N here, the kernel will run on uni- and multiprocessor
380 machines, but will use only one CPU of a multiprocessor machine. If
381 you say Y here, the kernel will run on many, but not all,
382 uniprocessor machines. On a uniprocessor machine, the kernel
383 will run faster if you say N here.
385 Note that if you say Y here and choose architecture "586" or
386 "Pentium" under "Processor family", the kernel will not work on 486
387 architectures. Similarly, multiprocessor kernels for the "PPro"
388 architecture may not work on all Pentium based boards.
390 People using multiprocessor machines who say Y here should also say
391 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
392 Management" code will be disabled if you say Y here.
394 See also <file:Documentation/x86/i386/IO-APIC.txt>,
395 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
396 <http://www.tldp.org/docs.html#howto>.
398 If you don't know what to do here, say N.
400 config X86_FEATURE_NAMES
401 bool "Processor feature human-readable names" if EMBEDDED
404 This option compiles in a table of x86 feature bits and corresponding
405 names. This is required to support /proc/cpuinfo and a few kernel
406 messages. You can disable this to save space, at the expense of
407 making those few kernel messages show numeric feature bits instead.
412 bool "Support x2apic"
413 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
415 This enables x2apic support on CPUs that have this feature.
417 This allows 32-bit apic IDs (so it can support very large systems),
418 and accesses the local apic via MSRs not via mmio.
420 If you don't know what to do here, say N.
423 bool "Enable MPS table" if ACPI || SFI
425 depends on X86_LOCAL_APIC
427 For old smp systems that do not have proper acpi support. Newer systems
428 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
432 depends on X86_GOLDFISH
435 bool "Avoid speculative indirect branches in kernel"
437 select STACK_VALIDATION if HAVE_STACK_VALIDATION
439 Compile kernel with the retpoline compiler options to guard against
440 kernel-to-user data leaks by avoiding speculative indirect
441 branches. Requires a compiler with -mindirect-branch=thunk-extern
442 support for full protection. The kernel may run slower.
445 bool "Intel Resource Director Technology support"
447 depends on X86 && CPU_SUP_INTEL
450 Select to enable resource allocation and monitoring which are
451 sub-features of Intel Resource Director Technology(RDT). More
452 information about RDT can be found in the Intel x86
453 Architecture Software Developer Manual.
459 bool "Support for big SMP systems with more than 8 CPUs"
462 This option is needed for the systems that have more than 8 CPUs
464 config X86_EXTENDED_PLATFORM
465 bool "Support for extended (non-PC) x86 platforms"
468 If you disable this option then the kernel will only support
469 standard PC platforms. (which covers the vast majority of
472 If you enable this option then you'll be able to select support
473 for the following (non-PC) 32 bit x86 platforms:
474 Goldfish (Android emulator)
477 SGI 320/540 (Visual Workstation)
478 STA2X11-based (e.g. Northville)
479 Moorestown MID devices
481 If you have one of these systems, or if you want to build a
482 generic distribution kernel, say Y here - otherwise say N.
486 config X86_EXTENDED_PLATFORM
487 bool "Support for extended (non-PC) x86 platforms"
490 If you disable this option then the kernel will only support
491 standard PC platforms. (which covers the vast majority of
494 If you enable this option then you'll be able to select support
495 for the following (non-PC) 64 bit x86 platforms:
500 If you have one of these systems, or if you want to build a
501 generic distribution kernel, say Y here - otherwise say N.
503 # This is an alphabetically sorted list of 64 bit extended platforms
504 # Please maintain the alphabetic order if and when there are additions
506 bool "Numascale NumaChip"
508 depends on X86_EXTENDED_PLATFORM
511 depends on X86_X2APIC
512 depends on PCI_MMCONFIG
514 Adds support for Numascale NumaChip large-SMP systems. Needed to
515 enable more than ~168 cores.
516 If you don't have one of these, you should say N here.
520 select HYPERVISOR_GUEST
522 depends on X86_64 && PCI
523 depends on X86_EXTENDED_PLATFORM
526 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
527 supposed to run on these EM64T-based machines. Only choose this option
528 if you have one of these machines.
531 bool "SGI Ultraviolet"
533 depends on X86_EXTENDED_PLATFORM
536 depends on X86_X2APIC
539 This option is needed in order to support SGI Ultraviolet systems.
540 If you don't have one of these, you should say N here.
542 # Following is an alphabetically sorted list of 32 bit extended platforms
543 # Please maintain the alphabetic order if and when there are additions
546 bool "Goldfish (Virtual Platform)"
547 depends on X86_EXTENDED_PLATFORM
549 Enable support for the Goldfish virtual platform used primarily
550 for Android development. Unless you are building for the Android
551 Goldfish emulator say N here.
554 bool "CE4100 TV platform"
556 depends on PCI_GODIRECT
557 depends on X86_IO_APIC
559 depends on X86_EXTENDED_PLATFORM
560 select X86_REBOOTFIXUPS
562 select OF_EARLY_FLATTREE
564 Select for the Intel CE media processor (CE4100) SOC.
565 This option compiles in support for the CE4100 SOC for settop
566 boxes and media devices.
569 bool "Intel MID platform support"
570 depends on X86_EXTENDED_PLATFORM
571 depends on X86_PLATFORM_DEVICES
573 depends on X86_64 || (PCI_GOANY && X86_32)
574 depends on X86_IO_APIC
580 select MFD_INTEL_MSIC
582 Select to build a kernel capable of supporting Intel MID (Mobile
583 Internet Device) platform systems which do not have the PCI legacy
584 interfaces. If you are building for a PC class system say N here.
586 Intel MID platforms are based on an Intel processor and chipset which
587 consume less power than most of the x86 derivatives.
589 config X86_INTEL_QUARK
590 bool "Intel Quark platform support"
592 depends on X86_EXTENDED_PLATFORM
593 depends on X86_PLATFORM_DEVICES
597 depends on X86_IO_APIC
602 Select to include support for Quark X1000 SoC.
603 Say Y here if you have a Quark based system such as the Arduino
604 compatible Intel Galileo.
606 config X86_INTEL_LPSS
607 bool "Intel Low Power Subsystem Support"
608 depends on X86 && ACPI
613 Select to build support for Intel Low Power Subsystem such as
614 found on Intel Lynxpoint PCH. Selecting this option enables
615 things like clock tree (common clock framework) and pincontrol
616 which are needed by the LPSS peripheral drivers.
618 config X86_AMD_PLATFORM_DEVICE
619 bool "AMD ACPI2Platform devices support"
624 Select to interpret AMD specific ACPI device to platform device
625 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
626 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
627 implemented under PINCTRL subsystem.
630 tristate "Intel SoC IOSF Sideband support for SoC platforms"
633 This option enables sideband register access support for Intel SoC
634 platforms. On these platforms the IOSF sideband is used in lieu of
635 MSR's for some register accesses, mostly but not limited to thermal
636 and power. Drivers may query the availability of this device to
637 determine if they need the sideband in order to work on these
638 platforms. The sideband is available on the following SoC products.
639 This list is not meant to be exclusive.
644 You should say Y if you are running a kernel on one of these SoC's.
646 config IOSF_MBI_DEBUG
647 bool "Enable IOSF sideband access through debugfs"
648 depends on IOSF_MBI && DEBUG_FS
650 Select this option to expose the IOSF sideband access registers (MCR,
651 MDR, MCRX) through debugfs to write and read register information from
652 different units on the SoC. This is most useful for obtaining device
653 state information for debug and analysis. As this is a general access
654 mechanism, users of this option would have specific knowledge of the
655 device they want to access.
657 If you don't require the option or are in doubt, say N.
660 bool "RDC R-321x SoC"
662 depends on X86_EXTENDED_PLATFORM
664 select X86_REBOOTFIXUPS
666 This option is needed for RDC R-321x system-on-chip, also known
668 If you don't have one of these chips, you should say N here.
670 config X86_32_NON_STANDARD
671 bool "Support non-standard 32-bit SMP architectures"
672 depends on X86_32 && SMP
673 depends on X86_EXTENDED_PLATFORM
675 This option compiles in the bigsmp and STA2X11 default
676 subarchitectures. It is intended for a generic binary
677 kernel. If you select them all, kernel will probe it one by
678 one and will fallback to default.
680 # Alphabetically sorted list of Non standard 32 bit platforms
682 config X86_SUPPORTS_MEMORY_FAILURE
684 # MCE code calls memory_failure():
686 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
687 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
688 depends on X86_64 || !SPARSEMEM
689 select ARCH_SUPPORTS_MEMORY_FAILURE
692 bool "STA2X11 Companion Chip Support"
693 depends on X86_32_NON_STANDARD && PCI
694 select ARCH_HAS_PHYS_TO_DMA
695 select X86_DEV_DMA_OPS
702 This adds support for boards based on the STA2X11 IO-Hub,
703 a.k.a. "ConneXt". The chip is used in place of the standard
704 PC chipset, so all "standard" peripherals are missing. If this
705 option is selected the kernel will still be able to boot on
706 standard PC machines.
709 tristate "Eurobraille/Iris poweroff module"
712 The Iris machines from EuroBraille do not have APM or ACPI support
713 to shut themselves down properly. A special I/O sequence is
714 needed to do so, which is what this module does at
717 This is only for Iris machines from EuroBraille.
721 config SCHED_OMIT_FRAME_POINTER
723 prompt "Single-depth WCHAN output"
726 Calculate simpler /proc/<PID>/wchan values. If this option
727 is disabled then wchan values will recurse back to the
728 caller function. This provides more accurate wchan values,
729 at the expense of slightly more scheduling overhead.
731 If in doubt, say "Y".
733 menuconfig HYPERVISOR_GUEST
734 bool "Linux guest support"
736 Say Y here to enable options for running Linux under various hyper-
737 visors. This option enables basic hypervisor detection and platform
740 If you say N, all options in this submenu will be skipped and
741 disabled, and Linux guest support won't be built in.
746 bool "Enable paravirtualization code"
748 This changes the kernel so it can modify itself when it is run
749 under a hypervisor, potentially improving performance significantly
750 over full virtualization. However, when run without a hypervisor
751 the kernel is theoretically slower and slightly larger.
753 config PARAVIRT_DEBUG
754 bool "paravirt-ops debugging"
755 depends on PARAVIRT && DEBUG_KERNEL
757 Enable to debug paravirt_ops internals. Specifically, BUG if
758 a paravirt_op is missing when it is called.
760 config PARAVIRT_SPINLOCKS
761 bool "Paravirtualization layer for spinlocks"
762 depends on PARAVIRT && SMP
764 Paravirtualized spinlocks allow a pvops backend to replace the
765 spinlock implementation with something virtualization-friendly
766 (for example, block the virtual CPU rather than spinning).
768 It has a minimal impact on native kernels and gives a nice performance
769 benefit on paravirtualized KVM / Xen kernels.
771 If you are unsure how to answer this question, answer Y.
773 config QUEUED_LOCK_STAT
774 bool "Paravirt queued spinlock statistics"
775 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
777 Enable the collection of statistical data on the slowpath
778 behavior of paravirtualized queued spinlocks and report
781 source "arch/x86/xen/Kconfig"
784 bool "KVM Guest support (including kvmclock)"
786 select PARAVIRT_CLOCK
789 This option enables various optimizations for running under the KVM
790 hypervisor. It includes a paravirtualized clock, so that instead
791 of relying on a PIT (or probably other) emulation by the
792 underlying device model, the host provides the guest with
793 timing infrastructure such as time of day, and system time
796 bool "Enable debug information for KVM Guests in debugfs"
797 depends on KVM_GUEST && DEBUG_FS
800 This option enables collection of various statistics for KVM guest.
801 Statistics are displayed in debugfs filesystem. Enabling this option
802 may incur significant overhead.
804 config PARAVIRT_TIME_ACCOUNTING
805 bool "Paravirtual steal time accounting"
809 Select this option to enable fine granularity task steal time
810 accounting. Time spent executing other tasks in parallel with
811 the current vCPU is discounted from the vCPU power. To account for
812 that, there can be a small performance impact.
814 If in doubt, say N here.
816 config PARAVIRT_CLOCK
819 config JAILHOUSE_GUEST
820 bool "Jailhouse non-root cell support"
821 depends on X86_64 && PCI
824 This option allows to run Linux as guest in a Jailhouse non-root
825 cell. You can leave this option disabled if you only want to start
826 Jailhouse and run Linux afterwards in the root cell.
828 endif #HYPERVISOR_GUEST
833 source "arch/x86/Kconfig.cpu"
837 prompt "HPET Timer Support" if X86_32
839 Use the IA-PC HPET (High Precision Event Timer) to manage
840 time in preference to the PIT and RTC, if a HPET is
842 HPET is the next generation timer replacing legacy 8254s.
843 The HPET provides a stable time base on SMP
844 systems, unlike the TSC, but it is more expensive to access,
845 as it is off-chip. The interface used is documented
846 in the HPET spec, revision 1.
848 You can safely choose Y here. However, HPET will only be
849 activated if the platform and the BIOS support this feature.
850 Otherwise the 8254 will be used for timing services.
852 Choose N to continue using the legacy 8254 timer.
854 config HPET_EMULATE_RTC
856 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
859 def_bool y if X86_INTEL_MID
860 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
862 depends on X86_INTEL_MID && SFI
864 APB timer is the replacement for 8254, HPET on X86 MID platforms.
865 The APBT provides a stable time base on SMP
866 systems, unlike the TSC, but it is more expensive to access,
867 as it is off-chip. APB timers are always running regardless of CPU
868 C states, they are used as per CPU clockevent device when possible.
870 # Mark as expert because too many people got it wrong.
871 # The code disables itself when not needed.
874 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
875 bool "Enable DMI scanning" if EXPERT
877 Enabled scanning of DMI to identify machine quirks. Say Y
878 here unless you have verified that your setup is not
879 affected by entries in the DMI blacklist. Required by PNP
883 bool "Old AMD GART IOMMU support"
886 depends on X86_64 && PCI && AMD_NB
888 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
889 GART based hardware IOMMUs.
891 The GART supports full DMA access for devices with 32-bit access
892 limitations, on systems with more than 3 GB. This is usually needed
893 for USB, sound, many IDE/SATA chipsets and some other devices.
895 Newer systems typically have a modern AMD IOMMU, supported via
896 the CONFIG_AMD_IOMMU=y config option.
898 In normal configurations this driver is only active when needed:
899 there's more than 3 GB of memory and the system contains a
900 32-bit limited device.
905 bool "IBM Calgary IOMMU support"
908 depends on X86_64 && PCI
910 Support for hardware IOMMUs in IBM's xSeries x366 and x460
911 systems. Needed to run systems with more than 3GB of memory
912 properly with 32-bit PCI devices that do not support DAC
913 (Double Address Cycle). Calgary also supports bus level
914 isolation, where all DMAs pass through the IOMMU. This
915 prevents them from going anywhere except their intended
916 destination. This catches hard-to-find kernel bugs and
917 mis-behaving drivers and devices that do not use the DMA-API
918 properly to set up their DMA buffers. The IOMMU can be
919 turned off at boot time with the iommu=off parameter.
920 Normally the kernel will make the right choice by itself.
923 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
925 prompt "Should Calgary be enabled by default?"
926 depends on CALGARY_IOMMU
928 Should Calgary be enabled by default? if you choose 'y', Calgary
929 will be used (if it exists). If you choose 'n', Calgary will not be
930 used even if it exists. If you choose 'n' and would like to use
931 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
935 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
936 depends on X86_64 && SMP && DEBUG_KERNEL
937 select CPUMASK_OFFSTACK
939 Enable maximum number of CPUS and NUMA Nodes for this architecture.
943 # The maximum number of CPUs supported:
945 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
946 # and which can be configured interactively in the
947 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
949 # The ranges are different on 32-bit and 64-bit kernels, depending on
950 # hardware capabilities and scalability features of the kernel.
952 # ( If MAXSMP is enabled we just use the highest possible value and disable
953 # interactive configuration. )
956 config NR_CPUS_RANGE_BEGIN
958 default NR_CPUS_RANGE_END if MAXSMP
962 config NR_CPUS_RANGE_END
965 default 64 if SMP && X86_BIGSMP
966 default 8 if SMP && !X86_BIGSMP
969 config NR_CPUS_RANGE_END
972 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
973 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
976 config NR_CPUS_DEFAULT
979 default 32 if X86_BIGSMP
983 config NR_CPUS_DEFAULT
986 default 8192 if MAXSMP
991 int "Maximum number of CPUs" if SMP && !MAXSMP
992 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
993 default NR_CPUS_DEFAULT
995 This allows you to specify the maximum number of CPUs which this
996 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
997 supported value is 8192, otherwise the maximum value is 512. The
998 minimum value which makes sense is 2.
1000 This is purely to save memory: each supported CPU adds about 8KB
1001 to the kernel image.
1004 bool "SMT (Hyperthreading) scheduler support"
1007 SMT scheduler support improves the CPU scheduler's decision making
1008 when dealing with Intel Pentium 4 chips with HyperThreading at a
1009 cost of slightly increased overhead in some places. If unsure say
1014 prompt "Multi-core scheduler support"
1017 Multi-core scheduler support improves the CPU scheduler's decision
1018 making when dealing with multi-core CPU chips at a cost of slightly
1019 increased overhead in some places. If unsure say N here.
1021 config SCHED_MC_PRIO
1022 bool "CPU core priorities scheduler support"
1023 depends on SCHED_MC && CPU_SUP_INTEL
1024 select X86_INTEL_PSTATE
1028 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1029 core ordering determined at manufacturing time, which allows
1030 certain cores to reach higher turbo frequencies (when running
1031 single threaded workloads) than others.
1033 Enabling this kernel feature teaches the scheduler about
1034 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1035 scheduler's CPU selection logic accordingly, so that higher
1036 overall system performance can be achieved.
1038 This feature will have no effect on CPUs without this feature.
1040 If unsure say Y here.
1044 depends on !SMP && X86_LOCAL_APIC
1047 bool "Local APIC support on uniprocessors" if !PCI_MSI
1049 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1051 A local APIC (Advanced Programmable Interrupt Controller) is an
1052 integrated interrupt controller in the CPU. If you have a single-CPU
1053 system which has a processor with a local APIC, you can say Y here to
1054 enable and use it. If you say Y here even though your machine doesn't
1055 have a local APIC, then the kernel will still run with no slowdown at
1056 all. The local APIC supports CPU-generated self-interrupts (timer,
1057 performance counters), and the NMI watchdog which detects hard
1060 config X86_UP_IOAPIC
1061 bool "IO-APIC support on uniprocessors"
1062 depends on X86_UP_APIC
1064 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1065 SMP-capable replacement for PC-style interrupt controllers. Most
1066 SMP systems and many recent uniprocessor systems have one.
1068 If you have a single-CPU system with an IO-APIC, you can say Y here
1069 to use it. If you say Y here even though your machine doesn't have
1070 an IO-APIC, then the kernel will still run with no slowdown at all.
1072 config X86_LOCAL_APIC
1074 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1075 select IRQ_DOMAIN_HIERARCHY
1076 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1080 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1082 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1083 bool "Reroute for broken boot IRQs"
1084 depends on X86_IO_APIC
1086 This option enables a workaround that fixes a source of
1087 spurious interrupts. This is recommended when threaded
1088 interrupt handling is used on systems where the generation of
1089 superfluous "boot interrupts" cannot be disabled.
1091 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1092 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1093 kernel does during interrupt handling). On chipsets where this
1094 boot IRQ generation cannot be disabled, this workaround keeps
1095 the original IRQ line masked so that only the equivalent "boot
1096 IRQ" is delivered to the CPUs. The workaround also tells the
1097 kernel to set up the IRQ handler on the boot IRQ line. In this
1098 way only one interrupt is delivered to the kernel. Otherwise
1099 the spurious second interrupt may cause the kernel to bring
1100 down (vital) interrupt lines.
1102 Only affects "broken" chipsets. Interrupt sharing may be
1103 increased on these systems.
1106 bool "Machine Check / overheating reporting"
1107 select GENERIC_ALLOCATOR
1110 Machine Check support allows the processor to notify the
1111 kernel if it detects a problem (e.g. overheating, data corruption).
1112 The action the kernel takes depends on the severity of the problem,
1113 ranging from warning messages to halting the machine.
1115 config X86_MCELOG_LEGACY
1116 bool "Support for deprecated /dev/mcelog character device"
1119 Enable support for /dev/mcelog which is needed by the old mcelog
1120 userspace logging daemon. Consider switching to the new generation
1123 config X86_MCE_INTEL
1125 prompt "Intel MCE features"
1126 depends on X86_MCE && X86_LOCAL_APIC
1128 Additional support for intel specific MCE features such as
1129 the thermal monitor.
1133 prompt "AMD MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1136 Additional support for AMD specific MCE features such as
1137 the DRAM Error Threshold.
1139 config X86_ANCIENT_MCE
1140 bool "Support for old Pentium 5 / WinChip machine checks"
1141 depends on X86_32 && X86_MCE
1143 Include support for machine check handling on old Pentium 5 or WinChip
1144 systems. These typically need to be enabled explicitly on the command
1147 config X86_MCE_THRESHOLD
1148 depends on X86_MCE_AMD || X86_MCE_INTEL
1151 config X86_MCE_INJECT
1152 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1153 tristate "Machine check injector support"
1155 Provide support for injecting machine checks for testing purposes.
1156 If you don't know what a machine check is and you don't do kernel
1157 QA it is safe to say n.
1159 config X86_THERMAL_VECTOR
1161 depends on X86_MCE_INTEL
1163 source "arch/x86/events/Kconfig"
1165 config X86_LEGACY_VM86
1166 bool "Legacy VM86 support"
1170 This option allows user programs to put the CPU into V8086
1171 mode, which is an 80286-era approximation of 16-bit real mode.
1173 Some very old versions of X and/or vbetool require this option
1174 for user mode setting. Similarly, DOSEMU will use it if
1175 available to accelerate real mode DOS programs. However, any
1176 recent version of DOSEMU, X, or vbetool should be fully
1177 functional even without kernel VM86 support, as they will all
1178 fall back to software emulation. Nevertheless, if you are using
1179 a 16-bit DOS program where 16-bit performance matters, vm86
1180 mode might be faster than emulation and you might want to
1183 Note that any app that works on a 64-bit kernel is unlikely to
1184 need this option, as 64-bit kernels don't, and can't, support
1185 V8086 mode. This option is also unrelated to 16-bit protected
1186 mode and is not needed to run most 16-bit programs under Wine.
1188 Enabling this option increases the complexity of the kernel
1189 and slows down exception handling a tiny bit.
1191 If unsure, say N here.
1195 default X86_LEGACY_VM86
1198 bool "Enable support for 16-bit segments" if EXPERT
1200 depends on MODIFY_LDT_SYSCALL
1202 This option is required by programs like Wine to run 16-bit
1203 protected mode legacy code on x86 processors. Disabling
1204 this option saves about 300 bytes on i386, or around 6K text
1205 plus 16K runtime memory on x86-64,
1209 depends on X86_16BIT && X86_32
1213 depends on X86_16BIT && X86_64
1215 config X86_VSYSCALL_EMULATION
1216 bool "Enable vsyscall emulation" if EXPERT
1220 This enables emulation of the legacy vsyscall page. Disabling
1221 it is roughly equivalent to booting with vsyscall=none, except
1222 that it will also disable the helpful warning if a program
1223 tries to use a vsyscall. With this option set to N, offending
1224 programs will just segfault, citing addresses of the form
1227 This option is required by many programs built before 2013, and
1228 care should be used even with newer programs if set to N.
1230 Disabling this option saves about 7K of kernel size and
1231 possibly 4K of additional runtime pagetable memory.
1234 tristate "Toshiba Laptop support"
1237 This adds a driver to safely access the System Management Mode of
1238 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1239 not work on models with a Phoenix BIOS. The System Management Mode
1240 is used to set the BIOS and power saving options on Toshiba portables.
1242 For information on utilities to make use of this driver see the
1243 Toshiba Linux utilities web site at:
1244 <http://www.buzzard.org.uk/toshiba/>.
1246 Say Y if you intend to run this kernel on a Toshiba portable.
1250 tristate "Dell i8k legacy laptop support"
1252 select SENSORS_DELL_SMM
1254 This option enables legacy /proc/i8k userspace interface in hwmon
1255 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1256 temperature and allows controlling fan speeds of Dell laptops via
1257 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1258 it reports also power and hotkey status. For fan speed control is
1259 needed userspace package i8kutils.
1261 Say Y if you intend to run this kernel on old Dell laptops or want to
1262 use userspace package i8kutils.
1265 config X86_REBOOTFIXUPS
1266 bool "Enable X86 board specific fixups for reboot"
1269 This enables chipset and/or board specific fixups to be done
1270 in order to get reboot to work correctly. This is only needed on
1271 some combinations of hardware and BIOS. The symptom, for which
1272 this config is intended, is when reboot ends with a stalled/hung
1275 Currently, the only fixup is for the Geode machines using
1276 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1278 Say Y if you want to enable the fixup. Currently, it's safe to
1279 enable this option even if you don't need it.
1283 bool "CPU microcode loading support"
1285 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1288 If you say Y here, you will be able to update the microcode on
1289 Intel and AMD processors. The Intel support is for the IA32 family,
1290 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1291 AMD support is for families 0x10 and later. You will obviously need
1292 the actual microcode binary data itself which is not shipped with
1295 The preferred method to load microcode from a detached initrd is described
1296 in Documentation/x86/microcode.txt. For that you need to enable
1297 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1298 initrd for microcode blobs.
1300 In addition, you can build the microcode into the kernel. For that you
1301 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1304 config MICROCODE_INTEL
1305 bool "Intel microcode loading support"
1306 depends on MICROCODE
1310 This options enables microcode patch loading support for Intel
1313 For the current Intel microcode data package go to
1314 <https://downloadcenter.intel.com> and search for
1315 'Linux Processor Microcode Data File'.
1317 config MICROCODE_AMD
1318 bool "AMD microcode loading support"
1319 depends on MICROCODE
1322 If you select this option, microcode patch loading support for AMD
1323 processors will be enabled.
1325 config MICROCODE_OLD_INTERFACE
1327 depends on MICROCODE
1330 tristate "/dev/cpu/*/msr - Model-specific register support"
1332 This device gives privileged processes access to the x86
1333 Model-Specific Registers (MSRs). It is a character device with
1334 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1335 MSR accesses are directed to a specific CPU on multi-processor
1339 tristate "/dev/cpu/*/cpuid - CPU information support"
1341 This device gives processes access to the x86 CPUID instruction to
1342 be executed on a specific processor. It is a character device
1343 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1347 prompt "High Memory Support"
1354 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1355 However, the address space of 32-bit x86 processors is only 4
1356 Gigabytes large. That means that, if you have a large amount of
1357 physical memory, not all of it can be "permanently mapped" by the
1358 kernel. The physical memory that's not permanently mapped is called
1361 If you are compiling a kernel which will never run on a machine with
1362 more than 1 Gigabyte total physical RAM, answer "off" here (default
1363 choice and suitable for most users). This will result in a "3GB/1GB"
1364 split: 3GB are mapped so that each process sees a 3GB virtual memory
1365 space and the remaining part of the 4GB virtual memory space is used
1366 by the kernel to permanently map as much physical memory as
1369 If the machine has between 1 and 4 Gigabytes physical RAM, then
1372 If more than 4 Gigabytes is used then answer "64GB" here. This
1373 selection turns Intel PAE (Physical Address Extension) mode on.
1374 PAE implements 3-level paging on IA32 processors. PAE is fully
1375 supported by Linux, PAE mode is implemented on all recent Intel
1376 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1377 then the kernel will not boot on CPUs that don't support PAE!
1379 The actual amount of total physical memory will either be
1380 auto detected or can be forced by using a kernel command line option
1381 such as "mem=256M". (Try "man bootparam" or see the documentation of
1382 your boot loader (lilo or loadlin) about how to pass options to the
1383 kernel at boot time.)
1385 If unsure, say "off".
1390 Select this if you have a 32-bit processor and between 1 and 4
1391 gigabytes of physical RAM.
1395 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1398 Select this if you have a 32-bit processor and more than 4
1399 gigabytes of physical RAM.
1404 prompt "Memory split" if EXPERT
1408 Select the desired split between kernel and user memory.
1410 If the address range available to the kernel is less than the
1411 physical memory installed, the remaining memory will be available
1412 as "high memory". Accessing high memory is a little more costly
1413 than low memory, as it needs to be mapped into the kernel first.
1414 Note that increasing the kernel address space limits the range
1415 available to user programs, making the address space there
1416 tighter. Selecting anything other than the default 3G/1G split
1417 will also likely make your kernel incompatible with binary-only
1420 If you are not absolutely sure what you are doing, leave this
1424 bool "3G/1G user/kernel split"
1425 config VMSPLIT_3G_OPT
1427 bool "3G/1G user/kernel split (for full 1G low memory)"
1429 bool "2G/2G user/kernel split"
1430 config VMSPLIT_2G_OPT
1432 bool "2G/2G user/kernel split (for full 2G low memory)"
1434 bool "1G/3G user/kernel split"
1439 default 0xB0000000 if VMSPLIT_3G_OPT
1440 default 0x80000000 if VMSPLIT_2G
1441 default 0x78000000 if VMSPLIT_2G_OPT
1442 default 0x40000000 if VMSPLIT_1G
1448 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1451 bool "PAE (Physical Address Extension) Support"
1452 depends on X86_32 && !HIGHMEM4G
1453 select PHYS_ADDR_T_64BIT
1456 PAE is required for NX support, and furthermore enables
1457 larger swapspace support for non-overcommit purposes. It
1458 has the cost of more pagetable lookup overhead, and also
1459 consumes more pagetable space per process.
1462 bool "Enable 5-level page tables support"
1463 select DYNAMIC_MEMORY_LAYOUT
1464 select SPARSEMEM_VMEMMAP
1467 5-level paging enables access to larger address space:
1468 upto 128 PiB of virtual address space and 4 PiB of
1469 physical address space.
1471 It will be supported by future Intel CPUs.
1473 A kernel with the option enabled can be booted on machines that
1474 support 4- or 5-level paging.
1476 See Documentation/x86/x86_64/5level-paging.txt for more
1481 config X86_DIRECT_GBPAGES
1483 depends on X86_64 && !DEBUG_PAGEALLOC
1485 Certain kernel features effectively disable kernel
1486 linear 1 GB mappings (even if the CPU otherwise
1487 supports them), so don't confuse the user by printing
1488 that we have them enabled.
1490 config ARCH_HAS_MEM_ENCRYPT
1493 config AMD_MEM_ENCRYPT
1494 bool "AMD Secure Memory Encryption (SME) support"
1495 depends on X86_64 && CPU_SUP_AMD
1496 select DYNAMIC_PHYSICAL_MASK
1498 Say yes to enable support for the encryption of system memory.
1499 This requires an AMD processor that supports Secure Memory
1502 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1503 bool "Activate AMD Secure Memory Encryption (SME) by default"
1505 depends on AMD_MEM_ENCRYPT
1507 Say yes to have system memory encrypted by default if running on
1508 an AMD processor that supports Secure Memory Encryption (SME).
1510 If set to Y, then the encryption of system memory can be
1511 deactivated with the mem_encrypt=off command line option.
1513 If set to N, then the encryption of system memory can be
1514 activated with the mem_encrypt=on command line option.
1516 config ARCH_USE_MEMREMAP_PROT
1518 depends on AMD_MEM_ENCRYPT
1520 # Common NUMA Features
1522 bool "Numa Memory Allocation and Scheduler Support"
1524 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1525 default y if X86_BIGSMP
1527 Enable NUMA (Non Uniform Memory Access) support.
1529 The kernel will try to allocate memory used by a CPU on the
1530 local memory controller of the CPU and add some more
1531 NUMA awareness to the kernel.
1533 For 64-bit this is recommended if the system is Intel Core i7
1534 (or later), AMD Opteron, or EM64T NUMA.
1536 For 32-bit this is only needed if you boot a 32-bit
1537 kernel on a 64-bit NUMA platform.
1539 Otherwise, you should say N.
1543 prompt "Old style AMD Opteron NUMA detection"
1544 depends on X86_64 && NUMA && PCI
1546 Enable AMD NUMA node topology detection. You should say Y here if
1547 you have a multi processor AMD system. This uses an old method to
1548 read the NUMA configuration directly from the builtin Northbridge
1549 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1550 which also takes priority if both are compiled in.
1552 config X86_64_ACPI_NUMA
1554 prompt "ACPI NUMA detection"
1555 depends on X86_64 && NUMA && ACPI && PCI
1558 Enable ACPI SRAT based node topology detection.
1560 # Some NUMA nodes have memory ranges that span
1561 # other nodes. Even though a pfn is valid and
1562 # between a node's start and end pfns, it may not
1563 # reside on that node. See memmap_init_zone()
1565 config NODES_SPAN_OTHER_NODES
1567 depends on X86_64_ACPI_NUMA
1570 bool "NUMA emulation"
1573 Enable NUMA emulation. A flat machine will be split
1574 into virtual nodes when booted with "numa=fake=N", where N is the
1575 number of nodes. This is only useful for debugging.
1578 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1580 default "10" if MAXSMP
1581 default "6" if X86_64
1583 depends on NEED_MULTIPLE_NODES
1585 Specify the maximum number of NUMA Nodes available on the target
1586 system. Increases memory reserved to accommodate various tables.
1588 config ARCH_HAVE_MEMORY_PRESENT
1590 depends on X86_32 && DISCONTIGMEM
1592 config ARCH_FLATMEM_ENABLE
1594 depends on X86_32 && !NUMA
1596 config ARCH_DISCONTIGMEM_ENABLE
1598 depends on NUMA && X86_32
1600 config ARCH_DISCONTIGMEM_DEFAULT
1602 depends on NUMA && X86_32
1604 config ARCH_SPARSEMEM_ENABLE
1606 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1607 select SPARSEMEM_STATIC if X86_32
1608 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1610 config ARCH_SPARSEMEM_DEFAULT
1614 config ARCH_SELECT_MEMORY_MODEL
1616 depends on ARCH_SPARSEMEM_ENABLE
1618 config ARCH_MEMORY_PROBE
1619 bool "Enable sysfs memory/probe interface"
1620 depends on X86_64 && MEMORY_HOTPLUG
1622 This option enables a sysfs memory/probe interface for testing.
1623 See Documentation/memory-hotplug.txt for more information.
1624 If you are unsure how to answer this question, answer N.
1626 config ARCH_PROC_KCORE_TEXT
1628 depends on X86_64 && PROC_KCORE
1630 config ILLEGAL_POINTER_VALUE
1633 default 0xdead000000000000 if X86_64
1635 config X86_PMEM_LEGACY_DEVICE
1638 config X86_PMEM_LEGACY
1639 tristate "Support non-standard NVDIMMs and ADR protected memory"
1640 depends on PHYS_ADDR_T_64BIT
1642 select X86_PMEM_LEGACY_DEVICE
1645 Treat memory marked using the non-standard e820 type of 12 as used
1646 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1647 The kernel will offer these regions to the 'pmem' driver so
1648 they can be used for persistent storage.
1653 bool "Allocate 3rd-level pagetables from highmem"
1656 The VM uses one page table entry for each page of physical memory.
1657 For systems with a lot of RAM, this can be wasteful of precious
1658 low memory. Setting this option will put user-space page table
1659 entries in high memory.
1661 config X86_CHECK_BIOS_CORRUPTION
1662 bool "Check for low memory corruption"
1664 Periodically check for memory corruption in low memory, which
1665 is suspected to be caused by BIOS. Even when enabled in the
1666 configuration, it is disabled at runtime. Enable it by
1667 setting "memory_corruption_check=1" on the kernel command
1668 line. By default it scans the low 64k of memory every 60
1669 seconds; see the memory_corruption_check_size and
1670 memory_corruption_check_period parameters in
1671 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1673 When enabled with the default parameters, this option has
1674 almost no overhead, as it reserves a relatively small amount
1675 of memory and scans it infrequently. It both detects corruption
1676 and prevents it from affecting the running system.
1678 It is, however, intended as a diagnostic tool; if repeatable
1679 BIOS-originated corruption always affects the same memory,
1680 you can use memmap= to prevent the kernel from using that
1683 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1684 bool "Set the default setting of memory_corruption_check"
1685 depends on X86_CHECK_BIOS_CORRUPTION
1688 Set whether the default state of memory_corruption_check is
1691 config X86_RESERVE_LOW
1692 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1696 Specify the amount of low memory to reserve for the BIOS.
1698 The first page contains BIOS data structures that the kernel
1699 must not use, so that page must always be reserved.
1701 By default we reserve the first 64K of physical RAM, as a
1702 number of BIOSes are known to corrupt that memory range
1703 during events such as suspend/resume or monitor cable
1704 insertion, so it must not be used by the kernel.
1706 You can set this to 4 if you are absolutely sure that you
1707 trust the BIOS to get all its memory reservations and usages
1708 right. If you know your BIOS have problems beyond the
1709 default 64K area, you can set this to 640 to avoid using the
1710 entire low memory range.
1712 If you have doubts about the BIOS (e.g. suspend/resume does
1713 not work or there's kernel crashes after certain hardware
1714 hotplug events) then you might want to enable
1715 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1716 typical corruption patterns.
1718 Leave this to the default value of 64 if you are unsure.
1720 config MATH_EMULATION
1722 depends on MODIFY_LDT_SYSCALL
1723 prompt "Math emulation" if X86_32
1725 Linux can emulate a math coprocessor (used for floating point
1726 operations) if you don't have one. 486DX and Pentium processors have
1727 a math coprocessor built in, 486SX and 386 do not, unless you added
1728 a 487DX or 387, respectively. (The messages during boot time can
1729 give you some hints here ["man dmesg"].) Everyone needs either a
1730 coprocessor or this emulation.
1732 If you don't have a math coprocessor, you need to say Y here; if you
1733 say Y here even though you have a coprocessor, the coprocessor will
1734 be used nevertheless. (This behavior can be changed with the kernel
1735 command line option "no387", which comes handy if your coprocessor
1736 is broken. Try "man bootparam" or see the documentation of your boot
1737 loader (lilo or loadlin) about how to pass options to the kernel at
1738 boot time.) This means that it is a good idea to say Y here if you
1739 intend to use this kernel on different machines.
1741 More information about the internals of the Linux math coprocessor
1742 emulation can be found in <file:arch/x86/math-emu/README>.
1744 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1745 kernel, it won't hurt.
1749 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1751 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1752 the Memory Type Range Registers (MTRRs) may be used to control
1753 processor access to memory ranges. This is most useful if you have
1754 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1755 allows bus write transfers to be combined into a larger transfer
1756 before bursting over the PCI/AGP bus. This can increase performance
1757 of image write operations 2.5 times or more. Saying Y here creates a
1758 /proc/mtrr file which may be used to manipulate your processor's
1759 MTRRs. Typically the X server should use this.
1761 This code has a reasonably generic interface so that similar
1762 control registers on other processors can be easily supported
1765 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1766 Registers (ARRs) which provide a similar functionality to MTRRs. For
1767 these, the ARRs are used to emulate the MTRRs.
1768 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1769 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1770 write-combining. All of these processors are supported by this code
1771 and it makes sense to say Y here if you have one of them.
1773 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1774 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1775 can lead to all sorts of problems, so it's good to say Y here.
1777 You can safely say Y even if your machine doesn't have MTRRs, you'll
1778 just add about 9 KB to your kernel.
1780 See <file:Documentation/x86/mtrr.txt> for more information.
1782 config MTRR_SANITIZER
1784 prompt "MTRR cleanup support"
1787 Convert MTRR layout from continuous to discrete, so X drivers can
1788 add writeback entries.
1790 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1791 The largest mtrr entry size for a continuous block can be set with
1796 config MTRR_SANITIZER_ENABLE_DEFAULT
1797 int "MTRR cleanup enable value (0-1)"
1800 depends on MTRR_SANITIZER
1802 Enable mtrr cleanup default value
1804 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1805 int "MTRR cleanup spare reg num (0-7)"
1808 depends on MTRR_SANITIZER
1810 mtrr cleanup spare entries default, it can be changed via
1811 mtrr_spare_reg_nr=N on the kernel command line.
1815 prompt "x86 PAT support" if EXPERT
1818 Use PAT attributes to setup page level cache control.
1820 PATs are the modern equivalents of MTRRs and are much more
1821 flexible than MTRRs.
1823 Say N here if you see bootup problems (boot crash, boot hang,
1824 spontaneous reboots) or a non-working video driver.
1828 config ARCH_USES_PG_UNCACHED
1834 prompt "x86 architectural random number generator" if EXPERT
1836 Enable the x86 architectural RDRAND instruction
1837 (Intel Bull Mountain technology) to generate random numbers.
1838 If supported, this is a high bandwidth, cryptographically
1839 secure hardware random number generator.
1843 prompt "Supervisor Mode Access Prevention" if EXPERT
1845 Supervisor Mode Access Prevention (SMAP) is a security
1846 feature in newer Intel processors. There is a small
1847 performance cost if this enabled and turned on; there is
1848 also a small increase in the kernel size if this is enabled.
1852 config X86_INTEL_UMIP
1854 depends on CPU_SUP_INTEL
1855 prompt "Intel User Mode Instruction Prevention" if EXPERT
1857 The User Mode Instruction Prevention (UMIP) is a security
1858 feature in newer Intel processors. If enabled, a general
1859 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1860 or STR instructions are executed in user mode. These instructions
1861 unnecessarily expose information about the hardware state.
1863 The vast majority of applications do not use these instructions.
1864 For the very few that do, software emulation is provided in
1865 specific cases in protected and virtual-8086 modes. Emulated
1868 config X86_INTEL_MPX
1869 prompt "Intel MPX (Memory Protection Extensions)"
1871 # Note: only available in 64-bit mode due to VMA flags shortage
1872 depends on CPU_SUP_INTEL && X86_64
1873 select ARCH_USES_HIGH_VMA_FLAGS
1875 MPX provides hardware features that can be used in
1876 conjunction with compiler-instrumented code to check
1877 memory references. It is designed to detect buffer
1878 overflow or underflow bugs.
1880 This option enables running applications which are
1881 instrumented or otherwise use MPX. It does not use MPX
1882 itself inside the kernel or to protect the kernel
1883 against bad memory references.
1885 Enabling this option will make the kernel larger:
1886 ~8k of kernel text and 36 bytes of data on a 64-bit
1887 defconfig. It adds a long to the 'mm_struct' which
1888 will increase the kernel memory overhead of each
1889 process and adds some branches to paths used during
1890 exec() and munmap().
1892 For details, see Documentation/x86/intel_mpx.txt
1896 config X86_INTEL_MEMORY_PROTECTION_KEYS
1897 prompt "Intel Memory Protection Keys"
1899 # Note: only available in 64-bit mode
1900 depends on CPU_SUP_INTEL && X86_64
1901 select ARCH_USES_HIGH_VMA_FLAGS
1902 select ARCH_HAS_PKEYS
1904 Memory Protection Keys provides a mechanism for enforcing
1905 page-based protections, but without requiring modification of the
1906 page tables when an application changes protection domains.
1908 For details, see Documentation/x86/protection-keys.txt
1913 bool "EFI runtime service support"
1916 select EFI_RUNTIME_WRAPPERS
1918 This enables the kernel to use EFI runtime services that are
1919 available (such as the EFI variable services).
1921 This option is only useful on systems that have EFI firmware.
1922 In addition, you should use the latest ELILO loader available
1923 at <http://elilo.sourceforge.net> in order to take advantage
1924 of EFI runtime services. However, even with this option, the
1925 resultant kernel should continue to boot on existing non-EFI
1929 bool "EFI stub support"
1930 depends on EFI && !X86_USE_3DNOW
1933 This kernel feature allows a bzImage to be loaded directly
1934 by EFI firmware without the use of a bootloader.
1936 See Documentation/efi-stub.txt for more information.
1939 bool "EFI mixed-mode support"
1940 depends on EFI_STUB && X86_64
1942 Enabling this feature allows a 64-bit kernel to be booted
1943 on a 32-bit firmware, provided that your CPU supports 64-bit
1946 Note that it is not possible to boot a mixed-mode enabled
1947 kernel via the EFI boot stub - a bootloader that supports
1948 the EFI handover protocol must be used.
1954 prompt "Enable seccomp to safely compute untrusted bytecode"
1956 This kernel feature is useful for number crunching applications
1957 that may need to compute untrusted bytecode during their
1958 execution. By using pipes or other transports made available to
1959 the process as file descriptors supporting the read/write
1960 syscalls, it's possible to isolate those applications in
1961 their own address space using seccomp. Once seccomp is
1962 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1963 and the task is only allowed to execute a few safe syscalls
1964 defined by each seccomp mode.
1966 If unsure, say Y. Only embedded should say N here.
1968 source kernel/Kconfig.hz
1971 bool "kexec system call"
1974 kexec is a system call that implements the ability to shutdown your
1975 current kernel, and to start another kernel. It is like a reboot
1976 but it is independent of the system firmware. And like a reboot
1977 you can start any kernel with it, not just Linux.
1979 The name comes from the similarity to the exec system call.
1981 It is an ongoing process to be certain the hardware in a machine
1982 is properly shutdown, so do not be surprised if this code does not
1983 initially work for you. As of this writing the exact hardware
1984 interface is strongly in flux, so no good recommendation can be
1988 bool "kexec file based system call"
1993 depends on CRYPTO_SHA256=y
1995 This is new version of kexec system call. This system call is
1996 file based and takes file descriptors as system call argument
1997 for kernel and initramfs as opposed to list of segments as
1998 accepted by previous system call.
2000 config ARCH_HAS_KEXEC_PURGATORY
2003 config KEXEC_VERIFY_SIG
2004 bool "Verify kernel signature during kexec_file_load() syscall"
2005 depends on KEXEC_FILE
2007 This option makes kernel signature verification mandatory for
2008 the kexec_file_load() syscall.
2010 In addition to that option, you need to enable signature
2011 verification for the corresponding kernel image type being
2012 loaded in order for this to work.
2014 config KEXEC_BZIMAGE_VERIFY_SIG
2015 bool "Enable bzImage signature verification support"
2016 depends on KEXEC_VERIFY_SIG
2017 depends on SIGNED_PE_FILE_VERIFICATION
2018 select SYSTEM_TRUSTED_KEYRING
2020 Enable bzImage signature verification support.
2023 bool "kernel crash dumps"
2024 depends on X86_64 || (X86_32 && HIGHMEM)
2026 Generate crash dump after being started by kexec.
2027 This should be normally only set in special crash dump kernels
2028 which are loaded in the main kernel with kexec-tools into
2029 a specially reserved region and then later executed after
2030 a crash by kdump/kexec. The crash dump kernel must be compiled
2031 to a memory address not used by the main kernel or BIOS using
2032 PHYSICAL_START, or it must be built as a relocatable image
2033 (CONFIG_RELOCATABLE=y).
2034 For more details see Documentation/kdump/kdump.txt
2038 depends on KEXEC && HIBERNATION
2040 Jump between original kernel and kexeced kernel and invoke
2041 code in physical address mode via KEXEC
2043 config PHYSICAL_START
2044 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2047 This gives the physical address where the kernel is loaded.
2049 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2050 bzImage will decompress itself to above physical address and
2051 run from there. Otherwise, bzImage will run from the address where
2052 it has been loaded by the boot loader and will ignore above physical
2055 In normal kdump cases one does not have to set/change this option
2056 as now bzImage can be compiled as a completely relocatable image
2057 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2058 address. This option is mainly useful for the folks who don't want
2059 to use a bzImage for capturing the crash dump and want to use a
2060 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2061 to be specifically compiled to run from a specific memory area
2062 (normally a reserved region) and this option comes handy.
2064 So if you are using bzImage for capturing the crash dump,
2065 leave the value here unchanged to 0x1000000 and set
2066 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2067 for capturing the crash dump change this value to start of
2068 the reserved region. In other words, it can be set based on
2069 the "X" value as specified in the "crashkernel=YM@XM"
2070 command line boot parameter passed to the panic-ed
2071 kernel. Please take a look at Documentation/kdump/kdump.txt
2072 for more details about crash dumps.
2074 Usage of bzImage for capturing the crash dump is recommended as
2075 one does not have to build two kernels. Same kernel can be used
2076 as production kernel and capture kernel. Above option should have
2077 gone away after relocatable bzImage support is introduced. But it
2078 is present because there are users out there who continue to use
2079 vmlinux for dump capture. This option should go away down the
2082 Don't change this unless you know what you are doing.
2085 bool "Build a relocatable kernel"
2088 This builds a kernel image that retains relocation information
2089 so it can be loaded someplace besides the default 1MB.
2090 The relocations tend to make the kernel binary about 10% larger,
2091 but are discarded at runtime.
2093 One use is for the kexec on panic case where the recovery kernel
2094 must live at a different physical address than the primary
2097 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2098 it has been loaded at and the compile time physical address
2099 (CONFIG_PHYSICAL_START) is used as the minimum location.
2101 config RANDOMIZE_BASE
2102 bool "Randomize the address of the kernel image (KASLR)"
2103 depends on RELOCATABLE
2106 In support of Kernel Address Space Layout Randomization (KASLR),
2107 this randomizes the physical address at which the kernel image
2108 is decompressed and the virtual address where the kernel
2109 image is mapped, as a security feature that deters exploit
2110 attempts relying on knowledge of the location of kernel
2113 On 64-bit, the kernel physical and virtual addresses are
2114 randomized separately. The physical address will be anywhere
2115 between 16MB and the top of physical memory (up to 64TB). The
2116 virtual address will be randomized from 16MB up to 1GB (9 bits
2117 of entropy). Note that this also reduces the memory space
2118 available to kernel modules from 1.5GB to 1GB.
2120 On 32-bit, the kernel physical and virtual addresses are
2121 randomized together. They will be randomized from 16MB up to
2122 512MB (8 bits of entropy).
2124 Entropy is generated using the RDRAND instruction if it is
2125 supported. If RDTSC is supported, its value is mixed into
2126 the entropy pool as well. If neither RDRAND nor RDTSC are
2127 supported, then entropy is read from the i8254 timer. The
2128 usable entropy is limited by the kernel being built using
2129 2GB addressing, and that PHYSICAL_ALIGN must be at a
2130 minimum of 2MB. As a result, only 10 bits of entropy are
2131 theoretically possible, but the implementations are further
2132 limited due to memory layouts.
2136 # Relocation on x86 needs some additional build support
2137 config X86_NEED_RELOCS
2139 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2141 config PHYSICAL_ALIGN
2142 hex "Alignment value to which kernel should be aligned"
2144 range 0x2000 0x1000000 if X86_32
2145 range 0x200000 0x1000000 if X86_64
2147 This value puts the alignment restrictions on physical address
2148 where kernel is loaded and run from. Kernel is compiled for an
2149 address which meets above alignment restriction.
2151 If bootloader loads the kernel at a non-aligned address and
2152 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2153 address aligned to above value and run from there.
2155 If bootloader loads the kernel at a non-aligned address and
2156 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2157 load address and decompress itself to the address it has been
2158 compiled for and run from there. The address for which kernel is
2159 compiled already meets above alignment restrictions. Hence the
2160 end result is that kernel runs from a physical address meeting
2161 above alignment restrictions.
2163 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2164 this value must be a multiple of 0x200000.
2166 Don't change this unless you know what you are doing.
2168 config DYNAMIC_MEMORY_LAYOUT
2171 This option makes base addresses of vmalloc and vmemmap as well as
2172 __PAGE_OFFSET movable during boot.
2174 config RANDOMIZE_MEMORY
2175 bool "Randomize the kernel memory sections"
2177 depends on RANDOMIZE_BASE
2178 select DYNAMIC_MEMORY_LAYOUT
2179 default RANDOMIZE_BASE
2181 Randomizes the base virtual address of kernel memory sections
2182 (physical memory mapping, vmalloc & vmemmap). This security feature
2183 makes exploits relying on predictable memory locations less reliable.
2185 The order of allocations remains unchanged. Entropy is generated in
2186 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2187 configuration have in average 30,000 different possible virtual
2188 addresses for each memory section.
2192 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2193 hex "Physical memory mapping padding" if EXPERT
2194 depends on RANDOMIZE_MEMORY
2195 default "0xa" if MEMORY_HOTPLUG
2197 range 0x1 0x40 if MEMORY_HOTPLUG
2200 Define the padding in terabytes added to the existing physical
2201 memory size during kernel memory randomization. It is useful
2202 for memory hotplug support but reduces the entropy available for
2203 address randomization.
2205 If unsure, leave at the default value.
2208 bool "Support for hot-pluggable CPUs"
2211 Say Y here to allow turning CPUs off and on. CPUs can be
2212 controlled through /sys/devices/system/cpu.
2213 ( Note: power management support will enable this option
2214 automatically on SMP systems. )
2215 Say N if you want to disable CPU hotplug.
2217 config BOOTPARAM_HOTPLUG_CPU0
2218 bool "Set default setting of cpu0_hotpluggable"
2220 depends on HOTPLUG_CPU
2222 Set whether default state of cpu0_hotpluggable is on or off.
2224 Say Y here to enable CPU0 hotplug by default. If this switch
2225 is turned on, there is no need to give cpu0_hotplug kernel
2226 parameter and the CPU0 hotplug feature is enabled by default.
2228 Please note: there are two known CPU0 dependencies if you want
2229 to enable the CPU0 hotplug feature either by this switch or by
2230 cpu0_hotplug kernel parameter.
2232 First, resume from hibernate or suspend always starts from CPU0.
2233 So hibernate and suspend are prevented if CPU0 is offline.
2235 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2236 offline if any interrupt can not migrate out of CPU0. There may
2237 be other CPU0 dependencies.
2239 Please make sure the dependencies are under your control before
2240 you enable this feature.
2242 Say N if you don't want to enable CPU0 hotplug feature by default.
2243 You still can enable the CPU0 hotplug feature at boot by kernel
2244 parameter cpu0_hotplug.
2246 config DEBUG_HOTPLUG_CPU0
2248 prompt "Debug CPU0 hotplug"
2249 depends on HOTPLUG_CPU
2251 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2252 soon as possible and boots up userspace with CPU0 offlined. User
2253 can online CPU0 back after boot time.
2255 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2256 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2257 compilation or giving cpu0_hotplug kernel parameter at boot.
2263 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2264 depends on COMPAT_32
2266 Certain buggy versions of glibc will crash if they are
2267 presented with a 32-bit vDSO that is not mapped at the address
2268 indicated in its segment table.
2270 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2271 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2272 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2273 the only released version with the bug, but OpenSUSE 9
2274 contains a buggy "glibc 2.3.2".
2276 The symptom of the bug is that everything crashes on startup, saying:
2277 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2279 Saying Y here changes the default value of the vdso32 boot
2280 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2281 This works around the glibc bug but hurts performance.
2283 If unsure, say N: if you are compiling your own kernel, you
2284 are unlikely to be using a buggy version of glibc.
2287 prompt "vsyscall table for legacy applications"
2289 default LEGACY_VSYSCALL_EMULATE
2291 Legacy user code that does not know how to find the vDSO expects
2292 to be able to issue three syscalls by calling fixed addresses in
2293 kernel space. Since this location is not randomized with ASLR,
2294 it can be used to assist security vulnerability exploitation.
2296 This setting can be changed at boot time via the kernel command
2297 line parameter vsyscall=[emulate|none].
2299 On a system with recent enough glibc (2.14 or newer) and no
2300 static binaries, you can say None without a performance penalty
2301 to improve security.
2303 If unsure, select "Emulate".
2305 config LEGACY_VSYSCALL_EMULATE
2308 The kernel traps and emulates calls into the fixed
2309 vsyscall address mapping. This makes the mapping
2310 non-executable, but it still contains known contents,
2311 which could be used in certain rare security vulnerability
2312 exploits. This configuration is recommended when userspace
2313 still uses the vsyscall area.
2315 config LEGACY_VSYSCALL_NONE
2318 There will be no vsyscall mapping at all. This will
2319 eliminate any risk of ASLR bypass due to the vsyscall
2320 fixed address mapping. Attempts to use the vsyscalls
2321 will be reported to dmesg, so that either old or
2322 malicious userspace programs can be identified.
2327 bool "Built-in kernel command line"
2329 Allow for specifying boot arguments to the kernel at
2330 build time. On some systems (e.g. embedded ones), it is
2331 necessary or convenient to provide some or all of the
2332 kernel boot arguments with the kernel itself (that is,
2333 to not rely on the boot loader to provide them.)
2335 To compile command line arguments into the kernel,
2336 set this option to 'Y', then fill in the
2337 boot arguments in CONFIG_CMDLINE.
2339 Systems with fully functional boot loaders (i.e. non-embedded)
2340 should leave this option set to 'N'.
2343 string "Built-in kernel command string"
2344 depends on CMDLINE_BOOL
2347 Enter arguments here that should be compiled into the kernel
2348 image and used at boot time. If the boot loader provides a
2349 command line at boot time, it is appended to this string to
2350 form the full kernel command line, when the system boots.
2352 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2353 change this behavior.
2355 In most cases, the command line (whether built-in or provided
2356 by the boot loader) should specify the device for the root
2359 config CMDLINE_OVERRIDE
2360 bool "Built-in command line overrides boot loader arguments"
2361 depends on CMDLINE_BOOL
2363 Set this option to 'Y' to have the kernel ignore the boot loader
2364 command line, and use ONLY the built-in command line.
2366 This is used to work around broken boot loaders. This should
2367 be set to 'N' under normal conditions.
2369 config MODIFY_LDT_SYSCALL
2370 bool "Enable the LDT (local descriptor table)" if EXPERT
2373 Linux can allow user programs to install a per-process x86
2374 Local Descriptor Table (LDT) using the modify_ldt(2) system
2375 call. This is required to run 16-bit or segmented code such as
2376 DOSEMU or some Wine programs. It is also used by some very old
2377 threading libraries.
2379 Enabling this feature adds a small amount of overhead to
2380 context switches and increases the low-level kernel attack
2381 surface. Disabling it removes the modify_ldt(2) system call.
2383 Saying 'N' here may make sense for embedded or server kernels.
2385 source "kernel/livepatch/Kconfig"
2389 config ARCH_HAS_ADD_PAGES
2391 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2393 config ARCH_ENABLE_MEMORY_HOTPLUG
2395 depends on X86_64 || (X86_32 && HIGHMEM)
2397 config ARCH_ENABLE_MEMORY_HOTREMOVE
2399 depends on MEMORY_HOTPLUG
2401 config USE_PERCPU_NUMA_NODE_ID
2405 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2407 depends on X86_64 || X86_PAE
2409 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2411 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2413 config ARCH_ENABLE_THP_MIGRATION
2415 depends on X86_64 && TRANSPARENT_HUGEPAGE
2417 menu "Power management and ACPI options"
2419 config ARCH_HIBERNATION_HEADER
2421 depends on X86_64 && HIBERNATION
2423 source "kernel/power/Kconfig"
2425 source "drivers/acpi/Kconfig"
2427 source "drivers/sfi/Kconfig"
2434 tristate "APM (Advanced Power Management) BIOS support"
2435 depends on X86_32 && PM_SLEEP
2437 APM is a BIOS specification for saving power using several different
2438 techniques. This is mostly useful for battery powered laptops with
2439 APM compliant BIOSes. If you say Y here, the system time will be
2440 reset after a RESUME operation, the /proc/apm device will provide
2441 battery status information, and user-space programs will receive
2442 notification of APM "events" (e.g. battery status change).
2444 If you select "Y" here, you can disable actual use of the APM
2445 BIOS by passing the "apm=off" option to the kernel at boot time.
2447 Note that the APM support is almost completely disabled for
2448 machines with more than one CPU.
2450 In order to use APM, you will need supporting software. For location
2451 and more information, read <file:Documentation/power/apm-acpi.txt>
2452 and the Battery Powered Linux mini-HOWTO, available from
2453 <http://www.tldp.org/docs.html#howto>.
2455 This driver does not spin down disk drives (see the hdparm(8)
2456 manpage ("man 8 hdparm") for that), and it doesn't turn off
2457 VESA-compliant "green" monitors.
2459 This driver does not support the TI 4000M TravelMate and the ACER
2460 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2461 desktop machines also don't have compliant BIOSes, and this driver
2462 may cause those machines to panic during the boot phase.
2464 Generally, if you don't have a battery in your machine, there isn't
2465 much point in using this driver and you should say N. If you get
2466 random kernel OOPSes or reboots that don't seem to be related to
2467 anything, try disabling/enabling this option (or disabling/enabling
2470 Some other things you should try when experiencing seemingly random,
2473 1) make sure that you have enough swap space and that it is
2475 2) pass the "no-hlt" option to the kernel
2476 3) switch on floating point emulation in the kernel and pass
2477 the "no387" option to the kernel
2478 4) pass the "floppy=nodma" option to the kernel
2479 5) pass the "mem=4M" option to the kernel (thereby disabling
2480 all but the first 4 MB of RAM)
2481 6) make sure that the CPU is not over clocked.
2482 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2483 8) disable the cache from your BIOS settings
2484 9) install a fan for the video card or exchange video RAM
2485 10) install a better fan for the CPU
2486 11) exchange RAM chips
2487 12) exchange the motherboard.
2489 To compile this driver as a module, choose M here: the
2490 module will be called apm.
2494 config APM_IGNORE_USER_SUSPEND
2495 bool "Ignore USER SUSPEND"
2497 This option will ignore USER SUSPEND requests. On machines with a
2498 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2499 series notebooks, it is necessary to say Y because of a BIOS bug.
2501 config APM_DO_ENABLE
2502 bool "Enable PM at boot time"
2504 Enable APM features at boot time. From page 36 of the APM BIOS
2505 specification: "When disabled, the APM BIOS does not automatically
2506 power manage devices, enter the Standby State, enter the Suspend
2507 State, or take power saving steps in response to CPU Idle calls."
2508 This driver will make CPU Idle calls when Linux is idle (unless this
2509 feature is turned off -- see "Do CPU IDLE calls", below). This
2510 should always save battery power, but more complicated APM features
2511 will be dependent on your BIOS implementation. You may need to turn
2512 this option off if your computer hangs at boot time when using APM
2513 support, or if it beeps continuously instead of suspending. Turn
2514 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2515 T400CDT. This is off by default since most machines do fine without
2520 bool "Make CPU Idle calls when idle"
2522 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2523 On some machines, this can activate improved power savings, such as
2524 a slowed CPU clock rate, when the machine is idle. These idle calls
2525 are made after the idle loop has run for some length of time (e.g.,
2526 333 mS). On some machines, this will cause a hang at boot time or
2527 whenever the CPU becomes idle. (On machines with more than one CPU,
2528 this option does nothing.)
2530 config APM_DISPLAY_BLANK
2531 bool "Enable console blanking using APM"
2533 Enable console blanking using the APM. Some laptops can use this to
2534 turn off the LCD backlight when the screen blanker of the Linux
2535 virtual console blanks the screen. Note that this is only used by
2536 the virtual console screen blanker, and won't turn off the backlight
2537 when using the X Window system. This also doesn't have anything to
2538 do with your VESA-compliant power-saving monitor. Further, this
2539 option doesn't work for all laptops -- it might not turn off your
2540 backlight at all, or it might print a lot of errors to the console,
2541 especially if you are using gpm.
2543 config APM_ALLOW_INTS
2544 bool "Allow interrupts during APM BIOS calls"
2546 Normally we disable external interrupts while we are making calls to
2547 the APM BIOS as a measure to lessen the effects of a badly behaving
2548 BIOS implementation. The BIOS should reenable interrupts if it
2549 needs to. Unfortunately, some BIOSes do not -- especially those in
2550 many of the newer IBM Thinkpads. If you experience hangs when you
2551 suspend, try setting this to Y. Otherwise, say N.
2555 source "drivers/cpufreq/Kconfig"
2557 source "drivers/cpuidle/Kconfig"
2559 source "drivers/idle/Kconfig"
2564 menu "Bus options (PCI etc.)"
2570 Find out whether you have a PCI motherboard. PCI is the name of a
2571 bus system, i.e. the way the CPU talks to the other stuff inside
2572 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2573 VESA. If you have PCI, say Y, otherwise N.
2576 prompt "PCI access mode"
2577 depends on X86_32 && PCI
2580 On PCI systems, the BIOS can be used to detect the PCI devices and
2581 determine their configuration. However, some old PCI motherboards
2582 have BIOS bugs and may crash if this is done. Also, some embedded
2583 PCI-based systems don't have any BIOS at all. Linux can also try to
2584 detect the PCI hardware directly without using the BIOS.
2586 With this option, you can specify how Linux should detect the
2587 PCI devices. If you choose "BIOS", the BIOS will be used,
2588 if you choose "Direct", the BIOS won't be used, and if you
2589 choose "MMConfig", then PCI Express MMCONFIG will be used.
2590 If you choose "Any", the kernel will try MMCONFIG, then the
2591 direct access method and falls back to the BIOS if that doesn't
2592 work. If unsure, go with the default, which is "Any".
2597 config PCI_GOMMCONFIG
2614 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2616 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2619 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2622 bool "Support mmconfig PCI config space access" if X86_64
2624 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2625 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2629 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2633 depends on PCI && XEN
2640 config MMCONF_FAM10H
2642 depends on X86_64 && PCI_MMCONFIG && ACPI
2644 config PCI_CNB20LE_QUIRK
2645 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2648 Read the PCI windows out of the CNB20LE host bridge. This allows
2649 PCI hotplug to work on systems with the CNB20LE chipset which do
2652 There's no public spec for this chipset, and this functionality
2653 is known to be incomplete.
2655 You should say N unless you know you need this.
2657 source "drivers/pci/Kconfig"
2660 bool "ISA bus support on modern systems" if EXPERT
2662 Expose ISA bus device drivers and options available for selection and
2663 configuration. Enable this option if your target machine has an ISA
2664 bus. ISA is an older system, displaced by PCI and newer bus
2665 architectures -- if your target machine is modern, it probably does
2666 not have an ISA bus.
2670 # x86_64 have no ISA slots, but can have ISA-style DMA.
2672 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2675 Enables ISA-style DMA support for devices requiring such controllers.
2683 Find out whether you have ISA slots on your motherboard. ISA is the
2684 name of a bus system, i.e. the way the CPU talks to the other stuff
2685 inside your box. Other bus systems are PCI, EISA, MicroChannel
2686 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2687 newer boards don't support it. If you have ISA, say Y, otherwise N.
2693 The Extended Industry Standard Architecture (EISA) bus was
2694 developed as an open alternative to the IBM MicroChannel bus.
2696 The EISA bus provided some of the features of the IBM MicroChannel
2697 bus while maintaining backward compatibility with cards made for
2698 the older ISA bus. The EISA bus saw limited use between 1988 and
2699 1995 when it was made obsolete by the PCI bus.
2701 Say Y here if you are building a kernel for an EISA-based machine.
2705 source "drivers/eisa/Kconfig"
2708 tristate "NatSemi SCx200 support"
2710 This provides basic support for National Semiconductor's
2711 (now AMD's) Geode processors. The driver probes for the
2712 PCI-IDs of several on-chip devices, so its a good dependency
2713 for other scx200_* drivers.
2715 If compiled as a module, the driver is named scx200.
2717 config SCx200HR_TIMER
2718 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2722 This driver provides a clocksource built upon the on-chip
2723 27MHz high-resolution timer. Its also a workaround for
2724 NSC Geode SC-1100's buggy TSC, which loses time when the
2725 processor goes idle (as is done by the scheduler). The
2726 other workaround is idle=poll boot option.
2729 bool "One Laptop Per Child support"
2736 Add support for detecting the unique features of the OLPC
2740 bool "OLPC XO-1 Power Management"
2741 depends on OLPC && MFD_CS5535 && PM_SLEEP
2744 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2747 bool "OLPC XO-1 Real Time Clock"
2748 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2750 Add support for the XO-1 real time clock, which can be used as a
2751 programmable wakeup source.
2754 bool "OLPC XO-1 SCI extras"
2755 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2759 Add support for SCI-based features of the OLPC XO-1 laptop:
2760 - EC-driven system wakeups
2764 - AC adapter status updates
2765 - Battery status updates
2767 config OLPC_XO15_SCI
2768 bool "OLPC XO-1.5 SCI extras"
2769 depends on OLPC && ACPI
2772 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2773 - EC-driven system wakeups
2774 - AC adapter status updates
2775 - Battery status updates
2778 bool "PCEngines ALIX System Support (LED setup)"
2781 This option enables system support for the PCEngines ALIX.
2782 At present this just sets up LEDs for GPIO control on
2783 ALIX2/3/6 boards. However, other system specific setup should
2786 Note: You must still enable the drivers for GPIO and LED support
2787 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2789 Note: You have to set alix.force=1 for boards with Award BIOS.
2792 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2795 This option enables system support for the Soekris Engineering net5501.
2798 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2802 This option enables system support for the Traverse Technologies GEOS.
2805 bool "Technologic Systems TS-5500 platform support"
2807 select CHECK_SIGNATURE
2811 This option enables system support for the Technologic Systems TS-5500.
2817 depends on CPU_SUP_AMD && PCI
2819 source "drivers/pcmcia/Kconfig"
2822 tristate "RapidIO support"
2826 If enabled this option will include drivers and the core
2827 infrastructure code to support RapidIO interconnect devices.
2829 source "drivers/rapidio/Kconfig"
2832 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2834 Firmwares often provide initial graphics framebuffers so the BIOS,
2835 bootloader or kernel can show basic video-output during boot for
2836 user-guidance and debugging. Historically, x86 used the VESA BIOS
2837 Extensions and EFI-framebuffers for this, which are mostly limited
2839 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2840 framebuffers so the new generic system-framebuffer drivers can be
2841 used on x86. If the framebuffer is not compatible with the generic
2842 modes, it is advertised as fallback platform framebuffer so legacy
2843 drivers like efifb, vesafb and uvesafb can pick it up.
2844 If this option is not selected, all system framebuffers are always
2845 marked as fallback platform framebuffers as usual.
2847 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2848 not be able to pick up generic system framebuffers if this option
2849 is selected. You are highly encouraged to enable simplefb as
2850 replacement if you select this option. simplefb can correctly deal
2851 with generic system framebuffers. But you should still keep vesafb
2852 and others enabled as fallback if a system framebuffer is
2853 incompatible with simplefb.
2860 menu "Binary Emulations"
2862 config IA32_EMULATION
2863 bool "IA32 Emulation"
2865 select ARCH_WANT_OLD_COMPAT_IPC
2867 select COMPAT_BINFMT_ELF
2868 select COMPAT_OLD_SIGACTION
2870 Include code to run legacy 32-bit programs under a
2871 64-bit kernel. You should likely turn this on, unless you're
2872 100% sure that you don't have any 32-bit programs left.
2875 tristate "IA32 a.out support"
2876 depends on IA32_EMULATION
2878 Support old a.out binaries in the 32bit emulation.
2881 bool "x32 ABI for 64-bit mode"
2884 Include code to run binaries for the x32 native 32-bit ABI
2885 for 64-bit processors. An x32 process gets access to the
2886 full 64-bit register file and wide data path while leaving
2887 pointers at 32 bits for smaller memory footprint.
2889 You will need a recent binutils (2.22 or later) with
2890 elf32_x86_64 support enabled to compile a kernel with this
2895 depends on IA32_EMULATION || X86_32
2897 select OLD_SIGSUSPEND3
2901 depends on IA32_EMULATION || X86_X32
2904 config COMPAT_FOR_U64_ALIGNMENT
2907 config SYSVIPC_COMPAT
2915 config HAVE_ATOMIC_IOMAP
2919 config X86_DEV_DMA_OPS
2921 depends on X86_64 || STA2X11
2923 config X86_DMA_REMAP
2927 config HAVE_GENERIC_GUP
2930 source "drivers/firmware/Kconfig"
2932 source "arch/x86/kvm/Kconfig"