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 KEXEC_CORE
537 depends on X86_X2APIC
540 This option is needed in order to support SGI Ultraviolet systems.
541 If you don't have one of these, you should say N here.
543 # Following is an alphabetically sorted list of 32 bit extended platforms
544 # Please maintain the alphabetic order if and when there are additions
547 bool "Goldfish (Virtual Platform)"
548 depends on X86_EXTENDED_PLATFORM
550 Enable support for the Goldfish virtual platform used primarily
551 for Android development. Unless you are building for the Android
552 Goldfish emulator say N here.
555 bool "CE4100 TV platform"
557 depends on PCI_GODIRECT
558 depends on X86_IO_APIC
560 depends on X86_EXTENDED_PLATFORM
561 select X86_REBOOTFIXUPS
563 select OF_EARLY_FLATTREE
565 Select for the Intel CE media processor (CE4100) SOC.
566 This option compiles in support for the CE4100 SOC for settop
567 boxes and media devices.
570 bool "Intel MID platform support"
571 depends on X86_EXTENDED_PLATFORM
572 depends on X86_PLATFORM_DEVICES
574 depends on X86_64 || (PCI_GOANY && X86_32)
575 depends on X86_IO_APIC
581 select MFD_INTEL_MSIC
583 Select to build a kernel capable of supporting Intel MID (Mobile
584 Internet Device) platform systems which do not have the PCI legacy
585 interfaces. If you are building for a PC class system say N here.
587 Intel MID platforms are based on an Intel processor and chipset which
588 consume less power than most of the x86 derivatives.
590 config X86_INTEL_QUARK
591 bool "Intel Quark platform support"
593 depends on X86_EXTENDED_PLATFORM
594 depends on X86_PLATFORM_DEVICES
598 depends on X86_IO_APIC
603 Select to include support for Quark X1000 SoC.
604 Say Y here if you have a Quark based system such as the Arduino
605 compatible Intel Galileo.
607 config X86_INTEL_LPSS
608 bool "Intel Low Power Subsystem Support"
609 depends on X86 && ACPI
614 Select to build support for Intel Low Power Subsystem such as
615 found on Intel Lynxpoint PCH. Selecting this option enables
616 things like clock tree (common clock framework) and pincontrol
617 which are needed by the LPSS peripheral drivers.
619 config X86_AMD_PLATFORM_DEVICE
620 bool "AMD ACPI2Platform devices support"
625 Select to interpret AMD specific ACPI device to platform device
626 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
627 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
628 implemented under PINCTRL subsystem.
631 tristate "Intel SoC IOSF Sideband support for SoC platforms"
634 This option enables sideband register access support for Intel SoC
635 platforms. On these platforms the IOSF sideband is used in lieu of
636 MSR's for some register accesses, mostly but not limited to thermal
637 and power. Drivers may query the availability of this device to
638 determine if they need the sideband in order to work on these
639 platforms. The sideband is available on the following SoC products.
640 This list is not meant to be exclusive.
645 You should say Y if you are running a kernel on one of these SoC's.
647 config IOSF_MBI_DEBUG
648 bool "Enable IOSF sideband access through debugfs"
649 depends on IOSF_MBI && DEBUG_FS
651 Select this option to expose the IOSF sideband access registers (MCR,
652 MDR, MCRX) through debugfs to write and read register information from
653 different units on the SoC. This is most useful for obtaining device
654 state information for debug and analysis. As this is a general access
655 mechanism, users of this option would have specific knowledge of the
656 device they want to access.
658 If you don't require the option or are in doubt, say N.
661 bool "RDC R-321x SoC"
663 depends on X86_EXTENDED_PLATFORM
665 select X86_REBOOTFIXUPS
667 This option is needed for RDC R-321x system-on-chip, also known
669 If you don't have one of these chips, you should say N here.
671 config X86_32_NON_STANDARD
672 bool "Support non-standard 32-bit SMP architectures"
673 depends on X86_32 && SMP
674 depends on X86_EXTENDED_PLATFORM
676 This option compiles in the bigsmp and STA2X11 default
677 subarchitectures. It is intended for a generic binary
678 kernel. If you select them all, kernel will probe it one by
679 one and will fallback to default.
681 # Alphabetically sorted list of Non standard 32 bit platforms
683 config X86_SUPPORTS_MEMORY_FAILURE
685 # MCE code calls memory_failure():
687 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
688 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
689 depends on X86_64 || !SPARSEMEM
690 select ARCH_SUPPORTS_MEMORY_FAILURE
693 bool "STA2X11 Companion Chip Support"
694 depends on X86_32_NON_STANDARD && PCI
695 select ARCH_HAS_PHYS_TO_DMA
696 select X86_DEV_DMA_OPS
703 This adds support for boards based on the STA2X11 IO-Hub,
704 a.k.a. "ConneXt". The chip is used in place of the standard
705 PC chipset, so all "standard" peripherals are missing. If this
706 option is selected the kernel will still be able to boot on
707 standard PC machines.
710 tristate "Eurobraille/Iris poweroff module"
713 The Iris machines from EuroBraille do not have APM or ACPI support
714 to shut themselves down properly. A special I/O sequence is
715 needed to do so, which is what this module does at
718 This is only for Iris machines from EuroBraille.
722 config SCHED_OMIT_FRAME_POINTER
724 prompt "Single-depth WCHAN output"
727 Calculate simpler /proc/<PID>/wchan values. If this option
728 is disabled then wchan values will recurse back to the
729 caller function. This provides more accurate wchan values,
730 at the expense of slightly more scheduling overhead.
732 If in doubt, say "Y".
734 menuconfig HYPERVISOR_GUEST
735 bool "Linux guest support"
737 Say Y here to enable options for running Linux under various hyper-
738 visors. This option enables basic hypervisor detection and platform
741 If you say N, all options in this submenu will be skipped and
742 disabled, and Linux guest support won't be built in.
747 bool "Enable paravirtualization code"
749 This changes the kernel so it can modify itself when it is run
750 under a hypervisor, potentially improving performance significantly
751 over full virtualization. However, when run without a hypervisor
752 the kernel is theoretically slower and slightly larger.
754 config PARAVIRT_DEBUG
755 bool "paravirt-ops debugging"
756 depends on PARAVIRT && DEBUG_KERNEL
758 Enable to debug paravirt_ops internals. Specifically, BUG if
759 a paravirt_op is missing when it is called.
761 config PARAVIRT_SPINLOCKS
762 bool "Paravirtualization layer for spinlocks"
763 depends on PARAVIRT && SMP
765 Paravirtualized spinlocks allow a pvops backend to replace the
766 spinlock implementation with something virtualization-friendly
767 (for example, block the virtual CPU rather than spinning).
769 It has a minimal impact on native kernels and gives a nice performance
770 benefit on paravirtualized KVM / Xen kernels.
772 If you are unsure how to answer this question, answer Y.
774 config QUEUED_LOCK_STAT
775 bool "Paravirt queued spinlock statistics"
776 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
778 Enable the collection of statistical data on the slowpath
779 behavior of paravirtualized queued spinlocks and report
782 source "arch/x86/xen/Kconfig"
785 bool "KVM Guest support (including kvmclock)"
787 select PARAVIRT_CLOCK
790 This option enables various optimizations for running under the KVM
791 hypervisor. It includes a paravirtualized clock, so that instead
792 of relying on a PIT (or probably other) emulation by the
793 underlying device model, the host provides the guest with
794 timing infrastructure such as time of day, and system time
797 bool "Enable debug information for KVM Guests in debugfs"
798 depends on KVM_GUEST && DEBUG_FS
801 This option enables collection of various statistics for KVM guest.
802 Statistics are displayed in debugfs filesystem. Enabling this option
803 may incur significant overhead.
805 config PARAVIRT_TIME_ACCOUNTING
806 bool "Paravirtual steal time accounting"
810 Select this option to enable fine granularity task steal time
811 accounting. Time spent executing other tasks in parallel with
812 the current vCPU is discounted from the vCPU power. To account for
813 that, there can be a small performance impact.
815 If in doubt, say N here.
817 config PARAVIRT_CLOCK
820 config JAILHOUSE_GUEST
821 bool "Jailhouse non-root cell support"
822 depends on X86_64 && PCI
825 This option allows to run Linux as guest in a Jailhouse non-root
826 cell. You can leave this option disabled if you only want to start
827 Jailhouse and run Linux afterwards in the root cell.
829 endif #HYPERVISOR_GUEST
834 source "arch/x86/Kconfig.cpu"
838 prompt "HPET Timer Support" if X86_32
840 Use the IA-PC HPET (High Precision Event Timer) to manage
841 time in preference to the PIT and RTC, if a HPET is
843 HPET is the next generation timer replacing legacy 8254s.
844 The HPET provides a stable time base on SMP
845 systems, unlike the TSC, but it is more expensive to access,
846 as it is off-chip. The interface used is documented
847 in the HPET spec, revision 1.
849 You can safely choose Y here. However, HPET will only be
850 activated if the platform and the BIOS support this feature.
851 Otherwise the 8254 will be used for timing services.
853 Choose N to continue using the legacy 8254 timer.
855 config HPET_EMULATE_RTC
857 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
860 def_bool y if X86_INTEL_MID
861 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
863 depends on X86_INTEL_MID && SFI
865 APB timer is the replacement for 8254, HPET on X86 MID platforms.
866 The APBT provides a stable time base on SMP
867 systems, unlike the TSC, but it is more expensive to access,
868 as it is off-chip. APB timers are always running regardless of CPU
869 C states, they are used as per CPU clockevent device when possible.
871 # Mark as expert because too many people got it wrong.
872 # The code disables itself when not needed.
875 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
876 bool "Enable DMI scanning" if EXPERT
878 Enabled scanning of DMI to identify machine quirks. Say Y
879 here unless you have verified that your setup is not
880 affected by entries in the DMI blacklist. Required by PNP
884 bool "Old AMD GART IOMMU support"
887 depends on X86_64 && PCI && AMD_NB
889 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
890 GART based hardware IOMMUs.
892 The GART supports full DMA access for devices with 32-bit access
893 limitations, on systems with more than 3 GB. This is usually needed
894 for USB, sound, many IDE/SATA chipsets and some other devices.
896 Newer systems typically have a modern AMD IOMMU, supported via
897 the CONFIG_AMD_IOMMU=y config option.
899 In normal configurations this driver is only active when needed:
900 there's more than 3 GB of memory and the system contains a
901 32-bit limited device.
906 bool "IBM Calgary IOMMU support"
909 depends on X86_64 && PCI
911 Support for hardware IOMMUs in IBM's xSeries x366 and x460
912 systems. Needed to run systems with more than 3GB of memory
913 properly with 32-bit PCI devices that do not support DAC
914 (Double Address Cycle). Calgary also supports bus level
915 isolation, where all DMAs pass through the IOMMU. This
916 prevents them from going anywhere except their intended
917 destination. This catches hard-to-find kernel bugs and
918 mis-behaving drivers and devices that do not use the DMA-API
919 properly to set up their DMA buffers. The IOMMU can be
920 turned off at boot time with the iommu=off parameter.
921 Normally the kernel will make the right choice by itself.
924 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
926 prompt "Should Calgary be enabled by default?"
927 depends on CALGARY_IOMMU
929 Should Calgary be enabled by default? if you choose 'y', Calgary
930 will be used (if it exists). If you choose 'n', Calgary will not be
931 used even if it exists. If you choose 'n' and would like to use
932 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
936 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
937 depends on X86_64 && SMP && DEBUG_KERNEL
938 select CPUMASK_OFFSTACK
940 Enable maximum number of CPUS and NUMA Nodes for this architecture.
944 # The maximum number of CPUs supported:
946 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
947 # and which can be configured interactively in the
948 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
950 # The ranges are different on 32-bit and 64-bit kernels, depending on
951 # hardware capabilities and scalability features of the kernel.
953 # ( If MAXSMP is enabled we just use the highest possible value and disable
954 # interactive configuration. )
957 config NR_CPUS_RANGE_BEGIN
959 default NR_CPUS_RANGE_END if MAXSMP
963 config NR_CPUS_RANGE_END
966 default 64 if SMP && X86_BIGSMP
967 default 8 if SMP && !X86_BIGSMP
970 config NR_CPUS_RANGE_END
973 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
974 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
977 config NR_CPUS_DEFAULT
980 default 32 if X86_BIGSMP
984 config NR_CPUS_DEFAULT
987 default 8192 if MAXSMP
992 int "Maximum number of CPUs" if SMP && !MAXSMP
993 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
994 default NR_CPUS_DEFAULT
996 This allows you to specify the maximum number of CPUs which this
997 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
998 supported value is 8192, otherwise the maximum value is 512. The
999 minimum value which makes sense is 2.
1001 This is purely to save memory: each supported CPU adds about 8KB
1002 to the kernel image.
1009 prompt "Multi-core scheduler support"
1012 Multi-core scheduler support improves the CPU scheduler's decision
1013 making when dealing with multi-core CPU chips at a cost of slightly
1014 increased overhead in some places. If unsure say N here.
1016 config SCHED_MC_PRIO
1017 bool "CPU core priorities scheduler support"
1018 depends on SCHED_MC && CPU_SUP_INTEL
1019 select X86_INTEL_PSTATE
1023 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1024 core ordering determined at manufacturing time, which allows
1025 certain cores to reach higher turbo frequencies (when running
1026 single threaded workloads) than others.
1028 Enabling this kernel feature teaches the scheduler about
1029 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1030 scheduler's CPU selection logic accordingly, so that higher
1031 overall system performance can be achieved.
1033 This feature will have no effect on CPUs without this feature.
1035 If unsure say Y here.
1039 depends on !SMP && X86_LOCAL_APIC
1042 bool "Local APIC support on uniprocessors" if !PCI_MSI
1044 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1046 A local APIC (Advanced Programmable Interrupt Controller) is an
1047 integrated interrupt controller in the CPU. If you have a single-CPU
1048 system which has a processor with a local APIC, you can say Y here to
1049 enable and use it. If you say Y here even though your machine doesn't
1050 have a local APIC, then the kernel will still run with no slowdown at
1051 all. The local APIC supports CPU-generated self-interrupts (timer,
1052 performance counters), and the NMI watchdog which detects hard
1055 config X86_UP_IOAPIC
1056 bool "IO-APIC support on uniprocessors"
1057 depends on X86_UP_APIC
1059 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1060 SMP-capable replacement for PC-style interrupt controllers. Most
1061 SMP systems and many recent uniprocessor systems have one.
1063 If you have a single-CPU system with an IO-APIC, you can say Y here
1064 to use it. If you say Y here even though your machine doesn't have
1065 an IO-APIC, then the kernel will still run with no slowdown at all.
1067 config X86_LOCAL_APIC
1069 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1070 select IRQ_DOMAIN_HIERARCHY
1071 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1075 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1077 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1078 bool "Reroute for broken boot IRQs"
1079 depends on X86_IO_APIC
1081 This option enables a workaround that fixes a source of
1082 spurious interrupts. This is recommended when threaded
1083 interrupt handling is used on systems where the generation of
1084 superfluous "boot interrupts" cannot be disabled.
1086 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1087 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1088 kernel does during interrupt handling). On chipsets where this
1089 boot IRQ generation cannot be disabled, this workaround keeps
1090 the original IRQ line masked so that only the equivalent "boot
1091 IRQ" is delivered to the CPUs. The workaround also tells the
1092 kernel to set up the IRQ handler on the boot IRQ line. In this
1093 way only one interrupt is delivered to the kernel. Otherwise
1094 the spurious second interrupt may cause the kernel to bring
1095 down (vital) interrupt lines.
1097 Only affects "broken" chipsets. Interrupt sharing may be
1098 increased on these systems.
1101 bool "Machine Check / overheating reporting"
1102 select GENERIC_ALLOCATOR
1105 Machine Check support allows the processor to notify the
1106 kernel if it detects a problem (e.g. overheating, data corruption).
1107 The action the kernel takes depends on the severity of the problem,
1108 ranging from warning messages to halting the machine.
1110 config X86_MCELOG_LEGACY
1111 bool "Support for deprecated /dev/mcelog character device"
1114 Enable support for /dev/mcelog which is needed by the old mcelog
1115 userspace logging daemon. Consider switching to the new generation
1118 config X86_MCE_INTEL
1120 prompt "Intel MCE features"
1121 depends on X86_MCE && X86_LOCAL_APIC
1123 Additional support for intel specific MCE features such as
1124 the thermal monitor.
1128 prompt "AMD MCE features"
1129 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1131 Additional support for AMD specific MCE features such as
1132 the DRAM Error Threshold.
1134 config X86_ANCIENT_MCE
1135 bool "Support for old Pentium 5 / WinChip machine checks"
1136 depends on X86_32 && X86_MCE
1138 Include support for machine check handling on old Pentium 5 or WinChip
1139 systems. These typically need to be enabled explicitly on the command
1142 config X86_MCE_THRESHOLD
1143 depends on X86_MCE_AMD || X86_MCE_INTEL
1146 config X86_MCE_INJECT
1147 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1148 tristate "Machine check injector support"
1150 Provide support for injecting machine checks for testing purposes.
1151 If you don't know what a machine check is and you don't do kernel
1152 QA it is safe to say n.
1154 config X86_THERMAL_VECTOR
1156 depends on X86_MCE_INTEL
1158 source "arch/x86/events/Kconfig"
1160 config X86_LEGACY_VM86
1161 bool "Legacy VM86 support"
1165 This option allows user programs to put the CPU into V8086
1166 mode, which is an 80286-era approximation of 16-bit real mode.
1168 Some very old versions of X and/or vbetool require this option
1169 for user mode setting. Similarly, DOSEMU will use it if
1170 available to accelerate real mode DOS programs. However, any
1171 recent version of DOSEMU, X, or vbetool should be fully
1172 functional even without kernel VM86 support, as they will all
1173 fall back to software emulation. Nevertheless, if you are using
1174 a 16-bit DOS program where 16-bit performance matters, vm86
1175 mode might be faster than emulation and you might want to
1178 Note that any app that works on a 64-bit kernel is unlikely to
1179 need this option, as 64-bit kernels don't, and can't, support
1180 V8086 mode. This option is also unrelated to 16-bit protected
1181 mode and is not needed to run most 16-bit programs under Wine.
1183 Enabling this option increases the complexity of the kernel
1184 and slows down exception handling a tiny bit.
1186 If unsure, say N here.
1190 default X86_LEGACY_VM86
1193 bool "Enable support for 16-bit segments" if EXPERT
1195 depends on MODIFY_LDT_SYSCALL
1197 This option is required by programs like Wine to run 16-bit
1198 protected mode legacy code on x86 processors. Disabling
1199 this option saves about 300 bytes on i386, or around 6K text
1200 plus 16K runtime memory on x86-64,
1204 depends on X86_16BIT && X86_32
1208 depends on X86_16BIT && X86_64
1210 config X86_VSYSCALL_EMULATION
1211 bool "Enable vsyscall emulation" if EXPERT
1215 This enables emulation of the legacy vsyscall page. Disabling
1216 it is roughly equivalent to booting with vsyscall=none, except
1217 that it will also disable the helpful warning if a program
1218 tries to use a vsyscall. With this option set to N, offending
1219 programs will just segfault, citing addresses of the form
1222 This option is required by many programs built before 2013, and
1223 care should be used even with newer programs if set to N.
1225 Disabling this option saves about 7K of kernel size and
1226 possibly 4K of additional runtime pagetable memory.
1229 tristate "Toshiba Laptop support"
1232 This adds a driver to safely access the System Management Mode of
1233 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1234 not work on models with a Phoenix BIOS. The System Management Mode
1235 is used to set the BIOS and power saving options on Toshiba portables.
1237 For information on utilities to make use of this driver see the
1238 Toshiba Linux utilities web site at:
1239 <http://www.buzzard.org.uk/toshiba/>.
1241 Say Y if you intend to run this kernel on a Toshiba portable.
1245 tristate "Dell i8k legacy laptop support"
1247 select SENSORS_DELL_SMM
1249 This option enables legacy /proc/i8k userspace interface in hwmon
1250 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1251 temperature and allows controlling fan speeds of Dell laptops via
1252 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1253 it reports also power and hotkey status. For fan speed control is
1254 needed userspace package i8kutils.
1256 Say Y if you intend to run this kernel on old Dell laptops or want to
1257 use userspace package i8kutils.
1260 config X86_REBOOTFIXUPS
1261 bool "Enable X86 board specific fixups for reboot"
1264 This enables chipset and/or board specific fixups to be done
1265 in order to get reboot to work correctly. This is only needed on
1266 some combinations of hardware and BIOS. The symptom, for which
1267 this config is intended, is when reboot ends with a stalled/hung
1270 Currently, the only fixup is for the Geode machines using
1271 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1273 Say Y if you want to enable the fixup. Currently, it's safe to
1274 enable this option even if you don't need it.
1278 bool "CPU microcode loading support"
1280 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1283 If you say Y here, you will be able to update the microcode on
1284 Intel and AMD processors. The Intel support is for the IA32 family,
1285 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1286 AMD support is for families 0x10 and later. You will obviously need
1287 the actual microcode binary data itself which is not shipped with
1290 The preferred method to load microcode from a detached initrd is described
1291 in Documentation/x86/microcode.txt. For that you need to enable
1292 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1293 initrd for microcode blobs.
1295 In addition, you can build the microcode into the kernel. For that you
1296 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1299 config MICROCODE_INTEL
1300 bool "Intel microcode loading support"
1301 depends on MICROCODE
1305 This options enables microcode patch loading support for Intel
1308 For the current Intel microcode data package go to
1309 <https://downloadcenter.intel.com> and search for
1310 'Linux Processor Microcode Data File'.
1312 config MICROCODE_AMD
1313 bool "AMD microcode loading support"
1314 depends on MICROCODE
1317 If you select this option, microcode patch loading support for AMD
1318 processors will be enabled.
1320 config MICROCODE_OLD_INTERFACE
1322 depends on MICROCODE
1325 tristate "/dev/cpu/*/msr - Model-specific register support"
1327 This device gives privileged processes access to the x86
1328 Model-Specific Registers (MSRs). It is a character device with
1329 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1330 MSR accesses are directed to a specific CPU on multi-processor
1334 tristate "/dev/cpu/*/cpuid - CPU information support"
1336 This device gives processes access to the x86 CPUID instruction to
1337 be executed on a specific processor. It is a character device
1338 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1342 prompt "High Memory Support"
1349 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1350 However, the address space of 32-bit x86 processors is only 4
1351 Gigabytes large. That means that, if you have a large amount of
1352 physical memory, not all of it can be "permanently mapped" by the
1353 kernel. The physical memory that's not permanently mapped is called
1356 If you are compiling a kernel which will never run on a machine with
1357 more than 1 Gigabyte total physical RAM, answer "off" here (default
1358 choice and suitable for most users). This will result in a "3GB/1GB"
1359 split: 3GB are mapped so that each process sees a 3GB virtual memory
1360 space and the remaining part of the 4GB virtual memory space is used
1361 by the kernel to permanently map as much physical memory as
1364 If the machine has between 1 and 4 Gigabytes physical RAM, then
1367 If more than 4 Gigabytes is used then answer "64GB" here. This
1368 selection turns Intel PAE (Physical Address Extension) mode on.
1369 PAE implements 3-level paging on IA32 processors. PAE is fully
1370 supported by Linux, PAE mode is implemented on all recent Intel
1371 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1372 then the kernel will not boot on CPUs that don't support PAE!
1374 The actual amount of total physical memory will either be
1375 auto detected or can be forced by using a kernel command line option
1376 such as "mem=256M". (Try "man bootparam" or see the documentation of
1377 your boot loader (lilo or loadlin) about how to pass options to the
1378 kernel at boot time.)
1380 If unsure, say "off".
1385 Select this if you have a 32-bit processor and between 1 and 4
1386 gigabytes of physical RAM.
1390 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1393 Select this if you have a 32-bit processor and more than 4
1394 gigabytes of physical RAM.
1399 prompt "Memory split" if EXPERT
1403 Select the desired split between kernel and user memory.
1405 If the address range available to the kernel is less than the
1406 physical memory installed, the remaining memory will be available
1407 as "high memory". Accessing high memory is a little more costly
1408 than low memory, as it needs to be mapped into the kernel first.
1409 Note that increasing the kernel address space limits the range
1410 available to user programs, making the address space there
1411 tighter. Selecting anything other than the default 3G/1G split
1412 will also likely make your kernel incompatible with binary-only
1415 If you are not absolutely sure what you are doing, leave this
1419 bool "3G/1G user/kernel split"
1420 config VMSPLIT_3G_OPT
1422 bool "3G/1G user/kernel split (for full 1G low memory)"
1424 bool "2G/2G user/kernel split"
1425 config VMSPLIT_2G_OPT
1427 bool "2G/2G user/kernel split (for full 2G low memory)"
1429 bool "1G/3G user/kernel split"
1434 default 0xB0000000 if VMSPLIT_3G_OPT
1435 default 0x80000000 if VMSPLIT_2G
1436 default 0x78000000 if VMSPLIT_2G_OPT
1437 default 0x40000000 if VMSPLIT_1G
1443 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1446 bool "PAE (Physical Address Extension) Support"
1447 depends on X86_32 && !HIGHMEM4G
1448 select PHYS_ADDR_T_64BIT
1451 PAE is required for NX support, and furthermore enables
1452 larger swapspace support for non-overcommit purposes. It
1453 has the cost of more pagetable lookup overhead, and also
1454 consumes more pagetable space per process.
1457 bool "Enable 5-level page tables support"
1458 select DYNAMIC_MEMORY_LAYOUT
1459 select SPARSEMEM_VMEMMAP
1462 5-level paging enables access to larger address space:
1463 upto 128 PiB of virtual address space and 4 PiB of
1464 physical address space.
1466 It will be supported by future Intel CPUs.
1468 A kernel with the option enabled can be booted on machines that
1469 support 4- or 5-level paging.
1471 See Documentation/x86/x86_64/5level-paging.txt for more
1476 config X86_DIRECT_GBPAGES
1478 depends on X86_64 && !DEBUG_PAGEALLOC
1480 Certain kernel features effectively disable kernel
1481 linear 1 GB mappings (even if the CPU otherwise
1482 supports them), so don't confuse the user by printing
1483 that we have them enabled.
1485 config ARCH_HAS_MEM_ENCRYPT
1488 config AMD_MEM_ENCRYPT
1489 bool "AMD Secure Memory Encryption (SME) support"
1490 depends on X86_64 && CPU_SUP_AMD
1491 select DYNAMIC_PHYSICAL_MASK
1493 Say yes to enable support for the encryption of system memory.
1494 This requires an AMD processor that supports Secure Memory
1497 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1498 bool "Activate AMD Secure Memory Encryption (SME) by default"
1500 depends on AMD_MEM_ENCRYPT
1502 Say yes to have system memory encrypted by default if running on
1503 an AMD processor that supports Secure Memory Encryption (SME).
1505 If set to Y, then the encryption of system memory can be
1506 deactivated with the mem_encrypt=off command line option.
1508 If set to N, then the encryption of system memory can be
1509 activated with the mem_encrypt=on command line option.
1511 config ARCH_USE_MEMREMAP_PROT
1513 depends on AMD_MEM_ENCRYPT
1515 # Common NUMA Features
1517 bool "Numa Memory Allocation and Scheduler Support"
1519 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1520 default y if X86_BIGSMP
1522 Enable NUMA (Non Uniform Memory Access) support.
1524 The kernel will try to allocate memory used by a CPU on the
1525 local memory controller of the CPU and add some more
1526 NUMA awareness to the kernel.
1528 For 64-bit this is recommended if the system is Intel Core i7
1529 (or later), AMD Opteron, or EM64T NUMA.
1531 For 32-bit this is only needed if you boot a 32-bit
1532 kernel on a 64-bit NUMA platform.
1534 Otherwise, you should say N.
1538 prompt "Old style AMD Opteron NUMA detection"
1539 depends on X86_64 && NUMA && PCI
1541 Enable AMD NUMA node topology detection. You should say Y here if
1542 you have a multi processor AMD system. This uses an old method to
1543 read the NUMA configuration directly from the builtin Northbridge
1544 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1545 which also takes priority if both are compiled in.
1547 config X86_64_ACPI_NUMA
1549 prompt "ACPI NUMA detection"
1550 depends on X86_64 && NUMA && ACPI && PCI
1553 Enable ACPI SRAT based node topology detection.
1555 # Some NUMA nodes have memory ranges that span
1556 # other nodes. Even though a pfn is valid and
1557 # between a node's start and end pfns, it may not
1558 # reside on that node. See memmap_init_zone()
1560 config NODES_SPAN_OTHER_NODES
1562 depends on X86_64_ACPI_NUMA
1565 bool "NUMA emulation"
1568 Enable NUMA emulation. A flat machine will be split
1569 into virtual nodes when booted with "numa=fake=N", where N is the
1570 number of nodes. This is only useful for debugging.
1573 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1575 default "10" if MAXSMP
1576 default "6" if X86_64
1578 depends on NEED_MULTIPLE_NODES
1580 Specify the maximum number of NUMA Nodes available on the target
1581 system. Increases memory reserved to accommodate various tables.
1583 config ARCH_HAVE_MEMORY_PRESENT
1585 depends on X86_32 && DISCONTIGMEM
1587 config ARCH_FLATMEM_ENABLE
1589 depends on X86_32 && !NUMA
1591 config ARCH_DISCONTIGMEM_ENABLE
1593 depends on NUMA && X86_32
1595 config ARCH_DISCONTIGMEM_DEFAULT
1597 depends on NUMA && X86_32
1599 config ARCH_SPARSEMEM_ENABLE
1601 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1602 select SPARSEMEM_STATIC if X86_32
1603 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1605 config ARCH_SPARSEMEM_DEFAULT
1609 config ARCH_SELECT_MEMORY_MODEL
1611 depends on ARCH_SPARSEMEM_ENABLE
1613 config ARCH_MEMORY_PROBE
1614 bool "Enable sysfs memory/probe interface"
1615 depends on X86_64 && MEMORY_HOTPLUG
1617 This option enables a sysfs memory/probe interface for testing.
1618 See Documentation/memory-hotplug.txt for more information.
1619 If you are unsure how to answer this question, answer N.
1621 config ARCH_PROC_KCORE_TEXT
1623 depends on X86_64 && PROC_KCORE
1625 config ILLEGAL_POINTER_VALUE
1628 default 0xdead000000000000 if X86_64
1630 config X86_PMEM_LEGACY_DEVICE
1633 config X86_PMEM_LEGACY
1634 tristate "Support non-standard NVDIMMs and ADR protected memory"
1635 depends on PHYS_ADDR_T_64BIT
1637 select X86_PMEM_LEGACY_DEVICE
1640 Treat memory marked using the non-standard e820 type of 12 as used
1641 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1642 The kernel will offer these regions to the 'pmem' driver so
1643 they can be used for persistent storage.
1648 bool "Allocate 3rd-level pagetables from highmem"
1651 The VM uses one page table entry for each page of physical memory.
1652 For systems with a lot of RAM, this can be wasteful of precious
1653 low memory. Setting this option will put user-space page table
1654 entries in high memory.
1656 config X86_CHECK_BIOS_CORRUPTION
1657 bool "Check for low memory corruption"
1659 Periodically check for memory corruption in low memory, which
1660 is suspected to be caused by BIOS. Even when enabled in the
1661 configuration, it is disabled at runtime. Enable it by
1662 setting "memory_corruption_check=1" on the kernel command
1663 line. By default it scans the low 64k of memory every 60
1664 seconds; see the memory_corruption_check_size and
1665 memory_corruption_check_period parameters in
1666 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1668 When enabled with the default parameters, this option has
1669 almost no overhead, as it reserves a relatively small amount
1670 of memory and scans it infrequently. It both detects corruption
1671 and prevents it from affecting the running system.
1673 It is, however, intended as a diagnostic tool; if repeatable
1674 BIOS-originated corruption always affects the same memory,
1675 you can use memmap= to prevent the kernel from using that
1678 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1679 bool "Set the default setting of memory_corruption_check"
1680 depends on X86_CHECK_BIOS_CORRUPTION
1683 Set whether the default state of memory_corruption_check is
1686 config X86_RESERVE_LOW
1687 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1691 Specify the amount of low memory to reserve for the BIOS.
1693 The first page contains BIOS data structures that the kernel
1694 must not use, so that page must always be reserved.
1696 By default we reserve the first 64K of physical RAM, as a
1697 number of BIOSes are known to corrupt that memory range
1698 during events such as suspend/resume or monitor cable
1699 insertion, so it must not be used by the kernel.
1701 You can set this to 4 if you are absolutely sure that you
1702 trust the BIOS to get all its memory reservations and usages
1703 right. If you know your BIOS have problems beyond the
1704 default 64K area, you can set this to 640 to avoid using the
1705 entire low memory range.
1707 If you have doubts about the BIOS (e.g. suspend/resume does
1708 not work or there's kernel crashes after certain hardware
1709 hotplug events) then you might want to enable
1710 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1711 typical corruption patterns.
1713 Leave this to the default value of 64 if you are unsure.
1715 config MATH_EMULATION
1717 depends on MODIFY_LDT_SYSCALL
1718 prompt "Math emulation" if X86_32
1720 Linux can emulate a math coprocessor (used for floating point
1721 operations) if you don't have one. 486DX and Pentium processors have
1722 a math coprocessor built in, 486SX and 386 do not, unless you added
1723 a 487DX or 387, respectively. (The messages during boot time can
1724 give you some hints here ["man dmesg"].) Everyone needs either a
1725 coprocessor or this emulation.
1727 If you don't have a math coprocessor, you need to say Y here; if you
1728 say Y here even though you have a coprocessor, the coprocessor will
1729 be used nevertheless. (This behavior can be changed with the kernel
1730 command line option "no387", which comes handy if your coprocessor
1731 is broken. Try "man bootparam" or see the documentation of your boot
1732 loader (lilo or loadlin) about how to pass options to the kernel at
1733 boot time.) This means that it is a good idea to say Y here if you
1734 intend to use this kernel on different machines.
1736 More information about the internals of the Linux math coprocessor
1737 emulation can be found in <file:arch/x86/math-emu/README>.
1739 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1740 kernel, it won't hurt.
1744 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1746 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1747 the Memory Type Range Registers (MTRRs) may be used to control
1748 processor access to memory ranges. This is most useful if you have
1749 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1750 allows bus write transfers to be combined into a larger transfer
1751 before bursting over the PCI/AGP bus. This can increase performance
1752 of image write operations 2.5 times or more. Saying Y here creates a
1753 /proc/mtrr file which may be used to manipulate your processor's
1754 MTRRs. Typically the X server should use this.
1756 This code has a reasonably generic interface so that similar
1757 control registers on other processors can be easily supported
1760 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1761 Registers (ARRs) which provide a similar functionality to MTRRs. For
1762 these, the ARRs are used to emulate the MTRRs.
1763 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1764 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1765 write-combining. All of these processors are supported by this code
1766 and it makes sense to say Y here if you have one of them.
1768 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1769 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1770 can lead to all sorts of problems, so it's good to say Y here.
1772 You can safely say Y even if your machine doesn't have MTRRs, you'll
1773 just add about 9 KB to your kernel.
1775 See <file:Documentation/x86/mtrr.txt> for more information.
1777 config MTRR_SANITIZER
1779 prompt "MTRR cleanup support"
1782 Convert MTRR layout from continuous to discrete, so X drivers can
1783 add writeback entries.
1785 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1786 The largest mtrr entry size for a continuous block can be set with
1791 config MTRR_SANITIZER_ENABLE_DEFAULT
1792 int "MTRR cleanup enable value (0-1)"
1795 depends on MTRR_SANITIZER
1797 Enable mtrr cleanup default value
1799 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1800 int "MTRR cleanup spare reg num (0-7)"
1803 depends on MTRR_SANITIZER
1805 mtrr cleanup spare entries default, it can be changed via
1806 mtrr_spare_reg_nr=N on the kernel command line.
1810 prompt "x86 PAT support" if EXPERT
1813 Use PAT attributes to setup page level cache control.
1815 PATs are the modern equivalents of MTRRs and are much more
1816 flexible than MTRRs.
1818 Say N here if you see bootup problems (boot crash, boot hang,
1819 spontaneous reboots) or a non-working video driver.
1823 config ARCH_USES_PG_UNCACHED
1829 prompt "x86 architectural random number generator" if EXPERT
1831 Enable the x86 architectural RDRAND instruction
1832 (Intel Bull Mountain technology) to generate random numbers.
1833 If supported, this is a high bandwidth, cryptographically
1834 secure hardware random number generator.
1838 prompt "Supervisor Mode Access Prevention" if EXPERT
1840 Supervisor Mode Access Prevention (SMAP) is a security
1841 feature in newer Intel processors. There is a small
1842 performance cost if this enabled and turned on; there is
1843 also a small increase in the kernel size if this is enabled.
1847 config X86_INTEL_UMIP
1849 depends on CPU_SUP_INTEL
1850 prompt "Intel User Mode Instruction Prevention" if EXPERT
1852 The User Mode Instruction Prevention (UMIP) is a security
1853 feature in newer Intel processors. If enabled, a general
1854 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1855 or STR instructions are executed in user mode. These instructions
1856 unnecessarily expose information about the hardware state.
1858 The vast majority of applications do not use these instructions.
1859 For the very few that do, software emulation is provided in
1860 specific cases in protected and virtual-8086 modes. Emulated
1863 config X86_INTEL_MPX
1864 prompt "Intel MPX (Memory Protection Extensions)"
1866 # Note: only available in 64-bit mode due to VMA flags shortage
1867 depends on CPU_SUP_INTEL && X86_64
1868 select ARCH_USES_HIGH_VMA_FLAGS
1870 MPX provides hardware features that can be used in
1871 conjunction with compiler-instrumented code to check
1872 memory references. It is designed to detect buffer
1873 overflow or underflow bugs.
1875 This option enables running applications which are
1876 instrumented or otherwise use MPX. It does not use MPX
1877 itself inside the kernel or to protect the kernel
1878 against bad memory references.
1880 Enabling this option will make the kernel larger:
1881 ~8k of kernel text and 36 bytes of data on a 64-bit
1882 defconfig. It adds a long to the 'mm_struct' which
1883 will increase the kernel memory overhead of each
1884 process and adds some branches to paths used during
1885 exec() and munmap().
1887 For details, see Documentation/x86/intel_mpx.txt
1891 config X86_INTEL_MEMORY_PROTECTION_KEYS
1892 prompt "Intel Memory Protection Keys"
1894 # Note: only available in 64-bit mode
1895 depends on CPU_SUP_INTEL && X86_64
1896 select ARCH_USES_HIGH_VMA_FLAGS
1897 select ARCH_HAS_PKEYS
1899 Memory Protection Keys provides a mechanism for enforcing
1900 page-based protections, but without requiring modification of the
1901 page tables when an application changes protection domains.
1903 For details, see Documentation/x86/protection-keys.txt
1908 prompt "TSX enable mode"
1909 depends on CPU_SUP_INTEL
1910 default X86_INTEL_TSX_MODE_OFF
1912 Intel's TSX (Transactional Synchronization Extensions) feature
1913 allows to optimize locking protocols through lock elision which
1914 can lead to a noticeable performance boost.
1916 On the other hand it has been shown that TSX can be exploited
1917 to form side channel attacks (e.g. TAA) and chances are there
1918 will be more of those attacks discovered in the future.
1920 Therefore TSX is not enabled by default (aka tsx=off). An admin
1921 might override this decision by tsx=on the command line parameter.
1922 Even with TSX enabled, the kernel will attempt to enable the best
1923 possible TAA mitigation setting depending on the microcode available
1924 for the particular machine.
1926 This option allows to set the default tsx mode between tsx=on, =off
1927 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1930 Say off if not sure, auto if TSX is in use but it should be used on safe
1931 platforms or on if TSX is in use and the security aspect of tsx is not
1934 config X86_INTEL_TSX_MODE_OFF
1937 TSX is disabled if possible - equals to tsx=off command line parameter.
1939 config X86_INTEL_TSX_MODE_ON
1942 TSX is always enabled on TSX capable HW - equals the tsx=on command
1945 config X86_INTEL_TSX_MODE_AUTO
1948 TSX is enabled on TSX capable HW that is believed to be safe against
1949 side channel attacks- equals the tsx=auto command line parameter.
1953 bool "EFI runtime service support"
1956 select EFI_RUNTIME_WRAPPERS
1958 This enables the kernel to use EFI runtime services that are
1959 available (such as the EFI variable services).
1961 This option is only useful on systems that have EFI firmware.
1962 In addition, you should use the latest ELILO loader available
1963 at <http://elilo.sourceforge.net> in order to take advantage
1964 of EFI runtime services. However, even with this option, the
1965 resultant kernel should continue to boot on existing non-EFI
1969 bool "EFI stub support"
1970 depends on EFI && !X86_USE_3DNOW
1973 This kernel feature allows a bzImage to be loaded directly
1974 by EFI firmware without the use of a bootloader.
1976 See Documentation/efi-stub.txt for more information.
1979 bool "EFI mixed-mode support"
1980 depends on EFI_STUB && X86_64
1982 Enabling this feature allows a 64-bit kernel to be booted
1983 on a 32-bit firmware, provided that your CPU supports 64-bit
1986 Note that it is not possible to boot a mixed-mode enabled
1987 kernel via the EFI boot stub - a bootloader that supports
1988 the EFI handover protocol must be used.
1994 prompt "Enable seccomp to safely compute untrusted bytecode"
1996 This kernel feature is useful for number crunching applications
1997 that may need to compute untrusted bytecode during their
1998 execution. By using pipes or other transports made available to
1999 the process as file descriptors supporting the read/write
2000 syscalls, it's possible to isolate those applications in
2001 their own address space using seccomp. Once seccomp is
2002 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2003 and the task is only allowed to execute a few safe syscalls
2004 defined by each seccomp mode.
2006 If unsure, say Y. Only embedded should say N here.
2008 source kernel/Kconfig.hz
2011 bool "kexec system call"
2014 kexec is a system call that implements the ability to shutdown your
2015 current kernel, and to start another kernel. It is like a reboot
2016 but it is independent of the system firmware. And like a reboot
2017 you can start any kernel with it, not just Linux.
2019 The name comes from the similarity to the exec system call.
2021 It is an ongoing process to be certain the hardware in a machine
2022 is properly shutdown, so do not be surprised if this code does not
2023 initially work for you. As of this writing the exact hardware
2024 interface is strongly in flux, so no good recommendation can be
2028 bool "kexec file based system call"
2033 depends on CRYPTO_SHA256=y
2035 This is new version of kexec system call. This system call is
2036 file based and takes file descriptors as system call argument
2037 for kernel and initramfs as opposed to list of segments as
2038 accepted by previous system call.
2040 config ARCH_HAS_KEXEC_PURGATORY
2043 config KEXEC_VERIFY_SIG
2044 bool "Verify kernel signature during kexec_file_load() syscall"
2045 depends on KEXEC_FILE
2047 This option makes kernel signature verification mandatory for
2048 the kexec_file_load() syscall.
2050 In addition to that option, you need to enable signature
2051 verification for the corresponding kernel image type being
2052 loaded in order for this to work.
2054 config KEXEC_BZIMAGE_VERIFY_SIG
2055 bool "Enable bzImage signature verification support"
2056 depends on KEXEC_VERIFY_SIG
2057 depends on SIGNED_PE_FILE_VERIFICATION
2058 select SYSTEM_TRUSTED_KEYRING
2060 Enable bzImage signature verification support.
2063 bool "kernel crash dumps"
2064 depends on X86_64 || (X86_32 && HIGHMEM)
2066 Generate crash dump after being started by kexec.
2067 This should be normally only set in special crash dump kernels
2068 which are loaded in the main kernel with kexec-tools into
2069 a specially reserved region and then later executed after
2070 a crash by kdump/kexec. The crash dump kernel must be compiled
2071 to a memory address not used by the main kernel or BIOS using
2072 PHYSICAL_START, or it must be built as a relocatable image
2073 (CONFIG_RELOCATABLE=y).
2074 For more details see Documentation/kdump/kdump.txt
2078 depends on KEXEC && HIBERNATION
2080 Jump between original kernel and kexeced kernel and invoke
2081 code in physical address mode via KEXEC
2083 config PHYSICAL_START
2084 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2087 This gives the physical address where the kernel is loaded.
2089 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2090 bzImage will decompress itself to above physical address and
2091 run from there. Otherwise, bzImage will run from the address where
2092 it has been loaded by the boot loader and will ignore above physical
2095 In normal kdump cases one does not have to set/change this option
2096 as now bzImage can be compiled as a completely relocatable image
2097 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2098 address. This option is mainly useful for the folks who don't want
2099 to use a bzImage for capturing the crash dump and want to use a
2100 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2101 to be specifically compiled to run from a specific memory area
2102 (normally a reserved region) and this option comes handy.
2104 So if you are using bzImage for capturing the crash dump,
2105 leave the value here unchanged to 0x1000000 and set
2106 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2107 for capturing the crash dump change this value to start of
2108 the reserved region. In other words, it can be set based on
2109 the "X" value as specified in the "crashkernel=YM@XM"
2110 command line boot parameter passed to the panic-ed
2111 kernel. Please take a look at Documentation/kdump/kdump.txt
2112 for more details about crash dumps.
2114 Usage of bzImage for capturing the crash dump is recommended as
2115 one does not have to build two kernels. Same kernel can be used
2116 as production kernel and capture kernel. Above option should have
2117 gone away after relocatable bzImage support is introduced. But it
2118 is present because there are users out there who continue to use
2119 vmlinux for dump capture. This option should go away down the
2122 Don't change this unless you know what you are doing.
2125 bool "Build a relocatable kernel"
2128 This builds a kernel image that retains relocation information
2129 so it can be loaded someplace besides the default 1MB.
2130 The relocations tend to make the kernel binary about 10% larger,
2131 but are discarded at runtime.
2133 One use is for the kexec on panic case where the recovery kernel
2134 must live at a different physical address than the primary
2137 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2138 it has been loaded at and the compile time physical address
2139 (CONFIG_PHYSICAL_START) is used as the minimum location.
2141 config RANDOMIZE_BASE
2142 bool "Randomize the address of the kernel image (KASLR)"
2143 depends on RELOCATABLE
2146 In support of Kernel Address Space Layout Randomization (KASLR),
2147 this randomizes the physical address at which the kernel image
2148 is decompressed and the virtual address where the kernel
2149 image is mapped, as a security feature that deters exploit
2150 attempts relying on knowledge of the location of kernel
2153 On 64-bit, the kernel physical and virtual addresses are
2154 randomized separately. The physical address will be anywhere
2155 between 16MB and the top of physical memory (up to 64TB). The
2156 virtual address will be randomized from 16MB up to 1GB (9 bits
2157 of entropy). Note that this also reduces the memory space
2158 available to kernel modules from 1.5GB to 1GB.
2160 On 32-bit, the kernel physical and virtual addresses are
2161 randomized together. They will be randomized from 16MB up to
2162 512MB (8 bits of entropy).
2164 Entropy is generated using the RDRAND instruction if it is
2165 supported. If RDTSC is supported, its value is mixed into
2166 the entropy pool as well. If neither RDRAND nor RDTSC are
2167 supported, then entropy is read from the i8254 timer. The
2168 usable entropy is limited by the kernel being built using
2169 2GB addressing, and that PHYSICAL_ALIGN must be at a
2170 minimum of 2MB. As a result, only 10 bits of entropy are
2171 theoretically possible, but the implementations are further
2172 limited due to memory layouts.
2176 # Relocation on x86 needs some additional build support
2177 config X86_NEED_RELOCS
2179 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2181 config PHYSICAL_ALIGN
2182 hex "Alignment value to which kernel should be aligned"
2184 range 0x2000 0x1000000 if X86_32
2185 range 0x200000 0x1000000 if X86_64
2187 This value puts the alignment restrictions on physical address
2188 where kernel is loaded and run from. Kernel is compiled for an
2189 address which meets above alignment restriction.
2191 If bootloader loads the kernel at a non-aligned address and
2192 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2193 address aligned to above value and run from there.
2195 If bootloader loads the kernel at a non-aligned address and
2196 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2197 load address and decompress itself to the address it has been
2198 compiled for and run from there. The address for which kernel is
2199 compiled already meets above alignment restrictions. Hence the
2200 end result is that kernel runs from a physical address meeting
2201 above alignment restrictions.
2203 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2204 this value must be a multiple of 0x200000.
2206 Don't change this unless you know what you are doing.
2208 config DYNAMIC_MEMORY_LAYOUT
2211 This option makes base addresses of vmalloc and vmemmap as well as
2212 __PAGE_OFFSET movable during boot.
2214 config RANDOMIZE_MEMORY
2215 bool "Randomize the kernel memory sections"
2217 depends on RANDOMIZE_BASE
2218 select DYNAMIC_MEMORY_LAYOUT
2219 default RANDOMIZE_BASE
2221 Randomizes the base virtual address of kernel memory sections
2222 (physical memory mapping, vmalloc & vmemmap). This security feature
2223 makes exploits relying on predictable memory locations less reliable.
2225 The order of allocations remains unchanged. Entropy is generated in
2226 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2227 configuration have in average 30,000 different possible virtual
2228 addresses for each memory section.
2232 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2233 hex "Physical memory mapping padding" if EXPERT
2234 depends on RANDOMIZE_MEMORY
2235 default "0xa" if MEMORY_HOTPLUG
2237 range 0x1 0x40 if MEMORY_HOTPLUG
2240 Define the padding in terabytes added to the existing physical
2241 memory size during kernel memory randomization. It is useful
2242 for memory hotplug support but reduces the entropy available for
2243 address randomization.
2245 If unsure, leave at the default value.
2251 config BOOTPARAM_HOTPLUG_CPU0
2252 bool "Set default setting of cpu0_hotpluggable"
2254 depends on HOTPLUG_CPU
2256 Set whether default state of cpu0_hotpluggable is on or off.
2258 Say Y here to enable CPU0 hotplug by default. If this switch
2259 is turned on, there is no need to give cpu0_hotplug kernel
2260 parameter and the CPU0 hotplug feature is enabled by default.
2262 Please note: there are two known CPU0 dependencies if you want
2263 to enable the CPU0 hotplug feature either by this switch or by
2264 cpu0_hotplug kernel parameter.
2266 First, resume from hibernate or suspend always starts from CPU0.
2267 So hibernate and suspend are prevented if CPU0 is offline.
2269 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2270 offline if any interrupt can not migrate out of CPU0. There may
2271 be other CPU0 dependencies.
2273 Please make sure the dependencies are under your control before
2274 you enable this feature.
2276 Say N if you don't want to enable CPU0 hotplug feature by default.
2277 You still can enable the CPU0 hotplug feature at boot by kernel
2278 parameter cpu0_hotplug.
2280 config DEBUG_HOTPLUG_CPU0
2282 prompt "Debug CPU0 hotplug"
2283 depends on HOTPLUG_CPU
2285 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2286 soon as possible and boots up userspace with CPU0 offlined. User
2287 can online CPU0 back after boot time.
2289 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2290 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2291 compilation or giving cpu0_hotplug kernel parameter at boot.
2297 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2298 depends on COMPAT_32
2300 Certain buggy versions of glibc will crash if they are
2301 presented with a 32-bit vDSO that is not mapped at the address
2302 indicated in its segment table.
2304 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2305 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2306 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2307 the only released version with the bug, but OpenSUSE 9
2308 contains a buggy "glibc 2.3.2".
2310 The symptom of the bug is that everything crashes on startup, saying:
2311 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2313 Saying Y here changes the default value of the vdso32 boot
2314 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2315 This works around the glibc bug but hurts performance.
2317 If unsure, say N: if you are compiling your own kernel, you
2318 are unlikely to be using a buggy version of glibc.
2321 prompt "vsyscall table for legacy applications"
2323 default LEGACY_VSYSCALL_EMULATE
2325 Legacy user code that does not know how to find the vDSO expects
2326 to be able to issue three syscalls by calling fixed addresses in
2327 kernel space. Since this location is not randomized with ASLR,
2328 it can be used to assist security vulnerability exploitation.
2330 This setting can be changed at boot time via the kernel command
2331 line parameter vsyscall=[emulate|none].
2333 On a system with recent enough glibc (2.14 or newer) and no
2334 static binaries, you can say None without a performance penalty
2335 to improve security.
2337 If unsure, select "Emulate".
2339 config LEGACY_VSYSCALL_EMULATE
2342 The kernel traps and emulates calls into the fixed
2343 vsyscall address mapping. This makes the mapping
2344 non-executable, but it still contains known contents,
2345 which could be used in certain rare security vulnerability
2346 exploits. This configuration is recommended when userspace
2347 still uses the vsyscall area.
2349 config LEGACY_VSYSCALL_NONE
2352 There will be no vsyscall mapping at all. This will
2353 eliminate any risk of ASLR bypass due to the vsyscall
2354 fixed address mapping. Attempts to use the vsyscalls
2355 will be reported to dmesg, so that either old or
2356 malicious userspace programs can be identified.
2361 bool "Built-in kernel command line"
2363 Allow for specifying boot arguments to the kernel at
2364 build time. On some systems (e.g. embedded ones), it is
2365 necessary or convenient to provide some or all of the
2366 kernel boot arguments with the kernel itself (that is,
2367 to not rely on the boot loader to provide them.)
2369 To compile command line arguments into the kernel,
2370 set this option to 'Y', then fill in the
2371 boot arguments in CONFIG_CMDLINE.
2373 Systems with fully functional boot loaders (i.e. non-embedded)
2374 should leave this option set to 'N'.
2377 string "Built-in kernel command string"
2378 depends on CMDLINE_BOOL
2381 Enter arguments here that should be compiled into the kernel
2382 image and used at boot time. If the boot loader provides a
2383 command line at boot time, it is appended to this string to
2384 form the full kernel command line, when the system boots.
2386 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2387 change this behavior.
2389 In most cases, the command line (whether built-in or provided
2390 by the boot loader) should specify the device for the root
2393 config CMDLINE_OVERRIDE
2394 bool "Built-in command line overrides boot loader arguments"
2395 depends on CMDLINE_BOOL
2397 Set this option to 'Y' to have the kernel ignore the boot loader
2398 command line, and use ONLY the built-in command line.
2400 This is used to work around broken boot loaders. This should
2401 be set to 'N' under normal conditions.
2403 config MODIFY_LDT_SYSCALL
2404 bool "Enable the LDT (local descriptor table)" if EXPERT
2407 Linux can allow user programs to install a per-process x86
2408 Local Descriptor Table (LDT) using the modify_ldt(2) system
2409 call. This is required to run 16-bit or segmented code such as
2410 DOSEMU or some Wine programs. It is also used by some very old
2411 threading libraries.
2413 Enabling this feature adds a small amount of overhead to
2414 context switches and increases the low-level kernel attack
2415 surface. Disabling it removes the modify_ldt(2) system call.
2417 Saying 'N' here may make sense for embedded or server kernels.
2419 source "kernel/livepatch/Kconfig"
2423 config ARCH_HAS_ADD_PAGES
2425 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2427 config ARCH_ENABLE_MEMORY_HOTPLUG
2429 depends on X86_64 || (X86_32 && HIGHMEM)
2431 config ARCH_ENABLE_MEMORY_HOTREMOVE
2433 depends on MEMORY_HOTPLUG
2435 config USE_PERCPU_NUMA_NODE_ID
2439 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2441 depends on X86_64 || X86_PAE
2443 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2445 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2447 config ARCH_ENABLE_THP_MIGRATION
2449 depends on X86_64 && TRANSPARENT_HUGEPAGE
2451 menu "Power management and ACPI options"
2453 config ARCH_HIBERNATION_HEADER
2455 depends on X86_64 && HIBERNATION
2457 source "kernel/power/Kconfig"
2459 source "drivers/acpi/Kconfig"
2461 source "drivers/sfi/Kconfig"
2468 tristate "APM (Advanced Power Management) BIOS support"
2469 depends on X86_32 && PM_SLEEP
2471 APM is a BIOS specification for saving power using several different
2472 techniques. This is mostly useful for battery powered laptops with
2473 APM compliant BIOSes. If you say Y here, the system time will be
2474 reset after a RESUME operation, the /proc/apm device will provide
2475 battery status information, and user-space programs will receive
2476 notification of APM "events" (e.g. battery status change).
2478 If you select "Y" here, you can disable actual use of the APM
2479 BIOS by passing the "apm=off" option to the kernel at boot time.
2481 Note that the APM support is almost completely disabled for
2482 machines with more than one CPU.
2484 In order to use APM, you will need supporting software. For location
2485 and more information, read <file:Documentation/power/apm-acpi.txt>
2486 and the Battery Powered Linux mini-HOWTO, available from
2487 <http://www.tldp.org/docs.html#howto>.
2489 This driver does not spin down disk drives (see the hdparm(8)
2490 manpage ("man 8 hdparm") for that), and it doesn't turn off
2491 VESA-compliant "green" monitors.
2493 This driver does not support the TI 4000M TravelMate and the ACER
2494 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2495 desktop machines also don't have compliant BIOSes, and this driver
2496 may cause those machines to panic during the boot phase.
2498 Generally, if you don't have a battery in your machine, there isn't
2499 much point in using this driver and you should say N. If you get
2500 random kernel OOPSes or reboots that don't seem to be related to
2501 anything, try disabling/enabling this option (or disabling/enabling
2504 Some other things you should try when experiencing seemingly random,
2507 1) make sure that you have enough swap space and that it is
2509 2) pass the "no-hlt" option to the kernel
2510 3) switch on floating point emulation in the kernel and pass
2511 the "no387" option to the kernel
2512 4) pass the "floppy=nodma" option to the kernel
2513 5) pass the "mem=4M" option to the kernel (thereby disabling
2514 all but the first 4 MB of RAM)
2515 6) make sure that the CPU is not over clocked.
2516 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2517 8) disable the cache from your BIOS settings
2518 9) install a fan for the video card or exchange video RAM
2519 10) install a better fan for the CPU
2520 11) exchange RAM chips
2521 12) exchange the motherboard.
2523 To compile this driver as a module, choose M here: the
2524 module will be called apm.
2528 config APM_IGNORE_USER_SUSPEND
2529 bool "Ignore USER SUSPEND"
2531 This option will ignore USER SUSPEND requests. On machines with a
2532 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2533 series notebooks, it is necessary to say Y because of a BIOS bug.
2535 config APM_DO_ENABLE
2536 bool "Enable PM at boot time"
2538 Enable APM features at boot time. From page 36 of the APM BIOS
2539 specification: "When disabled, the APM BIOS does not automatically
2540 power manage devices, enter the Standby State, enter the Suspend
2541 State, or take power saving steps in response to CPU Idle calls."
2542 This driver will make CPU Idle calls when Linux is idle (unless this
2543 feature is turned off -- see "Do CPU IDLE calls", below). This
2544 should always save battery power, but more complicated APM features
2545 will be dependent on your BIOS implementation. You may need to turn
2546 this option off if your computer hangs at boot time when using APM
2547 support, or if it beeps continuously instead of suspending. Turn
2548 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2549 T400CDT. This is off by default since most machines do fine without
2554 bool "Make CPU Idle calls when idle"
2556 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2557 On some machines, this can activate improved power savings, such as
2558 a slowed CPU clock rate, when the machine is idle. These idle calls
2559 are made after the idle loop has run for some length of time (e.g.,
2560 333 mS). On some machines, this will cause a hang at boot time or
2561 whenever the CPU becomes idle. (On machines with more than one CPU,
2562 this option does nothing.)
2564 config APM_DISPLAY_BLANK
2565 bool "Enable console blanking using APM"
2567 Enable console blanking using the APM. Some laptops can use this to
2568 turn off the LCD backlight when the screen blanker of the Linux
2569 virtual console blanks the screen. Note that this is only used by
2570 the virtual console screen blanker, and won't turn off the backlight
2571 when using the X Window system. This also doesn't have anything to
2572 do with your VESA-compliant power-saving monitor. Further, this
2573 option doesn't work for all laptops -- it might not turn off your
2574 backlight at all, or it might print a lot of errors to the console,
2575 especially if you are using gpm.
2577 config APM_ALLOW_INTS
2578 bool "Allow interrupts during APM BIOS calls"
2580 Normally we disable external interrupts while we are making calls to
2581 the APM BIOS as a measure to lessen the effects of a badly behaving
2582 BIOS implementation. The BIOS should reenable interrupts if it
2583 needs to. Unfortunately, some BIOSes do not -- especially those in
2584 many of the newer IBM Thinkpads. If you experience hangs when you
2585 suspend, try setting this to Y. Otherwise, say N.
2589 source "drivers/cpufreq/Kconfig"
2591 source "drivers/cpuidle/Kconfig"
2593 source "drivers/idle/Kconfig"
2598 menu "Bus options (PCI etc.)"
2604 Find out whether you have a PCI motherboard. PCI is the name of a
2605 bus system, i.e. the way the CPU talks to the other stuff inside
2606 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2607 VESA. If you have PCI, say Y, otherwise N.
2610 prompt "PCI access mode"
2611 depends on X86_32 && PCI
2614 On PCI systems, the BIOS can be used to detect the PCI devices and
2615 determine their configuration. However, some old PCI motherboards
2616 have BIOS bugs and may crash if this is done. Also, some embedded
2617 PCI-based systems don't have any BIOS at all. Linux can also try to
2618 detect the PCI hardware directly without using the BIOS.
2620 With this option, you can specify how Linux should detect the
2621 PCI devices. If you choose "BIOS", the BIOS will be used,
2622 if you choose "Direct", the BIOS won't be used, and if you
2623 choose "MMConfig", then PCI Express MMCONFIG will be used.
2624 If you choose "Any", the kernel will try MMCONFIG, then the
2625 direct access method and falls back to the BIOS if that doesn't
2626 work. If unsure, go with the default, which is "Any".
2631 config PCI_GOMMCONFIG
2648 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2650 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2653 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2656 bool "Support mmconfig PCI config space access" if X86_64
2658 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2659 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2663 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2667 depends on PCI && XEN
2674 config MMCONF_FAM10H
2676 depends on X86_64 && PCI_MMCONFIG && ACPI
2678 config PCI_CNB20LE_QUIRK
2679 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2682 Read the PCI windows out of the CNB20LE host bridge. This allows
2683 PCI hotplug to work on systems with the CNB20LE chipset which do
2686 There's no public spec for this chipset, and this functionality
2687 is known to be incomplete.
2689 You should say N unless you know you need this.
2691 source "drivers/pci/Kconfig"
2694 bool "ISA bus support on modern systems" if EXPERT
2696 Expose ISA bus device drivers and options available for selection and
2697 configuration. Enable this option if your target machine has an ISA
2698 bus. ISA is an older system, displaced by PCI and newer bus
2699 architectures -- if your target machine is modern, it probably does
2700 not have an ISA bus.
2704 # x86_64 have no ISA slots, but can have ISA-style DMA.
2706 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2709 Enables ISA-style DMA support for devices requiring such controllers.
2717 Find out whether you have ISA slots on your motherboard. ISA is the
2718 name of a bus system, i.e. the way the CPU talks to the other stuff
2719 inside your box. Other bus systems are PCI, EISA, MicroChannel
2720 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2721 newer boards don't support it. If you have ISA, say Y, otherwise N.
2727 The Extended Industry Standard Architecture (EISA) bus was
2728 developed as an open alternative to the IBM MicroChannel bus.
2730 The EISA bus provided some of the features of the IBM MicroChannel
2731 bus while maintaining backward compatibility with cards made for
2732 the older ISA bus. The EISA bus saw limited use between 1988 and
2733 1995 when it was made obsolete by the PCI bus.
2735 Say Y here if you are building a kernel for an EISA-based machine.
2739 source "drivers/eisa/Kconfig"
2742 tristate "NatSemi SCx200 support"
2744 This provides basic support for National Semiconductor's
2745 (now AMD's) Geode processors. The driver probes for the
2746 PCI-IDs of several on-chip devices, so its a good dependency
2747 for other scx200_* drivers.
2749 If compiled as a module, the driver is named scx200.
2751 config SCx200HR_TIMER
2752 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2756 This driver provides a clocksource built upon the on-chip
2757 27MHz high-resolution timer. Its also a workaround for
2758 NSC Geode SC-1100's buggy TSC, which loses time when the
2759 processor goes idle (as is done by the scheduler). The
2760 other workaround is idle=poll boot option.
2763 bool "One Laptop Per Child support"
2770 Add support for detecting the unique features of the OLPC
2774 bool "OLPC XO-1 Power Management"
2775 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2777 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2780 bool "OLPC XO-1 Real Time Clock"
2781 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2783 Add support for the XO-1 real time clock, which can be used as a
2784 programmable wakeup source.
2787 bool "OLPC XO-1 SCI extras"
2788 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2792 Add support for SCI-based features of the OLPC XO-1 laptop:
2793 - EC-driven system wakeups
2797 - AC adapter status updates
2798 - Battery status updates
2800 config OLPC_XO15_SCI
2801 bool "OLPC XO-1.5 SCI extras"
2802 depends on OLPC && ACPI
2805 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2806 - EC-driven system wakeups
2807 - AC adapter status updates
2808 - Battery status updates
2811 bool "PCEngines ALIX System Support (LED setup)"
2814 This option enables system support for the PCEngines ALIX.
2815 At present this just sets up LEDs for GPIO control on
2816 ALIX2/3/6 boards. However, other system specific setup should
2819 Note: You must still enable the drivers for GPIO and LED support
2820 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2822 Note: You have to set alix.force=1 for boards with Award BIOS.
2825 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2828 This option enables system support for the Soekris Engineering net5501.
2831 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2835 This option enables system support for the Traverse Technologies GEOS.
2838 bool "Technologic Systems TS-5500 platform support"
2840 select CHECK_SIGNATURE
2844 This option enables system support for the Technologic Systems TS-5500.
2850 depends on CPU_SUP_AMD && PCI
2852 source "drivers/pcmcia/Kconfig"
2855 tristate "RapidIO support"
2859 If enabled this option will include drivers and the core
2860 infrastructure code to support RapidIO interconnect devices.
2862 source "drivers/rapidio/Kconfig"
2865 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2867 Firmwares often provide initial graphics framebuffers so the BIOS,
2868 bootloader or kernel can show basic video-output during boot for
2869 user-guidance and debugging. Historically, x86 used the VESA BIOS
2870 Extensions and EFI-framebuffers for this, which are mostly limited
2872 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2873 framebuffers so the new generic system-framebuffer drivers can be
2874 used on x86. If the framebuffer is not compatible with the generic
2875 modes, it is advertised as fallback platform framebuffer so legacy
2876 drivers like efifb, vesafb and uvesafb can pick it up.
2877 If this option is not selected, all system framebuffers are always
2878 marked as fallback platform framebuffers as usual.
2880 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2881 not be able to pick up generic system framebuffers if this option
2882 is selected. You are highly encouraged to enable simplefb as
2883 replacement if you select this option. simplefb can correctly deal
2884 with generic system framebuffers. But you should still keep vesafb
2885 and others enabled as fallback if a system framebuffer is
2886 incompatible with simplefb.
2893 menu "Binary Emulations"
2895 config IA32_EMULATION
2896 bool "IA32 Emulation"
2898 select ARCH_WANT_OLD_COMPAT_IPC
2900 select COMPAT_BINFMT_ELF
2901 select COMPAT_OLD_SIGACTION
2903 Include code to run legacy 32-bit programs under a
2904 64-bit kernel. You should likely turn this on, unless you're
2905 100% sure that you don't have any 32-bit programs left.
2908 tristate "IA32 a.out support"
2909 depends on IA32_EMULATION
2911 Support old a.out binaries in the 32bit emulation.
2914 bool "x32 ABI for 64-bit mode"
2917 Include code to run binaries for the x32 native 32-bit ABI
2918 for 64-bit processors. An x32 process gets access to the
2919 full 64-bit register file and wide data path while leaving
2920 pointers at 32 bits for smaller memory footprint.
2922 You will need a recent binutils (2.22 or later) with
2923 elf32_x86_64 support enabled to compile a kernel with this
2928 depends on IA32_EMULATION || X86_32
2930 select OLD_SIGSUSPEND3
2934 depends on IA32_EMULATION || X86_X32
2937 config COMPAT_FOR_U64_ALIGNMENT
2940 config SYSVIPC_COMPAT
2948 config HAVE_ATOMIC_IOMAP
2952 config X86_DEV_DMA_OPS
2954 depends on X86_64 || STA2X11
2956 config X86_DMA_REMAP
2960 config HAVE_GENERIC_GUP
2963 source "drivers/firmware/Kconfig"
2965 source "arch/x86/kvm/Kconfig"