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 && !MWINCHIP3D && !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
1492 select ARCH_USE_MEMREMAP_PROT
1494 Say yes to enable support for the encryption of system memory.
1495 This requires an AMD processor that supports Secure Memory
1498 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1499 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 # Common NUMA Features
1513 bool "Numa Memory Allocation and Scheduler Support"
1515 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1516 default y if X86_BIGSMP
1518 Enable NUMA (Non Uniform Memory Access) support.
1520 The kernel will try to allocate memory used by a CPU on the
1521 local memory controller of the CPU and add some more
1522 NUMA awareness to the kernel.
1524 For 64-bit this is recommended if the system is Intel Core i7
1525 (or later), AMD Opteron, or EM64T NUMA.
1527 For 32-bit this is only needed if you boot a 32-bit
1528 kernel on a 64-bit NUMA platform.
1530 Otherwise, you should say N.
1534 prompt "Old style AMD Opteron NUMA detection"
1535 depends on X86_64 && NUMA && PCI
1537 Enable AMD NUMA node topology detection. You should say Y here if
1538 you have a multi processor AMD system. This uses an old method to
1539 read the NUMA configuration directly from the builtin Northbridge
1540 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1541 which also takes priority if both are compiled in.
1543 config X86_64_ACPI_NUMA
1545 prompt "ACPI NUMA detection"
1546 depends on X86_64 && NUMA && ACPI && PCI
1549 Enable ACPI SRAT based node topology detection.
1551 # Some NUMA nodes have memory ranges that span
1552 # other nodes. Even though a pfn is valid and
1553 # between a node's start and end pfns, it may not
1554 # reside on that node. See memmap_init_zone()
1556 config NODES_SPAN_OTHER_NODES
1558 depends on X86_64_ACPI_NUMA
1561 bool "NUMA emulation"
1564 Enable NUMA emulation. A flat machine will be split
1565 into virtual nodes when booted with "numa=fake=N", where N is the
1566 number of nodes. This is only useful for debugging.
1569 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1571 default "10" if MAXSMP
1572 default "6" if X86_64
1574 depends on NEED_MULTIPLE_NODES
1576 Specify the maximum number of NUMA Nodes available on the target
1577 system. Increases memory reserved to accommodate various tables.
1579 config ARCH_HAVE_MEMORY_PRESENT
1581 depends on X86_32 && DISCONTIGMEM
1583 config ARCH_FLATMEM_ENABLE
1585 depends on X86_32 && !NUMA
1587 config ARCH_DISCONTIGMEM_ENABLE
1589 depends on NUMA && X86_32
1591 config ARCH_DISCONTIGMEM_DEFAULT
1593 depends on NUMA && X86_32
1595 config ARCH_SPARSEMEM_ENABLE
1597 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1598 select SPARSEMEM_STATIC if X86_32
1599 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1601 config ARCH_SPARSEMEM_DEFAULT
1605 config ARCH_SELECT_MEMORY_MODEL
1607 depends on ARCH_SPARSEMEM_ENABLE
1609 config ARCH_MEMORY_PROBE
1610 bool "Enable sysfs memory/probe interface"
1611 depends on X86_64 && MEMORY_HOTPLUG
1613 This option enables a sysfs memory/probe interface for testing.
1614 See Documentation/memory-hotplug.txt for more information.
1615 If you are unsure how to answer this question, answer N.
1617 config ARCH_PROC_KCORE_TEXT
1619 depends on X86_64 && PROC_KCORE
1621 config ILLEGAL_POINTER_VALUE
1624 default 0xdead000000000000 if X86_64
1626 config X86_PMEM_LEGACY_DEVICE
1629 config X86_PMEM_LEGACY
1630 tristate "Support non-standard NVDIMMs and ADR protected memory"
1631 depends on PHYS_ADDR_T_64BIT
1633 select X86_PMEM_LEGACY_DEVICE
1636 Treat memory marked using the non-standard e820 type of 12 as used
1637 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1638 The kernel will offer these regions to the 'pmem' driver so
1639 they can be used for persistent storage.
1644 bool "Allocate 3rd-level pagetables from highmem"
1647 The VM uses one page table entry for each page of physical memory.
1648 For systems with a lot of RAM, this can be wasteful of precious
1649 low memory. Setting this option will put user-space page table
1650 entries in high memory.
1652 config X86_CHECK_BIOS_CORRUPTION
1653 bool "Check for low memory corruption"
1655 Periodically check for memory corruption in low memory, which
1656 is suspected to be caused by BIOS. Even when enabled in the
1657 configuration, it is disabled at runtime. Enable it by
1658 setting "memory_corruption_check=1" on the kernel command
1659 line. By default it scans the low 64k of memory every 60
1660 seconds; see the memory_corruption_check_size and
1661 memory_corruption_check_period parameters in
1662 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1664 When enabled with the default parameters, this option has
1665 almost no overhead, as it reserves a relatively small amount
1666 of memory and scans it infrequently. It both detects corruption
1667 and prevents it from affecting the running system.
1669 It is, however, intended as a diagnostic tool; if repeatable
1670 BIOS-originated corruption always affects the same memory,
1671 you can use memmap= to prevent the kernel from using that
1674 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1675 bool "Set the default setting of memory_corruption_check"
1676 depends on X86_CHECK_BIOS_CORRUPTION
1679 Set whether the default state of memory_corruption_check is
1682 config X86_RESERVE_LOW
1683 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1687 Specify the amount of low memory to reserve for the BIOS.
1689 The first page contains BIOS data structures that the kernel
1690 must not use, so that page must always be reserved.
1692 By default we reserve the first 64K of physical RAM, as a
1693 number of BIOSes are known to corrupt that memory range
1694 during events such as suspend/resume or monitor cable
1695 insertion, so it must not be used by the kernel.
1697 You can set this to 4 if you are absolutely sure that you
1698 trust the BIOS to get all its memory reservations and usages
1699 right. If you know your BIOS have problems beyond the
1700 default 64K area, you can set this to 640 to avoid using the
1701 entire low memory range.
1703 If you have doubts about the BIOS (e.g. suspend/resume does
1704 not work or there's kernel crashes after certain hardware
1705 hotplug events) then you might want to enable
1706 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1707 typical corruption patterns.
1709 Leave this to the default value of 64 if you are unsure.
1711 config MATH_EMULATION
1713 depends on MODIFY_LDT_SYSCALL
1714 prompt "Math emulation" if X86_32
1716 Linux can emulate a math coprocessor (used for floating point
1717 operations) if you don't have one. 486DX and Pentium processors have
1718 a math coprocessor built in, 486SX and 386 do not, unless you added
1719 a 487DX or 387, respectively. (The messages during boot time can
1720 give you some hints here ["man dmesg"].) Everyone needs either a
1721 coprocessor or this emulation.
1723 If you don't have a math coprocessor, you need to say Y here; if you
1724 say Y here even though you have a coprocessor, the coprocessor will
1725 be used nevertheless. (This behavior can be changed with the kernel
1726 command line option "no387", which comes handy if your coprocessor
1727 is broken. Try "man bootparam" or see the documentation of your boot
1728 loader (lilo or loadlin) about how to pass options to the kernel at
1729 boot time.) This means that it is a good idea to say Y here if you
1730 intend to use this kernel on different machines.
1732 More information about the internals of the Linux math coprocessor
1733 emulation can be found in <file:arch/x86/math-emu/README>.
1735 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1736 kernel, it won't hurt.
1740 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1742 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1743 the Memory Type Range Registers (MTRRs) may be used to control
1744 processor access to memory ranges. This is most useful if you have
1745 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1746 allows bus write transfers to be combined into a larger transfer
1747 before bursting over the PCI/AGP bus. This can increase performance
1748 of image write operations 2.5 times or more. Saying Y here creates a
1749 /proc/mtrr file which may be used to manipulate your processor's
1750 MTRRs. Typically the X server should use this.
1752 This code has a reasonably generic interface so that similar
1753 control registers on other processors can be easily supported
1756 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1757 Registers (ARRs) which provide a similar functionality to MTRRs. For
1758 these, the ARRs are used to emulate the MTRRs.
1759 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1760 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1761 write-combining. All of these processors are supported by this code
1762 and it makes sense to say Y here if you have one of them.
1764 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1765 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1766 can lead to all sorts of problems, so it's good to say Y here.
1768 You can safely say Y even if your machine doesn't have MTRRs, you'll
1769 just add about 9 KB to your kernel.
1771 See <file:Documentation/x86/mtrr.txt> for more information.
1773 config MTRR_SANITIZER
1775 prompt "MTRR cleanup support"
1778 Convert MTRR layout from continuous to discrete, so X drivers can
1779 add writeback entries.
1781 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1782 The largest mtrr entry size for a continuous block can be set with
1787 config MTRR_SANITIZER_ENABLE_DEFAULT
1788 int "MTRR cleanup enable value (0-1)"
1791 depends on MTRR_SANITIZER
1793 Enable mtrr cleanup default value
1795 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1796 int "MTRR cleanup spare reg num (0-7)"
1799 depends on MTRR_SANITIZER
1801 mtrr cleanup spare entries default, it can be changed via
1802 mtrr_spare_reg_nr=N on the kernel command line.
1806 prompt "x86 PAT support" if EXPERT
1809 Use PAT attributes to setup page level cache control.
1811 PATs are the modern equivalents of MTRRs and are much more
1812 flexible than MTRRs.
1814 Say N here if you see bootup problems (boot crash, boot hang,
1815 spontaneous reboots) or a non-working video driver.
1819 config ARCH_USES_PG_UNCACHED
1825 prompt "x86 architectural random number generator" if EXPERT
1827 Enable the x86 architectural RDRAND instruction
1828 (Intel Bull Mountain technology) to generate random numbers.
1829 If supported, this is a high bandwidth, cryptographically
1830 secure hardware random number generator.
1834 prompt "Supervisor Mode Access Prevention" if EXPERT
1836 Supervisor Mode Access Prevention (SMAP) is a security
1837 feature in newer Intel processors. There is a small
1838 performance cost if this enabled and turned on; there is
1839 also a small increase in the kernel size if this is enabled.
1843 config X86_INTEL_UMIP
1845 depends on CPU_SUP_INTEL
1846 prompt "Intel User Mode Instruction Prevention" if EXPERT
1848 The User Mode Instruction Prevention (UMIP) is a security
1849 feature in newer Intel processors. If enabled, a general
1850 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1851 or STR instructions are executed in user mode. These instructions
1852 unnecessarily expose information about the hardware state.
1854 The vast majority of applications do not use these instructions.
1855 For the very few that do, software emulation is provided in
1856 specific cases in protected and virtual-8086 modes. Emulated
1859 config X86_INTEL_MPX
1860 prompt "Intel MPX (Memory Protection Extensions)"
1862 # Note: only available in 64-bit mode due to VMA flags shortage
1863 depends on CPU_SUP_INTEL && X86_64
1864 select ARCH_USES_HIGH_VMA_FLAGS
1866 MPX provides hardware features that can be used in
1867 conjunction with compiler-instrumented code to check
1868 memory references. It is designed to detect buffer
1869 overflow or underflow bugs.
1871 This option enables running applications which are
1872 instrumented or otherwise use MPX. It does not use MPX
1873 itself inside the kernel or to protect the kernel
1874 against bad memory references.
1876 Enabling this option will make the kernel larger:
1877 ~8k of kernel text and 36 bytes of data on a 64-bit
1878 defconfig. It adds a long to the 'mm_struct' which
1879 will increase the kernel memory overhead of each
1880 process and adds some branches to paths used during
1881 exec() and munmap().
1883 For details, see Documentation/x86/intel_mpx.txt
1887 config X86_INTEL_MEMORY_PROTECTION_KEYS
1888 prompt "Intel Memory Protection Keys"
1890 # Note: only available in 64-bit mode
1891 depends on CPU_SUP_INTEL && X86_64
1892 select ARCH_USES_HIGH_VMA_FLAGS
1893 select ARCH_HAS_PKEYS
1895 Memory Protection Keys provides a mechanism for enforcing
1896 page-based protections, but without requiring modification of the
1897 page tables when an application changes protection domains.
1899 For details, see Documentation/x86/protection-keys.txt
1904 prompt "TSX enable mode"
1905 depends on CPU_SUP_INTEL
1906 default X86_INTEL_TSX_MODE_OFF
1908 Intel's TSX (Transactional Synchronization Extensions) feature
1909 allows to optimize locking protocols through lock elision which
1910 can lead to a noticeable performance boost.
1912 On the other hand it has been shown that TSX can be exploited
1913 to form side channel attacks (e.g. TAA) and chances are there
1914 will be more of those attacks discovered in the future.
1916 Therefore TSX is not enabled by default (aka tsx=off). An admin
1917 might override this decision by tsx=on the command line parameter.
1918 Even with TSX enabled, the kernel will attempt to enable the best
1919 possible TAA mitigation setting depending on the microcode available
1920 for the particular machine.
1922 This option allows to set the default tsx mode between tsx=on, =off
1923 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1926 Say off if not sure, auto if TSX is in use but it should be used on safe
1927 platforms or on if TSX is in use and the security aspect of tsx is not
1930 config X86_INTEL_TSX_MODE_OFF
1933 TSX is disabled if possible - equals to tsx=off command line parameter.
1935 config X86_INTEL_TSX_MODE_ON
1938 TSX is always enabled on TSX capable HW - equals the tsx=on command
1941 config X86_INTEL_TSX_MODE_AUTO
1944 TSX is enabled on TSX capable HW that is believed to be safe against
1945 side channel attacks- equals the tsx=auto command line parameter.
1949 bool "EFI runtime service support"
1952 select EFI_RUNTIME_WRAPPERS
1953 select ARCH_USE_MEMREMAP_PROT
1955 This enables the kernel to use EFI runtime services that are
1956 available (such as the EFI variable services).
1958 This option is only useful on systems that have EFI firmware.
1959 In addition, you should use the latest ELILO loader available
1960 at <http://elilo.sourceforge.net> in order to take advantage
1961 of EFI runtime services. However, even with this option, the
1962 resultant kernel should continue to boot on existing non-EFI
1966 bool "EFI stub support"
1967 depends on EFI && !X86_USE_3DNOW
1970 This kernel feature allows a bzImage to be loaded directly
1971 by EFI firmware without the use of a bootloader.
1973 See Documentation/efi-stub.txt for more information.
1976 bool "EFI mixed-mode support"
1977 depends on EFI_STUB && X86_64
1979 Enabling this feature allows a 64-bit kernel to be booted
1980 on a 32-bit firmware, provided that your CPU supports 64-bit
1983 Note that it is not possible to boot a mixed-mode enabled
1984 kernel via the EFI boot stub - a bootloader that supports
1985 the EFI handover protocol must be used.
1991 prompt "Enable seccomp to safely compute untrusted bytecode"
1993 This kernel feature is useful for number crunching applications
1994 that may need to compute untrusted bytecode during their
1995 execution. By using pipes or other transports made available to
1996 the process as file descriptors supporting the read/write
1997 syscalls, it's possible to isolate those applications in
1998 their own address space using seccomp. Once seccomp is
1999 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2000 and the task is only allowed to execute a few safe syscalls
2001 defined by each seccomp mode.
2003 If unsure, say Y. Only embedded should say N here.
2005 source kernel/Kconfig.hz
2008 bool "kexec system call"
2011 kexec is a system call that implements the ability to shutdown your
2012 current kernel, and to start another kernel. It is like a reboot
2013 but it is independent of the system firmware. And like a reboot
2014 you can start any kernel with it, not just Linux.
2016 The name comes from the similarity to the exec system call.
2018 It is an ongoing process to be certain the hardware in a machine
2019 is properly shutdown, so do not be surprised if this code does not
2020 initially work for you. As of this writing the exact hardware
2021 interface is strongly in flux, so no good recommendation can be
2025 bool "kexec file based system call"
2030 depends on CRYPTO_SHA256=y
2032 This is new version of kexec system call. This system call is
2033 file based and takes file descriptors as system call argument
2034 for kernel and initramfs as opposed to list of segments as
2035 accepted by previous system call.
2037 config ARCH_HAS_KEXEC_PURGATORY
2040 config KEXEC_VERIFY_SIG
2041 bool "Verify kernel signature during kexec_file_load() syscall"
2042 depends on KEXEC_FILE
2044 This option makes kernel signature verification mandatory for
2045 the kexec_file_load() syscall.
2047 In addition to that option, you need to enable signature
2048 verification for the corresponding kernel image type being
2049 loaded in order for this to work.
2051 config KEXEC_BZIMAGE_VERIFY_SIG
2052 bool "Enable bzImage signature verification support"
2053 depends on KEXEC_VERIFY_SIG
2054 depends on SIGNED_PE_FILE_VERIFICATION
2055 select SYSTEM_TRUSTED_KEYRING
2057 Enable bzImage signature verification support.
2060 bool "kernel crash dumps"
2061 depends on X86_64 || (X86_32 && HIGHMEM)
2063 Generate crash dump after being started by kexec.
2064 This should be normally only set in special crash dump kernels
2065 which are loaded in the main kernel with kexec-tools into
2066 a specially reserved region and then later executed after
2067 a crash by kdump/kexec. The crash dump kernel must be compiled
2068 to a memory address not used by the main kernel or BIOS using
2069 PHYSICAL_START, or it must be built as a relocatable image
2070 (CONFIG_RELOCATABLE=y).
2071 For more details see Documentation/kdump/kdump.txt
2075 depends on KEXEC && HIBERNATION
2077 Jump between original kernel and kexeced kernel and invoke
2078 code in physical address mode via KEXEC
2080 config PHYSICAL_START
2081 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2084 This gives the physical address where the kernel is loaded.
2086 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2087 bzImage will decompress itself to above physical address and
2088 run from there. Otherwise, bzImage will run from the address where
2089 it has been loaded by the boot loader and will ignore above physical
2092 In normal kdump cases one does not have to set/change this option
2093 as now bzImage can be compiled as a completely relocatable image
2094 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2095 address. This option is mainly useful for the folks who don't want
2096 to use a bzImage for capturing the crash dump and want to use a
2097 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2098 to be specifically compiled to run from a specific memory area
2099 (normally a reserved region) and this option comes handy.
2101 So if you are using bzImage for capturing the crash dump,
2102 leave the value here unchanged to 0x1000000 and set
2103 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2104 for capturing the crash dump change this value to start of
2105 the reserved region. In other words, it can be set based on
2106 the "X" value as specified in the "crashkernel=YM@XM"
2107 command line boot parameter passed to the panic-ed
2108 kernel. Please take a look at Documentation/kdump/kdump.txt
2109 for more details about crash dumps.
2111 Usage of bzImage for capturing the crash dump is recommended as
2112 one does not have to build two kernels. Same kernel can be used
2113 as production kernel and capture kernel. Above option should have
2114 gone away after relocatable bzImage support is introduced. But it
2115 is present because there are users out there who continue to use
2116 vmlinux for dump capture. This option should go away down the
2119 Don't change this unless you know what you are doing.
2122 bool "Build a relocatable kernel"
2125 This builds a kernel image that retains relocation information
2126 so it can be loaded someplace besides the default 1MB.
2127 The relocations tend to make the kernel binary about 10% larger,
2128 but are discarded at runtime.
2130 One use is for the kexec on panic case where the recovery kernel
2131 must live at a different physical address than the primary
2134 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2135 it has been loaded at and the compile time physical address
2136 (CONFIG_PHYSICAL_START) is used as the minimum location.
2138 config RANDOMIZE_BASE
2139 bool "Randomize the address of the kernel image (KASLR)"
2140 depends on RELOCATABLE
2143 In support of Kernel Address Space Layout Randomization (KASLR),
2144 this randomizes the physical address at which the kernel image
2145 is decompressed and the virtual address where the kernel
2146 image is mapped, as a security feature that deters exploit
2147 attempts relying on knowledge of the location of kernel
2150 On 64-bit, the kernel physical and virtual addresses are
2151 randomized separately. The physical address will be anywhere
2152 between 16MB and the top of physical memory (up to 64TB). The
2153 virtual address will be randomized from 16MB up to 1GB (9 bits
2154 of entropy). Note that this also reduces the memory space
2155 available to kernel modules from 1.5GB to 1GB.
2157 On 32-bit, the kernel physical and virtual addresses are
2158 randomized together. They will be randomized from 16MB up to
2159 512MB (8 bits of entropy).
2161 Entropy is generated using the RDRAND instruction if it is
2162 supported. If RDTSC is supported, its value is mixed into
2163 the entropy pool as well. If neither RDRAND nor RDTSC are
2164 supported, then entropy is read from the i8254 timer. The
2165 usable entropy is limited by the kernel being built using
2166 2GB addressing, and that PHYSICAL_ALIGN must be at a
2167 minimum of 2MB. As a result, only 10 bits of entropy are
2168 theoretically possible, but the implementations are further
2169 limited due to memory layouts.
2173 # Relocation on x86 needs some additional build support
2174 config X86_NEED_RELOCS
2176 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2178 config PHYSICAL_ALIGN
2179 hex "Alignment value to which kernel should be aligned"
2181 range 0x2000 0x1000000 if X86_32
2182 range 0x200000 0x1000000 if X86_64
2184 This value puts the alignment restrictions on physical address
2185 where kernel is loaded and run from. Kernel is compiled for an
2186 address which meets above alignment restriction.
2188 If bootloader loads the kernel at a non-aligned address and
2189 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2190 address aligned to above value and run from there.
2192 If bootloader loads the kernel at a non-aligned address and
2193 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2194 load address and decompress itself to the address it has been
2195 compiled for and run from there. The address for which kernel is
2196 compiled already meets above alignment restrictions. Hence the
2197 end result is that kernel runs from a physical address meeting
2198 above alignment restrictions.
2200 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2201 this value must be a multiple of 0x200000.
2203 Don't change this unless you know what you are doing.
2205 config DYNAMIC_MEMORY_LAYOUT
2208 This option makes base addresses of vmalloc and vmemmap as well as
2209 __PAGE_OFFSET movable during boot.
2211 config RANDOMIZE_MEMORY
2212 bool "Randomize the kernel memory sections"
2214 depends on RANDOMIZE_BASE
2215 select DYNAMIC_MEMORY_LAYOUT
2216 default RANDOMIZE_BASE
2218 Randomizes the base virtual address of kernel memory sections
2219 (physical memory mapping, vmalloc & vmemmap). This security feature
2220 makes exploits relying on predictable memory locations less reliable.
2222 The order of allocations remains unchanged. Entropy is generated in
2223 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2224 configuration have in average 30,000 different possible virtual
2225 addresses for each memory section.
2229 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2230 hex "Physical memory mapping padding" if EXPERT
2231 depends on RANDOMIZE_MEMORY
2232 default "0xa" if MEMORY_HOTPLUG
2234 range 0x1 0x40 if MEMORY_HOTPLUG
2237 Define the padding in terabytes added to the existing physical
2238 memory size during kernel memory randomization. It is useful
2239 for memory hotplug support but reduces the entropy available for
2240 address randomization.
2242 If unsure, leave at the default value.
2248 config BOOTPARAM_HOTPLUG_CPU0
2249 bool "Set default setting of cpu0_hotpluggable"
2251 depends on HOTPLUG_CPU
2253 Set whether default state of cpu0_hotpluggable is on or off.
2255 Say Y here to enable CPU0 hotplug by default. If this switch
2256 is turned on, there is no need to give cpu0_hotplug kernel
2257 parameter and the CPU0 hotplug feature is enabled by default.
2259 Please note: there are two known CPU0 dependencies if you want
2260 to enable the CPU0 hotplug feature either by this switch or by
2261 cpu0_hotplug kernel parameter.
2263 First, resume from hibernate or suspend always starts from CPU0.
2264 So hibernate and suspend are prevented if CPU0 is offline.
2266 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2267 offline if any interrupt can not migrate out of CPU0. There may
2268 be other CPU0 dependencies.
2270 Please make sure the dependencies are under your control before
2271 you enable this feature.
2273 Say N if you don't want to enable CPU0 hotplug feature by default.
2274 You still can enable the CPU0 hotplug feature at boot by kernel
2275 parameter cpu0_hotplug.
2277 config DEBUG_HOTPLUG_CPU0
2279 prompt "Debug CPU0 hotplug"
2280 depends on HOTPLUG_CPU
2282 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2283 soon as possible and boots up userspace with CPU0 offlined. User
2284 can online CPU0 back after boot time.
2286 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2287 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2288 compilation or giving cpu0_hotplug kernel parameter at boot.
2294 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2295 depends on COMPAT_32
2297 Certain buggy versions of glibc will crash if they are
2298 presented with a 32-bit vDSO that is not mapped at the address
2299 indicated in its segment table.
2301 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2302 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2303 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2304 the only released version with the bug, but OpenSUSE 9
2305 contains a buggy "glibc 2.3.2".
2307 The symptom of the bug is that everything crashes on startup, saying:
2308 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2310 Saying Y here changes the default value of the vdso32 boot
2311 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2312 This works around the glibc bug but hurts performance.
2314 If unsure, say N: if you are compiling your own kernel, you
2315 are unlikely to be using a buggy version of glibc.
2318 prompt "vsyscall table for legacy applications"
2320 default LEGACY_VSYSCALL_EMULATE
2322 Legacy user code that does not know how to find the vDSO expects
2323 to be able to issue three syscalls by calling fixed addresses in
2324 kernel space. Since this location is not randomized with ASLR,
2325 it can be used to assist security vulnerability exploitation.
2327 This setting can be changed at boot time via the kernel command
2328 line parameter vsyscall=[emulate|none].
2330 On a system with recent enough glibc (2.14 or newer) and no
2331 static binaries, you can say None without a performance penalty
2332 to improve security.
2334 If unsure, select "Emulate".
2336 config LEGACY_VSYSCALL_EMULATE
2339 The kernel traps and emulates calls into the fixed
2340 vsyscall address mapping. This makes the mapping
2341 non-executable, but it still contains known contents,
2342 which could be used in certain rare security vulnerability
2343 exploits. This configuration is recommended when userspace
2344 still uses the vsyscall area.
2346 config LEGACY_VSYSCALL_NONE
2349 There will be no vsyscall mapping at all. This will
2350 eliminate any risk of ASLR bypass due to the vsyscall
2351 fixed address mapping. Attempts to use the vsyscalls
2352 will be reported to dmesg, so that either old or
2353 malicious userspace programs can be identified.
2358 bool "Built-in kernel command line"
2360 Allow for specifying boot arguments to the kernel at
2361 build time. On some systems (e.g. embedded ones), it is
2362 necessary or convenient to provide some or all of the
2363 kernel boot arguments with the kernel itself (that is,
2364 to not rely on the boot loader to provide them.)
2366 To compile command line arguments into the kernel,
2367 set this option to 'Y', then fill in the
2368 boot arguments in CONFIG_CMDLINE.
2370 Systems with fully functional boot loaders (i.e. non-embedded)
2371 should leave this option set to 'N'.
2374 string "Built-in kernel command string"
2375 depends on CMDLINE_BOOL
2378 Enter arguments here that should be compiled into the kernel
2379 image and used at boot time. If the boot loader provides a
2380 command line at boot time, it is appended to this string to
2381 form the full kernel command line, when the system boots.
2383 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2384 change this behavior.
2386 In most cases, the command line (whether built-in or provided
2387 by the boot loader) should specify the device for the root
2390 config CMDLINE_OVERRIDE
2391 bool "Built-in command line overrides boot loader arguments"
2392 depends on CMDLINE_BOOL
2394 Set this option to 'Y' to have the kernel ignore the boot loader
2395 command line, and use ONLY the built-in command line.
2397 This is used to work around broken boot loaders. This should
2398 be set to 'N' under normal conditions.
2400 config MODIFY_LDT_SYSCALL
2401 bool "Enable the LDT (local descriptor table)" if EXPERT
2404 Linux can allow user programs to install a per-process x86
2405 Local Descriptor Table (LDT) using the modify_ldt(2) system
2406 call. This is required to run 16-bit or segmented code such as
2407 DOSEMU or some Wine programs. It is also used by some very old
2408 threading libraries.
2410 Enabling this feature adds a small amount of overhead to
2411 context switches and increases the low-level kernel attack
2412 surface. Disabling it removes the modify_ldt(2) system call.
2414 Saying 'N' here may make sense for embedded or server kernels.
2416 source "kernel/livepatch/Kconfig"
2420 config ARCH_HAS_ADD_PAGES
2422 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2424 config ARCH_ENABLE_MEMORY_HOTPLUG
2426 depends on X86_64 || (X86_32 && HIGHMEM)
2428 config ARCH_ENABLE_MEMORY_HOTREMOVE
2430 depends on MEMORY_HOTPLUG
2432 config USE_PERCPU_NUMA_NODE_ID
2436 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2438 depends on X86_64 || X86_PAE
2440 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2442 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2444 config ARCH_ENABLE_THP_MIGRATION
2446 depends on X86_64 && TRANSPARENT_HUGEPAGE
2448 menu "Power management and ACPI options"
2450 config ARCH_HIBERNATION_HEADER
2452 depends on X86_64 && HIBERNATION
2454 source "kernel/power/Kconfig"
2456 source "drivers/acpi/Kconfig"
2458 source "drivers/sfi/Kconfig"
2465 tristate "APM (Advanced Power Management) BIOS support"
2466 depends on X86_32 && PM_SLEEP
2468 APM is a BIOS specification for saving power using several different
2469 techniques. This is mostly useful for battery powered laptops with
2470 APM compliant BIOSes. If you say Y here, the system time will be
2471 reset after a RESUME operation, the /proc/apm device will provide
2472 battery status information, and user-space programs will receive
2473 notification of APM "events" (e.g. battery status change).
2475 If you select "Y" here, you can disable actual use of the APM
2476 BIOS by passing the "apm=off" option to the kernel at boot time.
2478 Note that the APM support is almost completely disabled for
2479 machines with more than one CPU.
2481 In order to use APM, you will need supporting software. For location
2482 and more information, read <file:Documentation/power/apm-acpi.txt>
2483 and the Battery Powered Linux mini-HOWTO, available from
2484 <http://www.tldp.org/docs.html#howto>.
2486 This driver does not spin down disk drives (see the hdparm(8)
2487 manpage ("man 8 hdparm") for that), and it doesn't turn off
2488 VESA-compliant "green" monitors.
2490 This driver does not support the TI 4000M TravelMate and the ACER
2491 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2492 desktop machines also don't have compliant BIOSes, and this driver
2493 may cause those machines to panic during the boot phase.
2495 Generally, if you don't have a battery in your machine, there isn't
2496 much point in using this driver and you should say N. If you get
2497 random kernel OOPSes or reboots that don't seem to be related to
2498 anything, try disabling/enabling this option (or disabling/enabling
2501 Some other things you should try when experiencing seemingly random,
2504 1) make sure that you have enough swap space and that it is
2506 2) pass the "no-hlt" option to the kernel
2507 3) switch on floating point emulation in the kernel and pass
2508 the "no387" option to the kernel
2509 4) pass the "floppy=nodma" option to the kernel
2510 5) pass the "mem=4M" option to the kernel (thereby disabling
2511 all but the first 4 MB of RAM)
2512 6) make sure that the CPU is not over clocked.
2513 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2514 8) disable the cache from your BIOS settings
2515 9) install a fan for the video card or exchange video RAM
2516 10) install a better fan for the CPU
2517 11) exchange RAM chips
2518 12) exchange the motherboard.
2520 To compile this driver as a module, choose M here: the
2521 module will be called apm.
2525 config APM_IGNORE_USER_SUSPEND
2526 bool "Ignore USER SUSPEND"
2528 This option will ignore USER SUSPEND requests. On machines with a
2529 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2530 series notebooks, it is necessary to say Y because of a BIOS bug.
2532 config APM_DO_ENABLE
2533 bool "Enable PM at boot time"
2535 Enable APM features at boot time. From page 36 of the APM BIOS
2536 specification: "When disabled, the APM BIOS does not automatically
2537 power manage devices, enter the Standby State, enter the Suspend
2538 State, or take power saving steps in response to CPU Idle calls."
2539 This driver will make CPU Idle calls when Linux is idle (unless this
2540 feature is turned off -- see "Do CPU IDLE calls", below). This
2541 should always save battery power, but more complicated APM features
2542 will be dependent on your BIOS implementation. You may need to turn
2543 this option off if your computer hangs at boot time when using APM
2544 support, or if it beeps continuously instead of suspending. Turn
2545 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2546 T400CDT. This is off by default since most machines do fine without
2551 bool "Make CPU Idle calls when idle"
2553 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2554 On some machines, this can activate improved power savings, such as
2555 a slowed CPU clock rate, when the machine is idle. These idle calls
2556 are made after the idle loop has run for some length of time (e.g.,
2557 333 mS). On some machines, this will cause a hang at boot time or
2558 whenever the CPU becomes idle. (On machines with more than one CPU,
2559 this option does nothing.)
2561 config APM_DISPLAY_BLANK
2562 bool "Enable console blanking using APM"
2564 Enable console blanking using the APM. Some laptops can use this to
2565 turn off the LCD backlight when the screen blanker of the Linux
2566 virtual console blanks the screen. Note that this is only used by
2567 the virtual console screen blanker, and won't turn off the backlight
2568 when using the X Window system. This also doesn't have anything to
2569 do with your VESA-compliant power-saving monitor. Further, this
2570 option doesn't work for all laptops -- it might not turn off your
2571 backlight at all, or it might print a lot of errors to the console,
2572 especially if you are using gpm.
2574 config APM_ALLOW_INTS
2575 bool "Allow interrupts during APM BIOS calls"
2577 Normally we disable external interrupts while we are making calls to
2578 the APM BIOS as a measure to lessen the effects of a badly behaving
2579 BIOS implementation. The BIOS should reenable interrupts if it
2580 needs to. Unfortunately, some BIOSes do not -- especially those in
2581 many of the newer IBM Thinkpads. If you experience hangs when you
2582 suspend, try setting this to Y. Otherwise, say N.
2586 source "drivers/cpufreq/Kconfig"
2588 source "drivers/cpuidle/Kconfig"
2590 source "drivers/idle/Kconfig"
2595 menu "Bus options (PCI etc.)"
2601 Find out whether you have a PCI motherboard. PCI is the name of a
2602 bus system, i.e. the way the CPU talks to the other stuff inside
2603 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2604 VESA. If you have PCI, say Y, otherwise N.
2607 prompt "PCI access mode"
2608 depends on X86_32 && PCI
2611 On PCI systems, the BIOS can be used to detect the PCI devices and
2612 determine their configuration. However, some old PCI motherboards
2613 have BIOS bugs and may crash if this is done. Also, some embedded
2614 PCI-based systems don't have any BIOS at all. Linux can also try to
2615 detect the PCI hardware directly without using the BIOS.
2617 With this option, you can specify how Linux should detect the
2618 PCI devices. If you choose "BIOS", the BIOS will be used,
2619 if you choose "Direct", the BIOS won't be used, and if you
2620 choose "MMConfig", then PCI Express MMCONFIG will be used.
2621 If you choose "Any", the kernel will try MMCONFIG, then the
2622 direct access method and falls back to the BIOS if that doesn't
2623 work. If unsure, go with the default, which is "Any".
2628 config PCI_GOMMCONFIG
2645 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2647 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2650 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2653 bool "Support mmconfig PCI config space access" if X86_64
2655 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2656 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2660 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2664 depends on PCI && XEN
2671 config MMCONF_FAM10H
2673 depends on X86_64 && PCI_MMCONFIG && ACPI
2675 config PCI_CNB20LE_QUIRK
2676 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2679 Read the PCI windows out of the CNB20LE host bridge. This allows
2680 PCI hotplug to work on systems with the CNB20LE chipset which do
2683 There's no public spec for this chipset, and this functionality
2684 is known to be incomplete.
2686 You should say N unless you know you need this.
2688 source "drivers/pci/Kconfig"
2691 bool "ISA bus support on modern systems" if EXPERT
2693 Expose ISA bus device drivers and options available for selection and
2694 configuration. Enable this option if your target machine has an ISA
2695 bus. ISA is an older system, displaced by PCI and newer bus
2696 architectures -- if your target machine is modern, it probably does
2697 not have an ISA bus.
2701 # x86_64 have no ISA slots, but can have ISA-style DMA.
2703 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2706 Enables ISA-style DMA support for devices requiring such controllers.
2714 Find out whether you have ISA slots on your motherboard. ISA is the
2715 name of a bus system, i.e. the way the CPU talks to the other stuff
2716 inside your box. Other bus systems are PCI, EISA, MicroChannel
2717 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2718 newer boards don't support it. If you have ISA, say Y, otherwise N.
2724 The Extended Industry Standard Architecture (EISA) bus was
2725 developed as an open alternative to the IBM MicroChannel bus.
2727 The EISA bus provided some of the features of the IBM MicroChannel
2728 bus while maintaining backward compatibility with cards made for
2729 the older ISA bus. The EISA bus saw limited use between 1988 and
2730 1995 when it was made obsolete by the PCI bus.
2732 Say Y here if you are building a kernel for an EISA-based machine.
2736 source "drivers/eisa/Kconfig"
2739 tristate "NatSemi SCx200 support"
2741 This provides basic support for National Semiconductor's
2742 (now AMD's) Geode processors. The driver probes for the
2743 PCI-IDs of several on-chip devices, so its a good dependency
2744 for other scx200_* drivers.
2746 If compiled as a module, the driver is named scx200.
2748 config SCx200HR_TIMER
2749 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2753 This driver provides a clocksource built upon the on-chip
2754 27MHz high-resolution timer. Its also a workaround for
2755 NSC Geode SC-1100's buggy TSC, which loses time when the
2756 processor goes idle (as is done by the scheduler). The
2757 other workaround is idle=poll boot option.
2760 bool "One Laptop Per Child support"
2767 Add support for detecting the unique features of the OLPC
2771 bool "OLPC XO-1 Power Management"
2772 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2774 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2777 bool "OLPC XO-1 Real Time Clock"
2778 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2780 Add support for the XO-1 real time clock, which can be used as a
2781 programmable wakeup source.
2784 bool "OLPC XO-1 SCI extras"
2785 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2789 Add support for SCI-based features of the OLPC XO-1 laptop:
2790 - EC-driven system wakeups
2794 - AC adapter status updates
2795 - Battery status updates
2797 config OLPC_XO15_SCI
2798 bool "OLPC XO-1.5 SCI extras"
2799 depends on OLPC && ACPI
2802 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2803 - EC-driven system wakeups
2804 - AC adapter status updates
2805 - Battery status updates
2808 bool "PCEngines ALIX System Support (LED setup)"
2811 This option enables system support for the PCEngines ALIX.
2812 At present this just sets up LEDs for GPIO control on
2813 ALIX2/3/6 boards. However, other system specific setup should
2816 Note: You must still enable the drivers for GPIO and LED support
2817 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2819 Note: You have to set alix.force=1 for boards with Award BIOS.
2822 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2825 This option enables system support for the Soekris Engineering net5501.
2828 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2832 This option enables system support for the Traverse Technologies GEOS.
2835 bool "Technologic Systems TS-5500 platform support"
2837 select CHECK_SIGNATURE
2841 This option enables system support for the Technologic Systems TS-5500.
2847 depends on CPU_SUP_AMD && PCI
2849 source "drivers/pcmcia/Kconfig"
2852 tristate "RapidIO support"
2856 If enabled this option will include drivers and the core
2857 infrastructure code to support RapidIO interconnect devices.
2859 source "drivers/rapidio/Kconfig"
2862 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2864 Firmwares often provide initial graphics framebuffers so the BIOS,
2865 bootloader or kernel can show basic video-output during boot for
2866 user-guidance and debugging. Historically, x86 used the VESA BIOS
2867 Extensions and EFI-framebuffers for this, which are mostly limited
2869 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2870 framebuffers so the new generic system-framebuffer drivers can be
2871 used on x86. If the framebuffer is not compatible with the generic
2872 modes, it is advertised as fallback platform framebuffer so legacy
2873 drivers like efifb, vesafb and uvesafb can pick it up.
2874 If this option is not selected, all system framebuffers are always
2875 marked as fallback platform framebuffers as usual.
2877 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2878 not be able to pick up generic system framebuffers if this option
2879 is selected. You are highly encouraged to enable simplefb as
2880 replacement if you select this option. simplefb can correctly deal
2881 with generic system framebuffers. But you should still keep vesafb
2882 and others enabled as fallback if a system framebuffer is
2883 incompatible with simplefb.
2890 menu "Binary Emulations"
2892 config IA32_EMULATION
2893 bool "IA32 Emulation"
2895 select ARCH_WANT_OLD_COMPAT_IPC
2897 select COMPAT_BINFMT_ELF
2898 select COMPAT_OLD_SIGACTION
2900 Include code to run legacy 32-bit programs under a
2901 64-bit kernel. You should likely turn this on, unless you're
2902 100% sure that you don't have any 32-bit programs left.
2905 tristate "IA32 a.out support"
2906 depends on IA32_EMULATION
2908 Support old a.out binaries in the 32bit emulation.
2911 bool "x32 ABI for 64-bit mode"
2914 Include code to run binaries for the x32 native 32-bit ABI
2915 for 64-bit processors. An x32 process gets access to the
2916 full 64-bit register file and wide data path while leaving
2917 pointers at 32 bits for smaller memory footprint.
2919 You will need a recent binutils (2.22 or later) with
2920 elf32_x86_64 support enabled to compile a kernel with this
2925 depends on IA32_EMULATION || X86_32
2927 select OLD_SIGSUSPEND3
2931 depends on IA32_EMULATION || X86_X32
2934 config COMPAT_FOR_U64_ALIGNMENT
2937 config SYSVIPC_COMPAT
2945 config HAVE_ATOMIC_IOMAP
2949 config X86_DEV_DMA_OPS
2951 depends on X86_64 || STA2X11
2953 config X86_DMA_REMAP
2957 config HAVE_GENERIC_GUP
2960 source "drivers/firmware/Kconfig"
2962 source "arch/x86/kvm/Kconfig"