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_CLOCKSOURCE_INIT
52 select ARCH_DISCARD_MEMBLOCK
53 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
54 select ARCH_HAS_DEBUG_VIRTUAL
55 select ARCH_HAS_DEVMEM_IS_ALLOWED
56 select ARCH_HAS_ELF_RANDOMIZE
57 select ARCH_HAS_FAST_MULTIPLIER
58 select ARCH_HAS_FILTER_PGPROT
59 select ARCH_HAS_FORTIFY_SOURCE
60 select ARCH_HAS_GCOV_PROFILE_ALL
61 select ARCH_HAS_KCOV if X86_64
62 select ARCH_HAS_MEMBARRIER_SYNC_CORE
63 select ARCH_HAS_PMEM_API if X86_64
64 select ARCH_HAS_PTE_SPECIAL
65 select ARCH_HAS_REFCOUNT
66 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
67 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
68 select ARCH_HAS_SET_MEMORY
69 select ARCH_HAS_SG_CHAIN
70 select ARCH_HAS_STRICT_KERNEL_RWX
71 select ARCH_HAS_STRICT_MODULE_RWX
72 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
73 select ARCH_HAS_UBSAN_SANITIZE_ALL
74 select ARCH_HAS_ZONE_DEVICE if X86_64
75 select ARCH_HAVE_NMI_SAFE_CMPXCHG
76 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
77 select ARCH_MIGHT_HAVE_PC_PARPORT
78 select ARCH_MIGHT_HAVE_PC_SERIO
79 select ARCH_SUPPORTS_ACPI
80 select ARCH_SUPPORTS_ATOMIC_RMW
81 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
82 select ARCH_USE_BUILTIN_BSWAP
83 select ARCH_USE_QUEUED_RWLOCKS
84 select ARCH_USE_QUEUED_SPINLOCKS
85 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
86 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
87 select ARCH_WANTS_THP_SWAP if X86_64
88 select BUILDTIME_EXTABLE_SORT
90 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
91 select CLOCKSOURCE_WATCHDOG
92 select DCACHE_WORD_ACCESS
94 select EDAC_ATOMIC_SCRUB
96 select GENERIC_CLOCKEVENTS
97 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
98 select GENERIC_CLOCKEVENTS_MIN_ADJUST
99 select GENERIC_CMOS_UPDATE
100 select GENERIC_CPU_AUTOPROBE
101 select GENERIC_CPU_VULNERABILITIES
102 select GENERIC_EARLY_IOREMAP
103 select GENERIC_FIND_FIRST_BIT
105 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
106 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
107 select GENERIC_IRQ_MIGRATION if SMP
108 select GENERIC_IRQ_PROBE
109 select GENERIC_IRQ_RESERVATION_MODE
110 select GENERIC_IRQ_SHOW
111 select GENERIC_PENDING_IRQ if SMP
112 select GENERIC_SMP_IDLE_THREAD
113 select GENERIC_STRNCPY_FROM_USER
114 select GENERIC_STRNLEN_USER
115 select GENERIC_TIME_VSYSCALL
116 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
117 select HAVE_ACPI_APEI if ACPI
118 select HAVE_ACPI_APEI_NMI if ACPI
119 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
120 select HAVE_ARCH_AUDITSYSCALL
121 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
122 select HAVE_ARCH_JUMP_LABEL
123 select HAVE_ARCH_JUMP_LABEL_RELATIVE
124 select HAVE_ARCH_KASAN if X86_64
125 select HAVE_ARCH_KGDB
126 select HAVE_ARCH_MMAP_RND_BITS if MMU
127 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
128 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
129 select HAVE_ARCH_PREL32_RELOCATIONS
130 select HAVE_ARCH_SECCOMP_FILTER
131 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
132 select HAVE_ARCH_STACKLEAK
133 select HAVE_ARCH_TRACEHOOK
134 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
135 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
136 select HAVE_ARCH_VMAP_STACK if X86_64
137 select HAVE_ARCH_WITHIN_STACK_FRAMES
138 select HAVE_CMPXCHG_DOUBLE
139 select HAVE_CMPXCHG_LOCAL
140 select HAVE_CONTEXT_TRACKING if X86_64
141 select HAVE_COPY_THREAD_TLS
142 select HAVE_C_RECORDMCOUNT
143 select HAVE_DEBUG_KMEMLEAK
144 select HAVE_DEBUG_STACKOVERFLOW
145 select HAVE_DMA_CONTIGUOUS
146 select HAVE_DYNAMIC_FTRACE
147 select HAVE_DYNAMIC_FTRACE_WITH_REGS
149 select HAVE_EFFICIENT_UNALIGNED_ACCESS
150 select HAVE_EXIT_THREAD
151 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
152 select HAVE_FTRACE_MCOUNT_RECORD
153 select HAVE_FUNCTION_GRAPH_TRACER
154 select HAVE_FUNCTION_TRACER
155 select HAVE_GCC_PLUGINS
156 select HAVE_HW_BREAKPOINT
158 select HAVE_IOREMAP_PROT
159 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
160 select HAVE_IRQ_TIME_ACCOUNTING
161 select HAVE_KERNEL_BZIP2
162 select HAVE_KERNEL_GZIP
163 select HAVE_KERNEL_LZ4
164 select HAVE_KERNEL_LZMA
165 select HAVE_KERNEL_LZO
166 select HAVE_KERNEL_XZ
168 select HAVE_KPROBES_ON_FTRACE
169 select HAVE_FUNCTION_ERROR_INJECTION
170 select HAVE_KRETPROBES
172 select HAVE_LIVEPATCH if X86_64
173 select HAVE_MEMBLOCK_NODE_MAP
174 select HAVE_MIXED_BREAKPOINTS_REGS
175 select HAVE_MOD_ARCH_SPECIFIC
178 select HAVE_OPTPROBES
179 select HAVE_PCSPKR_PLATFORM
180 select HAVE_PERF_EVENTS
181 select HAVE_PERF_EVENTS_NMI
182 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
183 select HAVE_PERF_REGS
184 select HAVE_PERF_USER_STACK_DUMP
185 select HAVE_RCU_TABLE_FREE if PARAVIRT
186 select HAVE_RCU_TABLE_INVALIDATE if HAVE_RCU_TABLE_FREE
187 select HAVE_REGS_AND_STACK_ACCESS_API
188 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
189 select HAVE_FUNCTION_ARG_ACCESS_API
190 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
191 select HAVE_STACK_VALIDATION if X86_64
193 select HAVE_SYSCALL_TRACEPOINTS
194 select HAVE_UNSTABLE_SCHED_CLOCK
195 select HAVE_USER_RETURN_NOTIFIER
196 select HOTPLUG_SMT if SMP
197 select IRQ_FORCED_THREADING
198 select NEED_SG_DMA_LENGTH
199 select PCI_LOCKLESS_CONFIG
202 select RTC_MC146818_LIB
205 select SYSCTL_EXCEPTION_TRACE
206 select THREAD_INFO_IN_TASK
207 select USER_STACKTRACE_SUPPORT
209 select X86_FEATURE_NAMES if PROC_FS
211 config INSTRUCTION_DECODER
213 depends on KPROBES || PERF_EVENTS || UPROBES
217 default "elf32-i386" if X86_32
218 default "elf64-x86-64" if X86_64
220 config ARCH_DEFCONFIG
222 default "arch/x86/configs/i386_defconfig" if X86_32
223 default "arch/x86/configs/x86_64_defconfig" if X86_64
225 config LOCKDEP_SUPPORT
228 config STACKTRACE_SUPPORT
234 config ARCH_MMAP_RND_BITS_MIN
238 config ARCH_MMAP_RND_BITS_MAX
242 config ARCH_MMAP_RND_COMPAT_BITS_MIN
245 config ARCH_MMAP_RND_COMPAT_BITS_MAX
251 config GENERIC_ISA_DMA
253 depends on ISA_DMA_API
258 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
260 config GENERIC_BUG_RELATIVE_POINTERS
263 config GENERIC_HWEIGHT
266 config ARCH_MAY_HAVE_PC_FDC
268 depends on ISA_DMA_API
270 config RWSEM_XCHGADD_ALGORITHM
273 config GENERIC_CALIBRATE_DELAY
276 config ARCH_HAS_CPU_RELAX
279 config ARCH_HAS_CACHE_LINE_SIZE
282 config ARCH_HAS_FILTER_PGPROT
285 config HAVE_SETUP_PER_CPU_AREA
288 config NEED_PER_CPU_EMBED_FIRST_CHUNK
291 config NEED_PER_CPU_PAGE_FIRST_CHUNK
294 config ARCH_HIBERNATION_POSSIBLE
297 config ARCH_SUSPEND_POSSIBLE
300 config ARCH_WANT_HUGE_PMD_SHARE
303 config ARCH_WANT_GENERAL_HUGETLB
312 config ARCH_SUPPORTS_OPTIMIZED_INLINING
315 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
318 config KASAN_SHADOW_OFFSET
321 default 0xdffffc0000000000
323 config HAVE_INTEL_TXT
325 depends on INTEL_IOMMU && ACPI
329 depends on X86_32 && SMP
333 depends on X86_64 && SMP
335 config X86_32_LAZY_GS
337 depends on X86_32 && !STACKPROTECTOR
339 config ARCH_SUPPORTS_UPROBES
342 config FIX_EARLYCON_MEM
345 config DYNAMIC_PHYSICAL_MASK
348 config PGTABLE_LEVELS
350 default 5 if X86_5LEVEL
355 config CC_HAS_SANE_STACKPROTECTOR
357 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
358 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
360 We have to make sure stack protector is unconditionally disabled if
361 the compiler produces broken code.
363 menu "Processor type and features"
366 bool "DMA memory allocation support" if EXPERT
369 DMA memory allocation support allows devices with less than 32-bit
370 addressing to allocate within the first 16MB of address space.
371 Disable if no such devices will be used.
376 bool "Symmetric multi-processing support"
378 This enables support for systems with more than one CPU. If you have
379 a system with only one CPU, say N. If you have a system with more
382 If you say N here, the kernel will run on uni- and multiprocessor
383 machines, but will use only one CPU of a multiprocessor machine. If
384 you say Y here, the kernel will run on many, but not all,
385 uniprocessor machines. On a uniprocessor machine, the kernel
386 will run faster if you say N here.
388 Note that if you say Y here and choose architecture "586" or
389 "Pentium" under "Processor family", the kernel will not work on 486
390 architectures. Similarly, multiprocessor kernels for the "PPro"
391 architecture may not work on all Pentium based boards.
393 People using multiprocessor machines who say Y here should also say
394 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
395 Management" code will be disabled if you say Y here.
397 See also <file:Documentation/x86/i386/IO-APIC.txt>,
398 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
399 <http://www.tldp.org/docs.html#howto>.
401 If you don't know what to do here, say N.
403 config X86_FEATURE_NAMES
404 bool "Processor feature human-readable names" if EMBEDDED
407 This option compiles in a table of x86 feature bits and corresponding
408 names. This is required to support /proc/cpuinfo and a few kernel
409 messages. You can disable this to save space, at the expense of
410 making those few kernel messages show numeric feature bits instead.
415 bool "Support x2apic"
416 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
418 This enables x2apic support on CPUs that have this feature.
420 This allows 32-bit apic IDs (so it can support very large systems),
421 and accesses the local apic via MSRs not via mmio.
423 If you don't know what to do here, say N.
426 bool "Enable MPS table" if ACPI || SFI
428 depends on X86_LOCAL_APIC
430 For old smp systems that do not have proper acpi support. Newer systems
431 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
435 depends on X86_GOLDFISH
438 bool "Avoid speculative indirect branches in kernel"
440 select STACK_VALIDATION if HAVE_STACK_VALIDATION
442 Compile kernel with the retpoline compiler options to guard against
443 kernel-to-user data leaks by avoiding speculative indirect
444 branches. Requires a compiler with -mindirect-branch=thunk-extern
445 support for full protection. The kernel may run slower.
447 Without compiler support, at least indirect branches in assembler
448 code are eliminated. Since this includes the syscall entry path,
449 it is not entirely pointless.
452 bool "Intel Resource Director Technology support"
453 depends on X86 && CPU_SUP_INTEL
456 Select to enable resource allocation and monitoring which are
457 sub-features of Intel Resource Director Technology(RDT). More
458 information about RDT can be found in the Intel x86
459 Architecture Software Developer Manual.
465 bool "Support for big SMP systems with more than 8 CPUs"
468 This option is needed for the systems that have more than 8 CPUs
470 config X86_EXTENDED_PLATFORM
471 bool "Support for extended (non-PC) x86 platforms"
474 If you disable this option then the kernel will only support
475 standard PC platforms. (which covers the vast majority of
478 If you enable this option then you'll be able to select support
479 for the following (non-PC) 32 bit x86 platforms:
480 Goldfish (Android emulator)
483 SGI 320/540 (Visual Workstation)
484 STA2X11-based (e.g. Northville)
485 Moorestown MID devices
487 If you have one of these systems, or if you want to build a
488 generic distribution kernel, say Y here - otherwise say N.
492 config X86_EXTENDED_PLATFORM
493 bool "Support for extended (non-PC) x86 platforms"
496 If you disable this option then the kernel will only support
497 standard PC platforms. (which covers the vast majority of
500 If you enable this option then you'll be able to select support
501 for the following (non-PC) 64 bit x86 platforms:
506 If you have one of these systems, or if you want to build a
507 generic distribution kernel, say Y here - otherwise say N.
509 # This is an alphabetically sorted list of 64 bit extended platforms
510 # Please maintain the alphabetic order if and when there are additions
512 bool "Numascale NumaChip"
514 depends on X86_EXTENDED_PLATFORM
517 depends on X86_X2APIC
518 depends on PCI_MMCONFIG
520 Adds support for Numascale NumaChip large-SMP systems. Needed to
521 enable more than ~168 cores.
522 If you don't have one of these, you should say N here.
526 select HYPERVISOR_GUEST
529 depends on X86_64 && PCI
530 depends on X86_EXTENDED_PLATFORM
533 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
534 supposed to run on these EM64T-based machines. Only choose this option
535 if you have one of these machines.
538 bool "SGI Ultraviolet"
540 depends on X86_EXTENDED_PLATFORM
543 depends on X86_X2APIC
546 This option is needed in order to support SGI Ultraviolet systems.
547 If you don't have one of these, you should say N here.
549 # Following is an alphabetically sorted list of 32 bit extended platforms
550 # Please maintain the alphabetic order if and when there are additions
553 bool "Goldfish (Virtual Platform)"
554 depends on X86_EXTENDED_PLATFORM
556 Enable support for the Goldfish virtual platform used primarily
557 for Android development. Unless you are building for the Android
558 Goldfish emulator say N here.
561 bool "CE4100 TV platform"
563 depends on PCI_GODIRECT
564 depends on X86_IO_APIC
566 depends on X86_EXTENDED_PLATFORM
567 select X86_REBOOTFIXUPS
569 select OF_EARLY_FLATTREE
571 Select for the Intel CE media processor (CE4100) SOC.
572 This option compiles in support for the CE4100 SOC for settop
573 boxes and media devices.
576 bool "Intel MID platform support"
577 depends on X86_EXTENDED_PLATFORM
578 depends on X86_PLATFORM_DEVICES
580 depends on X86_64 || (PCI_GOANY && X86_32)
581 depends on X86_IO_APIC
587 select MFD_INTEL_MSIC
589 Select to build a kernel capable of supporting Intel MID (Mobile
590 Internet Device) platform systems which do not have the PCI legacy
591 interfaces. If you are building for a PC class system say N here.
593 Intel MID platforms are based on an Intel processor and chipset which
594 consume less power than most of the x86 derivatives.
596 config X86_INTEL_QUARK
597 bool "Intel Quark platform support"
599 depends on X86_EXTENDED_PLATFORM
600 depends on X86_PLATFORM_DEVICES
604 depends on X86_IO_APIC
609 Select to include support for Quark X1000 SoC.
610 Say Y here if you have a Quark based system such as the Arduino
611 compatible Intel Galileo.
613 config X86_INTEL_LPSS
614 bool "Intel Low Power Subsystem Support"
615 depends on X86 && ACPI
620 Select to build support for Intel Low Power Subsystem such as
621 found on Intel Lynxpoint PCH. Selecting this option enables
622 things like clock tree (common clock framework) and pincontrol
623 which are needed by the LPSS peripheral drivers.
625 config X86_AMD_PLATFORM_DEVICE
626 bool "AMD ACPI2Platform devices support"
631 Select to interpret AMD specific ACPI device to platform device
632 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
633 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
634 implemented under PINCTRL subsystem.
637 tristate "Intel SoC IOSF Sideband support for SoC platforms"
640 This option enables sideband register access support for Intel SoC
641 platforms. On these platforms the IOSF sideband is used in lieu of
642 MSR's for some register accesses, mostly but not limited to thermal
643 and power. Drivers may query the availability of this device to
644 determine if they need the sideband in order to work on these
645 platforms. The sideband is available on the following SoC products.
646 This list is not meant to be exclusive.
651 You should say Y if you are running a kernel on one of these SoC's.
653 config IOSF_MBI_DEBUG
654 bool "Enable IOSF sideband access through debugfs"
655 depends on IOSF_MBI && DEBUG_FS
657 Select this option to expose the IOSF sideband access registers (MCR,
658 MDR, MCRX) through debugfs to write and read register information from
659 different units on the SoC. This is most useful for obtaining device
660 state information for debug and analysis. As this is a general access
661 mechanism, users of this option would have specific knowledge of the
662 device they want to access.
664 If you don't require the option or are in doubt, say N.
667 bool "RDC R-321x SoC"
669 depends on X86_EXTENDED_PLATFORM
671 select X86_REBOOTFIXUPS
673 This option is needed for RDC R-321x system-on-chip, also known
675 If you don't have one of these chips, you should say N here.
677 config X86_32_NON_STANDARD
678 bool "Support non-standard 32-bit SMP architectures"
679 depends on X86_32 && SMP
680 depends on X86_EXTENDED_PLATFORM
682 This option compiles in the bigsmp and STA2X11 default
683 subarchitectures. It is intended for a generic binary
684 kernel. If you select them all, kernel will probe it one by
685 one and will fallback to default.
687 # Alphabetically sorted list of Non standard 32 bit platforms
689 config X86_SUPPORTS_MEMORY_FAILURE
691 # MCE code calls memory_failure():
693 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
694 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
695 depends on X86_64 || !SPARSEMEM
696 select ARCH_SUPPORTS_MEMORY_FAILURE
699 bool "STA2X11 Companion Chip Support"
700 depends on X86_32_NON_STANDARD && PCI
701 select ARCH_HAS_PHYS_TO_DMA
702 select X86_DEV_DMA_OPS
708 This adds support for boards based on the STA2X11 IO-Hub,
709 a.k.a. "ConneXt". The chip is used in place of the standard
710 PC chipset, so all "standard" peripherals are missing. If this
711 option is selected the kernel will still be able to boot on
712 standard PC machines.
715 tristate "Eurobraille/Iris poweroff module"
718 The Iris machines from EuroBraille do not have APM or ACPI support
719 to shut themselves down properly. A special I/O sequence is
720 needed to do so, which is what this module does at
723 This is only for Iris machines from EuroBraille.
727 config SCHED_OMIT_FRAME_POINTER
729 prompt "Single-depth WCHAN output"
732 Calculate simpler /proc/<PID>/wchan values. If this option
733 is disabled then wchan values will recurse back to the
734 caller function. This provides more accurate wchan values,
735 at the expense of slightly more scheduling overhead.
737 If in doubt, say "Y".
739 menuconfig HYPERVISOR_GUEST
740 bool "Linux guest support"
742 Say Y here to enable options for running Linux under various hyper-
743 visors. This option enables basic hypervisor detection and platform
746 If you say N, all options in this submenu will be skipped and
747 disabled, and Linux guest support won't be built in.
752 bool "Enable paravirtualization code"
754 This changes the kernel so it can modify itself when it is run
755 under a hypervisor, potentially improving performance significantly
756 over full virtualization. However, when run without a hypervisor
757 the kernel is theoretically slower and slightly larger.
762 config PARAVIRT_DEBUG
763 bool "paravirt-ops debugging"
764 depends on PARAVIRT && DEBUG_KERNEL
766 Enable to debug paravirt_ops internals. Specifically, BUG if
767 a paravirt_op is missing when it is called.
769 config PARAVIRT_SPINLOCKS
770 bool "Paravirtualization layer for spinlocks"
771 depends on PARAVIRT && SMP
773 Paravirtualized spinlocks allow a pvops backend to replace the
774 spinlock implementation with something virtualization-friendly
775 (for example, block the virtual CPU rather than spinning).
777 It has a minimal impact on native kernels and gives a nice performance
778 benefit on paravirtualized KVM / Xen kernels.
780 If you are unsure how to answer this question, answer Y.
782 config QUEUED_LOCK_STAT
783 bool "Paravirt queued spinlock statistics"
784 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
786 Enable the collection of statistical data on the slowpath
787 behavior of paravirtualized queued spinlocks and report
790 source "arch/x86/xen/Kconfig"
793 bool "KVM Guest support (including kvmclock)"
795 select PARAVIRT_CLOCK
798 This option enables various optimizations for running under the KVM
799 hypervisor. It includes a paravirtualized clock, so that instead
800 of relying on a PIT (or probably other) emulation by the
801 underlying device model, the host provides the guest with
802 timing infrastructure such as time of day, and system time
805 bool "Enable debug information for KVM Guests in debugfs"
806 depends on KVM_GUEST && DEBUG_FS
808 This option enables collection of various statistics for KVM guest.
809 Statistics are displayed in debugfs filesystem. Enabling this option
810 may incur significant overhead.
812 config PARAVIRT_TIME_ACCOUNTING
813 bool "Paravirtual steal time accounting"
816 Select this option to enable fine granularity task steal time
817 accounting. Time spent executing other tasks in parallel with
818 the current vCPU is discounted from the vCPU power. To account for
819 that, there can be a small performance impact.
821 If in doubt, say N here.
823 config PARAVIRT_CLOCK
826 config JAILHOUSE_GUEST
827 bool "Jailhouse non-root cell support"
828 depends on X86_64 && PCI
831 This option allows to run Linux as guest in a Jailhouse non-root
832 cell. You can leave this option disabled if you only want to start
833 Jailhouse and run Linux afterwards in the root cell.
835 endif #HYPERVISOR_GUEST
837 source "arch/x86/Kconfig.cpu"
841 prompt "HPET Timer Support" if X86_32
843 Use the IA-PC HPET (High Precision Event Timer) to manage
844 time in preference to the PIT and RTC, if a HPET is
846 HPET is the next generation timer replacing legacy 8254s.
847 The HPET provides a stable time base on SMP
848 systems, unlike the TSC, but it is more expensive to access,
849 as it is off-chip. The interface used is documented
850 in the HPET spec, revision 1.
852 You can safely choose Y here. However, HPET will only be
853 activated if the platform and the BIOS support this feature.
854 Otherwise the 8254 will be used for timing services.
856 Choose N to continue using the legacy 8254 timer.
858 config HPET_EMULATE_RTC
860 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
863 def_bool y if X86_INTEL_MID
864 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
866 depends on X86_INTEL_MID && SFI
868 APB timer is the replacement for 8254, HPET on X86 MID platforms.
869 The APBT provides a stable time base on SMP
870 systems, unlike the TSC, but it is more expensive to access,
871 as it is off-chip. APB timers are always running regardless of CPU
872 C states, they are used as per CPU clockevent device when possible.
874 # Mark as expert because too many people got it wrong.
875 # The code disables itself when not needed.
878 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
879 bool "Enable DMI scanning" if EXPERT
881 Enabled scanning of DMI to identify machine quirks. Say Y
882 here unless you have verified that your setup is not
883 affected by entries in the DMI blacklist. Required by PNP
887 bool "Old AMD GART IOMMU support"
890 depends on X86_64 && PCI && AMD_NB
892 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
893 GART based hardware IOMMUs.
895 The GART supports full DMA access for devices with 32-bit access
896 limitations, on systems with more than 3 GB. This is usually needed
897 for USB, sound, many IDE/SATA chipsets and some other devices.
899 Newer systems typically have a modern AMD IOMMU, supported via
900 the CONFIG_AMD_IOMMU=y config option.
902 In normal configurations this driver is only active when needed:
903 there's more than 3 GB of memory and the system contains a
904 32-bit limited device.
909 bool "IBM Calgary IOMMU support"
912 depends on X86_64 && PCI
914 Support for hardware IOMMUs in IBM's xSeries x366 and x460
915 systems. Needed to run systems with more than 3GB of memory
916 properly with 32-bit PCI devices that do not support DAC
917 (Double Address Cycle). Calgary also supports bus level
918 isolation, where all DMAs pass through the IOMMU. This
919 prevents them from going anywhere except their intended
920 destination. This catches hard-to-find kernel bugs and
921 mis-behaving drivers and devices that do not use the DMA-API
922 properly to set up their DMA buffers. The IOMMU can be
923 turned off at boot time with the iommu=off parameter.
924 Normally the kernel will make the right choice by itself.
927 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
929 prompt "Should Calgary be enabled by default?"
930 depends on CALGARY_IOMMU
932 Should Calgary be enabled by default? if you choose 'y', Calgary
933 will be used (if it exists). If you choose 'n', Calgary will not be
934 used even if it exists. If you choose 'n' and would like to use
935 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
939 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
940 depends on X86_64 && SMP && DEBUG_KERNEL
941 select CPUMASK_OFFSTACK
943 Enable maximum number of CPUS and NUMA Nodes for this architecture.
947 # The maximum number of CPUs supported:
949 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
950 # and which can be configured interactively in the
951 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
953 # The ranges are different on 32-bit and 64-bit kernels, depending on
954 # hardware capabilities and scalability features of the kernel.
956 # ( If MAXSMP is enabled we just use the highest possible value and disable
957 # interactive configuration. )
960 config NR_CPUS_RANGE_BEGIN
962 default NR_CPUS_RANGE_END if MAXSMP
966 config NR_CPUS_RANGE_END
969 default 64 if SMP && X86_BIGSMP
970 default 8 if SMP && !X86_BIGSMP
973 config NR_CPUS_RANGE_END
976 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
977 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
980 config NR_CPUS_DEFAULT
983 default 32 if X86_BIGSMP
987 config NR_CPUS_DEFAULT
990 default 8192 if MAXSMP
995 int "Maximum number of CPUs" if SMP && !MAXSMP
996 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
997 default NR_CPUS_DEFAULT
999 This allows you to specify the maximum number of CPUs which this
1000 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1001 supported value is 8192, otherwise the maximum value is 512. The
1002 minimum value which makes sense is 2.
1004 This is purely to save memory: each supported CPU adds about 8KB
1005 to the kernel image.
1008 bool "SMT (Hyperthreading) scheduler support"
1011 SMT scheduler support improves the CPU scheduler's decision making
1012 when dealing with Intel Pentium 4 chips with HyperThreading at a
1013 cost of slightly increased overhead in some places. If unsure say
1018 prompt "Multi-core scheduler support"
1021 Multi-core scheduler support improves the CPU scheduler's decision
1022 making when dealing with multi-core CPU chips at a cost of slightly
1023 increased overhead in some places. If unsure say N here.
1025 config SCHED_MC_PRIO
1026 bool "CPU core priorities scheduler support"
1027 depends on SCHED_MC && CPU_SUP_INTEL
1028 select X86_INTEL_PSTATE
1032 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1033 core ordering determined at manufacturing time, which allows
1034 certain cores to reach higher turbo frequencies (when running
1035 single threaded workloads) than others.
1037 Enabling this kernel feature teaches the scheduler about
1038 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1039 scheduler's CPU selection logic accordingly, so that higher
1040 overall system performance can be achieved.
1042 This feature will have no effect on CPUs without this feature.
1044 If unsure say Y here.
1048 depends on !SMP && X86_LOCAL_APIC
1051 bool "Local APIC support on uniprocessors" if !PCI_MSI
1053 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1055 A local APIC (Advanced Programmable Interrupt Controller) is an
1056 integrated interrupt controller in the CPU. If you have a single-CPU
1057 system which has a processor with a local APIC, you can say Y here to
1058 enable and use it. If you say Y here even though your machine doesn't
1059 have a local APIC, then the kernel will still run with no slowdown at
1060 all. The local APIC supports CPU-generated self-interrupts (timer,
1061 performance counters), and the NMI watchdog which detects hard
1064 config X86_UP_IOAPIC
1065 bool "IO-APIC support on uniprocessors"
1066 depends on X86_UP_APIC
1068 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1069 SMP-capable replacement for PC-style interrupt controllers. Most
1070 SMP systems and many recent uniprocessor systems have one.
1072 If you have a single-CPU system with an IO-APIC, you can say Y here
1073 to use it. If you say Y here even though your machine doesn't have
1074 an IO-APIC, then the kernel will still run with no slowdown at all.
1076 config X86_LOCAL_APIC
1078 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1079 select IRQ_DOMAIN_HIERARCHY
1080 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1084 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1086 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1087 bool "Reroute for broken boot IRQs"
1088 depends on X86_IO_APIC
1090 This option enables a workaround that fixes a source of
1091 spurious interrupts. This is recommended when threaded
1092 interrupt handling is used on systems where the generation of
1093 superfluous "boot interrupts" cannot be disabled.
1095 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1096 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1097 kernel does during interrupt handling). On chipsets where this
1098 boot IRQ generation cannot be disabled, this workaround keeps
1099 the original IRQ line masked so that only the equivalent "boot
1100 IRQ" is delivered to the CPUs. The workaround also tells the
1101 kernel to set up the IRQ handler on the boot IRQ line. In this
1102 way only one interrupt is delivered to the kernel. Otherwise
1103 the spurious second interrupt may cause the kernel to bring
1104 down (vital) interrupt lines.
1106 Only affects "broken" chipsets. Interrupt sharing may be
1107 increased on these systems.
1110 bool "Machine Check / overheating reporting"
1111 select GENERIC_ALLOCATOR
1114 Machine Check support allows the processor to notify the
1115 kernel if it detects a problem (e.g. overheating, data corruption).
1116 The action the kernel takes depends on the severity of the problem,
1117 ranging from warning messages to halting the machine.
1119 config X86_MCELOG_LEGACY
1120 bool "Support for deprecated /dev/mcelog character device"
1123 Enable support for /dev/mcelog which is needed by the old mcelog
1124 userspace logging daemon. Consider switching to the new generation
1127 config X86_MCE_INTEL
1129 prompt "Intel MCE features"
1130 depends on X86_MCE && X86_LOCAL_APIC
1132 Additional support for intel specific MCE features such as
1133 the thermal monitor.
1137 prompt "AMD MCE features"
1138 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1140 Additional support for AMD specific MCE features such as
1141 the DRAM Error Threshold.
1143 config X86_ANCIENT_MCE
1144 bool "Support for old Pentium 5 / WinChip machine checks"
1145 depends on X86_32 && X86_MCE
1147 Include support for machine check handling on old Pentium 5 or WinChip
1148 systems. These typically need to be enabled explicitly on the command
1151 config X86_MCE_THRESHOLD
1152 depends on X86_MCE_AMD || X86_MCE_INTEL
1155 config X86_MCE_INJECT
1156 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1157 tristate "Machine check injector support"
1159 Provide support for injecting machine checks for testing purposes.
1160 If you don't know what a machine check is and you don't do kernel
1161 QA it is safe to say n.
1163 config X86_THERMAL_VECTOR
1165 depends on X86_MCE_INTEL
1167 source "arch/x86/events/Kconfig"
1169 config X86_LEGACY_VM86
1170 bool "Legacy VM86 support"
1173 This option allows user programs to put the CPU into V8086
1174 mode, which is an 80286-era approximation of 16-bit real mode.
1176 Some very old versions of X and/or vbetool require this option
1177 for user mode setting. Similarly, DOSEMU will use it if
1178 available to accelerate real mode DOS programs. However, any
1179 recent version of DOSEMU, X, or vbetool should be fully
1180 functional even without kernel VM86 support, as they will all
1181 fall back to software emulation. Nevertheless, if you are using
1182 a 16-bit DOS program where 16-bit performance matters, vm86
1183 mode might be faster than emulation and you might want to
1186 Note that any app that works on a 64-bit kernel is unlikely to
1187 need this option, as 64-bit kernels don't, and can't, support
1188 V8086 mode. This option is also unrelated to 16-bit protected
1189 mode and is not needed to run most 16-bit programs under Wine.
1191 Enabling this option increases the complexity of the kernel
1192 and slows down exception handling a tiny bit.
1194 If unsure, say N here.
1198 default X86_LEGACY_VM86
1201 bool "Enable support for 16-bit segments" if EXPERT
1203 depends on MODIFY_LDT_SYSCALL
1205 This option is required by programs like Wine to run 16-bit
1206 protected mode legacy code on x86 processors. Disabling
1207 this option saves about 300 bytes on i386, or around 6K text
1208 plus 16K runtime memory on x86-64,
1212 depends on X86_16BIT && X86_32
1216 depends on X86_16BIT && X86_64
1218 config X86_VSYSCALL_EMULATION
1219 bool "Enable vsyscall emulation" if EXPERT
1223 This enables emulation of the legacy vsyscall page. Disabling
1224 it is roughly equivalent to booting with vsyscall=none, except
1225 that it will also disable the helpful warning if a program
1226 tries to use a vsyscall. With this option set to N, offending
1227 programs will just segfault, citing addresses of the form
1230 This option is required by many programs built before 2013, and
1231 care should be used even with newer programs if set to N.
1233 Disabling this option saves about 7K of kernel size and
1234 possibly 4K of additional runtime pagetable memory.
1237 tristate "Toshiba Laptop support"
1240 This adds a driver to safely access the System Management Mode of
1241 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1242 not work on models with a Phoenix BIOS. The System Management Mode
1243 is used to set the BIOS and power saving options on Toshiba portables.
1245 For information on utilities to make use of this driver see the
1246 Toshiba Linux utilities web site at:
1247 <http://www.buzzard.org.uk/toshiba/>.
1249 Say Y if you intend to run this kernel on a Toshiba portable.
1253 tristate "Dell i8k legacy laptop support"
1255 select SENSORS_DELL_SMM
1257 This option enables legacy /proc/i8k userspace interface in hwmon
1258 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1259 temperature and allows controlling fan speeds of Dell laptops via
1260 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1261 it reports also power and hotkey status. For fan speed control is
1262 needed userspace package i8kutils.
1264 Say Y if you intend to run this kernel on old Dell laptops or want to
1265 use userspace package i8kutils.
1268 config X86_REBOOTFIXUPS
1269 bool "Enable X86 board specific fixups for reboot"
1272 This enables chipset and/or board specific fixups to be done
1273 in order to get reboot to work correctly. This is only needed on
1274 some combinations of hardware and BIOS. The symptom, for which
1275 this config is intended, is when reboot ends with a stalled/hung
1278 Currently, the only fixup is for the Geode machines using
1279 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1281 Say Y if you want to enable the fixup. Currently, it's safe to
1282 enable this option even if you don't need it.
1286 bool "CPU microcode loading support"
1288 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1291 If you say Y here, you will be able to update the microcode on
1292 Intel and AMD processors. The Intel support is for the IA32 family,
1293 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1294 AMD support is for families 0x10 and later. You will obviously need
1295 the actual microcode binary data itself which is not shipped with
1298 The preferred method to load microcode from a detached initrd is described
1299 in Documentation/x86/microcode.txt. For that you need to enable
1300 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1301 initrd for microcode blobs.
1303 In addition, you can build the microcode into the kernel. For that you
1304 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1307 config MICROCODE_INTEL
1308 bool "Intel microcode loading support"
1309 depends on MICROCODE
1313 This options enables microcode patch loading support for Intel
1316 For the current Intel microcode data package go to
1317 <https://downloadcenter.intel.com> and search for
1318 'Linux Processor Microcode Data File'.
1320 config MICROCODE_AMD
1321 bool "AMD microcode loading support"
1322 depends on MICROCODE
1325 If you select this option, microcode patch loading support for AMD
1326 processors will be enabled.
1328 config MICROCODE_OLD_INTERFACE
1330 depends on MICROCODE
1333 tristate "/dev/cpu/*/msr - Model-specific register support"
1335 This device gives privileged processes access to the x86
1336 Model-Specific Registers (MSRs). It is a character device with
1337 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1338 MSR accesses are directed to a specific CPU on multi-processor
1342 tristate "/dev/cpu/*/cpuid - CPU information support"
1344 This device gives processes access to the x86 CPUID instruction to
1345 be executed on a specific processor. It is a character device
1346 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1350 prompt "High Memory Support"
1357 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1358 However, the address space of 32-bit x86 processors is only 4
1359 Gigabytes large. That means that, if you have a large amount of
1360 physical memory, not all of it can be "permanently mapped" by the
1361 kernel. The physical memory that's not permanently mapped is called
1364 If you are compiling a kernel which will never run on a machine with
1365 more than 1 Gigabyte total physical RAM, answer "off" here (default
1366 choice and suitable for most users). This will result in a "3GB/1GB"
1367 split: 3GB are mapped so that each process sees a 3GB virtual memory
1368 space and the remaining part of the 4GB virtual memory space is used
1369 by the kernel to permanently map as much physical memory as
1372 If the machine has between 1 and 4 Gigabytes physical RAM, then
1375 If more than 4 Gigabytes is used then answer "64GB" here. This
1376 selection turns Intel PAE (Physical Address Extension) mode on.
1377 PAE implements 3-level paging on IA32 processors. PAE is fully
1378 supported by Linux, PAE mode is implemented on all recent Intel
1379 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1380 then the kernel will not boot on CPUs that don't support PAE!
1382 The actual amount of total physical memory will either be
1383 auto detected or can be forced by using a kernel command line option
1384 such as "mem=256M". (Try "man bootparam" or see the documentation of
1385 your boot loader (lilo or loadlin) about how to pass options to the
1386 kernel at boot time.)
1388 If unsure, say "off".
1393 Select this if you have a 32-bit processor and between 1 and 4
1394 gigabytes of physical RAM.
1398 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1401 Select this if you have a 32-bit processor and more than 4
1402 gigabytes of physical RAM.
1407 prompt "Memory split" if EXPERT
1411 Select the desired split between kernel and user memory.
1413 If the address range available to the kernel is less than the
1414 physical memory installed, the remaining memory will be available
1415 as "high memory". Accessing high memory is a little more costly
1416 than low memory, as it needs to be mapped into the kernel first.
1417 Note that increasing the kernel address space limits the range
1418 available to user programs, making the address space there
1419 tighter. Selecting anything other than the default 3G/1G split
1420 will also likely make your kernel incompatible with binary-only
1423 If you are not absolutely sure what you are doing, leave this
1427 bool "3G/1G user/kernel split"
1428 config VMSPLIT_3G_OPT
1430 bool "3G/1G user/kernel split (for full 1G low memory)"
1432 bool "2G/2G user/kernel split"
1433 config VMSPLIT_2G_OPT
1435 bool "2G/2G user/kernel split (for full 2G low memory)"
1437 bool "1G/3G user/kernel split"
1442 default 0xB0000000 if VMSPLIT_3G_OPT
1443 default 0x80000000 if VMSPLIT_2G
1444 default 0x78000000 if VMSPLIT_2G_OPT
1445 default 0x40000000 if VMSPLIT_1G
1451 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1454 bool "PAE (Physical Address Extension) Support"
1455 depends on X86_32 && !HIGHMEM4G
1456 select PHYS_ADDR_T_64BIT
1459 PAE is required for NX support, and furthermore enables
1460 larger swapspace support for non-overcommit purposes. It
1461 has the cost of more pagetable lookup overhead, and also
1462 consumes more pagetable space per process.
1465 bool "Enable 5-level page tables support"
1466 select DYNAMIC_MEMORY_LAYOUT
1467 select SPARSEMEM_VMEMMAP
1470 5-level paging enables access to larger address space:
1471 upto 128 PiB of virtual address space and 4 PiB of
1472 physical address space.
1474 It will be supported by future Intel CPUs.
1476 A kernel with the option enabled can be booted on machines that
1477 support 4- or 5-level paging.
1479 See Documentation/x86/x86_64/5level-paging.txt for more
1484 config X86_DIRECT_GBPAGES
1486 depends on X86_64 && !DEBUG_PAGEALLOC
1488 Certain kernel features effectively disable kernel
1489 linear 1 GB mappings (even if the CPU otherwise
1490 supports them), so don't confuse the user by printing
1491 that we have them enabled.
1493 config X86_CPA_STATISTICS
1494 bool "Enable statistic for Change Page Attribute"
1497 Expose statistics about the Change Page Attribute mechanims, which
1498 helps to determine the effectivness of preserving large and huge
1499 page mappings when mapping protections are changed.
1501 config ARCH_HAS_MEM_ENCRYPT
1504 config AMD_MEM_ENCRYPT
1505 bool "AMD Secure Memory Encryption (SME) support"
1506 depends on X86_64 && CPU_SUP_AMD
1507 select DYNAMIC_PHYSICAL_MASK
1509 Say yes to enable support for the encryption of system memory.
1510 This requires an AMD processor that supports Secure Memory
1513 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1514 bool "Activate AMD Secure Memory Encryption (SME) by default"
1516 depends on AMD_MEM_ENCRYPT
1518 Say yes to have system memory encrypted by default if running on
1519 an AMD processor that supports Secure Memory Encryption (SME).
1521 If set to Y, then the encryption of system memory can be
1522 deactivated with the mem_encrypt=off command line option.
1524 If set to N, then the encryption of system memory can be
1525 activated with the mem_encrypt=on command line option.
1527 config ARCH_USE_MEMREMAP_PROT
1529 depends on AMD_MEM_ENCRYPT
1531 # Common NUMA Features
1533 bool "Numa Memory Allocation and Scheduler Support"
1535 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1536 default y if X86_BIGSMP
1538 Enable NUMA (Non Uniform Memory Access) support.
1540 The kernel will try to allocate memory used by a CPU on the
1541 local memory controller of the CPU and add some more
1542 NUMA awareness to the kernel.
1544 For 64-bit this is recommended if the system is Intel Core i7
1545 (or later), AMD Opteron, or EM64T NUMA.
1547 For 32-bit this is only needed if you boot a 32-bit
1548 kernel on a 64-bit NUMA platform.
1550 Otherwise, you should say N.
1554 prompt "Old style AMD Opteron NUMA detection"
1555 depends on X86_64 && NUMA && PCI
1557 Enable AMD NUMA node topology detection. You should say Y here if
1558 you have a multi processor AMD system. This uses an old method to
1559 read the NUMA configuration directly from the builtin Northbridge
1560 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1561 which also takes priority if both are compiled in.
1563 config X86_64_ACPI_NUMA
1565 prompt "ACPI NUMA detection"
1566 depends on X86_64 && NUMA && ACPI && PCI
1569 Enable ACPI SRAT based node topology detection.
1571 # Some NUMA nodes have memory ranges that span
1572 # other nodes. Even though a pfn is valid and
1573 # between a node's start and end pfns, it may not
1574 # reside on that node. See memmap_init_zone()
1576 config NODES_SPAN_OTHER_NODES
1578 depends on X86_64_ACPI_NUMA
1581 bool "NUMA emulation"
1584 Enable NUMA emulation. A flat machine will be split
1585 into virtual nodes when booted with "numa=fake=N", where N is the
1586 number of nodes. This is only useful for debugging.
1589 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1591 default "10" if MAXSMP
1592 default "6" if X86_64
1594 depends on NEED_MULTIPLE_NODES
1596 Specify the maximum number of NUMA Nodes available on the target
1597 system. Increases memory reserved to accommodate various tables.
1599 config ARCH_HAVE_MEMORY_PRESENT
1601 depends on X86_32 && DISCONTIGMEM
1603 config ARCH_FLATMEM_ENABLE
1605 depends on X86_32 && !NUMA
1607 config ARCH_DISCONTIGMEM_ENABLE
1609 depends on NUMA && X86_32
1611 config ARCH_DISCONTIGMEM_DEFAULT
1613 depends on NUMA && X86_32
1615 config ARCH_SPARSEMEM_ENABLE
1617 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1618 select SPARSEMEM_STATIC if X86_32
1619 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1621 config ARCH_SPARSEMEM_DEFAULT
1625 config ARCH_SELECT_MEMORY_MODEL
1627 depends on ARCH_SPARSEMEM_ENABLE
1629 config ARCH_MEMORY_PROBE
1630 bool "Enable sysfs memory/probe interface"
1631 depends on X86_64 && MEMORY_HOTPLUG
1633 This option enables a sysfs memory/probe interface for testing.
1634 See Documentation/memory-hotplug.txt for more information.
1635 If you are unsure how to answer this question, answer N.
1637 config ARCH_PROC_KCORE_TEXT
1639 depends on X86_64 && PROC_KCORE
1641 config ILLEGAL_POINTER_VALUE
1644 default 0xdead000000000000 if X86_64
1646 config X86_PMEM_LEGACY_DEVICE
1649 config X86_PMEM_LEGACY
1650 tristate "Support non-standard NVDIMMs and ADR protected memory"
1651 depends on PHYS_ADDR_T_64BIT
1653 select X86_PMEM_LEGACY_DEVICE
1656 Treat memory marked using the non-standard e820 type of 12 as used
1657 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1658 The kernel will offer these regions to the 'pmem' driver so
1659 they can be used for persistent storage.
1664 bool "Allocate 3rd-level pagetables from highmem"
1667 The VM uses one page table entry for each page of physical memory.
1668 For systems with a lot of RAM, this can be wasteful of precious
1669 low memory. Setting this option will put user-space page table
1670 entries in high memory.
1672 config X86_CHECK_BIOS_CORRUPTION
1673 bool "Check for low memory corruption"
1675 Periodically check for memory corruption in low memory, which
1676 is suspected to be caused by BIOS. Even when enabled in the
1677 configuration, it is disabled at runtime. Enable it by
1678 setting "memory_corruption_check=1" on the kernel command
1679 line. By default it scans the low 64k of memory every 60
1680 seconds; see the memory_corruption_check_size and
1681 memory_corruption_check_period parameters in
1682 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1684 When enabled with the default parameters, this option has
1685 almost no overhead, as it reserves a relatively small amount
1686 of memory and scans it infrequently. It both detects corruption
1687 and prevents it from affecting the running system.
1689 It is, however, intended as a diagnostic tool; if repeatable
1690 BIOS-originated corruption always affects the same memory,
1691 you can use memmap= to prevent the kernel from using that
1694 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1695 bool "Set the default setting of memory_corruption_check"
1696 depends on X86_CHECK_BIOS_CORRUPTION
1699 Set whether the default state of memory_corruption_check is
1702 config X86_RESERVE_LOW
1703 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1707 Specify the amount of low memory to reserve for the BIOS.
1709 The first page contains BIOS data structures that the kernel
1710 must not use, so that page must always be reserved.
1712 By default we reserve the first 64K of physical RAM, as a
1713 number of BIOSes are known to corrupt that memory range
1714 during events such as suspend/resume or monitor cable
1715 insertion, so it must not be used by the kernel.
1717 You can set this to 4 if you are absolutely sure that you
1718 trust the BIOS to get all its memory reservations and usages
1719 right. If you know your BIOS have problems beyond the
1720 default 64K area, you can set this to 640 to avoid using the
1721 entire low memory range.
1723 If you have doubts about the BIOS (e.g. suspend/resume does
1724 not work or there's kernel crashes after certain hardware
1725 hotplug events) then you might want to enable
1726 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1727 typical corruption patterns.
1729 Leave this to the default value of 64 if you are unsure.
1731 config MATH_EMULATION
1733 depends on MODIFY_LDT_SYSCALL
1734 prompt "Math emulation" if X86_32
1736 Linux can emulate a math coprocessor (used for floating point
1737 operations) if you don't have one. 486DX and Pentium processors have
1738 a math coprocessor built in, 486SX and 386 do not, unless you added
1739 a 487DX or 387, respectively. (The messages during boot time can
1740 give you some hints here ["man dmesg"].) Everyone needs either a
1741 coprocessor or this emulation.
1743 If you don't have a math coprocessor, you need to say Y here; if you
1744 say Y here even though you have a coprocessor, the coprocessor will
1745 be used nevertheless. (This behavior can be changed with the kernel
1746 command line option "no387", which comes handy if your coprocessor
1747 is broken. Try "man bootparam" or see the documentation of your boot
1748 loader (lilo or loadlin) about how to pass options to the kernel at
1749 boot time.) This means that it is a good idea to say Y here if you
1750 intend to use this kernel on different machines.
1752 More information about the internals of the Linux math coprocessor
1753 emulation can be found in <file:arch/x86/math-emu/README>.
1755 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1756 kernel, it won't hurt.
1760 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1762 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1763 the Memory Type Range Registers (MTRRs) may be used to control
1764 processor access to memory ranges. This is most useful if you have
1765 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1766 allows bus write transfers to be combined into a larger transfer
1767 before bursting over the PCI/AGP bus. This can increase performance
1768 of image write operations 2.5 times or more. Saying Y here creates a
1769 /proc/mtrr file which may be used to manipulate your processor's
1770 MTRRs. Typically the X server should use this.
1772 This code has a reasonably generic interface so that similar
1773 control registers on other processors can be easily supported
1776 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1777 Registers (ARRs) which provide a similar functionality to MTRRs. For
1778 these, the ARRs are used to emulate the MTRRs.
1779 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1780 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1781 write-combining. All of these processors are supported by this code
1782 and it makes sense to say Y here if you have one of them.
1784 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1785 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1786 can lead to all sorts of problems, so it's good to say Y here.
1788 You can safely say Y even if your machine doesn't have MTRRs, you'll
1789 just add about 9 KB to your kernel.
1791 See <file:Documentation/x86/mtrr.txt> for more information.
1793 config MTRR_SANITIZER
1795 prompt "MTRR cleanup support"
1798 Convert MTRR layout from continuous to discrete, so X drivers can
1799 add writeback entries.
1801 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1802 The largest mtrr entry size for a continuous block can be set with
1807 config MTRR_SANITIZER_ENABLE_DEFAULT
1808 int "MTRR cleanup enable value (0-1)"
1811 depends on MTRR_SANITIZER
1813 Enable mtrr cleanup default value
1815 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1816 int "MTRR cleanup spare reg num (0-7)"
1819 depends on MTRR_SANITIZER
1821 mtrr cleanup spare entries default, it can be changed via
1822 mtrr_spare_reg_nr=N on the kernel command line.
1826 prompt "x86 PAT support" if EXPERT
1829 Use PAT attributes to setup page level cache control.
1831 PATs are the modern equivalents of MTRRs and are much more
1832 flexible than MTRRs.
1834 Say N here if you see bootup problems (boot crash, boot hang,
1835 spontaneous reboots) or a non-working video driver.
1839 config ARCH_USES_PG_UNCACHED
1845 prompt "x86 architectural random number generator" if EXPERT
1847 Enable the x86 architectural RDRAND instruction
1848 (Intel Bull Mountain technology) to generate random numbers.
1849 If supported, this is a high bandwidth, cryptographically
1850 secure hardware random number generator.
1854 prompt "Supervisor Mode Access Prevention" if EXPERT
1856 Supervisor Mode Access Prevention (SMAP) is a security
1857 feature in newer Intel processors. There is a small
1858 performance cost if this enabled and turned on; there is
1859 also a small increase in the kernel size if this is enabled.
1863 config X86_INTEL_UMIP
1865 depends on CPU_SUP_INTEL
1866 prompt "Intel User Mode Instruction Prevention" if EXPERT
1868 The User Mode Instruction Prevention (UMIP) is a security
1869 feature in newer Intel processors. If enabled, a general
1870 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1871 or STR instructions are executed in user mode. These instructions
1872 unnecessarily expose information about the hardware state.
1874 The vast majority of applications do not use these instructions.
1875 For the very few that do, software emulation is provided in
1876 specific cases in protected and virtual-8086 modes. Emulated
1879 config X86_INTEL_MPX
1880 prompt "Intel MPX (Memory Protection Extensions)"
1882 # Note: only available in 64-bit mode due to VMA flags shortage
1883 depends on CPU_SUP_INTEL && X86_64
1884 select ARCH_USES_HIGH_VMA_FLAGS
1886 MPX provides hardware features that can be used in
1887 conjunction with compiler-instrumented code to check
1888 memory references. It is designed to detect buffer
1889 overflow or underflow bugs.
1891 This option enables running applications which are
1892 instrumented or otherwise use MPX. It does not use MPX
1893 itself inside the kernel or to protect the kernel
1894 against bad memory references.
1896 Enabling this option will make the kernel larger:
1897 ~8k of kernel text and 36 bytes of data on a 64-bit
1898 defconfig. It adds a long to the 'mm_struct' which
1899 will increase the kernel memory overhead of each
1900 process and adds some branches to paths used during
1901 exec() and munmap().
1903 For details, see Documentation/x86/intel_mpx.txt
1907 config X86_INTEL_MEMORY_PROTECTION_KEYS
1908 prompt "Intel Memory Protection Keys"
1910 # Note: only available in 64-bit mode
1911 depends on CPU_SUP_INTEL && X86_64
1912 select ARCH_USES_HIGH_VMA_FLAGS
1913 select ARCH_HAS_PKEYS
1915 Memory Protection Keys provides a mechanism for enforcing
1916 page-based protections, but without requiring modification of the
1917 page tables when an application changes protection domains.
1919 For details, see Documentation/x86/protection-keys.txt
1924 bool "EFI runtime service support"
1927 select EFI_RUNTIME_WRAPPERS
1929 This enables the kernel to use EFI runtime services that are
1930 available (such as the EFI variable services).
1932 This option is only useful on systems that have EFI firmware.
1933 In addition, you should use the latest ELILO loader available
1934 at <http://elilo.sourceforge.net> in order to take advantage
1935 of EFI runtime services. However, even with this option, the
1936 resultant kernel should continue to boot on existing non-EFI
1940 bool "EFI stub support"
1941 depends on EFI && !X86_USE_3DNOW
1944 This kernel feature allows a bzImage to be loaded directly
1945 by EFI firmware without the use of a bootloader.
1947 See Documentation/efi-stub.txt for more information.
1950 bool "EFI mixed-mode support"
1951 depends on EFI_STUB && X86_64
1953 Enabling this feature allows a 64-bit kernel to be booted
1954 on a 32-bit firmware, provided that your CPU supports 64-bit
1957 Note that it is not possible to boot a mixed-mode enabled
1958 kernel via the EFI boot stub - a bootloader that supports
1959 the EFI handover protocol must be used.
1965 prompt "Enable seccomp to safely compute untrusted bytecode"
1967 This kernel feature is useful for number crunching applications
1968 that may need to compute untrusted bytecode during their
1969 execution. By using pipes or other transports made available to
1970 the process as file descriptors supporting the read/write
1971 syscalls, it's possible to isolate those applications in
1972 their own address space using seccomp. Once seccomp is
1973 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1974 and the task is only allowed to execute a few safe syscalls
1975 defined by each seccomp mode.
1977 If unsure, say Y. Only embedded should say N here.
1979 source kernel/Kconfig.hz
1982 bool "kexec system call"
1985 kexec is a system call that implements the ability to shutdown your
1986 current kernel, and to start another kernel. It is like a reboot
1987 but it is independent of the system firmware. And like a reboot
1988 you can start any kernel with it, not just Linux.
1990 The name comes from the similarity to the exec system call.
1992 It is an ongoing process to be certain the hardware in a machine
1993 is properly shutdown, so do not be surprised if this code does not
1994 initially work for you. As of this writing the exact hardware
1995 interface is strongly in flux, so no good recommendation can be
1999 bool "kexec file based system call"
2004 depends on CRYPTO_SHA256=y
2006 This is new version of kexec system call. This system call is
2007 file based and takes file descriptors as system call argument
2008 for kernel and initramfs as opposed to list of segments as
2009 accepted by previous system call.
2011 config ARCH_HAS_KEXEC_PURGATORY
2014 config KEXEC_VERIFY_SIG
2015 bool "Verify kernel signature during kexec_file_load() syscall"
2016 depends on KEXEC_FILE
2018 This option makes kernel signature verification mandatory for
2019 the kexec_file_load() syscall.
2021 In addition to that option, you need to enable signature
2022 verification for the corresponding kernel image type being
2023 loaded in order for this to work.
2025 config KEXEC_BZIMAGE_VERIFY_SIG
2026 bool "Enable bzImage signature verification support"
2027 depends on KEXEC_VERIFY_SIG
2028 depends on SIGNED_PE_FILE_VERIFICATION
2029 select SYSTEM_TRUSTED_KEYRING
2031 Enable bzImage signature verification support.
2034 bool "kernel crash dumps"
2035 depends on X86_64 || (X86_32 && HIGHMEM)
2037 Generate crash dump after being started by kexec.
2038 This should be normally only set in special crash dump kernels
2039 which are loaded in the main kernel with kexec-tools into
2040 a specially reserved region and then later executed after
2041 a crash by kdump/kexec. The crash dump kernel must be compiled
2042 to a memory address not used by the main kernel or BIOS using
2043 PHYSICAL_START, or it must be built as a relocatable image
2044 (CONFIG_RELOCATABLE=y).
2045 For more details see Documentation/kdump/kdump.txt
2049 depends on KEXEC && HIBERNATION
2051 Jump between original kernel and kexeced kernel and invoke
2052 code in physical address mode via KEXEC
2054 config PHYSICAL_START
2055 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2058 This gives the physical address where the kernel is loaded.
2060 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2061 bzImage will decompress itself to above physical address and
2062 run from there. Otherwise, bzImage will run from the address where
2063 it has been loaded by the boot loader and will ignore above physical
2066 In normal kdump cases one does not have to set/change this option
2067 as now bzImage can be compiled as a completely relocatable image
2068 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2069 address. This option is mainly useful for the folks who don't want
2070 to use a bzImage for capturing the crash dump and want to use a
2071 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2072 to be specifically compiled to run from a specific memory area
2073 (normally a reserved region) and this option comes handy.
2075 So if you are using bzImage for capturing the crash dump,
2076 leave the value here unchanged to 0x1000000 and set
2077 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2078 for capturing the crash dump change this value to start of
2079 the reserved region. In other words, it can be set based on
2080 the "X" value as specified in the "crashkernel=YM@XM"
2081 command line boot parameter passed to the panic-ed
2082 kernel. Please take a look at Documentation/kdump/kdump.txt
2083 for more details about crash dumps.
2085 Usage of bzImage for capturing the crash dump is recommended as
2086 one does not have to build two kernels. Same kernel can be used
2087 as production kernel and capture kernel. Above option should have
2088 gone away after relocatable bzImage support is introduced. But it
2089 is present because there are users out there who continue to use
2090 vmlinux for dump capture. This option should go away down the
2093 Don't change this unless you know what you are doing.
2096 bool "Build a relocatable kernel"
2099 This builds a kernel image that retains relocation information
2100 so it can be loaded someplace besides the default 1MB.
2101 The relocations tend to make the kernel binary about 10% larger,
2102 but are discarded at runtime.
2104 One use is for the kexec on panic case where the recovery kernel
2105 must live at a different physical address than the primary
2108 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2109 it has been loaded at and the compile time physical address
2110 (CONFIG_PHYSICAL_START) is used as the minimum location.
2112 config RANDOMIZE_BASE
2113 bool "Randomize the address of the kernel image (KASLR)"
2114 depends on RELOCATABLE
2117 In support of Kernel Address Space Layout Randomization (KASLR),
2118 this randomizes the physical address at which the kernel image
2119 is decompressed and the virtual address where the kernel
2120 image is mapped, as a security feature that deters exploit
2121 attempts relying on knowledge of the location of kernel
2124 On 64-bit, the kernel physical and virtual addresses are
2125 randomized separately. The physical address will be anywhere
2126 between 16MB and the top of physical memory (up to 64TB). The
2127 virtual address will be randomized from 16MB up to 1GB (9 bits
2128 of entropy). Note that this also reduces the memory space
2129 available to kernel modules from 1.5GB to 1GB.
2131 On 32-bit, the kernel physical and virtual addresses are
2132 randomized together. They will be randomized from 16MB up to
2133 512MB (8 bits of entropy).
2135 Entropy is generated using the RDRAND instruction if it is
2136 supported. If RDTSC is supported, its value is mixed into
2137 the entropy pool as well. If neither RDRAND nor RDTSC are
2138 supported, then entropy is read from the i8254 timer. The
2139 usable entropy is limited by the kernel being built using
2140 2GB addressing, and that PHYSICAL_ALIGN must be at a
2141 minimum of 2MB. As a result, only 10 bits of entropy are
2142 theoretically possible, but the implementations are further
2143 limited due to memory layouts.
2147 # Relocation on x86 needs some additional build support
2148 config X86_NEED_RELOCS
2150 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2152 config PHYSICAL_ALIGN
2153 hex "Alignment value to which kernel should be aligned"
2155 range 0x2000 0x1000000 if X86_32
2156 range 0x200000 0x1000000 if X86_64
2158 This value puts the alignment restrictions on physical address
2159 where kernel is loaded and run from. Kernel is compiled for an
2160 address which meets above alignment restriction.
2162 If bootloader loads the kernel at a non-aligned address and
2163 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2164 address aligned to above value and run from there.
2166 If bootloader loads the kernel at a non-aligned address and
2167 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2168 load address and decompress itself to the address it has been
2169 compiled for and run from there. The address for which kernel is
2170 compiled already meets above alignment restrictions. Hence the
2171 end result is that kernel runs from a physical address meeting
2172 above alignment restrictions.
2174 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2175 this value must be a multiple of 0x200000.
2177 Don't change this unless you know what you are doing.
2179 config DYNAMIC_MEMORY_LAYOUT
2182 This option makes base addresses of vmalloc and vmemmap as well as
2183 __PAGE_OFFSET movable during boot.
2185 config RANDOMIZE_MEMORY
2186 bool "Randomize the kernel memory sections"
2188 depends on RANDOMIZE_BASE
2189 select DYNAMIC_MEMORY_LAYOUT
2190 default RANDOMIZE_BASE
2192 Randomizes the base virtual address of kernel memory sections
2193 (physical memory mapping, vmalloc & vmemmap). This security feature
2194 makes exploits relying on predictable memory locations less reliable.
2196 The order of allocations remains unchanged. Entropy is generated in
2197 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2198 configuration have in average 30,000 different possible virtual
2199 addresses for each memory section.
2203 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2204 hex "Physical memory mapping padding" if EXPERT
2205 depends on RANDOMIZE_MEMORY
2206 default "0xa" if MEMORY_HOTPLUG
2208 range 0x1 0x40 if MEMORY_HOTPLUG
2211 Define the padding in terabytes added to the existing physical
2212 memory size during kernel memory randomization. It is useful
2213 for memory hotplug support but reduces the entropy available for
2214 address randomization.
2216 If unsure, leave at the default value.
2219 bool "Support for hot-pluggable CPUs"
2222 Say Y here to allow turning CPUs off and on. CPUs can be
2223 controlled through /sys/devices/system/cpu.
2224 ( Note: power management support will enable this option
2225 automatically on SMP systems. )
2226 Say N if you want to disable CPU hotplug.
2228 config BOOTPARAM_HOTPLUG_CPU0
2229 bool "Set default setting of cpu0_hotpluggable"
2230 depends on HOTPLUG_CPU
2232 Set whether default state of cpu0_hotpluggable is on or off.
2234 Say Y here to enable CPU0 hotplug by default. If this switch
2235 is turned on, there is no need to give cpu0_hotplug kernel
2236 parameter and the CPU0 hotplug feature is enabled by default.
2238 Please note: there are two known CPU0 dependencies if you want
2239 to enable the CPU0 hotplug feature either by this switch or by
2240 cpu0_hotplug kernel parameter.
2242 First, resume from hibernate or suspend always starts from CPU0.
2243 So hibernate and suspend are prevented if CPU0 is offline.
2245 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2246 offline if any interrupt can not migrate out of CPU0. There may
2247 be other CPU0 dependencies.
2249 Please make sure the dependencies are under your control before
2250 you enable this feature.
2252 Say N if you don't want to enable CPU0 hotplug feature by default.
2253 You still can enable the CPU0 hotplug feature at boot by kernel
2254 parameter cpu0_hotplug.
2256 config DEBUG_HOTPLUG_CPU0
2258 prompt "Debug CPU0 hotplug"
2259 depends on HOTPLUG_CPU
2261 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2262 soon as possible and boots up userspace with CPU0 offlined. User
2263 can online CPU0 back after boot time.
2265 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2266 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2267 compilation or giving cpu0_hotplug kernel parameter at boot.
2273 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2274 depends on COMPAT_32
2276 Certain buggy versions of glibc will crash if they are
2277 presented with a 32-bit vDSO that is not mapped at the address
2278 indicated in its segment table.
2280 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2281 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2282 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2283 the only released version with the bug, but OpenSUSE 9
2284 contains a buggy "glibc 2.3.2".
2286 The symptom of the bug is that everything crashes on startup, saying:
2287 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2289 Saying Y here changes the default value of the vdso32 boot
2290 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2291 This works around the glibc bug but hurts performance.
2293 If unsure, say N: if you are compiling your own kernel, you
2294 are unlikely to be using a buggy version of glibc.
2297 prompt "vsyscall table for legacy applications"
2299 default LEGACY_VSYSCALL_EMULATE
2301 Legacy user code that does not know how to find the vDSO expects
2302 to be able to issue three syscalls by calling fixed addresses in
2303 kernel space. Since this location is not randomized with ASLR,
2304 it can be used to assist security vulnerability exploitation.
2306 This setting can be changed at boot time via the kernel command
2307 line parameter vsyscall=[emulate|none].
2309 On a system with recent enough glibc (2.14 or newer) and no
2310 static binaries, you can say None without a performance penalty
2311 to improve security.
2313 If unsure, select "Emulate".
2315 config LEGACY_VSYSCALL_EMULATE
2318 The kernel traps and emulates calls into the fixed
2319 vsyscall address mapping. This makes the mapping
2320 non-executable, but it still contains known contents,
2321 which could be used in certain rare security vulnerability
2322 exploits. This configuration is recommended when userspace
2323 still uses the vsyscall area.
2325 config LEGACY_VSYSCALL_NONE
2328 There will be no vsyscall mapping at all. This will
2329 eliminate any risk of ASLR bypass due to the vsyscall
2330 fixed address mapping. Attempts to use the vsyscalls
2331 will be reported to dmesg, so that either old or
2332 malicious userspace programs can be identified.
2337 bool "Built-in kernel command line"
2339 Allow for specifying boot arguments to the kernel at
2340 build time. On some systems (e.g. embedded ones), it is
2341 necessary or convenient to provide some or all of the
2342 kernel boot arguments with the kernel itself (that is,
2343 to not rely on the boot loader to provide them.)
2345 To compile command line arguments into the kernel,
2346 set this option to 'Y', then fill in the
2347 boot arguments in CONFIG_CMDLINE.
2349 Systems with fully functional boot loaders (i.e. non-embedded)
2350 should leave this option set to 'N'.
2353 string "Built-in kernel command string"
2354 depends on CMDLINE_BOOL
2357 Enter arguments here that should be compiled into the kernel
2358 image and used at boot time. If the boot loader provides a
2359 command line at boot time, it is appended to this string to
2360 form the full kernel command line, when the system boots.
2362 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2363 change this behavior.
2365 In most cases, the command line (whether built-in or provided
2366 by the boot loader) should specify the device for the root
2369 config CMDLINE_OVERRIDE
2370 bool "Built-in command line overrides boot loader arguments"
2371 depends on CMDLINE_BOOL
2373 Set this option to 'Y' to have the kernel ignore the boot loader
2374 command line, and use ONLY the built-in command line.
2376 This is used to work around broken boot loaders. This should
2377 be set to 'N' under normal conditions.
2379 config MODIFY_LDT_SYSCALL
2380 bool "Enable the LDT (local descriptor table)" if EXPERT
2383 Linux can allow user programs to install a per-process x86
2384 Local Descriptor Table (LDT) using the modify_ldt(2) system
2385 call. This is required to run 16-bit or segmented code such as
2386 DOSEMU or some Wine programs. It is also used by some very old
2387 threading libraries.
2389 Enabling this feature adds a small amount of overhead to
2390 context switches and increases the low-level kernel attack
2391 surface. Disabling it removes the modify_ldt(2) system call.
2393 Saying 'N' here may make sense for embedded or server kernels.
2395 source "kernel/livepatch/Kconfig"
2399 config ARCH_HAS_ADD_PAGES
2401 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2403 config ARCH_ENABLE_MEMORY_HOTPLUG
2405 depends on X86_64 || (X86_32 && HIGHMEM)
2407 config ARCH_ENABLE_MEMORY_HOTREMOVE
2409 depends on MEMORY_HOTPLUG
2411 config USE_PERCPU_NUMA_NODE_ID
2415 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2417 depends on X86_64 || X86_PAE
2419 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2421 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2423 config ARCH_ENABLE_THP_MIGRATION
2425 depends on X86_64 && TRANSPARENT_HUGEPAGE
2427 menu "Power management and ACPI options"
2429 config ARCH_HIBERNATION_HEADER
2431 depends on HIBERNATION
2433 source "kernel/power/Kconfig"
2435 source "drivers/acpi/Kconfig"
2437 source "drivers/sfi/Kconfig"
2444 tristate "APM (Advanced Power Management) BIOS support"
2445 depends on X86_32 && PM_SLEEP
2447 APM is a BIOS specification for saving power using several different
2448 techniques. This is mostly useful for battery powered laptops with
2449 APM compliant BIOSes. If you say Y here, the system time will be
2450 reset after a RESUME operation, the /proc/apm device will provide
2451 battery status information, and user-space programs will receive
2452 notification of APM "events" (e.g. battery status change).
2454 If you select "Y" here, you can disable actual use of the APM
2455 BIOS by passing the "apm=off" option to the kernel at boot time.
2457 Note that the APM support is almost completely disabled for
2458 machines with more than one CPU.
2460 In order to use APM, you will need supporting software. For location
2461 and more information, read <file:Documentation/power/apm-acpi.txt>
2462 and the Battery Powered Linux mini-HOWTO, available from
2463 <http://www.tldp.org/docs.html#howto>.
2465 This driver does not spin down disk drives (see the hdparm(8)
2466 manpage ("man 8 hdparm") for that), and it doesn't turn off
2467 VESA-compliant "green" monitors.
2469 This driver does not support the TI 4000M TravelMate and the ACER
2470 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2471 desktop machines also don't have compliant BIOSes, and this driver
2472 may cause those machines to panic during the boot phase.
2474 Generally, if you don't have a battery in your machine, there isn't
2475 much point in using this driver and you should say N. If you get
2476 random kernel OOPSes or reboots that don't seem to be related to
2477 anything, try disabling/enabling this option (or disabling/enabling
2480 Some other things you should try when experiencing seemingly random,
2483 1) make sure that you have enough swap space and that it is
2485 2) pass the "no-hlt" option to the kernel
2486 3) switch on floating point emulation in the kernel and pass
2487 the "no387" option to the kernel
2488 4) pass the "floppy=nodma" option to the kernel
2489 5) pass the "mem=4M" option to the kernel (thereby disabling
2490 all but the first 4 MB of RAM)
2491 6) make sure that the CPU is not over clocked.
2492 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2493 8) disable the cache from your BIOS settings
2494 9) install a fan for the video card or exchange video RAM
2495 10) install a better fan for the CPU
2496 11) exchange RAM chips
2497 12) exchange the motherboard.
2499 To compile this driver as a module, choose M here: the
2500 module will be called apm.
2504 config APM_IGNORE_USER_SUSPEND
2505 bool "Ignore USER SUSPEND"
2507 This option will ignore USER SUSPEND requests. On machines with a
2508 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2509 series notebooks, it is necessary to say Y because of a BIOS bug.
2511 config APM_DO_ENABLE
2512 bool "Enable PM at boot time"
2514 Enable APM features at boot time. From page 36 of the APM BIOS
2515 specification: "When disabled, the APM BIOS does not automatically
2516 power manage devices, enter the Standby State, enter the Suspend
2517 State, or take power saving steps in response to CPU Idle calls."
2518 This driver will make CPU Idle calls when Linux is idle (unless this
2519 feature is turned off -- see "Do CPU IDLE calls", below). This
2520 should always save battery power, but more complicated APM features
2521 will be dependent on your BIOS implementation. You may need to turn
2522 this option off if your computer hangs at boot time when using APM
2523 support, or if it beeps continuously instead of suspending. Turn
2524 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2525 T400CDT. This is off by default since most machines do fine without
2530 bool "Make CPU Idle calls when idle"
2532 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2533 On some machines, this can activate improved power savings, such as
2534 a slowed CPU clock rate, when the machine is idle. These idle calls
2535 are made after the idle loop has run for some length of time (e.g.,
2536 333 mS). On some machines, this will cause a hang at boot time or
2537 whenever the CPU becomes idle. (On machines with more than one CPU,
2538 this option does nothing.)
2540 config APM_DISPLAY_BLANK
2541 bool "Enable console blanking using APM"
2543 Enable console blanking using the APM. Some laptops can use this to
2544 turn off the LCD backlight when the screen blanker of the Linux
2545 virtual console blanks the screen. Note that this is only used by
2546 the virtual console screen blanker, and won't turn off the backlight
2547 when using the X Window system. This also doesn't have anything to
2548 do with your VESA-compliant power-saving monitor. Further, this
2549 option doesn't work for all laptops -- it might not turn off your
2550 backlight at all, or it might print a lot of errors to the console,
2551 especially if you are using gpm.
2553 config APM_ALLOW_INTS
2554 bool "Allow interrupts during APM BIOS calls"
2556 Normally we disable external interrupts while we are making calls to
2557 the APM BIOS as a measure to lessen the effects of a badly behaving
2558 BIOS implementation. The BIOS should reenable interrupts if it
2559 needs to. Unfortunately, some BIOSes do not -- especially those in
2560 many of the newer IBM Thinkpads. If you experience hangs when you
2561 suspend, try setting this to Y. Otherwise, say N.
2565 source "drivers/cpufreq/Kconfig"
2567 source "drivers/cpuidle/Kconfig"
2569 source "drivers/idle/Kconfig"
2574 menu "Bus options (PCI etc.)"
2580 Find out whether you have a PCI motherboard. PCI is the name of a
2581 bus system, i.e. the way the CPU talks to the other stuff inside
2582 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2583 VESA. If you have PCI, say Y, otherwise N.
2586 prompt "PCI access mode"
2587 depends on X86_32 && PCI
2590 On PCI systems, the BIOS can be used to detect the PCI devices and
2591 determine their configuration. However, some old PCI motherboards
2592 have BIOS bugs and may crash if this is done. Also, some embedded
2593 PCI-based systems don't have any BIOS at all. Linux can also try to
2594 detect the PCI hardware directly without using the BIOS.
2596 With this option, you can specify how Linux should detect the
2597 PCI devices. If you choose "BIOS", the BIOS will be used,
2598 if you choose "Direct", the BIOS won't be used, and if you
2599 choose "MMConfig", then PCI Express MMCONFIG will be used.
2600 If you choose "Any", the kernel will try MMCONFIG, then the
2601 direct access method and falls back to the BIOS if that doesn't
2602 work. If unsure, go with the default, which is "Any".
2607 config PCI_GOMMCONFIG
2624 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2626 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2629 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2632 bool "Support mmconfig PCI config space access" if X86_64
2634 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2635 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2639 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2643 depends on PCI && XEN
2650 config MMCONF_FAM10H
2652 depends on X86_64 && PCI_MMCONFIG && ACPI
2654 config PCI_CNB20LE_QUIRK
2655 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2658 Read the PCI windows out of the CNB20LE host bridge. This allows
2659 PCI hotplug to work on systems with the CNB20LE chipset which do
2662 There's no public spec for this chipset, and this functionality
2663 is known to be incomplete.
2665 You should say N unless you know you need this.
2667 source "drivers/pci/Kconfig"
2670 bool "ISA bus support on modern systems" if EXPERT
2672 Expose ISA bus device drivers and options available for selection and
2673 configuration. Enable this option if your target machine has an ISA
2674 bus. ISA is an older system, displaced by PCI and newer bus
2675 architectures -- if your target machine is modern, it probably does
2676 not have an ISA bus.
2680 # x86_64 have no ISA slots, but can have ISA-style DMA.
2682 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2685 Enables ISA-style DMA support for devices requiring such controllers.
2693 Find out whether you have ISA slots on your motherboard. ISA is the
2694 name of a bus system, i.e. the way the CPU talks to the other stuff
2695 inside your box. Other bus systems are PCI, EISA, MicroChannel
2696 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2697 newer boards don't support it. If you have ISA, say Y, otherwise N.
2703 The Extended Industry Standard Architecture (EISA) bus was
2704 developed as an open alternative to the IBM MicroChannel bus.
2706 The EISA bus provided some of the features of the IBM MicroChannel
2707 bus while maintaining backward compatibility with cards made for
2708 the older ISA bus. The EISA bus saw limited use between 1988 and
2709 1995 when it was made obsolete by the PCI bus.
2711 Say Y here if you are building a kernel for an EISA-based machine.
2715 source "drivers/eisa/Kconfig"
2718 tristate "NatSemi SCx200 support"
2720 This provides basic support for National Semiconductor's
2721 (now AMD's) Geode processors. The driver probes for the
2722 PCI-IDs of several on-chip devices, so its a good dependency
2723 for other scx200_* drivers.
2725 If compiled as a module, the driver is named scx200.
2727 config SCx200HR_TIMER
2728 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2732 This driver provides a clocksource built upon the on-chip
2733 27MHz high-resolution timer. Its also a workaround for
2734 NSC Geode SC-1100's buggy TSC, which loses time when the
2735 processor goes idle (as is done by the scheduler). The
2736 other workaround is idle=poll boot option.
2739 bool "One Laptop Per Child support"
2746 Add support for detecting the unique features of the OLPC
2750 bool "OLPC XO-1 Power Management"
2751 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2753 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2756 bool "OLPC XO-1 Real Time Clock"
2757 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2759 Add support for the XO-1 real time clock, which can be used as a
2760 programmable wakeup source.
2763 bool "OLPC XO-1 SCI extras"
2764 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2768 Add support for SCI-based features of the OLPC XO-1 laptop:
2769 - EC-driven system wakeups
2773 - AC adapter status updates
2774 - Battery status updates
2776 config OLPC_XO15_SCI
2777 bool "OLPC XO-1.5 SCI extras"
2778 depends on OLPC && ACPI
2781 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2782 - EC-driven system wakeups
2783 - AC adapter status updates
2784 - Battery status updates
2787 bool "PCEngines ALIX System Support (LED setup)"
2790 This option enables system support for the PCEngines ALIX.
2791 At present this just sets up LEDs for GPIO control on
2792 ALIX2/3/6 boards. However, other system specific setup should
2795 Note: You must still enable the drivers for GPIO and LED support
2796 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2798 Note: You have to set alix.force=1 for boards with Award BIOS.
2801 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2804 This option enables system support for the Soekris Engineering net5501.
2807 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2811 This option enables system support for the Traverse Technologies GEOS.
2814 bool "Technologic Systems TS-5500 platform support"
2816 select CHECK_SIGNATURE
2820 This option enables system support for the Technologic Systems TS-5500.
2826 depends on CPU_SUP_AMD && PCI
2828 source "drivers/pcmcia/Kconfig"
2831 tristate "RapidIO support"
2834 If enabled this option will include drivers and the core
2835 infrastructure code to support RapidIO interconnect devices.
2837 source "drivers/rapidio/Kconfig"
2840 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2842 Firmwares often provide initial graphics framebuffers so the BIOS,
2843 bootloader or kernel can show basic video-output during boot for
2844 user-guidance and debugging. Historically, x86 used the VESA BIOS
2845 Extensions and EFI-framebuffers for this, which are mostly limited
2847 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2848 framebuffers so the new generic system-framebuffer drivers can be
2849 used on x86. If the framebuffer is not compatible with the generic
2850 modes, it is advertised as fallback platform framebuffer so legacy
2851 drivers like efifb, vesafb and uvesafb can pick it up.
2852 If this option is not selected, all system framebuffers are always
2853 marked as fallback platform framebuffers as usual.
2855 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2856 not be able to pick up generic system framebuffers if this option
2857 is selected. You are highly encouraged to enable simplefb as
2858 replacement if you select this option. simplefb can correctly deal
2859 with generic system framebuffers. But you should still keep vesafb
2860 and others enabled as fallback if a system framebuffer is
2861 incompatible with simplefb.
2868 menu "Binary Emulations"
2870 config IA32_EMULATION
2871 bool "IA32 Emulation"
2873 select ARCH_WANT_OLD_COMPAT_IPC
2875 select COMPAT_BINFMT_ELF
2876 select COMPAT_OLD_SIGACTION
2878 Include code to run legacy 32-bit programs under a
2879 64-bit kernel. You should likely turn this on, unless you're
2880 100% sure that you don't have any 32-bit programs left.
2883 tristate "IA32 a.out support"
2884 depends on IA32_EMULATION
2886 Support old a.out binaries in the 32bit emulation.
2889 bool "x32 ABI for 64-bit mode"
2892 Include code to run binaries for the x32 native 32-bit ABI
2893 for 64-bit processors. An x32 process gets access to the
2894 full 64-bit register file and wide data path while leaving
2895 pointers at 32 bits for smaller memory footprint.
2897 You will need a recent binutils (2.22 or later) with
2898 elf32_x86_64 support enabled to compile a kernel with this
2903 depends on IA32_EMULATION || X86_32
2905 select OLD_SIGSUSPEND3
2909 depends on IA32_EMULATION || X86_X32
2912 config COMPAT_FOR_U64_ALIGNMENT
2915 config SYSVIPC_COMPAT
2923 config HAVE_ATOMIC_IOMAP
2927 config X86_DEV_DMA_OPS
2929 depends on X86_64 || STA2X11
2931 config X86_DMA_REMAP
2935 config HAVE_GENERIC_GUP
2938 source "drivers/firmware/Kconfig"
2940 source "arch/x86/kvm/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob