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_TRACEHOOK
133 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
134 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
135 select HAVE_ARCH_VMAP_STACK if X86_64
136 select HAVE_ARCH_WITHIN_STACK_FRAMES
137 select HAVE_CMPXCHG_DOUBLE
138 select HAVE_CMPXCHG_LOCAL
139 select HAVE_CONTEXT_TRACKING if X86_64
140 select HAVE_COPY_THREAD_TLS
141 select HAVE_C_RECORDMCOUNT
142 select HAVE_DEBUG_KMEMLEAK
143 select HAVE_DEBUG_STACKOVERFLOW
144 select HAVE_DMA_CONTIGUOUS
145 select HAVE_DYNAMIC_FTRACE
146 select HAVE_DYNAMIC_FTRACE_WITH_REGS
148 select HAVE_EFFICIENT_UNALIGNED_ACCESS
149 select HAVE_EXIT_THREAD
150 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
151 select HAVE_FTRACE_MCOUNT_RECORD
152 select HAVE_FUNCTION_GRAPH_TRACER
153 select HAVE_FUNCTION_TRACER
154 select HAVE_GCC_PLUGINS
155 select HAVE_HW_BREAKPOINT
157 select HAVE_IOREMAP_PROT
158 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
159 select HAVE_IRQ_TIME_ACCOUNTING
160 select HAVE_KERNEL_BZIP2
161 select HAVE_KERNEL_GZIP
162 select HAVE_KERNEL_LZ4
163 select HAVE_KERNEL_LZMA
164 select HAVE_KERNEL_LZO
165 select HAVE_KERNEL_XZ
167 select HAVE_KPROBES_ON_FTRACE
168 select HAVE_FUNCTION_ERROR_INJECTION
169 select HAVE_KRETPROBES
171 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_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
190 select HAVE_STACK_VALIDATION if X86_64
192 select HAVE_SYSCALL_TRACEPOINTS
193 select HAVE_UNSTABLE_SCHED_CLOCK
194 select HAVE_USER_RETURN_NOTIFIER
195 select HOTPLUG_SMT if SMP
196 select IRQ_FORCED_THREADING
197 select NEED_SG_DMA_LENGTH
198 select PCI_LOCKLESS_CONFIG
201 select RTC_MC146818_LIB
204 select SYSCTL_EXCEPTION_TRACE
205 select THREAD_INFO_IN_TASK
206 select USER_STACKTRACE_SUPPORT
208 select X86_FEATURE_NAMES if PROC_FS
210 config INSTRUCTION_DECODER
212 depends on KPROBES || PERF_EVENTS || UPROBES
216 default "elf32-i386" if X86_32
217 default "elf64-x86-64" if X86_64
219 config ARCH_DEFCONFIG
221 default "arch/x86/configs/i386_defconfig" if X86_32
222 default "arch/x86/configs/x86_64_defconfig" if X86_64
224 config LOCKDEP_SUPPORT
227 config STACKTRACE_SUPPORT
233 config ARCH_MMAP_RND_BITS_MIN
237 config ARCH_MMAP_RND_BITS_MAX
241 config ARCH_MMAP_RND_COMPAT_BITS_MIN
244 config ARCH_MMAP_RND_COMPAT_BITS_MAX
250 config GENERIC_ISA_DMA
252 depends on ISA_DMA_API
257 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
259 config GENERIC_BUG_RELATIVE_POINTERS
262 config GENERIC_HWEIGHT
265 config ARCH_MAY_HAVE_PC_FDC
267 depends on ISA_DMA_API
269 config RWSEM_XCHGADD_ALGORITHM
272 config GENERIC_CALIBRATE_DELAY
275 config ARCH_HAS_CPU_RELAX
278 config ARCH_HAS_CACHE_LINE_SIZE
281 config ARCH_HAS_FILTER_PGPROT
284 config HAVE_SETUP_PER_CPU_AREA
287 config NEED_PER_CPU_EMBED_FIRST_CHUNK
290 config NEED_PER_CPU_PAGE_FIRST_CHUNK
293 config ARCH_HIBERNATION_POSSIBLE
296 config ARCH_SUSPEND_POSSIBLE
299 config ARCH_WANT_HUGE_PMD_SHARE
302 config ARCH_WANT_GENERAL_HUGETLB
311 config ARCH_SUPPORTS_OPTIMIZED_INLINING
314 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
317 config KASAN_SHADOW_OFFSET
320 default 0xdffffc0000000000
322 config HAVE_INTEL_TXT
324 depends on INTEL_IOMMU && ACPI
328 depends on X86_32 && SMP
332 depends on X86_64 && SMP
334 config X86_32_LAZY_GS
336 depends on X86_32 && !STACKPROTECTOR
338 config ARCH_SUPPORTS_UPROBES
341 config FIX_EARLYCON_MEM
344 config DYNAMIC_PHYSICAL_MASK
347 config PGTABLE_LEVELS
349 default 5 if X86_5LEVEL
354 config CC_HAS_SANE_STACKPROTECTOR
356 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
357 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
359 We have to make sure stack protector is unconditionally disabled if
360 the compiler produces broken code.
362 menu "Processor type and features"
365 bool "DMA memory allocation support" if EXPERT
368 DMA memory allocation support allows devices with less than 32-bit
369 addressing to allocate within the first 16MB of address space.
370 Disable if no such devices will be used.
375 bool "Symmetric multi-processing support"
377 This enables support for systems with more than one CPU. If you have
378 a system with only one CPU, say N. If you have a system with more
381 If you say N here, the kernel will run on uni- and multiprocessor
382 machines, but will use only one CPU of a multiprocessor machine. If
383 you say Y here, the kernel will run on many, but not all,
384 uniprocessor machines. On a uniprocessor machine, the kernel
385 will run faster if you say N here.
387 Note that if you say Y here and choose architecture "586" or
388 "Pentium" under "Processor family", the kernel will not work on 486
389 architectures. Similarly, multiprocessor kernels for the "PPro"
390 architecture may not work on all Pentium based boards.
392 People using multiprocessor machines who say Y here should also say
393 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
394 Management" code will be disabled if you say Y here.
396 See also <file:Documentation/x86/i386/IO-APIC.txt>,
397 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
398 <http://www.tldp.org/docs.html#howto>.
400 If you don't know what to do here, say N.
402 config X86_FEATURE_NAMES
403 bool "Processor feature human-readable names" if EMBEDDED
406 This option compiles in a table of x86 feature bits and corresponding
407 names. This is required to support /proc/cpuinfo and a few kernel
408 messages. You can disable this to save space, at the expense of
409 making those few kernel messages show numeric feature bits instead.
414 bool "Support x2apic"
415 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
417 This enables x2apic support on CPUs that have this feature.
419 This allows 32-bit apic IDs (so it can support very large systems),
420 and accesses the local apic via MSRs not via mmio.
422 If you don't know what to do here, say N.
425 bool "Enable MPS table" if ACPI || SFI
427 depends on X86_LOCAL_APIC
429 For old smp systems that do not have proper acpi support. Newer systems
430 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
434 depends on X86_GOLDFISH
437 bool "Avoid speculative indirect branches in kernel"
439 select STACK_VALIDATION if HAVE_STACK_VALIDATION
441 Compile kernel with the retpoline compiler options to guard against
442 kernel-to-user data leaks by avoiding speculative indirect
443 branches. Requires a compiler with -mindirect-branch=thunk-extern
444 support for full protection. The kernel may run slower.
446 Without compiler support, at least indirect branches in assembler
447 code are eliminated. Since this includes the syscall entry path,
448 it is not entirely pointless.
451 bool "Intel Resource Director Technology support"
452 depends on X86 && CPU_SUP_INTEL
455 Select to enable resource allocation and monitoring which are
456 sub-features of Intel Resource Director Technology(RDT). More
457 information about RDT can be found in the Intel x86
458 Architecture Software Developer Manual.
464 bool "Support for big SMP systems with more than 8 CPUs"
467 This option is needed for the systems that have more than 8 CPUs
469 config X86_EXTENDED_PLATFORM
470 bool "Support for extended (non-PC) x86 platforms"
473 If you disable this option then the kernel will only support
474 standard PC platforms. (which covers the vast majority of
477 If you enable this option then you'll be able to select support
478 for the following (non-PC) 32 bit x86 platforms:
479 Goldfish (Android emulator)
482 SGI 320/540 (Visual Workstation)
483 STA2X11-based (e.g. Northville)
484 Moorestown MID devices
486 If you have one of these systems, or if you want to build a
487 generic distribution kernel, say Y here - otherwise say N.
491 config X86_EXTENDED_PLATFORM
492 bool "Support for extended (non-PC) x86 platforms"
495 If you disable this option then the kernel will only support
496 standard PC platforms. (which covers the vast majority of
499 If you enable this option then you'll be able to select support
500 for the following (non-PC) 64 bit x86 platforms:
505 If you have one of these systems, or if you want to build a
506 generic distribution kernel, say Y here - otherwise say N.
508 # This is an alphabetically sorted list of 64 bit extended platforms
509 # Please maintain the alphabetic order if and when there are additions
511 bool "Numascale NumaChip"
513 depends on X86_EXTENDED_PLATFORM
516 depends on X86_X2APIC
517 depends on PCI_MMCONFIG
519 Adds support for Numascale NumaChip large-SMP systems. Needed to
520 enable more than ~168 cores.
521 If you don't have one of these, you should say N here.
525 select HYPERVISOR_GUEST
528 depends on X86_64 && PCI
529 depends on X86_EXTENDED_PLATFORM
532 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
533 supposed to run on these EM64T-based machines. Only choose this option
534 if you have one of these machines.
537 bool "SGI Ultraviolet"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
545 This option is needed in order to support SGI Ultraviolet systems.
546 If you don't have one of these, you should say N here.
548 # Following is an alphabetically sorted list of 32 bit extended platforms
549 # Please maintain the alphabetic order if and when there are additions
552 bool "Goldfish (Virtual Platform)"
553 depends on X86_EXTENDED_PLATFORM
555 Enable support for the Goldfish virtual platform used primarily
556 for Android development. Unless you are building for the Android
557 Goldfish emulator say N here.
560 bool "CE4100 TV platform"
562 depends on PCI_GODIRECT
563 depends on X86_IO_APIC
565 depends on X86_EXTENDED_PLATFORM
566 select X86_REBOOTFIXUPS
568 select OF_EARLY_FLATTREE
570 Select for the Intel CE media processor (CE4100) SOC.
571 This option compiles in support for the CE4100 SOC for settop
572 boxes and media devices.
575 bool "Intel MID platform support"
576 depends on X86_EXTENDED_PLATFORM
577 depends on X86_PLATFORM_DEVICES
579 depends on X86_64 || (PCI_GOANY && X86_32)
580 depends on X86_IO_APIC
586 select MFD_INTEL_MSIC
588 Select to build a kernel capable of supporting Intel MID (Mobile
589 Internet Device) platform systems which do not have the PCI legacy
590 interfaces. If you are building for a PC class system say N here.
592 Intel MID platforms are based on an Intel processor and chipset which
593 consume less power than most of the x86 derivatives.
595 config X86_INTEL_QUARK
596 bool "Intel Quark platform support"
598 depends on X86_EXTENDED_PLATFORM
599 depends on X86_PLATFORM_DEVICES
603 depends on X86_IO_APIC
608 Select to include support for Quark X1000 SoC.
609 Say Y here if you have a Quark based system such as the Arduino
610 compatible Intel Galileo.
612 config X86_INTEL_LPSS
613 bool "Intel Low Power Subsystem Support"
614 depends on X86 && ACPI
619 Select to build support for Intel Low Power Subsystem such as
620 found on Intel Lynxpoint PCH. Selecting this option enables
621 things like clock tree (common clock framework) and pincontrol
622 which are needed by the LPSS peripheral drivers.
624 config X86_AMD_PLATFORM_DEVICE
625 bool "AMD ACPI2Platform devices support"
630 Select to interpret AMD specific ACPI device to platform device
631 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
632 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
633 implemented under PINCTRL subsystem.
636 tristate "Intel SoC IOSF Sideband support for SoC platforms"
639 This option enables sideband register access support for Intel SoC
640 platforms. On these platforms the IOSF sideband is used in lieu of
641 MSR's for some register accesses, mostly but not limited to thermal
642 and power. Drivers may query the availability of this device to
643 determine if they need the sideband in order to work on these
644 platforms. The sideband is available on the following SoC products.
645 This list is not meant to be exclusive.
650 You should say Y if you are running a kernel on one of these SoC's.
652 config IOSF_MBI_DEBUG
653 bool "Enable IOSF sideband access through debugfs"
654 depends on IOSF_MBI && DEBUG_FS
656 Select this option to expose the IOSF sideband access registers (MCR,
657 MDR, MCRX) through debugfs to write and read register information from
658 different units on the SoC. This is most useful for obtaining device
659 state information for debug and analysis. As this is a general access
660 mechanism, users of this option would have specific knowledge of the
661 device they want to access.
663 If you don't require the option or are in doubt, say N.
666 bool "RDC R-321x SoC"
668 depends on X86_EXTENDED_PLATFORM
670 select X86_REBOOTFIXUPS
672 This option is needed for RDC R-321x system-on-chip, also known
674 If you don't have one of these chips, you should say N here.
676 config X86_32_NON_STANDARD
677 bool "Support non-standard 32-bit SMP architectures"
678 depends on X86_32 && SMP
679 depends on X86_EXTENDED_PLATFORM
681 This option compiles in the bigsmp and STA2X11 default
682 subarchitectures. It is intended for a generic binary
683 kernel. If you select them all, kernel will probe it one by
684 one and will fallback to default.
686 # Alphabetically sorted list of Non standard 32 bit platforms
688 config X86_SUPPORTS_MEMORY_FAILURE
690 # MCE code calls memory_failure():
692 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
693 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
694 depends on X86_64 || !SPARSEMEM
695 select ARCH_SUPPORTS_MEMORY_FAILURE
698 bool "STA2X11 Companion Chip Support"
699 depends on X86_32_NON_STANDARD && PCI
700 select ARCH_HAS_PHYS_TO_DMA
701 select X86_DEV_DMA_OPS
707 This adds support for boards based on the STA2X11 IO-Hub,
708 a.k.a. "ConneXt". The chip is used in place of the standard
709 PC chipset, so all "standard" peripherals are missing. If this
710 option is selected the kernel will still be able to boot on
711 standard PC machines.
714 tristate "Eurobraille/Iris poweroff module"
717 The Iris machines from EuroBraille do not have APM or ACPI support
718 to shut themselves down properly. A special I/O sequence is
719 needed to do so, which is what this module does at
722 This is only for Iris machines from EuroBraille.
726 config SCHED_OMIT_FRAME_POINTER
728 prompt "Single-depth WCHAN output"
731 Calculate simpler /proc/<PID>/wchan values. If this option
732 is disabled then wchan values will recurse back to the
733 caller function. This provides more accurate wchan values,
734 at the expense of slightly more scheduling overhead.
736 If in doubt, say "Y".
738 menuconfig HYPERVISOR_GUEST
739 bool "Linux guest support"
741 Say Y here to enable options for running Linux under various hyper-
742 visors. This option enables basic hypervisor detection and platform
745 If you say N, all options in this submenu will be skipped and
746 disabled, and Linux guest support won't be built in.
751 bool "Enable paravirtualization code"
753 This changes the kernel so it can modify itself when it is run
754 under a hypervisor, potentially improving performance significantly
755 over full virtualization. However, when run without a hypervisor
756 the kernel is theoretically slower and slightly larger.
761 config PARAVIRT_DEBUG
762 bool "paravirt-ops debugging"
763 depends on PARAVIRT && DEBUG_KERNEL
765 Enable to debug paravirt_ops internals. Specifically, BUG if
766 a paravirt_op is missing when it is called.
768 config PARAVIRT_SPINLOCKS
769 bool "Paravirtualization layer for spinlocks"
770 depends on PARAVIRT && SMP
772 Paravirtualized spinlocks allow a pvops backend to replace the
773 spinlock implementation with something virtualization-friendly
774 (for example, block the virtual CPU rather than spinning).
776 It has a minimal impact on native kernels and gives a nice performance
777 benefit on paravirtualized KVM / Xen kernels.
779 If you are unsure how to answer this question, answer Y.
781 config QUEUED_LOCK_STAT
782 bool "Paravirt queued spinlock statistics"
783 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
785 Enable the collection of statistical data on the slowpath
786 behavior of paravirtualized queued spinlocks and report
789 source "arch/x86/xen/Kconfig"
792 bool "KVM Guest support (including kvmclock)"
794 select PARAVIRT_CLOCK
797 This option enables various optimizations for running under the KVM
798 hypervisor. It includes a paravirtualized clock, so that instead
799 of relying on a PIT (or probably other) emulation by the
800 underlying device model, the host provides the guest with
801 timing infrastructure such as time of day, and system time
804 bool "Enable debug information for KVM Guests in debugfs"
805 depends on KVM_GUEST && DEBUG_FS
807 This option enables collection of various statistics for KVM guest.
808 Statistics are displayed in debugfs filesystem. Enabling this option
809 may incur significant overhead.
811 config PARAVIRT_TIME_ACCOUNTING
812 bool "Paravirtual steal time accounting"
815 Select this option to enable fine granularity task steal time
816 accounting. Time spent executing other tasks in parallel with
817 the current vCPU is discounted from the vCPU power. To account for
818 that, there can be a small performance impact.
820 If in doubt, say N here.
822 config PARAVIRT_CLOCK
825 config JAILHOUSE_GUEST
826 bool "Jailhouse non-root cell support"
827 depends on X86_64 && PCI
830 This option allows to run Linux as guest in a Jailhouse non-root
831 cell. You can leave this option disabled if you only want to start
832 Jailhouse and run Linux afterwards in the root cell.
834 endif #HYPERVISOR_GUEST
839 source "arch/x86/Kconfig.cpu"
843 prompt "HPET Timer Support" if X86_32
845 Use the IA-PC HPET (High Precision Event Timer) to manage
846 time in preference to the PIT and RTC, if a HPET is
848 HPET is the next generation timer replacing legacy 8254s.
849 The HPET provides a stable time base on SMP
850 systems, unlike the TSC, but it is more expensive to access,
851 as it is off-chip. The interface used is documented
852 in the HPET spec, revision 1.
854 You can safely choose Y here. However, HPET will only be
855 activated if the platform and the BIOS support this feature.
856 Otherwise the 8254 will be used for timing services.
858 Choose N to continue using the legacy 8254 timer.
860 config HPET_EMULATE_RTC
862 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
865 def_bool y if X86_INTEL_MID
866 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
868 depends on X86_INTEL_MID && SFI
870 APB timer is the replacement for 8254, HPET on X86 MID platforms.
871 The APBT provides a stable time base on SMP
872 systems, unlike the TSC, but it is more expensive to access,
873 as it is off-chip. APB timers are always running regardless of CPU
874 C states, they are used as per CPU clockevent device when possible.
876 # Mark as expert because too many people got it wrong.
877 # The code disables itself when not needed.
880 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
881 bool "Enable DMI scanning" if EXPERT
883 Enabled scanning of DMI to identify machine quirks. Say Y
884 here unless you have verified that your setup is not
885 affected by entries in the DMI blacklist. Required by PNP
889 bool "Old AMD GART IOMMU support"
892 depends on X86_64 && PCI && AMD_NB
894 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
895 GART based hardware IOMMUs.
897 The GART supports full DMA access for devices with 32-bit access
898 limitations, on systems with more than 3 GB. This is usually needed
899 for USB, sound, many IDE/SATA chipsets and some other devices.
901 Newer systems typically have a modern AMD IOMMU, supported via
902 the CONFIG_AMD_IOMMU=y config option.
904 In normal configurations this driver is only active when needed:
905 there's more than 3 GB of memory and the system contains a
906 32-bit limited device.
911 bool "IBM Calgary IOMMU support"
914 depends on X86_64 && PCI
916 Support for hardware IOMMUs in IBM's xSeries x366 and x460
917 systems. Needed to run systems with more than 3GB of memory
918 properly with 32-bit PCI devices that do not support DAC
919 (Double Address Cycle). Calgary also supports bus level
920 isolation, where all DMAs pass through the IOMMU. This
921 prevents them from going anywhere except their intended
922 destination. This catches hard-to-find kernel bugs and
923 mis-behaving drivers and devices that do not use the DMA-API
924 properly to set up their DMA buffers. The IOMMU can be
925 turned off at boot time with the iommu=off parameter.
926 Normally the kernel will make the right choice by itself.
929 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
931 prompt "Should Calgary be enabled by default?"
932 depends on CALGARY_IOMMU
934 Should Calgary be enabled by default? if you choose 'y', Calgary
935 will be used (if it exists). If you choose 'n', Calgary will not be
936 used even if it exists. If you choose 'n' and would like to use
937 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
941 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
942 depends on X86_64 && SMP && DEBUG_KERNEL
943 select CPUMASK_OFFSTACK
945 Enable maximum number of CPUS and NUMA Nodes for this architecture.
949 # The maximum number of CPUs supported:
951 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
952 # and which can be configured interactively in the
953 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
955 # The ranges are different on 32-bit and 64-bit kernels, depending on
956 # hardware capabilities and scalability features of the kernel.
958 # ( If MAXSMP is enabled we just use the highest possible value and disable
959 # interactive configuration. )
962 config NR_CPUS_RANGE_BEGIN
964 default NR_CPUS_RANGE_END if MAXSMP
968 config NR_CPUS_RANGE_END
971 default 64 if SMP && X86_BIGSMP
972 default 8 if SMP && !X86_BIGSMP
975 config NR_CPUS_RANGE_END
978 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
979 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
982 config NR_CPUS_DEFAULT
985 default 32 if X86_BIGSMP
989 config NR_CPUS_DEFAULT
992 default 8192 if MAXSMP
997 int "Maximum number of CPUs" if SMP && !MAXSMP
998 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
999 default NR_CPUS_DEFAULT
1001 This allows you to specify the maximum number of CPUs which this
1002 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1003 supported value is 8192, otherwise the maximum value is 512. The
1004 minimum value which makes sense is 2.
1006 This is purely to save memory: each supported CPU adds about 8KB
1007 to the kernel image.
1010 bool "SMT (Hyperthreading) scheduler support"
1013 SMT scheduler support improves the CPU scheduler's decision making
1014 when dealing with Intel Pentium 4 chips with HyperThreading at a
1015 cost of slightly increased overhead in some places. If unsure say
1020 prompt "Multi-core scheduler support"
1023 Multi-core scheduler support improves the CPU scheduler's decision
1024 making when dealing with multi-core CPU chips at a cost of slightly
1025 increased overhead in some places. If unsure say N here.
1027 config SCHED_MC_PRIO
1028 bool "CPU core priorities scheduler support"
1029 depends on SCHED_MC && CPU_SUP_INTEL
1030 select X86_INTEL_PSTATE
1034 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1035 core ordering determined at manufacturing time, which allows
1036 certain cores to reach higher turbo frequencies (when running
1037 single threaded workloads) than others.
1039 Enabling this kernel feature teaches the scheduler about
1040 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1041 scheduler's CPU selection logic accordingly, so that higher
1042 overall system performance can be achieved.
1044 This feature will have no effect on CPUs without this feature.
1046 If unsure say Y here.
1050 depends on !SMP && X86_LOCAL_APIC
1053 bool "Local APIC support on uniprocessors" if !PCI_MSI
1055 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1057 A local APIC (Advanced Programmable Interrupt Controller) is an
1058 integrated interrupt controller in the CPU. If you have a single-CPU
1059 system which has a processor with a local APIC, you can say Y here to
1060 enable and use it. If you say Y here even though your machine doesn't
1061 have a local APIC, then the kernel will still run with no slowdown at
1062 all. The local APIC supports CPU-generated self-interrupts (timer,
1063 performance counters), and the NMI watchdog which detects hard
1066 config X86_UP_IOAPIC
1067 bool "IO-APIC support on uniprocessors"
1068 depends on X86_UP_APIC
1070 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1071 SMP-capable replacement for PC-style interrupt controllers. Most
1072 SMP systems and many recent uniprocessor systems have one.
1074 If you have a single-CPU system with an IO-APIC, you can say Y here
1075 to use it. If you say Y here even though your machine doesn't have
1076 an IO-APIC, then the kernel will still run with no slowdown at all.
1078 config X86_LOCAL_APIC
1080 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1081 select IRQ_DOMAIN_HIERARCHY
1082 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1086 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1088 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1089 bool "Reroute for broken boot IRQs"
1090 depends on X86_IO_APIC
1092 This option enables a workaround that fixes a source of
1093 spurious interrupts. This is recommended when threaded
1094 interrupt handling is used on systems where the generation of
1095 superfluous "boot interrupts" cannot be disabled.
1097 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1098 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1099 kernel does during interrupt handling). On chipsets where this
1100 boot IRQ generation cannot be disabled, this workaround keeps
1101 the original IRQ line masked so that only the equivalent "boot
1102 IRQ" is delivered to the CPUs. The workaround also tells the
1103 kernel to set up the IRQ handler on the boot IRQ line. In this
1104 way only one interrupt is delivered to the kernel. Otherwise
1105 the spurious second interrupt may cause the kernel to bring
1106 down (vital) interrupt lines.
1108 Only affects "broken" chipsets. Interrupt sharing may be
1109 increased on these systems.
1112 bool "Machine Check / overheating reporting"
1113 select GENERIC_ALLOCATOR
1116 Machine Check support allows the processor to notify the
1117 kernel if it detects a problem (e.g. overheating, data corruption).
1118 The action the kernel takes depends on the severity of the problem,
1119 ranging from warning messages to halting the machine.
1121 config X86_MCELOG_LEGACY
1122 bool "Support for deprecated /dev/mcelog character device"
1125 Enable support for /dev/mcelog which is needed by the old mcelog
1126 userspace logging daemon. Consider switching to the new generation
1129 config X86_MCE_INTEL
1131 prompt "Intel MCE features"
1132 depends on X86_MCE && X86_LOCAL_APIC
1134 Additional support for intel specific MCE features such as
1135 the thermal monitor.
1139 prompt "AMD MCE features"
1140 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1142 Additional support for AMD specific MCE features such as
1143 the DRAM Error Threshold.
1145 config X86_ANCIENT_MCE
1146 bool "Support for old Pentium 5 / WinChip machine checks"
1147 depends on X86_32 && X86_MCE
1149 Include support for machine check handling on old Pentium 5 or WinChip
1150 systems. These typically need to be enabled explicitly on the command
1153 config X86_MCE_THRESHOLD
1154 depends on X86_MCE_AMD || X86_MCE_INTEL
1157 config X86_MCE_INJECT
1158 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1159 tristate "Machine check injector support"
1161 Provide support for injecting machine checks for testing purposes.
1162 If you don't know what a machine check is and you don't do kernel
1163 QA it is safe to say n.
1165 config X86_THERMAL_VECTOR
1167 depends on X86_MCE_INTEL
1169 source "arch/x86/events/Kconfig"
1171 config X86_LEGACY_VM86
1172 bool "Legacy VM86 support"
1175 This option allows user programs to put the CPU into V8086
1176 mode, which is an 80286-era approximation of 16-bit real mode.
1178 Some very old versions of X and/or vbetool require this option
1179 for user mode setting. Similarly, DOSEMU will use it if
1180 available to accelerate real mode DOS programs. However, any
1181 recent version of DOSEMU, X, or vbetool should be fully
1182 functional even without kernel VM86 support, as they will all
1183 fall back to software emulation. Nevertheless, if you are using
1184 a 16-bit DOS program where 16-bit performance matters, vm86
1185 mode might be faster than emulation and you might want to
1188 Note that any app that works on a 64-bit kernel is unlikely to
1189 need this option, as 64-bit kernels don't, and can't, support
1190 V8086 mode. This option is also unrelated to 16-bit protected
1191 mode and is not needed to run most 16-bit programs under Wine.
1193 Enabling this option increases the complexity of the kernel
1194 and slows down exception handling a tiny bit.
1196 If unsure, say N here.
1200 default X86_LEGACY_VM86
1203 bool "Enable support for 16-bit segments" if EXPERT
1205 depends on MODIFY_LDT_SYSCALL
1207 This option is required by programs like Wine to run 16-bit
1208 protected mode legacy code on x86 processors. Disabling
1209 this option saves about 300 bytes on i386, or around 6K text
1210 plus 16K runtime memory on x86-64,
1214 depends on X86_16BIT && X86_32
1218 depends on X86_16BIT && X86_64
1220 config X86_VSYSCALL_EMULATION
1221 bool "Enable vsyscall emulation" if EXPERT
1225 This enables emulation of the legacy vsyscall page. Disabling
1226 it is roughly equivalent to booting with vsyscall=none, except
1227 that it will also disable the helpful warning if a program
1228 tries to use a vsyscall. With this option set to N, offending
1229 programs will just segfault, citing addresses of the form
1232 This option is required by many programs built before 2013, and
1233 care should be used even with newer programs if set to N.
1235 Disabling this option saves about 7K of kernel size and
1236 possibly 4K of additional runtime pagetable memory.
1239 tristate "Toshiba Laptop support"
1242 This adds a driver to safely access the System Management Mode of
1243 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1244 not work on models with a Phoenix BIOS. The System Management Mode
1245 is used to set the BIOS and power saving options on Toshiba portables.
1247 For information on utilities to make use of this driver see the
1248 Toshiba Linux utilities web site at:
1249 <http://www.buzzard.org.uk/toshiba/>.
1251 Say Y if you intend to run this kernel on a Toshiba portable.
1255 tristate "Dell i8k legacy laptop support"
1257 select SENSORS_DELL_SMM
1259 This option enables legacy /proc/i8k userspace interface in hwmon
1260 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1261 temperature and allows controlling fan speeds of Dell laptops via
1262 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1263 it reports also power and hotkey status. For fan speed control is
1264 needed userspace package i8kutils.
1266 Say Y if you intend to run this kernel on old Dell laptops or want to
1267 use userspace package i8kutils.
1270 config X86_REBOOTFIXUPS
1271 bool "Enable X86 board specific fixups for reboot"
1274 This enables chipset and/or board specific fixups to be done
1275 in order to get reboot to work correctly. This is only needed on
1276 some combinations of hardware and BIOS. The symptom, for which
1277 this config is intended, is when reboot ends with a stalled/hung
1280 Currently, the only fixup is for the Geode machines using
1281 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1283 Say Y if you want to enable the fixup. Currently, it's safe to
1284 enable this option even if you don't need it.
1288 bool "CPU microcode loading support"
1290 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1293 If you say Y here, you will be able to update the microcode on
1294 Intel and AMD processors. The Intel support is for the IA32 family,
1295 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1296 AMD support is for families 0x10 and later. You will obviously need
1297 the actual microcode binary data itself which is not shipped with
1300 The preferred method to load microcode from a detached initrd is described
1301 in Documentation/x86/microcode.txt. For that you need to enable
1302 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1303 initrd for microcode blobs.
1305 In addition, you can build the microcode into the kernel. For that you
1306 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1309 config MICROCODE_INTEL
1310 bool "Intel microcode loading support"
1311 depends on MICROCODE
1315 This options enables microcode patch loading support for Intel
1318 For the current Intel microcode data package go to
1319 <https://downloadcenter.intel.com> and search for
1320 'Linux Processor Microcode Data File'.
1322 config MICROCODE_AMD
1323 bool "AMD microcode loading support"
1324 depends on MICROCODE
1327 If you select this option, microcode patch loading support for AMD
1328 processors will be enabled.
1330 config MICROCODE_OLD_INTERFACE
1332 depends on MICROCODE
1335 tristate "/dev/cpu/*/msr - Model-specific register support"
1337 This device gives privileged processes access to the x86
1338 Model-Specific Registers (MSRs). It is a character device with
1339 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1340 MSR accesses are directed to a specific CPU on multi-processor
1344 tristate "/dev/cpu/*/cpuid - CPU information support"
1346 This device gives processes access to the x86 CPUID instruction to
1347 be executed on a specific processor. It is a character device
1348 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1352 prompt "High Memory Support"
1359 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1360 However, the address space of 32-bit x86 processors is only 4
1361 Gigabytes large. That means that, if you have a large amount of
1362 physical memory, not all of it can be "permanently mapped" by the
1363 kernel. The physical memory that's not permanently mapped is called
1366 If you are compiling a kernel which will never run on a machine with
1367 more than 1 Gigabyte total physical RAM, answer "off" here (default
1368 choice and suitable for most users). This will result in a "3GB/1GB"
1369 split: 3GB are mapped so that each process sees a 3GB virtual memory
1370 space and the remaining part of the 4GB virtual memory space is used
1371 by the kernel to permanently map as much physical memory as
1374 If the machine has between 1 and 4 Gigabytes physical RAM, then
1377 If more than 4 Gigabytes is used then answer "64GB" here. This
1378 selection turns Intel PAE (Physical Address Extension) mode on.
1379 PAE implements 3-level paging on IA32 processors. PAE is fully
1380 supported by Linux, PAE mode is implemented on all recent Intel
1381 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1382 then the kernel will not boot on CPUs that don't support PAE!
1384 The actual amount of total physical memory will either be
1385 auto detected or can be forced by using a kernel command line option
1386 such as "mem=256M". (Try "man bootparam" or see the documentation of
1387 your boot loader (lilo or loadlin) about how to pass options to the
1388 kernel at boot time.)
1390 If unsure, say "off".
1395 Select this if you have a 32-bit processor and between 1 and 4
1396 gigabytes of physical RAM.
1400 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1403 Select this if you have a 32-bit processor and more than 4
1404 gigabytes of physical RAM.
1409 prompt "Memory split" if EXPERT
1413 Select the desired split between kernel and user memory.
1415 If the address range available to the kernel is less than the
1416 physical memory installed, the remaining memory will be available
1417 as "high memory". Accessing high memory is a little more costly
1418 than low memory, as it needs to be mapped into the kernel first.
1419 Note that increasing the kernel address space limits the range
1420 available to user programs, making the address space there
1421 tighter. Selecting anything other than the default 3G/1G split
1422 will also likely make your kernel incompatible with binary-only
1425 If you are not absolutely sure what you are doing, leave this
1429 bool "3G/1G user/kernel split"
1430 config VMSPLIT_3G_OPT
1432 bool "3G/1G user/kernel split (for full 1G low memory)"
1434 bool "2G/2G user/kernel split"
1435 config VMSPLIT_2G_OPT
1437 bool "2G/2G user/kernel split (for full 2G low memory)"
1439 bool "1G/3G user/kernel split"
1444 default 0xB0000000 if VMSPLIT_3G_OPT
1445 default 0x80000000 if VMSPLIT_2G
1446 default 0x78000000 if VMSPLIT_2G_OPT
1447 default 0x40000000 if VMSPLIT_1G
1453 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1456 bool "PAE (Physical Address Extension) Support"
1457 depends on X86_32 && !HIGHMEM4G
1458 select PHYS_ADDR_T_64BIT
1461 PAE is required for NX support, and furthermore enables
1462 larger swapspace support for non-overcommit purposes. It
1463 has the cost of more pagetable lookup overhead, and also
1464 consumes more pagetable space per process.
1467 bool "Enable 5-level page tables support"
1468 select DYNAMIC_MEMORY_LAYOUT
1469 select SPARSEMEM_VMEMMAP
1472 5-level paging enables access to larger address space:
1473 upto 128 PiB of virtual address space and 4 PiB of
1474 physical address space.
1476 It will be supported by future Intel CPUs.
1478 A kernel with the option enabled can be booted on machines that
1479 support 4- or 5-level paging.
1481 See Documentation/x86/x86_64/5level-paging.txt for more
1486 config X86_DIRECT_GBPAGES
1488 depends on X86_64 && !DEBUG_PAGEALLOC
1490 Certain kernel features effectively disable kernel
1491 linear 1 GB mappings (even if the CPU otherwise
1492 supports them), so don't confuse the user by printing
1493 that we have them enabled.
1495 config X86_CPA_STATISTICS
1496 bool "Enable statistic for Change Page Attribute"
1499 Expose statistics about the Change Page Attribute mechanims, which
1500 helps to determine the effectivness of preserving large and huge
1501 page mappings when mapping protections are changed.
1503 config ARCH_HAS_MEM_ENCRYPT
1506 config AMD_MEM_ENCRYPT
1507 bool "AMD Secure Memory Encryption (SME) support"
1508 depends on X86_64 && CPU_SUP_AMD
1509 select DYNAMIC_PHYSICAL_MASK
1511 Say yes to enable support for the encryption of system memory.
1512 This requires an AMD processor that supports Secure Memory
1515 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1516 bool "Activate AMD Secure Memory Encryption (SME) by default"
1518 depends on AMD_MEM_ENCRYPT
1520 Say yes to have system memory encrypted by default if running on
1521 an AMD processor that supports Secure Memory Encryption (SME).
1523 If set to Y, then the encryption of system memory can be
1524 deactivated with the mem_encrypt=off command line option.
1526 If set to N, then the encryption of system memory can be
1527 activated with the mem_encrypt=on command line option.
1529 config ARCH_USE_MEMREMAP_PROT
1531 depends on AMD_MEM_ENCRYPT
1533 # Common NUMA Features
1535 bool "Numa Memory Allocation and Scheduler Support"
1537 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1538 default y if X86_BIGSMP
1540 Enable NUMA (Non Uniform Memory Access) support.
1542 The kernel will try to allocate memory used by a CPU on the
1543 local memory controller of the CPU and add some more
1544 NUMA awareness to the kernel.
1546 For 64-bit this is recommended if the system is Intel Core i7
1547 (or later), AMD Opteron, or EM64T NUMA.
1549 For 32-bit this is only needed if you boot a 32-bit
1550 kernel on a 64-bit NUMA platform.
1552 Otherwise, you should say N.
1556 prompt "Old style AMD Opteron NUMA detection"
1557 depends on X86_64 && NUMA && PCI
1559 Enable AMD NUMA node topology detection. You should say Y here if
1560 you have a multi processor AMD system. This uses an old method to
1561 read the NUMA configuration directly from the builtin Northbridge
1562 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1563 which also takes priority if both are compiled in.
1565 config X86_64_ACPI_NUMA
1567 prompt "ACPI NUMA detection"
1568 depends on X86_64 && NUMA && ACPI && PCI
1571 Enable ACPI SRAT based node topology detection.
1573 # Some NUMA nodes have memory ranges that span
1574 # other nodes. Even though a pfn is valid and
1575 # between a node's start and end pfns, it may not
1576 # reside on that node. See memmap_init_zone()
1578 config NODES_SPAN_OTHER_NODES
1580 depends on X86_64_ACPI_NUMA
1583 bool "NUMA emulation"
1586 Enable NUMA emulation. A flat machine will be split
1587 into virtual nodes when booted with "numa=fake=N", where N is the
1588 number of nodes. This is only useful for debugging.
1591 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1593 default "10" if MAXSMP
1594 default "6" if X86_64
1596 depends on NEED_MULTIPLE_NODES
1598 Specify the maximum number of NUMA Nodes available on the target
1599 system. Increases memory reserved to accommodate various tables.
1601 config ARCH_HAVE_MEMORY_PRESENT
1603 depends on X86_32 && DISCONTIGMEM
1605 config ARCH_FLATMEM_ENABLE
1607 depends on X86_32 && !NUMA
1609 config ARCH_DISCONTIGMEM_ENABLE
1611 depends on NUMA && X86_32
1613 config ARCH_DISCONTIGMEM_DEFAULT
1615 depends on NUMA && X86_32
1617 config ARCH_SPARSEMEM_ENABLE
1619 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1620 select SPARSEMEM_STATIC if X86_32
1621 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1623 config ARCH_SPARSEMEM_DEFAULT
1627 config ARCH_SELECT_MEMORY_MODEL
1629 depends on ARCH_SPARSEMEM_ENABLE
1631 config ARCH_MEMORY_PROBE
1632 bool "Enable sysfs memory/probe interface"
1633 depends on X86_64 && MEMORY_HOTPLUG
1635 This option enables a sysfs memory/probe interface for testing.
1636 See Documentation/memory-hotplug.txt for more information.
1637 If you are unsure how to answer this question, answer N.
1639 config ARCH_PROC_KCORE_TEXT
1641 depends on X86_64 && PROC_KCORE
1643 config ILLEGAL_POINTER_VALUE
1646 default 0xdead000000000000 if X86_64
1648 config X86_PMEM_LEGACY_DEVICE
1651 config X86_PMEM_LEGACY
1652 tristate "Support non-standard NVDIMMs and ADR protected memory"
1653 depends on PHYS_ADDR_T_64BIT
1655 select X86_PMEM_LEGACY_DEVICE
1658 Treat memory marked using the non-standard e820 type of 12 as used
1659 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1660 The kernel will offer these regions to the 'pmem' driver so
1661 they can be used for persistent storage.
1666 bool "Allocate 3rd-level pagetables from highmem"
1669 The VM uses one page table entry for each page of physical memory.
1670 For systems with a lot of RAM, this can be wasteful of precious
1671 low memory. Setting this option will put user-space page table
1672 entries in high memory.
1674 config X86_CHECK_BIOS_CORRUPTION
1675 bool "Check for low memory corruption"
1677 Periodically check for memory corruption in low memory, which
1678 is suspected to be caused by BIOS. Even when enabled in the
1679 configuration, it is disabled at runtime. Enable it by
1680 setting "memory_corruption_check=1" on the kernel command
1681 line. By default it scans the low 64k of memory every 60
1682 seconds; see the memory_corruption_check_size and
1683 memory_corruption_check_period parameters in
1684 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1686 When enabled with the default parameters, this option has
1687 almost no overhead, as it reserves a relatively small amount
1688 of memory and scans it infrequently. It both detects corruption
1689 and prevents it from affecting the running system.
1691 It is, however, intended as a diagnostic tool; if repeatable
1692 BIOS-originated corruption always affects the same memory,
1693 you can use memmap= to prevent the kernel from using that
1696 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1697 bool "Set the default setting of memory_corruption_check"
1698 depends on X86_CHECK_BIOS_CORRUPTION
1701 Set whether the default state of memory_corruption_check is
1704 config X86_RESERVE_LOW
1705 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1709 Specify the amount of low memory to reserve for the BIOS.
1711 The first page contains BIOS data structures that the kernel
1712 must not use, so that page must always be reserved.
1714 By default we reserve the first 64K of physical RAM, as a
1715 number of BIOSes are known to corrupt that memory range
1716 during events such as suspend/resume or monitor cable
1717 insertion, so it must not be used by the kernel.
1719 You can set this to 4 if you are absolutely sure that you
1720 trust the BIOS to get all its memory reservations and usages
1721 right. If you know your BIOS have problems beyond the
1722 default 64K area, you can set this to 640 to avoid using the
1723 entire low memory range.
1725 If you have doubts about the BIOS (e.g. suspend/resume does
1726 not work or there's kernel crashes after certain hardware
1727 hotplug events) then you might want to enable
1728 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1729 typical corruption patterns.
1731 Leave this to the default value of 64 if you are unsure.
1733 config MATH_EMULATION
1735 depends on MODIFY_LDT_SYSCALL
1736 prompt "Math emulation" if X86_32
1738 Linux can emulate a math coprocessor (used for floating point
1739 operations) if you don't have one. 486DX and Pentium processors have
1740 a math coprocessor built in, 486SX and 386 do not, unless you added
1741 a 487DX or 387, respectively. (The messages during boot time can
1742 give you some hints here ["man dmesg"].) Everyone needs either a
1743 coprocessor or this emulation.
1745 If you don't have a math coprocessor, you need to say Y here; if you
1746 say Y here even though you have a coprocessor, the coprocessor will
1747 be used nevertheless. (This behavior can be changed with the kernel
1748 command line option "no387", which comes handy if your coprocessor
1749 is broken. Try "man bootparam" or see the documentation of your boot
1750 loader (lilo or loadlin) about how to pass options to the kernel at
1751 boot time.) This means that it is a good idea to say Y here if you
1752 intend to use this kernel on different machines.
1754 More information about the internals of the Linux math coprocessor
1755 emulation can be found in <file:arch/x86/math-emu/README>.
1757 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1758 kernel, it won't hurt.
1762 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1764 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1765 the Memory Type Range Registers (MTRRs) may be used to control
1766 processor access to memory ranges. This is most useful if you have
1767 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1768 allows bus write transfers to be combined into a larger transfer
1769 before bursting over the PCI/AGP bus. This can increase performance
1770 of image write operations 2.5 times or more. Saying Y here creates a
1771 /proc/mtrr file which may be used to manipulate your processor's
1772 MTRRs. Typically the X server should use this.
1774 This code has a reasonably generic interface so that similar
1775 control registers on other processors can be easily supported
1778 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1779 Registers (ARRs) which provide a similar functionality to MTRRs. For
1780 these, the ARRs are used to emulate the MTRRs.
1781 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1782 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1783 write-combining. All of these processors are supported by this code
1784 and it makes sense to say Y here if you have one of them.
1786 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1787 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1788 can lead to all sorts of problems, so it's good to say Y here.
1790 You can safely say Y even if your machine doesn't have MTRRs, you'll
1791 just add about 9 KB to your kernel.
1793 See <file:Documentation/x86/mtrr.txt> for more information.
1795 config MTRR_SANITIZER
1797 prompt "MTRR cleanup support"
1800 Convert MTRR layout from continuous to discrete, so X drivers can
1801 add writeback entries.
1803 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1804 The largest mtrr entry size for a continuous block can be set with
1809 config MTRR_SANITIZER_ENABLE_DEFAULT
1810 int "MTRR cleanup enable value (0-1)"
1813 depends on MTRR_SANITIZER
1815 Enable mtrr cleanup default value
1817 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1818 int "MTRR cleanup spare reg num (0-7)"
1821 depends on MTRR_SANITIZER
1823 mtrr cleanup spare entries default, it can be changed via
1824 mtrr_spare_reg_nr=N on the kernel command line.
1828 prompt "x86 PAT support" if EXPERT
1831 Use PAT attributes to setup page level cache control.
1833 PATs are the modern equivalents of MTRRs and are much more
1834 flexible than MTRRs.
1836 Say N here if you see bootup problems (boot crash, boot hang,
1837 spontaneous reboots) or a non-working video driver.
1841 config ARCH_USES_PG_UNCACHED
1847 prompt "x86 architectural random number generator" if EXPERT
1849 Enable the x86 architectural RDRAND instruction
1850 (Intel Bull Mountain technology) to generate random numbers.
1851 If supported, this is a high bandwidth, cryptographically
1852 secure hardware random number generator.
1856 prompt "Supervisor Mode Access Prevention" if EXPERT
1858 Supervisor Mode Access Prevention (SMAP) is a security
1859 feature in newer Intel processors. There is a small
1860 performance cost if this enabled and turned on; there is
1861 also a small increase in the kernel size if this is enabled.
1865 config X86_INTEL_UMIP
1867 depends on CPU_SUP_INTEL
1868 prompt "Intel User Mode Instruction Prevention" if EXPERT
1870 The User Mode Instruction Prevention (UMIP) is a security
1871 feature in newer Intel processors. If enabled, a general
1872 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1873 or STR instructions are executed in user mode. These instructions
1874 unnecessarily expose information about the hardware state.
1876 The vast majority of applications do not use these instructions.
1877 For the very few that do, software emulation is provided in
1878 specific cases in protected and virtual-8086 modes. Emulated
1881 config X86_INTEL_MPX
1882 prompt "Intel MPX (Memory Protection Extensions)"
1884 # Note: only available in 64-bit mode due to VMA flags shortage
1885 depends on CPU_SUP_INTEL && X86_64
1886 select ARCH_USES_HIGH_VMA_FLAGS
1888 MPX provides hardware features that can be used in
1889 conjunction with compiler-instrumented code to check
1890 memory references. It is designed to detect buffer
1891 overflow or underflow bugs.
1893 This option enables running applications which are
1894 instrumented or otherwise use MPX. It does not use MPX
1895 itself inside the kernel or to protect the kernel
1896 against bad memory references.
1898 Enabling this option will make the kernel larger:
1899 ~8k of kernel text and 36 bytes of data on a 64-bit
1900 defconfig. It adds a long to the 'mm_struct' which
1901 will increase the kernel memory overhead of each
1902 process and adds some branches to paths used during
1903 exec() and munmap().
1905 For details, see Documentation/x86/intel_mpx.txt
1909 config X86_INTEL_MEMORY_PROTECTION_KEYS
1910 prompt "Intel Memory Protection Keys"
1912 # Note: only available in 64-bit mode
1913 depends on CPU_SUP_INTEL && X86_64
1914 select ARCH_USES_HIGH_VMA_FLAGS
1915 select ARCH_HAS_PKEYS
1917 Memory Protection Keys provides a mechanism for enforcing
1918 page-based protections, but without requiring modification of the
1919 page tables when an application changes protection domains.
1921 For details, see Documentation/x86/protection-keys.txt
1926 bool "EFI runtime service support"
1929 select EFI_RUNTIME_WRAPPERS
1931 This enables the kernel to use EFI runtime services that are
1932 available (such as the EFI variable services).
1934 This option is only useful on systems that have EFI firmware.
1935 In addition, you should use the latest ELILO loader available
1936 at <http://elilo.sourceforge.net> in order to take advantage
1937 of EFI runtime services. However, even with this option, the
1938 resultant kernel should continue to boot on existing non-EFI
1942 bool "EFI stub support"
1943 depends on EFI && !X86_USE_3DNOW
1946 This kernel feature allows a bzImage to be loaded directly
1947 by EFI firmware without the use of a bootloader.
1949 See Documentation/efi-stub.txt for more information.
1952 bool "EFI mixed-mode support"
1953 depends on EFI_STUB && X86_64
1955 Enabling this feature allows a 64-bit kernel to be booted
1956 on a 32-bit firmware, provided that your CPU supports 64-bit
1959 Note that it is not possible to boot a mixed-mode enabled
1960 kernel via the EFI boot stub - a bootloader that supports
1961 the EFI handover protocol must be used.
1967 prompt "Enable seccomp to safely compute untrusted bytecode"
1969 This kernel feature is useful for number crunching applications
1970 that may need to compute untrusted bytecode during their
1971 execution. By using pipes or other transports made available to
1972 the process as file descriptors supporting the read/write
1973 syscalls, it's possible to isolate those applications in
1974 their own address space using seccomp. Once seccomp is
1975 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1976 and the task is only allowed to execute a few safe syscalls
1977 defined by each seccomp mode.
1979 If unsure, say Y. Only embedded should say N here.
1981 source kernel/Kconfig.hz
1984 bool "kexec system call"
1987 kexec is a system call that implements the ability to shutdown your
1988 current kernel, and to start another kernel. It is like a reboot
1989 but it is independent of the system firmware. And like a reboot
1990 you can start any kernel with it, not just Linux.
1992 The name comes from the similarity to the exec system call.
1994 It is an ongoing process to be certain the hardware in a machine
1995 is properly shutdown, so do not be surprised if this code does not
1996 initially work for you. As of this writing the exact hardware
1997 interface is strongly in flux, so no good recommendation can be
2001 bool "kexec file based system call"
2006 depends on CRYPTO_SHA256=y
2008 This is new version of kexec system call. This system call is
2009 file based and takes file descriptors as system call argument
2010 for kernel and initramfs as opposed to list of segments as
2011 accepted by previous system call.
2013 config ARCH_HAS_KEXEC_PURGATORY
2016 config KEXEC_VERIFY_SIG
2017 bool "Verify kernel signature during kexec_file_load() syscall"
2018 depends on KEXEC_FILE
2020 This option makes kernel signature verification mandatory for
2021 the kexec_file_load() syscall.
2023 In addition to that option, you need to enable signature
2024 verification for the corresponding kernel image type being
2025 loaded in order for this to work.
2027 config KEXEC_BZIMAGE_VERIFY_SIG
2028 bool "Enable bzImage signature verification support"
2029 depends on KEXEC_VERIFY_SIG
2030 depends on SIGNED_PE_FILE_VERIFICATION
2031 select SYSTEM_TRUSTED_KEYRING
2033 Enable bzImage signature verification support.
2036 bool "kernel crash dumps"
2037 depends on X86_64 || (X86_32 && HIGHMEM)
2039 Generate crash dump after being started by kexec.
2040 This should be normally only set in special crash dump kernels
2041 which are loaded in the main kernel with kexec-tools into
2042 a specially reserved region and then later executed after
2043 a crash by kdump/kexec. The crash dump kernel must be compiled
2044 to a memory address not used by the main kernel or BIOS using
2045 PHYSICAL_START, or it must be built as a relocatable image
2046 (CONFIG_RELOCATABLE=y).
2047 For more details see Documentation/kdump/kdump.txt
2051 depends on KEXEC && HIBERNATION
2053 Jump between original kernel and kexeced kernel and invoke
2054 code in physical address mode via KEXEC
2056 config PHYSICAL_START
2057 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2060 This gives the physical address where the kernel is loaded.
2062 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2063 bzImage will decompress itself to above physical address and
2064 run from there. Otherwise, bzImage will run from the address where
2065 it has been loaded by the boot loader and will ignore above physical
2068 In normal kdump cases one does not have to set/change this option
2069 as now bzImage can be compiled as a completely relocatable image
2070 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2071 address. This option is mainly useful for the folks who don't want
2072 to use a bzImage for capturing the crash dump and want to use a
2073 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2074 to be specifically compiled to run from a specific memory area
2075 (normally a reserved region) and this option comes handy.
2077 So if you are using bzImage for capturing the crash dump,
2078 leave the value here unchanged to 0x1000000 and set
2079 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2080 for capturing the crash dump change this value to start of
2081 the reserved region. In other words, it can be set based on
2082 the "X" value as specified in the "crashkernel=YM@XM"
2083 command line boot parameter passed to the panic-ed
2084 kernel. Please take a look at Documentation/kdump/kdump.txt
2085 for more details about crash dumps.
2087 Usage of bzImage for capturing the crash dump is recommended as
2088 one does not have to build two kernels. Same kernel can be used
2089 as production kernel and capture kernel. Above option should have
2090 gone away after relocatable bzImage support is introduced. But it
2091 is present because there are users out there who continue to use
2092 vmlinux for dump capture. This option should go away down the
2095 Don't change this unless you know what you are doing.
2098 bool "Build a relocatable kernel"
2101 This builds a kernel image that retains relocation information
2102 so it can be loaded someplace besides the default 1MB.
2103 The relocations tend to make the kernel binary about 10% larger,
2104 but are discarded at runtime.
2106 One use is for the kexec on panic case where the recovery kernel
2107 must live at a different physical address than the primary
2110 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2111 it has been loaded at and the compile time physical address
2112 (CONFIG_PHYSICAL_START) is used as the minimum location.
2114 config RANDOMIZE_BASE
2115 bool "Randomize the address of the kernel image (KASLR)"
2116 depends on RELOCATABLE
2119 In support of Kernel Address Space Layout Randomization (KASLR),
2120 this randomizes the physical address at which the kernel image
2121 is decompressed and the virtual address where the kernel
2122 image is mapped, as a security feature that deters exploit
2123 attempts relying on knowledge of the location of kernel
2126 On 64-bit, the kernel physical and virtual addresses are
2127 randomized separately. The physical address will be anywhere
2128 between 16MB and the top of physical memory (up to 64TB). The
2129 virtual address will be randomized from 16MB up to 1GB (9 bits
2130 of entropy). Note that this also reduces the memory space
2131 available to kernel modules from 1.5GB to 1GB.
2133 On 32-bit, the kernel physical and virtual addresses are
2134 randomized together. They will be randomized from 16MB up to
2135 512MB (8 bits of entropy).
2137 Entropy is generated using the RDRAND instruction if it is
2138 supported. If RDTSC is supported, its value is mixed into
2139 the entropy pool as well. If neither RDRAND nor RDTSC are
2140 supported, then entropy is read from the i8254 timer. The
2141 usable entropy is limited by the kernel being built using
2142 2GB addressing, and that PHYSICAL_ALIGN must be at a
2143 minimum of 2MB. As a result, only 10 bits of entropy are
2144 theoretically possible, but the implementations are further
2145 limited due to memory layouts.
2149 # Relocation on x86 needs some additional build support
2150 config X86_NEED_RELOCS
2152 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2154 config PHYSICAL_ALIGN
2155 hex "Alignment value to which kernel should be aligned"
2157 range 0x2000 0x1000000 if X86_32
2158 range 0x200000 0x1000000 if X86_64
2160 This value puts the alignment restrictions on physical address
2161 where kernel is loaded and run from. Kernel is compiled for an
2162 address which meets above alignment restriction.
2164 If bootloader loads the kernel at a non-aligned address and
2165 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2166 address aligned to above value and run from there.
2168 If bootloader loads the kernel at a non-aligned address and
2169 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2170 load address and decompress itself to the address it has been
2171 compiled for and run from there. The address for which kernel is
2172 compiled already meets above alignment restrictions. Hence the
2173 end result is that kernel runs from a physical address meeting
2174 above alignment restrictions.
2176 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2177 this value must be a multiple of 0x200000.
2179 Don't change this unless you know what you are doing.
2181 config DYNAMIC_MEMORY_LAYOUT
2184 This option makes base addresses of vmalloc and vmemmap as well as
2185 __PAGE_OFFSET movable during boot.
2187 config RANDOMIZE_MEMORY
2188 bool "Randomize the kernel memory sections"
2190 depends on RANDOMIZE_BASE
2191 select DYNAMIC_MEMORY_LAYOUT
2192 default RANDOMIZE_BASE
2194 Randomizes the base virtual address of kernel memory sections
2195 (physical memory mapping, vmalloc & vmemmap). This security feature
2196 makes exploits relying on predictable memory locations less reliable.
2198 The order of allocations remains unchanged. Entropy is generated in
2199 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2200 configuration have in average 30,000 different possible virtual
2201 addresses for each memory section.
2205 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2206 hex "Physical memory mapping padding" if EXPERT
2207 depends on RANDOMIZE_MEMORY
2208 default "0xa" if MEMORY_HOTPLUG
2210 range 0x1 0x40 if MEMORY_HOTPLUG
2213 Define the padding in terabytes added to the existing physical
2214 memory size during kernel memory randomization. It is useful
2215 for memory hotplug support but reduces the entropy available for
2216 address randomization.
2218 If unsure, leave at the default value.
2221 bool "Support for hot-pluggable CPUs"
2224 Say Y here to allow turning CPUs off and on. CPUs can be
2225 controlled through /sys/devices/system/cpu.
2226 ( Note: power management support will enable this option
2227 automatically on SMP systems. )
2228 Say N if you want to disable CPU hotplug.
2230 config BOOTPARAM_HOTPLUG_CPU0
2231 bool "Set default setting of cpu0_hotpluggable"
2232 depends on HOTPLUG_CPU
2234 Set whether default state of cpu0_hotpluggable is on or off.
2236 Say Y here to enable CPU0 hotplug by default. If this switch
2237 is turned on, there is no need to give cpu0_hotplug kernel
2238 parameter and the CPU0 hotplug feature is enabled by default.
2240 Please note: there are two known CPU0 dependencies if you want
2241 to enable the CPU0 hotplug feature either by this switch or by
2242 cpu0_hotplug kernel parameter.
2244 First, resume from hibernate or suspend always starts from CPU0.
2245 So hibernate and suspend are prevented if CPU0 is offline.
2247 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2248 offline if any interrupt can not migrate out of CPU0. There may
2249 be other CPU0 dependencies.
2251 Please make sure the dependencies are under your control before
2252 you enable this feature.
2254 Say N if you don't want to enable CPU0 hotplug feature by default.
2255 You still can enable the CPU0 hotplug feature at boot by kernel
2256 parameter cpu0_hotplug.
2258 config DEBUG_HOTPLUG_CPU0
2260 prompt "Debug CPU0 hotplug"
2261 depends on HOTPLUG_CPU
2263 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2264 soon as possible and boots up userspace with CPU0 offlined. User
2265 can online CPU0 back after boot time.
2267 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2268 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2269 compilation or giving cpu0_hotplug kernel parameter at boot.
2275 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2276 depends on COMPAT_32
2278 Certain buggy versions of glibc will crash if they are
2279 presented with a 32-bit vDSO that is not mapped at the address
2280 indicated in its segment table.
2282 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2283 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2284 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2285 the only released version with the bug, but OpenSUSE 9
2286 contains a buggy "glibc 2.3.2".
2288 The symptom of the bug is that everything crashes on startup, saying:
2289 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2291 Saying Y here changes the default value of the vdso32 boot
2292 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2293 This works around the glibc bug but hurts performance.
2295 If unsure, say N: if you are compiling your own kernel, you
2296 are unlikely to be using a buggy version of glibc.
2299 prompt "vsyscall table for legacy applications"
2301 default LEGACY_VSYSCALL_EMULATE
2303 Legacy user code that does not know how to find the vDSO expects
2304 to be able to issue three syscalls by calling fixed addresses in
2305 kernel space. Since this location is not randomized with ASLR,
2306 it can be used to assist security vulnerability exploitation.
2308 This setting can be changed at boot time via the kernel command
2309 line parameter vsyscall=[emulate|none].
2311 On a system with recent enough glibc (2.14 or newer) and no
2312 static binaries, you can say None without a performance penalty
2313 to improve security.
2315 If unsure, select "Emulate".
2317 config LEGACY_VSYSCALL_EMULATE
2320 The kernel traps and emulates calls into the fixed
2321 vsyscall address mapping. This makes the mapping
2322 non-executable, but it still contains known contents,
2323 which could be used in certain rare security vulnerability
2324 exploits. This configuration is recommended when userspace
2325 still uses the vsyscall area.
2327 config LEGACY_VSYSCALL_NONE
2330 There will be no vsyscall mapping at all. This will
2331 eliminate any risk of ASLR bypass due to the vsyscall
2332 fixed address mapping. Attempts to use the vsyscalls
2333 will be reported to dmesg, so that either old or
2334 malicious userspace programs can be identified.
2339 bool "Built-in kernel command line"
2341 Allow for specifying boot arguments to the kernel at
2342 build time. On some systems (e.g. embedded ones), it is
2343 necessary or convenient to provide some or all of the
2344 kernel boot arguments with the kernel itself (that is,
2345 to not rely on the boot loader to provide them.)
2347 To compile command line arguments into the kernel,
2348 set this option to 'Y', then fill in the
2349 boot arguments in CONFIG_CMDLINE.
2351 Systems with fully functional boot loaders (i.e. non-embedded)
2352 should leave this option set to 'N'.
2355 string "Built-in kernel command string"
2356 depends on CMDLINE_BOOL
2359 Enter arguments here that should be compiled into the kernel
2360 image and used at boot time. If the boot loader provides a
2361 command line at boot time, it is appended to this string to
2362 form the full kernel command line, when the system boots.
2364 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2365 change this behavior.
2367 In most cases, the command line (whether built-in or provided
2368 by the boot loader) should specify the device for the root
2371 config CMDLINE_OVERRIDE
2372 bool "Built-in command line overrides boot loader arguments"
2373 depends on CMDLINE_BOOL
2375 Set this option to 'Y' to have the kernel ignore the boot loader
2376 command line, and use ONLY the built-in command line.
2378 This is used to work around broken boot loaders. This should
2379 be set to 'N' under normal conditions.
2381 config MODIFY_LDT_SYSCALL
2382 bool "Enable the LDT (local descriptor table)" if EXPERT
2385 Linux can allow user programs to install a per-process x86
2386 Local Descriptor Table (LDT) using the modify_ldt(2) system
2387 call. This is required to run 16-bit or segmented code such as
2388 DOSEMU or some Wine programs. It is also used by some very old
2389 threading libraries.
2391 Enabling this feature adds a small amount of overhead to
2392 context switches and increases the low-level kernel attack
2393 surface. Disabling it removes the modify_ldt(2) system call.
2395 Saying 'N' here may make sense for embedded or server kernels.
2397 source "kernel/livepatch/Kconfig"
2401 config ARCH_HAS_ADD_PAGES
2403 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2405 config ARCH_ENABLE_MEMORY_HOTPLUG
2407 depends on X86_64 || (X86_32 && HIGHMEM)
2409 config ARCH_ENABLE_MEMORY_HOTREMOVE
2411 depends on MEMORY_HOTPLUG
2413 config USE_PERCPU_NUMA_NODE_ID
2417 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2419 depends on X86_64 || X86_PAE
2421 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2423 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2425 config ARCH_ENABLE_THP_MIGRATION
2427 depends on X86_64 && TRANSPARENT_HUGEPAGE
2429 menu "Power management and ACPI options"
2431 config ARCH_HIBERNATION_HEADER
2433 depends on HIBERNATION
2435 source "kernel/power/Kconfig"
2437 source "drivers/acpi/Kconfig"
2439 source "drivers/sfi/Kconfig"
2446 tristate "APM (Advanced Power Management) BIOS support"
2447 depends on X86_32 && PM_SLEEP
2449 APM is a BIOS specification for saving power using several different
2450 techniques. This is mostly useful for battery powered laptops with
2451 APM compliant BIOSes. If you say Y here, the system time will be
2452 reset after a RESUME operation, the /proc/apm device will provide
2453 battery status information, and user-space programs will receive
2454 notification of APM "events" (e.g. battery status change).
2456 If you select "Y" here, you can disable actual use of the APM
2457 BIOS by passing the "apm=off" option to the kernel at boot time.
2459 Note that the APM support is almost completely disabled for
2460 machines with more than one CPU.
2462 In order to use APM, you will need supporting software. For location
2463 and more information, read <file:Documentation/power/apm-acpi.txt>
2464 and the Battery Powered Linux mini-HOWTO, available from
2465 <http://www.tldp.org/docs.html#howto>.
2467 This driver does not spin down disk drives (see the hdparm(8)
2468 manpage ("man 8 hdparm") for that), and it doesn't turn off
2469 VESA-compliant "green" monitors.
2471 This driver does not support the TI 4000M TravelMate and the ACER
2472 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2473 desktop machines also don't have compliant BIOSes, and this driver
2474 may cause those machines to panic during the boot phase.
2476 Generally, if you don't have a battery in your machine, there isn't
2477 much point in using this driver and you should say N. If you get
2478 random kernel OOPSes or reboots that don't seem to be related to
2479 anything, try disabling/enabling this option (or disabling/enabling
2482 Some other things you should try when experiencing seemingly random,
2485 1) make sure that you have enough swap space and that it is
2487 2) pass the "no-hlt" option to the kernel
2488 3) switch on floating point emulation in the kernel and pass
2489 the "no387" option to the kernel
2490 4) pass the "floppy=nodma" option to the kernel
2491 5) pass the "mem=4M" option to the kernel (thereby disabling
2492 all but the first 4 MB of RAM)
2493 6) make sure that the CPU is not over clocked.
2494 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2495 8) disable the cache from your BIOS settings
2496 9) install a fan for the video card or exchange video RAM
2497 10) install a better fan for the CPU
2498 11) exchange RAM chips
2499 12) exchange the motherboard.
2501 To compile this driver as a module, choose M here: the
2502 module will be called apm.
2506 config APM_IGNORE_USER_SUSPEND
2507 bool "Ignore USER SUSPEND"
2509 This option will ignore USER SUSPEND requests. On machines with a
2510 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2511 series notebooks, it is necessary to say Y because of a BIOS bug.
2513 config APM_DO_ENABLE
2514 bool "Enable PM at boot time"
2516 Enable APM features at boot time. From page 36 of the APM BIOS
2517 specification: "When disabled, the APM BIOS does not automatically
2518 power manage devices, enter the Standby State, enter the Suspend
2519 State, or take power saving steps in response to CPU Idle calls."
2520 This driver will make CPU Idle calls when Linux is idle (unless this
2521 feature is turned off -- see "Do CPU IDLE calls", below). This
2522 should always save battery power, but more complicated APM features
2523 will be dependent on your BIOS implementation. You may need to turn
2524 this option off if your computer hangs at boot time when using APM
2525 support, or if it beeps continuously instead of suspending. Turn
2526 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2527 T400CDT. This is off by default since most machines do fine without
2532 bool "Make CPU Idle calls when idle"
2534 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2535 On some machines, this can activate improved power savings, such as
2536 a slowed CPU clock rate, when the machine is idle. These idle calls
2537 are made after the idle loop has run for some length of time (e.g.,
2538 333 mS). On some machines, this will cause a hang at boot time or
2539 whenever the CPU becomes idle. (On machines with more than one CPU,
2540 this option does nothing.)
2542 config APM_DISPLAY_BLANK
2543 bool "Enable console blanking using APM"
2545 Enable console blanking using the APM. Some laptops can use this to
2546 turn off the LCD backlight when the screen blanker of the Linux
2547 virtual console blanks the screen. Note that this is only used by
2548 the virtual console screen blanker, and won't turn off the backlight
2549 when using the X Window system. This also doesn't have anything to
2550 do with your VESA-compliant power-saving monitor. Further, this
2551 option doesn't work for all laptops -- it might not turn off your
2552 backlight at all, or it might print a lot of errors to the console,
2553 especially if you are using gpm.
2555 config APM_ALLOW_INTS
2556 bool "Allow interrupts during APM BIOS calls"
2558 Normally we disable external interrupts while we are making calls to
2559 the APM BIOS as a measure to lessen the effects of a badly behaving
2560 BIOS implementation. The BIOS should reenable interrupts if it
2561 needs to. Unfortunately, some BIOSes do not -- especially those in
2562 many of the newer IBM Thinkpads. If you experience hangs when you
2563 suspend, try setting this to Y. Otherwise, say N.
2567 source "drivers/cpufreq/Kconfig"
2569 source "drivers/cpuidle/Kconfig"
2571 source "drivers/idle/Kconfig"
2576 menu "Bus options (PCI etc.)"
2582 Find out whether you have a PCI motherboard. PCI is the name of a
2583 bus system, i.e. the way the CPU talks to the other stuff inside
2584 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2585 VESA. If you have PCI, say Y, otherwise N.
2588 prompt "PCI access mode"
2589 depends on X86_32 && PCI
2592 On PCI systems, the BIOS can be used to detect the PCI devices and
2593 determine their configuration. However, some old PCI motherboards
2594 have BIOS bugs and may crash if this is done. Also, some embedded
2595 PCI-based systems don't have any BIOS at all. Linux can also try to
2596 detect the PCI hardware directly without using the BIOS.
2598 With this option, you can specify how Linux should detect the
2599 PCI devices. If you choose "BIOS", the BIOS will be used,
2600 if you choose "Direct", the BIOS won't be used, and if you
2601 choose "MMConfig", then PCI Express MMCONFIG will be used.
2602 If you choose "Any", the kernel will try MMCONFIG, then the
2603 direct access method and falls back to the BIOS if that doesn't
2604 work. If unsure, go with the default, which is "Any".
2609 config PCI_GOMMCONFIG
2626 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2628 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2631 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2634 bool "Support mmconfig PCI config space access" if X86_64
2636 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2637 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2641 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2645 depends on PCI && XEN
2652 config MMCONF_FAM10H
2654 depends on X86_64 && PCI_MMCONFIG && ACPI
2656 config PCI_CNB20LE_QUIRK
2657 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2660 Read the PCI windows out of the CNB20LE host bridge. This allows
2661 PCI hotplug to work on systems with the CNB20LE chipset which do
2664 There's no public spec for this chipset, and this functionality
2665 is known to be incomplete.
2667 You should say N unless you know you need this.
2669 source "drivers/pci/Kconfig"
2672 bool "ISA bus support on modern systems" if EXPERT
2674 Expose ISA bus device drivers and options available for selection and
2675 configuration. Enable this option if your target machine has an ISA
2676 bus. ISA is an older system, displaced by PCI and newer bus
2677 architectures -- if your target machine is modern, it probably does
2678 not have an ISA bus.
2682 # x86_64 have no ISA slots, but can have ISA-style DMA.
2684 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2687 Enables ISA-style DMA support for devices requiring such controllers.
2695 Find out whether you have ISA slots on your motherboard. ISA is the
2696 name of a bus system, i.e. the way the CPU talks to the other stuff
2697 inside your box. Other bus systems are PCI, EISA, MicroChannel
2698 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2699 newer boards don't support it. If you have ISA, say Y, otherwise N.
2705 The Extended Industry Standard Architecture (EISA) bus was
2706 developed as an open alternative to the IBM MicroChannel bus.
2708 The EISA bus provided some of the features of the IBM MicroChannel
2709 bus while maintaining backward compatibility with cards made for
2710 the older ISA bus. The EISA bus saw limited use between 1988 and
2711 1995 when it was made obsolete by the PCI bus.
2713 Say Y here if you are building a kernel for an EISA-based machine.
2717 source "drivers/eisa/Kconfig"
2720 tristate "NatSemi SCx200 support"
2722 This provides basic support for National Semiconductor's
2723 (now AMD's) Geode processors. The driver probes for the
2724 PCI-IDs of several on-chip devices, so its a good dependency
2725 for other scx200_* drivers.
2727 If compiled as a module, the driver is named scx200.
2729 config SCx200HR_TIMER
2730 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2734 This driver provides a clocksource built upon the on-chip
2735 27MHz high-resolution timer. Its also a workaround for
2736 NSC Geode SC-1100's buggy TSC, which loses time when the
2737 processor goes idle (as is done by the scheduler). The
2738 other workaround is idle=poll boot option.
2741 bool "One Laptop Per Child support"
2748 Add support for detecting the unique features of the OLPC
2752 bool "OLPC XO-1 Power Management"
2753 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2755 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2758 bool "OLPC XO-1 Real Time Clock"
2759 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2761 Add support for the XO-1 real time clock, which can be used as a
2762 programmable wakeup source.
2765 bool "OLPC XO-1 SCI extras"
2766 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2770 Add support for SCI-based features of the OLPC XO-1 laptop:
2771 - EC-driven system wakeups
2775 - AC adapter status updates
2776 - Battery status updates
2778 config OLPC_XO15_SCI
2779 bool "OLPC XO-1.5 SCI extras"
2780 depends on OLPC && ACPI
2783 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2784 - EC-driven system wakeups
2785 - AC adapter status updates
2786 - Battery status updates
2789 bool "PCEngines ALIX System Support (LED setup)"
2792 This option enables system support for the PCEngines ALIX.
2793 At present this just sets up LEDs for GPIO control on
2794 ALIX2/3/6 boards. However, other system specific setup should
2797 Note: You must still enable the drivers for GPIO and LED support
2798 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2800 Note: You have to set alix.force=1 for boards with Award BIOS.
2803 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2806 This option enables system support for the Soekris Engineering net5501.
2809 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2813 This option enables system support for the Traverse Technologies GEOS.
2816 bool "Technologic Systems TS-5500 platform support"
2818 select CHECK_SIGNATURE
2822 This option enables system support for the Technologic Systems TS-5500.
2828 depends on CPU_SUP_AMD && PCI
2830 source "drivers/pcmcia/Kconfig"
2833 tristate "RapidIO support"
2836 If enabled this option will include drivers and the core
2837 infrastructure code to support RapidIO interconnect devices.
2839 source "drivers/rapidio/Kconfig"
2842 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2844 Firmwares often provide initial graphics framebuffers so the BIOS,
2845 bootloader or kernel can show basic video-output during boot for
2846 user-guidance and debugging. Historically, x86 used the VESA BIOS
2847 Extensions and EFI-framebuffers for this, which are mostly limited
2849 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2850 framebuffers so the new generic system-framebuffer drivers can be
2851 used on x86. If the framebuffer is not compatible with the generic
2852 modes, it is advertised as fallback platform framebuffer so legacy
2853 drivers like efifb, vesafb and uvesafb can pick it up.
2854 If this option is not selected, all system framebuffers are always
2855 marked as fallback platform framebuffers as usual.
2857 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2858 not be able to pick up generic system framebuffers if this option
2859 is selected. You are highly encouraged to enable simplefb as
2860 replacement if you select this option. simplefb can correctly deal
2861 with generic system framebuffers. But you should still keep vesafb
2862 and others enabled as fallback if a system framebuffer is
2863 incompatible with simplefb.
2870 menu "Binary Emulations"
2872 config IA32_EMULATION
2873 bool "IA32 Emulation"
2875 select ARCH_WANT_OLD_COMPAT_IPC
2877 select COMPAT_BINFMT_ELF
2878 select COMPAT_OLD_SIGACTION
2880 Include code to run legacy 32-bit programs under a
2881 64-bit kernel. You should likely turn this on, unless you're
2882 100% sure that you don't have any 32-bit programs left.
2885 tristate "IA32 a.out support"
2886 depends on IA32_EMULATION
2888 Support old a.out binaries in the 32bit emulation.
2891 bool "x32 ABI for 64-bit mode"
2894 Include code to run binaries for the x32 native 32-bit ABI
2895 for 64-bit processors. An x32 process gets access to the
2896 full 64-bit register file and wide data path while leaving
2897 pointers at 32 bits for smaller memory footprint.
2899 You will need a recent binutils (2.22 or later) with
2900 elf32_x86_64 support enabled to compile a kernel with this
2905 depends on IA32_EMULATION || X86_32
2907 select OLD_SIGSUSPEND3
2911 depends on IA32_EMULATION || X86_X32
2914 config COMPAT_FOR_U64_ALIGNMENT
2917 config SYSVIPC_COMPAT
2925 config HAVE_ATOMIC_IOMAP
2929 config X86_DEV_DMA_OPS
2931 depends on X86_64 || STA2X11
2933 config X86_DMA_REMAP
2937 config HAVE_GENERIC_GUP
2940 source "drivers/firmware/Kconfig"
2942 source "arch/x86/kvm/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob