1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if ARCH = "x86"
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 X86_DEV_DMA_OPS
36 # ( Note that options that are marked 'if X86_64' could in principle be
37 # ported to 32-bit as well. )
42 # Note: keep this list sorted alphabetically
44 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
45 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
47 select ARCH_CLOCKSOURCE_DATA
48 select ARCH_DISCARD_MEMBLOCK
49 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
50 select ARCH_HAS_DEBUG_VIRTUAL
51 select ARCH_HAS_DEVMEM_IS_ALLOWED
52 select ARCH_HAS_ELF_RANDOMIZE
53 select ARCH_HAS_FAST_MULTIPLIER
54 select ARCH_HAS_FORTIFY_SOURCE
55 select ARCH_HAS_GCOV_PROFILE_ALL
56 select ARCH_HAS_KCOV if X86_64
57 select ARCH_HAS_PHYS_TO_DMA
58 select ARCH_HAS_MEMBARRIER_SYNC_CORE
59 select ARCH_HAS_PMEM_API if X86_64
60 select ARCH_HAS_REFCOUNT
61 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
62 select ARCH_HAS_SET_MEMORY
63 select ARCH_HAS_SG_CHAIN
64 select ARCH_HAS_STRICT_KERNEL_RWX
65 select ARCH_HAS_STRICT_MODULE_RWX
66 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
67 select ARCH_HAS_UBSAN_SANITIZE_ALL
68 select ARCH_HAS_ZONE_DEVICE if X86_64
69 select ARCH_HAVE_NMI_SAFE_CMPXCHG
70 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
71 select ARCH_MIGHT_HAVE_PC_PARPORT
72 select ARCH_MIGHT_HAVE_PC_SERIO
73 select ARCH_SUPPORTS_ATOMIC_RMW
74 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
75 select ARCH_USE_BUILTIN_BSWAP
76 select ARCH_USE_QUEUED_RWLOCKS
77 select ARCH_USE_QUEUED_SPINLOCKS
78 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
79 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
80 select ARCH_WANTS_THP_SWAP if X86_64
81 select BUILDTIME_EXTABLE_SORT
83 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
84 select CLOCKSOURCE_WATCHDOG
85 select DCACHE_WORD_ACCESS
86 select EDAC_ATOMIC_SCRUB
88 select GENERIC_CLOCKEVENTS
89 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
90 select GENERIC_CLOCKEVENTS_MIN_ADJUST
91 select GENERIC_CMOS_UPDATE
92 select GENERIC_CPU_AUTOPROBE
93 select GENERIC_CPU_VULNERABILITIES
94 select GENERIC_EARLY_IOREMAP
95 select GENERIC_FIND_FIRST_BIT
97 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
98 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
99 select GENERIC_IRQ_MIGRATION if SMP
100 select GENERIC_IRQ_PROBE
101 select GENERIC_IRQ_RESERVATION_MODE
102 select GENERIC_IRQ_SHOW
103 select GENERIC_PENDING_IRQ if SMP
104 select GENERIC_SMP_IDLE_THREAD
105 select GENERIC_STRNCPY_FROM_USER
106 select GENERIC_STRNLEN_USER
107 select GENERIC_TIME_VSYSCALL
108 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
109 select HAVE_ACPI_APEI if ACPI
110 select HAVE_ACPI_APEI_NMI if ACPI
111 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
112 select HAVE_ARCH_AUDITSYSCALL
113 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
114 select HAVE_ARCH_JUMP_LABEL
115 select HAVE_ARCH_KASAN if X86_64
116 select HAVE_ARCH_KGDB
117 select HAVE_ARCH_MMAP_RND_BITS if MMU
118 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
119 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
120 select HAVE_ARCH_SECCOMP_FILTER
121 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
122 select HAVE_ARCH_TRACEHOOK
123 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
124 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
125 select HAVE_ARCH_VMAP_STACK if X86_64
126 select HAVE_ARCH_WITHIN_STACK_FRAMES
127 select HAVE_CC_STACKPROTECTOR
128 select HAVE_CMPXCHG_DOUBLE
129 select HAVE_CMPXCHG_LOCAL
130 select HAVE_CONTEXT_TRACKING if X86_64
131 select HAVE_COPY_THREAD_TLS
132 select HAVE_C_RECORDMCOUNT
133 select HAVE_DEBUG_KMEMLEAK
134 select HAVE_DEBUG_STACKOVERFLOW
135 select HAVE_DMA_API_DEBUG
136 select HAVE_DMA_CONTIGUOUS
137 select HAVE_DYNAMIC_FTRACE
138 select HAVE_DYNAMIC_FTRACE_WITH_REGS
139 select HAVE_EBPF_JIT if X86_64
140 select HAVE_EFFICIENT_UNALIGNED_ACCESS
141 select HAVE_EXIT_THREAD
142 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
143 select HAVE_FTRACE_MCOUNT_RECORD
144 select HAVE_FUNCTION_GRAPH_TRACER
145 select HAVE_FUNCTION_TRACER
146 select HAVE_GCC_PLUGINS
147 select HAVE_HW_BREAKPOINT
149 select HAVE_IOREMAP_PROT
150 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
151 select HAVE_IRQ_TIME_ACCOUNTING
152 select HAVE_KERNEL_BZIP2
153 select HAVE_KERNEL_GZIP
154 select HAVE_KERNEL_LZ4
155 select HAVE_KERNEL_LZMA
156 select HAVE_KERNEL_LZO
157 select HAVE_KERNEL_XZ
159 select HAVE_KPROBES_ON_FTRACE
160 select HAVE_FUNCTION_ERROR_INJECTION
161 select HAVE_KRETPROBES
163 select HAVE_LIVEPATCH if X86_64
165 select HAVE_MEMBLOCK_NODE_MAP
166 select HAVE_MIXED_BREAKPOINTS_REGS
167 select HAVE_MOD_ARCH_SPECIFIC
170 select HAVE_OPTPROBES
171 select HAVE_PCSPKR_PLATFORM
172 select HAVE_PERF_EVENTS
173 select HAVE_PERF_EVENTS_NMI
174 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
175 select HAVE_PERF_REGS
176 select HAVE_PERF_USER_STACK_DUMP
177 select HAVE_RCU_TABLE_FREE
178 select HAVE_REGS_AND_STACK_ACCESS_API
179 select HAVE_RELIABLE_STACKTRACE if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
180 select HAVE_STACK_VALIDATION if X86_64
181 select HAVE_SYSCALL_TRACEPOINTS
182 select HAVE_UNSTABLE_SCHED_CLOCK
183 select HAVE_USER_RETURN_NOTIFIER
184 select IRQ_FORCED_THREADING
185 select PCI_LOCKLESS_CONFIG
188 select RTC_MC146818_LIB
191 select SYSCTL_EXCEPTION_TRACE
192 select THREAD_INFO_IN_TASK
193 select USER_STACKTRACE_SUPPORT
195 select X86_FEATURE_NAMES if PROC_FS
197 config INSTRUCTION_DECODER
199 depends on KPROBES || PERF_EVENTS || UPROBES
203 default "elf32-i386" if X86_32
204 default "elf64-x86-64" if X86_64
206 config ARCH_DEFCONFIG
208 default "arch/x86/configs/i386_defconfig" if X86_32
209 default "arch/x86/configs/x86_64_defconfig" if X86_64
211 config LOCKDEP_SUPPORT
214 config STACKTRACE_SUPPORT
220 config ARCH_MMAP_RND_BITS_MIN
224 config ARCH_MMAP_RND_BITS_MAX
228 config ARCH_MMAP_RND_COMPAT_BITS_MIN
231 config ARCH_MMAP_RND_COMPAT_BITS_MAX
237 config NEED_DMA_MAP_STATE
239 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
241 config NEED_SG_DMA_LENGTH
244 config GENERIC_ISA_DMA
246 depends on ISA_DMA_API
251 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
253 config GENERIC_BUG_RELATIVE_POINTERS
256 config GENERIC_HWEIGHT
259 config ARCH_MAY_HAVE_PC_FDC
261 depends on ISA_DMA_API
263 config RWSEM_XCHGADD_ALGORITHM
266 config GENERIC_CALIBRATE_DELAY
269 config ARCH_HAS_CPU_RELAX
272 config ARCH_HAS_CACHE_LINE_SIZE
275 config HAVE_SETUP_PER_CPU_AREA
278 config NEED_PER_CPU_EMBED_FIRST_CHUNK
281 config NEED_PER_CPU_PAGE_FIRST_CHUNK
284 config ARCH_HIBERNATION_POSSIBLE
287 config ARCH_SUSPEND_POSSIBLE
290 config ARCH_WANT_HUGE_PMD_SHARE
293 config ARCH_WANT_GENERAL_HUGETLB
302 config ARCH_SUPPORTS_OPTIMIZED_INLINING
305 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
308 config KASAN_SHADOW_OFFSET
311 default 0xdffffc0000000000
313 config HAVE_INTEL_TXT
315 depends on INTEL_IOMMU && ACPI
319 depends on X86_32 && SMP
323 depends on X86_64 && SMP
325 config X86_32_LAZY_GS
327 depends on X86_32 && CC_STACKPROTECTOR_NONE
329 config ARCH_SUPPORTS_UPROBES
332 config FIX_EARLYCON_MEM
335 config PGTABLE_LEVELS
337 default 5 if X86_5LEVEL
342 source "init/Kconfig"
343 source "kernel/Kconfig.freezer"
345 menu "Processor type and features"
348 bool "DMA memory allocation support" if EXPERT
351 DMA memory allocation support allows devices with less than 32-bit
352 addressing to allocate within the first 16MB of address space.
353 Disable if no such devices will be used.
358 bool "Symmetric multi-processing support"
360 This enables support for systems with more than one CPU. If you have
361 a system with only one CPU, say N. If you have a system with more
364 If you say N here, the kernel will run on uni- and multiprocessor
365 machines, but will use only one CPU of a multiprocessor machine. If
366 you say Y here, the kernel will run on many, but not all,
367 uniprocessor machines. On a uniprocessor machine, the kernel
368 will run faster if you say N here.
370 Note that if you say Y here and choose architecture "586" or
371 "Pentium" under "Processor family", the kernel will not work on 486
372 architectures. Similarly, multiprocessor kernels for the "PPro"
373 architecture may not work on all Pentium based boards.
375 People using multiprocessor machines who say Y here should also say
376 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
377 Management" code will be disabled if you say Y here.
379 See also <file:Documentation/x86/i386/IO-APIC.txt>,
380 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
381 <http://www.tldp.org/docs.html#howto>.
383 If you don't know what to do here, say N.
385 config X86_FEATURE_NAMES
386 bool "Processor feature human-readable names" if EMBEDDED
389 This option compiles in a table of x86 feature bits and corresponding
390 names. This is required to support /proc/cpuinfo and a few kernel
391 messages. You can disable this to save space, at the expense of
392 making those few kernel messages show numeric feature bits instead.
396 config X86_FAST_FEATURE_TESTS
397 bool "Fast CPU feature tests" if EMBEDDED
400 Some fast-paths in the kernel depend on the capabilities of the CPU.
401 Say Y here for the kernel to patch in the appropriate code at runtime
402 based on the capabilities of the CPU. The infrastructure for patching
403 code at runtime takes up some additional space; space-constrained
404 embedded systems may wish to say N here to produce smaller, slightly
408 bool "Support x2apic"
409 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
411 This enables x2apic support on CPUs that have this feature.
413 This allows 32-bit apic IDs (so it can support very large systems),
414 and accesses the local apic via MSRs not via mmio.
416 If you don't know what to do here, say N.
419 bool "Enable MPS table" if ACPI || SFI
421 depends on X86_LOCAL_APIC
423 For old smp systems that do not have proper acpi support. Newer systems
424 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
428 depends on X86_GOLDFISH
431 bool "Avoid speculative indirect branches in kernel"
433 select STACK_VALIDATION if HAVE_STACK_VALIDATION
435 Compile kernel with the retpoline compiler options to guard against
436 kernel-to-user data leaks by avoiding speculative indirect
437 branches. Requires a compiler with -mindirect-branch=thunk-extern
438 support for full protection. The kernel may run slower.
440 Without compiler support, at least indirect branches in assembler
441 code are eliminated. Since this includes the syscall entry path,
442 it is not entirely pointless.
445 bool "Intel Resource Director Technology support"
447 depends on X86 && CPU_SUP_INTEL
450 Select to enable resource allocation and monitoring which are
451 sub-features of Intel Resource Director Technology(RDT). More
452 information about RDT can be found in the Intel x86
453 Architecture Software Developer Manual.
459 bool "Support for big SMP systems with more than 8 CPUs"
462 This option is needed for the systems that have more than 8 CPUs
464 config X86_EXTENDED_PLATFORM
465 bool "Support for extended (non-PC) x86 platforms"
468 If you disable this option then the kernel will only support
469 standard PC platforms. (which covers the vast majority of
472 If you enable this option then you'll be able to select support
473 for the following (non-PC) 32 bit x86 platforms:
474 Goldfish (Android emulator)
477 SGI 320/540 (Visual Workstation)
478 STA2X11-based (e.g. Northville)
479 Moorestown MID devices
481 If you have one of these systems, or if you want to build a
482 generic distribution kernel, say Y here - otherwise say N.
486 config X86_EXTENDED_PLATFORM
487 bool "Support for extended (non-PC) x86 platforms"
490 If you disable this option then the kernel will only support
491 standard PC platforms. (which covers the vast majority of
494 If you enable this option then you'll be able to select support
495 for the following (non-PC) 64 bit x86 platforms:
500 If you have one of these systems, or if you want to build a
501 generic distribution kernel, say Y here - otherwise say N.
503 # This is an alphabetically sorted list of 64 bit extended platforms
504 # Please maintain the alphabetic order if and when there are additions
506 bool "Numascale NumaChip"
508 depends on X86_EXTENDED_PLATFORM
511 depends on X86_X2APIC
512 depends on PCI_MMCONFIG
514 Adds support for Numascale NumaChip large-SMP systems. Needed to
515 enable more than ~168 cores.
516 If you don't have one of these, you should say N here.
520 select HYPERVISOR_GUEST
522 depends on X86_64 && PCI
523 depends on X86_EXTENDED_PLATFORM
526 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
527 supposed to run on these EM64T-based machines. Only choose this option
528 if you have one of these machines.
531 bool "SGI Ultraviolet"
533 depends on X86_EXTENDED_PLATFORM
536 depends on X86_X2APIC
539 This option is needed in order to support SGI Ultraviolet systems.
540 If you don't have one of these, you should say N here.
542 # Following is an alphabetically sorted list of 32 bit extended platforms
543 # Please maintain the alphabetic order if and when there are additions
546 bool "Goldfish (Virtual Platform)"
547 depends on X86_EXTENDED_PLATFORM
549 Enable support for the Goldfish virtual platform used primarily
550 for Android development. Unless you are building for the Android
551 Goldfish emulator say N here.
554 bool "CE4100 TV platform"
556 depends on PCI_GODIRECT
557 depends on X86_IO_APIC
559 depends on X86_EXTENDED_PLATFORM
560 select X86_REBOOTFIXUPS
562 select OF_EARLY_FLATTREE
564 Select for the Intel CE media processor (CE4100) SOC.
565 This option compiles in support for the CE4100 SOC for settop
566 boxes and media devices.
569 bool "Intel MID platform support"
570 depends on X86_EXTENDED_PLATFORM
571 depends on X86_PLATFORM_DEVICES
573 depends on X86_64 || (PCI_GOANY && X86_32)
574 depends on X86_IO_APIC
580 select MFD_INTEL_MSIC
582 Select to build a kernel capable of supporting Intel MID (Mobile
583 Internet Device) platform systems which do not have the PCI legacy
584 interfaces. If you are building for a PC class system say N here.
586 Intel MID platforms are based on an Intel processor and chipset which
587 consume less power than most of the x86 derivatives.
589 config X86_INTEL_QUARK
590 bool "Intel Quark platform support"
592 depends on X86_EXTENDED_PLATFORM
593 depends on X86_PLATFORM_DEVICES
597 depends on X86_IO_APIC
602 Select to include support for Quark X1000 SoC.
603 Say Y here if you have a Quark based system such as the Arduino
604 compatible Intel Galileo.
606 config X86_INTEL_LPSS
607 bool "Intel Low Power Subsystem Support"
608 depends on X86 && ACPI
613 Select to build support for Intel Low Power Subsystem such as
614 found on Intel Lynxpoint PCH. Selecting this option enables
615 things like clock tree (common clock framework) and pincontrol
616 which are needed by the LPSS peripheral drivers.
618 config X86_AMD_PLATFORM_DEVICE
619 bool "AMD ACPI2Platform devices support"
624 Select to interpret AMD specific ACPI device to platform device
625 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
626 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
627 implemented under PINCTRL subsystem.
630 tristate "Intel SoC IOSF Sideband support for SoC platforms"
633 This option enables sideband register access support for Intel SoC
634 platforms. On these platforms the IOSF sideband is used in lieu of
635 MSR's for some register accesses, mostly but not limited to thermal
636 and power. Drivers may query the availability of this device to
637 determine if they need the sideband in order to work on these
638 platforms. The sideband is available on the following SoC products.
639 This list is not meant to be exclusive.
644 You should say Y if you are running a kernel on one of these SoC's.
646 config IOSF_MBI_DEBUG
647 bool "Enable IOSF sideband access through debugfs"
648 depends on IOSF_MBI && DEBUG_FS
650 Select this option to expose the IOSF sideband access registers (MCR,
651 MDR, MCRX) through debugfs to write and read register information from
652 different units on the SoC. This is most useful for obtaining device
653 state information for debug and analysis. As this is a general access
654 mechanism, users of this option would have specific knowledge of the
655 device they want to access.
657 If you don't require the option or are in doubt, say N.
660 bool "RDC R-321x SoC"
662 depends on X86_EXTENDED_PLATFORM
664 select X86_REBOOTFIXUPS
666 This option is needed for RDC R-321x system-on-chip, also known
668 If you don't have one of these chips, you should say N here.
670 config X86_32_NON_STANDARD
671 bool "Support non-standard 32-bit SMP architectures"
672 depends on X86_32 && SMP
673 depends on X86_EXTENDED_PLATFORM
675 This option compiles in the bigsmp and STA2X11 default
676 subarchitectures. It is intended for a generic binary
677 kernel. If you select them all, kernel will probe it one by
678 one and will fallback to default.
680 # Alphabetically sorted list of Non standard 32 bit platforms
682 config X86_SUPPORTS_MEMORY_FAILURE
684 # MCE code calls memory_failure():
686 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
687 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
688 depends on X86_64 || !SPARSEMEM
689 select ARCH_SUPPORTS_MEMORY_FAILURE
692 bool "STA2X11 Companion Chip Support"
693 depends on X86_32_NON_STANDARD && PCI
694 select X86_DEV_DMA_OPS
701 This adds support for boards based on the STA2X11 IO-Hub,
702 a.k.a. "ConneXt". The chip is used in place of the standard
703 PC chipset, so all "standard" peripherals are missing. If this
704 option is selected the kernel will still be able to boot on
705 standard PC machines.
708 tristate "Eurobraille/Iris poweroff module"
711 The Iris machines from EuroBraille do not have APM or ACPI support
712 to shut themselves down properly. A special I/O sequence is
713 needed to do so, which is what this module does at
716 This is only for Iris machines from EuroBraille.
720 config SCHED_OMIT_FRAME_POINTER
722 prompt "Single-depth WCHAN output"
725 Calculate simpler /proc/<PID>/wchan values. If this option
726 is disabled then wchan values will recurse back to the
727 caller function. This provides more accurate wchan values,
728 at the expense of slightly more scheduling overhead.
730 If in doubt, say "Y".
732 menuconfig HYPERVISOR_GUEST
733 bool "Linux guest support"
735 Say Y here to enable options for running Linux under various hyper-
736 visors. This option enables basic hypervisor detection and platform
739 If you say N, all options in this submenu will be skipped and
740 disabled, and Linux guest support won't be built in.
745 bool "Enable paravirtualization code"
747 This changes the kernel so it can modify itself when it is run
748 under a hypervisor, potentially improving performance significantly
749 over full virtualization. However, when run without a hypervisor
750 the kernel is theoretically slower and slightly larger.
752 config PARAVIRT_DEBUG
753 bool "paravirt-ops debugging"
754 depends on PARAVIRT && DEBUG_KERNEL
756 Enable to debug paravirt_ops internals. Specifically, BUG if
757 a paravirt_op is missing when it is called.
759 config PARAVIRT_SPINLOCKS
760 bool "Paravirtualization layer for spinlocks"
761 depends on PARAVIRT && SMP
763 Paravirtualized spinlocks allow a pvops backend to replace the
764 spinlock implementation with something virtualization-friendly
765 (for example, block the virtual CPU rather than spinning).
767 It has a minimal impact on native kernels and gives a nice performance
768 benefit on paravirtualized KVM / Xen kernels.
770 If you are unsure how to answer this question, answer Y.
772 config QUEUED_LOCK_STAT
773 bool "Paravirt queued spinlock statistics"
774 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
776 Enable the collection of statistical data on the slowpath
777 behavior of paravirtualized queued spinlocks and report
780 source "arch/x86/xen/Kconfig"
783 bool "KVM Guest support (including kvmclock)"
785 select PARAVIRT_CLOCK
788 This option enables various optimizations for running under the KVM
789 hypervisor. It includes a paravirtualized clock, so that instead
790 of relying on a PIT (or probably other) emulation by the
791 underlying device model, the host provides the guest with
792 timing infrastructure such as time of day, and system time
795 bool "Enable debug information for KVM Guests in debugfs"
796 depends on KVM_GUEST && DEBUG_FS
799 This option enables collection of various statistics for KVM guest.
800 Statistics are displayed in debugfs filesystem. Enabling this option
801 may incur significant overhead.
803 config PARAVIRT_TIME_ACCOUNTING
804 bool "Paravirtual steal time accounting"
808 Select this option to enable fine granularity task steal time
809 accounting. Time spent executing other tasks in parallel with
810 the current vCPU is discounted from the vCPU power. To account for
811 that, there can be a small performance impact.
813 If in doubt, say N here.
815 config PARAVIRT_CLOCK
818 config JAILHOUSE_GUEST
819 bool "Jailhouse non-root cell support"
820 depends on X86_64 && PCI
823 This option allows to run Linux as guest in a Jailhouse non-root
824 cell. You can leave this option disabled if you only want to start
825 Jailhouse and run Linux afterwards in the root cell.
827 endif #HYPERVISOR_GUEST
832 source "arch/x86/Kconfig.cpu"
836 prompt "HPET Timer Support" if X86_32
838 Use the IA-PC HPET (High Precision Event Timer) to manage
839 time in preference to the PIT and RTC, if a HPET is
841 HPET is the next generation timer replacing legacy 8254s.
842 The HPET provides a stable time base on SMP
843 systems, unlike the TSC, but it is more expensive to access,
844 as it is off-chip. The interface used is documented
845 in the HPET spec, revision 1.
847 You can safely choose Y here. However, HPET will only be
848 activated if the platform and the BIOS support this feature.
849 Otherwise the 8254 will be used for timing services.
851 Choose N to continue using the legacy 8254 timer.
853 config HPET_EMULATE_RTC
855 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
858 def_bool y if X86_INTEL_MID
859 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
861 depends on X86_INTEL_MID && SFI
863 APB timer is the replacement for 8254, HPET on X86 MID platforms.
864 The APBT provides a stable time base on SMP
865 systems, unlike the TSC, but it is more expensive to access,
866 as it is off-chip. APB timers are always running regardless of CPU
867 C states, they are used as per CPU clockevent device when possible.
869 # Mark as expert because too many people got it wrong.
870 # The code disables itself when not needed.
873 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
874 bool "Enable DMI scanning" if EXPERT
876 Enabled scanning of DMI to identify machine quirks. Say Y
877 here unless you have verified that your setup is not
878 affected by entries in the DMI blacklist. Required by PNP
882 bool "Old AMD GART IOMMU support"
884 depends on X86_64 && PCI && AMD_NB
886 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
887 GART based hardware IOMMUs.
889 The GART supports full DMA access for devices with 32-bit access
890 limitations, on systems with more than 3 GB. This is usually needed
891 for USB, sound, many IDE/SATA chipsets and some other devices.
893 Newer systems typically have a modern AMD IOMMU, supported via
894 the CONFIG_AMD_IOMMU=y config option.
896 In normal configurations this driver is only active when needed:
897 there's more than 3 GB of memory and the system contains a
898 32-bit limited device.
903 bool "IBM Calgary IOMMU support"
905 depends on X86_64 && PCI
907 Support for hardware IOMMUs in IBM's xSeries x366 and x460
908 systems. Needed to run systems with more than 3GB of memory
909 properly with 32-bit PCI devices that do not support DAC
910 (Double Address Cycle). Calgary also supports bus level
911 isolation, where all DMAs pass through the IOMMU. This
912 prevents them from going anywhere except their intended
913 destination. This catches hard-to-find kernel bugs and
914 mis-behaving drivers and devices that do not use the DMA-API
915 properly to set up their DMA buffers. The IOMMU can be
916 turned off at boot time with the iommu=off parameter.
917 Normally the kernel will make the right choice by itself.
920 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
922 prompt "Should Calgary be enabled by default?"
923 depends on CALGARY_IOMMU
925 Should Calgary be enabled by default? if you choose 'y', Calgary
926 will be used (if it exists). If you choose 'n', Calgary will not be
927 used even if it exists. If you choose 'n' and would like to use
928 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
931 # need this always selected by IOMMU for the VIA workaround
935 Support for software bounce buffers used on x86-64 systems
936 which don't have a hardware IOMMU. Using this PCI devices
937 which can only access 32-bits of memory can be used on systems
938 with more than 3 GB of memory.
943 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
946 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
947 depends on X86_64 && SMP && DEBUG_KERNEL
948 select CPUMASK_OFFSTACK
950 Enable maximum number of CPUS and NUMA Nodes for this architecture.
954 # The maximum number of CPUs supported:
956 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
957 # and which can be configured interactively in the
958 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
960 # The ranges are different on 32-bit and 64-bit kernels, depending on
961 # hardware capabilities and scalability features of the kernel.
963 # ( If MAXSMP is enabled we just use the highest possible value and disable
964 # interactive configuration. )
967 config NR_CPUS_RANGE_BEGIN
969 default NR_CPUS_RANGE_END if MAXSMP
973 config NR_CPUS_RANGE_END
976 default 64 if SMP && X86_BIGSMP
977 default 8 if SMP && !X86_BIGSMP
980 config NR_CPUS_RANGE_END
983 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
984 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
987 config NR_CPUS_DEFAULT
990 default 32 if X86_BIGSMP
994 config NR_CPUS_DEFAULT
997 default 8192 if MAXSMP
1002 int "Maximum number of CPUs" if SMP && !MAXSMP
1003 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1004 default NR_CPUS_DEFAULT
1006 This allows you to specify the maximum number of CPUs which this
1007 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1008 supported value is 8192, otherwise the maximum value is 512. The
1009 minimum value which makes sense is 2.
1011 This is purely to save memory: each supported CPU adds about 8KB
1012 to the kernel image.
1015 bool "SMT (Hyperthreading) scheduler support"
1018 SMT scheduler support improves the CPU scheduler's decision making
1019 when dealing with Intel Pentium 4 chips with HyperThreading at a
1020 cost of slightly increased overhead in some places. If unsure say
1025 prompt "Multi-core scheduler support"
1028 Multi-core scheduler support improves the CPU scheduler's decision
1029 making when dealing with multi-core CPU chips at a cost of slightly
1030 increased overhead in some places. If unsure say N here.
1032 config SCHED_MC_PRIO
1033 bool "CPU core priorities scheduler support"
1034 depends on SCHED_MC && CPU_SUP_INTEL
1035 select X86_INTEL_PSTATE
1039 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1040 core ordering determined at manufacturing time, which allows
1041 certain cores to reach higher turbo frequencies (when running
1042 single threaded workloads) than others.
1044 Enabling this kernel feature teaches the scheduler about
1045 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1046 scheduler's CPU selection logic accordingly, so that higher
1047 overall system performance can be achieved.
1049 This feature will have no effect on CPUs without this feature.
1051 If unsure say Y here.
1053 source "kernel/Kconfig.preempt"
1057 depends on !SMP && X86_LOCAL_APIC
1060 bool "Local APIC support on uniprocessors" if !PCI_MSI
1062 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1064 A local APIC (Advanced Programmable Interrupt Controller) is an
1065 integrated interrupt controller in the CPU. If you have a single-CPU
1066 system which has a processor with a local APIC, you can say Y here to
1067 enable and use it. If you say Y here even though your machine doesn't
1068 have a local APIC, then the kernel will still run with no slowdown at
1069 all. The local APIC supports CPU-generated self-interrupts (timer,
1070 performance counters), and the NMI watchdog which detects hard
1073 config X86_UP_IOAPIC
1074 bool "IO-APIC support on uniprocessors"
1075 depends on X86_UP_APIC
1077 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1078 SMP-capable replacement for PC-style interrupt controllers. Most
1079 SMP systems and many recent uniprocessor systems have one.
1081 If you have a single-CPU system with an IO-APIC, you can say Y here
1082 to use it. If you say Y here even though your machine doesn't have
1083 an IO-APIC, then the kernel will still run with no slowdown at all.
1085 config X86_LOCAL_APIC
1087 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1088 select IRQ_DOMAIN_HIERARCHY
1089 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1093 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1095 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1096 bool "Reroute for broken boot IRQs"
1097 depends on X86_IO_APIC
1099 This option enables a workaround that fixes a source of
1100 spurious interrupts. This is recommended when threaded
1101 interrupt handling is used on systems where the generation of
1102 superfluous "boot interrupts" cannot be disabled.
1104 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1105 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1106 kernel does during interrupt handling). On chipsets where this
1107 boot IRQ generation cannot be disabled, this workaround keeps
1108 the original IRQ line masked so that only the equivalent "boot
1109 IRQ" is delivered to the CPUs. The workaround also tells the
1110 kernel to set up the IRQ handler on the boot IRQ line. In this
1111 way only one interrupt is delivered to the kernel. Otherwise
1112 the spurious second interrupt may cause the kernel to bring
1113 down (vital) interrupt lines.
1115 Only affects "broken" chipsets. Interrupt sharing may be
1116 increased on these systems.
1119 bool "Machine Check / overheating reporting"
1120 select GENERIC_ALLOCATOR
1123 Machine Check support allows the processor to notify the
1124 kernel if it detects a problem (e.g. overheating, data corruption).
1125 The action the kernel takes depends on the severity of the problem,
1126 ranging from warning messages to halting the machine.
1128 config X86_MCELOG_LEGACY
1129 bool "Support for deprecated /dev/mcelog character device"
1132 Enable support for /dev/mcelog which is needed by the old mcelog
1133 userspace logging daemon. Consider switching to the new generation
1136 config X86_MCE_INTEL
1138 prompt "Intel MCE features"
1139 depends on X86_MCE && X86_LOCAL_APIC
1141 Additional support for intel specific MCE features such as
1142 the thermal monitor.
1146 prompt "AMD MCE features"
1147 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1149 Additional support for AMD specific MCE features such as
1150 the DRAM Error Threshold.
1152 config X86_ANCIENT_MCE
1153 bool "Support for old Pentium 5 / WinChip machine checks"
1154 depends on X86_32 && X86_MCE
1156 Include support for machine check handling on old Pentium 5 or WinChip
1157 systems. These typically need to be enabled explicitly on the command
1160 config X86_MCE_THRESHOLD
1161 depends on X86_MCE_AMD || X86_MCE_INTEL
1164 config X86_MCE_INJECT
1165 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1166 tristate "Machine check injector support"
1168 Provide support for injecting machine checks for testing purposes.
1169 If you don't know what a machine check is and you don't do kernel
1170 QA it is safe to say n.
1172 config X86_THERMAL_VECTOR
1174 depends on X86_MCE_INTEL
1176 source "arch/x86/events/Kconfig"
1178 config X86_LEGACY_VM86
1179 bool "Legacy VM86 support"
1183 This option allows user programs to put the CPU into V8086
1184 mode, which is an 80286-era approximation of 16-bit real mode.
1186 Some very old versions of X and/or vbetool require this option
1187 for user mode setting. Similarly, DOSEMU will use it if
1188 available to accelerate real mode DOS programs. However, any
1189 recent version of DOSEMU, X, or vbetool should be fully
1190 functional even without kernel VM86 support, as they will all
1191 fall back to software emulation. Nevertheless, if you are using
1192 a 16-bit DOS program where 16-bit performance matters, vm86
1193 mode might be faster than emulation and you might want to
1196 Note that any app that works on a 64-bit kernel is unlikely to
1197 need this option, as 64-bit kernels don't, and can't, support
1198 V8086 mode. This option is also unrelated to 16-bit protected
1199 mode and is not needed to run most 16-bit programs under Wine.
1201 Enabling this option increases the complexity of the kernel
1202 and slows down exception handling a tiny bit.
1204 If unsure, say N here.
1208 default X86_LEGACY_VM86
1211 bool "Enable support for 16-bit segments" if EXPERT
1213 depends on MODIFY_LDT_SYSCALL
1215 This option is required by programs like Wine to run 16-bit
1216 protected mode legacy code on x86 processors. Disabling
1217 this option saves about 300 bytes on i386, or around 6K text
1218 plus 16K runtime memory on x86-64,
1222 depends on X86_16BIT && X86_32
1226 depends on X86_16BIT && X86_64
1228 config X86_VSYSCALL_EMULATION
1229 bool "Enable vsyscall emulation" if EXPERT
1233 This enables emulation of the legacy vsyscall page. Disabling
1234 it is roughly equivalent to booting with vsyscall=none, except
1235 that it will also disable the helpful warning if a program
1236 tries to use a vsyscall. With this option set to N, offending
1237 programs will just segfault, citing addresses of the form
1240 This option is required by many programs built before 2013, and
1241 care should be used even with newer programs if set to N.
1243 Disabling this option saves about 7K of kernel size and
1244 possibly 4K of additional runtime pagetable memory.
1247 tristate "Toshiba Laptop support"
1250 This adds a driver to safely access the System Management Mode of
1251 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1252 not work on models with a Phoenix BIOS. The System Management Mode
1253 is used to set the BIOS and power saving options on Toshiba portables.
1255 For information on utilities to make use of this driver see the
1256 Toshiba Linux utilities web site at:
1257 <http://www.buzzard.org.uk/toshiba/>.
1259 Say Y if you intend to run this kernel on a Toshiba portable.
1263 tristate "Dell i8k legacy laptop support"
1265 select SENSORS_DELL_SMM
1267 This option enables legacy /proc/i8k userspace interface in hwmon
1268 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1269 temperature and allows controlling fan speeds of Dell laptops via
1270 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1271 it reports also power and hotkey status. For fan speed control is
1272 needed userspace package i8kutils.
1274 Say Y if you intend to run this kernel on old Dell laptops or want to
1275 use userspace package i8kutils.
1278 config X86_REBOOTFIXUPS
1279 bool "Enable X86 board specific fixups for reboot"
1282 This enables chipset and/or board specific fixups to be done
1283 in order to get reboot to work correctly. This is only needed on
1284 some combinations of hardware and BIOS. The symptom, for which
1285 this config is intended, is when reboot ends with a stalled/hung
1288 Currently, the only fixup is for the Geode machines using
1289 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1291 Say Y if you want to enable the fixup. Currently, it's safe to
1292 enable this option even if you don't need it.
1296 bool "CPU microcode loading support"
1298 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1301 If you say Y here, you will be able to update the microcode on
1302 Intel and AMD processors. The Intel support is for the IA32 family,
1303 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1304 AMD support is for families 0x10 and later. You will obviously need
1305 the actual microcode binary data itself which is not shipped with
1308 The preferred method to load microcode from a detached initrd is described
1309 in Documentation/x86/early-microcode.txt. For that you need to enable
1310 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1311 initrd for microcode blobs.
1313 In addition, you can build the microcode into the kernel. For that you
1314 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1317 config MICROCODE_INTEL
1318 bool "Intel microcode loading support"
1319 depends on MICROCODE
1323 This options enables microcode patch loading support for Intel
1326 For the current Intel microcode data package go to
1327 <https://downloadcenter.intel.com> and search for
1328 'Linux Processor Microcode Data File'.
1330 config MICROCODE_AMD
1331 bool "AMD microcode loading support"
1332 depends on MICROCODE
1335 If you select this option, microcode patch loading support for AMD
1336 processors will be enabled.
1338 config MICROCODE_OLD_INTERFACE
1340 depends on MICROCODE
1343 tristate "/dev/cpu/*/msr - Model-specific register support"
1345 This device gives privileged processes access to the x86
1346 Model-Specific Registers (MSRs). It is a character device with
1347 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1348 MSR accesses are directed to a specific CPU on multi-processor
1352 tristate "/dev/cpu/*/cpuid - CPU information support"
1354 This device gives processes access to the x86 CPUID instruction to
1355 be executed on a specific processor. It is a character device
1356 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1360 prompt "High Memory Support"
1367 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1368 However, the address space of 32-bit x86 processors is only 4
1369 Gigabytes large. That means that, if you have a large amount of
1370 physical memory, not all of it can be "permanently mapped" by the
1371 kernel. The physical memory that's not permanently mapped is called
1374 If you are compiling a kernel which will never run on a machine with
1375 more than 1 Gigabyte total physical RAM, answer "off" here (default
1376 choice and suitable for most users). This will result in a "3GB/1GB"
1377 split: 3GB are mapped so that each process sees a 3GB virtual memory
1378 space and the remaining part of the 4GB virtual memory space is used
1379 by the kernel to permanently map as much physical memory as
1382 If the machine has between 1 and 4 Gigabytes physical RAM, then
1385 If more than 4 Gigabytes is used then answer "64GB" here. This
1386 selection turns Intel PAE (Physical Address Extension) mode on.
1387 PAE implements 3-level paging on IA32 processors. PAE is fully
1388 supported by Linux, PAE mode is implemented on all recent Intel
1389 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1390 then the kernel will not boot on CPUs that don't support PAE!
1392 The actual amount of total physical memory will either be
1393 auto detected or can be forced by using a kernel command line option
1394 such as "mem=256M". (Try "man bootparam" or see the documentation of
1395 your boot loader (lilo or loadlin) about how to pass options to the
1396 kernel at boot time.)
1398 If unsure, say "off".
1403 Select this if you have a 32-bit processor and between 1 and 4
1404 gigabytes of physical RAM.
1408 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1411 Select this if you have a 32-bit processor and more than 4
1412 gigabytes of physical RAM.
1417 prompt "Memory split" if EXPERT
1421 Select the desired split between kernel and user memory.
1423 If the address range available to the kernel is less than the
1424 physical memory installed, the remaining memory will be available
1425 as "high memory". Accessing high memory is a little more costly
1426 than low memory, as it needs to be mapped into the kernel first.
1427 Note that increasing the kernel address space limits the range
1428 available to user programs, making the address space there
1429 tighter. Selecting anything other than the default 3G/1G split
1430 will also likely make your kernel incompatible with binary-only
1433 If you are not absolutely sure what you are doing, leave this
1437 bool "3G/1G user/kernel split"
1438 config VMSPLIT_3G_OPT
1440 bool "3G/1G user/kernel split (for full 1G low memory)"
1442 bool "2G/2G user/kernel split"
1443 config VMSPLIT_2G_OPT
1445 bool "2G/2G user/kernel split (for full 2G low memory)"
1447 bool "1G/3G user/kernel split"
1452 default 0xB0000000 if VMSPLIT_3G_OPT
1453 default 0x80000000 if VMSPLIT_2G
1454 default 0x78000000 if VMSPLIT_2G_OPT
1455 default 0x40000000 if VMSPLIT_1G
1461 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1464 bool "PAE (Physical Address Extension) Support"
1465 depends on X86_32 && !HIGHMEM4G
1468 PAE is required for NX support, and furthermore enables
1469 larger swapspace support for non-overcommit purposes. It
1470 has the cost of more pagetable lookup overhead, and also
1471 consumes more pagetable space per process.
1474 bool "Enable 5-level page tables support"
1475 select DYNAMIC_MEMORY_LAYOUT
1476 select SPARSEMEM_VMEMMAP
1479 5-level paging enables access to larger address space:
1480 upto 128 PiB of virtual address space and 4 PiB of
1481 physical address space.
1483 It will be supported by future Intel CPUs.
1485 A kernel with the option enabled can be booted on machines that
1486 support 4- or 5-level paging.
1488 See Documentation/x86/x86_64/5level-paging.txt for more
1493 config ARCH_PHYS_ADDR_T_64BIT
1495 depends on X86_64 || X86_PAE
1497 config ARCH_DMA_ADDR_T_64BIT
1499 depends on X86_64 || HIGHMEM64G
1501 config X86_DIRECT_GBPAGES
1503 depends on X86_64 && !DEBUG_PAGEALLOC
1505 Certain kernel features effectively disable kernel
1506 linear 1 GB mappings (even if the CPU otherwise
1507 supports them), so don't confuse the user by printing
1508 that we have them enabled.
1510 config ARCH_HAS_MEM_ENCRYPT
1513 config AMD_MEM_ENCRYPT
1514 bool "AMD Secure Memory Encryption (SME) support"
1515 depends on X86_64 && CPU_SUP_AMD
1517 Say yes to enable support for the encryption of system memory.
1518 This requires an AMD processor that supports Secure Memory
1521 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1522 bool "Activate AMD Secure Memory Encryption (SME) by default"
1524 depends on AMD_MEM_ENCRYPT
1526 Say yes to have system memory encrypted by default if running on
1527 an AMD processor that supports Secure Memory Encryption (SME).
1529 If set to Y, then the encryption of system memory can be
1530 deactivated with the mem_encrypt=off command line option.
1532 If set to N, then the encryption of system memory can be
1533 activated with the mem_encrypt=on command line option.
1535 config ARCH_USE_MEMREMAP_PROT
1537 depends on AMD_MEM_ENCRYPT
1539 # Common NUMA Features
1541 bool "Numa Memory Allocation and Scheduler Support"
1543 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1544 default y if X86_BIGSMP
1546 Enable NUMA (Non Uniform Memory Access) support.
1548 The kernel will try to allocate memory used by a CPU on the
1549 local memory controller of the CPU and add some more
1550 NUMA awareness to the kernel.
1552 For 64-bit this is recommended if the system is Intel Core i7
1553 (or later), AMD Opteron, or EM64T NUMA.
1555 For 32-bit this is only needed if you boot a 32-bit
1556 kernel on a 64-bit NUMA platform.
1558 Otherwise, you should say N.
1562 prompt "Old style AMD Opteron NUMA detection"
1563 depends on X86_64 && NUMA && PCI
1565 Enable AMD NUMA node topology detection. You should say Y here if
1566 you have a multi processor AMD system. This uses an old method to
1567 read the NUMA configuration directly from the builtin Northbridge
1568 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1569 which also takes priority if both are compiled in.
1571 config X86_64_ACPI_NUMA
1573 prompt "ACPI NUMA detection"
1574 depends on X86_64 && NUMA && ACPI && PCI
1577 Enable ACPI SRAT based node topology detection.
1579 # Some NUMA nodes have memory ranges that span
1580 # other nodes. Even though a pfn is valid and
1581 # between a node's start and end pfns, it may not
1582 # reside on that node. See memmap_init_zone()
1584 config NODES_SPAN_OTHER_NODES
1586 depends on X86_64_ACPI_NUMA
1589 bool "NUMA emulation"
1592 Enable NUMA emulation. A flat machine will be split
1593 into virtual nodes when booted with "numa=fake=N", where N is the
1594 number of nodes. This is only useful for debugging.
1597 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1599 default "10" if MAXSMP
1600 default "6" if X86_64
1602 depends on NEED_MULTIPLE_NODES
1604 Specify the maximum number of NUMA Nodes available on the target
1605 system. Increases memory reserved to accommodate various tables.
1607 config ARCH_HAVE_MEMORY_PRESENT
1609 depends on X86_32 && DISCONTIGMEM
1611 config NEED_NODE_MEMMAP_SIZE
1613 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1615 config ARCH_FLATMEM_ENABLE
1617 depends on X86_32 && !NUMA
1619 config ARCH_DISCONTIGMEM_ENABLE
1621 depends on NUMA && X86_32
1623 config ARCH_DISCONTIGMEM_DEFAULT
1625 depends on NUMA && X86_32
1627 config ARCH_SPARSEMEM_ENABLE
1629 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1630 select SPARSEMEM_STATIC if X86_32
1631 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1633 config ARCH_SPARSEMEM_DEFAULT
1637 config ARCH_SELECT_MEMORY_MODEL
1639 depends on ARCH_SPARSEMEM_ENABLE
1641 config ARCH_MEMORY_PROBE
1642 bool "Enable sysfs memory/probe interface"
1643 depends on X86_64 && MEMORY_HOTPLUG
1645 This option enables a sysfs memory/probe interface for testing.
1646 See Documentation/memory-hotplug.txt for more information.
1647 If you are unsure how to answer this question, answer N.
1649 config ARCH_PROC_KCORE_TEXT
1651 depends on X86_64 && PROC_KCORE
1653 config ILLEGAL_POINTER_VALUE
1656 default 0xdead000000000000 if X86_64
1660 config X86_PMEM_LEGACY_DEVICE
1663 config X86_PMEM_LEGACY
1664 tristate "Support non-standard NVDIMMs and ADR protected memory"
1665 depends on PHYS_ADDR_T_64BIT
1667 select X86_PMEM_LEGACY_DEVICE
1670 Treat memory marked using the non-standard e820 type of 12 as used
1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1672 The kernel will offer these regions to the 'pmem' driver so
1673 they can be used for persistent storage.
1678 bool "Allocate 3rd-level pagetables from highmem"
1681 The VM uses one page table entry for each page of physical memory.
1682 For systems with a lot of RAM, this can be wasteful of precious
1683 low memory. Setting this option will put user-space page table
1684 entries in high memory.
1686 config X86_CHECK_BIOS_CORRUPTION
1687 bool "Check for low memory corruption"
1689 Periodically check for memory corruption in low memory, which
1690 is suspected to be caused by BIOS. Even when enabled in the
1691 configuration, it is disabled at runtime. Enable it by
1692 setting "memory_corruption_check=1" on the kernel command
1693 line. By default it scans the low 64k of memory every 60
1694 seconds; see the memory_corruption_check_size and
1695 memory_corruption_check_period parameters in
1696 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1698 When enabled with the default parameters, this option has
1699 almost no overhead, as it reserves a relatively small amount
1700 of memory and scans it infrequently. It both detects corruption
1701 and prevents it from affecting the running system.
1703 It is, however, intended as a diagnostic tool; if repeatable
1704 BIOS-originated corruption always affects the same memory,
1705 you can use memmap= to prevent the kernel from using that
1708 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1709 bool "Set the default setting of memory_corruption_check"
1710 depends on X86_CHECK_BIOS_CORRUPTION
1713 Set whether the default state of memory_corruption_check is
1716 config X86_RESERVE_LOW
1717 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1721 Specify the amount of low memory to reserve for the BIOS.
1723 The first page contains BIOS data structures that the kernel
1724 must not use, so that page must always be reserved.
1726 By default we reserve the first 64K of physical RAM, as a
1727 number of BIOSes are known to corrupt that memory range
1728 during events such as suspend/resume or monitor cable
1729 insertion, so it must not be used by the kernel.
1731 You can set this to 4 if you are absolutely sure that you
1732 trust the BIOS to get all its memory reservations and usages
1733 right. If you know your BIOS have problems beyond the
1734 default 64K area, you can set this to 640 to avoid using the
1735 entire low memory range.
1737 If you have doubts about the BIOS (e.g. suspend/resume does
1738 not work or there's kernel crashes after certain hardware
1739 hotplug events) then you might want to enable
1740 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1741 typical corruption patterns.
1743 Leave this to the default value of 64 if you are unsure.
1745 config MATH_EMULATION
1747 depends on MODIFY_LDT_SYSCALL
1748 prompt "Math emulation" if X86_32
1750 Linux can emulate a math coprocessor (used for floating point
1751 operations) if you don't have one. 486DX and Pentium processors have
1752 a math coprocessor built in, 486SX and 386 do not, unless you added
1753 a 487DX or 387, respectively. (The messages during boot time can
1754 give you some hints here ["man dmesg"].) Everyone needs either a
1755 coprocessor or this emulation.
1757 If you don't have a math coprocessor, you need to say Y here; if you
1758 say Y here even though you have a coprocessor, the coprocessor will
1759 be used nevertheless. (This behavior can be changed with the kernel
1760 command line option "no387", which comes handy if your coprocessor
1761 is broken. Try "man bootparam" or see the documentation of your boot
1762 loader (lilo or loadlin) about how to pass options to the kernel at
1763 boot time.) This means that it is a good idea to say Y here if you
1764 intend to use this kernel on different machines.
1766 More information about the internals of the Linux math coprocessor
1767 emulation can be found in <file:arch/x86/math-emu/README>.
1769 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1770 kernel, it won't hurt.
1774 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1776 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1777 the Memory Type Range Registers (MTRRs) may be used to control
1778 processor access to memory ranges. This is most useful if you have
1779 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1780 allows bus write transfers to be combined into a larger transfer
1781 before bursting over the PCI/AGP bus. This can increase performance
1782 of image write operations 2.5 times or more. Saying Y here creates a
1783 /proc/mtrr file which may be used to manipulate your processor's
1784 MTRRs. Typically the X server should use this.
1786 This code has a reasonably generic interface so that similar
1787 control registers on other processors can be easily supported
1790 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1791 Registers (ARRs) which provide a similar functionality to MTRRs. For
1792 these, the ARRs are used to emulate the MTRRs.
1793 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1794 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1795 write-combining. All of these processors are supported by this code
1796 and it makes sense to say Y here if you have one of them.
1798 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1799 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1800 can lead to all sorts of problems, so it's good to say Y here.
1802 You can safely say Y even if your machine doesn't have MTRRs, you'll
1803 just add about 9 KB to your kernel.
1805 See <file:Documentation/x86/mtrr.txt> for more information.
1807 config MTRR_SANITIZER
1809 prompt "MTRR cleanup support"
1812 Convert MTRR layout from continuous to discrete, so X drivers can
1813 add writeback entries.
1815 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1816 The largest mtrr entry size for a continuous block can be set with
1821 config MTRR_SANITIZER_ENABLE_DEFAULT
1822 int "MTRR cleanup enable value (0-1)"
1825 depends on MTRR_SANITIZER
1827 Enable mtrr cleanup default value
1829 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1830 int "MTRR cleanup spare reg num (0-7)"
1833 depends on MTRR_SANITIZER
1835 mtrr cleanup spare entries default, it can be changed via
1836 mtrr_spare_reg_nr=N on the kernel command line.
1840 prompt "x86 PAT support" if EXPERT
1843 Use PAT attributes to setup page level cache control.
1845 PATs are the modern equivalents of MTRRs and are much more
1846 flexible than MTRRs.
1848 Say N here if you see bootup problems (boot crash, boot hang,
1849 spontaneous reboots) or a non-working video driver.
1853 config ARCH_USES_PG_UNCACHED
1859 prompt "x86 architectural random number generator" if EXPERT
1861 Enable the x86 architectural RDRAND instruction
1862 (Intel Bull Mountain technology) to generate random numbers.
1863 If supported, this is a high bandwidth, cryptographically
1864 secure hardware random number generator.
1868 prompt "Supervisor Mode Access Prevention" if EXPERT
1870 Supervisor Mode Access Prevention (SMAP) is a security
1871 feature in newer Intel processors. There is a small
1872 performance cost if this enabled and turned on; there is
1873 also a small increase in the kernel size if this is enabled.
1877 config X86_INTEL_UMIP
1879 depends on CPU_SUP_INTEL
1880 prompt "Intel User Mode Instruction Prevention" if EXPERT
1882 The User Mode Instruction Prevention (UMIP) is a security
1883 feature in newer Intel processors. If enabled, a general
1884 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1885 or STR instructions are executed in user mode. These instructions
1886 unnecessarily expose information about the hardware state.
1888 The vast majority of applications do not use these instructions.
1889 For the very few that do, software emulation is provided in
1890 specific cases in protected and virtual-8086 modes. Emulated
1893 config X86_INTEL_MPX
1894 prompt "Intel MPX (Memory Protection Extensions)"
1896 # Note: only available in 64-bit mode due to VMA flags shortage
1897 depends on CPU_SUP_INTEL && X86_64
1898 select ARCH_USES_HIGH_VMA_FLAGS
1900 MPX provides hardware features that can be used in
1901 conjunction with compiler-instrumented code to check
1902 memory references. It is designed to detect buffer
1903 overflow or underflow bugs.
1905 This option enables running applications which are
1906 instrumented or otherwise use MPX. It does not use MPX
1907 itself inside the kernel or to protect the kernel
1908 against bad memory references.
1910 Enabling this option will make the kernel larger:
1911 ~8k of kernel text and 36 bytes of data on a 64-bit
1912 defconfig. It adds a long to the 'mm_struct' which
1913 will increase the kernel memory overhead of each
1914 process and adds some branches to paths used during
1915 exec() and munmap().
1917 For details, see Documentation/x86/intel_mpx.txt
1921 config X86_INTEL_MEMORY_PROTECTION_KEYS
1922 prompt "Intel Memory Protection Keys"
1924 # Note: only available in 64-bit mode
1925 depends on CPU_SUP_INTEL && X86_64
1926 select ARCH_USES_HIGH_VMA_FLAGS
1927 select ARCH_HAS_PKEYS
1929 Memory Protection Keys provides a mechanism for enforcing
1930 page-based protections, but without requiring modification of the
1931 page tables when an application changes protection domains.
1933 For details, see Documentation/x86/protection-keys.txt
1938 bool "EFI runtime service support"
1941 select EFI_RUNTIME_WRAPPERS
1943 This enables the kernel to use EFI runtime services that are
1944 available (such as the EFI variable services).
1946 This option is only useful on systems that have EFI firmware.
1947 In addition, you should use the latest ELILO loader available
1948 at <http://elilo.sourceforge.net> in order to take advantage
1949 of EFI runtime services. However, even with this option, the
1950 resultant kernel should continue to boot on existing non-EFI
1954 bool "EFI stub support"
1955 depends on EFI && !X86_USE_3DNOW
1958 This kernel feature allows a bzImage to be loaded directly
1959 by EFI firmware without the use of a bootloader.
1961 See Documentation/efi-stub.txt for more information.
1964 bool "EFI mixed-mode support"
1965 depends on EFI_STUB && X86_64
1967 Enabling this feature allows a 64-bit kernel to be booted
1968 on a 32-bit firmware, provided that your CPU supports 64-bit
1971 Note that it is not possible to boot a mixed-mode enabled
1972 kernel via the EFI boot stub - a bootloader that supports
1973 the EFI handover protocol must be used.
1979 prompt "Enable seccomp to safely compute untrusted bytecode"
1981 This kernel feature is useful for number crunching applications
1982 that may need to compute untrusted bytecode during their
1983 execution. By using pipes or other transports made available to
1984 the process as file descriptors supporting the read/write
1985 syscalls, it's possible to isolate those applications in
1986 their own address space using seccomp. Once seccomp is
1987 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1988 and the task is only allowed to execute a few safe syscalls
1989 defined by each seccomp mode.
1991 If unsure, say Y. Only embedded should say N here.
1993 source kernel/Kconfig.hz
1996 bool "kexec system call"
1999 kexec is a system call that implements the ability to shutdown your
2000 current kernel, and to start another kernel. It is like a reboot
2001 but it is independent of the system firmware. And like a reboot
2002 you can start any kernel with it, not just Linux.
2004 The name comes from the similarity to the exec system call.
2006 It is an ongoing process to be certain the hardware in a machine
2007 is properly shutdown, so do not be surprised if this code does not
2008 initially work for you. As of this writing the exact hardware
2009 interface is strongly in flux, so no good recommendation can be
2013 bool "kexec file based system call"
2018 depends on CRYPTO_SHA256=y
2020 This is new version of kexec system call. This system call is
2021 file based and takes file descriptors as system call argument
2022 for kernel and initramfs as opposed to list of segments as
2023 accepted by previous system call.
2025 config KEXEC_VERIFY_SIG
2026 bool "Verify kernel signature during kexec_file_load() syscall"
2027 depends on KEXEC_FILE
2029 This option makes kernel signature verification mandatory for
2030 the kexec_file_load() syscall.
2032 In addition to that option, you need to enable signature
2033 verification for the corresponding kernel image type being
2034 loaded in order for this to work.
2036 config KEXEC_BZIMAGE_VERIFY_SIG
2037 bool "Enable bzImage signature verification support"
2038 depends on KEXEC_VERIFY_SIG
2039 depends on SIGNED_PE_FILE_VERIFICATION
2040 select SYSTEM_TRUSTED_KEYRING
2042 Enable bzImage signature verification support.
2045 bool "kernel crash dumps"
2046 depends on X86_64 || (X86_32 && HIGHMEM)
2048 Generate crash dump after being started by kexec.
2049 This should be normally only set in special crash dump kernels
2050 which are loaded in the main kernel with kexec-tools into
2051 a specially reserved region and then later executed after
2052 a crash by kdump/kexec. The crash dump kernel must be compiled
2053 to a memory address not used by the main kernel or BIOS using
2054 PHYSICAL_START, or it must be built as a relocatable image
2055 (CONFIG_RELOCATABLE=y).
2056 For more details see Documentation/kdump/kdump.txt
2060 depends on KEXEC && HIBERNATION
2062 Jump between original kernel and kexeced kernel and invoke
2063 code in physical address mode via KEXEC
2065 config PHYSICAL_START
2066 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2069 This gives the physical address where the kernel is loaded.
2071 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2072 bzImage will decompress itself to above physical address and
2073 run from there. Otherwise, bzImage will run from the address where
2074 it has been loaded by the boot loader and will ignore above physical
2077 In normal kdump cases one does not have to set/change this option
2078 as now bzImage can be compiled as a completely relocatable image
2079 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2080 address. This option is mainly useful for the folks who don't want
2081 to use a bzImage for capturing the crash dump and want to use a
2082 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2083 to be specifically compiled to run from a specific memory area
2084 (normally a reserved region) and this option comes handy.
2086 So if you are using bzImage for capturing the crash dump,
2087 leave the value here unchanged to 0x1000000 and set
2088 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2089 for capturing the crash dump change this value to start of
2090 the reserved region. In other words, it can be set based on
2091 the "X" value as specified in the "crashkernel=YM@XM"
2092 command line boot parameter passed to the panic-ed
2093 kernel. Please take a look at Documentation/kdump/kdump.txt
2094 for more details about crash dumps.
2096 Usage of bzImage for capturing the crash dump is recommended as
2097 one does not have to build two kernels. Same kernel can be used
2098 as production kernel and capture kernel. Above option should have
2099 gone away after relocatable bzImage support is introduced. But it
2100 is present because there are users out there who continue to use
2101 vmlinux for dump capture. This option should go away down the
2104 Don't change this unless you know what you are doing.
2107 bool "Build a relocatable kernel"
2110 This builds a kernel image that retains relocation information
2111 so it can be loaded someplace besides the default 1MB.
2112 The relocations tend to make the kernel binary about 10% larger,
2113 but are discarded at runtime.
2115 One use is for the kexec on panic case where the recovery kernel
2116 must live at a different physical address than the primary
2119 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2120 it has been loaded at and the compile time physical address
2121 (CONFIG_PHYSICAL_START) is used as the minimum location.
2123 config RANDOMIZE_BASE
2124 bool "Randomize the address of the kernel image (KASLR)"
2125 depends on RELOCATABLE
2128 In support of Kernel Address Space Layout Randomization (KASLR),
2129 this randomizes the physical address at which the kernel image
2130 is decompressed and the virtual address where the kernel
2131 image is mapped, as a security feature that deters exploit
2132 attempts relying on knowledge of the location of kernel
2135 On 64-bit, the kernel physical and virtual addresses are
2136 randomized separately. The physical address will be anywhere
2137 between 16MB and the top of physical memory (up to 64TB). The
2138 virtual address will be randomized from 16MB up to 1GB (9 bits
2139 of entropy). Note that this also reduces the memory space
2140 available to kernel modules from 1.5GB to 1GB.
2142 On 32-bit, the kernel physical and virtual addresses are
2143 randomized together. They will be randomized from 16MB up to
2144 512MB (8 bits of entropy).
2146 Entropy is generated using the RDRAND instruction if it is
2147 supported. If RDTSC is supported, its value is mixed into
2148 the entropy pool as well. If neither RDRAND nor RDTSC are
2149 supported, then entropy is read from the i8254 timer. The
2150 usable entropy is limited by the kernel being built using
2151 2GB addressing, and that PHYSICAL_ALIGN must be at a
2152 minimum of 2MB. As a result, only 10 bits of entropy are
2153 theoretically possible, but the implementations are further
2154 limited due to memory layouts.
2158 # Relocation on x86 needs some additional build support
2159 config X86_NEED_RELOCS
2161 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2163 config PHYSICAL_ALIGN
2164 hex "Alignment value to which kernel should be aligned"
2166 range 0x2000 0x1000000 if X86_32
2167 range 0x200000 0x1000000 if X86_64
2169 This value puts the alignment restrictions on physical address
2170 where kernel is loaded and run from. Kernel is compiled for an
2171 address which meets above alignment restriction.
2173 If bootloader loads the kernel at a non-aligned address and
2174 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2175 address aligned to above value and run from there.
2177 If bootloader loads the kernel at a non-aligned address and
2178 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2179 load address and decompress itself to the address it has been
2180 compiled for and run from there. The address for which kernel is
2181 compiled already meets above alignment restrictions. Hence the
2182 end result is that kernel runs from a physical address meeting
2183 above alignment restrictions.
2185 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2186 this value must be a multiple of 0x200000.
2188 Don't change this unless you know what you are doing.
2190 config DYNAMIC_MEMORY_LAYOUT
2193 This option makes base addresses of vmalloc and vmemmap as well as
2194 __PAGE_OFFSET movable during boot.
2196 config RANDOMIZE_MEMORY
2197 bool "Randomize the kernel memory sections"
2199 depends on RANDOMIZE_BASE
2200 select DYNAMIC_MEMORY_LAYOUT
2201 default RANDOMIZE_BASE
2203 Randomizes the base virtual address of kernel memory sections
2204 (physical memory mapping, vmalloc & vmemmap). This security feature
2205 makes exploits relying on predictable memory locations less reliable.
2207 The order of allocations remains unchanged. Entropy is generated in
2208 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2209 configuration have in average 30,000 different possible virtual
2210 addresses for each memory section.
2214 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2215 hex "Physical memory mapping padding" if EXPERT
2216 depends on RANDOMIZE_MEMORY
2217 default "0xa" if MEMORY_HOTPLUG
2219 range 0x1 0x40 if MEMORY_HOTPLUG
2222 Define the padding in terabytes added to the existing physical
2223 memory size during kernel memory randomization. It is useful
2224 for memory hotplug support but reduces the entropy available for
2225 address randomization.
2227 If unsure, leave at the default value.
2230 bool "Support for hot-pluggable CPUs"
2233 Say Y here to allow turning CPUs off and on. CPUs can be
2234 controlled through /sys/devices/system/cpu.
2235 ( Note: power management support will enable this option
2236 automatically on SMP systems. )
2237 Say N if you want to disable CPU hotplug.
2239 config BOOTPARAM_HOTPLUG_CPU0
2240 bool "Set default setting of cpu0_hotpluggable"
2242 depends on HOTPLUG_CPU
2244 Set whether default state of cpu0_hotpluggable is on or off.
2246 Say Y here to enable CPU0 hotplug by default. If this switch
2247 is turned on, there is no need to give cpu0_hotplug kernel
2248 parameter and the CPU0 hotplug feature is enabled by default.
2250 Please note: there are two known CPU0 dependencies if you want
2251 to enable the CPU0 hotplug feature either by this switch or by
2252 cpu0_hotplug kernel parameter.
2254 First, resume from hibernate or suspend always starts from CPU0.
2255 So hibernate and suspend are prevented if CPU0 is offline.
2257 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2258 offline if any interrupt can not migrate out of CPU0. There may
2259 be other CPU0 dependencies.
2261 Please make sure the dependencies are under your control before
2262 you enable this feature.
2264 Say N if you don't want to enable CPU0 hotplug feature by default.
2265 You still can enable the CPU0 hotplug feature at boot by kernel
2266 parameter cpu0_hotplug.
2268 config DEBUG_HOTPLUG_CPU0
2270 prompt "Debug CPU0 hotplug"
2271 depends on HOTPLUG_CPU
2273 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2274 soon as possible and boots up userspace with CPU0 offlined. User
2275 can online CPU0 back after boot time.
2277 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2278 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2279 compilation or giving cpu0_hotplug kernel parameter at boot.
2285 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2286 depends on COMPAT_32
2288 Certain buggy versions of glibc will crash if they are
2289 presented with a 32-bit vDSO that is not mapped at the address
2290 indicated in its segment table.
2292 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2293 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2294 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2295 the only released version with the bug, but OpenSUSE 9
2296 contains a buggy "glibc 2.3.2".
2298 The symptom of the bug is that everything crashes on startup, saying:
2299 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2301 Saying Y here changes the default value of the vdso32 boot
2302 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2303 This works around the glibc bug but hurts performance.
2305 If unsure, say N: if you are compiling your own kernel, you
2306 are unlikely to be using a buggy version of glibc.
2309 prompt "vsyscall table for legacy applications"
2311 default LEGACY_VSYSCALL_EMULATE
2313 Legacy user code that does not know how to find the vDSO expects
2314 to be able to issue three syscalls by calling fixed addresses in
2315 kernel space. Since this location is not randomized with ASLR,
2316 it can be used to assist security vulnerability exploitation.
2318 This setting can be changed at boot time via the kernel command
2319 line parameter vsyscall=[emulate|none].
2321 On a system with recent enough glibc (2.14 or newer) and no
2322 static binaries, you can say None without a performance penalty
2323 to improve security.
2325 If unsure, select "Emulate".
2327 config LEGACY_VSYSCALL_EMULATE
2330 The kernel traps and emulates calls into the fixed
2331 vsyscall address mapping. This makes the mapping
2332 non-executable, but it still contains known contents,
2333 which could be used in certain rare security vulnerability
2334 exploits. This configuration is recommended when userspace
2335 still uses the vsyscall area.
2337 config LEGACY_VSYSCALL_NONE
2340 There will be no vsyscall mapping at all. This will
2341 eliminate any risk of ASLR bypass due to the vsyscall
2342 fixed address mapping. Attempts to use the vsyscalls
2343 will be reported to dmesg, so that either old or
2344 malicious userspace programs can be identified.
2349 bool "Built-in kernel command line"
2351 Allow for specifying boot arguments to the kernel at
2352 build time. On some systems (e.g. embedded ones), it is
2353 necessary or convenient to provide some or all of the
2354 kernel boot arguments with the kernel itself (that is,
2355 to not rely on the boot loader to provide them.)
2357 To compile command line arguments into the kernel,
2358 set this option to 'Y', then fill in the
2359 boot arguments in CONFIG_CMDLINE.
2361 Systems with fully functional boot loaders (i.e. non-embedded)
2362 should leave this option set to 'N'.
2365 string "Built-in kernel command string"
2366 depends on CMDLINE_BOOL
2369 Enter arguments here that should be compiled into the kernel
2370 image and used at boot time. If the boot loader provides a
2371 command line at boot time, it is appended to this string to
2372 form the full kernel command line, when the system boots.
2374 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2375 change this behavior.
2377 In most cases, the command line (whether built-in or provided
2378 by the boot loader) should specify the device for the root
2381 config CMDLINE_OVERRIDE
2382 bool "Built-in command line overrides boot loader arguments"
2383 depends on CMDLINE_BOOL
2385 Set this option to 'Y' to have the kernel ignore the boot loader
2386 command line, and use ONLY the built-in command line.
2388 This is used to work around broken boot loaders. This should
2389 be set to 'N' under normal conditions.
2391 config MODIFY_LDT_SYSCALL
2392 bool "Enable the LDT (local descriptor table)" if EXPERT
2395 Linux can allow user programs to install a per-process x86
2396 Local Descriptor Table (LDT) using the modify_ldt(2) system
2397 call. This is required to run 16-bit or segmented code such as
2398 DOSEMU or some Wine programs. It is also used by some very old
2399 threading libraries.
2401 Enabling this feature adds a small amount of overhead to
2402 context switches and increases the low-level kernel attack
2403 surface. Disabling it removes the modify_ldt(2) system call.
2405 Saying 'N' here may make sense for embedded or server kernels.
2407 source "kernel/livepatch/Kconfig"
2411 config ARCH_HAS_ADD_PAGES
2413 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2415 config ARCH_ENABLE_MEMORY_HOTPLUG
2417 depends on X86_64 || (X86_32 && HIGHMEM)
2419 config ARCH_ENABLE_MEMORY_HOTREMOVE
2421 depends on MEMORY_HOTPLUG
2423 config USE_PERCPU_NUMA_NODE_ID
2427 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2429 depends on X86_64 || X86_PAE
2431 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2433 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2435 config ARCH_ENABLE_THP_MIGRATION
2437 depends on X86_64 && TRANSPARENT_HUGEPAGE
2439 menu "Power management and ACPI options"
2441 config ARCH_HIBERNATION_HEADER
2443 depends on X86_64 && HIBERNATION
2445 source "kernel/power/Kconfig"
2447 source "drivers/acpi/Kconfig"
2449 source "drivers/sfi/Kconfig"
2456 tristate "APM (Advanced Power Management) BIOS support"
2457 depends on X86_32 && PM_SLEEP
2459 APM is a BIOS specification for saving power using several different
2460 techniques. This is mostly useful for battery powered laptops with
2461 APM compliant BIOSes. If you say Y here, the system time will be
2462 reset after a RESUME operation, the /proc/apm device will provide
2463 battery status information, and user-space programs will receive
2464 notification of APM "events" (e.g. battery status change).
2466 If you select "Y" here, you can disable actual use of the APM
2467 BIOS by passing the "apm=off" option to the kernel at boot time.
2469 Note that the APM support is almost completely disabled for
2470 machines with more than one CPU.
2472 In order to use APM, you will need supporting software. For location
2473 and more information, read <file:Documentation/power/apm-acpi.txt>
2474 and the Battery Powered Linux mini-HOWTO, available from
2475 <http://www.tldp.org/docs.html#howto>.
2477 This driver does not spin down disk drives (see the hdparm(8)
2478 manpage ("man 8 hdparm") for that), and it doesn't turn off
2479 VESA-compliant "green" monitors.
2481 This driver does not support the TI 4000M TravelMate and the ACER
2482 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2483 desktop machines also don't have compliant BIOSes, and this driver
2484 may cause those machines to panic during the boot phase.
2486 Generally, if you don't have a battery in your machine, there isn't
2487 much point in using this driver and you should say N. If you get
2488 random kernel OOPSes or reboots that don't seem to be related to
2489 anything, try disabling/enabling this option (or disabling/enabling
2492 Some other things you should try when experiencing seemingly random,
2495 1) make sure that you have enough swap space and that it is
2497 2) pass the "no-hlt" option to the kernel
2498 3) switch on floating point emulation in the kernel and pass
2499 the "no387" option to the kernel
2500 4) pass the "floppy=nodma" option to the kernel
2501 5) pass the "mem=4M" option to the kernel (thereby disabling
2502 all but the first 4 MB of RAM)
2503 6) make sure that the CPU is not over clocked.
2504 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2505 8) disable the cache from your BIOS settings
2506 9) install a fan for the video card or exchange video RAM
2507 10) install a better fan for the CPU
2508 11) exchange RAM chips
2509 12) exchange the motherboard.
2511 To compile this driver as a module, choose M here: the
2512 module will be called apm.
2516 config APM_IGNORE_USER_SUSPEND
2517 bool "Ignore USER SUSPEND"
2519 This option will ignore USER SUSPEND requests. On machines with a
2520 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2521 series notebooks, it is necessary to say Y because of a BIOS bug.
2523 config APM_DO_ENABLE
2524 bool "Enable PM at boot time"
2526 Enable APM features at boot time. From page 36 of the APM BIOS
2527 specification: "When disabled, the APM BIOS does not automatically
2528 power manage devices, enter the Standby State, enter the Suspend
2529 State, or take power saving steps in response to CPU Idle calls."
2530 This driver will make CPU Idle calls when Linux is idle (unless this
2531 feature is turned off -- see "Do CPU IDLE calls", below). This
2532 should always save battery power, but more complicated APM features
2533 will be dependent on your BIOS implementation. You may need to turn
2534 this option off if your computer hangs at boot time when using APM
2535 support, or if it beeps continuously instead of suspending. Turn
2536 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2537 T400CDT. This is off by default since most machines do fine without
2542 bool "Make CPU Idle calls when idle"
2544 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2545 On some machines, this can activate improved power savings, such as
2546 a slowed CPU clock rate, when the machine is idle. These idle calls
2547 are made after the idle loop has run for some length of time (e.g.,
2548 333 mS). On some machines, this will cause a hang at boot time or
2549 whenever the CPU becomes idle. (On machines with more than one CPU,
2550 this option does nothing.)
2552 config APM_DISPLAY_BLANK
2553 bool "Enable console blanking using APM"
2555 Enable console blanking using the APM. Some laptops can use this to
2556 turn off the LCD backlight when the screen blanker of the Linux
2557 virtual console blanks the screen. Note that this is only used by
2558 the virtual console screen blanker, and won't turn off the backlight
2559 when using the X Window system. This also doesn't have anything to
2560 do with your VESA-compliant power-saving monitor. Further, this
2561 option doesn't work for all laptops -- it might not turn off your
2562 backlight at all, or it might print a lot of errors to the console,
2563 especially if you are using gpm.
2565 config APM_ALLOW_INTS
2566 bool "Allow interrupts during APM BIOS calls"
2568 Normally we disable external interrupts while we are making calls to
2569 the APM BIOS as a measure to lessen the effects of a badly behaving
2570 BIOS implementation. The BIOS should reenable interrupts if it
2571 needs to. Unfortunately, some BIOSes do not -- especially those in
2572 many of the newer IBM Thinkpads. If you experience hangs when you
2573 suspend, try setting this to Y. Otherwise, say N.
2577 source "drivers/cpufreq/Kconfig"
2579 source "drivers/cpuidle/Kconfig"
2581 source "drivers/idle/Kconfig"
2586 menu "Bus options (PCI etc.)"
2592 Find out whether you have a PCI motherboard. PCI is the name of a
2593 bus system, i.e. the way the CPU talks to the other stuff inside
2594 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2595 VESA. If you have PCI, say Y, otherwise N.
2598 prompt "PCI access mode"
2599 depends on X86_32 && PCI
2602 On PCI systems, the BIOS can be used to detect the PCI devices and
2603 determine their configuration. However, some old PCI motherboards
2604 have BIOS bugs and may crash if this is done. Also, some embedded
2605 PCI-based systems don't have any BIOS at all. Linux can also try to
2606 detect the PCI hardware directly without using the BIOS.
2608 With this option, you can specify how Linux should detect the
2609 PCI devices. If you choose "BIOS", the BIOS will be used,
2610 if you choose "Direct", the BIOS won't be used, and if you
2611 choose "MMConfig", then PCI Express MMCONFIG will be used.
2612 If you choose "Any", the kernel will try MMCONFIG, then the
2613 direct access method and falls back to the BIOS if that doesn't
2614 work. If unsure, go with the default, which is "Any".
2619 config PCI_GOMMCONFIG
2636 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2638 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2641 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2645 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2649 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2653 depends on PCI && XEN
2661 bool "Support mmconfig PCI config space access"
2662 depends on X86_64 && PCI && ACPI
2664 config PCI_CNB20LE_QUIRK
2665 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2668 Read the PCI windows out of the CNB20LE host bridge. This allows
2669 PCI hotplug to work on systems with the CNB20LE chipset which do
2672 There's no public spec for this chipset, and this functionality
2673 is known to be incomplete.
2675 You should say N unless you know you need this.
2677 source "drivers/pci/Kconfig"
2680 bool "ISA-style bus support on modern systems" if EXPERT
2683 Enables ISA-style drivers on modern systems. This is necessary to
2684 support PC/104 devices on X86_64 platforms.
2688 # x86_64 have no ISA slots, but can have ISA-style DMA.
2690 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2693 Enables ISA-style DMA support for devices requiring such controllers.
2701 Find out whether you have ISA slots on your motherboard. ISA is the
2702 name of a bus system, i.e. the way the CPU talks to the other stuff
2703 inside your box. Other bus systems are PCI, EISA, MicroChannel
2704 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2705 newer boards don't support it. If you have ISA, say Y, otherwise N.
2711 The Extended Industry Standard Architecture (EISA) bus was
2712 developed as an open alternative to the IBM MicroChannel bus.
2714 The EISA bus provided some of the features of the IBM MicroChannel
2715 bus while maintaining backward compatibility with cards made for
2716 the older ISA bus. The EISA bus saw limited use between 1988 and
2717 1995 when it was made obsolete by the PCI bus.
2719 Say Y here if you are building a kernel for an EISA-based machine.
2723 source "drivers/eisa/Kconfig"
2726 tristate "NatSemi SCx200 support"
2728 This provides basic support for National Semiconductor's
2729 (now AMD's) Geode processors. The driver probes for the
2730 PCI-IDs of several on-chip devices, so its a good dependency
2731 for other scx200_* drivers.
2733 If compiled as a module, the driver is named scx200.
2735 config SCx200HR_TIMER
2736 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2740 This driver provides a clocksource built upon the on-chip
2741 27MHz high-resolution timer. Its also a workaround for
2742 NSC Geode SC-1100's buggy TSC, which loses time when the
2743 processor goes idle (as is done by the scheduler). The
2744 other workaround is idle=poll boot option.
2747 bool "One Laptop Per Child support"
2754 Add support for detecting the unique features of the OLPC
2758 bool "OLPC XO-1 Power Management"
2759 depends on OLPC && MFD_CS5535 && PM_SLEEP
2762 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2765 bool "OLPC XO-1 Real Time Clock"
2766 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2768 Add support for the XO-1 real time clock, which can be used as a
2769 programmable wakeup source.
2772 bool "OLPC XO-1 SCI extras"
2773 depends on OLPC && OLPC_XO1_PM
2779 Add support for SCI-based features of the OLPC XO-1 laptop:
2780 - EC-driven system wakeups
2784 - AC adapter status updates
2785 - Battery status updates
2787 config OLPC_XO15_SCI
2788 bool "OLPC XO-1.5 SCI extras"
2789 depends on OLPC && ACPI
2792 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2793 - EC-driven system wakeups
2794 - AC adapter status updates
2795 - Battery status updates
2798 bool "PCEngines ALIX System Support (LED setup)"
2801 This option enables system support for the PCEngines ALIX.
2802 At present this just sets up LEDs for GPIO control on
2803 ALIX2/3/6 boards. However, other system specific setup should
2806 Note: You must still enable the drivers for GPIO and LED support
2807 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2809 Note: You have to set alix.force=1 for boards with Award BIOS.
2812 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2815 This option enables system support for the Soekris Engineering net5501.
2818 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2822 This option enables system support for the Traverse Technologies GEOS.
2825 bool "Technologic Systems TS-5500 platform support"
2827 select CHECK_SIGNATURE
2831 This option enables system support for the Technologic Systems TS-5500.
2837 depends on CPU_SUP_AMD && PCI
2839 source "drivers/pcmcia/Kconfig"
2842 tristate "RapidIO support"
2846 If enabled this option will include drivers and the core
2847 infrastructure code to support RapidIO interconnect devices.
2849 source "drivers/rapidio/Kconfig"
2852 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2854 Firmwares often provide initial graphics framebuffers so the BIOS,
2855 bootloader or kernel can show basic video-output during boot for
2856 user-guidance and debugging. Historically, x86 used the VESA BIOS
2857 Extensions and EFI-framebuffers for this, which are mostly limited
2859 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2860 framebuffers so the new generic system-framebuffer drivers can be
2861 used on x86. If the framebuffer is not compatible with the generic
2862 modes, it is adverticed as fallback platform framebuffer so legacy
2863 drivers like efifb, vesafb and uvesafb can pick it up.
2864 If this option is not selected, all system framebuffers are always
2865 marked as fallback platform framebuffers as usual.
2867 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2868 not be able to pick up generic system framebuffers if this option
2869 is selected. You are highly encouraged to enable simplefb as
2870 replacement if you select this option. simplefb can correctly deal
2871 with generic system framebuffers. But you should still keep vesafb
2872 and others enabled as fallback if a system framebuffer is
2873 incompatible with simplefb.
2880 menu "Executable file formats / Emulations"
2882 source "fs/Kconfig.binfmt"
2884 config IA32_EMULATION
2885 bool "IA32 Emulation"
2887 select ARCH_WANT_OLD_COMPAT_IPC
2889 select COMPAT_BINFMT_ELF
2890 select COMPAT_OLD_SIGACTION
2892 Include code to run legacy 32-bit programs under a
2893 64-bit kernel. You should likely turn this on, unless you're
2894 100% sure that you don't have any 32-bit programs left.
2897 tristate "IA32 a.out support"
2898 depends on IA32_EMULATION
2900 Support old a.out binaries in the 32bit emulation.
2903 bool "x32 ABI for 64-bit mode"
2906 Include code to run binaries for the x32 native 32-bit ABI
2907 for 64-bit processors. An x32 process gets access to the
2908 full 64-bit register file and wide data path while leaving
2909 pointers at 32 bits for smaller memory footprint.
2911 You will need a recent binutils (2.22 or later) with
2912 elf32_x86_64 support enabled to compile a kernel with this
2917 depends on IA32_EMULATION || X86_32
2919 select OLD_SIGSUSPEND3
2923 depends on IA32_EMULATION || X86_X32
2926 config COMPAT_FOR_U64_ALIGNMENT
2929 config SYSVIPC_COMPAT
2937 config HAVE_ATOMIC_IOMAP
2941 config X86_DEV_DMA_OPS
2943 depends on X86_64 || STA2X11
2945 config X86_DMA_REMAP
2949 config HAVE_GENERIC_GUP
2952 source "net/Kconfig"
2954 source "drivers/Kconfig"
2956 source "drivers/firmware/Kconfig"
2960 source "arch/x86/Kconfig.debug"
2962 source "security/Kconfig"
2964 source "crypto/Kconfig"
2966 source "arch/x86/kvm/Kconfig"
2968 source "lib/Kconfig"
projects / linux-2.6-microblaze.git / blob