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
427 bool "Support for big SMP systems with more than 8 CPUs"
428 depends on X86_32 && SMP
430 This option is needed for the systems that have more than 8 CPUs
434 depends on X86_GOLDFISH
437 bool "Avoid speculative indirect branches in kernel"
440 Compile kernel with the retpoline compiler options to guard against
441 kernel-to-user data leaks by avoiding speculative indirect
442 branches. Requires a compiler with -mindirect-branch=thunk-extern
443 support for full protection. The kernel may run slower.
445 Without compiler support, at least indirect branches in assembler
446 code are eliminated. Since this includes the syscall entry path,
447 it is not entirely pointless.
450 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.
463 config X86_EXTENDED_PLATFORM
464 bool "Support for extended (non-PC) x86 platforms"
467 If you disable this option then the kernel will only support
468 standard PC platforms. (which covers the vast majority of
471 If you enable this option then you'll be able to select support
472 for the following (non-PC) 32 bit x86 platforms:
473 Goldfish (Android emulator)
476 SGI 320/540 (Visual Workstation)
477 STA2X11-based (e.g. Northville)
478 Moorestown MID devices
480 If you have one of these systems, or if you want to build a
481 generic distribution kernel, say Y here - otherwise say N.
485 config X86_EXTENDED_PLATFORM
486 bool "Support for extended (non-PC) x86 platforms"
489 If you disable this option then the kernel will only support
490 standard PC platforms. (which covers the vast majority of
493 If you enable this option then you'll be able to select support
494 for the following (non-PC) 64 bit x86 platforms:
499 If you have one of these systems, or if you want to build a
500 generic distribution kernel, say Y here - otherwise say N.
502 # This is an alphabetically sorted list of 64 bit extended platforms
503 # Please maintain the alphabetic order if and when there are additions
505 bool "Numascale NumaChip"
507 depends on X86_EXTENDED_PLATFORM
510 depends on X86_X2APIC
511 depends on PCI_MMCONFIG
513 Adds support for Numascale NumaChip large-SMP systems. Needed to
514 enable more than ~168 cores.
515 If you don't have one of these, you should say N here.
519 select HYPERVISOR_GUEST
521 depends on X86_64 && PCI
522 depends on X86_EXTENDED_PLATFORM
525 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
526 supposed to run on these EM64T-based machines. Only choose this option
527 if you have one of these machines.
530 bool "SGI Ultraviolet"
532 depends on X86_EXTENDED_PLATFORM
535 depends on X86_X2APIC
538 This option is needed in order to support SGI Ultraviolet systems.
539 If you don't have one of these, you should say N here.
541 # Following is an alphabetically sorted list of 32 bit extended platforms
542 # Please maintain the alphabetic order if and when there are additions
545 bool "Goldfish (Virtual Platform)"
546 depends on X86_EXTENDED_PLATFORM
548 Enable support for the Goldfish virtual platform used primarily
549 for Android development. Unless you are building for the Android
550 Goldfish emulator say N here.
553 bool "CE4100 TV platform"
555 depends on PCI_GODIRECT
556 depends on X86_IO_APIC
558 depends on X86_EXTENDED_PLATFORM
559 select X86_REBOOTFIXUPS
561 select OF_EARLY_FLATTREE
563 Select for the Intel CE media processor (CE4100) SOC.
564 This option compiles in support for the CE4100 SOC for settop
565 boxes and media devices.
568 bool "Intel MID platform support"
569 depends on X86_EXTENDED_PLATFORM
570 depends on X86_PLATFORM_DEVICES
572 depends on X86_64 || (PCI_GOANY && X86_32)
573 depends on X86_IO_APIC
579 select MFD_INTEL_MSIC
581 Select to build a kernel capable of supporting Intel MID (Mobile
582 Internet Device) platform systems which do not have the PCI legacy
583 interfaces. If you are building for a PC class system say N here.
585 Intel MID platforms are based on an Intel processor and chipset which
586 consume less power than most of the x86 derivatives.
588 config X86_INTEL_QUARK
589 bool "Intel Quark platform support"
591 depends on X86_EXTENDED_PLATFORM
592 depends on X86_PLATFORM_DEVICES
596 depends on X86_IO_APIC
601 Select to include support for Quark X1000 SoC.
602 Say Y here if you have a Quark based system such as the Arduino
603 compatible Intel Galileo.
605 config X86_INTEL_LPSS
606 bool "Intel Low Power Subsystem Support"
607 depends on X86 && ACPI
612 Select to build support for Intel Low Power Subsystem such as
613 found on Intel Lynxpoint PCH. Selecting this option enables
614 things like clock tree (common clock framework) and pincontrol
615 which are needed by the LPSS peripheral drivers.
617 config X86_AMD_PLATFORM_DEVICE
618 bool "AMD ACPI2Platform devices support"
623 Select to interpret AMD specific ACPI device to platform device
624 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
625 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
626 implemented under PINCTRL subsystem.
629 tristate "Intel SoC IOSF Sideband support for SoC platforms"
632 This option enables sideband register access support for Intel SoC
633 platforms. On these platforms the IOSF sideband is used in lieu of
634 MSR's for some register accesses, mostly but not limited to thermal
635 and power. Drivers may query the availability of this device to
636 determine if they need the sideband in order to work on these
637 platforms. The sideband is available on the following SoC products.
638 This list is not meant to be exclusive.
643 You should say Y if you are running a kernel on one of these SoC's.
645 config IOSF_MBI_DEBUG
646 bool "Enable IOSF sideband access through debugfs"
647 depends on IOSF_MBI && DEBUG_FS
649 Select this option to expose the IOSF sideband access registers (MCR,
650 MDR, MCRX) through debugfs to write and read register information from
651 different units on the SoC. This is most useful for obtaining device
652 state information for debug and analysis. As this is a general access
653 mechanism, users of this option would have specific knowledge of the
654 device they want to access.
656 If you don't require the option or are in doubt, say N.
659 bool "RDC R-321x SoC"
661 depends on X86_EXTENDED_PLATFORM
663 select X86_REBOOTFIXUPS
665 This option is needed for RDC R-321x system-on-chip, also known
667 If you don't have one of these chips, you should say N here.
669 config X86_32_NON_STANDARD
670 bool "Support non-standard 32-bit SMP architectures"
671 depends on X86_32 && SMP
672 depends on X86_EXTENDED_PLATFORM
674 This option compiles in the bigsmp and STA2X11 default
675 subarchitectures. It is intended for a generic binary
676 kernel. If you select them all, kernel will probe it one by
677 one and will fallback to default.
679 # Alphabetically sorted list of Non standard 32 bit platforms
681 config X86_SUPPORTS_MEMORY_FAILURE
683 # MCE code calls memory_failure():
685 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
686 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
687 depends on X86_64 || !SPARSEMEM
688 select ARCH_SUPPORTS_MEMORY_FAILURE
691 bool "STA2X11 Companion Chip Support"
692 depends on X86_32_NON_STANDARD && PCI
693 select X86_DEV_DMA_OPS
700 This adds support for boards based on the STA2X11 IO-Hub,
701 a.k.a. "ConneXt". The chip is used in place of the standard
702 PC chipset, so all "standard" peripherals are missing. If this
703 option is selected the kernel will still be able to boot on
704 standard PC machines.
707 tristate "Eurobraille/Iris poweroff module"
710 The Iris machines from EuroBraille do not have APM or ACPI support
711 to shut themselves down properly. A special I/O sequence is
712 needed to do so, which is what this module does at
715 This is only for Iris machines from EuroBraille.
719 config SCHED_OMIT_FRAME_POINTER
721 prompt "Single-depth WCHAN output"
724 Calculate simpler /proc/<PID>/wchan values. If this option
725 is disabled then wchan values will recurse back to the
726 caller function. This provides more accurate wchan values,
727 at the expense of slightly more scheduling overhead.
729 If in doubt, say "Y".
731 menuconfig HYPERVISOR_GUEST
732 bool "Linux guest support"
734 Say Y here to enable options for running Linux under various hyper-
735 visors. This option enables basic hypervisor detection and platform
738 If you say N, all options in this submenu will be skipped and
739 disabled, and Linux guest support won't be built in.
744 bool "Enable paravirtualization code"
746 This changes the kernel so it can modify itself when it is run
747 under a hypervisor, potentially improving performance significantly
748 over full virtualization. However, when run without a hypervisor
749 the kernel is theoretically slower and slightly larger.
751 config PARAVIRT_DEBUG
752 bool "paravirt-ops debugging"
753 depends on PARAVIRT && DEBUG_KERNEL
755 Enable to debug paravirt_ops internals. Specifically, BUG if
756 a paravirt_op is missing when it is called.
758 config PARAVIRT_SPINLOCKS
759 bool "Paravirtualization layer for spinlocks"
760 depends on PARAVIRT && SMP
762 Paravirtualized spinlocks allow a pvops backend to replace the
763 spinlock implementation with something virtualization-friendly
764 (for example, block the virtual CPU rather than spinning).
766 It has a minimal impact on native kernels and gives a nice performance
767 benefit on paravirtualized KVM / Xen kernels.
769 If you are unsure how to answer this question, answer Y.
771 config QUEUED_LOCK_STAT
772 bool "Paravirt queued spinlock statistics"
773 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
775 Enable the collection of statistical data on the slowpath
776 behavior of paravirtualized queued spinlocks and report
779 source "arch/x86/xen/Kconfig"
782 bool "KVM Guest support (including kvmclock)"
784 select PARAVIRT_CLOCK
787 This option enables various optimizations for running under the KVM
788 hypervisor. It includes a paravirtualized clock, so that instead
789 of relying on a PIT (or probably other) emulation by the
790 underlying device model, the host provides the guest with
791 timing infrastructure such as time of day, and system time
794 bool "Enable debug information for KVM Guests in debugfs"
795 depends on KVM_GUEST && DEBUG_FS
798 This option enables collection of various statistics for KVM guest.
799 Statistics are displayed in debugfs filesystem. Enabling this option
800 may incur significant overhead.
802 config PARAVIRT_TIME_ACCOUNTING
803 bool "Paravirtual steal time accounting"
807 Select this option to enable fine granularity task steal time
808 accounting. Time spent executing other tasks in parallel with
809 the current vCPU is discounted from the vCPU power. To account for
810 that, there can be a small performance impact.
812 If in doubt, say N here.
814 config PARAVIRT_CLOCK
817 config JAILHOUSE_GUEST
818 bool "Jailhouse non-root cell support"
819 depends on X86_64 && PCI
822 This option allows to run Linux as guest in a Jailhouse non-root
823 cell. You can leave this option disabled if you only want to start
824 Jailhouse and run Linux afterwards in the root cell.
826 endif #HYPERVISOR_GUEST
831 source "arch/x86/Kconfig.cpu"
835 prompt "HPET Timer Support" if X86_32
837 Use the IA-PC HPET (High Precision Event Timer) to manage
838 time in preference to the PIT and RTC, if a HPET is
840 HPET is the next generation timer replacing legacy 8254s.
841 The HPET provides a stable time base on SMP
842 systems, unlike the TSC, but it is more expensive to access,
843 as it is off-chip. The interface used is documented
844 in the HPET spec, revision 1.
846 You can safely choose Y here. However, HPET will only be
847 activated if the platform and the BIOS support this feature.
848 Otherwise the 8254 will be used for timing services.
850 Choose N to continue using the legacy 8254 timer.
852 config HPET_EMULATE_RTC
854 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
857 def_bool y if X86_INTEL_MID
858 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
860 depends on X86_INTEL_MID && SFI
862 APB timer is the replacement for 8254, HPET on X86 MID platforms.
863 The APBT provides a stable time base on SMP
864 systems, unlike the TSC, but it is more expensive to access,
865 as it is off-chip. APB timers are always running regardless of CPU
866 C states, they are used as per CPU clockevent device when possible.
868 # Mark as expert because too many people got it wrong.
869 # The code disables itself when not needed.
872 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
873 bool "Enable DMI scanning" if EXPERT
875 Enabled scanning of DMI to identify machine quirks. Say Y
876 here unless you have verified that your setup is not
877 affected by entries in the DMI blacklist. Required by PNP
881 bool "Old AMD GART IOMMU support"
883 depends on X86_64 && PCI && AMD_NB
885 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
886 GART based hardware IOMMUs.
888 The GART supports full DMA access for devices with 32-bit access
889 limitations, on systems with more than 3 GB. This is usually needed
890 for USB, sound, many IDE/SATA chipsets and some other devices.
892 Newer systems typically have a modern AMD IOMMU, supported via
893 the CONFIG_AMD_IOMMU=y config option.
895 In normal configurations this driver is only active when needed:
896 there's more than 3 GB of memory and the system contains a
897 32-bit limited device.
902 bool "IBM Calgary IOMMU support"
904 depends on X86_64 && PCI
906 Support for hardware IOMMUs in IBM's xSeries x366 and x460
907 systems. Needed to run systems with more than 3GB of memory
908 properly with 32-bit PCI devices that do not support DAC
909 (Double Address Cycle). Calgary also supports bus level
910 isolation, where all DMAs pass through the IOMMU. This
911 prevents them from going anywhere except their intended
912 destination. This catches hard-to-find kernel bugs and
913 mis-behaving drivers and devices that do not use the DMA-API
914 properly to set up their DMA buffers. The IOMMU can be
915 turned off at boot time with the iommu=off parameter.
916 Normally the kernel will make the right choice by itself.
919 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
921 prompt "Should Calgary be enabled by default?"
922 depends on CALGARY_IOMMU
924 Should Calgary be enabled by default? if you choose 'y', Calgary
925 will be used (if it exists). If you choose 'n', Calgary will not be
926 used even if it exists. If you choose 'n' and would like to use
927 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
930 # need this always selected by IOMMU for the VIA workaround
934 Support for software bounce buffers used on x86-64 systems
935 which don't have a hardware IOMMU. Using this PCI devices
936 which can only access 32-bits of memory can be used on systems
937 with more than 3 GB of memory.
942 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
945 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
946 depends on X86_64 && SMP && DEBUG_KERNEL
947 select CPUMASK_OFFSTACK
949 Enable maximum number of CPUS and NUMA Nodes for this architecture.
953 int "Maximum number of CPUs" if SMP && !MAXSMP
954 range 2 8 if SMP && X86_32 && !X86_BIGSMP
955 range 2 64 if SMP && X86_32 && X86_BIGSMP
956 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
957 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
959 default "8192" if MAXSMP
960 default "32" if SMP && X86_BIGSMP
961 default "8" if SMP && X86_32
964 This allows you to specify the maximum number of CPUs which this
965 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
966 supported value is 8192, otherwise the maximum value is 512. The
967 minimum value which makes sense is 2.
969 This is purely to save memory - each supported CPU adds
970 approximately eight kilobytes to the kernel image.
973 bool "SMT (Hyperthreading) scheduler support"
976 SMT scheduler support improves the CPU scheduler's decision making
977 when dealing with Intel Pentium 4 chips with HyperThreading at a
978 cost of slightly increased overhead in some places. If unsure say
983 prompt "Multi-core scheduler support"
986 Multi-core scheduler support improves the CPU scheduler's decision
987 making when dealing with multi-core CPU chips at a cost of slightly
988 increased overhead in some places. If unsure say N here.
991 bool "CPU core priorities scheduler support"
992 depends on SCHED_MC && CPU_SUP_INTEL
993 select X86_INTEL_PSTATE
997 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
998 core ordering determined at manufacturing time, which allows
999 certain cores to reach higher turbo frequencies (when running
1000 single threaded workloads) than others.
1002 Enabling this kernel feature teaches the scheduler about
1003 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1004 scheduler's CPU selection logic accordingly, so that higher
1005 overall system performance can be achieved.
1007 This feature will have no effect on CPUs without this feature.
1009 If unsure say Y here.
1011 source "kernel/Kconfig.preempt"
1015 depends on !SMP && X86_LOCAL_APIC
1018 bool "Local APIC support on uniprocessors" if !PCI_MSI
1020 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1022 A local APIC (Advanced Programmable Interrupt Controller) is an
1023 integrated interrupt controller in the CPU. If you have a single-CPU
1024 system which has a processor with a local APIC, you can say Y here to
1025 enable and use it. If you say Y here even though your machine doesn't
1026 have a local APIC, then the kernel will still run with no slowdown at
1027 all. The local APIC supports CPU-generated self-interrupts (timer,
1028 performance counters), and the NMI watchdog which detects hard
1031 config X86_UP_IOAPIC
1032 bool "IO-APIC support on uniprocessors"
1033 depends on X86_UP_APIC
1035 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1036 SMP-capable replacement for PC-style interrupt controllers. Most
1037 SMP systems and many recent uniprocessor systems have one.
1039 If you have a single-CPU system with an IO-APIC, you can say Y here
1040 to use it. If you say Y here even though your machine doesn't have
1041 an IO-APIC, then the kernel will still run with no slowdown at all.
1043 config X86_LOCAL_APIC
1045 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1046 select IRQ_DOMAIN_HIERARCHY
1047 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1051 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1053 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1054 bool "Reroute for broken boot IRQs"
1055 depends on X86_IO_APIC
1057 This option enables a workaround that fixes a source of
1058 spurious interrupts. This is recommended when threaded
1059 interrupt handling is used on systems where the generation of
1060 superfluous "boot interrupts" cannot be disabled.
1062 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1063 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1064 kernel does during interrupt handling). On chipsets where this
1065 boot IRQ generation cannot be disabled, this workaround keeps
1066 the original IRQ line masked so that only the equivalent "boot
1067 IRQ" is delivered to the CPUs. The workaround also tells the
1068 kernel to set up the IRQ handler on the boot IRQ line. In this
1069 way only one interrupt is delivered to the kernel. Otherwise
1070 the spurious second interrupt may cause the kernel to bring
1071 down (vital) interrupt lines.
1073 Only affects "broken" chipsets. Interrupt sharing may be
1074 increased on these systems.
1077 bool "Machine Check / overheating reporting"
1078 select GENERIC_ALLOCATOR
1081 Machine Check support allows the processor to notify the
1082 kernel if it detects a problem (e.g. overheating, data corruption).
1083 The action the kernel takes depends on the severity of the problem,
1084 ranging from warning messages to halting the machine.
1086 config X86_MCELOG_LEGACY
1087 bool "Support for deprecated /dev/mcelog character device"
1090 Enable support for /dev/mcelog which is needed by the old mcelog
1091 userspace logging daemon. Consider switching to the new generation
1094 config X86_MCE_INTEL
1096 prompt "Intel MCE features"
1097 depends on X86_MCE && X86_LOCAL_APIC
1099 Additional support for intel specific MCE features such as
1100 the thermal monitor.
1104 prompt "AMD MCE features"
1105 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1107 Additional support for AMD specific MCE features such as
1108 the DRAM Error Threshold.
1110 config X86_ANCIENT_MCE
1111 bool "Support for old Pentium 5 / WinChip machine checks"
1112 depends on X86_32 && X86_MCE
1114 Include support for machine check handling on old Pentium 5 or WinChip
1115 systems. These typically need to be enabled explicitly on the command
1118 config X86_MCE_THRESHOLD
1119 depends on X86_MCE_AMD || X86_MCE_INTEL
1122 config X86_MCE_INJECT
1123 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1124 tristate "Machine check injector support"
1126 Provide support for injecting machine checks for testing purposes.
1127 If you don't know what a machine check is and you don't do kernel
1128 QA it is safe to say n.
1130 config X86_THERMAL_VECTOR
1132 depends on X86_MCE_INTEL
1134 source "arch/x86/events/Kconfig"
1136 config X86_LEGACY_VM86
1137 bool "Legacy VM86 support"
1141 This option allows user programs to put the CPU into V8086
1142 mode, which is an 80286-era approximation of 16-bit real mode.
1144 Some very old versions of X and/or vbetool require this option
1145 for user mode setting. Similarly, DOSEMU will use it if
1146 available to accelerate real mode DOS programs. However, any
1147 recent version of DOSEMU, X, or vbetool should be fully
1148 functional even without kernel VM86 support, as they will all
1149 fall back to software emulation. Nevertheless, if you are using
1150 a 16-bit DOS program where 16-bit performance matters, vm86
1151 mode might be faster than emulation and you might want to
1154 Note that any app that works on a 64-bit kernel is unlikely to
1155 need this option, as 64-bit kernels don't, and can't, support
1156 V8086 mode. This option is also unrelated to 16-bit protected
1157 mode and is not needed to run most 16-bit programs under Wine.
1159 Enabling this option increases the complexity of the kernel
1160 and slows down exception handling a tiny bit.
1162 If unsure, say N here.
1166 default X86_LEGACY_VM86
1169 bool "Enable support for 16-bit segments" if EXPERT
1171 depends on MODIFY_LDT_SYSCALL
1173 This option is required by programs like Wine to run 16-bit
1174 protected mode legacy code on x86 processors. Disabling
1175 this option saves about 300 bytes on i386, or around 6K text
1176 plus 16K runtime memory on x86-64,
1180 depends on X86_16BIT && X86_32
1184 depends on X86_16BIT && X86_64
1186 config X86_VSYSCALL_EMULATION
1187 bool "Enable vsyscall emulation" if EXPERT
1191 This enables emulation of the legacy vsyscall page. Disabling
1192 it is roughly equivalent to booting with vsyscall=none, except
1193 that it will also disable the helpful warning if a program
1194 tries to use a vsyscall. With this option set to N, offending
1195 programs will just segfault, citing addresses of the form
1198 This option is required by many programs built before 2013, and
1199 care should be used even with newer programs if set to N.
1201 Disabling this option saves about 7K of kernel size and
1202 possibly 4K of additional runtime pagetable memory.
1205 tristate "Toshiba Laptop support"
1208 This adds a driver to safely access the System Management Mode of
1209 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1210 not work on models with a Phoenix BIOS. The System Management Mode
1211 is used to set the BIOS and power saving options on Toshiba portables.
1213 For information on utilities to make use of this driver see the
1214 Toshiba Linux utilities web site at:
1215 <http://www.buzzard.org.uk/toshiba/>.
1217 Say Y if you intend to run this kernel on a Toshiba portable.
1221 tristate "Dell i8k legacy laptop support"
1223 select SENSORS_DELL_SMM
1225 This option enables legacy /proc/i8k userspace interface in hwmon
1226 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1227 temperature and allows controlling fan speeds of Dell laptops via
1228 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1229 it reports also power and hotkey status. For fan speed control is
1230 needed userspace package i8kutils.
1232 Say Y if you intend to run this kernel on old Dell laptops or want to
1233 use userspace package i8kutils.
1236 config X86_REBOOTFIXUPS
1237 bool "Enable X86 board specific fixups for reboot"
1240 This enables chipset and/or board specific fixups to be done
1241 in order to get reboot to work correctly. This is only needed on
1242 some combinations of hardware and BIOS. The symptom, for which
1243 this config is intended, is when reboot ends with a stalled/hung
1246 Currently, the only fixup is for the Geode machines using
1247 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1249 Say Y if you want to enable the fixup. Currently, it's safe to
1250 enable this option even if you don't need it.
1254 bool "CPU microcode loading support"
1256 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1259 If you say Y here, you will be able to update the microcode on
1260 Intel and AMD processors. The Intel support is for the IA32 family,
1261 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1262 AMD support is for families 0x10 and later. You will obviously need
1263 the actual microcode binary data itself which is not shipped with
1266 The preferred method to load microcode from a detached initrd is described
1267 in Documentation/x86/early-microcode.txt. For that you need to enable
1268 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1269 initrd for microcode blobs.
1271 In addition, you can build the microcode into the kernel. For that you
1272 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1275 config MICROCODE_INTEL
1276 bool "Intel microcode loading support"
1277 depends on MICROCODE
1281 This options enables microcode patch loading support for Intel
1284 For the current Intel microcode data package go to
1285 <https://downloadcenter.intel.com> and search for
1286 'Linux Processor Microcode Data File'.
1288 config MICROCODE_AMD
1289 bool "AMD microcode loading support"
1290 depends on MICROCODE
1293 If you select this option, microcode patch loading support for AMD
1294 processors will be enabled.
1296 config MICROCODE_OLD_INTERFACE
1298 depends on MICROCODE
1301 tristate "/dev/cpu/*/msr - Model-specific register support"
1303 This device gives privileged processes access to the x86
1304 Model-Specific Registers (MSRs). It is a character device with
1305 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1306 MSR accesses are directed to a specific CPU on multi-processor
1310 tristate "/dev/cpu/*/cpuid - CPU information support"
1312 This device gives processes access to the x86 CPUID instruction to
1313 be executed on a specific processor. It is a character device
1314 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1318 prompt "High Memory Support"
1325 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1326 However, the address space of 32-bit x86 processors is only 4
1327 Gigabytes large. That means that, if you have a large amount of
1328 physical memory, not all of it can be "permanently mapped" by the
1329 kernel. The physical memory that's not permanently mapped is called
1332 If you are compiling a kernel which will never run on a machine with
1333 more than 1 Gigabyte total physical RAM, answer "off" here (default
1334 choice and suitable for most users). This will result in a "3GB/1GB"
1335 split: 3GB are mapped so that each process sees a 3GB virtual memory
1336 space and the remaining part of the 4GB virtual memory space is used
1337 by the kernel to permanently map as much physical memory as
1340 If the machine has between 1 and 4 Gigabytes physical RAM, then
1343 If more than 4 Gigabytes is used then answer "64GB" here. This
1344 selection turns Intel PAE (Physical Address Extension) mode on.
1345 PAE implements 3-level paging on IA32 processors. PAE is fully
1346 supported by Linux, PAE mode is implemented on all recent Intel
1347 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1348 then the kernel will not boot on CPUs that don't support PAE!
1350 The actual amount of total physical memory will either be
1351 auto detected or can be forced by using a kernel command line option
1352 such as "mem=256M". (Try "man bootparam" or see the documentation of
1353 your boot loader (lilo or loadlin) about how to pass options to the
1354 kernel at boot time.)
1356 If unsure, say "off".
1361 Select this if you have a 32-bit processor and between 1 and 4
1362 gigabytes of physical RAM.
1369 Select this if you have a 32-bit processor and more than 4
1370 gigabytes of physical RAM.
1375 prompt "Memory split" if EXPERT
1379 Select the desired split between kernel and user memory.
1381 If the address range available to the kernel is less than the
1382 physical memory installed, the remaining memory will be available
1383 as "high memory". Accessing high memory is a little more costly
1384 than low memory, as it needs to be mapped into the kernel first.
1385 Note that increasing the kernel address space limits the range
1386 available to user programs, making the address space there
1387 tighter. Selecting anything other than the default 3G/1G split
1388 will also likely make your kernel incompatible with binary-only
1391 If you are not absolutely sure what you are doing, leave this
1395 bool "3G/1G user/kernel split"
1396 config VMSPLIT_3G_OPT
1398 bool "3G/1G user/kernel split (for full 1G low memory)"
1400 bool "2G/2G user/kernel split"
1401 config VMSPLIT_2G_OPT
1403 bool "2G/2G user/kernel split (for full 2G low memory)"
1405 bool "1G/3G user/kernel split"
1410 default 0xB0000000 if VMSPLIT_3G_OPT
1411 default 0x80000000 if VMSPLIT_2G
1412 default 0x78000000 if VMSPLIT_2G_OPT
1413 default 0x40000000 if VMSPLIT_1G
1419 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1422 bool "PAE (Physical Address Extension) Support"
1423 depends on X86_32 && !HIGHMEM4G
1426 PAE is required for NX support, and furthermore enables
1427 larger swapspace support for non-overcommit purposes. It
1428 has the cost of more pagetable lookup overhead, and also
1429 consumes more pagetable space per process.
1432 bool "Enable 5-level page tables support"
1435 5-level paging enables access to larger address space:
1436 upto 128 PiB of virtual address space and 4 PiB of
1437 physical address space.
1439 It will be supported by future Intel CPUs.
1441 Note: a kernel with this option enabled can only be booted
1442 on machines that support the feature.
1444 See Documentation/x86/x86_64/5level-paging.txt for more
1449 config ARCH_PHYS_ADDR_T_64BIT
1451 depends on X86_64 || X86_PAE
1453 config ARCH_DMA_ADDR_T_64BIT
1455 depends on X86_64 || HIGHMEM64G
1457 config X86_DIRECT_GBPAGES
1459 depends on X86_64 && !DEBUG_PAGEALLOC
1461 Certain kernel features effectively disable kernel
1462 linear 1 GB mappings (even if the CPU otherwise
1463 supports them), so don't confuse the user by printing
1464 that we have them enabled.
1466 config ARCH_HAS_MEM_ENCRYPT
1469 config AMD_MEM_ENCRYPT
1470 bool "AMD Secure Memory Encryption (SME) support"
1471 depends on X86_64 && CPU_SUP_AMD
1473 Say yes to enable support for the encryption of system memory.
1474 This requires an AMD processor that supports Secure Memory
1477 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1478 bool "Activate AMD Secure Memory Encryption (SME) by default"
1480 depends on AMD_MEM_ENCRYPT
1482 Say yes to have system memory encrypted by default if running on
1483 an AMD processor that supports Secure Memory Encryption (SME).
1485 If set to Y, then the encryption of system memory can be
1486 deactivated with the mem_encrypt=off command line option.
1488 If set to N, then the encryption of system memory can be
1489 activated with the mem_encrypt=on command line option.
1491 config ARCH_USE_MEMREMAP_PROT
1493 depends on AMD_MEM_ENCRYPT
1495 # Common NUMA Features
1497 bool "Numa Memory Allocation and Scheduler Support"
1499 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1500 default y if X86_BIGSMP
1502 Enable NUMA (Non Uniform Memory Access) support.
1504 The kernel will try to allocate memory used by a CPU on the
1505 local memory controller of the CPU and add some more
1506 NUMA awareness to the kernel.
1508 For 64-bit this is recommended if the system is Intel Core i7
1509 (or later), AMD Opteron, or EM64T NUMA.
1511 For 32-bit this is only needed if you boot a 32-bit
1512 kernel on a 64-bit NUMA platform.
1514 Otherwise, you should say N.
1518 prompt "Old style AMD Opteron NUMA detection"
1519 depends on X86_64 && NUMA && PCI
1521 Enable AMD NUMA node topology detection. You should say Y here if
1522 you have a multi processor AMD system. This uses an old method to
1523 read the NUMA configuration directly from the builtin Northbridge
1524 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1525 which also takes priority if both are compiled in.
1527 config X86_64_ACPI_NUMA
1529 prompt "ACPI NUMA detection"
1530 depends on X86_64 && NUMA && ACPI && PCI
1533 Enable ACPI SRAT based node topology detection.
1535 # Some NUMA nodes have memory ranges that span
1536 # other nodes. Even though a pfn is valid and
1537 # between a node's start and end pfns, it may not
1538 # reside on that node. See memmap_init_zone()
1540 config NODES_SPAN_OTHER_NODES
1542 depends on X86_64_ACPI_NUMA
1545 bool "NUMA emulation"
1548 Enable NUMA emulation. A flat machine will be split
1549 into virtual nodes when booted with "numa=fake=N", where N is the
1550 number of nodes. This is only useful for debugging.
1553 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1555 default "10" if MAXSMP
1556 default "6" if X86_64
1558 depends on NEED_MULTIPLE_NODES
1560 Specify the maximum number of NUMA Nodes available on the target
1561 system. Increases memory reserved to accommodate various tables.
1563 config ARCH_HAVE_MEMORY_PRESENT
1565 depends on X86_32 && DISCONTIGMEM
1567 config NEED_NODE_MEMMAP_SIZE
1569 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1571 config ARCH_FLATMEM_ENABLE
1573 depends on X86_32 && !NUMA
1575 config ARCH_DISCONTIGMEM_ENABLE
1577 depends on NUMA && X86_32
1579 config ARCH_DISCONTIGMEM_DEFAULT
1581 depends on NUMA && X86_32
1583 config ARCH_SPARSEMEM_ENABLE
1585 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1586 select SPARSEMEM_STATIC if X86_32
1587 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1589 config ARCH_SPARSEMEM_DEFAULT
1593 config ARCH_SELECT_MEMORY_MODEL
1595 depends on ARCH_SPARSEMEM_ENABLE
1597 config ARCH_MEMORY_PROBE
1598 bool "Enable sysfs memory/probe interface"
1599 depends on X86_64 && MEMORY_HOTPLUG
1601 This option enables a sysfs memory/probe interface for testing.
1602 See Documentation/memory-hotplug.txt for more information.
1603 If you are unsure how to answer this question, answer N.
1605 config ARCH_PROC_KCORE_TEXT
1607 depends on X86_64 && PROC_KCORE
1609 config ILLEGAL_POINTER_VALUE
1612 default 0xdead000000000000 if X86_64
1616 config X86_PMEM_LEGACY_DEVICE
1619 config X86_PMEM_LEGACY
1620 tristate "Support non-standard NVDIMMs and ADR protected memory"
1621 depends on PHYS_ADDR_T_64BIT
1623 select X86_PMEM_LEGACY_DEVICE
1626 Treat memory marked using the non-standard e820 type of 12 as used
1627 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1628 The kernel will offer these regions to the 'pmem' driver so
1629 they can be used for persistent storage.
1634 bool "Allocate 3rd-level pagetables from highmem"
1637 The VM uses one page table entry for each page of physical memory.
1638 For systems with a lot of RAM, this can be wasteful of precious
1639 low memory. Setting this option will put user-space page table
1640 entries in high memory.
1642 config X86_CHECK_BIOS_CORRUPTION
1643 bool "Check for low memory corruption"
1645 Periodically check for memory corruption in low memory, which
1646 is suspected to be caused by BIOS. Even when enabled in the
1647 configuration, it is disabled at runtime. Enable it by
1648 setting "memory_corruption_check=1" on the kernel command
1649 line. By default it scans the low 64k of memory every 60
1650 seconds; see the memory_corruption_check_size and
1651 memory_corruption_check_period parameters in
1652 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1654 When enabled with the default parameters, this option has
1655 almost no overhead, as it reserves a relatively small amount
1656 of memory and scans it infrequently. It both detects corruption
1657 and prevents it from affecting the running system.
1659 It is, however, intended as a diagnostic tool; if repeatable
1660 BIOS-originated corruption always affects the same memory,
1661 you can use memmap= to prevent the kernel from using that
1664 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1665 bool "Set the default setting of memory_corruption_check"
1666 depends on X86_CHECK_BIOS_CORRUPTION
1669 Set whether the default state of memory_corruption_check is
1672 config X86_RESERVE_LOW
1673 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1677 Specify the amount of low memory to reserve for the BIOS.
1679 The first page contains BIOS data structures that the kernel
1680 must not use, so that page must always be reserved.
1682 By default we reserve the first 64K of physical RAM, as a
1683 number of BIOSes are known to corrupt that memory range
1684 during events such as suspend/resume or monitor cable
1685 insertion, so it must not be used by the kernel.
1687 You can set this to 4 if you are absolutely sure that you
1688 trust the BIOS to get all its memory reservations and usages
1689 right. If you know your BIOS have problems beyond the
1690 default 64K area, you can set this to 640 to avoid using the
1691 entire low memory range.
1693 If you have doubts about the BIOS (e.g. suspend/resume does
1694 not work or there's kernel crashes after certain hardware
1695 hotplug events) then you might want to enable
1696 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1697 typical corruption patterns.
1699 Leave this to the default value of 64 if you are unsure.
1701 config MATH_EMULATION
1703 depends on MODIFY_LDT_SYSCALL
1704 prompt "Math emulation" if X86_32
1706 Linux can emulate a math coprocessor (used for floating point
1707 operations) if you don't have one. 486DX and Pentium processors have
1708 a math coprocessor built in, 486SX and 386 do not, unless you added
1709 a 487DX or 387, respectively. (The messages during boot time can
1710 give you some hints here ["man dmesg"].) Everyone needs either a
1711 coprocessor or this emulation.
1713 If you don't have a math coprocessor, you need to say Y here; if you
1714 say Y here even though you have a coprocessor, the coprocessor will
1715 be used nevertheless. (This behavior can be changed with the kernel
1716 command line option "no387", which comes handy if your coprocessor
1717 is broken. Try "man bootparam" or see the documentation of your boot
1718 loader (lilo or loadlin) about how to pass options to the kernel at
1719 boot time.) This means that it is a good idea to say Y here if you
1720 intend to use this kernel on different machines.
1722 More information about the internals of the Linux math coprocessor
1723 emulation can be found in <file:arch/x86/math-emu/README>.
1725 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1726 kernel, it won't hurt.
1730 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1732 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1733 the Memory Type Range Registers (MTRRs) may be used to control
1734 processor access to memory ranges. This is most useful if you have
1735 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1736 allows bus write transfers to be combined into a larger transfer
1737 before bursting over the PCI/AGP bus. This can increase performance
1738 of image write operations 2.5 times or more. Saying Y here creates a
1739 /proc/mtrr file which may be used to manipulate your processor's
1740 MTRRs. Typically the X server should use this.
1742 This code has a reasonably generic interface so that similar
1743 control registers on other processors can be easily supported
1746 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1747 Registers (ARRs) which provide a similar functionality to MTRRs. For
1748 these, the ARRs are used to emulate the MTRRs.
1749 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1750 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1751 write-combining. All of these processors are supported by this code
1752 and it makes sense to say Y here if you have one of them.
1754 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1755 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1756 can lead to all sorts of problems, so it's good to say Y here.
1758 You can safely say Y even if your machine doesn't have MTRRs, you'll
1759 just add about 9 KB to your kernel.
1761 See <file:Documentation/x86/mtrr.txt> for more information.
1763 config MTRR_SANITIZER
1765 prompt "MTRR cleanup support"
1768 Convert MTRR layout from continuous to discrete, so X drivers can
1769 add writeback entries.
1771 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1772 The largest mtrr entry size for a continuous block can be set with
1777 config MTRR_SANITIZER_ENABLE_DEFAULT
1778 int "MTRR cleanup enable value (0-1)"
1781 depends on MTRR_SANITIZER
1783 Enable mtrr cleanup default value
1785 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1786 int "MTRR cleanup spare reg num (0-7)"
1789 depends on MTRR_SANITIZER
1791 mtrr cleanup spare entries default, it can be changed via
1792 mtrr_spare_reg_nr=N on the kernel command line.
1796 prompt "x86 PAT support" if EXPERT
1799 Use PAT attributes to setup page level cache control.
1801 PATs are the modern equivalents of MTRRs and are much more
1802 flexible than MTRRs.
1804 Say N here if you see bootup problems (boot crash, boot hang,
1805 spontaneous reboots) or a non-working video driver.
1809 config ARCH_USES_PG_UNCACHED
1815 prompt "x86 architectural random number generator" if EXPERT
1817 Enable the x86 architectural RDRAND instruction
1818 (Intel Bull Mountain technology) to generate random numbers.
1819 If supported, this is a high bandwidth, cryptographically
1820 secure hardware random number generator.
1824 prompt "Supervisor Mode Access Prevention" if EXPERT
1826 Supervisor Mode Access Prevention (SMAP) is a security
1827 feature in newer Intel processors. There is a small
1828 performance cost if this enabled and turned on; there is
1829 also a small increase in the kernel size if this is enabled.
1833 config X86_INTEL_UMIP
1835 depends on CPU_SUP_INTEL
1836 prompt "Intel User Mode Instruction Prevention" if EXPERT
1838 The User Mode Instruction Prevention (UMIP) is a security
1839 feature in newer Intel processors. If enabled, a general
1840 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1841 or STR instructions are executed in user mode. These instructions
1842 unnecessarily expose information about the hardware state.
1844 The vast majority of applications do not use these instructions.
1845 For the very few that do, software emulation is provided in
1846 specific cases in protected and virtual-8086 modes. Emulated
1849 config X86_INTEL_MPX
1850 prompt "Intel MPX (Memory Protection Extensions)"
1852 # Note: only available in 64-bit mode due to VMA flags shortage
1853 depends on CPU_SUP_INTEL && X86_64
1854 select ARCH_USES_HIGH_VMA_FLAGS
1856 MPX provides hardware features that can be used in
1857 conjunction with compiler-instrumented code to check
1858 memory references. It is designed to detect buffer
1859 overflow or underflow bugs.
1861 This option enables running applications which are
1862 instrumented or otherwise use MPX. It does not use MPX
1863 itself inside the kernel or to protect the kernel
1864 against bad memory references.
1866 Enabling this option will make the kernel larger:
1867 ~8k of kernel text and 36 bytes of data on a 64-bit
1868 defconfig. It adds a long to the 'mm_struct' which
1869 will increase the kernel memory overhead of each
1870 process and adds some branches to paths used during
1871 exec() and munmap().
1873 For details, see Documentation/x86/intel_mpx.txt
1877 config X86_INTEL_MEMORY_PROTECTION_KEYS
1878 prompt "Intel Memory Protection Keys"
1880 # Note: only available in 64-bit mode
1881 depends on CPU_SUP_INTEL && X86_64
1882 select ARCH_USES_HIGH_VMA_FLAGS
1883 select ARCH_HAS_PKEYS
1885 Memory Protection Keys provides a mechanism for enforcing
1886 page-based protections, but without requiring modification of the
1887 page tables when an application changes protection domains.
1889 For details, see Documentation/x86/protection-keys.txt
1894 bool "EFI runtime service support"
1897 select EFI_RUNTIME_WRAPPERS
1899 This enables the kernel to use EFI runtime services that are
1900 available (such as the EFI variable services).
1902 This option is only useful on systems that have EFI firmware.
1903 In addition, you should use the latest ELILO loader available
1904 at <http://elilo.sourceforge.net> in order to take advantage
1905 of EFI runtime services. However, even with this option, the
1906 resultant kernel should continue to boot on existing non-EFI
1910 bool "EFI stub support"
1911 depends on EFI && !X86_USE_3DNOW
1914 This kernel feature allows a bzImage to be loaded directly
1915 by EFI firmware without the use of a bootloader.
1917 See Documentation/efi-stub.txt for more information.
1920 bool "EFI mixed-mode support"
1921 depends on EFI_STUB && X86_64
1923 Enabling this feature allows a 64-bit kernel to be booted
1924 on a 32-bit firmware, provided that your CPU supports 64-bit
1927 Note that it is not possible to boot a mixed-mode enabled
1928 kernel via the EFI boot stub - a bootloader that supports
1929 the EFI handover protocol must be used.
1935 prompt "Enable seccomp to safely compute untrusted bytecode"
1937 This kernel feature is useful for number crunching applications
1938 that may need to compute untrusted bytecode during their
1939 execution. By using pipes or other transports made available to
1940 the process as file descriptors supporting the read/write
1941 syscalls, it's possible to isolate those applications in
1942 their own address space using seccomp. Once seccomp is
1943 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1944 and the task is only allowed to execute a few safe syscalls
1945 defined by each seccomp mode.
1947 If unsure, say Y. Only embedded should say N here.
1949 source kernel/Kconfig.hz
1952 bool "kexec system call"
1955 kexec is a system call that implements the ability to shutdown your
1956 current kernel, and to start another kernel. It is like a reboot
1957 but it is independent of the system firmware. And like a reboot
1958 you can start any kernel with it, not just Linux.
1960 The name comes from the similarity to the exec system call.
1962 It is an ongoing process to be certain the hardware in a machine
1963 is properly shutdown, so do not be surprised if this code does not
1964 initially work for you. As of this writing the exact hardware
1965 interface is strongly in flux, so no good recommendation can be
1969 bool "kexec file based system call"
1974 depends on CRYPTO_SHA256=y
1976 This is new version of kexec system call. This system call is
1977 file based and takes file descriptors as system call argument
1978 for kernel and initramfs as opposed to list of segments as
1979 accepted by previous system call.
1981 config KEXEC_VERIFY_SIG
1982 bool "Verify kernel signature during kexec_file_load() syscall"
1983 depends on KEXEC_FILE
1985 This option makes kernel signature verification mandatory for
1986 the kexec_file_load() syscall.
1988 In addition to that option, you need to enable signature
1989 verification for the corresponding kernel image type being
1990 loaded in order for this to work.
1992 config KEXEC_BZIMAGE_VERIFY_SIG
1993 bool "Enable bzImage signature verification support"
1994 depends on KEXEC_VERIFY_SIG
1995 depends on SIGNED_PE_FILE_VERIFICATION
1996 select SYSTEM_TRUSTED_KEYRING
1998 Enable bzImage signature verification support.
2001 bool "kernel crash dumps"
2002 depends on X86_64 || (X86_32 && HIGHMEM)
2004 Generate crash dump after being started by kexec.
2005 This should be normally only set in special crash dump kernels
2006 which are loaded in the main kernel with kexec-tools into
2007 a specially reserved region and then later executed after
2008 a crash by kdump/kexec. The crash dump kernel must be compiled
2009 to a memory address not used by the main kernel or BIOS using
2010 PHYSICAL_START, or it must be built as a relocatable image
2011 (CONFIG_RELOCATABLE=y).
2012 For more details see Documentation/kdump/kdump.txt
2016 depends on KEXEC && HIBERNATION
2018 Jump between original kernel and kexeced kernel and invoke
2019 code in physical address mode via KEXEC
2021 config PHYSICAL_START
2022 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2025 This gives the physical address where the kernel is loaded.
2027 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2028 bzImage will decompress itself to above physical address and
2029 run from there. Otherwise, bzImage will run from the address where
2030 it has been loaded by the boot loader and will ignore above physical
2033 In normal kdump cases one does not have to set/change this option
2034 as now bzImage can be compiled as a completely relocatable image
2035 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2036 address. This option is mainly useful for the folks who don't want
2037 to use a bzImage for capturing the crash dump and want to use a
2038 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2039 to be specifically compiled to run from a specific memory area
2040 (normally a reserved region) and this option comes handy.
2042 So if you are using bzImage for capturing the crash dump,
2043 leave the value here unchanged to 0x1000000 and set
2044 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2045 for capturing the crash dump change this value to start of
2046 the reserved region. In other words, it can be set based on
2047 the "X" value as specified in the "crashkernel=YM@XM"
2048 command line boot parameter passed to the panic-ed
2049 kernel. Please take a look at Documentation/kdump/kdump.txt
2050 for more details about crash dumps.
2052 Usage of bzImage for capturing the crash dump is recommended as
2053 one does not have to build two kernels. Same kernel can be used
2054 as production kernel and capture kernel. Above option should have
2055 gone away after relocatable bzImage support is introduced. But it
2056 is present because there are users out there who continue to use
2057 vmlinux for dump capture. This option should go away down the
2060 Don't change this unless you know what you are doing.
2063 bool "Build a relocatable kernel"
2066 This builds a kernel image that retains relocation information
2067 so it can be loaded someplace besides the default 1MB.
2068 The relocations tend to make the kernel binary about 10% larger,
2069 but are discarded at runtime.
2071 One use is for the kexec on panic case where the recovery kernel
2072 must live at a different physical address than the primary
2075 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2076 it has been loaded at and the compile time physical address
2077 (CONFIG_PHYSICAL_START) is used as the minimum location.
2079 config RANDOMIZE_BASE
2080 bool "Randomize the address of the kernel image (KASLR)"
2081 depends on RELOCATABLE
2084 In support of Kernel Address Space Layout Randomization (KASLR),
2085 this randomizes the physical address at which the kernel image
2086 is decompressed and the virtual address where the kernel
2087 image is mapped, as a security feature that deters exploit
2088 attempts relying on knowledge of the location of kernel
2091 On 64-bit, the kernel physical and virtual addresses are
2092 randomized separately. The physical address will be anywhere
2093 between 16MB and the top of physical memory (up to 64TB). The
2094 virtual address will be randomized from 16MB up to 1GB (9 bits
2095 of entropy). Note that this also reduces the memory space
2096 available to kernel modules from 1.5GB to 1GB.
2098 On 32-bit, the kernel physical and virtual addresses are
2099 randomized together. They will be randomized from 16MB up to
2100 512MB (8 bits of entropy).
2102 Entropy is generated using the RDRAND instruction if it is
2103 supported. If RDTSC is supported, its value is mixed into
2104 the entropy pool as well. If neither RDRAND nor RDTSC are
2105 supported, then entropy is read from the i8254 timer. The
2106 usable entropy is limited by the kernel being built using
2107 2GB addressing, and that PHYSICAL_ALIGN must be at a
2108 minimum of 2MB. As a result, only 10 bits of entropy are
2109 theoretically possible, but the implementations are further
2110 limited due to memory layouts.
2114 # Relocation on x86 needs some additional build support
2115 config X86_NEED_RELOCS
2117 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2119 config PHYSICAL_ALIGN
2120 hex "Alignment value to which kernel should be aligned"
2122 range 0x2000 0x1000000 if X86_32
2123 range 0x200000 0x1000000 if X86_64
2125 This value puts the alignment restrictions on physical address
2126 where kernel is loaded and run from. Kernel is compiled for an
2127 address which meets above alignment restriction.
2129 If bootloader loads the kernel at a non-aligned address and
2130 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2131 address aligned to above value and run from there.
2133 If bootloader loads the kernel at a non-aligned address and
2134 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2135 load address and decompress itself to the address it has been
2136 compiled for and run from there. The address for which kernel is
2137 compiled already meets above alignment restrictions. Hence the
2138 end result is that kernel runs from a physical address meeting
2139 above alignment restrictions.
2141 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2142 this value must be a multiple of 0x200000.
2144 Don't change this unless you know what you are doing.
2146 config RANDOMIZE_MEMORY
2147 bool "Randomize the kernel memory sections"
2149 depends on RANDOMIZE_BASE
2150 default RANDOMIZE_BASE
2152 Randomizes the base virtual address of kernel memory sections
2153 (physical memory mapping, vmalloc & vmemmap). This security feature
2154 makes exploits relying on predictable memory locations less reliable.
2156 The order of allocations remains unchanged. Entropy is generated in
2157 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2158 configuration have in average 30,000 different possible virtual
2159 addresses for each memory section.
2163 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2164 hex "Physical memory mapping padding" if EXPERT
2165 depends on RANDOMIZE_MEMORY
2166 default "0xa" if MEMORY_HOTPLUG
2168 range 0x1 0x40 if MEMORY_HOTPLUG
2171 Define the padding in terabytes added to the existing physical
2172 memory size during kernel memory randomization. It is useful
2173 for memory hotplug support but reduces the entropy available for
2174 address randomization.
2176 If unsure, leave at the default value.
2179 bool "Support for hot-pluggable CPUs"
2182 Say Y here to allow turning CPUs off and on. CPUs can be
2183 controlled through /sys/devices/system/cpu.
2184 ( Note: power management support will enable this option
2185 automatically on SMP systems. )
2186 Say N if you want to disable CPU hotplug.
2188 config BOOTPARAM_HOTPLUG_CPU0
2189 bool "Set default setting of cpu0_hotpluggable"
2191 depends on HOTPLUG_CPU
2193 Set whether default state of cpu0_hotpluggable is on or off.
2195 Say Y here to enable CPU0 hotplug by default. If this switch
2196 is turned on, there is no need to give cpu0_hotplug kernel
2197 parameter and the CPU0 hotplug feature is enabled by default.
2199 Please note: there are two known CPU0 dependencies if you want
2200 to enable the CPU0 hotplug feature either by this switch or by
2201 cpu0_hotplug kernel parameter.
2203 First, resume from hibernate or suspend always starts from CPU0.
2204 So hibernate and suspend are prevented if CPU0 is offline.
2206 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2207 offline if any interrupt can not migrate out of CPU0. There may
2208 be other CPU0 dependencies.
2210 Please make sure the dependencies are under your control before
2211 you enable this feature.
2213 Say N if you don't want to enable CPU0 hotplug feature by default.
2214 You still can enable the CPU0 hotplug feature at boot by kernel
2215 parameter cpu0_hotplug.
2217 config DEBUG_HOTPLUG_CPU0
2219 prompt "Debug CPU0 hotplug"
2220 depends on HOTPLUG_CPU
2222 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2223 soon as possible and boots up userspace with CPU0 offlined. User
2224 can online CPU0 back after boot time.
2226 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2227 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2228 compilation or giving cpu0_hotplug kernel parameter at boot.
2234 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2235 depends on COMPAT_32
2237 Certain buggy versions of glibc will crash if they are
2238 presented with a 32-bit vDSO that is not mapped at the address
2239 indicated in its segment table.
2241 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2242 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2243 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2244 the only released version with the bug, but OpenSUSE 9
2245 contains a buggy "glibc 2.3.2".
2247 The symptom of the bug is that everything crashes on startup, saying:
2248 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2250 Saying Y here changes the default value of the vdso32 boot
2251 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2252 This works around the glibc bug but hurts performance.
2254 If unsure, say N: if you are compiling your own kernel, you
2255 are unlikely to be using a buggy version of glibc.
2258 prompt "vsyscall table for legacy applications"
2260 default LEGACY_VSYSCALL_EMULATE
2262 Legacy user code that does not know how to find the vDSO expects
2263 to be able to issue three syscalls by calling fixed addresses in
2264 kernel space. Since this location is not randomized with ASLR,
2265 it can be used to assist security vulnerability exploitation.
2267 This setting can be changed at boot time via the kernel command
2268 line parameter vsyscall=[native|emulate|none].
2270 On a system with recent enough glibc (2.14 or newer) and no
2271 static binaries, you can say None without a performance penalty
2272 to improve security.
2274 If unsure, select "Emulate".
2276 config LEGACY_VSYSCALL_NATIVE
2279 Actual executable code is located in the fixed vsyscall
2280 address mapping, implementing time() efficiently. Since
2281 this makes the mapping executable, it can be used during
2282 security vulnerability exploitation (traditionally as
2283 ROP gadgets). This configuration is not recommended.
2285 config LEGACY_VSYSCALL_EMULATE
2288 The kernel traps and emulates calls into the fixed
2289 vsyscall address mapping. This makes the mapping
2290 non-executable, but it still contains known contents,
2291 which could be used in certain rare security vulnerability
2292 exploits. This configuration is recommended when userspace
2293 still uses the vsyscall area.
2295 config LEGACY_VSYSCALL_NONE
2298 There will be no vsyscall mapping at all. This will
2299 eliminate any risk of ASLR bypass due to the vsyscall
2300 fixed address mapping. Attempts to use the vsyscalls
2301 will be reported to dmesg, so that either old or
2302 malicious userspace programs can be identified.
2307 bool "Built-in kernel command line"
2309 Allow for specifying boot arguments to the kernel at
2310 build time. On some systems (e.g. embedded ones), it is
2311 necessary or convenient to provide some or all of the
2312 kernel boot arguments with the kernel itself (that is,
2313 to not rely on the boot loader to provide them.)
2315 To compile command line arguments into the kernel,
2316 set this option to 'Y', then fill in the
2317 boot arguments in CONFIG_CMDLINE.
2319 Systems with fully functional boot loaders (i.e. non-embedded)
2320 should leave this option set to 'N'.
2323 string "Built-in kernel command string"
2324 depends on CMDLINE_BOOL
2327 Enter arguments here that should be compiled into the kernel
2328 image and used at boot time. If the boot loader provides a
2329 command line at boot time, it is appended to this string to
2330 form the full kernel command line, when the system boots.
2332 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2333 change this behavior.
2335 In most cases, the command line (whether built-in or provided
2336 by the boot loader) should specify the device for the root
2339 config CMDLINE_OVERRIDE
2340 bool "Built-in command line overrides boot loader arguments"
2341 depends on CMDLINE_BOOL
2343 Set this option to 'Y' to have the kernel ignore the boot loader
2344 command line, and use ONLY the built-in command line.
2346 This is used to work around broken boot loaders. This should
2347 be set to 'N' under normal conditions.
2349 config MODIFY_LDT_SYSCALL
2350 bool "Enable the LDT (local descriptor table)" if EXPERT
2353 Linux can allow user programs to install a per-process x86
2354 Local Descriptor Table (LDT) using the modify_ldt(2) system
2355 call. This is required to run 16-bit or segmented code such as
2356 DOSEMU or some Wine programs. It is also used by some very old
2357 threading libraries.
2359 Enabling this feature adds a small amount of overhead to
2360 context switches and increases the low-level kernel attack
2361 surface. Disabling it removes the modify_ldt(2) system call.
2363 Saying 'N' here may make sense for embedded or server kernels.
2365 source "kernel/livepatch/Kconfig"
2369 config ARCH_HAS_ADD_PAGES
2371 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2373 config ARCH_ENABLE_MEMORY_HOTPLUG
2375 depends on X86_64 || (X86_32 && HIGHMEM)
2377 config ARCH_ENABLE_MEMORY_HOTREMOVE
2379 depends on MEMORY_HOTPLUG
2381 config USE_PERCPU_NUMA_NODE_ID
2385 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2387 depends on X86_64 || X86_PAE
2389 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2391 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2393 config ARCH_ENABLE_THP_MIGRATION
2395 depends on X86_64 && TRANSPARENT_HUGEPAGE
2397 menu "Power management and ACPI options"
2399 config ARCH_HIBERNATION_HEADER
2401 depends on X86_64 && HIBERNATION
2403 source "kernel/power/Kconfig"
2405 source "drivers/acpi/Kconfig"
2407 source "drivers/sfi/Kconfig"
2414 tristate "APM (Advanced Power Management) BIOS support"
2415 depends on X86_32 && PM_SLEEP
2417 APM is a BIOS specification for saving power using several different
2418 techniques. This is mostly useful for battery powered laptops with
2419 APM compliant BIOSes. If you say Y here, the system time will be
2420 reset after a RESUME operation, the /proc/apm device will provide
2421 battery status information, and user-space programs will receive
2422 notification of APM "events" (e.g. battery status change).
2424 If you select "Y" here, you can disable actual use of the APM
2425 BIOS by passing the "apm=off" option to the kernel at boot time.
2427 Note that the APM support is almost completely disabled for
2428 machines with more than one CPU.
2430 In order to use APM, you will need supporting software. For location
2431 and more information, read <file:Documentation/power/apm-acpi.txt>
2432 and the Battery Powered Linux mini-HOWTO, available from
2433 <http://www.tldp.org/docs.html#howto>.
2435 This driver does not spin down disk drives (see the hdparm(8)
2436 manpage ("man 8 hdparm") for that), and it doesn't turn off
2437 VESA-compliant "green" monitors.
2439 This driver does not support the TI 4000M TravelMate and the ACER
2440 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2441 desktop machines also don't have compliant BIOSes, and this driver
2442 may cause those machines to panic during the boot phase.
2444 Generally, if you don't have a battery in your machine, there isn't
2445 much point in using this driver and you should say N. If you get
2446 random kernel OOPSes or reboots that don't seem to be related to
2447 anything, try disabling/enabling this option (or disabling/enabling
2450 Some other things you should try when experiencing seemingly random,
2453 1) make sure that you have enough swap space and that it is
2455 2) pass the "no-hlt" option to the kernel
2456 3) switch on floating point emulation in the kernel and pass
2457 the "no387" option to the kernel
2458 4) pass the "floppy=nodma" option to the kernel
2459 5) pass the "mem=4M" option to the kernel (thereby disabling
2460 all but the first 4 MB of RAM)
2461 6) make sure that the CPU is not over clocked.
2462 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2463 8) disable the cache from your BIOS settings
2464 9) install a fan for the video card or exchange video RAM
2465 10) install a better fan for the CPU
2466 11) exchange RAM chips
2467 12) exchange the motherboard.
2469 To compile this driver as a module, choose M here: the
2470 module will be called apm.
2474 config APM_IGNORE_USER_SUSPEND
2475 bool "Ignore USER SUSPEND"
2477 This option will ignore USER SUSPEND requests. On machines with a
2478 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2479 series notebooks, it is necessary to say Y because of a BIOS bug.
2481 config APM_DO_ENABLE
2482 bool "Enable PM at boot time"
2484 Enable APM features at boot time. From page 36 of the APM BIOS
2485 specification: "When disabled, the APM BIOS does not automatically
2486 power manage devices, enter the Standby State, enter the Suspend
2487 State, or take power saving steps in response to CPU Idle calls."
2488 This driver will make CPU Idle calls when Linux is idle (unless this
2489 feature is turned off -- see "Do CPU IDLE calls", below). This
2490 should always save battery power, but more complicated APM features
2491 will be dependent on your BIOS implementation. You may need to turn
2492 this option off if your computer hangs at boot time when using APM
2493 support, or if it beeps continuously instead of suspending. Turn
2494 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2495 T400CDT. This is off by default since most machines do fine without
2500 bool "Make CPU Idle calls when idle"
2502 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2503 On some machines, this can activate improved power savings, such as
2504 a slowed CPU clock rate, when the machine is idle. These idle calls
2505 are made after the idle loop has run for some length of time (e.g.,
2506 333 mS). On some machines, this will cause a hang at boot time or
2507 whenever the CPU becomes idle. (On machines with more than one CPU,
2508 this option does nothing.)
2510 config APM_DISPLAY_BLANK
2511 bool "Enable console blanking using APM"
2513 Enable console blanking using the APM. Some laptops can use this to
2514 turn off the LCD backlight when the screen blanker of the Linux
2515 virtual console blanks the screen. Note that this is only used by
2516 the virtual console screen blanker, and won't turn off the backlight
2517 when using the X Window system. This also doesn't have anything to
2518 do with your VESA-compliant power-saving monitor. Further, this
2519 option doesn't work for all laptops -- it might not turn off your
2520 backlight at all, or it might print a lot of errors to the console,
2521 especially if you are using gpm.
2523 config APM_ALLOW_INTS
2524 bool "Allow interrupts during APM BIOS calls"
2526 Normally we disable external interrupts while we are making calls to
2527 the APM BIOS as a measure to lessen the effects of a badly behaving
2528 BIOS implementation. The BIOS should reenable interrupts if it
2529 needs to. Unfortunately, some BIOSes do not -- especially those in
2530 many of the newer IBM Thinkpads. If you experience hangs when you
2531 suspend, try setting this to Y. Otherwise, say N.
2535 source "drivers/cpufreq/Kconfig"
2537 source "drivers/cpuidle/Kconfig"
2539 source "drivers/idle/Kconfig"
2544 menu "Bus options (PCI etc.)"
2550 Find out whether you have a PCI motherboard. PCI is the name of a
2551 bus system, i.e. the way the CPU talks to the other stuff inside
2552 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2553 VESA. If you have PCI, say Y, otherwise N.
2556 prompt "PCI access mode"
2557 depends on X86_32 && PCI
2560 On PCI systems, the BIOS can be used to detect the PCI devices and
2561 determine their configuration. However, some old PCI motherboards
2562 have BIOS bugs and may crash if this is done. Also, some embedded
2563 PCI-based systems don't have any BIOS at all. Linux can also try to
2564 detect the PCI hardware directly without using the BIOS.
2566 With this option, you can specify how Linux should detect the
2567 PCI devices. If you choose "BIOS", the BIOS will be used,
2568 if you choose "Direct", the BIOS won't be used, and if you
2569 choose "MMConfig", then PCI Express MMCONFIG will be used.
2570 If you choose "Any", the kernel will try MMCONFIG, then the
2571 direct access method and falls back to the BIOS if that doesn't
2572 work. If unsure, go with the default, which is "Any".
2577 config PCI_GOMMCONFIG
2594 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2596 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2599 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2603 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2607 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2611 depends on PCI && XEN
2619 bool "Support mmconfig PCI config space access"
2620 depends on X86_64 && PCI && ACPI
2622 config PCI_CNB20LE_QUIRK
2623 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2626 Read the PCI windows out of the CNB20LE host bridge. This allows
2627 PCI hotplug to work on systems with the CNB20LE chipset which do
2630 There's no public spec for this chipset, and this functionality
2631 is known to be incomplete.
2633 You should say N unless you know you need this.
2635 source "drivers/pci/Kconfig"
2638 bool "ISA-style bus support on modern systems" if EXPERT
2641 Enables ISA-style drivers on modern systems. This is necessary to
2642 support PC/104 devices on X86_64 platforms.
2646 # x86_64 have no ISA slots, but can have ISA-style DMA.
2648 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2651 Enables ISA-style DMA support for devices requiring such controllers.
2659 Find out whether you have ISA slots on your motherboard. ISA is the
2660 name of a bus system, i.e. the way the CPU talks to the other stuff
2661 inside your box. Other bus systems are PCI, EISA, MicroChannel
2662 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2663 newer boards don't support it. If you have ISA, say Y, otherwise N.
2669 The Extended Industry Standard Architecture (EISA) bus was
2670 developed as an open alternative to the IBM MicroChannel bus.
2672 The EISA bus provided some of the features of the IBM MicroChannel
2673 bus while maintaining backward compatibility with cards made for
2674 the older ISA bus. The EISA bus saw limited use between 1988 and
2675 1995 when it was made obsolete by the PCI bus.
2677 Say Y here if you are building a kernel for an EISA-based machine.
2681 source "drivers/eisa/Kconfig"
2684 tristate "NatSemi SCx200 support"
2686 This provides basic support for National Semiconductor's
2687 (now AMD's) Geode processors. The driver probes for the
2688 PCI-IDs of several on-chip devices, so its a good dependency
2689 for other scx200_* drivers.
2691 If compiled as a module, the driver is named scx200.
2693 config SCx200HR_TIMER
2694 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2698 This driver provides a clocksource built upon the on-chip
2699 27MHz high-resolution timer. Its also a workaround for
2700 NSC Geode SC-1100's buggy TSC, which loses time when the
2701 processor goes idle (as is done by the scheduler). The
2702 other workaround is idle=poll boot option.
2705 bool "One Laptop Per Child support"
2712 Add support for detecting the unique features of the OLPC
2716 bool "OLPC XO-1 Power Management"
2717 depends on OLPC && MFD_CS5535 && PM_SLEEP
2720 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2723 bool "OLPC XO-1 Real Time Clock"
2724 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2726 Add support for the XO-1 real time clock, which can be used as a
2727 programmable wakeup source.
2730 bool "OLPC XO-1 SCI extras"
2731 depends on OLPC && OLPC_XO1_PM
2737 Add support for SCI-based features of the OLPC XO-1 laptop:
2738 - EC-driven system wakeups
2742 - AC adapter status updates
2743 - Battery status updates
2745 config OLPC_XO15_SCI
2746 bool "OLPC XO-1.5 SCI extras"
2747 depends on OLPC && ACPI
2750 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2751 - EC-driven system wakeups
2752 - AC adapter status updates
2753 - Battery status updates
2756 bool "PCEngines ALIX System Support (LED setup)"
2759 This option enables system support for the PCEngines ALIX.
2760 At present this just sets up LEDs for GPIO control on
2761 ALIX2/3/6 boards. However, other system specific setup should
2764 Note: You must still enable the drivers for GPIO and LED support
2765 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2767 Note: You have to set alix.force=1 for boards with Award BIOS.
2770 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2773 This option enables system support for the Soekris Engineering net5501.
2776 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2780 This option enables system support for the Traverse Technologies GEOS.
2783 bool "Technologic Systems TS-5500 platform support"
2785 select CHECK_SIGNATURE
2789 This option enables system support for the Technologic Systems TS-5500.
2795 depends on CPU_SUP_AMD && PCI
2797 source "drivers/pcmcia/Kconfig"
2800 tristate "RapidIO support"
2804 If enabled this option will include drivers and the core
2805 infrastructure code to support RapidIO interconnect devices.
2807 source "drivers/rapidio/Kconfig"
2810 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2812 Firmwares often provide initial graphics framebuffers so the BIOS,
2813 bootloader or kernel can show basic video-output during boot for
2814 user-guidance and debugging. Historically, x86 used the VESA BIOS
2815 Extensions and EFI-framebuffers for this, which are mostly limited
2817 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2818 framebuffers so the new generic system-framebuffer drivers can be
2819 used on x86. If the framebuffer is not compatible with the generic
2820 modes, it is adverticed as fallback platform framebuffer so legacy
2821 drivers like efifb, vesafb and uvesafb can pick it up.
2822 If this option is not selected, all system framebuffers are always
2823 marked as fallback platform framebuffers as usual.
2825 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2826 not be able to pick up generic system framebuffers if this option
2827 is selected. You are highly encouraged to enable simplefb as
2828 replacement if you select this option. simplefb can correctly deal
2829 with generic system framebuffers. But you should still keep vesafb
2830 and others enabled as fallback if a system framebuffer is
2831 incompatible with simplefb.
2838 menu "Executable file formats / Emulations"
2840 source "fs/Kconfig.binfmt"
2842 config IA32_EMULATION
2843 bool "IA32 Emulation"
2845 select ARCH_WANT_OLD_COMPAT_IPC
2847 select COMPAT_BINFMT_ELF
2848 select COMPAT_OLD_SIGACTION
2850 Include code to run legacy 32-bit programs under a
2851 64-bit kernel. You should likely turn this on, unless you're
2852 100% sure that you don't have any 32-bit programs left.
2855 tristate "IA32 a.out support"
2856 depends on IA32_EMULATION
2858 Support old a.out binaries in the 32bit emulation.
2861 bool "x32 ABI for 64-bit mode"
2864 Include code to run binaries for the x32 native 32-bit ABI
2865 for 64-bit processors. An x32 process gets access to the
2866 full 64-bit register file and wide data path while leaving
2867 pointers at 32 bits for smaller memory footprint.
2869 You will need a recent binutils (2.22 or later) with
2870 elf32_x86_64 support enabled to compile a kernel with this
2875 depends on IA32_EMULATION || X86_32
2877 select OLD_SIGSUSPEND3
2881 depends on IA32_EMULATION || X86_X32
2884 config COMPAT_FOR_U64_ALIGNMENT
2887 config SYSVIPC_COMPAT
2895 config HAVE_ATOMIC_IOMAP
2899 config X86_DEV_DMA_OPS
2901 depends on X86_64 || STA2X11
2903 config X86_DMA_REMAP
2907 config HAVE_GENERIC_GUP
2910 source "net/Kconfig"
2912 source "drivers/Kconfig"
2914 source "drivers/firmware/Kconfig"
2918 source "arch/x86/Kconfig.debug"
2920 source "security/Kconfig"
2922 source "crypto/Kconfig"
2924 source "arch/x86/kvm/Kconfig"
2926 source "lib/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob