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_PMEM_API if X86_64
58 # Causing hangs/crashes, see the commit that added this change for details.
59 select ARCH_HAS_REFCOUNT
60 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
61 select ARCH_HAS_SET_MEMORY
62 select ARCH_HAS_SG_CHAIN
63 select ARCH_HAS_STRICT_KERNEL_RWX
64 select ARCH_HAS_STRICT_MODULE_RWX
65 select ARCH_HAS_UBSAN_SANITIZE_ALL
66 select ARCH_HAS_ZONE_DEVICE if X86_64
67 select ARCH_HAVE_NMI_SAFE_CMPXCHG
68 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
69 select ARCH_MIGHT_HAVE_PC_PARPORT
70 select ARCH_MIGHT_HAVE_PC_SERIO
71 select ARCH_SUPPORTS_ATOMIC_RMW
72 select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
73 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
74 select ARCH_USE_BUILTIN_BSWAP
75 select ARCH_USE_QUEUED_RWLOCKS
76 select ARCH_USE_QUEUED_SPINLOCKS
77 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
78 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
79 select ARCH_WANTS_THP_SWAP if X86_64
80 select BUILDTIME_EXTABLE_SORT
82 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
83 select CLOCKSOURCE_WATCHDOG
84 select DCACHE_WORD_ACCESS
85 select EDAC_ATOMIC_SCRUB
87 select GENERIC_CLOCKEVENTS
88 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
89 select GENERIC_CLOCKEVENTS_MIN_ADJUST
90 select GENERIC_CMOS_UPDATE
91 select GENERIC_CPU_AUTOPROBE
92 select GENERIC_EARLY_IOREMAP
93 select GENERIC_FIND_FIRST_BIT
95 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
96 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
97 select GENERIC_IRQ_MIGRATION if SMP
98 select GENERIC_IRQ_PROBE
99 select GENERIC_IRQ_RESERVATION_MODE
100 select GENERIC_IRQ_SHOW
101 select GENERIC_PENDING_IRQ if SMP
102 select GENERIC_SMP_IDLE_THREAD
103 select GENERIC_STRNCPY_FROM_USER
104 select GENERIC_STRNLEN_USER
105 select GENERIC_TIME_VSYSCALL
106 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
107 select HAVE_ACPI_APEI if ACPI
108 select HAVE_ACPI_APEI_NMI if ACPI
109 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
110 select HAVE_ARCH_AUDITSYSCALL
111 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
112 select HAVE_ARCH_JUMP_LABEL
113 select HAVE_ARCH_KASAN if X86_64
114 select HAVE_ARCH_KGDB
115 select HAVE_ARCH_MMAP_RND_BITS if MMU
116 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
117 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
118 select HAVE_ARCH_SECCOMP_FILTER
119 select HAVE_ARCH_TRACEHOOK
120 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
121 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
122 select HAVE_ARCH_VMAP_STACK if X86_64
123 select HAVE_ARCH_WITHIN_STACK_FRAMES
124 select HAVE_CC_STACKPROTECTOR
125 select HAVE_CMPXCHG_DOUBLE
126 select HAVE_CMPXCHG_LOCAL
127 select HAVE_CONTEXT_TRACKING if X86_64
128 select HAVE_COPY_THREAD_TLS
129 select HAVE_C_RECORDMCOUNT
130 select HAVE_DEBUG_KMEMLEAK
131 select HAVE_DEBUG_STACKOVERFLOW
132 select HAVE_DMA_API_DEBUG
133 select HAVE_DMA_CONTIGUOUS
134 select HAVE_DYNAMIC_FTRACE
135 select HAVE_DYNAMIC_FTRACE_WITH_REGS
136 select HAVE_EBPF_JIT if X86_64
137 select HAVE_EFFICIENT_UNALIGNED_ACCESS
138 select HAVE_EXIT_THREAD
139 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
140 select HAVE_FTRACE_MCOUNT_RECORD
141 select HAVE_FUNCTION_GRAPH_TRACER
142 select HAVE_FUNCTION_TRACER
143 select HAVE_GCC_PLUGINS
144 select HAVE_HW_BREAKPOINT
146 select HAVE_IOREMAP_PROT
147 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
148 select HAVE_IRQ_TIME_ACCOUNTING
149 select HAVE_KERNEL_BZIP2
150 select HAVE_KERNEL_GZIP
151 select HAVE_KERNEL_LZ4
152 select HAVE_KERNEL_LZMA
153 select HAVE_KERNEL_LZO
154 select HAVE_KERNEL_XZ
156 select HAVE_KPROBES_ON_FTRACE
157 select HAVE_KRETPROBES
159 select HAVE_LIVEPATCH if X86_64
161 select HAVE_MEMBLOCK_NODE_MAP
162 select HAVE_MIXED_BREAKPOINTS_REGS
163 select HAVE_MOD_ARCH_SPECIFIC
166 select HAVE_OPTPROBES
167 select HAVE_PCSPKR_PLATFORM
168 select HAVE_PERF_EVENTS
169 select HAVE_PERF_EVENTS_NMI
170 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
171 select HAVE_PERF_REGS
172 select HAVE_PERF_USER_STACK_DUMP
173 select HAVE_RCU_TABLE_FREE
174 select HAVE_REGS_AND_STACK_ACCESS_API
175 select HAVE_RELIABLE_STACKTRACE if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
176 select HAVE_STACK_VALIDATION if X86_64
177 select HAVE_SYSCALL_TRACEPOINTS
178 select HAVE_UNSTABLE_SCHED_CLOCK
179 select HAVE_USER_RETURN_NOTIFIER
180 select IRQ_FORCED_THREADING
181 select PCI_LOCKLESS_CONFIG
184 select RTC_MC146818_LIB
187 select SYSCTL_EXCEPTION_TRACE
188 select THREAD_INFO_IN_TASK
189 select USER_STACKTRACE_SUPPORT
191 select X86_FEATURE_NAMES if PROC_FS
193 config INSTRUCTION_DECODER
195 depends on KPROBES || PERF_EVENTS || UPROBES
199 default "elf32-i386" if X86_32
200 default "elf64-x86-64" if X86_64
202 config ARCH_DEFCONFIG
204 default "arch/x86/configs/i386_defconfig" if X86_32
205 default "arch/x86/configs/x86_64_defconfig" if X86_64
207 config LOCKDEP_SUPPORT
210 config STACKTRACE_SUPPORT
216 config ARCH_MMAP_RND_BITS_MIN
220 config ARCH_MMAP_RND_BITS_MAX
224 config ARCH_MMAP_RND_COMPAT_BITS_MIN
227 config ARCH_MMAP_RND_COMPAT_BITS_MAX
233 config NEED_DMA_MAP_STATE
235 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
237 config NEED_SG_DMA_LENGTH
240 config GENERIC_ISA_DMA
242 depends on ISA_DMA_API
247 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
249 config GENERIC_BUG_RELATIVE_POINTERS
252 config GENERIC_HWEIGHT
255 config ARCH_MAY_HAVE_PC_FDC
257 depends on ISA_DMA_API
259 config RWSEM_XCHGADD_ALGORITHM
262 config GENERIC_CALIBRATE_DELAY
265 config ARCH_HAS_CPU_RELAX
268 config ARCH_HAS_CACHE_LINE_SIZE
271 config HAVE_SETUP_PER_CPU_AREA
274 config NEED_PER_CPU_EMBED_FIRST_CHUNK
277 config NEED_PER_CPU_PAGE_FIRST_CHUNK
280 config ARCH_HIBERNATION_POSSIBLE
283 config ARCH_SUSPEND_POSSIBLE
286 config ARCH_WANT_HUGE_PMD_SHARE
289 config ARCH_WANT_GENERAL_HUGETLB
298 config ARCH_SUPPORTS_OPTIMIZED_INLINING
301 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
304 config KASAN_SHADOW_OFFSET
307 default 0xdffffc0000000000
309 config HAVE_INTEL_TXT
311 depends on INTEL_IOMMU && ACPI
315 depends on X86_32 && SMP
319 depends on X86_64 && SMP
321 config X86_32_LAZY_GS
323 depends on X86_32 && !CC_STACKPROTECTOR
325 config ARCH_SUPPORTS_UPROBES
328 config FIX_EARLYCON_MEM
331 config PGTABLE_LEVELS
333 default 5 if X86_5LEVEL
338 source "init/Kconfig"
339 source "kernel/Kconfig.freezer"
341 menu "Processor type and features"
344 bool "DMA memory allocation support" if EXPERT
347 DMA memory allocation support allows devices with less than 32-bit
348 addressing to allocate within the first 16MB of address space.
349 Disable if no such devices will be used.
354 bool "Symmetric multi-processing support"
356 This enables support for systems with more than one CPU. If you have
357 a system with only one CPU, say N. If you have a system with more
360 If you say N here, the kernel will run on uni- and multiprocessor
361 machines, but will use only one CPU of a multiprocessor machine. If
362 you say Y here, the kernel will run on many, but not all,
363 uniprocessor machines. On a uniprocessor machine, the kernel
364 will run faster if you say N here.
366 Note that if you say Y here and choose architecture "586" or
367 "Pentium" under "Processor family", the kernel will not work on 486
368 architectures. Similarly, multiprocessor kernels for the "PPro"
369 architecture may not work on all Pentium based boards.
371 People using multiprocessor machines who say Y here should also say
372 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
373 Management" code will be disabled if you say Y here.
375 See also <file:Documentation/x86/i386/IO-APIC.txt>,
376 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
377 <http://www.tldp.org/docs.html#howto>.
379 If you don't know what to do here, say N.
381 config X86_FEATURE_NAMES
382 bool "Processor feature human-readable names" if EMBEDDED
385 This option compiles in a table of x86 feature bits and corresponding
386 names. This is required to support /proc/cpuinfo and a few kernel
387 messages. You can disable this to save space, at the expense of
388 making those few kernel messages show numeric feature bits instead.
392 config X86_FAST_FEATURE_TESTS
393 bool "Fast CPU feature tests" if EMBEDDED
396 Some fast-paths in the kernel depend on the capabilities of the CPU.
397 Say Y here for the kernel to patch in the appropriate code at runtime
398 based on the capabilities of the CPU. The infrastructure for patching
399 code at runtime takes up some additional space; space-constrained
400 embedded systems may wish to say N here to produce smaller, slightly
404 bool "Support x2apic"
405 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
407 This enables x2apic support on CPUs that have this feature.
409 This allows 32-bit apic IDs (so it can support very large systems),
410 and accesses the local apic via MSRs not via mmio.
412 If you don't know what to do here, say N.
415 bool "Enable MPS table" if ACPI || SFI
417 depends on X86_LOCAL_APIC
419 For old smp systems that do not have proper acpi support. Newer systems
420 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
423 bool "Support for big SMP systems with more than 8 CPUs"
424 depends on X86_32 && SMP
426 This option is needed for the systems that have more than 8 CPUs
430 depends on X86_GOLDFISH
433 bool "Intel Resource Director Technology support"
435 depends on X86 && CPU_SUP_INTEL
438 Select to enable resource allocation and monitoring which are
439 sub-features of Intel Resource Director Technology(RDT). More
440 information about RDT can be found in the Intel x86
441 Architecture Software Developer Manual.
446 config X86_EXTENDED_PLATFORM
447 bool "Support for extended (non-PC) x86 platforms"
450 If you disable this option then the kernel will only support
451 standard PC platforms. (which covers the vast majority of
454 If you enable this option then you'll be able to select support
455 for the following (non-PC) 32 bit x86 platforms:
456 Goldfish (Android emulator)
459 SGI 320/540 (Visual Workstation)
460 STA2X11-based (e.g. Northville)
461 Moorestown MID devices
463 If you have one of these systems, or if you want to build a
464 generic distribution kernel, say Y here - otherwise say N.
468 config X86_EXTENDED_PLATFORM
469 bool "Support for extended (non-PC) x86 platforms"
472 If you disable this option then the kernel will only support
473 standard PC platforms. (which covers the vast majority of
476 If you enable this option then you'll be able to select support
477 for the following (non-PC) 64 bit x86 platforms:
482 If you have one of these systems, or if you want to build a
483 generic distribution kernel, say Y here - otherwise say N.
485 # This is an alphabetically sorted list of 64 bit extended platforms
486 # Please maintain the alphabetic order if and when there are additions
488 bool "Numascale NumaChip"
490 depends on X86_EXTENDED_PLATFORM
493 depends on X86_X2APIC
494 depends on PCI_MMCONFIG
496 Adds support for Numascale NumaChip large-SMP systems. Needed to
497 enable more than ~168 cores.
498 If you don't have one of these, you should say N here.
502 select HYPERVISOR_GUEST
504 depends on X86_64 && PCI
505 depends on X86_EXTENDED_PLATFORM
508 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
509 supposed to run on these EM64T-based machines. Only choose this option
510 if you have one of these machines.
513 bool "SGI Ultraviolet"
515 depends on X86_EXTENDED_PLATFORM
518 depends on X86_X2APIC
521 This option is needed in order to support SGI Ultraviolet systems.
522 If you don't have one of these, you should say N here.
524 # Following is an alphabetically sorted list of 32 bit extended platforms
525 # Please maintain the alphabetic order if and when there are additions
528 bool "Goldfish (Virtual Platform)"
529 depends on X86_EXTENDED_PLATFORM
531 Enable support for the Goldfish virtual platform used primarily
532 for Android development. Unless you are building for the Android
533 Goldfish emulator say N here.
536 bool "CE4100 TV platform"
538 depends on PCI_GODIRECT
539 depends on X86_IO_APIC
541 depends on X86_EXTENDED_PLATFORM
542 select X86_REBOOTFIXUPS
544 select OF_EARLY_FLATTREE
546 Select for the Intel CE media processor (CE4100) SOC.
547 This option compiles in support for the CE4100 SOC for settop
548 boxes and media devices.
551 bool "Intel MID platform support"
552 depends on X86_EXTENDED_PLATFORM
553 depends on X86_PLATFORM_DEVICES
555 depends on X86_64 || (PCI_GOANY && X86_32)
556 depends on X86_IO_APIC
562 select MFD_INTEL_MSIC
564 Select to build a kernel capable of supporting Intel MID (Mobile
565 Internet Device) platform systems which do not have the PCI legacy
566 interfaces. If you are building for a PC class system say N here.
568 Intel MID platforms are based on an Intel processor and chipset which
569 consume less power than most of the x86 derivatives.
571 config X86_INTEL_QUARK
572 bool "Intel Quark platform support"
574 depends on X86_EXTENDED_PLATFORM
575 depends on X86_PLATFORM_DEVICES
579 depends on X86_IO_APIC
584 Select to include support for Quark X1000 SoC.
585 Say Y here if you have a Quark based system such as the Arduino
586 compatible Intel Galileo.
588 config X86_INTEL_LPSS
589 bool "Intel Low Power Subsystem Support"
590 depends on X86 && ACPI
595 Select to build support for Intel Low Power Subsystem such as
596 found on Intel Lynxpoint PCH. Selecting this option enables
597 things like clock tree (common clock framework) and pincontrol
598 which are needed by the LPSS peripheral drivers.
600 config X86_AMD_PLATFORM_DEVICE
601 bool "AMD ACPI2Platform devices support"
606 Select to interpret AMD specific ACPI device to platform device
607 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
608 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
609 implemented under PINCTRL subsystem.
612 tristate "Intel SoC IOSF Sideband support for SoC platforms"
615 This option enables sideband register access support for Intel SoC
616 platforms. On these platforms the IOSF sideband is used in lieu of
617 MSR's for some register accesses, mostly but not limited to thermal
618 and power. Drivers may query the availability of this device to
619 determine if they need the sideband in order to work on these
620 platforms. The sideband is available on the following SoC products.
621 This list is not meant to be exclusive.
626 You should say Y if you are running a kernel on one of these SoC's.
628 config IOSF_MBI_DEBUG
629 bool "Enable IOSF sideband access through debugfs"
630 depends on IOSF_MBI && DEBUG_FS
632 Select this option to expose the IOSF sideband access registers (MCR,
633 MDR, MCRX) through debugfs to write and read register information from
634 different units on the SoC. This is most useful for obtaining device
635 state information for debug and analysis. As this is a general access
636 mechanism, users of this option would have specific knowledge of the
637 device they want to access.
639 If you don't require the option or are in doubt, say N.
642 bool "RDC R-321x SoC"
644 depends on X86_EXTENDED_PLATFORM
646 select X86_REBOOTFIXUPS
648 This option is needed for RDC R-321x system-on-chip, also known
650 If you don't have one of these chips, you should say N here.
652 config X86_32_NON_STANDARD
653 bool "Support non-standard 32-bit SMP architectures"
654 depends on X86_32 && SMP
655 depends on X86_EXTENDED_PLATFORM
657 This option compiles in the bigsmp and STA2X11 default
658 subarchitectures. It is intended for a generic binary
659 kernel. If you select them all, kernel will probe it one by
660 one and will fallback to default.
662 # Alphabetically sorted list of Non standard 32 bit platforms
664 config X86_SUPPORTS_MEMORY_FAILURE
666 # MCE code calls memory_failure():
668 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
669 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
670 depends on X86_64 || !SPARSEMEM
671 select ARCH_SUPPORTS_MEMORY_FAILURE
674 bool "STA2X11 Companion Chip Support"
675 depends on X86_32_NON_STANDARD && PCI
676 select X86_DEV_DMA_OPS
683 This adds support for boards based on the STA2X11 IO-Hub,
684 a.k.a. "ConneXt". The chip is used in place of the standard
685 PC chipset, so all "standard" peripherals are missing. If this
686 option is selected the kernel will still be able to boot on
687 standard PC machines.
690 tristate "Eurobraille/Iris poweroff module"
693 The Iris machines from EuroBraille do not have APM or ACPI support
694 to shut themselves down properly. A special I/O sequence is
695 needed to do so, which is what this module does at
698 This is only for Iris machines from EuroBraille.
702 config SCHED_OMIT_FRAME_POINTER
704 prompt "Single-depth WCHAN output"
707 Calculate simpler /proc/<PID>/wchan values. If this option
708 is disabled then wchan values will recurse back to the
709 caller function. This provides more accurate wchan values,
710 at the expense of slightly more scheduling overhead.
712 If in doubt, say "Y".
714 menuconfig HYPERVISOR_GUEST
715 bool "Linux guest support"
717 Say Y here to enable options for running Linux under various hyper-
718 visors. This option enables basic hypervisor detection and platform
721 If you say N, all options in this submenu will be skipped and
722 disabled, and Linux guest support won't be built in.
727 bool "Enable paravirtualization code"
729 This changes the kernel so it can modify itself when it is run
730 under a hypervisor, potentially improving performance significantly
731 over full virtualization. However, when run without a hypervisor
732 the kernel is theoretically slower and slightly larger.
734 config PARAVIRT_DEBUG
735 bool "paravirt-ops debugging"
736 depends on PARAVIRT && DEBUG_KERNEL
738 Enable to debug paravirt_ops internals. Specifically, BUG if
739 a paravirt_op is missing when it is called.
741 config PARAVIRT_SPINLOCKS
742 bool "Paravirtualization layer for spinlocks"
743 depends on PARAVIRT && SMP
745 Paravirtualized spinlocks allow a pvops backend to replace the
746 spinlock implementation with something virtualization-friendly
747 (for example, block the virtual CPU rather than spinning).
749 It has a minimal impact on native kernels and gives a nice performance
750 benefit on paravirtualized KVM / Xen kernels.
752 If you are unsure how to answer this question, answer Y.
754 config QUEUED_LOCK_STAT
755 bool "Paravirt queued spinlock statistics"
756 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
758 Enable the collection of statistical data on the slowpath
759 behavior of paravirtualized queued spinlocks and report
762 source "arch/x86/xen/Kconfig"
765 bool "KVM Guest support (including kvmclock)"
767 select PARAVIRT_CLOCK
770 This option enables various optimizations for running under the KVM
771 hypervisor. It includes a paravirtualized clock, so that instead
772 of relying on a PIT (or probably other) emulation by the
773 underlying device model, the host provides the guest with
774 timing infrastructure such as time of day, and system time
777 bool "Enable debug information for KVM Guests in debugfs"
778 depends on KVM_GUEST && DEBUG_FS
781 This option enables collection of various statistics for KVM guest.
782 Statistics are displayed in debugfs filesystem. Enabling this option
783 may incur significant overhead.
785 config PARAVIRT_TIME_ACCOUNTING
786 bool "Paravirtual steal time accounting"
790 Select this option to enable fine granularity task steal time
791 accounting. Time spent executing other tasks in parallel with
792 the current vCPU is discounted from the vCPU power. To account for
793 that, there can be a small performance impact.
795 If in doubt, say N here.
797 config PARAVIRT_CLOCK
800 endif #HYPERVISOR_GUEST
805 source "arch/x86/Kconfig.cpu"
809 prompt "HPET Timer Support" if X86_32
811 Use the IA-PC HPET (High Precision Event Timer) to manage
812 time in preference to the PIT and RTC, if a HPET is
814 HPET is the next generation timer replacing legacy 8254s.
815 The HPET provides a stable time base on SMP
816 systems, unlike the TSC, but it is more expensive to access,
817 as it is off-chip. The interface used is documented
818 in the HPET spec, revision 1.
820 You can safely choose Y here. However, HPET will only be
821 activated if the platform and the BIOS support this feature.
822 Otherwise the 8254 will be used for timing services.
824 Choose N to continue using the legacy 8254 timer.
826 config HPET_EMULATE_RTC
828 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
831 def_bool y if X86_INTEL_MID
832 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
834 depends on X86_INTEL_MID && SFI
836 APB timer is the replacement for 8254, HPET on X86 MID platforms.
837 The APBT provides a stable time base on SMP
838 systems, unlike the TSC, but it is more expensive to access,
839 as it is off-chip. APB timers are always running regardless of CPU
840 C states, they are used as per CPU clockevent device when possible.
842 # Mark as expert because too many people got it wrong.
843 # The code disables itself when not needed.
846 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
847 bool "Enable DMI scanning" if EXPERT
849 Enabled scanning of DMI to identify machine quirks. Say Y
850 here unless you have verified that your setup is not
851 affected by entries in the DMI blacklist. Required by PNP
855 bool "Old AMD GART IOMMU support"
857 depends on X86_64 && PCI && AMD_NB
859 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
860 GART based hardware IOMMUs.
862 The GART supports full DMA access for devices with 32-bit access
863 limitations, on systems with more than 3 GB. This is usually needed
864 for USB, sound, many IDE/SATA chipsets and some other devices.
866 Newer systems typically have a modern AMD IOMMU, supported via
867 the CONFIG_AMD_IOMMU=y config option.
869 In normal configurations this driver is only active when needed:
870 there's more than 3 GB of memory and the system contains a
871 32-bit limited device.
876 bool "IBM Calgary IOMMU support"
878 depends on X86_64 && PCI
880 Support for hardware IOMMUs in IBM's xSeries x366 and x460
881 systems. Needed to run systems with more than 3GB of memory
882 properly with 32-bit PCI devices that do not support DAC
883 (Double Address Cycle). Calgary also supports bus level
884 isolation, where all DMAs pass through the IOMMU. This
885 prevents them from going anywhere except their intended
886 destination. This catches hard-to-find kernel bugs and
887 mis-behaving drivers and devices that do not use the DMA-API
888 properly to set up their DMA buffers. The IOMMU can be
889 turned off at boot time with the iommu=off parameter.
890 Normally the kernel will make the right choice by itself.
893 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
895 prompt "Should Calgary be enabled by default?"
896 depends on CALGARY_IOMMU
898 Should Calgary be enabled by default? if you choose 'y', Calgary
899 will be used (if it exists). If you choose 'n', Calgary will not be
900 used even if it exists. If you choose 'n' and would like to use
901 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
904 # need this always selected by IOMMU for the VIA workaround
908 Support for software bounce buffers used on x86-64 systems
909 which don't have a hardware IOMMU. Using this PCI devices
910 which can only access 32-bits of memory can be used on systems
911 with more than 3 GB of memory.
916 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
919 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
920 depends on X86_64 && SMP && DEBUG_KERNEL
921 select CPUMASK_OFFSTACK
923 Enable maximum number of CPUS and NUMA Nodes for this architecture.
927 int "Maximum number of CPUs" if SMP && !MAXSMP
928 range 2 8 if SMP && X86_32 && !X86_BIGSMP
929 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
930 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
932 default "8192" if MAXSMP
933 default "32" if SMP && X86_BIGSMP
934 default "8" if SMP && X86_32
937 This allows you to specify the maximum number of CPUs which this
938 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
939 supported value is 8192, otherwise the maximum value is 512. The
940 minimum value which makes sense is 2.
942 This is purely to save memory - each supported CPU adds
943 approximately eight kilobytes to the kernel image.
946 bool "SMT (Hyperthreading) scheduler support"
949 SMT scheduler support improves the CPU scheduler's decision making
950 when dealing with Intel Pentium 4 chips with HyperThreading at a
951 cost of slightly increased overhead in some places. If unsure say
956 prompt "Multi-core scheduler support"
959 Multi-core scheduler support improves the CPU scheduler's decision
960 making when dealing with multi-core CPU chips at a cost of slightly
961 increased overhead in some places. If unsure say N here.
964 bool "CPU core priorities scheduler support"
965 depends on SCHED_MC && CPU_SUP_INTEL
966 select X86_INTEL_PSTATE
970 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
971 core ordering determined at manufacturing time, which allows
972 certain cores to reach higher turbo frequencies (when running
973 single threaded workloads) than others.
975 Enabling this kernel feature teaches the scheduler about
976 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
977 scheduler's CPU selection logic accordingly, so that higher
978 overall system performance can be achieved.
980 This feature will have no effect on CPUs without this feature.
982 If unsure say Y here.
984 source "kernel/Kconfig.preempt"
988 depends on !SMP && X86_LOCAL_APIC
991 bool "Local APIC support on uniprocessors" if !PCI_MSI
993 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
995 A local APIC (Advanced Programmable Interrupt Controller) is an
996 integrated interrupt controller in the CPU. If you have a single-CPU
997 system which has a processor with a local APIC, you can say Y here to
998 enable and use it. If you say Y here even though your machine doesn't
999 have a local APIC, then the kernel will still run with no slowdown at
1000 all. The local APIC supports CPU-generated self-interrupts (timer,
1001 performance counters), and the NMI watchdog which detects hard
1004 config X86_UP_IOAPIC
1005 bool "IO-APIC support on uniprocessors"
1006 depends on X86_UP_APIC
1008 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1009 SMP-capable replacement for PC-style interrupt controllers. Most
1010 SMP systems and many recent uniprocessor systems have one.
1012 If you have a single-CPU system with an IO-APIC, you can say Y here
1013 to use it. If you say Y here even though your machine doesn't have
1014 an IO-APIC, then the kernel will still run with no slowdown at all.
1016 config X86_LOCAL_APIC
1018 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1019 select IRQ_DOMAIN_HIERARCHY
1020 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1024 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1026 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1027 bool "Reroute for broken boot IRQs"
1028 depends on X86_IO_APIC
1030 This option enables a workaround that fixes a source of
1031 spurious interrupts. This is recommended when threaded
1032 interrupt handling is used on systems where the generation of
1033 superfluous "boot interrupts" cannot be disabled.
1035 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1036 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1037 kernel does during interrupt handling). On chipsets where this
1038 boot IRQ generation cannot be disabled, this workaround keeps
1039 the original IRQ line masked so that only the equivalent "boot
1040 IRQ" is delivered to the CPUs. The workaround also tells the
1041 kernel to set up the IRQ handler on the boot IRQ line. In this
1042 way only one interrupt is delivered to the kernel. Otherwise
1043 the spurious second interrupt may cause the kernel to bring
1044 down (vital) interrupt lines.
1046 Only affects "broken" chipsets. Interrupt sharing may be
1047 increased on these systems.
1050 bool "Machine Check / overheating reporting"
1051 select GENERIC_ALLOCATOR
1054 Machine Check support allows the processor to notify the
1055 kernel if it detects a problem (e.g. overheating, data corruption).
1056 The action the kernel takes depends on the severity of the problem,
1057 ranging from warning messages to halting the machine.
1059 config X86_MCELOG_LEGACY
1060 bool "Support for deprecated /dev/mcelog character device"
1063 Enable support for /dev/mcelog which is needed by the old mcelog
1064 userspace logging daemon. Consider switching to the new generation
1067 config X86_MCE_INTEL
1069 prompt "Intel MCE features"
1070 depends on X86_MCE && X86_LOCAL_APIC
1072 Additional support for intel specific MCE features such as
1073 the thermal monitor.
1077 prompt "AMD MCE features"
1078 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1080 Additional support for AMD specific MCE features such as
1081 the DRAM Error Threshold.
1083 config X86_ANCIENT_MCE
1084 bool "Support for old Pentium 5 / WinChip machine checks"
1085 depends on X86_32 && X86_MCE
1087 Include support for machine check handling on old Pentium 5 or WinChip
1088 systems. These typically need to be enabled explicitly on the command
1091 config X86_MCE_THRESHOLD
1092 depends on X86_MCE_AMD || X86_MCE_INTEL
1095 config X86_MCE_INJECT
1096 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1097 tristate "Machine check injector support"
1099 Provide support for injecting machine checks for testing purposes.
1100 If you don't know what a machine check is and you don't do kernel
1101 QA it is safe to say n.
1103 config X86_THERMAL_VECTOR
1105 depends on X86_MCE_INTEL
1107 source "arch/x86/events/Kconfig"
1109 config X86_LEGACY_VM86
1110 bool "Legacy VM86 support"
1114 This option allows user programs to put the CPU into V8086
1115 mode, which is an 80286-era approximation of 16-bit real mode.
1117 Some very old versions of X and/or vbetool require this option
1118 for user mode setting. Similarly, DOSEMU will use it if
1119 available to accelerate real mode DOS programs. However, any
1120 recent version of DOSEMU, X, or vbetool should be fully
1121 functional even without kernel VM86 support, as they will all
1122 fall back to software emulation. Nevertheless, if you are using
1123 a 16-bit DOS program where 16-bit performance matters, vm86
1124 mode might be faster than emulation and you might want to
1127 Note that any app that works on a 64-bit kernel is unlikely to
1128 need this option, as 64-bit kernels don't, and can't, support
1129 V8086 mode. This option is also unrelated to 16-bit protected
1130 mode and is not needed to run most 16-bit programs under Wine.
1132 Enabling this option increases the complexity of the kernel
1133 and slows down exception handling a tiny bit.
1135 If unsure, say N here.
1139 default X86_LEGACY_VM86
1142 bool "Enable support for 16-bit segments" if EXPERT
1144 depends on MODIFY_LDT_SYSCALL
1146 This option is required by programs like Wine to run 16-bit
1147 protected mode legacy code on x86 processors. Disabling
1148 this option saves about 300 bytes on i386, or around 6K text
1149 plus 16K runtime memory on x86-64,
1153 depends on X86_16BIT && X86_32
1157 depends on X86_16BIT && X86_64
1159 config X86_VSYSCALL_EMULATION
1160 bool "Enable vsyscall emulation" if EXPERT
1164 This enables emulation of the legacy vsyscall page. Disabling
1165 it is roughly equivalent to booting with vsyscall=none, except
1166 that it will also disable the helpful warning if a program
1167 tries to use a vsyscall. With this option set to N, offending
1168 programs will just segfault, citing addresses of the form
1171 This option is required by many programs built before 2013, and
1172 care should be used even with newer programs if set to N.
1174 Disabling this option saves about 7K of kernel size and
1175 possibly 4K of additional runtime pagetable memory.
1178 tristate "Toshiba Laptop support"
1181 This adds a driver to safely access the System Management Mode of
1182 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1183 not work on models with a Phoenix BIOS. The System Management Mode
1184 is used to set the BIOS and power saving options on Toshiba portables.
1186 For information on utilities to make use of this driver see the
1187 Toshiba Linux utilities web site at:
1188 <http://www.buzzard.org.uk/toshiba/>.
1190 Say Y if you intend to run this kernel on a Toshiba portable.
1194 tristate "Dell i8k legacy laptop support"
1196 select SENSORS_DELL_SMM
1198 This option enables legacy /proc/i8k userspace interface in hwmon
1199 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1200 temperature and allows controlling fan speeds of Dell laptops via
1201 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1202 it reports also power and hotkey status. For fan speed control is
1203 needed userspace package i8kutils.
1205 Say Y if you intend to run this kernel on old Dell laptops or want to
1206 use userspace package i8kutils.
1209 config X86_REBOOTFIXUPS
1210 bool "Enable X86 board specific fixups for reboot"
1213 This enables chipset and/or board specific fixups to be done
1214 in order to get reboot to work correctly. This is only needed on
1215 some combinations of hardware and BIOS. The symptom, for which
1216 this config is intended, is when reboot ends with a stalled/hung
1219 Currently, the only fixup is for the Geode machines using
1220 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1222 Say Y if you want to enable the fixup. Currently, it's safe to
1223 enable this option even if you don't need it.
1227 bool "CPU microcode loading support"
1229 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1232 If you say Y here, you will be able to update the microcode on
1233 Intel and AMD processors. The Intel support is for the IA32 family,
1234 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1235 AMD support is for families 0x10 and later. You will obviously need
1236 the actual microcode binary data itself which is not shipped with
1239 The preferred method to load microcode from a detached initrd is described
1240 in Documentation/x86/early-microcode.txt. For that you need to enable
1241 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1242 initrd for microcode blobs.
1244 In addition, you can build-in the microcode into the kernel. For that you
1245 need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
1246 to the CONFIG_EXTRA_FIRMWARE config option.
1248 config MICROCODE_INTEL
1249 bool "Intel microcode loading support"
1250 depends on MICROCODE
1254 This options enables microcode patch loading support for Intel
1257 For the current Intel microcode data package go to
1258 <https://downloadcenter.intel.com> and search for
1259 'Linux Processor Microcode Data File'.
1261 config MICROCODE_AMD
1262 bool "AMD microcode loading support"
1263 depends on MICROCODE
1266 If you select this option, microcode patch loading support for AMD
1267 processors will be enabled.
1269 config MICROCODE_OLD_INTERFACE
1271 depends on MICROCODE
1274 tristate "/dev/cpu/*/msr - Model-specific register support"
1276 This device gives privileged processes access to the x86
1277 Model-Specific Registers (MSRs). It is a character device with
1278 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1279 MSR accesses are directed to a specific CPU on multi-processor
1283 tristate "/dev/cpu/*/cpuid - CPU information support"
1285 This device gives processes access to the x86 CPUID instruction to
1286 be executed on a specific processor. It is a character device
1287 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1291 prompt "High Memory Support"
1298 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1299 However, the address space of 32-bit x86 processors is only 4
1300 Gigabytes large. That means that, if you have a large amount of
1301 physical memory, not all of it can be "permanently mapped" by the
1302 kernel. The physical memory that's not permanently mapped is called
1305 If you are compiling a kernel which will never run on a machine with
1306 more than 1 Gigabyte total physical RAM, answer "off" here (default
1307 choice and suitable for most users). This will result in a "3GB/1GB"
1308 split: 3GB are mapped so that each process sees a 3GB virtual memory
1309 space and the remaining part of the 4GB virtual memory space is used
1310 by the kernel to permanently map as much physical memory as
1313 If the machine has between 1 and 4 Gigabytes physical RAM, then
1316 If more than 4 Gigabytes is used then answer "64GB" here. This
1317 selection turns Intel PAE (Physical Address Extension) mode on.
1318 PAE implements 3-level paging on IA32 processors. PAE is fully
1319 supported by Linux, PAE mode is implemented on all recent Intel
1320 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1321 then the kernel will not boot on CPUs that don't support PAE!
1323 The actual amount of total physical memory will either be
1324 auto detected or can be forced by using a kernel command line option
1325 such as "mem=256M". (Try "man bootparam" or see the documentation of
1326 your boot loader (lilo or loadlin) about how to pass options to the
1327 kernel at boot time.)
1329 If unsure, say "off".
1334 Select this if you have a 32-bit processor and between 1 and 4
1335 gigabytes of physical RAM.
1342 Select this if you have a 32-bit processor and more than 4
1343 gigabytes of physical RAM.
1348 prompt "Memory split" if EXPERT
1352 Select the desired split between kernel and user memory.
1354 If the address range available to the kernel is less than the
1355 physical memory installed, the remaining memory will be available
1356 as "high memory". Accessing high memory is a little more costly
1357 than low memory, as it needs to be mapped into the kernel first.
1358 Note that increasing the kernel address space limits the range
1359 available to user programs, making the address space there
1360 tighter. Selecting anything other than the default 3G/1G split
1361 will also likely make your kernel incompatible with binary-only
1364 If you are not absolutely sure what you are doing, leave this
1368 bool "3G/1G user/kernel split"
1369 config VMSPLIT_3G_OPT
1371 bool "3G/1G user/kernel split (for full 1G low memory)"
1373 bool "2G/2G user/kernel split"
1374 config VMSPLIT_2G_OPT
1376 bool "2G/2G user/kernel split (for full 2G low memory)"
1378 bool "1G/3G user/kernel split"
1383 default 0xB0000000 if VMSPLIT_3G_OPT
1384 default 0x80000000 if VMSPLIT_2G
1385 default 0x78000000 if VMSPLIT_2G_OPT
1386 default 0x40000000 if VMSPLIT_1G
1392 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1395 bool "PAE (Physical Address Extension) Support"
1396 depends on X86_32 && !HIGHMEM4G
1399 PAE is required for NX support, and furthermore enables
1400 larger swapspace support for non-overcommit purposes. It
1401 has the cost of more pagetable lookup overhead, and also
1402 consumes more pagetable space per process.
1405 bool "Enable 5-level page tables support"
1408 5-level paging enables access to larger address space:
1409 upto 128 PiB of virtual address space and 4 PiB of
1410 physical address space.
1412 It will be supported by future Intel CPUs.
1414 Note: a kernel with this option enabled can only be booted
1415 on machines that support the feature.
1417 See Documentation/x86/x86_64/5level-paging.txt for more
1422 config ARCH_PHYS_ADDR_T_64BIT
1424 depends on X86_64 || X86_PAE
1426 config ARCH_DMA_ADDR_T_64BIT
1428 depends on X86_64 || HIGHMEM64G
1430 config X86_DIRECT_GBPAGES
1432 depends on X86_64 && !DEBUG_PAGEALLOC
1434 Certain kernel features effectively disable kernel
1435 linear 1 GB mappings (even if the CPU otherwise
1436 supports them), so don't confuse the user by printing
1437 that we have them enabled.
1439 config ARCH_HAS_MEM_ENCRYPT
1442 config AMD_MEM_ENCRYPT
1443 bool "AMD Secure Memory Encryption (SME) support"
1444 depends on X86_64 && CPU_SUP_AMD
1446 Say yes to enable support for the encryption of system memory.
1447 This requires an AMD processor that supports Secure Memory
1450 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1451 bool "Activate AMD Secure Memory Encryption (SME) by default"
1453 depends on AMD_MEM_ENCRYPT
1455 Say yes to have system memory encrypted by default if running on
1456 an AMD processor that supports Secure Memory Encryption (SME).
1458 If set to Y, then the encryption of system memory can be
1459 deactivated with the mem_encrypt=off command line option.
1461 If set to N, then the encryption of system memory can be
1462 activated with the mem_encrypt=on command line option.
1464 config ARCH_USE_MEMREMAP_PROT
1466 depends on AMD_MEM_ENCRYPT
1468 # Common NUMA Features
1470 bool "Numa Memory Allocation and Scheduler Support"
1472 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1473 default y if X86_BIGSMP
1475 Enable NUMA (Non Uniform Memory Access) support.
1477 The kernel will try to allocate memory used by a CPU on the
1478 local memory controller of the CPU and add some more
1479 NUMA awareness to the kernel.
1481 For 64-bit this is recommended if the system is Intel Core i7
1482 (or later), AMD Opteron, or EM64T NUMA.
1484 For 32-bit this is only needed if you boot a 32-bit
1485 kernel on a 64-bit NUMA platform.
1487 Otherwise, you should say N.
1491 prompt "Old style AMD Opteron NUMA detection"
1492 depends on X86_64 && NUMA && PCI
1494 Enable AMD NUMA node topology detection. You should say Y here if
1495 you have a multi processor AMD system. This uses an old method to
1496 read the NUMA configuration directly from the builtin Northbridge
1497 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1498 which also takes priority if both are compiled in.
1500 config X86_64_ACPI_NUMA
1502 prompt "ACPI NUMA detection"
1503 depends on X86_64 && NUMA && ACPI && PCI
1506 Enable ACPI SRAT based node topology detection.
1508 # Some NUMA nodes have memory ranges that span
1509 # other nodes. Even though a pfn is valid and
1510 # between a node's start and end pfns, it may not
1511 # reside on that node. See memmap_init_zone()
1513 config NODES_SPAN_OTHER_NODES
1515 depends on X86_64_ACPI_NUMA
1518 bool "NUMA emulation"
1521 Enable NUMA emulation. A flat machine will be split
1522 into virtual nodes when booted with "numa=fake=N", where N is the
1523 number of nodes. This is only useful for debugging.
1526 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1528 default "10" if MAXSMP
1529 default "6" if X86_64
1531 depends on NEED_MULTIPLE_NODES
1533 Specify the maximum number of NUMA Nodes available on the target
1534 system. Increases memory reserved to accommodate various tables.
1536 config ARCH_HAVE_MEMORY_PRESENT
1538 depends on X86_32 && DISCONTIGMEM
1540 config NEED_NODE_MEMMAP_SIZE
1542 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1544 config ARCH_FLATMEM_ENABLE
1546 depends on X86_32 && !NUMA
1548 config ARCH_DISCONTIGMEM_ENABLE
1550 depends on NUMA && X86_32
1552 config ARCH_DISCONTIGMEM_DEFAULT
1554 depends on NUMA && X86_32
1556 config ARCH_SPARSEMEM_ENABLE
1558 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1559 select SPARSEMEM_STATIC if X86_32
1560 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1562 config ARCH_SPARSEMEM_DEFAULT
1566 config ARCH_SELECT_MEMORY_MODEL
1568 depends on ARCH_SPARSEMEM_ENABLE
1570 config ARCH_MEMORY_PROBE
1571 bool "Enable sysfs memory/probe interface"
1572 depends on X86_64 && MEMORY_HOTPLUG
1574 This option enables a sysfs memory/probe interface for testing.
1575 See Documentation/memory-hotplug.txt for more information.
1576 If you are unsure how to answer this question, answer N.
1578 config ARCH_PROC_KCORE_TEXT
1580 depends on X86_64 && PROC_KCORE
1582 config ILLEGAL_POINTER_VALUE
1585 default 0xdead000000000000 if X86_64
1589 config X86_PMEM_LEGACY_DEVICE
1592 config X86_PMEM_LEGACY
1593 tristate "Support non-standard NVDIMMs and ADR protected memory"
1594 depends on PHYS_ADDR_T_64BIT
1596 select X86_PMEM_LEGACY_DEVICE
1599 Treat memory marked using the non-standard e820 type of 12 as used
1600 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1601 The kernel will offer these regions to the 'pmem' driver so
1602 they can be used for persistent storage.
1607 bool "Allocate 3rd-level pagetables from highmem"
1610 The VM uses one page table entry for each page of physical memory.
1611 For systems with a lot of RAM, this can be wasteful of precious
1612 low memory. Setting this option will put user-space page table
1613 entries in high memory.
1615 config X86_CHECK_BIOS_CORRUPTION
1616 bool "Check for low memory corruption"
1618 Periodically check for memory corruption in low memory, which
1619 is suspected to be caused by BIOS. Even when enabled in the
1620 configuration, it is disabled at runtime. Enable it by
1621 setting "memory_corruption_check=1" on the kernel command
1622 line. By default it scans the low 64k of memory every 60
1623 seconds; see the memory_corruption_check_size and
1624 memory_corruption_check_period parameters in
1625 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1627 When enabled with the default parameters, this option has
1628 almost no overhead, as it reserves a relatively small amount
1629 of memory and scans it infrequently. It both detects corruption
1630 and prevents it from affecting the running system.
1632 It is, however, intended as a diagnostic tool; if repeatable
1633 BIOS-originated corruption always affects the same memory,
1634 you can use memmap= to prevent the kernel from using that
1637 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1638 bool "Set the default setting of memory_corruption_check"
1639 depends on X86_CHECK_BIOS_CORRUPTION
1642 Set whether the default state of memory_corruption_check is
1645 config X86_RESERVE_LOW
1646 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1650 Specify the amount of low memory to reserve for the BIOS.
1652 The first page contains BIOS data structures that the kernel
1653 must not use, so that page must always be reserved.
1655 By default we reserve the first 64K of physical RAM, as a
1656 number of BIOSes are known to corrupt that memory range
1657 during events such as suspend/resume or monitor cable
1658 insertion, so it must not be used by the kernel.
1660 You can set this to 4 if you are absolutely sure that you
1661 trust the BIOS to get all its memory reservations and usages
1662 right. If you know your BIOS have problems beyond the
1663 default 64K area, you can set this to 640 to avoid using the
1664 entire low memory range.
1666 If you have doubts about the BIOS (e.g. suspend/resume does
1667 not work or there's kernel crashes after certain hardware
1668 hotplug events) then you might want to enable
1669 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1670 typical corruption patterns.
1672 Leave this to the default value of 64 if you are unsure.
1674 config MATH_EMULATION
1676 depends on MODIFY_LDT_SYSCALL
1677 prompt "Math emulation" if X86_32
1679 Linux can emulate a math coprocessor (used for floating point
1680 operations) if you don't have one. 486DX and Pentium processors have
1681 a math coprocessor built in, 486SX and 386 do not, unless you added
1682 a 487DX or 387, respectively. (The messages during boot time can
1683 give you some hints here ["man dmesg"].) Everyone needs either a
1684 coprocessor or this emulation.
1686 If you don't have a math coprocessor, you need to say Y here; if you
1687 say Y here even though you have a coprocessor, the coprocessor will
1688 be used nevertheless. (This behavior can be changed with the kernel
1689 command line option "no387", which comes handy if your coprocessor
1690 is broken. Try "man bootparam" or see the documentation of your boot
1691 loader (lilo or loadlin) about how to pass options to the kernel at
1692 boot time.) This means that it is a good idea to say Y here if you
1693 intend to use this kernel on different machines.
1695 More information about the internals of the Linux math coprocessor
1696 emulation can be found in <file:arch/x86/math-emu/README>.
1698 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1699 kernel, it won't hurt.
1703 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1705 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1706 the Memory Type Range Registers (MTRRs) may be used to control
1707 processor access to memory ranges. This is most useful if you have
1708 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1709 allows bus write transfers to be combined into a larger transfer
1710 before bursting over the PCI/AGP bus. This can increase performance
1711 of image write operations 2.5 times or more. Saying Y here creates a
1712 /proc/mtrr file which may be used to manipulate your processor's
1713 MTRRs. Typically the X server should use this.
1715 This code has a reasonably generic interface so that similar
1716 control registers on other processors can be easily supported
1719 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1720 Registers (ARRs) which provide a similar functionality to MTRRs. For
1721 these, the ARRs are used to emulate the MTRRs.
1722 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1723 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1724 write-combining. All of these processors are supported by this code
1725 and it makes sense to say Y here if you have one of them.
1727 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1728 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1729 can lead to all sorts of problems, so it's good to say Y here.
1731 You can safely say Y even if your machine doesn't have MTRRs, you'll
1732 just add about 9 KB to your kernel.
1734 See <file:Documentation/x86/mtrr.txt> for more information.
1736 config MTRR_SANITIZER
1738 prompt "MTRR cleanup support"
1741 Convert MTRR layout from continuous to discrete, so X drivers can
1742 add writeback entries.
1744 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1745 The largest mtrr entry size for a continuous block can be set with
1750 config MTRR_SANITIZER_ENABLE_DEFAULT
1751 int "MTRR cleanup enable value (0-1)"
1754 depends on MTRR_SANITIZER
1756 Enable mtrr cleanup default value
1758 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1759 int "MTRR cleanup spare reg num (0-7)"
1762 depends on MTRR_SANITIZER
1764 mtrr cleanup spare entries default, it can be changed via
1765 mtrr_spare_reg_nr=N on the kernel command line.
1769 prompt "x86 PAT support" if EXPERT
1772 Use PAT attributes to setup page level cache control.
1774 PATs are the modern equivalents of MTRRs and are much more
1775 flexible than MTRRs.
1777 Say N here if you see bootup problems (boot crash, boot hang,
1778 spontaneous reboots) or a non-working video driver.
1782 config ARCH_USES_PG_UNCACHED
1788 prompt "x86 architectural random number generator" if EXPERT
1790 Enable the x86 architectural RDRAND instruction
1791 (Intel Bull Mountain technology) to generate random numbers.
1792 If supported, this is a high bandwidth, cryptographically
1793 secure hardware random number generator.
1797 prompt "Supervisor Mode Access Prevention" if EXPERT
1799 Supervisor Mode Access Prevention (SMAP) is a security
1800 feature in newer Intel processors. There is a small
1801 performance cost if this enabled and turned on; there is
1802 also a small increase in the kernel size if this is enabled.
1806 config X86_INTEL_UMIP
1808 depends on CPU_SUP_INTEL
1809 prompt "Intel User Mode Instruction Prevention" if EXPERT
1811 The User Mode Instruction Prevention (UMIP) is a security
1812 feature in newer Intel processors. If enabled, a general
1813 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1814 or STR instructions are executed in user mode. These instructions
1815 unnecessarily expose information about the hardware state.
1817 The vast majority of applications do not use these instructions.
1818 For the very few that do, software emulation is provided in
1819 specific cases in protected and virtual-8086 modes. Emulated
1822 config X86_INTEL_MPX
1823 prompt "Intel MPX (Memory Protection Extensions)"
1825 # Note: only available in 64-bit mode due to VMA flags shortage
1826 depends on CPU_SUP_INTEL && X86_64
1827 select ARCH_USES_HIGH_VMA_FLAGS
1829 MPX provides hardware features that can be used in
1830 conjunction with compiler-instrumented code to check
1831 memory references. It is designed to detect buffer
1832 overflow or underflow bugs.
1834 This option enables running applications which are
1835 instrumented or otherwise use MPX. It does not use MPX
1836 itself inside the kernel or to protect the kernel
1837 against bad memory references.
1839 Enabling this option will make the kernel larger:
1840 ~8k of kernel text and 36 bytes of data on a 64-bit
1841 defconfig. It adds a long to the 'mm_struct' which
1842 will increase the kernel memory overhead of each
1843 process and adds some branches to paths used during
1844 exec() and munmap().
1846 For details, see Documentation/x86/intel_mpx.txt
1850 config X86_INTEL_MEMORY_PROTECTION_KEYS
1851 prompt "Intel Memory Protection Keys"
1853 # Note: only available in 64-bit mode
1854 depends on CPU_SUP_INTEL && X86_64
1855 select ARCH_USES_HIGH_VMA_FLAGS
1856 select ARCH_HAS_PKEYS
1858 Memory Protection Keys provides a mechanism for enforcing
1859 page-based protections, but without requiring modification of the
1860 page tables when an application changes protection domains.
1862 For details, see Documentation/x86/protection-keys.txt
1867 bool "EFI runtime service support"
1870 select EFI_RUNTIME_WRAPPERS
1872 This enables the kernel to use EFI runtime services that are
1873 available (such as the EFI variable services).
1875 This option is only useful on systems that have EFI firmware.
1876 In addition, you should use the latest ELILO loader available
1877 at <http://elilo.sourceforge.net> in order to take advantage
1878 of EFI runtime services. However, even with this option, the
1879 resultant kernel should continue to boot on existing non-EFI
1883 bool "EFI stub support"
1884 depends on EFI && !X86_USE_3DNOW
1887 This kernel feature allows a bzImage to be loaded directly
1888 by EFI firmware without the use of a bootloader.
1890 See Documentation/efi-stub.txt for more information.
1893 bool "EFI mixed-mode support"
1894 depends on EFI_STUB && X86_64
1896 Enabling this feature allows a 64-bit kernel to be booted
1897 on a 32-bit firmware, provided that your CPU supports 64-bit
1900 Note that it is not possible to boot a mixed-mode enabled
1901 kernel via the EFI boot stub - a bootloader that supports
1902 the EFI handover protocol must be used.
1908 prompt "Enable seccomp to safely compute untrusted bytecode"
1910 This kernel feature is useful for number crunching applications
1911 that may need to compute untrusted bytecode during their
1912 execution. By using pipes or other transports made available to
1913 the process as file descriptors supporting the read/write
1914 syscalls, it's possible to isolate those applications in
1915 their own address space using seccomp. Once seccomp is
1916 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1917 and the task is only allowed to execute a few safe syscalls
1918 defined by each seccomp mode.
1920 If unsure, say Y. Only embedded should say N here.
1922 source kernel/Kconfig.hz
1925 bool "kexec system call"
1928 kexec is a system call that implements the ability to shutdown your
1929 current kernel, and to start another kernel. It is like a reboot
1930 but it is independent of the system firmware. And like a reboot
1931 you can start any kernel with it, not just Linux.
1933 The name comes from the similarity to the exec system call.
1935 It is an ongoing process to be certain the hardware in a machine
1936 is properly shutdown, so do not be surprised if this code does not
1937 initially work for you. As of this writing the exact hardware
1938 interface is strongly in flux, so no good recommendation can be
1942 bool "kexec file based system call"
1947 depends on CRYPTO_SHA256=y
1949 This is new version of kexec system call. This system call is
1950 file based and takes file descriptors as system call argument
1951 for kernel and initramfs as opposed to list of segments as
1952 accepted by previous system call.
1954 config KEXEC_VERIFY_SIG
1955 bool "Verify kernel signature during kexec_file_load() syscall"
1956 depends on KEXEC_FILE
1958 This option makes kernel signature verification mandatory for
1959 the kexec_file_load() syscall.
1961 In addition to that option, you need to enable signature
1962 verification for the corresponding kernel image type being
1963 loaded in order for this to work.
1965 config KEXEC_BZIMAGE_VERIFY_SIG
1966 bool "Enable bzImage signature verification support"
1967 depends on KEXEC_VERIFY_SIG
1968 depends on SIGNED_PE_FILE_VERIFICATION
1969 select SYSTEM_TRUSTED_KEYRING
1971 Enable bzImage signature verification support.
1974 bool "kernel crash dumps"
1975 depends on X86_64 || (X86_32 && HIGHMEM)
1977 Generate crash dump after being started by kexec.
1978 This should be normally only set in special crash dump kernels
1979 which are loaded in the main kernel with kexec-tools into
1980 a specially reserved region and then later executed after
1981 a crash by kdump/kexec. The crash dump kernel must be compiled
1982 to a memory address not used by the main kernel or BIOS using
1983 PHYSICAL_START, or it must be built as a relocatable image
1984 (CONFIG_RELOCATABLE=y).
1985 For more details see Documentation/kdump/kdump.txt
1989 depends on KEXEC && HIBERNATION
1991 Jump between original kernel and kexeced kernel and invoke
1992 code in physical address mode via KEXEC
1994 config PHYSICAL_START
1995 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1998 This gives the physical address where the kernel is loaded.
2000 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2001 bzImage will decompress itself to above physical address and
2002 run from there. Otherwise, bzImage will run from the address where
2003 it has been loaded by the boot loader and will ignore above physical
2006 In normal kdump cases one does not have to set/change this option
2007 as now bzImage can be compiled as a completely relocatable image
2008 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2009 address. This option is mainly useful for the folks who don't want
2010 to use a bzImage for capturing the crash dump and want to use a
2011 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2012 to be specifically compiled to run from a specific memory area
2013 (normally a reserved region) and this option comes handy.
2015 So if you are using bzImage for capturing the crash dump,
2016 leave the value here unchanged to 0x1000000 and set
2017 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2018 for capturing the crash dump change this value to start of
2019 the reserved region. In other words, it can be set based on
2020 the "X" value as specified in the "crashkernel=YM@XM"
2021 command line boot parameter passed to the panic-ed
2022 kernel. Please take a look at Documentation/kdump/kdump.txt
2023 for more details about crash dumps.
2025 Usage of bzImage for capturing the crash dump is recommended as
2026 one does not have to build two kernels. Same kernel can be used
2027 as production kernel and capture kernel. Above option should have
2028 gone away after relocatable bzImage support is introduced. But it
2029 is present because there are users out there who continue to use
2030 vmlinux for dump capture. This option should go away down the
2033 Don't change this unless you know what you are doing.
2036 bool "Build a relocatable kernel"
2039 This builds a kernel image that retains relocation information
2040 so it can be loaded someplace besides the default 1MB.
2041 The relocations tend to make the kernel binary about 10% larger,
2042 but are discarded at runtime.
2044 One use is for the kexec on panic case where the recovery kernel
2045 must live at a different physical address than the primary
2048 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2049 it has been loaded at and the compile time physical address
2050 (CONFIG_PHYSICAL_START) is used as the minimum location.
2052 config RANDOMIZE_BASE
2053 bool "Randomize the address of the kernel image (KASLR)"
2054 depends on RELOCATABLE
2057 In support of Kernel Address Space Layout Randomization (KASLR),
2058 this randomizes the physical address at which the kernel image
2059 is decompressed and the virtual address where the kernel
2060 image is mapped, as a security feature that deters exploit
2061 attempts relying on knowledge of the location of kernel
2064 On 64-bit, the kernel physical and virtual addresses are
2065 randomized separately. The physical address will be anywhere
2066 between 16MB and the top of physical memory (up to 64TB). The
2067 virtual address will be randomized from 16MB up to 1GB (9 bits
2068 of entropy). Note that this also reduces the memory space
2069 available to kernel modules from 1.5GB to 1GB.
2071 On 32-bit, the kernel physical and virtual addresses are
2072 randomized together. They will be randomized from 16MB up to
2073 512MB (8 bits of entropy).
2075 Entropy is generated using the RDRAND instruction if it is
2076 supported. If RDTSC is supported, its value is mixed into
2077 the entropy pool as well. If neither RDRAND nor RDTSC are
2078 supported, then entropy is read from the i8254 timer. The
2079 usable entropy is limited by the kernel being built using
2080 2GB addressing, and that PHYSICAL_ALIGN must be at a
2081 minimum of 2MB. As a result, only 10 bits of entropy are
2082 theoretically possible, but the implementations are further
2083 limited due to memory layouts.
2087 # Relocation on x86 needs some additional build support
2088 config X86_NEED_RELOCS
2090 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2092 config PHYSICAL_ALIGN
2093 hex "Alignment value to which kernel should be aligned"
2095 range 0x2000 0x1000000 if X86_32
2096 range 0x200000 0x1000000 if X86_64
2098 This value puts the alignment restrictions on physical address
2099 where kernel is loaded and run from. Kernel is compiled for an
2100 address which meets above alignment restriction.
2102 If bootloader loads the kernel at a non-aligned address and
2103 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2104 address aligned to above value and run from there.
2106 If bootloader loads the kernel at a non-aligned address and
2107 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2108 load address and decompress itself to the address it has been
2109 compiled for and run from there. The address for which kernel is
2110 compiled already meets above alignment restrictions. Hence the
2111 end result is that kernel runs from a physical address meeting
2112 above alignment restrictions.
2114 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2115 this value must be a multiple of 0x200000.
2117 Don't change this unless you know what you are doing.
2119 config RANDOMIZE_MEMORY
2120 bool "Randomize the kernel memory sections"
2122 depends on RANDOMIZE_BASE
2123 default RANDOMIZE_BASE
2125 Randomizes the base virtual address of kernel memory sections
2126 (physical memory mapping, vmalloc & vmemmap). This security feature
2127 makes exploits relying on predictable memory locations less reliable.
2129 The order of allocations remains unchanged. Entropy is generated in
2130 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2131 configuration have in average 30,000 different possible virtual
2132 addresses for each memory section.
2136 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2137 hex "Physical memory mapping padding" if EXPERT
2138 depends on RANDOMIZE_MEMORY
2139 default "0xa" if MEMORY_HOTPLUG
2141 range 0x1 0x40 if MEMORY_HOTPLUG
2144 Define the padding in terabytes added to the existing physical
2145 memory size during kernel memory randomization. It is useful
2146 for memory hotplug support but reduces the entropy available for
2147 address randomization.
2149 If unsure, leave at the default value.
2152 bool "Support for hot-pluggable CPUs"
2155 Say Y here to allow turning CPUs off and on. CPUs can be
2156 controlled through /sys/devices/system/cpu.
2157 ( Note: power management support will enable this option
2158 automatically on SMP systems. )
2159 Say N if you want to disable CPU hotplug.
2161 config BOOTPARAM_HOTPLUG_CPU0
2162 bool "Set default setting of cpu0_hotpluggable"
2164 depends on HOTPLUG_CPU
2166 Set whether default state of cpu0_hotpluggable is on or off.
2168 Say Y here to enable CPU0 hotplug by default. If this switch
2169 is turned on, there is no need to give cpu0_hotplug kernel
2170 parameter and the CPU0 hotplug feature is enabled by default.
2172 Please note: there are two known CPU0 dependencies if you want
2173 to enable the CPU0 hotplug feature either by this switch or by
2174 cpu0_hotplug kernel parameter.
2176 First, resume from hibernate or suspend always starts from CPU0.
2177 So hibernate and suspend are prevented if CPU0 is offline.
2179 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2180 offline if any interrupt can not migrate out of CPU0. There may
2181 be other CPU0 dependencies.
2183 Please make sure the dependencies are under your control before
2184 you enable this feature.
2186 Say N if you don't want to enable CPU0 hotplug feature by default.
2187 You still can enable the CPU0 hotplug feature at boot by kernel
2188 parameter cpu0_hotplug.
2190 config DEBUG_HOTPLUG_CPU0
2192 prompt "Debug CPU0 hotplug"
2193 depends on HOTPLUG_CPU
2195 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2196 soon as possible and boots up userspace with CPU0 offlined. User
2197 can online CPU0 back after boot time.
2199 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2200 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2201 compilation or giving cpu0_hotplug kernel parameter at boot.
2207 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2208 depends on COMPAT_32
2210 Certain buggy versions of glibc will crash if they are
2211 presented with a 32-bit vDSO that is not mapped at the address
2212 indicated in its segment table.
2214 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2215 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2216 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2217 the only released version with the bug, but OpenSUSE 9
2218 contains a buggy "glibc 2.3.2".
2220 The symptom of the bug is that everything crashes on startup, saying:
2221 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2223 Saying Y here changes the default value of the vdso32 boot
2224 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2225 This works around the glibc bug but hurts performance.
2227 If unsure, say N: if you are compiling your own kernel, you
2228 are unlikely to be using a buggy version of glibc.
2231 prompt "vsyscall table for legacy applications"
2233 default LEGACY_VSYSCALL_EMULATE
2235 Legacy user code that does not know how to find the vDSO expects
2236 to be able to issue three syscalls by calling fixed addresses in
2237 kernel space. Since this location is not randomized with ASLR,
2238 it can be used to assist security vulnerability exploitation.
2240 This setting can be changed at boot time via the kernel command
2241 line parameter vsyscall=[native|emulate|none].
2243 On a system with recent enough glibc (2.14 or newer) and no
2244 static binaries, you can say None without a performance penalty
2245 to improve security.
2247 If unsure, select "Emulate".
2249 config LEGACY_VSYSCALL_NATIVE
2252 Actual executable code is located in the fixed vsyscall
2253 address mapping, implementing time() efficiently. Since
2254 this makes the mapping executable, it can be used during
2255 security vulnerability exploitation (traditionally as
2256 ROP gadgets). This configuration is not recommended.
2258 config LEGACY_VSYSCALL_EMULATE
2261 The kernel traps and emulates calls into the fixed
2262 vsyscall address mapping. This makes the mapping
2263 non-executable, but it still contains known contents,
2264 which could be used in certain rare security vulnerability
2265 exploits. This configuration is recommended when userspace
2266 still uses the vsyscall area.
2268 config LEGACY_VSYSCALL_NONE
2271 There will be no vsyscall mapping at all. This will
2272 eliminate any risk of ASLR bypass due to the vsyscall
2273 fixed address mapping. Attempts to use the vsyscalls
2274 will be reported to dmesg, so that either old or
2275 malicious userspace programs can be identified.
2280 bool "Built-in kernel command line"
2282 Allow for specifying boot arguments to the kernel at
2283 build time. On some systems (e.g. embedded ones), it is
2284 necessary or convenient to provide some or all of the
2285 kernel boot arguments with the kernel itself (that is,
2286 to not rely on the boot loader to provide them.)
2288 To compile command line arguments into the kernel,
2289 set this option to 'Y', then fill in the
2290 boot arguments in CONFIG_CMDLINE.
2292 Systems with fully functional boot loaders (i.e. non-embedded)
2293 should leave this option set to 'N'.
2296 string "Built-in kernel command string"
2297 depends on CMDLINE_BOOL
2300 Enter arguments here that should be compiled into the kernel
2301 image and used at boot time. If the boot loader provides a
2302 command line at boot time, it is appended to this string to
2303 form the full kernel command line, when the system boots.
2305 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2306 change this behavior.
2308 In most cases, the command line (whether built-in or provided
2309 by the boot loader) should specify the device for the root
2312 config CMDLINE_OVERRIDE
2313 bool "Built-in command line overrides boot loader arguments"
2314 depends on CMDLINE_BOOL
2316 Set this option to 'Y' to have the kernel ignore the boot loader
2317 command line, and use ONLY the built-in command line.
2319 This is used to work around broken boot loaders. This should
2320 be set to 'N' under normal conditions.
2322 config MODIFY_LDT_SYSCALL
2323 bool "Enable the LDT (local descriptor table)" if EXPERT
2326 Linux can allow user programs to install a per-process x86
2327 Local Descriptor Table (LDT) using the modify_ldt(2) system
2328 call. This is required to run 16-bit or segmented code such as
2329 DOSEMU or some Wine programs. It is also used by some very old
2330 threading libraries.
2332 Enabling this feature adds a small amount of overhead to
2333 context switches and increases the low-level kernel attack
2334 surface. Disabling it removes the modify_ldt(2) system call.
2336 Saying 'N' here may make sense for embedded or server kernels.
2338 source "kernel/livepatch/Kconfig"
2342 config ARCH_HAS_ADD_PAGES
2344 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2346 config ARCH_ENABLE_MEMORY_HOTPLUG
2348 depends on X86_64 || (X86_32 && HIGHMEM)
2350 config ARCH_ENABLE_MEMORY_HOTREMOVE
2352 depends on MEMORY_HOTPLUG
2354 config USE_PERCPU_NUMA_NODE_ID
2358 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2360 depends on X86_64 || X86_PAE
2362 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2364 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2366 config ARCH_ENABLE_THP_MIGRATION
2368 depends on X86_64 && TRANSPARENT_HUGEPAGE
2370 menu "Power management and ACPI options"
2372 config ARCH_HIBERNATION_HEADER
2374 depends on X86_64 && HIBERNATION
2376 source "kernel/power/Kconfig"
2378 source "drivers/acpi/Kconfig"
2380 source "drivers/sfi/Kconfig"
2387 tristate "APM (Advanced Power Management) BIOS support"
2388 depends on X86_32 && PM_SLEEP
2390 APM is a BIOS specification for saving power using several different
2391 techniques. This is mostly useful for battery powered laptops with
2392 APM compliant BIOSes. If you say Y here, the system time will be
2393 reset after a RESUME operation, the /proc/apm device will provide
2394 battery status information, and user-space programs will receive
2395 notification of APM "events" (e.g. battery status change).
2397 If you select "Y" here, you can disable actual use of the APM
2398 BIOS by passing the "apm=off" option to the kernel at boot time.
2400 Note that the APM support is almost completely disabled for
2401 machines with more than one CPU.
2403 In order to use APM, you will need supporting software. For location
2404 and more information, read <file:Documentation/power/apm-acpi.txt>
2405 and the Battery Powered Linux mini-HOWTO, available from
2406 <http://www.tldp.org/docs.html#howto>.
2408 This driver does not spin down disk drives (see the hdparm(8)
2409 manpage ("man 8 hdparm") for that), and it doesn't turn off
2410 VESA-compliant "green" monitors.
2412 This driver does not support the TI 4000M TravelMate and the ACER
2413 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2414 desktop machines also don't have compliant BIOSes, and this driver
2415 may cause those machines to panic during the boot phase.
2417 Generally, if you don't have a battery in your machine, there isn't
2418 much point in using this driver and you should say N. If you get
2419 random kernel OOPSes or reboots that don't seem to be related to
2420 anything, try disabling/enabling this option (or disabling/enabling
2423 Some other things you should try when experiencing seemingly random,
2426 1) make sure that you have enough swap space and that it is
2428 2) pass the "no-hlt" option to the kernel
2429 3) switch on floating point emulation in the kernel and pass
2430 the "no387" option to the kernel
2431 4) pass the "floppy=nodma" option to the kernel
2432 5) pass the "mem=4M" option to the kernel (thereby disabling
2433 all but the first 4 MB of RAM)
2434 6) make sure that the CPU is not over clocked.
2435 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2436 8) disable the cache from your BIOS settings
2437 9) install a fan for the video card or exchange video RAM
2438 10) install a better fan for the CPU
2439 11) exchange RAM chips
2440 12) exchange the motherboard.
2442 To compile this driver as a module, choose M here: the
2443 module will be called apm.
2447 config APM_IGNORE_USER_SUSPEND
2448 bool "Ignore USER SUSPEND"
2450 This option will ignore USER SUSPEND requests. On machines with a
2451 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2452 series notebooks, it is necessary to say Y because of a BIOS bug.
2454 config APM_DO_ENABLE
2455 bool "Enable PM at boot time"
2457 Enable APM features at boot time. From page 36 of the APM BIOS
2458 specification: "When disabled, the APM BIOS does not automatically
2459 power manage devices, enter the Standby State, enter the Suspend
2460 State, or take power saving steps in response to CPU Idle calls."
2461 This driver will make CPU Idle calls when Linux is idle (unless this
2462 feature is turned off -- see "Do CPU IDLE calls", below). This
2463 should always save battery power, but more complicated APM features
2464 will be dependent on your BIOS implementation. You may need to turn
2465 this option off if your computer hangs at boot time when using APM
2466 support, or if it beeps continuously instead of suspending. Turn
2467 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2468 T400CDT. This is off by default since most machines do fine without
2473 bool "Make CPU Idle calls when idle"
2475 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2476 On some machines, this can activate improved power savings, such as
2477 a slowed CPU clock rate, when the machine is idle. These idle calls
2478 are made after the idle loop has run for some length of time (e.g.,
2479 333 mS). On some machines, this will cause a hang at boot time or
2480 whenever the CPU becomes idle. (On machines with more than one CPU,
2481 this option does nothing.)
2483 config APM_DISPLAY_BLANK
2484 bool "Enable console blanking using APM"
2486 Enable console blanking using the APM. Some laptops can use this to
2487 turn off the LCD backlight when the screen blanker of the Linux
2488 virtual console blanks the screen. Note that this is only used by
2489 the virtual console screen blanker, and won't turn off the backlight
2490 when using the X Window system. This also doesn't have anything to
2491 do with your VESA-compliant power-saving monitor. Further, this
2492 option doesn't work for all laptops -- it might not turn off your
2493 backlight at all, or it might print a lot of errors to the console,
2494 especially if you are using gpm.
2496 config APM_ALLOW_INTS
2497 bool "Allow interrupts during APM BIOS calls"
2499 Normally we disable external interrupts while we are making calls to
2500 the APM BIOS as a measure to lessen the effects of a badly behaving
2501 BIOS implementation. The BIOS should reenable interrupts if it
2502 needs to. Unfortunately, some BIOSes do not -- especially those in
2503 many of the newer IBM Thinkpads. If you experience hangs when you
2504 suspend, try setting this to Y. Otherwise, say N.
2508 source "drivers/cpufreq/Kconfig"
2510 source "drivers/cpuidle/Kconfig"
2512 source "drivers/idle/Kconfig"
2517 menu "Bus options (PCI etc.)"
2523 Find out whether you have a PCI motherboard. PCI is the name of a
2524 bus system, i.e. the way the CPU talks to the other stuff inside
2525 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2526 VESA. If you have PCI, say Y, otherwise N.
2529 prompt "PCI access mode"
2530 depends on X86_32 && PCI
2533 On PCI systems, the BIOS can be used to detect the PCI devices and
2534 determine their configuration. However, some old PCI motherboards
2535 have BIOS bugs and may crash if this is done. Also, some embedded
2536 PCI-based systems don't have any BIOS at all. Linux can also try to
2537 detect the PCI hardware directly without using the BIOS.
2539 With this option, you can specify how Linux should detect the
2540 PCI devices. If you choose "BIOS", the BIOS will be used,
2541 if you choose "Direct", the BIOS won't be used, and if you
2542 choose "MMConfig", then PCI Express MMCONFIG will be used.
2543 If you choose "Any", the kernel will try MMCONFIG, then the
2544 direct access method and falls back to the BIOS if that doesn't
2545 work. If unsure, go with the default, which is "Any".
2550 config PCI_GOMMCONFIG
2567 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2569 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2572 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2576 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2580 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2584 depends on PCI && XEN
2592 bool "Support mmconfig PCI config space access"
2593 depends on X86_64 && PCI && ACPI
2595 config PCI_CNB20LE_QUIRK
2596 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2599 Read the PCI windows out of the CNB20LE host bridge. This allows
2600 PCI hotplug to work on systems with the CNB20LE chipset which do
2603 There's no public spec for this chipset, and this functionality
2604 is known to be incomplete.
2606 You should say N unless you know you need this.
2608 source "drivers/pci/Kconfig"
2611 bool "ISA-style bus support on modern systems" if EXPERT
2614 Enables ISA-style drivers on modern systems. This is necessary to
2615 support PC/104 devices on X86_64 platforms.
2619 # x86_64 have no ISA slots, but can have ISA-style DMA.
2621 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2624 Enables ISA-style DMA support for devices requiring such controllers.
2632 Find out whether you have ISA slots on your motherboard. ISA is the
2633 name of a bus system, i.e. the way the CPU talks to the other stuff
2634 inside your box. Other bus systems are PCI, EISA, MicroChannel
2635 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2636 newer boards don't support it. If you have ISA, say Y, otherwise N.
2642 The Extended Industry Standard Architecture (EISA) bus was
2643 developed as an open alternative to the IBM MicroChannel bus.
2645 The EISA bus provided some of the features of the IBM MicroChannel
2646 bus while maintaining backward compatibility with cards made for
2647 the older ISA bus. The EISA bus saw limited use between 1988 and
2648 1995 when it was made obsolete by the PCI bus.
2650 Say Y here if you are building a kernel for an EISA-based machine.
2654 source "drivers/eisa/Kconfig"
2657 tristate "NatSemi SCx200 support"
2659 This provides basic support for National Semiconductor's
2660 (now AMD's) Geode processors. The driver probes for the
2661 PCI-IDs of several on-chip devices, so its a good dependency
2662 for other scx200_* drivers.
2664 If compiled as a module, the driver is named scx200.
2666 config SCx200HR_TIMER
2667 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2671 This driver provides a clocksource built upon the on-chip
2672 27MHz high-resolution timer. Its also a workaround for
2673 NSC Geode SC-1100's buggy TSC, which loses time when the
2674 processor goes idle (as is done by the scheduler). The
2675 other workaround is idle=poll boot option.
2678 bool "One Laptop Per Child support"
2685 Add support for detecting the unique features of the OLPC
2689 bool "OLPC XO-1 Power Management"
2690 depends on OLPC && MFD_CS5535 && PM_SLEEP
2693 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2696 bool "OLPC XO-1 Real Time Clock"
2697 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2699 Add support for the XO-1 real time clock, which can be used as a
2700 programmable wakeup source.
2703 bool "OLPC XO-1 SCI extras"
2704 depends on OLPC && OLPC_XO1_PM
2710 Add support for SCI-based features of the OLPC XO-1 laptop:
2711 - EC-driven system wakeups
2715 - AC adapter status updates
2716 - Battery status updates
2718 config OLPC_XO15_SCI
2719 bool "OLPC XO-1.5 SCI extras"
2720 depends on OLPC && ACPI
2723 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2724 - EC-driven system wakeups
2725 - AC adapter status updates
2726 - Battery status updates
2729 bool "PCEngines ALIX System Support (LED setup)"
2732 This option enables system support for the PCEngines ALIX.
2733 At present this just sets up LEDs for GPIO control on
2734 ALIX2/3/6 boards. However, other system specific setup should
2737 Note: You must still enable the drivers for GPIO and LED support
2738 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2740 Note: You have to set alix.force=1 for boards with Award BIOS.
2743 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2746 This option enables system support for the Soekris Engineering net5501.
2749 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2753 This option enables system support for the Traverse Technologies GEOS.
2756 bool "Technologic Systems TS-5500 platform support"
2758 select CHECK_SIGNATURE
2762 This option enables system support for the Technologic Systems TS-5500.
2768 depends on CPU_SUP_AMD && PCI
2770 source "drivers/pcmcia/Kconfig"
2773 tristate "RapidIO support"
2777 If enabled this option will include drivers and the core
2778 infrastructure code to support RapidIO interconnect devices.
2780 source "drivers/rapidio/Kconfig"
2783 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2785 Firmwares often provide initial graphics framebuffers so the BIOS,
2786 bootloader or kernel can show basic video-output during boot for
2787 user-guidance and debugging. Historically, x86 used the VESA BIOS
2788 Extensions and EFI-framebuffers for this, which are mostly limited
2790 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2791 framebuffers so the new generic system-framebuffer drivers can be
2792 used on x86. If the framebuffer is not compatible with the generic
2793 modes, it is adverticed as fallback platform framebuffer so legacy
2794 drivers like efifb, vesafb and uvesafb can pick it up.
2795 If this option is not selected, all system framebuffers are always
2796 marked as fallback platform framebuffers as usual.
2798 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2799 not be able to pick up generic system framebuffers if this option
2800 is selected. You are highly encouraged to enable simplefb as
2801 replacement if you select this option. simplefb can correctly deal
2802 with generic system framebuffers. But you should still keep vesafb
2803 and others enabled as fallback if a system framebuffer is
2804 incompatible with simplefb.
2811 menu "Executable file formats / Emulations"
2813 source "fs/Kconfig.binfmt"
2815 config IA32_EMULATION
2816 bool "IA32 Emulation"
2818 select ARCH_WANT_OLD_COMPAT_IPC
2820 select COMPAT_BINFMT_ELF
2821 select COMPAT_OLD_SIGACTION
2823 Include code to run legacy 32-bit programs under a
2824 64-bit kernel. You should likely turn this on, unless you're
2825 100% sure that you don't have any 32-bit programs left.
2828 tristate "IA32 a.out support"
2829 depends on IA32_EMULATION
2831 Support old a.out binaries in the 32bit emulation.
2834 bool "x32 ABI for 64-bit mode"
2837 Include code to run binaries for the x32 native 32-bit ABI
2838 for 64-bit processors. An x32 process gets access to the
2839 full 64-bit register file and wide data path while leaving
2840 pointers at 32 bits for smaller memory footprint.
2842 You will need a recent binutils (2.22 or later) with
2843 elf32_x86_64 support enabled to compile a kernel with this
2848 depends on IA32_EMULATION || X86_32
2850 select OLD_SIGSUSPEND3
2854 depends on IA32_EMULATION || X86_X32
2857 config COMPAT_FOR_U64_ALIGNMENT
2860 config SYSVIPC_COMPAT
2868 config HAVE_ATOMIC_IOMAP
2872 config X86_DEV_DMA_OPS
2874 depends on X86_64 || STA2X11
2876 config X86_DMA_REMAP
2880 config HAVE_GENERIC_GUP
2883 source "net/Kconfig"
2885 source "drivers/Kconfig"
2887 source "drivers/firmware/Kconfig"
2891 source "arch/x86/Kconfig.debug"
2893 source "security/Kconfig"
2895 source "crypto/Kconfig"
2897 source "arch/x86/kvm/Kconfig"
2899 source "lib/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob