1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
18 select HAVE_GENERIC_DMA_COHERENT
19 select MODULES_USE_ELF_REL
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
27 select ARCH_SUPPORTS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select NEED_DMA_MAP_STATE
33 select X86_DEV_DMA_OPS
34 select ARCH_HAS_SYSCALL_WRAPPER
39 # ( Note that options that are marked 'if X86_64' could in principle be
40 # ported to 32-bit as well. )
45 # Note: keep this list sorted alphabetically
47 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
48 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
50 select ARCH_CLOCKSOURCE_DATA
51 select ARCH_DISCARD_MEMBLOCK
52 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
53 select ARCH_HAS_DEBUG_VIRTUAL
54 select ARCH_HAS_DEVMEM_IS_ALLOWED
55 select ARCH_HAS_ELF_RANDOMIZE
56 select ARCH_HAS_FAST_MULTIPLIER
57 select ARCH_HAS_FILTER_PGPROT
58 select ARCH_HAS_FORTIFY_SOURCE
59 select ARCH_HAS_GCOV_PROFILE_ALL
60 select ARCH_HAS_KCOV if X86_64
61 select ARCH_HAS_MEMBARRIER_SYNC_CORE
62 select ARCH_HAS_PMEM_API if X86_64
63 select ARCH_HAS_PTE_SPECIAL
64 select ARCH_HAS_REFCOUNT
65 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
66 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
67 select ARCH_HAS_SET_MEMORY
68 select ARCH_HAS_SG_CHAIN
69 select ARCH_HAS_STRICT_KERNEL_RWX
70 select ARCH_HAS_STRICT_MODULE_RWX
71 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
72 select ARCH_HAS_UBSAN_SANITIZE_ALL
73 select ARCH_HAS_ZONE_DEVICE if X86_64
74 select ARCH_HAVE_NMI_SAFE_CMPXCHG
75 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
76 select ARCH_MIGHT_HAVE_PC_PARPORT
77 select ARCH_MIGHT_HAVE_PC_SERIO
78 select ARCH_SUPPORTS_ACPI
79 select ARCH_SUPPORTS_ATOMIC_RMW
80 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
81 select ARCH_USE_BUILTIN_BSWAP
82 select ARCH_USE_QUEUED_RWLOCKS
83 select ARCH_USE_QUEUED_SPINLOCKS
84 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
85 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
86 select ARCH_WANTS_THP_SWAP if X86_64
87 select BUILDTIME_EXTABLE_SORT
89 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
90 select CLOCKSOURCE_WATCHDOG
91 select DCACHE_WORD_ACCESS
93 select EDAC_ATOMIC_SCRUB
95 select GENERIC_CLOCKEVENTS
96 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
97 select GENERIC_CLOCKEVENTS_MIN_ADJUST
98 select GENERIC_CMOS_UPDATE
99 select GENERIC_CPU_AUTOPROBE
100 select GENERIC_CPU_VULNERABILITIES
101 select GENERIC_EARLY_IOREMAP
102 select GENERIC_FIND_FIRST_BIT
104 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
105 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
106 select GENERIC_IRQ_MIGRATION if SMP
107 select GENERIC_IRQ_PROBE
108 select GENERIC_IRQ_RESERVATION_MODE
109 select GENERIC_IRQ_SHOW
110 select GENERIC_PENDING_IRQ if SMP
111 select GENERIC_SMP_IDLE_THREAD
112 select GENERIC_STRNCPY_FROM_USER
113 select GENERIC_STRNLEN_USER
114 select GENERIC_TIME_VSYSCALL
115 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
116 select HAVE_ACPI_APEI if ACPI
117 select HAVE_ACPI_APEI_NMI if ACPI
118 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
119 select HAVE_ARCH_AUDITSYSCALL
120 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
121 select HAVE_ARCH_JUMP_LABEL
122 select HAVE_ARCH_KASAN if X86_64
123 select HAVE_ARCH_KGDB
124 select HAVE_ARCH_MMAP_RND_BITS if MMU
125 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
126 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
127 select HAVE_ARCH_SECCOMP_FILTER
128 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
129 select HAVE_ARCH_TRACEHOOK
130 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
131 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
132 select HAVE_ARCH_VMAP_STACK if X86_64
133 select HAVE_ARCH_WITHIN_STACK_FRAMES
134 select HAVE_CMPXCHG_DOUBLE
135 select HAVE_CMPXCHG_LOCAL
136 select HAVE_CONTEXT_TRACKING if X86_64
137 select HAVE_COPY_THREAD_TLS
138 select HAVE_C_RECORDMCOUNT
139 select HAVE_DEBUG_KMEMLEAK
140 select HAVE_DEBUG_STACKOVERFLOW
141 select HAVE_DMA_CONTIGUOUS
142 select HAVE_DYNAMIC_FTRACE
143 select HAVE_DYNAMIC_FTRACE_WITH_REGS
145 select HAVE_EFFICIENT_UNALIGNED_ACCESS
146 select HAVE_EXIT_THREAD
147 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
148 select HAVE_FTRACE_MCOUNT_RECORD
149 select HAVE_FUNCTION_GRAPH_TRACER
150 select HAVE_FUNCTION_TRACER
151 select HAVE_GCC_PLUGINS
152 select HAVE_HW_BREAKPOINT
154 select HAVE_IOREMAP_PROT
155 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
156 select HAVE_IRQ_TIME_ACCOUNTING
157 select HAVE_KERNEL_BZIP2
158 select HAVE_KERNEL_GZIP
159 select HAVE_KERNEL_LZ4
160 select HAVE_KERNEL_LZMA
161 select HAVE_KERNEL_LZO
162 select HAVE_KERNEL_XZ
164 select HAVE_KPROBES_ON_FTRACE
165 select HAVE_FUNCTION_ERROR_INJECTION
166 select HAVE_KRETPROBES
168 select HAVE_LIVEPATCH if X86_64
170 select HAVE_MEMBLOCK_NODE_MAP
171 select HAVE_MIXED_BREAKPOINTS_REGS
172 select HAVE_MOD_ARCH_SPECIFIC
175 select HAVE_OPTPROBES
176 select HAVE_PCSPKR_PLATFORM
177 select HAVE_PERF_EVENTS
178 select HAVE_PERF_EVENTS_NMI
179 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
180 select HAVE_PERF_REGS
181 select HAVE_PERF_USER_STACK_DUMP
182 select HAVE_RCU_TABLE_FREE
183 select HAVE_REGS_AND_STACK_ACCESS_API
184 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
185 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
186 select HAVE_STACK_VALIDATION if X86_64
188 select HAVE_SYSCALL_TRACEPOINTS
189 select HAVE_UNSTABLE_SCHED_CLOCK
190 select HAVE_USER_RETURN_NOTIFIER
191 select HOTPLUG_SMT if SMP
192 select IRQ_FORCED_THREADING
193 select NEED_SG_DMA_LENGTH
194 select PCI_LOCKLESS_CONFIG
197 select RTC_MC146818_LIB
200 select SYSCTL_EXCEPTION_TRACE
201 select THREAD_INFO_IN_TASK
202 select USER_STACKTRACE_SUPPORT
204 select X86_FEATURE_NAMES if PROC_FS
206 config INSTRUCTION_DECODER
208 depends on KPROBES || PERF_EVENTS || UPROBES
212 default "elf32-i386" if X86_32
213 default "elf64-x86-64" if X86_64
215 config ARCH_DEFCONFIG
217 default "arch/x86/configs/i386_defconfig" if X86_32
218 default "arch/x86/configs/x86_64_defconfig" if X86_64
220 config LOCKDEP_SUPPORT
223 config STACKTRACE_SUPPORT
229 config ARCH_MMAP_RND_BITS_MIN
233 config ARCH_MMAP_RND_BITS_MAX
237 config ARCH_MMAP_RND_COMPAT_BITS_MIN
240 config ARCH_MMAP_RND_COMPAT_BITS_MAX
246 config GENERIC_ISA_DMA
248 depends on ISA_DMA_API
253 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
255 config GENERIC_BUG_RELATIVE_POINTERS
258 config GENERIC_HWEIGHT
261 config ARCH_MAY_HAVE_PC_FDC
263 depends on ISA_DMA_API
265 config RWSEM_XCHGADD_ALGORITHM
268 config GENERIC_CALIBRATE_DELAY
271 config ARCH_HAS_CPU_RELAX
274 config ARCH_HAS_CACHE_LINE_SIZE
277 config ARCH_HAS_FILTER_PGPROT
280 config HAVE_SETUP_PER_CPU_AREA
283 config NEED_PER_CPU_EMBED_FIRST_CHUNK
286 config NEED_PER_CPU_PAGE_FIRST_CHUNK
289 config ARCH_HIBERNATION_POSSIBLE
292 config ARCH_SUSPEND_POSSIBLE
295 config ARCH_WANT_HUGE_PMD_SHARE
298 config ARCH_WANT_GENERAL_HUGETLB
307 config ARCH_SUPPORTS_OPTIMIZED_INLINING
310 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
313 config KASAN_SHADOW_OFFSET
316 default 0xdffffc0000000000
318 config HAVE_INTEL_TXT
320 depends on INTEL_IOMMU && ACPI
324 depends on X86_32 && SMP
328 depends on X86_64 && SMP
330 config X86_32_LAZY_GS
332 depends on X86_32 && !STACKPROTECTOR
334 config ARCH_SUPPORTS_UPROBES
337 config FIX_EARLYCON_MEM
340 config DYNAMIC_PHYSICAL_MASK
343 config PGTABLE_LEVELS
345 default 5 if X86_5LEVEL
350 source "init/Kconfig"
352 config CC_HAS_SANE_STACKPROTECTOR
354 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
355 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
357 We have to make sure stack protector is unconditionally disabled if
358 the compiler produces broken code.
360 source "kernel/Kconfig.freezer"
362 menu "Processor type and features"
365 bool "DMA memory allocation support" if EXPERT
368 DMA memory allocation support allows devices with less than 32-bit
369 addressing to allocate within the first 16MB of address space.
370 Disable if no such devices will be used.
375 bool "Symmetric multi-processing support"
377 This enables support for systems with more than one CPU. If you have
378 a system with only one CPU, say N. If you have a system with more
381 If you say N here, the kernel will run on uni- and multiprocessor
382 machines, but will use only one CPU of a multiprocessor machine. If
383 you say Y here, the kernel will run on many, but not all,
384 uniprocessor machines. On a uniprocessor machine, the kernel
385 will run faster if you say N here.
387 Note that if you say Y here and choose architecture "586" or
388 "Pentium" under "Processor family", the kernel will not work on 486
389 architectures. Similarly, multiprocessor kernels for the "PPro"
390 architecture may not work on all Pentium based boards.
392 People using multiprocessor machines who say Y here should also say
393 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
394 Management" code will be disabled if you say Y here.
396 See also <file:Documentation/x86/i386/IO-APIC.txt>,
397 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
398 <http://www.tldp.org/docs.html#howto>.
400 If you don't know what to do here, say N.
402 config X86_FEATURE_NAMES
403 bool "Processor feature human-readable names" if EMBEDDED
406 This option compiles in a table of x86 feature bits and corresponding
407 names. This is required to support /proc/cpuinfo and a few kernel
408 messages. You can disable this to save space, at the expense of
409 making those few kernel messages show numeric feature bits instead.
414 bool "Support x2apic"
415 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
417 This enables x2apic support on CPUs that have this feature.
419 This allows 32-bit apic IDs (so it can support very large systems),
420 and accesses the local apic via MSRs not via mmio.
422 If you don't know what to do here, say N.
425 bool "Enable MPS table" if ACPI || SFI
427 depends on X86_LOCAL_APIC
429 For old smp systems that do not have proper acpi support. Newer systems
430 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
434 depends on X86_GOLDFISH
437 bool "Avoid speculative indirect branches in kernel"
439 select STACK_VALIDATION if HAVE_STACK_VALIDATION
441 Compile kernel with the retpoline compiler options to guard against
442 kernel-to-user data leaks by avoiding speculative indirect
443 branches. Requires a compiler with -mindirect-branch=thunk-extern
444 support for full protection. The kernel may run slower.
446 Without compiler support, at least indirect branches in assembler
447 code are eliminated. Since this includes the syscall entry path,
448 it is not entirely pointless.
451 bool "Intel Resource Director Technology support"
453 depends on X86 && CPU_SUP_INTEL
456 Select to enable resource allocation and monitoring which are
457 sub-features of Intel Resource Director Technology(RDT). More
458 information about RDT can be found in the Intel x86
459 Architecture Software Developer Manual.
465 bool "Support for big SMP systems with more than 8 CPUs"
468 This option is needed for the systems that have more than 8 CPUs
470 config X86_EXTENDED_PLATFORM
471 bool "Support for extended (non-PC) x86 platforms"
474 If you disable this option then the kernel will only support
475 standard PC platforms. (which covers the vast majority of
478 If you enable this option then you'll be able to select support
479 for the following (non-PC) 32 bit x86 platforms:
480 Goldfish (Android emulator)
483 SGI 320/540 (Visual Workstation)
484 STA2X11-based (e.g. Northville)
485 Moorestown MID devices
487 If you have one of these systems, or if you want to build a
488 generic distribution kernel, say Y here - otherwise say N.
492 config X86_EXTENDED_PLATFORM
493 bool "Support for extended (non-PC) x86 platforms"
496 If you disable this option then the kernel will only support
497 standard PC platforms. (which covers the vast majority of
500 If you enable this option then you'll be able to select support
501 for the following (non-PC) 64 bit x86 platforms:
506 If you have one of these systems, or if you want to build a
507 generic distribution kernel, say Y here - otherwise say N.
509 # This is an alphabetically sorted list of 64 bit extended platforms
510 # Please maintain the alphabetic order if and when there are additions
512 bool "Numascale NumaChip"
514 depends on X86_EXTENDED_PLATFORM
517 depends on X86_X2APIC
518 depends on PCI_MMCONFIG
520 Adds support for Numascale NumaChip large-SMP systems. Needed to
521 enable more than ~168 cores.
522 If you don't have one of these, you should say N here.
526 select HYPERVISOR_GUEST
528 depends on X86_64 && PCI
529 depends on X86_EXTENDED_PLATFORM
532 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
533 supposed to run on these EM64T-based machines. Only choose this option
534 if you have one of these machines.
537 bool "SGI Ultraviolet"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
545 This option is needed in order to support SGI Ultraviolet systems.
546 If you don't have one of these, you should say N here.
548 # Following is an alphabetically sorted list of 32 bit extended platforms
549 # Please maintain the alphabetic order if and when there are additions
552 bool "Goldfish (Virtual Platform)"
553 depends on X86_EXTENDED_PLATFORM
555 Enable support for the Goldfish virtual platform used primarily
556 for Android development. Unless you are building for the Android
557 Goldfish emulator say N here.
560 bool "CE4100 TV platform"
562 depends on PCI_GODIRECT
563 depends on X86_IO_APIC
565 depends on X86_EXTENDED_PLATFORM
566 select X86_REBOOTFIXUPS
568 select OF_EARLY_FLATTREE
570 Select for the Intel CE media processor (CE4100) SOC.
571 This option compiles in support for the CE4100 SOC for settop
572 boxes and media devices.
575 bool "Intel MID platform support"
576 depends on X86_EXTENDED_PLATFORM
577 depends on X86_PLATFORM_DEVICES
579 depends on X86_64 || (PCI_GOANY && X86_32)
580 depends on X86_IO_APIC
586 select MFD_INTEL_MSIC
588 Select to build a kernel capable of supporting Intel MID (Mobile
589 Internet Device) platform systems which do not have the PCI legacy
590 interfaces. If you are building for a PC class system say N here.
592 Intel MID platforms are based on an Intel processor and chipset which
593 consume less power than most of the x86 derivatives.
595 config X86_INTEL_QUARK
596 bool "Intel Quark platform support"
598 depends on X86_EXTENDED_PLATFORM
599 depends on X86_PLATFORM_DEVICES
603 depends on X86_IO_APIC
608 Select to include support for Quark X1000 SoC.
609 Say Y here if you have a Quark based system such as the Arduino
610 compatible Intel Galileo.
612 config X86_INTEL_LPSS
613 bool "Intel Low Power Subsystem Support"
614 depends on X86 && ACPI
619 Select to build support for Intel Low Power Subsystem such as
620 found on Intel Lynxpoint PCH. Selecting this option enables
621 things like clock tree (common clock framework) and pincontrol
622 which are needed by the LPSS peripheral drivers.
624 config X86_AMD_PLATFORM_DEVICE
625 bool "AMD ACPI2Platform devices support"
630 Select to interpret AMD specific ACPI device to platform device
631 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
632 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
633 implemented under PINCTRL subsystem.
636 tristate "Intel SoC IOSF Sideband support for SoC platforms"
639 This option enables sideband register access support for Intel SoC
640 platforms. On these platforms the IOSF sideband is used in lieu of
641 MSR's for some register accesses, mostly but not limited to thermal
642 and power. Drivers may query the availability of this device to
643 determine if they need the sideband in order to work on these
644 platforms. The sideband is available on the following SoC products.
645 This list is not meant to be exclusive.
650 You should say Y if you are running a kernel on one of these SoC's.
652 config IOSF_MBI_DEBUG
653 bool "Enable IOSF sideband access through debugfs"
654 depends on IOSF_MBI && DEBUG_FS
656 Select this option to expose the IOSF sideband access registers (MCR,
657 MDR, MCRX) through debugfs to write and read register information from
658 different units on the SoC. This is most useful for obtaining device
659 state information for debug and analysis. As this is a general access
660 mechanism, users of this option would have specific knowledge of the
661 device they want to access.
663 If you don't require the option or are in doubt, say N.
666 bool "RDC R-321x SoC"
668 depends on X86_EXTENDED_PLATFORM
670 select X86_REBOOTFIXUPS
672 This option is needed for RDC R-321x system-on-chip, also known
674 If you don't have one of these chips, you should say N here.
676 config X86_32_NON_STANDARD
677 bool "Support non-standard 32-bit SMP architectures"
678 depends on X86_32 && SMP
679 depends on X86_EXTENDED_PLATFORM
681 This option compiles in the bigsmp and STA2X11 default
682 subarchitectures. It is intended for a generic binary
683 kernel. If you select them all, kernel will probe it one by
684 one and will fallback to default.
686 # Alphabetically sorted list of Non standard 32 bit platforms
688 config X86_SUPPORTS_MEMORY_FAILURE
690 # MCE code calls memory_failure():
692 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
693 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
694 depends on X86_64 || !SPARSEMEM
695 select ARCH_SUPPORTS_MEMORY_FAILURE
698 bool "STA2X11 Companion Chip Support"
699 depends on X86_32_NON_STANDARD && PCI
700 select ARCH_HAS_PHYS_TO_DMA
701 select X86_DEV_DMA_OPS
708 This adds support for boards based on the STA2X11 IO-Hub,
709 a.k.a. "ConneXt". The chip is used in place of the standard
710 PC chipset, so all "standard" peripherals are missing. If this
711 option is selected the kernel will still be able to boot on
712 standard PC machines.
715 tristate "Eurobraille/Iris poweroff module"
718 The Iris machines from EuroBraille do not have APM or ACPI support
719 to shut themselves down properly. A special I/O sequence is
720 needed to do so, which is what this module does at
723 This is only for Iris machines from EuroBraille.
727 config SCHED_OMIT_FRAME_POINTER
729 prompt "Single-depth WCHAN output"
732 Calculate simpler /proc/<PID>/wchan values. If this option
733 is disabled then wchan values will recurse back to the
734 caller function. This provides more accurate wchan values,
735 at the expense of slightly more scheduling overhead.
737 If in doubt, say "Y".
739 menuconfig HYPERVISOR_GUEST
740 bool "Linux guest support"
742 Say Y here to enable options for running Linux under various hyper-
743 visors. This option enables basic hypervisor detection and platform
746 If you say N, all options in this submenu will be skipped and
747 disabled, and Linux guest support won't be built in.
752 bool "Enable paravirtualization code"
754 This changes the kernel so it can modify itself when it is run
755 under a hypervisor, potentially improving performance significantly
756 over full virtualization. However, when run without a hypervisor
757 the kernel is theoretically slower and slightly larger.
759 config PARAVIRT_DEBUG
760 bool "paravirt-ops debugging"
761 depends on PARAVIRT && DEBUG_KERNEL
763 Enable to debug paravirt_ops internals. Specifically, BUG if
764 a paravirt_op is missing when it is called.
766 config PARAVIRT_SPINLOCKS
767 bool "Paravirtualization layer for spinlocks"
768 depends on PARAVIRT && SMP
770 Paravirtualized spinlocks allow a pvops backend to replace the
771 spinlock implementation with something virtualization-friendly
772 (for example, block the virtual CPU rather than spinning).
774 It has a minimal impact on native kernels and gives a nice performance
775 benefit on paravirtualized KVM / Xen kernels.
777 If you are unsure how to answer this question, answer Y.
779 config QUEUED_LOCK_STAT
780 bool "Paravirt queued spinlock statistics"
781 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
783 Enable the collection of statistical data on the slowpath
784 behavior of paravirtualized queued spinlocks and report
787 source "arch/x86/xen/Kconfig"
790 bool "KVM Guest support (including kvmclock)"
792 select PARAVIRT_CLOCK
795 This option enables various optimizations for running under the KVM
796 hypervisor. It includes a paravirtualized clock, so that instead
797 of relying on a PIT (or probably other) emulation by the
798 underlying device model, the host provides the guest with
799 timing infrastructure such as time of day, and system time
802 bool "Enable debug information for KVM Guests in debugfs"
803 depends on KVM_GUEST && DEBUG_FS
806 This option enables collection of various statistics for KVM guest.
807 Statistics are displayed in debugfs filesystem. Enabling this option
808 may incur significant overhead.
810 config PARAVIRT_TIME_ACCOUNTING
811 bool "Paravirtual steal time accounting"
815 Select this option to enable fine granularity task steal time
816 accounting. Time spent executing other tasks in parallel with
817 the current vCPU is discounted from the vCPU power. To account for
818 that, there can be a small performance impact.
820 If in doubt, say N here.
822 config PARAVIRT_CLOCK
825 config JAILHOUSE_GUEST
826 bool "Jailhouse non-root cell support"
827 depends on X86_64 && PCI
830 This option allows to run Linux as guest in a Jailhouse non-root
831 cell. You can leave this option disabled if you only want to start
832 Jailhouse and run Linux afterwards in the root cell.
834 endif #HYPERVISOR_GUEST
839 source "arch/x86/Kconfig.cpu"
843 prompt "HPET Timer Support" if X86_32
845 Use the IA-PC HPET (High Precision Event Timer) to manage
846 time in preference to the PIT and RTC, if a HPET is
848 HPET is the next generation timer replacing legacy 8254s.
849 The HPET provides a stable time base on SMP
850 systems, unlike the TSC, but it is more expensive to access,
851 as it is off-chip. The interface used is documented
852 in the HPET spec, revision 1.
854 You can safely choose Y here. However, HPET will only be
855 activated if the platform and the BIOS support this feature.
856 Otherwise the 8254 will be used for timing services.
858 Choose N to continue using the legacy 8254 timer.
860 config HPET_EMULATE_RTC
862 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
865 def_bool y if X86_INTEL_MID
866 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
868 depends on X86_INTEL_MID && SFI
870 APB timer is the replacement for 8254, HPET on X86 MID platforms.
871 The APBT provides a stable time base on SMP
872 systems, unlike the TSC, but it is more expensive to access,
873 as it is off-chip. APB timers are always running regardless of CPU
874 C states, they are used as per CPU clockevent device when possible.
876 # Mark as expert because too many people got it wrong.
877 # The code disables itself when not needed.
880 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
881 bool "Enable DMI scanning" if EXPERT
883 Enabled scanning of DMI to identify machine quirks. Say Y
884 here unless you have verified that your setup is not
885 affected by entries in the DMI blacklist. Required by PNP
889 bool "Old AMD GART IOMMU support"
892 depends on X86_64 && PCI && AMD_NB
894 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
895 GART based hardware IOMMUs.
897 The GART supports full DMA access for devices with 32-bit access
898 limitations, on systems with more than 3 GB. This is usually needed
899 for USB, sound, many IDE/SATA chipsets and some other devices.
901 Newer systems typically have a modern AMD IOMMU, supported via
902 the CONFIG_AMD_IOMMU=y config option.
904 In normal configurations this driver is only active when needed:
905 there's more than 3 GB of memory and the system contains a
906 32-bit limited device.
911 bool "IBM Calgary IOMMU support"
914 depends on X86_64 && PCI
916 Support for hardware IOMMUs in IBM's xSeries x366 and x460
917 systems. Needed to run systems with more than 3GB of memory
918 properly with 32-bit PCI devices that do not support DAC
919 (Double Address Cycle). Calgary also supports bus level
920 isolation, where all DMAs pass through the IOMMU. This
921 prevents them from going anywhere except their intended
922 destination. This catches hard-to-find kernel bugs and
923 mis-behaving drivers and devices that do not use the DMA-API
924 properly to set up their DMA buffers. The IOMMU can be
925 turned off at boot time with the iommu=off parameter.
926 Normally the kernel will make the right choice by itself.
929 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
931 prompt "Should Calgary be enabled by default?"
932 depends on CALGARY_IOMMU
934 Should Calgary be enabled by default? if you choose 'y', Calgary
935 will be used (if it exists). If you choose 'n', Calgary will not be
936 used even if it exists. If you choose 'n' and would like to use
937 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
941 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
942 depends on X86_64 && SMP && DEBUG_KERNEL
943 select CPUMASK_OFFSTACK
945 Enable maximum number of CPUS and NUMA Nodes for this architecture.
949 # The maximum number of CPUs supported:
951 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
952 # and which can be configured interactively in the
953 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
955 # The ranges are different on 32-bit and 64-bit kernels, depending on
956 # hardware capabilities and scalability features of the kernel.
958 # ( If MAXSMP is enabled we just use the highest possible value and disable
959 # interactive configuration. )
962 config NR_CPUS_RANGE_BEGIN
964 default NR_CPUS_RANGE_END if MAXSMP
968 config NR_CPUS_RANGE_END
971 default 64 if SMP && X86_BIGSMP
972 default 8 if SMP && !X86_BIGSMP
975 config NR_CPUS_RANGE_END
978 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
979 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
982 config NR_CPUS_DEFAULT
985 default 32 if X86_BIGSMP
989 config NR_CPUS_DEFAULT
992 default 8192 if MAXSMP
997 int "Maximum number of CPUs" if SMP && !MAXSMP
998 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
999 default NR_CPUS_DEFAULT
1001 This allows you to specify the maximum number of CPUs which this
1002 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1003 supported value is 8192, otherwise the maximum value is 512. The
1004 minimum value which makes sense is 2.
1006 This is purely to save memory: each supported CPU adds about 8KB
1007 to the kernel image.
1010 bool "SMT (Hyperthreading) scheduler support"
1013 SMT scheduler support improves the CPU scheduler's decision making
1014 when dealing with Intel Pentium 4 chips with HyperThreading at a
1015 cost of slightly increased overhead in some places. If unsure say
1020 prompt "Multi-core scheduler support"
1023 Multi-core scheduler support improves the CPU scheduler's decision
1024 making when dealing with multi-core CPU chips at a cost of slightly
1025 increased overhead in some places. If unsure say N here.
1027 config SCHED_MC_PRIO
1028 bool "CPU core priorities scheduler support"
1029 depends on SCHED_MC && CPU_SUP_INTEL
1030 select X86_INTEL_PSTATE
1034 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1035 core ordering determined at manufacturing time, which allows
1036 certain cores to reach higher turbo frequencies (when running
1037 single threaded workloads) than others.
1039 Enabling this kernel feature teaches the scheduler about
1040 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1041 scheduler's CPU selection logic accordingly, so that higher
1042 overall system performance can be achieved.
1044 This feature will have no effect on CPUs without this feature.
1046 If unsure say Y here.
1048 source "kernel/Kconfig.preempt"
1052 depends on !SMP && X86_LOCAL_APIC
1055 bool "Local APIC support on uniprocessors" if !PCI_MSI
1057 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1059 A local APIC (Advanced Programmable Interrupt Controller) is an
1060 integrated interrupt controller in the CPU. If you have a single-CPU
1061 system which has a processor with a local APIC, you can say Y here to
1062 enable and use it. If you say Y here even though your machine doesn't
1063 have a local APIC, then the kernel will still run with no slowdown at
1064 all. The local APIC supports CPU-generated self-interrupts (timer,
1065 performance counters), and the NMI watchdog which detects hard
1068 config X86_UP_IOAPIC
1069 bool "IO-APIC support on uniprocessors"
1070 depends on X86_UP_APIC
1072 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1073 SMP-capable replacement for PC-style interrupt controllers. Most
1074 SMP systems and many recent uniprocessor systems have one.
1076 If you have a single-CPU system with an IO-APIC, you can say Y here
1077 to use it. If you say Y here even though your machine doesn't have
1078 an IO-APIC, then the kernel will still run with no slowdown at all.
1080 config X86_LOCAL_APIC
1082 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1083 select IRQ_DOMAIN_HIERARCHY
1084 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1088 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1090 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1091 bool "Reroute for broken boot IRQs"
1092 depends on X86_IO_APIC
1094 This option enables a workaround that fixes a source of
1095 spurious interrupts. This is recommended when threaded
1096 interrupt handling is used on systems where the generation of
1097 superfluous "boot interrupts" cannot be disabled.
1099 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1100 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1101 kernel does during interrupt handling). On chipsets where this
1102 boot IRQ generation cannot be disabled, this workaround keeps
1103 the original IRQ line masked so that only the equivalent "boot
1104 IRQ" is delivered to the CPUs. The workaround also tells the
1105 kernel to set up the IRQ handler on the boot IRQ line. In this
1106 way only one interrupt is delivered to the kernel. Otherwise
1107 the spurious second interrupt may cause the kernel to bring
1108 down (vital) interrupt lines.
1110 Only affects "broken" chipsets. Interrupt sharing may be
1111 increased on these systems.
1114 bool "Machine Check / overheating reporting"
1115 select GENERIC_ALLOCATOR
1118 Machine Check support allows the processor to notify the
1119 kernel if it detects a problem (e.g. overheating, data corruption).
1120 The action the kernel takes depends on the severity of the problem,
1121 ranging from warning messages to halting the machine.
1123 config X86_MCELOG_LEGACY
1124 bool "Support for deprecated /dev/mcelog character device"
1127 Enable support for /dev/mcelog which is needed by the old mcelog
1128 userspace logging daemon. Consider switching to the new generation
1131 config X86_MCE_INTEL
1133 prompt "Intel MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC
1136 Additional support for intel specific MCE features such as
1137 the thermal monitor.
1141 prompt "AMD MCE features"
1142 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1144 Additional support for AMD specific MCE features such as
1145 the DRAM Error Threshold.
1147 config X86_ANCIENT_MCE
1148 bool "Support for old Pentium 5 / WinChip machine checks"
1149 depends on X86_32 && X86_MCE
1151 Include support for machine check handling on old Pentium 5 or WinChip
1152 systems. These typically need to be enabled explicitly on the command
1155 config X86_MCE_THRESHOLD
1156 depends on X86_MCE_AMD || X86_MCE_INTEL
1159 config X86_MCE_INJECT
1160 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1161 tristate "Machine check injector support"
1163 Provide support for injecting machine checks for testing purposes.
1164 If you don't know what a machine check is and you don't do kernel
1165 QA it is safe to say n.
1167 config X86_THERMAL_VECTOR
1169 depends on X86_MCE_INTEL
1171 source "arch/x86/events/Kconfig"
1173 config X86_LEGACY_VM86
1174 bool "Legacy VM86 support"
1178 This option allows user programs to put the CPU into V8086
1179 mode, which is an 80286-era approximation of 16-bit real mode.
1181 Some very old versions of X and/or vbetool require this option
1182 for user mode setting. Similarly, DOSEMU will use it if
1183 available to accelerate real mode DOS programs. However, any
1184 recent version of DOSEMU, X, or vbetool should be fully
1185 functional even without kernel VM86 support, as they will all
1186 fall back to software emulation. Nevertheless, if you are using
1187 a 16-bit DOS program where 16-bit performance matters, vm86
1188 mode might be faster than emulation and you might want to
1191 Note that any app that works on a 64-bit kernel is unlikely to
1192 need this option, as 64-bit kernels don't, and can't, support
1193 V8086 mode. This option is also unrelated to 16-bit protected
1194 mode and is not needed to run most 16-bit programs under Wine.
1196 Enabling this option increases the complexity of the kernel
1197 and slows down exception handling a tiny bit.
1199 If unsure, say N here.
1203 default X86_LEGACY_VM86
1206 bool "Enable support for 16-bit segments" if EXPERT
1208 depends on MODIFY_LDT_SYSCALL
1210 This option is required by programs like Wine to run 16-bit
1211 protected mode legacy code on x86 processors. Disabling
1212 this option saves about 300 bytes on i386, or around 6K text
1213 plus 16K runtime memory on x86-64,
1217 depends on X86_16BIT && X86_32
1221 depends on X86_16BIT && X86_64
1223 config X86_VSYSCALL_EMULATION
1224 bool "Enable vsyscall emulation" if EXPERT
1228 This enables emulation of the legacy vsyscall page. Disabling
1229 it is roughly equivalent to booting with vsyscall=none, except
1230 that it will also disable the helpful warning if a program
1231 tries to use a vsyscall. With this option set to N, offending
1232 programs will just segfault, citing addresses of the form
1235 This option is required by many programs built before 2013, and
1236 care should be used even with newer programs if set to N.
1238 Disabling this option saves about 7K of kernel size and
1239 possibly 4K of additional runtime pagetable memory.
1242 tristate "Toshiba Laptop support"
1245 This adds a driver to safely access the System Management Mode of
1246 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1247 not work on models with a Phoenix BIOS. The System Management Mode
1248 is used to set the BIOS and power saving options on Toshiba portables.
1250 For information on utilities to make use of this driver see the
1251 Toshiba Linux utilities web site at:
1252 <http://www.buzzard.org.uk/toshiba/>.
1254 Say Y if you intend to run this kernel on a Toshiba portable.
1258 tristate "Dell i8k legacy laptop support"
1260 select SENSORS_DELL_SMM
1262 This option enables legacy /proc/i8k userspace interface in hwmon
1263 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1264 temperature and allows controlling fan speeds of Dell laptops via
1265 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1266 it reports also power and hotkey status. For fan speed control is
1267 needed userspace package i8kutils.
1269 Say Y if you intend to run this kernel on old Dell laptops or want to
1270 use userspace package i8kutils.
1273 config X86_REBOOTFIXUPS
1274 bool "Enable X86 board specific fixups for reboot"
1277 This enables chipset and/or board specific fixups to be done
1278 in order to get reboot to work correctly. This is only needed on
1279 some combinations of hardware and BIOS. The symptom, for which
1280 this config is intended, is when reboot ends with a stalled/hung
1283 Currently, the only fixup is for the Geode machines using
1284 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1286 Say Y if you want to enable the fixup. Currently, it's safe to
1287 enable this option even if you don't need it.
1291 bool "CPU microcode loading support"
1293 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1296 If you say Y here, you will be able to update the microcode on
1297 Intel and AMD processors. The Intel support is for the IA32 family,
1298 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1299 AMD support is for families 0x10 and later. You will obviously need
1300 the actual microcode binary data itself which is not shipped with
1303 The preferred method to load microcode from a detached initrd is described
1304 in Documentation/x86/microcode.txt. For that you need to enable
1305 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1306 initrd for microcode blobs.
1308 In addition, you can build the microcode into the kernel. For that you
1309 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1312 config MICROCODE_INTEL
1313 bool "Intel microcode loading support"
1314 depends on MICROCODE
1318 This options enables microcode patch loading support for Intel
1321 For the current Intel microcode data package go to
1322 <https://downloadcenter.intel.com> and search for
1323 'Linux Processor Microcode Data File'.
1325 config MICROCODE_AMD
1326 bool "AMD microcode loading support"
1327 depends on MICROCODE
1330 If you select this option, microcode patch loading support for AMD
1331 processors will be enabled.
1333 config MICROCODE_OLD_INTERFACE
1335 depends on MICROCODE
1338 tristate "/dev/cpu/*/msr - Model-specific register support"
1340 This device gives privileged processes access to the x86
1341 Model-Specific Registers (MSRs). It is a character device with
1342 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1343 MSR accesses are directed to a specific CPU on multi-processor
1347 tristate "/dev/cpu/*/cpuid - CPU information support"
1349 This device gives processes access to the x86 CPUID instruction to
1350 be executed on a specific processor. It is a character device
1351 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1355 prompt "High Memory Support"
1362 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1363 However, the address space of 32-bit x86 processors is only 4
1364 Gigabytes large. That means that, if you have a large amount of
1365 physical memory, not all of it can be "permanently mapped" by the
1366 kernel. The physical memory that's not permanently mapped is called
1369 If you are compiling a kernel which will never run on a machine with
1370 more than 1 Gigabyte total physical RAM, answer "off" here (default
1371 choice and suitable for most users). This will result in a "3GB/1GB"
1372 split: 3GB are mapped so that each process sees a 3GB virtual memory
1373 space and the remaining part of the 4GB virtual memory space is used
1374 by the kernel to permanently map as much physical memory as
1377 If the machine has between 1 and 4 Gigabytes physical RAM, then
1380 If more than 4 Gigabytes is used then answer "64GB" here. This
1381 selection turns Intel PAE (Physical Address Extension) mode on.
1382 PAE implements 3-level paging on IA32 processors. PAE is fully
1383 supported by Linux, PAE mode is implemented on all recent Intel
1384 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1385 then the kernel will not boot on CPUs that don't support PAE!
1387 The actual amount of total physical memory will either be
1388 auto detected or can be forced by using a kernel command line option
1389 such as "mem=256M". (Try "man bootparam" or see the documentation of
1390 your boot loader (lilo or loadlin) about how to pass options to the
1391 kernel at boot time.)
1393 If unsure, say "off".
1398 Select this if you have a 32-bit processor and between 1 and 4
1399 gigabytes of physical RAM.
1403 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1406 Select this if you have a 32-bit processor and more than 4
1407 gigabytes of physical RAM.
1412 prompt "Memory split" if EXPERT
1416 Select the desired split between kernel and user memory.
1418 If the address range available to the kernel is less than the
1419 physical memory installed, the remaining memory will be available
1420 as "high memory". Accessing high memory is a little more costly
1421 than low memory, as it needs to be mapped into the kernel first.
1422 Note that increasing the kernel address space limits the range
1423 available to user programs, making the address space there
1424 tighter. Selecting anything other than the default 3G/1G split
1425 will also likely make your kernel incompatible with binary-only
1428 If you are not absolutely sure what you are doing, leave this
1432 bool "3G/1G user/kernel split"
1433 config VMSPLIT_3G_OPT
1435 bool "3G/1G user/kernel split (for full 1G low memory)"
1437 bool "2G/2G user/kernel split"
1438 config VMSPLIT_2G_OPT
1440 bool "2G/2G user/kernel split (for full 2G low memory)"
1442 bool "1G/3G user/kernel split"
1447 default 0xB0000000 if VMSPLIT_3G_OPT
1448 default 0x80000000 if VMSPLIT_2G
1449 default 0x78000000 if VMSPLIT_2G_OPT
1450 default 0x40000000 if VMSPLIT_1G
1456 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1459 bool "PAE (Physical Address Extension) Support"
1460 depends on X86_32 && !HIGHMEM4G
1461 select PHYS_ADDR_T_64BIT
1464 PAE is required for NX support, and furthermore enables
1465 larger swapspace support for non-overcommit purposes. It
1466 has the cost of more pagetable lookup overhead, and also
1467 consumes more pagetable space per process.
1470 bool "Enable 5-level page tables support"
1471 select DYNAMIC_MEMORY_LAYOUT
1472 select SPARSEMEM_VMEMMAP
1475 5-level paging enables access to larger address space:
1476 upto 128 PiB of virtual address space and 4 PiB of
1477 physical address space.
1479 It will be supported by future Intel CPUs.
1481 A kernel with the option enabled can be booted on machines that
1482 support 4- or 5-level paging.
1484 See Documentation/x86/x86_64/5level-paging.txt for more
1489 config X86_DIRECT_GBPAGES
1491 depends on X86_64 && !DEBUG_PAGEALLOC
1493 Certain kernel features effectively disable kernel
1494 linear 1 GB mappings (even if the CPU otherwise
1495 supports them), so don't confuse the user by printing
1496 that we have them enabled.
1498 config ARCH_HAS_MEM_ENCRYPT
1501 config AMD_MEM_ENCRYPT
1502 bool "AMD Secure Memory Encryption (SME) support"
1503 depends on X86_64 && CPU_SUP_AMD
1504 select DYNAMIC_PHYSICAL_MASK
1506 Say yes to enable support for the encryption of system memory.
1507 This requires an AMD processor that supports Secure Memory
1510 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1511 bool "Activate AMD Secure Memory Encryption (SME) by default"
1513 depends on AMD_MEM_ENCRYPT
1515 Say yes to have system memory encrypted by default if running on
1516 an AMD processor that supports Secure Memory Encryption (SME).
1518 If set to Y, then the encryption of system memory can be
1519 deactivated with the mem_encrypt=off command line option.
1521 If set to N, then the encryption of system memory can be
1522 activated with the mem_encrypt=on command line option.
1524 config ARCH_USE_MEMREMAP_PROT
1526 depends on AMD_MEM_ENCRYPT
1528 # Common NUMA Features
1530 bool "Numa Memory Allocation and Scheduler Support"
1532 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1533 default y if X86_BIGSMP
1535 Enable NUMA (Non Uniform Memory Access) support.
1537 The kernel will try to allocate memory used by a CPU on the
1538 local memory controller of the CPU and add some more
1539 NUMA awareness to the kernel.
1541 For 64-bit this is recommended if the system is Intel Core i7
1542 (or later), AMD Opteron, or EM64T NUMA.
1544 For 32-bit this is only needed if you boot a 32-bit
1545 kernel on a 64-bit NUMA platform.
1547 Otherwise, you should say N.
1551 prompt "Old style AMD Opteron NUMA detection"
1552 depends on X86_64 && NUMA && PCI
1554 Enable AMD NUMA node topology detection. You should say Y here if
1555 you have a multi processor AMD system. This uses an old method to
1556 read the NUMA configuration directly from the builtin Northbridge
1557 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1558 which also takes priority if both are compiled in.
1560 config X86_64_ACPI_NUMA
1562 prompt "ACPI NUMA detection"
1563 depends on X86_64 && NUMA && ACPI && PCI
1566 Enable ACPI SRAT based node topology detection.
1568 # Some NUMA nodes have memory ranges that span
1569 # other nodes. Even though a pfn is valid and
1570 # between a node's start and end pfns, it may not
1571 # reside on that node. See memmap_init_zone()
1573 config NODES_SPAN_OTHER_NODES
1575 depends on X86_64_ACPI_NUMA
1578 bool "NUMA emulation"
1581 Enable NUMA emulation. A flat machine will be split
1582 into virtual nodes when booted with "numa=fake=N", where N is the
1583 number of nodes. This is only useful for debugging.
1586 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1588 default "10" if MAXSMP
1589 default "6" if X86_64
1591 depends on NEED_MULTIPLE_NODES
1593 Specify the maximum number of NUMA Nodes available on the target
1594 system. Increases memory reserved to accommodate various tables.
1596 config ARCH_HAVE_MEMORY_PRESENT
1598 depends on X86_32 && DISCONTIGMEM
1600 config ARCH_FLATMEM_ENABLE
1602 depends on X86_32 && !NUMA
1604 config ARCH_DISCONTIGMEM_ENABLE
1606 depends on NUMA && X86_32
1608 config ARCH_DISCONTIGMEM_DEFAULT
1610 depends on NUMA && X86_32
1612 config ARCH_SPARSEMEM_ENABLE
1614 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1615 select SPARSEMEM_STATIC if X86_32
1616 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1618 config ARCH_SPARSEMEM_DEFAULT
1622 config ARCH_SELECT_MEMORY_MODEL
1624 depends on ARCH_SPARSEMEM_ENABLE
1626 config ARCH_MEMORY_PROBE
1627 bool "Enable sysfs memory/probe interface"
1628 depends on X86_64 && MEMORY_HOTPLUG
1630 This option enables a sysfs memory/probe interface for testing.
1631 See Documentation/memory-hotplug.txt for more information.
1632 If you are unsure how to answer this question, answer N.
1634 config ARCH_PROC_KCORE_TEXT
1636 depends on X86_64 && PROC_KCORE
1638 config ILLEGAL_POINTER_VALUE
1641 default 0xdead000000000000 if X86_64
1645 config X86_PMEM_LEGACY_DEVICE
1648 config X86_PMEM_LEGACY
1649 tristate "Support non-standard NVDIMMs and ADR protected memory"
1650 depends on PHYS_ADDR_T_64BIT
1652 select X86_PMEM_LEGACY_DEVICE
1655 Treat memory marked using the non-standard e820 type of 12 as used
1656 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1657 The kernel will offer these regions to the 'pmem' driver so
1658 they can be used for persistent storage.
1663 bool "Allocate 3rd-level pagetables from highmem"
1666 The VM uses one page table entry for each page of physical memory.
1667 For systems with a lot of RAM, this can be wasteful of precious
1668 low memory. Setting this option will put user-space page table
1669 entries in high memory.
1671 config X86_CHECK_BIOS_CORRUPTION
1672 bool "Check for low memory corruption"
1674 Periodically check for memory corruption in low memory, which
1675 is suspected to be caused by BIOS. Even when enabled in the
1676 configuration, it is disabled at runtime. Enable it by
1677 setting "memory_corruption_check=1" on the kernel command
1678 line. By default it scans the low 64k of memory every 60
1679 seconds; see the memory_corruption_check_size and
1680 memory_corruption_check_period parameters in
1681 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1683 When enabled with the default parameters, this option has
1684 almost no overhead, as it reserves a relatively small amount
1685 of memory and scans it infrequently. It both detects corruption
1686 and prevents it from affecting the running system.
1688 It is, however, intended as a diagnostic tool; if repeatable
1689 BIOS-originated corruption always affects the same memory,
1690 you can use memmap= to prevent the kernel from using that
1693 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1694 bool "Set the default setting of memory_corruption_check"
1695 depends on X86_CHECK_BIOS_CORRUPTION
1698 Set whether the default state of memory_corruption_check is
1701 config X86_RESERVE_LOW
1702 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1706 Specify the amount of low memory to reserve for the BIOS.
1708 The first page contains BIOS data structures that the kernel
1709 must not use, so that page must always be reserved.
1711 By default we reserve the first 64K of physical RAM, as a
1712 number of BIOSes are known to corrupt that memory range
1713 during events such as suspend/resume or monitor cable
1714 insertion, so it must not be used by the kernel.
1716 You can set this to 4 if you are absolutely sure that you
1717 trust the BIOS to get all its memory reservations and usages
1718 right. If you know your BIOS have problems beyond the
1719 default 64K area, you can set this to 640 to avoid using the
1720 entire low memory range.
1722 If you have doubts about the BIOS (e.g. suspend/resume does
1723 not work or there's kernel crashes after certain hardware
1724 hotplug events) then you might want to enable
1725 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1726 typical corruption patterns.
1728 Leave this to the default value of 64 if you are unsure.
1730 config MATH_EMULATION
1732 depends on MODIFY_LDT_SYSCALL
1733 prompt "Math emulation" if X86_32
1735 Linux can emulate a math coprocessor (used for floating point
1736 operations) if you don't have one. 486DX and Pentium processors have
1737 a math coprocessor built in, 486SX and 386 do not, unless you added
1738 a 487DX or 387, respectively. (The messages during boot time can
1739 give you some hints here ["man dmesg"].) Everyone needs either a
1740 coprocessor or this emulation.
1742 If you don't have a math coprocessor, you need to say Y here; if you
1743 say Y here even though you have a coprocessor, the coprocessor will
1744 be used nevertheless. (This behavior can be changed with the kernel
1745 command line option "no387", which comes handy if your coprocessor
1746 is broken. Try "man bootparam" or see the documentation of your boot
1747 loader (lilo or loadlin) about how to pass options to the kernel at
1748 boot time.) This means that it is a good idea to say Y here if you
1749 intend to use this kernel on different machines.
1751 More information about the internals of the Linux math coprocessor
1752 emulation can be found in <file:arch/x86/math-emu/README>.
1754 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1755 kernel, it won't hurt.
1759 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1761 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1762 the Memory Type Range Registers (MTRRs) may be used to control
1763 processor access to memory ranges. This is most useful if you have
1764 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1765 allows bus write transfers to be combined into a larger transfer
1766 before bursting over the PCI/AGP bus. This can increase performance
1767 of image write operations 2.5 times or more. Saying Y here creates a
1768 /proc/mtrr file which may be used to manipulate your processor's
1769 MTRRs. Typically the X server should use this.
1771 This code has a reasonably generic interface so that similar
1772 control registers on other processors can be easily supported
1775 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1776 Registers (ARRs) which provide a similar functionality to MTRRs. For
1777 these, the ARRs are used to emulate the MTRRs.
1778 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1779 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1780 write-combining. All of these processors are supported by this code
1781 and it makes sense to say Y here if you have one of them.
1783 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1784 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1785 can lead to all sorts of problems, so it's good to say Y here.
1787 You can safely say Y even if your machine doesn't have MTRRs, you'll
1788 just add about 9 KB to your kernel.
1790 See <file:Documentation/x86/mtrr.txt> for more information.
1792 config MTRR_SANITIZER
1794 prompt "MTRR cleanup support"
1797 Convert MTRR layout from continuous to discrete, so X drivers can
1798 add writeback entries.
1800 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1801 The largest mtrr entry size for a continuous block can be set with
1806 config MTRR_SANITIZER_ENABLE_DEFAULT
1807 int "MTRR cleanup enable value (0-1)"
1810 depends on MTRR_SANITIZER
1812 Enable mtrr cleanup default value
1814 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1815 int "MTRR cleanup spare reg num (0-7)"
1818 depends on MTRR_SANITIZER
1820 mtrr cleanup spare entries default, it can be changed via
1821 mtrr_spare_reg_nr=N on the kernel command line.
1825 prompt "x86 PAT support" if EXPERT
1828 Use PAT attributes to setup page level cache control.
1830 PATs are the modern equivalents of MTRRs and are much more
1831 flexible than MTRRs.
1833 Say N here if you see bootup problems (boot crash, boot hang,
1834 spontaneous reboots) or a non-working video driver.
1838 config ARCH_USES_PG_UNCACHED
1844 prompt "x86 architectural random number generator" if EXPERT
1846 Enable the x86 architectural RDRAND instruction
1847 (Intel Bull Mountain technology) to generate random numbers.
1848 If supported, this is a high bandwidth, cryptographically
1849 secure hardware random number generator.
1853 prompt "Supervisor Mode Access Prevention" if EXPERT
1855 Supervisor Mode Access Prevention (SMAP) is a security
1856 feature in newer Intel processors. There is a small
1857 performance cost if this enabled and turned on; there is
1858 also a small increase in the kernel size if this is enabled.
1862 config X86_INTEL_UMIP
1864 depends on CPU_SUP_INTEL
1865 prompt "Intel User Mode Instruction Prevention" if EXPERT
1867 The User Mode Instruction Prevention (UMIP) is a security
1868 feature in newer Intel processors. If enabled, a general
1869 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1870 or STR instructions are executed in user mode. These instructions
1871 unnecessarily expose information about the hardware state.
1873 The vast majority of applications do not use these instructions.
1874 For the very few that do, software emulation is provided in
1875 specific cases in protected and virtual-8086 modes. Emulated
1878 config X86_INTEL_MPX
1879 prompt "Intel MPX (Memory Protection Extensions)"
1881 # Note: only available in 64-bit mode due to VMA flags shortage
1882 depends on CPU_SUP_INTEL && X86_64
1883 select ARCH_USES_HIGH_VMA_FLAGS
1885 MPX provides hardware features that can be used in
1886 conjunction with compiler-instrumented code to check
1887 memory references. It is designed to detect buffer
1888 overflow or underflow bugs.
1890 This option enables running applications which are
1891 instrumented or otherwise use MPX. It does not use MPX
1892 itself inside the kernel or to protect the kernel
1893 against bad memory references.
1895 Enabling this option will make the kernel larger:
1896 ~8k of kernel text and 36 bytes of data on a 64-bit
1897 defconfig. It adds a long to the 'mm_struct' which
1898 will increase the kernel memory overhead of each
1899 process and adds some branches to paths used during
1900 exec() and munmap().
1902 For details, see Documentation/x86/intel_mpx.txt
1906 config X86_INTEL_MEMORY_PROTECTION_KEYS
1907 prompt "Intel Memory Protection Keys"
1909 # Note: only available in 64-bit mode
1910 depends on CPU_SUP_INTEL && X86_64
1911 select ARCH_USES_HIGH_VMA_FLAGS
1912 select ARCH_HAS_PKEYS
1914 Memory Protection Keys provides a mechanism for enforcing
1915 page-based protections, but without requiring modification of the
1916 page tables when an application changes protection domains.
1918 For details, see Documentation/x86/protection-keys.txt
1923 bool "EFI runtime service support"
1926 select EFI_RUNTIME_WRAPPERS
1928 This enables the kernel to use EFI runtime services that are
1929 available (such as the EFI variable services).
1931 This option is only useful on systems that have EFI firmware.
1932 In addition, you should use the latest ELILO loader available
1933 at <http://elilo.sourceforge.net> in order to take advantage
1934 of EFI runtime services. However, even with this option, the
1935 resultant kernel should continue to boot on existing non-EFI
1939 bool "EFI stub support"
1940 depends on EFI && !X86_USE_3DNOW
1943 This kernel feature allows a bzImage to be loaded directly
1944 by EFI firmware without the use of a bootloader.
1946 See Documentation/efi-stub.txt for more information.
1949 bool "EFI mixed-mode support"
1950 depends on EFI_STUB && X86_64
1952 Enabling this feature allows a 64-bit kernel to be booted
1953 on a 32-bit firmware, provided that your CPU supports 64-bit
1956 Note that it is not possible to boot a mixed-mode enabled
1957 kernel via the EFI boot stub - a bootloader that supports
1958 the EFI handover protocol must be used.
1964 prompt "Enable seccomp to safely compute untrusted bytecode"
1966 This kernel feature is useful for number crunching applications
1967 that may need to compute untrusted bytecode during their
1968 execution. By using pipes or other transports made available to
1969 the process as file descriptors supporting the read/write
1970 syscalls, it's possible to isolate those applications in
1971 their own address space using seccomp. Once seccomp is
1972 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1973 and the task is only allowed to execute a few safe syscalls
1974 defined by each seccomp mode.
1976 If unsure, say Y. Only embedded should say N here.
1978 source kernel/Kconfig.hz
1981 bool "kexec system call"
1984 kexec is a system call that implements the ability to shutdown your
1985 current kernel, and to start another kernel. It is like a reboot
1986 but it is independent of the system firmware. And like a reboot
1987 you can start any kernel with it, not just Linux.
1989 The name comes from the similarity to the exec system call.
1991 It is an ongoing process to be certain the hardware in a machine
1992 is properly shutdown, so do not be surprised if this code does not
1993 initially work for you. As of this writing the exact hardware
1994 interface is strongly in flux, so no good recommendation can be
1998 bool "kexec file based system call"
2003 depends on CRYPTO_SHA256=y
2005 This is new version of kexec system call. This system call is
2006 file based and takes file descriptors as system call argument
2007 for kernel and initramfs as opposed to list of segments as
2008 accepted by previous system call.
2010 config ARCH_HAS_KEXEC_PURGATORY
2013 config KEXEC_VERIFY_SIG
2014 bool "Verify kernel signature during kexec_file_load() syscall"
2015 depends on KEXEC_FILE
2017 This option makes kernel signature verification mandatory for
2018 the kexec_file_load() syscall.
2020 In addition to that option, you need to enable signature
2021 verification for the corresponding kernel image type being
2022 loaded in order for this to work.
2024 config KEXEC_BZIMAGE_VERIFY_SIG
2025 bool "Enable bzImage signature verification support"
2026 depends on KEXEC_VERIFY_SIG
2027 depends on SIGNED_PE_FILE_VERIFICATION
2028 select SYSTEM_TRUSTED_KEYRING
2030 Enable bzImage signature verification support.
2033 bool "kernel crash dumps"
2034 depends on X86_64 || (X86_32 && HIGHMEM)
2036 Generate crash dump after being started by kexec.
2037 This should be normally only set in special crash dump kernels
2038 which are loaded in the main kernel with kexec-tools into
2039 a specially reserved region and then later executed after
2040 a crash by kdump/kexec. The crash dump kernel must be compiled
2041 to a memory address not used by the main kernel or BIOS using
2042 PHYSICAL_START, or it must be built as a relocatable image
2043 (CONFIG_RELOCATABLE=y).
2044 For more details see Documentation/kdump/kdump.txt
2048 depends on KEXEC && HIBERNATION
2050 Jump between original kernel and kexeced kernel and invoke
2051 code in physical address mode via KEXEC
2053 config PHYSICAL_START
2054 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2057 This gives the physical address where the kernel is loaded.
2059 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2060 bzImage will decompress itself to above physical address and
2061 run from there. Otherwise, bzImage will run from the address where
2062 it has been loaded by the boot loader and will ignore above physical
2065 In normal kdump cases one does not have to set/change this option
2066 as now bzImage can be compiled as a completely relocatable image
2067 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2068 address. This option is mainly useful for the folks who don't want
2069 to use a bzImage for capturing the crash dump and want to use a
2070 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2071 to be specifically compiled to run from a specific memory area
2072 (normally a reserved region) and this option comes handy.
2074 So if you are using bzImage for capturing the crash dump,
2075 leave the value here unchanged to 0x1000000 and set
2076 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2077 for capturing the crash dump change this value to start of
2078 the reserved region. In other words, it can be set based on
2079 the "X" value as specified in the "crashkernel=YM@XM"
2080 command line boot parameter passed to the panic-ed
2081 kernel. Please take a look at Documentation/kdump/kdump.txt
2082 for more details about crash dumps.
2084 Usage of bzImage for capturing the crash dump is recommended as
2085 one does not have to build two kernels. Same kernel can be used
2086 as production kernel and capture kernel. Above option should have
2087 gone away after relocatable bzImage support is introduced. But it
2088 is present because there are users out there who continue to use
2089 vmlinux for dump capture. This option should go away down the
2092 Don't change this unless you know what you are doing.
2095 bool "Build a relocatable kernel"
2098 This builds a kernel image that retains relocation information
2099 so it can be loaded someplace besides the default 1MB.
2100 The relocations tend to make the kernel binary about 10% larger,
2101 but are discarded at runtime.
2103 One use is for the kexec on panic case where the recovery kernel
2104 must live at a different physical address than the primary
2107 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2108 it has been loaded at and the compile time physical address
2109 (CONFIG_PHYSICAL_START) is used as the minimum location.
2111 config RANDOMIZE_BASE
2112 bool "Randomize the address of the kernel image (KASLR)"
2113 depends on RELOCATABLE
2116 In support of Kernel Address Space Layout Randomization (KASLR),
2117 this randomizes the physical address at which the kernel image
2118 is decompressed and the virtual address where the kernel
2119 image is mapped, as a security feature that deters exploit
2120 attempts relying on knowledge of the location of kernel
2123 On 64-bit, the kernel physical and virtual addresses are
2124 randomized separately. The physical address will be anywhere
2125 between 16MB and the top of physical memory (up to 64TB). The
2126 virtual address will be randomized from 16MB up to 1GB (9 bits
2127 of entropy). Note that this also reduces the memory space
2128 available to kernel modules from 1.5GB to 1GB.
2130 On 32-bit, the kernel physical and virtual addresses are
2131 randomized together. They will be randomized from 16MB up to
2132 512MB (8 bits of entropy).
2134 Entropy is generated using the RDRAND instruction if it is
2135 supported. If RDTSC is supported, its value is mixed into
2136 the entropy pool as well. If neither RDRAND nor RDTSC are
2137 supported, then entropy is read from the i8254 timer. The
2138 usable entropy is limited by the kernel being built using
2139 2GB addressing, and that PHYSICAL_ALIGN must be at a
2140 minimum of 2MB. As a result, only 10 bits of entropy are
2141 theoretically possible, but the implementations are further
2142 limited due to memory layouts.
2146 # Relocation on x86 needs some additional build support
2147 config X86_NEED_RELOCS
2149 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2151 config PHYSICAL_ALIGN
2152 hex "Alignment value to which kernel should be aligned"
2154 range 0x2000 0x1000000 if X86_32
2155 range 0x200000 0x1000000 if X86_64
2157 This value puts the alignment restrictions on physical address
2158 where kernel is loaded and run from. Kernel is compiled for an
2159 address which meets above alignment restriction.
2161 If bootloader loads the kernel at a non-aligned address and
2162 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2163 address aligned to above value and run from there.
2165 If bootloader loads the kernel at a non-aligned address and
2166 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2167 load address and decompress itself to the address it has been
2168 compiled for and run from there. The address for which kernel is
2169 compiled already meets above alignment restrictions. Hence the
2170 end result is that kernel runs from a physical address meeting
2171 above alignment restrictions.
2173 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2174 this value must be a multiple of 0x200000.
2176 Don't change this unless you know what you are doing.
2178 config DYNAMIC_MEMORY_LAYOUT
2181 This option makes base addresses of vmalloc and vmemmap as well as
2182 __PAGE_OFFSET movable during boot.
2184 config RANDOMIZE_MEMORY
2185 bool "Randomize the kernel memory sections"
2187 depends on RANDOMIZE_BASE
2188 select DYNAMIC_MEMORY_LAYOUT
2189 default RANDOMIZE_BASE
2191 Randomizes the base virtual address of kernel memory sections
2192 (physical memory mapping, vmalloc & vmemmap). This security feature
2193 makes exploits relying on predictable memory locations less reliable.
2195 The order of allocations remains unchanged. Entropy is generated in
2196 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2197 configuration have in average 30,000 different possible virtual
2198 addresses for each memory section.
2202 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2203 hex "Physical memory mapping padding" if EXPERT
2204 depends on RANDOMIZE_MEMORY
2205 default "0xa" if MEMORY_HOTPLUG
2207 range 0x1 0x40 if MEMORY_HOTPLUG
2210 Define the padding in terabytes added to the existing physical
2211 memory size during kernel memory randomization. It is useful
2212 for memory hotplug support but reduces the entropy available for
2213 address randomization.
2215 If unsure, leave at the default value.
2218 bool "Support for hot-pluggable CPUs"
2221 Say Y here to allow turning CPUs off and on. CPUs can be
2222 controlled through /sys/devices/system/cpu.
2223 ( Note: power management support will enable this option
2224 automatically on SMP systems. )
2225 Say N if you want to disable CPU hotplug.
2227 config BOOTPARAM_HOTPLUG_CPU0
2228 bool "Set default setting of cpu0_hotpluggable"
2230 depends on HOTPLUG_CPU
2232 Set whether default state of cpu0_hotpluggable is on or off.
2234 Say Y here to enable CPU0 hotplug by default. If this switch
2235 is turned on, there is no need to give cpu0_hotplug kernel
2236 parameter and the CPU0 hotplug feature is enabled by default.
2238 Please note: there are two known CPU0 dependencies if you want
2239 to enable the CPU0 hotplug feature either by this switch or by
2240 cpu0_hotplug kernel parameter.
2242 First, resume from hibernate or suspend always starts from CPU0.
2243 So hibernate and suspend are prevented if CPU0 is offline.
2245 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2246 offline if any interrupt can not migrate out of CPU0. There may
2247 be other CPU0 dependencies.
2249 Please make sure the dependencies are under your control before
2250 you enable this feature.
2252 Say N if you don't want to enable CPU0 hotplug feature by default.
2253 You still can enable the CPU0 hotplug feature at boot by kernel
2254 parameter cpu0_hotplug.
2256 config DEBUG_HOTPLUG_CPU0
2258 prompt "Debug CPU0 hotplug"
2259 depends on HOTPLUG_CPU
2261 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2262 soon as possible and boots up userspace with CPU0 offlined. User
2263 can online CPU0 back after boot time.
2265 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2266 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2267 compilation or giving cpu0_hotplug kernel parameter at boot.
2273 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2274 depends on COMPAT_32
2276 Certain buggy versions of glibc will crash if they are
2277 presented with a 32-bit vDSO that is not mapped at the address
2278 indicated in its segment table.
2280 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2281 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2282 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2283 the only released version with the bug, but OpenSUSE 9
2284 contains a buggy "glibc 2.3.2".
2286 The symptom of the bug is that everything crashes on startup, saying:
2287 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2289 Saying Y here changes the default value of the vdso32 boot
2290 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2291 This works around the glibc bug but hurts performance.
2293 If unsure, say N: if you are compiling your own kernel, you
2294 are unlikely to be using a buggy version of glibc.
2297 prompt "vsyscall table for legacy applications"
2299 default LEGACY_VSYSCALL_EMULATE
2301 Legacy user code that does not know how to find the vDSO expects
2302 to be able to issue three syscalls by calling fixed addresses in
2303 kernel space. Since this location is not randomized with ASLR,
2304 it can be used to assist security vulnerability exploitation.
2306 This setting can be changed at boot time via the kernel command
2307 line parameter vsyscall=[emulate|none].
2309 On a system with recent enough glibc (2.14 or newer) and no
2310 static binaries, you can say None without a performance penalty
2311 to improve security.
2313 If unsure, select "Emulate".
2315 config LEGACY_VSYSCALL_EMULATE
2318 The kernel traps and emulates calls into the fixed
2319 vsyscall address mapping. This makes the mapping
2320 non-executable, but it still contains known contents,
2321 which could be used in certain rare security vulnerability
2322 exploits. This configuration is recommended when userspace
2323 still uses the vsyscall area.
2325 config LEGACY_VSYSCALL_NONE
2328 There will be no vsyscall mapping at all. This will
2329 eliminate any risk of ASLR bypass due to the vsyscall
2330 fixed address mapping. Attempts to use the vsyscalls
2331 will be reported to dmesg, so that either old or
2332 malicious userspace programs can be identified.
2337 bool "Built-in kernel command line"
2339 Allow for specifying boot arguments to the kernel at
2340 build time. On some systems (e.g. embedded ones), it is
2341 necessary or convenient to provide some or all of the
2342 kernel boot arguments with the kernel itself (that is,
2343 to not rely on the boot loader to provide them.)
2345 To compile command line arguments into the kernel,
2346 set this option to 'Y', then fill in the
2347 boot arguments in CONFIG_CMDLINE.
2349 Systems with fully functional boot loaders (i.e. non-embedded)
2350 should leave this option set to 'N'.
2353 string "Built-in kernel command string"
2354 depends on CMDLINE_BOOL
2357 Enter arguments here that should be compiled into the kernel
2358 image and used at boot time. If the boot loader provides a
2359 command line at boot time, it is appended to this string to
2360 form the full kernel command line, when the system boots.
2362 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2363 change this behavior.
2365 In most cases, the command line (whether built-in or provided
2366 by the boot loader) should specify the device for the root
2369 config CMDLINE_OVERRIDE
2370 bool "Built-in command line overrides boot loader arguments"
2371 depends on CMDLINE_BOOL
2373 Set this option to 'Y' to have the kernel ignore the boot loader
2374 command line, and use ONLY the built-in command line.
2376 This is used to work around broken boot loaders. This should
2377 be set to 'N' under normal conditions.
2379 config MODIFY_LDT_SYSCALL
2380 bool "Enable the LDT (local descriptor table)" if EXPERT
2383 Linux can allow user programs to install a per-process x86
2384 Local Descriptor Table (LDT) using the modify_ldt(2) system
2385 call. This is required to run 16-bit or segmented code such as
2386 DOSEMU or some Wine programs. It is also used by some very old
2387 threading libraries.
2389 Enabling this feature adds a small amount of overhead to
2390 context switches and increases the low-level kernel attack
2391 surface. Disabling it removes the modify_ldt(2) system call.
2393 Saying 'N' here may make sense for embedded or server kernels.
2395 source "kernel/livepatch/Kconfig"
2399 config ARCH_HAS_ADD_PAGES
2401 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2403 config ARCH_ENABLE_MEMORY_HOTPLUG
2405 depends on X86_64 || (X86_32 && HIGHMEM)
2407 config ARCH_ENABLE_MEMORY_HOTREMOVE
2409 depends on MEMORY_HOTPLUG
2411 config USE_PERCPU_NUMA_NODE_ID
2415 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2417 depends on X86_64 || X86_PAE
2419 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2421 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2423 config ARCH_ENABLE_THP_MIGRATION
2425 depends on X86_64 && TRANSPARENT_HUGEPAGE
2427 menu "Power management and ACPI options"
2429 config ARCH_HIBERNATION_HEADER
2431 depends on X86_64 && HIBERNATION
2433 source "kernel/power/Kconfig"
2435 source "drivers/acpi/Kconfig"
2437 source "drivers/sfi/Kconfig"
2444 tristate "APM (Advanced Power Management) BIOS support"
2445 depends on X86_32 && PM_SLEEP
2447 APM is a BIOS specification for saving power using several different
2448 techniques. This is mostly useful for battery powered laptops with
2449 APM compliant BIOSes. If you say Y here, the system time will be
2450 reset after a RESUME operation, the /proc/apm device will provide
2451 battery status information, and user-space programs will receive
2452 notification of APM "events" (e.g. battery status change).
2454 If you select "Y" here, you can disable actual use of the APM
2455 BIOS by passing the "apm=off" option to the kernel at boot time.
2457 Note that the APM support is almost completely disabled for
2458 machines with more than one CPU.
2460 In order to use APM, you will need supporting software. For location
2461 and more information, read <file:Documentation/power/apm-acpi.txt>
2462 and the Battery Powered Linux mini-HOWTO, available from
2463 <http://www.tldp.org/docs.html#howto>.
2465 This driver does not spin down disk drives (see the hdparm(8)
2466 manpage ("man 8 hdparm") for that), and it doesn't turn off
2467 VESA-compliant "green" monitors.
2469 This driver does not support the TI 4000M TravelMate and the ACER
2470 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2471 desktop machines also don't have compliant BIOSes, and this driver
2472 may cause those machines to panic during the boot phase.
2474 Generally, if you don't have a battery in your machine, there isn't
2475 much point in using this driver and you should say N. If you get
2476 random kernel OOPSes or reboots that don't seem to be related to
2477 anything, try disabling/enabling this option (or disabling/enabling
2480 Some other things you should try when experiencing seemingly random,
2483 1) make sure that you have enough swap space and that it is
2485 2) pass the "no-hlt" option to the kernel
2486 3) switch on floating point emulation in the kernel and pass
2487 the "no387" option to the kernel
2488 4) pass the "floppy=nodma" option to the kernel
2489 5) pass the "mem=4M" option to the kernel (thereby disabling
2490 all but the first 4 MB of RAM)
2491 6) make sure that the CPU is not over clocked.
2492 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2493 8) disable the cache from your BIOS settings
2494 9) install a fan for the video card or exchange video RAM
2495 10) install a better fan for the CPU
2496 11) exchange RAM chips
2497 12) exchange the motherboard.
2499 To compile this driver as a module, choose M here: the
2500 module will be called apm.
2504 config APM_IGNORE_USER_SUSPEND
2505 bool "Ignore USER SUSPEND"
2507 This option will ignore USER SUSPEND requests. On machines with a
2508 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2509 series notebooks, it is necessary to say Y because of a BIOS bug.
2511 config APM_DO_ENABLE
2512 bool "Enable PM at boot time"
2514 Enable APM features at boot time. From page 36 of the APM BIOS
2515 specification: "When disabled, the APM BIOS does not automatically
2516 power manage devices, enter the Standby State, enter the Suspend
2517 State, or take power saving steps in response to CPU Idle calls."
2518 This driver will make CPU Idle calls when Linux is idle (unless this
2519 feature is turned off -- see "Do CPU IDLE calls", below). This
2520 should always save battery power, but more complicated APM features
2521 will be dependent on your BIOS implementation. You may need to turn
2522 this option off if your computer hangs at boot time when using APM
2523 support, or if it beeps continuously instead of suspending. Turn
2524 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2525 T400CDT. This is off by default since most machines do fine without
2530 bool "Make CPU Idle calls when idle"
2532 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2533 On some machines, this can activate improved power savings, such as
2534 a slowed CPU clock rate, when the machine is idle. These idle calls
2535 are made after the idle loop has run for some length of time (e.g.,
2536 333 mS). On some machines, this will cause a hang at boot time or
2537 whenever the CPU becomes idle. (On machines with more than one CPU,
2538 this option does nothing.)
2540 config APM_DISPLAY_BLANK
2541 bool "Enable console blanking using APM"
2543 Enable console blanking using the APM. Some laptops can use this to
2544 turn off the LCD backlight when the screen blanker of the Linux
2545 virtual console blanks the screen. Note that this is only used by
2546 the virtual console screen blanker, and won't turn off the backlight
2547 when using the X Window system. This also doesn't have anything to
2548 do with your VESA-compliant power-saving monitor. Further, this
2549 option doesn't work for all laptops -- it might not turn off your
2550 backlight at all, or it might print a lot of errors to the console,
2551 especially if you are using gpm.
2553 config APM_ALLOW_INTS
2554 bool "Allow interrupts during APM BIOS calls"
2556 Normally we disable external interrupts while we are making calls to
2557 the APM BIOS as a measure to lessen the effects of a badly behaving
2558 BIOS implementation. The BIOS should reenable interrupts if it
2559 needs to. Unfortunately, some BIOSes do not -- especially those in
2560 many of the newer IBM Thinkpads. If you experience hangs when you
2561 suspend, try setting this to Y. Otherwise, say N.
2565 source "drivers/cpufreq/Kconfig"
2567 source "drivers/cpuidle/Kconfig"
2569 source "drivers/idle/Kconfig"
2574 menu "Bus options (PCI etc.)"
2580 Find out whether you have a PCI motherboard. PCI is the name of a
2581 bus system, i.e. the way the CPU talks to the other stuff inside
2582 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2583 VESA. If you have PCI, say Y, otherwise N.
2586 prompt "PCI access mode"
2587 depends on X86_32 && PCI
2590 On PCI systems, the BIOS can be used to detect the PCI devices and
2591 determine their configuration. However, some old PCI motherboards
2592 have BIOS bugs and may crash if this is done. Also, some embedded
2593 PCI-based systems don't have any BIOS at all. Linux can also try to
2594 detect the PCI hardware directly without using the BIOS.
2596 With this option, you can specify how Linux should detect the
2597 PCI devices. If you choose "BIOS", the BIOS will be used,
2598 if you choose "Direct", the BIOS won't be used, and if you
2599 choose "MMConfig", then PCI Express MMCONFIG will be used.
2600 If you choose "Any", the kernel will try MMCONFIG, then the
2601 direct access method and falls back to the BIOS if that doesn't
2602 work. If unsure, go with the default, which is "Any".
2607 config PCI_GOMMCONFIG
2624 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2626 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2629 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2632 bool "Support mmconfig PCI config space access" if X86_64
2634 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2635 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2639 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2643 depends on PCI && XEN
2650 config MMCONF_FAM10H
2652 depends on X86_64 && PCI_MMCONFIG && ACPI
2654 config PCI_CNB20LE_QUIRK
2655 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2658 Read the PCI windows out of the CNB20LE host bridge. This allows
2659 PCI hotplug to work on systems with the CNB20LE chipset which do
2662 There's no public spec for this chipset, and this functionality
2663 is known to be incomplete.
2665 You should say N unless you know you need this.
2667 source "drivers/pci/Kconfig"
2670 bool "ISA bus support on modern systems" if EXPERT
2672 Expose ISA bus device drivers and options available for selection and
2673 configuration. Enable this option if your target machine has an ISA
2674 bus. ISA is an older system, displaced by PCI and newer bus
2675 architectures -- if your target machine is modern, it probably does
2676 not have an ISA bus.
2680 # x86_64 have no ISA slots, but can have ISA-style DMA.
2682 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2685 Enables ISA-style DMA support for devices requiring such controllers.
2693 Find out whether you have ISA slots on your motherboard. ISA is the
2694 name of a bus system, i.e. the way the CPU talks to the other stuff
2695 inside your box. Other bus systems are PCI, EISA, MicroChannel
2696 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2697 newer boards don't support it. If you have ISA, say Y, otherwise N.
2703 The Extended Industry Standard Architecture (EISA) bus was
2704 developed as an open alternative to the IBM MicroChannel bus.
2706 The EISA bus provided some of the features of the IBM MicroChannel
2707 bus while maintaining backward compatibility with cards made for
2708 the older ISA bus. The EISA bus saw limited use between 1988 and
2709 1995 when it was made obsolete by the PCI bus.
2711 Say Y here if you are building a kernel for an EISA-based machine.
2715 source "drivers/eisa/Kconfig"
2718 tristate "NatSemi SCx200 support"
2720 This provides basic support for National Semiconductor's
2721 (now AMD's) Geode processors. The driver probes for the
2722 PCI-IDs of several on-chip devices, so its a good dependency
2723 for other scx200_* drivers.
2725 If compiled as a module, the driver is named scx200.
2727 config SCx200HR_TIMER
2728 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2732 This driver provides a clocksource built upon the on-chip
2733 27MHz high-resolution timer. Its also a workaround for
2734 NSC Geode SC-1100's buggy TSC, which loses time when the
2735 processor goes idle (as is done by the scheduler). The
2736 other workaround is idle=poll boot option.
2739 bool "One Laptop Per Child support"
2746 Add support for detecting the unique features of the OLPC
2750 bool "OLPC XO-1 Power Management"
2751 depends on OLPC && MFD_CS5535 && PM_SLEEP
2754 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2757 bool "OLPC XO-1 Real Time Clock"
2758 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2760 Add support for the XO-1 real time clock, which can be used as a
2761 programmable wakeup source.
2764 bool "OLPC XO-1 SCI extras"
2765 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2769 Add support for SCI-based features of the OLPC XO-1 laptop:
2770 - EC-driven system wakeups
2774 - AC adapter status updates
2775 - Battery status updates
2777 config OLPC_XO15_SCI
2778 bool "OLPC XO-1.5 SCI extras"
2779 depends on OLPC && ACPI
2782 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2783 - EC-driven system wakeups
2784 - AC adapter status updates
2785 - Battery status updates
2788 bool "PCEngines ALIX System Support (LED setup)"
2791 This option enables system support for the PCEngines ALIX.
2792 At present this just sets up LEDs for GPIO control on
2793 ALIX2/3/6 boards. However, other system specific setup should
2796 Note: You must still enable the drivers for GPIO and LED support
2797 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2799 Note: You have to set alix.force=1 for boards with Award BIOS.
2802 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2805 This option enables system support for the Soekris Engineering net5501.
2808 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2812 This option enables system support for the Traverse Technologies GEOS.
2815 bool "Technologic Systems TS-5500 platform support"
2817 select CHECK_SIGNATURE
2821 This option enables system support for the Technologic Systems TS-5500.
2827 depends on CPU_SUP_AMD && PCI
2829 source "drivers/pcmcia/Kconfig"
2832 tristate "RapidIO support"
2836 If enabled this option will include drivers and the core
2837 infrastructure code to support RapidIO interconnect devices.
2839 source "drivers/rapidio/Kconfig"
2842 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2844 Firmwares often provide initial graphics framebuffers so the BIOS,
2845 bootloader or kernel can show basic video-output during boot for
2846 user-guidance and debugging. Historically, x86 used the VESA BIOS
2847 Extensions and EFI-framebuffers for this, which are mostly limited
2849 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2850 framebuffers so the new generic system-framebuffer drivers can be
2851 used on x86. If the framebuffer is not compatible with the generic
2852 modes, it is adverticed as fallback platform framebuffer so legacy
2853 drivers like efifb, vesafb and uvesafb can pick it up.
2854 If this option is not selected, all system framebuffers are always
2855 marked as fallback platform framebuffers as usual.
2857 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2858 not be able to pick up generic system framebuffers if this option
2859 is selected. You are highly encouraged to enable simplefb as
2860 replacement if you select this option. simplefb can correctly deal
2861 with generic system framebuffers. But you should still keep vesafb
2862 and others enabled as fallback if a system framebuffer is
2863 incompatible with simplefb.
2870 menu "Executable file formats / Emulations"
2872 source "fs/Kconfig.binfmt"
2874 config IA32_EMULATION
2875 bool "IA32 Emulation"
2877 select ARCH_WANT_OLD_COMPAT_IPC
2879 select COMPAT_BINFMT_ELF
2880 select COMPAT_OLD_SIGACTION
2882 Include code to run legacy 32-bit programs under a
2883 64-bit kernel. You should likely turn this on, unless you're
2884 100% sure that you don't have any 32-bit programs left.
2887 tristate "IA32 a.out support"
2888 depends on IA32_EMULATION
2890 Support old a.out binaries in the 32bit emulation.
2893 bool "x32 ABI for 64-bit mode"
2896 Include code to run binaries for the x32 native 32-bit ABI
2897 for 64-bit processors. An x32 process gets access to the
2898 full 64-bit register file and wide data path while leaving
2899 pointers at 32 bits for smaller memory footprint.
2901 You will need a recent binutils (2.22 or later) with
2902 elf32_x86_64 support enabled to compile a kernel with this
2907 depends on IA32_EMULATION || X86_32
2909 select OLD_SIGSUSPEND3
2913 depends on IA32_EMULATION || X86_X32
2916 config COMPAT_FOR_U64_ALIGNMENT
2919 config SYSVIPC_COMPAT
2927 config HAVE_ATOMIC_IOMAP
2931 config X86_DEV_DMA_OPS
2933 depends on X86_64 || STA2X11
2935 config X86_DMA_REMAP
2939 config HAVE_GENERIC_GUP
2942 source "net/Kconfig"
2944 source "drivers/Kconfig"
2946 source "drivers/firmware/Kconfig"
2950 source "arch/x86/Kconfig.debug"
2952 source "security/Kconfig"
2954 source "crypto/Kconfig"
2956 source "arch/x86/kvm/Kconfig"
2958 source "lib/Kconfig"
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