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_PREL32_RELOCATIONS
128 select HAVE_ARCH_SECCOMP_FILTER
129 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
130 select HAVE_ARCH_TRACEHOOK
131 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
132 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
133 select HAVE_ARCH_VMAP_STACK if X86_64
134 select HAVE_ARCH_WITHIN_STACK_FRAMES
135 select HAVE_CMPXCHG_DOUBLE
136 select HAVE_CMPXCHG_LOCAL
137 select HAVE_CONTEXT_TRACKING if X86_64
138 select HAVE_COPY_THREAD_TLS
139 select HAVE_C_RECORDMCOUNT
140 select HAVE_DEBUG_KMEMLEAK
141 select HAVE_DEBUG_STACKOVERFLOW
142 select HAVE_DMA_CONTIGUOUS
143 select HAVE_DYNAMIC_FTRACE
144 select HAVE_DYNAMIC_FTRACE_WITH_REGS
146 select HAVE_EFFICIENT_UNALIGNED_ACCESS
147 select HAVE_EXIT_THREAD
148 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
149 select HAVE_FTRACE_MCOUNT_RECORD
150 select HAVE_FUNCTION_GRAPH_TRACER
151 select HAVE_FUNCTION_TRACER
152 select HAVE_GCC_PLUGINS
153 select HAVE_HW_BREAKPOINT
155 select HAVE_IOREMAP_PROT
156 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
157 select HAVE_IRQ_TIME_ACCOUNTING
158 select HAVE_KERNEL_BZIP2
159 select HAVE_KERNEL_GZIP
160 select HAVE_KERNEL_LZ4
161 select HAVE_KERNEL_LZMA
162 select HAVE_KERNEL_LZO
163 select HAVE_KERNEL_XZ
165 select HAVE_KPROBES_ON_FTRACE
166 select HAVE_FUNCTION_ERROR_INJECTION
167 select HAVE_KRETPROBES
169 select HAVE_LIVEPATCH if X86_64
171 select HAVE_MEMBLOCK_NODE_MAP
172 select HAVE_MIXED_BREAKPOINTS_REGS
173 select HAVE_MOD_ARCH_SPECIFIC
176 select HAVE_OPTPROBES
177 select HAVE_PCSPKR_PLATFORM
178 select HAVE_PERF_EVENTS
179 select HAVE_PERF_EVENTS_NMI
180 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
181 select HAVE_PERF_REGS
182 select HAVE_PERF_USER_STACK_DUMP
183 select HAVE_RCU_TABLE_FREE if PARAVIRT
184 select HAVE_RCU_TABLE_INVALIDATE if HAVE_RCU_TABLE_FREE
185 select HAVE_REGS_AND_STACK_ACCESS_API
186 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
187 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
188 select HAVE_STACK_VALIDATION if X86_64
190 select HAVE_SYSCALL_TRACEPOINTS
191 select HAVE_UNSTABLE_SCHED_CLOCK
192 select HAVE_USER_RETURN_NOTIFIER
193 select HOTPLUG_SMT if SMP
194 select IRQ_FORCED_THREADING
195 select NEED_SG_DMA_LENGTH
196 select PCI_LOCKLESS_CONFIG
199 select RTC_MC146818_LIB
202 select SYSCTL_EXCEPTION_TRACE
203 select THREAD_INFO_IN_TASK
204 select USER_STACKTRACE_SUPPORT
206 select X86_FEATURE_NAMES if PROC_FS
208 config INSTRUCTION_DECODER
210 depends on KPROBES || PERF_EVENTS || UPROBES
214 default "elf32-i386" if X86_32
215 default "elf64-x86-64" if X86_64
217 config ARCH_DEFCONFIG
219 default "arch/x86/configs/i386_defconfig" if X86_32
220 default "arch/x86/configs/x86_64_defconfig" if X86_64
222 config LOCKDEP_SUPPORT
225 config STACKTRACE_SUPPORT
231 config ARCH_MMAP_RND_BITS_MIN
235 config ARCH_MMAP_RND_BITS_MAX
239 config ARCH_MMAP_RND_COMPAT_BITS_MIN
242 config ARCH_MMAP_RND_COMPAT_BITS_MAX
248 config GENERIC_ISA_DMA
250 depends on ISA_DMA_API
255 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
257 config GENERIC_BUG_RELATIVE_POINTERS
260 config GENERIC_HWEIGHT
263 config ARCH_MAY_HAVE_PC_FDC
265 depends on ISA_DMA_API
267 config RWSEM_XCHGADD_ALGORITHM
270 config GENERIC_CALIBRATE_DELAY
273 config ARCH_HAS_CPU_RELAX
276 config ARCH_HAS_CACHE_LINE_SIZE
279 config ARCH_HAS_FILTER_PGPROT
282 config HAVE_SETUP_PER_CPU_AREA
285 config NEED_PER_CPU_EMBED_FIRST_CHUNK
288 config NEED_PER_CPU_PAGE_FIRST_CHUNK
291 config ARCH_HIBERNATION_POSSIBLE
294 config ARCH_SUSPEND_POSSIBLE
297 config ARCH_WANT_HUGE_PMD_SHARE
300 config ARCH_WANT_GENERAL_HUGETLB
309 config ARCH_SUPPORTS_OPTIMIZED_INLINING
312 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
315 config KASAN_SHADOW_OFFSET
318 default 0xdffffc0000000000
320 config HAVE_INTEL_TXT
322 depends on INTEL_IOMMU && ACPI
326 depends on X86_32 && SMP
330 depends on X86_64 && SMP
332 config X86_32_LAZY_GS
334 depends on X86_32 && !STACKPROTECTOR
336 config ARCH_SUPPORTS_UPROBES
339 config FIX_EARLYCON_MEM
342 config DYNAMIC_PHYSICAL_MASK
345 config PGTABLE_LEVELS
347 default 5 if X86_5LEVEL
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 menu "Processor type and features"
363 bool "DMA memory allocation support" if EXPERT
366 DMA memory allocation support allows devices with less than 32-bit
367 addressing to allocate within the first 16MB of address space.
368 Disable if no such devices will be used.
373 bool "Symmetric multi-processing support"
375 This enables support for systems with more than one CPU. If you have
376 a system with only one CPU, say N. If you have a system with more
379 If you say N here, the kernel will run on uni- and multiprocessor
380 machines, but will use only one CPU of a multiprocessor machine. If
381 you say Y here, the kernel will run on many, but not all,
382 uniprocessor machines. On a uniprocessor machine, the kernel
383 will run faster if you say N here.
385 Note that if you say Y here and choose architecture "586" or
386 "Pentium" under "Processor family", the kernel will not work on 486
387 architectures. Similarly, multiprocessor kernels for the "PPro"
388 architecture may not work on all Pentium based boards.
390 People using multiprocessor machines who say Y here should also say
391 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
392 Management" code will be disabled if you say Y here.
394 See also <file:Documentation/x86/i386/IO-APIC.txt>,
395 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
396 <http://www.tldp.org/docs.html#howto>.
398 If you don't know what to do here, say N.
400 config X86_FEATURE_NAMES
401 bool "Processor feature human-readable names" if EMBEDDED
404 This option compiles in a table of x86 feature bits and corresponding
405 names. This is required to support /proc/cpuinfo and a few kernel
406 messages. You can disable this to save space, at the expense of
407 making those few kernel messages show numeric feature bits instead.
412 bool "Support x2apic"
413 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
415 This enables x2apic support on CPUs that have this feature.
417 This allows 32-bit apic IDs (so it can support very large systems),
418 and accesses the local apic via MSRs not via mmio.
420 If you don't know what to do here, say N.
423 bool "Enable MPS table" if ACPI || SFI
425 depends on X86_LOCAL_APIC
427 For old smp systems that do not have proper acpi support. Newer systems
428 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
432 depends on X86_GOLDFISH
435 bool "Avoid speculative indirect branches in kernel"
437 select STACK_VALIDATION if HAVE_STACK_VALIDATION
439 Compile kernel with the retpoline compiler options to guard against
440 kernel-to-user data leaks by avoiding speculative indirect
441 branches. Requires a compiler with -mindirect-branch=thunk-extern
442 support for full protection. The kernel may run slower.
445 bool "Intel Resource Director Technology support"
447 depends on X86 && CPU_SUP_INTEL
450 Select to enable resource allocation and monitoring which are
451 sub-features of Intel Resource Director Technology(RDT). More
452 information about RDT can be found in the Intel x86
453 Architecture Software Developer Manual.
459 bool "Support for big SMP systems with more than 8 CPUs"
462 This option is needed for the systems that have more than 8 CPUs
464 config X86_EXTENDED_PLATFORM
465 bool "Support for extended (non-PC) x86 platforms"
468 If you disable this option then the kernel will only support
469 standard PC platforms. (which covers the vast majority of
472 If you enable this option then you'll be able to select support
473 for the following (non-PC) 32 bit x86 platforms:
474 Goldfish (Android emulator)
477 SGI 320/540 (Visual Workstation)
478 STA2X11-based (e.g. Northville)
479 Moorestown MID devices
481 If you have one of these systems, or if you want to build a
482 generic distribution kernel, say Y here - otherwise say N.
486 config X86_EXTENDED_PLATFORM
487 bool "Support for extended (non-PC) x86 platforms"
490 If you disable this option then the kernel will only support
491 standard PC platforms. (which covers the vast majority of
494 If you enable this option then you'll be able to select support
495 for the following (non-PC) 64 bit x86 platforms:
500 If you have one of these systems, or if you want to build a
501 generic distribution kernel, say Y here - otherwise say N.
503 # This is an alphabetically sorted list of 64 bit extended platforms
504 # Please maintain the alphabetic order if and when there are additions
506 bool "Numascale NumaChip"
508 depends on X86_EXTENDED_PLATFORM
511 depends on X86_X2APIC
512 depends on PCI_MMCONFIG
514 Adds support for Numascale NumaChip large-SMP systems. Needed to
515 enable more than ~168 cores.
516 If you don't have one of these, you should say N here.
520 select HYPERVISOR_GUEST
522 depends on X86_64 && PCI
523 depends on X86_EXTENDED_PLATFORM
526 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
527 supposed to run on these EM64T-based machines. Only choose this option
528 if you have one of these machines.
531 bool "SGI Ultraviolet"
533 depends on X86_EXTENDED_PLATFORM
536 depends on X86_X2APIC
539 This option is needed in order to support SGI Ultraviolet systems.
540 If you don't have one of these, you should say N here.
542 # Following is an alphabetically sorted list of 32 bit extended platforms
543 # Please maintain the alphabetic order if and when there are additions
546 bool "Goldfish (Virtual Platform)"
547 depends on X86_EXTENDED_PLATFORM
549 Enable support for the Goldfish virtual platform used primarily
550 for Android development. Unless you are building for the Android
551 Goldfish emulator say N here.
554 bool "CE4100 TV platform"
556 depends on PCI_GODIRECT
557 depends on X86_IO_APIC
559 depends on X86_EXTENDED_PLATFORM
560 select X86_REBOOTFIXUPS
562 select OF_EARLY_FLATTREE
564 Select for the Intel CE media processor (CE4100) SOC.
565 This option compiles in support for the CE4100 SOC for settop
566 boxes and media devices.
569 bool "Intel MID platform support"
570 depends on X86_EXTENDED_PLATFORM
571 depends on X86_PLATFORM_DEVICES
573 depends on X86_64 || (PCI_GOANY && X86_32)
574 depends on X86_IO_APIC
580 select MFD_INTEL_MSIC
582 Select to build a kernel capable of supporting Intel MID (Mobile
583 Internet Device) platform systems which do not have the PCI legacy
584 interfaces. If you are building for a PC class system say N here.
586 Intel MID platforms are based on an Intel processor and chipset which
587 consume less power than most of the x86 derivatives.
589 config X86_INTEL_QUARK
590 bool "Intel Quark platform support"
592 depends on X86_EXTENDED_PLATFORM
593 depends on X86_PLATFORM_DEVICES
597 depends on X86_IO_APIC
602 Select to include support for Quark X1000 SoC.
603 Say Y here if you have a Quark based system such as the Arduino
604 compatible Intel Galileo.
606 config X86_INTEL_LPSS
607 bool "Intel Low Power Subsystem Support"
608 depends on X86 && ACPI
613 Select to build support for Intel Low Power Subsystem such as
614 found on Intel Lynxpoint PCH. Selecting this option enables
615 things like clock tree (common clock framework) and pincontrol
616 which are needed by the LPSS peripheral drivers.
618 config X86_AMD_PLATFORM_DEVICE
619 bool "AMD ACPI2Platform devices support"
624 Select to interpret AMD specific ACPI device to platform device
625 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
626 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
627 implemented under PINCTRL subsystem.
630 tristate "Intel SoC IOSF Sideband support for SoC platforms"
633 This option enables sideband register access support for Intel SoC
634 platforms. On these platforms the IOSF sideband is used in lieu of
635 MSR's for some register accesses, mostly but not limited to thermal
636 and power. Drivers may query the availability of this device to
637 determine if they need the sideband in order to work on these
638 platforms. The sideband is available on the following SoC products.
639 This list is not meant to be exclusive.
644 You should say Y if you are running a kernel on one of these SoC's.
646 config IOSF_MBI_DEBUG
647 bool "Enable IOSF sideband access through debugfs"
648 depends on IOSF_MBI && DEBUG_FS
650 Select this option to expose the IOSF sideband access registers (MCR,
651 MDR, MCRX) through debugfs to write and read register information from
652 different units on the SoC. This is most useful for obtaining device
653 state information for debug and analysis. As this is a general access
654 mechanism, users of this option would have specific knowledge of the
655 device they want to access.
657 If you don't require the option or are in doubt, say N.
660 bool "RDC R-321x SoC"
662 depends on X86_EXTENDED_PLATFORM
664 select X86_REBOOTFIXUPS
666 This option is needed for RDC R-321x system-on-chip, also known
668 If you don't have one of these chips, you should say N here.
670 config X86_32_NON_STANDARD
671 bool "Support non-standard 32-bit SMP architectures"
672 depends on X86_32 && SMP
673 depends on X86_EXTENDED_PLATFORM
675 This option compiles in the bigsmp and STA2X11 default
676 subarchitectures. It is intended for a generic binary
677 kernel. If you select them all, kernel will probe it one by
678 one and will fallback to default.
680 # Alphabetically sorted list of Non standard 32 bit platforms
682 config X86_SUPPORTS_MEMORY_FAILURE
684 # MCE code calls memory_failure():
686 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
687 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
688 depends on X86_64 || !SPARSEMEM
689 select ARCH_SUPPORTS_MEMORY_FAILURE
692 bool "STA2X11 Companion Chip Support"
693 depends on X86_32_NON_STANDARD && PCI
694 select ARCH_HAS_PHYS_TO_DMA
695 select X86_DEV_DMA_OPS
702 This adds support for boards based on the STA2X11 IO-Hub,
703 a.k.a. "ConneXt". The chip is used in place of the standard
704 PC chipset, so all "standard" peripherals are missing. If this
705 option is selected the kernel will still be able to boot on
706 standard PC machines.
709 tristate "Eurobraille/Iris poweroff module"
712 The Iris machines from EuroBraille do not have APM or ACPI support
713 to shut themselves down properly. A special I/O sequence is
714 needed to do so, which is what this module does at
717 This is only for Iris machines from EuroBraille.
721 config SCHED_OMIT_FRAME_POINTER
723 prompt "Single-depth WCHAN output"
726 Calculate simpler /proc/<PID>/wchan values. If this option
727 is disabled then wchan values will recurse back to the
728 caller function. This provides more accurate wchan values,
729 at the expense of slightly more scheduling overhead.
731 If in doubt, say "Y".
733 menuconfig HYPERVISOR_GUEST
734 bool "Linux guest support"
736 Say Y here to enable options for running Linux under various hyper-
737 visors. This option enables basic hypervisor detection and platform
740 If you say N, all options in this submenu will be skipped and
741 disabled, and Linux guest support won't be built in.
746 bool "Enable paravirtualization code"
748 This changes the kernel so it can modify itself when it is run
749 under a hypervisor, potentially improving performance significantly
750 over full virtualization. However, when run without a hypervisor
751 the kernel is theoretically slower and slightly larger.
753 config PARAVIRT_DEBUG
754 bool "paravirt-ops debugging"
755 depends on PARAVIRT && DEBUG_KERNEL
757 Enable to debug paravirt_ops internals. Specifically, BUG if
758 a paravirt_op is missing when it is called.
760 config PARAVIRT_SPINLOCKS
761 bool "Paravirtualization layer for spinlocks"
762 depends on PARAVIRT && SMP
764 Paravirtualized spinlocks allow a pvops backend to replace the
765 spinlock implementation with something virtualization-friendly
766 (for example, block the virtual CPU rather than spinning).
768 It has a minimal impact on native kernels and gives a nice performance
769 benefit on paravirtualized KVM / Xen kernels.
771 If you are unsure how to answer this question, answer Y.
773 config QUEUED_LOCK_STAT
774 bool "Paravirt queued spinlock statistics"
775 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
777 Enable the collection of statistical data on the slowpath
778 behavior of paravirtualized queued spinlocks and report
781 source "arch/x86/xen/Kconfig"
784 bool "KVM Guest support (including kvmclock)"
786 select PARAVIRT_CLOCK
789 This option enables various optimizations for running under the KVM
790 hypervisor. It includes a paravirtualized clock, so that instead
791 of relying on a PIT (or probably other) emulation by the
792 underlying device model, the host provides the guest with
793 timing infrastructure such as time of day, and system time
796 bool "Enable debug information for KVM Guests in debugfs"
797 depends on KVM_GUEST && DEBUG_FS
800 This option enables collection of various statistics for KVM guest.
801 Statistics are displayed in debugfs filesystem. Enabling this option
802 may incur significant overhead.
804 config PARAVIRT_TIME_ACCOUNTING
805 bool "Paravirtual steal time accounting"
809 Select this option to enable fine granularity task steal time
810 accounting. Time spent executing other tasks in parallel with
811 the current vCPU is discounted from the vCPU power. To account for
812 that, there can be a small performance impact.
814 If in doubt, say N here.
816 config PARAVIRT_CLOCK
819 config JAILHOUSE_GUEST
820 bool "Jailhouse non-root cell support"
821 depends on X86_64 && PCI
824 This option allows to run Linux as guest in a Jailhouse non-root
825 cell. You can leave this option disabled if you only want to start
826 Jailhouse and run Linux afterwards in the root cell.
828 endif #HYPERVISOR_GUEST
833 source "arch/x86/Kconfig.cpu"
837 prompt "HPET Timer Support" if X86_32
839 Use the IA-PC HPET (High Precision Event Timer) to manage
840 time in preference to the PIT and RTC, if a HPET is
842 HPET is the next generation timer replacing legacy 8254s.
843 The HPET provides a stable time base on SMP
844 systems, unlike the TSC, but it is more expensive to access,
845 as it is off-chip. The interface used is documented
846 in the HPET spec, revision 1.
848 You can safely choose Y here. However, HPET will only be
849 activated if the platform and the BIOS support this feature.
850 Otherwise the 8254 will be used for timing services.
852 Choose N to continue using the legacy 8254 timer.
854 config HPET_EMULATE_RTC
856 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
859 def_bool y if X86_INTEL_MID
860 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
862 depends on X86_INTEL_MID && SFI
864 APB timer is the replacement for 8254, HPET on X86 MID platforms.
865 The APBT provides a stable time base on SMP
866 systems, unlike the TSC, but it is more expensive to access,
867 as it is off-chip. APB timers are always running regardless of CPU
868 C states, they are used as per CPU clockevent device when possible.
870 # Mark as expert because too many people got it wrong.
871 # The code disables itself when not needed.
874 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
875 bool "Enable DMI scanning" if EXPERT
877 Enabled scanning of DMI to identify machine quirks. Say Y
878 here unless you have verified that your setup is not
879 affected by entries in the DMI blacklist. Required by PNP
883 bool "Old AMD GART IOMMU support"
886 depends on X86_64 && PCI && AMD_NB
888 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
889 GART based hardware IOMMUs.
891 The GART supports full DMA access for devices with 32-bit access
892 limitations, on systems with more than 3 GB. This is usually needed
893 for USB, sound, many IDE/SATA chipsets and some other devices.
895 Newer systems typically have a modern AMD IOMMU, supported via
896 the CONFIG_AMD_IOMMU=y config option.
898 In normal configurations this driver is only active when needed:
899 there's more than 3 GB of memory and the system contains a
900 32-bit limited device.
905 bool "IBM Calgary IOMMU support"
908 depends on X86_64 && PCI
910 Support for hardware IOMMUs in IBM's xSeries x366 and x460
911 systems. Needed to run systems with more than 3GB of memory
912 properly with 32-bit PCI devices that do not support DAC
913 (Double Address Cycle). Calgary also supports bus level
914 isolation, where all DMAs pass through the IOMMU. This
915 prevents them from going anywhere except their intended
916 destination. This catches hard-to-find kernel bugs and
917 mis-behaving drivers and devices that do not use the DMA-API
918 properly to set up their DMA buffers. The IOMMU can be
919 turned off at boot time with the iommu=off parameter.
920 Normally the kernel will make the right choice by itself.
923 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
925 prompt "Should Calgary be enabled by default?"
926 depends on CALGARY_IOMMU
928 Should Calgary be enabled by default? if you choose 'y', Calgary
929 will be used (if it exists). If you choose 'n', Calgary will not be
930 used even if it exists. If you choose 'n' and would like to use
931 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
935 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
936 depends on X86_64 && SMP && DEBUG_KERNEL
937 select CPUMASK_OFFSTACK
939 Enable maximum number of CPUS and NUMA Nodes for this architecture.
943 # The maximum number of CPUs supported:
945 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
946 # and which can be configured interactively in the
947 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
949 # The ranges are different on 32-bit and 64-bit kernels, depending on
950 # hardware capabilities and scalability features of the kernel.
952 # ( If MAXSMP is enabled we just use the highest possible value and disable
953 # interactive configuration. )
956 config NR_CPUS_RANGE_BEGIN
958 default NR_CPUS_RANGE_END if MAXSMP
962 config NR_CPUS_RANGE_END
965 default 64 if SMP && X86_BIGSMP
966 default 8 if SMP && !X86_BIGSMP
969 config NR_CPUS_RANGE_END
972 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
973 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
976 config NR_CPUS_DEFAULT
979 default 32 if X86_BIGSMP
983 config NR_CPUS_DEFAULT
986 default 8192 if MAXSMP
991 int "Maximum number of CPUs" if SMP && !MAXSMP
992 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
993 default NR_CPUS_DEFAULT
995 This allows you to specify the maximum number of CPUs which this
996 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
997 supported value is 8192, otherwise the maximum value is 512. The
998 minimum value which makes sense is 2.
1000 This is purely to save memory: each supported CPU adds about 8KB
1001 to the kernel image.
1008 prompt "Multi-core scheduler support"
1011 Multi-core scheduler support improves the CPU scheduler's decision
1012 making when dealing with multi-core CPU chips at a cost of slightly
1013 increased overhead in some places. If unsure say N here.
1015 config SCHED_MC_PRIO
1016 bool "CPU core priorities scheduler support"
1017 depends on SCHED_MC && CPU_SUP_INTEL
1018 select X86_INTEL_PSTATE
1022 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1023 core ordering determined at manufacturing time, which allows
1024 certain cores to reach higher turbo frequencies (when running
1025 single threaded workloads) than others.
1027 Enabling this kernel feature teaches the scheduler about
1028 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1029 scheduler's CPU selection logic accordingly, so that higher
1030 overall system performance can be achieved.
1032 This feature will have no effect on CPUs without this feature.
1034 If unsure say Y here.
1038 depends on !SMP && X86_LOCAL_APIC
1041 bool "Local APIC support on uniprocessors" if !PCI_MSI
1043 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1045 A local APIC (Advanced Programmable Interrupt Controller) is an
1046 integrated interrupt controller in the CPU. If you have a single-CPU
1047 system which has a processor with a local APIC, you can say Y here to
1048 enable and use it. If you say Y here even though your machine doesn't
1049 have a local APIC, then the kernel will still run with no slowdown at
1050 all. The local APIC supports CPU-generated self-interrupts (timer,
1051 performance counters), and the NMI watchdog which detects hard
1054 config X86_UP_IOAPIC
1055 bool "IO-APIC support on uniprocessors"
1056 depends on X86_UP_APIC
1058 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1059 SMP-capable replacement for PC-style interrupt controllers. Most
1060 SMP systems and many recent uniprocessor systems have one.
1062 If you have a single-CPU system with an IO-APIC, you can say Y here
1063 to use it. If you say Y here even though your machine doesn't have
1064 an IO-APIC, then the kernel will still run with no slowdown at all.
1066 config X86_LOCAL_APIC
1068 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1069 select IRQ_DOMAIN_HIERARCHY
1070 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1074 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1076 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1077 bool "Reroute for broken boot IRQs"
1078 depends on X86_IO_APIC
1080 This option enables a workaround that fixes a source of
1081 spurious interrupts. This is recommended when threaded
1082 interrupt handling is used on systems where the generation of
1083 superfluous "boot interrupts" cannot be disabled.
1085 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1086 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1087 kernel does during interrupt handling). On chipsets where this
1088 boot IRQ generation cannot be disabled, this workaround keeps
1089 the original IRQ line masked so that only the equivalent "boot
1090 IRQ" is delivered to the CPUs. The workaround also tells the
1091 kernel to set up the IRQ handler on the boot IRQ line. In this
1092 way only one interrupt is delivered to the kernel. Otherwise
1093 the spurious second interrupt may cause the kernel to bring
1094 down (vital) interrupt lines.
1096 Only affects "broken" chipsets. Interrupt sharing may be
1097 increased on these systems.
1100 bool "Machine Check / overheating reporting"
1101 select GENERIC_ALLOCATOR
1104 Machine Check support allows the processor to notify the
1105 kernel if it detects a problem (e.g. overheating, data corruption).
1106 The action the kernel takes depends on the severity of the problem,
1107 ranging from warning messages to halting the machine.
1109 config X86_MCELOG_LEGACY
1110 bool "Support for deprecated /dev/mcelog character device"
1113 Enable support for /dev/mcelog which is needed by the old mcelog
1114 userspace logging daemon. Consider switching to the new generation
1117 config X86_MCE_INTEL
1119 prompt "Intel MCE features"
1120 depends on X86_MCE && X86_LOCAL_APIC
1122 Additional support for intel specific MCE features such as
1123 the thermal monitor.
1127 prompt "AMD MCE features"
1128 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1130 Additional support for AMD specific MCE features such as
1131 the DRAM Error Threshold.
1133 config X86_ANCIENT_MCE
1134 bool "Support for old Pentium 5 / WinChip machine checks"
1135 depends on X86_32 && X86_MCE
1137 Include support for machine check handling on old Pentium 5 or WinChip
1138 systems. These typically need to be enabled explicitly on the command
1141 config X86_MCE_THRESHOLD
1142 depends on X86_MCE_AMD || X86_MCE_INTEL
1145 config X86_MCE_INJECT
1146 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1147 tristate "Machine check injector support"
1149 Provide support for injecting machine checks for testing purposes.
1150 If you don't know what a machine check is and you don't do kernel
1151 QA it is safe to say n.
1153 config X86_THERMAL_VECTOR
1155 depends on X86_MCE_INTEL
1157 source "arch/x86/events/Kconfig"
1159 config X86_LEGACY_VM86
1160 bool "Legacy VM86 support"
1164 This option allows user programs to put the CPU into V8086
1165 mode, which is an 80286-era approximation of 16-bit real mode.
1167 Some very old versions of X and/or vbetool require this option
1168 for user mode setting. Similarly, DOSEMU will use it if
1169 available to accelerate real mode DOS programs. However, any
1170 recent version of DOSEMU, X, or vbetool should be fully
1171 functional even without kernel VM86 support, as they will all
1172 fall back to software emulation. Nevertheless, if you are using
1173 a 16-bit DOS program where 16-bit performance matters, vm86
1174 mode might be faster than emulation and you might want to
1177 Note that any app that works on a 64-bit kernel is unlikely to
1178 need this option, as 64-bit kernels don't, and can't, support
1179 V8086 mode. This option is also unrelated to 16-bit protected
1180 mode and is not needed to run most 16-bit programs under Wine.
1182 Enabling this option increases the complexity of the kernel
1183 and slows down exception handling a tiny bit.
1185 If unsure, say N here.
1189 default X86_LEGACY_VM86
1192 bool "Enable support for 16-bit segments" if EXPERT
1194 depends on MODIFY_LDT_SYSCALL
1196 This option is required by programs like Wine to run 16-bit
1197 protected mode legacy code on x86 processors. Disabling
1198 this option saves about 300 bytes on i386, or around 6K text
1199 plus 16K runtime memory on x86-64,
1203 depends on X86_16BIT && X86_32
1207 depends on X86_16BIT && X86_64
1209 config X86_VSYSCALL_EMULATION
1210 bool "Enable vsyscall emulation" if EXPERT
1214 This enables emulation of the legacy vsyscall page. Disabling
1215 it is roughly equivalent to booting with vsyscall=none, except
1216 that it will also disable the helpful warning if a program
1217 tries to use a vsyscall. With this option set to N, offending
1218 programs will just segfault, citing addresses of the form
1221 This option is required by many programs built before 2013, and
1222 care should be used even with newer programs if set to N.
1224 Disabling this option saves about 7K of kernel size and
1225 possibly 4K of additional runtime pagetable memory.
1228 tristate "Toshiba Laptop support"
1231 This adds a driver to safely access the System Management Mode of
1232 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1233 not work on models with a Phoenix BIOS. The System Management Mode
1234 is used to set the BIOS and power saving options on Toshiba portables.
1236 For information on utilities to make use of this driver see the
1237 Toshiba Linux utilities web site at:
1238 <http://www.buzzard.org.uk/toshiba/>.
1240 Say Y if you intend to run this kernel on a Toshiba portable.
1244 tristate "Dell i8k legacy laptop support"
1246 select SENSORS_DELL_SMM
1248 This option enables legacy /proc/i8k userspace interface in hwmon
1249 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1250 temperature and allows controlling fan speeds of Dell laptops via
1251 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1252 it reports also power and hotkey status. For fan speed control is
1253 needed userspace package i8kutils.
1255 Say Y if you intend to run this kernel on old Dell laptops or want to
1256 use userspace package i8kutils.
1259 config X86_REBOOTFIXUPS
1260 bool "Enable X86 board specific fixups for reboot"
1263 This enables chipset and/or board specific fixups to be done
1264 in order to get reboot to work correctly. This is only needed on
1265 some combinations of hardware and BIOS. The symptom, for which
1266 this config is intended, is when reboot ends with a stalled/hung
1269 Currently, the only fixup is for the Geode machines using
1270 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1272 Say Y if you want to enable the fixup. Currently, it's safe to
1273 enable this option even if you don't need it.
1277 bool "CPU microcode loading support"
1279 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1282 If you say Y here, you will be able to update the microcode on
1283 Intel and AMD processors. The Intel support is for the IA32 family,
1284 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1285 AMD support is for families 0x10 and later. You will obviously need
1286 the actual microcode binary data itself which is not shipped with
1289 The preferred method to load microcode from a detached initrd is described
1290 in Documentation/x86/microcode.txt. For that you need to enable
1291 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1292 initrd for microcode blobs.
1294 In addition, you can build the microcode into the kernel. For that you
1295 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1298 config MICROCODE_INTEL
1299 bool "Intel microcode loading support"
1300 depends on MICROCODE
1304 This options enables microcode patch loading support for Intel
1307 For the current Intel microcode data package go to
1308 <https://downloadcenter.intel.com> and search for
1309 'Linux Processor Microcode Data File'.
1311 config MICROCODE_AMD
1312 bool "AMD microcode loading support"
1313 depends on MICROCODE
1316 If you select this option, microcode patch loading support for AMD
1317 processors will be enabled.
1319 config MICROCODE_OLD_INTERFACE
1321 depends on MICROCODE
1324 tristate "/dev/cpu/*/msr - Model-specific register support"
1326 This device gives privileged processes access to the x86
1327 Model-Specific Registers (MSRs). It is a character device with
1328 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1329 MSR accesses are directed to a specific CPU on multi-processor
1333 tristate "/dev/cpu/*/cpuid - CPU information support"
1335 This device gives processes access to the x86 CPUID instruction to
1336 be executed on a specific processor. It is a character device
1337 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1341 prompt "High Memory Support"
1348 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1349 However, the address space of 32-bit x86 processors is only 4
1350 Gigabytes large. That means that, if you have a large amount of
1351 physical memory, not all of it can be "permanently mapped" by the
1352 kernel. The physical memory that's not permanently mapped is called
1355 If you are compiling a kernel which will never run on a machine with
1356 more than 1 Gigabyte total physical RAM, answer "off" here (default
1357 choice and suitable for most users). This will result in a "3GB/1GB"
1358 split: 3GB are mapped so that each process sees a 3GB virtual memory
1359 space and the remaining part of the 4GB virtual memory space is used
1360 by the kernel to permanently map as much physical memory as
1363 If the machine has between 1 and 4 Gigabytes physical RAM, then
1366 If more than 4 Gigabytes is used then answer "64GB" here. This
1367 selection turns Intel PAE (Physical Address Extension) mode on.
1368 PAE implements 3-level paging on IA32 processors. PAE is fully
1369 supported by Linux, PAE mode is implemented on all recent Intel
1370 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1371 then the kernel will not boot on CPUs that don't support PAE!
1373 The actual amount of total physical memory will either be
1374 auto detected or can be forced by using a kernel command line option
1375 such as "mem=256M". (Try "man bootparam" or see the documentation of
1376 your boot loader (lilo or loadlin) about how to pass options to the
1377 kernel at boot time.)
1379 If unsure, say "off".
1384 Select this if you have a 32-bit processor and between 1 and 4
1385 gigabytes of physical RAM.
1389 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1392 Select this if you have a 32-bit processor and more than 4
1393 gigabytes of physical RAM.
1398 prompt "Memory split" if EXPERT
1402 Select the desired split between kernel and user memory.
1404 If the address range available to the kernel is less than the
1405 physical memory installed, the remaining memory will be available
1406 as "high memory". Accessing high memory is a little more costly
1407 than low memory, as it needs to be mapped into the kernel first.
1408 Note that increasing the kernel address space limits the range
1409 available to user programs, making the address space there
1410 tighter. Selecting anything other than the default 3G/1G split
1411 will also likely make your kernel incompatible with binary-only
1414 If you are not absolutely sure what you are doing, leave this
1418 bool "3G/1G user/kernel split"
1419 config VMSPLIT_3G_OPT
1421 bool "3G/1G user/kernel split (for full 1G low memory)"
1423 bool "2G/2G user/kernel split"
1424 config VMSPLIT_2G_OPT
1426 bool "2G/2G user/kernel split (for full 2G low memory)"
1428 bool "1G/3G user/kernel split"
1433 default 0xB0000000 if VMSPLIT_3G_OPT
1434 default 0x80000000 if VMSPLIT_2G
1435 default 0x78000000 if VMSPLIT_2G_OPT
1436 default 0x40000000 if VMSPLIT_1G
1442 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1445 bool "PAE (Physical Address Extension) Support"
1446 depends on X86_32 && !HIGHMEM4G
1447 select PHYS_ADDR_T_64BIT
1450 PAE is required for NX support, and furthermore enables
1451 larger swapspace support for non-overcommit purposes. It
1452 has the cost of more pagetable lookup overhead, and also
1453 consumes more pagetable space per process.
1456 bool "Enable 5-level page tables support"
1457 select DYNAMIC_MEMORY_LAYOUT
1458 select SPARSEMEM_VMEMMAP
1461 5-level paging enables access to larger address space:
1462 upto 128 PiB of virtual address space and 4 PiB of
1463 physical address space.
1465 It will be supported by future Intel CPUs.
1467 A kernel with the option enabled can be booted on machines that
1468 support 4- or 5-level paging.
1470 See Documentation/x86/x86_64/5level-paging.txt for more
1475 config X86_DIRECT_GBPAGES
1477 depends on X86_64 && !DEBUG_PAGEALLOC
1479 Certain kernel features effectively disable kernel
1480 linear 1 GB mappings (even if the CPU otherwise
1481 supports them), so don't confuse the user by printing
1482 that we have them enabled.
1484 config ARCH_HAS_MEM_ENCRYPT
1487 config AMD_MEM_ENCRYPT
1488 bool "AMD Secure Memory Encryption (SME) support"
1489 depends on X86_64 && CPU_SUP_AMD
1490 select DYNAMIC_PHYSICAL_MASK
1492 Say yes to enable support for the encryption of system memory.
1493 This requires an AMD processor that supports Secure Memory
1496 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1497 bool "Activate AMD Secure Memory Encryption (SME) by default"
1499 depends on AMD_MEM_ENCRYPT
1501 Say yes to have system memory encrypted by default if running on
1502 an AMD processor that supports Secure Memory Encryption (SME).
1504 If set to Y, then the encryption of system memory can be
1505 deactivated with the mem_encrypt=off command line option.
1507 If set to N, then the encryption of system memory can be
1508 activated with the mem_encrypt=on command line option.
1510 config ARCH_USE_MEMREMAP_PROT
1512 depends on AMD_MEM_ENCRYPT
1514 # Common NUMA Features
1516 bool "Numa Memory Allocation and Scheduler Support"
1518 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1519 default y if X86_BIGSMP
1521 Enable NUMA (Non Uniform Memory Access) support.
1523 The kernel will try to allocate memory used by a CPU on the
1524 local memory controller of the CPU and add some more
1525 NUMA awareness to the kernel.
1527 For 64-bit this is recommended if the system is Intel Core i7
1528 (or later), AMD Opteron, or EM64T NUMA.
1530 For 32-bit this is only needed if you boot a 32-bit
1531 kernel on a 64-bit NUMA platform.
1533 Otherwise, you should say N.
1537 prompt "Old style AMD Opteron NUMA detection"
1538 depends on X86_64 && NUMA && PCI
1540 Enable AMD NUMA node topology detection. You should say Y here if
1541 you have a multi processor AMD system. This uses an old method to
1542 read the NUMA configuration directly from the builtin Northbridge
1543 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1544 which also takes priority if both are compiled in.
1546 config X86_64_ACPI_NUMA
1548 prompt "ACPI NUMA detection"
1549 depends on X86_64 && NUMA && ACPI && PCI
1552 Enable ACPI SRAT based node topology detection.
1554 # Some NUMA nodes have memory ranges that span
1555 # other nodes. Even though a pfn is valid and
1556 # between a node's start and end pfns, it may not
1557 # reside on that node. See memmap_init_zone()
1559 config NODES_SPAN_OTHER_NODES
1561 depends on X86_64_ACPI_NUMA
1564 bool "NUMA emulation"
1567 Enable NUMA emulation. A flat machine will be split
1568 into virtual nodes when booted with "numa=fake=N", where N is the
1569 number of nodes. This is only useful for debugging.
1572 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1574 default "10" if MAXSMP
1575 default "6" if X86_64
1577 depends on NEED_MULTIPLE_NODES
1579 Specify the maximum number of NUMA Nodes available on the target
1580 system. Increases memory reserved to accommodate various tables.
1582 config ARCH_HAVE_MEMORY_PRESENT
1584 depends on X86_32 && DISCONTIGMEM
1586 config ARCH_FLATMEM_ENABLE
1588 depends on X86_32 && !NUMA
1590 config ARCH_DISCONTIGMEM_ENABLE
1592 depends on NUMA && X86_32
1594 config ARCH_DISCONTIGMEM_DEFAULT
1596 depends on NUMA && X86_32
1598 config ARCH_SPARSEMEM_ENABLE
1600 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1601 select SPARSEMEM_STATIC if X86_32
1602 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1604 config ARCH_SPARSEMEM_DEFAULT
1608 config ARCH_SELECT_MEMORY_MODEL
1610 depends on ARCH_SPARSEMEM_ENABLE
1612 config ARCH_MEMORY_PROBE
1613 bool "Enable sysfs memory/probe interface"
1614 depends on X86_64 && MEMORY_HOTPLUG
1616 This option enables a sysfs memory/probe interface for testing.
1617 See Documentation/memory-hotplug.txt for more information.
1618 If you are unsure how to answer this question, answer N.
1620 config ARCH_PROC_KCORE_TEXT
1622 depends on X86_64 && PROC_KCORE
1624 config ILLEGAL_POINTER_VALUE
1627 default 0xdead000000000000 if X86_64
1629 config X86_PMEM_LEGACY_DEVICE
1632 config X86_PMEM_LEGACY
1633 tristate "Support non-standard NVDIMMs and ADR protected memory"
1634 depends on PHYS_ADDR_T_64BIT
1636 select X86_PMEM_LEGACY_DEVICE
1639 Treat memory marked using the non-standard e820 type of 12 as used
1640 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1641 The kernel will offer these regions to the 'pmem' driver so
1642 they can be used for persistent storage.
1647 bool "Allocate 3rd-level pagetables from highmem"
1650 The VM uses one page table entry for each page of physical memory.
1651 For systems with a lot of RAM, this can be wasteful of precious
1652 low memory. Setting this option will put user-space page table
1653 entries in high memory.
1655 config X86_CHECK_BIOS_CORRUPTION
1656 bool "Check for low memory corruption"
1658 Periodically check for memory corruption in low memory, which
1659 is suspected to be caused by BIOS. Even when enabled in the
1660 configuration, it is disabled at runtime. Enable it by
1661 setting "memory_corruption_check=1" on the kernel command
1662 line. By default it scans the low 64k of memory every 60
1663 seconds; see the memory_corruption_check_size and
1664 memory_corruption_check_period parameters in
1665 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1667 When enabled with the default parameters, this option has
1668 almost no overhead, as it reserves a relatively small amount
1669 of memory and scans it infrequently. It both detects corruption
1670 and prevents it from affecting the running system.
1672 It is, however, intended as a diagnostic tool; if repeatable
1673 BIOS-originated corruption always affects the same memory,
1674 you can use memmap= to prevent the kernel from using that
1677 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1678 bool "Set the default setting of memory_corruption_check"
1679 depends on X86_CHECK_BIOS_CORRUPTION
1682 Set whether the default state of memory_corruption_check is
1685 config X86_RESERVE_LOW
1686 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1690 Specify the amount of low memory to reserve for the BIOS.
1692 The first page contains BIOS data structures that the kernel
1693 must not use, so that page must always be reserved.
1695 By default we reserve the first 64K of physical RAM, as a
1696 number of BIOSes are known to corrupt that memory range
1697 during events such as suspend/resume or monitor cable
1698 insertion, so it must not be used by the kernel.
1700 You can set this to 4 if you are absolutely sure that you
1701 trust the BIOS to get all its memory reservations and usages
1702 right. If you know your BIOS have problems beyond the
1703 default 64K area, you can set this to 640 to avoid using the
1704 entire low memory range.
1706 If you have doubts about the BIOS (e.g. suspend/resume does
1707 not work or there's kernel crashes after certain hardware
1708 hotplug events) then you might want to enable
1709 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1710 typical corruption patterns.
1712 Leave this to the default value of 64 if you are unsure.
1714 config MATH_EMULATION
1716 depends on MODIFY_LDT_SYSCALL
1717 prompt "Math emulation" if X86_32
1719 Linux can emulate a math coprocessor (used for floating point
1720 operations) if you don't have one. 486DX and Pentium processors have
1721 a math coprocessor built in, 486SX and 386 do not, unless you added
1722 a 487DX or 387, respectively. (The messages during boot time can
1723 give you some hints here ["man dmesg"].) Everyone needs either a
1724 coprocessor or this emulation.
1726 If you don't have a math coprocessor, you need to say Y here; if you
1727 say Y here even though you have a coprocessor, the coprocessor will
1728 be used nevertheless. (This behavior can be changed with the kernel
1729 command line option "no387", which comes handy if your coprocessor
1730 is broken. Try "man bootparam" or see the documentation of your boot
1731 loader (lilo or loadlin) about how to pass options to the kernel at
1732 boot time.) This means that it is a good idea to say Y here if you
1733 intend to use this kernel on different machines.
1735 More information about the internals of the Linux math coprocessor
1736 emulation can be found in <file:arch/x86/math-emu/README>.
1738 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1739 kernel, it won't hurt.
1743 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1745 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1746 the Memory Type Range Registers (MTRRs) may be used to control
1747 processor access to memory ranges. This is most useful if you have
1748 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1749 allows bus write transfers to be combined into a larger transfer
1750 before bursting over the PCI/AGP bus. This can increase performance
1751 of image write operations 2.5 times or more. Saying Y here creates a
1752 /proc/mtrr file which may be used to manipulate your processor's
1753 MTRRs. Typically the X server should use this.
1755 This code has a reasonably generic interface so that similar
1756 control registers on other processors can be easily supported
1759 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1760 Registers (ARRs) which provide a similar functionality to MTRRs. For
1761 these, the ARRs are used to emulate the MTRRs.
1762 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1763 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1764 write-combining. All of these processors are supported by this code
1765 and it makes sense to say Y here if you have one of them.
1767 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1768 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1769 can lead to all sorts of problems, so it's good to say Y here.
1771 You can safely say Y even if your machine doesn't have MTRRs, you'll
1772 just add about 9 KB to your kernel.
1774 See <file:Documentation/x86/mtrr.txt> for more information.
1776 config MTRR_SANITIZER
1778 prompt "MTRR cleanup support"
1781 Convert MTRR layout from continuous to discrete, so X drivers can
1782 add writeback entries.
1784 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1785 The largest mtrr entry size for a continuous block can be set with
1790 config MTRR_SANITIZER_ENABLE_DEFAULT
1791 int "MTRR cleanup enable value (0-1)"
1794 depends on MTRR_SANITIZER
1796 Enable mtrr cleanup default value
1798 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1799 int "MTRR cleanup spare reg num (0-7)"
1802 depends on MTRR_SANITIZER
1804 mtrr cleanup spare entries default, it can be changed via
1805 mtrr_spare_reg_nr=N on the kernel command line.
1809 prompt "x86 PAT support" if EXPERT
1812 Use PAT attributes to setup page level cache control.
1814 PATs are the modern equivalents of MTRRs and are much more
1815 flexible than MTRRs.
1817 Say N here if you see bootup problems (boot crash, boot hang,
1818 spontaneous reboots) or a non-working video driver.
1822 config ARCH_USES_PG_UNCACHED
1828 prompt "x86 architectural random number generator" if EXPERT
1830 Enable the x86 architectural RDRAND instruction
1831 (Intel Bull Mountain technology) to generate random numbers.
1832 If supported, this is a high bandwidth, cryptographically
1833 secure hardware random number generator.
1837 prompt "Supervisor Mode Access Prevention" if EXPERT
1839 Supervisor Mode Access Prevention (SMAP) is a security
1840 feature in newer Intel processors. There is a small
1841 performance cost if this enabled and turned on; there is
1842 also a small increase in the kernel size if this is enabled.
1846 config X86_INTEL_UMIP
1848 depends on CPU_SUP_INTEL
1849 prompt "Intel User Mode Instruction Prevention" if EXPERT
1851 The User Mode Instruction Prevention (UMIP) is a security
1852 feature in newer Intel processors. If enabled, a general
1853 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1854 or STR instructions are executed in user mode. These instructions
1855 unnecessarily expose information about the hardware state.
1857 The vast majority of applications do not use these instructions.
1858 For the very few that do, software emulation is provided in
1859 specific cases in protected and virtual-8086 modes. Emulated
1862 config X86_INTEL_MPX
1863 prompt "Intel MPX (Memory Protection Extensions)"
1865 # Note: only available in 64-bit mode due to VMA flags shortage
1866 depends on CPU_SUP_INTEL && X86_64
1867 select ARCH_USES_HIGH_VMA_FLAGS
1869 MPX provides hardware features that can be used in
1870 conjunction with compiler-instrumented code to check
1871 memory references. It is designed to detect buffer
1872 overflow or underflow bugs.
1874 This option enables running applications which are
1875 instrumented or otherwise use MPX. It does not use MPX
1876 itself inside the kernel or to protect the kernel
1877 against bad memory references.
1879 Enabling this option will make the kernel larger:
1880 ~8k of kernel text and 36 bytes of data on a 64-bit
1881 defconfig. It adds a long to the 'mm_struct' which
1882 will increase the kernel memory overhead of each
1883 process and adds some branches to paths used during
1884 exec() and munmap().
1886 For details, see Documentation/x86/intel_mpx.txt
1890 config X86_INTEL_MEMORY_PROTECTION_KEYS
1891 prompt "Intel Memory Protection Keys"
1893 # Note: only available in 64-bit mode
1894 depends on CPU_SUP_INTEL && X86_64
1895 select ARCH_USES_HIGH_VMA_FLAGS
1896 select ARCH_HAS_PKEYS
1898 Memory Protection Keys provides a mechanism for enforcing
1899 page-based protections, but without requiring modification of the
1900 page tables when an application changes protection domains.
1902 For details, see Documentation/x86/protection-keys.txt
1907 bool "EFI runtime service support"
1910 select EFI_RUNTIME_WRAPPERS
1912 This enables the kernel to use EFI runtime services that are
1913 available (such as the EFI variable services).
1915 This option is only useful on systems that have EFI firmware.
1916 In addition, you should use the latest ELILO loader available
1917 at <http://elilo.sourceforge.net> in order to take advantage
1918 of EFI runtime services. However, even with this option, the
1919 resultant kernel should continue to boot on existing non-EFI
1923 bool "EFI stub support"
1924 depends on EFI && !X86_USE_3DNOW
1927 This kernel feature allows a bzImage to be loaded directly
1928 by EFI firmware without the use of a bootloader.
1930 See Documentation/efi-stub.txt for more information.
1933 bool "EFI mixed-mode support"
1934 depends on EFI_STUB && X86_64
1936 Enabling this feature allows a 64-bit kernel to be booted
1937 on a 32-bit firmware, provided that your CPU supports 64-bit
1940 Note that it is not possible to boot a mixed-mode enabled
1941 kernel via the EFI boot stub - a bootloader that supports
1942 the EFI handover protocol must be used.
1948 prompt "Enable seccomp to safely compute untrusted bytecode"
1950 This kernel feature is useful for number crunching applications
1951 that may need to compute untrusted bytecode during their
1952 execution. By using pipes or other transports made available to
1953 the process as file descriptors supporting the read/write
1954 syscalls, it's possible to isolate those applications in
1955 their own address space using seccomp. Once seccomp is
1956 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1957 and the task is only allowed to execute a few safe syscalls
1958 defined by each seccomp mode.
1960 If unsure, say Y. Only embedded should say N here.
1962 source kernel/Kconfig.hz
1965 bool "kexec system call"
1968 kexec is a system call that implements the ability to shutdown your
1969 current kernel, and to start another kernel. It is like a reboot
1970 but it is independent of the system firmware. And like a reboot
1971 you can start any kernel with it, not just Linux.
1973 The name comes from the similarity to the exec system call.
1975 It is an ongoing process to be certain the hardware in a machine
1976 is properly shutdown, so do not be surprised if this code does not
1977 initially work for you. As of this writing the exact hardware
1978 interface is strongly in flux, so no good recommendation can be
1982 bool "kexec file based system call"
1987 depends on CRYPTO_SHA256=y
1989 This is new version of kexec system call. This system call is
1990 file based and takes file descriptors as system call argument
1991 for kernel and initramfs as opposed to list of segments as
1992 accepted by previous system call.
1994 config ARCH_HAS_KEXEC_PURGATORY
1997 config KEXEC_VERIFY_SIG
1998 bool "Verify kernel signature during kexec_file_load() syscall"
1999 depends on KEXEC_FILE
2001 This option makes kernel signature verification mandatory for
2002 the kexec_file_load() syscall.
2004 In addition to that option, you need to enable signature
2005 verification for the corresponding kernel image type being
2006 loaded in order for this to work.
2008 config KEXEC_BZIMAGE_VERIFY_SIG
2009 bool "Enable bzImage signature verification support"
2010 depends on KEXEC_VERIFY_SIG
2011 depends on SIGNED_PE_FILE_VERIFICATION
2012 select SYSTEM_TRUSTED_KEYRING
2014 Enable bzImage signature verification support.
2017 bool "kernel crash dumps"
2018 depends on X86_64 || (X86_32 && HIGHMEM)
2020 Generate crash dump after being started by kexec.
2021 This should be normally only set in special crash dump kernels
2022 which are loaded in the main kernel with kexec-tools into
2023 a specially reserved region and then later executed after
2024 a crash by kdump/kexec. The crash dump kernel must be compiled
2025 to a memory address not used by the main kernel or BIOS using
2026 PHYSICAL_START, or it must be built as a relocatable image
2027 (CONFIG_RELOCATABLE=y).
2028 For more details see Documentation/kdump/kdump.txt
2032 depends on KEXEC && HIBERNATION
2034 Jump between original kernel and kexeced kernel and invoke
2035 code in physical address mode via KEXEC
2037 config PHYSICAL_START
2038 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2041 This gives the physical address where the kernel is loaded.
2043 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2044 bzImage will decompress itself to above physical address and
2045 run from there. Otherwise, bzImage will run from the address where
2046 it has been loaded by the boot loader and will ignore above physical
2049 In normal kdump cases one does not have to set/change this option
2050 as now bzImage can be compiled as a completely relocatable image
2051 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2052 address. This option is mainly useful for the folks who don't want
2053 to use a bzImage for capturing the crash dump and want to use a
2054 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2055 to be specifically compiled to run from a specific memory area
2056 (normally a reserved region) and this option comes handy.
2058 So if you are using bzImage for capturing the crash dump,
2059 leave the value here unchanged to 0x1000000 and set
2060 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2061 for capturing the crash dump change this value to start of
2062 the reserved region. In other words, it can be set based on
2063 the "X" value as specified in the "crashkernel=YM@XM"
2064 command line boot parameter passed to the panic-ed
2065 kernel. Please take a look at Documentation/kdump/kdump.txt
2066 for more details about crash dumps.
2068 Usage of bzImage for capturing the crash dump is recommended as
2069 one does not have to build two kernels. Same kernel can be used
2070 as production kernel and capture kernel. Above option should have
2071 gone away after relocatable bzImage support is introduced. But it
2072 is present because there are users out there who continue to use
2073 vmlinux for dump capture. This option should go away down the
2076 Don't change this unless you know what you are doing.
2079 bool "Build a relocatable kernel"
2082 This builds a kernel image that retains relocation information
2083 so it can be loaded someplace besides the default 1MB.
2084 The relocations tend to make the kernel binary about 10% larger,
2085 but are discarded at runtime.
2087 One use is for the kexec on panic case where the recovery kernel
2088 must live at a different physical address than the primary
2091 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2092 it has been loaded at and the compile time physical address
2093 (CONFIG_PHYSICAL_START) is used as the minimum location.
2095 config RANDOMIZE_BASE
2096 bool "Randomize the address of the kernel image (KASLR)"
2097 depends on RELOCATABLE
2100 In support of Kernel Address Space Layout Randomization (KASLR),
2101 this randomizes the physical address at which the kernel image
2102 is decompressed and the virtual address where the kernel
2103 image is mapped, as a security feature that deters exploit
2104 attempts relying on knowledge of the location of kernel
2107 On 64-bit, the kernel physical and virtual addresses are
2108 randomized separately. The physical address will be anywhere
2109 between 16MB and the top of physical memory (up to 64TB). The
2110 virtual address will be randomized from 16MB up to 1GB (9 bits
2111 of entropy). Note that this also reduces the memory space
2112 available to kernel modules from 1.5GB to 1GB.
2114 On 32-bit, the kernel physical and virtual addresses are
2115 randomized together. They will be randomized from 16MB up to
2116 512MB (8 bits of entropy).
2118 Entropy is generated using the RDRAND instruction if it is
2119 supported. If RDTSC is supported, its value is mixed into
2120 the entropy pool as well. If neither RDRAND nor RDTSC are
2121 supported, then entropy is read from the i8254 timer. The
2122 usable entropy is limited by the kernel being built using
2123 2GB addressing, and that PHYSICAL_ALIGN must be at a
2124 minimum of 2MB. As a result, only 10 bits of entropy are
2125 theoretically possible, but the implementations are further
2126 limited due to memory layouts.
2130 # Relocation on x86 needs some additional build support
2131 config X86_NEED_RELOCS
2133 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2135 config PHYSICAL_ALIGN
2136 hex "Alignment value to which kernel should be aligned"
2138 range 0x2000 0x1000000 if X86_32
2139 range 0x200000 0x1000000 if X86_64
2141 This value puts the alignment restrictions on physical address
2142 where kernel is loaded and run from. Kernel is compiled for an
2143 address which meets above alignment restriction.
2145 If bootloader loads the kernel at a non-aligned address and
2146 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2147 address aligned to above value and run from there.
2149 If bootloader loads the kernel at a non-aligned address and
2150 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2151 load address and decompress itself to the address it has been
2152 compiled for and run from there. The address for which kernel is
2153 compiled already meets above alignment restrictions. Hence the
2154 end result is that kernel runs from a physical address meeting
2155 above alignment restrictions.
2157 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2158 this value must be a multiple of 0x200000.
2160 Don't change this unless you know what you are doing.
2162 config DYNAMIC_MEMORY_LAYOUT
2165 This option makes base addresses of vmalloc and vmemmap as well as
2166 __PAGE_OFFSET movable during boot.
2168 config RANDOMIZE_MEMORY
2169 bool "Randomize the kernel memory sections"
2171 depends on RANDOMIZE_BASE
2172 select DYNAMIC_MEMORY_LAYOUT
2173 default RANDOMIZE_BASE
2175 Randomizes the base virtual address of kernel memory sections
2176 (physical memory mapping, vmalloc & vmemmap). This security feature
2177 makes exploits relying on predictable memory locations less reliable.
2179 The order of allocations remains unchanged. Entropy is generated in
2180 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2181 configuration have in average 30,000 different possible virtual
2182 addresses for each memory section.
2186 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2187 hex "Physical memory mapping padding" if EXPERT
2188 depends on RANDOMIZE_MEMORY
2189 default "0xa" if MEMORY_HOTPLUG
2191 range 0x1 0x40 if MEMORY_HOTPLUG
2194 Define the padding in terabytes added to the existing physical
2195 memory size during kernel memory randomization. It is useful
2196 for memory hotplug support but reduces the entropy available for
2197 address randomization.
2199 If unsure, leave at the default value.
2205 config BOOTPARAM_HOTPLUG_CPU0
2206 bool "Set default setting of cpu0_hotpluggable"
2208 depends on HOTPLUG_CPU
2210 Set whether default state of cpu0_hotpluggable is on or off.
2212 Say Y here to enable CPU0 hotplug by default. If this switch
2213 is turned on, there is no need to give cpu0_hotplug kernel
2214 parameter and the CPU0 hotplug feature is enabled by default.
2216 Please note: there are two known CPU0 dependencies if you want
2217 to enable the CPU0 hotplug feature either by this switch or by
2218 cpu0_hotplug kernel parameter.
2220 First, resume from hibernate or suspend always starts from CPU0.
2221 So hibernate and suspend are prevented if CPU0 is offline.
2223 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2224 offline if any interrupt can not migrate out of CPU0. There may
2225 be other CPU0 dependencies.
2227 Please make sure the dependencies are under your control before
2228 you enable this feature.
2230 Say N if you don't want to enable CPU0 hotplug feature by default.
2231 You still can enable the CPU0 hotplug feature at boot by kernel
2232 parameter cpu0_hotplug.
2234 config DEBUG_HOTPLUG_CPU0
2236 prompt "Debug CPU0 hotplug"
2237 depends on HOTPLUG_CPU
2239 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2240 soon as possible and boots up userspace with CPU0 offlined. User
2241 can online CPU0 back after boot time.
2243 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2244 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2245 compilation or giving cpu0_hotplug kernel parameter at boot.
2251 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2252 depends on COMPAT_32
2254 Certain buggy versions of glibc will crash if they are
2255 presented with a 32-bit vDSO that is not mapped at the address
2256 indicated in its segment table.
2258 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2259 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2260 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2261 the only released version with the bug, but OpenSUSE 9
2262 contains a buggy "glibc 2.3.2".
2264 The symptom of the bug is that everything crashes on startup, saying:
2265 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2267 Saying Y here changes the default value of the vdso32 boot
2268 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2269 This works around the glibc bug but hurts performance.
2271 If unsure, say N: if you are compiling your own kernel, you
2272 are unlikely to be using a buggy version of glibc.
2275 prompt "vsyscall table for legacy applications"
2277 default LEGACY_VSYSCALL_EMULATE
2279 Legacy user code that does not know how to find the vDSO expects
2280 to be able to issue three syscalls by calling fixed addresses in
2281 kernel space. Since this location is not randomized with ASLR,
2282 it can be used to assist security vulnerability exploitation.
2284 This setting can be changed at boot time via the kernel command
2285 line parameter vsyscall=[emulate|none].
2287 On a system with recent enough glibc (2.14 or newer) and no
2288 static binaries, you can say None without a performance penalty
2289 to improve security.
2291 If unsure, select "Emulate".
2293 config LEGACY_VSYSCALL_EMULATE
2296 The kernel traps and emulates calls into the fixed
2297 vsyscall address mapping. This makes the mapping
2298 non-executable, but it still contains known contents,
2299 which could be used in certain rare security vulnerability
2300 exploits. This configuration is recommended when userspace
2301 still uses the vsyscall area.
2303 config LEGACY_VSYSCALL_NONE
2306 There will be no vsyscall mapping at all. This will
2307 eliminate any risk of ASLR bypass due to the vsyscall
2308 fixed address mapping. Attempts to use the vsyscalls
2309 will be reported to dmesg, so that either old or
2310 malicious userspace programs can be identified.
2315 bool "Built-in kernel command line"
2317 Allow for specifying boot arguments to the kernel at
2318 build time. On some systems (e.g. embedded ones), it is
2319 necessary or convenient to provide some or all of the
2320 kernel boot arguments with the kernel itself (that is,
2321 to not rely on the boot loader to provide them.)
2323 To compile command line arguments into the kernel,
2324 set this option to 'Y', then fill in the
2325 boot arguments in CONFIG_CMDLINE.
2327 Systems with fully functional boot loaders (i.e. non-embedded)
2328 should leave this option set to 'N'.
2331 string "Built-in kernel command string"
2332 depends on CMDLINE_BOOL
2335 Enter arguments here that should be compiled into the kernel
2336 image and used at boot time. If the boot loader provides a
2337 command line at boot time, it is appended to this string to
2338 form the full kernel command line, when the system boots.
2340 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2341 change this behavior.
2343 In most cases, the command line (whether built-in or provided
2344 by the boot loader) should specify the device for the root
2347 config CMDLINE_OVERRIDE
2348 bool "Built-in command line overrides boot loader arguments"
2349 depends on CMDLINE_BOOL
2351 Set this option to 'Y' to have the kernel ignore the boot loader
2352 command line, and use ONLY the built-in command line.
2354 This is used to work around broken boot loaders. This should
2355 be set to 'N' under normal conditions.
2357 config MODIFY_LDT_SYSCALL
2358 bool "Enable the LDT (local descriptor table)" if EXPERT
2361 Linux can allow user programs to install a per-process x86
2362 Local Descriptor Table (LDT) using the modify_ldt(2) system
2363 call. This is required to run 16-bit or segmented code such as
2364 DOSEMU or some Wine programs. It is also used by some very old
2365 threading libraries.
2367 Enabling this feature adds a small amount of overhead to
2368 context switches and increases the low-level kernel attack
2369 surface. Disabling it removes the modify_ldt(2) system call.
2371 Saying 'N' here may make sense for embedded or server kernels.
2373 source "kernel/livepatch/Kconfig"
2377 config ARCH_HAS_ADD_PAGES
2379 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2381 config ARCH_ENABLE_MEMORY_HOTPLUG
2383 depends on X86_64 || (X86_32 && HIGHMEM)
2385 config ARCH_ENABLE_MEMORY_HOTREMOVE
2387 depends on MEMORY_HOTPLUG
2389 config USE_PERCPU_NUMA_NODE_ID
2393 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2395 depends on X86_64 || X86_PAE
2397 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2399 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2401 config ARCH_ENABLE_THP_MIGRATION
2403 depends on X86_64 && TRANSPARENT_HUGEPAGE
2405 menu "Power management and ACPI options"
2407 config ARCH_HIBERNATION_HEADER
2409 depends on X86_64 && HIBERNATION
2411 source "kernel/power/Kconfig"
2413 source "drivers/acpi/Kconfig"
2415 source "drivers/sfi/Kconfig"
2422 tristate "APM (Advanced Power Management) BIOS support"
2423 depends on X86_32 && PM_SLEEP
2425 APM is a BIOS specification for saving power using several different
2426 techniques. This is mostly useful for battery powered laptops with
2427 APM compliant BIOSes. If you say Y here, the system time will be
2428 reset after a RESUME operation, the /proc/apm device will provide
2429 battery status information, and user-space programs will receive
2430 notification of APM "events" (e.g. battery status change).
2432 If you select "Y" here, you can disable actual use of the APM
2433 BIOS by passing the "apm=off" option to the kernel at boot time.
2435 Note that the APM support is almost completely disabled for
2436 machines with more than one CPU.
2438 In order to use APM, you will need supporting software. For location
2439 and more information, read <file:Documentation/power/apm-acpi.txt>
2440 and the Battery Powered Linux mini-HOWTO, available from
2441 <http://www.tldp.org/docs.html#howto>.
2443 This driver does not spin down disk drives (see the hdparm(8)
2444 manpage ("man 8 hdparm") for that), and it doesn't turn off
2445 VESA-compliant "green" monitors.
2447 This driver does not support the TI 4000M TravelMate and the ACER
2448 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2449 desktop machines also don't have compliant BIOSes, and this driver
2450 may cause those machines to panic during the boot phase.
2452 Generally, if you don't have a battery in your machine, there isn't
2453 much point in using this driver and you should say N. If you get
2454 random kernel OOPSes or reboots that don't seem to be related to
2455 anything, try disabling/enabling this option (or disabling/enabling
2458 Some other things you should try when experiencing seemingly random,
2461 1) make sure that you have enough swap space and that it is
2463 2) pass the "no-hlt" option to the kernel
2464 3) switch on floating point emulation in the kernel and pass
2465 the "no387" option to the kernel
2466 4) pass the "floppy=nodma" option to the kernel
2467 5) pass the "mem=4M" option to the kernel (thereby disabling
2468 all but the first 4 MB of RAM)
2469 6) make sure that the CPU is not over clocked.
2470 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2471 8) disable the cache from your BIOS settings
2472 9) install a fan for the video card or exchange video RAM
2473 10) install a better fan for the CPU
2474 11) exchange RAM chips
2475 12) exchange the motherboard.
2477 To compile this driver as a module, choose M here: the
2478 module will be called apm.
2482 config APM_IGNORE_USER_SUSPEND
2483 bool "Ignore USER SUSPEND"
2485 This option will ignore USER SUSPEND requests. On machines with a
2486 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2487 series notebooks, it is necessary to say Y because of a BIOS bug.
2489 config APM_DO_ENABLE
2490 bool "Enable PM at boot time"
2492 Enable APM features at boot time. From page 36 of the APM BIOS
2493 specification: "When disabled, the APM BIOS does not automatically
2494 power manage devices, enter the Standby State, enter the Suspend
2495 State, or take power saving steps in response to CPU Idle calls."
2496 This driver will make CPU Idle calls when Linux is idle (unless this
2497 feature is turned off -- see "Do CPU IDLE calls", below). This
2498 should always save battery power, but more complicated APM features
2499 will be dependent on your BIOS implementation. You may need to turn
2500 this option off if your computer hangs at boot time when using APM
2501 support, or if it beeps continuously instead of suspending. Turn
2502 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2503 T400CDT. This is off by default since most machines do fine without
2508 bool "Make CPU Idle calls when idle"
2510 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2511 On some machines, this can activate improved power savings, such as
2512 a slowed CPU clock rate, when the machine is idle. These idle calls
2513 are made after the idle loop has run for some length of time (e.g.,
2514 333 mS). On some machines, this will cause a hang at boot time or
2515 whenever the CPU becomes idle. (On machines with more than one CPU,
2516 this option does nothing.)
2518 config APM_DISPLAY_BLANK
2519 bool "Enable console blanking using APM"
2521 Enable console blanking using the APM. Some laptops can use this to
2522 turn off the LCD backlight when the screen blanker of the Linux
2523 virtual console blanks the screen. Note that this is only used by
2524 the virtual console screen blanker, and won't turn off the backlight
2525 when using the X Window system. This also doesn't have anything to
2526 do with your VESA-compliant power-saving monitor. Further, this
2527 option doesn't work for all laptops -- it might not turn off your
2528 backlight at all, or it might print a lot of errors to the console,
2529 especially if you are using gpm.
2531 config APM_ALLOW_INTS
2532 bool "Allow interrupts during APM BIOS calls"
2534 Normally we disable external interrupts while we are making calls to
2535 the APM BIOS as a measure to lessen the effects of a badly behaving
2536 BIOS implementation. The BIOS should reenable interrupts if it
2537 needs to. Unfortunately, some BIOSes do not -- especially those in
2538 many of the newer IBM Thinkpads. If you experience hangs when you
2539 suspend, try setting this to Y. Otherwise, say N.
2543 source "drivers/cpufreq/Kconfig"
2545 source "drivers/cpuidle/Kconfig"
2547 source "drivers/idle/Kconfig"
2552 menu "Bus options (PCI etc.)"
2558 Find out whether you have a PCI motherboard. PCI is the name of a
2559 bus system, i.e. the way the CPU talks to the other stuff inside
2560 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2561 VESA. If you have PCI, say Y, otherwise N.
2564 prompt "PCI access mode"
2565 depends on X86_32 && PCI
2568 On PCI systems, the BIOS can be used to detect the PCI devices and
2569 determine their configuration. However, some old PCI motherboards
2570 have BIOS bugs and may crash if this is done. Also, some embedded
2571 PCI-based systems don't have any BIOS at all. Linux can also try to
2572 detect the PCI hardware directly without using the BIOS.
2574 With this option, you can specify how Linux should detect the
2575 PCI devices. If you choose "BIOS", the BIOS will be used,
2576 if you choose "Direct", the BIOS won't be used, and if you
2577 choose "MMConfig", then PCI Express MMCONFIG will be used.
2578 If you choose "Any", the kernel will try MMCONFIG, then the
2579 direct access method and falls back to the BIOS if that doesn't
2580 work. If unsure, go with the default, which is "Any".
2585 config PCI_GOMMCONFIG
2602 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2604 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2607 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2610 bool "Support mmconfig PCI config space access" if X86_64
2612 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2613 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2617 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2621 depends on PCI && XEN
2628 config MMCONF_FAM10H
2630 depends on X86_64 && PCI_MMCONFIG && ACPI
2632 config PCI_CNB20LE_QUIRK
2633 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2636 Read the PCI windows out of the CNB20LE host bridge. This allows
2637 PCI hotplug to work on systems with the CNB20LE chipset which do
2640 There's no public spec for this chipset, and this functionality
2641 is known to be incomplete.
2643 You should say N unless you know you need this.
2645 source "drivers/pci/Kconfig"
2648 bool "ISA bus support on modern systems" if EXPERT
2650 Expose ISA bus device drivers and options available for selection and
2651 configuration. Enable this option if your target machine has an ISA
2652 bus. ISA is an older system, displaced by PCI and newer bus
2653 architectures -- if your target machine is modern, it probably does
2654 not have an ISA bus.
2658 # x86_64 have no ISA slots, but can have ISA-style DMA.
2660 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2663 Enables ISA-style DMA support for devices requiring such controllers.
2671 Find out whether you have ISA slots on your motherboard. ISA is the
2672 name of a bus system, i.e. the way the CPU talks to the other stuff
2673 inside your box. Other bus systems are PCI, EISA, MicroChannel
2674 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2675 newer boards don't support it. If you have ISA, say Y, otherwise N.
2681 The Extended Industry Standard Architecture (EISA) bus was
2682 developed as an open alternative to the IBM MicroChannel bus.
2684 The EISA bus provided some of the features of the IBM MicroChannel
2685 bus while maintaining backward compatibility with cards made for
2686 the older ISA bus. The EISA bus saw limited use between 1988 and
2687 1995 when it was made obsolete by the PCI bus.
2689 Say Y here if you are building a kernel for an EISA-based machine.
2693 source "drivers/eisa/Kconfig"
2696 tristate "NatSemi SCx200 support"
2698 This provides basic support for National Semiconductor's
2699 (now AMD's) Geode processors. The driver probes for the
2700 PCI-IDs of several on-chip devices, so its a good dependency
2701 for other scx200_* drivers.
2703 If compiled as a module, the driver is named scx200.
2705 config SCx200HR_TIMER
2706 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2710 This driver provides a clocksource built upon the on-chip
2711 27MHz high-resolution timer. Its also a workaround for
2712 NSC Geode SC-1100's buggy TSC, which loses time when the
2713 processor goes idle (as is done by the scheduler). The
2714 other workaround is idle=poll boot option.
2717 bool "One Laptop Per Child support"
2724 Add support for detecting the unique features of the OLPC
2728 bool "OLPC XO-1 Power Management"
2729 depends on OLPC && MFD_CS5535 && PM_SLEEP
2732 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2735 bool "OLPC XO-1 Real Time Clock"
2736 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2738 Add support for the XO-1 real time clock, which can be used as a
2739 programmable wakeup source.
2742 bool "OLPC XO-1 SCI extras"
2743 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2747 Add support for SCI-based features of the OLPC XO-1 laptop:
2748 - EC-driven system wakeups
2752 - AC adapter status updates
2753 - Battery status updates
2755 config OLPC_XO15_SCI
2756 bool "OLPC XO-1.5 SCI extras"
2757 depends on OLPC && ACPI
2760 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2761 - EC-driven system wakeups
2762 - AC adapter status updates
2763 - Battery status updates
2766 bool "PCEngines ALIX System Support (LED setup)"
2769 This option enables system support for the PCEngines ALIX.
2770 At present this just sets up LEDs for GPIO control on
2771 ALIX2/3/6 boards. However, other system specific setup should
2774 Note: You must still enable the drivers for GPIO and LED support
2775 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2777 Note: You have to set alix.force=1 for boards with Award BIOS.
2780 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2783 This option enables system support for the Soekris Engineering net5501.
2786 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2790 This option enables system support for the Traverse Technologies GEOS.
2793 bool "Technologic Systems TS-5500 platform support"
2795 select CHECK_SIGNATURE
2799 This option enables system support for the Technologic Systems TS-5500.
2805 depends on CPU_SUP_AMD && PCI
2807 source "drivers/pcmcia/Kconfig"
2810 tristate "RapidIO support"
2814 If enabled this option will include drivers and the core
2815 infrastructure code to support RapidIO interconnect devices.
2817 source "drivers/rapidio/Kconfig"
2820 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2822 Firmwares often provide initial graphics framebuffers so the BIOS,
2823 bootloader or kernel can show basic video-output during boot for
2824 user-guidance and debugging. Historically, x86 used the VESA BIOS
2825 Extensions and EFI-framebuffers for this, which are mostly limited
2827 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2828 framebuffers so the new generic system-framebuffer drivers can be
2829 used on x86. If the framebuffer is not compatible with the generic
2830 modes, it is advertised as fallback platform framebuffer so legacy
2831 drivers like efifb, vesafb and uvesafb can pick it up.
2832 If this option is not selected, all system framebuffers are always
2833 marked as fallback platform framebuffers as usual.
2835 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2836 not be able to pick up generic system framebuffers if this option
2837 is selected. You are highly encouraged to enable simplefb as
2838 replacement if you select this option. simplefb can correctly deal
2839 with generic system framebuffers. But you should still keep vesafb
2840 and others enabled as fallback if a system framebuffer is
2841 incompatible with simplefb.
2848 menu "Binary Emulations"
2850 config IA32_EMULATION
2851 bool "IA32 Emulation"
2853 select ARCH_WANT_OLD_COMPAT_IPC
2855 select COMPAT_BINFMT_ELF
2856 select COMPAT_OLD_SIGACTION
2858 Include code to run legacy 32-bit programs under a
2859 64-bit kernel. You should likely turn this on, unless you're
2860 100% sure that you don't have any 32-bit programs left.
2863 tristate "IA32 a.out support"
2864 depends on IA32_EMULATION
2866 Support old a.out binaries in the 32bit emulation.
2869 bool "x32 ABI for 64-bit mode"
2872 Include code to run binaries for the x32 native 32-bit ABI
2873 for 64-bit processors. An x32 process gets access to the
2874 full 64-bit register file and wide data path while leaving
2875 pointers at 32 bits for smaller memory footprint.
2877 You will need a recent binutils (2.22 or later) with
2878 elf32_x86_64 support enabled to compile a kernel with this
2883 depends on IA32_EMULATION || X86_32
2885 select OLD_SIGSUSPEND3
2889 depends on IA32_EMULATION || X86_X32
2892 config COMPAT_FOR_U64_ALIGNMENT
2895 config SYSVIPC_COMPAT
2903 config HAVE_ATOMIC_IOMAP
2907 config X86_DEV_DMA_OPS
2909 depends on X86_64 || STA2X11
2911 config X86_DMA_REMAP
2915 config HAVE_GENERIC_GUP
2918 source "drivers/firmware/Kconfig"
2920 source "arch/x86/kvm/Kconfig"