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 config CC_HAS_SANE_STACKPROTECTOR
352 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
353 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
355 We have to make sure stack protector is unconditionally disabled if
356 the compiler produces broken code.
358 menu "Processor type and features"
361 bool "DMA memory allocation support" if EXPERT
364 DMA memory allocation support allows devices with less than 32-bit
365 addressing to allocate within the first 16MB of address space.
366 Disable if no such devices will be used.
371 bool "Symmetric multi-processing support"
373 This enables support for systems with more than one CPU. If you have
374 a system with only one CPU, say N. If you have a system with more
377 If you say N here, the kernel will run on uni- and multiprocessor
378 machines, but will use only one CPU of a multiprocessor machine. If
379 you say Y here, the kernel will run on many, but not all,
380 uniprocessor machines. On a uniprocessor machine, the kernel
381 will run faster if you say N here.
383 Note that if you say Y here and choose architecture "586" or
384 "Pentium" under "Processor family", the kernel will not work on 486
385 architectures. Similarly, multiprocessor kernels for the "PPro"
386 architecture may not work on all Pentium based boards.
388 People using multiprocessor machines who say Y here should also say
389 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
390 Management" code will be disabled if you say Y here.
392 See also <file:Documentation/x86/i386/IO-APIC.txt>,
393 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
394 <http://www.tldp.org/docs.html#howto>.
396 If you don't know what to do here, say N.
398 config X86_FEATURE_NAMES
399 bool "Processor feature human-readable names" if EMBEDDED
402 This option compiles in a table of x86 feature bits and corresponding
403 names. This is required to support /proc/cpuinfo and a few kernel
404 messages. You can disable this to save space, at the expense of
405 making those few kernel messages show numeric feature bits instead.
410 bool "Support x2apic"
411 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
413 This enables x2apic support on CPUs that have this feature.
415 This allows 32-bit apic IDs (so it can support very large systems),
416 and accesses the local apic via MSRs not via mmio.
418 If you don't know what to do here, say N.
421 bool "Enable MPS table" if ACPI || SFI
423 depends on X86_LOCAL_APIC
425 For old smp systems that do not have proper acpi support. Newer systems
426 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
430 depends on X86_GOLDFISH
433 bool "Avoid speculative indirect branches in kernel"
435 select STACK_VALIDATION if HAVE_STACK_VALIDATION
437 Compile kernel with the retpoline compiler options to guard against
438 kernel-to-user data leaks by avoiding speculative indirect
439 branches. Requires a compiler with -mindirect-branch=thunk-extern
440 support for full protection. The kernel may run slower.
442 Without compiler support, at least indirect branches in assembler
443 code are eliminated. Since this includes the syscall entry path,
444 it is not entirely pointless.
447 bool "Intel Resource Director Technology support"
449 depends on X86 && CPU_SUP_INTEL
452 Select to enable resource allocation and monitoring which are
453 sub-features of Intel Resource Director Technology(RDT). More
454 information about RDT can be found in the Intel x86
455 Architecture Software Developer Manual.
461 bool "Support for big SMP systems with more than 8 CPUs"
464 This option is needed for the systems that have more than 8 CPUs
466 config X86_EXTENDED_PLATFORM
467 bool "Support for extended (non-PC) x86 platforms"
470 If you disable this option then the kernel will only support
471 standard PC platforms. (which covers the vast majority of
474 If you enable this option then you'll be able to select support
475 for the following (non-PC) 32 bit x86 platforms:
476 Goldfish (Android emulator)
479 SGI 320/540 (Visual Workstation)
480 STA2X11-based (e.g. Northville)
481 Moorestown MID devices
483 If you have one of these systems, or if you want to build a
484 generic distribution kernel, say Y here - otherwise say N.
488 config X86_EXTENDED_PLATFORM
489 bool "Support for extended (non-PC) x86 platforms"
492 If you disable this option then the kernel will only support
493 standard PC platforms. (which covers the vast majority of
496 If you enable this option then you'll be able to select support
497 for the following (non-PC) 64 bit x86 platforms:
502 If you have one of these systems, or if you want to build a
503 generic distribution kernel, say Y here - otherwise say N.
505 # This is an alphabetically sorted list of 64 bit extended platforms
506 # Please maintain the alphabetic order if and when there are additions
508 bool "Numascale NumaChip"
510 depends on X86_EXTENDED_PLATFORM
513 depends on X86_X2APIC
514 depends on PCI_MMCONFIG
516 Adds support for Numascale NumaChip large-SMP systems. Needed to
517 enable more than ~168 cores.
518 If you don't have one of these, you should say N here.
522 select HYPERVISOR_GUEST
524 depends on X86_64 && PCI
525 depends on X86_EXTENDED_PLATFORM
528 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
529 supposed to run on these EM64T-based machines. Only choose this option
530 if you have one of these machines.
533 bool "SGI Ultraviolet"
535 depends on X86_EXTENDED_PLATFORM
538 depends on X86_X2APIC
541 This option is needed in order to support SGI Ultraviolet systems.
542 If you don't have one of these, you should say N here.
544 # Following is an alphabetically sorted list of 32 bit extended platforms
545 # Please maintain the alphabetic order if and when there are additions
548 bool "Goldfish (Virtual Platform)"
549 depends on X86_EXTENDED_PLATFORM
551 Enable support for the Goldfish virtual platform used primarily
552 for Android development. Unless you are building for the Android
553 Goldfish emulator say N here.
556 bool "CE4100 TV platform"
558 depends on PCI_GODIRECT
559 depends on X86_IO_APIC
561 depends on X86_EXTENDED_PLATFORM
562 select X86_REBOOTFIXUPS
564 select OF_EARLY_FLATTREE
566 Select for the Intel CE media processor (CE4100) SOC.
567 This option compiles in support for the CE4100 SOC for settop
568 boxes and media devices.
571 bool "Intel MID platform support"
572 depends on X86_EXTENDED_PLATFORM
573 depends on X86_PLATFORM_DEVICES
575 depends on X86_64 || (PCI_GOANY && X86_32)
576 depends on X86_IO_APIC
582 select MFD_INTEL_MSIC
584 Select to build a kernel capable of supporting Intel MID (Mobile
585 Internet Device) platform systems which do not have the PCI legacy
586 interfaces. If you are building for a PC class system say N here.
588 Intel MID platforms are based on an Intel processor and chipset which
589 consume less power than most of the x86 derivatives.
591 config X86_INTEL_QUARK
592 bool "Intel Quark platform support"
594 depends on X86_EXTENDED_PLATFORM
595 depends on X86_PLATFORM_DEVICES
599 depends on X86_IO_APIC
604 Select to include support for Quark X1000 SoC.
605 Say Y here if you have a Quark based system such as the Arduino
606 compatible Intel Galileo.
608 config X86_INTEL_LPSS
609 bool "Intel Low Power Subsystem Support"
610 depends on X86 && ACPI
615 Select to build support for Intel Low Power Subsystem such as
616 found on Intel Lynxpoint PCH. Selecting this option enables
617 things like clock tree (common clock framework) and pincontrol
618 which are needed by the LPSS peripheral drivers.
620 config X86_AMD_PLATFORM_DEVICE
621 bool "AMD ACPI2Platform devices support"
626 Select to interpret AMD specific ACPI device to platform device
627 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
628 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
629 implemented under PINCTRL subsystem.
632 tristate "Intel SoC IOSF Sideband support for SoC platforms"
635 This option enables sideband register access support for Intel SoC
636 platforms. On these platforms the IOSF sideband is used in lieu of
637 MSR's for some register accesses, mostly but not limited to thermal
638 and power. Drivers may query the availability of this device to
639 determine if they need the sideband in order to work on these
640 platforms. The sideband is available on the following SoC products.
641 This list is not meant to be exclusive.
646 You should say Y if you are running a kernel on one of these SoC's.
648 config IOSF_MBI_DEBUG
649 bool "Enable IOSF sideband access through debugfs"
650 depends on IOSF_MBI && DEBUG_FS
652 Select this option to expose the IOSF sideband access registers (MCR,
653 MDR, MCRX) through debugfs to write and read register information from
654 different units on the SoC. This is most useful for obtaining device
655 state information for debug and analysis. As this is a general access
656 mechanism, users of this option would have specific knowledge of the
657 device they want to access.
659 If you don't require the option or are in doubt, say N.
662 bool "RDC R-321x SoC"
664 depends on X86_EXTENDED_PLATFORM
666 select X86_REBOOTFIXUPS
668 This option is needed for RDC R-321x system-on-chip, also known
670 If you don't have one of these chips, you should say N here.
672 config X86_32_NON_STANDARD
673 bool "Support non-standard 32-bit SMP architectures"
674 depends on X86_32 && SMP
675 depends on X86_EXTENDED_PLATFORM
677 This option compiles in the bigsmp and STA2X11 default
678 subarchitectures. It is intended for a generic binary
679 kernel. If you select them all, kernel will probe it one by
680 one and will fallback to default.
682 # Alphabetically sorted list of Non standard 32 bit platforms
684 config X86_SUPPORTS_MEMORY_FAILURE
686 # MCE code calls memory_failure():
688 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
689 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
690 depends on X86_64 || !SPARSEMEM
691 select ARCH_SUPPORTS_MEMORY_FAILURE
694 bool "STA2X11 Companion Chip Support"
695 depends on X86_32_NON_STANDARD && PCI
696 select ARCH_HAS_PHYS_TO_DMA
697 select X86_DEV_DMA_OPS
704 This adds support for boards based on the STA2X11 IO-Hub,
705 a.k.a. "ConneXt". The chip is used in place of the standard
706 PC chipset, so all "standard" peripherals are missing. If this
707 option is selected the kernel will still be able to boot on
708 standard PC machines.
711 tristate "Eurobraille/Iris poweroff module"
714 The Iris machines from EuroBraille do not have APM or ACPI support
715 to shut themselves down properly. A special I/O sequence is
716 needed to do so, which is what this module does at
719 This is only for Iris machines from EuroBraille.
723 config SCHED_OMIT_FRAME_POINTER
725 prompt "Single-depth WCHAN output"
728 Calculate simpler /proc/<PID>/wchan values. If this option
729 is disabled then wchan values will recurse back to the
730 caller function. This provides more accurate wchan values,
731 at the expense of slightly more scheduling overhead.
733 If in doubt, say "Y".
735 menuconfig HYPERVISOR_GUEST
736 bool "Linux guest support"
738 Say Y here to enable options for running Linux under various hyper-
739 visors. This option enables basic hypervisor detection and platform
742 If you say N, all options in this submenu will be skipped and
743 disabled, and Linux guest support won't be built in.
748 bool "Enable paravirtualization code"
750 This changes the kernel so it can modify itself when it is run
751 under a hypervisor, potentially improving performance significantly
752 over full virtualization. However, when run without a hypervisor
753 the kernel is theoretically slower and slightly larger.
755 config PARAVIRT_DEBUG
756 bool "paravirt-ops debugging"
757 depends on PARAVIRT && DEBUG_KERNEL
759 Enable to debug paravirt_ops internals. Specifically, BUG if
760 a paravirt_op is missing when it is called.
762 config PARAVIRT_SPINLOCKS
763 bool "Paravirtualization layer for spinlocks"
764 depends on PARAVIRT && SMP
766 Paravirtualized spinlocks allow a pvops backend to replace the
767 spinlock implementation with something virtualization-friendly
768 (for example, block the virtual CPU rather than spinning).
770 It has a minimal impact on native kernels and gives a nice performance
771 benefit on paravirtualized KVM / Xen kernels.
773 If you are unsure how to answer this question, answer Y.
775 config QUEUED_LOCK_STAT
776 bool "Paravirt queued spinlock statistics"
777 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
779 Enable the collection of statistical data on the slowpath
780 behavior of paravirtualized queued spinlocks and report
783 source "arch/x86/xen/Kconfig"
786 bool "KVM Guest support (including kvmclock)"
788 select PARAVIRT_CLOCK
791 This option enables various optimizations for running under the KVM
792 hypervisor. It includes a paravirtualized clock, so that instead
793 of relying on a PIT (or probably other) emulation by the
794 underlying device model, the host provides the guest with
795 timing infrastructure such as time of day, and system time
798 bool "Enable debug information for KVM Guests in debugfs"
799 depends on KVM_GUEST && DEBUG_FS
802 This option enables collection of various statistics for KVM guest.
803 Statistics are displayed in debugfs filesystem. Enabling this option
804 may incur significant overhead.
806 config PARAVIRT_TIME_ACCOUNTING
807 bool "Paravirtual steal time accounting"
811 Select this option to enable fine granularity task steal time
812 accounting. Time spent executing other tasks in parallel with
813 the current vCPU is discounted from the vCPU power. To account for
814 that, there can be a small performance impact.
816 If in doubt, say N here.
818 config PARAVIRT_CLOCK
821 config JAILHOUSE_GUEST
822 bool "Jailhouse non-root cell support"
823 depends on X86_64 && PCI
826 This option allows to run Linux as guest in a Jailhouse non-root
827 cell. You can leave this option disabled if you only want to start
828 Jailhouse and run Linux afterwards in the root cell.
830 endif #HYPERVISOR_GUEST
835 source "arch/x86/Kconfig.cpu"
839 prompt "HPET Timer Support" if X86_32
841 Use the IA-PC HPET (High Precision Event Timer) to manage
842 time in preference to the PIT and RTC, if a HPET is
844 HPET is the next generation timer replacing legacy 8254s.
845 The HPET provides a stable time base on SMP
846 systems, unlike the TSC, but it is more expensive to access,
847 as it is off-chip. The interface used is documented
848 in the HPET spec, revision 1.
850 You can safely choose Y here. However, HPET will only be
851 activated if the platform and the BIOS support this feature.
852 Otherwise the 8254 will be used for timing services.
854 Choose N to continue using the legacy 8254 timer.
856 config HPET_EMULATE_RTC
858 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
861 def_bool y if X86_INTEL_MID
862 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
864 depends on X86_INTEL_MID && SFI
866 APB timer is the replacement for 8254, HPET on X86 MID platforms.
867 The APBT provides a stable time base on SMP
868 systems, unlike the TSC, but it is more expensive to access,
869 as it is off-chip. APB timers are always running regardless of CPU
870 C states, they are used as per CPU clockevent device when possible.
872 # Mark as expert because too many people got it wrong.
873 # The code disables itself when not needed.
876 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
877 bool "Enable DMI scanning" if EXPERT
879 Enabled scanning of DMI to identify machine quirks. Say Y
880 here unless you have verified that your setup is not
881 affected by entries in the DMI blacklist. Required by PNP
885 bool "Old AMD GART IOMMU support"
888 depends on X86_64 && PCI && AMD_NB
890 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
891 GART based hardware IOMMUs.
893 The GART supports full DMA access for devices with 32-bit access
894 limitations, on systems with more than 3 GB. This is usually needed
895 for USB, sound, many IDE/SATA chipsets and some other devices.
897 Newer systems typically have a modern AMD IOMMU, supported via
898 the CONFIG_AMD_IOMMU=y config option.
900 In normal configurations this driver is only active when needed:
901 there's more than 3 GB of memory and the system contains a
902 32-bit limited device.
907 bool "IBM Calgary IOMMU support"
910 depends on X86_64 && PCI
912 Support for hardware IOMMUs in IBM's xSeries x366 and x460
913 systems. Needed to run systems with more than 3GB of memory
914 properly with 32-bit PCI devices that do not support DAC
915 (Double Address Cycle). Calgary also supports bus level
916 isolation, where all DMAs pass through the IOMMU. This
917 prevents them from going anywhere except their intended
918 destination. This catches hard-to-find kernel bugs and
919 mis-behaving drivers and devices that do not use the DMA-API
920 properly to set up their DMA buffers. The IOMMU can be
921 turned off at boot time with the iommu=off parameter.
922 Normally the kernel will make the right choice by itself.
925 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
927 prompt "Should Calgary be enabled by default?"
928 depends on CALGARY_IOMMU
930 Should Calgary be enabled by default? if you choose 'y', Calgary
931 will be used (if it exists). If you choose 'n', Calgary will not be
932 used even if it exists. If you choose 'n' and would like to use
933 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
937 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
938 depends on X86_64 && SMP && DEBUG_KERNEL
939 select CPUMASK_OFFSTACK
941 Enable maximum number of CPUS and NUMA Nodes for this architecture.
945 # The maximum number of CPUs supported:
947 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
948 # and which can be configured interactively in the
949 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
951 # The ranges are different on 32-bit and 64-bit kernels, depending on
952 # hardware capabilities and scalability features of the kernel.
954 # ( If MAXSMP is enabled we just use the highest possible value and disable
955 # interactive configuration. )
958 config NR_CPUS_RANGE_BEGIN
960 default NR_CPUS_RANGE_END if MAXSMP
964 config NR_CPUS_RANGE_END
967 default 64 if SMP && X86_BIGSMP
968 default 8 if SMP && !X86_BIGSMP
971 config NR_CPUS_RANGE_END
974 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
975 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
978 config NR_CPUS_DEFAULT
981 default 32 if X86_BIGSMP
985 config NR_CPUS_DEFAULT
988 default 8192 if MAXSMP
993 int "Maximum number of CPUs" if SMP && !MAXSMP
994 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
995 default NR_CPUS_DEFAULT
997 This allows you to specify the maximum number of CPUs which this
998 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
999 supported value is 8192, otherwise the maximum value is 512. The
1000 minimum value which makes sense is 2.
1002 This is purely to save memory: each supported CPU adds about 8KB
1003 to the kernel image.
1006 bool "SMT (Hyperthreading) scheduler support"
1009 SMT scheduler support improves the CPU scheduler's decision making
1010 when dealing with Intel Pentium 4 chips with HyperThreading at a
1011 cost of slightly increased overhead in some places. If unsure say
1016 prompt "Multi-core scheduler support"
1019 Multi-core scheduler support improves the CPU scheduler's decision
1020 making when dealing with multi-core CPU chips at a cost of slightly
1021 increased overhead in some places. If unsure say N here.
1023 config SCHED_MC_PRIO
1024 bool "CPU core priorities scheduler support"
1025 depends on SCHED_MC && CPU_SUP_INTEL
1026 select X86_INTEL_PSTATE
1030 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1031 core ordering determined at manufacturing time, which allows
1032 certain cores to reach higher turbo frequencies (when running
1033 single threaded workloads) than others.
1035 Enabling this kernel feature teaches the scheduler about
1036 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1037 scheduler's CPU selection logic accordingly, so that higher
1038 overall system performance can be achieved.
1040 This feature will have no effect on CPUs without this feature.
1042 If unsure say Y here.
1046 depends on !SMP && X86_LOCAL_APIC
1049 bool "Local APIC support on uniprocessors" if !PCI_MSI
1051 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1053 A local APIC (Advanced Programmable Interrupt Controller) is an
1054 integrated interrupt controller in the CPU. If you have a single-CPU
1055 system which has a processor with a local APIC, you can say Y here to
1056 enable and use it. If you say Y here even though your machine doesn't
1057 have a local APIC, then the kernel will still run with no slowdown at
1058 all. The local APIC supports CPU-generated self-interrupts (timer,
1059 performance counters), and the NMI watchdog which detects hard
1062 config X86_UP_IOAPIC
1063 bool "IO-APIC support on uniprocessors"
1064 depends on X86_UP_APIC
1066 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1067 SMP-capable replacement for PC-style interrupt controllers. Most
1068 SMP systems and many recent uniprocessor systems have one.
1070 If you have a single-CPU system with an IO-APIC, you can say Y here
1071 to use it. If you say Y here even though your machine doesn't have
1072 an IO-APIC, then the kernel will still run with no slowdown at all.
1074 config X86_LOCAL_APIC
1076 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1077 select IRQ_DOMAIN_HIERARCHY
1078 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1082 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1084 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1085 bool "Reroute for broken boot IRQs"
1086 depends on X86_IO_APIC
1088 This option enables a workaround that fixes a source of
1089 spurious interrupts. This is recommended when threaded
1090 interrupt handling is used on systems where the generation of
1091 superfluous "boot interrupts" cannot be disabled.
1093 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1094 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1095 kernel does during interrupt handling). On chipsets where this
1096 boot IRQ generation cannot be disabled, this workaround keeps
1097 the original IRQ line masked so that only the equivalent "boot
1098 IRQ" is delivered to the CPUs. The workaround also tells the
1099 kernel to set up the IRQ handler on the boot IRQ line. In this
1100 way only one interrupt is delivered to the kernel. Otherwise
1101 the spurious second interrupt may cause the kernel to bring
1102 down (vital) interrupt lines.
1104 Only affects "broken" chipsets. Interrupt sharing may be
1105 increased on these systems.
1108 bool "Machine Check / overheating reporting"
1109 select GENERIC_ALLOCATOR
1112 Machine Check support allows the processor to notify the
1113 kernel if it detects a problem (e.g. overheating, data corruption).
1114 The action the kernel takes depends on the severity of the problem,
1115 ranging from warning messages to halting the machine.
1117 config X86_MCELOG_LEGACY
1118 bool "Support for deprecated /dev/mcelog character device"
1121 Enable support for /dev/mcelog which is needed by the old mcelog
1122 userspace logging daemon. Consider switching to the new generation
1125 config X86_MCE_INTEL
1127 prompt "Intel MCE features"
1128 depends on X86_MCE && X86_LOCAL_APIC
1130 Additional support for intel specific MCE features such as
1131 the thermal monitor.
1135 prompt "AMD MCE features"
1136 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1138 Additional support for AMD specific MCE features such as
1139 the DRAM Error Threshold.
1141 config X86_ANCIENT_MCE
1142 bool "Support for old Pentium 5 / WinChip machine checks"
1143 depends on X86_32 && X86_MCE
1145 Include support for machine check handling on old Pentium 5 or WinChip
1146 systems. These typically need to be enabled explicitly on the command
1149 config X86_MCE_THRESHOLD
1150 depends on X86_MCE_AMD || X86_MCE_INTEL
1153 config X86_MCE_INJECT
1154 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1155 tristate "Machine check injector support"
1157 Provide support for injecting machine checks for testing purposes.
1158 If you don't know what a machine check is and you don't do kernel
1159 QA it is safe to say n.
1161 config X86_THERMAL_VECTOR
1163 depends on X86_MCE_INTEL
1165 source "arch/x86/events/Kconfig"
1167 config X86_LEGACY_VM86
1168 bool "Legacy VM86 support"
1172 This option allows user programs to put the CPU into V8086
1173 mode, which is an 80286-era approximation of 16-bit real mode.
1175 Some very old versions of X and/or vbetool require this option
1176 for user mode setting. Similarly, DOSEMU will use it if
1177 available to accelerate real mode DOS programs. However, any
1178 recent version of DOSEMU, X, or vbetool should be fully
1179 functional even without kernel VM86 support, as they will all
1180 fall back to software emulation. Nevertheless, if you are using
1181 a 16-bit DOS program where 16-bit performance matters, vm86
1182 mode might be faster than emulation and you might want to
1185 Note that any app that works on a 64-bit kernel is unlikely to
1186 need this option, as 64-bit kernels don't, and can't, support
1187 V8086 mode. This option is also unrelated to 16-bit protected
1188 mode and is not needed to run most 16-bit programs under Wine.
1190 Enabling this option increases the complexity of the kernel
1191 and slows down exception handling a tiny bit.
1193 If unsure, say N here.
1197 default X86_LEGACY_VM86
1200 bool "Enable support for 16-bit segments" if EXPERT
1202 depends on MODIFY_LDT_SYSCALL
1204 This option is required by programs like Wine to run 16-bit
1205 protected mode legacy code on x86 processors. Disabling
1206 this option saves about 300 bytes on i386, or around 6K text
1207 plus 16K runtime memory on x86-64,
1211 depends on X86_16BIT && X86_32
1215 depends on X86_16BIT && X86_64
1217 config X86_VSYSCALL_EMULATION
1218 bool "Enable vsyscall emulation" if EXPERT
1222 This enables emulation of the legacy vsyscall page. Disabling
1223 it is roughly equivalent to booting with vsyscall=none, except
1224 that it will also disable the helpful warning if a program
1225 tries to use a vsyscall. With this option set to N, offending
1226 programs will just segfault, citing addresses of the form
1229 This option is required by many programs built before 2013, and
1230 care should be used even with newer programs if set to N.
1232 Disabling this option saves about 7K of kernel size and
1233 possibly 4K of additional runtime pagetable memory.
1236 tristate "Toshiba Laptop support"
1239 This adds a driver to safely access the System Management Mode of
1240 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1241 not work on models with a Phoenix BIOS. The System Management Mode
1242 is used to set the BIOS and power saving options on Toshiba portables.
1244 For information on utilities to make use of this driver see the
1245 Toshiba Linux utilities web site at:
1246 <http://www.buzzard.org.uk/toshiba/>.
1248 Say Y if you intend to run this kernel on a Toshiba portable.
1252 tristate "Dell i8k legacy laptop support"
1254 select SENSORS_DELL_SMM
1256 This option enables legacy /proc/i8k userspace interface in hwmon
1257 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1258 temperature and allows controlling fan speeds of Dell laptops via
1259 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1260 it reports also power and hotkey status. For fan speed control is
1261 needed userspace package i8kutils.
1263 Say Y if you intend to run this kernel on old Dell laptops or want to
1264 use userspace package i8kutils.
1267 config X86_REBOOTFIXUPS
1268 bool "Enable X86 board specific fixups for reboot"
1271 This enables chipset and/or board specific fixups to be done
1272 in order to get reboot to work correctly. This is only needed on
1273 some combinations of hardware and BIOS. The symptom, for which
1274 this config is intended, is when reboot ends with a stalled/hung
1277 Currently, the only fixup is for the Geode machines using
1278 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1280 Say Y if you want to enable the fixup. Currently, it's safe to
1281 enable this option even if you don't need it.
1285 bool "CPU microcode loading support"
1287 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1290 If you say Y here, you will be able to update the microcode on
1291 Intel and AMD processors. The Intel support is for the IA32 family,
1292 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1293 AMD support is for families 0x10 and later. You will obviously need
1294 the actual microcode binary data itself which is not shipped with
1297 The preferred method to load microcode from a detached initrd is described
1298 in Documentation/x86/microcode.txt. For that you need to enable
1299 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1300 initrd for microcode blobs.
1302 In addition, you can build the microcode into the kernel. For that you
1303 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1306 config MICROCODE_INTEL
1307 bool "Intel microcode loading support"
1308 depends on MICROCODE
1312 This options enables microcode patch loading support for Intel
1315 For the current Intel microcode data package go to
1316 <https://downloadcenter.intel.com> and search for
1317 'Linux Processor Microcode Data File'.
1319 config MICROCODE_AMD
1320 bool "AMD microcode loading support"
1321 depends on MICROCODE
1324 If you select this option, microcode patch loading support for AMD
1325 processors will be enabled.
1327 config MICROCODE_OLD_INTERFACE
1329 depends on MICROCODE
1332 tristate "/dev/cpu/*/msr - Model-specific register support"
1334 This device gives privileged processes access to the x86
1335 Model-Specific Registers (MSRs). It is a character device with
1336 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1337 MSR accesses are directed to a specific CPU on multi-processor
1341 tristate "/dev/cpu/*/cpuid - CPU information support"
1343 This device gives processes access to the x86 CPUID instruction to
1344 be executed on a specific processor. It is a character device
1345 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1349 prompt "High Memory Support"
1356 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1357 However, the address space of 32-bit x86 processors is only 4
1358 Gigabytes large. That means that, if you have a large amount of
1359 physical memory, not all of it can be "permanently mapped" by the
1360 kernel. The physical memory that's not permanently mapped is called
1363 If you are compiling a kernel which will never run on a machine with
1364 more than 1 Gigabyte total physical RAM, answer "off" here (default
1365 choice and suitable for most users). This will result in a "3GB/1GB"
1366 split: 3GB are mapped so that each process sees a 3GB virtual memory
1367 space and the remaining part of the 4GB virtual memory space is used
1368 by the kernel to permanently map as much physical memory as
1371 If the machine has between 1 and 4 Gigabytes physical RAM, then
1374 If more than 4 Gigabytes is used then answer "64GB" here. This
1375 selection turns Intel PAE (Physical Address Extension) mode on.
1376 PAE implements 3-level paging on IA32 processors. PAE is fully
1377 supported by Linux, PAE mode is implemented on all recent Intel
1378 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1379 then the kernel will not boot on CPUs that don't support PAE!
1381 The actual amount of total physical memory will either be
1382 auto detected or can be forced by using a kernel command line option
1383 such as "mem=256M". (Try "man bootparam" or see the documentation of
1384 your boot loader (lilo or loadlin) about how to pass options to the
1385 kernel at boot time.)
1387 If unsure, say "off".
1392 Select this if you have a 32-bit processor and between 1 and 4
1393 gigabytes of physical RAM.
1397 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1400 Select this if you have a 32-bit processor and more than 4
1401 gigabytes of physical RAM.
1406 prompt "Memory split" if EXPERT
1410 Select the desired split between kernel and user memory.
1412 If the address range available to the kernel is less than the
1413 physical memory installed, the remaining memory will be available
1414 as "high memory". Accessing high memory is a little more costly
1415 than low memory, as it needs to be mapped into the kernel first.
1416 Note that increasing the kernel address space limits the range
1417 available to user programs, making the address space there
1418 tighter. Selecting anything other than the default 3G/1G split
1419 will also likely make your kernel incompatible with binary-only
1422 If you are not absolutely sure what you are doing, leave this
1426 bool "3G/1G user/kernel split"
1427 config VMSPLIT_3G_OPT
1429 bool "3G/1G user/kernel split (for full 1G low memory)"
1431 bool "2G/2G user/kernel split"
1432 config VMSPLIT_2G_OPT
1434 bool "2G/2G user/kernel split (for full 2G low memory)"
1436 bool "1G/3G user/kernel split"
1441 default 0xB0000000 if VMSPLIT_3G_OPT
1442 default 0x80000000 if VMSPLIT_2G
1443 default 0x78000000 if VMSPLIT_2G_OPT
1444 default 0x40000000 if VMSPLIT_1G
1450 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1453 bool "PAE (Physical Address Extension) Support"
1454 depends on X86_32 && !HIGHMEM4G
1455 select PHYS_ADDR_T_64BIT
1458 PAE is required for NX support, and furthermore enables
1459 larger swapspace support for non-overcommit purposes. It
1460 has the cost of more pagetable lookup overhead, and also
1461 consumes more pagetable space per process.
1464 bool "Enable 5-level page tables support"
1465 select DYNAMIC_MEMORY_LAYOUT
1466 select SPARSEMEM_VMEMMAP
1469 5-level paging enables access to larger address space:
1470 upto 128 PiB of virtual address space and 4 PiB of
1471 physical address space.
1473 It will be supported by future Intel CPUs.
1475 A kernel with the option enabled can be booted on machines that
1476 support 4- or 5-level paging.
1478 See Documentation/x86/x86_64/5level-paging.txt for more
1483 config X86_DIRECT_GBPAGES
1485 depends on X86_64 && !DEBUG_PAGEALLOC
1487 Certain kernel features effectively disable kernel
1488 linear 1 GB mappings (even if the CPU otherwise
1489 supports them), so don't confuse the user by printing
1490 that we have them enabled.
1492 config ARCH_HAS_MEM_ENCRYPT
1495 config AMD_MEM_ENCRYPT
1496 bool "AMD Secure Memory Encryption (SME) support"
1497 depends on X86_64 && CPU_SUP_AMD
1498 select DYNAMIC_PHYSICAL_MASK
1500 Say yes to enable support for the encryption of system memory.
1501 This requires an AMD processor that supports Secure Memory
1504 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1505 bool "Activate AMD Secure Memory Encryption (SME) by default"
1507 depends on AMD_MEM_ENCRYPT
1509 Say yes to have system memory encrypted by default if running on
1510 an AMD processor that supports Secure Memory Encryption (SME).
1512 If set to Y, then the encryption of system memory can be
1513 deactivated with the mem_encrypt=off command line option.
1515 If set to N, then the encryption of system memory can be
1516 activated with the mem_encrypt=on command line option.
1518 config ARCH_USE_MEMREMAP_PROT
1520 depends on AMD_MEM_ENCRYPT
1522 # Common NUMA Features
1524 bool "Numa Memory Allocation and Scheduler Support"
1526 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1527 default y if X86_BIGSMP
1529 Enable NUMA (Non Uniform Memory Access) support.
1531 The kernel will try to allocate memory used by a CPU on the
1532 local memory controller of the CPU and add some more
1533 NUMA awareness to the kernel.
1535 For 64-bit this is recommended if the system is Intel Core i7
1536 (or later), AMD Opteron, or EM64T NUMA.
1538 For 32-bit this is only needed if you boot a 32-bit
1539 kernel on a 64-bit NUMA platform.
1541 Otherwise, you should say N.
1545 prompt "Old style AMD Opteron NUMA detection"
1546 depends on X86_64 && NUMA && PCI
1548 Enable AMD NUMA node topology detection. You should say Y here if
1549 you have a multi processor AMD system. This uses an old method to
1550 read the NUMA configuration directly from the builtin Northbridge
1551 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1552 which also takes priority if both are compiled in.
1554 config X86_64_ACPI_NUMA
1556 prompt "ACPI NUMA detection"
1557 depends on X86_64 && NUMA && ACPI && PCI
1560 Enable ACPI SRAT based node topology detection.
1562 # Some NUMA nodes have memory ranges that span
1563 # other nodes. Even though a pfn is valid and
1564 # between a node's start and end pfns, it may not
1565 # reside on that node. See memmap_init_zone()
1567 config NODES_SPAN_OTHER_NODES
1569 depends on X86_64_ACPI_NUMA
1572 bool "NUMA emulation"
1575 Enable NUMA emulation. A flat machine will be split
1576 into virtual nodes when booted with "numa=fake=N", where N is the
1577 number of nodes. This is only useful for debugging.
1580 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1582 default "10" if MAXSMP
1583 default "6" if X86_64
1585 depends on NEED_MULTIPLE_NODES
1587 Specify the maximum number of NUMA Nodes available on the target
1588 system. Increases memory reserved to accommodate various tables.
1590 config ARCH_HAVE_MEMORY_PRESENT
1592 depends on X86_32 && DISCONTIGMEM
1594 config ARCH_FLATMEM_ENABLE
1596 depends on X86_32 && !NUMA
1598 config ARCH_DISCONTIGMEM_ENABLE
1600 depends on NUMA && X86_32
1602 config ARCH_DISCONTIGMEM_DEFAULT
1604 depends on NUMA && X86_32
1606 config ARCH_SPARSEMEM_ENABLE
1608 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1609 select SPARSEMEM_STATIC if X86_32
1610 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1612 config ARCH_SPARSEMEM_DEFAULT
1616 config ARCH_SELECT_MEMORY_MODEL
1618 depends on ARCH_SPARSEMEM_ENABLE
1620 config ARCH_MEMORY_PROBE
1621 bool "Enable sysfs memory/probe interface"
1622 depends on X86_64 && MEMORY_HOTPLUG
1624 This option enables a sysfs memory/probe interface for testing.
1625 See Documentation/memory-hotplug.txt for more information.
1626 If you are unsure how to answer this question, answer N.
1628 config ARCH_PROC_KCORE_TEXT
1630 depends on X86_64 && PROC_KCORE
1632 config ILLEGAL_POINTER_VALUE
1635 default 0xdead000000000000 if X86_64
1637 config X86_PMEM_LEGACY_DEVICE
1640 config X86_PMEM_LEGACY
1641 tristate "Support non-standard NVDIMMs and ADR protected memory"
1642 depends on PHYS_ADDR_T_64BIT
1644 select X86_PMEM_LEGACY_DEVICE
1647 Treat memory marked using the non-standard e820 type of 12 as used
1648 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1649 The kernel will offer these regions to the 'pmem' driver so
1650 they can be used for persistent storage.
1655 bool "Allocate 3rd-level pagetables from highmem"
1658 The VM uses one page table entry for each page of physical memory.
1659 For systems with a lot of RAM, this can be wasteful of precious
1660 low memory. Setting this option will put user-space page table
1661 entries in high memory.
1663 config X86_CHECK_BIOS_CORRUPTION
1664 bool "Check for low memory corruption"
1666 Periodically check for memory corruption in low memory, which
1667 is suspected to be caused by BIOS. Even when enabled in the
1668 configuration, it is disabled at runtime. Enable it by
1669 setting "memory_corruption_check=1" on the kernel command
1670 line. By default it scans the low 64k of memory every 60
1671 seconds; see the memory_corruption_check_size and
1672 memory_corruption_check_period parameters in
1673 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1675 When enabled with the default parameters, this option has
1676 almost no overhead, as it reserves a relatively small amount
1677 of memory and scans it infrequently. It both detects corruption
1678 and prevents it from affecting the running system.
1680 It is, however, intended as a diagnostic tool; if repeatable
1681 BIOS-originated corruption always affects the same memory,
1682 you can use memmap= to prevent the kernel from using that
1685 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1686 bool "Set the default setting of memory_corruption_check"
1687 depends on X86_CHECK_BIOS_CORRUPTION
1690 Set whether the default state of memory_corruption_check is
1693 config X86_RESERVE_LOW
1694 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1698 Specify the amount of low memory to reserve for the BIOS.
1700 The first page contains BIOS data structures that the kernel
1701 must not use, so that page must always be reserved.
1703 By default we reserve the first 64K of physical RAM, as a
1704 number of BIOSes are known to corrupt that memory range
1705 during events such as suspend/resume or monitor cable
1706 insertion, so it must not be used by the kernel.
1708 You can set this to 4 if you are absolutely sure that you
1709 trust the BIOS to get all its memory reservations and usages
1710 right. If you know your BIOS have problems beyond the
1711 default 64K area, you can set this to 640 to avoid using the
1712 entire low memory range.
1714 If you have doubts about the BIOS (e.g. suspend/resume does
1715 not work or there's kernel crashes after certain hardware
1716 hotplug events) then you might want to enable
1717 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1718 typical corruption patterns.
1720 Leave this to the default value of 64 if you are unsure.
1722 config MATH_EMULATION
1724 depends on MODIFY_LDT_SYSCALL
1725 prompt "Math emulation" if X86_32
1727 Linux can emulate a math coprocessor (used for floating point
1728 operations) if you don't have one. 486DX and Pentium processors have
1729 a math coprocessor built in, 486SX and 386 do not, unless you added
1730 a 487DX or 387, respectively. (The messages during boot time can
1731 give you some hints here ["man dmesg"].) Everyone needs either a
1732 coprocessor or this emulation.
1734 If you don't have a math coprocessor, you need to say Y here; if you
1735 say Y here even though you have a coprocessor, the coprocessor will
1736 be used nevertheless. (This behavior can be changed with the kernel
1737 command line option "no387", which comes handy if your coprocessor
1738 is broken. Try "man bootparam" or see the documentation of your boot
1739 loader (lilo or loadlin) about how to pass options to the kernel at
1740 boot time.) This means that it is a good idea to say Y here if you
1741 intend to use this kernel on different machines.
1743 More information about the internals of the Linux math coprocessor
1744 emulation can be found in <file:arch/x86/math-emu/README>.
1746 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1747 kernel, it won't hurt.
1751 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1753 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1754 the Memory Type Range Registers (MTRRs) may be used to control
1755 processor access to memory ranges. This is most useful if you have
1756 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1757 allows bus write transfers to be combined into a larger transfer
1758 before bursting over the PCI/AGP bus. This can increase performance
1759 of image write operations 2.5 times or more. Saying Y here creates a
1760 /proc/mtrr file which may be used to manipulate your processor's
1761 MTRRs. Typically the X server should use this.
1763 This code has a reasonably generic interface so that similar
1764 control registers on other processors can be easily supported
1767 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1768 Registers (ARRs) which provide a similar functionality to MTRRs. For
1769 these, the ARRs are used to emulate the MTRRs.
1770 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1771 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1772 write-combining. All of these processors are supported by this code
1773 and it makes sense to say Y here if you have one of them.
1775 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1776 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1777 can lead to all sorts of problems, so it's good to say Y here.
1779 You can safely say Y even if your machine doesn't have MTRRs, you'll
1780 just add about 9 KB to your kernel.
1782 See <file:Documentation/x86/mtrr.txt> for more information.
1784 config MTRR_SANITIZER
1786 prompt "MTRR cleanup support"
1789 Convert MTRR layout from continuous to discrete, so X drivers can
1790 add writeback entries.
1792 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1793 The largest mtrr entry size for a continuous block can be set with
1798 config MTRR_SANITIZER_ENABLE_DEFAULT
1799 int "MTRR cleanup enable value (0-1)"
1802 depends on MTRR_SANITIZER
1804 Enable mtrr cleanup default value
1806 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1807 int "MTRR cleanup spare reg num (0-7)"
1810 depends on MTRR_SANITIZER
1812 mtrr cleanup spare entries default, it can be changed via
1813 mtrr_spare_reg_nr=N on the kernel command line.
1817 prompt "x86 PAT support" if EXPERT
1820 Use PAT attributes to setup page level cache control.
1822 PATs are the modern equivalents of MTRRs and are much more
1823 flexible than MTRRs.
1825 Say N here if you see bootup problems (boot crash, boot hang,
1826 spontaneous reboots) or a non-working video driver.
1830 config ARCH_USES_PG_UNCACHED
1836 prompt "x86 architectural random number generator" if EXPERT
1838 Enable the x86 architectural RDRAND instruction
1839 (Intel Bull Mountain technology) to generate random numbers.
1840 If supported, this is a high bandwidth, cryptographically
1841 secure hardware random number generator.
1845 prompt "Supervisor Mode Access Prevention" if EXPERT
1847 Supervisor Mode Access Prevention (SMAP) is a security
1848 feature in newer Intel processors. There is a small
1849 performance cost if this enabled and turned on; there is
1850 also a small increase in the kernel size if this is enabled.
1854 config X86_INTEL_UMIP
1856 depends on CPU_SUP_INTEL
1857 prompt "Intel User Mode Instruction Prevention" if EXPERT
1859 The User Mode Instruction Prevention (UMIP) is a security
1860 feature in newer Intel processors. If enabled, a general
1861 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1862 or STR instructions are executed in user mode. These instructions
1863 unnecessarily expose information about the hardware state.
1865 The vast majority of applications do not use these instructions.
1866 For the very few that do, software emulation is provided in
1867 specific cases in protected and virtual-8086 modes. Emulated
1870 config X86_INTEL_MPX
1871 prompt "Intel MPX (Memory Protection Extensions)"
1873 # Note: only available in 64-bit mode due to VMA flags shortage
1874 depends on CPU_SUP_INTEL && X86_64
1875 select ARCH_USES_HIGH_VMA_FLAGS
1877 MPX provides hardware features that can be used in
1878 conjunction with compiler-instrumented code to check
1879 memory references. It is designed to detect buffer
1880 overflow or underflow bugs.
1882 This option enables running applications which are
1883 instrumented or otherwise use MPX. It does not use MPX
1884 itself inside the kernel or to protect the kernel
1885 against bad memory references.
1887 Enabling this option will make the kernel larger:
1888 ~8k of kernel text and 36 bytes of data on a 64-bit
1889 defconfig. It adds a long to the 'mm_struct' which
1890 will increase the kernel memory overhead of each
1891 process and adds some branches to paths used during
1892 exec() and munmap().
1894 For details, see Documentation/x86/intel_mpx.txt
1898 config X86_INTEL_MEMORY_PROTECTION_KEYS
1899 prompt "Intel Memory Protection Keys"
1901 # Note: only available in 64-bit mode
1902 depends on CPU_SUP_INTEL && X86_64
1903 select ARCH_USES_HIGH_VMA_FLAGS
1904 select ARCH_HAS_PKEYS
1906 Memory Protection Keys provides a mechanism for enforcing
1907 page-based protections, but without requiring modification of the
1908 page tables when an application changes protection domains.
1910 For details, see Documentation/x86/protection-keys.txt
1915 bool "EFI runtime service support"
1918 select EFI_RUNTIME_WRAPPERS
1920 This enables the kernel to use EFI runtime services that are
1921 available (such as the EFI variable services).
1923 This option is only useful on systems that have EFI firmware.
1924 In addition, you should use the latest ELILO loader available
1925 at <http://elilo.sourceforge.net> in order to take advantage
1926 of EFI runtime services. However, even with this option, the
1927 resultant kernel should continue to boot on existing non-EFI
1931 bool "EFI stub support"
1932 depends on EFI && !X86_USE_3DNOW
1935 This kernel feature allows a bzImage to be loaded directly
1936 by EFI firmware without the use of a bootloader.
1938 See Documentation/efi-stub.txt for more information.
1941 bool "EFI mixed-mode support"
1942 depends on EFI_STUB && X86_64
1944 Enabling this feature allows a 64-bit kernel to be booted
1945 on a 32-bit firmware, provided that your CPU supports 64-bit
1948 Note that it is not possible to boot a mixed-mode enabled
1949 kernel via the EFI boot stub - a bootloader that supports
1950 the EFI handover protocol must be used.
1956 prompt "Enable seccomp to safely compute untrusted bytecode"
1958 This kernel feature is useful for number crunching applications
1959 that may need to compute untrusted bytecode during their
1960 execution. By using pipes or other transports made available to
1961 the process as file descriptors supporting the read/write
1962 syscalls, it's possible to isolate those applications in
1963 their own address space using seccomp. Once seccomp is
1964 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1965 and the task is only allowed to execute a few safe syscalls
1966 defined by each seccomp mode.
1968 If unsure, say Y. Only embedded should say N here.
1970 source kernel/Kconfig.hz
1973 bool "kexec system call"
1976 kexec is a system call that implements the ability to shutdown your
1977 current kernel, and to start another kernel. It is like a reboot
1978 but it is independent of the system firmware. And like a reboot
1979 you can start any kernel with it, not just Linux.
1981 The name comes from the similarity to the exec system call.
1983 It is an ongoing process to be certain the hardware in a machine
1984 is properly shutdown, so do not be surprised if this code does not
1985 initially work for you. As of this writing the exact hardware
1986 interface is strongly in flux, so no good recommendation can be
1990 bool "kexec file based system call"
1995 depends on CRYPTO_SHA256=y
1997 This is new version of kexec system call. This system call is
1998 file based and takes file descriptors as system call argument
1999 for kernel and initramfs as opposed to list of segments as
2000 accepted by previous system call.
2002 config ARCH_HAS_KEXEC_PURGATORY
2005 config KEXEC_VERIFY_SIG
2006 bool "Verify kernel signature during kexec_file_load() syscall"
2007 depends on KEXEC_FILE
2009 This option makes kernel signature verification mandatory for
2010 the kexec_file_load() syscall.
2012 In addition to that option, you need to enable signature
2013 verification for the corresponding kernel image type being
2014 loaded in order for this to work.
2016 config KEXEC_BZIMAGE_VERIFY_SIG
2017 bool "Enable bzImage signature verification support"
2018 depends on KEXEC_VERIFY_SIG
2019 depends on SIGNED_PE_FILE_VERIFICATION
2020 select SYSTEM_TRUSTED_KEYRING
2022 Enable bzImage signature verification support.
2025 bool "kernel crash dumps"
2026 depends on X86_64 || (X86_32 && HIGHMEM)
2028 Generate crash dump after being started by kexec.
2029 This should be normally only set in special crash dump kernels
2030 which are loaded in the main kernel with kexec-tools into
2031 a specially reserved region and then later executed after
2032 a crash by kdump/kexec. The crash dump kernel must be compiled
2033 to a memory address not used by the main kernel or BIOS using
2034 PHYSICAL_START, or it must be built as a relocatable image
2035 (CONFIG_RELOCATABLE=y).
2036 For more details see Documentation/kdump/kdump.txt
2040 depends on KEXEC && HIBERNATION
2042 Jump between original kernel and kexeced kernel and invoke
2043 code in physical address mode via KEXEC
2045 config PHYSICAL_START
2046 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2049 This gives the physical address where the kernel is loaded.
2051 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2052 bzImage will decompress itself to above physical address and
2053 run from there. Otherwise, bzImage will run from the address where
2054 it has been loaded by the boot loader and will ignore above physical
2057 In normal kdump cases one does not have to set/change this option
2058 as now bzImage can be compiled as a completely relocatable image
2059 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2060 address. This option is mainly useful for the folks who don't want
2061 to use a bzImage for capturing the crash dump and want to use a
2062 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2063 to be specifically compiled to run from a specific memory area
2064 (normally a reserved region) and this option comes handy.
2066 So if you are using bzImage for capturing the crash dump,
2067 leave the value here unchanged to 0x1000000 and set
2068 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2069 for capturing the crash dump change this value to start of
2070 the reserved region. In other words, it can be set based on
2071 the "X" value as specified in the "crashkernel=YM@XM"
2072 command line boot parameter passed to the panic-ed
2073 kernel. Please take a look at Documentation/kdump/kdump.txt
2074 for more details about crash dumps.
2076 Usage of bzImage for capturing the crash dump is recommended as
2077 one does not have to build two kernels. Same kernel can be used
2078 as production kernel and capture kernel. Above option should have
2079 gone away after relocatable bzImage support is introduced. But it
2080 is present because there are users out there who continue to use
2081 vmlinux for dump capture. This option should go away down the
2084 Don't change this unless you know what you are doing.
2087 bool "Build a relocatable kernel"
2090 This builds a kernel image that retains relocation information
2091 so it can be loaded someplace besides the default 1MB.
2092 The relocations tend to make the kernel binary about 10% larger,
2093 but are discarded at runtime.
2095 One use is for the kexec on panic case where the recovery kernel
2096 must live at a different physical address than the primary
2099 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2100 it has been loaded at and the compile time physical address
2101 (CONFIG_PHYSICAL_START) is used as the minimum location.
2103 config RANDOMIZE_BASE
2104 bool "Randomize the address of the kernel image (KASLR)"
2105 depends on RELOCATABLE
2108 In support of Kernel Address Space Layout Randomization (KASLR),
2109 this randomizes the physical address at which the kernel image
2110 is decompressed and the virtual address where the kernel
2111 image is mapped, as a security feature that deters exploit
2112 attempts relying on knowledge of the location of kernel
2115 On 64-bit, the kernel physical and virtual addresses are
2116 randomized separately. The physical address will be anywhere
2117 between 16MB and the top of physical memory (up to 64TB). The
2118 virtual address will be randomized from 16MB up to 1GB (9 bits
2119 of entropy). Note that this also reduces the memory space
2120 available to kernel modules from 1.5GB to 1GB.
2122 On 32-bit, the kernel physical and virtual addresses are
2123 randomized together. They will be randomized from 16MB up to
2124 512MB (8 bits of entropy).
2126 Entropy is generated using the RDRAND instruction if it is
2127 supported. If RDTSC is supported, its value is mixed into
2128 the entropy pool as well. If neither RDRAND nor RDTSC are
2129 supported, then entropy is read from the i8254 timer. The
2130 usable entropy is limited by the kernel being built using
2131 2GB addressing, and that PHYSICAL_ALIGN must be at a
2132 minimum of 2MB. As a result, only 10 bits of entropy are
2133 theoretically possible, but the implementations are further
2134 limited due to memory layouts.
2138 # Relocation on x86 needs some additional build support
2139 config X86_NEED_RELOCS
2141 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2143 config PHYSICAL_ALIGN
2144 hex "Alignment value to which kernel should be aligned"
2146 range 0x2000 0x1000000 if X86_32
2147 range 0x200000 0x1000000 if X86_64
2149 This value puts the alignment restrictions on physical address
2150 where kernel is loaded and run from. Kernel is compiled for an
2151 address which meets above alignment restriction.
2153 If bootloader loads the kernel at a non-aligned address and
2154 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2155 address aligned to above value and run from there.
2157 If bootloader loads the kernel at a non-aligned address and
2158 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2159 load address and decompress itself to the address it has been
2160 compiled for and run from there. The address for which kernel is
2161 compiled already meets above alignment restrictions. Hence the
2162 end result is that kernel runs from a physical address meeting
2163 above alignment restrictions.
2165 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2166 this value must be a multiple of 0x200000.
2168 Don't change this unless you know what you are doing.
2170 config DYNAMIC_MEMORY_LAYOUT
2173 This option makes base addresses of vmalloc and vmemmap as well as
2174 __PAGE_OFFSET movable during boot.
2176 config RANDOMIZE_MEMORY
2177 bool "Randomize the kernel memory sections"
2179 depends on RANDOMIZE_BASE
2180 select DYNAMIC_MEMORY_LAYOUT
2181 default RANDOMIZE_BASE
2183 Randomizes the base virtual address of kernel memory sections
2184 (physical memory mapping, vmalloc & vmemmap). This security feature
2185 makes exploits relying on predictable memory locations less reliable.
2187 The order of allocations remains unchanged. Entropy is generated in
2188 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2189 configuration have in average 30,000 different possible virtual
2190 addresses for each memory section.
2194 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2195 hex "Physical memory mapping padding" if EXPERT
2196 depends on RANDOMIZE_MEMORY
2197 default "0xa" if MEMORY_HOTPLUG
2199 range 0x1 0x40 if MEMORY_HOTPLUG
2202 Define the padding in terabytes added to the existing physical
2203 memory size during kernel memory randomization. It is useful
2204 for memory hotplug support but reduces the entropy available for
2205 address randomization.
2207 If unsure, leave at the default value.
2210 bool "Support for hot-pluggable CPUs"
2213 Say Y here to allow turning CPUs off and on. CPUs can be
2214 controlled through /sys/devices/system/cpu.
2215 ( Note: power management support will enable this option
2216 automatically on SMP systems. )
2217 Say N if you want to disable CPU hotplug.
2219 config BOOTPARAM_HOTPLUG_CPU0
2220 bool "Set default setting of cpu0_hotpluggable"
2222 depends on HOTPLUG_CPU
2224 Set whether default state of cpu0_hotpluggable is on or off.
2226 Say Y here to enable CPU0 hotplug by default. If this switch
2227 is turned on, there is no need to give cpu0_hotplug kernel
2228 parameter and the CPU0 hotplug feature is enabled by default.
2230 Please note: there are two known CPU0 dependencies if you want
2231 to enable the CPU0 hotplug feature either by this switch or by
2232 cpu0_hotplug kernel parameter.
2234 First, resume from hibernate or suspend always starts from CPU0.
2235 So hibernate and suspend are prevented if CPU0 is offline.
2237 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2238 offline if any interrupt can not migrate out of CPU0. There may
2239 be other CPU0 dependencies.
2241 Please make sure the dependencies are under your control before
2242 you enable this feature.
2244 Say N if you don't want to enable CPU0 hotplug feature by default.
2245 You still can enable the CPU0 hotplug feature at boot by kernel
2246 parameter cpu0_hotplug.
2248 config DEBUG_HOTPLUG_CPU0
2250 prompt "Debug CPU0 hotplug"
2251 depends on HOTPLUG_CPU
2253 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2254 soon as possible and boots up userspace with CPU0 offlined. User
2255 can online CPU0 back after boot time.
2257 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2258 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2259 compilation or giving cpu0_hotplug kernel parameter at boot.
2265 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2266 depends on COMPAT_32
2268 Certain buggy versions of glibc will crash if they are
2269 presented with a 32-bit vDSO that is not mapped at the address
2270 indicated in its segment table.
2272 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2273 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2274 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2275 the only released version with the bug, but OpenSUSE 9
2276 contains a buggy "glibc 2.3.2".
2278 The symptom of the bug is that everything crashes on startup, saying:
2279 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2281 Saying Y here changes the default value of the vdso32 boot
2282 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2283 This works around the glibc bug but hurts performance.
2285 If unsure, say N: if you are compiling your own kernel, you
2286 are unlikely to be using a buggy version of glibc.
2289 prompt "vsyscall table for legacy applications"
2291 default LEGACY_VSYSCALL_EMULATE
2293 Legacy user code that does not know how to find the vDSO expects
2294 to be able to issue three syscalls by calling fixed addresses in
2295 kernel space. Since this location is not randomized with ASLR,
2296 it can be used to assist security vulnerability exploitation.
2298 This setting can be changed at boot time via the kernel command
2299 line parameter vsyscall=[emulate|none].
2301 On a system with recent enough glibc (2.14 or newer) and no
2302 static binaries, you can say None without a performance penalty
2303 to improve security.
2305 If unsure, select "Emulate".
2307 config LEGACY_VSYSCALL_EMULATE
2310 The kernel traps and emulates calls into the fixed
2311 vsyscall address mapping. This makes the mapping
2312 non-executable, but it still contains known contents,
2313 which could be used in certain rare security vulnerability
2314 exploits. This configuration is recommended when userspace
2315 still uses the vsyscall area.
2317 config LEGACY_VSYSCALL_NONE
2320 There will be no vsyscall mapping at all. This will
2321 eliminate any risk of ASLR bypass due to the vsyscall
2322 fixed address mapping. Attempts to use the vsyscalls
2323 will be reported to dmesg, so that either old or
2324 malicious userspace programs can be identified.
2329 bool "Built-in kernel command line"
2331 Allow for specifying boot arguments to the kernel at
2332 build time. On some systems (e.g. embedded ones), it is
2333 necessary or convenient to provide some or all of the
2334 kernel boot arguments with the kernel itself (that is,
2335 to not rely on the boot loader to provide them.)
2337 To compile command line arguments into the kernel,
2338 set this option to 'Y', then fill in the
2339 boot arguments in CONFIG_CMDLINE.
2341 Systems with fully functional boot loaders (i.e. non-embedded)
2342 should leave this option set to 'N'.
2345 string "Built-in kernel command string"
2346 depends on CMDLINE_BOOL
2349 Enter arguments here that should be compiled into the kernel
2350 image and used at boot time. If the boot loader provides a
2351 command line at boot time, it is appended to this string to
2352 form the full kernel command line, when the system boots.
2354 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2355 change this behavior.
2357 In most cases, the command line (whether built-in or provided
2358 by the boot loader) should specify the device for the root
2361 config CMDLINE_OVERRIDE
2362 bool "Built-in command line overrides boot loader arguments"
2363 depends on CMDLINE_BOOL
2365 Set this option to 'Y' to have the kernel ignore the boot loader
2366 command line, and use ONLY the built-in command line.
2368 This is used to work around broken boot loaders. This should
2369 be set to 'N' under normal conditions.
2371 config MODIFY_LDT_SYSCALL
2372 bool "Enable the LDT (local descriptor table)" if EXPERT
2375 Linux can allow user programs to install a per-process x86
2376 Local Descriptor Table (LDT) using the modify_ldt(2) system
2377 call. This is required to run 16-bit or segmented code such as
2378 DOSEMU or some Wine programs. It is also used by some very old
2379 threading libraries.
2381 Enabling this feature adds a small amount of overhead to
2382 context switches and increases the low-level kernel attack
2383 surface. Disabling it removes the modify_ldt(2) system call.
2385 Saying 'N' here may make sense for embedded or server kernels.
2387 source "kernel/livepatch/Kconfig"
2391 config ARCH_HAS_ADD_PAGES
2393 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2395 config ARCH_ENABLE_MEMORY_HOTPLUG
2397 depends on X86_64 || (X86_32 && HIGHMEM)
2399 config ARCH_ENABLE_MEMORY_HOTREMOVE
2401 depends on MEMORY_HOTPLUG
2403 config USE_PERCPU_NUMA_NODE_ID
2407 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2409 depends on X86_64 || X86_PAE
2411 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2413 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2415 config ARCH_ENABLE_THP_MIGRATION
2417 depends on X86_64 && TRANSPARENT_HUGEPAGE
2419 menu "Power management and ACPI options"
2421 config ARCH_HIBERNATION_HEADER
2423 depends on X86_64 && HIBERNATION
2425 source "kernel/power/Kconfig"
2427 source "drivers/acpi/Kconfig"
2429 source "drivers/sfi/Kconfig"
2436 tristate "APM (Advanced Power Management) BIOS support"
2437 depends on X86_32 && PM_SLEEP
2439 APM is a BIOS specification for saving power using several different
2440 techniques. This is mostly useful for battery powered laptops with
2441 APM compliant BIOSes. If you say Y here, the system time will be
2442 reset after a RESUME operation, the /proc/apm device will provide
2443 battery status information, and user-space programs will receive
2444 notification of APM "events" (e.g. battery status change).
2446 If you select "Y" here, you can disable actual use of the APM
2447 BIOS by passing the "apm=off" option to the kernel at boot time.
2449 Note that the APM support is almost completely disabled for
2450 machines with more than one CPU.
2452 In order to use APM, you will need supporting software. For location
2453 and more information, read <file:Documentation/power/apm-acpi.txt>
2454 and the Battery Powered Linux mini-HOWTO, available from
2455 <http://www.tldp.org/docs.html#howto>.
2457 This driver does not spin down disk drives (see the hdparm(8)
2458 manpage ("man 8 hdparm") for that), and it doesn't turn off
2459 VESA-compliant "green" monitors.
2461 This driver does not support the TI 4000M TravelMate and the ACER
2462 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2463 desktop machines also don't have compliant BIOSes, and this driver
2464 may cause those machines to panic during the boot phase.
2466 Generally, if you don't have a battery in your machine, there isn't
2467 much point in using this driver and you should say N. If you get
2468 random kernel OOPSes or reboots that don't seem to be related to
2469 anything, try disabling/enabling this option (or disabling/enabling
2472 Some other things you should try when experiencing seemingly random,
2475 1) make sure that you have enough swap space and that it is
2477 2) pass the "no-hlt" option to the kernel
2478 3) switch on floating point emulation in the kernel and pass
2479 the "no387" option to the kernel
2480 4) pass the "floppy=nodma" option to the kernel
2481 5) pass the "mem=4M" option to the kernel (thereby disabling
2482 all but the first 4 MB of RAM)
2483 6) make sure that the CPU is not over clocked.
2484 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2485 8) disable the cache from your BIOS settings
2486 9) install a fan for the video card or exchange video RAM
2487 10) install a better fan for the CPU
2488 11) exchange RAM chips
2489 12) exchange the motherboard.
2491 To compile this driver as a module, choose M here: the
2492 module will be called apm.
2496 config APM_IGNORE_USER_SUSPEND
2497 bool "Ignore USER SUSPEND"
2499 This option will ignore USER SUSPEND requests. On machines with a
2500 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2501 series notebooks, it is necessary to say Y because of a BIOS bug.
2503 config APM_DO_ENABLE
2504 bool "Enable PM at boot time"
2506 Enable APM features at boot time. From page 36 of the APM BIOS
2507 specification: "When disabled, the APM BIOS does not automatically
2508 power manage devices, enter the Standby State, enter the Suspend
2509 State, or take power saving steps in response to CPU Idle calls."
2510 This driver will make CPU Idle calls when Linux is idle (unless this
2511 feature is turned off -- see "Do CPU IDLE calls", below). This
2512 should always save battery power, but more complicated APM features
2513 will be dependent on your BIOS implementation. You may need to turn
2514 this option off if your computer hangs at boot time when using APM
2515 support, or if it beeps continuously instead of suspending. Turn
2516 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2517 T400CDT. This is off by default since most machines do fine without
2522 bool "Make CPU Idle calls when idle"
2524 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2525 On some machines, this can activate improved power savings, such as
2526 a slowed CPU clock rate, when the machine is idle. These idle calls
2527 are made after the idle loop has run for some length of time (e.g.,
2528 333 mS). On some machines, this will cause a hang at boot time or
2529 whenever the CPU becomes idle. (On machines with more than one CPU,
2530 this option does nothing.)
2532 config APM_DISPLAY_BLANK
2533 bool "Enable console blanking using APM"
2535 Enable console blanking using the APM. Some laptops can use this to
2536 turn off the LCD backlight when the screen blanker of the Linux
2537 virtual console blanks the screen. Note that this is only used by
2538 the virtual console screen blanker, and won't turn off the backlight
2539 when using the X Window system. This also doesn't have anything to
2540 do with your VESA-compliant power-saving monitor. Further, this
2541 option doesn't work for all laptops -- it might not turn off your
2542 backlight at all, or it might print a lot of errors to the console,
2543 especially if you are using gpm.
2545 config APM_ALLOW_INTS
2546 bool "Allow interrupts during APM BIOS calls"
2548 Normally we disable external interrupts while we are making calls to
2549 the APM BIOS as a measure to lessen the effects of a badly behaving
2550 BIOS implementation. The BIOS should reenable interrupts if it
2551 needs to. Unfortunately, some BIOSes do not -- especially those in
2552 many of the newer IBM Thinkpads. If you experience hangs when you
2553 suspend, try setting this to Y. Otherwise, say N.
2557 source "drivers/cpufreq/Kconfig"
2559 source "drivers/cpuidle/Kconfig"
2561 source "drivers/idle/Kconfig"
2566 menu "Bus options (PCI etc.)"
2572 Find out whether you have a PCI motherboard. PCI is the name of a
2573 bus system, i.e. the way the CPU talks to the other stuff inside
2574 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2575 VESA. If you have PCI, say Y, otherwise N.
2578 prompt "PCI access mode"
2579 depends on X86_32 && PCI
2582 On PCI systems, the BIOS can be used to detect the PCI devices and
2583 determine their configuration. However, some old PCI motherboards
2584 have BIOS bugs and may crash if this is done. Also, some embedded
2585 PCI-based systems don't have any BIOS at all. Linux can also try to
2586 detect the PCI hardware directly without using the BIOS.
2588 With this option, you can specify how Linux should detect the
2589 PCI devices. If you choose "BIOS", the BIOS will be used,
2590 if you choose "Direct", the BIOS won't be used, and if you
2591 choose "MMConfig", then PCI Express MMCONFIG will be used.
2592 If you choose "Any", the kernel will try MMCONFIG, then the
2593 direct access method and falls back to the BIOS if that doesn't
2594 work. If unsure, go with the default, which is "Any".
2599 config PCI_GOMMCONFIG
2616 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2618 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2621 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2624 bool "Support mmconfig PCI config space access" if X86_64
2626 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2627 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2631 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2635 depends on PCI && XEN
2642 config MMCONF_FAM10H
2644 depends on X86_64 && PCI_MMCONFIG && ACPI
2646 config PCI_CNB20LE_QUIRK
2647 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2650 Read the PCI windows out of the CNB20LE host bridge. This allows
2651 PCI hotplug to work on systems with the CNB20LE chipset which do
2654 There's no public spec for this chipset, and this functionality
2655 is known to be incomplete.
2657 You should say N unless you know you need this.
2659 source "drivers/pci/Kconfig"
2662 bool "ISA bus support on modern systems" if EXPERT
2664 Expose ISA bus device drivers and options available for selection and
2665 configuration. Enable this option if your target machine has an ISA
2666 bus. ISA is an older system, displaced by PCI and newer bus
2667 architectures -- if your target machine is modern, it probably does
2668 not have an ISA bus.
2672 # x86_64 have no ISA slots, but can have ISA-style DMA.
2674 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2677 Enables ISA-style DMA support for devices requiring such controllers.
2685 Find out whether you have ISA slots on your motherboard. ISA is the
2686 name of a bus system, i.e. the way the CPU talks to the other stuff
2687 inside your box. Other bus systems are PCI, EISA, MicroChannel
2688 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2689 newer boards don't support it. If you have ISA, say Y, otherwise N.
2695 The Extended Industry Standard Architecture (EISA) bus was
2696 developed as an open alternative to the IBM MicroChannel bus.
2698 The EISA bus provided some of the features of the IBM MicroChannel
2699 bus while maintaining backward compatibility with cards made for
2700 the older ISA bus. The EISA bus saw limited use between 1988 and
2701 1995 when it was made obsolete by the PCI bus.
2703 Say Y here if you are building a kernel for an EISA-based machine.
2707 source "drivers/eisa/Kconfig"
2710 tristate "NatSemi SCx200 support"
2712 This provides basic support for National Semiconductor's
2713 (now AMD's) Geode processors. The driver probes for the
2714 PCI-IDs of several on-chip devices, so its a good dependency
2715 for other scx200_* drivers.
2717 If compiled as a module, the driver is named scx200.
2719 config SCx200HR_TIMER
2720 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2724 This driver provides a clocksource built upon the on-chip
2725 27MHz high-resolution timer. Its also a workaround for
2726 NSC Geode SC-1100's buggy TSC, which loses time when the
2727 processor goes idle (as is done by the scheduler). The
2728 other workaround is idle=poll boot option.
2731 bool "One Laptop Per Child support"
2738 Add support for detecting the unique features of the OLPC
2742 bool "OLPC XO-1 Power Management"
2743 depends on OLPC && MFD_CS5535 && PM_SLEEP
2746 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2749 bool "OLPC XO-1 Real Time Clock"
2750 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2752 Add support for the XO-1 real time clock, which can be used as a
2753 programmable wakeup source.
2756 bool "OLPC XO-1 SCI extras"
2757 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2761 Add support for SCI-based features of the OLPC XO-1 laptop:
2762 - EC-driven system wakeups
2766 - AC adapter status updates
2767 - Battery status updates
2769 config OLPC_XO15_SCI
2770 bool "OLPC XO-1.5 SCI extras"
2771 depends on OLPC && ACPI
2774 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2775 - EC-driven system wakeups
2776 - AC adapter status updates
2777 - Battery status updates
2780 bool "PCEngines ALIX System Support (LED setup)"
2783 This option enables system support for the PCEngines ALIX.
2784 At present this just sets up LEDs for GPIO control on
2785 ALIX2/3/6 boards. However, other system specific setup should
2788 Note: You must still enable the drivers for GPIO and LED support
2789 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2791 Note: You have to set alix.force=1 for boards with Award BIOS.
2794 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2797 This option enables system support for the Soekris Engineering net5501.
2800 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2804 This option enables system support for the Traverse Technologies GEOS.
2807 bool "Technologic Systems TS-5500 platform support"
2809 select CHECK_SIGNATURE
2813 This option enables system support for the Technologic Systems TS-5500.
2819 depends on CPU_SUP_AMD && PCI
2821 source "drivers/pcmcia/Kconfig"
2824 tristate "RapidIO support"
2828 If enabled this option will include drivers and the core
2829 infrastructure code to support RapidIO interconnect devices.
2831 source "drivers/rapidio/Kconfig"
2834 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2836 Firmwares often provide initial graphics framebuffers so the BIOS,
2837 bootloader or kernel can show basic video-output during boot for
2838 user-guidance and debugging. Historically, x86 used the VESA BIOS
2839 Extensions and EFI-framebuffers for this, which are mostly limited
2841 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2842 framebuffers so the new generic system-framebuffer drivers can be
2843 used on x86. If the framebuffer is not compatible with the generic
2844 modes, it is adverticed as fallback platform framebuffer so legacy
2845 drivers like efifb, vesafb and uvesafb can pick it up.
2846 If this option is not selected, all system framebuffers are always
2847 marked as fallback platform framebuffers as usual.
2849 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2850 not be able to pick up generic system framebuffers if this option
2851 is selected. You are highly encouraged to enable simplefb as
2852 replacement if you select this option. simplefb can correctly deal
2853 with generic system framebuffers. But you should still keep vesafb
2854 and others enabled as fallback if a system framebuffer is
2855 incompatible with simplefb.
2862 menu "Binary Emulations"
2864 config IA32_EMULATION
2865 bool "IA32 Emulation"
2867 select ARCH_WANT_OLD_COMPAT_IPC
2869 select COMPAT_BINFMT_ELF
2870 select COMPAT_OLD_SIGACTION
2872 Include code to run legacy 32-bit programs under a
2873 64-bit kernel. You should likely turn this on, unless you're
2874 100% sure that you don't have any 32-bit programs left.
2877 tristate "IA32 a.out support"
2878 depends on IA32_EMULATION
2880 Support old a.out binaries in the 32bit emulation.
2883 bool "x32 ABI for 64-bit mode"
2886 Include code to run binaries for the x32 native 32-bit ABI
2887 for 64-bit processors. An x32 process gets access to the
2888 full 64-bit register file and wide data path while leaving
2889 pointers at 32 bits for smaller memory footprint.
2891 You will need a recent binutils (2.22 or later) with
2892 elf32_x86_64 support enabled to compile a kernel with this
2897 depends on IA32_EMULATION || X86_32
2899 select OLD_SIGSUSPEND3
2903 depends on IA32_EMULATION || X86_X32
2906 config COMPAT_FOR_U64_ALIGNMENT
2909 config SYSVIPC_COMPAT
2917 config HAVE_ATOMIC_IOMAP
2921 config X86_DEV_DMA_OPS
2923 depends on X86_64 || STA2X11
2925 config X86_DMA_REMAP
2929 config HAVE_GENERIC_GUP
2932 source "drivers/firmware/Kconfig"
2934 source "arch/x86/kvm/Kconfig"
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