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_JUMP_LABEL_RELATIVE
123 select HAVE_ARCH_KASAN if X86_64
124 select HAVE_ARCH_KGDB
125 select HAVE_ARCH_MMAP_RND_BITS if MMU
126 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
127 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
128 select HAVE_ARCH_PREL32_RELOCATIONS
129 select HAVE_ARCH_SECCOMP_FILTER
130 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
131 select HAVE_ARCH_TRACEHOOK
132 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
133 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
134 select HAVE_ARCH_VMAP_STACK if X86_64
135 select HAVE_ARCH_WITHIN_STACK_FRAMES
136 select HAVE_CMPXCHG_DOUBLE
137 select HAVE_CMPXCHG_LOCAL
138 select HAVE_CONTEXT_TRACKING if X86_64
139 select HAVE_COPY_THREAD_TLS
140 select HAVE_C_RECORDMCOUNT
141 select HAVE_DEBUG_KMEMLEAK
142 select HAVE_DEBUG_STACKOVERFLOW
143 select HAVE_DMA_CONTIGUOUS
144 select HAVE_DYNAMIC_FTRACE
145 select HAVE_DYNAMIC_FTRACE_WITH_REGS
147 select HAVE_EFFICIENT_UNALIGNED_ACCESS
148 select HAVE_EXIT_THREAD
149 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
150 select HAVE_FTRACE_MCOUNT_RECORD
151 select HAVE_FUNCTION_GRAPH_TRACER
152 select HAVE_FUNCTION_TRACER
153 select HAVE_GCC_PLUGINS
154 select HAVE_HW_BREAKPOINT
156 select HAVE_IOREMAP_PROT
157 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
158 select HAVE_IRQ_TIME_ACCOUNTING
159 select HAVE_KERNEL_BZIP2
160 select HAVE_KERNEL_GZIP
161 select HAVE_KERNEL_LZ4
162 select HAVE_KERNEL_LZMA
163 select HAVE_KERNEL_LZO
164 select HAVE_KERNEL_XZ
166 select HAVE_KPROBES_ON_FTRACE
167 select HAVE_FUNCTION_ERROR_INJECTION
168 select HAVE_KRETPROBES
170 select HAVE_LIVEPATCH if X86_64
172 select HAVE_MEMBLOCK_NODE_MAP
173 select HAVE_MIXED_BREAKPOINTS_REGS
174 select HAVE_MOD_ARCH_SPECIFIC
177 select HAVE_OPTPROBES
178 select HAVE_PCSPKR_PLATFORM
179 select HAVE_PERF_EVENTS
180 select HAVE_PERF_EVENTS_NMI
181 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
182 select HAVE_PERF_REGS
183 select HAVE_PERF_USER_STACK_DUMP
184 select HAVE_RCU_TABLE_FREE if PARAVIRT
185 select HAVE_RCU_TABLE_INVALIDATE if HAVE_RCU_TABLE_FREE
186 select HAVE_REGS_AND_STACK_ACCESS_API
187 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
188 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
189 select HAVE_STACK_VALIDATION if X86_64
191 select HAVE_SYSCALL_TRACEPOINTS
192 select HAVE_UNSTABLE_SCHED_CLOCK
193 select HAVE_USER_RETURN_NOTIFIER
194 select HOTPLUG_SMT if SMP
195 select IRQ_FORCED_THREADING
196 select NEED_SG_DMA_LENGTH
197 select PCI_LOCKLESS_CONFIG
200 select RTC_MC146818_LIB
203 select SYSCTL_EXCEPTION_TRACE
204 select THREAD_INFO_IN_TASK
205 select USER_STACKTRACE_SUPPORT
207 select X86_FEATURE_NAMES if PROC_FS
209 config INSTRUCTION_DECODER
211 depends on KPROBES || PERF_EVENTS || UPROBES
215 default "elf32-i386" if X86_32
216 default "elf64-x86-64" if X86_64
218 config ARCH_DEFCONFIG
220 default "arch/x86/configs/i386_defconfig" if X86_32
221 default "arch/x86/configs/x86_64_defconfig" if X86_64
223 config LOCKDEP_SUPPORT
226 config STACKTRACE_SUPPORT
232 config ARCH_MMAP_RND_BITS_MIN
236 config ARCH_MMAP_RND_BITS_MAX
240 config ARCH_MMAP_RND_COMPAT_BITS_MIN
243 config ARCH_MMAP_RND_COMPAT_BITS_MAX
249 config GENERIC_ISA_DMA
251 depends on ISA_DMA_API
256 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
258 config GENERIC_BUG_RELATIVE_POINTERS
261 config GENERIC_HWEIGHT
264 config ARCH_MAY_HAVE_PC_FDC
266 depends on ISA_DMA_API
268 config RWSEM_XCHGADD_ALGORITHM
271 config GENERIC_CALIBRATE_DELAY
274 config ARCH_HAS_CPU_RELAX
277 config ARCH_HAS_CACHE_LINE_SIZE
280 config ARCH_HAS_FILTER_PGPROT
283 config HAVE_SETUP_PER_CPU_AREA
286 config NEED_PER_CPU_EMBED_FIRST_CHUNK
289 config NEED_PER_CPU_PAGE_FIRST_CHUNK
292 config ARCH_HIBERNATION_POSSIBLE
295 config ARCH_SUSPEND_POSSIBLE
298 config ARCH_WANT_HUGE_PMD_SHARE
301 config ARCH_WANT_GENERAL_HUGETLB
310 config ARCH_SUPPORTS_OPTIMIZED_INLINING
313 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
316 config KASAN_SHADOW_OFFSET
319 default 0xdffffc0000000000
321 config HAVE_INTEL_TXT
323 depends on INTEL_IOMMU && ACPI
327 depends on X86_32 && SMP
331 depends on X86_64 && SMP
333 config X86_32_LAZY_GS
335 depends on X86_32 && !STACKPROTECTOR
337 config ARCH_SUPPORTS_UPROBES
340 config FIX_EARLYCON_MEM
343 config DYNAMIC_PHYSICAL_MASK
346 config PGTABLE_LEVELS
348 default 5 if X86_5LEVEL
353 config CC_HAS_SANE_STACKPROTECTOR
355 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
356 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
358 We have to make sure stack protector is unconditionally disabled if
359 the compiler produces broken code.
361 menu "Processor type and features"
364 bool "DMA memory allocation support" if EXPERT
367 DMA memory allocation support allows devices with less than 32-bit
368 addressing to allocate within the first 16MB of address space.
369 Disable if no such devices will be used.
374 bool "Symmetric multi-processing support"
376 This enables support for systems with more than one CPU. If you have
377 a system with only one CPU, say N. If you have a system with more
380 If you say N here, the kernel will run on uni- and multiprocessor
381 machines, but will use only one CPU of a multiprocessor machine. If
382 you say Y here, the kernel will run on many, but not all,
383 uniprocessor machines. On a uniprocessor machine, the kernel
384 will run faster if you say N here.
386 Note that if you say Y here and choose architecture "586" or
387 "Pentium" under "Processor family", the kernel will not work on 486
388 architectures. Similarly, multiprocessor kernels for the "PPro"
389 architecture may not work on all Pentium based boards.
391 People using multiprocessor machines who say Y here should also say
392 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
393 Management" code will be disabled if you say Y here.
395 See also <file:Documentation/x86/i386/IO-APIC.txt>,
396 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
397 <http://www.tldp.org/docs.html#howto>.
399 If you don't know what to do here, say N.
401 config X86_FEATURE_NAMES
402 bool "Processor feature human-readable names" if EMBEDDED
405 This option compiles in a table of x86 feature bits and corresponding
406 names. This is required to support /proc/cpuinfo and a few kernel
407 messages. You can disable this to save space, at the expense of
408 making those few kernel messages show numeric feature bits instead.
413 bool "Support x2apic"
414 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
416 This enables x2apic support on CPUs that have this feature.
418 This allows 32-bit apic IDs (so it can support very large systems),
419 and accesses the local apic via MSRs not via mmio.
421 If you don't know what to do here, say N.
424 bool "Enable MPS table" if ACPI || SFI
426 depends on X86_LOCAL_APIC
428 For old smp systems that do not have proper acpi support. Newer systems
429 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
433 depends on X86_GOLDFISH
436 bool "Avoid speculative indirect branches in kernel"
438 select STACK_VALIDATION if HAVE_STACK_VALIDATION
440 Compile kernel with the retpoline compiler options to guard against
441 kernel-to-user data leaks by avoiding speculative indirect
442 branches. Requires a compiler with -mindirect-branch=thunk-extern
443 support for full protection. The kernel may run slower.
445 Without compiler support, at least indirect branches in assembler
446 code are eliminated. Since this includes the syscall entry path,
447 it is not entirely pointless.
450 bool "Intel Resource Director Technology support"
452 depends on X86 && CPU_SUP_INTEL
455 Select to enable resource allocation and monitoring which are
456 sub-features of Intel Resource Director Technology(RDT). More
457 information about RDT can be found in the Intel x86
458 Architecture Software Developer Manual.
464 bool "Support for big SMP systems with more than 8 CPUs"
467 This option is needed for the systems that have more than 8 CPUs
469 config X86_EXTENDED_PLATFORM
470 bool "Support for extended (non-PC) x86 platforms"
473 If you disable this option then the kernel will only support
474 standard PC platforms. (which covers the vast majority of
477 If you enable this option then you'll be able to select support
478 for the following (non-PC) 32 bit x86 platforms:
479 Goldfish (Android emulator)
482 SGI 320/540 (Visual Workstation)
483 STA2X11-based (e.g. Northville)
484 Moorestown MID devices
486 If you have one of these systems, or if you want to build a
487 generic distribution kernel, say Y here - otherwise say N.
491 config X86_EXTENDED_PLATFORM
492 bool "Support for extended (non-PC) x86 platforms"
495 If you disable this option then the kernel will only support
496 standard PC platforms. (which covers the vast majority of
499 If you enable this option then you'll be able to select support
500 for the following (non-PC) 64 bit x86 platforms:
505 If you have one of these systems, or if you want to build a
506 generic distribution kernel, say Y here - otherwise say N.
508 # This is an alphabetically sorted list of 64 bit extended platforms
509 # Please maintain the alphabetic order if and when there are additions
511 bool "Numascale NumaChip"
513 depends on X86_EXTENDED_PLATFORM
516 depends on X86_X2APIC
517 depends on PCI_MMCONFIG
519 Adds support for Numascale NumaChip large-SMP systems. Needed to
520 enable more than ~168 cores.
521 If you don't have one of these, you should say N here.
525 select HYPERVISOR_GUEST
527 depends on X86_64 && PCI
528 depends on X86_EXTENDED_PLATFORM
531 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
532 supposed to run on these EM64T-based machines. Only choose this option
533 if you have one of these machines.
536 bool "SGI Ultraviolet"
538 depends on X86_EXTENDED_PLATFORM
541 depends on X86_X2APIC
544 This option is needed in order to support SGI Ultraviolet systems.
545 If you don't have one of these, you should say N here.
547 # Following is an alphabetically sorted list of 32 bit extended platforms
548 # Please maintain the alphabetic order if and when there are additions
551 bool "Goldfish (Virtual Platform)"
552 depends on X86_EXTENDED_PLATFORM
554 Enable support for the Goldfish virtual platform used primarily
555 for Android development. Unless you are building for the Android
556 Goldfish emulator say N here.
559 bool "CE4100 TV platform"
561 depends on PCI_GODIRECT
562 depends on X86_IO_APIC
564 depends on X86_EXTENDED_PLATFORM
565 select X86_REBOOTFIXUPS
567 select OF_EARLY_FLATTREE
569 Select for the Intel CE media processor (CE4100) SOC.
570 This option compiles in support for the CE4100 SOC for settop
571 boxes and media devices.
574 bool "Intel MID platform support"
575 depends on X86_EXTENDED_PLATFORM
576 depends on X86_PLATFORM_DEVICES
578 depends on X86_64 || (PCI_GOANY && X86_32)
579 depends on X86_IO_APIC
585 select MFD_INTEL_MSIC
587 Select to build a kernel capable of supporting Intel MID (Mobile
588 Internet Device) platform systems which do not have the PCI legacy
589 interfaces. If you are building for a PC class system say N here.
591 Intel MID platforms are based on an Intel processor and chipset which
592 consume less power than most of the x86 derivatives.
594 config X86_INTEL_QUARK
595 bool "Intel Quark platform support"
597 depends on X86_EXTENDED_PLATFORM
598 depends on X86_PLATFORM_DEVICES
602 depends on X86_IO_APIC
607 Select to include support for Quark X1000 SoC.
608 Say Y here if you have a Quark based system such as the Arduino
609 compatible Intel Galileo.
611 config X86_INTEL_LPSS
612 bool "Intel Low Power Subsystem Support"
613 depends on X86 && ACPI
618 Select to build support for Intel Low Power Subsystem such as
619 found on Intel Lynxpoint PCH. Selecting this option enables
620 things like clock tree (common clock framework) and pincontrol
621 which are needed by the LPSS peripheral drivers.
623 config X86_AMD_PLATFORM_DEVICE
624 bool "AMD ACPI2Platform devices support"
629 Select to interpret AMD specific ACPI device to platform device
630 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
631 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
632 implemented under PINCTRL subsystem.
635 tristate "Intel SoC IOSF Sideband support for SoC platforms"
638 This option enables sideband register access support for Intel SoC
639 platforms. On these platforms the IOSF sideband is used in lieu of
640 MSR's for some register accesses, mostly but not limited to thermal
641 and power. Drivers may query the availability of this device to
642 determine if they need the sideband in order to work on these
643 platforms. The sideband is available on the following SoC products.
644 This list is not meant to be exclusive.
649 You should say Y if you are running a kernel on one of these SoC's.
651 config IOSF_MBI_DEBUG
652 bool "Enable IOSF sideband access through debugfs"
653 depends on IOSF_MBI && DEBUG_FS
655 Select this option to expose the IOSF sideband access registers (MCR,
656 MDR, MCRX) through debugfs to write and read register information from
657 different units on the SoC. This is most useful for obtaining device
658 state information for debug and analysis. As this is a general access
659 mechanism, users of this option would have specific knowledge of the
660 device they want to access.
662 If you don't require the option or are in doubt, say N.
665 bool "RDC R-321x SoC"
667 depends on X86_EXTENDED_PLATFORM
669 select X86_REBOOTFIXUPS
671 This option is needed for RDC R-321x system-on-chip, also known
673 If you don't have one of these chips, you should say N here.
675 config X86_32_NON_STANDARD
676 bool "Support non-standard 32-bit SMP architectures"
677 depends on X86_32 && SMP
678 depends on X86_EXTENDED_PLATFORM
680 This option compiles in the bigsmp and STA2X11 default
681 subarchitectures. It is intended for a generic binary
682 kernel. If you select them all, kernel will probe it one by
683 one and will fallback to default.
685 # Alphabetically sorted list of Non standard 32 bit platforms
687 config X86_SUPPORTS_MEMORY_FAILURE
689 # MCE code calls memory_failure():
691 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
692 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
693 depends on X86_64 || !SPARSEMEM
694 select ARCH_SUPPORTS_MEMORY_FAILURE
697 bool "STA2X11 Companion Chip Support"
698 depends on X86_32_NON_STANDARD && PCI
699 select ARCH_HAS_PHYS_TO_DMA
700 select X86_DEV_DMA_OPS
707 This adds support for boards based on the STA2X11 IO-Hub,
708 a.k.a. "ConneXt". The chip is used in place of the standard
709 PC chipset, so all "standard" peripherals are missing. If this
710 option is selected the kernel will still be able to boot on
711 standard PC machines.
714 tristate "Eurobraille/Iris poweroff module"
717 The Iris machines from EuroBraille do not have APM or ACPI support
718 to shut themselves down properly. A special I/O sequence is
719 needed to do so, which is what this module does at
722 This is only for Iris machines from EuroBraille.
726 config SCHED_OMIT_FRAME_POINTER
728 prompt "Single-depth WCHAN output"
731 Calculate simpler /proc/<PID>/wchan values. If this option
732 is disabled then wchan values will recurse back to the
733 caller function. This provides more accurate wchan values,
734 at the expense of slightly more scheduling overhead.
736 If in doubt, say "Y".
738 menuconfig HYPERVISOR_GUEST
739 bool "Linux guest support"
741 Say Y here to enable options for running Linux under various hyper-
742 visors. This option enables basic hypervisor detection and platform
745 If you say N, all options in this submenu will be skipped and
746 disabled, and Linux guest support won't be built in.
751 bool "Enable paravirtualization code"
753 This changes the kernel so it can modify itself when it is run
754 under a hypervisor, potentially improving performance significantly
755 over full virtualization. However, when run without a hypervisor
756 the kernel is theoretically slower and slightly larger.
758 config PARAVIRT_DEBUG
759 bool "paravirt-ops debugging"
760 depends on PARAVIRT && DEBUG_KERNEL
762 Enable to debug paravirt_ops internals. Specifically, BUG if
763 a paravirt_op is missing when it is called.
765 config PARAVIRT_SPINLOCKS
766 bool "Paravirtualization layer for spinlocks"
767 depends on PARAVIRT && SMP
769 Paravirtualized spinlocks allow a pvops backend to replace the
770 spinlock implementation with something virtualization-friendly
771 (for example, block the virtual CPU rather than spinning).
773 It has a minimal impact on native kernels and gives a nice performance
774 benefit on paravirtualized KVM / Xen kernels.
776 If you are unsure how to answer this question, answer Y.
778 config QUEUED_LOCK_STAT
779 bool "Paravirt queued spinlock statistics"
780 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
782 Enable the collection of statistical data on the slowpath
783 behavior of paravirtualized queued spinlocks and report
786 source "arch/x86/xen/Kconfig"
789 bool "KVM Guest support (including kvmclock)"
791 select PARAVIRT_CLOCK
794 This option enables various optimizations for running under the KVM
795 hypervisor. It includes a paravirtualized clock, so that instead
796 of relying on a PIT (or probably other) emulation by the
797 underlying device model, the host provides the guest with
798 timing infrastructure such as time of day, and system time
801 bool "Enable debug information for KVM Guests in debugfs"
802 depends on KVM_GUEST && DEBUG_FS
805 This option enables collection of various statistics for KVM guest.
806 Statistics are displayed in debugfs filesystem. Enabling this option
807 may incur significant overhead.
809 config PARAVIRT_TIME_ACCOUNTING
810 bool "Paravirtual steal time accounting"
814 Select this option to enable fine granularity task steal time
815 accounting. Time spent executing other tasks in parallel with
816 the current vCPU is discounted from the vCPU power. To account for
817 that, there can be a small performance impact.
819 If in doubt, say N here.
821 config PARAVIRT_CLOCK
824 config JAILHOUSE_GUEST
825 bool "Jailhouse non-root cell support"
826 depends on X86_64 && PCI
829 This option allows to run Linux as guest in a Jailhouse non-root
830 cell. You can leave this option disabled if you only want to start
831 Jailhouse and run Linux afterwards in the root cell.
833 endif #HYPERVISOR_GUEST
838 source "arch/x86/Kconfig.cpu"
842 prompt "HPET Timer Support" if X86_32
844 Use the IA-PC HPET (High Precision Event Timer) to manage
845 time in preference to the PIT and RTC, if a HPET is
847 HPET is the next generation timer replacing legacy 8254s.
848 The HPET provides a stable time base on SMP
849 systems, unlike the TSC, but it is more expensive to access,
850 as it is off-chip. The interface used is documented
851 in the HPET spec, revision 1.
853 You can safely choose Y here. However, HPET will only be
854 activated if the platform and the BIOS support this feature.
855 Otherwise the 8254 will be used for timing services.
857 Choose N to continue using the legacy 8254 timer.
859 config HPET_EMULATE_RTC
861 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
864 def_bool y if X86_INTEL_MID
865 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
867 depends on X86_INTEL_MID && SFI
869 APB timer is the replacement for 8254, HPET on X86 MID platforms.
870 The APBT provides a stable time base on SMP
871 systems, unlike the TSC, but it is more expensive to access,
872 as it is off-chip. APB timers are always running regardless of CPU
873 C states, they are used as per CPU clockevent device when possible.
875 # Mark as expert because too many people got it wrong.
876 # The code disables itself when not needed.
879 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
880 bool "Enable DMI scanning" if EXPERT
882 Enabled scanning of DMI to identify machine quirks. Say Y
883 here unless you have verified that your setup is not
884 affected by entries in the DMI blacklist. Required by PNP
888 bool "Old AMD GART IOMMU support"
891 depends on X86_64 && PCI && AMD_NB
893 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
894 GART based hardware IOMMUs.
896 The GART supports full DMA access for devices with 32-bit access
897 limitations, on systems with more than 3 GB. This is usually needed
898 for USB, sound, many IDE/SATA chipsets and some other devices.
900 Newer systems typically have a modern AMD IOMMU, supported via
901 the CONFIG_AMD_IOMMU=y config option.
903 In normal configurations this driver is only active when needed:
904 there's more than 3 GB of memory and the system contains a
905 32-bit limited device.
910 bool "IBM Calgary IOMMU support"
913 depends on X86_64 && PCI
915 Support for hardware IOMMUs in IBM's xSeries x366 and x460
916 systems. Needed to run systems with more than 3GB of memory
917 properly with 32-bit PCI devices that do not support DAC
918 (Double Address Cycle). Calgary also supports bus level
919 isolation, where all DMAs pass through the IOMMU. This
920 prevents them from going anywhere except their intended
921 destination. This catches hard-to-find kernel bugs and
922 mis-behaving drivers and devices that do not use the DMA-API
923 properly to set up their DMA buffers. The IOMMU can be
924 turned off at boot time with the iommu=off parameter.
925 Normally the kernel will make the right choice by itself.
928 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
930 prompt "Should Calgary be enabled by default?"
931 depends on CALGARY_IOMMU
933 Should Calgary be enabled by default? if you choose 'y', Calgary
934 will be used (if it exists). If you choose 'n', Calgary will not be
935 used even if it exists. If you choose 'n' and would like to use
936 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
940 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
941 depends on X86_64 && SMP && DEBUG_KERNEL
942 select CPUMASK_OFFSTACK
944 Enable maximum number of CPUS and NUMA Nodes for this architecture.
948 # The maximum number of CPUs supported:
950 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
951 # and which can be configured interactively in the
952 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
954 # The ranges are different on 32-bit and 64-bit kernels, depending on
955 # hardware capabilities and scalability features of the kernel.
957 # ( If MAXSMP is enabled we just use the highest possible value and disable
958 # interactive configuration. )
961 config NR_CPUS_RANGE_BEGIN
963 default NR_CPUS_RANGE_END if MAXSMP
967 config NR_CPUS_RANGE_END
970 default 64 if SMP && X86_BIGSMP
971 default 8 if SMP && !X86_BIGSMP
974 config NR_CPUS_RANGE_END
977 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
978 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
981 config NR_CPUS_DEFAULT
984 default 32 if X86_BIGSMP
988 config NR_CPUS_DEFAULT
991 default 8192 if MAXSMP
996 int "Maximum number of CPUs" if SMP && !MAXSMP
997 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
998 default NR_CPUS_DEFAULT
1000 This allows you to specify the maximum number of CPUs which this
1001 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1002 supported value is 8192, otherwise the maximum value is 512. The
1003 minimum value which makes sense is 2.
1005 This is purely to save memory: each supported CPU adds about 8KB
1006 to the kernel image.
1009 bool "SMT (Hyperthreading) scheduler support"
1012 SMT scheduler support improves the CPU scheduler's decision making
1013 when dealing with Intel Pentium 4 chips with HyperThreading at a
1014 cost of slightly increased overhead in some places. If unsure say
1019 prompt "Multi-core scheduler support"
1022 Multi-core scheduler support improves the CPU scheduler's decision
1023 making when dealing with multi-core CPU chips at a cost of slightly
1024 increased overhead in some places. If unsure say N here.
1026 config SCHED_MC_PRIO
1027 bool "CPU core priorities scheduler support"
1028 depends on SCHED_MC && CPU_SUP_INTEL
1029 select X86_INTEL_PSTATE
1033 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1034 core ordering determined at manufacturing time, which allows
1035 certain cores to reach higher turbo frequencies (when running
1036 single threaded workloads) than others.
1038 Enabling this kernel feature teaches the scheduler about
1039 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1040 scheduler's CPU selection logic accordingly, so that higher
1041 overall system performance can be achieved.
1043 This feature will have no effect on CPUs without this feature.
1045 If unsure say Y here.
1049 depends on !SMP && X86_LOCAL_APIC
1052 bool "Local APIC support on uniprocessors" if !PCI_MSI
1054 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1056 A local APIC (Advanced Programmable Interrupt Controller) is an
1057 integrated interrupt controller in the CPU. If you have a single-CPU
1058 system which has a processor with a local APIC, you can say Y here to
1059 enable and use it. If you say Y here even though your machine doesn't
1060 have a local APIC, then the kernel will still run with no slowdown at
1061 all. The local APIC supports CPU-generated self-interrupts (timer,
1062 performance counters), and the NMI watchdog which detects hard
1065 config X86_UP_IOAPIC
1066 bool "IO-APIC support on uniprocessors"
1067 depends on X86_UP_APIC
1069 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1070 SMP-capable replacement for PC-style interrupt controllers. Most
1071 SMP systems and many recent uniprocessor systems have one.
1073 If you have a single-CPU system with an IO-APIC, you can say Y here
1074 to use it. If you say Y here even though your machine doesn't have
1075 an IO-APIC, then the kernel will still run with no slowdown at all.
1077 config X86_LOCAL_APIC
1079 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1080 select IRQ_DOMAIN_HIERARCHY
1081 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1085 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1087 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1088 bool "Reroute for broken boot IRQs"
1089 depends on X86_IO_APIC
1091 This option enables a workaround that fixes a source of
1092 spurious interrupts. This is recommended when threaded
1093 interrupt handling is used on systems where the generation of
1094 superfluous "boot interrupts" cannot be disabled.
1096 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1097 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1098 kernel does during interrupt handling). On chipsets where this
1099 boot IRQ generation cannot be disabled, this workaround keeps
1100 the original IRQ line masked so that only the equivalent "boot
1101 IRQ" is delivered to the CPUs. The workaround also tells the
1102 kernel to set up the IRQ handler on the boot IRQ line. In this
1103 way only one interrupt is delivered to the kernel. Otherwise
1104 the spurious second interrupt may cause the kernel to bring
1105 down (vital) interrupt lines.
1107 Only affects "broken" chipsets. Interrupt sharing may be
1108 increased on these systems.
1111 bool "Machine Check / overheating reporting"
1112 select GENERIC_ALLOCATOR
1115 Machine Check support allows the processor to notify the
1116 kernel if it detects a problem (e.g. overheating, data corruption).
1117 The action the kernel takes depends on the severity of the problem,
1118 ranging from warning messages to halting the machine.
1120 config X86_MCELOG_LEGACY
1121 bool "Support for deprecated /dev/mcelog character device"
1124 Enable support for /dev/mcelog which is needed by the old mcelog
1125 userspace logging daemon. Consider switching to the new generation
1128 config X86_MCE_INTEL
1130 prompt "Intel MCE features"
1131 depends on X86_MCE && X86_LOCAL_APIC
1133 Additional support for intel specific MCE features such as
1134 the thermal monitor.
1138 prompt "AMD MCE features"
1139 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1141 Additional support for AMD specific MCE features such as
1142 the DRAM Error Threshold.
1144 config X86_ANCIENT_MCE
1145 bool "Support for old Pentium 5 / WinChip machine checks"
1146 depends on X86_32 && X86_MCE
1148 Include support for machine check handling on old Pentium 5 or WinChip
1149 systems. These typically need to be enabled explicitly on the command
1152 config X86_MCE_THRESHOLD
1153 depends on X86_MCE_AMD || X86_MCE_INTEL
1156 config X86_MCE_INJECT
1157 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1158 tristate "Machine check injector support"
1160 Provide support for injecting machine checks for testing purposes.
1161 If you don't know what a machine check is and you don't do kernel
1162 QA it is safe to say n.
1164 config X86_THERMAL_VECTOR
1166 depends on X86_MCE_INTEL
1168 source "arch/x86/events/Kconfig"
1170 config X86_LEGACY_VM86
1171 bool "Legacy VM86 support"
1175 This option allows user programs to put the CPU into V8086
1176 mode, which is an 80286-era approximation of 16-bit real mode.
1178 Some very old versions of X and/or vbetool require this option
1179 for user mode setting. Similarly, DOSEMU will use it if
1180 available to accelerate real mode DOS programs. However, any
1181 recent version of DOSEMU, X, or vbetool should be fully
1182 functional even without kernel VM86 support, as they will all
1183 fall back to software emulation. Nevertheless, if you are using
1184 a 16-bit DOS program where 16-bit performance matters, vm86
1185 mode might be faster than emulation and you might want to
1188 Note that any app that works on a 64-bit kernel is unlikely to
1189 need this option, as 64-bit kernels don't, and can't, support
1190 V8086 mode. This option is also unrelated to 16-bit protected
1191 mode and is not needed to run most 16-bit programs under Wine.
1193 Enabling this option increases the complexity of the kernel
1194 and slows down exception handling a tiny bit.
1196 If unsure, say N here.
1200 default X86_LEGACY_VM86
1203 bool "Enable support for 16-bit segments" if EXPERT
1205 depends on MODIFY_LDT_SYSCALL
1207 This option is required by programs like Wine to run 16-bit
1208 protected mode legacy code on x86 processors. Disabling
1209 this option saves about 300 bytes on i386, or around 6K text
1210 plus 16K runtime memory on x86-64,
1214 depends on X86_16BIT && X86_32
1218 depends on X86_16BIT && X86_64
1220 config X86_VSYSCALL_EMULATION
1221 bool "Enable vsyscall emulation" if EXPERT
1225 This enables emulation of the legacy vsyscall page. Disabling
1226 it is roughly equivalent to booting with vsyscall=none, except
1227 that it will also disable the helpful warning if a program
1228 tries to use a vsyscall. With this option set to N, offending
1229 programs will just segfault, citing addresses of the form
1232 This option is required by many programs built before 2013, and
1233 care should be used even with newer programs if set to N.
1235 Disabling this option saves about 7K of kernel size and
1236 possibly 4K of additional runtime pagetable memory.
1239 tristate "Toshiba Laptop support"
1242 This adds a driver to safely access the System Management Mode of
1243 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1244 not work on models with a Phoenix BIOS. The System Management Mode
1245 is used to set the BIOS and power saving options on Toshiba portables.
1247 For information on utilities to make use of this driver see the
1248 Toshiba Linux utilities web site at:
1249 <http://www.buzzard.org.uk/toshiba/>.
1251 Say Y if you intend to run this kernel on a Toshiba portable.
1255 tristate "Dell i8k legacy laptop support"
1257 select SENSORS_DELL_SMM
1259 This option enables legacy /proc/i8k userspace interface in hwmon
1260 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1261 temperature and allows controlling fan speeds of Dell laptops via
1262 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1263 it reports also power and hotkey status. For fan speed control is
1264 needed userspace package i8kutils.
1266 Say Y if you intend to run this kernel on old Dell laptops or want to
1267 use userspace package i8kutils.
1270 config X86_REBOOTFIXUPS
1271 bool "Enable X86 board specific fixups for reboot"
1274 This enables chipset and/or board specific fixups to be done
1275 in order to get reboot to work correctly. This is only needed on
1276 some combinations of hardware and BIOS. The symptom, for which
1277 this config is intended, is when reboot ends with a stalled/hung
1280 Currently, the only fixup is for the Geode machines using
1281 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1283 Say Y if you want to enable the fixup. Currently, it's safe to
1284 enable this option even if you don't need it.
1288 bool "CPU microcode loading support"
1290 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1293 If you say Y here, you will be able to update the microcode on
1294 Intel and AMD processors. The Intel support is for the IA32 family,
1295 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1296 AMD support is for families 0x10 and later. You will obviously need
1297 the actual microcode binary data itself which is not shipped with
1300 The preferred method to load microcode from a detached initrd is described
1301 in Documentation/x86/microcode.txt. For that you need to enable
1302 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1303 initrd for microcode blobs.
1305 In addition, you can build the microcode into the kernel. For that you
1306 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1309 config MICROCODE_INTEL
1310 bool "Intel microcode loading support"
1311 depends on MICROCODE
1315 This options enables microcode patch loading support for Intel
1318 For the current Intel microcode data package go to
1319 <https://downloadcenter.intel.com> and search for
1320 'Linux Processor Microcode Data File'.
1322 config MICROCODE_AMD
1323 bool "AMD microcode loading support"
1324 depends on MICROCODE
1327 If you select this option, microcode patch loading support for AMD
1328 processors will be enabled.
1330 config MICROCODE_OLD_INTERFACE
1332 depends on MICROCODE
1335 tristate "/dev/cpu/*/msr - Model-specific register support"
1337 This device gives privileged processes access to the x86
1338 Model-Specific Registers (MSRs). It is a character device with
1339 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1340 MSR accesses are directed to a specific CPU on multi-processor
1344 tristate "/dev/cpu/*/cpuid - CPU information support"
1346 This device gives processes access to the x86 CPUID instruction to
1347 be executed on a specific processor. It is a character device
1348 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1352 prompt "High Memory Support"
1359 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1360 However, the address space of 32-bit x86 processors is only 4
1361 Gigabytes large. That means that, if you have a large amount of
1362 physical memory, not all of it can be "permanently mapped" by the
1363 kernel. The physical memory that's not permanently mapped is called
1366 If you are compiling a kernel which will never run on a machine with
1367 more than 1 Gigabyte total physical RAM, answer "off" here (default
1368 choice and suitable for most users). This will result in a "3GB/1GB"
1369 split: 3GB are mapped so that each process sees a 3GB virtual memory
1370 space and the remaining part of the 4GB virtual memory space is used
1371 by the kernel to permanently map as much physical memory as
1374 If the machine has between 1 and 4 Gigabytes physical RAM, then
1377 If more than 4 Gigabytes is used then answer "64GB" here. This
1378 selection turns Intel PAE (Physical Address Extension) mode on.
1379 PAE implements 3-level paging on IA32 processors. PAE is fully
1380 supported by Linux, PAE mode is implemented on all recent Intel
1381 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1382 then the kernel will not boot on CPUs that don't support PAE!
1384 The actual amount of total physical memory will either be
1385 auto detected or can be forced by using a kernel command line option
1386 such as "mem=256M". (Try "man bootparam" or see the documentation of
1387 your boot loader (lilo or loadlin) about how to pass options to the
1388 kernel at boot time.)
1390 If unsure, say "off".
1395 Select this if you have a 32-bit processor and between 1 and 4
1396 gigabytes of physical RAM.
1400 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1403 Select this if you have a 32-bit processor and more than 4
1404 gigabytes of physical RAM.
1409 prompt "Memory split" if EXPERT
1413 Select the desired split between kernel and user memory.
1415 If the address range available to the kernel is less than the
1416 physical memory installed, the remaining memory will be available
1417 as "high memory". Accessing high memory is a little more costly
1418 than low memory, as it needs to be mapped into the kernel first.
1419 Note that increasing the kernel address space limits the range
1420 available to user programs, making the address space there
1421 tighter. Selecting anything other than the default 3G/1G split
1422 will also likely make your kernel incompatible with binary-only
1425 If you are not absolutely sure what you are doing, leave this
1429 bool "3G/1G user/kernel split"
1430 config VMSPLIT_3G_OPT
1432 bool "3G/1G user/kernel split (for full 1G low memory)"
1434 bool "2G/2G user/kernel split"
1435 config VMSPLIT_2G_OPT
1437 bool "2G/2G user/kernel split (for full 2G low memory)"
1439 bool "1G/3G user/kernel split"
1444 default 0xB0000000 if VMSPLIT_3G_OPT
1445 default 0x80000000 if VMSPLIT_2G
1446 default 0x78000000 if VMSPLIT_2G_OPT
1447 default 0x40000000 if VMSPLIT_1G
1453 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1456 bool "PAE (Physical Address Extension) Support"
1457 depends on X86_32 && !HIGHMEM4G
1458 select PHYS_ADDR_T_64BIT
1461 PAE is required for NX support, and furthermore enables
1462 larger swapspace support for non-overcommit purposes. It
1463 has the cost of more pagetable lookup overhead, and also
1464 consumes more pagetable space per process.
1467 bool "Enable 5-level page tables support"
1468 select DYNAMIC_MEMORY_LAYOUT
1469 select SPARSEMEM_VMEMMAP
1472 5-level paging enables access to larger address space:
1473 upto 128 PiB of virtual address space and 4 PiB of
1474 physical address space.
1476 It will be supported by future Intel CPUs.
1478 A kernel with the option enabled can be booted on machines that
1479 support 4- or 5-level paging.
1481 See Documentation/x86/x86_64/5level-paging.txt for more
1486 config X86_DIRECT_GBPAGES
1488 depends on X86_64 && !DEBUG_PAGEALLOC
1490 Certain kernel features effectively disable kernel
1491 linear 1 GB mappings (even if the CPU otherwise
1492 supports them), so don't confuse the user by printing
1493 that we have them enabled.
1495 config ARCH_HAS_MEM_ENCRYPT
1498 config AMD_MEM_ENCRYPT
1499 bool "AMD Secure Memory Encryption (SME) support"
1500 depends on X86_64 && CPU_SUP_AMD
1501 select DYNAMIC_PHYSICAL_MASK
1503 Say yes to enable support for the encryption of system memory.
1504 This requires an AMD processor that supports Secure Memory
1507 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1508 bool "Activate AMD Secure Memory Encryption (SME) by default"
1510 depends on AMD_MEM_ENCRYPT
1512 Say yes to have system memory encrypted by default if running on
1513 an AMD processor that supports Secure Memory Encryption (SME).
1515 If set to Y, then the encryption of system memory can be
1516 deactivated with the mem_encrypt=off command line option.
1518 If set to N, then the encryption of system memory can be
1519 activated with the mem_encrypt=on command line option.
1521 config ARCH_USE_MEMREMAP_PROT
1523 depends on AMD_MEM_ENCRYPT
1525 # Common NUMA Features
1527 bool "Numa Memory Allocation and Scheduler Support"
1529 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1530 default y if X86_BIGSMP
1532 Enable NUMA (Non Uniform Memory Access) support.
1534 The kernel will try to allocate memory used by a CPU on the
1535 local memory controller of the CPU and add some more
1536 NUMA awareness to the kernel.
1538 For 64-bit this is recommended if the system is Intel Core i7
1539 (or later), AMD Opteron, or EM64T NUMA.
1541 For 32-bit this is only needed if you boot a 32-bit
1542 kernel on a 64-bit NUMA platform.
1544 Otherwise, you should say N.
1548 prompt "Old style AMD Opteron NUMA detection"
1549 depends on X86_64 && NUMA && PCI
1551 Enable AMD NUMA node topology detection. You should say Y here if
1552 you have a multi processor AMD system. This uses an old method to
1553 read the NUMA configuration directly from the builtin Northbridge
1554 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1555 which also takes priority if both are compiled in.
1557 config X86_64_ACPI_NUMA
1559 prompt "ACPI NUMA detection"
1560 depends on X86_64 && NUMA && ACPI && PCI
1563 Enable ACPI SRAT based node topology detection.
1565 # Some NUMA nodes have memory ranges that span
1566 # other nodes. Even though a pfn is valid and
1567 # between a node's start and end pfns, it may not
1568 # reside on that node. See memmap_init_zone()
1570 config NODES_SPAN_OTHER_NODES
1572 depends on X86_64_ACPI_NUMA
1575 bool "NUMA emulation"
1578 Enable NUMA emulation. A flat machine will be split
1579 into virtual nodes when booted with "numa=fake=N", where N is the
1580 number of nodes. This is only useful for debugging.
1583 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1585 default "10" if MAXSMP
1586 default "6" if X86_64
1588 depends on NEED_MULTIPLE_NODES
1590 Specify the maximum number of NUMA Nodes available on the target
1591 system. Increases memory reserved to accommodate various tables.
1593 config ARCH_HAVE_MEMORY_PRESENT
1595 depends on X86_32 && DISCONTIGMEM
1597 config ARCH_FLATMEM_ENABLE
1599 depends on X86_32 && !NUMA
1601 config ARCH_DISCONTIGMEM_ENABLE
1603 depends on NUMA && X86_32
1605 config ARCH_DISCONTIGMEM_DEFAULT
1607 depends on NUMA && X86_32
1609 config ARCH_SPARSEMEM_ENABLE
1611 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1612 select SPARSEMEM_STATIC if X86_32
1613 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1615 config ARCH_SPARSEMEM_DEFAULT
1619 config ARCH_SELECT_MEMORY_MODEL
1621 depends on ARCH_SPARSEMEM_ENABLE
1623 config ARCH_MEMORY_PROBE
1624 bool "Enable sysfs memory/probe interface"
1625 depends on X86_64 && MEMORY_HOTPLUG
1627 This option enables a sysfs memory/probe interface for testing.
1628 See Documentation/memory-hotplug.txt for more information.
1629 If you are unsure how to answer this question, answer N.
1631 config ARCH_PROC_KCORE_TEXT
1633 depends on X86_64 && PROC_KCORE
1635 config ILLEGAL_POINTER_VALUE
1638 default 0xdead000000000000 if X86_64
1640 config X86_PMEM_LEGACY_DEVICE
1643 config X86_PMEM_LEGACY
1644 tristate "Support non-standard NVDIMMs and ADR protected memory"
1645 depends on PHYS_ADDR_T_64BIT
1647 select X86_PMEM_LEGACY_DEVICE
1650 Treat memory marked using the non-standard e820 type of 12 as used
1651 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1652 The kernel will offer these regions to the 'pmem' driver so
1653 they can be used for persistent storage.
1658 bool "Allocate 3rd-level pagetables from highmem"
1661 The VM uses one page table entry for each page of physical memory.
1662 For systems with a lot of RAM, this can be wasteful of precious
1663 low memory. Setting this option will put user-space page table
1664 entries in high memory.
1666 config X86_CHECK_BIOS_CORRUPTION
1667 bool "Check for low memory corruption"
1669 Periodically check for memory corruption in low memory, which
1670 is suspected to be caused by BIOS. Even when enabled in the
1671 configuration, it is disabled at runtime. Enable it by
1672 setting "memory_corruption_check=1" on the kernel command
1673 line. By default it scans the low 64k of memory every 60
1674 seconds; see the memory_corruption_check_size and
1675 memory_corruption_check_period parameters in
1676 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1678 When enabled with the default parameters, this option has
1679 almost no overhead, as it reserves a relatively small amount
1680 of memory and scans it infrequently. It both detects corruption
1681 and prevents it from affecting the running system.
1683 It is, however, intended as a diagnostic tool; if repeatable
1684 BIOS-originated corruption always affects the same memory,
1685 you can use memmap= to prevent the kernel from using that
1688 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1689 bool "Set the default setting of memory_corruption_check"
1690 depends on X86_CHECK_BIOS_CORRUPTION
1693 Set whether the default state of memory_corruption_check is
1696 config X86_RESERVE_LOW
1697 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1701 Specify the amount of low memory to reserve for the BIOS.
1703 The first page contains BIOS data structures that the kernel
1704 must not use, so that page must always be reserved.
1706 By default we reserve the first 64K of physical RAM, as a
1707 number of BIOSes are known to corrupt that memory range
1708 during events such as suspend/resume or monitor cable
1709 insertion, so it must not be used by the kernel.
1711 You can set this to 4 if you are absolutely sure that you
1712 trust the BIOS to get all its memory reservations and usages
1713 right. If you know your BIOS have problems beyond the
1714 default 64K area, you can set this to 640 to avoid using the
1715 entire low memory range.
1717 If you have doubts about the BIOS (e.g. suspend/resume does
1718 not work or there's kernel crashes after certain hardware
1719 hotplug events) then you might want to enable
1720 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1721 typical corruption patterns.
1723 Leave this to the default value of 64 if you are unsure.
1725 config MATH_EMULATION
1727 depends on MODIFY_LDT_SYSCALL
1728 prompt "Math emulation" if X86_32
1730 Linux can emulate a math coprocessor (used for floating point
1731 operations) if you don't have one. 486DX and Pentium processors have
1732 a math coprocessor built in, 486SX and 386 do not, unless you added
1733 a 487DX or 387, respectively. (The messages during boot time can
1734 give you some hints here ["man dmesg"].) Everyone needs either a
1735 coprocessor or this emulation.
1737 If you don't have a math coprocessor, you need to say Y here; if you
1738 say Y here even though you have a coprocessor, the coprocessor will
1739 be used nevertheless. (This behavior can be changed with the kernel
1740 command line option "no387", which comes handy if your coprocessor
1741 is broken. Try "man bootparam" or see the documentation of your boot
1742 loader (lilo or loadlin) about how to pass options to the kernel at
1743 boot time.) This means that it is a good idea to say Y here if you
1744 intend to use this kernel on different machines.
1746 More information about the internals of the Linux math coprocessor
1747 emulation can be found in <file:arch/x86/math-emu/README>.
1749 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1750 kernel, it won't hurt.
1754 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1756 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1757 the Memory Type Range Registers (MTRRs) may be used to control
1758 processor access to memory ranges. This is most useful if you have
1759 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1760 allows bus write transfers to be combined into a larger transfer
1761 before bursting over the PCI/AGP bus. This can increase performance
1762 of image write operations 2.5 times or more. Saying Y here creates a
1763 /proc/mtrr file which may be used to manipulate your processor's
1764 MTRRs. Typically the X server should use this.
1766 This code has a reasonably generic interface so that similar
1767 control registers on other processors can be easily supported
1770 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1771 Registers (ARRs) which provide a similar functionality to MTRRs. For
1772 these, the ARRs are used to emulate the MTRRs.
1773 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1774 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1775 write-combining. All of these processors are supported by this code
1776 and it makes sense to say Y here if you have one of them.
1778 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1779 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1780 can lead to all sorts of problems, so it's good to say Y here.
1782 You can safely say Y even if your machine doesn't have MTRRs, you'll
1783 just add about 9 KB to your kernel.
1785 See <file:Documentation/x86/mtrr.txt> for more information.
1787 config MTRR_SANITIZER
1789 prompt "MTRR cleanup support"
1792 Convert MTRR layout from continuous to discrete, so X drivers can
1793 add writeback entries.
1795 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1796 The largest mtrr entry size for a continuous block can be set with
1801 config MTRR_SANITIZER_ENABLE_DEFAULT
1802 int "MTRR cleanup enable value (0-1)"
1805 depends on MTRR_SANITIZER
1807 Enable mtrr cleanup default value
1809 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1810 int "MTRR cleanup spare reg num (0-7)"
1813 depends on MTRR_SANITIZER
1815 mtrr cleanup spare entries default, it can be changed via
1816 mtrr_spare_reg_nr=N on the kernel command line.
1820 prompt "x86 PAT support" if EXPERT
1823 Use PAT attributes to setup page level cache control.
1825 PATs are the modern equivalents of MTRRs and are much more
1826 flexible than MTRRs.
1828 Say N here if you see bootup problems (boot crash, boot hang,
1829 spontaneous reboots) or a non-working video driver.
1833 config ARCH_USES_PG_UNCACHED
1839 prompt "x86 architectural random number generator" if EXPERT
1841 Enable the x86 architectural RDRAND instruction
1842 (Intel Bull Mountain technology) to generate random numbers.
1843 If supported, this is a high bandwidth, cryptographically
1844 secure hardware random number generator.
1848 prompt "Supervisor Mode Access Prevention" if EXPERT
1850 Supervisor Mode Access Prevention (SMAP) is a security
1851 feature in newer Intel processors. There is a small
1852 performance cost if this enabled and turned on; there is
1853 also a small increase in the kernel size if this is enabled.
1857 config X86_INTEL_UMIP
1859 depends on CPU_SUP_INTEL
1860 prompt "Intel User Mode Instruction Prevention" if EXPERT
1862 The User Mode Instruction Prevention (UMIP) is a security
1863 feature in newer Intel processors. If enabled, a general
1864 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1865 or STR instructions are executed in user mode. These instructions
1866 unnecessarily expose information about the hardware state.
1868 The vast majority of applications do not use these instructions.
1869 For the very few that do, software emulation is provided in
1870 specific cases in protected and virtual-8086 modes. Emulated
1873 config X86_INTEL_MPX
1874 prompt "Intel MPX (Memory Protection Extensions)"
1876 # Note: only available in 64-bit mode due to VMA flags shortage
1877 depends on CPU_SUP_INTEL && X86_64
1878 select ARCH_USES_HIGH_VMA_FLAGS
1880 MPX provides hardware features that can be used in
1881 conjunction with compiler-instrumented code to check
1882 memory references. It is designed to detect buffer
1883 overflow or underflow bugs.
1885 This option enables running applications which are
1886 instrumented or otherwise use MPX. It does not use MPX
1887 itself inside the kernel or to protect the kernel
1888 against bad memory references.
1890 Enabling this option will make the kernel larger:
1891 ~8k of kernel text and 36 bytes of data on a 64-bit
1892 defconfig. It adds a long to the 'mm_struct' which
1893 will increase the kernel memory overhead of each
1894 process and adds some branches to paths used during
1895 exec() and munmap().
1897 For details, see Documentation/x86/intel_mpx.txt
1901 config X86_INTEL_MEMORY_PROTECTION_KEYS
1902 prompt "Intel Memory Protection Keys"
1904 # Note: only available in 64-bit mode
1905 depends on CPU_SUP_INTEL && X86_64
1906 select ARCH_USES_HIGH_VMA_FLAGS
1907 select ARCH_HAS_PKEYS
1909 Memory Protection Keys provides a mechanism for enforcing
1910 page-based protections, but without requiring modification of the
1911 page tables when an application changes protection domains.
1913 For details, see Documentation/x86/protection-keys.txt
1918 bool "EFI runtime service support"
1921 select EFI_RUNTIME_WRAPPERS
1923 This enables the kernel to use EFI runtime services that are
1924 available (such as the EFI variable services).
1926 This option is only useful on systems that have EFI firmware.
1927 In addition, you should use the latest ELILO loader available
1928 at <http://elilo.sourceforge.net> in order to take advantage
1929 of EFI runtime services. However, even with this option, the
1930 resultant kernel should continue to boot on existing non-EFI
1934 bool "EFI stub support"
1935 depends on EFI && !X86_USE_3DNOW
1938 This kernel feature allows a bzImage to be loaded directly
1939 by EFI firmware without the use of a bootloader.
1941 See Documentation/efi-stub.txt for more information.
1944 bool "EFI mixed-mode support"
1945 depends on EFI_STUB && X86_64
1947 Enabling this feature allows a 64-bit kernel to be booted
1948 on a 32-bit firmware, provided that your CPU supports 64-bit
1951 Note that it is not possible to boot a mixed-mode enabled
1952 kernel via the EFI boot stub - a bootloader that supports
1953 the EFI handover protocol must be used.
1959 prompt "Enable seccomp to safely compute untrusted bytecode"
1961 This kernel feature is useful for number crunching applications
1962 that may need to compute untrusted bytecode during their
1963 execution. By using pipes or other transports made available to
1964 the process as file descriptors supporting the read/write
1965 syscalls, it's possible to isolate those applications in
1966 their own address space using seccomp. Once seccomp is
1967 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1968 and the task is only allowed to execute a few safe syscalls
1969 defined by each seccomp mode.
1971 If unsure, say Y. Only embedded should say N here.
1973 source kernel/Kconfig.hz
1976 bool "kexec system call"
1979 kexec is a system call that implements the ability to shutdown your
1980 current kernel, and to start another kernel. It is like a reboot
1981 but it is independent of the system firmware. And like a reboot
1982 you can start any kernel with it, not just Linux.
1984 The name comes from the similarity to the exec system call.
1986 It is an ongoing process to be certain the hardware in a machine
1987 is properly shutdown, so do not be surprised if this code does not
1988 initially work for you. As of this writing the exact hardware
1989 interface is strongly in flux, so no good recommendation can be
1993 bool "kexec file based system call"
1998 depends on CRYPTO_SHA256=y
2000 This is new version of kexec system call. This system call is
2001 file based and takes file descriptors as system call argument
2002 for kernel and initramfs as opposed to list of segments as
2003 accepted by previous system call.
2005 config ARCH_HAS_KEXEC_PURGATORY
2008 config KEXEC_VERIFY_SIG
2009 bool "Verify kernel signature during kexec_file_load() syscall"
2010 depends on KEXEC_FILE
2012 This option makes kernel signature verification mandatory for
2013 the kexec_file_load() syscall.
2015 In addition to that option, you need to enable signature
2016 verification for the corresponding kernel image type being
2017 loaded in order for this to work.
2019 config KEXEC_BZIMAGE_VERIFY_SIG
2020 bool "Enable bzImage signature verification support"
2021 depends on KEXEC_VERIFY_SIG
2022 depends on SIGNED_PE_FILE_VERIFICATION
2023 select SYSTEM_TRUSTED_KEYRING
2025 Enable bzImage signature verification support.
2028 bool "kernel crash dumps"
2029 depends on X86_64 || (X86_32 && HIGHMEM)
2031 Generate crash dump after being started by kexec.
2032 This should be normally only set in special crash dump kernels
2033 which are loaded in the main kernel with kexec-tools into
2034 a specially reserved region and then later executed after
2035 a crash by kdump/kexec. The crash dump kernel must be compiled
2036 to a memory address not used by the main kernel or BIOS using
2037 PHYSICAL_START, or it must be built as a relocatable image
2038 (CONFIG_RELOCATABLE=y).
2039 For more details see Documentation/kdump/kdump.txt
2043 depends on KEXEC && HIBERNATION
2045 Jump between original kernel and kexeced kernel and invoke
2046 code in physical address mode via KEXEC
2048 config PHYSICAL_START
2049 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2052 This gives the physical address where the kernel is loaded.
2054 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2055 bzImage will decompress itself to above physical address and
2056 run from there. Otherwise, bzImage will run from the address where
2057 it has been loaded by the boot loader and will ignore above physical
2060 In normal kdump cases one does not have to set/change this option
2061 as now bzImage can be compiled as a completely relocatable image
2062 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2063 address. This option is mainly useful for the folks who don't want
2064 to use a bzImage for capturing the crash dump and want to use a
2065 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2066 to be specifically compiled to run from a specific memory area
2067 (normally a reserved region) and this option comes handy.
2069 So if you are using bzImage for capturing the crash dump,
2070 leave the value here unchanged to 0x1000000 and set
2071 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2072 for capturing the crash dump change this value to start of
2073 the reserved region. In other words, it can be set based on
2074 the "X" value as specified in the "crashkernel=YM@XM"
2075 command line boot parameter passed to the panic-ed
2076 kernel. Please take a look at Documentation/kdump/kdump.txt
2077 for more details about crash dumps.
2079 Usage of bzImage for capturing the crash dump is recommended as
2080 one does not have to build two kernels. Same kernel can be used
2081 as production kernel and capture kernel. Above option should have
2082 gone away after relocatable bzImage support is introduced. But it
2083 is present because there are users out there who continue to use
2084 vmlinux for dump capture. This option should go away down the
2087 Don't change this unless you know what you are doing.
2090 bool "Build a relocatable kernel"
2093 This builds a kernel image that retains relocation information
2094 so it can be loaded someplace besides the default 1MB.
2095 The relocations tend to make the kernel binary about 10% larger,
2096 but are discarded at runtime.
2098 One use is for the kexec on panic case where the recovery kernel
2099 must live at a different physical address than the primary
2102 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2103 it has been loaded at and the compile time physical address
2104 (CONFIG_PHYSICAL_START) is used as the minimum location.
2106 config RANDOMIZE_BASE
2107 bool "Randomize the address of the kernel image (KASLR)"
2108 depends on RELOCATABLE
2111 In support of Kernel Address Space Layout Randomization (KASLR),
2112 this randomizes the physical address at which the kernel image
2113 is decompressed and the virtual address where the kernel
2114 image is mapped, as a security feature that deters exploit
2115 attempts relying on knowledge of the location of kernel
2118 On 64-bit, the kernel physical and virtual addresses are
2119 randomized separately. The physical address will be anywhere
2120 between 16MB and the top of physical memory (up to 64TB). The
2121 virtual address will be randomized from 16MB up to 1GB (9 bits
2122 of entropy). Note that this also reduces the memory space
2123 available to kernel modules from 1.5GB to 1GB.
2125 On 32-bit, the kernel physical and virtual addresses are
2126 randomized together. They will be randomized from 16MB up to
2127 512MB (8 bits of entropy).
2129 Entropy is generated using the RDRAND instruction if it is
2130 supported. If RDTSC is supported, its value is mixed into
2131 the entropy pool as well. If neither RDRAND nor RDTSC are
2132 supported, then entropy is read from the i8254 timer. The
2133 usable entropy is limited by the kernel being built using
2134 2GB addressing, and that PHYSICAL_ALIGN must be at a
2135 minimum of 2MB. As a result, only 10 bits of entropy are
2136 theoretically possible, but the implementations are further
2137 limited due to memory layouts.
2141 # Relocation on x86 needs some additional build support
2142 config X86_NEED_RELOCS
2144 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2146 config PHYSICAL_ALIGN
2147 hex "Alignment value to which kernel should be aligned"
2149 range 0x2000 0x1000000 if X86_32
2150 range 0x200000 0x1000000 if X86_64
2152 This value puts the alignment restrictions on physical address
2153 where kernel is loaded and run from. Kernel is compiled for an
2154 address which meets above alignment restriction.
2156 If bootloader loads the kernel at a non-aligned address and
2157 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2158 address aligned to above value and run from there.
2160 If bootloader loads the kernel at a non-aligned address and
2161 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2162 load address and decompress itself to the address it has been
2163 compiled for and run from there. The address for which kernel is
2164 compiled already meets above alignment restrictions. Hence the
2165 end result is that kernel runs from a physical address meeting
2166 above alignment restrictions.
2168 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2169 this value must be a multiple of 0x200000.
2171 Don't change this unless you know what you are doing.
2173 config DYNAMIC_MEMORY_LAYOUT
2176 This option makes base addresses of vmalloc and vmemmap as well as
2177 __PAGE_OFFSET movable during boot.
2179 config RANDOMIZE_MEMORY
2180 bool "Randomize the kernel memory sections"
2182 depends on RANDOMIZE_BASE
2183 select DYNAMIC_MEMORY_LAYOUT
2184 default RANDOMIZE_BASE
2186 Randomizes the base virtual address of kernel memory sections
2187 (physical memory mapping, vmalloc & vmemmap). This security feature
2188 makes exploits relying on predictable memory locations less reliable.
2190 The order of allocations remains unchanged. Entropy is generated in
2191 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2192 configuration have in average 30,000 different possible virtual
2193 addresses for each memory section.
2197 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2198 hex "Physical memory mapping padding" if EXPERT
2199 depends on RANDOMIZE_MEMORY
2200 default "0xa" if MEMORY_HOTPLUG
2202 range 0x1 0x40 if MEMORY_HOTPLUG
2205 Define the padding in terabytes added to the existing physical
2206 memory size during kernel memory randomization. It is useful
2207 for memory hotplug support but reduces the entropy available for
2208 address randomization.
2210 If unsure, leave at the default value.
2213 bool "Support for hot-pluggable CPUs"
2216 Say Y here to allow turning CPUs off and on. CPUs can be
2217 controlled through /sys/devices/system/cpu.
2218 ( Note: power management support will enable this option
2219 automatically on SMP systems. )
2220 Say N if you want to disable CPU hotplug.
2222 config BOOTPARAM_HOTPLUG_CPU0
2223 bool "Set default setting of cpu0_hotpluggable"
2225 depends on HOTPLUG_CPU
2227 Set whether default state of cpu0_hotpluggable is on or off.
2229 Say Y here to enable CPU0 hotplug by default. If this switch
2230 is turned on, there is no need to give cpu0_hotplug kernel
2231 parameter and the CPU0 hotplug feature is enabled by default.
2233 Please note: there are two known CPU0 dependencies if you want
2234 to enable the CPU0 hotplug feature either by this switch or by
2235 cpu0_hotplug kernel parameter.
2237 First, resume from hibernate or suspend always starts from CPU0.
2238 So hibernate and suspend are prevented if CPU0 is offline.
2240 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2241 offline if any interrupt can not migrate out of CPU0. There may
2242 be other CPU0 dependencies.
2244 Please make sure the dependencies are under your control before
2245 you enable this feature.
2247 Say N if you don't want to enable CPU0 hotplug feature by default.
2248 You still can enable the CPU0 hotplug feature at boot by kernel
2249 parameter cpu0_hotplug.
2251 config DEBUG_HOTPLUG_CPU0
2253 prompt "Debug CPU0 hotplug"
2254 depends on HOTPLUG_CPU
2256 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2257 soon as possible and boots up userspace with CPU0 offlined. User
2258 can online CPU0 back after boot time.
2260 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2261 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2262 compilation or giving cpu0_hotplug kernel parameter at boot.
2268 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2269 depends on COMPAT_32
2271 Certain buggy versions of glibc will crash if they are
2272 presented with a 32-bit vDSO that is not mapped at the address
2273 indicated in its segment table.
2275 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2276 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2277 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2278 the only released version with the bug, but OpenSUSE 9
2279 contains a buggy "glibc 2.3.2".
2281 The symptom of the bug is that everything crashes on startup, saying:
2282 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2284 Saying Y here changes the default value of the vdso32 boot
2285 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2286 This works around the glibc bug but hurts performance.
2288 If unsure, say N: if you are compiling your own kernel, you
2289 are unlikely to be using a buggy version of glibc.
2292 prompt "vsyscall table for legacy applications"
2294 default LEGACY_VSYSCALL_EMULATE
2296 Legacy user code that does not know how to find the vDSO expects
2297 to be able to issue three syscalls by calling fixed addresses in
2298 kernel space. Since this location is not randomized with ASLR,
2299 it can be used to assist security vulnerability exploitation.
2301 This setting can be changed at boot time via the kernel command
2302 line parameter vsyscall=[emulate|none].
2304 On a system with recent enough glibc (2.14 or newer) and no
2305 static binaries, you can say None without a performance penalty
2306 to improve security.
2308 If unsure, select "Emulate".
2310 config LEGACY_VSYSCALL_EMULATE
2313 The kernel traps and emulates calls into the fixed
2314 vsyscall address mapping. This makes the mapping
2315 non-executable, but it still contains known contents,
2316 which could be used in certain rare security vulnerability
2317 exploits. This configuration is recommended when userspace
2318 still uses the vsyscall area.
2320 config LEGACY_VSYSCALL_NONE
2323 There will be no vsyscall mapping at all. This will
2324 eliminate any risk of ASLR bypass due to the vsyscall
2325 fixed address mapping. Attempts to use the vsyscalls
2326 will be reported to dmesg, so that either old or
2327 malicious userspace programs can be identified.
2332 bool "Built-in kernel command line"
2334 Allow for specifying boot arguments to the kernel at
2335 build time. On some systems (e.g. embedded ones), it is
2336 necessary or convenient to provide some or all of the
2337 kernel boot arguments with the kernel itself (that is,
2338 to not rely on the boot loader to provide them.)
2340 To compile command line arguments into the kernel,
2341 set this option to 'Y', then fill in the
2342 boot arguments in CONFIG_CMDLINE.
2344 Systems with fully functional boot loaders (i.e. non-embedded)
2345 should leave this option set to 'N'.
2348 string "Built-in kernel command string"
2349 depends on CMDLINE_BOOL
2352 Enter arguments here that should be compiled into the kernel
2353 image and used at boot time. If the boot loader provides a
2354 command line at boot time, it is appended to this string to
2355 form the full kernel command line, when the system boots.
2357 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2358 change this behavior.
2360 In most cases, the command line (whether built-in or provided
2361 by the boot loader) should specify the device for the root
2364 config CMDLINE_OVERRIDE
2365 bool "Built-in command line overrides boot loader arguments"
2366 depends on CMDLINE_BOOL
2368 Set this option to 'Y' to have the kernel ignore the boot loader
2369 command line, and use ONLY the built-in command line.
2371 This is used to work around broken boot loaders. This should
2372 be set to 'N' under normal conditions.
2374 config MODIFY_LDT_SYSCALL
2375 bool "Enable the LDT (local descriptor table)" if EXPERT
2378 Linux can allow user programs to install a per-process x86
2379 Local Descriptor Table (LDT) using the modify_ldt(2) system
2380 call. This is required to run 16-bit or segmented code such as
2381 DOSEMU or some Wine programs. It is also used by some very old
2382 threading libraries.
2384 Enabling this feature adds a small amount of overhead to
2385 context switches and increases the low-level kernel attack
2386 surface. Disabling it removes the modify_ldt(2) system call.
2388 Saying 'N' here may make sense for embedded or server kernels.
2390 source "kernel/livepatch/Kconfig"
2394 config ARCH_HAS_ADD_PAGES
2396 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2398 config ARCH_ENABLE_MEMORY_HOTPLUG
2400 depends on X86_64 || (X86_32 && HIGHMEM)
2402 config ARCH_ENABLE_MEMORY_HOTREMOVE
2404 depends on MEMORY_HOTPLUG
2406 config USE_PERCPU_NUMA_NODE_ID
2410 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2412 depends on X86_64 || X86_PAE
2414 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2416 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2418 config ARCH_ENABLE_THP_MIGRATION
2420 depends on X86_64 && TRANSPARENT_HUGEPAGE
2422 menu "Power management and ACPI options"
2424 config ARCH_HIBERNATION_HEADER
2426 depends on HIBERNATION
2428 source "kernel/power/Kconfig"
2430 source "drivers/acpi/Kconfig"
2432 source "drivers/sfi/Kconfig"
2439 tristate "APM (Advanced Power Management) BIOS support"
2440 depends on X86_32 && PM_SLEEP
2442 APM is a BIOS specification for saving power using several different
2443 techniques. This is mostly useful for battery powered laptops with
2444 APM compliant BIOSes. If you say Y here, the system time will be
2445 reset after a RESUME operation, the /proc/apm device will provide
2446 battery status information, and user-space programs will receive
2447 notification of APM "events" (e.g. battery status change).
2449 If you select "Y" here, you can disable actual use of the APM
2450 BIOS by passing the "apm=off" option to the kernel at boot time.
2452 Note that the APM support is almost completely disabled for
2453 machines with more than one CPU.
2455 In order to use APM, you will need supporting software. For location
2456 and more information, read <file:Documentation/power/apm-acpi.txt>
2457 and the Battery Powered Linux mini-HOWTO, available from
2458 <http://www.tldp.org/docs.html#howto>.
2460 This driver does not spin down disk drives (see the hdparm(8)
2461 manpage ("man 8 hdparm") for that), and it doesn't turn off
2462 VESA-compliant "green" monitors.
2464 This driver does not support the TI 4000M TravelMate and the ACER
2465 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2466 desktop machines also don't have compliant BIOSes, and this driver
2467 may cause those machines to panic during the boot phase.
2469 Generally, if you don't have a battery in your machine, there isn't
2470 much point in using this driver and you should say N. If you get
2471 random kernel OOPSes or reboots that don't seem to be related to
2472 anything, try disabling/enabling this option (or disabling/enabling
2475 Some other things you should try when experiencing seemingly random,
2478 1) make sure that you have enough swap space and that it is
2480 2) pass the "no-hlt" option to the kernel
2481 3) switch on floating point emulation in the kernel and pass
2482 the "no387" option to the kernel
2483 4) pass the "floppy=nodma" option to the kernel
2484 5) pass the "mem=4M" option to the kernel (thereby disabling
2485 all but the first 4 MB of RAM)
2486 6) make sure that the CPU is not over clocked.
2487 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2488 8) disable the cache from your BIOS settings
2489 9) install a fan for the video card or exchange video RAM
2490 10) install a better fan for the CPU
2491 11) exchange RAM chips
2492 12) exchange the motherboard.
2494 To compile this driver as a module, choose M here: the
2495 module will be called apm.
2499 config APM_IGNORE_USER_SUSPEND
2500 bool "Ignore USER SUSPEND"
2502 This option will ignore USER SUSPEND requests. On machines with a
2503 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2504 series notebooks, it is necessary to say Y because of a BIOS bug.
2506 config APM_DO_ENABLE
2507 bool "Enable PM at boot time"
2509 Enable APM features at boot time. From page 36 of the APM BIOS
2510 specification: "When disabled, the APM BIOS does not automatically
2511 power manage devices, enter the Standby State, enter the Suspend
2512 State, or take power saving steps in response to CPU Idle calls."
2513 This driver will make CPU Idle calls when Linux is idle (unless this
2514 feature is turned off -- see "Do CPU IDLE calls", below). This
2515 should always save battery power, but more complicated APM features
2516 will be dependent on your BIOS implementation. You may need to turn
2517 this option off if your computer hangs at boot time when using APM
2518 support, or if it beeps continuously instead of suspending. Turn
2519 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2520 T400CDT. This is off by default since most machines do fine without
2525 bool "Make CPU Idle calls when idle"
2527 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2528 On some machines, this can activate improved power savings, such as
2529 a slowed CPU clock rate, when the machine is idle. These idle calls
2530 are made after the idle loop has run for some length of time (e.g.,
2531 333 mS). On some machines, this will cause a hang at boot time or
2532 whenever the CPU becomes idle. (On machines with more than one CPU,
2533 this option does nothing.)
2535 config APM_DISPLAY_BLANK
2536 bool "Enable console blanking using APM"
2538 Enable console blanking using the APM. Some laptops can use this to
2539 turn off the LCD backlight when the screen blanker of the Linux
2540 virtual console blanks the screen. Note that this is only used by
2541 the virtual console screen blanker, and won't turn off the backlight
2542 when using the X Window system. This also doesn't have anything to
2543 do with your VESA-compliant power-saving monitor. Further, this
2544 option doesn't work for all laptops -- it might not turn off your
2545 backlight at all, or it might print a lot of errors to the console,
2546 especially if you are using gpm.
2548 config APM_ALLOW_INTS
2549 bool "Allow interrupts during APM BIOS calls"
2551 Normally we disable external interrupts while we are making calls to
2552 the APM BIOS as a measure to lessen the effects of a badly behaving
2553 BIOS implementation. The BIOS should reenable interrupts if it
2554 needs to. Unfortunately, some BIOSes do not -- especially those in
2555 many of the newer IBM Thinkpads. If you experience hangs when you
2556 suspend, try setting this to Y. Otherwise, say N.
2560 source "drivers/cpufreq/Kconfig"
2562 source "drivers/cpuidle/Kconfig"
2564 source "drivers/idle/Kconfig"
2569 menu "Bus options (PCI etc.)"
2575 Find out whether you have a PCI motherboard. PCI is the name of a
2576 bus system, i.e. the way the CPU talks to the other stuff inside
2577 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2578 VESA. If you have PCI, say Y, otherwise N.
2581 prompt "PCI access mode"
2582 depends on X86_32 && PCI
2585 On PCI systems, the BIOS can be used to detect the PCI devices and
2586 determine their configuration. However, some old PCI motherboards
2587 have BIOS bugs and may crash if this is done. Also, some embedded
2588 PCI-based systems don't have any BIOS at all. Linux can also try to
2589 detect the PCI hardware directly without using the BIOS.
2591 With this option, you can specify how Linux should detect the
2592 PCI devices. If you choose "BIOS", the BIOS will be used,
2593 if you choose "Direct", the BIOS won't be used, and if you
2594 choose "MMConfig", then PCI Express MMCONFIG will be used.
2595 If you choose "Any", the kernel will try MMCONFIG, then the
2596 direct access method and falls back to the BIOS if that doesn't
2597 work. If unsure, go with the default, which is "Any".
2602 config PCI_GOMMCONFIG
2619 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2621 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2624 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2627 bool "Support mmconfig PCI config space access" if X86_64
2629 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2630 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2634 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2638 depends on PCI && XEN
2645 config MMCONF_FAM10H
2647 depends on X86_64 && PCI_MMCONFIG && ACPI
2649 config PCI_CNB20LE_QUIRK
2650 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2653 Read the PCI windows out of the CNB20LE host bridge. This allows
2654 PCI hotplug to work on systems with the CNB20LE chipset which do
2657 There's no public spec for this chipset, and this functionality
2658 is known to be incomplete.
2660 You should say N unless you know you need this.
2662 source "drivers/pci/Kconfig"
2665 bool "ISA bus support on modern systems" if EXPERT
2667 Expose ISA bus device drivers and options available for selection and
2668 configuration. Enable this option if your target machine has an ISA
2669 bus. ISA is an older system, displaced by PCI and newer bus
2670 architectures -- if your target machine is modern, it probably does
2671 not have an ISA bus.
2675 # x86_64 have no ISA slots, but can have ISA-style DMA.
2677 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2680 Enables ISA-style DMA support for devices requiring such controllers.
2688 Find out whether you have ISA slots on your motherboard. ISA is the
2689 name of a bus system, i.e. the way the CPU talks to the other stuff
2690 inside your box. Other bus systems are PCI, EISA, MicroChannel
2691 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2692 newer boards don't support it. If you have ISA, say Y, otherwise N.
2698 The Extended Industry Standard Architecture (EISA) bus was
2699 developed as an open alternative to the IBM MicroChannel bus.
2701 The EISA bus provided some of the features of the IBM MicroChannel
2702 bus while maintaining backward compatibility with cards made for
2703 the older ISA bus. The EISA bus saw limited use between 1988 and
2704 1995 when it was made obsolete by the PCI bus.
2706 Say Y here if you are building a kernel for an EISA-based machine.
2710 source "drivers/eisa/Kconfig"
2713 tristate "NatSemi SCx200 support"
2715 This provides basic support for National Semiconductor's
2716 (now AMD's) Geode processors. The driver probes for the
2717 PCI-IDs of several on-chip devices, so its a good dependency
2718 for other scx200_* drivers.
2720 If compiled as a module, the driver is named scx200.
2722 config SCx200HR_TIMER
2723 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2727 This driver provides a clocksource built upon the on-chip
2728 27MHz high-resolution timer. Its also a workaround for
2729 NSC Geode SC-1100's buggy TSC, which loses time when the
2730 processor goes idle (as is done by the scheduler). The
2731 other workaround is idle=poll boot option.
2734 bool "One Laptop Per Child support"
2741 Add support for detecting the unique features of the OLPC
2745 bool "OLPC XO-1 Power Management"
2746 depends on OLPC && MFD_CS5535 && PM_SLEEP
2749 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2752 bool "OLPC XO-1 Real Time Clock"
2753 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2755 Add support for the XO-1 real time clock, which can be used as a
2756 programmable wakeup source.
2759 bool "OLPC XO-1 SCI extras"
2760 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2764 Add support for SCI-based features of the OLPC XO-1 laptop:
2765 - EC-driven system wakeups
2769 - AC adapter status updates
2770 - Battery status updates
2772 config OLPC_XO15_SCI
2773 bool "OLPC XO-1.5 SCI extras"
2774 depends on OLPC && ACPI
2777 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2778 - EC-driven system wakeups
2779 - AC adapter status updates
2780 - Battery status updates
2783 bool "PCEngines ALIX System Support (LED setup)"
2786 This option enables system support for the PCEngines ALIX.
2787 At present this just sets up LEDs for GPIO control on
2788 ALIX2/3/6 boards. However, other system specific setup should
2791 Note: You must still enable the drivers for GPIO and LED support
2792 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2794 Note: You have to set alix.force=1 for boards with Award BIOS.
2797 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2800 This option enables system support for the Soekris Engineering net5501.
2803 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2807 This option enables system support for the Traverse Technologies GEOS.
2810 bool "Technologic Systems TS-5500 platform support"
2812 select CHECK_SIGNATURE
2816 This option enables system support for the Technologic Systems TS-5500.
2822 depends on CPU_SUP_AMD && PCI
2824 source "drivers/pcmcia/Kconfig"
2827 tristate "RapidIO support"
2831 If enabled this option will include drivers and the core
2832 infrastructure code to support RapidIO interconnect devices.
2834 source "drivers/rapidio/Kconfig"
2837 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2839 Firmwares often provide initial graphics framebuffers so the BIOS,
2840 bootloader or kernel can show basic video-output during boot for
2841 user-guidance and debugging. Historically, x86 used the VESA BIOS
2842 Extensions and EFI-framebuffers for this, which are mostly limited
2844 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2845 framebuffers so the new generic system-framebuffer drivers can be
2846 used on x86. If the framebuffer is not compatible with the generic
2847 modes, it is advertised as fallback platform framebuffer so legacy
2848 drivers like efifb, vesafb and uvesafb can pick it up.
2849 If this option is not selected, all system framebuffers are always
2850 marked as fallback platform framebuffers as usual.
2852 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2853 not be able to pick up generic system framebuffers if this option
2854 is selected. You are highly encouraged to enable simplefb as
2855 replacement if you select this option. simplefb can correctly deal
2856 with generic system framebuffers. But you should still keep vesafb
2857 and others enabled as fallback if a system framebuffer is
2858 incompatible with simplefb.
2865 menu "Binary Emulations"
2867 config IA32_EMULATION
2868 bool "IA32 Emulation"
2870 select ARCH_WANT_OLD_COMPAT_IPC
2872 select COMPAT_BINFMT_ELF
2873 select COMPAT_OLD_SIGACTION
2875 Include code to run legacy 32-bit programs under a
2876 64-bit kernel. You should likely turn this on, unless you're
2877 100% sure that you don't have any 32-bit programs left.
2880 tristate "IA32 a.out support"
2881 depends on IA32_EMULATION
2883 Support old a.out binaries in the 32bit emulation.
2886 bool "x32 ABI for 64-bit mode"
2889 Include code to run binaries for the x32 native 32-bit ABI
2890 for 64-bit processors. An x32 process gets access to the
2891 full 64-bit register file and wide data path while leaving
2892 pointers at 32 bits for smaller memory footprint.
2894 You will need a recent binutils (2.22 or later) with
2895 elf32_x86_64 support enabled to compile a kernel with this
2900 depends on IA32_EMULATION || X86_32
2902 select OLD_SIGSUSPEND3
2906 depends on IA32_EMULATION || X86_X32
2909 config COMPAT_FOR_U64_ALIGNMENT
2912 config SYSVIPC_COMPAT
2920 config HAVE_ATOMIC_IOMAP
2924 config X86_DEV_DMA_OPS
2926 depends on X86_64 || STA2X11
2928 config X86_DMA_REMAP
2932 config HAVE_GENERIC_GUP
2935 source "drivers/firmware/Kconfig"
2937 source "arch/x86/kvm/Kconfig"
git.samba.org / sfrench / cifs-2.6.git / blob